04/03/2023 City Council Regular Agenda PacketApril 3, 2023 | 6:00 PM Page 1 of 7 City Council
Regular Meeting Agenda
CITY COUNCIL
AGENDA PACKET
CITY COUNCIL CHAMBERS, CITY HALL
7351 ROSANNA STREET, GILROY, CA
95020
REGULAR MEETING | 6:00 PM
MONDAY, APRIL 3, 2023
MAYOR
Marie Blankley
COUNCIL MEMBERS
Rebeca Armendariz
Dion Bracco
Tom Cline
Zach Hilton
Carol Marques
Fred Tovar
CITY COUNCIL PACKET MATERIALS ARE AVAILABLE ONLINE AT www.cityofgilroy.org
AGENDA CLOSING TIME IS 5:00 P.M. THE TUESDAY PRIOR TO THE MEETING
Due to COVID-19, it is possible that the planned in-person meeting may have to change to a virtual meeting at any
time and possibly on short notice. Please check the City of Gilroy website www.cityofgilroy.org for any updates to
meeting information.
COMMENTS BY THE PUBLIC WILL BE TAKEN ON AGENDA ITEMS BEFORE ACTION IS TAKEN BY THE CITY
COUNCIL. Public testimony is subject to reasonable regulations, including but not limited to time restrictions for
each individual speaker. Please limit your comments to 3 minutes. The amount of time allowed per speaker may
vary at the Mayor’s discretion depending on the number of speakers and length of the agenda.
Written comments on any agenda item may be emailed to the City Clerk’s Office at cityclerk@cityofgilroy.org or mailed
to the Gilroy City Clerk’s Office at City Hall, 7351 Rosanna Street, Gilroy, CA 95020. Comments received by the City
Clerk’s Office by 1 p.m. on the day of a Council meeting will be distributed to the City Council prior to or at the
meeting and available for public inspection with the agenda packet located in the lobby of Administration at City
Hall, 7351 Rosanna Street prior to the meeting. Any correspondence received will be incorporated into the meeting
record. Items received after the 1 p.m. deadline will be provided to the City Council as soon as practicable. Written
comments are also available on the City’s Public Records Portal at bit.ly/3NuS1IN.
In compliance with the Americans with Disabilities Act, the City will make reasonable
arrangements to ensure accessibility to this meeting. If you need special assistance
to participate in this meeting, please contact the City Clerk’s Office at least 72 hours
prior to the meeting at (408) 846-0204 or cityclerk@cityofgilroy.org to help ensure that
reasonable arrangements can be made.
If you challenge any planning or land use decision made at this meeting in court, you may be limited to raising only
those issues you or someone else raised at the public hearing held at this meeting, or in written correspondence
delivered to the City Council at, or prior to, the public hearing. Please take notice that the time within which to seek
judicial review of any final administrative determination reached at this meeting is governed by Section 1094.6 of
the California Code of Civil Procedure.
A Closed Session may be called during this meeting pursuant to Government Code Section 54956.9 (d)(2) if a point
has been reached where, in the opinion of the legislative body of the City on the advice of its legal counsel, based
on existing facts and circumstances, there is a significant exposure to litigation against the City.
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Regular Meeting Agenda
Materials related to an item on this agenda submitted to the City Council after distribution of the agenda packet are
available with the agenda packet on the City website at www.cityofgilroy.org subject to the Staff’s ability to post
the documents before the meeting.
KNOW YOUR RIGHTS UNDER THE GILROY OPEN GOVERNMENT ORDINANCE
Government's duty is to serve the public, reaching its decisions in full view of the public.
Commissions, task forces, councils and other agencies of the City exist to conduct the people's
business. This ordinance assures that deliberations are conducted before the people and that
City operations are open to the people's review.
FOR MORE INFORMATION ON YOUR RIGHTS UNDER THE OPEN GOVERNMENT ORDINANCE, TO
RECEIVE A FREE COPY OF THE ORDINANCE OR TO REPORT A VIOLATION OF THE ORDINANCE,
CONTACT THE OPEN GOVERNMENT COMMISSION STAFF AT (408) 846-0204.
If you need assistance with translation and would like to speak during public comment, please
contact the City Clerk a minimum of 72 hours prior to the meeting at 408-846-0204 or e-mail the
City Clerk’s Office at cityclerk@cityofgilroy.org.
Si necesita un intérprete durante la junta y gustaría dar un comentario público, comuníquese con el Secretario de la
Ciudad un mínimo de 72 horas antes de la junta al 408-846-0204 o envíe un correo electrónico a la Oficina del
Secretario de la Ciudad a cityclerk@cityofgilroy.org.
To access written translation during the meeting, please scan the QR Code or
click this link:
Para acceder a la traducción durante la reunión, por favor escanee el código QR
o haga clic en el enlace:
bit.ly/3FBiGA0
Choose Language and Click Attend | Seleccione su lenguaje y haga clic en asistir
Use a headset on your phone for audio or read the transcript on your device.
Use sus auriculares para escuchar el audio o leer la transcripción en el
dispositivo.
The agenda for this regular meeting is as follows:
1. OPENING
1.1. Call to Order
1.2. Pledge of Allegiance
1.3. Invocation
1.4. City Clerk's Report on Posting the Agenda
1.5. Roll Call
1.6. Orders of the Day
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Regular Meeting Agenda
1.7. Employee Introductions
2. CEREMONIAL ITEMS - Proclamations and Awards
3. PRESENTATIONS TO THE COUNCIL
3.1. Annual Presentation from Visit Gilroy/California Welcome Center
3.2. PUBLIC COMMENT BY MEMBERS OF THE PUBLIC ON ITEMS NOT ON THE
AGENDA BUT WITHIN THE SUBJECT MATTER JURISDICTION OF THE
CITY COUNCIL
This portion of the meeting is reserved for persons desiring to address the Council on
matters within the Gilroy City Council’s jurisdiction but not on the agenda. Persons
wishing to address the Council are requested to complete a Speaker’s Card located at the
entrances and handed to the City Clerk. Speakers are limited to 1 to 3 minutes each,
varying at the Mayor’s discretion depending on the number of speakers and length of the
agenda. The law does not permit Council action or extended discussion of any item not
on the agenda except under special circumstances. If Council action is requested, the
Council may place the matter on a future agenda.
Written comments to address the Council on matters not on this agenda may be e-mailed
to the City Clerk’s Office at cityclerk@cityofgilroy.org or mailed to the Gilroy City Clerk’s
Office at City Hall, 7351 Rosanna Street, Gilroy, CA 95020. Comments received by the City
Clerk’s Office by 1:00pm on the day of a Council meeting will be distributed to the City
Council prior to or at the meeting and available for public inspection with the agenda
packet located in the lobby of Administration at City Hall, 7351 Rosanna Street, prior to
the meeting. Any correspondence received will be incorporated into the meeting record.
Items received after the 1:00pm deadline will be provided to the City Council as soon as
practicable. Written material provided by public members under this section of the agenda
will be limited to 10 pages in hard copy. An unlimited amount of material may be provided
electronically.
4. REPORTS OF COUNCIL MEMBERS
Council Member Bracco – Cities Association Santa Clara County Board of Directors
(alternate), Santa Clara County Library Joint Powers Authority, Santa Clara Valley Water
Commission, Santa Clara Valley Water Joint Water Resources Commission, SCRWA
Council Member Armendariz – Santa Clara County Library Joint Powers Authority, Santa
Clara Valley Habitat Agency Governing Board, Santa Clara Valley Habitat Agency
Implementation Board, Silicon Valley Clean Energy Authority JPA Board (alternate), South
County United for Health
Council Member Marques – ABAG, Gilroy Gardens Board of Directors, Santa Clara Valley
Habitat Agency Governing Board, Santa Clara Valley Habitat Agency Implementation
Board, SCRWA (alternate)
Council Member Hilton – CalTrain Policy Group (alternate), Silicon Valley Clean Energy
Authority JPA Board, South County United for Health (alternate), VTA Policy Advisory
Committee
Council Member Cline – Gilroy Economic Development Partnership (alternate), Gilroy
Sister Cities Association, Gilroy Youth Task Force, Silicon Valley Regional Interoperability
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Regular Meeting Agenda
Authority Board, VTA Policy Advisory Committee (alternate), Visit Gilroy California Welcome
Center Board
Council Member Tovar – Gilroy Youth Task Force (alternate), Santa Clara County
Expressway Plan 2040 Advisory Board, Santa Clara Valley Water Commission, SCRWA,
South County Youth Task Force Policy Team, VTA Mobility Partnership
Mayor Blankley – ABAG (alternate), CalTrain Policy Group, Cities Association Santa Clara
County Board of Directors, Gilroy Economic Development Partnership, Gilroy Sister Cities
Association (alternate), Gilroy Youth Task Force, Santa Clara Valley Water Joint Water
Resources Commission, SCRWA, South County Youth Task Force Policy Team, VTA
Board of Directors, VTA Mobility Partnership 5. COUNCIL CORRESPONDENCE
5.1. Letter of Support – California High Speed Rail Authority Application for
Federal-State Partnership for Intercity Passenger Rail Program Grant
6. FUTURE COUNCIL INITIATED AGENDA ITEMS
7. CONSENT CALENDAR
All matters listed under the Consent Calendar are considered by the City Council to be routine and will
be enacted by one motion. There will be no separate discussion of these items unless a request is
made by a member of the City Council or a member of the public. Any person desiring to speak on any
item on the consent calendar should ask to have that item removed from the consent calendar prior to
the time the Council votes to approve. If removed, the item will be discussed in the order in which it
appears.
7.1. Approval of the Action Minutes of the March 20, 2023 City Council Regular
Meeting
7.2. Resolution of The City Council of The City of Gilroy Proclaiming April 2023
as Arts, Culture, and Creativity Month
7.3. Approval of the Updated Purchasing Policy Inclusive of Wage Theft Policy
Statement
7.4. Approval of the Gilroy Tourism Business Improvement District (GTBID)
Annual Report as Submitted by Visit Gilroy/California Welcome Center
Gilroy for the Period of January 1, 2022 Through December 31, 2022
8. BIDS AND PROPOSALS (NONE)
9. PUBLIC HEARINGS
9.1. Adopt the 2022 Sewer System Master Plan
1. Staff Report: Daryl Jordan, Public Works Director
2. Open Public Hearing
3. Close Public Hearing
4. Possible Action:
Approve a resolution to adopt the 2022 Sewer System Master Plan.
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9.2. Adopt the 2022 Water Master Plan
1. Staff Report: Daryl Jordan, Public Works Director
2. Open Public Hearing
3. Close Public Hearing
4. Possible Action:
Adopt a resolution approving the 2022 Water System Master Plan. 9.3. Adopt the 2022 Storm Drainage System Master Plan
1. Staff Report: Daryl Jordan, Public Works Director
2. Open Public Hearing
3. Close Public Hearing
4. Possible Action:
Approve a resolution to adopt the 2022 Storm Drainage System Master Plan. 10. UNFINISHED BUSINESS
10.1. Appointment to City Boards, Commissions, and Committees with Open
Vacancies
1. Staff Report: Thai Nam Pham, City Clerk
2. Public Comment
3. Possible Action:
Appoint members to Boards, Commissions, and Committees with open
vacancies. 11. INTRODUCTION OF NEW BUSINESS
11.1. Enhancing the Access to the Internet and Technology for Gilroy’s Youth
1. Staff Report: Bryce Atkins, Assistant to the City Administrator
2. Public Comment
3. Possible Action:
Council provide direction.
11.2. Consideration of Creating a Job Protection Policy
1. Staff Report: Bryce Atkins, Assistant to the City Administrator
2. Public Comment
3. Possible Action:
Council provide direction.
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Regular Meeting Agenda
11.3. Review and Approve an Extension to the Memorandum of Understanding
and Related Salary Schedules for the Gilroy Police Officers Association for
the Period Ending June 30, 2025
1. Staff Report: LeeAnn McPhillips, Administrative Services and Human
Resources Director / Risk Manager
2. Public Comment
3. Possible Action:
1. Approve the Extension and Supplemental Agreement to the Memorandum
of Understanding with the Gilroy Police Officers Association for the Period
Ending June 30, 2025.
2. Adopt by Resolution the Salary Schedules Associated with the Gilroy
Police Officers Association Memorandum of Understanding/Supplemental
Agreement for the Period July 1, 2023 - June 30, 2025. 11.4. Updates to Employment Agreement for City Administrator Jimmy Forbis
1. Staff Report: Marie Blankley, Mayor
2. Public Comment
3. Possible Action:
Approve updates to City Administrator’s Employment Agreement effective
April 3, 2023 and authorize the Mayor to sign the Employment Agreement on
behalf of the City/City Council. 11.5. Report on Potential Temporary/Emergency Housing at Gilroy Transit
Center
1. Staff Report: Jimmy Forbis, City Administrator
2. Public Comment
3. Possible Action:
Receive report. 12. CITY ADMINISTRATOR'S REPORTS
13. CITY ATTORNEY'S REPORTS
14. ADJOURNMENT
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Regular Meeting Agenda
FUTURE MEETING DATES
April 2023
17 Regular Meeting - 6:00 p.m
May 2023
1 Regular Meeting - 6:00 p.m
3 Capital Improvement Plan Workshop - 6:00 p.m – 8:00 p.m.
15 Regular Meeting - 6:00 p.m
22 Recommend Operating Budget Workshop - 6:00 p.m – 8:00 p.m.
June 2023
5 Regular Meeting - 6:00 p.m
19 Regular Meeting - 6:00 p.m
Meetings are webstreamed on the City of Gilroy’s website at gilroy.city/meetings.
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April 17, 2023
The Honorable Pete Buttigieg, Secretary
U.S. Department of Transportation
1200 New Jersey Avenue, SE
Washington, DC 20590
RE: Support for California High-Speed Rail Authority Applications for Federal-State Partnership
for Intercity Passenger Rail Program (FSP-National) Grant Funding for Fiscal Years 2022 and
2023
Dear Secretary Buttigieg:
On behalf of name of organization, we are/I am pleased to express support for the application
submitted by the California High-Speed Rail Authority (Authority) for funding from the Federal-
State Partnership for Intercity Passenger Rail Grant Program for projects outside the Northeast
Corridor (FSP-National).
The Authority’s first application for the California Inaugural High-Speed Service (Project) is
to fund early elements of a two-track, electrified high-speed passenger rail line of up to 171 miles
connecting the cities of Merced, Fresno and Bakersfield.
The Authority is requesting about $2.8 billion from the FSP-National Program for fiscal years
2002 and 2023 (to be combined with about $706 million of state Cap-and-Trade funds) for a
total Project cost of about $3.5 billion. These federal funds are needed to support areas of
critical need in advancing the State’s first intercity passenger service operating at high speeds.
Project details are below:
•Procure six electric trains for testing and use for passenger service at speeds up to 220 mph;
•Construct the second track on the 119-mile high-speed Central Valley Segment (CVS)
currently under construction from Madera to Poplar Avenue;
•Construct the Fresno Station; and
•Complete final design and early works including right-of-way acquisition on the following two
extensions beyond the current 119-mile CVS:
▪Merced Extension – from Madera to Merced – about 34 miles; and
▪Bakersfield Extension – from Poplar Avenue in Shafter to Bakersfield – about 18 miles
With the above work, the 119-mile Central Valley Segment would be completed, with trains and track
and system elements tested and certified. This segment would be ready to demonstrate high-speed
passenger operations. This requested funding will improve the health, safety, access,
connectivity, and economic vitality of underserved communities in California’s Central Valley.
This Project is a key part of the State’s rail modernization plan, linking key regional passenger
rail systems and completing a vital milestone toward the future Phase 1 High-Speed Rail
Corridor from San Francisco to Los Angeles and Anaheim, of which the Project is a critical
component. The projected ridership for the California Phase 1 Corridor would make it the most
traveled intercity passenger service in the nation.
The Authority’s second application for the California Phase 1 Corridor Configuration Design
(Design Project) is to fund configuration-level design (to 30 percent) for two critical high-speed rail
program sections – San José to Merced and Bakersfield to Palmdale. These vital program sections
Agenda Item 5.1
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The Honorable Pete Buttigieg, Secretary
U.S. Department of Transportation
April 12, 2023
Page 2
have completed environmental reviews, and both entail time-consuming and complex tunneling
design challenges. They will require extensive geotechnical studies, critical to support the design of
the long-lead-time tunnel sections through the Pacheco Pass and the Tehachapi Mountains that will
be required to connect the major regions of the State.
The requested federal grant funds of $193.6 million from the FSP-National Program for fiscal years
2022 and 2023 are proposed to be matched by state Cap-and-Trade funds of $48.4 million.
The Authority’s FSP-National Program grant applications are part of an on-going federal-state
partnership that, to-date, has provided approximately $25.2 billion in funding for California High-
Speed Rail: $21.7 billion (or 85%) from state funds and $3.5 billion (or 15%) from federal funds.
California is the only state in the country to have committed this level of funding and
advanced electrified, 220 mph high-speed rail this far.
This historic state-federal partnership also has resulted in significant job and economic
opportunities including:
•Creating 10,000 construction jobs since the start of high-speed rail construction (as of
February 2023), with most of these jobs going to Central Valley residents and men and
women from disadvantaged communities;
•Employing 761 small, disadvantaged, and disabled veteran businesses through December
2022; and
•Generating up to 80,000 job-years of employment, yielding nearly $6.0 billion in labor
income and $16.0 billion in total economic output across the State from 2006 through
fiscal year 2021-22
These improvements are a part of California’s strategic transportation network investment to
address climate concerns and to relieve existing highway and rail capacity constraints. They will
achieve both state and federal goals to improve safety, expand economic strength and global
competitiveness, address equity issues, and implement sustainability practices to confront climate
change. These investments will continue to support living wage jobs, provide small business
opportunities, and equitably enhance the mobility of communities in need – including
disadvantaged agricultural communities – all while reducing greenhouse gas emissions. The
scope, scale and momentum of the California High-Speed Rail Program is unmatched in the United
States.
Please consider the enormous value that funding California High-Speed Rail will provide. With
work well underway throughout the State, we/I urge you to award funds to further advance the
California High-Speed Rail project by supporting the Authority’s continued progress towards
completing construction of the Inaugural High-Speed Service between Merced – Fresno –
Bakersfield and advancing critical geotechnical studies and configuration-level design needed to
complete the California Phase 1 Corridor.
Sincerely,
Agenda Item 5.1
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City of Gilroy
City Council Regular Meeting Minutes
Monday, March 20, 2023 | 6:00 PM
1.OPENING
1.1.Call to Order
The meeting was called to order by Mayor Blankley at 6:00 PM.
1.2.Pledge of Allegiance
Council Member Armendariz led the Pledge of Allegiance.
1.3.Invocation
Trevor Van Laar from Gilroy Presbyterian Church provided the Invocation.
1.4.City Clerk's Report on Posting the Agenda
City Clerk Pham reported on the Posting of the Agenda.
1.5.Roll Call
Attendance Attendee Name
Present Rebeca Armendariz, Council Member
Dion Bracco, Mayor Pro Tempore
Tom Cline, Council Member
Zach Hilton, Council Member
Carol Marques, Council Member
Fred Tovar, Council Member
Marie Blankley, Mayor
Absent None
1.6.Orders of the Day
There were none.
1.7.Employee Introductions
Community Development Director Goei introduced Rens Boorsma, Building
Inspector.
2.CEREMONIAL ITEMS - Proclamations and Awards
2.1.Proclamation – Proclaiming April 2023 as Fair Housing Month
Mayor Blankley read aloud the proclamation and presented it to Ana Andrade
from Project Sentinel Fair Housing.
3.PRESENTATIONS TO THE COUNCIL
3.1.PUBLIC COMMENT BY MEMBERS OF THE PUBLIC ON ITEMS NOT ON THE
AGENDA BUT WITHIN THE SUBJECT MATTER JURISDICTION OF THE
CITY COUNCIL
Mayor Blankley opened Public Comment.
The following speakers spoke on items that were not on the agenda.
Alan Espinoza thanked Council for assisting with his issue.
Agenda Item 7.1
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There being no further speakers, Mayor Blankley closed Public Comment.
4.REPORTS OF COUNCIL MEMBERS
Council Member Bracco thanked the lineman who worked during the storms.
Council Member Armendariz reported on Santa Clara Valley Habitat Agency Governing
Board.
Council Member Marques had nothing to report.
Council Member Hilton reported on Silicon Valley Clean Energy Authority JPA Board.
Council Member Cline had nothing to report.
Council Member Tovar reported on South County Youth Task Force Policy Team.
Mayor Blankley reported on South County Youth Task Force Policy Team. The mayor gave
an update on the parking lot ribbon-cutting ceremony has been postponed to March 28,
2023, at 4 PM. She also announced that the State of the City event will be held Saturday,
April 1, 2023, and encouraged members of the public to attend.
5.COUNCIL CORRESPONDENCE
5.1.Letter of Support for SB 48 (Behavioral Health) and SB 363 (Mental
Health/Substance Abuse Facilities)
Mayor Blankley asked Council if they would like to sign off on the letter. Her
request received majority support.
6.FUTURE COUNCIL INITIATED AGENDA ITEMS
There were none.
7.BOARD AND COMMISSION INTERVIEWS
7.1.Interviews for Open Seats on Boards, Commissions, and Committees with
Terms Expired or Vacant as of March 20, 2023, for Future Appointment
Scheduled for April 3, 2023
Council accepted applicant Terrence Fugazzi’s application which was received
after the March 10, 2023 application deadline.
Council interviewed applicants Vincent Saso and Terrence Fugazzi for the Parks
and Recreation Commission seats expiring December 31, 2023, and December
31, 2025.
8.CONSENT CALENDAR
Mayor Blankley opened Public Comment. There being no speakers, Mayor Blankley closed
Public Comment.
Motion: Approve the Consent Calendar
RESULT:Pass
MOVER:Fred Tovar, Council Member
SECONDER:Rebeca Armendariz, Council Member
AYES:Council Member Armendariz, Mayor Pro Tempore Bracco, Council
Member Cline, Council Member Hilton, Council Member Marques,
Council Member Tovar, Mayor Blankley
Agenda Item 7.1
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Regular Meeting Minutes
8.1.Approval of the Action Minutes of the March 6, 2023 City Council Regular
Meeting
A motion was made to approve the minutes.
8.2.Approval of the Action Minutes of the March 13, 2023 City Council Goal /
Priority Setting Workshop
A motion was made to approve the minutes.
8.3.Acceptance of the City Fiscal Year 2021-22 Federal Single Audit
A motion was made to accept the Fiscal Year 2021-22 Federal Single Audit
report.
8.4.Accept and File Quarterly Cash and Investment Report as of December 31,
2022
A motion was made to accept and file quarterly cash and investment report as of
December 31, 2022.
8.5.Approval of Parcel Map and Property Improvement Agreement No. 2023-01
for Plaza Allium (Evergreen) 10th & Chestnut Commercial Development,
APN’s 841-66-036, 037, 038, 039
A motion was made to approve the Parcel Map and Property Improvement
Agreement No. 2023-01 for Plaza Allium (Evergreen) 10th & Chestnut
Commercial Development.
8.6.Award of Contract to Kimley-Horn for the Update of the Traffic Circulation
Master Plan and Transportation Impact Fee Program in the Amount of
$360,590 with a 10% Contingency for a Total of $396,649
A motion was made to award the contract and adopt the budget amendment
resolution.
Enactment No.: Resolution No. 2023-13.
8.7.Award a Contract to J.J.R. Construction, Inc. for the FY23 Annual Citywide
Curb Ramp Project No. 23-PW-280 for a Total Project Expenditure of
$174,565
A motion was made to award the contract.
8.8.Adopt a Resolution of the City Council of the City of Gilroy Approving the
City of Gilroy (Applicant) to Apply for Grant Funds Under the Safe, Clean
Water and Natural Flood Protection Program
A motion was made to adopt the resolution.
Enactment No.: Resolution No. 2023-14.
9.BIDS AND PROPOSALS
There were none.
Agenda Item 7.1
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Regular Meeting Minutes
10.PUBLIC HEARINGS
10.1.Appeal of Planning Commission Decision to Deny an Application
Proposing Changes to City Code to Allow Up to Two Electronic Billboards
in the City of Gilroy [This is a De Novo Hearing at Which the Council Will
Decide if the Environmental Review is Adequate, and if so, Whether or not
to Introduce the Ordinance.]
Mayor Blankley asked Council Members if they have any ex-parte
communications to disclose.
Council Member Bracco disclosed that he met with Connie Rogers. No new
information was gained.
Council Member Armendariz disclosed that she spoke with Mike Conrotto,
Connie Rogers, and Pete Carrillo from Outdoor Communications. She learned
more information about the lighting distance of the electronic billboards.
Council Member Marques disclosed that she spoke with Mike Conrotto and
Connie Rogers. No new information was gained.
Council Member Hilton disclosed that he engaged with various members of the
community. No new information was gained.
Council Member Cline disclosed that he spoke with Mike Conrotto, Connie
Rogers, and several managers from the car dealerships. No new information
was gained.
Council Member Tovar disclosed that he spoke with Mike Conrotto, Connie
Rogers, and Pete Carrillo. No new information was gained.
Mayor Blankley disclosed that she spoke with Mike Conrotto, Connie Rogers,
and Brian Verdin from Nissan of Gilroy. No new information was gained.
Customer Services Manager McCormick provided staff presentation and
responded to Council Member questions.
Mayor Blankley opened the Public Hearing at 6:48 PM.
Appellant Sean Marciniak provided the appellant’s presentation to Council
and responded to Council Member questions.
The following speakers spoke in favor of adopting the ordinance:
Danny Mitchell
Ron Kirkish
Gregory Bumb
Brian Verdin
Gary Gordon
Marucio Leon
Eduardo Martinez
Javier Leon
Fiesta Depot
Jose Martinez
Clair P. Braga
Tom Chavez
Agenda Item 7.1
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Regular Meeting Minutes
The following speakers spoke against the approval of the ordinance:
Terence Fugazzi
Les Levitt
Dr. Paul Lynam
Jason Hemp
Connie Rogers
Mar Yates
Michelle Nelson
Juan Estrada
Rani Fischer
There being no further public speakers, Appellants Sean Marciniak and Ron
Conrotto provided the appellant’s rebuttal to Council.
Mayor Blankley closed the Public Hearing at 7:19 PM.
Motion: Adopt the resolution finding that the Final IS/MND was completed
in compliance with the California Environmental Quality Act (CEQA); there
is no substantial evidence that the project will have a significant effect on
the environment due to mitigations agreed to by the applicant; and the
Final IS/MND reflects the City’s independent judgment and analysis.
RESULT:Pass
MOVER:Fred Tovar, Council Member
SECONDER:Carol Marques, Council Member
AYES:Mayor Pro Tempore Bracco, Council Member Cline, Council
Member Marques, Council Member Tovar, Mayor Blankley
NAYS:Council Member Armendariz, Council Member Hilton
Enactment No.: Resolution No. 2023-15.
Motion: Uphold the appeal and motion to read the ordinance by title only
and waive further reading of the ordinance.
RESULT:Fail
MOVER:Dion Bracco, Mayor Pro Tempore
SECONDER:Fred Tovar, Council Member
AYES:Mayor Pro Tempore Bracco, Council Member Marques, Council
Member Tovar
NAYS:Council Member Armendariz, Council Member Cline, Council
Member Hilton, Mayor Blankley
Motion: Deny the appeal and uphold the Planning Commission’s decision.
RESULT:Pass
MOVER:Rebeca Armendariz, Council Member
SECONDER:Zach Hilton, Council Member
AYES:Council Member Armendariz, Council Member Cline, Council
Member Hilton, Mayor Blankley
NAYS:Mayor Pro Tempore Bracco, Council Member Marques, Council
Member Tovar
11.UNFINISHED BUSINESS
Agenda Item 7.1
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Regular Meeting Minutes
There were none.
12.INTRODUCTION OF NEW BUSINESS
12.1.2022 General Plan and Housing Element Annual Progress Report
Community Development Director Goei provided staff presentation and
responded to Council Member questions.
Mayor Blankley opened Public Comment. There being no speakers, Mayor
Blankley closed Public Comment.
Council accepted the report and directed staff to submit the 2022 Annual
Progress Report to the California Department of Housing and
Community Development and the Governor’s Office of Planning and Research.
12.2.Unhoused Camping Ban Near Schools and Critical Infrastructure
Assistant to City Administrator Atkins provided staff presentation and responded
to Council Member questions.
Mayor Blankley opened Public Comment. There being no further speakers,
Mayor Blankley closed Public Comment.
Council directed staff to continue further analysis on draft key policy points 1
through 7 as laid out in the staff report, along with adding creeks in its analysis.
Council further directed staff to return with a map of areas affected by the
potential ordinance and to further analyze the concerns brought forth by Council.
13.CITY ADMINISTRATOR'S REPORTS
City Administrator Forbis provided brief report and responded to Council Member questions.
14.CITY ATTORNEY'S REPORTS
There were none.
15.CLOSED SESSION
Mayor Blankley opened Public Comment. There being no speakers, Mayor Blankley closed
Public Comment.
The Mayor recessed the City Council at 8:41 PM.
The Mayor reconvened the Council to Closed Session at 8:46 PM. The motion to stay in
Closed Session was unanimous.
15.1.Conference with Negotiator – Pursuant to Government Code Section
54957.6, Gilroy City Code Section 17A.11 (4)
City Employee: Jimmy Forbis, City Administrator;
City Negotiator: Marie Blankley, Mayor;
Anticipated Issue(s) Under Negotiation: Employment Contract:
Employment Contract Between City of Gilroy & Jimmy Forbis
No reportable action.
Agenda Item 7.1
Page 15 of 768
March 20, 2023 | 6:00 PM Page 7 of 7 City Council
Regular Meeting Minutes
16.ADJOURN TO OPEN SESSION
Mayor Blankley reported out of Closed Session as shown above.
17.ADJOURNMENT
The meeting was adjourned by Mayor Blankley at 8:47 PM.
I HEREBY CERTIFY that the foregoing minutes were duly and regularly adopted at a regular
meeting of the City Council of the City of Gilroy.
Thai Nam Pham, CMC, CPMC
City Clerk
Agenda Item 7.1
Page 16 of 768
Page 1 of 1
City of Gilroy
STAFF REPORT
Agenda Item Title:Resolution of The City Council of The City of Gilroy
Proclaiming April 2023 as Arts, Culture, and Creativity
Month
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:City Clerk
Submitted By:Thai Nam Pham, City Clerk
Prepared By:Thai Nam Pham, City Clerk
STRATEGIC PLAN GOALS Not Applicable
RECOMMENDATION
Staff recommends Council adopt the resolution.
BACKGROUND
At the March 6, 2023 City Council Regular Meeting, Council Member Hilton requested
Council to consider adopting a resolution proclaiming April 2023 as Arts, Culture, and
Creativity Month at a future meeting. The item received unanimous support. Attached is
the draft resolution for Council’s adoption.
Attachments:
1. Draft Resolution
Agenda Item 7.2
Page 17 of 768
RESOLUTION 2023-XX
RESOLUTION OF THE CITY COUNCIL OF THE CITY OF
GILROY PROCLAIMING APRIL 2023 AS ARTS, CULTURE,
AND CREATIVITY MONTH
WHEREAS, the City of Gilroy celebrates and highlights the power of the arts and
creativity to change our lives for the better; and
WHEREAS, the Gilroy Arts & Culture Commission and SV Creates work in
partnership to support the arts and creativity in Gilroy as an essential part of our thriving
community; and
WHEREAS, the Gilroy Arts & Culture Commission, SV Creates and the Gilroy Arts
Roundtable work together to promote the value of the arts and to elevate Santa Clara
County’s creative culture; and
WHEREAS, Arts, Culture, and Creativity Month of April is the 5th annual statewide
awareness and advocacy event that recognizes the crucial role of arts, culture, and
creativity in the lives of everyone in California; and
WHEREAS, the City of Gilroy appreciates our relationship with SV Creates and
recognizes that the arts and creativity support student success and life-long learning,
provide key job skills, and bring joy to our community.
NOW, THEREFORE, BE IT RESOLVED THAT the City Council of the City of
Gilroy hereby proclaims April 2023 as Arts, Culture, and Creativity Month, and
encourages everyone to celebrate the power of the arts in our community.
PASSED AND ADOPTED by the City Council of the City of Gilroy at a regular
meeting duly held on the 3rd day of April 2023 by the following roll call vote:
AYES:COUNCIL MEMBERS:
NOES:COUNCIL MEMBERS:
ABSTAIN:COUNCIL MEMBERS:
ABSENT:COUNCIL MEMBERS:
APPROVED:
Marie Blankley, Mayor
ATTEST:
_______________________
Thai Nam Pham, City Clerk
Agenda Item 7.2
Page 18 of 768
Page 1 of 3
City of Gilroy
STAFF REPORT
Agenda Item Title:Approval of the Updated Purchasing Policy Inclusive
of Wage Theft Policy Statement
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:Finance
Submitted By:Harjot Sangha, Finance Director
Prepared By:Harjot Sangha, Finance Director
STRATEGIC PLAN GOALS Develop a Financially Resilient Organization
RECOMMENDATION
Council approve the updated Purchasing Policy.
EXECUTIVE SUMMARY
Staff is returning an updated Purchasing Policy for Council approval incorporating a
wage theft policy statement for all parties contracting with the City.
BACKGROUND
At the March 6, 2023 City Council Regular Meeting, staff presented an updated
Purchasing Policy incorporating the voter-approved City Charter changes to procure
public projects.
The March 6th approval from Council included directing staff to bring back the policy with
a proposed statement on wage theft. The proposed statement required an additional
completed and signed form that the project owner, contractor, and any subcontractors
certify compliance with wage theft protection laws and that there are no unpaid wage
theft judgments.
Agenda Item 7.3
Page 19 of 768
Approval of the Updated Purchasing Policy Inclusive of Wage Theft Policy Statement
City of Gilroy City Council Page 2 of 3 April 3, 2023
ANALYSIS
After further review, research, and discussion with the Public Works Department and
the City Attorney’s Office, staff has proposed a new subsection, 7.6 - Wage Theft Policy
Statement, within Section 7 - Special Policies and Program, of the Purchasing Policy.
It includes a general policy statement that all parties contracting with the City must
comply with the applicable federal, state, and local wage and hour laws. Further, it
contains the following elements for disclosure, disqualification, and contract termination:
•Disclosure – As part of City’s solicitation for goods and/or services, including
public works projects, bidders are required complete a certification that requires
contractor to disclose whether they have outstanding court or final administrative
action for violation of federal, state, or local wage and hours laws within the past
five (5) years. For each disclosed violation, contractor is required to further
provide documents demonstrating either the order/judgement to be satisfied, or a
written and signed description of contractor’s efforts to date to satisfy the
order/judgment.
•Disqualification – the City may disqualify a contractor based on the disclosed
violation of wage theft laws on more than one (1) occasion or has one (1) unpaid
wage judgment. Instead of an automatic debarment or disqualification, the City
will take into consideration the following when considering the disqualification:
o The amount of the judgment or final administrative decision.
o The number of employees impacted by the prior violations.
o The size of the company and history of compliance with wage and hours
laws.
o The impact to the City.
o Other factors that may be deemed appropriate.
•Contract Termination – if an existing, or current, contractor is found by a court or
by final administrative action of an investigatory government agency to have
violated applicable wage and hour laws in the five (5) years prior to or during the
term of the contract with the City, the contractor may be in material breach if the
violation is not fully disclosed and/or satisfied. Such breach may serve as a basis
for contract termination.
Changes from the Proposed Policy Statement
Two key components are different from the Council’s proposed wage theft policy
statement:
1. The proposed policy statement implied an automatic disqualification. The City
Attorney’s Office advised against this as it could be considered an automatic
debarment. Instead, it is recommended that City have a process to take into
consideration the factors outlined above when considering the disqualification.
Agenda Item 7.3
Page 20 of 768
Approval of the Updated Purchasing Policy Inclusive of Wage Theft Policy Statement
City of Gilroy City Council Page 3 of 3 April 3, 2023
This allows the City to evaluate the breadth of the violation further and not limit
the pool of contractors that may be able to submit bids and proposals.
2. The proposed policy statement included subcontractors in the scope. After
further review and discussion, it is recommended, from a practical perspective,
that the scope includes the party entering into an agreement with the City. Any
issues with the subcontractor are generally addressed directly with the prime
contractor with whom the City has entered into an agreement.
ALTERNATIVES
Council can amend or reject the proposed wage theft policy statement.
FISCAL IMPACT/FUNDING SOURCE
There is no direct fiscal impact to updating the Purchasing Policy. The effort was
accommodated within the Finance Department’s existing work plan.
NEXT STEPS
The Policy will be posted on the City’s website and communicated internally to the
organization upon approval. Related training will be provided to City staff on the
requirements of certification to be included in the solicitations.
Attachments:
1. Updated Purchasing Policy - April 3, 2023
Agenda Item 7.3
Page 21 of 768
Updated: March 6April 3, 2023
City of Gilroy
Purchasing Policy
Agenda Item 7.3
Page 22 of 768
Purchasing Policy
Table of Contents
i
Table of Contents
Section 1 – Purchasing Policy Overview .............................................................................................. 1
1.1 Purchasing Policy Overview .................................................................................................... 1
Section 2 – Code of Conduct and Ethics ............................................................................................... 3
2.1 Code of Conduct Overview ...................................................................................................... 3
2.2 Conflict of Interest ...................................................................................................................... 3
2.3 No Gratuities ............................................................................................................................... 3
2.4 Conduct with Vendors .............................................................................................................. 3
2.5 Disciplinary Actions for Policy Violations.............................................................................. 4
Section 3 – Purchasing System Authorities and Responsibilities ................................................... 5
3.1 Decentralized Purchasing System Overview ......................................................................... 5
3.2 General Categories of Purchases .............................................................................................. 5
3.3 Authority to Award Contracts ............................................................................................. 556
3.4 Responsibilities of Purchasing Division .................................................................................. 7
3.5 Responsibilities of City Staff ..................................................................................................... 7
3.6 Authorized and Unauthorized Purchases .............................................................................. 8
3.7 Contracting Requirements .................................................................................................... 889
Section 4 – Procurement Mthods.......................................................................................................... 11
4.1 Procurement Methods Overview ........................................................................................... 11
4.2 Selecting the Appropriate Procurement Method ................................................................. 11
4.3 Purchasing Card Program ................................................................................................... 13
4.4 Informal Procurement Procedures ......................................................................................... 14
4.5 Formal Bidding Procedures .................................................................................................... 15
4.6 Request for Proposals .............................................................................................................. 19
4.7 Two-step Competitive Bidding Processes ............................................................................ 21
4.8 Emergency Procurement ......................................................................................................... 22
4.9 Purchases Exempt from Competitive Bidding ............................................................. 222223
4.10 Cooperative Purchases .......................................................................................................... 24
Section 5 – Specification Development .............................................................................................. 26
5.1 Specifications for Competitive Bidding – Overview ........................................................... 26
Section 6 – Sourcing and Standardization ......................................................................................... 28
6.1 Sourcing and Standardization Overview ............................................................................. 28
Agenda Item 7.3
Page 23 of 768
Purchasing Policy
Table of Contents
ii
6.2 Single and Sole Sourcing ......................................................................................................... 28
6.3 Standardization ........................................................................................................................ 28
Section 7 – Special Policies and Programs ......................................................................................... 29
7.1 Special Programs and Policies Overview ............................................................................. 29
7.2 Local Purchasing Preference ................................................................................................... 29
7.3 Minority, Disabled and Woman Owned Business Policy Statement ................................ 30
7.4 Environmentally Preferable Purchasing Policy ................................................................... 31
7.5 Policies and Procedures for Purchases Utilizing Federal Grant Funding ........................ 31
Section 8 – Purchasing-related Instructions and Procedures .................................................. 333332
8.1 Bid/Proposal Protest Procedures .................................................................................... 333332
8.2 Certificates of Insurance and Coverage Requirements ............................................... 343433
8.3 Instructions to Bidders..................................................................................................... 343433
8.5 Lease, Rental and Lease-to-Purchase Procurements ........................................................... 34
8.5 Life Cycle Cost Analysis .................................................................................................. 353534
8.6 Service Provider Evaluation ................................................................................................... 35
8.7 Surplus Property Disposal ...................................................................................................... 35
8.8 Used Automobile Purchases ................................................................................................... 37
Section 9 – Glossary of Terms....................................................................................................... 393938
9.1 Definitions ......................................................................................................................... 393938
Agenda Item 7.3
Page 24 of 768
Purchasing Policy
Section 1 – Purchasing Policy Overview
1
Section 1 – Purchasing Policy Overview
1.1 Purchasing Policy Overview
The purpose of this manual is to provide basic information for procuring goods and services
consistent with adopted policies and procedures, and best practices. This manual is intended to
provide sufficient information and reference detail to enable City employees to be fully aware
of, and comply with, City purchasing policies, and to effectively participate in the purchasing
program.
This section of the purchasing policies and procedures manual establishes the legal
requirements of the procurement function within the City organization and establishes
procurement expectations to safeguard fairness, system integrity and ethical practices.
1. Legal Requirements. The legal bases for the purchasing system are established below.
➢ Several sections of the City Charter enumerate authorities relative to purchasing-
related functions:
▪ Section 703. Establishes that the City Administrator:
• Can enter into contracts on behalf of the city involving Council-
appropriated expenditures and bid or proposals approved by
Council.
• Will implement a citywide purchasing system.
▪ Section 800. Requires in paragraph 4 that purchasing rules and
regulations be included in the administrative code which shall be
amended by ordinance as necessary.
▪ Section 1104. Specifies in paragraph 3 that during any fiscal year city
employees cannot spend or incur any obligations to spend money for any
purpose without a budgeted appropriation.
▪ Section 1109. Contains requirements for letting public works construction
projects, including best value and design-build contracting
▪ Section 1110. Contains certain requirements that bidders must follow
when bidding on city projects.
Agenda Item 7.3
Page 25 of 768
Purchasing Policy
Section 1 – Purchasing Policy Overview
2
➢ The City Code Section 2.43(c) establishes the responsibilities of the purchasing
function.
2. Expectations of Fair and Open Procurement.
➢ Secure goods and services at the lowest possible cost commensurate with the
quality needed.
➢ Endeavor to obtain the most open competition possible for all purchases.
➢ Encourage competitive pricing from responsive and responsible business
providers that are qualified, capable and willing to meet the city’s requirements.
➢ Fulfill the requirements of Charter and City Code in the procurement of goods
and services.
Safeguard the city’s reputation for fairness, integrity and ethical practices.
Agenda Item 7.3
Page 26 of 768
Purchasing Policy
Section 2 – Code of Conduct and Ethics
3
Section 2 – Code of Conduct and Ethics
2.1 Code of Conduct Overview
All employees are responsible for impartially assuring fair competitive access to city
procurement opportunities by responsible suppliers and contractors. In addition, all employees
shall conduct themselves in a manner that avoids any impropriety, or appearance of
impropriety, and that fosters the highest level of public confidence in the integrity of Gilroy’s
purchasing system.
2.2 Conflict of Interest
No employee shall participate in a city procurement when the employee knows that:
1. The employee or the employee’s spouse, domestic partner, child, stepchild, parent or
stepparent will benefit financially from the procurement; and/or
2. The employee or the employee’s spouse, domestic partner, child, stepchild, parent or
stepparent is negotiating or has an employment arrangement contingent on or will be
affected by the procurement.
Upon discovery of an actual or potential conflict of interest, an employee shall
immediately withdraw from further participation in the procurement.
2.3 No Gratuities
No city employee shall solicit, demand, accept or agree to accept a gift of goods or services,
payment, loan, advance, deposit of money, or employment offer presented, promised in return
for, or in anticipation of favorable consideration in a city procurement.
2.4 Conduct with Vendors
Conduct with vendors who provide goods or services to the city shall be fair, open and
transparent. City employees shall:
1. Refrain from showing favoritism to vendors or being unduly influenced.
2. Safeguard confidentiality when required to do so.
3. Select vendors on the basis of meeting appropriate and fair criteria.
Agenda Item 7.3
Page 27 of 768
Purchasing Policy
Section 2 – Code of Conduct and Ethics
4
2.5 Disciplinary Actions for Policy Violations
City employees shall abide by and be accountable for the codes of conduct established in this
section. Policy violations may result in disciplinary actions in accordance with the city’s
established procedures, consistent with state law.
Agenda Item 7.3
Page 28 of 768
Purchasing Policy
Section 3 – Purchasing System Authorities and Responsibilities
5
Section 3 – Purchasing System Authorities and Responsibilities
3.1 Decentralized Purchasing System Overview
The city has adopted a decentralized purchasing system. This means that for most purchases,
requesting departments can directly solicit bids or proposals and place orders with suppliers,
subject to the limitations established in policy and subject to the approval of the appropriate
award authority. Nothing precludes staff from seeking procurement assistance from the finance
director or purchasing coordinator, especially to clarify policies, processes and procedures.
In a decentralized purchasing system, it is very important that all employees understand and
abide by the city’s procurement rules/polices and ensure their fair and consistent application.
3.2 General Categories of Purchases
City purchase categories generally consist of the following categories, for which different
procurement methods may apply (see Section 4, Procurement Methods, page 11):
1. Goods. The purchase of goods consists of materials, equipment and supplies needed by
any department.
2. Services. City staff may require contracts for services, which fall into two categories:
a. General Services. Services rendered such as custodial services, building/
equipment maintenance, and machinery/equipment rental, excluding contracts
for public works projects or professional services.
b. Professional Services. Services provided by a person or firm engaged in a
profession based on highly specialized and/or technical knowledge or skill, such
as the professions of accountant, attorney, artist, architect, landscape architect,
construction manager, engineer, environmental consultant, dentist, physician,
training or educational consultant, or land surveyor, and whose services are
considered distinct and unique to such a degree that bidding of such services
may not be feasible, if appropriately justified and documented (see Subsection
4.9, Exemptions from Competitive Bidding, page 22).
3. Public Works Projects. Public works pertain to the construction, alteration, repair, or
improvement of any public structure, building, road, or other public improvement of
any kind, including demolitions, and the construction and installation of drainage
systems, lighting and signaling systems, sewer and water systems, and park and
recreational facilities. Maintenance required to preserve a public improvement is not
considered a public work.
3.3 Authority to Award Contracts
The following section outlines the various contract award authorities established under the
decentralized Purchasing System.
Agenda Item 7.3
Page 29 of 768
Purchasing Policy
Section 3 – Purchasing System Authorities and Responsibilities
6
1. Award Authority. Contract award authority is established by dollar threshold for each
of the following entities:
a. City Council. Purchases or contracts for goods and services, including public
works construction contracts, of $100,000 or more, must be awarded by the City
Council.
b. City Administrator. Purchases or contracts, including public works construction
contracts, up to $99,999 may be awarded by the City Administrator.
c. Department Heads. As authorized by the City Administrator, department heads
may make purchases and enter into contracts for goods and services, including
public works construction contracts, up to $49,999.
d. Staff. Purchases up to $4,999 may be made at the staff level as designated by
department directors.
2. Authority to Legally Bind City. Unless specifically authorized as established in this section or
elsewhere in adopted and written City policy, staff other than the City Administrator and
department heads cannot enter into contractual arrangements to purchase goods or
services or otherwise legally bind the City for such purchases.
3. Award Authority Determined by One Transaction. For the purpose of determining the
appropriate award authority, contract amounts are defined by what constitutes a single
or one transaction. This rule also applies to competitive bidding (the estimate of dollar
value of the transaction dictates the level of bidding required).
a. One-time Purchases. Each discrete, one-time purchase is a single transaction.
b. Blanket Purchase Orders. The contract term of a blanket purchase order is
generally considered a single transaction, subject to total contract length
requirements established in a competitive bidding process. See also Subsection
3.7.6.b on page 9.
Examples: A blanket order in the amount of $10,000 that is issued for vehicle
parts for a one-year period is a single transaction. Subsequent annual renewals of
the blanket order are considered separate, single transactions.
A five-year blanket order for on-call maintenance work in the amount of $25,000
each year (for a total of $125,000) requires Council approval.
c. Contract Amendments. Dollar increases to existing contracts require the sum of
the original contract to be added to the amount of the amendment to determine
the single transaction value.
Example: The City Administrator awards a contract for $75,000 and a $30,000
amendment is required. The resulting transaction is $105,000, now requiring
Council approval.
Agenda Item 7.3
Page 30 of 768
Purchasing Policy
Section 3 – Purchasing System Authorities and Responsibilities
7
3.4 Responsibilities of Purchasing Division
1. Purchasing Function. As established in Section 2.43(c) of the City Code, the purchasing
division is responsible for:
a. Purchasing materials, supplies, and equipment (goods) and services for use by
all departments when appropriate.
b. Preparing standard specifications for goods and services wherever possible.
c. Maintaining a purchase order system and issuing purchase orders as required.
d. Verifying that all bids and proposals are in accordance with policy requirements.
e. Establishing and operating a system of stores for the bulk purchase of commonly
used items.
f. Selling surplus personal property of the City, subject to the determinations and
approval of department heads, the City Administrator and the City Council.
3.5 Responsibilities of City Staff
1. Responsibilities of all employees. As keepers of the public trust, all City employees are
required to discharge their duties fairly, impartially and with the highest degree of
integrity. In support of these concepts as they apply to the purchase of goods and
services, City staff shall:
a. Clearly identify procurement needs and the availability of funding.
b. Work with the purchasing coordinator to develop suitable competitive
specifications.
c. Participate in the evaluation of bids and proposals as required.
d. Inspect goods delivered and services performed to determine conformity with
established requirements and contractual obligations.
e. Authorize payment for conforming goods and services.
f. Notify the purchasing coordinator of non-conforming goods or services.
g. Document tangible or intangible value to the city when requisitioning goods or
services without competition.
h. Recognize that fair and open competition results in better value to the city.
i. Understand and be accountable for the policies and procedures established for
purchasing goods and services.
2. Purchasing Requisition Required. Goods and services purchases that will require a
contract, purchase order, or blanket purchase order, including public works
construction, must be initiated with a properly documented and approved purchase
requisition which includes:
a. Concise description of the purchase which adequately communicates need.
b. Actual or estimated dollar amount.
c. Valid charge/project and object number.
d. Verification of available funding or identification that funding is needed.
Agenda Item 7.3
Page 31 of 768
Purchasing Policy
Section 3 – Purchasing System Authorities and Responsibilities
8
e. Price quotes with recommended vendor selection and appropriate award
justification.
f. Bid exemption documentation as required.
3.6 Authorized and Unauthorized Purchases
This section defines authorized and unauthorized purchases and how they are memorialized
and establishes that employees can be held responsible for unauthorized purchases that are not
ratified by the appropriate award authority.
1. Authorized Purchases. Purchases are authorized only when the appropriate award
authority has approved the purchase. Only the City Council, City Administrator, and
department heads, or authorized designee in writing from the City Administrator, may
legally bind the city to a contract.
2. Unauthorized Purchases. Purchases approved by anyone other than the designated
award authorities are unauthorized. It is the responsibility of every employee to
understand the policy requirements and avoid unauthorized purchases to the greatest
extent possible.
3. Ratification Process Required. Unauthorized purchases can be validated only if ratified
by the appropriate award authority, in its sole and absolute discretion. For
unauthorized purchases to be considered for ratification, the following steps must
occur:
a. The employee making the unauthorized purchase must provide a written
explanation of why the purchase was made.
b. The written explanation must be reviewed and approved by the appropriate
award authority.
4. Restitution. In the event that a vendor has been paid and the unauthorized purchase is
not subsequently ratified, the employee may be held responsible for reimbursing the
city.
3.7 Contracting Requirements
The following section explains the various contracting requirements associated with making
purchases with City funds.
1. Contract Award. A contract is not considered to be awarded until it is approved by the
appropriate award authority, i.e., the City Council, City Administrator or authorized
department head as described in Section 3.6 above.
2. Standard Contract Terms and Conditions. Use of the city’s standard contracts (or
terms and conditions for purchase orders) provided by the City Attorney are preferable
to using vendor-provided contracts. If presented with a vendor-provided agreement,
staff should attempt to replace it with the city’s standard agreement or standard terms
Agenda Item 7.3
Page 32 of 768
Purchasing Policy
Section 3 – Purchasing System Authorities and Responsibilities
9
and conditions for purchase orders. The purchasing coordinator can assist with the
negotiation process as necessary.
3. Written Contract Requirement. Written contracts on city templates provided by the
City Attorney are required for services with a value of $10,000 or more. Services with a
value of less than $10,000 should be put on purchase orders with standard terms and
conditions, unless compelling factors such as liability or risk dictate the use of a written
agreement.
4. City-provided Scope of Work Requirement. Contracts should include well-defined
scopes of work provided by city staff and the use of consultant or vendor-provided
work scopes should be minimized to the greatest extent possible.
5. No Contract Splitting. Under no circumstances can any contract be split or separated
into smaller components to determine the appropriate award authority or for any other
purpose.
6. Contract Types. The city utilizes several different types of contracts depending on the
nature of the purchase and requirements of the City Attorney’s Office.
a. Purchase Orders. Purchase orders are used to make discrete, non-recurring
purchases of goods and/or services. Depending on the cost and complexity of
the purchase, a written agreement may be required. Purchase orders are
required for most city transactions.
b. Blanket Purchase Orders. Blanket purchase orders are term contracts, usually
established for one-year periods for routine, recurring or as-needed purchases of
goods and/or services. Blanket purchase orders can be renewed annually
according to the terms established through competitive bidding or negotiation,
or as approved by the appropriate award authority. Blanket purchase orders
may also be established for multi-year periods and/or as master goods/services
agreements.
Blanket purchase orders may be established for as-needed small construction or
maintenance projects and/or for urgent or emergency repairs where time is of the
essence. These types of arrangements are referred to as Job Order Contracts
(JOCs) and are bid on a unit cost basis with contracts awarded based on not-to-
exceed amounts approved by the appropriate award authority.
c. Service Agreements. Depending on the cost and complexity, agreements may
be required for general or professional services. These are referred to as General
Services Agreements (GSAs), Professional Services Agreements (PSAs), Master
Service Agreements (MSAs) or Master Professional Service Agreements (MPSA).
d. Confirming Orders. Confirming orders are written purchase orders that
confirm previously placed verbal orders. This form of contract may be utilized
Agenda Item 7.3
Page 33 of 768
Purchasing Policy
Section 3 – Purchasing System Authorities and Responsibilities
10
for urgent or emergency purchases but requesting departments must use
prudent judgment.
7. Key Contracting Prerequisites. Contractors or vendors conducting business in the city
or working on city property or in city rights-of-way must be properly licensed, insured,
and otherwise comply with all lawful requirements such as obtaining a business license
as required by the Finance Department and having appropriate insurance coverage as
required by the risk manager. The contractor or vendor must include the City of Gilroy
as an “additional insured” on their insurance policy and provide up-to-date insurance
certificates with required policy endorsements. These requirements must be met before
any work can commence.
Agenda Item 7.3
Page 34 of 768
Purchasing Policy
Section 4 – Procurement Methods
11
Section 4 – Procurement Methods
4.1 Procurement Methods Overview
This section outlines the various methods of procurement to be used by employees who have
authority and/or responsibility for procurement processes and procedures.
Below are guiding principles by which staff participating in procurement processes must abide:
➢ Purchases shall be based on competitive bidding processes whenever possible, unless
otherwise exempt in accordance with Subsection 4.9, Purchases Exempt from Competitive
Bidding on page 22.
➢ The complexity of the bidding process, and the applicable requirements, increase with the
dollar value of the procurement.
➢ Under no circumstances shall purchases be artificially split to use a more simplified process.
➢ In situations where goods and/or services can be defined with a high degree of specificity,
then a contract will be awarded to the lowest responsive and responsible bidder through a
bid process.
➢ If the purchase is solution-based and cannot be exactly defined, then a best-value process
may be used where the city can pay a higher price for a good and/or service if the overall
value can be justified.
➢ Measured use of cooperative purchasing programs and piggyback agreements, which
leverage volume purchases, secure value pricing and reduce administrative overhead, is
encouraged.
➢ Staff must take into account the city’s special policies and procedures for many
procurements. These include environmental procurement, application of the 5% local
purchasing preference (except for public works construction and professional services),
disadvantaged business enterprises and purchases using federal grant funds (see Section 7,
Special Policies and Programs, page 31).
4.2 Selecting the Appropriate Procurement Method
To select an appropriate procurement method, employees should know the category of
purchase (type of goods, services or public works project) and have an estimated cost in mind.
Agenda Item 7.3
Page 35 of 768
Purchasing Policy
Section 4 – Procurement Methods
12
For goods and services purchases, competitive bidding and approval thresholds are determined
by each transaction.
1. Goods and services transactions $4,999 or less. Goods and services $4,999 or less may be
made without a competitive process. This amount is consistent with the threshold
established for purchases utilizing federal funding (see Subsection 7.5, Policies and
Procedures for Purchases Utilizing Federal Grant Funding, page 31). However, staff are
encouraged to price shop whenever possible to ensure the city is receiving the best value in
exchange for public funds.
2. Goods and services transactions between $5,000 and $99,999. Goods and services with an
estimated value between $5,000 and $99,999 in a single transaction must be procured using
the methods established in the Informal Procurement Procedures in Subsection 4.4 below.
3. Goods and services purchases $100,000 or more. Goods and services purchases with an
estimated value of $100,000 or more in a single transaction must be procured using formal
bidding or proposal procedures established in Subsection 4.5, Formal Bidding Procedures
on page 15.
4. Public works projects. In accordance with Section 1109 of the City Charter, Public works
projects anticipated to cost equal to or less than the amount allowed for informal bidding
pursuant to section 22032 of the California Public Contract Code, currently $200,000, as the
same may be amended from time to time, may be let using Informal Bidding Procedures
outlined in section 4.4, on page 14.
In accordance with Section 1109 of the City Charter, Public works projects anticipated to
exceed the amount allowed for informal bidding pursuant to section 22032 of the California
Public Contract Code, currently $200,000 or less, as the same may be amended from time to
time, must be conducted through sealed bidding and shall be let by contract to the lowest
responsive and responsible bidder, or through best value contracting, in further accordance
with the bidding procedures established in Subsection 4.5, Formal Bidding Procedures, on
page 15.
a. Design-Build public works projects. For public works projects with contracts equal to
or in excess of $1,000,000, the City Council may negotiate and award a Design-Build
Contract without formal sealed public bidding if the Council finds that such a contract
would save money or result in faster project completion. The process for competitively
selecting a design-build contract shall be consistent with the California Public Contract
Code. The procurement shall be made in accordance with the bidding procedures
established in subsection 4.6, Request for Proposals on page 19, and shall include the
following:
i. Bridging documents shall be prepared by a design professional designated by the
City, identifying the scope and estimated price or cost of the public works project
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and including additional requirements or information necessary to adequately
describe the City’s needs for the project. This may include, not limited to, the size,
type, and design character of the project, the performance specifications covering the
quality of the supplies, materials, equipment, and workmanship, or preliminary
plans or building layout plans. The design professional, which prepares the bridging
documents, may not subsequently submit or participate in the proposal submitted
for an award of design-build contract, or have any financial interest in any design-
build entity or team which submits a design-build contract construction proposal or
which provides the design-build services.
ii. A formal request for proposal shall include the bridging documents described in
section 4.2.4.a.(i) above, a request for qualification, and the design-build contract
documents approved by the City Attorney.
iii. Design-build entities may be required to pre-qualify in order to be eligible to submit
a proposal for the design-build project by responding to the request for
qualifications in advance of the date set for the submission of the proposals. A
standard template for statement of qualification shall be established and provided in
the request outlining the qualification criteria consistent with, but not limited to,
section 22164(b) of the California Public Contract Code. The City may establish and
maintain a qualified list of design-build entities based on the qualification process
for soliciting proposals on future new design-build projects.
iv. The design-build contract may be awarded to a responsive, responsible design-build
entity on the basis of either the lowest lump-sum price or the “best value” provided,
as defined in the formal request for proposals. A design-build contract that is
awarded on the best value basis shall be evaluated based solely on the selection
criteria and procedures set forth in the formal request for proposals.
v. The design-build contract shall require the design-build entity and its subcontractors
to comply with the requirements of Section 22164(c) of the California Public Contract
Code, as amended from time to time.
4.3 Purchasing Card Program
As an alternative, efficient method of making small dollar purchases, a purchasing card
program has been established for use by employees based on operational need. In many
instances, purchasing cards can be used to buy needed materials and supplies, rather than using
purchase orders.
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Purchasing cards are approved by department heads and issued by the purchasing coordinator,
to be used in strict accordance with the Purchasing Card Policy.
4.4 Informal Procurement Procedures
Informal procurement procedures apply to purchases of goods and services anticipated to be
less than $100,000, and for public works project anticipated to cost equal to or less than the
amount allowed for informal bidding pursuant to Section 22032 of the California Public
Contract Code, currently $200,000, as the same may be amended from time to time. Such
purchases may be made by staff in accordance with this section.
1. Purchases $4,999 or less. Purchases of goods and services less than $5,000 may be made by
staff without obtaining price quotes. However, staff are encouraged to price shop whenever
possible to ensure the city is receiving the best value in exchange for public funds.
2. Purchases between $5,000 and $24,999. Purchases in this estimated price range may be
made by staff with department director approval and based, to the best extent possible, on
at least three written price quotes. Contracts are typically awarded to the lowest responsive
and responsible provider, but best value determinations can be made on factors in addition
to pricing if the justification is properly documented and in the best interest of the City.
3. Purchases between $25,000 and $99,999. Purchases of goods and services in this estimated
price range may be made using informal bid and/or request for proposal documents, as
follows:
a. Invitation to Quote. Use this template for goods and/or services with an estimated cost
at or below $49,999 (or for a lower threshold amount if required by a department head
or the purchasing coordinator). If a contract is not being awarded to the lowest
responsive and responsible bidder, the purchasing requisition must contain a concise
explanation to justify the selection, including evaluation factors if appropriate or
requested by the purchasing coordinator.
b. Informal Request for Proposals (RFP). Use this template for services (or in some cases
specialized goods or a mix of goods and services) between $50,000 and $99,999 that are
procured through a best value, rather than low bid, process. Informal RFPs may also be
required for professional services less than $50,000 as required by department heads.
Best value procurements are awarded based on factors in addition to price (e.g., the city
may pay more for a solution if the overall value can be justified), and are conducted
through an evaluation process similar to but less formal than that required for formal
competitive proposals (see Subsection 4.6, Request for Proposals, on page 19).
4. Public works projects equal to or less than the amount allowed for informal bidding
pursuant to California Public Contract Code. Procurement of public works projects
estimated to cost equal to or less than the amount allowed for informal bidding pursuant to
Section 22032 of the California Public Contract Code, currently $200,000, as the same may be
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amended from time to time, may be made using the informal bid, subject to the appropriate
award authority outlined in section 3.3 and contracting requirements outlined in section 3.7:
a. Invitation to Quote. Use this template for public works construction contracts with an
estimated cost at or below $200,000, and to the best extent possible, with at least three
written price quotes. If a contract is not being awarded to the lowest responsive and
responsible bidder, the designee shall provide a written statement or report of the
procurement to the appropriate award authority and must contain a concise explanation
to justify the selection, including evaluation factors as appropriate.
5. Prevailing Wage Requirements. The payment of prevailing wages is required for
maintenance contracts over $15,000 and construction contracts over $25,000. Additionally,
such contracts must follow California Department of Industrial Relations (DIR) contractor
registration requirements for contractors and their subcontractors (see also Subsection
4.5.3.h on page 17). Suitable language regarding this requirement should be in all such
contracts.
4.5 Formal Bidding Procedures
Formal sealed bidding using an Invitation for Bids (IFB) is required for purchases anticipated to
be more than $100,000, including materials and equipment (goods), certain services, and public
works construction projects greater than $200,000. Contracts associated with formal bids are
awarded to the lowest responsive and responsible bidder with the exception of public works
construction projects that may be awarded by using the best value contracting per Section 1109
of City Charter. The requirements detailed below apply.
1. Coordination with Purchasing. These actions must be coordinated with Purchasing
before conducting a formal bid process:
a. Obtain a Bid Number. The purchasing coordinator will assign a bid number
that will be used to track the project throughout its life cycle.
b. Request Bid Opening Date. The purchasing coordinator will determine
availability of Council chambers to conduct the public bid opening.
c. Creation of Bid File. All bidding documents created in conjunction with each
bid must be sent to the purchasing coordinator so that a bid file constituting the
city’s official record can be kept in strict accordance with the records retention
schedule.
2. Advertising the Bid Opportunity. All formal bids should be publicly noticed by the
purchasing coordinator or designated staff for at least 14 calendar days, (except for
public works construction projects governed by section 1109 of the City charter) prior to
the date and time set for receiving bids, either in a newspaper of general circulation in
the City or on the City’s website, unless a shorter timeframe is warranted.
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For public works construction projects, the notice shall be given by one or more of the
following methods per Section 1109 of the City Charter:
• Publication in newspaper of general circulation in the City by one or more
insertions, the first of which shall be at least (7) days before the time of opening
bids. This method of publication shall be used if available;
• Publication electronically so that the notice is publicly available to the general
community of potential bidders;
• Publication in a trade journal specified by the Uniform Cost Accounting Act
Commission by one or more insertions, the first of which shall be at least (7) days
before the time of opening bids; or
• By using a list of qualified contractors, which includes responsible contractors
who have bid in the past and qualified contractors who ask to be included on the
list.
a. Notice Inviting Bids. The Notice Inviting Bids (NIB) specifies:
i. The date, time and place where and when bids will be received, publicly
opened and the bids of each bidder read out loud.
ii. The name of the staff member to whom bids must be addressed.
iii. General description of the goods, services or construction work required.
3. Invitation for Bids (IFB). An Invitation for Bids (IFB) is the bid template required for
use with formal bids. The IFB must include at least the following elements:
a. Notice Inviting Bids. The IFB must include the bid notice that was used to
advertise the bid.
b. Instructions to Bidders. Bid documents must include instructions to bidders to
explain the bidding process, and explain the city’s requirements (see also
Subsection 8.3, Instructions to Bidders, page 33).
For public works construction projects, the bid document must identify the
process by which the award will be made, either exclusively based on lowest
responsive and responsible bidder, or best value contracting based on objective
criteria to determine the best combination of price and qualifications.
c. Bid Specifications. Detailed specifications that provide technical design and/or
performance requirements are required for all IFBs.
d. Subcontractor Listing. Contractors bidding on city projects must include a
listing of subcontractors.
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e. Non-collusion Affidavit. Contractors bidding on city projects must provide a
notarized affidavit certifying that they have not colluded with any other entity
in providing a bid.
f. Bid Forms and Schedules. The bid document must include applicable bid forms
and schedules necessary for determining the lowest responsive and responsible
bidders.
g. Bond Forms as Required. Many awarded projects will require that contractors
provide executed faithful performance bonds (to guarantee their work) and
payment bonds (to guarantee payments to subcontractors).
h. Contractor/Subcontractor DIR Registration Section. Bids for construction and
maintenance work must include a form for contractors to provide their
Department of Industrial Relations (DIR) contractor registration numbers
(applies to contractors and their subcontractors) to ensure prevailing wage
compliance. This information must be provided by City staff to the DIR on the
PWC-100 Form following contract award.
i. Draft Contract if required. The bid documents must include a draft contract
with the city’s terms and conditions.
j. Instructions for Bid Addenda. Questions received within 10 business days of
the due date will be answered in the form of a properly issued bid addendum.
No change or modification to the plans or specifications can be made without
such notification. Bid addenda must be provided to all holders of official bid
documents and posted to the city’s website.
4. Bid Security. A bid security in the form of a bid bond, cash, certified check or other
acceptable instrument, in an amount not exceeding 10% of the bid price, may be
required. If a bid security is required, it must be stated in the bid documents.
5. Public Bid Opening. Sealed bids will be publicly opened in the presence of at least one
witness (typically the purchasing coordinator) at the time and location specified. If
members of the public are present, the names of each bidder and their total bid pricing
will be read aloud, and the apparent low bidder will be announced.
For public works construction projects, if the best value procurement option is utilized,
there shall be no public bid opening until the experience and qualifications information
is evaluated by a designated evaluation panel. The pricing information shall remain
sealed until the panel completes the evaluation to ensure the panel’s evaluations are not
influenced by the pricing information.
6. Late Bids. Under no circumstances can late bids be accepted.
7. Bid Summary. Following the bid opening a bid summary will be prepared by the user
department and posted to the city’s website.
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8. Evaluating Bids and Awarding a Contract. The contract award process includes steps
detailed below.
a. Bid Analysis. Each bidder will be evaluated by designated staff to determine
whether their bid is responsive (complies with all material requirements of the
bid) and if they are responsible (have the skill and ability necessary to complete
the work).
b. Council Report. The user department will prepare a report to Council
recommending contract award to the lowest responsive and responsible bidder
and/or a recommendation for bid rejection.
If best value procurement option is utilized for public works construction
projects, the report shall include the justification for the selection including the
evaluation factors utilized to making the determination.
c. Bid Rejection. The finance director will issue any notice of rejection of any and
all bids, or any non-responsive bids, and the bid may be re-advertised at the
city’s discretion, except that Council is the rejecting authority for all public
works bids deemed excessive or unsatisfactory, per Section 1109 of the City
Charter. If a contractor provides more than one bid for the same work, those
bids must be rejected by the appropriate rejection authority (Section 1110 of the
City Charter).
d. Determining Bidder’s Responsiveness and/or Responsibility. Bids determined
to be non-responsive at the bid opening shall not be accepted. Subsequent
determinations of bid responsiveness and bidder responsibility during the due
diligence period must be carefully considered, with the latter requiring a much
higher level of due process for contractors.
e. Bid Protest Procedures. In the event of a protest by a contractor who has
submitted a timely bid, the protesting party must be afforded the opportunity to
voice their concerns through the formal process outlined in Section 8,
Purchasing-related Instructions and Procedures on page 32.
f. Contract Execution. Upon Council approval, designated staff will prepare and
send a contract package, including performance and payment bonds and
identification of any other requirements such as insurance, business license, etc.,
to the awarded contractor.
If the contractor fails to enter into the contract, their bid bond will be forfeited
and deposited in the general fund. If a bid bond was not required (in the case of
goods or services purchases), then the contractor who fails to execute the
contract will be liable for the difference between its bid and the next lowest bid,
plus administrative expenses and any required legal costs.
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9. Prevailing Wage Requirements. Maintenance contracts exceeding $15,000 and
construction contracts exceeding $25,000 can only be awarded to contractors who are
registered with the DIR (including any subcontractors) for the purpose of determining
prevailing wage compliance. Suitable language regarding this requirement should be in
all such contracts. Awarded contracts must be registered with the DIR by designated
staff within 30 days of award. Awarding a contract to a contractor who is not registered
with the DIR can result in penalties to the City.
10. Return of Bid Securities. Once a contract has been executed, the security accompanying
the accepted bids, and the unsuccessful bids, must be returned.
11. Submit Purchasing Requisition. Following contract approval by Council, a requisition
must be submitted to the purchasing coordinator so a purchase order can be generated.
4.6 Request for Proposals
Competitive sealed proposals using a Request for Proposals (RFP) process are used when
contracting for services estimated to be more than $100,000, or for solutions where procurement
needs cannot be determined with a high degree of specificity, unless otherwise exempt from
competition as described in Subsection 4.9, Purchases Exempt from Competitive Bidding on
page 22. Such procurements are conducted by competitive negotiation processes, rather than
awarding a contract to the lowest responsive and responsible bidder, as follows:
1. Coordination with Purchasing. These actions must be coordinated with the purchasing
coordinator before conducting a formal proposal process:
a. Obtain an RFP Number. The purchasing coordinator will assign an RFP
number that will be used to track the project throughout its life cycle.
b. Creation of an RFP File. All proposal documents created in conjunction with
each RFP must be sent to the purchasing coordinator so that a file constituting
the city’s official record can be kept in strict accordance with records retention
policies.
2. Request for Proposals. An RFP using the city’s standard template(s) must be prepared
and advertised.
3. Best Value. RFPs are awarded based on the best overall value to the city, as opposed to
lowest responsive and responsible bid, and include evaluation of qualitative and/or
quantitative factors in addition to price.
4. Advertising the RFP Opportunity. RFPs will be publicly noticed by the purchasing
coordinator at least 14 calendar days prior to the date and time set for receiving
proposals, either in a newspaper of a general circulation in the City (if available) or on
the city’s website, unless a shorter timeframe is warranted.
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5. RFP Document Contents. The RFP document shall include, at minimum, a Notice
Inviting Proposals; instructions to proposers, including protest procedures if warranted;
evaluation factors and their relative importance; specifications, requirements or scope(s)
of work describing the required goods and/or services; proposal forms and schedules;
any required bond forms; insurance requirements; and contract terms and conditions.
6. Evaluation Program. Once RFP responses are received, the proposals will be
confidentially evaluated and scored in accordance with criteria and procedures
established by the user department with input of the purchasing coordinator as
necessary. Interviews, presentations, site visits, etc., may be conducted depending on the
nature of the procurement.
Once a top-rated proposer is identified, good faith negotiations will commence. If an
agreement cannot be reached in consideration of cost and/or scope, the next highest-
rated proposer will be engaged, and so on, until a mutually acceptable agreement is
reached.
7. Qualifications-Based Selection Procedures. RFPs for certain professional or specialized
services may, by law, require Qualifications-Based Selection (QBS) procedures where
consultants or consulting firms are evaluated on their demonstrated competence and
professional qualifications before pricing can be considered. The QBS selection process is
typically associated with architectural, engineering, environmental, land surveying
and construction management firms in accordance with Section 4525 et. seq. of the
California Government Code or its federal counterpart, the Brooks Act. However,
nothing shall preclude staff from utilizing a QBS process for other types of RFPs if in the
best interest of the city.
Once a top-rated proposer is identified, then scope and fee negotiations commence. If an
acceptable contract cannot be finalized in consideration of scope and/or cost, then the
purchasing coordinator may commence scope and fee discussions with the next highest-
rated proposer, and so on, until a mutually acceptable agreement is reached. This type of
process is also referred to as a Request for Qualifications (RFQL) or Request for
Statements of Qualifications (RSQ).
8. Process Integrity. To protect the identity of the proposers and safeguard the integrity of
the evaluation process, all City employees participating in the evaluation of
competitively sealed proposals shall maintain strict confidentiality as well as disclose
any real or perceived conflicts of interest that may arise.
The Finance Director and/or City Attorney will review any disclosed potential conflicts
of interest and make a determination about the evaluator’s continued participation in
the procurement.
9. One Response Received. If only one RFP response is received and staff wishes to
proceed with the procurement (rather than rejecting the proposal), the purchasing
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coordinator will document the effort used to generate proposal responses prior contract
negotiations.
10. Rejection of proposals. The finance director will issue any notice of rejection of any and
all proposals, or any non-responsive proposals, and the RFP may then be re-advertised
at the City’s discretion. If a proposer provides more than one RFP response for the same
work, those responses must be rejected (Section 1110 of the City Charter).
11. Late Proposals Refused. RFP responses received after the designated closing date and
time cannot be accepted and must be returned unopened unless opening is required for
identification purposes.
12. Awarding a Contract. The contract award process includes the following steps:
a. Council Report. Following the technical evaluation and competitive negotiation
processes, the user department will prepare a report to Council recommending
contract award to the firm whose solution provides the best value to the city.
b. Determining Proposer Responsiveness and/or Responsibility. Determinations
of proposer responsiveness and responsibility must be carefully considered, and
any determination of non-responsibility should be reviewed by the City
Attorney.
c. Proposal Protest Procedures. In the event of a protest by a proposer who has
submitted a timely RFP response, the protesting party must be afforded the
opportunity to voice their concerns through the formal process outlined in
Section 8, Purchasing-related Instructions and Procedures on page 32.
d. Contract Execution. Prior to Council approval, staff can begin the contract
execution process by obtaining signature(s) from the awardee. Upon Council
approval, the contract execution process can be completed.
13. Submit Purchasing Requisition. Following contract approval by Council, a requisition
must be submitted to the purchasing coordinator so that a purchase order can be
generated.
4.7 Two-step Competitive Bidding Processes
For some procurements, it may be advantageous to conduct a two-step competitive process
where the first step is used to “shortlist” or prequalify interested firms. This type of
procurement begins with a Request for Qualifications (RFQ or RFQL) process, followed by
either an Invitation for Bids (IFB) or a Request for Proposals (RFP) process, depending on the
situation.
The RFQ/IFB process (RFQ/B) can be utilized to contract for important construction projects or
maintenance service contracts for which detailed specifications can be articulated. At the outset,
the prequalification process utilizes minimum threshold requirements that prospective bidders
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must meet (determined by an evaluation process) to provide a sealed bid, to be awarded to the
lowest responsive and responsible bidder.
The RFQ/RFP process (RFQ/P) can be an effective way to contract for services or system
solutions where professional or technical expertise or complex functional requirements, are
critical and overriding considerations. In this type of procurement, submitting firms are
evaluated based on their qualifications (which can include minimum threshold requirements),
followed by a competitive negotiation.
4.8 Emergency Procurement
This section establishes the fundamental elements required for emergency procurements.
1. Emergency Procurements Defined. Emergency procurements are those purchases
defined as immediately necessary for the preservation of life, health or property, or for
the continued operation of a department. Emergency procurements required as the
result full or partial activations of the Emergency Organization shall be conducted in
conjunction with Chapter 9 of the City Code (Emergency Organization and Functions).
2. Authority and Responsibility. The City Administrator or their designee may make or
authorize others to make emergency procurements, regardless of cost.
3. Competitive Bidding. Emergency procurements shall be made with such competition
as is practical under the circumstances, or that is required for reimbursement funding,
and shall be limited to those goods and services necessary to satisfy the emergency
need.
4. Written Report and Ratification Required. In such circumstances where emergency
procurements are required, the department head or designee shall provide a written
report of the procurement to the appropriate award authority, including a description
of the emergency and the basis for selection of the contractor. A copy of this report shall
be included in the procurement records maintained by the purchasing coordinator.
4.9 Purchases Exempt from Competitive Bidding
This section describes the types of purchases that may be exempted from competitive bidding
requirements, subject to the appropriate approvals.
1. Enumerated Bid Exemptions. The following may be appropriately justified as
exemptions to the competitive bidding requirement:
a. Emergency procurements as defined herein.
b. Situations where solicitations of bids or proposals would for any reason be
unavailing or impossible.
c. Professional or specialized services as defined in Subsection 3.2, General
Categories of Purchases on page 5.
d. Public library collection materials.
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e. Insurance, bonds or financial services.
f. Single or sole source goods or services as defined herein.
g. Highly specialized equipment developed or designed for a special activity or
function or whose purpose is in the best interests of the City due to
compatibility with existing equipment or training of personnel.
h. Procurements funded by grants, donations or gifts when any special conditions
require the purchase of particular materials and/or services.
i. Purchase of surplus property owned by another public entity, or payment to
other public entities or utilities.
j. Membership dues, conventions, training, travel arrangements, or
advertisements in magazines, newspapers, or other media.
k. Works of art, entertainment or performance.
l. Goods procured for resale to the public.
m. Where competitive bids or proposals have been solicited and no bid or proposal
has been received. In such situations the City Administrator may proceed to
have the goods procured or services performed without further competitive
bidding.
n. Computer software license or subscription renewals.
o. Human Resources investigation, legal services, and medical services, including
but not limited to, fitness for duty evaluations, expert witnesses, and other
employment related medical services.
p. Regulatory permits.
q. Subscriptions.
r. Reimbursements and/or refunds of payments made to the City.
s. In other cases when specifically authorized by the Council (if over $100,000)
after a finding and determination that it is in the best interests of the city.
2. Negotiations. The purchasing coordinator or designated staff can conduct negotiations,
if/as appropriate, as to price, delivery and terms and may require the submission of cost
or price data in connection with the award of a contract that does not require
competitive bidding.
3. Competitive Bidding When Possible. Nothing in this section shall preclude the
solicitations of competitive bids or proposals, when possible.
4. Documentation and Approval Required. Goods or services proposed to be exempt
from a competitive bidding process must be appropriately documented and approved
before a transaction can be conducted, as follows:
a. Purchases greater than $50,000 require City Administrator approval that must
accompany a purchase requisition before a purchase is made.
b. Purchases between $5,000 and $49,999 require approval by the Finance Director
or designee that must accompany a purchase requisition before a purchase is
made.
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4.10 Cooperative Purchases
This section discusses fundamental elements of cooperative purchasing programs. Use of
purchasing cooperatives is encouraged as a way of obtaining goods and services by aggregating
volume, securing value pricing, and reducing administrative overhead. Measured use of
purchasing cooperatives can significantly reduce the time and resources needed to
competitively bid goods and services contracts.
1. Authority to Use Cooperative Purchasing Programs. The purchase of goods and/or
services made under cooperative purchase programs, leveraging purchasing
agreements maintained or utilized by the state, county or other public or quasi-public
agencies, is authorized under Section 703 of the City Charter, Powers and Duties of the
City Administrator. Cooperative purchasing contracts must be approved by the
appropriate award authority.
2. Competitive Bidding. Cooperative purchasing programs should be based on
competitively awarded contracts whenever possible, and documentation as to the
advantage of the cooperative purchase will be retained by the purchasing coordinator
in conjunction with the value analysis requirements listed below.
3. Purchasing Cooperatives. There are numerous purchasing cooperatives the staff can
evaluate for use. Some leading cooperatives include state contracts such as California
Multiple Award Schedules (CMAS) of the Department of General Services (DGS); U.S.
Communities Cooperative Purchasing; National Joint Powers Alliance (NJPA); NASPO
ValuePoint (formerly WSCA-NASPO, or the Western States Contracting Alliance-
National Association of State Procurement Officials); and federal General Services
Administration (GSA) procurements (GSA Advantage for State and Local
Governments).
4. Value Analysis. The determination to make a purchase using a purchasing cooperative
agreement requires an analysis to determine whether the procurement represents the
best value to the city. Purchases using any given cooperative need not be based on the
absolute lowest pricing and may consider factors in addition to price such as the time
and/or resources needed to competitively bid the good or service. The analysis will be
performed and documented by user departments, with assistance provided by the
purchasing coordinator.
5. Piggyback Contracting. Subject to the appropriate approval authority, authorized staff
may enter into contracts for goods and services purchases, the pricing and terms of
which have been previously established by another public agency. The following
requirements apply to piggyback contracts, and must be verified by the purchasing
coordinator prior to contract award:
a. The parties to the original contract agree to the piggyback.
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b. The contract is for identical or nearly identical goods and/or services.
c. The original contract resulted from competitive bidding or proposal procedures
similar to those required by the city.
d. The original contract was awarded within two years of the city’s purchase, or
written justification is provided to support the use of an older solicitation.
e. The price of the purchase is comparable to that estimated by the requesting
department.
Provided that the above conditions are met and the purchase is approved by the
appropriate award authority, the purchasing coordinator will issue a purchase order
and/or execute (or cause to be executed) a separate contract with the vendor selected by
the originating agency which incorporates by reference the original solicitation, terms,
conditions and prices.
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Section 5 – Specification Development
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Section 5 – Specification Development
5.1 Specifications for Competitive Bidding – Overview
Specifications define precise requirements for the solicitation of goods and/or services. Writing
specifications is a collaborative process between user departments and the purchasing
coordinator to translate specific needs into detailed requirements.
1. Definition. A specification is a precise description of the physical characteristics,
quality, or desired outcomes of a commodity to be procured, which a supplier must be
able to produce or deliver to be considered for contract award.
2. Collaborative Process. Writing bids or proposal specifications is a collaborative process
between user department and purchasing to develop specifications with the goal of
promoting competition.
3. Clear Language. Specifications should use plain language that is relevant to and
understood by the bidding community.
4. Promote Competition. Good specifications should promote and not unduly restrict
competition. Use of restrictive specifications must be properly justified in accordance
with the provisions of this section.
5. Specification Attributes. There are essentially two types of specifications: design and
performance. Specifications typically contain elements of design and performance and
may be viewed as a continuum with each element on opposing ends.
a. Design Specifications. Design specifications establish the characteristics that a
commodity must possess, and may include manufacturing details such as
engineered plans, drawings or blueprints.
b. Performance Specifications. Performance specifications describe a commodity’s
desired outcome.
i. Functional Descriptions or Requirements. Performance specifications
may utilize functional descriptions of defined tasks or desired results.
Functional requirements are typically used for solutions such as software
systems.
ii. Brand Name Specifications. In areas where the city has standardized a
particular product such as fleet vehicles, staff may use one brand name
manufacturer, subject to approval by a department head (see also Section
6, Sourcing and Standardization on page 28). Brand name specifications
are restrictive, limit competition, and can result in increased cost. Use of
brand name specifications must be carefully evaluated before using them
in competitive bid documents.
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Section 5 – Specification Development
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iii. Brand Name or Approved Equal. Specifications that contain “brand
name or approved equal” are based on functional equivalency and
should be used whenever possible to promote competition and reduce
pricing.
6. Specification Development. Specification development is a critical part of the
competitive bidding process. In many cases specifications can be highly complex and
technical and require subject-matter expertise beyond that of city staff. The following
steps should be considered when developing specifications.
a. Collaborate. Meet with stakeholders of the procurement to formulate and
understand needs, and to internally peer review the specifications.
b. Conduct Market Research and Analysis. Research and analysis help inform
product design and/or performance and create understanding of market and
supply chain trends.
c. Contact Other Public Agencies. Other public agencies may have conducted a
similar procurement and can share information and valuable insight.
d. Seek Professional Assistance. In some instances, contractors or consultants
must be engaged to create complex or highly technical specifications.
Note: NEVER obtain or accept specifications directly from a potential bidder. This will
give the bidder an unfair competitive advantage, require that the bidder be disqualified,
and may result in protest actions or legal challenges.
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Section 6 – Sourcing and Standardization
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Section 6 – Sourcing and Standardization
6.1 Sourcing and Standardization Overview
It is city policy that purchases be based on competitive bidding whenever possible to maximize
the best value in the expenditure of public funds. Competition tends to be limited when goods
or services are sourced to one entity or standardized to one particular brand or manufacturer.
Careful consideration must be given before a decision is made to standardize products and/or
to request single or sole sourced procurements.
6.2 Single and Sole Sourcing
1. Single Source. Single source is defined as the selection of a good or service that may be
available from two or more sources, but there is compelling reason to select one
particular vendor.
2. Sole Source. Sole source is defined as the selection of a good or service that can only be
obtained from one supplier or manufacturer because of its specialized, proprietary or
unique in character.
Single and sole source procurements must be properly documented and approved in
accordance with city policies and procedures.
6.3 Standardization
1. Standardization. Standardization is an organized process to adopt one product or group
of products to be used by the city, such as particular computer hardware or software.
Product standardization may be utilized to create efficiencies, enhance safety, increase
productivity, promote brand consistency, or to foster interoperability.
Product standardization decisions are made by consensus of the executive team after
careful consideration and review of recommendations from staff.
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Section 7 – Special Policies and Programs
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Section 7 – Special Policies and Programs
7.1 Special Programs and Policies Overview
Depending on the amount and/or type of purchase, there are several policies and programs that
must be considered. These include:
➢ Application of Local Purchasing Preference;
➢ Minority, Disabled and Woman Owned Business Policy Statement;
➢ Environmentally Preferable Products; and
➢ Policies and Procedures for Purchases Utilizing Federal Grant Funds; and.
➢ Wage Theft
Each is described below.
7.2 Local Purchasing Preference
The City Council has established a 5% local purchasing preference to be given to local
businesses who respond to bidding opportunities or otherwise contract with the city (excluding
public works construction and professional services), under the following guidelines and
conditions.
1. Definition of Local Business. A local business is defined as a vendor or contractor who:
a. Has a fixed place of business in the city limits and the point of sale (for the
business’s sales tax reporting purposes) occurs within the city limits,
b. Is current in the payment of their business license tax, and
c. Is in compliance with city laws and does not owe money to the city.
2. Applicable Purchasing Methods. The local preference will be applied to competitive
bidding or letting contracts for the purchase of goods and applicable/associated services,
whether by formal bid, informal bid, or competitive proposal processes.
3. Making the Calculation. The local preference calculation will be determined as follows:
a. The purchasing coordinator will apply a 5% discount to the total bid pricing
provided by the local business for the purpose of calculating the lowest
responsive and responsible bidder.
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Section 7 – Special Policies and Programs
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b. If a competitive negotiation process is used, then the local business will be
assigned 5% of the total evaluation points.
4. Inapplicability. Application of the local business preference does not apply in the
following situations:
a. Purchases of goods and services through legal contracts of other governmental
jurisdictions or public agencies, or cooperative purchasing agreements;
b. Contracts for professional or legal services;
c. Purchases or contracts which are funded, in whole or in part, by a governmental
entity, or private and public grants and the laws, regulations or policies
governing such funding prohibit application of the local preference; and
d. Purchases made under emergency situations.
5. Reserved Rights. The local purchasing preference does not prohibit the Council or
purchasing coordinator from comparing quality or basing purchasing decisions on the
quality of goods and/or services.
6. Notification. Information regarding the local purchasing preference should be provided
to prospective bidders to the best extent possible, but failure to do so will not be
grounds for invalidation of any purchase order or contract awarded under the city’s
purchasing policies.
7.3 Minority, Disabled and Woman Owned Business Policy Statement
It is the policy of the City to ensure full and equitable opportunities for minority business
enterprises, women business enterprises, disabled business enterprises, and local small
businesses.
To assure equitable opportunities for participation, the purchasing coordinator or designated
staff carry out the following programs:
➢ Contractors must sign a certification that they and their subcontractors are in
compliance with the City’s Fair Employment Practices Policy
➢ City staff works to actively develop vendors in these disadvantaged classifications on a
day-to-day basis.
➢ Bidding opportunities will be provided to known vendors in targeted groups.
➢ The purchasing coordinator will assist in the development of technical assistance
programs for these disadvantaged classifications.
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Section 7 – Special Policies and Programs
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7.4 Environmentally Preferable Purchasing Policy
Purchases for goods and services shall ascribe, wherever and whenever possible, to the
Environmentally Preferable Purchasing Policy. The current policy can be found at the below
link.
https://www.cityofgilroy.org/DocumentCenter/View/13566/Reso-2007-50-Environmental-
Preferable-Purchasing-Policy
7.5 Policies and Procedures for Purchases Utilizing Federal Grant
Funding
When purchasing goods and services under a federal grant award, the city is required to follow
the provisions of 2 CFR Part 200 Subpart A §200.318 General Procurement Standards through
§200.326 Contract Provisions.
7.6 Wage Theft Prevention Policy Statement
It is the policy of the City that all parties contracting with the City must comply with all
applicable federal, state and local wage and hour laws including but not limited to the Federal
Fair Labor Standards Act (“FLSA”) and the California Labor Code. Suitable language regarding
this requirement should be in all contracts.
1. Disclosure. As a part of any City solicitation for goods and/or services, including public
works projects, contractor shall complete a “Bid Certification” (“Certification”) that
requires each potential contractor to disclose whether the contractor has been found by a
court or final administrative action of an investigatory government agency to have
violated federal, state, or local wage and hour laws within the past five (5) years from
the date of the submitted bid or proposal. For each disclosed violation, the potential
contractor shall provide a copy of (i) the court order and judgment and/or final
administrative decision; and (ii) documents demonstrating either that the
order/judgment has been satisfied, or if the order/judgment has not been fully satisfied,
a written and signed description of potential contractor’s efforts to date to satisfy the
order/judgment. The completed Certification shall be submitted by the potential
contractor to the City as a part of its bid or proposal.
2. Disqualification. The City may disqualify a potential contractor based on the disclosed
violation if the potential contractor has been found by a court or by final administrative
action of an investigatory government agency to have violated applicable wage and
hour laws on more than one (1) occasion or has one (1) unpaid wage judgment.
In evaluating whether to disqualify a potential contractor, the City should evaluate (i)
the amount of the judgment or final administrative decision; (ii) the number of
employees impacted by the prior violations; (iii) the size of the company and history of
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Section 7 – Special Policies and Programs
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compliance with wage and hour laws; (iv) the impact to the City; and (v) other factors
that may be appropriate.
3. Contract Termination. A current contractor found by a court or by final administrative
action of an investigatory government agency to have violated applicable wage and
hour laws, in the five (5) years prior to or during the term of the contract with the City,
may be in material breach of its contract with the City if the violation is not fully
disclosed and/or satisfied per City contract requirements. Such breach may serve as a
basis for contract termination and/or any other remedies available under law, including
a stipulated remediation plan.
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Section 8 – Purchasing-related Instructions and Procedures
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Section 8 – Purchasing-related Instructions and Procedures
This section contains several purchasing-related instructions and procedures.
8.1 Bid/Proposal Protest Procedures
Contractors who have submitted timely bids or proposals may wish to protest or appeal a
contracting decision or procurement made by the appropriate award authority. Protest actions
must follow the procedures provided below. Protests of appeals, which are not submitted in
accordance with these procedures, will not be considered.
1. Protesting Party. Only bidders or proposers who have submitted timely bids or
proposals can initiate a protest action or appeal.
2. Protest Procedures. The following procedural steps must be followed to consider a
protest:
a. The protest must be in writing and hand delivered or sent by registered mail.
Once received, it will be date stamped at the Finance Department counter.
b. The protest must be received within five working days after the announced
decision to award a contract.
c. Copies of the protest and all supporting documentation must be concurrently
transmitted to all other parties with a direct financial interest that may be
adversely impacted by the outcome of the protest. Such parties shall include all
other bidders who appear to have a reasonable prospect of receiving an award
depending upon the outcome of the protest.
d. The protesting party must bear all of its own costs and fees in conjunction with
protest or appeals processes.
3. Protest Filing. The written protest shall:
a. Include the name, street address, business phone number and email address of
the protestor.
b. Identify the project under protest by name, IFB, RFP or quotation number.
c. Contain a concise statement of the grounds for protest.
d. Include all supporting documentation.
4. Protest Review Prior to Award. The purchasing coordinator or designated staff will
withhold contract award pending disposition of the protest unless it is determined that
an emergency exists. Upon review with the City Attorney, the purchasing coordinator or
designee will respond in writing to the material issues raised in the protest no later than
ten working days after receipt of the protest.
5. Right of Appeal. The protestor may appeal the initial determination to the finance
director in writing within five working days after notification of the purchasing
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coordinator’s decision. The finance director will review the submitted information and
render a final decision within ten working days.
6. Protest Received and Reviewed After Contract Award. Protests after award will not be
considered unless the protest concerns a matter which arises after the award or could
not have been discovered or reasonably known prior to award.
8.2 Certificates of Insurance and Coverage Requirements
To minimize the city’s exposure to loss, all contractors must be appropriately insured and must
include the city as an “additional insured” on their insurance policy. Contractors are also
responsible for up-to-date insurance certificates with required policy endorsements that provide
the city with required insurance coverage and indemnity provisions.
The Human Resources/Risk Management Department maintains current insurance
requirements. Please refer to the insurance requirements in effect at the time of procurement.
8.3 Instructions to Bidders
Clear, concise and consistent instructions to bidders and proposers (hereafter “bidders”) are a
key part of the bidding process and help to enhance process clarity and ensure that prospective
offerors are informed of all city requirements.
The instructions inform bidders how to prepare and submit bids, establish mandatory
requirements, cover the bid addendum process, and how to withdraw or protest bids, among
many other items. The instructions for IFBs and RFPs are similar but contain important
differences due to the way contracts are awarded (low bid versus best value). The instructions
for each type of competitive process are contained in the bidding templates.
In some cases, modifications can be made to the instructions, but this must be done in
consultation with the purchasing coordinator and/or City Attorney’s Office.
8.5 Lease, Rental and Lease-to-Purchase Procurements
In some cases it may be beneficial to rent or lease equipment rather than purchasing it due to
funding availability, length of time the equipment is needed, etc. Under certain circumstances it
may be optimal to purchase the equipment at the end of the lease period. Equipment rentals or
leasing may make the best economic sense in these situations:
➢ Week-to-week or month-to-month rentals of short duration (less than one year).
➢ Leasing for short timeframes (more than six months but less than three years).
➢ Renting/leasing to evaluate equipment suitability prior to purchase. In these instances,
a “no-cost” purchase order may be a better option if the vendor is willing.
➢ Leasing equipment when a new or improved design is imminent and the leasing
charges can be applied to the purchase cost of the new item.
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➢ Securing a lease to purchase because the purchase price exceeds the current
appropriation.
When considering equipment rental, lease or lease-to-purchase agreements, it is highly
recommended that the following provisions be negotiated and included in the agreement:
➢ Lease and lease-to-purchase agreements should include a non-appropriation clause for
multi-year financing.
➢ Agreements under any scenario should include a “cancellation for convenience” clause.
➢ A percentage of payments should be applied to an eventual purchase.
➢ Leasing agreements must include the annual interest rate, along with a payment
schedule that shows each principal and interest payment (to be forwarded to the
Accounting Division).
➢ A lease-to-purchase agreement for capital equipment should have a minimum life
expectancy of five years.
Equipment leasing must be carefully considered. Leased equipment costs more than purchasing
outright, and if the equipment is not purchased, the city cannot take advantage of any residual
value.
8.5 Life Cycle Cost Analysis
Life cycle analysis, or total cost of ownership (TCO), considers the long-term cost of equipment
assets and citywide systems such as the financial system. Costs include acquisition, installation,
ongoing maintenance and end of life disposal.
8.6 Service Provider Evaluation
When preparing to contract for services, it is important to evaluate service providers to
determine whether they are independent contractors or if they are more appropriately
characterized as temporary employees.
8.7 Surplus Property Disposal
All city equipment, supplies, and vehicles (“personal property” or “property”) will eventually
reach the end of their useful life and must be disposed of, and to the best extent possible,
generate revenue through sale or traded-in when new equipment is purchased. The following
procedures apply to the disposal of surplus property:
➢ Surplus Disposal. It is the responsibility of department heads to determine when an
item is obsolete or excess surplus property. After such determination is made, the
surplus property may be transferred to another department or used as a trade-in for
new equipment. Surplused items may be donated, sold through a competitive sealed
bid process, or sold at public auction to another governmental or non-profit entity. For
final disposal, City Council shall approve of items to be surplused.
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➢ Sale of Surplus Property. As required by Section 2.43(c)(6) of the City Code, the sale of
surplus property is subject the approval of the City Administrator except that sale of
property having a value consistent with those classified as fixed assets by the fixed asset
accounting rules in effect at the time of the request must be approved by Council.
➢ Property List. The department surplusing an item shall submit a list of property items,
the current value, and the asset number, if applicable, to the purchasing coordinator. The
purchasing coordinator will periodically compile a list of excess items and provide it to
all departments for review, and will subsequently obtain approval from the City
Administrator and/or City Council. Upon approval, the following three options are
available to dispose of the items:
o Sale to Another Governmental Entity. Surplus personal property may be sold
at fair market value to another governmental entity (or non-profit organization).
Such entity will have no more than 3 weeks to accept or reject the offer. If
accepted, the entity will be invoiced by Accounts Receivable. All applicable sales
tax shall be included. Note: The receiving entity is responsible for transportation
and liability of the item
o Auction. This option provides a convenient and efficient means of disposing
surplus. After an item has been declared surplus, the purchasing coordinator
will coordinate with the surplusing department to arrange for pickup by the
auction company.
o Competitive Bids. The purchasing coordinator may require that sealed bids be
obtained for certain surplus equipment, such as vehicles with considerable
resale value. Sealed bids shall be advertised in a newspaper of general
circulation (if available), and on the City’s website, 10 days prior to the bid
opening. Prospective bidders shall have the opportunity to evaluate the
equipment prior to bid opening as prescribed by the purchasing coordinator.
Award will be made to the bidder most responsive to the City’s needs.
The equipment shall be bid upon in “as-is” condition with no warranty, and a
10% deposit in the form of a money order or cashier’s check must be submitted
at the time of bid opening, with a balance due within 7 calendar days. Deposits
will be returned to unsuccessful bidders within 14 calendar days.
➢ Donations of Surplus and Preferred Recipients. In order of preference, surplus items
may be donated to: 1) the Gilroy Unified School District; 2) the Gilroy Chamber of
Commerce. Surplus property unlikely to generate significant revenue and that are not
transferred to other departments may be donated to other public agencies, to Gilroy’s
sister cities, or to non-profit organizations.
Any donation of surplus property to a non-profit organization shall be approved by the
City Council upon findings that the non-profit is qualified under section 501(c)(3) of the
Internal Revenue Code and that the donation will benefit the City and its constituents.
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All donations pursuant to this section shall be without warranty, express or implied,
and the transferee shall agree to defend, indemnify and hold harmless the City, its
officers and employees, from any claim, cause of action, damage, loss or liability arising
out of the condition of the property or its use by the organization or subsequent
transferee.
➢ Specialized Police Department Surplus. Upon the request of the Gilroy Police Chief
and with City Council approval, surplus items of a unique nature, i.e., guns, vests, and
other protective equipment may be disposed of in an appropriate manner to suitable
recipients. Disposal shall incorporate the Range Master’s Policy in regard to the sale of
guns to a Gilroy police officer or other law enforcement officer.
➢ Stolen Property. All stolen property shall be held by the police department for a period
of 6 months. Periodic lists shall be prepared by the police department and submitted to
the purchasing coordinator, to be agendized and declared surplus. Items will be
disposed of in the most equitable manner. The only exception is Bicycles, which shall
only be sold at public auction once declared surplus.
➢ Tracking Surplus. Regardless of the value established in policy, departments shall
furnish a memorandum to the purchasing coordinator for tracking low value items.
Broken or unrepairable items considered trash need not be listed in the memorandum.
➢ Revenue. The revenue received for the sale of surplus property shall be deposited in
the General Fund or other appropriate fund for certain equipment sales.
8.8 Used Automobile Purchases
For efficiency purposes, the Council has waived formal bidding procedures for purchasing used
vehicles under the following conditions:
➢ A budgeted appropriation exists.
➢ A determination is made by the fleet manager that purchasing a used vehicle is in the
city’s best interest.
➢ All Gilroy used-car vendors are notified of the city’s intent to purchase.
The following procedures and requirements must be followed to purchase a used vehicle:
➢ The fleet manager will develop specifications based on the user department’s needs.
➢ The fleet manager will solicit at least three written quotes utilizing informal
procurement procedures; two of which must be solicited from Gilroy vendors.
➢ The used vehicle must have less than 25,000 miles and be less than 2 years old.
➢ A thorough inspection of each vehicle under consideration will be performed by Fleet
Division staff, who will make a recommendation for purchase.
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➢ The fleet manager will submit a purchasing requisition for department head
authorization.
➢ After the issuance of a purchase order, Fleet Division staff will arrange for
transportation to the city and ensure vehicle registration. They are also responsible for
submitting sale documentation to accounts payable in a timely manner.
➢ The fleet manager will prepare a report for Council review.
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Section 9 – Glossary of Terms
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Section 9 – Glossary of Terms
9.1 Definitions
This section defines relevant purchasing terms and terminology in use by the City of Gilroy.
Agreement. A mutual, written understanding between two or more competent parties, whereby
one party agrees to perform as defined in the agreement and the other party agrees to
compensation for the performance rendered in accordance with the agreement conditions.
Agreement and contract may be used synonymously.
Amendment. An agreed upon modification to an existing contract.
Appropriation. Authorization by the City Council to expend budgeted funding for city operations
and infrastructure, or other designated purposes.
Award. The acceptance of a bid or proposal; the presentation of a purchase agreement by the
award authority to a bidder or offeror.
Award Authority. The governing body or staff person authorized to approve the purchase of
goods and services on behalf of the city; the staff person(s) authorized to approve or execute
procurement contracts and otherwise legally bind the city.
Best Value Procurement. A procurement that is awarded based on factors in addition to price. Best
value procurements are mainly conducted through the competitive proposal process.
Bid Addendum. A bid addendum is a document issued to all known participants (“planholders”)
in a competitive bid process that makes a change to the bid documents/project (i.e., changes to
specifications), or process (like a bid due date extension).
Bid Opening. The process in which sealed bids are publicly opened, in the presence of at least one
witness, at the time and place specified in the invitation for bids.
Blanket Purchase Order (BPO). A limited-term contract for goods and/or services based on unit
pricing, typically for one-year renewable periods. BPOs may be established with indefinite
quantities, allowing end users flexibility to order products when needed, or for on-call services.
Change Order. A contract modification consisting of additions or reductions in work or materials
approved by the City Council or purchasing coordinator.
Commodity. Goods consisting of supplies, materials and equipment.
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Competitive Bidding. The process of soliciting and obtaining formal and informal bids, including
price quotations, from competing sources, by which an award is made to the lowest responsive
and responsible bidder.
Competitive Proposals. The process of soliciting and obtaining formal and informal proposals
from competing sources, by which an award is made to the proposer whose solution provides the
best value to the city. The award may be made based on factors in addition to price, e.g., a higher
price can be paid for goods and/or services if the value can be justified.
Conflict of Interest. A conflict of interest in conjunction with a city purchase is a situation where
an employee or a member of the employee’s family stands to benefit financially from the
procurement.
Contract. See Agreement.
Cooperative Procurements. A variety of arrangements whereby two or more public entities
purchase goods and/or services from the same supplier or multiple suppliers using a single
competitive bid or proposal; the combining of the requirements of two or more public entities to
leverage the benefits of volume purchases, including administrative savings and other
demonstrable advantages.
Design-build. A public works contracts procurement method in which both the design and
construction of a project are procured from a single entity.
Design-build contract. A public works contracts equal to or in excess of one million dollars
($1,000,000) for a project to be constructed using a design-build process.
Design-build entity. A partnership, corporation or other legal entity that provides licensed
contracting, architectural or engineering services for a design-build contract.
Design professional. A professional, either City staff or an outside consultant licensed by the State
of California, who develops the criteria package which may include, but is not limited to, facility
program, design criteria, performance specifications and other project-specific technical materials.
Encumbrance. An accounting entry that commits an appropriated dollar amount to be spent.
Formal Sealed Bid. A procurement method for goods and/or services anticipated to be greater
than $100,000 whereby sealed Invitations for Bids (IFBs) are submitted and publicly opened, with a
contract awarded to the lowest responsive and responsible bidder.
Formal Sealed Proposal. A procurement method for goods and/or services anticipated to be
greater than $100,000 whereby sealed Requests for Proposals (RFPs) or similar proposal documents
are submitted and reviewed by an evaluation committee based on established criteria, with a
contract awarded to the responsive and responsible proposer whose solution provides the best
overall value to the city.
General Services. Work performed or services rendered by independent contractors such as
custodial services, building and equipment maintenance, machinery and equipment rental, and
utility services, excluding contracts for public works.
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Goods. Supplies, materials and equipment to be furnished or used by any department of the city,
including items purchased by the city and furnished to contractors for use in public works projects.
Informal Bid or Proposal. Competitive bids or proposals anticipated to be $100,000 or less
conducted under informal procurement procedures.
Invitation for Bids (IFB). The type of bid document typically used in a competitive (formal) sealed
bidding process. Components include but may not be limited to a bid invitation, instructions to
bidders, bid schedule(s), terms and conditions and technical specifications.
Job Order Contract. As-needed contracts for small construction or maintenance projects and/or for
urgent or emergency repairs where time is of the essence. These types of contracts are bid on a unit
cost basis and awarded based on not-to-exceed amounts approved by the appropriate award
authority. Job Order Contracts may be established as Master Agreements.
Local Purchasing Preference. A 5% bid preference granted to local bidders whose principal place
of business is located within city limits, subject to policy limitations.
Lowest Responsive and Responsible Bidder. The bidder to be awarded a contract who fully
complies with all material bid requirements, whose past performance and financial capacity is
determined to be acceptable and has offered the lowest price.
Master Agreement. A contract that is awarded to multiple qualified providers pursuant to a
primary agreement with a standard set of terms and conditions, typically created under a
competitive proposal process. Once established, services are distributed among providers with
discrete project work negotiated through task orders; also referred to as Master Service
Agreements (MSA) or Master Professional Service Agreements (MPSA).
Piggybacking. A form of intergovernmental cooperative purchasing whereby the city utilizes the
contract pricing and terms of another government agency.
Prevailing Wages. The wage rates, including fringe benefits, paid to a majority of workers in a
geographic area for the same type of work on similar projects as established by the California
Department of Industrial Relations.
Professional Services. Services provided by a person or firm engaged in a profession based on
highly specialized and/or technical knowledge or skill; services considered distinct and unique to
such a degree that bidding may not be feasible, if appropriately justified and documented. Some
examples include accountants, attorneys, artists, architects, engineers and physicians.
Public Works. The construction, alteration, repair, or improvement of any public structure,
building, road, or other public improvement of any kind, including demolitions, and the
construction and installation of drainage systems, lighting and signaling systems, sewer and water
systems, and park and recreational facilities.
Purchasing Coordinator. Designated finance staff responsible for issuing bid #s, coordinating the
issuance and opening of bids and proposals, reviewing requisitions, and issuing purchasing
orders.
Agenda Item 7.3
Page 65 of 768
Purchasing Policy
Section 9 – Glossary of Terms
42
Purchase Order. A legally binding contract issued by purchasing staff to a vendor which includes
the terms and conditions of a transaction.
Purchase Requisition. The document required to be submitted through the financial system to
begin the procurement process. Purchase requisitions must be properly documented and approved
for the procurement process to proceed.
Qualified list of design-build entities. A list of design-build entities selected based on a
competitive selection process and who are determined to be qualified to act as a design-build
entity for the City on public works projects equal to or in excess of one million dollars ($1,000,000).
Ratification. The process by which an unauthorized purchase is approved or ratified by the
appropriate award authority after-the-fact.
Request for Proposals (RFP). The solicitation document used to solicit proposals for goods and/or
services from potential providers.
Request for Qualifications (RFQL). Also referred to as Requests for Statements of Qualifications
(RSQ), this type of solicitation seeks to establish qualified applicants or pools of applicants for as-
needed services, sometimes under Master Professional Service Agreements (MPSA); most
commonly used for architectural and engineering services or other highly specialized consultants.
Request for Quotations (RFQ). The type of bid document used for obtaining competitive quotes
through the informal procurement procedures.
Responsible Bidder. A bidder is considered responsible if they possess the demonstrated ability,
capacity, experience and skill to provide the goods and/or services in accordance with the city’s
requirements; has a record of satisfactory or better performance under prior contracts with the city
and other entities; and has complied with laws, regulations and guidelines governing prior or
existing contracts.
Responsive Bidder. A person or entity who has submitted a bid which conforms in all material
respects to a bid or proposal solicitation.
Single Source. A good or service that may be available from more than one source, but a
compelling justification can be made to obtain the good or service from one particular vendor.
Sole Source. A situation where a good or service can only be obtained from one source due to its
proprietary or specialized nature.
Specification. A precise description of the physical characteristics, quality, or desired outcomes of
a commodity to be procured, which a supplier must be able to produce or deliver to be considered
for award of a contract. There are two types of specifications: design and performance.
Standardization. The process to adopt one product or group of products to be used by the city,
such as particular computer hardware or software.
Agenda Item 7.3
Page 66 of 768
Purchasing Policy
Section 9 – Glossary of Terms
43
Surplus Property. Supplies, materials, and equipment that is no longer used or has become
obsolete, to be sold, exchanged or donated by the purchasing coordinator in accordance with
policy provisions covering surplus property donations.
Wage Theft. Wage theft occurs when employers do not pay workers according to the law.
Examples of wage theft include paying less than minimum wage, not paying workers overtime,
not allowing workers to take meal and rest breaks, requiring off-the-clock work, or taking workers'
tips.
Agenda Item 7.3
Page 67 of 768
Page 1 of 2
City of Gilroy
STAFF REPORT
Agenda Item Title:Approval of the Gilroy Tourism Business
Improvement District (GTBID) Annual Report as
Submitted by Visit Gilroy/California Welcome Center
Gilroy for the Period of January 1, 2022 Through
December 31, 2022
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:Administration
Submitted By:Bryce Atkins, Assistant to the City Administrator
Prepared By:Bryce Atkins, Assistant to the City Administrator
STRATEGIC PLAN GOALS Promote Economic Development Activities
RECOMMENDATION
Approve the Gilroy Tourism Business Improvement District (GTBID) annual report as
submitted by Visit Gilroy/California Welcome Center Gilroy for the period of January 1,
2022 through December 31, 2022.
BACKGROUND
Visit Gilroy/California Welcome Center (VG/CWC) Gilroy Board of Directors
representing the Gilroy Tourism Business Improvement District (GTBID) has submitted
the attached report pursuant to Section 36650 of the Street and Highway Code.
Effective in 2013, GTBID provides a steady and dedicated funding source to the
(VG/CWC) through an assessment levied on lodging businesses within the GTBID
boundaries.
ALTERNATIVES
None – This is an informational item.
Agenda Item 7.4
Page 68 of 768
Approval of the Gilroy Tourism Business Improvement District (GTBID) Annual Report as Submitted
by Visit Gilroy/California Welcome Center Gilroy for the Period of January 1, 2022 Through
December 31, 2022.
City of Gilroy City Council Page 2 of 2 April 3, 2023
FISCAL IMPACT/FUNDING SOURCE
None – This is an informational item.
PUBLIC OUTREACH
This item was included in the publicly posted agenda for this meeting.
Attachments:
1. GTBID Annual Report for the Period of January 1, 2022 Through December 31,
2022.
Agenda Item 7.4
Page 69 of 768
4
5
6
To:Gilroy City Council
From: Gilroy Visitors Bureau, dba Visit Gilroy Board of Directors
representing Gilroy Tourism Business Improvement District (GTBID)
Date: April 3, 2023
Subject: Gilroy Tourism Business Improvement District (GTBID) Report
for January 1, 2022 – December 31, 2022
Pursuant to Section 36650 of the Street and Highway Code, the Gilroy Tourism
Business Improvement District (GTBID) is submitting the following report to the
Gilroy City Council for approval and to be filed with the City Clerk.
The Management District Plan identifies the Gilroy Visitors Bureau, dba Visit Gilroy
Board of Directors to serve as the Owner’s Association for GTBID. The Owner’s
Association serves as a private, nonprofit entity that administers and implements
the improvements, services, and activities of GTBID as specified in the Management
District Plan.
Items 1 – 7 as identified in the Management District Plan Reporting Requirements:
1. Proposed changes in the
boundaries, benefit zones or
classification of business of GTBID
None.
2. Services, improvements, and
activities provided for the period
January 1, 2021 – December 31,
2021
Public relations, print ads, google
adwords, social media campaigns,
online marketing, trade shows,
website support, research and google
analytics
3. Cost of providing the services for
this reporting period
Advertising and Marketing - $295,335
Administration - $63,458
City Collection Fee - $7,181
Reserve/Renewal - $2,500
Total Amount - $368,474
4. Any proposed changes to basis and
method of levying the assessments
None. The GTBID annual assessment
rate is 2% of Taxable Rates, as stated
Agenda Item 7.4
Page 70 of 768
4
5
6
on the City’s Quarterly Transient
Occupancy Tax Reporting Form.
5. Method and basis of levying
assessments collected for the
reporting period
The city receives the assessment
revenue along with the quarterly TOT
collections from each business located
in the boundaries of the GTBID. The
city then forwards the assessments to
Gilroy Visitors Bureau, dba Visit Gilroy
to manage and implement the GTBID
programs.
6. Amount of any surplus revenues to
be carried over from reporting
period
$79,00
7. Amount of any contributions to be
made from sources other than the
assessments levied
None.
2022 Strategic Marketing Plan Results
Smart Targets 2021
Actual
2022
Goals
2022
Actual
Website
Pageviews 249,584 232,996 247,064
Website Total
Sessions 172,207 158,623 160,267
Website Users 138,681 132,113 135,827
Hotels Page
Pageviews 15,792 16,895 19,304
Hotel Page
Conversions 35.80%54.82%30.57%
Collateral
Downloads 3,577 3,333 3,945
Agenda Item 7.4
Page 71 of 768
4
5
6
Submissions
to CCTC 16 16 17
Submissions
to Visit CA 25 20 24
Gilroy Tourism Business Improvement District (GTBID)
Business Assessees Listing
Hotel Address
Days Inn 8292 Murray Avenue
Gilroy, CA 95020
Budget Motels/Whiterock 8897 Monterey Road
Gilroy, CA 95020
Garlic Farm Inn 5920 Travel Park Circle
Gilroy, CA 95020
Gilroy Inn 611 Leavesley Road
Gilroy, CA 95020
Hilton Garden Inn 6070 Monterey Road
Gilroy, CA 95020
Kings Rest Motel 8175 Monterey Road
Gilroy, CA 95020
Best Western Plus Forest Park Inn 375 Leavesley Rd,
Gilroy, CA 95020
Motel 6 6110 Monterey Road
Gilroy, CA 95020
Travel Inn 5530 Monterey Road
Gilroy, CA 95020
Oaks Motel 8065 Monterey Road
Gilroy, CA 95020
Pacheco Pass 570 Old Gilroy Street
Gilroy, CA 95020
Quality Inn & Suites 8430 Murray Avenue
Agenda Item 7.4
Page 72 of 768
4
5
6
Gilroy, CA 95020
Hampton Inn 5975 Travel Park Cir, Gilroy, CA
95020
Comfort Inn 8435 San Ysidro Avenue
Gilroy, CA 95020
Econo Lodge 360 Leavesley Rd,
Gilroy, CA 95020
Agenda Item 7.4
Page 73 of 768
11:29 AM
01 /14/23
Accrual Basis
Ordinary Income/Expense
Income
80000 · TBID Income
Total Income
Gross Profit
Expense
97010 • TBID Personnel/Administration
97011 • TBID Executive Director
97014 · P/R Taxes & Simple IRA
97015 · Workers Compensation Ins
97019 · Auto/Mileage Expense
97016 · Accounting/Legal Expenses
97017 · Office Supplies
97018 · Miscellaneous Expenses
Total 97010 · TBID Personnel/Administration
97020 · TBID Collection Costs/City of G
97030 · TBID Reserve
97040 • TBID Advertising/Marketing
97056 · Tourism Coordinator
97041 · Public Relations
97043 · Social Media/SEO Mgmt/Website
97044 · Collateral
97046 · Advertising
97047 · Research & Measurement
97048 · Marketing Services
97050 · Postage-VG Fullfillment Request
97052 · Conferences & Travel
�
97057 · Payroll Taxes
97058 · Health Insurance .....J\ 97059 · Sales & Event Marketing \J"', Total 97040 · TBID Advertising/Marketing
Total Expense
For management purposes only.
Dec22
92,614.71
92,614.71
92,614.71
7,389.70
334.05
34.17
0.00
258.50
747.20
0.00
8,763.62
1,852.29
625.00
2,870.10
587.92
7,784.27
0.00
6,834.45
0.00
991.13
15.48
0.00
219.58
0.00
0.00
19,302.93
30,543.84
Gilroy Visitors Bureau dba Visit Gilroy
P & L Budget Performance - TBID
December 2022
Budget
81,250.00
81,250.00
81,250.00
3,333.35
366.65
33.35
100.00
200.00
125.00
25.00
4,183.35
1,625.00
1,625.00
2,708.35
1,500.00
4,000.00
833.35
7,333.35
833.35
1,500.00
300.00
416.65
325.00
400.00
1,666.65
21,816.70
29,250.05
%of Budget
113.99%
113.99%
113.99%
221.69%
91.11%
102.46%
0.0%
129.25%
597.76%
0.0%
209.49%
113.99%
38.46%
105.97%
39.2%
194.61%
0.0%
93.2%
0.0%
66.08%
5.16%
0.0%
67.56%
0.0%
0.0%
88.48%
104.42%
Jan-Dec22
359,063.15
359,063.15
359,063.15
54,090.42
3,906.66
384.20
526.69
3,213.06
1,337.03
0.00
63,458.06
7,181.26
2,500.00
26,166.60
19,680.82
78,900.58
8,192.05
107,454.48
2,231.10
22,067.77
1,366.04
2,011.00
2,104.30
0.00
25,160.84
295,335.58
368,474.90
Budget
325,000.00
325,000.00
325,000.00
40,000.00
4,400.00
400.00
1,200.00
2,400.00
1,500.00
300.00
50,200.00
6,500.00
6,500.00
32,500.00
18,000.00
48,000.00
10,000.00
88,000.00
10,000.00
18,000.00
3,600.00
5,000.00
3,900.00
4,800.00
20,000.00
261,800.00
325,000.00
% of Budget
110.48%
110.48%
110.48%
135.23%
88.79%
96.05%
43.89%
133.88%
89.14%
0.0%
126.41%
110.48%
38.46%
80.51%
109.34%
164.38%
81.92%
122.11%
22.31%
122.6%
37.95%
40.22%
53.96%
0.0%
125.8%
112.81%
113.38%
Annual
Budget
325,000.00
325,000.00
325,000.00
40,000.00
4,400.00
400.00
1,200.00
2,400.00
1,500.00
300.00
50,200.00
6,500.00
6,500.00
32,500.00
18,000.00
48,000.00
10,000.00
88,000.00
10,000.00
18,000.00
3,600.00
5,000.00
3,900.00
4,800.00
20,000.00
261,800.00
325,000.00
Page1 of2
Agenda Item 7.4
Page 74 of 768
Agenda Item 7.4
Page 75 of 768
Page 1 of 4
City of Gilroy
STAFF REPORT
Agenda Item Title: Adopt the 2022 Sewer System Master Plan
Meeting Date: April 3, 2023
From: Jimmy Forbis, City Administrator
Department: Public Works
Submitted By: Daryl Jordan, Public Works Director
Prepared By: Michael Lewis, Management Analyst
STRATEGIC PLAN GOALS Maintain and Improve City Infrastructure
RECOMMENDATION
Approve a resolution to adopt the 2022 Sewer System Master Plan.
BACKGROUND
Cities rely on sewer master plans to evaluate system capacity and conditions to provide
comprehensive recommendations for replacements and improvements to their sewer
system. The City last developed a Sewer System Master Plan in 2004 (2004 Master
Plan) which identified capacity deficiencies in the existing sewer system and
recommended improvements to alleviate existing deficiencies and serve future
developments in the Gilroy Planning Area.
The City operates and maintains the sewer system covering most of the area within the
City Limits, including the system that carries flows from the City of Morgan Hill to the
regional South County Regional Water Authority (SCRWA) wastewater treatment plant
(SCRWA WWTP). The City provides sewer collection services for approximately
17,000 residential, commercial, industrial, and institutional accounts. The City’s
collection system consists of approximately 167 miles of up to 60-inch gravity sewer
pipes that convey flows toward the SCRWA WWTP. The City’s sewer system consists
of 163.13 miles of gravity sewers, 4,026 manholes, 0.16 miles of force mains, three (3)
lift stations, and one (1) pump station.
The SCRWA WWTP is an 8.5 million gallons per day (MGD) Average Dry Weather Flow
(ADWF) primary, secondary, and tertiary treatment facility. The treatment facility is
Agenda Item 11.1
Page 76 of 768
City of Gilroy City Council Page 2 of 4 April 3, 2023
located at the end of Southside Dr. The original plant was completed in 1990 with a
plant expansion in 2007 to provide the plant with current capacity and technology. The
plant is currently operating at an average flow of 6.54 MGD with a low of approximately
4.78 MGD and a peak of approximately 10 MGD in 2019. The current expansion project
will increase the current capacity of 6.54 MGD to 8.5 MGD.
The City Council approved Akel Engineering Group, Inc. to prepare the 2022 Master
Plan and a concurrent Water System Master Plan and Storm Drainage Master Plan in
August 2019. These documents were coordinated for consistency with the
development of the City’s 2040 General Plan.
The 2022 Master Plan includes detailed mapping of the sewer system and the
development of a digital hydraulic model that can be used to project and evaluate the
impacts of development and population growth.
ANALYSIS
The 2022 Master Plan evaluated the City’s sewer collection system and recommended
capacity improvements necessary to service the needs of existing users and the future
growth of the City. This 2022 Master Plan is intended to serve as a tool for planning and
phasing the construction of future sewer collection system infrastructure for the
projected buildout of the City’s service area. The area and horizon for this 2022 Master
Plan is based on the City’s 2040 General Plan.
The City Council authorized Akel Engineering Group, Inc. to perform the following tasks:
1. Summarize the City’s existing sewer collection system facilities.
2. Document growth planning assumptions and known future developments.
3. Summarize the sewer system performance criteria and design storm event.
4. Project future sewer flows.
5. Update and validate the City’s hydraulic model based on the City’s Geographic
Information Systems (GIS).
6. Evaluate the adequacy of capacity for the sewer collection system facilities to
meet existing and projected peak dry weather flows and peak wet weather flows.
7. Recommend a Capital Improvement Program (CIP) with an opinion of probable
construction costs.
8. Perform a capacity allocation analysis for cost sharing purposes.
9. Develop a 2022 Sewer System Master Plan Report.
RESULTS
The 2022 Sewer System Master Plan provided recommendations for improvements
needed to mitigate existing deficiencies and expand the system to service future growth
Agenda Item 11.1
Page 77 of 768
City of Gilroy City Council Page 3 of 4 April 3, 2023
identified in the 2040 General Plan. The recommended capital improvement program
(Table 8.2) is attached as Attachment 1.
The Master Plan indicates that overall that the City’s sewer system is in good condition
but in need of improvements to mitigate some specific deficiencies and that future
capacity projects will be development driven. Sixteen segments out of 34 potential
projects of the previous master plan were constructed, totaling over $2,530,000. Many
of these projects were for the shared trunk line passing through the city with Morgan
Hill. In total, the 2022 Master Plan recommends 15 pipeline improvement and
replacement projects in six (6) sub-trunk systems. The list includes projects from the
2004 Master Plan that were not completed and new projects needed to accommodate
future growth based on the updated Sewer System modeling. The projects identified
will be added to the City’s Capital Improvement Program and budget.
In total, the plan recommends seven capacity projects totaling nearly $7.84 million and
eight projects totaling $4.88 million that will need to be constructed as the City adds
more residential units. The cost allocation of the projects is broken up between Existing
and Future users based on existing capacity needs and capacity need as more
development occurs.
Sub-Trunk
Number of
Replacement
Projects
Number of
New Projects
Cost
Allocation to
Existing
Users
Cost
Allocation to
Future Users
Santa Teresa –
Long Meadow 1 0 $689,302 $445,498
Welburn 2 0 $1,246,051 $127,049
Forest-
Swanston 2 0 $1,695,122 $90,478
Old Gilroy 2 0 $457,674 $55,126
Uvas Park 5 1 $1,858,470 $3,019,230
Thomas 2 0 $1,897,061 $1,142,739
Total Cost $7,843,681 $4,880,119
The master plan also includes a section identifying needed repairs to the Morgan Hill-
Gilroy joint trunk line resulting from a recently completed condition assessment. The
cost of the repairs that are needed will be split 50%/50% between the two cities. The
priority repairs will be added to the Capital Improvement Program. The repairs
identified for the trunk line include:
• Five Immediate Projects on Pipelines for a total of $1,082,000
• Forty Immediate Projects on Manholes for a total of $2,417,900
• Various Intermediate Projects on Pipelines for a total of $16,916,800
Agenda Item 11.1
Page 78 of 768
City of Gilroy City Council Page 4 of 4 April 3, 2023
ALTERNATIVES
Council may reject or modify the Adoption of the 2022 Sewer Master Plan. This option is
not recommended due to the requirements to maintain the citywide sanitary sewer
system.
FISCAL IMPACT/FUNDING SOURCE
The City has two sewer funds utilized to fund the capital improvements and the annual
operational and maintenance needs. The Sewer Impact Fund, which collects revenues
in the form if impact fees from developments that impact future growth, primarily funds
infrastructure/capital costs attributable to future users for future capacity needs. The
Sewer Operations fund funds the current annual operational, maintenance, and capital
costs to repair and maintain existing infrastructure. The Sewer Impact (future users) and
Sewer Operation (existing users) funds have a projected FY23 ending fund balance of
$15.7 million and $20.0 million, respectively.
Of the total $12.7 million capital improvements identified in the master plan,
approximately $7.8 million are attributable to existing users – to be funded by Sewer
Operations Fund, and $4.9 million are attributable to future users - to be funded by the
Sewer Impact Fund. The 2024 Master Plan capital improvements are in addition to the
existing capital improvements identified by staff.
While both funds have fund balances to fund the 2022 Master Plan’s identified capital
needs, a typical next step after the Master Plans are updated is to review and update
the utility user fees, and the development impact fees to incorporate the identified
existing and future growth capital improvements and adjust the fees accordingly to
ensure capital and operational needs are adequately funded for a period. The City is
undergoing a rate study for sewer user fees and will consider the projects contemplated
in this Master Plan and the CIP to help determine the rate proposals in the next few
months. Staff will plan to review and update the sewer impact fee as a project in the
departmental workplan in the upcoming fiscal year.
NEXT STEPS
With Council adoption of the 2022 Master Plan, staff will incorporate the projects into
the Capital Improvement Program and plan for delivering the proposed projects. State
approval is not required.
Attachments:
1. Sewer System Master Plan – Attachment 1
2. Sewer System Master Plan Capital Improvement Program List
3. Sewer System Master Plan Draft Resolution
Agenda Item 11.1
Page 79 of 768
City of Gilroy APRIL 2023
2023 Sewer System Master Plan
Agenda Item 9.1
Page 80 of 768
CITY OF GILROY
2023
SEWER SYSTEM
MASTER PLAN
Final
March 2023
Agenda Item 9.1
Page 81 of 768
7 4 3 3 N. F I R S T S T R E E T , S U I T E 1 0 3 • F RE S N O , C A L I F O R N I A 9 3 7 2 0 • ( 5 5 9 ) 43 6-0 6 0 0 • F A X ( 5 5 9 ) 4 3 6 - 0 6 22
www.akeleng.com
Smart Planning Our Water Resources
March 28, 2023
City of Gilroy
7351 Rosanna Street
Gilroy, CA 95020
Attention: Gary Heap, P.E.
City Engineer
Subject: 2023 Sewer System Master Plan – Final Report
Dear Gary:
We are pleased to submit the final report for the City of Gilroy Sewer System Master Plan. This
master plan is a standalone document, though it was prepared as part of the integrated
infrastructure master plans for the water, sewer, and storm drainage master plans. The master
plan documents the following:
Existing collection system facilities, acceptable hydraulic performance criteria, and
projected wastewater flows consistent with the Urban Planning Area
Development and calibration of the City’s GIS-based hydraulic sewer collection system
model.
Capacity evaluation of the existing sewer system with improvements to mitigate existing
deficiencies and to accommodate future growth.
Capital improvement program (CIP) with an opinion of probable construction costs and
suggestions for cost allocations to meet AB 1600.
We extend our thanks to you, Sharon Goei, Community Development Director; Daryl
Jordan, Director of Public Works; and other City staff whose courtesy and
cooperation were valuable components in completing this study.
Sincerely,
AKEL ENGINEERING GROUP, INC.
Tony Akel, P.E.
Principal
Enclosure: Report
Agenda Item 9.1
Page 82 of 768
Acknowledgements
City Council
Marie Blankley, Mayor
Dion Bracco, Mayor Pro Tempore
Rebeca Armendariz
Tom Cline
Zach Hilton
Carol Marques
Fred Tovar
Management Personnel
Jimmy Forbis, City Administrator
Daryl Jordan, P.E., Director of Public Works
Gary Heap, P.E., City Engineer
Jorge Duran, P.E., Senior City Engineer
Sharon Goei, Community Development Director
Matt Jones, Deputy Director of Public Works
Other City Engineering, Planning, and Operations Staff
Agenda Item 9.1
Page 83 of 768
City of Gilroy
Sewer System Master Plan
TABLE OF CONTENTS PAGE NO.
March 2023 i City of Gilroy
Sewer System Master Plan
0.0 EXECUTIVE SUMMARY ................................................................................................. ES-1
ES.1 STUDY OBJECTIVES ..................................................................................... ES-1
ES.2 INTEGRATED APPROACH TO MASTER PLANNING .................................... ES-1
ES.3 STUDY AREA DESCRIPTION......................................................................... ES-2
ES.4 SYSTEM PERFORMANCE AND DESIGN CRITERIA ..................................... ES-2
ES.5 EXISTING SEWER COLLECTION SYSTEM OVERVIEW ............................... ES-5
ES.6 SEWER FLOWS .............................................................................................. ES-5
ES.7 HYDRAULIC MODEL DEVELOPMENT AND CALIBRATION .......................... ES-9
ES.8 CAPACITY EVALUATION ............................................................................... ES-10
ES.9 CAPITAL IMPROVEMENT PROGRAM ........................................................... ES-11
1.0 CHAPTER 1 - INTRODUCTION ...................................................................................... 1-1
1.1 BACKGROUND ............................................................................................... 1-1
1.2 SCOPE OF WORK .......................................................................................... 1-1
1.3 INTEGRATED APPROACH TO MASTER PLANNING .................................... 1-3
1.4 PREVIOUS MASTER PLANS .......................................................................... 1-3
1.5 RELEVANT REPORTS ................................................................................... 1-3
1.6 REPORT ORGANIZATION .............................................................................. 1-4
1.7 ACKNOWLEDGEMENTS ................................................................................ 1-5
1.8 UNIT CONVERSIONS AND ABBREVIATIONS ............................................... 1-5
1.9 GEOGRAPHIC INFORMATION SYSTEMS ..................................................... 1-8
2.0 CHAPTER 2 – PLANNING AREA CHARACTERISTICS ................................................ 2-1
2.1 STUDY AREA DESCRIPTION......................................................................... 2-1
2.2 SEWER SERVICE AREAS AND LAND USE ................................................... 2-1
2.3 HISTORICAL AND PROJECTED POPULATION............................................. 2-9
3.0 CHAPTER 3 – SYSTEM PERFORMANCE AND DESIGN CRITERIA ............................. 3-1
3.1 HYDRAULIC CAPACITY CRITERIA ................................................................ 3-1
3.1.1 Gravity Sewers .................................................................................. 3-1
3.1.2 Force Mains and Lift Stations ............................................................ 3-5
3.2 DRY WEATHER FLOW CRITERIA ................................................................. 3-5
3.2.1 Unit Flow Factors Methodology ......................................................... 3-6
3.2.2 Average Daily Sewer Unit Flow Factors ............................................. 3-6
3.2.3 Peaking Factors ................................................................................. 3-6
3.3 WET WEATHER FLOW CRITERIA ................................................................. 3-9
3.3.1 Infiltration and Inflow .......................................................................... 3-9
3.3.2 Sewer System Flow Monitoring ......................................................... 3-14
3.3.3 10-Year 24-Hour Design Storm ......................................................... 3-14
4.0 CHAPTER 4 – EXISTING SEWER COLLECTION FACILITIES ...................................... 4-1
4.1 SEWER COLLECTION SYSTEM OVERVIEW ................................................ 4-1
4.2 SEWER COLLECTION BASINS AND TRUNKS .............................................. 4-1
4.2.1 Gilroy Trunk ....................................................................................... 4-1
4.2.2 Southside-Luchessa Trunk ................................................................ 4-5
4.2.3 Third-Princevalle Subtrunk................................................................. 4-5
4.2.4 Country Club Subtrunk ...................................................................... 4-5
4.2.5 Thomas Subtrunk .............................................................................. 4-5
Agenda Item 9.1
Page 84 of 768
City of Gilroy
Sewer System Master Plan
TABLE OF CONTENTS PAGE NO.
March 2023 ii City of Gilroy
Sewer System Master Plan
4.2.6 Uvas Park Subtrunk ........................................................................... 4-6
4.2.7 Eagle Ridge Subtrunk ........................................................................ 4-6
4.2.8 Ninth Street Subtrunk ........................................................................ 4-6
4.2.9 Old Gilroy Subtrunk ........................................................................... 4-6
4.2.10 Forest Subtrunk ................................................................................. 4-7
4.2.11 San Ysidro Subtrunk .......................................................................... 4-7
4.2.12 Forest Murray Subtrunk ..................................................................... 4-7
4.2.13 Leavesley-Church Subtrunk ............................................................... 4-7
4.2.14 Welburn Subtrunk .............................................................................. 4-7
4.2.15 Mantelli Subtrunk ............................................................................... 4-8
4.2.16 Santa Teresa-Long Meadow Subtrunk .............................................. 4-8
4.2.17 Morgan Hill – Gilroy Joint Sewer Trunk .............................................. 4-8
4.3 LIFT STATIONS .............................................................................................. 4-9
4.4 FLOW DIVERSIONS ....................................................................................... 4-9
4.5 SOUTH COUNTY REGIONAL WASTEWATER AUTHORITY WASTEWATER
TREATMENT PLANT ...................................................................................... 4-9
5.0 CHAPTER 5 –SEWER FLOWS ....................................................................................... 5-1
5.1 FLOWS AT THE SCRWA WWTP .................................................................... 5-1
5.2 EXISTING SEWER FLOWS ............................................................................ 5-3
5.3 BUILDOUT SEWER FLOWS ........................................................................... 5-3
5.4 SEWER COLLECTION SYSTEM DESIGN FLOWS ........................................ 5-3
6.0 CHAPTER 6 – HYDRAULIC MODEL DEVELOPMENT .................................................. 6-1
6.1 HYDRAULIC MODEL SOFTWARE SELECTION ............................................ 6-1
6.2 HYDRAULIC MODEL DEVELOPMENT ........................................................... 6-1
6.2.1 Skeletonization .................................................................................. 6-1
6.2.2 Digitizing and Quality Control ............................................................. 6-2
6.2.3 Pipes and Manholes .......................................................................... 6-2
6.2.4 Load Allocation .................................................................................. 6-2
6.3 MODEL CALIBRATION ................................................................................... 6-4
6.3.1 Calibration Plan ................................................................................. 6-4
6.3.2 2014 V&A Temporary Flow Monitoring Program ................................ 6-4
6.3.3 Dynamic Model Calibration ................................................................ 6-5
6.3.4 Use of the Calibrated Model .............................................................. 6-5
7.0 CHAPTER 7 - EVALUATION AND PROPOSED IMPROVEMENTS ............................... 7-1
7.1 OVERVIEW ..................................................................................................... 7-1
7.2 EXISTING SEWER SYSTEM CAPACITY EVALUATION ................................ 7-1
7.2.1 Existing Maximum Dry Weather Flows Capacity Evaluation .............. 7-4
7.2.2 Existing Maximum Day Wet Weather Flows Capacity Evaluation ...... 7-4
7.3 ULTIMATE BUILDOUT CAPACITY IMPROVEMENTS .................................... 7-4
7.3.1 Gravity Main Improvements ............................................................... 7-5
7.3.1.1 Santa Teresa – Long Meadow Subtrunk ............................... 7-5
7.3.1.2 Welburn Subtrunk ................................................................. 7-5
7.3.1.3 Forest-Swanston Subtrunk ................................................... 7-5
7.3.1.4 Old Gilroy Subtrunk .............................................................. 7-8
7.3.1.5 Uvas Park Subtrunk .............................................................. 7-8
Agenda Item 9.1
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City of Gilroy
Sewer System Master Plan
TABLE OF CONTENTS PAGE NO.
March 2023 iii City of Gilroy
Sewer System Master Plan
7.3.1.6 Thomas Subtrunk ................................................................. 7-8
8.0 CHAPTER 8 - CAPITAL IMPROVEMENT PROGRAM ................................................... 8-1
8.1 COST ESTIMATE ACCURACY ....................................................................... 8-1
8.2 COST ESTIMATE METHODOLOGY ............................................................... 8-2
8.2.1 Unit Costs .......................................................................................... 8-2
8.2.2 Construction Cost Index .................................................................... 8-2
8.2.3 Construction Contingency Allowance ................................................. 8-2
8.2.4 Project Related Costs ........................................................................ 8-2
8.3 CAPITAL IMPROVEMENT PROGRAM ........................................................... 8-4
8.3.1 Capital Improvement Costs ................................................................ 8-4
8.3.2 Pipelines ............................................................................................ 8-4
8.3.3 Construction Triggers ........................................................................ 8-8
8.3.4 Construction Phasing ......................................................................... 8-8
8.3.5 Recommended Cost Allocation Analysis ............................................ 8-8
8.4 JOINT TRUNK CONDITION ASSESSMENT IMPROVEMENTS ..................... 8-8
8.5 SUGGESTED PIPELINE REPLACEMENT BUDGET ...................................... 8-9
Agenda Item 9.1
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City of Gilroy
Sewer System Master Plan
TABLE OF CONTENTS PAGE NO.
March 2023 iv City of Gilroy
Sewer System Master Plan
FIGURES
Figure ES.1 Regional Location Map .................................................................................... ES-3
Figure ES.2 Planning Area .................................................................................................. ES-4
Figure ES.3 Existing Sewer Collection System .................................................................... ES-6
Figure ES.4 Capital Improvement Program ......................................................................... ES-12
Figure 1.1 Regional Location Map .................................................................................... 1-2
Figure 2.1 Planning Area .................................................................................................. 2-2
Figure 2.2 Existing Land Use ........................................................................................... 2-3
Figure 2.3 2040 General Plan Land Use .......................................................................... 2-6
Figure 3.1 Hydraulic Model Diurnals ................................................................................. 3-10
Figure 3.2 Hydraulic Model Diurnals ................................................................................. 3-11
Figure 3.3 Hydraulic Model Diurnals ................................................................................. 3-12
Figure 3.4 Infiltration and Inflow Sources .......................................................................... 3-13
Figure 3.5 Flow Meter Locations ...................................................................................... 3-15
Figure 3.6 10-Year 24-Hour Storm (Design vs. Historical Storms) .................................... 3-19
Figure 4.1 Existing Sewer Collection System ................................................................... 4-2
Figure 4.2 Existing Modeled Trunk System ...................................................................... 4-3
Figure 6.1 Site 1 Calibration – Inside WWTP .................................................................... 6-6
Figure 6.2 Site 4 Calibration – W. Luchessa Ave. and Hyde Park Dr. ............................... 6-7
Figure 7.1 Existing System Analysis for PDWF ................................................................ 7-2
Figure 7.2 Existing System Analysis for PWWF ............................................................... 7-3
Figure 7.3 Capacity Improvements ................................................................................... 7-6
Figure 8.1 Capital Improvement Program ......................................................................... 8-5
Figure 8.2 Pipeline Replacement Financial Sustainability ................................................. 8-10
Agenda Item 9.1
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City of Gilroy
Sewer System Master Plan
TABLE OF CONTENTS PAGE NO.
March 2023 v City of Gilroy
Sewer System Master Plan
TABLES
Table ES.1 Sewer System Performance and Design Criteria ............................................. ES-7
Table ES.2 Existing Sewer Pipe Inventory ......................................................................... ES-8
Table ES.3 Unit Costs ....................................................................................................... ES-13
Table ES.4 Capital Improvement Program ......................................................................... ES-14
Table 1.1 Unit Conversions ............................................................................................. 1-6
Table 1.2 Abbreviations and Acronyms ........................................................................... 1-7
Table 2.1 General Plan Land Use ................................................................................... 2-4
Table 2.2 Glen Loma and Hecker Pass Specific Plans, Land Use and Flows ................. 2-7
Table 2.3 Downtown Specific Plan, Land Use and Flows ................................................ 2-8
Table 2.4 Historical and Projected Population ................................................................. 2-10
Table 3.1 Sewer System Performance and Design Criteria ............................................. 3-4
Table 3.2 Sewer Flow Unit Factor Analysis ..................................................................... 3-7
Table 3.3 Recommended Sewer Unit Factors ................................................................. 3-8
Table 3.4 Flow Meter Locations ...................................................................................... 3-16
Table 3.5 Precipitation Depth-Duration-Frequency.......................................................... 3-17
Table 3.6 Storm Events Analysis .................................................................................... 3-20
Table 4.1 Existing Sewer Pipe Inventory ......................................................................... 4-4
Table 4.2 Existing System Lift Station Inventory ............................................................. 4-10
Table 5.1 Historical Flow Data and Peaking Factors ....................................................... 5-2
Table 5.2 Future Sewer Flows ........................................................................................ 5-4
Table 5.3 Design Flows .................................................................................................. 5-6
Table 6.1 Modeled Sewer Pipe Inventory ........................................................................ 6-3
Table 7.1 Proposed Capacity Improvements ................................................................... 7-7
Table 8.1 Capacity Improvement Unit Costs ................................................................... 8-3
Table 8.2 Capital Improvement Program ......................................................................... 8-6
Table 8.3 Joint Trunk Condition Assessment, Cost Estimates ........................................ 8-11
Agenda Item 9.1
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City of Gilroy
Sewer System Master Plan
TABLE OF CONTENTS
March 2023 vi City of Gilroy
Sewer System Master Plan
APPENDICES
Appendix A Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study, 2014 (V&A)
Appendix B Hydraulic Model Calibration Exhibits
Appendix C Joint Trunk Condition Assessment Report
Agenda Item 9.1
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March 2023 ES-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
0.0 EXECUTIVE SUMMARY
This executive summary presents a brief background of the City of Gilroy’s (City) sewer collection
system, the planning area characteristics, the planning and design criteria, and the hydraulic
model development.
The hydraulic model was used to evaluate the capacity adequacy of the existing sewer collection
system and for recommending improvements to mitigate existing deficiencies and for servicing
future growth. The prioritized capital improvement program accounts for growth through the Gilroy
Planning Area.
ES.1 STUDY OBJECTIVES
Recognizing the importance of planning, developing, and financing system facilities to provide
reliable sewer collection system service to existing customers and for servicing anticipated
growth within the sphere of influence, the City initiated the 2023 Sewer System Master Plan.
The City of Gilroy authorized Akel Engineering Group Inc. to complete the following tasks:
Summarize the City’s existing sewer collection system facilities.
Document growth planning assumptions and known future developments.
Summarize the sewer system performance criteria and design storm event.
Project future sewer flows.
Update and validate the City’s hydraulic model based on the City’s Geographic Information
Systems (GIS).
Evaluate the adequacy of capacity for the sewer collection system facilities to meet
existing and projected peak dry weather flows and peak wet weather flows.
Recommend a capital improvement program (CIP) with an opinion of probable construction
costs.
Perform a capacity allocation analysis for cost sharing purposes.
Develop a 2023 Sewer System Master Plan Report.
ES.2 INTEGRATED APPROACH TO MASTER PLANNING
The City implemented an integrated master planning approach and contracted the services of
Akel Engineering Group to prepare the following documents:
2023 Water System Master Plan
Agenda Item 9.1
Page 90 of 768
March 2023 ES-2 City of Gilroy
Sewer System Master Plan
2023 Sewer System Master Plan
2023 Storm Drainage System Master Plan
While each of these reports is published as a standalone document, it has been coordinated for
consistency with the City’s General Plan. Additionally, each document has been cross referenced
to reflect relevant analysis results with the other documents.
ES.3 STUDY AREA DESCRIPTION
The City of Gilroy is located in Santa Clara County near the west coast of California, south of City
of San Francisco. The City of Gilroy lies within the seismically active region of San Francisco Bay.
The City of Gilroy lies in the southern portion of the Santa Clara County and is the most southern
City located within the county. The City is located approximately 32 miles southeast of the City of
San Jose, 8 miles southeast of Morgan Hill, 25 miles east of City of Santa Cruz, and 16 miles
northwest of City of Hollister. The City limits currently encompass 16.5 square miles, with an
approximate population of 56,599 residents, according to Department of Finance as of January
2021. Figure ES.1 displays the City’s location.
The City’s service area is generally bound to the north by Fitzgerald Avenue, to the northeast by
San Ysidro Avenue, to the southeast by Camino Arroyo, to the west by Burchell Road and
Rancho Vista Drive, and to the south by Carnadero Avenue. U.S. Route 101 divides the City in a
southeast to northwest direction and the California State Route 152 (Hecker Pass Hwy) runs east-
west direction in the northern half of the City. The topography is generally flat in the middle of the
service area, with increasing slopes in the east and west side of the City due to the Santa Cruz
Mountains to the west and the Diablo Range to the east. Figure ES.2 displays the planning area
showing City limits, the Urban Growth Boundary (UGB) of the City and Planning Area / Sphere of
Influence (SOI).
The City operates and maintains a sewer collection system that covers the majority of the area
within the City Limits and the City of Morgan Hill. Currently, the sewer flows are conveyed to the
South County Regional Wastewater Authority (SCRWA) Wastewater Treatment Plant (WWTP).
ES.4 SYSTEM PERFORMANCE AND DESIGN CRITERIA
Gravity sewer capacities depend on several factors including: material and roughness of the pipe,
the limiting velocity and slope, and the maximum allowable depth of flow. The hydraulic modeling
software used for evaluating the capacity adequacy of the City’s sewer collection system,
InfoSWMM by Innovyze Inc., utilizes the fully dynamic St. Venant’s equation which has a more
accurate engine for simulating backwater and surcharge, in addition to manifolded force mains.
The software also incorporates the use of the Manning Equation in other calculations including
upstream pipe flow conditions.
Agenda Item 9.1
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Figure ES.1
Regional Location Map
Sewer System Master Plan
City of Gilroy
5Updated: September 21, 2020
GIS
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Agenda Item 9.1
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City of Gilroy
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Planning Area
Sewer System Master Plan
City of Gilroy
5Updated: September 21, 2020
GIS
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File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig2-1PlanningArea_092120.mxd
Agenda Item 9.1
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March 2023 ES-5 City of Gilroy
Sewer System Master Plan
Partial Flow Criteria (d/D)
Partial flow in gravity sewers is expressed as a depth of flow to pipe diameter ratio (d/D). For
circular gravity conduits, the maximum capacity is generally reached at 92 percent of the full
height of the pipe (d/D ratio of 0.92). This is due to the additional wetted perimeter and increased
friction of a gravity pipe.
When designing sewer pipelines, it is common practice to use variable flow depth criteria that
allow higher safety factors in larger sizes. Thus, design d/D ratios may range between 0.5 and
0.92, with the lower values used for pipes with smaller diameters. These smaller pipes may
experience flow peaks greater than planned or may experience blockages from debris. The City’s
design standards pertaining to the d/D criteria are summarized in Table ES.1.
During peak dry weather flows (PDWF), the maximum allowable d/D ratio for proposed pipes (all
diameters) is 0.75. The maximum allowable d/D ratio for all existing pipes (all diameters) is 0.90.
The criterion for existing pipes is relaxed in order to maximize the use of the existing pipes before
costly pipe improvements are needed.
During peak wet weather flows (PWWF), to avoid premature or unnecessary trunk line
replacements, the capacity analysis allowed the d/D ratio to exceed the dry weather flow criteria
and surcharge. This condition is evaluated using the dynamic hydraulic model and the criteria
listed on Table ES.1, which stipulates that the hydraulic grade line (HGL), even during a
surcharged condition, should be at least three feet below the manhole rim elevation.
ES.5 EXISTING SEWER COLLECTION SYSTEM OVERVIEW
The City provides sewer collection services to approximately 17,000 residential, commercial,
industrial, and institutional accounts. The City’s collection system consists of approximately 167
miles of up to 60-inch gravity sewer pipes that convey flows towards the SCRWA WWTP, on
Southside Drive, as shown on Figure ES.3.
A system-wide pipe inventory, listing the total length by pipe diameter, is shown on Table ES.2.
This table is based on information extracted from the City’s GIS and was updated to reflect the
review of construction drawings provided by City Staff. The 8-inch and 12-inch diameter pipes
account for 68 percent of the total sewer pipe lengths.
ES.6 SEWER FLOWS
The sewer flows collected and treated at the SCRWA WWTP vary monthly, daily, and hourly.
While the dry weather flows are influenced by customer uses, the wet weather flows are
influenced by the severity and length of storm events and the condition of the system.
Agenda Item 9.1
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2 4 SS-33 6 363 6 Figure ES.3Existing SewerCollection SystemSewer System Master Plan City of Gilroy5Updated: September 17, 2021File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig4-1_ExistingModelSyst_091721.mxdGIS00.510.25MileLegendModeled Gravity Pipes by Size8" or Smaller10" - 18"24" or GreaterNon-Modeled SystemÈ6"#"ıLift StationNon-Modeled PipesRoadsRailroadsCity LimitsUrban Growth BoundaryRivers & CreeksWaterbodiesAgenda Item 9.1Page 95 of 768
Table ES.1 Sewer System Performance and Design Criteria
Pipeline Criteria
Peak Dry Weather Flow Criteria
Peak Wet Weather Flow Criteria
Hydraulic Grade Line (HGL) should be at least 3 foot below the manhole rim
Suggested Master
Plan Criteria
City of Gilroy
General Guidelines1
Minimum Grade
(Velocity = 2.0 ft/s)
Minimum
Capacity
(n= 0.013)
Minimum Grade
(Velocity = 2.5 ft/s)
Minimum
Capacity
(n= 0.013)
(in)(ft/ft)cfs (ft/ft)(cfs)
8 0.0026 0.55 0.0077 0.00
10 0.0019 0.87 0.0057 0.82
12 0.0015 1.23 0.0022 1.29
15 0.0011 1.98 0.0015 1.58
18 0.0009 2.75 0.0012 2.46
21 0.0007 3.76 0.0010 3.54
24 0.0006 5.05 0.0008 4.82
27 0.0005 6.47
30 0.0004 7.94
33 0.0004 9.34
36 0.0004 11.78
42 0.0003 15.90
Lift Station Criteria
Lift Stations: When permitted by City Engineer. Firm Capacity to meet Peak Wet
Weather Flow.
9/28/2020
Notes:
1. Source: City of Gilroy General Guidelines, August 2014.
Existing Sewer Trunks: Maximum allowable d/D of 0.90
Proposed Sewer Trunks: Maximum allowable d/D of 0.75
Sewer System Master Plan
City of Gilroy
Pipe
Size
Agenda Item 9.1
Page 96 of 768
Table ES.2 Existing Sewer Pipe Inventory
Sewer System Master Plan
City of Gilroy
(in)(feet)(miles)
City Pipes
≤62 154,358 29.2
8 463,234 87.7
10 81,809 15.5
12 58,195 11.0
14 327 0.1
15 16,330 3.1
16 136 0.03
18 43,284 8.2
24 13,447 2.5
27 12,542 2.4
30 914 0.2
42 5,810 1.1
48 375 0.1
Total 850,760 161.1
Joint Trunk Pipes3
21 202 < 0.1
24 5,679 1.1
27 4,407 0.8
30 2,776 0.5
33 22,132 4.2
42 246 < 0.1
60 96 < 0.1
Total 35,537 6.7
5/20/2021
Notes:
1. Source: GIS Received from City staff on September 10, 2020.
2. Includes pipelines of unknown diameter.
3. Indicates Joint Trunk pipelines south of intersection at
Fitzgerald Avenue and Monterey Road.
Pipe Size Length
Agenda Item 9.1
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March 2023 ES-9 City of Gilroy
Sewer System Master Plan
Flow data influent to the SCRWA WWTP was obtained from City operation staff. The flow data
covered a period from 2010 to 2019. From this data monthly, daily, and peak daily flows, were
determined.
The land use methodology was used to estimate the buildout flows from the City’s Planning Area
and to be consistent with the General Plan. The undeveloped lands were multiplied by the
corresponding unit flow factor to estimate the sewer flows. The buildout average daily flows were
calculated at 7.06 MGD.
ES.7 HYDRAULIC MODEL DEVELOPMENT AND CALIBRATION
The City’s hydraulic model combines information on the physical characteristics of the sewer
collection system (pipelines, manholes, and diversions) and operational characteristics (how they
operate). The hydraulic model then performs calculations and solves series of equations to
simulate flows in pipes, including backwater calculations for surcharged conditions.
There are several network analysis software products released by different manufacturers that
can equally perform the hydraulic analysis satisfactorily. The selection of a particular software
depends on user preferences, the sewer collection system’s unique requirements, and the costs
for purchasing and maintaining the software.
The hydraulic modeling software used for evaluating the capacity adequacy of the City’s sewer
collection system, InfoSWMM by Innovyze Inc., utilizes the fully dynamic St. Venant’s equation
which has a more accurate engine for simulating backwater and surcharge conditions, in addition
to having the capability for simulating manifolded force mains. The software also incorporates the
use of the Manning Equation in other calculations including upstream pipe flow conditions. The St
Venant’s and Manning’s equations are discussed in the System Performance and Design Criteria
chapter.
Model Development
The hydraulic model for the City of Gilroy was skeletonized to include the pipelines essential to
the hydraulic analysis.
Skeletonizing the model refers to the process where pipes not essential to the hydraulic analysis
of the system are stripped from the model. Skeletonizing the model is useful in creating a system
that accurately reflects the hydraulics of the pipes within the system. In addition, skeletonizing the
model will reduce both the complexities of large models and the time of analysis while maintaining
accuracy, but will also comply with the limitations imposed by the computer program.
In the City of Gilroy’s case, skeletonizing was necessary to reduce the model from approximately
4,529 pipes extracted from the GIS to 657 pipes. The modeled pipes included pipes 8-inches in
diameter and larger, in addition to some critical smaller gravity sewer pipes. The inventory
pipelines included in the hydraulic model are approximately 23.5 percent of the overall system.
Agenda Item 9.1
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March 2023 ES-10 City of Gilroy
Sewer System Master Plan
Model Calibration
Calibration can be performed for steady state conditions, which model the peak hour flows, or for
dynamic conditions (24 hours or more). Dynamic calibration consists of comparing the model
predictions to diurnal operational changes in the wastewater flows. The City’s hydraulic model
was calibrated for dynamic conditions.
In sewer collection systems, and when using dynamic hydraulic modeling to evaluate the impact
of wet weather flows, it is common practice to calibrate the model to the following three conditions:
Peak dry weather flows on a weekday and a weekend.
Peak wet weather flows from storm rainfall Event No. 1 (February 26 2014 – February 27
2014)
Peak wet weather flows from storm rainfall Event No. 2 (February 28 2014 – March 1
2014).
After the model is calibrated to these conditions, it is benchmarked and used for evaluating the
capacity adequacy of the sewer collection system, under dry and wet weather conditions.
The hydraulic model is a valuable investment that will continue to prove its worth to the City as
future planning issues or other operational conditions surface. It is recommended that the model
be maintained and updated with new construction projects to preserve its integrity.
ES.8 CAPACITY EVALUATION
The system performance and design criteria were used as a basis to judge the adequacy of
capacity for the existing sewer collection system. The design flows simulated in the hydraulic
model for existing conditions are listed as follows:
Existing PDWF = 8.79 MGD
Existing PWWF = 13.81 MGD
During the peak dry weather simulations, the maximum allowable pipe d/D criteria for new pipes
(d/D ratio of 0.75) was used. For existing pipes, the criteria was relaxed to allow a maximum d/D
ratio of 0.90 (full pipe capacity) to prevent unnecessary pipe replacements. During the peak wet
weather simulations, capacity deficiencies included pipe segments with a hydraulic grade line
(HGL) that rises within three feet of the manhole rim elevation.
In general, the hydraulic model indicated that the sewer collection system exhibited acceptable
performance to service the existing customers during peak dry weather flows and peak wet
weather flows. Future flows were then added to the hydraulic model and the existing system was
Agenda Item 9.1
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March 2023 ES-11 City of Gilroy
Sewer System Master Plan
expanded in order to serve these future customers. The proposed improvements for the future
system are shown with pipe sizes on an overall exhibit on Figure ES.4.
ES.9 CAPITAL IMPROVEMENT PROGRAM
The Capital Improvement Program includes pipeline improvements recommended in this master
plan (Table ES.4). Each improvement was assigned a uniquely coded identifier associated with its
tributary area. The baseline costs for pipelines and lift stations are shown in Table ES.2.
Improvements are shown in Figure ES.4.
The estimated costs include the baseline costs plus 30 percent contingency allowance to account
for unforeseen events and unknown field conditions. Capital improvement costs include the
estimated construction costs plus 30 percent project related costs (engineering design, project
administration, construction management and inspection, and legal costs).
The costs in this Sewer System Master Plan were benchmarked using a 20-City national average
ENR CCI of 13,176, reflecting a date of March 2023. In total, the CIP includes approximately 3.9
miles of gravity main improvements with a cost totaling over 12.7 million dollars.
Agenda Item 9.1
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2 4 STP-1WP-1WP-1WP-2FP-1FP -2 OP-2UP-615UP-4U P -3TP-1T P-2 ².WWTPSS-3OP-11215UP-5Uvas Creek12UP-13 6 363 6 Figure ES.4Captial ImprovementProgramSewer System Master Plan City of Gilroy5Updated: September 17, 2021File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig8-1_CIP_091721.mxdGIS00.510.25MileLegendImprovement PipesModeled Gravity Pipes by Size8" or Smaller10" - 18"24" or GreaterNon-Modeled SystemÈ6"#"ıLift StationNon-Modeled PipesRoadsRailroadsCity LimitsUrban Growth BoundaryRivers & CreeksWaterbodiesNote:WP-1 and WP-2 should be completedat the same time, the existing 10-inchin the middle may be reassessed andreplaced depending on pipelinecondition and age.Agenda Item 9.1Page 101 of 768
Table ES.3 Unit Costs
Sewer System Master Plan
City of Gilroy
Pipelines
Improvement Type Unit Cost
New/Parallel/Replacement
(in)($/unit length)
8 259
10 289
12 332
15 360
18 389
21 418
24 475
27 535
30 594
36 713
Pipeline Casings
23$ per inch diameter per linear foot
3/28/2023
Notes :
1. Unit costs are based on an ENR CCI Index Value
of 13,176 (March 2023).
Pipe
Size
Agenda Item 9.1
Page 102 of 768
Table ES.4 Capital Improvement Program
Sewer System Master Plan
City of Gilroy
Pipeline Improvements Infrastructure Costs Suggested Cost Allocation Cost Allocation
Existing
Diameter
New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost Existing
Users
Future
Users
Existing
Users
Future
Users
(in)(in)(ft)($)($)($)($)($)(gpm)(%)(%)($)($)
Gravity Main Improvements
Santa Teresa - Long Meadow Subtrunk
SLP-1 Gravity Main Santa Teresa Blvd From Sunrise Dr to Longmeadow Dr 10 Replacement 12 2,025 332 671,321 671,400 872,900 1,134,800 954 EDU 61%39%689,302 445,498
Subtotal - Santa Teresa - Long Meadow Subtrunk 671,400 872,900 1,134,800 689,302 445,498
Welburn Subtrunk
WP-1 Gravity Main Welburn Ave From Chiesa Dr to Aspen Wy 10 Replacement 12 1,700 332 563,578 563,600 732,700 952,600 Existing Deficiency 90%10%861,520 91,080
WP-2 Gravity Main Welburn Ave From Church St to Hanna St 10 Replacement 12 750 332 248,637 248,700 323,400 420,500 Existing Deficiency 91%9%384,531 35,969
Subtotal - Welburn Subtrunk 812,300 1,056,100 1,373,100 1,246,051 127,049
Forest-Swanston Subrunk
FP-1 Gravity Main Ioof Ave From Monterey Rd to Forest Ave 10 Replacement 12 1,150 332 381,244 381,300 495,700 644,500 Existing Deficiency 93%7%601,483 43,017
FP-2 Gravity Main Forest St From Lewis St to Old Gilroy St 12 Replacement 15 1,875 360 675,064 675,100 877,700 1,141,100 Existing Deficiency 96%4%1,093,639 47,461
Subtotal - Forest-Swanston Subrunk 1,056,400 1,373,400 1,785,600 1,695,122 90,478
Old Gilroy Subtrunk
OP-1 Gravity Main Old Gilroy St From 75' w/o Railroad St to Railroad St 10 Replacement 12 100 332 33,152 33,200 43,200 56,200 Existing Deficiency 89%11%50,159 6,042
OP-2 Gravity Main Old Gilroy St From Railroad St to Forest St 12 Replacement 15 750 360 270,026 270,100 351,200 456,600 Existing Deficiency 89%11%407,516 49,085
Subtotal - Old Gilroy Subtrunk 303,300 394,400 512,800 457,674 55,126
Uvas Park Subtrunk
UP-1 Gravity Main Uvas Park Dr From 3rd St to 350 ft e/o Santa Barbara Dr -New 12 2,375 332 787,352 787,400 1,023,700 1,330,900 Existing Deficiency 39%61%517,772 813,128
UP-2 Gravity Main Hoxett St / ROW From Wren Ave to Miller Ave 12 Replacement 18 1,550 389 602,255 602,300 783,000 1,017,900 2,020 EDU 36%64%370,355 647,545
UP-3 Gravity Main Yorktown Dr From Miller Ave to Greenwich Dr 12 Replacement 18 1,725 389 670,252 670,300 871,400 1,132,900 1,923 EDU 38%62%427,260 705,640
UP-4 Gravity Main Greenwich Dr From Yorktown Dr to Orchard Dr 12 Replacement 18 575 389 223,417 223,500 290,600 377,800 2,152 EDU 38%62%145,055 232,745
UP-5 Gravity Main Orchard Dr From Greenwich Dr to W 10th St 12 Replacement 18 200 389 77,710 77,800 101,200 131,600 2,401 EDU 39%61%51,307 80,293
UP-6 Gravity Main W 10th St From Orchard Dr to Princevalle St 12 Replacement 18 1,350 389 524,545 524,600 682,000 886,600 3,085 EDU 39%61%346,721 539,879
Subtotal - Uvas Park Subtrunk 2,885,900 3,751,900 4,877,700 1,858,470 3,019,230
Thomas Subtrunk
TP-1 Gravity Main London Pl From Monterey Rd to Princevalle St 18 Replacement 21 2,775 418 1,160,665 1,160,700 1,509,000 1,961,700 5,873 EDU 62%38%1,224,966 736,734
TP-2 Gravity Main Monterey Rd From Luchessa Ave to London Pl 18 Replacement 21 1,525 418 637,843 637,900 829,300 1,078,100 5,303 EDU 62%38%672,095 406,005
Subtotal - Thomas Subtrunk 1,798,600 2,338,300 3,039,800 1,897,061 1,142,739
Total Costs
Subtotal - Santa Teresa - Long Meadow Subtrunk 671,400 872,900 1,134,800 689,302 445,498
Subtotal - Welburn Subtrunk 812,300 1,056,100 1,373,100 1,246,051 127,049
Subtotal - Forest-Swanston Subrunk 1,056,400 1,373,400 1,785,600 1,695,122 90,478
Subtotal - Old Gilroy Subtrunk 303,300 394,400 512,800 457,674 55,126
Subtotal - Uvas Park Subtrunk 2,885,900 3,751,900 4,877,700 1,858,470 3,019,230
Subtotal - Thomas Subtrunk 1,798,600 2,338,300 3,039,800 1,897,061 1,142,739
Total Improvement Costs 7,527,900 9,787,000 12,723,800 7,843,681 4,880,119
3/28/2023
Notes :
1.Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,176 (March 2023).
2.Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.
3.Estimated construction cost plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal
costs.
Capital Improv.
Cost 3
Construction
TriggerImprov. No.Type of
Improvement Alignment Limits Baseline Constr.
Costs 1
Estimated Const.
Costs 2
Agenda Item 9.1
Page 103 of 768
March 2023 1-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
1.0 CHAPTER 1 - INTRODUCTION
This chapter provides a brief background of the City of Gilroy’s (City) sewer collection system
(also known as a wastewater collection system), the need for this master plan, and the objectives
of the study. Unit conversions, abbreviations, and definitions are also provided in this chapter.
1.1 BACKGROUND
The City of Gilroy is located approximately 32 miles southeast of the City of San Jose, 8 miles
southeast of Morgan Hill, 25 miles east of the City of Santa Cruz, and 16 miles northwest of City
of Hollister (Figure 1.1). The City provides sewer collection services to approximately 17,000
residential, commercial, industrial, and institutional accounts. The City owns, operates, and
maintains the sewer collection system, which consists of over 167 miles of gravity trunks and
force mains, with up to 42-inch pipe sizes, which convey the flow to the South County Wastewater
Authority (SCRWA) Wastewater Treatment Plant (WWTP). The WWTP has an average daily
capacity rating of 8.5 million gallons per day (MGD).
In 2004, the City of Gilroy developed a Sewer System Master Plan that identified capacity
deficiencies in the existing sewer system and recommended improvements to alleviate existing
deficiencies and serve future developments in the Gilroy Planning Area.
Recognizing the importance of planning, developing, and financing system facilities to provide
reliable sewer collection service to existing customers and for servicing anticipated growth within
the Gilroy Planning Area, the City initiated updating elements of the 2004 Sanitary Sewer Master
Plan, to reflect current land use conditions and General Plan updates.
1.2 SCOPE OF WORK
City Council approved Akel Engineering Group to prepare this 2023 Sewer System Master Plan
(SSMP) and a concurrent Water System Master Plan and Storm Drainage System Master Plan in
August 2019. The 2023 SSMP evaluates the City’s sewer collection system and recommends
capacity improvements necessary to service the needs of existing users and for servicing the
future growth of the City. This 2023 SSMP is intended to serve as a tool for planning and phasing
the construction of future sewer collection system infrastructure for the projected buildout of the
City’s service area. The area and horizon for this master plan is based on the City’s General Plan.
Should planning conditions change, and depending on their magnitude, adjustments to the master
plan recommendations might be necessary.
The master plan included the following tasks:
Summarizing the City’s existing sewer collection system facilities.
Documenting growth planning assumptions and known future developments.
Agenda Item 9.1
Page 104 of 768
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Figure 1.1
Regional Location Map
Sewer System Master Plan
City of Gilroy
5Updated: September 21, 2020
GIS
0120.5 Miles
Legend
!(Cities
Railroads
Highway
City Limits
Urban Growth Boundary
Study Area
Elevation (ft)
51 - 100
101 - 250
251 - 500
501 - 1,000
1,001 - 2,000
2,001 - 3,0009 - 50
3,001 - 3,792
Waterbodies
Flie Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig1-1RLMap_092120.mxd
Agenda Item 9.1
Page 105 of 768
March 2023 1-3 City of Gilroy
Sewer System Master Plan
Summarizing the sewer system performance criteria and design storm event.
Projecting future sewer flows.
Updating and validating the City’s hydraulic model based on the City’s Geographic
Information Systems (GIS).
Evaluating the adequacy of capacity for the sewer collection system facilities to meet
existing and projected peak dry weather flows and peak wet weather flows.
Recommending a capital improvement program (CIP) with an opinion of probable
construction costs.
Performing a capacity allocation analysis for cost sharing purposes.
Developing a 2023 Sewer System Master Plan Report.
1.3 INTEGRATED APPROACH TO MASTER PLANNING
This City implemented an integrated master planning approach and contracted the services of
Akel Engineering Group to prepare the following documents:
2023 Water System Master Plan
2023 Sewer System Master Plan
2023 Storm Drainage System Master Plan
While each of these reports is published as a standalone document, it has been coordinated for
consistency with the City’s General Plan. Additionally, each document has been cross referenced
to reflect relevant analysis results with the other documents.
1.4 PREVIOUS MASTER PLANS
The City’s most recent sewer master plan was completed in 2004. This master plan included
evaluation of servicing growth to the planning area, evaluated existing sewer flows and projected
future flows and recommended phased improvements to the sewer system for a horizon year of
2040. Additionally, the 2004 master plan included the development of the hydraulic model which
was used for evaluating the sewer system. Improvements were recommended for servicing
existing and future growth areas, and a corresponding Capital Improvement Program was
developed to quantify the corresponding costs.
1.5 RELEVANT REPORTS
The City has completed several special studies intended to evaluate localized growth. These
reports were referenced and used during this capacity analysis. The following lists relevant reports
that were used in the completion of this master plan, as well as a brief description of each
document:
Agenda Item 9.1
Page 106 of 768
March 2023 1-4 City of Gilroy
Sewer System Master Plan
City of Gilroy 2040 General Plan, November 2020 (2040 GP). The City’s 2040 General
Plan provides future land use planning, and growth assumptions for the Planning Area.
Additionally, this report establishes the planning horizon for improvements in this master
plan.
City of Gilroy Sewer System Master Plan, February 2004 (2004 SSMP). This report
documents the planning and performance criteria, evaluates the sewer system,
recommends improvements, and provides an estimate of costs.
City of Morgan Hill Sewer System Master Plan, January 2002 (2002 SSMP). This
report documents the planning and performance criteria, evaluates the sewer system,
recommends improvements, and provides an estimate of costs.
City of Morgan Hill Sewer System Master Plan, February 2016 (2016 SSMP). This
report documents the planning and performance criteria, evaluates the sewer system,
recommends improvements, and provides an estimate of costs. This document was used
to quantify the existing and future sewer flows in the Morgan Hill – Gilroy Joint Trunk.
1.6 REPORT ORGANIZATION
The Sewer System Master Plan report contains the following chapters:
Chapter 1 – Introduction. This chapter provides a brief background of the City of Gilroy’s (City)
sewer collection system (also known as a wastewater collection system), the need for this master
plan, and the objectives of the study. Unit conversions, abbreviations, and definitions are also
provided in this chapter.
Chapter 2 – Planning Area Characteristics. This chapter presents a discussion of planning
area characteristics and defines the land use classification.
Chapter 3 – System Performance and Design Criteria. This chapter presents the City’s
performance and design criteria which was used in this analysis for identifying current system
capacity deficiencies and for sizing proposed collection mains and lift stations.
Chapter 4 – Existing Sewer Collection Facilities. This chapter provides a description of the
City’s existing sewer collection system facilities including gravity trunks, force mains, lift stations,
and sewer collection basins. The chapter also includes a brief description of the SCRWA WWTP,
which treats and disposes of the wastewater for the City.
Chapter 5 – Sewer Flows. This chapter summarizes historical sewer flows experienced at the
South County Regional Wastewater Authority (SCRWA) WWTP and defines flow terminologies
relevant to this evaluation. This chapter discusses the design flows used in the hydraulic modeling
effort and capacity evaluation. The design flows include the existing condition (existing customers)
and buildout development conditions.
Agenda Item 9.1
Page 107 of 768
March 2023 1-5 City of Gilroy
Sewer System Master Plan
Chapter 6 – Hydraulic Model Development. This chapter describes the development and
calibration of the City’s sewer collection system hydraulic model. The City’s hydraulic model was
used to evaluate the capacity adequacy of the existing system and to plan its expansion to service
anticipated future growth.
Chapter 7 – Evaluation and Proposed Improvements. This section presents a summary of the
sewer collection system capacity evaluation during peak dry weather flows and peak wet weather
flows for the existing and buildout development conditions. The recommended sewer collection
system improvements needed to mitigate capacity deficiencies are also discussed in this chapter.
Chapter 8 – Capital Improvement Program. This chapter provides a summary of the
recommended sewer collection system improvements to mitigate existing capacity deficiencies
and service future growth. This chapter also presents the cost criteria and methodologies for
developing the capacity improvement costs. Finally, a cost allocation analysis, usually used for
cost sharing purposes, is also included.
1.7 ACKNOWLEDGEMENTS
Obtaining the necessary information to successfully complete the analysis presented in this
report, and developing the long-term strategy for mitigating the existing system deficiencies and
for accommodating future growth, was accomplished with the strong commitment and very active
input from dedicated team members including:
•Daryl Jordan, P.E.; Director of Public Works
•Gary Heap, P.E.; City Engineer
•Jorge Duran, P.E.; Senior City Engineer
•Matt Jones, Deputy Public Works Director
1.8 UNIT CONVERSIONS AND ABBREVIATIONS
Engineering units were used in reporting flow rates and volumes pertaining to the design and
operation of various components of the sewer collection system. Where it was necessary to report
values in smaller or large quantities, different sets of units were used to describe the same
parameter. Values reported in one set of units can be converted to another set of units by
applying a multiplication factor. A list of multiplication factors for units used in this report are
shown on Table 1.1.
Various abbreviations and acronyms were also used in this report to represent relevant sewer
collection system terminologies and engineering units. A list of abbreviations and acronyms is
included in Table 1.2.
Agenda Item 9.1
Page 108 of 768
Volume Unit Calculations
To Convert From: To: Multiply by:
acre feet gallons 325,857
acre feet cubic feet 43,560
acre feet million gallons 0.3259
cubic feet gallons 7.481
cubic feet acre feet 2.296 x 10‐5
cubic feet million gallons 7.481 x 10‐6
gallons cubic feet 0.1337
gallons acre feet 3.069 x 10‐6
gallons million gallons 1 x 10‐6
million gallons gallons 1,000,000
million gallons cubic feet 133,672
million gallons acre feet 3.069
Flow Rate Calculations
To Convert From: To: Multiply By:
ac‐ft/yr mgd 8.93 x 10‐4
ac‐ft/yr cfs 1.381 x 10‐3
ac‐ft/yr gpm 0.621
ac‐ft/yr gpd 892.7
cfs mgd 0.646
cfs gpm 448.8
cfs ac‐ft/yr 724
cfs gpd 646300
gpd mgd 1 x 10‐6
gpd cfs 1.547 x 10‐6
gpd gpm 6.944 x 10‐4
gpd ac‐ft/yr 1.12 x 10‐3
gpm mgd 1.44 x 10‐3
gpm cfs 2.228 x 10‐3
gpm ac‐ft/yr 1.61
gpm gpd 1,440
mgd cfs 1.547
mgd gpm 694.4
mgd ac‐ft/yr 1,120
mgd gpd 1,000,000
2/11/2016
Table 1.1 Unit Conversions
Sewer System Master Plan
City of Gilroy
Agenda Item 9.1
Page 109 of 768
Abbreviation Expansion Abbreviation Expansion
2016 SSMP 2016 Sewer System Master Plan HGL Hydraulic Grade Line
10Yr‐24Hr 10‐Year 24‐Hour in/hr Inch per Hour
ADWF Average Dry Weather Flow I&I Infiltration and Inflow
AAF Annual Average Flow LF Linear Feet
Akel Akel Engineering Group, Inc.MDDWF Maximum Day Dry Weather Flow
AWWF Average Wet Weather Flow MDWWF Maximum Day Wet Weather Flow
BWF Base Wastewater Flow MGD Million Gallons per Day
CCI Construct Cost Index MMDWF Maximum Month Dry Weather Flow
CCTV Closed Circuit Television MMWWF Maximum Month Wet Weather Flow
CDP Census Designated Place NOAA National Oceanic and Atmospheric
Administration
CIP Capital Improvement Program PWSS Public Water System Statistics
City City of Gilroy PDWF Peak Dry Weather Flow
DDF Depth Duration Frequency PWWF Peak Wet Weather Flow
d/D depth of flow to pipe diameter ROW Right of Way
EDUs Equivalent Dwelling Units SCADA Supervisory Control and Data
Acquisition
ENR Engineering News Record SCRWA South County Regional Wastewater
Authority
fps Feet per Second SCVWD Santa Clara Valley Water District
FY Fiscal Year VCP Vitrified Clay Pipe
GIS Geographic Information Systems V&A Villalobos and Associates
gpd Gallons per Day WWTP Wastewater Treatment Plant
gpm Gallons per Minute
2/11/2016
Sewer System Master Plan
City of Gilroy
Table 1.2 Abbreviations and Acronyms
Agenda Item 9.1
Page 110 of 768
March 2023 1-8 City of Gilroy
Sewer System Master Plan
1.9 GEOGRAPHIC INFORMATION SYSTEMS
This master planning effort made extensive use of Geographic Information Systems (GIS)
technology, for completing the following tasks:
Develop the physical characteristics of the hydraulic model (gravity mains, force mains,
and lift stations).
Allocate existing sewer loads, as calculated using the developed sewer unit factors.
Calculate and allocate future sewer loads, based on the future developments’ land use.
Extract ground elevations along the gravity and force mains from available contour maps
and digital elevation models.
Generate maps and exhibits used in this master plan.
Agenda Item 9.1
Page 111 of 768
March 2023 2-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
2.0 CHAPTER 2 – PLANNING AREA
CHARACTERISTICS
This chapter presents a discussion of planning area characteristics and defines the land use
classification.
2.1 STUDY AREA DESCRIPTION
The City of Gilroy is located in Santa Clara County near the west coast of California, south of City
of San Francisco. The City of Gilroy lies within the seismically active region of San Francisco Bay.
The City of Gilroy lies in the southern portion of the Santa Clara County and is the most southern
City located within the county. The City is located approximately 32 miles southeast of the City of
San Jose, 8 miles southeast of Morgan Hill, 25 miles east of City of Santa Cruz, and 16 miles
northwest of City of Hollister. The City limits currently encompass 16.5 square miles, with an
approximate population of 56,599 residents, according to Department of Finance as of January
2021. Figure 1.1 displays the City’s location.
The City’s service area is generally bound to the north by Fitzgerald Avenue, to the northeast by
San Ysidro Avenue, to the southeast by Camino Arroyo, to the west by Burchell Road and
Rancho Vista Drive, and to the south by Carnadero Avenue. U.S. Route 101 divides the City in a
southeast to northwest direction and the California State Route 152 (Hecker Pass Hwy) runs east-
west direction in the northern half of the City. The topography is generally flat in the middle of the
service area, with increasing slopes in the east and west side of the City due to the Santa Cruz
Mountains to the west and the Diablo Range to the east. Figure 2.1 displays the planning area
showing City limits, the Urban Growth Boundary (UGB) of the City and Planning Area / Sphere of
Influence (SOI).
The City operates and maintains a sewer collection system that covers the majority of the area
within the City Limits and the City of Morgan Hill. Currently, the sewer flows are conveyed to the
South County Regional Wastewater Authority (SCRWA) Wastewater Treatment Plant (WWTP).
2.2 SEWER SERVICE AREAS AND LAND USE
The City’s sewer system services residential and non-residential lands within the City limits, as
summarized on Table 2.1 and shown graphically on Figure 2.2. Areas within the City’s existing
service area include:
5,429 acres of developed lands inside the City limits.
3,673 acres of undeveloped lands inside the City limits.
Agenda Item 9.1
Page 112 of 768
City of Gilroy
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Figure 2.1
Planning Area
Sewer System Master Plan
City of Gilroy
5Updated: September 21, 2020
GIS
0120.5
Miles
Legend
City Limits
City Limits Area
Specific Plan Areas
Urban Service Area
Urban Growth Boundary
Sphere of Influence Boundary
General Plan Area
Roads
Highways
Railroads
Rivers & Creeks
Waterbodies
File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig2-1PlanningArea_092120.mxd
Agenda Item 9.1
Page 113 of 768
£¤101£¤101UV152UV152UV25L la g a s C r e e k
Miller SloughUvas CreekBuena Vista AveFitzgerald AveM o n te r e y R d
Day RdSunrise DrMantelli DrS a n ta T e r e s a Bl Wren AveLeavesley RdCa m in o Ar ro yo
Tenth StSouthside DrUvasPark D r Castro Valley RdF raz ie r L a ke R d Bloomfield AveSheldon AveDavidson AveLas Animas AveCohansey AveGilman RdHecker Pass RdFirst StRucker AvPajaro RiverShore RdFigure 2.2Existing Land UseSewer System Master PlanCity of GilroyLegendExisting Land UseLow Density ResidentiaMedium Density ResidentialHigh Density ResidentialNeighborhood DistrictPublic/Quasi-Public FacilityEducational FacilityProfessional OfficeGeneral Services CommercialVisitor-Serving CommercialIndustrialOpen SpacePark and Recreation FacilityVacantCity LimitsRoadsRailroadsRivers & CreeksWaterbodiesUpdated: September 21, 20200120.5Miles5GISFile Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig2-2ExistLandUse_092120.mxdAgenda Item 9.1Page 114 of 768
Table 2.1 General Plan Land Use Sewer System Master Plan City of GilroyExistingExisting Lands ‐ RedevelopingNew Lands ‐ RedevelopmentNew Development(acre)(acre)(acre)(acre)(acre)(acre)(acre)(acre)(acre)123 4 567891011ResidentialRural Residential‐0 0 00000 0 0Hillside Residential Hillside Residential 444‐1 442 112 344 8 464 907 913Low Density ResidentialLow Density Residential1,704‐1211,58312245442111,7944,221Medium Density ResidentialMedium Density Residential100‐425817742183240248High Density ResidentialHigh Density Residential249‐182671815336104111Subtotal ‐ Residential 2,496‐3462,151429408588953,0455,493Non‐ResidentialVisitor Serving Commercial Visitor Serving Commercial 99‐67 32 176 0 0 176 208 208General Services Commercial General Services Commercial 524‐91 432 106 55 44 205 637 837Professional Office 1 0 10000 1 1General Industrial General Industrial320‐712492132553898561,1052,036Campus Industrial56‐124400004444Educational FacilityEducational Facility12‐571001 8 22Public/Quasi‐Public FacilityPublic/Quasi‐Public Facility596‐44552152102282818331,013Neighborhood DistrictNeighborhood District94‐9403822336395395428City Gateway District‐0002070272727Downtown Specific Plan Area‐00057320898989Mixed Use Corridor High‐0002570333333Hecker Pass Special Use District‐000328880416416416Glen Loma Ranch‐0001032370341341341Industrial Park‐00043400838383Employment Center‐00027930222530530530Subtotal ‐ Non‐Residential 1,701‐3841,3171,5418761,0173,4344,7506,109OtherAgriculture‐0 0 00000 0 0Park and Recreation FacilityPark and Recreation Facility1,232‐238995066881541,1492,392VacantVacant2,391‐2,39100000 0 0Open SpaceOpen Space1,282‐1,03025301,04141,0451,2982,897Rural County0002803303017,726Subtotal ‐ Other 4,905‐3,6581,247281,107951,2302,47723,015TotalTotal Developed Area 9,102‐4,388 4,714 1,997 2,391 1,170 5,558 10,272 34,6169/22/2020Notes:1. Source: City of Gilroy General Plan Alternatives Report, Public Review Draft July 2019.Urban Growth BoundarySphere of InfluenceTotal DevelopmentGeneral Plan Land Use ClassificationExisting Land Use ClassificationSubtotal Existing Development ‐UnchangedWithin City LimitsUrban Growth BoundaryExisting Development Future DevelopmentWithin City LimitsSubtotal Future DevelopmentAgenda Item 9.1Page 115 of 768
March 2023 2-5 City of Gilroy
Sewer System Master Plan
At ultimate development of the General Plan, the City’s sewer system is anticipated to service
approximately 3,045 acres of residential land use, 4,750 acres of non-residential land use, and
2,477 acres of non-flow generating land use, for a total of 10,272 acres inside the City’s Urban
Growth Boundary (Table 2.1). The land use designations utilized in this master plan are
consistent with the Land Use Element of the City’s 2040 General Plan, and as received from the
City’s planning division and shown on Figure 2.3.
In addition to the General Plan Land Use documented on Figure 2.3, there are multiple areas of
known development, which are defined by Specific Plans or other development planning
information. These known development areas provide a more refined definition of planned land
uses, which is used for estimating future flows. The known development areas are summarized on
Figure 2.3, with the land use information shown on Table 2.1. Based on a review of aerial
imagery and existing land use information, some known development areas are partially
developed or completely developed. The known development areas are summarized in the
following sections.
Hecker Pass Specific Plan: This development area includes approximately 416 acres,
which includes 164 acres of residential, 154 acres of non-residential, and 98 acres of other
non-flow generating land use as documented in Table 2.2.
Glen Loma Specific Plan: This development area includes approximately 341 acres,
which includes 210 acres of residential, 35 acres of non-residential, and 96 acres of other
non-flow generating land use as documented in Table 2.2.
Downtown Specific Plan: This development area includes approximately 202 acres,
which includes 108 acres of residential and 94 acres of non-residential land use as
documented in Table 2.3. This development area is comprised of multiple land use
districts as summarized in the following sections.
o Historic Land Use District: This development area includes approximately 18
acres, which includes 7.9 acres of residential and 10.0 acres of non-residential land
use.
o VTA Transit-Oriented Development: This development area includes
approximately 8 acres, which includes 7.5 acres of residential and 0.3 acres of
non-residential land use.
o Expansion Land Use District: This development area includes approximately 48
acres, which includes 21 acres of residential and 27 acres of non-residential land
use.
o Cannery Land Use District: This development area includes approximately 37
acres, which includes 11 acres of residential and 26 acres of non-residential land
use.
Agenda Item 9.1
Page 116 of 768
£¤101£¤101UV152UV152UV25L la g a s C r e e k
Miller SloughUvas CreekBuena Vista AveFitzgerald AveM o n te r e y R d
Day RdSunrise DrMantelli DrS a n ta T e r e s a Bl Wren AveLeavesley RdCa m in o Ar ro yo
Tenth StSouthside DrUvasPark D r Castro Valley RdF raz ie r L a ke R d Bloomfield AveSheldon AveDavidson AveLas Animas AveCohansey AveGilman RdHecker Pass RdFirst StRucker AvPajaro RiverShore RdFigure 2.32040 General PlanLand UseSewer System Master PlanCity of GilroyLegendPlanning Area/Sphere of InfluenceUrban Growth BoundaryCity LimitsGeneral Plan Land UseHillside ResidentialLow Density ResidentialMedium Density ResidentialHigh Density ResidentialGeneral Services CommercialCity Gateway DistrictVisitor Serving CommercialGeneral IndustrialEmployment CenterIndustrial ParkPublic and Quasi-Public FacilityNeighborhood DistrictMixed UseRural CountyOpen SpacePark and Recreation FacilitySpecific Plan AreasDowntownGlen Loma RanchHecker PassRoadsRailroadsRivers & CreeksWaterbodiesUpdated: December 6, 20190120.5Miles5GISFile Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig2-3GeneralPlanLU_121019.mxdAgenda Item 9.1Page 117 of 768
Table 2.2 Glen Loma and Hecker Pass Specific Plans, Remaining Development Sewer Flow
Sewer System Master Plan
City of Gilroy
Residential Non‐Residential Other
HillsideLow DensityMedium DensityHigh DensityOffice and CommercialPublic Facility / InstitutionPark and Recreation FacilityAgricultureOpen SpaceTotal Development1
Hecker Pass Acres 46.2 16.3 99.1 2.2 58.0 0.0 95.7 51.7 46.8 416.0
Glen Loma Acres 0.0 112.9 70.3 26.5 0.0 26.9 8.7 0.0 95.7 341.0
Subtotal 46.2 129.2 169.5 28.7 58.0 26.9 104.3 51.7 142.5 757.0
Existing Development2
Hecker Pass Acres 11.2 7.6 89.3 0.0 36.8 0.0 95.7 16.6 0.1 257.1
Glen Loma Acres 0.0 33.7 70.3 0.3 0.0 24.5 3.9 0.0 22.0 154.7
Subtotal 11.2 41.2 159.6 0.3 36.8 24.5 99.6 16.6 22.1 411.9
Remaining Development3
Hecker Pass Acres 35.0 8.8 9.9 2.2 21.2 0.0 0.0 35.1 46.7 158.8
Glen Loma Acres 0.0 79.2 0.0 26.2 0.0 2.3 4.8 0.0 73.8 186.3
Subtotal 35.0 88.0 9.9 28.4 21.2 2.3 4.8 35.1 120.5 345.1
Existing Average Daily Flow
(560
gpd/acre)
(1,150
gpd/acre)
(2,020
gpd/acre)
(3,000
gpd/acre)
(870
gpd/acre)
(360
gpd/acre)
(0
gpd/acre)
(0
gpd/acre)
(0
gpd/acre)
Hecker Pass gpd 6,261 8,689 180,294 14 31,992 0 0 0 0 227,250
Glen Loma gpd 0 38,706 142,106 979 0 8,834 0 0 0 190,625
Subtotal 6,261 47,395 322,400 993 31,992 8,834 0 0 0 417,875
Remaining Average Daily Flow
(560
gpd/acre)
(1,150
gpd/acre)
(2,020
gpd/acre)
(3,000
gpd/acre)
(870
gpd/acre)
(360
gpd/acre)
(0
gpd/acre)
(0
gpd/acre)
(0
gpd/acre)
Hecker Pass gpd 19,624 10,078 19,915 6,573 18,433 0 0 0 0 74,622
Glen Loma gpd 0 91,127 0 78,496 0 836 0 0 0 170,460
Subtotal 19,624 101,205 19,915 85,069 18,433 836 0 0 0 245,082
2/25/2022
Notes:
1. Unless noted otherwise, development information shown based on Final Hecker Pass Specific Plan (May 2015) and Glen Loma Ranch Specific Plan (May 2014).
2. Existing development area based on a combination of City of Gilroy General Plan Land Use and aerial imagery review.
3. Remaining development area based on a combination of City of Gilroy General Plan Land Use and aerial imagery review.
Specific Plan Units
Land Use Types
Total
Agenda Item 9.1
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Table 2.3 Downtown Specific Plan, Redevelopment and New Development Sewer Flow
Sewer System Master Plan
City of Gilroy
Land Use District Existing
Development
Re-
Development
New
Development
Total
Buildout Residential Commercial
Total
Dwelling
Units2
Residential
Density3
Commercial
Density2 Residential4 Commercial5,6 Weighted7
(acres)(acres)(acres)(acres)%%DU DU/acre FAR gpd/acre gpd/acre gpd/acre (gpd)
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Historic 5.4 0.8 11.7 17.9 44%56%115 6.4 2.5 930 2,175 1,627 20,347
VTA Transit-Oriented
Development -7.8 0.0 7.8 96%4%320 41.0 2.5 5,934 2,175 5,783 45,110
Expansion 33.2 5.6 9.0 47.7 44%56%448 9.4 2.5 1,357 2,175 1,815 26,464
Cannery District 8.4 17.4 11.4 37.2 29%71%760 20.4 2.0 2,953 1,740 2,092 60,201
Transitional 20.1 0.28 0.0 20.4 69%31%79 3.9 1.5 560 1,305 791 218
Civic/Residential Only 14.8 1.3 1.0 17.0 40%60%14 0.8 1.5 119 1,305 831 1,863
Gateway 31.2 11.7 11.4 54.3 73%27%159 2.9 0.75 424 653 485 11,192
Total 113.1 44.8 44.4 202.4 1,895 165,394
9/13/2021
Notes:
1. Development area based on a combination of City of Gilroy General Plan Land Use, Downtown Gilroy Specific Plan, and aerial imagery review.
2. Source: Downtown Gilroy Specific Plan.
3. Residential Density calculated based on Total Dwelling Units and Total Buildout Acres.
4. Residential Unit Factor based on assumed residential density and a per dwelling unit consumption of 145 gpd/DU, which is estimated based on total High Density Residential consumption and number of dwelling units
5. Factors adjusted to account for increase in FAR.
6. SSMP Commercial Unit Factor of 870 gpd/acre assumes a FAR of 1.0.
7. Weighted unit factor based on Estimated Land Use Breakdown and Master Plan Unit Factors.
8. Additional sewer demand for new development and redevelopment estimated using weighted water unit factor.
9. VTA Transit-Oriented Development information based on Gilroy Station Area Visioning Project community presentation. This development plans to develop approximately 7.8 acres of land in the Downtown Historic district into residential housing, retail
space, and transit terminal.
Land Use Properties1 Estimated Land Use
Breakdown2
Development and Land Use
Assumptions Unit Factors Additional Sewer
Flow for
Redevelopment and
New Development8
Agenda Item 9.1
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March 2023 2-9 City of Gilroy
Sewer System Master Plan
o Transitional Land Use District: This development area includes approximately 20
acres, which includes 14 acres of residential and 6 acres of non-residential land
use.
o Civic/Residential Only Land Use District: This development area includes
approximately 17 acres, which includes 7 acres of residential and 10 acres of non-
residential land use.
o Gateway Land Use District: This development area includes approximately 54
acres, which includes 39 acres of residential and 15 acres of non-residential land
use.
2.3 HISTORICAL AND PROJECTED POPULATION
According to California Department of Finance (DOF) population estimates, the 2021 City
population is approximately 56,559 people. From 2015 to present, the City’s service area has
observed an average annual growth rate of approximately 0.7%. This 2023 SSMP is consistent
with the City’s 2020 Urban Water Management Plans (UWMP’s) annual growth rate factor of
1.5%. The current and projected service area population is summarized in Table 2.4.
Estimates of future sewer flows were not based on population, but rather on gross acreage for
residential and non-residential land uses. Future population was used as a means for estimating
the planning horizon of the sewer system.
Agenda Item 9.1
Page 120 of 768
Table 2.4 Historical and Projected Population
Percent Growth
(%)
Historical
2000 41,464 -
2001 42,436 2.3%
2002 43,144 1.6%
2003 43,866 1.6%
2004 45,026 2.6%
2005 45,782 1.7%
2006 46,446 1.4%
2007 47,047 1.3%
2008 48,353 2.7%
2009 48,627 0.6%
2010 48,821 0.4%
2011 49,622 1.6%
2012 50,716 2.2%
2013 52,475 3.4%
2014 53,325 1.6%
2015 54,233 1.7%
2016 54,849 1.1%
2017 55,811 1.7%
2018 56,030 0.4%
2019 56,635 1.1%
2020 56,704 0.1%
Projected
2021 57,555 1.9%
2022 58,418 1.9%
2023 59,294 1.9%
2024 60,184 1.9%
2025 61,086 1.9%
2026 62,003 1.9%
2027 62,933 1.9%
2028 63,877 1.9%
2029 64,835 1.9%
2030 65,807 1.9%
2031 66,794 1.9%
2032 67,796 1.9%
2033 68,813 1.9%
2034 69,845 1.9%
2035 70,893 1.9%
2036 71,957 1.9%
2037 73,036 1.9%
2038 74,131 1.9%
2039 75,243 1.9%
2040 76,372 1.9%
11/15/2021
Notes:
1. Historical populations taken from California Department of Finance Population Estimates E-4.
2. Projected population assuming medium annual growth rate of 1.9% by using values from ADE,
City of Gilroy July 2019 General Plan Alternatives Report.
Year Population 1,2
Sewer System Master Plan
City of Gilroy
Agenda Item 9.1
Page 121 of 768
March 2023 3-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
3.0 CHAPTER 3 – SYSTEM PERFORMANCE AND DESIGN CRITERIA
This chapter presents the City’s performance and design criteria which was used in this analysis
for identifying current system capacity deficiencies and for sizing proposed collection mains and
lift stations.
3.1 HYDRAULIC CAPACITY CRITERIA
In addition to applying the City design standards for evaluating hydraulic capacities; this master
plan included dynamic hydraulic modeling. The dynamic modeling was a critical and essential
element in identifying surcharge conditions resulting from downstream bottlenecks in the gravity
sewers.
3.1.1 Gravity Sewers
Gravity sewer capacities depend on several factors including: material and roughness of the pipe,
the limiting velocity and slope, and the maximum allowable depth of flow. The hydraulic modeling
software used for evaluating the capacity adequacy of the City’s sewer collection system,
InfoSWMM by Innovyze Inc., utilizes the fully dynamic St. Venant’s equation which has a more
accurate engine for simulating backwater and surcharge, in addition to manifolded force mains.
The software also incorporates the use of the Manning Equation in other calculations including
upstream pipe flow conditions.
Manning’s Equation for Pipe Capacity
The Continuity equation and the Manning equation for steady-state flow are used for calculating
pipe capacities in open channel flow. Open channel flow can consist of either open conduits or, in
the case of gravity sewers, partially full closed conduits. Gravity full flow occurs when the conduit
is flowing full but has not reached a pressure condition.
Continuity Equation: Q = V A
Where:
Q = peak flow, in cubic feet per second (cfs)
V = velocity, in feet per second (fps)
A = cross-sectional area of pipe, in square feet (sq. ft.)
Manning Equation: V = (1.486 R2/3 S1/2)/n
Where:
V = velocity, fps
n = Manning’s roughness coefficient
R = hydraulic radius (area divided by wetted perimeter), ft
S = slope of pipe, in feet per foot
Agenda Item 9.1
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March 2023 3-2 City of Gilroy
Sewer System Master Plan
St. Venant’s Equation for Pipe Capacity
Dynamic modeling facilitates the analysis of unsteady and non-uniform flows (dynamic flows)
within a sewer collection system. Some hydraulic modeling programs have the ability to analyze
these types of flows using the St. Venant equation, which take into account unsteady and non-
uniform conditions that occur over changes in time and cross-section within system pipes.
The St. Venant equation is a set of two equations, a continuity equation and a dynamic equation,
that are used to analyze dynamic flows within a system. The first equation, the continuity
equation, relates the continuity of flow mass within the system pipes in terms of: (A) the change in
the cross-sectional area of flow at a point over time and (B) The change of flow over the distance
of piping in the system. The continuity equation is provided as follows:
Continuity Equation: డ
డ௧ +డொ
డ௫ = 0
(A) (B) __
Where:
t = time
x = distance along the longitudinal direction of the channel
Q = discharge flow
A = flow cross-sectional area perpendicular to the x directional axis
The second equation, the dynamic equation, relates changes in flow to fluid momentum in the
system using: (A) Changes in acceleration at a point over time, (B) Changes in convective flow
acceleration, (C) Changes in momentum due to fluid pressure at a given point, (D) Changes in
momentum from the friction slope of the pipe and (E) Fluid momentum provided by gravitational
forces. The dynamic equation is provided as follows:
Dynamic Equation: డொ
డ௧ +డ
డ௧ ቀ𝛽ொమ
ቁ + 𝑔𝐴
డ௬
డ௫ + 𝑔𝐴𝑆 − 𝑔𝐴𝑆 = 0
(A) (B) (C) (D) (E) __
Where:
t = time
x = distance along the longitudinal direction of the channel
Q = discharge flow
A = flow cross-sectional area perpendicular to the x directional axis
y = flow depth measured from the channel bottom and normal to the x
directional axis
Sf = friction slope
So = channel slope
β = momentum
g = gravitational acceleration
Use of this method of analysis provides a more accurate and precise analysis of flow conditions
within the system compared to steady state flow analysis methods. It must be noted that two
Agenda Item 9.1
Page 123 of 768
March 2023 3-3 City of Gilroy
Sewer System Master Plan
assumptions are made for use of St. Venant equations in the modeling software. First, flow is one
dimensional. This means it is only necessary to consider velocities in the downstream direction
and not in the transverse or vertical directions. Second, the flow is gradually varied. This means
the vertical pressure distribution increases linearly with depth within the pipe.
Manning’s Roughness Coefficient (n)
The Manning roughness coefficient ‘n’ is a friction coefficient that is used in the Manning formula
for flow calculation in open channel flow. In sewer systems, the coefficient can vary between
0.009 and 0.017 depending on pipe material, size of pipe, depth of flow, root intrusion,
smoothness of joints, and other factors.
For the purpose of this evaluation, and in accordance with City standards, an “n” value of 0.013
was used for both existing and proposed gravity sewer pipes unless directed otherwise by City
staff based on pipe structural condition. This “n” value is an acceptable practice in planning
studies.
Partial Flow Criteria (d/D)
Partial flow in gravity sewers is expressed as a depth of flow to pipe diameter ratio (d/D). For
circular gravity conduits, the highest capacity is generally reached at 92 percent of the full height
of the pipe (d/D ratio of 0.92). This is due to the additional wetted perimeter and increased friction
of a gravity pipe.
When designing sewer pipelines, it is common practice to use variable flow depth criteria that
allow higher safety factors in larger sizes. Thus, design d/D ratios may range between 0.5 and
0.92, with the lower values used for smaller pipes. The smaller pipes may experience flow peaks
greater than planned or may experience blockages from debris. The City’s design standards
pertaining to the d/D criteria are summarized in Table 3.1.
During peak dry weather flows (PDWF), the maximum allowable d/D ratio for proposed pipes (all
diameters) is 0.75. The maximum allowable d/D ratio for all existing pipes (all diameters) is 0.90.
The criterion for existing pipes is relaxed in order to maximize the use of the existing pipes before
costly pipe improvements are needed.
During peak wet weather flows (PWWF), to avoid premature or unnecessary trunk line
replacements, the capacity analysis allowed the d/D ratio to exceed the dry weather flow criteria
and surcharge. This condition is evaluated using the dynamic hydraulic model and the criteria
listed on Table 3.1, which stipulates that the hydraulic grade line (HGL), even during a surcharged
condition, should be at least three feet below the manhole rim elevation.
Agenda Item 9.1
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Table 3.1 Sewer System Performance and Design Criteria
Pipeline Criteria
Peak Dry Weather Flow Criteria
Peak Wet Weather Flow Criteria
Hydraulic Grade Line (HGL) should be at least 3 foot below the manhole rim
Suggested Master
Plan Criteria
City of Gilroy
General Guidelines1
Minimum Grade
(Velocity = 2.0 ft/s)
Minimum
Capacity
(n= 0.013)
Minimum Grade
(Velocity = 2.5 ft/s)
Minimum
Capacity
(n= 0.013)
(in)(ft/ft)cfs (ft/ft)(cfs)
8 0.0026 0.55 0.0077 0.00
10 0.0019 0.87 0.0057 0.82
12 0.0015 1.23 0.0022 1.29
15 0.0011 1.98 0.0015 1.58
18 0.0009 2.75 0.0012 2.46
21 0.0007 3.76 0.0010 3.54
24 0.0006 5.05 0.0008 4.82
27 0.0005 6.47
30 0.0004 7.94
33 0.0004 9.34
36 0.0004 11.78
42 0.0003 15.90
Lift Station Criteria
Lift Stations: When permitted by City Engineer. Firm Capacity to meet Peak Wet
Weather Flow.
9/28/2020
Notes:
1. Source: City of Gilroy General Guidelines, August 2014.
Existing Sewer Trunks: Maximum allowable d/D of 0.90
Proposed Sewer Trunks: Maximum allowable d/D of 0.75
Sewer System Master Plan
City of Gilroy
Pipe
Size
Agenda Item 9.1
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March 2023 3-5 City of Gilroy
Sewer System Master Plan
Minimum Pipe Sizes and Design Velocities
In order to minimize the settlement of sewage solids, it is standard practice in the design of gravity
sewers to specify that a minimum velocity of 2 feet per second (fps) be maintained when the
pipeline is half-full. At this velocity, the sewer flow will typically result with self-cleaning of the pipe.
Due to the hydraulics of a circular conduit, velocity of half-full flows approaches the velocity of
nearly full flows. Table 3.1 lists the minimum slopes, varying by pipe size, in accordance with the
City’s design standards. The design standards also specify minimum pipe sizes, depending on
the peak dry weather flows, as shown on Table 3.1.
Changes in Pipe Size
When a smaller gravity sewer pipe joins a larger pipe, the invert of the larger pipe is generally to
maintain the same energy gradient. One of the methods used to approximate this condition
includes placing the 80 percent depth point (d/D at 0.8) from both sewers at the same elevation.
For master planning purposes, and in the absence of known field data, sewer crowns were
matched at the manholes.
3.1.2 Force Mains and Lift Stations
The Hazen-Williams formula is commonly used for the design of force mains as follows:
Hazen Williams Velocity Equation: V = 1.32 C R0.63 S0.54
Where:
V = mean velocity, fps
C = roughness coefficient
R = hydraulic radius, ft
S = slope of the energy grade line, ft/ft
The value of the Hazen-Williams ‘C’ varies and depends on the pipe material and is also
influenced by the type of construction and pipe age. A ‘C’ value of 110 was used in this analysis.
The minimum recommended velocity in force mains is at 2 feet per second. The economical
pumping velocity in force mains ranges between 3 and 5 fps. A maximum desired velocity is
typically around 7 fps and a maximum not-to-exceed velocity is at 10 fps.
The capacities of pump stations are evaluated and designed to meet the peak wet weather flows
with one standby pump having a capacity equal to the largest operating unit. The standby pump
provides a safety factor in case the duty pump malfunctions during operations and allows for
maintenance.
3.2 DRY WEATHER FLOW CRITERIA
Sewer unit flow factors are coefficients commonly used in planning level analysis to estimate
future average daily sewer flows for areas with predetermined land uses. The unit factors are
multiplied by the number of dwelling units or gross acreages for residential categories, and by the
gross acreages for non-residential categories, to yield the average daily sewer flow projections.
Agenda Item 9.1
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March 2023 3-6 City of Gilroy
Sewer System Master Plan
3.2.1 Unit Flow Factors Methodology
Sewer unit factors are developed by using water consumption records and applying a return to
sewer ratio for each land use to estimate sewer flow coefficients. There are several methods for
developing the unit factors. This analysis relied on the use of the City’s water consumption billing
records, which lists the monthly water consumption per customer account, by land use type, to
estimate the unit factors within the service area.
3.2.2 Average Daily Sewer Unit Flow Factors
Sewer flow factors were based on water demands as extracted from the City’s water consumption
billing records. A return to sewer ratio was applied to each unadjusted water demand factor for
individual land uses, and sewer flows were balanced to WWTP flows. Generally, non-residential
land uses return the majority of the water demand to the sewer collection system. These unit
factors were estimated at 90 percent return to sewer ratio. The same concept can be applied to
low-, medium, and high-density residential lots, which were estimated to range from 65 percent to
80 percent return to sewer ratio, respectively. Low density rural residential lots, such as the
Hillside residential lots often have the lowest return to sewer ratio. This is largely due to water loss
for landscape irrigation. Hillside residential lots were estimated at 50 percent return to sewer ratio.
Lastly, unit factors were adjusted to 100 percent occupancy and rounded.
This analysis generally indicates that existing residential land uses have higher flow generation
factors than that of non-residential land uses. The existing unit factor analysis is shown on Table
3.2, the unit factors are shown on Table 3.3.
3.2.3 Peaking Factors
The sewer collection system is evaluated based on its ability to convey peak sewer flows.
Peaking factors represent the increase in sewer flows experienced above the average dry
weather flows (ADWF). The various peaking conditions are numerical values obtained from a
review of historical data and, at times, tempered by engineering judgement.
The peaking conditions that are significant to hydraulic analysis of the sewer collection system
include:
Peak Dry Weather Flows (PDWF)
Peak Wet Weather Flows (PWWF)
Typical values for peaking factors of 2.0 or less are generally used to estimate peak flows at
treatment facilities where flow fluctuations are smoothed out during the time of travel in the sewer
collection system, while peaking factors between 3.0 and 4.0 are used to estimate peak flows in
the smaller upstream areas of the system where low flow conditions are prone to greater
fluctuations.
Agenda Item 9.1
Page 127 of 768
Table 3.2 Sewer Flow Unit Fator Analysis
Sewer System Master Plan
City of Gilroy
Unadjusted Water
Unit Factors
Unadjusted
Wastewater Unit
Factor
Balance to 2019
Average Dry
Weather Flows 2
Vacancy Rate 3,4,5 Recommended
Factor
Balance Using
Recommended Unit
Factor
(acres)(gpd/acres)(kgal/year)(gpd)(gpd/acres)(gpd)(%)(gpd/acres)(gpd)(gpd/acres)(gpd)
Residential
Hillside Residential 444 1,074 173,798 476,159 0.500 537 238,079 3.5%556 246,412 560 248,387
Low Density Residential 1,704 1,699 1,056,612 2,894,827 0.650 1,104 1,881,638 3.5%1,143 1,947,495 1,150 1,959,704
Medium Density Residential 100 2,782 101,072 276,910 0.700 1,948 193,837 3.5%2,016 200,621 2,020 201,044
High Density Residential 249 3,616 328,708 900,570 0.800 2,893 720,456 3.5%2,994 745,672 3,000 747,193
Subtotal - Residential 2,496 1,660,190 4,548,466 3,034,010 3,140,200 3,156,329
Non-Residential
Office and Commercial 6 623 893 203,171 556,633 0.900 804 500,970 7.5%864 538,542 870 542,280
Industrial 7 376 849 116,593 319,433 0.900 764 287,490 2.0%779 293,239 780 293,518
Public Facility / Institution 8,9 237 388 33,560 91,945 0.900 349 82,751 2.0%356 84,406 360 85,345
Neighborhood District 94 966 33,023 90,474 0.900 869 81,427 3.5%900 84,277 900 84,295
Subtotal - Non-Residential 1,330 386,347 1,058,485 952,636 1,000,464 1,005,438
Other
Park and Recreation Facility 1,232 356 159,972 438,279 0.000 0 0 0.0%0 0 0 0
Vacant 2,391 73 64,109 175,641 0.000 0 0 0.0%0 0 0 0
Open Space 1,282 101 47,417 129,910 0.000 0 0 0.0%0 0 0 0
Subtotal - Other 4,905 271,498 743,830 0 0 0
Total Developed Area 8,731 2,318,035 6,350,781 3,986,646 4,140,664 4,161,767
11/6/2020
Notes:
1. 2019 Water Consumption provided by City staff on August 12, 2020.
2. Recorded 2019 Average Dry Weather Flow equal to 3.94 mgd according to 2019 flows from Influent Flow Data provided by City staff on June 3, 2020.
3. Residential vacancy rate extracted from California Department of Finance Sheet E-5 published 2020.
4. Office and Commercial vacancy rate extracted from Cushman & Wakefield Silicon Valley Retail MarketBeat report published Q2 2020.
5. Industrial vacancy rate extracted from Cushman & Wakefield Silicon Valley Industrial MarketBeat report published Q2 2020.
6. "Office and Commercial" contains development and consumption for "Visitor Serving Commercial", "General Services Commercial", and "Profesional Office".
7. "Industrial" contains development and consumption for "General Industrial" and "Campus Industrial".
8. "Public Facility / Institution" contains development and consumption for "Public/Quasi-Public Facility" and "Educational Facility".
9. Existing acreage of Public Facility land use excludes City's Wastewater Treatment Plant.
Existing Land Use Classification
Existing
Development within
City Limits
Existing Average Daily Wastewater Unit Factors
Consumption1 Wastewater Flows Wastewater Flows at 100% Occupancy Recommended Wastewater Unit
Factor
Annual Consumption Projected Flows at 100% Occupancy
Return to Sewer
Ratio
Agenda Item 9.1
Page 128 of 768
Table 3.3 Recommended Sewer Unit Factors
Sewer System Master Plan
City of Gilroy
Recommended
Factor
(gpd/net acre)
Residential
Hillside Residential 560
Low Density Residential 1,150
Medium Density Residential 2,020
High Density Residential 3,000
Non-Residential
Office and Commercial 870
Industrial 780
Public Facility / Institution 360
Neighborhood District 900
11/20/2020
Land Use
Classification
Agenda Item 9.1
Page 129 of 768
March 2023 3-9 City of Gilroy
Sewer System Master Plan
This master plan used 24-hour diurnal patterns for dry weather flows tributary to each flow
monitor, as shown on Figure 3.1, Figure 3.2, and Figure 3.3. These diurnal patterns are
comprised on peaking factors meant to simulate the hourly change in MDDWF within the system,
averaging a factor of 1.0 over 24 hours. The PDWF is used for evaluating the capacity adequacy
of the sewer system, and to meet the criteria set forth in the City standards.
3.3 WET WEATHER FLOW CRITERIA
The wet weather flow criteria accounts for the infiltration and inflows (I&I) that seep into the City’s
sewer system during storm events.
3.3.1 Infiltration and Inflow
Groundwater infiltration and inflow is associated with extraneous water entering the sewer through
defects in pipelines and manholes. Infiltration occurs when groundwater rises or the soil is
saturated due to seasonal factors such as a storm event which causes an increase in flows in the
sewer system. The ground water will enter the sewer system through cracks in the pipes or
deteriorating manholes. Inflow occurs when surface water enters the sewer collection system from
storm drain cross connections, manhole covers, or roof/footing drains. Figure 3.4 was developed
by King County, Washington and was included in this chapter to illustrate the typical causes of
infiltration and inflow.
There are several accepted methodologies for estimating infiltration and inflows (I&I). These
include:
Methodology 1. Based on Acreages. In this methodology, factors that may range
between 400 and 1,500 gallons per day (gpd) or more are applied to acreages for
estimating the I&I component.
Methodology 2. Based on Linear Feet of Pipe. In this methodology, factors that may
range between 12 and 30 or more gallons per day per inch diameter per 100 linear feet
(gpd/inch diameter/100LF) are applied to linear feet of gravity sewers.
Methodology 3. Based on a percentage of Average Dry Weather Flows. In this
methodology, Infiltration and Inflows (I&I) are calculated based on a percentage of the
average dry weather flow.
Methodology 4. Based on flow monitoring data. In this methodology, infiltration and
inflows are determined by analyzing flow monitoring data of current and past flow
monitoring efforts.
This capacity analysis and master plan based the infiltration and inflow on specific flow
monitoring data from the Villalobos and Associates (V&A) 2014 Flow Monitoring Program
(Appendix A). Thus, the infiltration and inflows are reasonable and reflect the actual behavior
of the sewer collection system.
Agenda Item 9.1
Page 130 of 768
January 26, 2021
LEGEND
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Figure 3.1
Hydraulic Model Diurnals
Sewer System Master Plan
City of Gilroy
Peaking Factor
3
Agenda Item 9.1
Page 131 of 768
January 26,2021
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Figure 3.2
Hydraulic Model Diurnals
Sewer System Master Plan
City of Gilroy
Peaking Factor
Agenda Item 9.1
Page 132 of 768
January 26, 2021
LEGEND
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Figure 3.3
Hydraulic Model Diurnals
Sewer System Master Plan
City of Gilroy
Peaking Factor
Agenda Item 9.1
Page 133 of 768
September 22, 2020Figure 3.4Infiltration and Inflow SourcesSewer System Master Plan City of GilroyLEGENDSource: King County, WAhttp://www.kingcounty.gov/environment/wastewater/II/What.aspx?print=1Inflow Sources (Black Text)Infiltration Sources(White Text)Agenda Item 9.1Page 134 of 768
March 2023 3-14 City of Gilroy
Sewer System Master Plan
3.3.2 Sewer System Flow Monitoring
In 2014 V&A’s services were used for a temporary flow monitoring program to capture eleven
sites during dry and wet weather flows. These locations V&A monitored are documented on Table
3.4 and shown graphically on Figure 3.5. The rain gauge data for the V&A flow monitoring period
was obtained from V&A. There were three rain gauges used for the wet weather analysis. The
V&A rain gauges, were located in the North-East, West and South-West portion of the City. The
north-east rain gauge was located near Dryden Ave and New Ave, the west rain gauge was
located near Santa Teresa Blvd and Lerma Way, and the south-west rain gauge was located in
the western foothills near Santa Teresa Blvd and Ballybunion Ct. The flow monitoring and rain
data was used in this analysis to calibrate the computer hydraulic model to average dry weather
flow and wet weather flow conditions.
The City also provided flow data from the South County Regional Wastewater Authority WWTP.
This flow data was used to analyze the seasonal flow patterns the City’s sewer system
experiences and to gauge the effects the wet weather season has on the sewer system.
3.3.3 10-Year 24-Hour Design Storm
A synthetic design storm is typically used to evaluate the sewer collection system’s response
during wet weather flow conditions. The design storm information was collected from the National
Oceanic and Atmospheric Administration (NOAA) Atlas 14 Volume 6 (Table 3.5).
10-Year Frequency. Industry standards include design storms that range between 5-year
and 20-year events. Based on current regulatory trends, a 10-year storm event was
chosen for the City of Gilroy to evaluate the capacity adequacy of the sewer collection
system.
24-Hour Duration. Peak flows from a storm event are usually caused by brief intense
rains, that can happen as part of an individual event or as a portion of a larger storm. The
24-hour storm duration is longer than needed to determine peak flow but aids in identifying
infiltration and inflows a sewer system may experience during a storm event.
Balanced Rainfall Centered Distribution. The National Resources Conservation
Service, previously known as the Soil Conservation Service, has developed rainfall
distributions for wide geographic regions based on traditional Depth-Duration-Frequency
(DDF) rainfall data. In this methodology, the highest rainfall intensity is placed at the
center of the storm. Incrementally lower intensities are placed on alternating sides of the
peak.
Thus, the NOAA Atlas 14 Depth Duration Frequency (DDF), 10-year 24-hour (10yr-24hr) design
storm, with a balanced rainfall distribution, was used to evaluate the capacity adequacy of the
City’s sewer collection system during wet weather flow conditions.
Agenda Item 9.1
Page 135 of 768
!C(!C(!C(!C(!C(!C(!C(!C(!C(!C(!C(£¤101UV152SUNRISE DRSANTA TERESA BLKERN AVWREN AVTHIRD STSECOND STP RI N C E V A L L E S T SIXTH STTENTH STUVASM U R R AY A V RENZLEWIS STM O N T E R E Y S T
GOLDEN GATE AVBUENA VISTA AVM AR C E L L A A V LEAVESLEY RDS A N Y S ID R O A V BLOOMFIELD AVF R A Z IE R L A K E R D
M O N T E R E Y S T SOUTHSIDE DRS A N T A T E R E S A B L CASTRO VALLEY RDEAG LE R IDG E D R
CLUB DRDAY RDMANTELLI DRUV152UV152UV£¤101U vas C reekUvas CreekLlagas C reekLlagas Creek LN PARKSite #1MH ID: S113DM201Site #2MH ID: S102CM201Site #3MH ID: S091CM501Site #4MH ID: S100DM201Site #5MH ID: S076CM402Site #7MH ID: S079AM401Site #8MH ID: S079AM103Site #9MH ID: S048AM401Site #10MH ID: S047CM207Site #11MH ID: S037CM307Site #6MH ID: S064DM205Figure 3.5Flow Meter LocationsSewer System Master Plan City of Gilroy5Updated: January 11, 2016File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig6-2FlowMeterLocations_051221.mxdGIS00.510.25MileLegend!C(Flow MetersModeled Gravity Pipes by Size8" and Smaller10" - 21"24" and LargerNon-Modeled PipesFlow Meter BasinsCountry ClubEagle RidgeGilroyJoint TrunkLeavesley-ChurchMantelliNinth StreetOld GilroySouthside-LuchessaThomasWelburnRoadsRailroadsCity LimitsUrban Growth BoundaryRivers & CreeksWaterbodiesArea(gr. ac.)Country Club 732Eagle Ridge888Gilroy766Joint Trunk818Leavesley‐Church181Mantelli1,014Ninth Street137Old Gilroy566Southside‐Luchessa 1,661Thomas343Welburn456Basin Agenda Item 9.1Page 136 of 768
Table 3.4 Flow Monitoring Locations
Pipe Information Tributary Areas
Size Upstream
Pipe Slope Metered Basins Area
(in)(ft/ft)(gr. ac.)
1 S113DM201 Southside Dr east of Rossi Ln 27 0.0029 Southside-Luchessa, Thomas, Eagle
Ridge, Country Club 3,624
2 S102CM201 ROW north of Southside Drive 24 0.0006 Gilroy, Old Gilroy, Ninth Street,
Welburn 1,925
3 S091CM501 ROW north of Southside Drive 33 0.0014 Joint Trunk, Leavesley-Church,
Mantelli
2,013 +
Morgan Hill
4 S100DM201 West of Luchessa Ave and Monterey St 12 from W 0.0065 Thomas 343
5 S076CM402 Uvas Park Dr and Wren Ave 10 from SW 0.0030 Eagle Ridge 888
6 S064DM205 ROW west of 3rd St and Santa Teresa Blvd 24 0.0012 Country Club 732
7 S079AM401 ROW east of 9th St and Crocker Ln 10 0.0026 Ninth Street 137
8 S079AM103 Renz Ln north of HWY 101 and 10th St interchange 14 0.0015 Old Gilroy 566
9 S048AM401 Leavesley Rd off 101N Ramp 33 0.0015 Leavesley-Church, Mantelli 1,195 +
Morgan Hill
10 S047CM207 Southwest of Welburn Ave and Church St 10 from SW 0.0053 Welburn 456
11 S037CM307 Mantelli Dr and Wren Ave 18 from W 0.0021 Mantelli 1,014
1/7/2016
Sewer System Master Plan
City of Gilroy
Site No.GIS Manhole ID Location
Agenda Item 9.1
Page 137 of 768
Table 3.5 Precipitation Depth-Duration-Frequency
Sewer System Master Plan
City of Gilroy
2-Year 5-Year 10-Year 25-Year 100-Year
(in)(in/hr)(in)(in/hr)(in)(in/hr)(in)(in/hr)(in)(in/hr)
5-min 0.17 1.98 0.22 2.59 0.26 3.10 0.32 3.82 0.41 4.97
10-min 0.24 1.42 0.31 1.85 0.37 2.22 0.46 2.73 0.59 3.56
15-min 0.29 1.14 0.37 1.50 0.45 1.79 0.55 2.20 0.72 2.87
30-min 0.40 0.79 0.52 1.03 0.62 1.24 0.76 1.52 0.99 1.98
1-hr 0.56 0.56 0.73 0.73 0.87 0.87 1.07 1.07 1.40 1.40
2-hr 0.84 0.42 1.11 0.56 1.33 0.67 1.63 0.82 2.14 1.07
3-hr 1.06 0.35 1.40 0.47 1.68 0.56 2.07 0.69 2.71 0.90
6-hr 1.49 0.25 1.98 0.33 2.39 0.40 2.96 0.49 3.86 0.64
12-hr 2.04 0.17 2.79 0.23 3.40 0.28 4.22 0.35 5.46 0.46
24-hr 2.73 0.11 3.83 0.16 4.69 0.20 5.83 0.24 7.51 0.31
Note:
9/28/2020
1. Source: NOAA Atlas 14 Volume 6 Version 2 for Gilroy.
Duration
Agenda Item 9.1
Page 138 of 768
March 2023 3-18 City of Gilroy
Sewer System Master Plan
The selected 10-year 24-hour design storm was further compared to historical storm events,
between February 2014 and March 2014, as documented on Table 3.6 and shown graphically on
Figure 3.6. The table lists the total rainfall volume, duration, peak hour intensity, and total
monthly rainfall (if available) for each storm event.
Figure 3.6 is intended to show the diurnal comparison between the design storm and the two
storm events experienced during February and March of 2014. The comparison indicates that,
based on the balanced centered hyetograph, the design storm’s peak hour value is at 0.89 inches
per hour (in/hr), while the February 26th and March 1st storms’ peak values are 0.23 and 0.56 in/hr
respectively. This comparison illustrates the more conservative nature of the design storm and
the relatively small storm events experienced in February and March 2014.
Agenda Item 9.1
Page 139 of 768
Date
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
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3/8/2014
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3/8/20140
0.1
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1 3 5 7 9 11 13 15 17 19 21 23Unit Intensity (Unitless)Time (hours)
Historical Storm Event: February 28, 2014 (2.20 in)Historical Storm Event: February 26, 2014 (1.06 in)Design Storm (4.69 in)
October 27,2016
Figure 3.6
10-Year 24-Hour Storm
(Design vs Historical Storm)
Sewer System Master Plan
City of Gilroy
LEGEND
Agenda Item 9.1
Page 140 of 768
Table 3.6 Storm Events Analysis
Sewer System Master Plan
City of Gilroy
Single Rainfall Event Volume and
Intensity
Volume Peak Intensity
(in)(in//hr)
February 26- February 27, 2014 < 1-year 1.06 0.23
February 28 - March 1, 2014 2-Year 6 Hour 2.19 0.56
Design Storm 10-Year 24-Hour 4.69 0.89
11/15/2021
Storm Event Estimated Return
Interval
Agenda Item 9.1
Page 141 of 768
March 2023 4-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
4.0 CHAPTER 4 – EXISTING SEWER COLLECTION FACILITIES
This chapter provides a description of the City’s existing sewer collection system facilities
including gravity trunks, force mains, lift stations, and sewer collection basins. The chapter also
includes a brief description of the SCRWA WWTP, which treats and disposes of the wastewater
for the City.
4.1 SEWER COLLECTION SYSTEM OVERVIEW
The City provides sewer collection services to approximately 17,000 residential, commercial,
industrial, and institutional accounts. The City’s collection system consists of approximately 167
miles of up to 60-inch gravity sewer pipes that convey flows towards the SCRWA WWTP, on
Southside Drive, as shown on Figure 4.1.
A system-wide pipe inventory, listing the total length by pipe diameter, is shown on Table 4.1.
This table is based on information extracted from the City’s GIS and was updated to reflect the
review of construction drawings provided by City Staff. The 8-inch and 12-inch diameter pipes
account for 68 percent of the total sewer pipe lengths.
4.2 SEWER COLLECTION BASINS AND TRUNKS
Due to topography, the sewer collection system is divided into four separate dendritic sewer
collection basins, each defining the boundaries of a sewer collection trunk system. The following
sixteen sewer collection trunks were created, Gilroy Trunk, Southside-Luchessa Trunk, Third-
Princevalle Subtrunk, Country Club Subtrunk, Thomas Subtrunk, Uvas Park Subtrunk, Eagle
Ridge Subtrunk, Ninth Street Subtrunk, Old Gilroy Subtrunk, Forest-Swanston Subtrunk, San
Ysidro Subtrunk, Forest-Murray Subtrunk, Leavesley-Church Subtrunk, Welburn Subtrunk,
Mantelli Subtrunk, and Saint Teresa-Long Meadow Subtrunk. The sewer trunk system for each
collection basin is shown on Figure 4.2.
4.2.1 Gilroy Trunk
The Gilroy trunk discharges into the SCRWA WWTP as a 42-inch gravity pipe. The trunk begins
as an 18-inch pipeline on Leavesley Road approximately 400 feet east of the Murray Ave and
Leavesley Road intersection. Beginning from Leavesley Road, the trunk parallels the west side
US HWY 101 to I.O.O.F. Ave where it increases to a 27-inch pipeline and continues its path to E
Sixth St. From E Sixth St, the pipeline increases to a 30-inch pipe and siphons under US HWY
101 to the east side of the highway. Across the highway, the pipeline decreases to a 24-inch pipe
and follows frontage of the commercial building space to E 10th St. From E 10th St, continuing the
alignment, the pipe crosses through parking space and under other commercial buildings via
Right-Of-Way to approximately 500 feet west of the intersection of Camino Arroyo and Holloway
Rd where it increases to a 42-inch pipeline. Then the pipeline follows the dirt path in the south-
Agenda Item 9.1
Page 142 of 768
È6"#"ıÈ6"#"ıÈ6"#"ı£¤101UV152SUNRISE DRSANTA TERESA BLKERN AVWREN AVTHIRD STSECOND STP RI N C E V A L L E S T SIXTH STTENTH STUVASM U R R AY A V RENZLEWIS STM ON T E R E Y S T
GOLDEN GATE AVFITZGERALD RDS AN T A T E RE S A B L RUCKER AVBUENA VISTA AVC E N T E R A V
M ARCE
L L A A V LEAVESLEY RDS A N Y S ID R O A V BLOOMFIELD AVF R A Z IE R L A K E R D
M O N T E R E Y S T SOUTHSIDE DRS ANT A TE R ES A B L
S A N T A T E R E S A B L CASTRO VALLEY RDEA G LE RID G E D R
CLUB DRDAY RDMANTELLI DRUV152UV152UV25£¤10133/18331812
1 5
12
15103333183 3 3 3/2 4
183 3 /2 4
3 3 /4 23 3/4 2
Uvas CreekUvas CreekLlag as C reekPajaro RiverLlagas CreekUvas Creek3 0 3 0 2 7
1 8
18332 7
18181010151212101010101818101215 1 21215
1 5 10 LN10101010101 2
18
33 2 7
10103 3 121 2
1 2 302715121010881010101 0 1 0 10
18181212122424242418151 8 181810101010121215181218121218
81 8
121 8 18181 8 27/181212181027/18182 7
101818273 3 /4 2
181212 PARK DR².WWTPSS-1SS-22 7
2 4
2 4
2 4 SS-33 6 363 6 Figure 4.1Existing SewerCollection SystemSewer System Master Plan City of Gilroy5Updated: September 17, 2021File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig4-1_ExistingModelSyst_091721.mxdGIS00.510.25MileLegendModeled Gravity Pipes by Size8" or Smaller10" - 18"24" or GreaterNon-Modeled SystemÈ6"#"ıLift StationNon-Modeled PipesRoadsRailroadsCity LimitsUrban Growth BoundaryRivers & CreeksWaterbodiesAgenda Item 9.1Page 143 of 768
È6"#"ıÈ6"#"ıÈ6"#"ı£¤101UV152SUNRISE DRSANTA TERESA BLKERN AVWREN AVTHIRD STSECOND STP RI N C E V A L L E S T SIXTH STTENTH STUVASM U R R AY A V RENZLEWIS STM ON T E R E Y S T
GOLDEN GATE AVFITZGERALD RDS AN T A T E RE S A B L RUCKER AVBUENA VISTA AVC E N T E R A V
M ARCE
L L A A V LEAVESLEY RDS A N Y S ID R O A V BLOOMFIELD AVF R A Z IE R L A K E R D
M O N T E R E Y S T SOUTHSIDE DRS ANT A TE R ES A B L
S A N T A T E R E S A B L CASTRO VALLEY RDEA G LE RID G E D R
CLUB DRDAY RDMANTELLI DRUV152UV152UV25£¤10133/18331812
1 5
12
15103333183 3 3 3/2 4
183 3 /2 4
3 3 /4 23 3/4 2
Uvas CreekUvas CreekLlag as C reekPajaro RiverLlagas CreekUvas Creek3 0 3 0 2 7
1 8
18332 7
18181010151212101010101818101215 1 21215
1 5 10 LN10101010101 2
18
33 2 7
10103 3 121 2
1 2 302715121010881010101 0 1 0 10
18181212122424242418151 8 181810101010121215181218121218
81 8
121 8 18181 8 27/181212181027/18182 7
101818273 3 /4 2
181212 PARK DR².WWTPSS-12 7
2 4
2 4
2 4 SS-3Ninth Street SubtrunkJoint TrunkGilroy TrunkSouthside-Luchessa TrunkWelburn SubtrunkUvas Park SubtrunkEagle Ridge SubtrunkThird-Princevalle SubtrunkCountry Club SubtrunkThomas SubtrunkForest-Swanston SubtrunkMantelli SubtrunkSanta Teresa-Long MeadowSubtrunkLeavesley-Church SubtrunkSan Ysidro SubtrunkForest-Murray SubtrunkOld Gilroy SubtrunkSS-23 6 363 6
Relief TrunkFigure 4.2Existing ModeledTrunk SystemSewer System Master PlanCity of Gilroy5Updated: September 17, 2021File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig4-2_ExistingModelTrunk_091721.mxdGIS00.510.25MileLegendModeled Gravity Pipes by Size8" or Smaller10" - 18"24" or GreaterNon-Modeled SystemÈ6"#"ıLift StationNon-Modeled PipesRoadsRailroadsCity LimitsUrban Growth BoundaryRivers & CreeksWaterbodiesAgenda Item 9.1Page 144 of 768
Table 4.1 Existing Sewer Pipe Inventory
Sewer System Master Plan
City of Gilroy
(in)(feet)(miles)
City Pipes
≤62 154,358 29.2
8 463,234 87.7
10 81,809 15.5
12 58,195 11.0
14 327 0.1
15 16,330 3.1
16 136 0.03
18 43,284 8.2
24 13,447 2.5
27 12,542 2.4
30 914 0.2
42 5,810 1.1
48 375 0.1
Total 850,760 161.1
Joint Trunk Pipes3
21 202 < 0.1
24 5,679 1.1
27 4,407 0.8
30 2,776 0.5
33 22,132 4.2
42 246 < 0.1
60 96 < 0.1
Total 35,537 6.7
5/20/2021
Notes:
1. Source: GIS Received from City staff on September 10, 2020.
2. Includes pipelines of unknown diameter.
3. Indicates Joint Trunk pipelines south of intersection at
Fitzgerald Avenue and Monterey Road.
Pipe Size Length
Agenda Item 9.1
Page 145 of 768
March 2023 4-5 City of Gilroy
Sewer System Master Plan
easterly fashion to Southside Dr. At Southside Dr, the 42-inch gravity pipe discharges into the
SCRWA WWTP.
4.2.2 Southside-Luchessa Trunk
The Southside-Luchessa Trunk discharges into the WWTP via the 42-inch gravity pipe of Gilroy
Trunk. The trunk begins at the intersection of W Luchessa Ave and Monterey as a 27-inch gravity
main. From the intersection, the trunk follows W Luchessa Ave in the eastward direction to Rossi
Ln. From Rossi Ln, the trunk flows south-east to Southside Dr, turns east, and discharges into the
42-inch Gravity Main near SCRWA WWTP as a 27-inch pipeline.
4.2.3 Third-Princevalle Subtrunk
The Third-Princevalle Subtrunk discharges into the Southside-Luchessa Trunk, at the intersection
of Monterey Rd and W Luchessa Ave, as a 18-inch pipeline. The trunk begins at the Santa Teresa
Blvd and Third St intersection as a 12-inch pipeline. Flowing eastward on Third St, the pipeline
turns south on Santa Theresa Dr, then east on Fourth St, increases to a 18-inch pipe on Miller
Ave and flows south to W Sixth St. Keeping its size at 18-inch, the pipeline flows north-east on W
Sixth St to Princevalle St, turns south-east on Princevalle St and flows to the Princevalle Channel
easement. Here, the trunk turns east and flows under the Princevalle Channel easement to
Monterey St. At Monterey St, the trunk follows the street alignment in the south-east direction and
flows into the Southside-Luchessa Subtrunk as an 18-inch pipe.
4.2.4 Country Club Subtrunk
The Country Club Subtrunk discharges into the Third-Princevalle Subtrunk, at the intersection of
Santa Teresa Blvd and Third St, as a 24-inch pipeline. The trunk begins as a 15-inch pipe
approximately 300 feet south of the intersection of Burchell Rd and Bluebell Dr on Burchell Rd.
Flowing on Burchell Rd, the pipe increases to an 18-inch and flows south to Hecker Pass Hwy.
After crossing Hecker Pass Hwy, the trunk follows the eastern and then northern banks of Uvas
Creek, increases in size to a 24-inch, flows to Santa Teresa Blvd and Third St where it discharges
into the Third-Princevalle Subtrunk as a 24-inch.
4.2.5 Thomas Subtrunk
The Thomas Subtrunk discharges into the Southside-Luchessa Trunk, at the intersection of
Monterey Rd and W Luchessa Ave, as an 18-inch pipeline. The pipeline begins on Thomas Rd
and Alder St intersection as a 10-inch pipeline. From the intersection, the pipe flows northward on
Thomas Rd to W Luchessa Ave. At the intersection the trunk increases in size to a 15-inch
pipeline for approximately 300 feet, then decreases down to a 12-inch and flows eastward
following the alignment of W Luchessa Ave to Monterey Rd. At Monterey Rd, the trunk flows into
the Southside-Luchessa Trunk.
Agenda Item 9.1
Page 146 of 768
March 2023 4-6 City of Gilroy
Sewer System Master Plan
4.2.6 Uvas Park Subtrunk
The Uvas Park Subtrunk discharges into the Third-Princevalle Subtrunk, at the intersection of W
Tenth St and Princevalle St, as a 12-inch pipeline. The pipeline begins on Uvas Park Dr,
approximately 450 feet south-east of the intersection of Santa Barbara Dr and Hersman Dr, as a
12-inch size. Following Uvas Park Dr, the trunk jogs over to Crawford Dr at the extended
alignment of Crawford St. On Crawford Dr, the trunk flows south-easterly as a 12-inch pipe to
Wren Ave. From Wren Ave, the trunk extends under residential property lines to Hoxley St. At the
south-east corner of Hoxley St, the trunk jogs over to W Eighth St, flows south on Yorktown Dr to
Greenwich Dr. Keeping at the size of 12-inches the trunk flows north-east on Greenwich Dr to
Orchard Dr, then south to W Tenth St, where it flows north-east on W Tenth St to Princevalle St.
At the intersection, the trunk flows into the Third-Princevalle Subtrunk as a 12-inch pipeline.
4.2.7 Eagle Ridge Subtrunk
The Eagle Ridge Subtrunk discharges into the Uvas Park Subtrunk, at the intersection of Wren
Ave and Crawford Dr, as an 18-inch pipeline. The pipeline begins at the intersection of Muirfield
Way and Club Dr as a 10-inch pipeline. From the intersection the trunk flows in the south-east
direction on Club Dr, jogs north of property line at the intersection of Club Dr and St Andrews Cir,
then follows the alignment of St Andrews Cir for 1,600 ft. From here, the trunk jogs to Santa
Teresa Blvd, increases in size to a 12-inch and follows the bike trail to Grenache Way. At
Grenache Way, the trunk increases to a 15-inch pipeline, flows to the intersection of Syrah Ct,
further increases to an 18-inch pipe and flows north-east to the intersection of Wren Ave and
Crawford Dr. At the intersection, the trunk flows into the Uvas Park Subtrunk.
4.2.8 Ninth Street Subtrunk
The Ninth Street Subtrunk discharges into the Gilroy Trunk, on Renz Ln approximately 300 feet
north-west of the entrance from Pacheco Pass Hwy to US HWY 101, as a 10-inch pipeline. The
trunk begins approximately 45 feet east of W Ninth St and Princevalle St intersection. Flowing
north-east on Ninth St, the trunk crosses under US HWY 101, follows the Renz Ln and flows into
Gilroy Trunk.
4.2.9 Old Gilroy Subtrunk
The Old Gilroy Subtrunk discharges into the Joint Morgan Hill – Gilroy Trunk, on Renz Ln
approximately 300 feet north-west of the entrance from Pacheco Pass Hwy to US HWY 101, as
an 18-inch pipeline. The trunk begins as a 10-inch pipeline approximately 200 feet south-west of
the intersection of Rosanna St and W Seventh St. Flowing north-east on W Seventh St, the trunk
turns north on Monterey St, then east on Hornlein Ct, increases to a 12-inch pipe and flows under
the railroad tracks to Old Gilroy St. Following the alignment of Old Gilroy St, the pipeline increases
to a 15-inch on Forest St, then to an 18-inch on Crocker Ln where it crosses under US HWY 101,
and then flows to Renz Ln. Here, the trunk follows the alignment of Renz Ln to Joint Morgan Hill –
Gilroy Trunk where it discharges as an 18-inch.
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4.2.10 Forest Subtrunk
The Forest Subtrunk discharges into the Old Gilroy Subtrunk, at the intersection of Forest St and
Old Gilroy St, as a 12-inch pipeline.
The pipeline begins on the southern side of the intersection of Swanston St and Leavesley Rd as
a 12-inch pipeline and flows south-east on Swanston Ln, turns north-east on Swanston Ln, then
turns south-east on Forest Ave. The pipeline follows the Forest Avenue alignment south-east
where it flows into the Old Gilroy Subtrunk.
4.2.11 San Ysidro Subtrunk
The San Ysidro Subtrunk discharges into the Joint Morgan Hill – Gilroy Trunk, near the southern
side of the intersection of Leavesley Rd and San Ysirdo Ave, as a 15-inch pipeline. The pipeline
begins at the intersection of Cohansey Ave and Noname Uno as a 12-inch pipeline, increases to a
15-inch pipeline as it flows on Noname Uno, turns north-east on E Las Animas Ave, then turns
south-east on San Ysidro Ave. The pipeline follows the San Ysidro Ave alignment as a 15-inch
pipeline to Leavesley Rd, and flows into the Joint Morgan Hill – Gilroy Trunk just south of the
intersection.
4.2.12 Forest Murray Subtrunk
The Forest Murray Subtrunk discharges into the Joint Morgan Hill – Gilroy Trunk, at the
intersection of Forest St and Leavesley Rd, as a 15-inch pipeline. The trunk begins at the
intersection of E Las Animas Ave and Murray Ave as a 15-inch pipeline. From the intersection, the
trunk flows south-east on Murray Ave to Tomkins Ct. Approximately 400 feet, on Murray Ave, from
the intersection of Tomkins Ct, the trunk decreases in size to an 8-inch, then increases to a 12-
inch before it turns west on Kishimura Dr. Flowing westward on Kishimura Dr to Forest St, the
trunk turns south-east on Forest St where it flows to Leavesley Rd. Approximately 100 feet north
of the intersection of Forest St and Leavesley Rd, the pipeline increases to 15-inch in size and
flows into the Joint Morgan Hill – Gilroy Trunk.
4.2.13 Leavesley-Church Subtrunk
The Leavesley-Church Subtrunk discharges into the Gilroy Trunk, approximately 400 feet north-
west of the intersection of Leavesley Rd and Murray Ave on Leavesley Rd, as an 18-inch pipe.
The pipeline begins at the intersection of Farrell Ave and Church St as an 18-inch pipe and
follows the south-easterly alignment of Church St to Welburn Ave. On Welburn Ave, the gravity
main turns east and flow towards Monterey St. At Monterey St, the street alignment changes from
Welburn Ave to Leavesley Rd. The trunk follows the Leavesley Rd alignment to Murray Ave where
the pipe flows into the Gilroy Trunk just north-west of the intersection.
4.2.14 Welburn Subtrunk
The Welburn Subtrunk discharges into the Leavesley-Church Subtrunk, at the intersection of
Church St and Welburn Ave, as a 10-inch pipeline. The trunk begins at the Taryn Ln and Welburn
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Ave intersection as a 10-inch pipe. Flowing eastward on Welburn Ave, the pipeline crosses under
Santa Teresa Blvd, Kern Ave, and Wren Ave before it flows into the Leavesley-Church Subtrunk
on Church St as the same 10-inch pipeline.
4.2.15 Mantelli Subtrunk
The Mantelli Subtrunk discharges into the Joint Morgan Hill – Gilroy Trunk, at the intersection of
Wren Ave and Mantelli Dr, as an 18-inch pipeline. The trunk begins at the western cul-de-sac of
Bay Tree Dry near Calle Del Rey as a 10-inch pipeline. The trunk follows the Bay Tree Dr
alignment eastward to Santa Teresa Blvd, increases in size to an 18-inch pipe, then follows the
channel easement, parallel to Zinnia St, to Mantelli Dr. Here the trunk follows the Mantelli Dr
alignment to Joint Morgan Hill – Gilroy Trunk where it discharges as an 18-inch pipe.
4.2.16 Santa Teresa-Long Meadow Subtrunk
The Santa Teresa-Long Meadow Subtrunk discharges into the Mantelli Subtrunk, on Santa
Teresa Blvd near the eastern cul-de-sac of Bay Tree Dr, as an 18-inch pipeline. The trunk begins
just north of Quail Walk Dr on Eagle View Way as a 10-inch pipeline. Flowing south on Eagle
View Way, the trunk turns into a 12-inch pipe on Longmeadow Dr and follows the Longmeadow Dr
alignment. Flowing on Longmeadow Dr, the trunk increases to a 15-inch pipeline at Calle Del Rey,
continues on Longmeadow Dr to Santa Teresa Blvd where it decreases to a 14-inch pipeline.
Flowing south on Santa Teresa Blvd, the trunk increases in size to an 18-inch at the intersection
of Lerma Way. Continuing south, the pipeline discharges into the Mantelli Subtrunk as a 18-inch
pipe.
4.2.17 Morgan Hill – Gilroy Joint Sewer Trunk
Some of the sewer flows for City of Gilroy from the collection basins, their trunks and subtrunks
discharge into the joint Morgan Hill – Gilroy sewer trunk, also known as the Joint Trunk. The Joint
Trunk begins at the intersection of Monterey Rd and California Ave. From the intersection, the
trunk flows south-east to the City of Gilroy where it discharges into the South Country Regional
Wastewater Authority WWTP, located south of the City on Southside Dr.
The Joint Trunk is maintained by a Joint Exercise of Powers Agreement between the City of Gilroy
and the City of Morgan Hill and dated May 19th, 1992. This agreement establishes the formation of
the South County Regional Wastewater Authority (SCRWA), and includes an exhibit that
documents the pipeline capacities and the capacity allocation for each segment of the Joint Trunk.
The agreement stipulates that a 4.0 MGD capacity allocation exists in the Joint Trunk up to Farrell
Avenue, and a 7.7 MGD capacity reservation up to the WWTP, to accommodate Morgan Hill’s
flows. In the current agreement, the City of Morgan Hill is responsible for all maintenance of the
Trunk up to Highland Avenue in San Martin. Additional maintenance costs incurred south of
Highland Avenue are shared with Gilroy per the JPA capacity allocated for each section of the
trunk. Design information on the Joint Trunk, which is approximately 5.8 miles in length, were
obtained from City records, and summarized in Table 4.1.
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Sewer System Master Plan
4.3 LIFT STATIONS
When routing flows by gravity is not possible due to adverse grades, lift stations are used to pump
flows. The City currently maintains three lift stations in the sewer collection system, as
summarized on Table 4.2.
Table 4.2 lists each pump station with relevant information obtained from the City’s records such
as location, wet well capacity, number of pumps, pump capacity, and controls, if data was
available. The pump stations are operated to turn “on” or “off” based on their levels in their wet
wells.
The City’s lift stations were not included in the hydraulic model and capacity analysis as they were
not along the modeled sewer collection system.
4.4 FLOW DIVERSIONS
The sewer collection system contains diversion structures that are intended to provide
opportunities to route flow to various sewer pipelines that may have excess capacity.
City of Gilroy's sewer collection system contains diversion structures that are intended to provide
opportunities to route flow away from sewer trunks with capacity limitations to sewer pipelines that
may have excess capacity. The City’s sewer system includes the following active diversions along
the trunk sewer system:
Rossi Lane Diversion. The Rossi Lane diversion is located just south-east of the intersection of
E Luchessa Ave and Rossi Ln. Sewer flows from the western portion of the City near foothills and
downstream, flow into the E. Luchessa Ave and Rossi Ln intersection to this diversion. Most of the
flow continues south along the Rossi Ln alignment but the City has the option to divert flow north-
east from the diversion to Gilroy Trunk if needed. For the purposes of the hydraulic model, the
flow is only diverted to the Gilroy Trunk if there are adverse backup conditions.
I.O.O.F. Diversion. The I.O.O.F. diversion is located at the intersection of Forest St and I.O.O.F.
Ave. Sewer flows from the northern and western area of this intersection flow into this diversion.
From here, the flow can either continue southwardly on Forest St or flow east to the Gilroy Trunk.
In the existing system, the flow continues on I.O.O.F. Ave towards the Gilroy Trunk where it
discharges via a 10-inch pipeline.
4.5 SOUTH COUNTY REGIONAL WASTEWATER AUTHORITY
WASTEWATER TREATMENT PLANT
The South County Regional Wastewater Authority WWTP is an 8.5 million gallons per day (MGD)
ADWF primary, secondary and tertiary treatment facility. The treatment facility is located at the
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Table 4.2 Existing System Lift Station Inventory
Sewer System Master Plan
City of Gilroy
Pump Capacity Diameter Depth Per Tank Total
(gpm)(ft)(ft)(gal)(gal)(hrs)
Lift Stations
SS-1 Desiderio Wy / Farrell Ave 2004 -------
SS-2 Roundstone Dr / Strath Pl 2005 -------
SS-3 Santa Teresa Blvd (Gavilan
College)1966 2 420 -----
SS-4 Miller Ave/ Uvas Pkwy (Private
Lift Station)--------
1/25/2021
Notes:
1. Source: GIS Received from City staff on September 10, 2020.
2. Source: 2019 Sewer System Management Plan
Capacity Holding
Time
Station Location
Lift Station Information 1,2
Construction
Year No. of Pumps
Pump Information 2 Wet Well Dimensions
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Sewer System Master Plan
end of Southside Dr. The original plant was completed in 1990 with a plant expansion occurring in
2007 to provide the plants current capacity and technology. The SCRWA WWTP has a design
capacity of 9 MGD, but is limited to 8 mgd due to the chlorine contact basin capacity and it can
accommodate a design peak dry weather flow of up to 15.1 MGD. The plant is currently operating
at an average flow of 6.65 MGD with a low of approximately 4.78 MGD and a peak of
approximately 10 MGD in 2019.
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March 2023 5-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
5.0 CHAPTER 5 –SEWER FLOWS
This chapter summarizes historical sewer flows experienced at the South County Regional
Wastewater Authority (SCRWA) WWTP and defines flow terminologies relevant to this evaluation.
This chapter discusses the design flows used in the hydraulic modeling effort and capacity
evaluation. The design flows include the existing condition (existing customers) and buildout
development conditions.
5.1 FLOWS AT THE SCRWA WWTP
The sewer flows collected and treated at the SCRWA WWTP vary monthly, daily, and hourly.
While the dry weather flows are influenced by customer uses, the wet weather flows are
influenced by the severity and length of storm events and the condition of the system.
Flow data influent to the SCRWA WWTP was obtained from City operation staff. The flow data
covered a period from 2010 to 2019. From this data monthly, daily, and peak daily flows, were
determined as summarized on Table 5.1.
The following definitions are intended to document relevant terminologies shown on Table 5.1:
Average Annual Flow (AAF). The average annual flow is the total annual flow, or
average monthly flow, for a given year, expressed in daily or other time units. This flow
includes the combined average of the average dry weather flow (ADWF) and average wet
weather flow (AWWF).
Average Dry Weather Flow (ADWF). The average dry weather flow occurs on a daily
basis during the dry weather season, with no evident reaction to rainfall. The ADWF also
includes the Base Wastewater Flow (BWF). The base wastewater flow is the average flow
that is generated by residential, commercial, and industrial users. The flow pattern from
these users varies depending on land use types.
Average Wet Weather Flow (AWWF). This average wet weather flow occurs on a daily
basis during the wet weather season. In addition to the flow components in the ADWF, the
AWWF includes infiltration and inflow from storm rainfall events.
Maximum Month Dry Weather Flow (MMDWF). This maximum month flow occurs during
the dry weather season.
Maximum Month Wet Weather Flow (MMWWF). This maximum month flow occurs
during the wet weather season.
Maximum Day Dry Weather Flow (MDDWF). This is the highest measured daily flow that
occurs during a dry weather season.
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Average Annual Flow 1 Seasonal Average Maximum Month Total SCRWA Plant Flow 2
(MGD)(GPCD)(MGD)(MGD)(MGD)(MGD)(MGD)(MGD)(MGD)(MGD)
2010 48,821 3.60 74 -3.62 3.59 3.83 3.89 4.05 4.38 7.19 8.99
2011 49,611 3.91 79 9%3.76 4.07 4.13 4.76 4.27 6.17 7.37 11.98
2012 50,698 3.70 73 -5%3.66 3.74 3.81 3.97 4.36 5.07 7.13 9.68
2013 52,378 3.58 68 -3%3.55 3.61 3.68 3.83 4.28 4.58 7.18 7.67
2014 53,208 3.50 66 -2%3.49 3.50 3.58 3.77 3.76 4.76 6.57 8.45
2015 54,123 3.48 64 -1%3.44 3.50 3.48 3.61 3.60 4.47 6.02 8.24
2016 54,916 3.76 68 8%3.72 3.79 3.81 3.99 4.67 5.67 6.99 8.97
2017 55,932 4.88 87 30%4.23 6.04 5.04 7.31 6.30 10.06 8.34 16.46
2018 56,198 3.79 67 -22%3.80 3.79 3.90 4.15 4.77 5.36 7.08 8.58
2019 56,854 4.15 73 9%3.94 4.31 4.34 5.38 5.49 5.96 7.97 10.00
2010 -0.99 --1.00 0.99 1.06 1.07 1.12 1.21 --
2011 -1.04 --1.00 1.08 1.10 1.27 1.14 1.64 --
2012 -1.01 --1.00 1.02 1.04 1.08 1.19 1.39 --
2013 -1.01 --1.00 1.02 1.04 1.08 1.21 1.29 --
2014 -1.00 --1.00 1.00 1.03 1.08 1.08 1.36 --
2015 -1.01 --1.00 1.02 1.01 1.05 1.05 1.30 --
2016 -1.01 --1.00 1.02 1.02 1.07 1.26 1.52 --
2017 -1.15 --1.00 1.43 1.19 1.73 1.49 2.38 --
2018 -1.00 --1.00 1.00 1.03 1.09 1.26 1.41 --
2019 -1.05 --1.00 1.10 1.10 1.37 1.39 1.51 --
3 Year Average 1.40 1.38
1/14/2021
Notes:
1. Source:
2010 and 2011 flows from South County Regional WasteWater Authority Community Development Report
2012 - 2015 flows from South County Regional WasteWater Authority Public Works Report
2016 - 2019 flows from Influent Flow Data provided by City staff on June 3, 2020.
2. Total SCRWA Plant Flow Represents combined flow of cities of Morgan Hill and Gilroy.
3. Definitions are as follows:
AAF - Average Annual Flow (annual flow, expressed in daily or other time units)
ADWF - Average Dry Weather Flow (average flow that occurs on a daily basis during the dry weather season)
AWWF - Average Wet Weather Flow (average flow that occurs on a daily basis during the wet weather season)
MMDWF - Maximum Month Dry Weather Flow (maximum month flow during the dry weather season)
MMWWF - Maximum Month Wet Weather Flow (maximum month flow during the wet weather season)
MDDWF - Maximum Day Dry Weather Flow (highest measured daily flow that occurs during a dry weather season)
MDWWF - Maximum Day Wet Weather Flow (highest measured daily flow that occurs during a wet weather season)
PDWF - Peak Dry Weather Flow (highest measured hourly flow that occurs during a dry weather flow)
PWWF - Peak Hour Wet Weather Flow (highest measured hourly flow that occurs during wet weather)
MDWWFMDDWFMDWWF
Table 5.1 Historical Flow Data and Peaking Factors
Sewer System Master Plan
City of Gilroy
Recommended Peaking Fator
Historical Peaking Factors (Applied to ADWF)
MDDWF
Maximum Day
ADWFYearPopulationAAFPer Capita
Flow
Percentage
Change AWWF MMDWF MMWWF
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March 2023 5-3 City of Gilroy
Sewer System Master Plan
Maximum Day Wet Weather Flow (MDWWF). This is the highest measured daily flow
that occurs during a wet weather season.
Table 5.1 shows the City of Gilroy’s average annual flows (AAF) experienced at the SCRWA
WWTP increased from 3.6 MGD in 2010 to 4.15 MGD in 2019, which is an increase of
approximately 15 percent. In general, the AAF flows have decreased from 2010 to 2015, and
increased by approximately 19 percent between 2015 and 2019.
In addition to listing the 2010-2019 flows, and for comparison purposes, the table calculates the
peaking factors applied to the corresponding average annual flows for each year. During wet
weather flows, the maximum daily volume (MDWWF) contributed by the City at the SCRWA
WWTP was 2.38 times higher than the average annual flow.
5.2 EXISTING SEWER FLOWS
The existing sewer flows represented in this Master Plan were based on the City’s water
consumption billing records. The number of acres and corresponding sewer flows are summarized
on Table 5.2.
5.3 BUILDOUT SEWER FLOWS
The land use methodology was used to estimate the buildout flows from the City’s Planning Area
and to be consistent with the General Plan. Table 5.2 documents the total acreages for residential
and non-residential land use, and the undeveloped lands designated for urbanization. The
undeveloped lands were multiplied by the corresponding unit flow factor to estimate the sewer
flows. The buildout average daily flows were calculated at 7.07 MGD.
5.4 SEWER COLLECTION SYSTEM DESIGN FLOWS
The design flows most relevant in this capacity analysis of the sewer collection system, in addition
to the Maximum Day Dry Weather Flows (MDDWF), include the peak dry weather flow (PDWF)
and peak wet weather flow (PWWF).
Peak Dry Weather Flow (PDWF). The PDWF is used for evaluating the capacity
adequacy of the sewer collection system, and to meet the criteria set forth in the previous
chapter and in the City standards.
Peak Wet Weather Flow (PWWF). The PWWF is used for designing the capacity of the
sewer collection system, while allowing acceptable amounts of surcharging in the system.
During PWWF a relaxed criteria was used compared to PDWFs. The hydraulic analysis
allowed surcharging to occur during wet weather conditions with the hydraulic grade line
(HGL) rising up to three feet below the manhole rim. If the HGL at any time was less than
three feet from the manhole rim, the pipe was considered deficient.
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Table 5.2 Future Sewer FlowsSewer System Master PlanCity of GilroyExisting Unchanged Redeveloped Area New Development Total AreaAverage Daily Flow(gpd/acre)(acres)(acres)(acres)(acres)(gpd)ResidentialHillside Residential 560 442 112 353 907 507,789Low Density Residential 1,150 1,583 122 89 1,793.95 2,063,041Medium Density Residential 2,020 58 177 6 240.47 485,750High Density Residential 3,000 67 18 18 103.89 311,678Subtotal ‐ Residential 2,151 429 466 3,045 3,368,258Non‐ResidentialOffice and Commercial1870465281100846736,013Industrial27802932136431,149896,113Public Facility / Institution360559153129841302,621Neighborhood District900038358395355,920City Gateway District90002072724,570Downtown Specific Plan Area3Varies0573289165,683Mixed Use Corridor High87002573328,454Hecker Pass Special Use District4‐0 328 88 416 301,873Glen Loma Ranch4‐0 103 237 341 361,085Industrial Park 780 0 43 40 83 65,069Employment Center8700279251530461,164Subtotal ‐ Non‐Residential 1,3171,5411,8934,7503,698,565OtherPark and Recreation Facility 0 995 0 154 1,149 0Vacant 000000Open Space 0 253 0 1,045 1,298 0Rural County 00283300Subtotal ‐ Other 1,247 28 1,202 2,477 0Total4,7141,9973,56110,2727,066,8233/31/2022Notes:1. Office and Commercial accounts for Visitor Serving Commercial and General Services Commercial Land Use types.2. Industrial accounts for General Industrial and Campus Industrial Land Use types3. Downtown Specific Plan Water Unit Factors vary based on land use.4. Glen Loma and Hecker Pass sewer flow estimated separately, based on itemized land use plan and associated land use factorsSewer Unit FactorTotal Sewer FlowBuildout of Service AreaLand Use ClassificationAgenda Item 9.1Page 156 of 768
March 2023 5-5 City of Gilroy
Sewer System Master Plan
The design flows used in evaluating the capacity adequacy of the sewer collection system are
summarized on Table 5.3. The table lists the peak hour flows for dry and wet weather conditions.
PDWF and PWWF used for evaluating the existing collection system were estimated at 8.79 MGD
and 13.81 MGD, respectively. The PDWF and PWWF used for designing the General Plan
buildout system, including growth, were estimated at 14.66 MGD and 18.95 MGD, respectively.
Agenda Item 9.1
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Table 5.3 Design Flows
Sewer System Master Plan
City of Gilroy
Description Peak Dry
Weather Flow
Peak Wet
Weather Flow
(mgd)(mgd)
Existing 8.79 13.81
Buildout 14.66 18.95
Notes:
3/31/2022
1.Flows shown are extracted from sewer system hydraulic model and
reflect diurnal flow variations and flow attenuation.
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March 2023 6-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
6.0 CHAPTER 6 – HYDRAULIC MODEL
DEVELOPMENT
This chapter describes the development and calibration of the City’s sewer collection system
hydraulic model. The City’s hydraulic model was used to evaluate the capacity adequacy of the
existing system and to plan its expansion to service anticipated future growth.
6.1 HYDRAULIC MODEL SOFTWARE SELECTION
The City’s hydraulic model combines information on the physical characteristics of the sewer
collection system (pipelines, manholes, and diversions) and operational characteristics. The
hydraulic model then performs calculations and solves series of equations to simulate flows in
pipes, including backwater calculations for surcharged conditions.
There are several network analysis software products released by different manufacturers that
can equally perform the hydraulic analysis satisfactorily. The selection of a particular software
depends on user preferences, the sewer collection system’s unique requirements, and the costs
for purchasing and maintaining the software.
The hydraulic modeling software used for evaluating the capacity adequacy of the City’s sewer
collection system, InfoSWMM by Innovyze Inc., utilizes the fully dynamic St. Venant’s equation
which has a more accurate engine for simulating backwater and surcharge conditions, in addition
to having the capability for simulating manifolded force mains. The software also incorporates the
use of the Manning Equation in other calculations including upstream pipe flow conditions. The St.
Venant’s and Manning’s equations are discussed in the System Performance and Design Criteria
chapter.
6.2 HYDRAULIC MODEL DEVELOPMENT
Developing the hydraulic model included system skeletonization, digitizing and quality control,
developing pipe and manhole databases, and sewer loading allocation.
6.2.1 Skeletonization
Skeletonizing the model refers to the process where pipes not essential to the hydraulic analysis
of the system are stripped from the model. Skeletonizing the model is useful in creating a system
that accurately reflects the hydraulics of the pipes within the system. In addition, skeletonizing the
model will reduce complexities of large models, which will also reduce the time of analysis while
maintaining accuracy, but will also comply with the limitations imposed by the computer program.
In the City of Gilroy’s case, skeletonizing was necessary to reduce the model from approximately
4,529 pipes extracted from the GIS to 657 pipes. The modeled pipes included pipes 8-inches in
diameter and larger, in addition to some critical smaller gravity sewer pipes.
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Sewer System Master Plan
Table 4.1 lists the sewer collection system total length of pipes at 167.8 miles, compared to Table
6.1 listing the total length of modeled pipes at 39.4 miles. Thus, approximately 23.5 percent of the
total length of gravity sewers was modeled. The modeled sewer system is shown on Figure 4.1.
6.2.2 Digitizing and Quality Control
The City’s existing sewer collection system was digitized in GIS using serval sources of data and
various levels of quality control. The quality control program included the following:
Sewer System GIS data
Supplemental field surveys
Verification figures
Schematics provided by City staff
After reviewing the available data sources, the hydraulic model was built and verified by City staff.
Using the available sewer collection system data this master plan developed the Sewer collection
system in GIS. Resolving discrepancies in data sources was accomplished by graphically
identifying identified discrepancies and submitting it to City staff for review and comments. City
comments were incorporated in the verified model.
6.2.3 Pipes and Manholes
Computer modeling requires the compilation of large numerical databases that enable data input
into the model. Detailed physical aspects, such as pipe size, ground elevation, invert elevations,
and pipe lengths contribute to the accuracy of the model.
Pipes and manholes represent the physical aspect of the system within the model. A manhole is a
computer representation of a place where sewer flows may be allocated into the hydraulic system,
while a pipe represents the conveyance aspect of the sewer flows. In addition, lift station capacity
and design head settings were not included into the hydraulic model.
6.2.4 Load Allocation
Load allocation consists of assigning sewer flow to the appropriate manholes (nodes) in the
model. The goal is to distribute the loads throughout the model to best represent actual system
response.
Allocating loads to manholes within the hydraulic model required multiple steps, incorporating the
efficiency and capabilities of GIS and the hydraulic modeling software. Determining the sewer
loads was accomplished by using the sewer flow factors developed for this master plan and
presented in chapter 3, and parcel data including acreage and land use. The calculated loads
were allocated to the nearest manhole that serves the corresponding parcel using the capabilities
the hydraulic model has for allocating loads.
Agenda Item 9.1
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(feet)(miles)
City Pipes
8"1,317 0.2
10"50,278 9.5
12"38,328 7.3
14"123 < 0.1
15"13,686 2.6
18"43,284 8.2
24"9,694 1.8
27"9,847 1.9
30"914 0.2
42"5,277 1.0
Total 172,748 32.7
Joint Trunk Pipes1
21"202 < 0.1
24"5,679 1.1
27"4,407 0.8
30"2,776 0.5
33"22,132 4.2
42"246 < 0.1
60"96 < 0.1
Total 35,537 6.7
Notes:
5/20/2021
1. Indicates Joint Trunk pipelines south of intersection at Fitzgerald Avenue
and Monterey Road.
Table 6.1 Modeled Sewer Pipe Inventory
Sewer System Master Plan
City of Gilroy
Pipe Size Length
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March 2023 6-4 City of Gilroy
Sewer System Master Plan
6.3 MODEL CALIBRATION
Calibration is intended to instill a level of confidence in the flows that are simulated, and it
generally consists of comparing model predictions to the 2014 V&A flow monitoring program, and
making necessary adjustments.
6.3.1 Calibration Plan
Calibration can be performed for steady state conditions, which model the peak hour flows, or for
dynamic conditions (24 hours or more). Dynamic calibration consists of comparing the model
predictions to diurnal operational changes in the wastewater flows. The City’s hydraulic model
was calibrated for dynamic conditions.
In sewer collection systems, and when using dynamic hydraulic modeling to evaluate the impact
of wet weather flows, it is common practice to calibrate the model to the following three conditions:
Peak dry weather flows on a weekday and a weekend.
Peak wet weather flows from storm rainfall Event No. 1 (February 26 2014 – February 27
2014).
Peak wet weather flows from storm rainfall Event No. 2 (February 28 2014 – March 1
2014).
After the model is calibrated to these conditions, it is benchmarked and used for evaluating the
capacity adequacy of the sewer collection system, under dry and wet weather conditions.
The hydraulic model is a valuable investment that will continue to prove its worth to the City as
future planning issues or other operational conditions surface. It is recommended that the model
be maintained and updated with new construction projects to preserve its integrity.
6.3.2 2014 V&A Temporary Flow Monitoring Program
A temporary flow monitoring program was included in this project to validate the existing dry and
wet weather flows from each sewer collection basin. The program consisted of installing 11 flow
meters, for a period of 20 days, from February 24, 2014 to March 16, 2014. Villalobos and
Associates (V&A) was retained to install the flow meters, monitor rainfall, and perform an
Infiltration and Inflow analysis. The selected flow monitoring sites are listed on Table 3.4 and
shown on Figure 3.5.
The 2014 V&A Flow Monitoring Program captured two rainfall events and included a summary
report identifying areas of the City that were most affected by rain dependent infiltration and
inflows. The two rainfall events experienced during the flow monitoring period varied in duration
and intensity (Table 3.6), and provided an insight into the sewer system response to storm
conditions.
Agenda Item 9.1
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March 2023 6-5 City of Gilroy
Sewer System Master Plan
During the V&A flow monitoring program; three rain gauges were set up in the City to record storm
events during the monitoring period shown on Figure 3.5. Data from the V&A flow monitoring
effort, as documented in the 2014 V&A Flow Monitoring Program, was used in this analysis to
calibrate the computer hydraulic model to average dry weather flow (ADWF) and peak wet
weather flow (PWWF) conditions.
6.3.3 Dynamic Model Calibration
The calibration process was iterative as it involved calibrating each of the 11 flow monitored sites
and for three calibration conditions: 1) peak dry weather flow, 2) peak wet weather flows from
storm rainfall Event No. 1, and 3) peak wet weather flows from storm rainfall Event No. 2.
The rain events of February 26, 2014 and February 27, 2014 (Event No. 1) and February 28, 2014
and March 01, 2014 (Event No. 2), as listed on Table 3.6, were used to calibrate the hydraulic
model to the wet weather conditions. The diurnal curves for each of the 11 sites were extracted
from the 2014 V&A Flow Monitoring Program and the data was used for comparison purposes
with the hydraulic model predictions. The calibration effort continued until it yielded acceptable
results for each site and for each of the three calibration conditions.
The calibration results for each flow monitoring site are documented in Appendix B. These
results indicate the calibration effort yielded reasonable comparisons between the flow monitoring
data and the hydraulic model predictions at the 11 sites. The calibration results were reviewed
and approved by City staff, and representative extracts from Appendix B are shown on Figure
6.1 and Figure 6.2. After the calibration process, the hydraulic model was benchmarked for
further analysis and evaluation.
6.3.4 Use of the Calibrated Model
The calibrated hydraulic model was used as an established benchmark in the capacity evaluation
of the existing sewer collection system. The model was also used to identify improvements
necessary for mitigating existing system deficiencies and for accommodating future growth. The
hydraulic model is a valuable investment that will continue to prove its worth to the City as future
planning issues or other operational conditions surface. It is recommended that the model be
maintained and updated with new construction projects to preserve its integrity.
Agenda Item 9.1
Page 163 of 768
Figure 6.1
Site 1 Calibration
Inside WWTP
Sewer System Master Plan
City of Gilroy
LEGEND
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Agenda Item 9.1
Page 164 of 768
Figure 6.2
Site 4 Calibration
W. Luchessa Ave. and Hyde Park Dr.
Sewer System Master Plan
City of Gilroy
LEGEND
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Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 165 of 768
March 2023 7-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
7.0 CHAPTER 7 - EVALUATION AND PROPOSED IMPROVEMENTS
This section presents a summary of the sewer collection system capacity evaluation during peak
dry weather flows and peak wet weather flows for the existing and buildout development
conditions. The recommended sewer collection system improvements needed to mitigate capacity
deficiencies are also discussed in this chapter.
7.1 OVERVIEW
The calibrated hydraulic model was used for evaluating the sewer collection system for capacity
deficiencies during maximum day dry weather flows (MDDWF) and maximum day wet weather
flows (PWWF). Since the hydraulic model was calibrated for dynamic modeling, the analysis
duration was established at 24 hours for most analyses.
The criteria used for evaluating the capacity adequacy of the sewer collection system facilities
(gravity mains, force mains, and lift stations) were discussed and summarized in the System
Performance and Design Criteria chapter.
7.2 EXISTING SEWER SYSTEM CAPACITY EVALUATION
The system performance and design criteria summarized, on Table 3.1, was used as a basis to
judge the adequacy of capacity for the existing sewer collection system. The design flows
simulated in the hydraulic model for existing conditions were summarized on Table 5.3 and they
include:
Existing PDWF = 8.79 MGD
Existing PWWF = 13.81 MGD
During the peak dry weather simulations, the maximum allowable pipe d/D criteria for new pipes
(d/D ratio of 0.75) was used. For existing pipes, the criteria was relaxed to allow a maximum d/D
ratio of 0.90 (full pipe capacity) to prevent unnecessary pipe replacements. During the peak wet
weather simulations, capacity deficiencies included pipe segments with a hydraulic grade line
(HGL) that rises within three feet of the manhole rim elevation.
In general, the hydraulic model indicated that the sewer collection system exhibited acceptable
performance to service the existing customers during peak dry weather flows (Figure 7.1) and
peak wet weather flows (Figure 7.2), with exceptions noted in the following sections.
Agenda Item 9.1
Page 166 of 768
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2 4 ².WWTPSS-33 6 363 6 Figure 7.2Existing Modeled SewerSystem Analysis for PWWF Sewer System Master PlanCity of Gilroy5Updated: September 17, 2021File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig7-2_PWWF_091721.mxdGIS00.510.25MileLegendSurcharging Manholes!(Surcharging!(HGL within 3ftof Ground ElevationPipe d/Dd/D > 0.9d/D 0.75 - 0.9d/D 0.5 - 0.75Modeled Gravity Pipes by Size8" or Smaller10" - 18"24" or GreaterNon-Modeled SystemÈ6"#"ıLift StationNon-Modeled PipesRoadsRailroadsCity LimitsUrban Growth BoundaryRivers & CreeksWaterbodiesAgenda Item 9.1Page 168 of 768
March 2023 7-4 City of Gilroy
Sewer System Master Plan
7.2.1 Existing Maximum Dry Weather Flows Capacity Evaluation
The existing dry weather flow analysis indicated that the existing sewer collection system
exhibited acceptable performance to service the existing customers during peak dry weather
flows, as documented in Figure 7.1, with the following exceptions:
Welburn Avenue, from Kern Avenue to Wren Avenue. This segment experiences d/D
ratios over 0.9.
Welburn Avenue, from Hannah Street to Church Street. This segment experiences d/D
ratios over 0.9.
Loof Avenue, from Monterey Road to Murray Avenue. This segment experiences d/D ratio
between 0.9 and 1.
7.2.2 Existing Maximum Day Wet Weather Flows Capacity Evaluation
The wet weather analysis is intended to document the impact of significant rainfall events on the
existing system, and to identify the improvements necessary to limit sewer overflows. The design
criteria for wet weather events allows pipeline surcharging into the manhole to within three feet of
the rim elevation. The existing wet weather flow analysis indicated that the existing sewer
collection system exhibited acceptable performance to service the existing customers during peak
wet weather flows, as documented in Figure 7.2, with the following exceptions:
Loof Avenue, from Monterey Road to Forest Street. This segment experiences manhole
flooding.
Welburn Avenue, from Kern Avenue to Wren Avenue. This segment experiences
surcharging into the manhole within three feet of the rim elevation.
Forest Street, from Polk Court to Old Gilroy Street. This segment experiences surcharging
into the manhole within three feet of the rim elevation.
Old Gilroy Street, from Hanna Street to Monterey Road. This segment experiences
surcharging into the manhole within three feet of the rim elevation.
Third Street, from Los Padres Court to Santa Theresa Drive. This segment experiences
surcharging into the manhole within three feet of the rim elevation.
Santa Theresa Drive, from Third Street to Fourth Street. This segment experiences
surcharging into the manhole within three feet of the rim elevation.
7.3 ULTIMATE BUILDOUT CAPACITY IMPROVEMENTS
The system performance and design criteria summarized on Table 3.1, was used as a basis to
judge the capacity adequacy of the existing sewer collection system. The design flows simulated
Agenda Item 9.1
Page 169 of 768
March 2023 7-5 City of Gilroy
Sewer System Master Plan
in the hydraulic model for the General Plan buildout were summarized on Table 5.3 and they
include:
Buildout PDWF = 14.66 MGD
Buildout PWWF = 18.95 MGD
Sewer pipelines are recommended to serve future growth inside the City and increase the
reliability of the sewer collection system as well. The proposed improvements for the sewer
system are listed on Table 7.1. This table lists the master plan assigned improvement number
(e.g., WP-1) by different collection basins, along with other relevant information including
alignment descriptions, pipe size, and pipe length. The improvement number is further defined in
the Capital Improvement Program chapter (Chapter 8). The improvements are described in detail
on the following pages and shown of Figure 7.3.
7.3.1 Gravity Main Improvements
This section documents the gravity main improvements. This section documents pipeline
improvements within the City of Gilroy sewer collection system service area.
7.3.1.1 Santa Teresa – Long Meadow Subtrunk
This section documents pipeline improvements within the Santa Teresa – Long Meadow
Subtrunk.
SLP-1: Replace existing 10-inch gravity main with a new 12-inch gravity main on Santa
Teresa Boulevard, from Sunrise drive to Long Meadow Drive.
7.3.1.2 Welburn Subtrunk
This section documents pipeline improvements within the Welburn Subtrunk.
WP-1: Replace existing 10-inch gravity main with a new 12-inch gravity main on Welburn
Avenue, from Chisea Drive to Aspen Way.
WP-2: Replace existing 10-inch gravity main with a new 12-inch gravity main on Welburn
Avenue, from Church Street to Hanna Street.
7.3.1.3 Forest-Swanston Subtrunk
This section documents pipeline improvements within the Forest Swanston Subtrunk.
FP-1: Replace existing 10-inch gravity main with a new 12-inch gravity main on Loof
Avenue, from Monterey Road to Forest Avenue.
FP-2: Replace existing 12-inch gravity main with a new 15-inch gravity main on Forest
Street, from Lewis Street to Old Gilroy Street.
Agenda Item 9.1
Page 170 of 768
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Table 7.1 Schedule of Improvements
Sewer System Master Plan
City of Gilroy
Pipeline Improvements
New/Parallel/
Replace Diameter Length
(in)(in)(ft)
Gravity Main Improvements
Santa Teresa - Long Meadow Subtrunk
SLP-1 Future Growth Gravity Main Santa Teresa Blvd From Sunrise Dr to Longmeadow Dr 10 Replacement 12 2,025
Welburn Subtrunk
WP-1 Existing Deficiency Gravity Main Welburn Ave From Chiesa Dr to Aspen Wy 10 Replacement 12 1,700
WP-2 Existing Deficiency Gravity Main Welburn Ave From Church St to Hanna St 10 Replacement 12 750
Forest-Swanston Subrunk
FP-1 Existing Deficiency Gravity Main Ioof Ave From Monterey Rd to Forest Ave 10 Replacement 12 1,150
FP-2 Existing Deficiency Gravity Main Forest St From Lewis St to Old Gilroy St 12 Replacement 15 1,875
Old Gilroy Subtrunk
OP-1 Existing Deficiency Gravity Main Old Gilroy St From 75' w/o Railroad St to Railroad
St 10 Replacement 12 100
OP-2 Existing Deficiency Gravity Main Old Gilroy St From Railroad St to Forest St 12 Replacement 15 750
Uvas Park Subtrunk
UP-1 Existing Deficiency Gravity Main Uvas Park Dr From 3rd St to 350 ft e/o Santa
Barbara Dr -New 12 2,375
UP-2 Future Growth Gravity Main Hoxett St / ROW From Wren Ave to Miller Ave 12 Replacement 18 1,550
UP-3 Future Growth Gravity Main Yorktown Dr From Miller Ave to Greenwich Dr 12 Replacement 18 1,725
UP-4 Future Growth Gravity Main Greenwich Dr From Yorktown Dr to Orchard Dr 12 Replacement 18 575
UP-5 Future Growth Gravity Main Orchard Dr From Greenwich Dr to W 10th St 12 Replacement 18 200
UP-6 Future Growth Gravity Main W 10th St From Orchard Dr to Princevalle St 12 Replacement 18 1,350
Thomas Subtrunk
TP-1 Future Growth Gravity Main London Pl From Monterey Rd to Princevalle St 18 Replacement 21 2,775
TP-2 Future Growth Gravity Main Monterey Rd From Luchessa Ave to London Pl 18 Replacement 21 1,525
6/30/2021
Improv. No.Alignment Limits Existing
DiameterImprov. Type
Agenda Item 9.1
Page 172 of 768
March 2023 7-8 City of Gilroy
Sewer System Master Plan
7.3.1.4 Old Gilroy Subtrunk
This section documents pipeline improvements within the Old Gilroy Subtrunk.
OP-1: Replace existing 10-inch gravity main with a new 12-inch gravity main on Old Gilroy
Street, from approximately 75 feet west of Railroad Street to Railroad Street.
OP-2: Replace existing 12-inch gravity main with a new 15-inch gravity main on Old Gilroy
Street, from Railroad Street to Forest Street.
7.3.1.5 Uvas Park Subtrunk
This section documents pipeline improvements within the Uvas Park Subtrunk.
UP-1: Construct a new 12-inch gravity main along Uvas Park Drive, from Third Street to
approximately 350 feet east of Santa Barbara Drive.
UP-2: Replace existing 12-inch gravity main with a new 18-inch gravity main on Hoxett
Street and Right of Way, from Wren Avenue to Miller Avenue.
UP-3: Replace existing 12-inch gravity main with a new 18-inch gravity main on Yorktown
Drive, from Miller Avenue to Greenwich Drive.
UP-4: Replace existing 12-inch gravity main with a new 18-inch gravity main on Greenwich
Drive, from Yorktown Drive to Orchard Drive.
UP-5: Replace existing 12-inch gravity main with a new 18-inch gravity main on Orchard
Drive, from Greenwich Drive to West Tenth Street.
UP-6: Replace existing 12-inch gravity main with a new 18-inch gravity main on West
Tenth Street, from Orchard Drive to Princevalle Street.
7.3.1.6 Thomas Subtrunk
This section documents pipeline improvements within the Thomas Subtrunk.
TP-1: Replace existing 18-inch gravity main with a new 21-inch gravity main on London
Place, from Monterey Road to Princevalle Street.
TP-2: Replace existing 18-inch gravity main with a new 21-inch gravity main on Monterey
Road, from Luchessa Avenue to London Place.
Agenda Item 9.1
Page 173 of 768
March 2023 8-1 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
8.0 CHAPTER 8 - CAPITAL IMPROVEMENT
PROGRAM
This chapter provides a summary of the recommended sewer collection system improvements to
mitigate existing capacity deficiencies and service future growth. This chapter also presents the
cost criteria and methodologies for developing the capacity improvement costs. Finally, a cost
allocation analysis, usually used for cost sharing purposes, is also included.
8.1 COST ESTIMATE ACCURACY
Cost estimates presented in the capacity improvement costs were prepared for general master
planning purposes and, where relevant, for further project evaluation. Final costs of a project will
depend on several factors including the final project scope, costs of labor and material, and
market conditions during construction.
The Association for the Advancement of Cost Engineering (AACE International), formerly known
as the American Association of Cost Engineers, has defined three classifications. These
classifications are presented in order of increasing accuracy: Order of Magnitude, Budget, and
Definitive.
Order of Magnitude Estimate. This classification is also known as an “original estimate”,
“study estimate”, or “preliminary estimate”, and is generally intended for master plans and
studies.
This estimate is not supported with detailed engineering data about the specific project,
and its accuracy is dependent on historical data and cost indices. It is generally expected
that this estimate would be accurate within -30 percent to +50 percent.
Budget Estimate. This classification is also known as an “official estimate” and generally
intended for pre-design studies. This estimate is prepared to include flow sheets and
equipment layouts and details. It is generally expected that this estimate would be
accurate within -15 percent to +30 percent.
Definitive Estimate. This classification is also known as a “final estimate” and prepared
during the time of contract bidding. The data includes complete plot plans and elevations,
equipment data sheets, and complete specifications. It is generally expected that this
estimate would be accurate within -5 percent to +15 percent.
Costs developed in this study should be considered “Order of Magnitude” and have an expected
accuracy range of -30 percent and +50 percent.
Agenda Item 9.1
Page 174 of 768
March 2023 8-2 City of Gilroy
Sewer System Master Plan
8.2 COST ESTIMATE METHODOLOGY
Cost estimates presented in this chapter are opinions of probable construction and other relevant
costs developed from several sources including cost curves, Akel experience on other master
planning projects, and input from City staff on the development of public and private cost sharing.
Where appropriate, costs were escalated to reflect the more current Engineering News Records
(ENR) Construction Cost Index (CCI).
This section documents the unit costs used in developing the opinion of probable construction
costs, the Construction Cost Index, the land acquisition costs, and markups to account for
construction contingency and other project related costs.
8.2.1 Unit Costs
The unit cost estimates used in developing the Capital Improvement Program are summarized on
Table 8.1. Sewer pipeline unit costs are based on length of pipe per chosen diameter. The unit
costs are intended for developing the Order of Magnitude estimate, and do not account for site
specific conditions, labor or material costs during the time of construction, final project scope,
implementation schedule, detailed utility and topography surveys, investigation of alternative
routings for pipelines, and other various factors. The capital improvement program included in this
report accounts for construction and project-related contingencies as described in this chapter.
8.2.2 Construction Cost Index
Costs estimated in this study are adjusted utilizing the Engineering News Record (ENR)
Construction Cost Index (CCI), which is widely used in the engineering and construction
industries.
The costs in this Storm Drainage System Master Plan were benchmarked using a 20-City national
average ENR CCI of 13,176, reflecting a date of March 2023.
8.2.3 Construction Contingency Allowance
Knowledge about site-specific conditions for each proposed project is limited at the master
planning stage; therefore, construction contingencies were used. The estimated construction
costs in this master plan include a 30 percent contingency allowance to account for unforeseen
events and unknown field conditions.
8.2.4 Project Related Costs
The capital improvement costs also account for project-related costs, comprising of engineering
design, project administration (developer and City staff), construction management and
inspection, and legal costs. The project related costs in this master plan were estimated by
applying an additional 30 percent to the estimated construction costs.
Agenda Item 9.1
Page 175 of 768
Table 8.1 Unit Costs
Sewer System Master Plan
City of Gilroy
Pipelines
Improvement Type Unit Cost
New/Parallel/Replacement
(in)($/unit length)
8 259
10 289
12 332
15 360
18 389
21 418
24 475
27 535
30 594
36 713
Pipeline Casings
23$ per inch diameter per linear foot
3/28/2023
Notes :
1. Unit costs are based on an ENR CCI Index Value
of 13,176.3 (March 2023).
Pipe
Size
Agenda Item 9.1
Page 176 of 768
March 2023 8-4 City of Gilroy
Sewer System Master Plan
8.3 CAPITAL IMPROVEMENT PROGRAM
This section documents the capital improvement program, including estimated costs and
recommended construction phasing.
8.3.1 Capital Improvement Costs
The Capacity Improvement Program costs for the projects identified in this master plan for
mitigating existing deficiencies and for servicing future growth throughout the City are summarized
on Table 8.2.
Each improvement was assigned a unique code identifier associated with the improvement
pipelines tributary collection basin, and is summarized graphically on Figure 8.1. The estimated
construction costs include the baseline costs plus 30 percent contingency allowance to account
for unforeseen events and unknown field conditions, as described in a previous section. Capital
Improvement Costs include the estimated construction costs plus 30 percent project-related costs
(engineering design, project administration, construction management and inspection, and legal
costs).
8.3.2 Pipelines
The recommended pipeline improvements are grouped by collection basin and listed on Table
8.2. Each improvement includes a general description of the street alignment and limits as well as
existing pipe diameter and length.
The Capital Improvement Program generally includes the following three types of improvements:
Replacement Pipeline, Existing Capacity Deficiency. An existing pipe is recommended
for replacement to mitigate an existing system deficiency. This type of improvement is
listed as Existing Capacity Deficiency on Table 8.2. The recommended sizes for these
improvements are based on buildout flow requirements.
Replacement Pipeline, Capacity Deficiency Triggered by Future Development. An
existing pipe is recommended for replacement where additional flow due to future
development will create a capacity deficiency. This type of improvement is listed as Future
Capacity Increase on Table 8.2.
New Pipeline, Triggered by an Existing Capacity Deficiency. A new pipeline is
proposed to mitigate an existing system deficiency. This type of improvement is listed as
New – Existing Capacity Deficiency on Table 8.2.
The opinion of probable construction costs, for the projects included in this master plan, are based
on the pipe unit costs summarized on Table 8.1.
Agenda Item 9.1
Page 177 of 768
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Table 8.2 Capital Improvement Program
Sewer System Master Plan
City of Gilroy
Pipeline Improvements Infrastructure Costs Suggested Cost Allocation Cost Allocation
Existing
Diameter
New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost Existing
Users
Future
Users
Existing
Users
Future
Users
(in)(in)(ft)($)($)($)($)($)(gpm)(%)(%)($)($)
Gravity Main Improvements
Santa Teresa - Long Meadow Subtrunk
SLP-1 Gravity Main Santa Teresa Blvd From Sunrise Dr to Longmeadow Dr 10 Replacement 12 2,025 332 671,321 671,400 872,900 1,134,800 954 EDU 61%39%689,302 445,498
Subtotal - Santa Teresa - Long Meadow Subtrunk 671,400 872,900 1,134,800 689,302 445,498
Welburn Subtrunk
WP-1 Gravity Main Welburn Ave From Chiesa Dr to Aspen Wy 10 Replacement 12 1,700 332 563,578 563,600 732,700 952,600 Existing Deficiency 90%10%861,520 91,080
WP-2 Gravity Main Welburn Ave From Church St to Hanna St 10 Replacement 12 750 332 248,637 248,700 323,400 420,500 Existing Deficiency 91%9%384,531 35,969
Subtotal - Welburn Subtrunk 812,300 1,056,100 1,373,100 1,246,051 127,049
Forest-Swanston Subrunk
FP-1 Gravity Main Ioof Ave From Monterey Rd to Forest Ave 10 Replacement 12 1,150 332 381,244 381,300 495,700 644,500 Existing Deficiency 93%7%601,483 43,017
FP-2 Gravity Main Forest St From Lewis St to Old Gilroy St 12 Replacement 15 1,875 360 675,064 675,100 877,700 1,141,100 Existing Deficiency 96%4%1,093,639 47,461
Subtotal - Forest-Swanston Subrunk 1,056,400 1,373,400 1,785,600 1,695,122 90,478
Old Gilroy Subtrunk
OP-1 Gravity Main Old Gilroy St From 75' w/o Railroad St to Railroad St 10 Replacement 12 100 332 33,152 33,200 43,200 56,200 Existing Deficiency 89%11%50,159 6,042
OP-2 Gravity Main Old Gilroy St From Railroad St to Forest St 12 Replacement 15 750 360 270,026 270,100 351,200 456,600 Existing Deficiency 89%11%407,516 49,085
Subtotal - Old Gilroy Subtrunk 303,300 394,400 512,800 457,674 55,126
Uvas Park Subtrunk
UP-1 Gravity Main Uvas Park Dr From 3rd St to 350 ft e/o Santa Barbara Dr -New 12 2,375 332 787,352 787,400 1,023,700 1,330,900 Existing Deficiency 39%61%517,772 813,128
UP-2 Gravity Main Hoxett St / ROW From Wren Ave to Miller Ave 12 Replacement 18 1,550 389 602,255 602,300 783,000 1,017,900 2,020 EDU 36%64%370,355 647,545
UP-3 Gravity Main Yorktown Dr From Miller Ave to Greenwich Dr 12 Replacement 18 1,725 389 670,252 670,300 871,400 1,132,900 1,923 EDU 38%62%427,260 705,640
UP-4 Gravity Main Greenwich Dr From Yorktown Dr to Orchard Dr 12 Replacement 18 575 389 223,417 223,500 290,600 377,800 2,152 EDU 38%62%145,055 232,745
UP-5 Gravity Main Orchard Dr From Greenwich Dr to W 10th St 12 Replacement 18 200 389 77,710 77,800 101,200 131,600 2,401 EDU 39%61%51,307 80,293
UP-6 Gravity Main W 10th St From Orchard Dr to Princevalle St 12 Replacement 18 1,350 389 524,545 524,600 682,000 886,600 3,085 EDU 39%61%346,721 539,879
Subtotal - Uvas Park Subtrunk 2,885,900 3,751,900 4,877,700 1,858,470 3,019,230
Thomas Subtrunk
TP-1 Gravity Main London Pl From Monterey Rd to Princevalle St 18 Replacement 21 2,775 418 1,160,665 1,160,700 1,509,000 1,961,700 5,873 EDU 62%38%1,224,966 736,734
TP-2 Gravity Main Monterey Rd From Luchessa Ave to London Pl 18 Replacement 21 1,525 418 637,843 637,900 829,300 1,078,100 5,303 EDU 62%38%672,095 406,005
Subtotal - Thomas Subtrunk 1,798,600 2,338,300 3,039,800 1,897,061 1,142,739
Total Costs
Subtotal - Santa Teresa - Long Meadow Subtrunk 671,400 872,900 1,134,800 689,302 445,498
Subtotal - Welburn Subtrunk 812,300 1,056,100 1,373,100 1,246,051 127,049
Subtotal - Forest-Swanston Subrunk 1,056,400 1,373,400 1,785,600 1,695,122 90,478
Subtotal - Old Gilroy Subtrunk 303,300 394,400 512,800 457,674 55,126
Subtotal - Uvas Park Subtrunk 2,885,900 3,751,900 4,877,700 1,858,470 3,019,230
Subtotal - Thomas Subtrunk 1,798,600 2,338,300 3,039,800 1,897,061 1,142,739
Total Improvement Costs 7,527,900 9,787,000 12,723,800 7,843,681 4,880,119
3/28/2023
Notes :
1.Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,176 (March 2023).
2.Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.
3.Estimated construction cost plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal
costs.
Capital Improv.
Cost 3
Construction
Trigger
Type of
ImprovementImprov. No.Alignment Limits Baseline Constr.
Costs 1
Estimated Const.
Costs 2
Agenda Item 9.1
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March 2023 8-8 City of Gilroy
Sewer System Master Plan
It is assumed that any replacement pipes will be in the same alignment and at the same slope as
the existing pipe. However, this study recommends an investigation of the alignment during the
pre-design stage of each project.
8.3.3 Construction Triggers
As a part of this Master Planning process, construction triggers were developed in an effort to plan
the expansion of the sewer collection system in an orderly manner. The construction triggers for
multiple improvements are based on mitigating an existing system deficiency, increasing hydraulic
reliability, or continuing improvements currently planned by the City. Other improvements replace
existing infrastructure that is not currently deficient but will violate master plan criteria with future
development. The construction triggers quantify the amount of additional development that may
occur before the improvement becomes necessary.
8.3.4 Construction Phasing
The Capacity Improvement Program was divided into the following phases:
Near Term – Fiscal Year: This short-term phase consists of improvements for the fiscal
years (FY) 2022 through 2023 for improvements that are required to resolve existing
deficiencies and other critical pipes in the sewer collection system.
Intermediate Term – Equivalent Dwelling Unit: An equivalent dwelling unit (EDU)
construction trigger is provided for improvements designated as capacity increases for
future development. This trigger is based on remaining capacity in the existing facility
planned for future improvement. The remaining capacity is converted to EDUs assuming
210 gpd/EDU.
8.3.5 Recommended Cost Allocation Analysis
Capacity allocation analysis is needed to identify improvement funding sources, and to establish a
nexus between development impact fees and improvements needed to service growth. In
compliance with the provisions of Assembly Bill AB 1600, the analysis differentiates between the
project needs of servicing existing users and for those required to service anticipated future
developments. Table 8.2 lists each improvement and separates the cost by responsibility between
existing and future users. The cost responsibility is based on model parameters for existing and
future land use, and may change depending on the nature of development.
8.4 JOINT TRUNK CONDITION ASSESSMENT IMPROVEMENTS
The City of Morgan Hill initiated a Joint Trunk Pipeline Condition Assessment Report completed in
January 2021 (Appendix C). This Condition Assessment Report was prepared by Water Works
Engineers on behalf of the City of Morgan Hill, and summarizes the recommendations for the Joint
Trunk sewer main. Improvements within the City of Gilroy’s planning boundaries have been
Agenda Item 9.1
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March 2023 8-9 City of Gilroy
Sewer System Master Plan
extracted from the report and are documented on Table 8.3 and shown graphically in Appendix
C.
The recommended projects were designated as either Emergency condition assessment projects
or Intermediate condition assessment projects depending on their specific renewal choice; their
costs were provided in the Report prepared by Water Works Engineers and are summarized on
Table 8.3. These recommendations were determined as a result of the risk assessment and are
intended to mitigate or determine the condition of extreme or high-risk sewer infrastructure within
the City’s service area. In order to facilitate the prioritization of the projects included in the risk
analysis, each project has been prioritized based on its risk score and condition. Suggested cost
allocation between the City of Morgan Hill and City of Gilroy are based on the Morgan Hill – Gilroy
Joint Trunk Agreement for multi-segments.
8.5 SUGGESTED PIPELINE REPLACEMENT BUDGET
The suggested pipeline replacement budget alternatives are shown on Figure 8.2, and includes
the estimated costs for replacing pipelines by 5-year fiscal periods through the year 2055. The
industry recommended goal of pipeline R&R budgets is at 1.0 percent of system pipeline length
for 100-year pipeline replacement cycle. The cost estimates are starting from a base rate of 4.2
million dollars per year, with a pipeline replacement rate of 1.0 percent of system length per year,
the future costs in 2055 are expected to be approximately 5.1 million dollars per year.
Agenda Item 9.1
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Industry Standard Replacement ScheduleCurrently Available Budget$0$1,000,000$2,000,000$3,000,000$4,000,000$5,000,000$6,000,00020202025203020352040204520502055Dollars per year ($)YearR&R Budget AlternativesFigure 8.2Pipeline Replacement Budget AlternativesSewer System Master PlanCity of GilroyJuly 23, 2021LEGENDAssumptions:1. System Growth: 1 miles of new construction per year (based on historical construction)2. All costs in 2021 dollars3. Weighted average pipeline unit cost = $269/foot4. 30% contengency added for estimated construction cost5. 30% contengency added for capital improvement costCurrently Available Budget (Next 10 Years):$3M/yearIndustry Average Pipe R&R BudgetsExisting Average Budgets at 0.8 %per yearIndustry Goal is at 1.0% per year for 100‐year Pipe Replacement Cycle2021$4.3 M2025$4.4 M2030$4.5 M2035$4.6 M2040$4.7 M2045$4.8 M2050$5.0 M2055$5.1 MAgenda Item 9.1Page 182 of 768
Table 8.3 Joint Trunk Condition Assessment, Cost Estimates
Sewer System Master Plan
City of Gilroy
Pipeline Improvements1 Infrastructure Costs1 Suggested Cost
Allocation5,6 Cost Allocation
Existing
Diameter
New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost Gilroy Morgan
Hill Gilroy Morgan Hill
(in)(in)(ft)($)($)($)($)(%)(%)($)($)
Emergency/Immediate Projects - Pipelines3,5
E-1
MH-116 to MH-116A Gravity Main Leavesley Rd Intersection of South Valley Fwy 33 Open Cut Point Repair 33 35 1,133 39,664 39,700 55,600 50%50%27,800 27,800
E-2
MH-145 to MH-146 Gravity Main Camino Arroyo From 1000' n/o Mayock Rd to Mayock Rd 33 Structural CIPP Lining 33 561 493 276,553 276,600 387,200 50%50%193,600 193,600
E-3
MH-146 to MH-147 Gravity Main Camino Arroyo From Mayock Rd to 150' ne/o Camino Arroyo 33 Structural CIPP Lining 33 206 493 101,551 101,600 142,200 50%50%71,100 71,100
E-4
MH-152 to MH-153 Gravity Main Camino Arroyo From 650' n/o Southside Dr to 325 n/o
Southside Dr 33 Structural CIPP Lining 33 393 493 193,735 193,800 271,300 50%50%135,650 135,650
E-5
MH-153 to MH-154 Gravity Main Camino Arroyo From 325' n/o Southside Dr to 100' n/o
Southside Dr 33 Structural CIPP Lining 33 327 493 161,199 161,200 225,700 50%50%112,850 112,850
Subtotal - Emergency Pipeline Projects 772,900 1,082,000 541,000 541,000
Emergency/Immediate Projects - Manholes3,6
E-6 Manhole Various --Repair
Raising Buried Manholes 4,533 36,264 36,300 50,800 49%51%24,956 25,845
E-7 Manhole Various --Rehabilitation
Cementitious Liners 4,533 145,056 145,100 203,100 45%55%91,788 111,312
Subtotal - Emergency Manhole Projects 1,727,200 2,417,900 1,198,744 1,219,156
Intermediate Projects - Pipelines4,6
I-1 Gravity Main Various --Structural CIPP Lining -24,807 470 11,666,703 11,666,800 16,916,800 50.3%49.7%8,502,173 8,414,627
Subtotal - intermediate Pipeline Projects 11,666,800 16,916,800 8,502,173 8,414,627
Total Costs
Subtotal - Emergency Pipeline Projects 772,900 1,082,000 541,000 541,000
Subtotal - Emergency Manhole Projects 1,727,200 2,417,900 1,198,744 1,219,156
Subtotal - intermediate Pipeline Projects 11,666,800 16,916,800 8,502,173 8,414,627
Total Improvement Costs 13,394,000 19,334,700 9,700,917 9,633,783
3/28/2023
Notes :
1. Source of all identified projects, recommended costs, and contingencies are based on City of Morgan Hill, Joint Trunk Pipeline Condition Assessment Report completed by Water Works Engineers on January 2021. The units were escalated to reflect the current ENR CCI of March 2023.
2. To ensure consistency with the Joint Trunk Pipeline Condition Assessment Report , Capital Improvement Costs include a singular contingency markup of 45% for Emergency Projects and 40% for Intermediate Projects.
3. Contingency for Emergency Projects: Baseline construction costs plus 15% general contingency, plus 15% design contingency, plus 15% construction contingency.
4. Contingency for Intermediate Projects: Baseline construction costs plus 10% general contingency, plus 15% design contingency, plus 15% construction contingency.
5. Suggested Cost Allocation based on Morgan Hill-Gilroy Joint Trunk Agreement.
6. Suggested Cost Allocation based on Morgan Hill-Gilroy Joint Trunk Agreement for multi-segments.
Capital Improv.
Cost2,3,4
8 Manholes
32 Manholes
Improvement ID1 Type of
Improvement Alignment Limits Baseline Constr.
Costs1
Agenda Item 9.1
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March 2023 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
APPENDICES
Agenda Item 9.1
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March 2023 City of Gilroy
Sewer System Master Plan
City of Gilroy
APPENDIX A
Sewer Flow Monitoring and Inflow/Infiltration Study, 2014
(V&A)
Agenda Item 9.1
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SANITARY SEWER FLOW MONITORING AND
INFLOW / INFILTRATION STUDY
City of Gilroy, CA
May 2014
Agenda Item 9.1
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SANITARY SEWER FLOW MONITORING AND
INFLOW / INFILTRATION STUDY
Prepared for
Akel Engineering Group, Inc.
7433 N. First Street, Suite 103
Fresno, CA 93720
Prepared by
May 2014
Agenda Item 9.1
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TABLE OF CONTENTS
ABBREVIATIONS, TERMS AND DEFINITIONS ................................................................................... iii
EXECUTIVE SUMMARY ........................................................................................................................ 1
Scope and Purpose ............................................................................................................................ 1
Site Flow Monitoring and Capacity Results ........................................................................................ 1
Basin Inflow and Infiltration Analysis Results ..................................................................................... 4
Recommendations .............................................................................................................................. 9
INTRODUCTION .................................................................................................................................. 10
Scope and Purpose .......................................................................................................................... 10
Flow Monitoring Sites ........................................................................................................................ 10
Flow Monitoring Basins ..................................................................................................................... 10
METHODS AND PROCEDURES......................................................................................................... 13
Confined Space Entry ....................................................................................................................... 13
Flow Meter Installation ...................................................................................................................... 14
Flow Calculation ................................................................................................................................ 14
RESULTS AND ANALYSIS .................................................................................................................. 15
Rainfall: Rain Gauge Data ................................................................................................................ 15
Rain Gauge Triangulation Distribution .............................................................................................. 17
Rainfall: Storm Event Classification .................................................................................................. 19
Flow Monitoring: Average Dry Weather Flows ................................................................................. 21
Flow Monitoring: Peak Measured Flows and Pipeline Capacity Analysis ........................................ 23
Inflow / Infiltration Analysis: Definitions and Identification ................................................................ 26
Inflow ............................................................................................................................................. 26
Infiltration ....................................................................................................................................... 26
Infiltration Components ................................................................................................................. 27
Inflow / Infiltration: Analysis Methods ................................................................................................ 29
Inflow / Infiltration: Results ................................................................................................................ 31
Inflow Results Summary ................................................................................................................ 31
Rainfall-Dependent Infiltration Results Summary ......................................................................... 34
Groundwater Infiltration Results Summary ................................................................................... 37
Combined I/I Results Summary .................................................................................................... 40
Inflow / Infiltration: Synthetic Hydrographs ....................................................................................... 43
Design Storm Development .......................................................................................................... 44
Design Storm Response Summary ............................................................................................... 45
RECOMMENDATIONS ........................................................................................................................ 46
TABLES
Table 1. Capacity Analysis Summary ..................................................................................................... 1
Table 2. I/I Analysis Summary ................................................................................................................ 4
Table 3. List of Flow Monitoring Sites................................................................................................... 11
Table 4. Flow Monitoring Basin Information ......................................................................................... 12
Table 5. Rainfall Events Used for I/I Analysis ...................................................................................... 15
Table 6. Rain Gauge Distribution by Basin .......................................................................................... 18
Agenda Item 9.1
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Table 7. Dry Weather Flow Summary .................................................................................................. 22
Table 8. Capacity Analysis Summary ................................................................................................... 23
Table 9. Basin Inflow Analysis Summary ............................................................................................. 31
Table 10. Basin RDI Analysis Summary .............................................................................................. 34
Table 11. Basin Combined I/I Analysis Summary ................................................................................ 40
Table 12. Design Storm I/I Analysis Summary ..................................................................................... 45
FIGURES
Figure 1. Capacity Summary Bar Graphs: Peaking Factors and Peak d/D Ratios ............................... 2
Figure 2. Peak Measured Flow (Flow Schematic) ................................................................................. 3
Figure 3. Inflow Temperature Map (by Rank) ........................................................................................ 5
Figure 4. RDI Temperature Map (by Rank) ........................................................................................... 6
Figure 5. Basins with Groundwater Infiltration ....................................................................................... 7
Figure 6. Combined I/I Temperature Map (by Rank) ............................................................................. 8
Figure 7. Site Location Map ................................................................................................................. 11
Figure 8. Basin Location Map .............................................................................................................. 12
Figure 9. Typical Installation for Flow Meter with Submerged Sensor ................................................ 14
Figure 10. Rainfall Activity over Flow Monitoring Period ..................................................................... 15
Figure 11. Rainfall Accumulation Plot.................................................................................................. 16
Figure 12. Rainfall Inverse Distance Weighting Method ..................................................................... 17
Figure 13. NOAA Northern California Rainfall Frequency Map ........................................................... 19
Figure 14. Storm Event Classification (GILRO7) ................................................................................. 20
Figure 15. Sample ADWF Diurnal Flow Patterns ................................................................................ 21
Figure 16. Average Dry Weather Flow (Flow Schematic) ................................................................... 22
Figure 17. Capacity Summary Bar Graphs: Peaking Factors and Peak d/D Ratios ........................... 24
Figure 18. Peak Measured Flow (Flow Schematic) ............................................................................. 25
Figure 19. Inflow and Infiltration: Graphical Response Patterns ......................................................... 27
Figure 20. Typical Sources of Infiltration and Inflow ............................................................................ 28
Figure 21. Sample Infiltration and Inflow Isolation Graph ................................................................... 30
Figure 22. Bar Graphs: Inflow Analysis Summary ............................................................................... 32
Figure 23. Inflow Temperature Map (by Rank) .................................................................................... 33
Figure 24. Bar Graphs: RDI Analysis Summary .................................................................................. 35
Figure 25. RDI Temperature Map (by Rank) ....................................................................................... 36
Figure 26. Groundwater Infiltration Sample Figure ............................................................................. 37
Figure 27. Minimum Flow Ratios vs. ADWF ........................................................................................ 38
Figure 28. Basins with Groundwater Infiltration ................................................................................... 39
Figure 29. Bar Graphs: Combined I/I Analysis Summary ................................................................... 41
Figure 30. Combined I/I Temperature Map (by Rank) ......................................................................... 42
Figure 31. Site 3, Storm Event 1: Synthetic Hydrograph .................................................................... 43
Figure 32. 10-Year, 24-Hour Design Storm Values and Profile .......................................................... 44
APPENDIX
Appendix A: Flow Monitoring Sites: Data, Graphs, Information
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ABBREVIATIONS, TERMS AND DEFINITIONS USED IN THIS REPORT
Table i. Abbreviations
Abbreviation Term
ADWF average dry weather flow
CCTV closed-circuit television
CIP capital improvement plan
CO carbon monoxide
d/D depth/diameter ratio
FM flow monitor
gpd gallons per day
gpm gallons per minute
GWI groundwater infiltration
H2S hydrogen sulfide
I/I inflow and infiltration
IDM inch-diameter-mile (miles of pipeline multiplied by
the diameter of the pipeline in inches)
IDW inverse distance weighting
LEL lower explosive limit
mgd million gallons per day
NOAA National Oceanic and Atmospheric Administration
PS pump station
Q flow rate
QA/QC quality assurance/quality control
RDI rainfall-dependent infiltration
ROW right of way
RRI rainfall-responsive infiltration
RG rain gauge
SSO sanitary sewer overflow
WEF Water Environment Federation
WRCC Western Regional Climate Center
WWTP wastewater treatment plant
Agenda Item 9.1
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Table ii. Terms and Definitions
Term Definition
Attenuation
Flow attenuation in a sewer collection system is the natural process of the
reduction of the peak flow rate through redistribution of the same volume of flow
over a longer period of time. This occurs as a result of friction (resistance),
internal storage and a tendency to reach a steady state along the sewer pipes.
As the flows from the basins combine within the trunk sewer lines, (a) the peaks
from each basin will not necessary coincide at the same time, and (b) due to the
length and time of travel through the trunk sewers, peak flows will attenuate as
the peak flows move downstream. The sum of the peak flows of individual
basins upstream will generally be greater than the measured peak flows
observed at points downstream.
Average dry
weather flow
(ADWF)
Average flow rate or pattern from days without noticeable inflow or infiltration
response. ADWF usage patterns for weekdays and weekends differ and must
be computed separately. ADWF can be expressed as a numeric average or as
a curve showing the variation in flow over a day. ADWF includes the influence of
normal groundwater infiltration (not related to a rain event).
Basin
Sanitary sewer collection system upstream of a given location (often a flow
meter), including all pipelines, inlets, and appurtenances. Also refers to the
ground surface area near and enclosed by the pipelines. A basin may refer to
the entire collection system upstream from a flow meter or exclude separately
monitored basins upstream.
Depth/diameter
(d/D) ratio
Depth of water in a pipe as a fraction of the pipe’s diameter. A measure of
fullness of the pipe used in capacity analysis.
Design storm
A theoretical storm event of a given duration and intensity that aligns with
historical frequency records of rainfall events. For example, a 10-year, 24-hour
design storm is a storm event wherein the volume of rain that falls in a 24-hour
period would historically occur once every 10 years. Design storm events are
used to predict I/I response and are useful for modeling how a collection system
will react to a given set of storm event scenarios.
Infiltration and
inflow
Infiltration and inflow (I/I) rates are calculated by subtracting the ADWF flow
curve from the instantaneous flow measurements taken during and after a storm
event. Flow in excess of the baseline consists of inflow, rainfall-responsive
infiltration, and rainfall-dependent infiltration. Combined I/I is the total sum in
gallons of additional flow attributable to a storm event.
Infiltration,
groundwater
Groundwater infiltration (GWI) is groundwater that enters the collection system
through pipe defects. GWI depends on the depth of the groundwater table
above the pipelines as well as the percentage of the system submerged. The
variation of groundwater levels and subsequent groundwater infiltration rates is
seasonal by nature. On a day-to-day basis, groundwater infiltration rates are
relatively steady and will not fluctuate greatly.
Infiltration,
rainfall-dependent
Rainfall-dependent infiltration (RDI) is similar to groundwater infiltration but
occurs as a result of storm water. The storm water percolates into the soil,
submerges more of the pipe system, and enters through pipe defects. RDI is the
slowest component of storm-related infiltration and inflow, beginning gradually
and often lasting 24 hours or longer. The response time depends on the soil
permeability and saturation levels.
Infiltration,
rainfall-responsive
Rainfall-responsive infiltration (RRI) is storm water that enters the collection
system through pipe defects, but normally in sewers constructed close to the
ground surface such as private laterals. RRI is independent of the groundwater
table and reaches defective sewers via the pipe trench in which the sewer is
constructed, particularly if the pipe is placed in impermeable soil and bedded and
Agenda Item 9.1
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Term Definition
backfilled with a granular material. In this case, the pipe trench serves as a
conduit similar to a French drain, conveying storm drainage to defective joints
and other openings in the system.
Inflow
Inflow is defined as water discharged into the sewer system, including private
sewer laterals, from direct connections such as downspouts, yard and area
drains, holes in manhole covers, cross-connections from storm drains, or catch
basins. Inflow creates a peak flow problem in the sewer system and often
dictates the required capacity of downstream pipes and transport facilities to
carry these peak instantaneous flows. Overflows are often attributable to high
inflow rates.
Normalization
To run an “apples-to-apples” comparison amongst different basins, calculated
metrics must be normalized. Individual basins will have different runoff areas,
pipe lengths and sanitary flows. There are three common methods of
normalization. Depending on the information available, one or all methods can
be applied to a given project:
Pipe Length: The metric is divided by the length of pipe in the upstream
basin expressed in units of inch-diameter-mile (IDM).
Basin Area: The metric is divided by the estimated drainage area of the
basin in acres.
ADWF: The metric is divided by the average dry weather sanitary flow
(ADWF).
Normalization,
inflow
The peak I/I flow rate is used to quantify inflow. Although the instantaneous flow
monitoring data will typically show an inflow peak, the inflow response is
measured from the I/I flow rate (in excess of baseline flow). This removes the
effect of sanitary flow variations and measures only the I/I response:
Pipe Length: The peak I/I flow rate is divided by the length of pipe (IDM) in
the upstream basin. The result is expressed in gallons per day (gpd) per
IDM (gpd/IDM).
Basin Area: The peak I/I flow rate is divided by the geographic area of the
upstream basin. The result is expressed in gpd per acre.
ADWF: The peak I/I flow rate is divided by the average dry weather flow
(ADWF). This is a ratio and is expressed without units.
Normalization,
GWI
The estimated GWI rates are compared to acceptable GWI rates, as defined by
the Water Environment Federation, and used to identify basins with high GWI:
Pipe Length: The GWI flow rate is divided by the length of pipe (IDM) in the
upstream basin. The result is expressed in gallons per day (gpd) per IDM
(gpd/IDM).
Basin Area: The GWI flow rate is divided by the geographic area of the
upstream basin. The result is expressed in gpd per acre.
ADWF: The GWI flow rate is divided by the average dry weather flow
(ADWF). This is a ratio and is expressed without units.
Normalization,
RDI
The estimated RDI rates at a period 24 hours or more after the conclusion of a
storm event are used to identify basins with high RDI:
Agenda Item 9.1
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Term Definition
Pipe Length: The RDI flow rate is divided by the length of pipe (IDM) in the
upstream basin. The result is expressed in gallons per day (gpd) per IDM
(gpd/IDM).
Basin Area: The RDI flow rate is divided by the geographic area of the
upstream basin. The result is expressed in gpd per acre.
ADWF: The RDI flow rate is divided by the average dry weather flow
(ADWF). This is a ratio and is expressed without units.
Normalization,
total I/I
The estimated totalized I/I in gallons attributable to a particular storm event is
used to identify basins with high total I/I. Because this is a totalized value rather
than a rate and can be attributable solely to an individual storm event, the
volume of the storm event is also taken into consideration. This allows for a
comparison not only between basins but also between storm events:
Pipe Length: Total gallons of I/I is divided by the length of pipe (IDM) in the
upstream basin and the rainfall total (inches) of the storm event. The result
is expressed in gallons per IDM per inch of rain.
Basin Area (R-Value): Total gallons of I/I is divided by total gallons of
rainfall water that fell within the acreage of the basin area. This is a ratio
and expressed as a percentage. R-value is described as “the percentage
of rainfall that enters the collection system.” Systems with R-values less
than 5%1 are often considered to be performing well.
ADWF: Total gallons of I/I is divided by the ADWF and the rainfall total of
the storm event. The result is expressed in million gallons per mgd of
ADWF per inch of rain.
Peaking factor
Ratio of peak measured flow to average dry weather flow. This ratio expresses
the degree of fluctuation in flow rate over the monitoring period and is used in
capacity analysis.
Surcharge
When the flow level is higher than the crown of the pipe, then the pipeline is said
to be in a surcharged condition. The pipeline is surcharged when the d/D ratio
is greater than 1.0.
Synthetic
hydrograph
A set of algorithms developed to approximate the actual I/I hydrograph. The
synthetic hydrograph is developed strictly using rainfall data and response
parameters representing response time, recession coefficient and soil saturation.
Weekend/weekday
ratio
The ratio of weekend ADWFs to weekday ADWFs. In residential areas, this ratio
is typically slightly higher than 1.0. In business districts, depending on type of
service, this ratio can be significantly less than 1.0.
1 Keefe, P.N. “Test Basins for I/I Reduction and SSO Elimination.” 1998 WEF Wet Weather Specialty Conference, Cleveland.
Agenda Item 9.1
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EXECUTIVE SUMMARY
Scope and Purpose
V&A was retained by Akel Engineering Group to perform sanitary sewer flow monitoring, rainfall
monitoring, and inflow and infiltration (I/I) analysis within the City of Gilroy, California (City). Flow and
rainfall monitoring was performed over a three-week period at eleven open-channel flow monitoring
sites within the City. The flow monitoring period began on February 24, 2014, and ended on March
16, 2014. The purpose of this study was to measure sanitary sewer flows at the flow monitoring sites
and estimate available sewer capacity and infiltration and inflow (I/I) occurring in the basins upstream
from the flow monitoring sites.
Site Flow Monitoring and Capacity Results
Peak measured flows and the corresponding flow levels (depths) are important to understand the
capacity limitations of a collection system. Table 1 summarizes the peak recorded flows, levels, d/D
ratios, and peaking factors per site during the flow monitoring period. Capacity analysis data is
presented on a site-by-site basis and represents the hydraulic conditions only at the site locations;
hydraulic conditions in other areas of the collection system will differ.
Table 1. Capacity Analysis Summary
Metering
Site
ADWF
(mgd)
Peak
Measured
Flow
(mgd)
Peaking
Factor
Diameter
(in)
Peak
Level
(in)
Peak
d/D
Ratio
Level
Surcharged
above
Crown (ft)
Site 1 1.04 2.82 2.70 27 12.80 0.47 -
Site 2 1.24 2.21 1.79 25 15.92 0.64 -
Site 3 3.66 6.69 1.83 33 18.22 0.55 -
Site 4 0.13 0.31 2.42 12 2.86 0.24 -
Site 5 0.12 0.41 3.43 10.5 7.10 0.68 -
Site 6 0.07 0.15 2.15 24 3.82 0.16 -
Site 7 0.15 0.26 1.78 10 13.27 1.33 0.3
Site 8 0.29 0.91 3.09 14 6.51 0.47 -
Site 9 3.30 6.49 1.96 33 14.51 0.44 -
Site 10 0.31 0.58 1.88 10.5 6.88 0.66 -
Site 11 0.54 1.11 2.07 17.75 11.39 0.64 -
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The following capacity analysis results are noted:
Peaking Factor: Sites 5 and 8 had peaking factors that exceeded typical design threshold
limits for the ratio of peak flow to average dry weather flow.
d/D Ratio: Site 7 had a d/D ratio that exceeded the common design threshold for d/D ratio. It
should be noted that the peak level that was recorded was not a result of a rainfall event. It
was also observed that several sites had recorded peak levels that were not related to rainfall
events.
Figure 1 shows bar graphs of the capacity results. Figure 2 shows a schematic diagram of the peak
measured flows with peak flow levels.
Figure 1. Capacity Summary Bar Graphs: Peaking Factors and Peak d/D Ratios 2.7 1.8 1.8 2.4 3.4 2.2 1.9 3.1 2.0 2.1 2.2 0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Site FM01Site FM02Site FM03Site FM04Site FM05Site FM06Site FM07Site FM08Site FM09Site FM10Site FM11Peaking Factor 0.5 0.6 0.6 0.2 0.7 0.2 1.3 0.5 0.4 0.7 0.6 0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Site FM01Site FM02Site FM03Site FM04Site FM05Site FM06Site FM07Site FM08Site FM09Site FM10Site FM11d/D Ratio Surcharge
Threshold
Typ. Design
Threshold
Typical
Design
Threshold
Agenda Item 9.1
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Figure 2. Peak Measured Flow (Flow Schematic)
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Basin Inflow and Infiltration Analysis Results
Table 2 summarizes the flow monitoring and I/I results for the 11 flow monitoring basins that were
isolated during this study. Infiltration and inflow rankings are shown such that 1 represents the highest
infiltration or inflow contribution and 11 represents the least. Basins that ranked 1, 2 or 3 in a category
are color coded red. Please refer to the I/I Methods section for more information on inflow and
infiltration analysis methods and ranking methods.
Table 2. I/I Analysis Summary
Metering
Basin
ADWF
(mgd)
Peak I/I
Rate
(mgd)
Combined I/I
(gallons)
Inflow
Ranking
RDI
Ranking
Evidence
of High
GWI?
Combined
I/I
Ranking
Basin 1 1.04 1.98 334,600 2 8 No 6
Basin 2 1.24 0.35 153,000 8 T10 No 7
Basin 3 3.66 0.00 483,500 10 1 No 1
Basin 4 0.13 0.14 71,000 6 3 Yes 4
Basin 5 0.12 0.22 135,200 5 4 Yes 3
Basin 6 0.07 0.10 41,700 7 7 Yes 8
Basin 7 0.15 0.20 19,800 3 T10 No 10
Basin 8 0.29 0.84 166,700 1 2 No 2
Basin 9 3.30 n/a 38,400 n/a 5 No 5
Basin 10 0.31 0.40 40,700 4 9 No 11
Basin 11 0.54 0.39 132,700 9 6 No 9
The following inflow/infiltration analysis results are noted:
Inflow: Basins 1, 7 and 8 ranked highest for normalized inflow contribution.
Rainfall-Dependent Infiltration: Basins 3, 4 and 8 ranked highest for normalized RDI
contribution.
Groundwater Infiltration: Basins 4, 5 and 6 had GWI rates that were above the WEF typical
low-to-average ratio, indicating excessive groundwater infiltration.
Combined I/I: Basins 3, 5 and 8 ranked highest for normalized combined I/I contribution.
Figure 3 through Figure 6 show temperature maps of the overall rankings for each inflow and
infiltration component.
Agenda Item 9.1
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Figure 3. Inflow Temperature Map (by Rank)
Legend
Inflow Ranking
1-2
3-4
5-6
7-8
9-11
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Figure 4. RDI Temperature Map (by Rank)
Legend
RDI/I Ranking
1-2
3-4
5-6
7-8
9-11
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Figure 5. Basins with Groundwater Infiltration
Legend
Groundwater Infiltration
Above typical rates
At or below typical rates
Agenda Item 9.1
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Figure 6. Combined I/I Temperature Map (by Rank)
Legend
Combined I/I Ranking
1-2
3-4
5-6
7-8
9-11
Agenda Item 9.1
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Recommendations
V&A advises that future I/I reduction plans consider the following recommendations:
1. Determine I/I Reduction Program: The City should examine its I/I reduction needs to
determine a future I/I reduction program.
a. If peak flows, sanitary sewer overflows, and pipeline capacity issues are of greater
concern, then priority can be given to investigate and reduce sources of inflow within the
basins with the greatest inflow problems. The highest inflow occurred in Basins 1, 7 and
8.
b. If total infiltration and general pipeline deterioration are of greater concern, then the
program can be weighted to investigate and reduce sources of infiltration within the
basins with the greatest infiltration problems.
i. The highest normalized rainfall-dependent infiltration occurred in Basins 3, 4 and 8.
ii. The highest groundwater infiltration occurred in Basins 4, 5 and 6.
2. I/I Investigation Methods: Potential I/I investigation methods include the following:
a. Smoke testing.
b. Mini-basin flow monitoring.
c. Nighttime reconnaissance work to (1) investigate and determine direct point sources of
inflow and (2) determine the areas and pipe reaches responsible for high levels of
infiltration contribution.
3. I/I Reduction Cost-Effectiveness Analysis: The City should conduct a study to determine
which is more cost-effective: (1) locating the sources of inflow and infiltration and
systematically rehabilitating or replacing the faulty pipelines or (2) continued treatment of the
additional rainfall-dependent I/I flow.
Agenda Item 9.1
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INTRODUCTION
Scope and Purpose
V&A was retained by Akel Engineering Group to perform sanitary sewer flow monitoring, rainfall
monitoring, and inflow and infiltration (I/I) analysis within the City of Gilroy, California (City). Flow and
rainfall monitoring was performed over a three-week period at eleven open-channel flow monitoring
sites within the City. The flow monitoring period began on February 24, 2014, and ended on March
16, 2014. The purpose of this study was to measure sanitary sewer flows at the flow monitoring sites
and estimate available sewer capacity and infiltration and inflow (I/I) occurring in the basins upstream
from the flow monitoring sites, as shown in Figure 8.
Flow Monitoring Sites
Flow monitoring sites are the manholes where the flow monitors were placed. Flow monitoring site
data may include the flows of one or many drainage basins. To isolate a flow monitoring basin, an
addition or subtraction of flows may be required 2. One issue of note is that the flow for the City of
Morgan Hill flows south into Gilroy and enters the system through Basin 9. The flow data for this
portion of the study was obtained from a flow meter on Harding Way that captures all of Morgan Hill’s
flow, is owned by the City of Morgan Hill and is maintained by V&A. Capacity and flow rate
information is presented on a site-by-site basis. The locations and other information for the flow
monitoring sites are shown in Table 3.
Flow Monitoring Basins
Flow monitoring basins are localized areas of a sanitary sewer collection system upstream of a given
location (often a flow meter), including all pipelines, inlets, and appurtenances (Figure 8). The basin
refers to the ground surface area near and enclosed by the pipelines 3. A basin may refer to the entire
collection system upstream from a flow meter or may exclude separately monitored basins upstream.
I/I analysis in this report will be conducted on a basin-by-basin basis. For this study subtraction of
flows was required to isolate the drainage areas of some flow monitoring basins. Shown in Table 4
are the equations (in which Q refers to flow rate) used to calculate the flow rate results for each basin
from the flow rates recorded at the monitoring sites. Detailed descriptions of the individual flow
monitoring sites, including photographs, are included in Appendix A.
2 There is error inherent in flow monitoring. Adding and subtracting flows increases error on an additive basis. For example, if
Site A has an error of ±10% and Site B has an error of ±10%, then the resulting flow when subtracting Site A from Site B would
have an error of up to ±20%. 3 The basin areas (in acres) were provided by Akel Engineering Group.
Agenda Item 9.1
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Table 3. List of Flow Monitoring Sites
Metering
Site
Pipe
Dia.
(in)
City GIS
Manhole
Number
Location
Site 1 27 S113DM201 Inside WWTP property 100 ft. west of Influent Pump Station
Site 2 25 S102CM201 ROW southeast of Holloway Rd.
Site 3 33 S091CM501 ROW southeast of Holloway Rd.
Site 4 12 S100DM201 W. Luchessa Ave. near Hyde Park Dr.
Site 5 18 S076CM402 Wren Ave. and Uvas Park Dr.
Site 6 24 S064DM205 100 ft. south of west end of 3rd St. on bike path
Site 7 10 S079AM401 East end of E. 9th St. near Hwy. 101 offramp
Site 8 14 S079AM103 Near northwest end of Renz Ln.
Site 9 33 S048AM401 Behind Nike Outlet Store off Arroyo Circle
Site 10 10.5 S047CM207 Welburn Ave. west of Church St.
Site 11 17.75 S037CM307 Intersection of Wren Ave. and Mantelli Dr.
Figure 7. Site Location Map
Agenda Item 9.1
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Table 4. Flow Monitoring Basin Information
Flow Metering
Basin
Metering
Basin Size (acres)
Basin Flow
Calculation
Basin 1 1,661 Q1(Basin) = Q1(Site) – Q4(Site) – Q5(Site) – Q6(Site)
Basin 2 766 Q2(Basin) = Q2(Site) – Q7(Site) – Q8(Site) – Q10(Site)
Basin 3 818 Q3(Basin) = Q3(Site) – Q9(Site)
Basin 4 343 Q4(Basin) = Q4(Site)
Basin 5 888 Q5(Basin) = Q5(Site)
Basin 6 732 Q6(Basin) = Q6(Site)
Basin 7 137 Q7(Basin) = Q7(Site)
Basin 8 566 Q8(Basin) = Q8(Site)
Basin 9 181 Q9(Basin) = Q9(Site) – Q11(Site) – QMorgan Hill
Basin 10 456 Q10(Basin) = Q10(Site)
Basin 11 1,014 Q11(Basin) = Q11(Site)
Figure 8. Basin Location Map
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METHODS AND PROCEDURES
Confined Space Entry
A confined space (Photo 1) is defined as any space that is large enough and so configured that a
person can bodily enter and perform assigned work, has limited or restricted means for entry or exit
and is not designed for continuous employee occupancy. In general, the atmosphere must be
constantly monitored for sufficient levels of oxygen (19.5% to 23.0%) and the absence of hydrogen
sulfide (H2S) gas, carbon monoxide (CO) gas, and lower explosive limit (LEL) levels. A typical
confined space entry crew has members with OSHA-defined responsibilities of Entrant, Attendant and
Supervisor. The Entrant is the individual performing the work. He or she is equipped with the
necessary personal protective equipment needed to perform the job safely, including a personal four-
gas monitor (Photo 2). If it is not possible to maintain line-of-sight with the Entrant, then more
Entrants are required until line-of-sight can be maintained. The Attendant is responsible for
maintaining contact with the Entrants to monitor the atmosphere on another four-gas monitor and
maintaining records of all Entrants, if there are more than one. The Supervisor develops the safe
work plan for the job at hand prior to entering.
Photo 1. Confined Space Entry Photo 2. Typical Personal Four-Gas
Monitor
Agenda Item 9.1
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Flow Meter Installation
V&A installed eleven Isco 2150 area-velocity flow meters at the metering locations referenced in
Table 3. Isco 2150 meters use submerged sensors with a pressure transducer to collect depth
readings and an ultrasonic Doppler sensor to determine the average fluid velocity. The ultrasonic
sensor emits high-frequency (500 kHz) sound waves, which are reflected by air bubbles and
suspended particles in the flow. The sensor receives the reflected signal and determines the Doppler
frequency shift, which indicates the estimated average flow velocity. The sensor is typically mounted
at a manhole inlet to take advantage of smoother upstream flow conditions. The sensor may be offset
to one side to lessen the chances of fouling and sedimentation where these problems are expected to
occur. Manual level and velocity measurements were taken during installation of the flow meters and
again when they were removed and compared to simultaneous level and velocity readings from the
flow meters to ensure proper calibration and accuracy. Figure 9 shows a typical installation for a flow
meter with a submerged sensor.
Figure 9. Typical Installation for Flow Meter with Submerged Sensor
Flow Calculation
Data retrieved from the flow meter was placed into a spreadsheet program for analysis. Data analysis
includes data comparison to field calibration measurements, as well as necessary geometric
adjustments as required for sediment (sediment reduces the pipe’s wetted cross-sectional area
available to carry flow). Area-velocity flow metering uses the continuity equation,
AVQ⋅=
where Q is the volume flow rate, V is the average velocity as determined by the ultrasonic sensor,
and A is the cross-sectional area of flow as determined from the depth of flow. For circular pipe,
−
−−
−=−−
D
dDdD
D
dDA 21cossin22
21cos4
11
2
,
where D is the pipe diameter
and d is the depth of flow.
Agenda Item 9.1
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RESULTS AND ANALYSIS
Rainfall: Rain Gauge Data
V&A utilized rain data from three rain gauges maintained by local weather enthusiasts. While V&A
performed QA/QC analysis to ensure, to the extent possible, the quality of the rainfall data, it is noted
that V&A has no direct control over these gauges.
There was one primary rainfall event spread over several days that was used for infiltration and inflow
analysis for this study, as summarized in Table 5. Figure 10 graphically displays the rainfall activity
recorded over the flow monitoring period (average of rain gauges). Figure 11 shows the rain
accumulation plot of the period rainfall, as well as the historical average rainfall 4 in Gilroy during this
project duration. Rainfall totals for Gilroy were 121%, 113% and 110% per gauge of historical normal
levels during this time period.
Table 5. Rainfall Events Used for I/I Analysis
Rainfall Event
GILRO2
Event Rainfall
(in)
GILRO7
Event Rainfall
(in)
GILRO17
Event Rainfall
(in)
Event 1: February 26, 2014 –
March 2, 2014 3.39 3.27 3.59
Total over Monitoring Period 3.58 3.48 3.82
Figure 10. Rainfall Activity over Flow Monitoring Period
4 Historical data taken from the WRCC (Station 043417 in Gilroy): http://www.wrcc.dri.edu/summary/climsmnca.html
Agenda Item 9.1
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Figure 11. Rainfall Accumulation Plot
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Rain Gauge Triangulation Distribution
The rainfall affecting the sanitary sewer collection system basins must be calculated based on the
proximity to the rain gauge locations. The mean precipitation for each site was calculated by taking
data from the rain gauges and using the inverse distance weighting (IDW) method. IDW is an
interpolation method that assumes the influence of each rain gauge location diminishes with distance.
The approximate geographic coordinates of each site were determined and a weighted average was
taken of the precipitation data from nearby rain gauge locations.
IDW is performed using the equation
where the weight, w, depends on the distance, d, from the rain gauge to the monitoring site and p, a
user-selected power (p > 0). The most common choice of p in hydrological studies of watershed
areas is 2. Figure 12 illustrates the IDW method with sample data.
Figure 12. Rainfall Inverse Distance Weighting Method
∑=
p
p
d
dw1
1
Agenda Item 9.1
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The rain gauge distribution as calculated for each metering site for this project is shown in Table 6.
Table 6. Rain Gauge Distribution by Basin
Metering
Basin
GILRO2
(%)
GILRO7
(%)
GILRO17
(%)
Basin 1 10.7% 18.8% 70.4%
Basin 2 35.5% 37.3% 27.2%
Basin 3 45.4% 26.1% 28.5%
Basin 4 9.6% 15.4% 75.0%
Basin 5 2.4% 15.1% 82.5%
Basin 6 5.5% 59.4% 35.1%
Basin 7 23.8% 29.6% 46.6%
Basin 8 20.2% 43.2% 36.6%
Basin 9 13.5% 72.2% 14.3%
Basin 10 4.7% 79.3% 15.9%
Basin 11 0.6% 98.0% 1.4%
Agenda Item 9.1
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Rainfall: Storm Event Classification
It is important to classify the relative size of the major storm event that occurs over the course of a
flow monitoring period 5. Storm events are classified by intensity and duration. Based on historical
data, frequency contour maps for storm events of given intensity and duration have been developed
by the National Oceanic and Atmospheric Administration (NOAA) for all areas within the continental
United States. For example, the NOAA Rainfall Frequency Atlas 6 classifies a 10-year, 24-hour storm
event in Gilroy (at the location of the GILRO7 rain gauge) as 4.42 inches (Figure 13). This means that
in any given year, there is a 10% chance that 4.42 inches of rain will fall in any 24-hour period.
Figure 13. NOAA Northern California Rainfall Frequency Map
From the NOAA frequency maps, for a specific latitude and longitude, the rainfall densities for period
durations ranging from 15 minutes to 60 days are known for rain events ranging from 1-year to 100-year
5 Sanitary sewers are often designed to withstand I/I contribution to sanitary flows for “design” storm events of specific sizes.
6 NOAA Western U.S. Precipitation Frequency Maps Atlas 2, 1973: http://www.wrcc.dri.edu/pcpnfreq.html
Agenda Item 9.1
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intensities. These are plotted to develop a rain event frequency map specific to each rainfall monitoring
site. Superimposing the peak measured densities for Event 1 on the rain event frequency plot
determines the classification of the storm event, as shown in Figure 14. The rain event that occurred
during the flow-monitoring period was classified as a 1-year, 24-hour rainfall event at the GILRO2 and
GILRO7 rain gauges. The event actually approached 5-year, 6-hour status at the GILRO2 gauge.
Figure 14. Storm Event Classification (GILRO7)
Agenda Item 9.1
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Flow Monitoring: Average Dry Weather Flows
Weekday and weekend diurnal flow patterns differ and can be separated when establishing average
dry weather flow rates. Within weekdays, the average dry weather flow (ADWF) patterns for Friday
will vary from the Monday through Thursday patterns, particularly in the evening hours as people
prepare for the weekend. Similarly, Sunday flow patterns typically vary in the evenings from Saturday
flow patterns as people prepare for the work week. Figure 15 illustrates the varying flow patterns
within a work week (Site 2 shown).
Figure 15. Sample ADWF Diurnal Flow Patterns
Graphs of the ADWF flow patterns for each site may be found in Appendix A. The overall average
dry weather flow (ADWF) is calculated per the following equation:
×+
×+
×+
×=−7
1
7
1
7
1
7
4
SunSatFriThuMonADWFADWFADWFADWFADWF ,
Table 7 lists the average dry weather flow (ADWF) recorded during this study for the flow monitoring
sites. Figure 16 shows a schematic diagram of the average dry weather flows and flow levels.
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 00Flow (mgd) Hour
Mon - Thurs (mgd)Friday (mgd)Saturday (mgd)Sunday (mgd)
Agenda Item 9.1
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Table 7. Dry Weather Flow Summary
Monitoring
Site
Mon-Thu
ADWF
(mgd)
Friday
ADWF
(mgd)
Saturday
ADWF
(mgd)
Sunday
ADWF
(mgd)
Overall
ADWF
(mgd)
Site 1 1.04 1.01 1.03 1.07 1.04
Site 2 1.23 1.23 1.27 1.24 1.24
Site 3 3.69 3.58 3.60 3.68 3.66
Site 4 0.13 0.12 0.12 0.13 0.13
Site 5 0.12 0.12 0.12 0.13 0.12
Site 6 0.07 0.06 0.07 0.07 0.07
Site 7 0.15 0.14 0.16 0.13 0.15
Site 8 0.28 0.27 0.29 0.36 0.29
Site 9 3.15 3.11 3.24 3.30 3.18
Site 10 0.31 0.30 0.31 0.31 0.31
Site 11 0.52 0.52 0.55 0.58 0.54
Figure 16. Average Dry Weather Flow (Flow Schematic)
Agenda Item 9.1
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Flow Monitoring: Peak Measured Flows and Pipeline Capacity Analysis
Peak measured flows and the corresponding flow levels (depths) are important to understand the
capacity limitations of a collection system. The peak flows and flow levels reported are from the peak
measurements as taken across the entirety of the flow monitoring period. Peak flows and levels may
not correspond to a rainfall event, but instead may be caused due to blockages, grease or roots that
cause a backflow condition.
Two key capacity analysis terms are defined as follows:
Peaking Factor: Peaking factor is defined as the peak measured flow divided by the average
dry weather flow (ADWF). A peaking factor threshold value of 3.0 is commonly used for
sanitary sewer design.
d/D Ratio: The d/D ratio is the peak measured depth of flow (d) divided by the pipe diameter
(D). A d/D ratio of 0.75 is a common maximum threshold value used for pipe design. The
d/D ratio for each site was computed based on the maximum depth of flow from the flow
monitoring study.
Table 8 summarizes the peak recorded flows, levels, d/D ratios, and peaking factors per site during
the flow monitoring period. Capacity analysis data is presented on a site-by-site basis and represents
the hydraulic conditions only at the site locations; hydraulic conditions in other areas of the collection
system will differ.
Table 8. Capacity Analysis Summary
Metering
Site
ADWF
(mgd)
Peak
Measured
Flow
(mgd)
Peaking
Factor
Diameter
(in)
Peak
Level
(in)
Peak
d/D
Ratio
Level
Surcharged
above
Crown (ft)
Site 1 1.04 2.82 2.70 27 12.80 0.47 -
Site 2 1.24 2.21 1.79 25 15.92 0.64 -
Site 3 3.66 6.69 1.83 33 18.22 0.55 -
Site 4 0.13 0.31 2.42 12 2.86 0.24 -
Site 5 0.12 0.41 3.43 10.5 7.10 0.68 -
Site 6 0.07 0.15 2.15 24 3.82 0.16 -
Site 7 0.15 0.26 1.78 10 13.27 1.33 0.3
Site 8 0.29 0.91 3.09 14 6.51 0.47 -
Site 9 3.30 6.49 1.96 33 14.51 0.44 -
Site 10 0.31 0.58 1.88 10.5 6.88 0.66 -
Site 11 0.54 1.11 2.07 17.75 11.39 0.64 -
Agenda Item 9.1
Page 216 of 768
The following capacity analysis results are noted:
Peaking Factor: Sites 5 and 8 had peaking factors that exceeded typical design threshold
limits for the ratio of peak flow to average dry weather flow.
d/D Ratio: Site 7 had a d/D ratio that exceeded the common design threshold for d/D ratio. It
should be noted that the peak level that was recorded was not a result of a rainfall event. It
was also observed that several sites had recorded peak levels that were not related to rainfall
events.
Figure 17 shows bar graphs of the capacity results. Figure 18 shows a schematic diagram of the peak
measured flows with peak flow levels.
Figure 17. Capacity Summary Bar Graphs: Peaking Factors and Peak d/D Ratios
2.7
1.8 1.8
2.4
3.4
2.2
1.8
3.1
2.0 1.9 2.1
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Site FM01Site FM02Site FM03Site FM04Site FM05Site FM06Site FM07Site FM08Site FM09Site FM10Site FM11Peaking Factor 0.47
0.64
0.55
0.24
0.68
0.16
1.33
0.47 0.44
0.66 0.64
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Site FM01Site FM02Site FM03Site FM04Site FM05Site FM06Site FM07Site FM08Site FM09Site FM10Site FM11d/D Ratio Surcharge
Threshold
Typ. Design
Threshold
Typical
Design
Threshold
Agenda Item 9.1
Page 217 of 768
Figure 18. Peak Measured Flow (Flow Schematic)
Agenda Item 9.1
Page 218 of 768
Inflow / Infiltration Analysis: Definitions and Identification
Inflow and infiltration (I/I) consists of storm water and groundwater that enter the sewer system
through pipe defects and improper storm drainage connections and is defined as follows:
Inflow
Definition: Storm water inflow is defined as water discharged into the sewer system,
including private sewer laterals, from direct connections such as downspouts, yard and area
drains, holes in manhole covers, cross-connections from storm drains, or catch basins.
Impact: This component of I/I creates a peak flow problem in the sewer system and often
dictates the required capacity of downstream pipes and transport facilities to carry these peak
instantaneous flows. Because the response and magnitude of inflow is tied closely to the
intensity of the storm event, the short-term peak instantaneous flows may result in
surcharging and overflows within a collection system. Severe inflow may result in sewage
dilution, resulting in upsetting the biological treatment (secondary treatment) at the treatment
facility.
Cost of Source Identification and Removal: Inflow locations are usually less difficult to find
and less expensive to correct. These sources include direct and indirect cross-connections
with storm drainage systems, roof downspouts, and various types of surface drains.
Generally, the costs to identify and remove sources of inflow are low compared to potential
benefits to public health and safety or the costs of building new facilities to convey and treat
the resulting peak flows.
Graphical Identification: Inflow is usually recognized graphically by large-magnitude, short-
duration spikes in flow immediately following a rain event.
Infiltration
Definition: Infiltration is defined as water entering the sanitary sewer system through defects
in pipes, pipe joints, and manhole walls, which may include cracks, offset joints, root intrusion
points, and broken pipes.
Impact: Infiltration typically creates long-term annual volumetric problems. The major impact
is the cost of pumping and treating the additional volume of water, and of paying for treatment
(for municipalities that are billed strictly on flow volume).
Cost of Source Detection and Removal: Infiltration sources are usually harder to find and
more expensive to correct than inflow sources. Infiltration sources include defects in
deteriorated sewer pipes or manholes that may be widespread throughout a sanitary sewer
system.
Graphical Identification: Infiltration is often recognized graphically by a gradual increase in
flow after a wet-weather event. The increased flow typically sustains for a period after rainfall
has stopped and then gradually drops off as soils become less saturated and as groundwater
levels recede to normal levels.
Figure 19 shows sample graphs indicating the typical graphical response patterns for inflow and
infiltration.
Agenda Item 9.1
Page 219 of 768
Figure 19. Inflow and Infiltration: Graphical Response Patterns
Infiltration Components
Infiltration can be further subdivided into components as follows:
Groundwater Infiltration: Groundwater infiltration depends on the depth of the groundwater
table above the pipelines as well as the percentage of the system submerged. The variation
of groundwater levels and subsequent groundwater infiltration rates is seasonal by nature.
On a day-to-day basis, groundwater infiltration rates are relatively steady and will not
fluctuate greatly.
Rainfall-Dependent Infiltration: This component occurs as a result of storm water and
enters the sewer system through pipe defects, as with groundwater infiltration. The storm
water first percolates directly into the soil and then migrates to an infiltration point. Typically,
the time of concentration for rainfall-related infiltration may be 24 hours or longer, but this
depends on the soil permeability and saturation levels.
Rainfall-Responsive Infiltration is storm water which enters the collection system indirectly
through pipe defects, but normally in sewers constructed close to the ground surface such as
private laterals. Rainfall-responsive infiltration is independent of the groundwater table and
reaches defective sewers via the pipe trench in which the sewer is constructed, particularly if
the pipe is placed in impermeable soil and bedded and backfilled with a granular material. In
this case, the pipe trench serves as a conduit similar to a French drain, conveying storm
drainage to defective joints and other openings in the system. This type of infiltration can
have a quick response and graphically can look very similar to inflow.
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Flow (MGD)0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0 Rain (in/hr)0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
4-Jun 5-JunI/I (MGD)0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0 Rain (in/hr)0
5
10
15
20
25
30
Flow (gpm)0.0
0.1
0.2
0.3
0.4
0.5
0.6 Rain (in/hr)0
2
4
6
8
10
12
14
16
18
22-Feb 23-FebFlow (gpm)0.0
0.1
0.2
0.3
0.4
0.5
0.6 Rain (in/hr)0.00
0.10
0.20
0.30
0.40
0.50
Flow (MGD)0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0 Rain (in/hr)0.00
0.05
0.10
0.15
0.20
0.25
17-Dec 18-Dec 19-Dec 20-DecFlow (MGD)0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0 Rain (in/hr)Inflow Combination I/I Infiltration
Rainfall
ADWF Flow
Realtime Flow
I/I Flow Rate
Response Pattern
Sharp Spike
Short Duration
Response Pattern
Gradual Increase
Gradual Recession
Response Pattern
Combination of Inflow
and Infiltration
Agenda Item 9.1
Page 220 of 768
Figure 20 illustrates the possible sources and components of I/I.
Figure 20. Typical Sources of Infiltration and Inflow
..
.
Downspout
connected
to Lateral
Manhole Cover
with Holes
Cross-connection
from
Storm Catch Basin
Area Drain
connected
to Lateral
Deteriorated
Manhole
Cracked or
Damaged Pipe
Faulty Lateral Connection
to Sanitary Sewer
Exfiltration
from
Storm Sewer
Deteriorated
Lateral
Roof Vent
Tree Root
Penetration
Agenda Item 9.1
Page 221 of 768
Inflow / Infiltration: Analysis Methods
After differentiating I/I flows from ADWF flows, various calculations can be made to determine which
I/I component (inflow or infiltration) is more prevalent at a particular site and to compare the relative
magnitudes of the I/I components between drainage basins and between storm events, as follows:
Inflow Indicators
Peak I/I Flow Rate: Inflow is characterized by sharp, direct spikes occurring during a rainfall event.
Peak I/I rates are used for inflow analysis 7. After determining the peak I/I flow rate for a given site,
and for a given storm event, there are three ways to normalize the peak I/I rates for an “apples-to-
apples” comparison amongst the different drainage basins:
Peak I/I Flow Rate per IDM: Peak measured I/I rate divided by length of pipe within the
drainage basin, expressed in units of inch-diameter-mile (IDM, miles of pipeline multiplied by
the diameter of the pipeline in inches). Final units are gallons per day (gpd) per IDM.
Peak I/I Flow Rate per Acre: Peak measured I/I rate divided by the geographic area of the
upstream basin in acres. Units are gpd per acre.
Peak I/I Flow Rate to ADWF Ratio: Peak measured I/I rate divided by average dry weather
flow (ADWF). This is a ratio and is expressed without units.
Infiltration Indicators
Dry Weather Groundwater Infiltration: GWI analysis is conducted by looking at minimum dry
weather flow to average dry weather flow ratios and comparing them to established standards to
quantify the rate of excess groundwater infiltration. As with inflow, GWI infiltration rates can be
normalized by means of pipe length (IDM), basin area (acres), and dry weather flow rates (ADWF).
These methods are discussed in further detail in the Groundwater Analysis section later in this report.
Rainfall-Dependent Infiltration: Infiltration occurring after the conclusion of a storm event is
classified as rainfall-dependent infiltration. Analysis is conducted by looking at the infiltration rates at
set periods after the conclusion of a storm event. Depending on the particular collection system and
the time required for flows to return to ADWF levels, different set periods may be examined to
determine the basins with the greatest or most sustained rainfall-dependent infiltration rates.
Combined I/I Indicators
Total Infiltration: The total inflow and infiltration is measured in gallons per site and per storm event.
Because it is based on total I/I volume, it is an indicator of combined inflow and infiltration and is used
to identify the overall volumetric influence of I/I within the monitoring basin. As with inflow, pipe length,
basin area, and dry weather flow are used to normalize combined I/I for basin comparison:
Combined I/I Flow Rate per IDM: Total infiltration (gallons) divided by length of pipe (IDM)
and divided by storm event rainfall (inches of rain). Final units are gallons per day (gpd) per
IDM per inch of rain.
7 I/I flow rate is the realtime flow less the estimated average dry weather flow rate. It is an estimate of flows attributable to
rainfall. By using peak measured flow rates (inclusive of ADWF), the I/I flow rate would be skewed higher or lower depending
on whether the storm event I/I response occurs during low-flow or high-flow hours.
Agenda Item 9.1
Page 222 of 768
R-Value: Total infiltration (gallons) divided by the total rainfall that fell within the acreage of
that basin (gallons of rainfall). This is expressed as a percentage and is explained as “the
percentage of rain that enters the sanitary sewer collection system.” Systems with R-values
less than 5%8 are often considered to be performing well.
Combined I/I Flow Rate per ADWF: Total infiltration (gallons) divided by the ADWF (gpd)
and divided by storm event rainfall (inches of rain). Final units are million gallons per mgd of
ADWF per inch of rain.
Instantaneous flows were plotted against ADWF flows to analyze the I/I response to rainfall events.
Figure 21 illustrates a sample of how this analysis is conducted and some of the measurements that
are used to distinguish infiltration and inflow. Similar graphs were generated for the individual flow
monitoring sites and can be found in Appendix A.
Figure 21. Sample Infiltration and Inflow Isolation Graph
The infiltration and inflow indicators were normalized by basin area and by ADWF in this report. Final
rankings were determined by weighting the normalization methods by 51% for ADWF, and 49% for
basin area, with ties broken by ADWF. The per-ADWF method is given the tie-break because it is
normalized by actual sanitary waste usage. The per-acre method was given the lower weighting
because the catchment area per each flow monitoring basin is estimated but requires a thorough
hydrologic study to determine the true watershed.
8 Keefe, P.N. “Test Basins for I/I Reduction and SSO Elimination.” 1998 WEF Wet Weather Specialty Conference, Cleveland.
Total I/I – all I/I attributable to rainfall (shaded orange) RDI: sustained response 24 or more
hours after rainfall ends
Inflow: Sharp spike response to rainfall
Peak I/I: inflow indicator and used to
compare and rank basins
Agenda Item 9.1
Page 223 of 768
Inflow / Infiltration: Results
Inflow Results Summary
Table 9 summarizes the peak measured I/I flows and inflow analysis results for Storm Event 1, which
elicited the highest peak I/I response (refer to the I/I Methods section for more information on inflow
analysis methods and ranking procedures). Basins that ranked 1, 2 or 3 in a category are color
coded red.
Table 9. Basin Inflow Analysis Summary
Metering
Basin
ADWF
(mgd)
Peak I/I
Rate
(mgd)
Peak I/I per
Acre
(gpd/acre)
Peak I/I per
ADWF
Overall
Inflow
RankingA
Basin 1 0.72 1.98 1,195 (3)B 2.74 (2) 2
Basin 2 0.49 0.35 453 (5) 0.71 (9) 8
Basin 3 0.36 0.00 0 (10) 0.00 (10) 10
Basin 4 0.13 0.14 410 (6) 1.11 (7) 6
Basin 5 0.12 0.22 248 (8) 1.84 (3) 5
Basin 6 0.07 0.10 130 (9) 1.34 (5) 7
Basin 7 0.15 0.20 1,488 (1) 1.38 (4) 3
Basin 8 0.29 0.84 1,483 (2) 2.85 (1) 1
Basin 9 9 0.12 n/a n/a n/a n/a
Basin 10 0.31 0.40 870 (4) 1.28 (6) 4
Basin 11 0.54 0.39 386 (7) 0.73 (8) 9
A Ranking of 1 represents most inflow after normalization.
B The number in parenthesis shows the ranking within the individual Category.
The following inflow analysis results are noted:
Basins 1, 7 and 8 ranked highest for normalized inflow contribution.
Figure 22 shows bar graph summaries of the inflow analysis. Figure 23 shows a temperature map
summary of the inflow analysis results per basin.
9 Basin 9 was excluded from this analysis. The size of Basin 9 is very small compared to the size of the other basins that are
measured through Site 9, most notably the entirety of the City of Morgan Hill collection system. Due to attenuation and dilution
occurring, a true peak I/I rate specific for Basin 9 cannot be calculated with any degree of confidence.
Agenda Item 9.1
Page 224 of 768
Figure 22. Bar Graphs: Inflow Analysis Summary
0
200
400
600
800
1,000
1,200
1,400
1,600
Basin 1Basin 2Basin 3Basin 4Basin 5Basin 6Basin 7Basin 8Basin 9Basin 10Basin 11Pk I/I per ACRE 0.0
0.5
1.0
1.5
2.0
2.5
3.0
Basin 1Basin 2Basin 3Basin 4Basin 5Basin 6Basin 7Basin 8Basin 9Basin 10Basin 11Pk I/I per ADWF Agenda Item 9.1
Page 225 of 768
Figure 23. Inflow Temperature Map (by Rank)
Legend
Inflow Ranking
1-2
3-4
5-6
7-8
9-11
Agenda Item 9.1
Page 226 of 768
Rainfall-Dependent Infiltration Results Summary
Table 10 summarizes the calculated average RDI flow rate during the low-flow hours immediately
following the rainfall event (refer to the I/I Methods section for more information on RDI analysis
methods and ranking methods). Basins that ranked 1, 2 or 3 in a category are color coded red.
Table 10. Basin RDI Analysis Summary
Metering
Basin
ADWF
(mgd)
RDI Rate
(mgd)
RDI per Acre
(GPAD)
RDI per
ADWF
RDI
RankingA
Basin 1 0.72 0.048 29 (8)B 7% (8) 8
Basin 2 0.49 0.000 0 (T10) 0% (T10) T10
Basin 3 0.36 0.181 222 (1) 51% (1) 1
Basin 4 0.13 0.028 82 (3) 22% (4) 3
Basin 5 0.12 0.045 50 (6) 37% (2) 4
Basin 6 0.07 0.011 15 (9) 16% (5) 7
Basin 7 0.15 0.000 0 (T10) 0% (T10) T10
Basin 8 0.29 0.096 169 (2) 33% (3) 2
Basin 9 0.12 0.014 79 (4) 12% (6) 5
Basin 10 0.31 0.019 42 (7) 6% (9) 9
Basin 11 0.54 0.064 63 (5) 12% (7) 6
A Ranking of 1 represents most RDI after normalization.
B The number in parenthesis shows the ranking within the individual Category.
The following RDI analysis results are noted:
Basins 3, 4 and 8 ranked highest for normalized RDI contribution.
Figure 24 shows bar graph summaries of the RDI analysis. A temperature map by overall ranking is
shown in Figure 25.
Agenda Item 9.1
Page 227 of 768
Figure 24. Bar Graphs: RDI Analysis Summary
0
50
100
150
200
250
Basin 1Basin 2Basin 3Basin 4Basin 5Basin 6Basin 7Basin 8Basin 9Basin 10Basin 11RDI Rate per ACRE (gal/day-acre) 0%
10%
20%
30%
40%
50%
60%Basin 1Basin 2Basin 3Basin 4Basin 5Basin 6Basin 7Basin 8Basin 9Basin 10Basin 11RDI Rate per ADWF (%) Agenda Item 9.1
Page 228 of 768
Figure 25. RDI Temperature Map (by Rank)
Legend
RDI/I Ranking
1-2
3-4
5-6
7-8
9-11
Agenda Item 9.1
Page 229 of 768
Groundwater Infiltration Results Summary
Dry weather (ADWF) flow can be expected to have a predictable diurnal flow pattern. While each site
is unique, experience has shown that, given a reasonable volume of flow and typical loading
conditions, the daily flows fall into a predictable range when compared to the daily average flow. If a
site has a large percentage of groundwater infiltration occurring during the periods of dry weather flow
measurement, the amplitudes of the peak and low flows will be dampened 10. Figure 26 shows a
sample of two flow monitoring sites, both with nearly the same average daily flow, but with
considerably different peak and low flows. In this sample case, Site B1 may have a considerable
volume of groundwater infiltration.
Figure 26. Groundwater Infiltration Sample Figure
It can be useful to compare the low-to-ADWF flow ratios for the flow metering sites. A site with
abnormal ratios, and with no other reasons to suspect abnormal flow patterns (such as proximity to a
pump station, treatment facilities, etc.), has a possibility of higher levels of groundwater infiltration in
comparison to the rest of the collection system. Figure 27 plots the low-to-ADWF flow ratios against
the ADWF flows for the sites monitored during this study. The dotted line shows “typical” low-to-
ADWF ratios per the Water Environment Federation (WEF)11. The following GWI results are noted:
Basins 4, 5 and 6 had GWI rates that were above the WEF typical low-to-average ratio,
indicating excessive groundwater infiltration.
Figure 28 shows a color-coded map of the basins with rates of groundwater infiltration considerably
above typical groundwater infiltration standards (as set forth by WEF).
10 In an extreme case, perhaps 0.2 mgd of ADWF flow and 2.0 mgd of groundwater infiltration, the peaks and lows would be
barely recognizable; the ADWF flow would be nearly a straight line.
11 WEF Manual of Practice No. 9, “Design and Construction of Sanitary and Storm Sewers.”
West County Wastewater District: B1 and A9 Baseline Weekday Flows
0.0
0.1
0.2
0.3
0.4
0.5
0.6
00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 00
HourFlow N1 (MGD)Site A9 Site B1
Site B1 Baseline Weekday Flow: 0.30 MGD
Site A9 Baseline Weekday Flow: 0.28 MGD
Agenda Item 9.1
Page 230 of 768
Figure 27. Minimum Flow Ratios vs. ADWF 12
12 Due to attenuation, it should be expected that sites with larger flow volumes should not have quite the peak-to-average and
low-to-average flow ratios as sites with lesser flow volumes, which is why the WEF typical trend lines slope closer to 1.0 as the
ADWF increases, as shown in the figure.
-
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.00 0.20 0.40 0.60 0.80 1.00Minimum to Average Flow Ratio ADWF (mgd)
Basin 6
Basin 4
Basin 5
Agenda Item 9.1
Page 231 of 768
Figure 28. Basins with Groundwater Infiltration
Legend
Groundwater Infiltration
Above typical rates
At or below typical rates
Agenda Item 9.1
Page 232 of 768
Combined I/I Results Summary
Combined I/I analysis considers the totalized volume (in gallons) of both inflow and rainfall-dependent
infiltration over the course of the storm event. Table 11 summarizes the combined I/I results (refer to
the I/I Methods section for more information on combined I/I analysis methods and ranking methods).
Basins that ranked 1, 2 or 3 in a category are color coded red.
Table 11. Basin Combined I/I Analysis Summary
Metering
Basin
ADWF
(mgd)
Combined
I/I
(gallons)
R-Value
(%)
Combined I/I
per ADWF
Combined
I/I
RankingA
Basin 1 0.72 334,600 0.32% (6)B 0.202 (6) 6
Basin 2 0.49 153,000 0.33% (5) 0.140 (8) 7
Basin 3 0.36 483,500 1.01% (1) 0.633 (1) 1
Basin 4 0.13 71,000 0.33% (4) 0.246 (5) 4
Basin 5 0.12 135,200 0.25% (7) 0.496 (2) 3
Basin 6 0.07 41,700 0.09% (11) 0.267 (3) 8
Basin 7 0.15 19,800 0.23% (8) 0.059 (11) 10
Basin 8 0.29 166,700 0.48% (2) 0.252 (4) 2
Basin 9 0.12 38,400 0.36% (3) 0.146 (7) 5
Basin 10 0.31 40,700 0.15% (10) 0.060 (10) 11
Basin 11 0.54 132,700 0.22% (9) 0.116 (9) 9
A Ranking of 1 represents most combined I/I after normalization.
B The number in parenthesis shows the ranking within the individual Category
The following combined I/I analysis results are noted:
Basins 3, 5 and 8 ranked highest for normalized combined I/I contribution.
Figure 29 shows bar graph summaries of the combined I/I analysis. A temperature map by overall
ranking is shown in Figure 30.
Agenda Item 9.1
Page 233 of 768
Figure 29. Bar Graphs: Combined I/I Analysis Summary
0.0%
0.2%
0.4%
0.6%
0.8%
1.0%
1.2%Basin 1Basin 2Basin 3Basin 4Basin 5Basin 6Basin 7Basin 8Basin 9Basin 10Basin 11R-Value (%) 0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
Basin 1Basin 2Basin 3Basin 4Basin 5Basin 6Basin 7Basin 8Basin 9Basin 10Basin 11Combined I/I to ADWF Agenda Item 9.1
Page 234 of 768
Figure 30. Combined I/I Temperature Map (by Rank)
Legend
Combined I/I Ranking
1-2
3-4
5-6
7-8
9-11
Agenda Item 9.1
Page 235 of 768
Inflow / Infiltration: Synthetic Hydrographs
In order to model design storms, synthetic hydrographs were developed to approximate the actual
RDI hydrograph shape in terms of the time to the peak and the recession coefficient. The actual RDI
hydrograph was best matched with a synthetic hydrograph by separating the synthetic hydrograph
into seven volume components (R1 through R7). The seven components represent different
response times to the rainfall event and, therefore, different infiltration or inflow paths into the sewer
system. R1 is characterized by a short response time and is assumed to consist of mainly inflow. R7
represents slower response and longer recession times and consists of mostly infiltration. Levels of
soil saturation are also considered. Using synthetic hydrograph analysis, appropriate time and
recession parameters were estimated by a trial-and-error procedure until a good match was obtained.
For example, the hydrograph and its component hydrographs for Storm Event 1, for Site 3 is shown in
Figure 31.
Figure 31. Site 3, Storm Event 1: Synthetic Hydrograph
Rain Realtime I/I Hydrograph
Synthetic Hydrograph R1 Component
R2 Component R3 Component
R4 Component R5 Component
R6 Component R7 Component
Agenda Item 9.1
Page 236 of 768
Design Storm Development
With the I/I response modeled by a synthetic hydrograph, design storms can be applied. This serves
two functions: (a) predicted flows are based on the same storm event and are therefore normalized to
each other, making for easier and better comparisons, and (b) the resulting I/I flows can be predicted
for a design storm event. This helps to calibrate modeling efforts that will determine if the collection
system has adequate capacity to handle very large storm events.
V&A used a 10-year, 24-hour design storm for this analysis. Storm events were taken from the
NOAA Precipitation-Frequency Atlas of the Western United States. Figure 32 summarizes the design
storm magnitude and profile. This particular profile distribution also fits the NOAA criterion for 2-hour
and 6-hour durations, in addition to the 24-hour duration.
10-Year, 24-
hour Design
Storm
Hour
Inches
of
Rain
1 0.010
2 0.026
3 0.255
4 0.153
5 0.051
6 0.015
7 0.219
8 0.125
9 0.176
10 0.063
11 0.031
12 0.013
13 0.129
14 0.362
15 0.043
16 0.197
17 0.197
18 0.432
19 0.801
20 0.395
21 0.197
22 0.103
23 0.172
24 0.052
Total: 4.22
Figure 32. 10-Year, 24-Hour Design Storm Values and Profile
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Rainfall (in/hr) Agenda Item 9.1
Page 237 of 768
Design Storm Response Summary
The 10-year, 24-hour storm event was applied to the synthetic I/I hydrograph components developed
for each flow monitoring site. This method produces the best estimated response to the design storm
events. These results assume full ground saturation and that the peak I/I flows from the design storm
coincide with peak sanitary flows to produce a “worst-case” scenario of peak wet weather flows.
Table 12 summarizes the final results for the design storm on a site-by-site basis.
Table 12. Design Storm I/I Analysis Summary
Metering
Site
Predicted
Peak Dry
Weather
Flow (mgd)
Predicted
Peak I/I
Rate
(mgd)
Predicted
Peak
Flow
(mgd)
Predicted
Total I/I
(gallons)
Site 1 1.50 6.74 8.24 2,251,000
Site 2 1.77 4.01 5.77 1,514,000
Site 3 4.50 7.16 11.67 4,598,000
Site 4 0.21 0.42 0.63 145,000
Site 5 0.21 0.71 0.92 467,000
Site 6 0.11 0.23 0.33 104,000
Site 7 0.23 0.45 0.67 91,000
Site 8 0.53 1.69 2.22 358,000
Site 9 4.31 7.98 12.29 4,080,000
Site 10 0.53 0.70 1.24 153,000
Site 11 0.93 0.78 1.72 290,000
Agenda Item 9.1
Page 238 of 768
RECOMMENDATIONS
V&A advises that future I/I reduction plans consider the following recommendations:
4. Determine I/I Reduction Program: The City should examine its I/I reduction needs to
determine a future I/I reduction program.
a. If peak flows, sanitary sewer overflows, and pipeline capacity issues are of greater
concern, then priority can be given to investigate and reduce sources of inflow within the
basins with the greatest inflow problems. The highest inflow occurred in Basins 1, 7 and
8.
b. If total infiltration and general pipeline deterioration are of greater concern, then the
program can be weighted to investigate and reduce sources of infiltration within the
basins with the greatest infiltration problems.
i. The highest normalized rainfall-dependent infiltration occurred in Basins 3, 4 and 8.
ii. The highest groundwater infiltration occurred in Basins 4, 5 and 6.
5. I/I Investigation Methods: Potential I/I investigation methods include the following:
a. Smoke testing.
b. Mini-basin flow monitoring.
c. Nighttime reconnaissance work to (1) investigate and determine direct point sources of
inflow and (2) determine the areas and pipe reaches responsible for high levels of
infiltration contribution.
6. I/I Reduction Cost-Effectiveness Analysis: The City should conduct a study to determine
which is more cost-effective: (1) locating the sources of inflow and infiltration and
systematically rehabilitating or replacing the faulty pipelines or (2) continued treatment of the
additional rainfall-dependent I/I flow.
Agenda Item 9.1
Page 239 of 768
APPENDIX A
FLOW MONITORING SITES: DATA, GRAPHS, INFORMATION
Agenda Item 9.1
Page 240 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 1
Inside WWTP property 100’ west of Influent Pump
Station
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 1
Data Summary Report
Page S1 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 241 of 768
SITE 1
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:27 inches
Baseline Flow:1.042 mgd
Peak Measured Flow:2.816 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:Inside WWTP property 100’
west of Influent Pump Station
Coordinates:121.5425° W, 36.9860° N
Rim Elevation:175 feet
Plan View
Page S1 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 242 of 768
SITE 1
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S1 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
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SITE 1Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.200.400.600.801.001.201.401.602/252/273/13/33/53/73/93/113/133/15Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.200.400.600.801.001.201.401.602/252/273/13/33/53/73/93/113/133/150.00.51.01.52.02.53.03.54.04.55.00.000.200.400.600.801.001.201.401.602/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.72 inchesAvg Period Flow: 1.077 MGal Peak Daily Flow: 1.476 MGal Min Daily Flow: 1.013 MGalPage S1 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 244 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 1Flow Summary: 2/25/2014 to 3/16/20140.000.501.001.502.002.503.003.50Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.501.001.502.002.503.003.50Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.72 inchesAvg Flow: 1.077 mgd Peak Flow: 2.816 mgd Min Flow: 0.362 mgdPage S1 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 245 of 768
SITE 1Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.200.400.600.801.001.201.401.601.802.000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day1.042mgdBaseline Flow:Page S1 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 246 of 768
SITE 1Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:12.8Peak d/D Ratio:0.47Pipe Diameter:27inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter05101520253002/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S1 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 247 of 768
SITE 1
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.28 inches
Event 1
0.00
0.50
1.00
1.50
2.00
2.50
3.00
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.28 inches)
2.82Peak Flow:
PF:
mgd
2.70
Capacity
2.37Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons582,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S1 - 8
Agenda Item 9.1
Page 248 of 768
SITE 1
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Velocity (fps)Vel
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.51 inches
Avg Level: 8.12 in. Peak Level: 12.80 in. Min Level: 5.35 in.
Avg Velocity: 1.70 fps Peak Velocity: 2.37 fps Min Velocity: 1.09 fps
Avg Flow: 1.150 mgd Peak Flow: 2.816 mgd Min Flow: 0.395 mgd
Page S1 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 249 of 768
SITE 1
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Velocity (fps)Vel
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.22 inches
Avg Level: 7.87 in. Peak Level: 10.12 in. Min Level: 5.27 in.
Avg Velocity: 1.63 fps Peak Velocity: 2.05 fps Min Velocity: 1.04 fps
Avg Flow: 1.052 mgd Peak Flow: 1.777 mgd Min Flow: 0.367 mgd
Page S1 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 250 of 768
SITE 1
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Velocity (fps)Vel
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 7.83 in. Peak Level: 10.13 in. Min Level: 5.24 in.
Avg Velocity: 1.62 fps Peak Velocity: 2.07 fps Min Velocity: 1.03 fps
Avg Flow: 1.040 mgd Peak Flow: 1.801 mgd Min Flow: 0.362 mgd
Page S1 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 251 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 2
ROW southeast of Holloway Road
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 2
Data Summary Report
Page S2 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 252 of 768
SITE 2
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:25 inches
Baseline Flow:1.239 mgd
Peak Measured Flow:2.211 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:ROW southeast of Holloway
Road
Coordinates:121.5444° W, 36.9916° N
Rim Elevation:177 feet
Plan View
Page S2 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 253 of 768
SITE 2
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S2 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 254 of 768
SITE 2Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.200.400.600.801.001.201.401.602/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.200.400.600.801.001.201.401.602/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.200.400.600.801.001.201.401.602/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.61 inchesAvg Period Flow: 1.254 MGal Peak Daily Flow: 1.501 MGal Min Daily Flow: 1.155 MGalPage S2 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 255 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 2Flow Summary: 2/25/2014 to 3/16/20140.000.501.001.502.002.503.003.504.00Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.501.001.502.002.503.003.504.00Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.61 inchesAvg Flow: 1.259 mgd Peak Flow: 2.211 mgd Min Flow: 0.375 mgdPage S2 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 256 of 768
SITE 2Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.501.001.502.002.500:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day1.239mgdBaseline Flow:Page S2 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 257 of 768
SITE 2Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:15.9Peak d/D Ratio:0.64Pipe Diameter:25inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter05101520253002/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S2 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 258 of 768
SITE 2
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.27 inches
Event 1
0.00
0.50
1.00
1.50
2.00
2.50
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.27 inches)
2.21Peak Flow:
PF:
mgd
1.79
Capacity
1.66Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons380,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S2 - 8
Agenda Item 9.1
Page 259 of 768
SITE 2
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Velocity (fps)Vel
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.41 inches
Avg Level: 11.43 in. Peak Level: 15.92 in. Min Level: 7.24 in.
Avg Velocity: 1.36 fps Peak Velocity: 1.67 fps Min Velocity: 0.87 fps
Avg Flow: 1.278 mgd Peak Flow: 2.211 mgd Min Flow: 0.405 mgd
Page S2 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 260 of 768
SITE 2
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Velocity (fps)Vel
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.20 inches
Avg Level: 11.28 in. Peak Level: 15.02 in. Min Level: 7.02 in.
Avg Velocity: 1.36 fps Peak Velocity: 1.59 fps Min Velocity: 0.85 fps
Avg Flow: 1.254 mgd Peak Flow: 1.988 mgd Min Flow: 0.375 mgd
Page S2 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 261 of 768
SITE 2
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Velocity (fps)Vel
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 11.26 in. Peak Level: 14.74 in. Min Level: 7.40 in.
Avg Velocity: 1.34 fps Peak Velocity: 1.58 fps Min Velocity: 0.87 fps
Avg Flow: 1.231 mgd Peak Flow: 1.991 mgd Min Flow: 0.422 mgd
Page S2 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 262 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 3
ROW southeast of Holloway Road
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 3
Data Summary Report
Page S3 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 263 of 768
SITE 3
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:33 inches
Baseline Flow:3.660 mgd
Peak Measured Flow:6.693 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:ROW southeast of Holloway
Road
Coordinates:121.5464° W, 36.9942° N
Rim Elevation:179 feet
Plan View
Page S3 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 264 of 768
SITE 3
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S3 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 265 of 768
SITE 3Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.001.002.003.004.005.006.002/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.001.002.003.004.005.006.002/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.001.002.003.004.005.006.002/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.63 inchesAvg Period Flow: 3.810 MGal Peak Daily Flow: 4.815 MGal Min Daily Flow: 3.504 MGalPage S3 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 266 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 3Flow Summary: 2/25/2014 to 3/16/20140.002.004.006.008.0010.0012.00Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.002.004.006.008.0010.0012.00Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.63 inchesAvg Flow: 3.810 mgd Peak Flow: 6.693 mgd Min Flow: 1.475 mgdPage S3 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 267 of 768
SITE 3Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.001.002.003.004.005.006.000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day3.660mgdBaseline Flow:Page S3 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 268 of 768
SITE 3Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:18.2Peak d/D Ratio:0.55Pipe Diameter:33inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter0510152025303502/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S3 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 269 of 768
SITE 3
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
2.00
4.00
6.00
8.00
10.00
12.00
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.30 inches
Event 1
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.30 inches)
6.69Peak Flow:
PF:
mgd
1.83
Capacity
3.18Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons1,790,000
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Agenda Item 9.1
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SITE 3
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
35
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
2.00
4.00
6.00
8.00
10.00
12.00
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.43 inches
Avg Level: 13.73 in. Peak Level: 18.22 in. Min Level: 9.37 in.
Avg Velocity: 2.63 fps Peak Velocity: 3.13 fps Min Velocity: 1.74 fps
Avg Flow: 4.054 mgd Peak Flow: 6.693 mgd Min Flow: 1.565 mgd
Page S3 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
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SITE 3
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
35
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
2.00
4.00
6.00
8.00
10.00
12.00
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.20 inches
Avg Level: 13.20 in. Peak Level: 16.81 in. Min Level: 9.43 in.
Avg Velocity: 2.57 fps Peak Velocity: 3.26 fps Min Velocity: 1.76 fps
Avg Flow: 3.767 mgd Peak Flow: 5.905 mgd Min Flow: 1.628 mgd
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Agenda Item 9.1
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SITE 3
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
35
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
2.00
4.00
6.00
8.00
10.00
12.00
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 13.25 in. Peak Level: 17.00 in. Min Level: 9.24 in.
Avg Velocity: 2.45 fps Peak Velocity: 2.95 fps Min Velocity: 1.67 fps
Avg Flow: 3.608 mgd Peak Flow: 5.677 mgd Min Flow: 1.475 mgd
Page S3 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 273 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 4
W. Luchessa Avenue near Hyde Park Drive
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 4
Data Summary Report
Page S4 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 274 of 768
SITE 4
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:12 inches
Baseline Flow:0.126 mgd
Peak Measured Flow:0.306 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:W. Luchessa Avenue near
Hyde Park Drive
Coordinates:121.5638° W, 36.9915° N
Rim Elevation:196 feet
Plan View
Page S4 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 275 of 768
SITE 4
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S4 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 276 of 768
SITE 4Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.020.040.060.080.100.120.140.160.182/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.020.040.060.080.100.120.140.160.182/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.020.040.060.080.100.120.140.160.182/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.74 inchesAvg Period Flow: 0.132 MGal Peak Daily Flow: 0.164 MGal Min Daily Flow: 0.117 MGalPage S4 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 277 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 4Flow Summary: 2/25/2014 to 3/16/20140.000.100.200.300.400.500.60Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.100.200.300.400.500.60Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.74 inchesAvg Flow: 0.132 mgd Peak Flow: 0.306 mgd Min Flow: 0.035 mgdPage S4 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 278 of 768
SITE 4Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.050.100.150.200.250:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day0.126mgdBaseline Flow:Page S4 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 279 of 768
SITE 4Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:2.86Peak d/D Ratio:0.24Pipe Diameter:12inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter0246810121402/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S4 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 280 of 768
SITE 4
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.10
0.20
0.30
0.40
0.50
0.60
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.28 inches
Event 1
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.28 inches)
0.31Peak Flow:
PF:
mgd
2.42
Capacity
0.14Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons71,000
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Agenda Item 9.1
Page 281 of 768
SITE 4
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.52 inches
Avg Level: 1.85 in. Peak Level: 2.86 in. Min Level: 0.94 in.
Avg Velocity: 2.69 fps Peak Velocity: 3.30 fps Min Velocity: 1.85 fps
Avg Flow: 0.139 mgd Peak Flow: 0.306 mgd Min Flow: 0.035 mgd
Page S4 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 282 of 768
SITE 4
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.22 inches
Avg Level: 1.80 in. Peak Level: 2.59 in. Min Level: 1.14 in.
Avg Velocity: 2.68 fps Peak Velocity: 3.17 fps Min Velocity: 1.88 fps
Avg Flow: 0.131 mgd Peak Flow: 0.250 mgd Min Flow: 0.050 mgd
Page S4 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 283 of 768
SITE 4
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 1.74 in. Peak Level: 2.66 in. Min Level: 1.08 in.
Avg Velocity: 2.67 fps Peak Velocity: 3.34 fps Min Velocity: 1.84 fps
Avg Flow: 0.125 mgd Peak Flow: 0.278 mgd Min Flow: 0.044 mgd
Page S4 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 284 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 5
Wren Avenue and Uvas Park Drive
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 5
Data Summary Report
Page S5 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 285 of 768
SITE 5
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:10.5 inches
Baseline Flow:0.120 mgd
Peak Measured Flow:0.410 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:Wren Avenue and Uvas Park
Drive
Coordinates:121.5881° W, 37.0010° N
Rim Elevation:215 feet
Plan View
Page S5 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 286 of 768
SITE 5
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S5 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 287 of 768
SITE 5Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.050.100.150.200.252/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.050.100.150.200.252/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.050.100.150.200.252/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.75 inchesAvg Period Flow: 0.131 MGal Peak Daily Flow: 0.210 MGal Min Daily Flow: 0.107 MGalPage S5 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 288 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 5Flow Summary: 2/25/2014 to 3/16/20140.000.100.200.300.400.500.60Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.100.200.300.400.500.60Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.75 inchesAvg Flow: 0.132 mgd Peak Flow: 0.410 mgd Min Flow: 0.027 mgdPage S5 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 289 of 768
SITE 5Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.050.100.150.200.250:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day0.120mgdBaseline Flow:Page S5 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 290 of 768
SITE 5Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:7.1Peak d/D Ratio:0.68Pipe Diameter:10.5inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter02468101202/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S5 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 291 of 768
SITE 5
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.10
0.20
0.30
0.40
0.50
0.60
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.28 inches
Event 1
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.28 inches)
0.41Peak Flow:
PF:
mgd
3.43
Capacity
0.22Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons135,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S5 - 8
Agenda Item 9.1
Page 292 of 768
SITE 5
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.53 inches
Avg Level: 5.22 in. Peak Level: 7.10 in. Min Level: 3.81 in.
Avg Velocity: 0.75 fps Peak Velocity: 1.50 fps Min Velocity: 0.35 fps
Avg Flow: 0.149 mgd Peak Flow: 0.410 mgd Min Flow: 0.045 mgd
Page S5 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 293 of 768
SITE 5
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.22 inches
Avg Level: 4.90 in. Peak Level: 5.99 in. Min Level: 3.71 in.
Avg Velocity: 0.72 fps Peak Velocity: 1.16 fps Min Velocity: 0.36 fps
Avg Flow: 0.130 mgd Peak Flow: 0.261 mgd Min Flow: 0.047 mgd
Page S5 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 294 of 768
SITE 5
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 4.74 in. Peak Level: 5.66 in. Min Level: 3.52 in.
Avg Velocity: 0.66 fps Peak Velocity: 1.06 fps Min Velocity: 0.24 fps
Avg Flow: 0.115 mgd Peak Flow: 0.224 mgd Min Flow: 0.027 mgd
Page S5 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 295 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 6
100’ south of west end of 3rd Street on bike path
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 6
Data Summary Report
Page S6 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 296 of 768
SITE 6
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:24 inches
Baseline Flow:0.071 mgd
Peak Measured Flow:0.152 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:100’ south of west end of 3rd
Street on bike path
Coordinates:121.6019° W, 37.0073° N
Rim Elevation:226 feet
Plan View
Page S6 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 297 of 768
SITE 6
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S6 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 298 of 768
SITE 6
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Lateral
Appendix A, Page S6 - 413-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 299 of 768
SITE 6Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.010.020.030.040.050.060.070.080.090.102/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.010.020.030.040.050.060.070.080.090.102/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.010.020.030.040.050.060.070.080.090.102/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.58 inchesAvg Period Flow: 0.071 MGal Peak Daily Flow: 0.095 MGal Min Daily Flow: 0.061 MGalPage S6 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 300 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 6Flow Summary: 2/25/2014 to 3/16/20140.000.050.100.150.200.25Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.050.100.150.200.25Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.58 inchesAvg Flow: 0.071 mgd Peak Flow: 0.152 mgd Min Flow: 0.030 mgdPage S6 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 301 of 768
SITE 6Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.020.040.060.080.100.120.140:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day0.071mgdBaseline Flow:Page S6 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 302 of 768
SITE 6Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:4.05Peak d/D Ratio:0.17Pipe Diameter:24inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter05101520253002/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S6 - 813-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 303 of 768
SITE 6
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.05
0.10
0.15
0.20
0.25
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.21 inches
Event 1
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.21 inches)
0.15Peak Flow:
PF:
mgd
2.15
Capacity
0.10Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons42,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S6 - 9
Agenda Item 9.1
Page 304 of 768
SITE 6
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Velocity (fps)Vel
0.00
0.05
0.10
0.15
0.20
0.25
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.38 inches
Avg Level: 3.05 in. Peak Level: 3.82 in. Min Level: 2.40 in.
Avg Velocity: 0.48 fps Peak Velocity: 0.76 fps Min Velocity: 0.28 fps
Avg Flow: 0.072 mgd Peak Flow: 0.152 mgd Min Flow: 0.031 mgd
Page S6 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 305 of 768
SITE 6
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Velocity (fps)Vel
0.00
0.05
0.10
0.15
0.20
0.25
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.20 inches
Avg Level: 3.07 in. Peak Level: 3.90 in. Min Level: 2.43 in.
Avg Velocity: 0.45 fps Peak Velocity: 0.75 fps Min Velocity: 0.28 fps
Avg Flow: 0.068 mgd Peak Flow: 0.148 mgd Min Flow: 0.030 mgd
Page S6 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 306 of 768
SITE 6
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Velocity (fps)Vel
0.00
0.05
0.10
0.15
0.20
0.25
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 3.11 in. Peak Level: 4.05 in. Min Level: 2.58 in.
Avg Velocity: 0.47 fps Peak Velocity: 0.69 fps Min Velocity: 0.28 fps
Avg Flow: 0.071 mgd Peak Flow: 0.127 mgd Min Flow: 0.034 mgd
Page S6 - 1213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 307 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 7
East end of E. 9th Street near Highway 101 offramp
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 7
Data Summary Report
Page S7 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 308 of 768
SITE 7
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:10 inches
Baseline Flow:0.148 mgd
Peak Measured Flow:0.279 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:East end of E. 9th Street
near Highway 101 offramp
Coordinates:121.5581° W, 37.0042° N
Rim Elevation:193 feet
Plan View
Page S7 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 309 of 768
SITE 7
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S7 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 310 of 768
SITE 7Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.020.040.060.080.100.120.140.160.182/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.020.040.060.080.100.120.140.160.182/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.020.040.060.080.100.120.140.160.182/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.66 inchesAvg Period Flow: 0.146 MGal Peak Daily Flow: 0.168 MGal Min Daily Flow: 0.096 MGalPage S7 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 311 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 7Flow Summary: 2/25/2014 to 3/16/20140.000.100.200.300.400.500.60Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.100.200.300.400.500.60Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.66 inchesAvg Flow: 0.147 mgd Peak Flow: 0.279 mgd Min Flow: 0.021 mgdPage S7 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 312 of 768
SITE 7Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.050.100.150.200.250.300:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day0.148mgdBaseline Flow:Page S7 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 313 of 768
SITE 7Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I StudySurcharged 23.6 inches over crownPeak Measured Level:33.6Peak d/D Ratio:3.36Pipe Diameter:10inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter051015202530354002/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S7 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 314 of 768
SITE 7
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.10
0.20
0.30
0.40
0.50
0.60
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.28 inches
Event 1
0.00
0.05
0.10
0.15
0.20
0.25
0.30
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.28 inches)
0.26Peak Flow:
PF:
mgd
1.78
Capacity
0.20Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons20,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S7 - 8
Agenda Item 9.1
Page 315 of 768
SITE 7
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
35
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.45 inches
Avg Level: 6.77 in. Peak Level: 13.27 in. Min Level: 2.58 in.
Avg Velocity: 0.63 fps Peak Velocity: 0.96 fps Min Velocity: 0.20 fps
Avg Flow: 0.145 mgd Peak Flow: 0.262 mgd Min Flow: 0.043 mgd
Page S7 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 316 of 768
SITE 7
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
35
40
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.21 inches
Avg Level: 14.07 in. Peak Level: 33.62 in. Min Level: 2.68 in.
Avg Velocity: 0.53 fps Peak Velocity: 0.92 fps Min Velocity: 0.06 fps
Avg Flow: 0.150 mgd Peak Flow: 0.279 mgd Min Flow: 0.021 mgd
Page S7 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 317 of 768
SITE 7
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
35
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Velocity (fps)Vel
0.00
0.10
0.20
0.30
0.40
0.50
0.60
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 15.53 in. Peak Level: 31.26 in. Min Level: 8.37 in.
Avg Velocity: 0.41 fps Peak Velocity: 0.78 fps Min Velocity: 0.11 fps
Avg Flow: 0.144 mgd Peak Flow: 0.273 mgd Min Flow: 0.035 mgd
Page S7 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 318 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 8
Near northwest end of Renz Lane
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 8
Data Summary Report
Page S8 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 319 of 768
SITE 8
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:14 inches
Baseline Flow:0.294 mgd
Peak Measured Flow:0.910 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:Near northwest end of Renz
Lane
Coordinates:121.5571° W, 37.0057° N
Rim Elevation:191 feet
Plan View
Page S8 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 320 of 768
SITE 8
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S8 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 321 of 768
SITE 8Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.050.100.150.200.250.300.350.400.452/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.050.100.150.200.250.300.350.400.452/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.050.100.150.200.250.300.350.400.452/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.62 inchesAvg Period Flow: 0.311 MGal Peak Daily Flow: 0.412 MGal Min Daily Flow: 0.245 MGalPage S8 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 322 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 8Flow Summary: 2/25/2014 to 3/16/20140.000.200.400.600.801.001.20Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.200.400.600.801.001.20Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.62 inchesAvg Flow: 0.313 mgd Peak Flow: 0.910 mgd Min Flow: 0.053 mgdPage S8 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 323 of 768
SITE 8Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.100.200.300.400.500.600.700:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day0.294mgdBaseline Flow:Page S8 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 324 of 768
SITE 8Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:6.51Peak d/D Ratio:0.47Pipe Diameter:14inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter024681012141602/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S8 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 325 of 768
SITE 8
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.20
0.40
0.60
0.80
1.00
1.20
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.25 inches
Event 1
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.25 inches)
0.91Peak Flow:
PF:
mgd
3.09
Capacity
0.84Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons167,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S8 - 8
Agenda Item 9.1
Page 326 of 768
SITE 8
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
14
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.41 inches
Avg Level: 3.93 in. Peak Level: 6.51 in. Min Level: 2.14 in.
Avg Velocity: 1.99 fps Peak Velocity: 2.89 fps Min Velocity: 0.91 fps
Avg Flow: 0.339 mgd Peak Flow: 0.910 mgd Min Flow: 0.070 mgd
Page S8 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 327 of 768
SITE 8
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
14
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.20 inches
Avg Level: 3.54 in. Peak Level: 4.99 in. Min Level: 1.90 in.
Avg Velocity: 1.87 fps Peak Velocity: 2.64 fps Min Velocity: 0.96 fps
Avg Flow: 0.283 mgd Peak Flow: 0.583 mgd Min Flow: 0.056 mgd
Page S8 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 328 of 768
SITE 8
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
14
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 3.68 in. Peak Level: 5.77 in. Min Level: 1.85 in.
Avg Velocity: 1.92 fps Peak Velocity: 2.82 fps Min Velocity: 0.94 fps
Avg Flow: 0.311 mgd Peak Flow: 0.742 mgd Min Flow: 0.053 mgd
Page S8 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 329 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 9
Behind Nike Outlet Store off Arroyo Circle
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 9
Data Summary Report
Page S9 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 330 of 768
SITE 9
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:33 inches
Baseline Flow:3.304 mgd
Peak Measured Flow:6.486 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:Behind Nike Outlet Store off
Arroyo Circle
Coordinates:121.5649° W, 37.0206° N
Rim Elevation:202 feet
Plan View
Page S9 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 331 of 768
SITE 9
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S9 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 332 of 768
SITE 9Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.501.001.502.002.503.003.504.004.505.002/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.501.001.502.002.503.003.504.004.505.002/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.501.001.502.002.503.003.504.004.505.002/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.52 inchesAvg Period Flow: 3.403 MGal Peak Daily Flow: 4.366 MGal Min Daily Flow: 3.168 MGalPage S9 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 333 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 9Flow Summary: 2/25/2014 to 3/16/20140.001.002.003.004.005.006.007.008.009.00Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.001.002.003.004.005.006.007.008.009.00Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.52 inchesAvg Flow: 3.406 mgd Peak Flow: 6.486 mgd Min Flow: 1.224 mgdPage S9 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 334 of 768
SITE 9Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.001.002.003.004.005.006.000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day3.304mgdBaseline Flow:Page S9 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 335 of 768
SITE 9Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:14.5Peak d/D Ratio:0.44Pipe Diameter:33inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter0510152025303502/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S9 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 336 of 768
SITE 9
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.20 inches
Event 1
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.20 inches)
6.49Peak Flow:
PF:
mgd
1.96
Capacity
3.75Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons1,307,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S9 - 8
Agenda Item 9.1
Page 337 of 768
SITE 9
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Velocity (fps)Vel
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.33 inches
Avg Level: 11.00 in. Peak Level: 14.51 in. Min Level: 7.24 in.
Avg Velocity: 3.08 fps Peak Velocity: 4.02 fps Min Velocity: 2.11 fps
Avg Flow: 3.557 mgd Peak Flow: 6.486 mgd Min Flow: 1.315 mgd
Page S9 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 338 of 768
SITE 9
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Velocity (fps)Vel
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.19 inches
Avg Level: 10.74 in. Peak Level: 13.39 in. Min Level: 7.18 in.
Avg Velocity: 3.01 fps Peak Velocity: 3.72 fps Min Velocity: 1.96 fps
Avg Flow: 3.356 mgd Peak Flow: 5.323 mgd Min Flow: 1.337 mgd
Page S9 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 339 of 768
SITE 9
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
5
10
15
20
25
30
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Velocity (fps)Vel
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 10.66 in. Peak Level: 13.61 in. Min Level: 7.01 in.
Avg Velocity: 2.98 fps Peak Velocity: 3.74 fps Min Velocity: 2.04 fps
Avg Flow: 3.298 mgd Peak Flow: 5.518 mgd Min Flow: 1.224 mgd
Page S9 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 340 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 10
Welburn Avenue west of Church Street
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 10
Data Summary Report
Page S10 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 341 of 768
SITE 10
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:10.5 inches
Baseline Flow:0.310 mgd
Peak Measured Flow:0.664 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:Welburn Avenue west of
Church Street
Coordinates:121.5781° W, 37.0189° N
Rim Elevation:207 feet
Plan View
Page S10 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 342 of 768
SITE 10
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S10 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 343 of 768
SITE 10Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.050.100.150.200.250.300.350.400.452/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.050.100.150.200.250.300.350.400.452/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.050.100.150.200.250.300.350.400.452/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.51 inchesAvg Period Flow: 0.307 MGal Peak Daily Flow: 0.408 MGal Min Daily Flow: 0.255 MGalPage S10 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 344 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 10Flow Summary: 2/25/2014 to 3/16/20140.000.200.400.600.801.001.20Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.200.400.600.801.001.20Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.51 inchesAvg Flow: 0.306 mgd Peak Flow: 0.664 mgd Min Flow: 0.063 mgdPage S10 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 345 of 768
SITE 10Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.100.200.300.400.500.600.700:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day0.310mgdBaseline Flow:Page S10 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 346 of 768
SITE 10Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:7.29Peak d/D Ratio:0.69Pipe Diameter:10.5inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter02468101202/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S10 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 347 of 768
SITE 10
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.20
0.40
0.60
0.80
1.00
1.20
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.18 inches
Event 1
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.18 inches)
0.58Peak Flow:
PF:
mgd
1.88
Capacity
0.40Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons41,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S10 - 8
Agenda Item 9.1
Page 348 of 768
SITE 10
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.32 inches
Avg Level: 5.01 in. Peak Level: 6.88 in. Min Level: 3.10 in.
Avg Velocity: 1.62 fps Peak Velocity: 2.36 fps Min Velocity: 0.64 fps
Avg Flow: 0.314 mgd Peak Flow: 0.591 mgd Min Flow: 0.066 mgd
Page S10 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 349 of 768
SITE 10
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.19 inches
Avg Level: 5.16 in. Peak Level: 7.19 in. Min Level: 3.27 in.
Avg Velocity: 1.60 fps Peak Velocity: 2.81 fps Min Velocity: 0.61 fps
Avg Flow: 0.324 mgd Peak Flow: 0.664 mgd Min Flow: 0.063 mgd
Page S10 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 350 of 768
SITE 10
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
1
2
3
4
5
6
7
8
9
10
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 5.22 in. Peak Level: 7.29 in. Min Level: 3.16 in.
Avg Velocity: 1.38 fps Peak Velocity: 2.42 fps Min Velocity: 0.61 fps
Avg Flow: 0.283 mgd Peak Flow: 0.650 mgd Min Flow: 0.065 mgd
Page S10 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 351 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Site 11
Intersection of Wren Avenue and Mantelli Drive
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Site 11
Data Summary Report
Page S11 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 352 of 768
SITE 11
Site Information
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Pipe Diameter:17.75 inches
Baseline Flow:0.535 mgd
Peak Measured Flow:1.161 mgd
Flow Sketch
Satellite Map
Street View
Sewer Map
Location:Intersection of Wren Avenue
and Mantelli Drive
Coordinates:121.5867° W, 37.0234° N
Rim Elevation:212 feet
Plan View
Page S11 - 213-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 353 of 768
SITE 11
Additional Site Photos
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Effluent Pipe
Influent Pipe
Appendix A, Page S11 - 313-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 354 of 768
SITE 11Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.100.200.300.400.500.600.702/242/262/283/23/43/63/83/103/123/143/16Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.000.100.200.300.400.500.600.702/242/262/283/23/43/63/83/103/123/143/160.00.51.01.52.02.53.03.54.04.55.00.000.100.200.300.400.500.600.702/242/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Total Period Rainfall: 3.45 inchesAvg Period Flow: 0.548 MGal Peak Daily Flow: 0.623 MGal Min Daily Flow: 0.507 MGalPage S11 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 355 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITE 11Flow Summary: 2/25/2014 to 3/16/20140.000.200.400.600.801.001.201.401.601.80Feb 25 (Tue) Feb 26 (Wed) Feb 27 (Thu) Feb 28 (Fri) Mar 1 (Sat) Mar 2 (Sun) Mar 3 (Mon) Mar 4 (Tue) Mar 5 (Wed) Mar 6 (Thu)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.000.200.400.600.801.001.201.401.601.80Mar 7 (Fri) Mar 8 (Sat) Mar 9 (Sun) Mar 10 (Mon) Mar 11 (Tue) Mar 12 (Wed) Mar 13 (Thu) Mar 14 (Fri) Mar 15 (Sat) Mar 16 (Sun)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.45 inchesAvg Flow: 0.549 mgd Peak Flow: 1.161 mgd Min Flow: 0.142 mgdPage S11 - 513-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 356 of 768
SITE 11Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.000.200.400.600.801.001.200:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day0.535mgdBaseline Flow:Page S11 - 613-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 357 of 768
SITE 11Site Capacity and Surcharge SummaryCity of GilroySanitary Sewer Flow Monitoring and I/I Study Peak Measured Level:11.4Peak d/D Ratio:0.64Pipe Diameter:17.8inchesinchesRealtime Flow Levels with Rainfall Data over Monitoring PeriodDiameter0246810121416182002/2502/2703/0103/0303/0503/0703/0903/1103/1303/15Level (in)0.00.20.40.60.81.01.21.41.61.82.0Rain (in)Page S11 - 713-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 358 of 768
SITE 11
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.14 inches
Event 1
0.00
0.20
0.40
0.60
0.80
1.00
1.20
02/2803/0103/02Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.14 inches)
1.11Peak Flow:
PF:
mgd
2.07
Capacity
0.39Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons133,000
13-0053 AEG Gilroy FM and II Rpt.doc Page S11 - 8
Agenda Item 9.1
Page 359 of 768
SITE 11
Weekly Level, Velocity and Flow Hydrographs
2/24/2014 to 3/3/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
14
16
18
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2/24 2/25 2/26 2/27 2/28 3/1 3/2Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 3.27 inches
Avg Level: 7.63 in. Peak Level: 11.39 in. Min Level: 4.75 in.
Avg Velocity: 1.18 fps Peak Velocity: 1.78 fps Min Velocity: 0.64 fps
Avg Flow: 0.563 mgd Peak Flow: 1.107 mgd Min Flow: 0.157 mgd
Page S11 - 913-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 360 of 768
SITE 11
Weekly Level, Velocity and Flow Hydrographs
3/3/2014 to 3/10/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
14
16
18
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
3/3 3/4 3/5 3/6 3/7 3/8 3/9Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlowTotal Weekly Rainfall: 0.18 inches
Avg Level: 7.36 in. Peak Level: 10.26 in. Min Level: 4.77 in.
Avg Velocity: 1.21 fps Peak Velocity: 1.91 fps Min Velocity: 0.66 fps
Avg Flow: 0.551 mgd Peak Flow: 1.161 mgd Min Flow: 0.167 mgd
Page S11 - 1013-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 361 of 768
SITE 11
Weekly Level, Velocity and Flow Hydrographs
3/10/2014 to 3/17/2014
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
0
2
4
6
8
10
12
14
16
18
Mon Tue Wed Thu Fri Sat Sun
Level (in)Lev
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Velocity (fps)Vel
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
3/10 3/11 3/12 3/13 3/14 3/15 3/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rain Flow BLFlow
Avg Level: 7.26 in. Peak Level: 10.30 in. Min Level: 4.65 in.
Avg Velocity: 1.18 fps Peak Velocity: 1.79 fps Min Velocity: 0.60 fps
Avg Flow: 0.531 mgd Peak Flow: 1.017 mgd Min Flow: 0.142 mgd
Page S11 - 1113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 362 of 768
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
Monitoring Site:
Location:
Sites 1+2+3
Sum of Sites 1, 2 and 3 -- total flow entering the
treatment facility
Temporary Monitoring: February and March, 2014
Sanitary Sewer Flow Monitoring
City of Gilroy
Vicinity Map: Sites 1+2+3
Data Summary Report
Page 1+2+3 - 113-0053 AEG Gilroy FM and II Rpt.doc
Agenda Item 9.1
Page 363 of 768
SITES 1+2+3Period Flow Summary: Daily Flow TotalsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.001.002.003.004.005.006.007.008.009.002/252/273/13/33/53/73/93/113/133/15Flow (MGal)0.00.51.01.52.02.53.03.54.04.55.0Rainfall (in/day)0.001.002.003.004.005.006.007.008.009.002/252/273/13/33/53/73/93/113/133/150.00.51.01.52.02.53.03.54.04.55.00.001.002.003.004.005.006.007.008.009.002/252/262/272/283/13/23/33/43/53/63/73/83/93/103/113/123/133/143/153/160.00.51.01.52.02.53.03.54.04.55.0Page 1+2+3 - 213-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 364 of 768
City of GilroySanitary Sewer Flow Monitoring and I/I StudySITES 1+2+3Flow Summary: 2/25/2014 to 3/16/20140.002.004.006.008.0010.0012.0014.0016.00Feb 25 (Tuesday)Feb 26 (Wednesday)Feb 27 (Thursday)Feb 28 (Friday)Mar 1 (Saturday)Mar 2 (Sunday)Mar 3 (Monday)Mar 4 (Tuesday)Mar 5 (Wednesday)Mar 6 (Thursday)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)RainFlowBLFlow0.002.004.006.008.0010.0012.0014.0016.00Mar 7 (Friday)Mar 8 (Saturday)Mar 9 (Sunday)Mar 10 (Monday)Mar 11 (Tuesday)Mar 12 (Wednesday)Mar 13 (Thursday)Mar 14 (Friday)Mar 15 (Saturday)Mar 16 (Sunday)Flow (mgd)0.00.20.40.60.81.01.2Rainfall (in/hr)Total Period Rainfall: 3.64 inchesAvg Flow: 6.147 mgd Peak Flow: 10.785 mgd Min Flow: 2.522 mgdPage 1+2+3 - 313-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 365 of 768
SITES 1+2+3Baseline Flow HydrographsCity of GilroySanitary Sewer Flow Monitoring and I/I Study0.001.002.003.004.005.006.007.008.009.0010.000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00Flow (mgd)Mon-ThursFridaySaturdaySundayTime of Day5.944mgdBaseline Flow:Page 1+2+3 - 413-0053 AEG Gilroy FM and II Rpt.docAgenda Item 9.1Page 366 of 768
SITES 1+2+3
City of Gilroy
Sanitary Sewer Flow Monitoring and I/I Study
I/I Summary: Event 1
Baseline and Realtime Flows with Rainfall Data over Monitoring Period
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
0.2
0.4
0.6
0.8
1.0
1.2 Rain (in/hr)Rainfall: 2.29 inches
Event 1
0.00
2.00
4.00
6.00
8.00
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12.00
02/2803/0103/02Flow (mgd)0.0
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0.6
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1.0
1.2 Rain (in/hr)Event 1 Detail Graph
Storm Event I/I Analysis (Rain = 2.29 inches)
10.78Peak Flow:
PF:
mgd
1.81
Capacity
5.92Peak I/I Rate:mgd
Inflow / Infiltration
Total I/I:gallons2,796,000
13-0053 AEG Gilroy FM and II Rpt.doc Page 1+2+3 - 5
Agenda Item 9.1
Page 367 of 768
Flow Site
Rain Gauge
RG West
RG Southwest
RG Northeast N
Houston
8220 Jones Road, Suite 500
Houston, TX 77065
713.568.9067 Tel
vaengineering.com
Oakland
155 Grand Avenue, Suite 700
Oakland, CA 94612
510.903.6600 Tel
510.903.6601 Fax
San Diego
11011 Via Frontera, Suite C
San Diego, CA 92127
858.576.0226 Tel
Las Vegas
3430 East Russell Road, Suite 316
Las Vegas, NV 89120
702.522.7967 Tel
702.553.4694 Fax
Agenda Item 9.1
Page 368 of 768
March 2023 City of Gilroy
Sewer System Master Plan
City of Gilroy
APPENDIX B
Hydraulic Model Calibration Exhibits
City of Gilroy
Agenda Item 9.1
Page 369 of 768
Figure 6.5
Site 1 Calibration
Inside WWTP
Sewer System Master Plan
City of Gilroy
LEGEND
June 29, 2016
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Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring
Agenda Item 9.1
Page 370 of 768
Figure 6.6
Site 2 Calibration
ROW se/o Holloway Rd.
Sewer System Master Plan
City of Gilroy
LEGEND
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Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 371 of 768
Figure 6.7
Site 3 Calibration
ROW se/o Holloway Rd.
Sewer System Master Plan
City of Gilroy
LEGEND
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Wet Weather Event 1 (02/26/14 -02/27/14)
Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 372 of 768
Figure 6.8
Site 4 Calibration
W. Luchessa Ave. and Hyde Park Dr.
Sewer System Master Plan
City of Gilroy
LEGEND
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Wet Weather Event 1 (02/26/14 -02/27/14)
Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 373 of 768
Figure 6.9
Site 5 Calibration
Wren Ave. and Uvas Park Dr.
Sewer System Master Plan
City of Gilroy
LEGEND
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Wet Weather Event 1 (02/26/14 -02/27/14)
Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 374 of 768
Figure 6.10
Site 6 Calibration
sw/o 3rd S.t and Santa Teresa Blvd.
Sewer System Master Plan
City of Gilroy
LEGEND
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Wet Weather Event 1 (02/26/14 -02/27/14)
Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 375 of 768
Figure 6.11
Site 7 Calibration
E. 9th St. and Highway 101 Off-ramp
Sewer System Master Plan
City of Gilroy
LEGEND
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0 5 10 15 20 25 30 35 40 45 Rain Intensity (in/hr)Flow (gpm)Time (hr)
Wet Weather Event 1 (02/26/14 -02/27/14)
Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 376 of 768
Figure 6.12
Site 8 Calibration
Renz Ln. and Highway 101 On-ramp
Sewer System Master Plan
City of Gilroy
LEGEND
0.0
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Wet Weather Event 1 (02/26/14 -02/27/14)
Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 377 of 768
Figure 6.13
Site 9 Calibration
Behind Nike Outlet off Arroyo Circle
Sewer System Master Plan
City of Gilroy
LEGEND
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Wet Weather Event 1 (02/26/14 -02/27/14)
Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 378 of 768
Figure 6.14
Site 10 Calibration
Welburn Ave. and Church St.
Sewer System Master Plan
City of Gilroy
LEGEND
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Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 379 of 768
Figure 6.15
Site 11 Calibration
Wren Ave. and Mantelli Dr.
Sewer System Master Plan
City of Gilroy
LEGEND
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Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Agenda Item 9.1
Page 380 of 768
March 2023 City of Gilroy
Sewer System Master Plan
APPENDIX C
Joint Trunk Condition Assessment Report
Agenda Item 9.1
Page 381 of 768
City of Morgan Hill Joint Trunk Pipeline Condition Assessment Report - DRAFT
Date: January 2021
Prepared by: Water Works Engineers
Anthony Baltazar, P.E.
Table of Contents
0 Executive Summary ..................................................................................................................................... 4
1 Purpose for Investigation ............................................................................................................................ 7
2 Project Approach/Methodology .................................................................................................................. 7
2.1 Risk Prioritization Methodology .......................................................................................................... 7
2.2 Field Assessment Role in Risk Prioritization ...................................................................................... 13
2.3 City Master Plan Role in Risk Prioritization ....................................................................................... 14
2.4 Location Criteria Forms Role in Risk Prioritization ............................................................................ 14
3 Summary of Field Assessment ................................................................................................................... 15
3.1 Investigation Procedures ................................................................................................................... 15
3.2 Summary of Work Completed ........................................................................................................... 17
3.3 Summary of Findings ......................................................................................................................... 20
4 Summary of Manhole Location Criteria Forms ......................................................................................... 50
5 Summary of City Master Plan .................................................................................................................... 50
5.1 Capital Improvement Projects ........................................................................................................... 50
5.2 Pipe Capacity Rating Data .................................................................................................................. 52
5.3 Flow Volume Rating ........................................................................................................................... 52
6 Risk Prioritization Results .......................................................................................................................... 53
6.1 Probability Rating and Criteria .......................................................................................................... 53
6.2 Consequence Rating and Criteria ...................................................................................................... 57
6.3 Overall Risk Rating ............................................................................................................................. 62
7 Proposed Repair, Rehabilitation, and/or Replacement (RRR) Alternatives .............................................. 68
7.1 Pipelines ............................................................................................................................................ 68
7.2 Manholes ........................................................................................................................................... 74
8 Unit Cost for Each RRR Alternative ............................................................................................................ 75
8.1 Pipelines ............................................................................................................................................ 75
8.2 Manholes ........................................................................................................................................... 76
9 RRR Alternatives Assignment .................................................................................................................... 76
9.1 Pipelines ............................................................................................................................................ 76
9.2 Manholes ........................................................................................................................................... 82
10 Proposed Improvement Project Bundling/Phasing & Analysis ................................................................. 84
10.1 “All-at-Once” Approach ..................................................................................................................... 85
10.2 Phasing Approach .............................................................................................................................. 86
Agenda Item 9.1
Page 382 of 768
11 O&M Recommendations ........................................................................................................................... 86
12 Construction Cost Estimates...................................................................................................................... 86
13 Recommended Project .............................................................................................................................. 87
14 Potential Constraints of Recommended Methodology ............................................................................. 89
14.1 Permits ............................................................................................................................................... 89
14.2 Environmental Considerations .......................................................................................................... 89
14.3 Utility Coordination ........................................................................................................................... 89
15 Appendices ................................................................................................................................................ 90
List of Appendices
15.1 Appendix A – Summary of Pipeline Work Completed
15.2 Appendix B – Pipeline Structural Quick Ratings
15.3 Appendix C – Pipeline Maintenance Quick Ratings
15.4 Appendix D – Pipeline Overall Risk Ratings
15.5 Appendix E – Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 – All-at-Once
15.6 Appendix F – Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 – Phased
15.7 Appendix G – Recommended Emergency/Immediate Projects
15.8 Appendix H – Recommended Intermediate Projects
16.9 Appendix I – Mapbook, Pipeline Inspection Findings
List of Tables
Table 1: Structural/O&M Condition Rating Determination .......................................................................................9
Table 2: Pipe Capacity Rating Determination .......................................................................................................... 10
Table 3: Weighting Factors for Probability Criteria ................................................................................................. 10
Table 4: Probability Rating Determination .............................................................................................................. 10
Table 5: Flow Volume Rating Determination .......................................................................................................... 11
Table 6: Proximity to Waterways Rating Determination ........................................................................................ 12
Table 7: Public Impact Rating Determination .......................................................................................................... 12
Table 8: O&M Access and Safety Rating Determination ......................................................................................... 12
Table 9: Weighting Factors for Consequence Criteria ............................................................................................. 13
Table 10: Consequence Rating Determination ........................................................................................................ 13
Table 11: Abandoned Inspection Summary ............................................................................................................ 17
Table 12: Pipelines Not Inspected ........................................................................................................................... 18
Table 13: Manholes Not MACP Inspected ............................................................................................................... 19
Table 14: Nonexistent Manholes............................................................................................................................. 19
Table 15: Pipelines with Grade 5 Structural Defects ............................................................................................... 21
Table 16: Pipelines with Grade 4 Structural Defects as Highest Severity ............................................................... 21
Table 17: Pipelines with Grade 3 Structural Defects as Highest Severity ............................................................... 21
Table 18: Pipelines with Grade 2 Structural Defects as Highest Severity ............................................................... 22
Table 19: Pipelines with Grade 1 Structural Defects as Highest Severity ............................................................... 24
Table 20: Pipelines with Grade 5 Maintenance Defects ......................................................................................... 26
Table 21: Pipelines with Grade 4 Maintenance Defects as Highest Severity .......................................................... 26
Agenda Item 9.1
Page 383 of 768
Table 22: Pipelines with Grade 3 Maintenance Defects as Highest Severity .......................................................... 26
Table 23: Pipelines with Grade 2 Maintenance Defects as Highest Severity .......................................................... 26
Table 24: Pipelines with Infiltration Defect Observations ....................................................................................... 31
Table 25: Pipelines with Lateral Connections .......................................................................................................... 33
Table 26: Manholes with Grade 5 Structural Defects ............................................................................................. 35
Table 27: Manholes with Grade 4 Structural Defects as Highest Severity .............................................................. 37
Table 28: Manholes with Grade 3 Structural Defects as Highest Severity .............................................................. 37
Table 29: Manholes with Grade 2 Structural Defects as Highest Severity .............................................................. 38
Table 30: Manholes with Grade 1 Structural Defects as Highest Severity .............................................................. 40
Table 31: Manholes with Grade 5 O&M Defects..................................................................................................... 42
Table 32: Manholes with Grade 3 O&M Defects as Highest Severity ..................................................................... 42
Table 33: Manholes with Grade 2 O&M Defects as Highest Severity ..................................................................... 43
Table 34: Manholes with Grade 1 O&M Defects as Highest Severity ..................................................................... 46
Table 35: Manholes with Infiltration Defect Observations ..................................................................................... 46
Table 36: Buried Manholes ...................................................................................................................................... 47
Table 37: City GIS and Field Assessment Findings Discrepancies ............................................................................ 48
Table 38: Probability Rating & Criteria for Inspected Pipelines .............................................................................. 53
Table 39: Probability Rating & Criteria for Pipelines Not Inspected ....................................................................... 57
Table 40: Consequence Rating & Criteria for Inspected Pipelines .......................................................................... 58
Table 41: Consequence Rating & Criteria for Pipelines Not Inspected ................................................................... 62
Table 42: Overall Risk Rating by Rank for Inspected Pipelines ................................................................................ 63
Table 43: Overall Risk Rating by Rank for Pipelines Not Inspected ......................................................................... 67
Table 44: Pipeline RRR Alternatives Assignment ..................................................................................................... 78
Table 45: Pipelines with Structural Defects Requiring Immediate Rehabilitation .................................................. 82
Table 46: Pipelines with I&I Defects Requiring Immediate Rehabilitation ............................................................. 82
Table 47: Manhole RRR Alternatives Assignment ................................................................................................... 82
Table 51: Cost Estimate Comparison ....................................................................................................................... 87
Table 52: Recommended Emergency/Immediate Projects ..................................................................................... 87
Table 53: Recommended Immediate/Intermediate Projects ................................................................................. 88
Agenda Item 9.1
Page 384 of 768
0 Executive Summary
This Condition Assessment Report (Report) was prepared by Water Works Engineers (WWE) on behalf of the City
of Morgan Hill (City) in an effort to summarize the condition assessment performed, and the resultant
recommendation(s), for the JTP sanitary sewer trunk main. After collecting condition assessment data on roughly
61,807 linear feet of trunk main, a review/analysis was performed on the data in conjunction with a capacity
analysis based on the City’s Sewer System Management Plan (SSMP), October 2017. A Risk Prioritization
Methodology was employed for all pipelines to determine their Overall Risk Rating, which is used to determine
the recommended path forward for rehabilitating the trunk main. Multiple Repair, Rehabilitation, and Renewal
(RRR) alternative methodologies (Section 7) were explored as options to address the trunk main’s varying
structural degradation and capacity constraints. In particular, two methodologies were considered as viable for
various components of the overall project: Structural Cured-in-Place-Pipe (CIPP) Lining (Section 7.1.2.2) and Spray
Coating (Section 7.1.2.3). From a constructability standpoint, Microtunneling (Section 7.1.3.3) was considered as
a viable alternative for replacement of the existing line but has a significant cost impact when compared with
other alternatives. Also from a constructability standpoint, Pipe Bursting (Section 7.1.3.2) was considered as a
viable alternative for replacement of the existing line but is considered infeasible due to the structurally degraded
portions of the JTP trunk main being reinforced concrete pipe material. By analyzing these alternative
methodologies side-by-side with the viable capacity projects from the City’s SSMP, two project
bundles/approaches (Section 10) were formed with an emphasis on risk reduction, feasibility/constructability,
consistent and accurate cost estimating taking into account identified project constraints, and cost efficiencies.
The results of the condition assessment analysis formed the basis for recommending rehabilitation for the
reinforced concrete pipe segments along the trunk main. The Overall Risk Rating for each pipeline was determined
on a scale of 1 to 5, with 1 being a relatively low risk and 5 being a high risk of failure. A majority of the trunk main
pipelines have Overall Risk Ratings of 5 or 4. The following summarizes the number of pipelines that fall under
each value for the Overall Risk Rating.
Table i: Executive Summary Overall Risk Rating Summary
Overall Risk Rating Number of Pipelines
5 57
4 30
3 35
2 38
1 8
Two alternatives were developed and analyzed. These included improvements to address existing and future
buildout planning horizon capacity related problems identified in the SSMP(i.e. capacity improvement projects JT-
P2 through JT-P9) combined with improvements required to address emergency (0-2 year), immediate (2-5 year)
and intermediate (2-15 year) condition deficiencies identified during the project field work. An intermediate
project to address significant existing structural deficiencies is recommended be constructed within the next 2-
Agenda Item 9.1
Page 385 of 768
years. To address the remainder of the capacity and condition deficiencies, two phasing approaches were
analyzed.
“All-at-Once” assumed all of the condition deficiencies and existing and future buildout planning horizon capacity
deficiencies (i.e. JT-P2 through JT-P9) would be constructed within a 5-year period as a single
immediate/intermediate project.
“Phased” assumed all of the condition deficiencies and existing and future buildout planning horizon capacity
deficiencies (i.e. JT-P2 through JT-P9) would be constructed over a 5 to 15-year period as a multi-phased
intermediate project. This approach required additional emergency/immediate improvements (i.e. crown
spraying of lines with capacity deficiencies that are being phased).
The following summarizes the cost estimate for each by project bundle.
Table ii: Executive Summary Project Alternatives Cost Estimate Summary
Approach Project Bundle Emergency /
Immediate Project
Immediate /
Intermediate Project
Total Project Cost*
All-at-
Once
Structural CIPP Lining
& JT-P2 through JT-P9
(Appendix E)
$0.84 Million
(0-2 years)
$32.8 Million
(2-5 years)
$47.1 Million
Phased
Structural CIPP Lining
& JT-P2 through JT-P9
(Appendix F)
$1.1 Million
(0-2 years)
$28.3 Million
(2-5 years)
$5.8 Million
(5-15 years)
$47.8 Million
*All presented 2021 dollars rounded to the nearest $100,000, including design and construction contingencies.
The recommended project bundle for the JTP trunk main is summarized below. It should be noted that the
recommendation for completing the capacity improvement projects JT-P2 through JT-P9 is based on the results
of the SSMP. The capacity project’s efficacy should be confirmed through flow monitoring during the design phase
to verify the proposed pipe diameters.
Structural CIPP Lining & JT-P2 through JT-P9 – All-at-Once
The “Emergency/Immediate Projects” (0-2 years) include the following:
• Structural CIPP lining and/or open cut replacement of the pipelines found to be in need of point repairs
(see Appendix G)
• Manhole RRR activities (as discussed in Section 9.2)
The “Intermediate Projects” (2-5 years) include the following:
• Structural CIPP lining of all assigned pipelines (see Section 9.1 and Appendix H)
• Capacity Improvement Projects JT-P2 through JT-P9
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This project bundle assumes the City is able to obtain the necessary funding to perform the various projects within
5 years (exclusive of engineering design and permitting, which is assumed to be 1 year), with anticipated
substantial completion of all improvements in 2027. The “Emergency/Immediate Projects” are recommended to
be completed by Year 2, with the “Intermediate Projects’ recommended to be completed by Year 5. The Total
Construction Cost Opinion for this project bundle is $47.1 Million. However, if the City is unable to take this
approach, a “Phased” approach has also been explored in this Report (see Section 10.2). While more expensive
overall than the project bundle explained above, this approach allows the City to “space out” the requisite funding
over a span of about 15 years.
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1 Purpose for Investigation
The City aims to complete cyclical condition assessment(s) of its wastewater collection assets by identifying system
deficiencies, developing rehabilitation and replacement recommendations to repair those deficiencies, and create
a prioritized capital program to construct the improvements. The City’s Joint Trunk Pipeline (JTP) conveys
wastewater from a large portion of the City’s collection system infrastructure, and eventually discharges its flow
to the South County Regional Wastewater Authority (SCRWA) Wastewater Treatment Plant (WWTP). The JTP
starts near the intersection of Monterey Rd and California Ave, turning west and then south along Harding Ave,
through various agricultural fields in San Martin, through the City of Gilroy, and terminating at the SCRWA WWTP.
The goal of the condition assessment project is to inspect the trunk sewer main to determine its physical condition
and determine if there are structural and/or maintenance deficiencies that require repair, rehabilitation,
replacement and/or O&M enhancements to maintain level of service consistent with City requirements. Once/if
pipelines are identified as having structural and/or maintenance deficiencies, they are evaluated to determine the
appropriate renewal/maintenance activity to address the issue(s) and lessen the potential risk of failure. Pipeline
renewal denotes any activity that is taken to renew or increase the serviceable life of an asset. Pipeline renewal
can be accomplished in various ways, including repair (i.e. localized repair of individual defects that affect a small
portion of the overall line segment), rehabilitation (i.e. activities that address defects along the entire line segment
but leave the host pipe in place), and replacement (i.e. activities that replace the defective line segment with an
entirely new pipeline). Maintenance activities aim to improve operation and knowledge of the sewer trunk main
and allow the City to better maintain the sewer infrastructure through activities like periodic cleaning.
Maintenance activities can encompass various methods such as heavy cleaning (i.e. remove debris/dirt from
pertinent line segments), closed-circuit television (CCTV) inspection (i.e. CCTV of line segments not completed as
part of this project), and adding access (i.e. adding manholes to portions of the alignment to allow for future
access).
This Report contains a summary of the results of the condition assessment performed and the engineering analysis
WWE utilized to determine the preferred methodology for the rehabilitation of the JTP wastewater trunk main.
Each pipeline segment is prioritized by need for repair, rehabilitation, and/or replacement (RRR) based on a risk
prioritization methodology, which is explained in more detail in Section 2 below.
2 Project Approach/Methodology
2.1 Risk Prioritization Methodology
The risk prioritization methodology utilized by WWE produces an Overall Risk Rating for each pipeline segment
that can then be used to rank each asset in order of their calculated risk of failure. The Overall Risk Rating is
determined using two separate ratings: Probability Rating and Consequence Rating. Figure 1 below shows the
Risk Rating Matrix used to determine the Overall Risk Rating. The orange box with a thick black outline denotes a
pipeline that has a Probability Rating of 4 and a Consequence Rating of 3, resulting in an Overall Risk Rating of 4
as shown in the legend. In general, pipelines with a high probability of failure represent a higher risk. The risk
associated with pipelines that have serious consequences of failure can be mitigated if the probability of failure is
low.
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Figure 1: Risk Rating Matrix
2.1.1 Probability Rating
The Probability Rating is based on three criteria:
• Structural Condition Rating
• O&M Condition Rating
• Pipe Capacity Rating
2.1.1.1 Structural Condition Rating
The Structural Condition Rating is based on the structural observations obtained during the CCTV inspections.
Each observation (e.g. cracks, fractures, breaks, holes, etc.) is assigned an individual defect grade ranging from 1
to 5, with 5 being the most severe. These structural observations are used to calculate the pipeline’s Total
Structural Score. The Total Structural Score for a pipeline is calculated through the summation of three terms, as
described below:
• The highest structural observation defect grade multiplied by 100.
• The sum of the structural observation defect grades.
• The average structural observation defect grade per unit length of the pipeline multiplied by 100.
The resultant Total Structural Score is then used to determine the pipeline’s Structural Condition Rating, as shown
in Table 1 below.
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Table 1: Structural/O&M Condition Rating Determination
Total Structural/O&M Score Structural/O&M Condition Rating
< 150 1
150 – 249.9 2
250 – 349.9 3
350 – 449.9 4
> 450 5
For example, assume a pipeline that is 438.9 feet in length has a high structural observation defect grade of 3.
Also assume the sum of its structural observation defect grades is 43. The pipeline’s Total Structural Score would
be calculated as follows:
• (3 x 100) = 300
• 43
• 100 x (43 / 438.9) = 9.797
o Total Structural Score = 300 + 43 + 9.797 = 352.797
This pipeline’s Total Structural Score would then be rounded up to the nearest whole number (i.e. 353). As Table
1 shows, the pipeline’s Structural Condition Rating would be 4.
2.1.1.2 O&M Condition Rating
The O&M Condition Rating is determined exactly the same way as the Structural Condition Rating, except the
O&M observation data for the pipeline is used instead. For the same pipeline described above, assume the highest
O&M observation defect grade is 2 and the sum of its O&M observation defect grades is 23. The pipeline’s Total
O&M Score would be calculated as follows:
• (2 x 100) = 200
• 23
• 100 x (23 / 438.9) = 5.24
o Total O&M Score = 200 + 23 + 5.24 = 228.24
This pipeline’s Total O&M Score would then be rounded up to the nearest whole number (i.e. 229). As Table 1
shows, the pipeline’s O&M Condition Rating would be 2.
2.1.1.3 Pipe Capacity Rating
The Pipe Capacity Rating is based on the pipeline’s depth-to-diameter (d/D) value during existing peak wet
weather flow (PWWF) conditions. The City’s hydraulic modeling results for the existing peak wet weather flow
scenario are utilized for determining each pipeline’s d/D value. A pipeline’s Pipe Capacity Rating is determined
according to Table 2 below.
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Table 2: Pipe Capacity Rating Determination
d/D Value Pipe Capacity Rating
< 0.60 1
0.60 – 0.6999 2
0.70 – 0.7499 3
0.75 – 0.90 4
> 0.90 5
Pipelines that are flowing at or near hydraulic capacity are more likely to cause a sanitary sewer overflow (SSO) in
the case of a total or partial blockage or structural failure. For the same pipeline previously described, assume its
d/D value is 0.65 under the “Existing PWWF” modeling scenario. As Table 2 shows, the pipeline’s Pipe Capacity
Rating would be 2.
2.1.1.4 Total Probability Score
The Total Probability Score for a given pipeline is the summation of the three probability criteria after each
criterion has been multiplied by their associated weighting factor. Table 3 below summarizes the weighting
factors for all three of the probability criteria.
Table 3: Weighting Factors for Probability Criteria
Probability Criteria Weighting Factor
Structural Condition Rating 5
Pipe Capacity Rating 3
O&M Condition Rating 2
Continuing with the same pipeline from above, its Total Probability Score would be calculated as follows:
• (Structural Condition Rating = 4) x (Weighting Factor = 5) = 20
• (Pipe Capacity Rating = 2) x (Weighting Factor = 3) = 6
• (O&M Condition Rating = 2) x (Weighting Factor = 2) = 4
o Total Probability Score = 20 + 6 + 4 = 30
The Total Probability Score is then translated into the Probability Rating according to Table 4 below.
Table 4: Probability Rating Determination
Total Probability Score Probability Rating
10 – 16 1
17 – 24 2
25 – 32 3
33 – 40 4
41 – 50 5
Therefore, the hypothetical pipeline’s Total Probability Score of 30 translates to a Probability Rating of 3.
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2.1.2 Consequence Rating
The Consequence Rating is based on four criteria:
• Flow Volume Rating
• Proximity to Waterways Rating
• Public Impact Rating
• O&M Access and Safety Rating
2.1.2.1 Flow Volume Rating
The Flow Volume Rating is based on the pipeline’s maximum flow volume during current PWWF conditions. Each
pipeline’s maximum flow value is taken from the City’s hydraulic modeling results for the “Existing PWWF”
scenario. In the absence of model results, the pipeline’s existing diameter will be used instead. The probability of
failure (i.e. SSO) is not more likely in a pipeline solely because it conveys more flow volume than another.
However, a failure in a pipeline with larger flow volumes will result in more damages, higher cleanup costs, and is
more likely to cause Category 1 SSOs. A pipeline’s Flow Volume Rating is determined according to Table 5 below.
Table 5: Flow Volume Rating Determination
Flow Volume (MGD) Pipe Diameter (in) Flow Volume Rating
< 0.25 < 10 1
0.25 – 1.05 10 – 13 2
1.05 – 3.15 14 – 23 3
3.15 – 7.20 24 – 35 4
> 7.20 > 35 5
Assuming the same hypothetical pipeline had a maximum flow volume of 1.75 MGD, its corresponding Flow
Volume Rating would be 3.
2.1.2.2 Proximity to Waterways Rating
The Proximity to Waterways Rating is based on the distance from the pipeline’s US manhole to drainages (i.e. to
storm drain inlets and/or waterways). A major focus of the California State Water Resources Control Board’s
General Waste Discharge Requirements is to reduce the occurrence of SSOs, particularly SSOs that affect
waterways of the United States. Any sewage spill to a waterway immediately becomes a Category 1 SSO, and is
likely to draw fines or other enforcement action for the responsible agency. Therefore, proximity of assets to
waterways is another significant factor in the criticality of failure. A pipeline’s Proximity to Waterways Rating is
determined according to Table 6 below.
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Table 6: Proximity to Waterways Rating Determination
Location – Proximity to Waterways Proximity to Waterways Rating
US SSMH > 2500 ft to waterway 1
US SSMH > 2500 ft to waterway & < 500 ft to storm drain inlet 2
US SSMH < 2500 ft to waterway 3
US SSMH < 2500 ft to waterway & < 500 ft to storm drain inlet 4
US SSMH < 1000 ft to waterway 5
Assuming the same hypothetical pipeline is less than 2500 feet from the nearest waterway and less than 500 feet
from the nearest storm drain inlet, its corresponding Proximity to Waterways Rating would be 4.
2.1.2.3 Public Impact Rating
The Public Impact Rating is based on the distance from the pipeline to public areas such as farms, parks, schools,
hospitals, and other densely populated locations. A pipeline’s Public Impact Rating is determined according to
Table 7 below.
Table 7: Public Impact Rating Determination
Location – Public Impact Public Impact Rating
> 1000 feet from public facilities, limited public traffic, limited
economic impact 1
Within 1000 feet of public facilities, moderate public traffic,
moderate economic impact 3
Within 100 feet of public facilities, significant public traffic, significant
economic impact, high construction cost 5
Assuming the same hypothetical pipeline is within 1000 feet of an elementary school, its corresponding Public
Impact Rating would be 3.
2.1.2.4 O&M Access and Safety Rating
The O&M Access and Safety Rating is based on the ability to access the pipeline for O&M or repair work as well as
the ability for O&M staff or contractors to safely perform the work. A pipeline’s Public Impact Rating is determined
according to Table 8 below.
Table 8: O&M Access and Safety Rating Determination
Location – O&M Access and Safety O&M Access and Safety Rating
In roadway, residential street 1
In roadway, arterial roadway 2
Not in roadway, can access with truck 3
Not in roadway, must walk equipment to site 4
Not in roadway, no safe working area, under buildings 5
Assuming the same hypothetical pipeline is in an arterial roadway, its corresponding O&M Access and Safety
Rating would be 2.
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2.1.2.5 Total Consequence Score
The Total Consequence Score for a given pipeline is the summation of the four consequence criteria after each
criterion has been multiplied by their associated weighting factor. Table 9 below summarizes the weighting factors
for all four of the consequence criteria.
Table 9: Weighting Factors for Consequence Criteria
Consequence Criteria Weighting Factor
Flow Volume Rating 4
Proximity to Waterway Rating 3
Public Impact Rating 2
O&M Access and Safety 1
Continuing with the same pipeline from above, its Total Consequence Score would be calculated as follows:
• (Flow Volume Rating = 3) x (Weighting Factor = 4) = 12
• (Proximity to Waterway Rating = 4) x (Weighting Factor = 3) = 12
• (Public Impact Rating = 3) x (Weighting Factor = 2) = 6
• (O&M Access and Safety = 2) x (Weighting Factor = 1) = 2
o Total Consequence Score = 12 + 12 + 6 + 2 = 32
The Total Consequence Score is then translated into the Consequence Rating according to Table 10 below.
Table 10: Consequence Rating Determination
Total Consequence Score Consequence Rating
10 – 16 1
17 – 24 2
25 – 32 3
33 – 40 4
41 – 50 5
Therefore, the hypothetical pipeline’s Total Consequence Score of 32 translates to a Consequence Rating of 3.
This pipeline’s Consequence Rating of 3 and Probability Rating of 3 equates to an Overall Risk Rating of 3 according
to Figure 1.
The following sections discuss how the aforementioned criteria are collected for their use in the risk prioritization
methodology.
2.2 Field Assessment Role in Risk Prioritization
During the field assessment of the JTP, data for two of the criteria are collected. The CCTV inspections provide
the structural and O&M defect observations that are used to determine the Structural Condition Rating and the
O&M Condition Rating of each pipeline. The inspections also provide the diameter of each pipeline, which is used
to determine the Flow Volume Rating in the absence of maximum flow volume data from the model results. The
procedures of the CCTV inspections are discussed in more detail in Section 3.1 below.
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2.3 City Master Plan Role in Risk Prioritization
The City’s Sewer System Master Plan contains a capacity assessment that provides the information needed to
determine the Pipe Capacity Rating and Flow Volume Rating for the pipelines. Specifically, the model scenario
titled “Existing PWWF” was utilized to determine the d/D values needed for the Pipe Capacity Rating and the
maximum flow values needed for the Flow Volume Rating. It should be noted that Ultimate Buildout PWWF values
contained in the Master Plan are projected to be higher than existing values. However, when assessing an
individual pipe’s risk of failure as it pertains to this Report, the pipe’s current conditions are utilized so as to not
overestimate the asset’s probability/consequence of failure should future conditions be used. A more detailed
discussion of the City’s Master Plan can be found in Section 5 below.
2.4 Location Criteria Forms Role in Risk Prioritization
Location Criteria Forms filled out during the field assessment provide the information needed to determine the
Proximity to Waterways Rating, Public Impact Rating, and O&M Access and Safety Rating. A more detailed
discussion of the Location Criteria Forms can be found in Section 4 below.
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3 Summary of Field Assessment
3.1 Investigation Procedures
3.1.1 Pipelines
Water Works Engineers (WWE) was retained to coordinate the inspection efforts and conduct the condition
assessment of the JTP wastewater trunk main . WWE teamed with Professional Pipe Services (Pro-Pipe), a division
of Hoffman Southwest Corporation, to perform the cleaning and CCTV inspection of the identified sewer trunk
main. Cleaning and inspection work began on October 12th, 2019 and continued until March 2020, at which time
Santa Clara County issued a Shelter in Place Order due to public health concerns regarding COVID-19. While a
majority of the pipeline inspection work was completed in this timeframe, the remaining pipeline work was
completed in October 2020. Due to the location of the JTP along farmland and roads with regular traffic, as well
as higher wastewater flows during the day, virtually all cleaning and inspection work was conducted at night.
Various methods of flow control were utilized along the JTP trunk main to provide a larger view of the pipeline
segments by lowering water level in the inspected segment. The “plug and release” method was utilized whereby
a plug was inserted to completely stop flow while crew members monitored upstream surcharging to ensure no
spills occurred. Another method utilized in pipe segments with larger amounts of flow involved inserting “flow-
through” plugs, which allow much smaller amounts of wastewater flow to pass through and into the pipe segment
being inspected.
Cleaning activities were conducted with a Vac-Con Recycler combination sewer cleaner to perform high-
velocity/vacuum cleaning (HVVC) of the sewer trunk pipeline segments before CCTV inspections were completed.
The Recycler machine allows for the reuse of water in the debris tank for cleaning purposes, leading to reduction
in occurrences of tank refilling during working hours and increased efficiency. Cleaning of the sewer trunk
pipelines was conducted before inspections to:
1) Increase the probability that the CCTV camera would be able to traverse the pipeline and not be slowed
or stopped by debris so a complete inspection could be performed; and
2) Provide the CCTV camera an unobstructed view of the pipeline interior so that structural defects (e.g.
cracks, fractures) could be assessed.
This method may limit the ability of the assessment to document maintenance related problems (e.g. debris,
grease, roots) since pre-cleaning by design has the potential to remove or reduce some of these potential
deficiencies. However, assessing the structural condition of the pipeline was prioritized above the maintenance
condition for this project because it was assumed that the pipes were more likely to fail due to a structural issue
than a blockage since the pipelines were to be cleaned as part of this project.
CCTV inspections were conducted using the IBAK Panoramo scanner technology. The IBAK Panoramo 3D
Optoscanner incorporates the use of two high-resolution digital cameras in the front and rear sections of the
housing, with 185° wide-angle lenses and parallel-mounted xenon flashlights capable of 360° spherical images.
The Panoramo system captures 100% of the pipeline interior and is delivered with a virtual 3D reader that enables
the reviewer to see the entire pipe interior from any angle. Additionally, the virtual 3D reader provides a flat-view
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component that enables the reviewer to make accurate measurements of features/observations and to more
easily assess the changes in observations along the pipeline to identify trends. Hyperlinks to the inspection files
were included in an ESRI GIS shapefile of the inspected pipelines so the virtual 3D reader could be opened for a
specific pipeline from a map environment for easy access.
Observations and defects were collected during the inspection work and coded using the National Association of
Sewer Service Companies (NASSCO) Pipeline Assessment and Certification Program (PACP) standards. Version 7.0
of the PACP Reference Manual was used for coding. The intent of the NASSCO PACP is to provide a means to
accurately assess underground infrastructure using tools and procedures that can serve as a national standard. A
benefit of the NASSCO PACP is it includes a Condition Grading System that provides pipe ratings to quantitatively
describe the condition of a pipeline that can be used to compare it to ratings of other pipelines. The PACP Quick
Rating uses a four-character alphanumeric score based on the number of defects with the highest severity grade
and the number of defects of the next highest severity grade for a given pipeline. Quick Ratings for both structural
and maintenance conditions were applied to all of the pipelines inspected as part of this project. Quick Ratings
are formulated as follows:
1. The first character is the highest severity grade occurring along the pipe segment.
2. The second character is the total number of occurrences of that highest severity grade. If the total number
is greater than 9, then alphabetic characters are assigned as follows: A – 10-14; B – 15-19; C – 20-24; etc.
3. The third character is the next highest severity grade occurring along the pipe segment.
4. The fourth character is the total number of occurrences of the severity grade derived in Step 3 above.
This follows the same rules as the character is Step 2.
WWE reviewed each pipeline inspected as part of this project, with particular attention to pipelines that had Quick
Ratings (Structural and Maintenance) indicating PACP Grade 5 and Grade 4 defects. WWE evaluated potential
renewal/maintenance activities for each pipeline so that no pipeline inspected as part of this project will have
defect(s) more severe than a Grade 3 once the activities are completed. The findings from the condition
assessment and a discussion of the potential renewal/maintenance activities can be found below in Section 3.3.1
and Section 7.1, respectively.
3.1.2 Manholes
Manhole inspection work began on March 4th, 2020 and continued until March 18th, 2020. As was the case for
the pipeline inspection work, Santa Clara County issued a Shelter in Place Order due to public health concerns
regarding COVID-19. Similar to the pipeline work, manhole inspections were conducted at night.
CCTV manhole inspections were conducted using the IBAK Panoramo Si 3D Optical Manhole Scanner. The Si
captures 100% of the entire manhole cavity for review in a virtual 3D reader, which can be utilized in flat-view for
measuring inverts, defects, etc. It also has the capability to be exported as a point cloud into AutoCAD. Hyperlinks
to the inspection files were included in an ESRI GIS shapefile of the inspected manholes so the virtual 3D reader
could be opened for a specific manhole from a map environment for easy access.
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Observations and defects were collected during the inspection work and coded using the NASSCO Manhole
Assessment and Certification Program (MACP) standards. Level 2 MACP coding was performed using Version 7.0
of the PACP Reference Manual. Many of the defects found in pipelines are also found in manholes, therefore
PACP defect codes are used where applicable for the Level 2 MACP inspections.
WWE reviewed each manhole inspected as part of this project, with particular attention to manholes that had
Structural Quick Ratings indicating Grade 5 and Grade 4 defects. WWE evaluated potential renewal activities for
each manhole so that no manhole inspected as part of this project will have defect(s) more severe than a Grade
3 once the activities are completed. The findings from the condition assessment and a discussion of the potential
renewal activities are found below in Section 0 and Section 7.2, respectively.
3.2 Summary of Work Completed
3.2.1 Pipeline Cleaning/Inspection
The JTP trunk main consists of approximately 62,006 linear feet of sewer pipe as it pertains to this project.
Cleaning was performed on each pipeline prior to commencement of CCTV inspection, which were performed on
almost every pipe segment along the trunk main (i.e. 61,807 LF, or 99%, of trunk main was inspected). It is the
opinion of the WWE that there is sufficient inspection data to warrant the recommendation of projects to address
the deteriorating condition of certain portions of the JTP trunk main.
The following CCTV inspections were abandoned due to the stated reasoning provided in Table 11 below.
• MH-116_MH-116A: The entirety of this pipeline was able to be inspected by performing a reverse
inspection from the opposite direction until the same joint seal was reached.
• MH-155_MH_156: As the last pipeline along the trunk main, the water level during the time of inspection
was too high for a complete CCTV inspection to be performed.
Table 11: Abandoned Inspection Summary
Date Pipeline Facility ID US Manhole DS Manhole Cleaning? Reason for
Abandonment
12/10/2019 MH-116_MH-116A MH-116 MH-116A YES
Joint Seal Blocking
Path
(reverse setup
completed total
pipe inspection
length)
01/16/2020 MH-155_MH-156 MH-155 MH-156 YES
Camera Underwater
(missing
approximately 163
LF of estimated
263LF of total
pipeline length due
to excessive water
level)
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Table 12 below summarizes the three siphon pipelines (on Wren Ave, north of La Primavera Way) that were not
inspected during the field assessment. A brief explanation of why the pipe segments were unable to be inspected
is described in Table 12, with a more detailed explanation of what was performed provided below.
• Pro-Pipe set up the bypass pumping system, with the intent to install a flow-through plug at MH-90 and
connect the bypass pump to the plug in order to reroute the sewage around the siphon pipe segments.
Cleaning was then to be performed on both siphon barrels before eventually running the CCTV camera
through the barrels in a relatively dry condition.
• Pro-Pipe rented a variety of flow-through plugs with the recognition that getting a 24” plug into these
relatively small manholes was going to be difficult, especially given the configuration of the siphon inlet.
The bypass pump manufacturer recommended that the connection size of the flow-through portion of
the plug be 8” in diameter to achieve full capacity, however the 24”/8” flow-through plug was very rigid
and the manholes are not big enough to get the plug into the line. Pro-Pipe was able to get a 6” flow-
through plug into the line, however the bypass operation was limited by the smaller diameter pipe and
the system started to surcharge, thereby not allowing sufficient time to complete the CCTV inspection
before Pro-Pipe was forced to remove the plug entirely.
• Pro-Pipe was able to clean both the 12” and 18” siphon barrels, and while doing so were able to visually
inspect the siphon inlet manhole configuration where the two barrels split. Roughly 85% of the
wastewater flow and almost all of the debris was going through the lower 12” barrel, which had significant
levels of debris that Pro-Pipe was able to remove with multiple cleaning passes. The 18” barrel inlet is
configured at a higher elevation than the 12” barrel, thereby resulting in a lower amount of flow (~15%)
and very little debris. Pro-Pipe was able to successfully clean and remove the debris in the 18” barrel.
• Pro-Pipe also found during the visual inspection that there was no indication of pipe degradation at the
pipe inlets. Refer to Section 11.2 later in this report for WWE’s recommendation(s) regarding the siphon
barrel pipe segments.
Table 12: Pipelines Not Inspected
Pipeline
Facility ID
US Manhole
(USMH)
DS Manhole
(DSMH)
Length
(ft)* Reason for No Inspection
MH-90_MH-91 MH-90 MH-91 47 Due to the relatively small size of the
manhole openings, the flow-through plug
with sufficient capacity to allow for CCTV
inspection was unable to be installed.
The largest flow-through plug that was
successfully installed was unable to
convey enough bypassed flow, resulting
in the upstream system surcharging too
quickly to allow for inspection.
MH-91_MH-92 MH-91 MH-92 99
MH-92_MH-93 MH-92 MH-93 56
*Total length of pipe segment based on estimated GIS lengths
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3.2.2 Manhole Inspection
There are a total of 169 manholes along the JTP trunk main, of which 150 (88.7%) were MACP inspected. Table
13 below summarizes the manholes that were not inspected as part of this project. The reasoning behind the
inability to inspect each manhole is also provided.
Table 13: Manholes Not MACP Inspected
Manhole Facility ID Reason for No MACP Inspection
MH-66 Unable to locate
MH-71 Unable to safely access in garlic fields without crop
damage
MH-72 Unable to safely access in garlic fields without crop
damage
MH-85 Unable to confirm exact manhole
MH-91 Intermediate siphon manhole, unable to inspect
MH-92 Intermediate siphon manhole, unable to inspect
MH-127 Unable to locate under grass/landscaping
MH-128 Unable to locate under grass/landscaping
MH-137 Unable to locate manhole
MH-138 Unable to locate manhole
MH-138A Unable to locate manhole, potentially paved over
MH-142A Unable to locate manhole, under gravel road
MH-142B Unable to locate manhole, under gravel road
MH-151 Unable to access locked cover
MH-152 Unable to access locked cover
MH-153 Unable to access locked cover
MH-154 Unable to access locked cover
MH-155 Unable to access locked cover
MH-156 Unable to access locked cover
The manholes listed below in Table 14 seemingly do not exist after the inspection work was completed and
reviewed, even though they were initially included in the City’s original system GIS data. A description of the
location where each manhole was originally believed to exist is also provided.
Table 14: Nonexistent Manholes
Nonexistent Manhole Facility ID Original Location Description
MH-45 On Harding Ave north of intersection of Highland Ave
and Harding Ave
MH-49 On Highland Ave west of intersection of Highland Ave
and Harding Ave
MH-124 Grass Area west of Arroyo Cir near Hometown Buffet
(7950 Arroyo Cir, Gilroy, CA 95020)
MH-129 Grass area west of Arroyo Cir near Kaiser Medical
Center (7520 Arroyo Cir, Gilroy, CA 95020)
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3.3 Summary of Findings
This section reviews the findings of the inspection work and subsequent condition assessment. The section is
broken down into four further sections. The first section reviews the structural/O&M/construction observations
found during the pipeline inspections, while the second section reviews the structural/O&M observations found
during the manhole inspections. The third section reviews the manholes that were unable to be found during the
inspections and are thought to be buried (i.e. under grass/landscaping, gravel, road, etc.). The fourth section
reviews differences along the alignment between the City’s GIS and field assessment findings.
3.3.1 Pipeline Inspection Findings
This section provides a summary of the pipeline observations made during the inspection phase. As previously
explained in Section 2.1.1, these pipeline observations are used in the risk prioritization methodology. Figures
summarizing the Structural Quick Rating and O&M Quick Rating for each pipeline inspected as part of this project
are included in Appendix B and Appendix C, respectively. See Table 38 and Table 39 in Section 6 for the pipelines’
Structural and O&M Condition Ratings. A more detailed view of the pipeline inspections performed and the defect
observations found during the field assessment can be found in Appendix I in Section 15.9.
3.3.1.1 Structural Observations
The structural defect codes listed in the tables below are the PACP codes applied to the observed structural
defects. The number in parentheses indicates the number of occurrences of that code. There may also be
continuous stretches of the codes, which will have the linear footage indicated. A condensed list of codes and
their associated descriptions is provided below. The tables are sorted on the Structural Quick Rating column so
the pipelines with the largest count of the highest severity defects are listed in descending order from the top of
the table. Refer to the PACP Reference Manual Version 7.0 for additional detailed information about these and
other PACP codes.
• SMW – Missing Wall (Grade 5)
• SRP – Reinforcement Projecting (Grade 5)
• SRV – Reinforcement Visible (Grade 4)
• SAM – Aggregate Missing (Grade 4)
• FM – Fractures, Multiple (Grade 4)
• SAP – Aggregate Projecting (Grade 3)
• FL – Fracture, Longitudinal (Grade 3)
• FS – Fracture, Spiral (Grade 3)
• CM – Cracks, Multiple (Grade 3)
• JAM – Joint Angular Medium (Grade 3)
• CL – Crack Longitudinal (Grade 2)
• CS – Crack Spiral (Grade 2)
• FC – Fracture Circumferential (Grade 2)
• SAV – Aggregate Visible (Grade 2)
• SSS – Surface Spalling (Grade 2)
• CC – Crack Circumferential (Grade 1)
• SRI – Roughness Increased (Grade 1)
• SSC – Spalling of Coating (Grade 1)
It should be noted that the linear footage provided for the continuous stretches of a defect might be the total sum
of multiple continuous stretches along the pipe segment. For example, a single pipe segment may have 2 separate
10-foot stretches of continuous Spiral Fractures (FS) that would be described as having 20 feet of this particular
defect.
Agenda Item 9.1
Page 401 of 768
Table 15 below lists the pipelines along the JTP trunk main that have a Grade 5 structural defect. These pipelines
are shown as red pipelines in Appendix B.
Table 15: Pipelines with Grade 5 Structural Defects
Pipeline Facility ID Structural Quick Rating Most Severe PACP Observations
MH-116_MH-116A 544B (1) SMW, (1) SRP, 10 LF of continuous SMW
Table 16 lists the pipelines that have a Grade 4 defect as the most severe structural defect on the line. These
pipelines are shown as orange pipelines in Appendix B.
Table 16: Pipelines with Grade 4 Structural Defects as Highest Severity
Pipeline Facility ID Structural Quick Rating Most Severe PACP Observations
MH-60_MH-61 4331 16 LF of continuous FM
MH-135_MH-136 422R (1) SRV, (1) SAM
MH-142B_MH-142C 4138 (1) FM
MH-143_MH-144 4132 (1) FM
Table 17 lists the pipelines that have a Grade 3 defect as the most severe structural defect on the line. These
pipelines are shown as yellow pipelines in Appendix B.
Table 17: Pipelines with Grade 3 Structural Defects as Highest Severity
Pipeline Facility ID Structural Quick Rating Most Severe PACP Observations
MH-142F_MH-143 372Z (4) CM, (3) SAP
MH-116A_MH-117 372E (1) SAP, 28 LF of continuous SAP
MH-147_MH-148 352M (3) SAP, (2) CM
MH-139_MH-140 342Z (3) CM, (1) FL
MH-142C_MH-142D 342N (4) FL
MH-153_MH-154 342L (3) SAP, (1) FL
MH-59_MH-60 3411 (4) FL
MH-151_MH-152 332Z (2) CM, (1) SAP
MH-117_MH-118 332G (3) SAP
MH-137_MH-138 332D (1) SAP, 10 LF of continuous SAP
MH-142A_MH-142B 332C (2) FL, (1) CM
MH-53_MH-54 3321 (1) CM, (1) FL, (1) FS
MH-131_MH-132 322Z (2) SAP
MH-126_MH-127 322S (2) CM
MH-142E_MH-142F 322L (2) CM
MH-110_MH-111 322G (1) FL, (1) CM
Agenda Item 9.1
Page 402 of 768
Pipeline Facility ID Structural Quick Rating Most Severe PACP Observations
MH-146_MH-147 322G (1) CM, (1) SAP
MH-145_MH-146 322C (1) FL, (1) SAP
MH-7_MH-9 3225 (1) CM, (1) JAM
MH-100_MH-101 312O (1) FS
MH-152_MH-153 312N (1) SAP
MH-97A_MH-98 312L (1) FL
MH-112_MH-113 312L (1) CM
MH-142D_MH-142E 312L (1) CM
MH-88_MH-89 312K (1) FS
MH-95_MH-96 312F (1) CM
MH-138_MH-138A 312F (1) SAP
MH-113_MH-114 312I (1) CM
MH-149_MH-150 312B (1) SAP
MH-32_MH-33 3127 (1) FL
MH-3_MH-5 3126 (1) FS
MH-5_MH-7 3126 (1) FS
MH-16_MH-18 3126 (1) JAM
MH-44_MH-48 3125 (1) FL
MH-70_MH-71 3124 (1) FL
MH-24_MH-26 3122 (1) CM
MH-21_MH-21A 3121 (1) FS
MH-61_MH-62 3100 (1) FL
Table 18 lists the pipelines that have a Grade 2 defect as the most severe structural defect on the line. These
pipelines are shown as blue pipelines in Appendix B.
Table 18: Pipelines with Grade 2 Structural Defects as Highest Severity
Pipeline Facility ID Structural Quick Rating Most Severe PACP Observations
MH-140_MH-141 2Z1V (10) CL, (3) SAV, (1) CC, 850 LF of continuous SAV
MH-128_MH-130 2Y1U (10) CL, (2) CS, (1) SAV, (1) SSS, 586 LF of
continuous SAV
MH-150_MH-151 2X1W (7) CL , (2) SAV, 595 LF of continuous SAV
MH-107_MH-108 2W1U (2) CL, (1) SAV, 585 LF of continuous SAV
MH-125_MH-126 2T1O (5) CL, (1) CS, (1) FC, (1) SAV, 486 LF of
continuous SAV
MH-106_MH-107 2T13 532 LF of continuous SAV
MH-105_MH-106 2S1R (3) CL, (1) FC, (1) SAV, 479 LF of continuous SAV
MH-111_MH-112 2R12 490 LF of continuous SAV
MH-133_MH-134 2Q1R (2) SAV, 458 LF of continuous SAV
Agenda Item 9.1
Page 403 of 768
Pipeline Facility ID Structural Quick Rating Most Severe PACP Observations
MH-115_MH-116 2P1P (1) CL, (1) SAV, 416 LF of continuous SAV
MH-101_MH-102 2P1D (3) CL, (1) CS, (1) FC, 408 LF of continuous SAV
MH-98_MH-99 2O1O (3) SAV, (2) SSS, (2) CS, (2) CL, 363 LF of
continuous SAV, 10 LF of continuous SSS
MH-134A_MH-135 2N1U (4) SAV, 373 LF of continuous SAV
MH-109_MH-110 2M1R (3) SAV, (3) CL, (1) CS, 319 LF of continuous SAV
MH-118_MH-119 2M1O (3) SAV, (1) CL, (1) FC, 341 LF of continuous SAV
MH-123_MH-125 2M1N (2) CL, (1) SAV, 342 LF of continuous SAV
MH-104_MH-105 2L1K (4) CL, (2) SAV, 311 LF of continuous SAV
MH-127_MH-128 2K1Z (3) CL, (3) CS, (3) SAV, (1) FC, 248 LF of
continuous SAV
MH-96_MH-96A 2K1L (2) CL, (1) SSS, 293 LF of continuous SAV
MH-89_MH-90 2G1H (2) CL, (2) SAV, (1) CS, 174 LF of continuous SAV
MH-103_MH-104 2G1G 217 LF of continuous SAV
MH-148_MH-149 2G1F (1) CS, 192 LF of continuous SAV, 24 LF of
continuous CL
MH-141_MH-142 2D1O (7) CL, (4) SAV, 73 LF of continuous SAV
MH-138A_MH-139 2D1I (1) CL, (1) SAV, 113 LF of continuous SAV
MH-96A_MH-97 2D1C (2) SSS, 120 LF of continuous SAV
MH-122_MH-123 2D16 (8) SAV, (3) CL, (1) FC, 76 LF of continuous SAV
MH-94_MH-95 2D00 130 LF of continuous SAV
MH-99_MH-100 2D00 (2) SAV, (1) CL, (1) CS, 115 LF of continuous SAV
MH-97_MH-97A 2C00 120 LF of continuous SAV
MH-102B_MH-103 2B1B 91 LF of continuous SAV
MH144_MH-145 2B1A (3) SAV, (2) CL, 54 LF of continuous CL
MH-130_MH-131 2A1V (3) SAV, (1) CL, 37 LF of continuous SAV
MH-121_MH-122 2A1F (8) SAV, 25 LF of continuous SAV
MH-26_MH-27 2A11 (9) CL, (1) CS
MH-119_MH-120 2912 (6) SAV, (2) FC, (1) CL
MH-33_MH-36 2900 (8) CL, (1) CS
MH-108_MH-109 281C (1) CL, (1) SAV, 28 LF of continuous SAV
MH-142_MH-142A 281A (1) CL, 33 LF of continuous SAV
MH-102_MH-102A 2812 (1) CL, (1) SAV, 28 LF of continuous SAV
MH-114_MH-115 261L (3) SAV, (2) CS, (1) CL
MH-29_MH-32 2611 (5) CL, (1) CS
MH-120_MH-121 251A (3) SAV, (1) CL, (1) FC
MH-64_MH-65 2500 (4) CL, (1) CS
MH-132_MH-133 241S (3) CL, (1) SAV
MH-87_MH-88 2400 (4) CL
MH-93_MH-94 2400 (1) FC, 17 LF of continuous SAV
Agenda Item 9.1
Page 404 of 768
Pipeline Facility ID Structural Quick Rating Most Severe PACP Observations
MH-77_MH-78 2311 (3) CL
MH-11_MH-15 2300 (2) CL, (1) FC
MH-42_MH-44 2300 (2) CL, (1) CS
MH-55_MH-56 2300 (3) CL
MH-18_MH-21 2211 (2) CL
MH-9_MH-11 2200 (2) CL
MH-15_MH-16 2200 (1) CL, (1) CS
MH-21A_MH-24 2200 (2) CL
MH-27_MH-29 2200 (2) CL
MH-38_MH-40 2200 (2) CL
MH-56_MH-57 2200 (2) CL
MH-71_MH-72 2200 (1) CL, (1) CS
MH-102A_MH-102B 211B (1) FC
MH-134_MH-134A 211A (1) SAV
MH-136_MH-137 211A (1) SAV
MH-73_MH-74 2112 (1) CL
MH-36_MH-38 2100 (1) SAV
MH-40_MH-41 2100 (1) CL
MH-34_MH-35 2100 (1) CL
MH-39A_MH-43 2100 (1) CL
MH-86_MH-87 2100 (1) CL
MH-154_MH-155 2100 5 LF of continuous SAV
MH-155_MH-156 2100 (1) CL
MH-54_MH-55 2100 (1) CL
MH-57_MH-58 2100 (1) CL
MH-68_MH-69 2100 (1) CL
MH-50_MH-51 2100 (1) CL
MH-51_MH-52 2100 (1) CL
MH-52_MH-53 2100 (1) CL
MH-65_MH-66 2100 (1) CL
Table 19 lists the pipelines that have a Grade 1 defect as the most severe structural defect on the line. These
pipelines are shown as cyan pipelines in Appendix B.
Table 19: Pipelines with Grade 1 Structural Defects as Highest Severity
Pipeline Facility ID Structural Quick Rating Most Severe PACP Observations
MH-80_MH-81 1100 (1) CC
MH-63_MH-64 1100 (1) CC
Agenda Item 9.1
Page 405 of 768
3.3.1.2 O&M Observations
The O&M defect codes listed in the tables below are the PACP codes applied to the observed O&M defects. The
number in parentheses indicates the number of occurrences of that code. There may also be continuous stretches
of the codes, which will have the linear footage indicated. A condensed list of codes and their associated
descriptions is provided below. Refer to the PACP Reference Manual Version 7.0 for additional detailed
information about these and other PACP codes.
• IGB – Infiltration Gusher, Barrel (Grade 5)
• RMB – Roots Medium, Barrel (Grade 4)
• IRB – Infiltration Runner, Barrel (Grade 4)
• IR – Infiltration Runner (Grade 4)
• MCU – Miscellaneous, Camera Underwater (Grade 4)
• RMJ – Roots Medium, Joint (Grade 3)
• DAGS – Deposits Attached, Grease (1-10%: Grade 2)
• DSZ – Deposits Settled, Other (1-10%: Grade 2)
• DSF – Deposits Settled, Fine (Grade 2)
• DSGV – Deposits Settled, Gravel (Grade 2)
• DNF – Deposits Ingress, Fine (Grade 2)
• DAE – Deposits Attached, Encrustation (1-10%: Grade 2)
• DSC – Deposits Settled, Hard/Compacted (Grade 2)
• IW – Infiltration Weeper (Grade 2)
• DAR – Deposits Attached, Ragging (Grade 2)
• OBS – Obstruction Built Into Structure (Grade 2)
• ISSRB – Intruding Sealing Material Sealing Ring Broken (Grade 2)
• ISSR – Intruding Sealing Material Sealing Ring (Grade 2)
• RFB – Roots Fine, Barrel (Grade 2)
• OBR – Obstruction Rocks (Grade 2)
• RFJ – Roots Fine, Joint (Grade 1)
• IS – Infiltration Stain (Grade N/A)
o IS defects are described in the NASSCO PACP Manual as follows: “No moisture present during the
inspection but a watermark indicates water has entered in the past.”
It should be noted that the linear footage provided for the continuous stretches of a defect might be the total sum
of multiple continuous stretches along the pipe segment. For example, a single pipe segment may have 2 separate
10-foot stretches of continuous DAGS defect that would be described as having 20 feet of this particular defect.
Table 20 lists the pipeline(s) in the trunk main that has a Grade 5 O&M defect. This pipeline is shown as a red
pipeline in Appendix C.
Agenda Item 9.1
Page 406 of 768
Table 20: Pipelines with Grade 5 Maintenance Defects
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-153_MH-154 512A (1) IGB
Table 21 lists the pipelines that have a Grade 4 defect as the most severe O&M defect on the line. These pipelines
are shown as orange pipelines in Appendix C.
Table 21: Pipelines with Grade 4 Maintenance Defects as Highest Severity
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-145_MH-146 422Z (2) IRB
MH-155_MH-156 4200 (2) MCU
MH-152_MH-153 412Z (1) IR
MH-146_MH-147 412P (1) IRB
MH-120_MH-121 412L (1) RMB
Table 22 lists the pipelines that have a Grade 3 defect as the most severe O&M defect on the line. These pipelines
are shown as yellow pipelines in Appendix C.
Table 22: Pipelines with Grade 3 Maintenance Defects as Highest Severity
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-121_MH-122 312Z (1) RMJ
Table 23 lists the pipelines that have a Grade 2 defect as the most severe O&M defect on the line. These pipelines
are shown as blue pipelines in Appendix C.
Table 23: Pipelines with Grade 2 Maintenance Defects as Highest Severity
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-15_MH-16 2Z1M 781 LF of continuous DAGS
MH-32_MH-33 2Z1C 995 LF of continuous DAGS
MH-16_MH-18 2Z16 (1) DSZ, 1013 LF of continuous DAGS, 444 LF
of continuous DAE
MH-19_MH-20 2Z16 (1) DAE, 1027 LF of continuous DAGS
MH-118_MH-119 2Z16 (3) ISSRB, (1) IW, 909 LF of continuous DAGS
MH-128_MH-130 2Z15 (1) IW, (1) SSS, (1) DAR, 1171 LF of
continuous DAGS
MH-35_MH-37 2Z15 763 LF of continuous DAGS
MH-126_MH-127 2Z13 (7) OBR, (5) DAR, (3) IW, (1) DSZ, 1011 LF of
continuous DAGS, 495 LF of continuous DAE
Agenda Item 9.1
Page 407 of 768
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-139_MH-140 2Z13 (1) IW, 1150 LF of continuous DAGS
MH-64_MH-65 2Z13 1154 LF of continuous DAGS
MH-143_MH-144 2Z13 (6) DAR, 962 LF of continuous DAGS
MH-113_MH-114 2Z13 696 LF of continuous DAGS
MH-140_MH-141 2Z12 1148 LF of continuous DAGS
MH-65_MH-66 2Z12 1144 LF of continuous DAGS
MH-25_MH-28 2Z12 1077 LF of continuous DAGS
MH-23_MH-25 2Z12 1010 LF of continuous DAGS
MH-127_MH-128 2Z12 1009 LF of continuous DAGS
MH-131_MH-132 2Z12 (8) ISSRB, (1) ISSR, 957 LF of continuous
DAGS
MH-86_MH-87 2Z12 990 LF of continuous DAGS
MH-33_MH-36 2Z12 (3) IW, 943 LF of continuous DAGS
MH-72_MH-73 2Z12 835 LF of continuous DAGS
MH-130_MH-131 2Z11 (1) DAR, (1) DSGV, 1180 LF of continuous
DAGS
MH-122_MH-123 2Z11 1060 LF of continuous DAGS
MH-24_MH-26 2Z11 1015 LF of continuous DAGS
MH-87_MH-88 2Z11 1014 LF of continuous DAGS
MH-105_MH-106 2Z11 1011 LF of continuous DAGS
MH-9_MH-11 2Z11 (3) DSGV, 961 LF of continuous DAGS, 22 LF
of continuous DSF
MH-30_MH-31 2Z11 988 LF of continuous DAGS
MH-28_MH-30 2Z11 879 LF of continuous DAGS
MH-101_MH-102 2Z11 (1) IW, 840 LF of continuous DAGS
MH-141_MH-142 2Z11 804 LF of continuous DAGS
MH-123_MH-125 2Z11 783 LF of continuous DAGS
MH-100_MH-101 2Z11 (3) DAR, (2) ISSRB, 781 LF of continuous
DAGS
MH-18_MH-21 2Z00 (1) DSGV, (1) DSF, 1021 LF of continuous
DAGS, 881 LF of continuous DAE, 12 LF of
continuous DSGV
MH-10_MH-12 2Z00 (2) DSZ, 880 LF of continuous DAGS, 439 LF
of continuous DSF
MH-150_MH-151 2Z00 (23) DAR, 1205 LF of continuous DAGS
MH-37_MH-39 2Z00 1205 LF of continuous DAGS
MH-151_MH-152 2Z00 (30) DAR, 1199 LF of continuous DAGS
MH-107_MH-108 2Z00 1180 LF of continuous DAGS
MH-51_MH-52 2Z00 1175 LF of continuous DAGS
MH-50_MH-51 2Z00 1163 LF of continuous DAGS
Agenda Item 9.1
Page 408 of 768
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-42_MH-44 2Z00 (2) IW, 1097 LF of continuous DAGS, 40 LF of
continuous DSGV
MH-134A_MH-135 2Z00 (1) DAR, 1111 LF of continuous DAGS
MH-44_MH-48 2Z00 (3) IW, 1102 LF of continuous DAGS
MH-26_MH-27 2Z00 1096 LF of continuous DAGS
MH-106_MH-107 2Z00 1085 LF of continuous DAGS
MH-55_MH-56 2Z00 1068 LF of continuous DAGS
MH-61_MH-62 2Z00 1062 LF of continuous DAGS
MH-58_MH-59 2Z00 (2) DAR, 1059 LF of continuous DAGS
MH-56_MH-57 2Z00 1057 LF of continuous DAGS
MH-43_MH-46 2Z00 (1) DAR, 1046 LF of continuous DAGS
MH-53_MH-54 2Z00 1045 LF of continuous DAGS
MH-39A_MH-43 2Z00 1044 LF of continuous DAGS
MH-142F_MH-143 2Z00 (9) DAR, (6) IW, (1) DSGV, 1042 LF of
continuous DAGS
MH-59_MH-60 2Z00 (2) DAR, 1038 LF of continuous DAGS
MH-60_MH-61 2Z00 1036 LF of continuous DAGS
MH-57_MH-58 2Z00 1035 LF of continuous DAGS
MH-4_MH-6 2Z00 1028 LF of continuous DAGS
MH-36_MH-38 2Z00 (1) DSGV, 1005 LF of continuous DAGS, 16 LF
of continuous DSGV
MH-132_MH-133 2Z00 (1) DAE, (1) DAR, 1019 LF of continuous
DAGS
MH-17_MH-19 2Z00 1018 LF of continuous DAGS
MH-34_MH-35 2Z00 1009 LF of continuous DAGS
MH-21_MH-21A 2Z00 499 LF of continuous DAE, 499 LF of
continuous DAGS
MH-125_MH-126 2Z00 (1) IW, 991 LF of continuous DAGS
MH-31_MH-34 2Z00 986 LF of continuous DAGS
MH-52_MH-53 2Z00 985 LF of continuous DAGS
MH-62_MH-63 2Z00 984 LF of continuous DAGS
MH-111_MH-112 2Z00 (1) DAR, 973 LF of continuous DAGS
MH-5_MH-7 2Z00 971 LF of continuous DAGS
MH-133_MH-134 2Z00 970 LF of continuous DAGS
MH-67_MH-68 2Z00 965 LF of continuous DAGS
MH-68_MH-69 2Z00 965 LF of continuous DAGS
MH-76_MH-77 2Z00 965 LF of continuous DAGS
MH-3_MH-5 2Z00 (1) DAR, (1) DSGV, 964 LF of continuous
DAGS
MH-75_MH-76 2Z00 964 LF of continuous DAGS
Agenda Item 9.1
Page 409 of 768
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-29_MH-32 2Z00 (2) IW, 962 LF of continuous DAGS
MH-74_MH-75 2Z00 (1) DAGS, 961 LF of continuous DAGS
MH-109_MH-110 2Z00 960 LF of continuous DAGS
MH-8_MH-10 2Z00 952 LF of continuous DAGS
MH-54_MH-55 2Z00 939 LF of continuous DAGS
MH-6_MH-8 2Z00 938 LF of continuous DAGS
MH-78_MH-79 2Z00 914 LF of continuous DAGS
MH-38_MH-40 2Z00 (1) DAR, 905 LF of continuous DAGS
MH-79_MH-80 2Z00 893 LF of continuous DAGS
MH-115_MH-116 2Z00 (1) DSZ, (1) ISSRB, 883 LF of continuous
DAGS
MH-27_MH-29 2Z00 (1) DSC, 881 LF of continuous DAGS
MH-83_MH-84 2Z00 873 LF of continuous DAGS
MH-84_MH-85 2Z00 868 LF of continuous DAGS
MH-82_MH-83 2Z00 863 LF of continuous DAGS
MH-77_MH-78 2Z00 862 LF of continuous DAGS
MH-73_MH-74 2Z00 855 LF of continuous DAGS
MH-71_MH-72 2Z00 839 LF of continuous DAGS
MH-70_MH-71 2Z00 837 LF of continuous DAGS
MH-80_MH-81 2Z00 823 LF of continuous DAGS
MH-48_MH-50 2Z00 810 LF of continuous DAGS
MH-85_MH-85A 2Z00 790 LF of continuous DAGS
MH-14_MH-17 2Z00 752 LF of continuous DAGS
MH-135_MH-136 2Z00 (1) DAR, 750 LF of continuous DAGS
MH-98_MH-99 2Z00 (3) DSGV, (1) DAR, (1) DAGS, 742 LF of
continuous DAGS
MH-112_MH-113 2Z00 (2) DAR, (1) DSZ, 726 LF of continuous DAGS
MH-114_MH-115 2Z00 (2) DAR, 666 LF of continuous DAGS
MH-138_MH-138A 2Z00 (16) ISSRB, (5) ISSR, 607 LF of continuous
DAGS
MH-142C_MH-142D 2Y00 664 LF of continuous DAGS
MH-88_MH-89 2Y00 663 LF of continuous DAGS
MH-104_MH-105 2Y00 652 LF of continuous DAGS
MH-97A_MH-98 2X00 (1) IW, (1) DAR, 632 LF of continuous DAGS
MH-96_MH-96A 2X00 (4) DAGS, (1) IW, 611 LF of continuous DAGS
MH-63_MH-64 2W00 618 LF of continuous DAGS
MH-102_MH-102A 2W00 600 LF of continuous DAGS
MH-142E_MH-142F 2W00 (8) DAR, (1) RFB, 560 LF of continuous DAGS
MH-117_MH-118 2V00 (1) DAR, 595 LF of continuous DAGS
MH-81_MH-82 2T00 538 LF of continuous DAGS
Agenda Item 9.1
Page 410 of 768
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-22_MH-23 2S11 505 LF of continuous DAGS
MH-21A_MH-24 2S00 (1) DSZ, 514 LF of continuous DAGS
MH-20_MH-22 2R12 490 LF of continuous DAGS
MH-142B_MH-142C 2Q11 (3) DAR, 442 LF of continuous DAGS
MH-89_MH-90 2Q00 464 LF of continuous DAGS
MH-138A_MH-139 2Q00 (1) DAR, 445 LF of continuous DAGS
MH-103_MH-104 2Q00 (4) IW, 434 LF of continuous DAGS
MH-147_MH-148 2Q00 (14) DAR, 393 LF of continuous DAGS
MH-110_MH-111 2P00 (3) ISSRB, 407 LF of continuous DAGS
MH-95_MH-96 2O00 (2) DAGS, 410 LF of continuous DAGS
MH-116_MH-116A 2O00 (3) ISSR, (3) ISSRB, (3) DAR, (1) DAGS, 352 LF
of continuous DAGS
MH-148_MH-149 2O00 (2) DAR, 385 LF of continuous DAGS
MH-119_MH-120 2N00 (1) RFB, 393 LF of continuous DAGS
MH-66_MH-67 2N00 386 LF of continuous DAGS
MH-69_MH-70 2N00 385 LF of continuous DAGS
MH-137_MH-138 2L00 (1) DSZ, 328 LF of continuous DAGS
MH-116A_MH-117 2K00 (2) DAR, (3) ISSRB, (1) ISSR, 289 LF of
continuous DAGS
MH-142D_MH-142E 2K00 (3) DAR, 295 LF of continuous DAGS
MH-94_MH-95 2I00 (1) DAGS, 259 LF of continuous DAGS
MH-96A_MH-97 2I00 250 LF of continuous DAGS
MH-99_MH-100 2I00 (2) DAGS, 235 LF of continuous DAGS
MH-11_MH-15 2I00 (3) DSGV, (1) DSZ, (1) DNF, 232 LF of
continuous DAGS
MH-108_MH-109 2H11 237 LF of continuous DAGS
MH-7_MH-9 2H00 (1) DSZ, 139 LF of continuous DAGS, 101 LF
of continuous DSF
MH-97_MH-97A 2H00 (1) IW, 239 LF of continuous DAGS
MH-142A_MH-142B 2H00 236 LF of continuous DAGS
MH-39_MH-39A 2F00 188 LF of continuous DAGS
MH-102B_MH-103 2F00 187 LF of continuous DAGS
MH-149_MH-150 2F00 (5) DAR, 149 LF of continuous DAGS
MH-13_MH-14 2D00 144 LF of continuous DAGS
MH-102A_MH-102B 2D00 (1) DAR, 129 LF of continuous DAGS
MH-134_MH-134A 2C11 98 LF of continuous DAGS
MH-144_MH-145 2C00 113 LF of continuous DAGS
MH-142_MH-142A 2C00 (1) DAR, 109 LF of continuous DAGS
MH-136_MH-137 2C00 108 LF of continuous DAGS
MH-85A_MH-85B 2A00 66 LF of continuous DAGS
Agenda Item 9.1
Page 411 of 768
Pipeline Facility ID Maintenance Quick Rating Most Severe PACP Observations
MH-2_MH-4 2A00 64 LF of continuous DAGS
MH-46_MH-47 2800 43 LF of continuous DAGS
MH-93_MH-94 2600 34 LF of continuous DAGS
MH-12_MH-13 2600 26 LF of continuous DAGS
MH-85B_MH-86 2200 14 LF of continuous DAGS
MH-1_MH-3 2100 (1) DSGV
MH-47_MH-48 2100 (1) DAGS
MH-41_MH-42 2100 (1) OBS (flow meter)
Table 24 lists the pipelines that have infiltration PACP defects. Looking at this data, the four pipelines with an
infiltration and inflow (I&I) defect of severity grade 4 or 5 warrant consideration for rehabilitation to address the
defect. Refer to Section 9.1 for the recommended rehabilitation activity for these defects. Besides these 4
pipelines, there does not seem to be evidence of widespread or significant I&I defects along the trunkline. A
majority of the defects are “IS – Infiltration Stain”, which do not indicate an immediate risk for I&I flow entry to
the collection system. “IS” defects are described in the NASSCO PACP Manual as follows: “No moisture present
during the inspection but a watermark indicates water has entered in the past.”
Table 24: Pipelines with Infiltration Defect Observations
Pipeline Facility ID Maintenance Quick Rating Infiltration PACP Observation(s)
MH-153_MH-154 512A (1) IGB
MH-145_MH-146 422Z (2) IRB
MH-146_MH-147 412P (1) IRB
MH-152_MH-153 412Z (1) IR
MH-142F_MH-143 2Z00 (6) IW
MH-103_MH-104 2Q00 (4) IW
MH-33_MH-36 2Z12 (3) IW, (2) IS
MH-126_MH-127 2Z13 (3) IW, (2) IS
MH-44_MH-48 2Z00 (3) IW
MH-29_MH-32 2Z00 (2) IW
MH-42_MH-44 2Z00 (2) IW
MH-118_MH-119 2Z16 (1) IW, (6) IS
MH-128_MH-130 2Z15 (1) IW, (5) IS
MH-139_MH-140 2Z13 (1) IW, (3) IS
MH-101_MH-102 2Z11 (1) IW, (1) IS
MH-96_MH-96A 2X00 (1) IW
MH-97_MH-97A 2H00 (1) IW
MH-97A_MH-98 2X00 (1) IW
MH-125_MH-126 2Z00 (1) IW
Agenda Item 9.1
Page 412 of 768
MH-32_MH-33 2Z1C (3) IS, 106 LF of continuous IS
MH-19_MH-20 2Z16 (6) IS
MH-35_MH-37 2Z15 (5) IS
MH-16_MH-18 2Z16 (4) IS
MH-15_MH-16 2Z1M (3) IS
MH-113_MH-114 2Z13 (3) IS
MH-20_MH-22 2R12 (2) IS
MH-23_MH-25 2Z12 (2) IS
MH-25_MH-28 2Z12 (2) IS
MH-127_MH-128 2Z12 (2) IS
MH-131_MH-132 2Z12 (2) IS
MH-140_MH-141 2Z12 (2) IS
MH-22_MH-23 2S11 (1) IS
MH-24_MH-26 2Z11 (1) IS
MH-28_MH-30 2Z11 (1) IS
MH-30_MH-31 2Z11 (1) IS
MH-100_MH-101 2Z11 (1) IS
MH-108_MH-109 2H11 (1) IS
MH-121_MH-122 312Z (1) IS
MH-122_MH-123 2Z11 (1) IS
MH-123_MH-125 2Z11 (1) IS
MH-130_MH-131 2Z11 (1) IS
MH-134_MH-134A 2C11 (1) IS
MH-141_MH-142 2Z11 (1) IS
3.3.1.3 Pipelines with Lateral Connections
A total of thirty-four (34) lateral, or “tap”, connections across sixteen (16) different pipelines were observed during
the CCTV inspections. The PACP codes used to make the observations for the lateral connections, and their
associated NASSCO descriptions, are provided below. Table 25 lists the pipelines that were observed to have
lateral connections, along with pertinent information regarding the connections themselves.
• TF – Factory Made Tap Connection
o The tap connection appears to be a “purpose-made or pre-formed pipe fitting that was built into
the sewer during construction.”
• TFA – Active Factory Made Tap Connection
o The tap connection appears to be a “purpose-made or pre-formed pipe fitting that was built into
the sewer during construction.” The tap connection is considered active if it was obviously
contributing flow to the pipeline during the inspection. However, use of another PACP code
denoting a tap connection does not mean that the connection is not active. It simply means that
while the CCTV camera was inspecting the tap connection, no activity was observed.
Agenda Item 9.1
Page 413 of 768
• TB – Break-in/Hammer Tap Connection
o The tap connection appears to be a rough hole that “has been made in the wall of the sewer main
with a lateral pipe inserted into it without the use of a fitting for connecting and sealing the lateral
pipe.”
• TBA – Active Break-in/Hammer Tap Connection
o The tap connection appears to be a rough hole that “has been made in the wall of the sewer main
with a lateral pipe inserted into it without the use of a fitting for connecting and sealing the lateral
pipe.” The tap connection is considered active if it was obviously contributing flow to the pipeline
during the inspection. However, use of another PACP code denoting a tap connection does not
mean that the connection is not active. It simply means that while the CCTV camera was
inspecting the tap connection, no activity was observed.
• TS – Saddle Tap Connection
o The tap connection appears to be “a special fitting used to connect and seal the lateral pipe to
the inside or outside wall of the sewer main, typically found on lateral connections that have been
made after the sewer main was installed, or on installed pipelines that will not accommodate a
factory made tap.”
• TSA – Active Saddle Tap Connection
o The tap connection appears to be “a special fitting used to connect and seal the lateral pipe to
the inside or outside wall of the sewer main, typically found on lateral connections that have been
made after the sewer main was installed, or on installed pipelines that will not accommodate a
factory made tap.” The tap connection is considered active if it was obviously contributing flow
to the pipeline during the inspection. However, use of another PACP code denoting a tap
connection does not mean that the connection is not active. It simply means that while the CCTV
camera was inspecting the tap connection, no activity was observed.
Table 25: Pipelines with Lateral Connections
Pipeline Facility ID PACP
Observation Lateral Diameter (in) Clock Position Distance from USMH (ft)
MH-94_MH-95 TS 4 2 122.9
MH-95_MH-96
TS 4 1 168.7
TS 4 9 139.4
TS 4 2 138.9
TS 4 2 48.6
MH-96_MH-96A
TB 4 2 5.5
TB 4 10 48.4
TB 4 3 51.5
TB 4 3 59.1
TB 4 11 79.9
TB 4 3 113.7
TB 4 10 171.1
TB 4 3 191.3
Agenda Item 9.1
Page 414 of 768
TB 4 3 280.4
MH-96A_MH-97 TB 4 2 27.2
TB 4 10 74.5
MH-97_MH-97A TB 4 10 39.9
MH-97A_MH-98
TB 4 3 144.2
TB 4 3 192.1
TB 4 2 269.4
TB 4 2 313
MH-98_MH-99
TB 4 2 75.1
TB 4 2 120.2
TB 4 1 199.4
MH-100_MH-101 TBA 10 9 31.5
MH-106_MH-107 TSA 4 12 26.3
MH-111_MH-112 TB 6 2 100.9
MH-114_MH-115 TFA 6 9 2.1
MH-134A_MH-135 TF 8 1 272.1
MH-152_MH-153 TS 8 11 383.4
TS 8 11 315.7
MH-59_MH-60 TB 6 11 233.9
MH-60_MH-61 TF 6 11 126.1
MH-62_MH-63 TBA 6 2 476.9
Agenda Item 9.1
Page 415 of 768
3.3.2 Manhole Inspection Findings
3.3.2.1 Structural Observations
The structural defect codes listed in the tables below are the MACP codes applied to the observed structural
defects. The number in parentheses indicates the number of occurrences of that code. There may also be
continuous stretches of the codes, which will have the linear footage indicated. A condensed list of codes and
their associated descriptions is provided below. The tables are sorted on the Structural Quick Rating column so
the manholes with the largest count of the highest severity defects are listed in descending order from the top of
the table. Refer to the PACP Reference Manual Version 7.0 for additional detailed information about these and
other MACP codes.
• SMW – Missing Wall (Grade 5)
• HVV – Hole Void Visible (Grade 5)
• JOL – Joint Offset Large (Grade 5)
• SRV – Reinforcement Visible (Grade 5)
• Frame Offset Distance
o >4”: Grade 5
o 1”-4”: Grade 3
o <1”: Grade 1
• Cover/Frame Fit (Oversized): Grade 5
• SAM – Aggregate Missing (Grade 4)
• Cover Condition
o Corroded: Grade 4
o Sound: Grade 1
• Frame Seal Condition
o Cracked/Loose: Grade 4
o Missing: Grade 3
o Sound: Grade 1
• CM – Crack Multiple (Grade 3)
• FL – Fracture Longitudinal (Grade 3)
• SAP – Aggregate Projecting (Grade 3)
• LFW – Lining Feature Wrinkled (Grade 2)
• CC – Crack Circumferential (Grade 2)
• CL – Crack Longitudinal (Grade 2)
• CS – Crack Spiral (Grade 2)
• MMS – Missing Mortar Small (Grade 2)
• SAV – Aggregate Visible (Grade 2)
• SRI – Roughness Increased (Grade 1)
• Adjustment Ring Condition (Sound): Grade 1
• Frame Condition (Sound): Grade 1
Table 26 below lists the manholes along the trunk main that have a Grade 5 structural defect.
Table 26: Manholes with Grade 5 Structural Defects
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-123 5341 (3) SRV
MH-130 5341 (3) SRV
MH-75 5331 (2) SRV, (1) SMW
MH-79 5241 (1) JOL, Frame Offset Distance = 7”
MH-29 5231 (2) SRV
MH-41 5231 (2) SRV
MH-87 5231 (2) SRV
Agenda Item 9.1
Page 416 of 768
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-147 5226 (2) SRV
MH-146 5224 (2) SRV
MH-68 5223 (1) HVV, Cover/Frame Oversized
MH-120 5222 (1) SRV, Cover/Frame Oversized
MH-55 5141 (1) SRV
MH-70 5141 (1) SRV
MH-99 5132 (1) SRV
MH-32 5131 (1) SMW
MH-122 5131 (1) SRV
MH-97A 5131 (1) SRV
MH-102A 5131 (1) SRV
MH-109 5129 (1) SRV
MH-150 5128 Cover/Frame Oversized
MH-139 5128 (1) SRV
MH-90 5127 Cover/Frame Oversized
MH-64 5127 (1) SRV
MH-102B 5127 (1) SRV
MH-94 5127 (1) SMW
MH-148 5126 Cover/Frame Oversized
MH-101 5126 (1) SRV
MH-81 5125 Cover/Frame Oversized
MH-60 5125 (1) SRV
MH-144 5125 (1) SRV
MH-126 5124 Cover/Frame Oversized
MH-16 5124 (1) SMW
MH-93 5124 (1) SRV
MH-36 5124 (1) SMW
MH-15 5121 Cover/Frame Oversized
MH-119 5121 (1) SRV
The particular JOL defect found for MH-79 was found to be so severe that WWE/Pro-Pipe decided that immediate
attention was deserved from the City. Subsequently, the City’s repair crew promptly went out on June 18th, 2020
and performed a point repair on the JOL defect. Therefore, this report will not recommend a corrective action for
this particular defect.
Table 27 below lists the manholes that have a Grade 4 defect as the most severe structural defect on the line.
Agenda Item 9.1
Page 417 of 768
Table 27: Manholes with Grade 4 Structural Defects as Highest Severity
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-4 4324 (3) SAM
MH-149 4131 (1) SAM
MH-78 4131 Seal Condition Loose
MH-21A 4131 Cover Condition Corroded
MH-131 412B Seal Condition Loose
MH-52 412A Seal Condition Loose
MH-54 412A Seal Condition Loose
MH-56 412A Seal Condition Loose
MH-74 412A Seal Condition Loose
MH-57 4129 Seal Condition Loose
MH-96 4129 Seal Condition Cracked
MH-73 4129 Seal Condition Loose
MH-53 4128 Seal Condition Loose
MH-51 4127 Seal Condition Loose
MH-58 4127 Seal Condition Loose
MH-59 4127 Seal Condition Loose
MH-100 4127 Seal Condition Cracked/Loose
MH-80 4127 Seal Condition Loose
MH-69 4126 Seal Condition Loose
MH-18 4124 Seal Condition Cracked
MH-135 4124 Cover Condition Corroded
MH-33 4122 Seal Condition Cracked
MH-31 4121 (1) SAM
Table 28 below lists the manholes that have a Grade 3 defect as the most severe structural defect on the line.
Table 28: Manholes with Grade 3 Structural Defects as Highest Severity
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-24 3222 (1) CM, (1) SAP
MH-5 312A (1) CM
MH-98 312A (1) FL
MH-83 3128 Seal Condition Missing
MH-121 3128 (1) CM
MH-105 3128 (1) CM
MH-61 3126 (1) CM
MH-7 3125 (1) FL
MH-125 3124 Frame Offset Distance = 2”
Agenda Item 9.1
Page 418 of 768
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-84 3123 (1) CM
MH-97 3123 (1) CM
MH-6 3122 (1) CM
MH-86B 3122 (1) CM
MH-22 3121 (1) CM
MH-96A 3121 (1) CM
Table 29 below lists the manholes that have a Grade 2 defect as the most severe structural defect on the line.
Table 29: Manholes with Grade 2 Structural Defects as Highest Severity
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-133 2A15 (6) CL, (4) SAV
MH-108 2A15 (6) SAV, (4) CL
MH-134 2A15 (6) SAV, (4) CL, (2) CC, (1) MMS
MH-67 2A14 (7) CL, (6) SAV
MH-136 2A14 (7) SAV, (3) CL
MH-76 2A14 (5) CL, (5) SAV
MH-116 2A14 (6) SAV, (5) CL
MH-27 2914 (5) SAV, (3) CL, (1) CC
MH-107 2914 (6) SAV, (3) CL
MH-142D 2814 (4) SAV, (2) CC, (1) CL, (1) CS
MH-88 2814 (3) CL, (3) SAV, (2) CC
MH-110 2814 (5) SAV, (2) MMS, (1) CL
MH-114 2814 (5) SAV, (2) CL, (1) CC
MH-117 2814 (4) SAV, (2) CL, (2) CC
MH-142 2715 (5) SAV, (1) CC, (1) CL
MH-143 2715 (5) SAV, (2) CL
MH-118 2715 (6) SAV, (1) CL
MH-145 2715 (5) SAV, (1) CL, (1) CC
MH-14 2714 (6) SAV, (1) CC
MH-116A 2714 (7) SAV
MH-102 2714 (4) SAV, (2) CL (1) CC
MH-63 2714 (4) SAV, (2) CL, (1) MMS
MH-13 2714 (5) SAV, (2) CL
MH-106 2714 (5) SAV, (2) CL
MH-115 2714 (5) SAV, (1) CL, (1) CC
MH-112 2615 (5) SAV, (1) CL
MH-82 2615 (3) SAV, (3) CL
Agenda Item 9.1
Page 419 of 768
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-103 2614 (4) CL, (2) SAV
MH-11 2614 (5) SAV, (1) CC
MH-9 2614 (5) SAV, (1) CC
MH-77 2614 (4) SAV, (2) CL
MH-111 2614 (4) SAV, (2) CL
MH-8 2614 (3) SAV, (3) CC
MH-132 2614 (4) SAV, (2) CL
MH-3 2516 (5) SAV
MH-17 2515 (2) SAV, (1) MMS, (1) CL, (1) CC
MH-1 2515 (4) SAV, (1) CL
MH-140 2515 (4) SAV, (1) CC
MH-62 2515 (5) SAV
MH-113 2514 (3) SAV, (1) CL, (1) CC
MH-141 2514 (4) SAV, (1) CL
MH-142F 2514 (4) SAV, (1) CC
MH-134A 2416 (3) SAV, (1) CC
MH-19 2415 (2) SAV, (2) CC
MH-142E 2414 (4) SAV
MH-12 2414 (3) SAV, (1) CC
MH-2 2414 (4) SAV
MH-104 2414 (1) CC, (1) CL, (1) MMS, (1) SAV
MH-65 2315 (2) SAV, (1) CL
MH-95 2315 (2) CC, (1) SAV
MH-42 2314 (2) CC, (1) SAV
MH-21 2314 (3) SAV
MH-44 2314 (3) SAV
MH-26 2314 (3) SAV
MH-38 2314 (2) CL, (1) SAV
MH-86 2314 (2) MMS, (1) CL
MH-40 2314 (2) CC, (1) LFW
MH-10 2218 (1) CL, (1) CC
MH-85A 2215 (2) SAV
MH-142C 2215 (1) SAV, (1) CC
MH-46 2215 (2) CC
MH-89 2215 (2) SAV
MH-28 2214 (1) CL, (1) SAV
MH-30 2214 (1) SAV, (1) CC
MH-34 2214 (1) SAV, (1) CC
MH-35 2214 (1) CL, (1) CC
Agenda Item 9.1
Page 420 of 768
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-47 2214 (2) CC
MH-25 2115 (1) CC
MH-20 2114 (1) CC
MH-48 2114 (1) CC
MH-39 2114 (1) SAV
MH-43 2114 (1) CC
MH-50 2114 (1) SAV
Table 30 below lists the manholes that have a Grade 1 defect as the most severe structural defect on the line.
Table 30: Manholes with Grade 1 Structural Defects as Highest Severity
Manhole Facility ID Structural Quick Rating Most Severe MACP Observations
MH-39A 1500
Cover Condition Sound, Adjustment Ring
Condition Sound, Frame Condition Sound, Seal
Condition Sound, Frame Offset Distance = 0”,
MH-23 1400
Cover Condition Sound, Frame Condition Sound,
Seal Condition Sound, Frame Offset Distance =
0”
MH-37 1400
Cover Condition Sound, Frame Condition Sound,
Seal Condition Sound, Frame Offset Distance =
0”
Agenda Item 9.1
Page 421 of 768
3.3.2.2 O&M Observations
The O&M defect codes listed in the tables below are the PACP codes applied to the observed O&M defects. The
number in parentheses indicates the number of occurrences of that code. A condensed list of codes and their
associated descriptions is provided below. Refer to the PACP Reference Manual Version 7.0 for additional detailed
information about these and other PACP codes.
• OBI – Obstruction Intruding Through Wall (Grade 5)
• Cover/Frame Fit
o Oversized: Grade 5
o Good: Grade 1
• Frame Seal Condition
o Cracked/Loose/Offset/Missing: Grade 3
o Sound: Grade 1
• Pipe Connection Condition
o Defective: Grade 3
o Sound: Grade 1
• Frame Seal Inflow
o Stained: Grade 2
o None: Grade 1
• OBS – Obstruction Built into Structure
o Chimney/Cone & Wall (30-100%): Grade 2
• RFB – Roots Fine Barrel
o Channel: Grade 2
o Chimney/Cone & Wall/Bench: Grade 1
• DAR – Deposits Attached, Ragging
o Chimney/Cone & Wall: Grade 1
o Bench (<30%): Grade 1
o Channel (1-10%): Grade 1
• DSC – Deposits Settled Hard/Compacted
o Bench (<30%): Grade 1
• DSF – Deposits Settled, Fine silt/sand
o Bench (<30%): Grade 1
• DSGV – Deposits Settled Gravel
o Bench (<30%): Grade 1
• DSZ – Deposits Settled, Other
o Bench (<30%): Grade 1
• IS – Infiltration Stain (Grade 1)
• ISJ – Infiltration Stain Joint (Grade 1)
• ISZ – Intruding Sealing Material Other (Grade 1)
• OBN – Obstruction Construction Debris
Agenda Item 9.1
Page 422 of 768
o Bench (<30%): Grade 1
• OBP – Obstruction External Pipe or Cable
o Chimney/Cone & Wall (<30%): Grade 1
• RFC – Roots Fine Connection (Grade 1)
• RFJ – Roots Fine Joint (Grade 1)
• RMB – Roots Medium Barrel
o Chimney: Grade 1
• RMC – Roots Medium Connection
o Wall: Grade 1
• RMJ – Roots Medium Joint
o Cone & Wall: Grade 1
• Cover Insert Condition (Sound): Grade 1
• Frame Condition (Sound): Grade 1
• Chimney I/I (None): Grade 1
Table 31 below lists the manholes in the JTP trunk main that have a Grade 5 O&M defect.
Table 31: Manholes with Grade 5 O&M Defects
Manhole Facility ID Maintenance Quick Rating Most Severe MACP Observations
MH-68 5121 Cover/Frame Oversized
MH-120 5121 Cover/Frame Oversized
MH-32 5121 (1) OBI
MH-150 5121 Cover/Frame Oversized
MH-90 5121 Cover/Frame Oversized
MH-148 5121 Cover/Frame Oversized
MH-81 5121 Cover/Frame Oversized
MH-126 5121 Cover/Frame Oversized
MH-15 5121 Cover/Frame Oversized
MH-119 5121 (1) OBI
MH-149 5121 (1) OBI
MH-133 5121 (1) OBI
MH-28 5121 (1) OBI
Table 32 below lists the manholes that have a Grade 3 defect as the most severe O&M defect on the line.
Table 32: Manholes with Grade 3 O&M Defects as Highest Severity
Manhole Facility ID Maintenance Quick Rating Most Severe MACP Observations
MH-18 3122 Seal Condition Cracked
MH-123 3121 Seal Condition Loose
MH-130 3121 Seal Condition Loose
MH-79 3121 Seal Condition Loose/Offset
Agenda Item 9.1
Page 423 of 768
Manhole Facility ID Maintenance Quick Rating Most Severe MACP Observations
MH-55 3121 Seal Condition Cracked/Loose
MH-70 3121 Seal Condition Loose
MH-122 3121 Pipe #4 Condition Defective (Root Intrusion)
MH-78 3121 Seal Condition Loose
MH-131 3121 Seal Condition Loose
MH-52 3121 Seal Condition Loose
MH-54 3121 Seal Condition Loose
MH-56 3121 Seal Condition Loose
MH-74 3121 Seal Condition Loose
MH-57 3121 Seal Condition Loose
MH-96 3121 Seal Condition Cracked
MH-73 3121 Seal Condition Loose
MH-53 3121 Seal Condition Loose
MH-51 3121 Seal Condition Loose
MH-58 3121 Seal Condition Loose
MH-59 3121 Seal Condition Loose
MH-100 3121 Seal Condition Cracked/Loose
MH-80 3121 Seal Condition Loose
MH-69 3121 Seal Condition Loose
MH-33 3121 Seal Condition Cracked
MH-83 3121 Seal Condition Missing
MH-14 3121 Pipe #2 Condition Defective (Blocked)
MH-116A 3121 Pipe #3 Condition Defective (Protruding)
Table 33 below lists the manholes that have a Grade 2 defect as the most severe O&M defect on the line.
Table 33: Manholes with Grade 2 O&M Defects as Highest Severity
Manhole Facility ID Maintenance Quick Rating Most Severe MACP Observations
MH-42 2215 (1) OBS, Frame Seal Inflow Stained
MH-39A 2215 (1) OBS, Frame Seal Inflow Stained
MH-21A 211A Frame Seal Inflow Stained
MH-134A 211A Frame Seal Inflow Stained
MH-65 211A Frame Seal Inflow Stained
MH-21 211A Frame Seal Inflow Stained
MH-16 2119 Frame Seal Inflow Stained
MH-93 2119 Frame Seal Inflow Stained
MH-24 2119 Frame Seal Inflow Stained
MH-17 2119 Frame Seal Inflow Stained
Agenda Item 9.1
Page 424 of 768
Manhole Facility ID Maintenance Quick Rating Most Severe MACP Observations
MH-113 2119 Frame Seal Inflow Stained
MH-142E 2119 Frame Seal Inflow Stained
MH-44 2119 Frame Seal Inflow Stained
MH-64 2118 Frame Seal Inflow Stained
MH-102B 2118 Frame Seal Inflow Stained
MH-103 2118 Frame Seal Inflow Stained
MH-29 2117 Frame Seal Inflow Stained
MH-60 2117 Frame Seal Inflow Stained
MH-144 2117 Frame Seal Inflow Stained
MH-5 2117 Frame Seal Inflow Stained
MH-84 2117 Frame Seal Inflow Stained
MH-22 2117 Frame Seal Inflow Stained
MH-27 2117 Frame Seal Inflow Stained
MH-142 2117 Frame Seal Inflow Stained
MH-143 2117 Frame Seal Inflow Stained
MH-11 2117 Frame Seal Inflow Stained
MH-1 2117 Frame Seal Inflow Stained
MH-140 2117 Frame Seal Inflow Stained
MH-26 2117 Frame Seal Inflow Stained
MH-75 2116 Frame Seal Inflow Stained
MH-41 2116 Frame Seal Inflow Stained
MH-147 2116 Frame Seal Inflow Stained
MH-146 2116 Frame Seal Inflow Stained
MH-97A 2116 Frame Seal Inflow Stained
MH-94 2116 Frame Seal Inflow Stained
MH-36 2116 Frame Seal Inflow Stained
MH-31 2116 Frame Seal Inflow Stained
MH-121 2116 Frame Seal Inflow Stained
MH-7 2116 Frame Seal Inflow Stained
MH-96A 2116 Frame Seal Inflow Stained
MH-67 2116 Frame Seal Inflow Stained
MH-136 2116 Frame Seal Inflow Stained
MH-142D 2116 Frame Seal Inflow Stained
MH-118 2116 Frame Seal Inflow Stained
MH-102 2116 Frame Seal Inflow Stained
MH-112 2116 Frame Seal Inflow Stained
MH-9 2116 Frame Seal Inflow Stained
MH-141 2116 Frame Seal Inflow Stained
MH-142F 2116 Frame Seal Inflow Stained
Agenda Item 9.1
Page 425 of 768
Manhole Facility ID Maintenance Quick Rating Most Severe MACP Observations
MH-19 2116 Frame Seal Inflow Stained
MH-12 2116 Frame Seal Inflow Stained
MH-38 2116 Frame Seal Inflow Stained
MH-86 2116 Frame Seal Inflow Stained
MH-85A 2116 Frame Seal Inflow Stained
MH-30 2116 Frame Seal Inflow Stained
MH-34 2116 Frame Seal Inflow Stained
MH-35 2116 Frame Seal Inflow Stained
MH-47 2116 Frame Seal Inflow Stained
MH-25 2116 Frame Seal Inflow Stained
MH-20 2116 Frame Seal Inflow Stained
MH-48 2116 Frame Seal Inflow Stained
MH-23 2116 Frame Seal Inflow Stained
MH-99 2115 Frame Seal Inflow Stained
MH-102A 2115 Frame Seal Inflow Stained
MH-4 2115 Frame Seal Inflow Stained
MH-98 2115 Frame Seal Inflow Stained
MH-125 2115 Frame Seal Inflow Stained
MH-6 2115 Frame Seal Inflow Stained
MH-86B 2115 Frame Seal Inflow Stained
MH-88 2115 Frame Seal Inflow Stained
MH-145 2115 Frame Seal Inflow Stained
MH-63 2115 Frame Seal Inflow Stained
MH-82 2115 Frame Seal Inflow Stained
MH-77 2115 Frame Seal Inflow Stained
MH-111 2115 Frame Seal Inflow Stained
MH-62 2115 Frame Seal Inflow Stained
MH-2 2115 Frame Seal Inflow Stained
MH-95 2115 Frame Seal Inflow Stained
MH-40 2115 Frame Seal Inflow Stained
MH-10 2115 Frame Seal Inflow Stained
MH-142C 2115 Frame Seal Inflow Stained
MH-39 2115 Frame Seal Inflow Stained
MH-43 2115 Frame Seal Inflow Stained
MH-50 2115 Frame Seal Inflow Stained
MH-37 2115 Frame Seal Inflow Stained
MH-87 2114 Frame Seal Inflow Stained
MH-109 2114 Frame Seal Inflow Stained
MH-139 2114 Frame Seal Inflow Stained
Agenda Item 9.1
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Manhole Facility ID Maintenance Quick Rating Most Severe MACP Observations
MH-101 2114 Frame Seal Inflow Stained
MH-135 2114 Frame Seal Inflow Stained
MH-105 2114 Frame Seal Inflow Stained
MH-61 2114 Frame Seal Inflow Stained
MH-97 2114 Frame Seal Inflow Stained
MH-108 2114 Frame Seal Inflow Stained
MH-134 2114 Frame Seal Inflow Stained
MH-76 2114 Frame Seal Inflow Stained
MH-116 2114 Frame Seal Inflow Stained
MH-107 2114 Frame Seal Inflow Stained
MH-110 2114 Frame Seal Inflow Stained
MH-114 2114 Frame Seal Inflow Stained
MH-117 2114 Frame Seal Inflow Stained
MH-13 2114 Frame Seal Inflow Stained
MH-106 2114 Frame Seal Inflow Stained
MH-115 2114 Frame Seal Inflow Stained
MH-8 2114 Frame Seal Inflow Stained
MH-132 2114 Frame Seal Inflow Stained
MH-104 2114 Frame Seal Inflow Stained
MH-46 2114 Frame Seal Inflow Stained
MH-89 2114 Frame Seal Inflow Stained
Table 34 below lists the manholes that have a Grade 1 defect as the most severe O&M defect on the line.
Table 34: Manholes with Grade 1 O&M Defects as Highest Severity
Manhole Facility ID Maintenance Quick Rating Most Severe MACP Observations
MH-3 1700
Cover/Frame Fit Good, Cover Insert Condition
Sound, Frame Condition Sound, Seal Condition
Sound, Frame Seal Inflow None, Chimney I/I
None, Pipe Connection Condition(s) Sound
Table 35 lists the manholes that have infiltration MACP defects. Looking at this data, there does not seem to be
evidence of potentially significant infiltration and inflow (I&I).
Table 35: Manholes with Infiltration Defect Observations
Manhole Facility ID Maintenance Quick Rating Infiltration PACP Observation(s)
MH-21A 1500 (3) IS
MH-93 1400 (1) IS
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Manhole Facility ID Maintenance Quick Rating Infiltration PACP Observation(s)
MH-16 1300 (1) IS
MH-17 1300 (3) ISJ
MH-143 1300 (2) IS
MH-12 1200 (1) IS
MH-14 1200 (2) IS
MH-84 1200 (2) IS
MH-118 1200 (2) IS
MH-142D 1200 (1) IS
MH-144 1200 (1) IS
MH-146 1200 (1) IS
MH-111 1100 (1) IS
MH-102 1100 (1) IS
3.3.3 Buried Manholes
During the field assessment, there were found to be multiple instances along the JTP trunkline where the manhole
was unable to be found and is assumed to be buried. Table 36 below lists the manholes that are believed to be
buried, along with a description of their estimated locations.
Table 36: Buried Manholes
Manhole Facility ID Pipeline Diameter (in) Location Description
MH-66 24”
South of Fitzgerald Ave, located in a ditch that straddles the
property line between the residential homes to the west and
the farmland to the east
MH-127 36”
Located underneath the grass/landscaping on the western
side of Arroyo Circle, near 7700 Arroyo Circle, Gilroy, CA
95020
MH-128 36”
Located underneath the grass/landscaping on the western
side of Arroyo Circle, near 7520 Arroyo Circle, Gilroy, CA
95020
MH-137 36” Located on the southern side of Renz Lane, west of 850 Renz
Lane, Gilroy, CA 95020
MH-138 36” Located underneath the grass/landscaping south of Renz
Lane/MH-137, west of 850 Renz Lane and north of SR-152
MH-138A 36”
Located underneath parking lot pavement of the Gilroy
Crossing shopping mall, near southwest corner of Mimi’s
Café at 6935 Camino Arroyo, Gilroy, CA 95020
MH-142A 36” Located underneath gravel/dirt road, south of Holloway
Road
MH-142B 36” Located underneath gravel/dirt road, south of Holloway
Road and MH-142A
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3.3.4 Differences between City GIS and Field Assessment Findings
During the field assessment, discrepancies between the City’s wastewater collection system configuration in GIS
and WWE’s field assessment findings were found. Table 37 below lists the differences for the associated assets.
Table 37: City GIS and Field Assessment Findings Discrepancies
Asset Facility ID Discrepancy Description
MH-45;
MH-44_MH-48
MH-45 does not exist; because the manhole does not exist, new pipeline MH-
44_MH-48 was created
MH-49;
MH-48_MH-50
MH-49 does not exist; because the manhole does not exist, new pipeline MH-
48_MH-50 was created
MH-124;
MH-123_MH-125
MH-124 does not exist; because the manhole does not exist, new pipeline MH-
123_MH-125 was created
MH-129;
MH-128_MH-130
MH-129 does not exist; pipeline is split into two separate pipelines in City GIS
due to MH-129; because the manhole does not exist, new pipeline MH-
128_MH-130 was created
MH-21A;
MH-39A;
MH-85A;
MH-85B;
MH-96A;
MH-97A;
MH-102A;
MH-102B;
MH-116A;
MH-134A;
MH-138A;
MH-142A;
MH-142B;
MH-142C;
MH-142D;
MH-142E;
MH-142F
Manholes not in City GIS
MH-21_MH-21A;
MH-21A_MH-24;
MH-39_MH-39A;
MH-39A_MH-43;
MH-85_MH-85A;
MH-85A_MH-85B;
MH-85B_MH-86;
MH-96_MH-96A;
MH-96A_MH-97;
MH-97_MH-97A;
MH-97A_MH-98;
MH-102_MH-102A;
MH-102A_MH-102B;
Pipelines not in City GIS that were created based on the new manholes found
and described in the row above
Agenda Item 9.1
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Asset Facility ID Discrepancy Description
MH-102B_MH-103;
MH-116_MH-116A;
MH-116A_MH-117;
MH-134_MH-134A;
MH-134A_MH-135;
MH-138_MH-138A;
MH-138A_MH-139;
MH-142_MH-142A;
MH-142A_MH-142B;
MH-142B_MH-142C;
MH-142C_MH-142D;
MH-142D_MH-142E;
MH-142E_MH-142F;
MH-99 Manhole actually located about 128 feet south of City GIS location
MH-100 Manhole actually located about 37 feet southwest of City GIS location
MH-106 Manhole actually located about 75 feet southeast of City GIS location
MH-110 Manhole actually located about 46 feet southeast of City GIS location
Pipelines/manholes from
MH-119 to MH-128
Manhole locations, and by extension pipe lengths/locations, differ significantly
from original City GIS data
Pipelines from MH-142 to
MH-152
Manhole locations, and by extension lengths/locations/alignments, differ from
original City GIS data
Agenda Item 9.1
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4 Summary of Manhole Location Criteria Forms
Manhole Location Criteria Forms were completed for manholes along the JTP trunkline. The forms include space
for a sketch of the area surrounding the manhole under inspection. The sketches typically include any surrounding
streets, other known utilities, and/or buildings of importance. The likely drainage path of an SSO emanating from
the manhole to the nearest storm drain inlet or waterway was drawn when identifiable. The bottom half of the
form is comprised of three location descriptions of the manhole. These three location descriptions are the
Proximity to Waterways Rating, Public Impact Rating, and O&M Access and Safety Rating previously described in
Section 2.1.2. When determining a pipeline’s Consequence Rating, the US manhole’s three location criteria ratings
are used. See Table 40 in Section 6 for the ratings for the trunk main pipelines.
5 Summary of City Master Plan
In October of 2017, Akel Engineering Group (AKEL) completed the Sewer System Master Plan (SSMP) for the City,
which included a capacity assessment of the City’s wastewater collection system and the JTP trunk main. In this
section, WWE has summarized the pertinent capacity improvement(s) recommended by AKEL. How the capacity
improvement(s) help to direct and prioritize the recommended RRR alternative proposed in this Report is
discussed in more detail in Section 9.1 and Section 10. This section also includes discussion on the model results
data used for determining the Pipe Capacity Rating and the Flow Volume Rating for the pipelines.
5.1 Capital Improvement Projects
AKEL’s modeling approach to criterion for assessing capacity performance of existing pipes allowed for depth to
diameter (d/D) ratios up to 90 percent, even though the City’s maximum d/D ratio for newly designed pipes is 0.7.
WWE generally agrees with this stance, in that “the criterion for existing pipes is relaxed in order to maximize the
use of the existing pipes before costly pipe improvements are required.” AKEL recommended a total of nine (9)
improvement projects pertaining to the JTP trunk main, all but one of which consists of constructing a new relief
trunk. The improvement project titled JT-P1 is an upsizing replacement of an existing section of the JTP from 21”
to 30”, which appears to have already been constructed (i.e. pipe segment MH-48_MH-50, located on Highland
Avenue from Harding Avenue and then west along JTP trunk main for about 400 linear feet). Figure 2 below is an
excerpt of Table 7.1 from AKEL’s SSMP, which shows brief descriptions of the improvements JT-P2 through JT-P9.
Figure 2: Excerpt of Table 7.1 from AKEL SSMP
Agenda Item 9.1
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Figure 3 below is an excerpt of Figure 7.4 from the AKEL SSMP, which shows the locations of the proposed
improvement projects (i.e. JT-P2 through JT-P9).
Figure 3: Excerpt of Figure 7.4 from AKEL SSMP
The JTP improvement projects JT-P2 through JT-P9 make up a large portion of the Joint Relief Trunk that was
initially identified in the City’s 2002 Master Plan, and its necessity has been confirmed since then through more
recent studies.
Agenda Item 9.1
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To estimate the total project costs shown in Figure 2 above, AKEL applied a contingency of 15% to construction
costs. AKEL estimated various costs as the 15% of the total construction cost with contingency. These costs
include, but are not limited to, the following:
• Unforeseen events
• Unknown conditions
• Project Administration
• Construction Management and Inspection
• Legal Costs
5.2 Pipe Capacity Rating Data
The City’s SSMP capacity assessment results provide the data needed to determine the Pipe Capacity Ratings for
the pipelines as previously discussed in Section 2.1.1. The results of the model scenario “Existing PWWF” were
used to determine the d/D values. Please refer to Table 38 and Table 39 in Section 6 for the Pipe Capacity Ratings
for the trunk main pipelines.
5.3 Flow Volume Rating
Lastly, the City’s SSMP capacity assessment results were also utilized to determine the Flow Volume Ratings for
the pipelines as previously discussed in Section 2.1.2. The results of the model scenario “Existing PWWF” were
used to determine the maximum flow values. Please refer to Table 38 and Table 39 in Section 6 for the Flow
Volume Ratings for the trunk main pipelines.
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6 Risk Prioritization Results
In this section, all of the various criteria previously discussed in Section 2.1.1 and Section 2.1.2 are assigned for
each pipe segment (both comprehensively for those segments that were CCTV’ed and for only those criteria where
we have data for segments where CCTV was not able to be conducted). For the pipelines that were not CCTV
inspected, the Structural and O&M Condition Ratings had to be assumed, thereby resulting in assumed values for
Total Probability Score, Probability Rating, and the Overall Risk Rating. For these pipelines, the Structural and
O&M Condition Ratings are chosen by looking at the nearby US and/or DS pipelines that were CCTV inspected and
assuming the lowest Quick Rating applies. This was chosen as the methodology for pipelines not CCTV inspected
because it is not desirable to overestimate the severity and frequency of defect observations, which would likely
lead to recommended repair/rehabilitation that might not have been necessary had CCTV inspection been
performed.
For a visual representation of each pipeline’s Overall Risk Rating, see Appendix Din Section 15.4.
6.1 Probability Rating and Criteria
Table 38 below lists the three probability criteria, Total Probability Score, and Probability Rating for the trunk main
pipelines that were CCTV inspected. It should be noted that the pipelines are listed from US to DS along the
alignment.
Table 38: Probability Rating & Criteria for Inspected Pipelines
Pipeline Facility ID
Structural
Condition
Rating
Pipe Capacity
Rating
O&M
Condition
Rating
Total
Probability
Score
Probability
Rating
MH-1_MH-3 1 1 2 12 1
MH-2_MH-4 1 1 3 14 1
MH-3_MH-5 3 1 5 28 3
MH-4_MH-6 1 1 5 18 2
MH-5_MH-7 3 1 5 28 3
MH-6_MH-8 1 1 5 18 2
MH-7_MH-9 3 1 3 24 2
MH-8_MH-10 1 1 5 18 2
MH-9_MH-11 2 1 5 23 2
MH-10_MH-12 1 1 5 18 2
MH-11_MH-15 2 1 4 21 2
MH-12_MH-13 1 1 3 14 1
MH-13_MH-14 1 1 3 14 1
MH-15_MH-16 2 1 5 23 2
MH-14_MH-17 1 1 5 18 2
MH-16_MH-18 3 1 5 28 3
MH-17_MH-19 1 1 5 18 2
MH-18_MH-21 2 1 5 23 2
MH-19_MH-20 1 1 5 18 2
MH-21_MH-21A 3 1 5 28 3
Agenda Item 9.1
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Pipeline Facility ID
Structural
Condition
Rating
Pipe Capacity
Rating
O&M
Condition
Rating
Total
Probability
Score
Probability
Rating
MH-20_MH-22 1 1 5 18 2
MH-21A_MH-24 2 1 5 23 2
MH-22_MH-23 1 1 5 18 2
MH-24_MH-26 3 1 5 28 3
MH-23_MH-25 1 1 5 18 2
MH-26_MH-27 2 1 5 23 2
MH-25_MH-28 1 1 5 18 2
MH-27_MH-29 2 1 5 23 2
MH-28_MH-30 1 1 5 18 2
MH-29_MH-32 2 1 5 23 2
MH-30_MH-31 1 1 5 18 2
MH-32_MH-33 3 1 5 28 3
MH-31_MH-34 1 1 5 18 2
MH-33_MH-36 2 1 5 23 2
MH-34_MH-35 2 1 5 23 2
MH-36_MH-38 2 1 5 23 2
MH-35_MH-37 1 1 5 18 2
MH-37_MH-39 1 1 5 18 2
MH-38_MH-40 2 2 5 26 3
MH-40_MH-41 2 2 1 18 2
MH-39_MH-39A 1 1 3 14 1
MH-41_MH-42 1 1 2 12 1
MH-42_MH-44 2 2 5 26 3
MH-39A_MH-43 2 1 5 23 2
MH-44_MH-48 3 3 5 34 4
MH-43_MH-46 1 1 5 18 2
MH-46_MH-47 1 1 3 14 1
MH-47_MH-48 1 1 2 12 1
MH-48_MH-50 1 1 5 18 2
MH-50_MH-51 2 5 5 35 4
MH-51_MH-52 2 5 5 35 4
MH-52_MH-53 2 3 5 29 3
MH-53_MH-54 3 1 5 28 3
MH-54_MH-55 2 1 5 23 2
MH-55_MH-56 2 1 5 23 2
MH-56_MH-57 2 1 5 23 2
MH-57_MH-58 2 1 5 23 2
MH-58_MH-59 1 1 5 18 2
MH-59_MH-60 3 1 5 28 3
MH-60_MH-61 4 2 5 36 4
MH-61_MH-62 3 1 5 28 3
MH-62_MH-63 1 1 5 18 2
Agenda Item 9.1
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Pipeline Facility ID
Structural
Condition
Rating
Pipe Capacity
Rating
O&M
Condition
Rating
Total
Probability
Score
Probability
Rating
MH-63_MH-64 1 3 5 24 2
MH-64_MH-65 2 5 5 35 4
MH-65_MH-66 2 5 5 35 4
MH-66_MH-67 1 5 4 28 3
MH-67_MH-68 1 5 5 30 3
MH-68_MH-69 2 5 5 35 4
MH-69_MH-70 1 5 4 28 3
MH-70_MH-71 3 5 5 40 4
MH-71_MH-72 2 5 5 35 4
MH-72_MH-73 1 5 5 30 3
MH-73_MH-74 2 4 5 32 3
MH-74_MH-75 1 3 5 24 2
MH-75_MH-76 1 4 5 27 3
MH-76_MH-77 1 3 5 24 2
MH-77_MH-78 2 2 5 26 3
MH-78_MH-79 1 2 5 21 2
MH-79_MH-80 1 2 5 21 2
MH-80_MH-81 1 2 5 21 2
MH-81_MH-82 1 2 5 21 2
MH-82_MH-83 1 1 5 18 2
MH-83_MH-84 1 1 5 18 2
MH-84_MH-85 1 2 5 21 2
MH-85_MH-85A 1 1 5 18 2
MH-85A_MH-85B 1 1 3 14 1
MH-85B_MH-86 1 1 2 12 1
MH-86_MH-87 2 1 5 23 2
MH-87_MH-88 2 1 5 23 2
MH-88_MH-89 5 1 5 38 4
MH-89_MH-90 4 1 5 33 4
MH-93_MH-94 2 1 3 19 2
MH-94_MH-95 3 3 4 32 3
MH-95_MH-96 5 1 4 36 4
MH-96_MH-96A 5 1 5 38 4
MH-96A_MH-97 3 1 4 26 3
MH-97_MH-97A 3 1 4 26 3
MH-97A_MH-98 5 1 5 38 4
MH-98_MH-99 5 2 5 41 5
MH-99_MH-100 3 1 4 26 3
MH-100_MH-101 5 1 5 38 4
MH-101_MH-102 5 1 5 38 4
MH-102_MH-102A 2 1 5 23 2
MH-102A_MH-102B 2 1 3 19 2
Agenda Item 9.1
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Pipeline Facility ID
Structural
Condition
Rating
Pipe Capacity
Rating
O&M
Condition
Rating
Total
Probability
Score
Probability
Rating
MH-102B_MH-103 3 1 4 26 3
MH-103_MH-104 4 5 5 45 5
MH-104_MH-105 5 1 5 38 4
MH-105_MH-106 5 1 5 38 4
MH-106_MH-107 5 1 5 38 4
MH-107_MH-108 5 1 5 38 4
MH-108_MH-109 3 1 4 26 3
MH-109_MH-110 5 1 5 38 4
MH-110_MH-111 4 1 5 33 4
MH-111_MH-112 4 1 5 33 4
MH-112_MH-113 5 1 5 38 4
MH-113_MH-114 5 1 5 38 4
MH-114_MH-115 3 1 5 28 3
MH-115_MH-116 5 1 5 38 4
MH-116_MH-116A 5 1 4 36 4
MH-116A_MH-117 5 1 4 36 4
MH-117_MH-118 5 1 5 38 4
MH-118_MH-119 5 1 5 38 4
MH-119_MH-120 2 1 4 21 2
MH-120_MH-121 2 1 5 23 2
MH-121_MH-122 3 1 5 28 3
MH-122_MH-123 3 2 5 31 3
MH-123_MH-125 5 1 5 38 4
MH-125_MH-126 5 1 5 38 4
MH-126_MH-127 5 1 5 38 4
MH-127_MH-128 5 1 5 38 4
MH-128_MH-130 5 1 5 38 4
MH-130_MH-131 4 1 5 33 4
MH-131_MH-132 5 1 5 38 4
MH-132_MH-133 3 1 5 28 3
MH-133_MH-134 5 1 5 38 4
MH-134_MH-134A 2 1 3 19 2
MH-134A_MH-135 5 1 5 38 4
MH-135_MH-136 5 2 5 41 5
MH-136_MH-137 2 3 3 25 3
MH-137_MH-138 5 1 4 36 4
MH-138_MH-138A 5 1 5 38 4
MH-138A_MH-139 3 4 5 37 4
MH-139_MH-140 5 2 5 41 5
MH-140_MH-141 5 2 5 41 5
MH-141_MH-142 4 2 5 36 4
MH-142_MH-142A 3 4 3 33 4
Agenda Item 9.1
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Pipeline Facility ID
Structural
Condition
Rating
Pipe Capacity
Rating
O&M
Condition
Rating
Total
Probability
Score
Probability
Rating
MH-142A_MH-142B 4 4 4 40 4
MH-142B_MH-142C 5 4 5 47 5
MH-142C_MH-142D 5 4 5 47 5
MH-142D_MH-142E 5 4 4 45 5
MH-142E_MH-142F 5 4 5 47 5
MH-142F_MH-143 5 4 5 47 5
MH-143_MH-144 5 1 5 38 4
MH-144_MH-145 3 1 3 24 2
MH-145_MH-146 5 2 5 41 5
MH-146_MH-147 5 1 5 38 4
MH-147_MH-148 5 5 5 50 5
MH-148_MH-149 4 1 4 31 3
MH-149_MH-150 4 1 4 31 3
MH-150_MH-151 5 2 5 41 5
MH-151_MH-152 5 2 5 41 5
MH-152_MH-153 5 3 5 44 5
MH-153_MH-154 5 1 5 38 4
MH-154_MH-155 2 1 1 15 1
MH-155_MH-156 2 5 4 33 4
Table 39 below lists the three probability criteria, Total Probability Score, and Probability Rating for the trunk main
pipelines that were not CCTV inspected. It should be noted that the pipelines are listed from US to DS along the
alignment.
Table 39: Probability Rating & Criteria for Pipelines Not Inspected
Pipeline Facility ID
Structural
Condition
Rating
Pipe Capacity
Rating
O&M
Condition
Rating
Total
Probability
Score
Probability
Rating
MH-90_MH-91 2 1 2 17 2
MH-91_MH-92 2 1 2 17 2
MH-92_MH-93 2 1 2 17 2
6.2 Consequence Rating and Criteria
Table 40 below lists the four consequence criteria, Total Consequence Score, and Consequence Rating for the
trunk main pipelines that were CCTV inspected. It should be noted that the pipelines are listed from US to DS
along the alignment.
Agenda Item 9.1
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Table 40: Consequence Rating & Criteria for Inspected Pipelines
Pipeline Facility ID
Flow
Volume
Rating
Public
Impact
Rating
Proximity to
Waterways
Rating
O&M
Access and
Safety
Rating
Total
Consequence
Score
Consequence
Rating
MH-1_MH-3 4 5 1 1 30 3
MH-2_MH-4 4 5 1 1 30 3
MH-3_MH-5 3 5 1 1 26 3
MH-4_MH-6 4 5 1 1 30 3
MH-5_MH-7 3 5 1 1 26 3
MH-6_MH-8 4 5 1 1 30 3
MH-7_MH-9 3 5 1 1 26 3
MH-8_MH-10 4 5 1 1 30 3
MH-9_MH-11 3 5 1 1 26 3
MH-10_MH-12 4 5 1 1 30 3
MH-11_MH-15 4 5 1 1 30 3
MH-12_MH-13 4 5 1 1 30 3
MH-13_MH-14 4 5 1 1 30 3
MH-15_MH-16 4 3 1 1 26 3
MH-14_MH-17 4 3 1 1 26 3
MH-16_MH-18 4 3 1 1 26 3
MH-17_MH-19 4 3 1 1 26 3
MH-18_MH-21 4 3 1 1 26 3
MH-19_MH-20 4 3 1 1 26 3
MH-21_MH-21A 4 3 1 1 26 3
MH-20_MH-22 4 3 1 1 26 3
MH-21A_MH-24 4 3 1 1 26 3
MH-22_MH-23 4 3 1 1 26 3
MH-24_MH-26 4 1 1 1 22 2
MH-23_MH-25 4 1 1 1 22 2
MH-26_MH-27 4 3 1 1 26 3
MH-25_MH-28 4 3 1 1 26 3
MH-27_MH-29 4 5 1 1 30 3
MH-28_MH-30 4 5 1 1 30 3
MH-29_MH-32 4 5 1 1 30 3
MH-30_MH-31 4 5 1 1 30 3
MH-32_MH-33 4 5 1 1 30 3
MH-31_MH-34 4 5 1 1 30 3
MH-33_MH-36 4 3 1 1 26 3
MH-34_MH-35 4 3 1 1 26 3
MH-36_MH-38 4 5 1 1 30 3
MH-35_MH-37 4 5 1 1 30 3
MH-37_MH-39 4 5 1 1 30 3
MH-38_MH-40 4 5 1 1 30 3
Agenda Item 9.1
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Pipeline Facility ID
Flow
Volume
Rating
Public
Impact
Rating
Proximity to
Waterways
Rating
O&M
Access and
Safety
Rating
Total
Consequence
Score
Consequence
Rating
MH-40_MH-41 4 5 1 1 30 3
MH-39_MH-39A 3 5 1 1 26 3
MH-41_MH-42 4 5 1 1 30 3
MH-42_MH-44 4 5 1 1 30 3
MH-39A_MH-43 3 5 1 1 26 3
MH-44_MH-48 5 5 1 1 34 4
MH-43_MH-46 3 5 1 1 26 3
MH-46_MH-47 3 3 1 1 22 2
MH-47_MH-48 5 3 1 1 30 3
MH-48_MH-50 5 3 1 1 30 3
MH-50_MH-51 5 5 2 1 37 4
MH-51_MH-52 5 5 2 4 40 4
MH-52_MH-53 5 5 2 3 39 4
MH-53_MH-54 5 5 2 3 39 4
MH-54_MH-55 5 5 1 3 36 4
MH-55_MH-56 5 5 1 3 36 4
MH-56_MH-57 5 5 1 3 36 4
MH-57_MH-58 5 5 1 3 36 4
MH-58_MH-59 5 5 1 4 37 4
MH-59_MH-60 5 5 1 1 34 4
MH-60_MH-61 5 5 1 1 34 4
MH-61_MH-62 5 5 1 1 34 4
MH-62_MH-63 5 5 1 1 34 4
MH-63_MH-64 5 5 1 1 34 4
MH-64_MH-65 5 5 1 1 34 4
MH-65_MH-66 5 5 1 3 36 4
MH-66_MH-67 5 5 1 3 36 4
MH-67_MH-68 5 5 1 4 37 4
MH-68_MH-69 5 5 1 4 37 4
MH-69_MH-70 5 5 1 4 37 4
MH-70_MH-71 5 5 1 3 36 4
MH-71_MH-72 5 5 1 4 37 4
MH-72_MH-73 5 5 1 4 37 4
MH-73_MH-74 5 5 2 4 40 4
MH-74_MH-75 5 5 2 3 39 4
MH-75_MH-76 5 5 1 3 36 4
MH-76_MH-77 5 5 1 4 37 4
MH-77_MH-78 5 5 1 3 36 4
MH-78_MH-79 5 5 1 3 36 4
MH-79_MH-80 5 5 1 4 37 4
MH-80_MH-81 5 5 1 4 37 4
Agenda Item 9.1
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Pipeline Facility ID
Flow
Volume
Rating
Public
Impact
Rating
Proximity to
Waterways
Rating
O&M
Access and
Safety
Rating
Total
Consequence
Score
Consequence
Rating
MH-81_MH-82 5 5 1 1 34 4
MH-82_MH-83 5 5 1 1 34 4
MH-83_MH-84 5 5 1 3 36 4
MH-84_MH-85 5 5 1 3 36 4
MH-85_MH-85A 5 1 4 1 35 4
MH-85A_MH-85B 5 3 4 1 39 4
MH-85B_MH-86 5 3 4 1 39 4
MH-86_MH-87 5 3 4 1 39 4
MH-87_MH-88 5 5 5 1 46 5
MH-88_MH-89 5 5 5 1 46 5
MH-89_MH-90 5 3 5 1 42 5
MH-93_MH-94 5 1 5 1 38 4
MH-94_MH-95 5 1 5 1 38 4
MH-95_MH-96 5 1 5 1 38 4
MH-96_MH-96A 5 1 5 1 38 4
MH-96A_MH-97 5 3 5 1 42 5
MH-97_MH-97A 5 3 5 1 42 5
MH-97A_MH-98 5 3 4 1 39 4
MH-98_MH-99 5 3 4 1 39 4
MH-99_MH-100 5 5 4 1 43 5
MH-100_MH-101 5 5 4 1 43 5
MH-101_MH-102 5 5 4 3 45 5
MH-102_MH-102A 5 5 4 3 45 5
MH-102A_MH-102B 5 5 4 3 45 5
MH-102B_MH-103 5 5 4 3 45 5
MH-103_MH-104 5 5 2 1 37 4
MH-104_MH-105 5 5 4 1 43 5
MH-105_MH-106 5 5 4 1 43 5
MH-106_MH-107 5 5 2 1 37 4
MH-107_MH-108 5 3 2 1 33 4
MH-108_MH-109 5 3 1 2 31 3
MH-109_MH-110 5 3 1 2 31 3
MH-110_MH-111 5 3 1 2 31 3
MH-111_MH-112 5 3 1 2 31 3
MH-112_MH-113 5 3 2 2 34 4
MH-113_MH-114 5 3 2 2 34 4
MH-114_MH-115 5 3 2 2 34 4
MH-115_MH-116 5 3 2 2 34 4
MH-116_MH-116A 5 5 2 2 38 4
MH-116A_MH-117 5 5 2 2 38 4
MH-117_MH-118 5 5 2 2 38 4
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Pipeline Facility ID
Flow
Volume
Rating
Public
Impact
Rating
Proximity to
Waterways
Rating
O&M
Access and
Safety
Rating
Total
Consequence
Score
Consequence
Rating
MH-118_MH-119 5 5 2 2 38 4
MH-119_MH-120 5 3 2 1 33 4
MH-120_MH-121 5 3 2 1 33 4
MH-121_MH-122 5 3 2 1 33 4
MH-122_MH-123 5 3 2 1 33 4
MH-123_MH-125 5 3 2 2 34 4
MH-125_MH-126 5 3 2 3 35 4
MH-126_MH-127 5 1 2 3 31 3
MH-127_MH-128 5 1 2 3 31 3
MH-128_MH-130 5 1 2 3 31 3
MH-130_MH-131 5 1 1 3 28 3
MH-131_MH-132 5 1 3 3 34 4
MH-132_MH-133 5 3 5 3 44 5
MH-133_MH-134 5 3 2 1 33 4
MH-134_MH-134A 5 3 2 1 33 4
MH-134A_MH-135 5 3 2 3 35 4
MH-135_MH-136 5 3 2 1 33 4
MH-136_MH-137 5 3 2 1 33 4
MH-137_MH-138 5 3 2 1 33 4
MH-138_MH-138A 5 3 2 3 35 4
MH-138A_MH-139 5 3 2 1 33 4
MH-139_MH-140 5 3 2 1 33 4
MH-140_MH-141 5 3 2 1 33 4
MH-141_MH-142 5 3 2 1 33 4
MH-142_MH-142A 5 5 2 1 37 4
MH-142A_MH-142B 5 5 2 3 39 4
MH-142B_MH-142C 5 5 2 3 39 4
MH-142C_MH-142D 5 5 2 3 39 4
MH-142D_MH-142E 5 5 2 3 39 4
MH-142E_MH-142F 5 5 2 3 39 4
MH-142F_MH-143 5 5 2 3 39 4
MH-143_MH-144 5 5 2 3 39 4
MH-144_MH-145 5 5 2 3 39 4
MH-145_MH-146 5 5 2 3 39 4
MH-146_MH-147 5 5 2 3 39 4
MH-147_MH-148 5 5 2 3 39 4
MH-148_MH-149 5 5 2 3 39 4
MH-149_MH-150 5 5 2 3 39 4
MH-150_MH-151 5 5 2 3 39 4
MH-151_MH-152 5 5 2 3 39 4
MH-152_MH-153 5 5 2 3 39 4
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Pipeline Facility ID
Flow
Volume
Rating
Public
Impact
Rating
Proximity to
Waterways
Rating
O&M
Access and
Safety
Rating
Total
Consequence
Score
Consequence
Rating
MH-153_MH-154 5 5 2 3 39 4
MH-154_MH-155 5 5 2 3 39 4
MH-155_MH-156 5 5 2 3 39 4
Table 41 below lists the four consequence criteria, Total Consequence Score, and Consequence Rating for the
trunk main pipelines that were not CCTV inspected. It should be noted that the pipelines are listed from US to DS
along the alignment.
Table 41: Consequence Rating & Criteria for Pipelines Not Inspected
Pipeline Facility ID
Flow
Volume
Rating
Public
Impact
Rating
Proximity to
Waterways
Rating
O&M
Access and
Safety
Rating
Total
Consequence
Score
Consequence
Rating
MH-90_MH-91 1 1 5 1 22 2
MH-91_MH-92 1 1 5 1 22 2
MH-92_MH-93 1 1 5 1 22 2
6.3 Overall Risk Rating
Table 42 below lists the Probability Rating, Consequence Rating, and Overall Risk Rating for the trunk main
pipelines that were CCTV inspected. In the event that pipelines have the same Overall Risk Rating according to
Figure 1 above, they will be ranked in order of the following:
1. Probability Rating
2. Consequence Rating
3. Total Probability Score
4. Total Consequence Score
5. Structural Condition Rating
6. Pipe Capacity Rating
7. O&M Condition Rating
8. Flow Volume Rating
9. Proximity to Waterways Rating
10. Public Impact Rating
11. O&M Access and Safety Rating
12. Most US
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Table 42: Overall Risk Rating by Rank for Inspected Pipelines
Pipeline Facility ID Probability Rating Consequence
Rating
Overall Risk
Rating Rank
MH-147_MH-148 5 4 5 1
MH-142B_MH-142C 5 4 5 2
MH-142C_MH-142D 5 4 5 3
MH-142E_MH-142F 5 4 5 4
MH-142F_MH-143 5 4 5 5
MH-142D_MH-142E 5 4 5 6
MH-103_MH-104 5 4 5 7
MH-152_MH-153 5 4 5 8
MH-98_MH-99 5 4 5 9
MH-145_MH-146 5 4 5 10
MH-150_MH-151 5 4 5 11
MH-151_MH-152 5 4 5 12
MH-135_MH-136 5 4 5 13
MH-139_MH-140 5 4 5 14
MH-140_MH-141 5 4 5 15
MH-88_MH-89 4 5 5 16
MH-101_MH-102 4 5 5 17
MH-100_MH-101 4 5 5 18
MH-104_MH-105 4 5 5 19
MH-105_MH-106 4 5 5 20
MH-89_MH-90 4 5 5 21
MH-142A_MH-142B 4 4 5 22
MH-70_MH-71 4 4 5 23
MH-97A_MH-98 4 4 5 24
MH-143_MH-144 4 4 5 25
MH-146_MH-147 4 4 5 26
MH-153_MH-154 4 4 5 27
MH-96_MH-96A 4 4 5 28
MH-117_MH-118 4 4 5 29
MH-118_MH-119 4 4 5 30
MH-106_MH-107 4 4 5 31
MH-125_MH-126 4 4 5 32
MH-134A_MH-135 4 4 5 33
MH-138_MH-138A 4 4 5 34
MH-131_MH-132 4 4 5 35
MH-112_MH-113 4 4 5 36
MH-113_MH-114 4 4 5 37
MH-115_MH-116 4 4 5 38
MH-123_MH-125 4 4 5 39
MH-107_MH-108 4 4 5 40
MH-133_MH-134 4 4 5 41
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Pipeline Facility ID Probability Rating Consequence
Rating
Overall Risk
Rating Rank
MH-138A_MH-139 4 4 5 42
MH-95_MH-96 4 4 5 43
MH-116_MH-116A 4 4 5 44
MH-116A_MH-117 4 4 5 45
MH-60_MH-61 4 4 5 46
MH-137_MH-138 4 4 5 47
MH-141_MH-142 4 4 5 48
MH-51_MH-52 4 4 5 49
MH-50_MH-51 4 4 5 50
MH-68_MH-69 4 4 5 51
MH-71_MH-72 4 4 5 52
MH-65_MH-66 4 4 5 53
MH-64_MH-65 4 4 5 54
MH-44_MH-48 4 4 5 55
MH-155_MH-156 4 4 5 56
MH-142_MH-142A 4 4 5 57
MH-126_MH-127 4 3 4 58
MH-127_MH-128 4 3 4 59
MH-128_MH-130 4 3 4 60
MH-109_MH-110 4 3 4 61
MH-110_MH-111 4 3 4 62
MH-111_MH-112 4 3 4 63
MH-130_MH-131 4 3 4 64
MH-132_MH-133 3 5 4 65
MH-102B_MH-103 3 5 4 66
MH-99_MH-100 3 5 4 67
MH-96A_MH-97 3 5 4 68
MH-97_MH-97A 3 5 4 69
MH-73_MH-74 3 4 4 70
MH-94_MH-95 3 4 4 71
MH-148_MH-149 3 4 4 72
MH-149_MH-150 3 4 4 73
MH-122_MH-123 3 4 4 74
MH-67_MH-68 3 4 4 75
MH-72_MH-73 3 4 4 76
MH-52_MH-53 3 4 4 77
MH-53_MH-54 3 4 4 78
MH-69_MH-70 3 4 4 79
MH-66_MH-67 3 4 4 80
MH-114_MH-115 3 4 4 81
MH-59_MH-60 3 4 4 82
MH-61_MH-62 3 4 4 83
MH-121_MH-122 3 4 4 84
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Pipeline Facility ID Probability Rating Consequence
Rating
Overall Risk
Rating Rank
MH-75_MH-76 3 4 4 85
MH-77_MH-78 3 4 4 86
MH-136_MH-137 3 4 4 87
MH-32_MH-33 3 3 3 88
MH-16_MH-18 3 3 3 89
MH-21_MH-21A 3 3 3 90
MH-3_MH-5 3 3 3 91
MH-5_MH-7 3 3 3 92
MH-108_MH-109 3 3 3 93
MH-38_MH-40 3 3 3 94
MH-42_MH-44 3 3 3 95
MH-24_MH-26 3 2 3 96
MH-87_MH-88 2 5 3 97
MH-102_MH-102A 2 5 3 98
MH-102A_MH-102B 2 5 3 99
MH-144_MH-145 2 4 3 100
MH-74_MH-75 2 4 3 101
MH-76_MH-77 2 4 3 102
MH-63_MH-64 2 4 3 103
MH-86_MH-87 2 4 3 104
MH-54_MH-55 2 4 3 105
MH-55_MH-56 2 4 3 106
MH-56_MH-57 2 4 3 107
MH-57_MH-58 2 4 3 108
MH-120_MH-121 2 4 3 109
MH-79_MH-80 2 4 3 110
MH-80_MH-81 2 4 3 111
MH-78_MH-79 2 4 3 112
MH-84_MH-85 2 4 3 113
MH-81_MH-82 2 4 3 114
MH-119_MH-120 2 4 3 115
MH-93_MH-94 2 4 3 116
MH-134_MH-134A 2 4 3 117
MH-58_MH-59 2 4 3 118
MH-83_MH-84 2 4 3 119
MH-85_MH-85A 2 4 3 120
MH-62_MH-63 2 4 3 121
MH-82_MH-83 2 4 3 122
MH-7_MH-9 2 3 2 123
MH-27_MH-29 2 3 2 124
MH-29_MH-32 2 3 2 125
MH-36_MH-38 2 3 2 126
MH-15_MH-16 2 3 2 127
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Pipeline Facility ID Probability Rating Consequence
Rating
Overall Risk
Rating Rank
MH-18_MH-21 2 3 2 128
MH-21A_MH-24 2 3 2 129
MH-26_MH-27 2 3 2 130
MH-33_MH-36 2 3 2 131
MH-34_MH-35 2 3 2 132
MH-9_MH-11 2 3 2 133
MH-39A_MH-43 2 3 2 134
MH-11_MH-15 2 3 2 135
MH-40_MH-41 2 3 2 136
MH-48_MH-50 2 3 2 137
MH-4_MH-6 2 3 2 138
MH-6_MH-8 2 3 2 139
MH-8_MH-10 2 3 2 140
MH-10_MH-12 2 3 2 141
MH-28_MH-30 2 3 2 142
MH-30_MH-31 2 3 2 143
MH-31_MH-34 2 3 2 144
MH-35_MH-37 2 3 2 145
MH-37_MH-39 2 3 2 146
MH-14_MH-17 2 3 2 147
MH-17_MH-19 2 3 2 148
MH-19_MH-20 2 3 2 149
MH-20_MH-22 2 3 2 150
MH-22_MH-23 2 3 2 151
MH-25_MH-28 2 3 2 152
MH-43_MH-46 2 3 2 153
MH-23_MH-25 2 2 2 154
MH-154_MH-155 1 4 2 155
MH-85A_MH-85B 1 4 2 156
MH-85B_MH-86 1 4 2 157
MH-2_MH-4 1 3 1 158
MH-12_MH-13 1 3 1 159
MH-13_MH-14 1 3 1 160
MH-39_MH-39A 1 3 1 161
MH-47_MH-48 1 3 1 162
MH-1_MH-3 1 3 1 163
MH-41_MH-42 1 3 1 164
MH-46_MH-47 1 2 1 165
Table 43 below lists the Probability Rating, Consequence Rating, and Overall Risk Rating for the trunk main
pipelines that were not CCTV inspected. Note that these pipelines are listed according to the ranking explained
for Table 42.
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Table 43: Overall Risk Rating by Rank for Pipelines Not Inspected
Pipeline Facility ID Probability Rating Consequence
Rating
Overall Risk
Rating Rank
MH-90_MH-91 2 2 2 166
MH-91_MH-92 2 2 2 167
MH-92_MH-93 2 2 2 168
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7 Proposed Repair, Rehabilitation, and/or Replacement (RRR) Alternatives
In this section, WWE reviews various RRR alternative methodologies that aim to address the widespread structural
condition issues along the JTP trunk main. In Section 7.1, pipeline RRR alternatives are discussed, while manhole
RRR alternatives are discussed in Section 7.2.
All of the pipeline RRR alternatives discussed in Section 7.1 require sewage bypass pumping, with the exception
of the following alternative: spray coating. Spray coating, as described in Section 7.1.2.3, is applied to the crown
of the pipe, thus allowing for continual conveyance of live wastewater flow. Bypass pumping operations will
largely be similar for the various alternatives that require it, but the length of time of bypass pumping will depend
on how quickly the actual RRR work is completed. The cost of the bypass pumping is also dependent on how long
the RRR work lasts, as the sewer pipeline needs to remain out of service until the finished product is tested and
ready to be put back into service.
7.1 Pipelines
7.1.1 Repair
Grade 5 structural defects characterized as “point defects” can pose an immediate failure risk. The point defects
found along the JTP trunk main include the following:
• SMW – Missing Wall
• SRP – Reinforcement Projecting
The following repair methodologies can be utilized to address the point defects.
7.1.1.1 Open Cut Point Repair
Open cut trench excavation consists of excavating a trench to manually install each “stick” or piece of new pipe
where the point defect is located. Excavation must be performed to an adequate depth such that the existing
pipe is exposed, allowing for the repair to take place. This method is commonly used where the pipe is located
under non-pavement areas such as a front yard or back yard of a residence. However, open cut trench excavation
for a pipeline under a paved area can be accomplished, albeit at higher costs. This is due to the need to saw cut
and remove the existing pavement, fill the excavated area with the proper backfill (compacted stone, sand,
aggregate base, etc.), and then replace the pavement after the pipe repair has been completed. Open cut point
repairs under non-pavement areas would typically require backfilling with soil and the restoration of surface
vegetation with seed/sod, which is significantly cheaper. One significant advantage of the open cut method is
that due to it being widely known, with many experienced contractors available, it promotes a competitive bidding
environment.
For a majority of the JTP trunk main alignment, heavily trafficked areas (e.g. Leavesley Road near US-101) are not
an issue when assessing feasibility and cost of repair methodologies. However, the only pipe segment that was
found to have grade 5 structural defects (MH-116_MH-116A) that would warrant immediate corrective action(s)
is located on Leavesley Road west of US-101 highway. Due to the severity and continuous length of the “missing
wall” defect, as well as the close proximity of the other two grade 5 “missing wall” and “reinforcement projecting”
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structural defects, it is likely an open cut point repair to address these defects will be the most cost-conscious
methodology while still sufficiently addressing the near-term risks of the inspected defects.
7.1.1.2 Point Repair(s) with Structural CIPP Lining
The structural defects mentioned above could theoretically be addressed utilizing segmental structural CIPP point
repair technology that would cover the defect length plus approximately 5 to 10 linear feet either side of the
defect. A proven structural CIPP system would be used to renew the short sections of the gravity-flow pipelines.
This is a relatively fast, trenchless installation for maximum diameters of up to 48” depending on the manufacturer
and installer. The process is typically done with a corrosion-resistant fiberglass composite system and is an
industry proven means for expeditiously repairing and sealing isolated pipe defects such as cracks, holes,
fractures, leaks, joint offsets, corrosion and root intrusion. As such, point repairs utilizing a structural CIPP liner
material are also commonly used to address I&I defects to reduce additional wastewater flow volumes and
associated treatment costs.
Using a properly designed high-strength resin and fiberglass matrix, this method provides structural strength while
maintaining a relatively thin (1/2” – 1” thick), tapered profile and smooth finish to help maintain flow capacity.
The resins can be cured under ambient sewer conditions with very low shrink and can cure under water if
necessary. It is desirable to have design criteria that maximizes the potential for the tightest possible fit against
the host pipe while eliminating the need for a preliner/heater system/end seal. However, if a preliner/heater
system/end seal is determined to be necessary, it will be addressed in the design stage of the project.
This alternative would require less excavation when compared to the open cut method, thus potentially reducing
overall costs for point repairs under paved areas. The method typically only requires one access point to complete
the installation of the CIPP liner as well. An added benefit of this jointless pipe liner is the reduction in root and
water infiltration when compared to a new “stick” of installed pipe under the open cut method. For successful
implementation of the trenchless point repair method any roots and debris in the pertinent pipeline must be
removed before installation. It should also be noted that this method is typically not applicable for
collapsed/severely broken pipe, or pipes with heavy root blockages. While a large majority of CIPP work is
performed on the “smaller” pipe sizes of about 12” and smaller, there are still a number of contractors who are
experienced and qualified enough to address the aforementioned structural defects through the use of this
methodology.
While the structural CIPP lining point repair methodology would typically address most grade 5 structural defects
that warrant immediate corrective action, the aforementioned defects found in pipeline MH-116_MH-116A are
so severe that CIPP lining would likely not be feasible. However, this point repair methodology will still be
considered for potentially addressing any significant I&I point defects found through the inspection work.
7.1.1.3 Chemical Grouting
Chemical grouting is one of the oldest methods for impeding infiltration into sewer systems, including pipes and
manholes. Several chemical grouting manufacturers, such as AvantiGrout, can provide a short term (2 to 10-year
service life) product suitable for the rehabilitation of pipeline infiltration spots. Due to the grout being applied
under pressure, the product is able to form into the surrounding soil near the infiltration defect and not simply fill
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the crack/joint/etc. The product’s low viscosity allows it to enter virtually any space/area that water can reach,
making chemical grout a robust and versatile option.
7.1.2 Rehabilitation
7.1.2.1 Sliplining
The sliplining method of pipe rehabilitation would involve the insertion (pushing or pulling) of a new, smaller
pipeline (typically HDPE pipe) inside the existing JTP trunk main. The newly inserted pipeline would provide
adequate structural strength to replace the deteriorated existing pipeline. The annular space between the inside
of the existing pipeline and the outside of the new sliplined pipeline would be grouted for the following reasons:
• To prevent soil and groundwater migration into the annular space
• To keep the newly inserted pipe from moving around while inside of the existing pipe
• To transfer loads from the existing pipe to the new pipe to maintain structural integrity
Advantages of the sliplining method include the fact that it is has been successfully used for decades, thus making
it a well-understood technology. With many experienced contractors available, the anticipated competitive bids
often result in sliplining being a cost effective trenchless rehabilitation solution. However, it would be prudent to
require contractors to provide evidence of sufficient prior sliplining experience. Another advantage of sliplining
includes the installation rate of about 300-500 feet per day, after mobilization and preparation, thus limiting
significant impacts (such as major multi-lane closures) to shorter periods of time.
A significant disadvantage of the sliplining method is the resultant reduction in flow capacity for the trunk main.
The JTP trunk main has already been identified as capacity deficient, thus requiring the construction of the JT-P2
through JT-P9 improvement projects (as discussed in Section 5.1). Also, the insertion pit and staging area required
for sliplining are much larger than what is required for structural CIPP installation (see Section 7.1.2.2). The
insertion pits are typically about 60 feet long by 4-8 feet wide, while the staging areas are typically about 250 feet
long by 15 feet wide due to the HDPE pipe fusion process, although this staging work can potentially be located
outside of the alignment (or at minimum outside of a traffic lane along the edge of the right of way) and then the
pipe mobilized to the alignment only when the insertion pit is prepared and ready for actual installation. Another
potential disadvantage includes the need for small pits to reconnect all of the laterals along the trunk main. The
contractor would have to completely clean the trunk main of all debris and roots before the sliplining installation
can occur and CCTV inspect the finished product to ensure its quality. Due to the JTP trunk main already being
identified as capacity deficient and in need of the relief trunk improvement project (see Section 5.1), combined
with the plan of continued use of the JTP trunk main for conveyance of future flows even after the relief trunk
improvement project is constructed, the sliplining rehabilitation methodology will not be considered for
addressing the structural issues along the JTP trunk main due to the greater reduction in flow capacity when
compared to structural CIPP lining (discussed in Section 7.1.2.2) and/or spray coating (discussed in Section 7.1.2.3).
7.1.2.2 Structural CIPP Lining – Full Pipe Segment
Full segment structural CIPP lining utilizes the same methodology as previously described in Section 7.1.1.2, but
with the liner being installed from manhole to manhole for the pipeline (i.e. “full segment”). Major factors that
can impact the thickness of the CIPP liner include the following:
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•Extent of (crown) deterioration of the existing pipe
•The “ovality” of the pipe (i.e. whether or not the existing pipe has lost its round shape)
•Depth of cover
•Groundwater level
Based on preliminary research of expected groundwater levels in Morgan Hill and Gilroy, groundwater within the
pipe zone during installation of the structural CIPP liner becomes more likely as one moves further downstream
along the JTP trunk main. This is due to two primary reasons: 1) the JTP trunk main depth typically increases the
further downstream one goes, and 2) groundwater levels tend to increase as you move south from Morgan Hill to
Gilroy. However, the groundwater levels in Gilroy tend to follow a seasonal pattern where the highest levels are
recorded during the typical “wet” months of December through March. In any case, the possibility for high
groundwater levels will need to be considered during design and construction of any potential CIPP lining
improvement projects.
A distinct advantage of structural CIPP lining is that the liner is thinner than the typical HDPE pipe used for the
sliplining process, while still providing adequate structural strength to replace the deteriorated trunk main.
Because the liner is bonded to the existing pipe, there is no annular space that would have to be grouted and the
cured liner would not be likely to move inside the host pipe. Another advantage is the ability of CIPP liners to be
used through siphons like the one located near the intersection of Wren Avenue and La Primavera Way. Also, the
insertion pit and staging area required for this method are much smaller than what is required for a sliplining
installation. The insertion pits are typically about 5 feet long by 5 feet wide where needed (most smaller diameter
CIPP installations can typically utilized an existing manhole entrance as the insertion point), while the staging areas
are typically about 20 feet long by 12 feet wide. The staging area size assumes that the felt is impregnated with
the resin at the factory rather than on-site. Installation lengths can reach up to 1,000 feet between access pits,
which should render this methodology applicable to every pipeline along the JTP trunk main. Another advantage
to consider is that the lateral connections along the JTP trunk main can be remotely reinstated, whereas sliplining
would require a small pit for each lateral reinstatement. Lastly, due to the existence of several companies capable
of installing structural CIPP liners, this method can be cost-competitive with sliplining.
One disadvantage of structural CIPP lining is the potential of styrene from the curing water to be eventually
discharged to the SCRWA WWTP. This styrene could negatively affect the plant’s biological treatment process(es).
To prevent styrene discharge, options include the following:
•The use of a resin system that does not contain styrene
•Cure the pipe liner through steam or ultraviolet light instead of water
•Require the onsite treatment of the curing water prior to discharge into the trunk main; however, this
may require an additional water discharge permit review
Another disadvantage is related to the reinstatement of the lateral connections. Each time the lateral pipe is
tapped, there is some risk of water seeping between the CIPP liner and the existing pipe. With the potential high
groundwater table for the JTP trunk main as one moves further south, a lateral sealing technology would be
preferred where the lateral connects to the trunk main. A robot can be used to remotely apply top hats or
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interface seals from inside the CIPP liner, thus eliminating the need for aboveground access as with sliplining
lateral reinstatement. Also, the contractor would have to completely clean the trunk main of all debris and roots
before the structural CIPP lining installation can occur and potential repairs would be needed where holes in the
pipe liner walls occur. Lastly, CCTV inspection of the finished lining product would be needed to ensure its quality.
7.1.2.3 Spray Coating
Applying a magnesium hydroxide spray coating to the crown of the concrete sections of the JTP trunk main could
reduce corrosion potential for some period of time and thus extend the useful life by acting as a sacrificial layer
that the sulphuric acid will react with and neutralize instead of the concrete pipe. An example of such a product
is Thioguard TST, which is an alkaline magnesium hydroxide slurry that is typically applied with a coating thickness
of 100-125 mils. While the spray coating neutralizes existing sulphuric acid on the surface of the pipeline, it also
deactivates the bacteria that is responsible for the generation of the sulphuric acid. The spray coating also reacts
with hydrogen sulfide gas, thus helping to reduce potential odor problems.
Typical spray coating treatment can cost significantly less than the previously mentioned rehabilitation
methodologies, but would need to be replenished on a regular basis. Thioguard TST has been estimated to extend
sewer asset life by 20 years provided that annual retreatment using the magnesium hydroxide spray coating
occurs. In the case of the JTP trunk main, this system could be used on a more limited basis (spray every 2-3 years)
to support phasing of the more comprehensive rehabilitation methods over a longer period of time.
7.1.3 Replacement
7.1.3.1 Dig & Replace Open Cut Method
The dig and replace open cut method is the same methodology previously described in Section 7.1.1.1, but with
an entire manhole to manhole pipe segment being removed and replaced with a new pipe. This traditional
method of excavating, bedding, laying, and backfilling a pipeline is commonly utilized across the industry, thus
providing a competitive bidding environment if chosen.
The main disadvantage of this method in relation to the JTP trunk main is the substantial negative impact on local
residents, regional commuters, traffic, and the environment. Relative to other trenchless replacement methods
discussed in this Report, the open cut method would have the greatest impact on nearby commercial businesses
and local residents due to traffic impacts. Also, in areas of the alignment where the groundwater table is high,
dewatering of the trench and the preparation of a suitable, stable trench bottom can be difficult to achieve. To
prevent settlement of the area surrounding the trench, areas with high groundwater would likely require
impermeable shoring and imported light-weight backfill. Lastly, with depths of the trunk main reaching 23 feet,
the open cut construction costs would be significantly more expensive than the trenchless methodologies
discussed below. Due to the high construction costs and negative impact on local residents, traffic, and the
environment, the open cut replacement methodology will not be explored further in this Report.
7.1.3.2 Pipe Bursting
Pipe bursting is a trenchless construction method for replacing an existing pipe through the fragmentation of the
existing pipe and installing a new pipe of equal or larger diameter in its place. The method starts with the initial
cracking of the existing pipe with an oversized conical bursting head, which then fragments the existing pipe. This
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conical bursting head is effectively creating a tunnel into which the new pipe, which is pulled behind the bursting
head, is simultaneously installed. Typical diameters for new pipe installed through this method can experimentally
reach up to 54 inches, although more typical maximum diameters are 24 to 36-inches, with installation lengths
varying from 200-600 feet. On routine to moderately difficult projects, upsizing typically ranges from 1-2 pipe
diameter sizes. Pipe diameter upsizing of three or more sizes can be difficult and is dependent on favorable soil
conditions. It also tends to require specific bursting equipment to be specified.
Using an appropriate pipe bursting technique, almost all types of existing pipe material can be replaced. However,
exceptions to pipe bursting applications include pre-stressed concrete cylinder and heavily reinforced concrete
pipe (RCP). There have been instances where concrete pipe can be successfully replaced with pipe bursting if it is
not heavily reinforced or if it is substantially deteriorated. Because roughly 40% of the JTP trunk main is concrete
pipe or reinforced concrete pipe, this must be taken into consideration. While HDPE is the most commonly used
material for the newly installed pipe, both continuous and segmented pipe such as HDPE, polyvinyl chloride (PVC),
ductile iron and steel are used as the new product pipe.
Pipe bursting is very effective if the existing pipeline has structural defects that prevent other trenchless methods
from being utilized and if the pipeline has inadequate capacity. When compared to the traditional open-cut
construction method, pipe bursting can limit ground surface damage and disruption. Because these are significant
concerns along the JTP trunk main (crop fields, heavily trafficked roadways, commercial parking lots), pipe bursting
could reduce the social costs typically associated with pipeline replacement. While providing a significantly
smaller environmental footprint, installation rates can reach up to 200 linear feet per hour after all of the required
set-up is completed. Another advantage is that the pipe bursting pits have the ability to be located at manholes
that already require replacement. While the receiving pit can be an existing manhole where replacement is not
required, this manhole has to be prepared in advance by enlarging the pipe entry point in order to avoid damage
to the existing manhole.
One disadvantage of the pipe bursting method is the increasing difficulty of installation as the existing pipe
diameter increases. Typical pipe bursting diameters of the existing pipeline range from 8 to 24 inches with
installation lengths of up to 500 feet. However, projects have been completed in the past for larger diameter
pipes using the pneumatic pipe bursting technique. Another disadvantage involves the potential for soil heave or
settlement, especially when upsizing larger diameter pipelines. Soil heave can impact crossing utilities, but the
impact can be mitigated by potholing or placing pits above the utility and then extracting the soil so that no load
is placed on the existing utility during the pipe bursting application. While certain sections of the roadway can be
sawcut so that only that area is raised when significant heave is anticipated, roadway disruption like this would
need to be minimized on any highly traversed roadway along the JTP trunk main alignment. Lastly, pipe bursting
is possible for a single siphon. However, pipe bursting is not recommended for parallel siphon pipes located close
together like the double barrel siphon near the intersection of Wren Avenue and La Primavera Way.
7.1.3.3 Microtunneling
Microtunneling is a trenchless pipe replacement methodology that utilizes a closed face, remotely controlled,
guided, pipe jacking system to provide continuous support to the excavation face. Personnel entry into the tunnel
is not required because microtunneling is remotely controlled. A method of microtunneling called in-line
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microtunneling can be employed to replace the existing trunk main. The existing pipe is filled with flowable fill to
prevent fluid loss, and then the microtunnel boring machine (MTBM) excavates the entire pipe and surrounding
ground to allow for the installation of the new pipe. The system is guided by a laser mounted in the jacking shaft
that projects a beam onto a target in the steering section of the MTBM. The remotely controlled steering jacks
steer the MTBM by extending or retracting. In this manner, the contractor can precisely control the line and grade
of the installed pipe. Microtunneling can achieve installation lengths of around 800 linear feet. Microtunneling
typically has a unit cost around $35 per inch-diameter foot, making it considerably more expensive than the other
methodologies discussed in this Report.
7.2 Manholes
7.2.1 Repair
In Section 3.3.3, instances of buried manholes along the JTP trunk main are discussed. The manholes described
in Table 36 were found to be buried during the field assessment. These manholes are recommended to be
repaired by raising them to be flush with ground level so that they are accessible when necessary (i.e. for any
future cleaning/inspection/repair activities). The work involved will likely include the following: locating the
existing buried manhole, excavating down to the top of the manhole, installing the necessary amount of manhole
sections/risers/rings, installing the existing or new manhole frame and cover, cleaning, bedding/backfill,
compaction, testing, and any other subgrade improvements required per the applicable jurisdictional agency’s
standards.
7.2.2 Rehabilitation
This section contains discussion of the potential rehabilitation methodologies available to address the Grade 5
and Grade 4 structural defects listed in Table 26 and Table 27, respectively.
7.2.2.1 Cured-In-Place Manhole Liners
Cured-in-place manhole (CIPM) liners are similar to the CIPP liners previously discussed for pipeline rehabilitation
in Section 7.1.2.2. A properly designed high-strength resin and fiberglass matrix would be installed in the manhole.
These liners can be pre-made, designed and fabricated for each manhole as necessary. Constant diameter liners
are also available should the pertinent manholes be similar in size and shape. Any infiltration spots must be
stopped using a fast-setting cementitious material before the CIPM liner can be installed (see Section 7.2.2.2),
with the liner providing further infiltration prevention once installed. CIPM liners are a good rehabilitation
alternative that can expeditiously repair and seal isolated manhole defects while keeping the structural integrity
of the manhole intact. They are typically installed from the bench all the way up to the cone of the manhole.
While more expensive than the other manhole rehabilitation methodologies discussed below, CIPM liners are
suitable for manholes with several structural/O&M defects that would render spot application of cementitious
liners/grout cost prohibitive in comparison.
7.2.2.2 Cementitious Liners
Cementitious liners, such as SewperCoat, provide high-strength, corrosion-resistant protection against potential
future structural defects. They can also be used to rehabilitate existing defects such as those found in the
manholes described in Table 26 and Table 27. The liner is typically applied by troweling, spray application, and/or
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centrifugally spin-casting. Cementitious liners, as discussed in the previous section, can also be used to stop
infiltration at manholes. The following process is recommended to be used when using cementitious liners to
rehabilitate manhole defects:
1) Break away any degraded concrete to create a hard surface.
2) Clean and coat any exposed reinforcement.
3) Apply fast setting mortar.
4) Apply SewperCoat or other similar cementitious lining product to defect(s).
7.2.2.3 Chemical Grouting
Chemical grouting is one of the oldest methods for impeding infiltration into sewer systems, including manholes.
Several chemical grouting manufacturers, such as AvantiGrout, can provide a short term (2 to 10-year service life)
product suitable for the rehabilitation of manhole infiltration spots. Typically, chemical grout is only applied to
manholes that are structurally sound unless the grout is being used to prevent water from entering the manhole
during application of a liner such as CIPM liners discussed in Section 7.2.2.1 above. Grout injection holes are
drilled at strategic locations so as to re-direct flow that is infiltrating into the manholes. This is a good reason why
the potential contractors should provide evidence of prior experience with applying chemical grout.
8 Unit Cost for Each RRR Alternative
This section includes discussion of the unit costs assumed for the viable RRR alternatives mentioned previously in
Section 7.
8.1 Pipelines
8.1.1 Repair: Point Repair(s) with Structural CIPP Lining
For the point repairs with structural CIPP lining methodology discussed in Section 7.1.1.2, a unit cost of $435 per
linear foot will be used. This unit cost comes out larger than the comparable “per linear foot” unit cost of the
structural CIPP lining rehabilitation methodology due to the significantly smaller total length of pipeline to be
repaired. Mobilization costs for installing CIPP lining along a handful of different pipeline segments, as opposed
to the full pipe segment CIPP lining of the entire JTP trunk main, are a factor in the difference in unit costs. Also,
the pipelines that will potentially be recommended for this repair methodology are all 36” diameters which also
helps to account for the higher unit cost. This unit cost of $435 per linear foot accounts for the structural lining
material, installation, insertion pits, bedding and backfill, mobilization and demobilization, traffic control,
excavation, bypass pumping, and equipment.
8.1.2 Repair: Point Repair(s) with Open Cut
For the point repair with open cut dig and replace methodology discussed in Section 7.1.1.1, a unit cost of $1,000
per linear foot will be used. This unit cost accounts for excavation, backfill, paving, sheeting/shoring/bracing, pipe
material, installation, mobilization and demobilization, traffic control, bypass pumping, and equipment.
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8.1.3 Rehabilitation: Structural CIPP Lining – Full Pipe Segment
For the structural CIPP lining of full pipe segments rehabilitation methodology discussed in Section 7.1.2.2, a unit
cost of $12 per inch-diameter-foot will be used. This unit cost accounts for the structural lining material,
installation, insertion pits, bedding and backfill, mobilization and demobilization, traffic control, excavation,
bypass pumping, and equipment. The unit cost also accounts for manhole channelization upgrades to eliminate
potential low spots and to smoothen the wastewater flow.
8.1.4 Rehabilitation: Spray Coating
For the spray coating rehabilitation methodology discussed in Section 7.1.2.3, a unit cost of $0.30 per inch-
diameter-foot will be used. This unit cost accounts for the coating material, application, insertion pits, bedding
and backfill, mobilization and demobilization, traffic control, excavation, and equipment.
8.2 Manholes
8.2.1 Repair: Raising Buried Manholes
A unit cost of $4,000 per manhole will be used for estimating the cost of raising the buried manholes identified in
this Report. This unit cost accounts for locating the manhole, excavation, installed materials, bedding and backfill,
mobilization and demobilization, traffic control, and equipment.
8.2.2 Rehabilitation: CIPM Liners
A unit cost of $11 per inch-diameter-vertical foot will be used for estimating the cost of rehabilitating manholes
utilizing CIPM liners. This unit cost accounts for labor, mobilization and demobilization, traffic control, structural
lining material, and equipment.
8.2.3 Rehabilitation: Cementitious Liners
A unit cost of around $110 per vertical foot would typically be for estimating the cost of rehabilitating manholes
utilizing cementitious liners. However, given the limited number of manholes that have significant vertical footage
lengths in need of rehabilitation within the same manhole, a unit cost of $2,675 per manhole will be used. This
unit cost accounts for material, labor, mobilization and demobilization, traffic control, and equipment.
9 RRR Alternatives Assignment
This section entails assigning viable RRR alternative methodologies to pipelines based on an analysis of their Pipe
Capacity Rating, Structural Condition Rating and Overall Risk Rating as previously discussed in Section 6. For the
three siphon pipelines not CCTV inspected during the field assessment, RRR alternative methodologies will be
assigned based on their assumed Structural Condition Rating and Overall Risk Rating (note these segments should
be reevaluated for appropriate RRR alternative based on actual field results from any future CCTV inspection).
The assignment of RRR alternative methodologies to manholes is based on an analysis of their observed defects
(structural and O&M) and field assessment findings.
9.1 Pipelines
Pipelines were assigned viable RRR methodologies based on the decision tree presented in Figure 4 below. For
each pipeline along the trunk main, the steps in the decision tree are followed until one of the four end results is
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reached. The results of the assignment procedure for each pipeline is listed in Table 44 below (listed in order from
upstream to downstream). The table lists the following information:
• Pipeline Facility ID
• Length (feet)
• Pipe Material
• Pipe Diameter (in)
• Pipe Capacity Rating (utilized in decision tree)
• Structural Condition Rating (utilized in decision tree)
• Overall Risk Rating
• Rank
• Structural CIPP Lining viable? “Y” for yes and “N” for no
• Spray Coating viable? “Y” for yes and “N” for no
• Pipe Bursting viable? “Y” for yes and “N” for no
Figure 4: RRR Pipe Assignment Decision Tree
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Table 44: Pipeline RRR Alternatives Assignment
Pipeline Facility ID Length (ft) Material Diameter (in) Pipe Capacity Rating Structural Condition Rating Overall Risk Rating Rank CIPP Spray
Coating Pipe Bursting
MH-1_MH-3 32.8 PVC 18 1 1 1 163 N N N
MH-2_MH-4 37.4 PVC 30 1 1 1 158 N N N
MH-3_MH-5 513.7 VCP 18 1 3 3 91 N N N
MH-4_MH-6 522.5 PVC 30 1 1 2 138 N N N
MH-5_MH-7 488.18 VCP 18 1 3 3 92 N N N
MH-6_MH-8 486.8 PVC 30 1 1 2 139 N N N
MH-7_MH-9 494.28 VCP 18 1 3 2 123 N N N
MH-8_MH-10 493.76 PVC 30 1 1 2 140 N N N
MH-9_MH-11 489.95 VCP 21 1 2 2 133 N N N
MH-10_MH-12 456.1 PVC 30 1 1 2 141 N N N
MH-11_MH-15 120.41 VCP 24 1 2 2 135 N N N
MH-12_MH-13 26.3 PVC 30 1 1 1 159 N N N
MH-13_MH-14 81.9 PVC 30 1 1 1 160 N N N
MH-15_MH-16 397.13 VCP 24 1 2 2 127 N N N
MH-14_MH-17 404.8 PVC 30 1 1 2 147 N N N
MH-16_MH-18 514.49 VCP 24 1 3 3 89 N N N
MH-17_MH-19 514.43 PVC 30 1 1 2 148 N N N
MH-18_MH-21 520.37 VCP 24 1 2 2 128 N N N
MH-19_MH-20 519.02 PE 30 1 1 2 149 N N N
MH-21_MH-21A 253.39 VCP 24 1 3 3 90 N N N
MH-20_MH-22 250.9 PE 30 1 1 2 150 N N N
MH-21A_MH-24 261.4 VCP 24 1 2 2 129 N N N
MH-22_MH-23 260.2 PE 30 1 1 2 151 N N N
MH-24_MH-26 518.1 VCP 24 1 3 3 96 N N N
MH-23_MH-25 522 PE 30 1 1 2 154 N N N
MH-26_MH-27 566.04 VCP 24 1 2 2 130 N N N
MH-25_MH-28 564.4 PE 30 1 1 2 152 N N N
MH-27_MH-29 447.3 VCP 24 1 2 2 124 N N N
MH-28_MH-30 446.6 PE 30 1 1 2 142 N N N
MH-29_MH-32 503.34 VCP 24 1 2 2 125 N N N
MH-30_MH-31 499.8 PE 30 1 1 2 143 N N N
MH-32_MH-33 500.75 VCP 24 1 3 3 88 N N N
MH-31_MH-34 501.4 PE 30 1 1 2 144 N N N
MH-33_MH-36 510.03 VCP 24 1 2 2 131 N N N
MH-34_MH-35 508.2 PE 30 1 2 2 132 N N N
MH-36_MH-38 551.14 VCP 24 1 2 2 126 N N N
MH-35_MH-37 388.7 PE 30 1 1 2 145 N N N
MH-37_MH-39 611.4 PE 30 1 1 2 146 N N N
MH-38_MH-40 455.76 VCP 24 2 2 3 94 N N N
MH-40_MH-41 83.5 VCP 24 2 2 2 136 N N N
MH-39_MH-39A 107.4 PE 30 1 1 1 161 N N N
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Pipeline Facility ID Length (ft) Material Diameter (in) Pipe Capacity Rating Structural Condition Rating Overall Risk Rating Rank CIPP Spray
Coating Pipe Bursting
MH-41_MH-42 12.5 VCP 24 1 1 1 164 N N N
MH-42_MH-44 551.73 VCP 24 2 2 3 95 N N N
MH-39A_MH-43 532.3 PE 30 1 2 2 134 N N N
MH-44_MH-48 556.29 VCP 24 3 3 5 55 N N N
MH-43_MH-46 539.46 PE 30 1 1 2 153 N N N
MH-46_MH-47 28.8 PVC 30 1 1 1 165 N N N
MH-47_MH-48 8.89 PVC 30 1 1 1 162 N N N
MH-48_MH-50 412 PVC 30 1 1 2 137 N N N
MH-50_MH-51 599.64 VCP 24 5 2 5 50 N N N
MH-51_MH-52 593.04 VCP 24 5 2 5 49 N N N
MH-52_MH-53 498.32 VCP 24 3 2 4 77 N N N
MH-53_MH-54 526.24 VCP 27 1 3 4 78 N N N
MH-54_MH-55 473.22 VCP 27 1 2 3 105 N N N
MH-55_MH-56 540.38 VCP 27 1 2 3 106 N N N
MH-56_MH-57 534.31 VCP 27 1 2 3 107 N N N
MH-57_MH-58 534.64 VCP 27 1 2 3 108 N N N
MH-58_MH-59 534.41 VCP 27 1 1 3 118 N N N
MH-59_MH-60 535.26 VCP 27 1 3 4 82 Y N N
MH-60_MH-61 532.74 VCP 27 2 4 5 46 Y Y N
MH-61_MH-62 536.74 VCP 27 1 3 4 83 Y N N
MH-62_MH-63 498.1 VCP 27 1 1 3 121 N N N
MH-63_MH-64 313.73 VCP 24 3 1 3 103 N N N
MH-64_MH-65 581.72 VCP 24 5 2 5 54 N N N
MH-65_MH-66 577.32 VCP 24 5 2 5 53 N N N
MH-66_MH-67 199.32 VCP 24 5 1 4 80 N N N
MH-67_MH-68 487.4 VCP 24 5 1 4 75 N N N
MH-68_MH-69 488.64 VCP 24 5 2 5 51 N N N
MH-69_MH-70 199 VCP 24 5 1 4 79 N N N
MH-70_MH-71 425.2 VCP 24 5 3 5 23 N N N
MH-71_MH-72 424 VCP 24 5 2 5 52 N N N
MH-72_MH-73 423.6 VCP 24 5 1 4 76 N N N
MH-73_MH-74 439.82 VCP 24 4 2 4 70 N N N
MH-74_MH-75 486.2 VCP 24 3 1 3 101 N N N
MH-75_MH-76 487.3 VCP 24 4 1 4 85 N N N
MH-76_MH-77 487 VCP 24 3 1 3 102 N N N
MH-77_MH-78 447.63 VCP 27 2 2 4 86 N N N
MH-78_MH-79 467.84 VCP 27 2 1 3 112 N N N
MH-79_MH-80 457.54 VCP 27 2 1 3 110 N N N
MH-80_MH-81 418.23 VCP 27 2 1 3 111 N N N
MH-81_MH-82 275.51 VCP 27 2 1 3 114 N N N
MH-82_MH-83 442.31 VCP 30 1 1 3 122 N N N
MH-83_MH-84 440.74 VCP 30 1 1 3 119 N N N
MH-84_MH-85 437.72 VCP 30 2 1 3 113 N N N
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Pipeline Facility ID Length (ft) Material Diameter (in) Pipe Capacity Rating Structural Condition Rating Overall Risk Rating Rank CIPP Spray
Coating Pipe Bursting
MH-85_MH-85A 402.12 VCP 30 1 1 3 120 N N N
MH-85A_MH-85B 38.81 VCP 30 1 1 2 156 N N N
MH-85B_MH-86 9.51 VCP 30 1 1 2 157 N N N
MH-86_MH-87 501.53 VCP 30 1 2 3 104 N N N
MH-87_MH-88 511.18 VCP 30 1 2 3 97 N N N
MH-88_MH-89 336.9 RCP 27 1 5 5 16 Y Y N
MH-89_MH-90 235.7 RCP 27 1 4 5 21 Y Y N
MH-90_MH-91 47 RCP 12&18 1 2 2 166 N N N
MH-91_MH-92 99 RCP 12&18 1 2 2 167 N N N
MH-92_MH-93 56 RCP 12&18 1 2 2 168 N N N
MH-93_MH-94 20.4 RCP 27 1 2 3 116 N N N
MH-94_MH-95 134.4 RCP 27 3 3 4 71 Y Y N
MH-95_MH-96 211.23 RCP 27 1 5 5 43 Y Y N
MH-96_MH-96A 310.05 RCP 27 1 5 5 28 Y Y N
MH-96A_MH-97 134.5 RCP 27 1 3 4 68 Y Y N
MH-97_MH-97A 122.4 RCP 27 1 3 4 69 Y Y N
MH-97A_MH-98 321.51 RCP 27 1 5 5 24 Y Y N
MH-98_MH-99 402.68 RCP 27 2 5 5 9 Y Y N
MH-99_MH-100 130.62 RCP 27 1 3 4 67 Y Y N
MH-100_MH-101 395.82 RCP 36 1 5 5 18 Y Y N
MH-101_MH-102 427.42 RCP 36 1 5 5 17 Y Y N
MH-102_MH-102A 310.71 RCP 36 1 2 3 98 N N N
MH-102A_MH-102B 75.89 RCP 36 1 2 3 99 N N N
MH-102B_MH-103 98.4 RCP 36 1 3 4 66 Y Y N
MH-103_MH-104 222.71 RCP 36 5 4 5 7 Y Y N
MH-104_MH-105 340.21 RCP 36 1 5 5 19 Y Y N
MH-105_MH-106 510.62 RCP 36 1 5 5 20 Y Y N
MH-106_MH-107 553.05 RCP 36 1 5 5 31 Y Y N
MH-107_MH-108 596.75 RCP 36 1 5 5 40 Y Y N
MH-108_MH-109 124.91 RCP 36 1 3 3 93 Y Y N
MH-109_MH-110 485.72 RCP 36 1 5 4 61 Y Y N
MH-110_MH-111 211.62 RCP 36 1 4 4 62 Y Y N
MH-111_MH-112 496.55 RCP 36 1 4 4 63 Y Y N
MH-112_MH-113 371.84 RCP 36 1 5 5 36 Y Y N
MH-113_MH-114 351.13 RCP 36 1 5 5 37 Y Y N
MH-114_MH-115 336.83 RCP 36 1 3 4 81 Y Y N
MH-115_MH-116 444.31 RCP 36 1 5 5 38 Y Y N
MH-116_MH-116A 199.42 RCP 36 1 5 5 44 Y Y N
MH-116A_MH-117 151.62 RCP 36 1 5 5 45 Y Y N
MH-117_MH-118 307.23 RCP 36 1 5 5 29 Y Y N
MH-118_MH-119 462.46 RCP 36 1 5 5 30 Y Y N
MH-119_MH-120 206.7 RCP 36 1 2 3 115 N N N
MH-120_MH-121 193.51 RCP 36 1 2 3 109 N N N
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Pipeline Facility ID Length (ft) Material Diameter (in) Pipe Capacity Rating Structural Condition Rating Overall Risk Rating Rank CIPP Spray
Coating Pipe Bursting
MH-121_MH-122 532.15 RCP 36 1 3 4 84 N N N
MH-122_MH-123 534.84 RCP 36 2 3 4 74 Y Y N
MH-123_MH-125 398.54 RCP 36 1 5 5 39 Y Y N
MH-125_MH-126 498.12 RCP 36 1 5 5 32 Y Y N
MH-126_MH-127 510.46 RCP 36 1 5 4 58 Y Y N
MH-127_MH-128 511.05 RCP 36 1 5 4 59 Y Y N
MH-128_MH-130 596.03 RCP 36 1 5 4 60 Y Y N
MH-130_MH-131 595.2 RCP 36 1 4 4 64 Y Y N
MH-131_MH-132 484.6 RCP 36 1 5 5 35 Y Y N
MH-132_MH-133 518.3 RCP 36 1 3 4 65 Y Y N
MH-133_MH-134 492.45 RCP 36 1 5 5 41 Y Y N
MH-134_MH-134A 53.8 RCP 36 1 2 3 117 N N N
MH-134A_MH-135 559.2 RCP 36 1 5 5 33 Y Y N
MH-135_MH-136 379.8 RCP 36 2 5 5 13 Y Y N
MH-136_MH-137 60.5 RCP 36 3 2 4 87 N N N
MH-137_MH-138 172.12 RCP 36 1 5 5 47 Y Y N
MH-138_MH-138A 308.1 RCP 36 1 5 5 34 Y Y N
MH-138A_MH-139 226.7 RCP 36 4 3 5 42 Y Y N
MH-139_MH-140 577.8 RCP 36 2 5 5 14 Y Y N
MH-140_MH-141 578.3 RCP 36 2 5 5 15 Y Y N
MH-141_MH-142 406.6 RCP 36 2 4 5 48 Y Y N
MH-142_MH-142A 60.7 RCP 36 4 3 5 57 Y Y N
MH-142A_MH-142B 122.6 RCP 36 4 4 5 22 Y Y N
MH-142B_MH-142C 223.99 RCP 36 4 5 5 2 Y Y N
MH-142C_MH-142D 336.5 RCP 36 4 5 5 3 Y Y N
MH-142D_MH-142E 150.8 RCP 36 4 5 5 6 Y Y N
MH-142E_MH-142F 283 RCP 36 4 5 5 4 Y Y N
MH-142F_MH-143 523.9 RCP 36 4 5 5 5 Y Y N
MH-143_MH-144 485.6 RCP 36 1 5 5 25 Y Y N
MH-144_MH-145 63.9 RCP 36 1 3 3 100 Y Y N
MH-145_MH-146 560.9 RCP 36 2 5 5 10 Y Y N
MH-146_MH-147 206.05 RCP 36 1 5 5 26 Y Y N
MH-147_MH-148 199.2 RCP 36 5 5 5 1 Y Y N
MH-148_MH-149 196.8 RCP 36 1 4 4 72 Y Y N
MH-149_MH-150 80.29 RCP 36 1 4 4 73 Y Y N
MH-150_MH-151 608.6 RCP 36 2 5 5 11 Y Y N
MH-151_MH-152 603.2 RCP 36 2 5 5 12 Y Y N
MH-152_MH-153 392.51 RCP 36 3 5 5 8 Y Y N
MH-153_MH-154 327.2 RCP 36 1 5 5 27 Y Y N
MH-154_MH-155 10.6 RCP 36 1 2 2 155 N N N
MH-155_MH-156 207.2 RCP 42 5 2 5 56 N N N
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Table 45 below lists the pipeline that was found to have significant structural defects that are in need of immediate
rehabilitation.
Table 45: Pipelines with Structural Defects Requiring Immediate Rehabilitation
Facility ID RRR Alternative Reason for Recommendation
MH-116_MH-116A
Open Cut Point Repair
(replace roughly 35 LF of
pipe from
approximately 19’ to 54’
downstream of MH-116)
(1) SMW – Missing Wall
10 LF of continuous SMW – Missing Wall
(1) SRP – Reinforcement Projecting
Table 46 below lists the pipelines that were found to have significant I&I-related defects that are in need of
immediate rehabilitation. All four (4) of the pipelines are recommended for eventual full pipe length structural
CIPP lining rehabilitation due to the widespread structural degradation of the reinforced concrete pipe sections
of the JTP trunk main (i.e. from MH-88 to the SCRWA WWTP), and thus are recommended for immediate structural
CIPP lining rehabilitation in order to complete that work in advance.
Table 46: Pipelines with I&I Defects Requiring Immediate Rehabilitation
Facility ID RRR Alternative Reason for Recommendation
MH-153_MH-154
Structural CIPP Lining
(Full Pipe Segment)
(1) IGB – Infiltration Gusher, Barrel (Grade 5 Severity)
MH-145_MH-146 (2) IRB – Infiltration Runner, Barrel (Grade 4 Severity)
MH-146_MH-147 (1) IRB – Infiltration Runner, Barrel (Grade 4 Severity)
MH-152_MH-153 (1) IR – Infiltration Runner (Grade 4 Severity)
9.2 Manholes
This section lists the manholes that were found to be in need of repair, rehabilitation, or replacement based on
observed defects and field assessment findings. Table 47 below lists these manholes along with their RRR
alternative(s) and reason for recommendation.
Table 47: Manhole RRR Alternatives Assignment
Facility ID RRR Alternative Reason for Recommendation
MH-66
Repair: Raising Buried
Manholes
These manholes were found to be buried during
the field assessment. In order to allow for
proper and adequate access for future O&M
and/or construction activities, these manholes
are recommended to be raised flush with
ground level.
MH-127
MH-128
MH-137
MH-138
MH-138A
MH-142A
MH-142B
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Facility ID RRR Alternative Reason for Recommendation
MH-123
Rehabilitation:
Cementitious Liners
or
Rehabilitation:
CIPM Liner
These manholes were observed to have either
Grade 5 or Grade 4 structural defects.
Therefore, these manholes are recommended
for rehabilitation through the use of a
cementitious liner or CIPM liner.
MH-130
MH-75
MH-29
MH-41
MH-87
MH-147
MH-146
MH-68
MH-120
MH-55
MH-70
MH-99
MH-32
MH-122
MH-97A
MH-102A
MH-109
MH-139
MH-64
MH-102B
MH-94
MH-101
MH-60
MH-144
MH-16
MH-93
MH-36
MH-119
MH-4
MH-149
MH-31
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10 Proposed Improvement Project Bundling/Phasing & Analysis
This section contains discussion of the analysis performed to determine feasible project bundling/phasing
alternatives. As mentioned previously in Section 5.1, the JT-P2 through JT-P9 improvement projects are required
to address the capacity deficiencies identified in the City’s SSMP. The following topics were used to determine
comparable project bundling approaches.
Construction Methodology Feasibility
As it pertains to the RRR methodologies to address the widespread structural degradation along the RCP portions
of JTP trunk main, structural CIPP lining and spray coating are considered feasible. Pipe bursting is not feasible for
the RCP portions of the JTP trunk main because pipe bursting of reinforced concrete pipe is difficult/experimental
and in many cases not feasible, and the concern for potential heaving of the various crop fields/roads/commercial
areas would make the construction process slow with a high probability of failure and/or significant surface
damage and unsafe conditions for the general public. For this reason, pipe bursting would not be considered
feasible for addressing the trunk main’s structurally degraded portions.
While the microtunneling and open cut replacement methodologies are technically feasible to address the
structural degradation found along the JTP trunk main, the significantly higher associated costs and overall public
disturbance when compared to the aforementioned structural CIPP lining and spray coating methodologies
effectively rule out their potential for recommendation. Also, the extent to which the RCP portions of the JTP
trunk main have become degraded does not preclude the host pipe’s ability to continue to serve as a trunk main
for the City should a rehabilitation methodology be employed to extend its useful life. For these reasons, the
structural CIPP lining and spray coating rehabilitation methodologies will be included in the proposed
improvement project bundling and phasing options.
Capacity
Due to the planned continued use of the existing JTP trunk main even after the relief trunk JT-P2 through JT-P9
capacity improvement projects are constructed, any methodology employed to address the structural
degradation along the JTP trunk main needs to account for impacts on conveyance capacity. To that end, the
relatively low impact on conveyance capacity stemming from structural CIPP lining and/or spray coating of the JTP
trunk main was an important factor in the decision to recommend their potential implementation in the future.
While structural CIPP lining obviously decreases the inside diameter of the JTP trunk main once installed, the
smoother profile (and thereby smaller friction losses when analyzing conveyance capacity) can effectively offset
the loss of inside diameter. Lastly, spray coating is typically applied to a thickness of about 100-125 mils (or 0.1
to 0.125 inches), which will likely not negatively affect the conveyance capacity of the JTP trunk main to the point
where the JT-P2 through JT-P9 capacity improvement projects would become insufficient/undersized.
Capacity Project Cost Review
When looking at the cost estimates in the City’s SSMP for the aforementioned JT-P2 through JT-P9 capacity
improvement projects, the unit costs utilized appear to adequately account for the degree of difficulty of
constructing the various projects along the selected route. Therefore, when estimating the costs of the
approaches subsequently in this section, the original cost estimates will be utilized as the starting basis and will
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be escalated utilizing ENR’s 20-city national average Construction Cost Index values (i.e. a roughly 2% increase per
year from the original estimate).
Two variations of project bundling/phasing approaches were analyzed, with the following sub-sections discussing
the approaches determined to be feasible, comparatively costed (with similar feasibility profiles and level of risk
contingencies included), and addressing the structural degradation of the JTP trunk main. Two alternatives were
developed, analyzed, and grouped into two separate sections, the first being “Emergency/Immediate Projects”
and the second being “Intermediate Projects”. These included improvements to address existing and future
buildout planning horizon capacity related problems identified in the SSMP combined with improvements
required to address emergency (0-2 year) and intermediate (2-10 year) condition deficiencies identified during
the project field work. An emergency/immediate project to address significant existing structural deficiencies and
raise buried manholes will be constructed in the next 2-years. To address the remainder of the capacity and
condition deficiencies, two phasing approaches were analyzed.
“All-at-Once” assumed all of the projects addressing the structural condition deficiencies and existing and future
planning horizon capacity deficiencies (i.e. JT-P2 through JT-P9) would be constructed within a 5-year period as a
single intermediate project.
“Phased” assumed all of the projects addressing the structural condition deficiencies would be constructed over
a 2 to 15-year period as a multi-phased immediate/intermediate project. However, the JT-P2 through JT-P9
capacity improvement projects would still be constructed within a 5-year period due to the City’s SSMP originally
recommending these projects to begin in 2018. This approach required additional emergency/immediate
improvements (i.e. crown spraying of lines with condition deficiencies that are being phased).
The project bundling options are described below and their associated cost estimates in Section 12.
10.1 “All-at-Once” Approach
Providing there are no schedule and/or budgetary constraints, the various components of the overall project are
recommended to be completed all at the same time. This provides the most expedient approach to address the
high-risk structural defects with a methodology that will extend the trunk main’s useful life by 30-50 years for
rehabilitated pipe segments and 50-75 years for new pipes.
Structural CIPP Lining & JT-P2 through JT-P9 – All-at-Once
The “Emergency/Immediate Projects” (0-2 years) include the following:
• Structural CIPP lining and/or open cut replacement of the pipelines found to be in need of point repairs
(see Appendix G)
• Manhole RRR activities (as discussed in Section 9.2)
The “Intermediate Projects” (2-5 years) include the following:
• Structural CIPP lining of all assigned pipelines (see Section 9.1 and Appendix H)
• Capacity Improvement Projects JT-P2 through JT-P9
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10.2 Phasing Approach
If the “All-at-Once” approach cannot be implemented due to City identified constraints, a combination of
structural CIPP lining and crown spray coating could be completed. Note after completion of the phased approach,
service life expectancies similar to the “All-at-Once” approach would be met.
Structural CIPP Lining & CIP-6 with Microtunneling – Phased
The “Emergency/Immediate Projects (Years 0-2)” include the following:
• Structural CIPP lining and/or open cut replacement of the pipelines found to be in need of point repairs
(see Appendix G)
• Spray coating of all assigned pipelines (see Section 9.1)
• Manhole RRR activities (as discussed in Section 9.2)
The “Immediate/Intermediate Projects (Years 2-5 years)” include the following:
• Structural CIPP lining of all assigned pipelines (see Section 9.1) DS of MH-130
• Spray coating re-application of assigned pipelines (see Section 9.1) US of MH-130
• Capacity Improvement Projects JT-P2 through JT-P9
The “Intermediate/15-YR Projects (Years 5-15)” include the following:
• Spray coating re-application of assigned pipelines (see Section 9.1) US of MH-130
• Structural CIPP lining of all assigned pipelines (see Section 9.1) US of the “CIP-6” capacity project
11 O&M Recommendations
Due to past discussions with City staff regarding historical cleaning regimens/programs employed for the JTP trunk
main, WWE recommends that the City perform periodic cleaning of the JTP trunk main on a more regular basis
(i.e. once every 3-5 years). This will ensure that the vital JTP trunk main is maintained properly so that the City
can continue to sufficiently convey wastewater flows while reducing the potential for O&M-related SSOs and
associated costs. In addition, due to the visual inspection performed on the siphon barrel pipe segments near the
intersection of Wren Avenue and La Primavera Way, WWE recommends that these also be cleaned on a more
regular basis (similarly, once every 3-5 years) to ensure continued function performance for the only siphon along
the JTP trunk main.
12 Construction Cost Estimates
Planning level construction cost estimates were prepared for the project bundles previously described in Section
10. Table 51 below lists the associated appendices and total construction cost opinion for the aforementioned
project bundles.
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Table 48: Cost Estimate Comparison
Approach Project Bundle Appendix Total Construction
Cost Opinion
All-at-
Once Structural CIPP Lining & JT-P2 through JT-P9 Appendix E $47.1 Million
Phased Structural CIPP Lining & JT-P2 through JT-P9 Appendix F $47.8 Million
13 Recommended Project
Based on previous discussion regarding construction methodology feasibility, capacity, and the costs shown in
Table 51, the project bundle “Structural CIPP Lining & JT-P2 through JT-P9 – All-at-Once” is the recommended
project. Not only is this project bundle the least expensive, but it also addresses the structurally degraded portions
of the JTP trunk main in the quickest fashion. If this All-at-Once approach is not feasible based on City-identified
constraints (i.e. funding, schedule), the phased approach for the project bundle “Structural CIPP Lining & JT-P2
through JT-P9– Phased” is recommended.
The recommended project bundle “Structural CIPP Lining & JT-P2 through JT-P9 – All-at-Once” is broken down
into two separate groups of various RRR projects, as shown in Appendix E. The first group of
“Emergency/Immediate Projects” is comprised of pipeline and manhole work, with Table 52 below summarizing
the RRR activities for each asset. Appendix G contains a figure that graphically illustrates the
“Emergency/Immediate Projects”.
Table 49: Recommended Emergency/Immediate Projects
Asset Facility ID RRR Activity Note(s)
MH-116_MH-116A Open Cut Point Repair
36”; replace roughly 35 LF of pipe from
approximately 19’ to 54’ downstream
of MH-116
MH-153_MH-154
Structural CIPP Lining
(Full Pipe Segment)
36”
MH-145_MH-146 36”
MH-146_MH-147 36”
MH-152_MH-153 36”
MH-66
Repair: Raising Buried
Manholes
These manholes were found to be
buried during the field assessment. In
order to allow for proper and adequate
access for future O&M and/or
construction activities, these manholes
are recommended to be raised flush
with ground level.
MH-127
MH-128
MH-137
MH-138
MH-138A
MH-142A
MH-142B
MH-123
Rehab: Cementitious Liners
These manholes were observed to
have either Grade 5 or Grade 4
structural defects. Therefore, these
MH-130
MH-75
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Asset Facility ID RRR Activity Note(s)
MH-29 manholes are recommended for
rehabilitation through the use of a
cementitious liner or CIPM liner.
MH-41
MH-87
MH-147
MH-146
MH-68
MH-120
MH-55
MH-70
MH-99
MH-32
MH-122
MH-97A
MH-102A
MH-109
MH-139
MH-64
MH-102B
MH-94
MH-101
MH-60
MH-144
MH-16
MH-93
MH-36
MH-119
MH-4
MH-149
MH-31
The second group of “Intermediate Projects” aims to address the structural degradation of the trunk main through
structural CIPP lining. Also included are the capacity Improvement projects JT-P2 through JT-P9 as previously
discussed in 5.1. Table 53 below lists the pipelines that are recommended to be structurally lined with CIPP.
Appendix H contain a figure that graphically illustrates the “Intermediate Projects”.
Table 50: Recommended Immediate/Intermediate Projects
Pipeline Facility ID RRR Activity Note(s)
From MH-59 to MH-62
Structural CIPP
Total Length: 1,605 ft
From MH-88 to MH-90 Total Length: 573 ft
From MH-94 to MH-102 Total Length: 2,591 ft
From MH-102B to MH-119 Total Length: 6,265 ft
From MH-122 to MH-134 Total Length: 5,140 ft
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Pipeline Facility ID RRR Activity Note(s)
From MH-134A to MH-136 Total Length: 939 ft
From MH-137 to MH-154 Total Length: 7,695 ft
14 Potential Constraints of Recommended Methodology
14.1 Permits
The following are potential permits that could be required for construction of these project alternatives
dependent on final selected alignment and construction methodology:
• California Department of Transportation Encroachment Permit
• Santa Clara County and City of Gilroy Encroachment Permits
• US Army Corps of Engineers Section 404 Permit (Miller Slough)
• Regional Water Quality Control Board 401 Water Quality Certification (if contaminated water is
encountered or CIPP curing water is pretreated prior to discharge)
14.2 Environmental Considerations
Examples of environmental considerations for structural CIPP lining include noise, dust, and California
Environmental Quality Act (CEQA) and National Environmental Policy Act (NEPA) compliance documentation. It
is anticipated that the condition related work could be conducted as a categorical exemption (CatEx) or initial
study and mitigated or negative declaration (IS M/ND). However, the capacity related project would likely require
an ISMND.
14.3 Utility Coordination
Due to the potential for conflicting existing utilities, the project should follow the ABC Process as agreed upon by
the American Public Works Association (APWA) Joint Utilities Coordination Committee to collect Quality A Level
information as defined by the ASCE Standard 38-02 for Collection and Depiction of Existing Subsurface Utility Data.
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15 Appendices
15.1 Appendix A – Summary of Pipeline Work Completed
15.2 Appendix B – Pipeline Structural Quick Ratings
15.3 Appendix C – Pipeline Maintenance Quick Ratings
15.4 Appendix D – Pipeline Overall Risk Ratings
15.5 Appendix E – Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 – All-at-Once
15.6 Appendix F – Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 – Phased
15.7 Appendix G – Recommended Emergency/Immediate Projects
15.8 Appendix H – Recommended Intermediate Projects
15.9 Appendix I – Mapbook, Pipeline Inspection Findings
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Appendix A – Summary of Pipeline Work Completed
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Summary of PipelineWork Completed
Appendix A
Joint Trunk PipelineCondition Assessment ReportLegend
CCTV & Cleaning
Abandoned
No CCTV/Cleaning
Work Description
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Wren
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SR-152
SCRWA WWTP
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Appendix B – Pipeline Structural Quick Ratings
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StructuralQuick Ratings
Appendix B
Joint Trunk PipelineCondition Assessment Report
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Legend
5000 - 5999
4000 - 4999
3000 - 3999
2000 - 2999
1000 - 1999
0000
Not Inspected
Structural Quick Rating Agenda Item 9.1
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Appendix C – Pipeline Maintenance Quick Ratings
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MaintenanceQuick Ratings
Appendix C
Joint Trunk PipelineCondition Assessment Report
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Legend
5000 - 5999
4000 - 4999
3000 - 3999
2000 - 2999
1000 - 1999
0000
Not Inspected
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Appendix D – Pipeline Overall Risk Ratings
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Overall RiskRatings
Appendix D
Joint Trunk PipelineCondition Assessment Report
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SR-152
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LegendOverall Risk Rating
5
4
3
2
1
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Appendix E – Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 – All-at-Once
Agenda Item 9.1
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Quantity Unit Total Cost
Emergency/Immediate Projects
Pipelines
MH-116_MH-116A (Open Cut Point Repair)35 LF $35,000
MH-145_MH-146 (Structural CIPP)561 LF $244,035
MH-146_MH-147 (Structural CIPP)206 LF $89,610
MH-152_MH-153 (Structural CIPP)393 LF $170,955
MH-153_MH-154 (Structural CIPP)327 LF $142,245
Manholes
Repair: Raising Buried Manholes 8 EA $32,000
Rehabilitation: Cementitious Liners 32 EA $125,675
$839,500
Immediate/Intermediate Projects
Structural CIPP Lining*24807 LF $10,290,723
Capacity Improvement Projects: JT-P2 thru JT-P9**1 LS $22,473,992
*based on $12/in-dia-ft for structural liner
**excalated from original City SSMP estimate using ENR CCI Index $32,800,000
Note: All costs are in 2021 Dollars.
Subtotal, Emergency/Immediate Projects (years 0-2)$839,500
Subtotal, Immediate/Intermediate Projects (years 2-5)$32,800,000
Project SUBTOTAL $33,640,000
Design (Emergency/Immediate)15%$125,925
Design (Intermediate)10%$3,280,000
Design Contingency 15%$5,046,000
Construction Contingency 15%$5,046,000
TOTAL PROJECT COST ESTIMATE (WWE AND JT-P2 thru JT-P9) to the nearest $10,000 $47,100,000
Project:Morgan Hill Joint Trunk Pipeline
Computed By: ARB 1/15/21
Checked By:MJF 1/15/21
$4,000
APPENDIX E - Project Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 -
All-at-Once
Unit Cost
$1,000
$435
$435
$435
$435
$4,000
$415
$22,473,992
Subtotal
Subtotal
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Appendix F – Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 – Phased
Agenda Item 9.1
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Quantity Unit Total Cost
Emergency/Immediate Projects (Years 0-2)
Pipelines
MH-116_MH-116A (Open Cut Point Repair)35 LF $35,000
MH-145_MH-146 (Structural CIPP)561 LF $244,035
MH-146_MH-147 (Structural CIPP)206 LF $89,610
MH-152_MH-153 (Structural CIPP)393 LF $170,955
MH-153_MH-154 (Structural CIPP)327 LF $142,245
Spray Coat 24807 LF $257,268
Manholes
Repair: Raising Buried Manholes 8 EA $32,000
Rehabilitation: Cementitious Liners 32 EA $125,675
$1,096,800
Intermediate Projects (Years 2-5)
Structural CIPP Lining* (DS of MH-130)10725 LF $4,633,161
Spray Coat (re-application of pipes US of MH-130)14082 LF $141,439
Capacity Improvement Projects: JT-P2 thru JT-P9**1 LS $22,473,992
*based on $12/in-dia-ft for structural liner
**excalated from original City SSMP estimate using ENR CCI Index $27,200,000
Note: All costs are in 2021 Dollars.
Subtotal, Emergency/Immediate Projects (years 0-2)$1,096,800
Subtotal, Immediate/Intermediate Projects (years 2-5)$27,200,000
Project SUBTOTAL $28,297,000
Design (Emergency/Immediate)15%$164,520
Design (Immediate/Intermediate)10%$2,720,000
Design Contingency 15%$4,244,550
Construction Contingency 15%$4,244,550
YEARS 0-5 COST ESTIMATE (WWE AND JT-P2 thru JT-P9) to the nearest $10,000 $39,700,000
Intermediate/15-YR Projects (Years 5-15)
Spray Coat (re-application of pipes US of MH-130)14082 LF $141,439
Structural CIPP Lining* (US of MH-130)14082 LF $5,657,562
*based on $12/in-dia-ft for structural liner
$5,800,000
Subtotal, Intermediate/15-YR Phase Projects (years 10-15)$5,800,000
Design (Intermediate/15-YR Phase Projects)10%$580,000
Design Contingency 15%$870,000
Construction Contingency 15%$870,000
YEARS 10-15 COST ESTIMATE (WWE AND CIP-6 15-YR PHASE) to the nearest $10,000 $8,100,000
TOTAL PROJECT COST ESTIMATE (WWE AND CIP-6) to the nearest $10,000 $47,800,000
APPENDIX F - Project Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 -
Phased
Unit Cost
Project: Morgan Hill Joint Trunk Pipeline
Computed By: ARB 1/15/21
Checked By: MJF 1/15/21
$1,000
$435
$435
$10.37
$4,000
$435
Subtotal
$435
$10.04
Subtotal
$432
$10.04
$22,473,992
Subtotal
$402
$4,000
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Appendix G – Recommended Emergency/Immediate Projects
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RecommendedEmergency/ImmediateProjects
Appendix G
Joint Trunk PipelineCondition Assessment Report
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Legend
MH RRR Activity
Raise Buried MH
Pipe RRR Activity
Structural CIPP
All Other Pipes
Cast-in-Place Liner/Cement Liner
Open Cut Point Repair
Open Cut Point Repair
MH-116_MH-116A
(Replace 35 LF of Pipe from
~19' to ~54' Downstream of
MH-116)
Structural CIPP Lining
(Full Pipe Segment)
MH-145_MH-146
&
MH-146_MH-147
Structural CIPP Lining
(Full Pipe Segment)
MH-152_MH-153
&
MH-153_MH-154
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Appendix H – Recommended Intermediate Projects
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RecommendedIntermediateProjects
Appendix H
Joint Trunk PipelineCondition Assessment Report
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Legend
CIPP
Continue O&M Program
Structural CIPP
MH-59
to
MH-62
Structural CIPP
MH-88
to
MH-90
Structural CIPP
MH-94
to
MH-102
Structural CIPP
MH-102B
to
MH-119
Structural CIPP
MH-122
to
MH-134
Structural CIPP
MH-134A
to
MH-136
Structural CIPP
MH-137
to
MH-154
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Appendix I –Mapbook, Pipeline Inspection Findings
Agenda Item 9.1
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Table ES.4 Capital Improvement Program Sewer System Master Plan City of GilroyPipeline ImprovementsInfrastructure CostsSuggested Cost AllocationCost AllocationExisting DiameterNew/Parallel/ReplaceDiameter Length Unit Cost Infr. CostExistingUsersFutureUsersExistingUsersFutureUsers(in)(in)(ft)($)($)($)($)($)(gpm)(%)(%)($)($)Gravity Main ImprovementsSanta Teresa - Long Meadow SubtrunkSLP-1Gravity Main Santa Teresa BlvdFrom Sunrise Dr to Longmeadow Dr10 Replacement 12 2,025 332 671,321 671,400 872,900 1,134,800 954 EDU 61% 39% 689,302 445,498 Subtotal - Santa Teresa - Long Meadow Subtrunk 671,400 872,900 1,134,800689,302 445,498Welburn SubtrunkWP-1Gravity MainWelburn AveFrom Chiesa Dr to Aspen Wy10Replacement12 1,700 332 563,578 563,600 732,700952,600Existing Deficiency90% 10% 861,52091,080WP-2Gravity MainWelburn AveFrom Church St to Hanna St10Replacement12 750 332 248,637 248,700 323,400420,500Existing Deficiency91% 9% 384,53135,969 Subtotal - Welburn Subtrunk 812,300 1,056,100 1,373,1001,246,051 127,049Forest-Swanston SubrunkFP-1Gravity Main Ioof AveFrom Monterey Rd to Forest Ave10 Replacement 12 1,150 332 381,244 381,300 495,700 644,500Existing Deficiency93% 7% 601,483 43,017FP-2Gravity MainForest St From Lewis St to Old Gilroy St12 Replacement 15 1,875 360 675,064 675,100 877,700 1,141,100Existing Deficiency96% 4% 1,093,639 47,461 Subtotal - Forest-Swanston Subrunk 1,056,400 1,373,400 1,785,6001,695,122 90,478Old Gilroy SubtrunkOP-1Gravity Main Old Gilroy StFrom 75' w/o Railroad St to Railroad St10 Replacement 12 100 332 33,152 33,200 43,200 56,200Existing Deficiency89% 11% 50,159 6,042OP-2Gravity MainOld Gilroy St From Railroad St to Forest St12 Replacement 15 750 360 270,026 270,100 351,200 456,600Existing Deficiency89% 11% 407,516 49,085 Subtotal - Old Gilroy Subtrunk 303,300 394,400 512,800457,674 55,126Uvas Park SubtrunkUP-1Gravity Main Uvas Park DrFrom 3rd St to 350 ft e/o Santa Barbara Dr- New 12 2,375 332 787,352 787,400 1,023,700 1,330,900Existing Deficiency39% 61% 517,772 813,128UP-2Gravity MainHoxett St / ROW From Wren Ave to Miller Ave12 Replacement 18 1,550 389 602,255 602,300 783,000 1,017,900 2,020 EDU 36% 64% 370,355 647,545UP-3Gravity MainYorktown Dr From Miller Ave to Greenwich Dr12 Replacement 18 1,725 389 670,252 670,300 871,400 1,132,900 1,923 EDU 38% 62% 427,260 705,640UP-4Gravity MainGreenwich Dr From Yorktown Dr to Orchard Dr12 Replacement 18 575 389 223,417 223,500 290,600 377,800 2,152 EDU 38% 62% 145,055 232,745UP-5Gravity MainOrchard Dr From Greenwich Dr to W 10th St12 Replacement 18 200 389 77,710 77,800 101,200 131,600 2,401 EDU 39% 61% 51,307 80,293UP-6Gravity MainW 10th St From Orchard Dr to Princevalle St12 Replacement 18 1,350 389 524,545 524,600 682,000 886,600 3,085 EDU 39% 61% 346,721 539,879 Subtotal - Uvas Park Subtrunk 2,885,900 3,751,900 4,877,7001,858,470 3,019,230Thomas SubtrunkTP-1Gravity MainLondon Pl From Monterey Rd to Princevalle St 18 Replacement21 2,775 418 1,160,665 1,160,700 1,509,000 1,961,700 5,873 EDU 62% 38% 1,224,966 736,734TP-2Gravity MainMonterey Rd From Luchessa Ave to London Pl 18 Replacement21 1,525 418 637,843 637,900 829,300 1,078,100 5,303 EDU 62% 38% 672,095 406,005 Subtotal - Thomas Subtrunk 1,798,600 2,338,300 3,039,8001,897,061 1,142,739Total Costs Subtotal - Santa Teresa - Long Meadow Subtrunk671,400 872,900 1,134,800689,302 445,498 Subtotal - Welburn Subtrunk812,300 1,056,100 1,373,1001,246,051 127,049 Subtotal - Forest-Swanston Subrunk1,056,400 1,373,400 1,785,6001,695,122 90,478 Subtotal - Old Gilroy Subtrunk303,300 394,400 512,800457,674 55,126 Subtotal - Uvas Park Subtrunk2,885,900 3,751,900 4,877,7001,858,470 3,019,230 Subtotal - Thomas Subtrunk1,798,600 2,338,300 3,039,8001,897,061 1,142,739Total Improvement Costs 7,527,900 9,787,000 12,723,8007,843,6814,880,1193/28/2023Notes : ϭ͘Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,ϭϳϲ;DĂƌĐŚϮϬϮϯͿ͘Ϯ͘Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.ϯ͘Estimated construction cost plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal costs.Capital Improv. Cost 3Construction TriggerImprov. No.Type of ImprovementAlignmentLimitsBaseline Constr. Costs 1Estimated Const. Costs 2Agenda Item 9.1Page 489 of 768
RESOLUTION NO. 2023-XX
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF
GILROY ADOPTING THE SEWER SYSTEM MASTER
PLAN FOR THE CITY OF GILROY
WHEREAS, the 2022 Sewer System Master (Plan) serves as a guide to assess
the current operations and functionality of the City’s existing sewer system; and
WHEREAS, the City last developed a Sewer System Master Plan in 2004, which
identified capacity deficiencies in the existing sewer system and recommended
improvements to alleviate existing deficiencies and serve future developments in the
Gilroy Planning Area; and
WHEREAS, Akel Engineering Group, Inc. was retained by the City Council in
August 2019 to prepare the Plan; and
WHEREAS, the objective of the Plan is to review and make recommendations on
how the current sewer system can be upgraded within the City to best suit the sewer
needs of the City in the future; and
WHEREAS, the projects identified in the Plan will be added to the City’s Capital
Improvement Program; and
NOW, THEREFORE, BE IT RESOLVED that the City Council of the City of Gilroy
hereby adopts the Sewer System Master Plan attached hereto and made a part hereof.
PASSED AND ADOPTED by the City Council of the City of Gilroy at a regular
meeting duly held on the 3rd day of April 2023 by the following roll call vote:
AYES: COUNCIL MEMBERS:
NOES: COUNCIL MEMBERS:
ABSTAIN: COUNCIL MEMBERS:
ABSENT: COUNCIL MEMBERS:
APPROVED:
Marie Blankley, Mayor
ATTEST:
_______________________
Thai Nam Pham, City Clerk
Agenda Item 9.1
Page 490 of 768
Page 1 of 5
City of Gilroy
STAFF REPORT
Agenda Item Title:Adopt the 2022 Water Master Plan
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:Public Works
Submitted By:Daryl Jordan, Public Works Director
Prepared By:Michael Lewis, Management Analyst
STRATEGIC PLAN GOALS Maintain and Improve City Infrastructure
RECOMMENDATION
Adopt a resolution approving the 2022 Water System Master Plan.
BACKGROUND
Cities rely on water master plans to assess the current operations and functionality of
the City’s existing water system and to help meet the future water needs of the
community. The City last developed a water master plan in 2004 which identified
capacity deficiencies in the existing water system and recommended improvements to
alleviate existing deficiencies and serve future developments in the Gilroy Planning
Area.
The City operates and maintains a domestic water system that covers most of the area
within the service area limits. Currently, the water demands are provided from
groundwater wells located throughout the service area. The City’s municipal water
system consists of nine (9) groundwater wells, ten (10) storage reservoirs that have a
cumulative capacity of 14.1 million gallons (MG), and over approximately 202 miles of
distribution pipelines. The City’s generally flat topography slopes up from east to west at
approximately 180 feet above sea level in the east to approximately 250 feet above sea
level in the west. Even with this generally flat topography, the City utilizes three
separate pressure zones due to the slopes on the west side.
The City’s most recent water master plan was completed in 2004. This Master Plan
Agenda Item 9.2
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included an evaluation of servicing growth to the planning area, evaluated existing
demands and projected future demands, evaluated groundwater conditions and
management, and recommended phased improvements to the water system for the
horizon year of 2040 to be consistent with the recently updated 2040 General Plan,
state-approved Urban Water Management Plan (UWMP) and Water Service
Contingency Plan (WSCP). This 2020 WSCP document builds upon previous water
shortage contingency planning efforts completed by the City and documented in the
2015 UWMP Plans. Additionally, the 2004 Master Plan included the development of the
original hydraulic model, which was then used for evaluating the water
system. Improvements were recommended for servicing existing and future growth
areas, and a corresponding Capital Improvement Program was developed to quantify
construction costs. There were 12 water main segments out of 73 potential projects
constructed from the 2004 Master Plan at a total cost of $6,923,000.
Due to the increased demand for water, it became evident that an updated water master
plan was necessary. As such, the City Council approved Akel Engineering Group, Inc.
to prepare the 2022 Water Master Plan and a concurrent Sewer System Master Plan
and Storm Drainage Master Plan in August 2019. These documents were coordinated
for consistency with the City’s 2040 General Plan.
ANALYSIS
The 2022 Water System Master Plan (Plan) evaluates the City’s domestic water system
and recommends capacity improvements necessary to service the needs of existing
users and for servicing the future growth of the city. The Plan is intended to serve as a
tool for planning and phasing the construction of future domestic water system
infrastructure for the projected buildout of the City’s service area.
The City Council authorized Akel Engineering Group, Inc. to perform the following tasks:
1. Summarize the City’s existing domestic water system facilities.
2. Document growth planning assumptions and known future developments.
3. Summarize the water system performance criteria.
4. Project future domestic water demands.
5. Update and validate the City’s hydraulic model based on the City’s Geographic
Information System (GIS).
6. Evaluate the domestic water facilities to meet existing and projected demand
requirements and fire flows.
7. Evaluate existing groundwater conditions.
8. Perform a capacity analysis for major distribution mains.
9. Recommend a Capital Improvement Program (CIP) with an opinion of probable
construction costs.
10. Develop a 2022 Water System Master Plan report.
Agenda Item 9.2
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Adopt the 2022 Water Master Plan
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RESULTS
The 2022 Water Master Plan provided recommendations for improvements based on
immediate capacity needs and expected future growth. The recommended capital
improvement program (Table 8.2) is attached as Attachment 1.
The Water System Master Plan identifies the current and future water needs of the
community through the 2040 General Plan build-out. While there is adequate water
supply now, there is an identified deficiency of 5.1 mgd if build-out occurs without any
additional supply being generated. This will be remedied by constructing three new
water supply wells by 2040.
Supply vs. Demand Evaluation
Supply Balance Existing 2040 Buildout
Maximum Dry Day Demand 13.7 mgd 22.3 mgd
Standby Well 2.6 mgd 2.6 mgd
Required Capacity 16.3 mgd 24.9 mgd
Available Supply Capacity1 19.8 mgd 19.8 mgd
Capacity Surplus/Deficiency +3.5 mgd -5.1 mgd
Recommended New Wells
(at 2.2 mgd each)0 3
1. Includes capacity from the McCarthy Well #9 project that is currently in construction (projected
production of 3.6 mgd).
To address deficiencies in the water distribution system, and 2040 General Plan build-
out, projects have been recommended in the Water System Capital Improvement
needs. The projects identified will be added to the City’s Capital Improvement
Program. In total, the plan recommends 22 pipeline improvement projects, totaling
$25.6 million, three groundwater well improvement projects totaling $11.8 million and
one storage reservoir improvement project totaling $225,700 (attached).
Agenda Item 9.2
Page 493 of 768
Adopt the 2022 Water Master Plan
City of Gilroy City Council Page 4 of 5 April 3, 20231
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Project
Number of
Replacement
Projects
Number
of New
Projects
Cost Allocation
to Existing Users
Cost Allocation
to Future Users
Pipeline
Improvements 13 9 $13,883,000 $11,747,000
Storage
Reservoir
Improvements
0 1 $0 $225,700
Ground Well
Improvements 0 3 $0 $11,776,000
Total Cost $13,883,000 $23,738,700
ALTERNATIVES
Council may amend or reject the 2022 Water Master Plan. This is not recommended as
the 2022 Master Plan is essential to planning and constructing water system projects to
protect the provision of water to the community now and into the future.
FISCAL IMPACT/FUNDING SOURCE
The City has two water funds which are utilized to fund the capital improvements and
the annual operations and maintenance needs. The Water Impact Fund, which collects
revenues in the form of impact fees from developments that impact future growth,
primarily funds infrastructure/capital costs attributable to future users for future capacity
needs. The Water Operations Fund funds the current annual operational, maintenance,
and capital costs to repair and maintain the existing infrastructure. The Water Impact
(future users) and Water Operation (existing users) funds have a projected FY23 ending
fund balance of $3.8 million and $25.0 million, respectively.
Of the total $37.6 million capital improvements identified in the 2022 Water Master Plan,
approximately $13.9 million is attributable to existing users – to be funded by the Water
Operations fund, and $23.7 million is attributable to future users - to be funded by the
Water Impact Fund. The 2022 Water Master Plan capital improvements are in addition
to the existing capital improvements identified by staff.
While the Water Operations fund has adequate fund balance to fund the $13.9 million
identified in existing user costs, the Water Impact fund does not have sufficient fund
balances to fund the $23.7 million identified in future user costs. A typical next step after
the Master Plan is updated is to review and update the utility user fees, and the
development impact fees to incorporate the identified existing and future growth capital
improvements and adjust the fees accordingly to ensure capital and operational needs
are adequately funded for a period. The City is undergoing a rate study for the water
Agenda Item 9.2
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Adopt the 2022 Water Master Plan
City of Gilroy City Council Page 5 of 5 April 3, 20231
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user fees and will consider the projects contemplated in this Master Plan and the CIP to
help determine the rate proposals in the next few months. Staff will plan to review and
update the water impact fee as a project in the departmental workplan in the upcoming
fiscal year.
NEXT STEPS
With Council approval of the 2022 Water Master Plan, staff will incorporate the projects
into the City’s CIP, and plan for delivery of the recommended projects. State approval is
not required.
Attachments:
1. Water System Master Plan
2. Water System Master Plan Capital Improvement Program List
3. Water Master Plan Draft Resolution
Agenda Item 9.2
Page 495 of 768
Agenda Item 9.2
Page 496 of 768
2023
CITY OF GILROY
WATER SYSTEM
MASTER PLAN
FINAL
March 2023
Agenda Item 9.2
Page 497 of 768
Smart Planning Our Water Resources
March 29, 2023
City of Gilroy
7351 Rosanna Street
Gilroy, CA 95020
Attention: Gary Heap, P.E.
City Engineer
Subject: 2023 Water System Master Plan – Final Report
Dear Gary:
We are pleased to submit the draft report for the City of Gilroy Water System Master Plan. This
master plan is a standalone document, though it was prepared as part of the integrated
infrastructure master plans for the water, sewer, and storm drainage master plans. The master
plan documents the following:
•Existing distribution system facilities, acceptable hydraulic performance criteria, and
projected water demands consistent with the Urban Planning Area
•
•
Development and calibration of the City’s GIS-based hydraulic water model.
Capacity evaluation of the existing water system with improvements to mitigate existing
deficiencies and to accommodate future growth.
•Capital Improvement Program (CIP) with an opinion of probable construction costs and
suggestions for cost allocations to meet AB 1600.
We extend our thanks to you, Sharon Goei, Community Development Director; Daryl
Jordan, Director of Public Works; and other City staff whose courtesy and cooperation
were valuable components in completing this study.
Sincerely,
AKEL ENGINEERING GROUP, INC.
Tony Akel, P.E.
Senior Principal
Enclosure: Report
7 4 3 3 N . F I R S T S T R E E T , S U I T E 1 0 3 •F R E S N O , C A L I F O R N I A 9 3 7 2 0 •( 5 5 9 ) 4 3 6 - 0 6 0 0 •F A X ( 5 5 9 ) 4 3 6 - 0 6 2 2
www.akeleng.com
Agenda Item 9.2
Page 498 of 768
City of Gilroy
Water System Master Plan
Acknowledgements
City Council
Marie Blankley, Mayor
Dion Bracco, Mayor Pro Tempore
Rebeca Armendariz
Tom Cline
Zach Hilton
Carol Marques
Fred Tovar
Management Personnel
Jimmy Forbis, City Administrator
Daryl Jordan, P.E., Director of Public Works
Gary Heap, P.E., City Engineer
Jorge Duran, P.E., Senior City Engineer
Sharon Goei, Community Development Director
Matt Jones, Deputy Director of Public Works
Other City Engineering, Planning, and Operations Staff
Agenda Item 9.2
Page 499 of 768
City of Gilroy
Water System Master Plan
Table of Contents Page No.
EXECUTIVE SUMMARY ................................................................................................... ES-1
ES.1 STUDY OBJECTIVES........................................................................................ ES-1
ES.2 INTEGRATED APPROACH TO MASTER PLANNING ...................................... ES-2
ES.3 STUDY AREA.................................................................................................... ES-2
ES.4 SYSTEM PERFORMANCE AND DESIGN CRITERIA ....................................... ES-2
ES.5 EXISTING DOMESTIC WATER SYSTEM OVERVIEW ..................................... ES-5
ES.6 EXISTING AND FUTURE DOMESTIC WATER DEMANDS .............................. ES-5
ES.7 HYDRAULIC MODEL DEVELOPMENT............................................................. ES-5
ES.8 FIRE FLOW ANALYSIS..................................................................................... ES-9
ES.9 SUPPLY AND STORAGE EVALUATION........................................................... ES-9
ES.10 CAPITAL IMPROVEMENT PROGRAM ............................................................. ES-9
CHAPTER 1 - INTRODUCTION......................................................................................... 1-1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
BACKGROUND ................................................................................................. 1-1
SCOPE OF WORK ............................................................................................ 1-1
INTEGRATED APPROACH TO MASTER PLANNING ...................................... 1-3
PREVIOUS MASTER PLANS............................................................................ 1-3
RELEVANT REPORTS...................................................................................... 1-3
REPORT ORGANIZATION................................................................................ 1-4
ACKNOWLEDGEMENTS .................................................................................. 1-5
UNIT CONVERSIONS AND ABBREVIATIONS ................................................. 1-5
GEOGRAPHIC INFORMATION SYSTEMS....................................................... 1-5
CHAPTER 2 – PLANNING AREA CHARACTERISTICS................................................... 2-1
2.1
2.2
2.3
STUDY AREA DESCRIPTION........................................................................... 2-1
WATER SERVICE AREA AND LAND USE........................................................ 2-1
HISTORICAL AND FUTURE GROWTH............................................................. 2-9
CHAPTER 3 – SYSTEM PERFORMANCE AND DESIGN CRITERIA............................... 3-1
3.1
3.2
3.3
HISTORICAL WATER USE TRENDS................................................................ 3-1
SUPPLY CRITERIA ........................................................................................... 3-1
STORAGE CRITERIA........................................................................................ 3-7
3.3.1 Typical Storage Criteria........................................................................ 3-7
PRESSURE CRITERIA...................................................................................... 3-8
UNIT FACTORS ................................................................................................ 3-9
SEASONAL DEMANDS AND PEAKING FACTORS.......................................... 3-10
3.6.1 Maximum Month Demand.................................................................... 3-10
3.6.2 Maximum Day Demand........................................................................ 3-10
3.6.3 Peak Hour Demand ............................................................................. 3-13
TRANSMISSION AND DISTRIBUTION MAIN CRITERIA .................................. 3-13
3.4
3.5
3.6
3.7
CHAPTER 4 – EXISTING DOMESTIC WATER FACILITIES............................................. 4-1
4.1
4.2
4.3
4.4
4.5
4.6
EXISTING WATER SYSTEM OVERVIEW......................................................... 4-1
SOURCE OF SUPPLY....................................................................................... 4-1
PRESSURE ZONES.......................................................................................... 4-4
WATER DISTRIBUTION PIPELINES................................................................. 4-4
STORAGE RESERVOIRS ................................................................................. 4-4
BOOSTER STATIONS....................................................................................... 4-4
March 2023 i City of Gilroy
Water System Master Plan
Agenda Item 9.2
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City of Gilroy
Water System Master Plan
Table of Contents Page No.
4.7 PRESSURE REDUCING VALVES..................................................................... 4-11
CHAPTER 5 – WATER DEMANDS AND SUPPLY CHARACTERISTICS......................... 5-1
5.1
5.2
5.3
5.4
EXISTING DOMESTIC WATER DEMANDS ...................................................... 5-1
FUTURE DOMESTIC WATER DEMANDS ........................................................ 5-1
MAXIMUM DAY AND PEAK HOUR DEMANDS ................................................ 5-4
DIURNAL DEMAND PATTERNS....................................................................... 5-4
CHAPTER 6 – HYDRAULIC MODEL DEVELOPMENT .................................................... 6-1
6.1
6.2
6.3
OVERVIEW........................................................................................................ 6-1
MODEL SELECTION......................................................................................... 6-1
HYDRAULIC MODEL DEVELOPMENT............................................................. 6-1
6.3.1 Skeletonization..................................................................................... 6-2
6.3.2 Pipes and Nodes.................................................................................. 6-2
6.3.3 Digitizing and Quality Control............................................................... 6-2
6.3.4 Demand Allocation............................................................................... 6-2
MODEL CALIBRATION ..................................................................................... 6-3
6.4.1 Calibration Plan and SCADA................................................................ 6-3
6.4.2 EPS Calibration.................................................................................... 6-3
6.4.3 Use of the Calibrated Model................................................................. 6-4
6.4
CHAPTER 7 – EVALUATION AND PROPOSED IMPROVEMENTS................................. 7-1
7.1
7.2
7.3
7.4
7.5
7.6
OVERVIEW........................................................................................................ 7-1
LOW PRESSURE ANALYSIS............................................................................ 7-1
HIGH PRESSURE ANALYSIS........................................................................... 7-1
FIRE FLOW ANALYSIS..................................................................................... 7-1
WATER SUPPLY............................................................................................... 7-5
WATER SUPPLY REQUIREMENTS ................................................................. 7-5
7.6.1 Existing Supply Requirements ............................................................. 7-5
7.6.2 Future Supply Requirements................................................................ 7-5
WATER STORAGE REQUIREMENT................................................................. 7-11
7.7.1 Existing Storage Requirements............................................................ 7-11
7.7.2 Future Storage Requirements.............................................................. 7-11
7.7.3 Recommended New Storage Facilities ................................................ 7-11
PUMP STATION CAPACITY ANALYSIS ........................................................... 7-16
7.8.1 Existing Pump Station Capacity Requirements .................................... 7-16
7.8.2 Future Pump Station Capacity Requirements ...................................... 7-16
PIPELINE IMPROVEMENTS............................................................................. 7-16
7.9.1 Pipeline Improvements to Serve Future Growth................................... 7-19
7.9.2 Pipeline Improvement to Increase Fire Flow Reliability ........................ 7-19
7.9.3 Pipeline Improvements to Mitigate Existing System Deficiencies ......... 7-20
7.7
7.8
7.9
CHAPTER 8 – CAPITAL IMPROVEMENT PROGRAM..................................................... 8-1
8.1
8.2
COST ESTIMATE ACCURACY ......................................................................... 8-1
COST ESTIMATE METHODOLOGY ................................................................. 8-2
8.2.1 Unit Costs ............................................................................................ 8-2
8.2.2 Construction Cost Index....................................................................... 8-2
8.2.3 Construction Contingency Allowance................................................... 8-2
March 2023 ii City of Gilroy
Water System Master Plan
Agenda Item 9.2
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City of Gilroy
Water System Master Plan
Table of Contents Page No.
8.2.4 Project Related Costs .......................................................................... 8-2
CAPITAL IMPROVEMENT PROGRAM ............................................................. 8-4
8.3.1 Capital Improvements Costs ................................................................ 8-4
8.3.2 Recommended Cost Allocation Analysis.............................................. 8-4
8.3.3 Construction Triggers........................................................................... 8-4
SUGGESTED PIPELINE REPLACEMENT BUDGET ........................................ 8-4
8.3
8.4
March 2023 iii City of Gilroy
Water System Master Plan
Agenda Item 9.2
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City of Gilroy
Water System Master Plan
Table of Contents Page No.
FIGURES
Figure ES.1 Regional Location Map................................................................................. ES-3
Figure ES.2 Planning Area............................................................................................... ES-4
Figure ES.3 Existing System............................................................................................ ES-6
Figure ES.4 Capital Improvement Program...................................................................... 11
Figure 1.1
Figure 2.1
Figure 2.2
Figure 2.3
Figure 3.1
Figure 3.2
Figure 4.1
Figure 4.2
Figure 4.3
Figure 5.1
Figure 6.1
Figure 6.2
Figure 7.1
Figure 7.2
Figure 7.3
Figure 7.4
Figure 7.5
Figure 7.6
Figure 7.7
Figure 7.8
Figure 7.9
Figure 8.1
Figure 8.2
Regional Location Map ................................................................................. 1-2
Planning Area ............................................................................................... 2-2
Existing Land Use......................................................................................... 2-3
2040 General Plan Land Use........................................................................ 2-6
Historical Population vs. Average Daily Production....................................... 3-2
Water Use Per Capita Vs. Average Daily Production .................................... 3-3
Existing System ............................................................................................ 4-2
Pipelines by Pressure Zone .......................................................................... 4-5
System Hydraulic Profile Schematic ............................................................. 4-6
Diurnal Curve................................................................................................ 5-5
Storage Calibration....................................................................................... 6-5
Pump Calibration .......................................................................................... 6-6
Minimum System Pressures (Maximum Day Demand) ................................. 7-2
Minimum System Pressures (Peak Hour) ..................................................... 7-3
Maximum System Pressures ........................................................................ 7-4
Required Fire Flow........................................................................................ 7-6
Fire Flow Analysis......................................................................................... 7-7
Available Fire Flow........................................................................................ 7-8
Well Construction Schedule.......................................................................... 7-9
Recommended System Improvements ......................................................... 7-12
Existing Pipeline Deficiencies ....................................................................... 7-22
Capital Improvement Program ...................................................................... 8-5
Pipeline Relacement Budget Alternatives ..................................................... 8-9
March 2023 iv City of Gilroy
Water System Master Plan
Agenda Item 9.2
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City of Gilroy
Water System Master Plan
Table of Contents Page No.
TABLES
Table ES.1 Planning and Design Criteria Summary.........................................................ES-7
Table ES.2 Buildout Water Demands...............................................................................ES-8
Table ES.3 Capital Improvement Program.......................................................................ES-12
Table ES.4 Unit Costs......................................................................................................ES-14
Table 1.1
Table 1.2
Table 2.1
Table 2.2
Table 2.3
Table 2.4
Table 3.1
Table 3.2
Table 3.3
Table 3.4
Table 3.5
Table 4.1
Table 4.2
Table 4.3
Table 4.4
Table 4.5
Table 4.6
Table 5.1
Table 5.2
Table 7.1
Table 7.2
Table 7.3
Table 7.4
Table 7.5
Table 7.6
Table 7.7
Table 8.1
Table 8.2
Unit Conversions ...........................................................................................1-6
Abbreviations and Acronyms .........................................................................1-7
General Plan Land Use .................................................................................2-4
Hecker Pass and Glen Loma Land Use Summary.........................................2-7
Downtown Specific Plan Land Use Summary................................................2-8
Historical and Projected Population ...............................................................2-10
Historical Annual Water Production and Maximum Day Peaking Factors.......3-4
Historical Monthly Water Production (2017-2019)..........................................3-5
Planning and Design Criteria Summary.........................................................3-6
Water Demand Unit Factor Analysis..............................................................3-11
Recommended Water Unit Factors................................................................3-12
Existing Groundwater Supply Capacity..........................................................4-3
Existing Modeled Pipe Inventory....................................................................4-7
Pipe Roughness Coefficients.........................................................................4-8
Existing Storage Reservoirs...........................................................................4-9
Existing Booster Pumping Stations................................................................4-10
Existing Pressure Reducing Valves ...............................................................4-12
Existing Water Demands ...............................................................................5-2
Buildout Water Demand.................................................................................5-3
Supply Capacity Evaluation...........................................................................7-10
Existing Storage Requirements .....................................................................7-13
Buildout Storage Requirements.....................................................................7-14
Storage Capacity Evaluation by Pressure Zone.............................................7-15
Existing Pump Station Capacity Evaluation ...................................................7-17
Buildout Pump Station Capacity Evaluation...................................................7-18
Schedule of Improvements............................................................................7-21
Unit Costs......................................................................................................8-3
Capital Improvement Program.......................................................................8-6
March 2023 v City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 504 of 768
City of Gilroy
Water System Master Plan
Table of Contents Page No.
APPENDICES
Appendix A Calibration Curves
March 2023 vi City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 505 of 768
2023City of Gilroy
EXECUTIVE SUMMARY
This executive summary presents a brief background of the City of Gilroy’s (City) water
distribution system, the planning area characteristics, the system performance and design criteria,
the hydraulic model, and a capital improvement program.
The hydraulic model was used to evaluate the capacity adequacy of the existing distribution
system and for recommending improvements to mitigate existing deficiencies, as well as servicing
future growth. The prioritized capital improvement program accounts for growth throughout the
Gilroy planning area.
ES.1 STUDY OBJECTIVES
Recognizing the importance of planning, developing, and financing system facilities to provide
reliable domestic water system service to existing customers and for servicing anticipated growth
within the sphere of influence, the City initiated the 2023 Water System Master Plan.
The City of Gilroy authorized Akel Engineering Group Inc. to complete the following tasks:
•
•
•
•
•
Summarizing the City’s existing domestic water system facilities.
Documenting growth planning assumptions and known future developments.
Summarizing the water system performance criteria.
Projecting future domestic water demands.
Updating and validating the City’s hydraulic model based on the City’s Geographic
Information Systems (GIS).
•Evaluating the domestic water facilities to meet existing and projected demand
requirements, and fire flows.
•
•
•
•
Evaluating the existing groundwater conditions.
Performing a capacity analysis for major distribution mains.
Performing a fire flow analysis.
Recommending a capital improvement program (CIP) with an opinion of probable
construction costs.
•
•
Performing a capacity allocation analysis for cost sharing purposes.
Developing a 2023 Water System Master Plan report.
March 2023 ES-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 506 of 768
ES.2 INTEGRATED APPROACH TO MASTER PLANNING
The City implemented an integrated master planning approach and contracted the services of
Akel Engineering Group to prepare the following documents:
•
•
•
2023 Water System Master Plan
2023 Sewer System Master Plan
2023 Storm Drainage System Master Plan
While each of these reports is published as a standalone document, they have been coordinated
for consistency with the City’s General Plan. Additionally, each document has been cross
referenced to reflect relevant analysis results with the other documents.
ES.3 STUDY AREA
The City of Gilroy is located in Santa Clara County near the west coast of California, south of City
of San Francisco. The City of Gilroy lies within the seismically active region of San Francisco Bay.
The City of Gilroy lies in the southern portion of the Santa Clara County and is the most southern
city located within the county. The City is located approximately 32 miles southeast of the City of
San Jose, 8 miles southeast of Morgan Hill, 25 miles east of City of Santa Cruz, and 16 miles
northwest of City of Hollister. The City limits currently encompass 16.5 square miles, with an
approximate population of 56,600 residents, according to Department of Finance as of January
2021. Figure ES.1 displays the City’s location.
The City of Gilroy is generally bound to the north by Fitzgerald Avenue, to the northeast by San
Ysidro Avenue, to the southeast by Camino Arroyo, to the west by Burchell Road and Rancho
Vista Drive, and to the south by Carnadero Avenue. The U.S. Route 101 divides the City in a
southeast to northwest direction and the California State Route 152 (Hecker Pass Hwy) runs east-
west direction in the northern half of the City. The topography is relatively flat in the middle of the
service area, with increasing slopes in the east and west side of the city due to the Santa Cruz
Mountains to the west and the Diablo Range to the east. Figure ES.2 displays the planning area
showing city limits, the Urban Growth Boundary (UGC) of the City and Planning Area / Sphere of
Influence (SOI).
The City operates and maintains a domestic water system that covers the majority of the area
within the service area limits. Currently, the water demands are provided from groundwater wells
located throughout the service area.
ES.4 SYSTEM PERFORMANCE AND DESIGN CRITERIA
This report documents the City’s performance and design criteria that were used for evaluating
the domestic water system. The system performance and design criteria are used to establish
guidelines for determining future water demands, evaluating existing domestic water facilities, and
March 2023 ES-2 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 507 of 768
Calero
Reservoir
Anderson
Reservoir
101
Morgan Hill
Coyote
Reservoir
Uvas
Reservoir
101
152 Gilroy
152
101
152
25
Watsonville
152
1
129
101129129
Legend Figure .1CitiesElevation (ft)
9 - 50
1,001 - 2,000
2,001 - 3,000
3,001 - 3,792
Regional Location Map
Water System Master Plan
City of Gilroy
Study Area
City Limits 51 - 100
Urban Growth Boundary
Highway
101 - 250
251 - 500
501 - 1,000
Waterbodies
Railroads GIS
0 0.5 1 2Updated: September 21, 2020 Miles
Flie Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig1-1RLMap_092120.mxd
Agenda Item 9.2
Page 508 of 768
101 Coyote
Reservoir
152 152
City of Gilroy
101 152
101
25
Legend Figure
Planning Area
Water System Master Plan
City of Gilroy
.City Limits General Plan Area
City Limits Area Roads
HighwaysSpecific Plan Areas
Urban Service Area Railroads
Urban Growth Boundary
Sphere of Influence Boundary
Rivers & Creeks
Waterbodies GIS
0 0.5 1 2Updated: September 21, 2020 Miles
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig2-1PlanningArea_092120.mxd
Agenda Item 9.2
Page 509 of 768
for sizing future facilities. Table ES.1 documents the system performance and design criteria for
the domestic water system. This criterion was used in the capacity evaluation and for sizing
recommended improvements.
ES.5 EXISTING DOMESTIC WATER SYSTEM OVERVIEW
The City’s municipal water system consists of 9 groundwater wells, 10 storage reservoirs that
have a cumulative capacity of 14.1 MG, and over approximately 202 miles of distribution
pipelines. The City’s generally flat topography slopes up from east to west at approximately 180
feet in the east to approximately 250 feet in the west. Even with this generally flat topography, the
City utilizes three separate pressure zones due to the slopes on the west side.
The City’s existing domestic water distribution system is shown in Figure ES.3, with color coded
pipe sizes. This figure also identifies the location of existing wells and the storage reservoir.
ES.6 EXISTING AND FUTURE DOMESTIC WATER DEMANDS
The existing water demands used for this master plan were based on the City’s 2019 PWSS
consumption records, which included the monthly demands for each land use category, as well as
total annual production. These existing water demands in this analysis are adjusted to match the
annual production records and account for system losses.
The existing demand distribution, by pressure zone, was obtained from the water billing records.
Using GIS, each customer account was geocoded to its physical location within its existing
pressure zone. The accounts were then stored by pressure zone and total demand in each zone
was calculated.
The City’s existing average day domestic water demand, as extracted from water billing records,
were lower than the total demand listed in the annual production records due to system losses
that occurred between groundwater wells and customer service connections. The total domestic
water demand was increased proportionally to 4,768 gpm to reflect the total 2019 production and
account for transmission main losses. The existing domestic water demands for each pressure
zone (2019 SCADA) and design criteria peaking factors are summarized on Table ES.2.
ES.7 HYDRAULIC MODEL DEVELOPMENT
Hydraulic network analysis has become an effectively powerful tool in many aspects of water
distribution planning, design, operation, management, emergency response planning, system
reliability analysis, fire flow analysis, and water quality evaluations. The City’s hydraulic model
was used to evaluate the capacity adequacy of the existing system and to plan its expansion to
service anticipated future growth.
The City’s previous hydraulic model was developed using the Environmental Protection Agency’s
EPANET software, which allows the use of a single modeling scenario, and basic simulation
March 2023 ES-5 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 510 of 768
Legend
Existing System
Tanks
Wells
Booster Pumps
Existing Pipes by Diameter
4" - 6"
8
101
8"
10" - 30"Booster
Station 4Tanks: 2C-1
2C-2 RoadsBooster
Station 3 & 23D-1
3D-2 Booster
Station 1 Railroads
12 Well 5-2
Tank 1A City Limits
Well 7 Urban Growth Boundary
Rivers & Creeks
Waterbodies
152 24 152 Well 2 Well 12424 Well 8
Well 8A
8
152
Well 3-2
Tanks: 2E-1
2E-2
Booster
Station 5
Well 4
Well 6
Booster
Station 6
Tanks: 1B
2F-1
1G-1
1G-2
Figure .
Existing System
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: January 27, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig4-1_ExistingSystem_012721.mxd
Agenda Item 9.2
Page 511 of 768
Table ES.1 Planning and Design Criteria Summary
Water System Master Plan
City of Gilroy
Design Parameter Criteria
Supply Supply = Maximum Day Demand + Standby Well (1,805 gpm)
Storage Total Required Storage = Operational + Fire + Emergency
For Pressure Zone 1
Operational Storage
Fire Storage
25% of Maximum Day Demand
Varies
Emergency Storage
For Pressure Zones 2 and 3
Operational Storage
Fire Storage
25% of Maximum Day Demand
25% of Maximum Day Demand
Varies
Emergency Storage 50% of Maximum Day Demand
Booster Pumps Pumping Capacity = Maximum Day Demand
Distribution Mains Distribution mains should be designed to meet the greater of:
1) Peak Hour Demand, or 2) Maximum Day Demand + Fire Flow
Criteria for existing and future pipelines include:
Maximum pipe velocity of 8 feet per second
Maximum friction losses of 10 feet / 1,000 feet
Maximum PressureService Pressures 80 psi
40 psi
35 psi
40 psi
20 psi
Minimum Pressure (during Maximum Day)
Minimum Pressure (during Peak Hour)
Minimum Pressure for New Development1 (during Peak Hour)
Minimum Residual Pressure (during Fires)
Demand Peaking Factors Maximum Month Demand
Maximum Day Demand
Peak Hour Demand
Residential
1.50 x Average Day Demand
2.00 x Average Day Demand
3.00 x Average Day Demand
1,500 gpm for 2 hoursFire Flows
Commercial 2,500 gpm for 2 hours
Industrial 5,000 gpm for 3 hours
2Time-of-Use Time-of-Use considerations account for off-peak energy rate schedule before
4 PM and after 9 PM (19-hour pumping period).
Urban Water Use Targets
2020 Urban Water Management Plan Existing Coefficient 166 gpdc
149 gpdc
133 gpdc
2015 Interim Target
2020 Target (20% Conservation)
5/11/2021
Notes:
1. Unless otherwise noted, criteria is based on California Department of Public Health Title 22, Chapter 16, Article 8.
2. Source: PG&E Time-of-Use Pricing Schedule.
Agenda Item 9.2
Page 512 of 768
Table ES.2 Buildout Water Demands
Water System Master Plan
City of Gilroy
Total Water Demand Buildout of Service AreaWater Unit
Land Use Classification Factor Average Day
DemandExisting Unchanged Redeveloped Area New Development Total Area
(gpd/acre)(acres)(acres)(acres)(acres)(gpd)
Residential
Hillside Residential
Low Density Residential
Medium Density Residential
High Density Residential
1,270
2,000
442
1,583
58
112
122
177
18
353
89
907
1,794
240
1,151,593
3,587,897
788,7433,280 6
4,260 67 18 104 442,583
Subtotal - Residential 2,151 429 466 3,045 5,970,816
Non-Residential
Office and Commercial 1
Industrial 2
1,100
990
465 281
213
153
38
100
643
129
358
7
846
1,149
841
395
27
930,592
1,137,375
151,310
450,832
31,122
293
Public Facility / Institution
Neighborhood District
City Gateway District
180 559
1,140
1,140
Varies
1,100
Varies
Varies
990
0
0 20
Downtown Specific Plan Area 3
Mixed Use Corridor High
0 57 32 89 210,626
35,976025733
Hecker Pass Special Use District 4
Glen Loma Ranch 4
0 328
103
43
88 416
341
83
528,763
577,791
82,587
0
0
237
40Industrial Park
Employment Center 1,100 0 279
1,541
251
1,893
530
4,750
583,081
4,720,055Subtotal - Non-Residential 1,317
Other
Park and Recreation Facility 410
0
995
0
0
0
0
154
0
1,149
0
471,009
Vacant 0
0Open Space
Rural County
0 253 1,045 1,298
0 0 28 3 30 0
Subtotal - Other 1,247 28 1,202 2,477 471,009
Total
4,714 1,997 3,561 10,272 11,161,880
4/20/2022
Notes:
1. Office and Commercial accounts for Visitor Serving Commercial and General Services Commercial Land Use types.
2. Industrial accounts for General Industrial and Campus Industrial Land Use types.
3. Downtown Specific Plan Water Unit Factors vary based on land use.
4. Glen Loma and Hecker Pass water demand estimated separately, based on itemized land use plan and associated land use factors.
Agenda Item 9.2
Page 513 of 768
options for steady-state and extended period simulations. As part of this master plan, the
hydraulic model has been updated for consistency the City’s current GIS database and
redeveloped using the InfoWater hydraulic modeling software, available from Innovyze Inc. This
software is directly integrated with ESRI’s ArcGIS (GIS) environment, providing a useful modeling
tool linked to the City’s newly developed GIS database.
ES.8 FIRE FLOW ANALYSIS
The fire flow analysis consisted of using the maximum day demand in the hydraulic model and
applying hypothetical fire flows. The magnitude and duration of each fire flow was based on the
governing land use type within proximity to the fire location. The criterion for fire flows was also
summarized in the System Performance and Design Criteria chapter. The hydraulic model
indicates that the City’s existing distribution system performed adequately during the fire flow
analysis, with the exceptions noted in the Evaluation and Proposed Improvements Chapter.
ES.9 SUPPLY AND STORAGE EVALUATION
The water supply source, in this case groundwater, must meet the maximum day demands for
both existing and future growth conditions. Additionally, the groundwater supply capacity must
include a redundancy, which assumes the largest well remains out of service due to equipment
malfunction or reduced supply capacity during droughts.
Currently, the City of Gilroy’s existing water supply requirement based on current water demands
is approximately 16.3 MGD. The water supply evaluation indicates the available capacity is
approximately 19.8 MGD, which results in a supply surplus of 3.5 MGD. Similarly, the future
supply requirement based on the buildout of the 2040 General Plan is approximately 24.9 MGD,
which results in a supply deficit of 5.1 MGD. As such, three new groundwater wells are
recommended to meet city performance and design criteria. The first new well is recommended to
be operational by year 2033, the second well by year 2041 and the third well by year 2048.
A water storage evaluation was also conducted in each pressure zone based on City’s
operational, emergency and fire storage criteria. The results of the storage analysis indicate that
the existing storage volume is sufficient under existing conditions but is unable to meet the
requirements for both existing and future customers at the buildout of the General Plan.
Therefore, a new storage reservoir with a capacity of 0.1 MG is recommended specifically in Zone
3 to mitigate future deficiency.
ES.10 CAPITAL IMPROVEMENT PROGRAM
The overall capital improvements required for mitigating existing system deficiencies and for
serving anticipated future growth throughout the City are summarized on Table ES.3, and are
graphically represented on Figure ES.4. The unit costs for pipeline improvements, reservoir
construction and groundwater well construction are also identified on Table ES.4.
March 2023 ES-9 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 514 of 768
The estimated construction costs include the baseline costs plus 30 percent contingency
allowance to account for unforeseen events and unknown field conditions. Capital improvement
costs include the estimated construction costs plus 30 percent project-related costs (engineering
design, project administration, construction management and inspection, and legal costs).
The costs in this Water System Master Plan were benchmarked using a 20-City national average
Engineering News Record (ENR) Construction Cost Index (CCI) of 13,176, reflecting a date of
March 2023. In total, the CIP includes approximately 9.8 miles of pipeline improvements, one new
reservoir and three new groundwater wells with a total capital cost of over 37.6 million dollars.
March 2023 ES-10 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 515 of 768
Legend
Recommended Improvements
Tanks
Wells
New Pipes
Pipe Replacements
Existing System
Tanks
8
101
GW-10 WellsGW-12
Booster Pumps
Existing Pipes by Diameter
4" - 6"
Booster
Station 4Tanks: 2C-1
2C-2 Booster
Station 3 & 23D-1
3D-2 Booster
Station 1 8"12 Well 5-2
Tank 1A 10" - 30"
3H-1 16P1-5 RoadsWell 7
Railroads1522416
Well 2 P1-315224 City Limits2410
P1-6
Well 8
Well 8AWell 1
16
P1-8 Urban Growth Boundary
Rivers & Creeks
Waterbodies
8 12P1-7 152
GW-11Well 3-2
Tanks: 2E-1
2E-2 (Planned Well)
Booster
Station 5
Well 4
Well 6
Booster
Station 6
Tanks: 1B
2F-1
1G-1
1G-2
16
P1-22
Figure .
Capital Improvement
Program
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: September 14, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig8-1_CIP_091421.mxd
Agenda Item 9.2
Page 516 of 768
Table ES.3 Capital Improvement Program
Water System Master Plan
City of Gilroy
PRELIMINARY
Pipeline Information Infrastructure Costs Suggested Cost Allocation
Existing
Users
Cost SharingBaseline Constr. Estimated Const. Capital Improv.Pressure
Zone
Construction TriggerImprov. No.Improv. Type Alignment Limits Costs Costs1 Costs2New/Parallel/Existing Diameter Diameter Length Unit Cost Infr. Cost Future Users Existing Users Future UsersReplace
(in)(in)(ft)($)($)($)($)($)
Pipeline Improvements
P1-1
P1-2
Future Growth
Future Growth
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
FF Reliability
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Day Rd From Santa Teresa Blvd to Monterey Hwy
From approx. 620' n/o Day Rd to Cohansey Ave
From 2nd St to Ioof Ave
-
-
New
New
12
12
16
16
16
10
12
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
3,860
5,780
230
254
254
304
304
304
211
254
304
304
304
304
304
304
304
304
304
304
304
304
304
304
304
978,700
1,465,500
70,000
978,700
1,465,500
70,000
1,272,400
1,905,200
91,000
1,654,200
2,476,800
118,300
With Development
With Development
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
As Funding is Available
As Funding is Available
As Funding is Available
With Development
With Development
As Funding is Available
As Funding is Available
As Funding is Available
With Development
With Development
As Funding is Available
With Development
With Development
With Development
0%
0%
100%
100%
0%
0
0
1,654,200
Monterey Hwy / Orsetti
Rd / Hwy 101 2,476,800
P1-3 Monterey Hwy
Murray Ave
Arroyo Cir
Lewis St
12
12
12
8
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
New
100%
100%
100%
100%
100%
100%
100%
100%
100%
0%
118,300
1,131,400
36,100
82,200
137,300
154,400
889,800
1,563,300
1,080,000
0
0
P1-4 From Well 5-02 to Ioof Ave 2,200
70
669,400
21,300
669,400
21,300
870,300
27,700
1,131,400
36,100
0%0
P1-5 From Well 7 to Ioof Ave 0%0
P1-6 From approx. 180' e/o Forest St to Chestnut St
From Well 3 to 6th St
230 48,600 48,600 63,200 82,200 0%0
P1-7 Forest St 10
12
12
12
12
-
320 81,200 81,200 105,600
118,700
684,400
1,202,500
830,700
640,800
1,795,700
2,563,100
1,210,300
1,079,800
716,000
1,143,100
1,831,400
261,200
1,190,600
110,800
137,300 0%0
Gilman Rd / Camino
ArroyoP1-8 From Well 8 to approx. 80' se/o Gilman Rd
From Camino Arroyo to Cameron Blvd
From Pacheco Pass Hwy to Venture Wy
300 91,300 91,300 154,400 0%0
P1-9 Pacheco Pass Hwy
Camino Arroyo
Cameron Blvd
ROW
1,730
3,040
2,100
1,620
4,540
6,480
3,060
2,730
1,810
2,890
4,630
660
526,400
925,000
639,000
492,900
1,381,300
1,971,600
931,000
830,600
550,700
879,300
1,408,700
200,900
915,800
85,200
526,400
925,000
639,000
492,900
1,381,300
1,971,600
931,000
830,600
550,700
879,300
1,408,700
200,900
915,800
85,200
889,800 0%0
P1-10
P1-11
P1-12
P1-13
P1-14
P1-15
P1-16
P1-17
P1-18
P1-19
P1-20
P1-21
P1-22
FF Reliability 1,563,300
1,080,000
833,100
0%0
0From Pacheco Pass Hwy to approx. 200' se/o Venture
WyFF Reliability 0%
Future Growth
Future Growth
FF Reliability
From Camino Arroyo to approx. 1,800' e/o Luchessa Ave 100%
100%
0%
833,100
2,334,500
0
ROW / Cameron Blvd From approx. 200' se/o Venture Wy to Southside Dr -New 2,334,500
3,332,100
1,573,400
1,403,800
930,800
0%0
Luchessa Ave
Thomas Rd
Rossi Ln
ROW
From Thomas Rd to Rossi Ln 12
12
12
-
Replace
Replace
Replace
New
100%
100%
100%
0%
3,332,100
1,573,400
1,403,800
0
FF Reliability From Luchessa Ave to Santa Teresa Rd
From Luchessa Ave to Southside Dr
0%0
FF Reliability 0%0
Future Growth
Future Growth
FF Reliability
From Luchessa Ave to approx. 1,800' e/o Luchessa Ave
From approx. 1,800' e/o Luchessa Ave to Southside Dr
From Hwy 101 to Arizona Cir
100%
100%
0%
930,800
1,486,100
0
ROW -New 1,486,100
2,380,900
339,600
0%0
Garlic Farm Wy /
Southside Dr 12
-
Replace
New
100%
0%
2,380,900
0Future Growth
Future Growth
Future Growth
Southside Dr
Southside Dr
From Arizona Cir to approx. 660' e/o Arizona Cir
From approx. 660' e/o Arizona Cir to Camaron Blvd
100%
100%
100%
339,600
1,547,800
144,100
-New 3,010
280
1,547,800
144,100
0%0
From approx. 160' w/o Thomas Rd to approx. 110' e/o
Thomas RdSanta Teresa Blvd -New 0%0
Subtotal - Pipeline Improvements 15,164,400 19,714,500 25,630,000 13,883,000 11,747,000
Proposed Storage CapacityStorage Reservoir Improvements (MG)
3H-1 Storage Capacity Zone 3 Construct an additional 0.1 MG storage reservoir at existing 3D site New 0.10 133,442 133,500 173,600 225,700 813 EDU 0%100%0 225,700
Subtotal - Storage Reservoir Improvements 133,500 173,600 225,700 0 225,700
Agenda Item 9.2
Page 517 of 768
Table ES.3 Capital Improvement Program
Water System Master Plan
City of Gilroy
PRELIMINARY
Pipeline Information Infrastructure Costs Suggested Cost Allocation
Existing
Users
Cost SharingBaseline Constr. Estimated Const. Capital Improv.Pressure
Zone
Construction TriggerImprov. No.Improv. Type Alignment Limits Costs Costs1 Costs2New/Parallel/Existing Diameter Diameter Length Unit Cost Infr. Cost Future Users Existing Users Future UsersReplace
(in)(in)(ft)($)($)($)($)($)
Proposed Pumping CapacityGroundwater Well Improvements (gpm)
GW-10
GW-11
GW-12
Supply Capacity
Supply Capacity
Supply Capacity
Zone 1
Zone 1
Zone 1
Construct new well near the intersection of San Ysidro Ave and Las Animas Ave
Construct new well near the intersection of Camino Arroyo and Renz Lane
Construct new well near the intersection of Wren Ave and Vickery Ln
New
New
New
1,500
1,500
1,500
-
-
-
-
-
-
-
-
-
3,922,000
3,922,000
3,922,000
9,500 EDU
15,550 EDU
21,600 EDU
0%
0%
0%
100%
100%
100%
0
0
0
3,922,000
3,922,000
3,922,000
Subtotal - Groundwater Well Improvements 0 0 11,766,000 0 11,766,000
Total Improvement Cost
Pipeline Improvements 15,164,400 19,714,500
173,600
0
25,630,000
225,700
13,883,000 11,747,000
225,700Storage Reservoirs
Groundwater Wells
133,500
0
0
011,766,000
37,621,700
11,766,000
Total Improvement Costs 13,883,000 23,738,70015,297,900 19,888,100
3/29/2023Notes:
1. Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.
2. Estimated construction costs plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal costs.
3. Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,176 for March 2023.
Agenda Item 9.2
Page 518 of 768
Table ES.4 Unit Costs
Water System Master Plan
City of Gilroy
Pipelines
Pipe Size Cost1,2
(in)($/lineal foot)
6 $153
8 $187
$211
$254
$304
$312
$336
$400
$500
$560
$705
10
12
16
18
20
24
30
36
42
Pump Stations
Estimated Pumping Station Project Cost = 2.1*10(0.7583*log(Q)+3.1951)
where Q is in gpm
Storage Reservoirs ($/gallon)1,3
≤1.0 MG
1.1 MG-3.0 MG
3.1 MG - 5.0 MG
> 5 MG
$1.33
$2.11
$3.22
$4.89
Groundwater Wells1,4,5
1,500 gpm Capacity $3,922,000
3/28/2023
Notes:
1. Construction costs estimated using March 2023 ENR CCI of 13,176.
2. Pipeline cossts include utilities, construction staging, traffic control, and
lighting and signing
3. Source: City of Gilroy 2004 Water System Master Plan
4. Source: City of Gilroy 2021-2025 Capital Improvement Program
5. One new 1,500 gpm well costs $3,626,645, per City of Gilroy 2021-2025
Capital Improvement Program. The cost accounts for Design, CEQA,
Construction, Con. Support, and Land Acquisition
Agenda Item 9.2
Page 519 of 768
2023City of Gilroy
CHAPTER 1 - INTRODUCTION
This chapter provides a brief background of the City of Gilroy’s (City) domestic water system, the
need for this master plan, and the objectives of the study. Unit conversions, abbreviations, and
definitions are also provided in this chapter.
1.1 BACKGROUND
The City of Gilroy is located approximately 32 miles southeast of the City of San Jose, 8 miles
southeast of Morgan Hill, 25 miles east of the City of Santa Cruz, and 16 miles northwest of the
City of Hollister. (Figure 1.1). The City provides potable water service to approximately 56,700
residents, as well as a myriad of commercial, industrial, and institutional establishments. The City
operates a domestic water distribution system that consists of 9 groundwater wells, 10 storage
reservoirs providing 14.1 MG total storage, and approximately 202 miles of distribution pipelines.
In 2004, the City developed a Water System Master Plan that identified capacity deficiencies in
the existing water system and recommended improvements to alleviate existing deficiencies and
service anticipated developments in the Gilroy Urban Growth Boundary.
Recognizing the importance of planning, developing, and financing system facilities to provide
reliable water service to existing customers and for servicing anticipated growth within the Gilroy
Urban Growth Boundary, the City initiated updating elements of the 2004 Water System Master
Plan, to reflect current land use conditions.
1.2 SCOPE OF WORK
City Council approved Akel Engineering Group Inc. to prepare this 2022 Water System Master
Plan (WSMP) and a concurrent Sewer System Master Plan and Storm Drainage System Master
Plan in August 2019. The 2022 WSMP evaluates the City’s domestic water system and
recommends capacity improvements necessary to service the needs of existing users and for
servicing the future growth of the City. This 2022 WSMP is intended to serve as a tool for planning
and phasing the construction of future domestic water system infrastructure for the projected
buildout of the City’s service area. The area and horizon for this master plan is based on the City’s
General Plan. Should planning conditions change, and depending on their magnitude,
adjustments to the master plan recommendations might be necessary.
This master plan included the following tasks:
Summarizing the City’s existing domestic water system facilities.
Documenting growth planning assumptions and known future developments.
Summarizing the water system performance criteria.
March 2023 1-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 520 of 768
Calero
Reservoir
Anderson
Reservoir
101
Morgan Hill
Coyote
Reservoir
Uvas
Reservoir
101
152 Gilroy
152
101
152
25
Watsonville
152
1
129
101129129
Legend Figure 1.1CitiesElevation (ft)
9 - 50
1,001 - 2,000
2,001 - 3,000
3,001 - 3,792
Regional Location Map
Water System Master Plan
City of Gilroy
Study Area
City Limits 51 - 100
Urban Growth Boundary
Highway
101 - 250
251 - 500
501 - 1,000
Waterbodies
Railroads GIS
0 0.5 1 2Updated: September 21, 2020 Miles
Flie Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig1-1RLMap_092120.mxd
Agenda Item 9.2
Page 521 of 768
•
•
Projecting future domestic water demands.
Updating and validating the City’s hydraulic model based on the City’s Geographic
Information Systems (GIS).
•Evaluating the domestic water facilities to meet existing and projected demand
requirements and fire flows.
•
•
•
•
•
•
Evaluating the existing groundwater conditions.
Performing a capacity analysis for major distribution mains.
Performing a fire flow analysis.
Recommending a capital improvement program (CIP) with an estimation of probable costs.
Performing a capacity allocation analysis for cost sharing purposes.
Developing a 2023 Water System Master Plan report.
1.3 INTEGRATED APPROACH TO MASTER PLANNING
The City implemented an integrated master planning approach and contracted the services of
Akel Engineering Group to prepare the following documents:
•
•
•
2023 Water System Master Plan
2023 Sewer System Master Plan
2023 Storm Drainage System Master Plan
While each of these reports is published as a standalone document, it has been coordinated for
consistency with the City’s General Plan. Additionally, each document has been cross referenced
to reflect relevant analysis results with the other documents.
1.4 PREVIOUS MASTER PLANS
The City’s most recent water master plan was completed in 2004. This master plan included an
evaluation of servicing growth to the planning area, evaluated existing demands and projected
future demands, evaluated groundwater conditions and management, and recommended phased
improvements to the water system for a horizon year of 2040. Additionally, the 2004 master plan
included the development of the original hydraulic model, which was then used for evaluating the
water system. Improvements were recommended for servicing existing and future growth areas,
and a corresponding Capital Improvement Program was developed to quantify construction costs.
1.5 RELEVANT REPORTS
The City has completed several special studies intended to evaluate localized growth. These
reports were referenced and used during this capacity analysis. The following lists relevant reports
March 2023 1-3 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 522 of 768
that were used in the completion of this master plan, as well as a brief description of each
document:
City of Gilroy 2040 General Plan, November 2020 (2040 GP). The City’s 2040 General
Plan provides future land use planning, and growth assumptions for the Planning Area,
Additionally, this report establishes the planning horizon for improvements in this master
plan.
City of Gilroy Water System Master Plan, February 2004 (2004 SSMP). This report
documents the planning and performance criteria, evaluates the water system,
recommends improvements, and provides an estimate of costs.
1.6 REPORT ORGANIZATION
The water system master plan report contains the following chapters:
Chapter 1 - Introduction. This chapter provides a brief background of the City’s domestic water
system, the need for this master plan, and the objectives of the study. Abbreviations and
definitions are also provided in this chapter.
Chapter 2 - Planning Areas Characteristics. This chapter presents a discussion of the planning
area characteristics for this master plan and defines the land use classifications. The planning
area is divided into several planning sub-areas, as established by the City’s Planning Division.
Chapter 3 – System Performance and Design Criteria. This chapter presents the City’s
performance and design criteria, which was used in this analysis for identifying current system
capacity deficiencies and for sizing proposed distribution mains, storage reservoirs, and wells.
Chapter 4 – Existing Domestic Water Facilities. This chapter provides a description of the
City’s existing domestic water system facilities including the existing wells, distribution mains,
storage reservoirs, and booster station pumps.
Chapter 5 - Water Demands and Supply Characteristics. This chapter summarizes
groundwater quality, existing domestic water demands, identifies the recycled water demands,
and projects the future domestic water demands.
Chapter 6 - Hydraulic Model Development. This chapter describes the development and
calibration of the City’s domestic water distribution system hydraulic model. This hydraulic model
was used to evaluate the capacity adequacy of the existing system and to plan its expansion to
service anticipated future growth.
Chapter 7 - Evaluation and Proposed Improvements. This chapter presents a summary of the
domestic water system evaluation and identifies improvements needed to mitigate existing
deficiencies, as well as improvements needed to expand the system and service growth.
March 2023 1-4 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 523 of 768
Chapter 8- Capital Improvement Program. This chapter provides a summary of the
recommended domestic water system improvements to mitigate existing capacity deficiencies and
to accommodate anticipated future growth. The chapter also presents the cost criteria and
methodologies for developing the capital improvement program. Finally, a capacity allocation
analysis, usually used for cost sharing purposes, is also included.
1.7 ACKNOWLEDGEMENTS
Obtaining the necessary information to successfully complete the analysis presented in this
report, and developing the long term strategy for mitigating the existing system deficiencies and
for accommodating future growth, was accomplished with the strong commitment and very active
input from dedicated team members including:
Karen L. Garner; Community Development Director
Gary Heap, P.E.; City Engineer
Jorge Duran, P.E.; Senior City Engineer
Daryl Jordan, P.E.; Director of Public Works
Matt Jones, Deputy Public Works Director
1.8 UNIT CONVERSIONS AND ABBREVIATIONS
Engineering units were used in reporting flow rates and volumes pertaining to the design and
operation of various components of the domestic water system. Where it was necessary to report
values in smaller or larger quantities, different sets of units were used to describe the same
parameter. Values reported in one set of units can be converted to another set of units by
applying a multiplication factor. A list of multiplication factors for units used in this report is shown
on Table 1.1.
Various abbreviations and acronyms were also used in this report to represent relevant water
system terminologies and engineering units. A list of abbreviations and acronyms is included in
Table 1.2.
1.9 GEOGRAPHIC INFORMATION SYSTEMS
This master planning effort made extensive use of Geographic Information Systems (GIS)
technology, for completing the following tasks:
Develop the physical characteristics of the hydraulic model (pipes and junctions, wells, and
storage reservoirs).
Allocate existing water demands, as extracted from the water billing records, and based on
each user’s physical address.
March 2023 1-5 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 524 of 768
Table 1.1 Unit Conversions
Water System Master Plan
City of Gilroy
Volume Unit Calculations
To Convert From:
acre feet
acre feet
acre feet
cubic feet
cubic feet
cubic feet
gallons
To:Multiply by:
325,851
43,560
gallons
cubic feet
million gallons
gallons
0.3259
7.481
acre feet 2.296 x 10-5
7.481 x 10-6
0.1337
million gallons
cubic feet
acre feetgallons 3.069 x 10-6
1 x 10-6gallonsmillion gallons
million gallons gallons 1,000,000
million gallons
million gallons
cubic feet
acre feet
133,672
3.069
Flow Rate Calculations
To Convert From:To:
mgd
cfs
Multiply By:
ac-ft/yr
ac-ft/yr
ac-ft/yr
ac-ft/yr
cfs
8.93 x 10-4
1.381 x 10-3
0.621gpm
gpd 892.7
mgd
gpm
ac-ft/yr
gpd
0.646
cfs 448.8
cfs 724
cfs 646300
1 x 10-6
1.547 x 10-6
6.944 x 10-4
1.12 x 10-3
1.44 x 10-3
2.228 x 10-3
1.61
gpd mgd
cfsgpd
gpd gpm
ac-ft/yr
mgd
cfs
gpd
gpm
gpm
gpm
gpm
mgd
mgd
mgd
mgd
ac-ft/yr
gpd 1,440
cfs 1.547
gpm
ac-ft/yr
gpd
694.4
1,120
1,000,000
5/4/2021
Agenda Item 9.2
Page 525 of 768
Table 1.2 Abbreviations and Acronyms
Water System Master Plan
City of Gilroy
Abbreviation Expansion Abbreviation Expansion
2004 WSMP 2004 Water System Master Plan gpd gallons per day
2021 WSMP 2021 Water System Master Plan gpdc
gpm
hp
gallons per day per capita
gallons per minute
horsepower
Association for the Advancement of Cost
EngineeringAACE International
AC
ACP
ADD
Akel
CCI
acre
Asbestos Cement Pipe
average day demand
Akel Engineering Group, Inc.
Construction Cost Index
California Department of Public Health
cubic feet per second
cast iron pipe
HGL
HWL
in
hydraulic grade line
high water level
inch
LAFCO
LF
Local Agency Formation Commission
linear feetCDPH
cfs MDD
MG
maximum day demand
million gallonsCI
CIB Capital Improvement Budget
Capital Improvement Program
City of Gilroy
MGD
MMD
NFPA
PHD
PRV
psi
million gallons per day
maximum month demand
National Fire Protection Association
peak hour demand
pressure reducing valve
pounds per square inch
Right of Way
CIP
City
County
DIP
DU
Santa Clara County
Ductile Iron Pipe
dwelling unit
EDU
ENR
EPA
EPS
FRC
ft
equivalent dwelling unit
Engineering News Record
Environmental Protection Agency
Extended Period Simulation
Facility Reserve Charge
feet
ROW
SCADA
SOI
Supervisory Control and Data
Acquisition
Sphere of Influence
TBD
ULL
to be determined
Urban Limit Line
VW Valley Water
fps feet per second WSMP
WTP
Water System Master Plan
Water Treatment PlantFYFiscal Year
GIS Geographic Information Systems
4/28/2021
Agenda Item 9.2
Page 526 of 768
Calculate and allocate future water demands, based on future developments’ water use.
Extract ground elevations along the distribution mains from available contour maps.
Generate maps and exhibits used in this master plan.
March 2023 1-8 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 527 of 768
2023City of Gilroy
CHAPTER 2 – PLANNING AREA CHARACTERISTICS
This chapter presents a discussion of the planning area characteristics for this master plan and
defines the land use classifications. The planning area is divided into several planning sub-areas,
as established by the City’s Planning Division.
2.1 STUDY AREA DESCRIPTION
The City of Gilroy is located in Santa Clara County near the west coast of California, south of City
of San Francisco. The City of Gilroy lies within the seismically active region of San Francisco Bay.
The City of Gilroy lies in the southern portion of the Santa Clara County and is the most southern
city located within the county. The City is located approximately 32 miles southeast of the City of
San Jose, 8 miles southeast of Morgan Hill, 25 miles east of City of Santa Cruz, and 16 miles
northwest of City of Hollister. The City limits currently encompass 16.5 square miles, with an
approximate population of 56,600 residents, according to the Department of Finance as of
January 2021. Figure 1.1 displays the City’s location.
The City of Gilroy is generally bound to the north by Fitzgerald Ave, to the northeast by San
Ysidro Avenue, to the southeast by Camino Arroyo, to the west by Burchell Road and Rancho
Vista Drive, and to the south by Carnadero Avenue. The U.S. Route 101 divides the City in a
southeast to northwest direction and the California State Route 152 (Hecker Pass Hwy) runs east-
west direction in the northern half of the City. The topography is relatively flat in the middle of the
service area, with increasing slopes in the east and west side of the city due to the Santa Cruz
Mountains to the west and the Diablo Range to the east. Figure 2.1 displays the planning area
showing city limits, the Urban Growth Boundary (UGC) of the City and Planning Area / Sphere of
Influence (SOI).
The City operates and maintains a domestic water system that covers the majority of the area
within the service area limits. Currently, the water demands are provided from groundwater wells
located throughout the service area.
2.2 WATER SERVICE AREA AND LAND USE
The City’s domestic water system services residential and non-residential lands within the City
limits, as summarized on Table 2.1 and shown graphically on Figure 2.2. Areas within the City’s
existing service area include:
5,429 acres of developed lands inside the City limits
3,673 acres of undeveloped lands inside the City limits.
At ultimate development of the General Plan, the City’s domestic water system is anticipated to
serve approximately 3,045 acres of residential land use, 4,750 acres of non-residential land use,
March 2023 2-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 528 of 768
101 Coyote
Reservoir
152 152
City of Gilroy
101 152
101
25
Legend Figure 2.1
Planning Area
Water System Master Plan
City of Gilroy
City Limits General Plan Area
City Limits Area Roads
HighwaysSpecific Plan Areas
Urban Service Area Railroads
Urban Growth Boundary
Sphere of Influence Boundary
Rivers & Creeks
Waterbodies GIS
0 0.5 1 2Updated: September 21, 2020 Miles
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig2-1PlanningArea_092120.mxd
Agenda Item 9.2
Page 529 of 768
Legend101
Existing Land Use
Low Density Residentia
Medium Density Residential
High Density Residential
Neighborhood District
Public/Quasi-Public Facility
Educational Facility
Professional Office
General Services Commercial
Visitor-Serving Commercial
Industrial
Open Space
Park and Recreation Facility
Vacant152
City Limits152
Roads
Railroads
Rivers & Creeks
Waterbodies
25
101
Figure 2.2
Existing Land Use
Water System Master Plan
City of Gilroy
GIS
0 0.5 1 2
Updated: September 21, 2020 Miles
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Agenda Item 9.2
Page 530 of 768
Table 2.1 General Plan Land Use
Water System Master Plan
City of Gilroy
Existing Development
Within City Limits
Future Development Total Development
Subtotal
Existing
Within City Limits Subtotal
Future
Development
General Plan Land Use
Classification
Existing Land Use
Classification
Urban Growth
Boundary
Urban Growth Sphere of
InfluenceDevelopment -Boundary
Existing Lands -
Redeveloping
Unchanged New Lands -
Redevelopment
New
DevelopmentExisting
(acre)(acre)(acre)(acre)(acre)(acre)(acre)(acre)(acre)
Residential
Rural Residential
Hillside Residential
-0 0 0 0 0
344
45
4
0
8
0 0 0
Hillside Residential 444 -1 442
1,583
58
112
122
177
18
464
211
183
36
907 913
Low Density Residential
Medium Density Residential
High Density Residential
Low Density Residential
Medium Density Residential
High Density Residential
Subtotal - Residential
1,704
100
-121
-42
44
2
1,794
240
4,221
248
249 -182
-346
67 15
408
3 104 111
2,496 2,151 429 58 895 3,045 5,493
Non-Residential
Visitor Serving Commercial
General Services Commercial
Visitor Serving Commercial 99
524
1
-67
-91
0
32
432
1
176
106
0
0
55
0
0
44
0
176
205
0
208
637
1
208
837
1
General Services Commercial
Professional Office
General Industrial General Industrial 320
56
12
596
94
0
-71
-12
-5
249
44
7
213
0
255
0
389
0
856
0
1,105
44
2,036
44Campus Industrial
Educational Facility
Public/Quasi-Public Facility
Neighborhood District
City Gateway District
Educational Facility 1 0 0 1 8 22
Public/Quasi-Public Facility -44
-94
0
552
0
152
38
102
22
7
28
336
0
281
395
27
833
395
27
1,013
428
27
Neighborhood District
-0 20
Downtown Specific Plan Area
Mixed Use Corridor High
Hecker Pass Special Use District
Glen Loma Ranch
-0 0 0 57 32
7
0 89 89 89
-0 0 0 25 0 33 33 33
-0 0 0 328
103
43
88
237
40
30
876
0 416
341
83
416
341
83
416
341
83
-0 0 0 0
Industrial Park -0 0 0 0
Employment Center -0 0 0 279
1,541
222
1,017
530
3,434
530
4,750
530
6,109Subtotal - Non-Residential 1,701 -384 1,317
Other
Agriculture
Park and Recreation Facility
Vacant
-
Park and Recreation Facility
Vacant
0 0 0
995
0
0
0
0
66
0
88
0
0
154
0
0 0
1,232
2,391
1,282
0
-238
-2,391
-1,030
0
1,149
0
2,392
000
Open Space Open Space
-
253
0
0 1,041
0
4 1,045
30
1,298
30
2,897
17,726
23,015
Rural County 28
28
3
Subtotal - Other 4,905 -3,658 1,247 1,107 95 1,230 2,477
Total
Total Developed Area 9,102 -4,388 4,714 1,997 2,391 1,170 5,558 10,272 34,616
0 5/12/2021
Notes:
1. Source: City of Gilroy General Plan Alternatives Report, Public Review Draft July 2019.
2. Specific Plan land use types (Downtown, Hecker Pass, Glen Loma) are comprised of multiple land use types. As such, existing land use acreages reflect existing Specific Plan development under current existing land use designations.
Agenda Item 9.2
Page 531 of 768
and 2,477 acres of other (open space and parks) land use, for a total of 10,272 acres inside the
City’s Urban Growth Boundary (Table 2.1). The land use designations used in this master plan
are consistent with the City’s 2040 General Plan. The Land Use Element received from the City’s
Planning Division is shown on Figure 2.3.
In addition to the General Plan Land Use documented on Figure 2.3, there are multiple areas of
known development, which are defined by Specific Plans or other development planning
information. These known development areas provide a more refined definition of planned land
uses, which is critical for estimating future demands. The known development areas are
summarized on Figure 2.3, with the land use information shown on Table 2.1. Based on a review
of aerial imagery and existing land use information, some known development areas are partially
developed or completely developed. The known development areas are summarized in the
following sections.
Hecker Pass Specific Plan: This development area includes approximately 416 acres,
which includes 164 acres of residential, 154 acres of non-residential, and 98 acres of other
land use as documented in Table 2.2.
Glen Loma Specific Plan: This development area includes approximately 341 acres,
which includes 210 acres of residential, 35 acres of non-residential, and 96 acres of other
land use as documented in Table 2.2.
Downtown Specific Plan: This development area includes approximately 202 acres,
which includes 108 acres of residential and 94 acres of non-residential land use as
documented in Table 2.3. This development area is comprised of multiple land use
districts as summarized in the following sections.
o Historic Land Use District: This development area includes approximately 18
acres, which includes 8 acres of residential and 10 acres of non-residential land
use.
o VTA Transit-Oriented Development: This development area includes
approximately 8 acres, which is mostly residential (7.5 acres) with very limited non-
residential land use (0.3 acres).
o Expansion Land Use District: This development area includes approximately 48
acres, which includes 21 acres of residential and 27 acres of non-residential land
use.
o Cannery Land Use District: This development area includes approximately 37
acres, which includes 11 acres of residential and 26 acres of non-residential land
use.
March 2023 2-5 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 532 of 768
Legend101
Planning Area/Sphere of Influence
Urban Growth Boundary
City Limits
General Plan Land Use
Hillside Residential
Low Density Residential
Medium Density Residential
High Density Residential
General Services Commercial
City Gateway District
Visitor Serving Commercial
General Industrial
Employment Center
Industrial Park152
Public and Quasi-Public Facility
Neighborhood District
Mixed Use
152
Rural County
Open Space
Park and Recreation Facility
Specific Plan Areas
Downtown
Glen Loma Ranch
Hecker Pass
Roads
Railroads
Rivers & Creeks
25 Waterbodies
101
Figure 2.3
2040 General Plan
Land Use
Water System Master Plan
City of Gilroy
GIS
0 0.5 1 2
Updated: December 6, 2019 Miles
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Agenda Item 9.2
Page 533 of 768
Table 2.2 Glen Loma and Hecker Pass Specific Plans, Remaining Development Water Demand
Water Master Plan
City of Gilroy
Land Use Types
Residential Non-Residential Other
Specific Plan Units Total
Total Development1
Hecker Pass
Glen Loma
Acres
Acres
46.2
0.0
16.3
112.9
129.2
99.1
70.3
2.2 58.0 0.0 95.7 51.7
0.0
46.8
95.7
416.0
341.0
757.0
26.5
28.7
0.0 26.9
26.9
8.7
Subtotal 46.2 169.5 58.0 104.3 51.7 142.5
Existing Development2
Hecker Pass
Glen Loma
Acres
Acres
11.2
0.0
7.6 89.3
70.3
0.0
0.3
0.3
36.8
0.0
0.0 95.7
3.9
16.6
0.0
0.1 257.1
154.7
411.9
33.7
41.2
24.5
24.5
22.0
22.1Subtotal11.2 159.6 36.8 99.6 16.6
Remaining Development3
Hecker Pass
Glen Loma
Acres
Acres
35.0
0.0
8.8 9.9
0.0
9.9
2.2 21.2
0.0
0.0
2.3
2.3
0.0
4.8
4.8
35.1
0.0
46.7
73.8
158.8
186.3
345.1
79.2
88.0
26.2
28.4Subtotal35.0 21.2 35.1 120.5
Existing Average Daily Demand
(1,270 (2,000 (3,280 (4,260 (1,100 (180 (410 (0 (0
gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre)
Hecker Pass
Glen Loma
gpd
gpd
14,199
0
15,112
67,314
82,426
292,754
230,747
523,501
20 40,450
0
0 39,221
1,604
0
0
0
0
0
0
401,756
305,472
707,228
1,390
1,410
4,417
4,417Subtotal14,199 40,450 40,825
Remaining Average Day Demand
(1,270 (2,000 (3,280 (4,260 (1,100 (180 (410 (0 (0
gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre) gdp/acre)
Hecker Pass
Glen Loma
gpd
gpd
44,505
0
17,527
158,482
176,009
32,337
0
9,333 23,306
0
0 0 0
0
0
0
0
0
127,007
272,320
399,327
111,465
120,798
418
418
1,954
1,954Subtotal44,505 32,337 23,306
2/25/2022
Notes:
1. Unless noted otherwise, development information shown based on Final Hecker Pass Specific Plan (May 2015) and Glen Loma Ranch Specific Plan (May 2014).
2. Existing development area based on a combination of City of Gilroy General Plan Land Use and aerial imagery review.
3. Remaining development area based on a combination of City of Gilroy General Plan Land Use and aerial imagery review.
Agenda Item 9.2
Page 534 of 768
Table 2.3 Downtown Specific Plan, Redevelopment and New Development Water Demand
Water Master Plan
City of Gilroy
Estimated Land Use Development and Land UseLand Use Properties1 Unit Factors Additional Water
Demand forBreakdown2Assumptions
Redevelopment and
New Development8Total
Dwelling
Units2
Existing
Development Development Development
Re-New Total
Buildout
Residential CommercialLand Use District Residential Commercial Residential4 Commercial5,6 Weighted7
Density3 Density2
(acres)
2
(acres)
3
(acres)
4
(acres)
5
%
6
%
7
DU DU/acre
9
FAR
10
gpd/acre
11
gpd/acre
12
gpd/acre
13
(gpd)
1418
Historic 5.4
-
0.8
7.8
11.7
0.0
17.9
7.8
44%
96%
44%
29%
69%
40%
73%
56%
4%
56
320
448
760
79
3.1
41.0
9.4
2.5
2.5
2.5
2.0
1.5
1.5
0.75
594
7,792
1,776
3,877
735
2,750
2,750
2,750
2,200
1,650
1,650
825
1,801
7,614
2,321
2,686
1,019
1,052
629
22,529
59,388
34,250
77,319
280
VTA Transit-Oriented
Development 9
Expansion 33.2
8.4
5.8 9.0 47.9
37.2
20.4
17.0
54.3
202.5
56%
71%
31%
60%
27%
Cannery District
Transitional
Civic/Residential Only
Gateway
17.4
0.28
1.3
11.4
0.0
20.4
3.920.1
14.8
31.2
113.1
1.0 14 0.8 156 2,361
11.7
45.0
11.4
44.4
159
1,836
2.9 556 14,499
Total 210,626
5/12/2021
Notes:
1. Development area based on a combination of City of Gilroy General Plan Land Use, Downtown Gilroy Specific Plan, and aerial imagery review.
2. Source: Downtown Gilroy Specific Plan.
3. Residential Density calculated based on Total Dwelling Units and Total Buildout Acres.
4. Residential Unit Factor based on assumed residential density and a per dwelling unit consumption of 190 gpd/DU, which is estimated based on total High Density Residential consumption and number of dwelling units
5. Factors adjusted to account for increase in FAR.
6. WSMP Commercial Unit Factor of 1,100 gpd/acre assumes a FAR of 1.0.
7. Weighted unit factor based on Estimated Land Use Breakdown and Master Plan Unit Factors.
8. Additional water demand for new development and redevelopment estimated using weighted water unit factor.
Agenda Item 9.2
Page 535 of 768
o Transitional Land Use District: This development area includes approximately 20
acres, which includes 14 acres of residential and 6 acres of non-residential land
use.
o Civic/Residential Only Land Use District: This development area includes
approximately 17 acres, which includes 7 acres of residential and 10 acres of non-
residential land use.
o Gateway Land Use District: This development area includes approximately 54
acres, which includes 40 acres of residential and 14 acres of non-residential land
use.
2.3 HISTORICAL AND FUTURE GROWTH
According to the California Department of Finance (DOF) population estimates, the 2021 City
population is approximately 56,559 people. From 2015 to present, the City’s service area has
observed an average annual growth rate of approximately 0.7%. This 2022 WSMP is consistent
with the City’s 2020 Urban Water Management Plans (UWMP’s) annual growth rate factor of
1.5%. The current and projected service area population is summarized in Table 2.4.
Estimates of future water demands were not based on population, but rather on gross acreage for
residential and non-residential land uses. Future population was used as a means for estimating
the planning horizon of the domestic water system.
March 2023 2-9 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 536 of 768
Table 2. Historical and Projected Population
Water System Master Plan
City of Gilroy
Annual GrowthYearPopulation1,2
(%)
Historical
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
41,464
42,436
43,144
43,866
45,026
45,782
46,446
47,047
48,353
48,627
48,821
49,622
50,716
52,475
53,325
54,233
54,849
55,811
56,030
56,635
56,704
2.3%
1.7%
1.7%
2.6%
1.7%
1.5%
1.3%
2.8%
0.6%
0.4%
1.6%
2.2%
3.5%
1.6%
1.7%
1.1%
1.8%
0.4%
1.1%
0.1%
Projected
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
57,555
58,418
59,294
60,184
61,086
62,003
62,933
63,877
64,835
65,807
66,794
67,796
68,813
69,845
70,893
71,957
73,036
74,131
75,243
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
76,3722040 1.5%
8/31/2021
Notes:
1. Historical populations extracted from California Department of Finance, Population Estimates E 4.
2. Projected population assuming medium annual growth rate of 1.5% per the City of Gilroy 2020 Urban Water Management Plan.
Agenda Item 9.2
Page 537 of 768
2023City of Gilroy
CHAPTER 3 – SYSTEM PERFORMANCE AND DESIGN CRITERIA
This chapter presents the City’s performance and design criteria, which was used in this analysis
for identifying current system capacity deficiencies and for sizing proposed distribution mains,
storage reservoirs, and wells.
3.1 HISTORICAL WATER USE TRENDS
The historical domestic water consumption per capita was calculated to determine the average
water use per capita per day. This was accomplished by dividing the City’s historical water
production by the historical population for the respective year.
The City’s historical per capita consumption factors, for the period 2000-2019, are listed in Table
3.1. The City’s per capita consumption has generally decreased since 2008 by approximately
16%. This trend is largely attributed to the City’s effort of implementing water conservation
measures. Table 3.2 lists the last three years of monthly water production in the City from 2017 to
2019.
The ultimate demand forecasts included in this master plan for residential and non-residential land
uses is based on net acreages. However, to generalize trends in the City’s water use, per capita
water use was documented. Figure 3.1 displays the historical population in relation to average
daily water production. Figure 3.2 displays a comparison in the per capita water use and average
daily water production. The remainder of the City’s criteria are summarized in the following
sections and on Table 3.3.
3.2 SUPPLY CRITERIA
In determining the adequacy of the domestic water supply facilities, the source must be large
enough to meet the varying water demand conditions, as well as provide sufficient water during
potential emergencies such as power outages and natural or created disasters.
Ideally, a water distribution system should be operated at a constant water supply rate with
consistent supply from the water source. On the day of maximum demand, it is desirable to
maintain a water supply rate equal to the maximum day rate. Water required for peak hour
demands or for fire flows would come from storage.
As the City is currently using groundwater wells as a sole source of supply, groundwater should
be viewed as a sustainable resource. With little available existing storage in the system to supply
during peak period usage, supply wells should be capable of meeting maximum day demand,
including a 1,805 gallon per minute (gpm) standby capacity. The design criteria for water supply
are documented on Table 3.3.
March 2023 3-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 538 of 768
70,000
67,000
64,000
61,000
58,000
55,000
52,000
49,000
46,000
43,000
40,000
10
9
8
7
6
5
4
3
2
1
0
8.38.2 8.2
7.9 7.77.67.4 7.3 7.37.1 7.1 7.1 7.17.0 7.06.9 7.0 6.9
6.26.1
54,123
48,821
45,782
41,464
2000 2005 2010 2015 2020
Year
LEGEND Figure 3.1
Historical Population vs.Population
Average Daily Production
Water System Master Plan
City of Gilroy
Average Daily Production (MGD)
September 18, 2020
Agenda Item 9.2
Page 539 of 768
250
225
200
175
150
125
100
9
8
7
6
5
4
8.38.28.2
7.9
7.77.67.4 7.3 7.3
7.1 7.17.1 7.17.0 7.07.06.9 6.9
174171 171 6.1168 6.2167165165161159155156152
147146
138
125 125 121
113 113
3
2000 2005 2010 2015 2020
Year
LEGEND Figure 3.2
Water Use Per Capita vs.Water Use Per Capita (gpdc)
Average Daily Production (MGD)Average Daily Production
Water System Master Plan
City of Gilroy
September 18, 2020
Agenda Item 9.2
Page 540 of 768
Table 3.1 Historical Water Production and Maximum Day Peaking Factors (2000-2019)
Water System Master Plan
City of Gilroy
Historical Water Production
Average Daily
Water Use per
Capita
%Monthly ProductionYearPopulation1
Increase Annual Production2 % Increase Month of Max-to-Average Maximum3,4
Occur.Avg Ratio
(AF)(MGY)
2,542
(gpm)
4,836
(MGM)
212
(MGM)
308
(gpdc)
1682000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
41,464
42,436
43,144
43,866
45,026
45,782
46,446
47,047
48,353
48,627
48,821
49,611
50,698
52,378
53,208
54,123
54,916
55,932
56,198
56,854
-7,800 -August
July
1.46
1.48
1.43
1.60
1.47
1.61
1.61
1.46
1.61
1.54
1.56
1.47
1.48
1.54
1.42
1.24
1.44
1.44
1.43
1.43
2%
2%
2%
3%
2%
1%
1%
3%
1%
0%
2%
2%
3%
2%
2%
1%
2%
0%
1%
8,006
8,498
7,897
8,333
7,961
8,898
9,190
9,261
8,475
7,986
8,186
8,642
9,324
8,208
6,870
6,977
7,814
7,854
7,691
2,609
2,769
2,573
2,715
2,594
2,899
2,995
3,017
2,762
2,602
2,667
2,816
3,038
2,675
2,239
2,273
2,546
2,559
2,506
4,963
5,269
4,896
5,166
4,936
5,516
5,698
5,741
5,254
4,951
5,075
5,358
5,781
5,089
4,259
4,325
4,844
4,869
4,768
3%217
231
214
226
216
242
250
251
230
217
222
235
253
223
187
189
212
213
209
323
330
342
332
348
389
365
404
355
337
327
348
390
316
232
273
305
305
299
168
176
161
165
155
171
174
171
156
146
147
152
159
138
113
113
125
125
121
6%July
-7%
6%
July
July
-4%
12%
3%
August
August
July
1%July
-8%
-6%
3%
June
July
August
July6%
8%June
July-12%
-16%
2%
July
July
12%
1%
July
July
-2%August
Historical Maximum Month Peaking Factors
10-Year Maximum (2010-2019)
5-Year Maximum (2015-2019)
3-Year Maximum (2017-2019)
Last Year's Maximum (2019)
9,324
7,854
7,854
7,691
3,038
2,559
2,559
2,506
5,781
4,869
4,869
4,768
12%
12%
12%
-2%
253
213
213
209
390
305
305
299
1.56
1.44
1.44
1.43
159
125
125
121
2020 Water System Master Plan Peaking Factors
Maximum Month Demand
Maximum Day Demand
1.5 x Average Day Demand
2.0 x Average Day Demand
9/21/2020
Notes:
1. Source: Historical populations extracted from California Department of Finance, Population Estimates E-4.
2. Source: Years 2000-2010, 2010 Urban Water Management Plan. Years 2011-2019, Monthly Well Production Data received from City staff.
Agenda Item 9.2
Page 541 of 768
Table 3.2 Historical Monthly Water Production (2017-2019)
Water System Master Plan
City of Gilroy
2017 2018 2019
Daily
Production
Peaking
Factor
Daily
Production
Peaking
Factor
Daily
Production
Peaking
FactorMonthlyMonthlyMonthlyMonth
Percent of
Annual
Month to Avg
Factor
Percent of
Annual
Month to Avg
Factor
Percent of
Annual
Month to Avg
FactorAverage Day Production Average Day Production Average Day Production
(MGD)(MGM)(%)(MGD)(MGM)(%)(MGD)(MGM)(%)
January
February
March
4.29
4.19
4.74
5.37
8.10
9.31
9.85
9.74
9.17
8.16
5.60
5.00
133
117
147
161
251
279
305
302
275
253
168
155
5%
5%
0.63
0.55
0.69
0.76
1.18
1.32
1.44
1.42
1.30
1.19
0.79
0.73
4.48
5.07
4.58
5.63
7.94
9.10
9.84
9.68
8.87
7.94
6.43
4.45
139
142
142
169
246
273
305
300
266
246
193
138
5%
6%
0.65
0.67
0.67
0.79
1.15
1.28
1.43
1.41
1.25
1.15
0.91
0.65
4.26
4.14
4.29
5.83
7.13
8.70
9.61
9.65
9.23
8.13
6.83
4.45
132
116
133
175
221
261
298
299
277
252
205
138
5%
5%
0.63
0.56
0.64
0.84
1.06
1.25
1.43
1.43
1.33
1.21
0.98
0.66
6%6%5%
April 6%7%7%
May 10%
11%
12%
12%
11%
10%
7%
10%
11%
12%
12%
10%
10%
8%
9%
June 10%
12%
12%
11%
10%
8%
July
August
September
October
November
December 6%5%6%
Total
Average Value
Maximum Value
2,547
212
305
2,559
213
305
2,507
209
299
6.96 7.00 6.85
1.44 1.43 1.43
9/21/2020
Note:
1. Source: 2017-2019 Monthly Well Production provided by City Staff on June 5, 2020.
Agenda Item 9.2
Page 542 of 768
Table 3.3 Planning and Design Criteria Summary
Water System Master Plan
City of Gilroy
Design Parameter Criteria
Supply Supply = Maximum Day Demand + Standby Well (1,805 gpm)
Storage Total Required Storage = Operational + Fire + Emergency
For Pressure Zone 1
Operational Storage
Fire Storage
25% of Maximum Day Demand
Varies
Emergency Storage
For Pressure Zones 2 and 3
Operational Storage
Fire Storage
25% of Maximum Day Demand
25% of Maximum Day Demand
Varies
Emergency Storage 50% of Maximum Day Demand
Booster Pumps Pumping Capacity = Maximum Day Demand
Distribution Mains Distribution mains should be designed to meet the greater of:
1) Peak Hour Demand, or 2) Maximum Day Demand + Fire Flow
Criteria for existing and future pipelines include:
Maximum pipe velocity of 8 feet per second
Maximum friction losses of 10 feet / 1,000 feet
Maximum PressureService Pressures 80 psi
40 psi
35 psi
40 psi
20 psi
Minimum Pressure (during Maximum Day)
Minimum Pressure (during Peak Hour)
Minimum Pressure for New Development1 (during Peak Hour)
Minimum Residual Pressure (during Fires)
Demand Peaking Factors Maximum Month Demand
Maximum Day Demand
Peak Hour Demand
Residential
1.50 x Average Day Demand
2.00 x Average Day Demand
3.00 x Average Day Demand
1,500 gpm for 2 hoursFire Flows
Commercial 2,500 gpm for 2 hours
Industrial 5,000 gpm for 3 hours
2Time-of-Use Time-of-Use considerations account for off-peak energy rate schedule before
4 PM and after 9 PM (19-hour pumping period).
Urban Water Use Targets
2020 Urban Water Management Plan Existing Coefficient 166 gpdc
149 gpdc
133 gpdc
2015 Interim Target
2020 Target (20% Conservation)
5/11/2021
Notes:
1. Unless otherwise noted, criteria is based on California Department of Public Health Title 22, Chapter 16, Article 8.
2. Source: PG&E Time-of-Use Pricing Schedule.
Agenda Item 9.2
Page 543 of 768
Each new supply well should have adequate connections to power facilities, and every 4 th well
should have provisions for a backup power generator. For the purposes of this master plan, every
10th well was assumed to have provisions for water quality treatment.
3.3 STORAGE CRITERIA
The intent of domestic water storage is to provide adequate supply for operation equalization,
emergency conditions and fire protection. Operational or equalization storage provides the
difference in quantity between the customer’s peak hour demands and the system’s available
reliable supply. Emergency storage allows the system to maintain service pressures in the event
of emergency, such as system failure or power outages. Fire protection storage provides
adequate supply to mitigate potential fire hazards while maintaining adequate service pressure.
3.3.1 Typical Storage Criteria
City of Gilroy’s storage criteria consists of three main elements: operational, emergency, and fire
storage. These elements can typically vary for each pressure zone depending on key factors
including service population and demands. The storage criteria used for this master plan is
described below and documented in Table 3.3.
Operational Storage
Operational or equalization storage capacity is necessary to reduce the variations imposed on the
supply system by daily demand fluctuations. Peak hour demands may require up to 1.5 times the
amount of maximum day supply capacity. With storage in place, this increase in demand can be
met by the operational storage rather than by increasing production from the supply sources.
Equalization storage also stabilizes system pressures for enhancing the service. Equalization
storage requirements typically range from 25 percent to 50 percent of maximum day demand. For
all three pressure zones, the City criterion requires that 25 percent of the maximum day demand
be reserved for operational storage.
Emergency Storage
Emergency storage is the volume of water stored to meet demand during emergency situations
such as pipe failures, distribution main failures, pump failures, power outages, natural disasters,
or other cases in which the supply sources are not able to meet the demand condition.
The amount of water reserved for emergencies is determined by policies adopted by the City and
is based on an assessment of the costs and benefits including the desired degree of system
reliability, risk during an emergency situation, economic considerations, and water quality
concerns.
In California, the amount of emergency storage reserve in municipal water systems is usually
between 25 percent and 100 percent of the maximum day demand. The City criterion requires that
March 2023 3-7 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 544 of 768
25 percent of the maximum day demand for Pressure Zone 1 be reserved for emergency storage.
Additionally, the City criterion requires that 50 percent of the maximum day demand for Pressure
Zone 2 and Zone 3 be reserved for emergency storage.
Fire Storage Requirement
Fire storage is also needed to maintain acceptable service pressures within a service zone, in the
event of a fire flow, which may occur during the maximum day demand. The recommended fire
storage capacity varies by land use type, and is usually higher for commercial and industrial
areas. Fire flow provisions were calculated based on the governing (highest) land use type within
the reservoir service area as follows:
Residential: 1,500 gpm for 2 hours = 0.18 MG
Commercial/Public Facility: 2,500 gpm for 2 hours = 0.30 MG
Industrial: 5,000 gpm for 3 hours = 0.90 MG
Total Storage Requirement
For pressure zone 1, the total storage is the summation of operational (equalization), fire, and
emergency storage requirements as follows:
Qs = 25% MDD (equalization) + fire flow (varies) + 25% MDD (emergency)
For pressure zones 2 and 3, the total storage is the summation of operational (equalization), fire,
and emergency storage requirements as follows:
Qs = 25% MDD (equalization) + fire flow (varies) + 50% MDD (emergency)
where:
Qs is the Total Required Storage, in gallons
MDD is the Maximum Day Demand, in gallons
3.4 PRESSURE CRITERIA
Acceptable service pressures within distribution systems vary depending on City criteria and
pressure zone topography. It is essential that the water pressure in a consumer’s residence or
place of business be maintained within an acceptable range. Low pressures below 30 psi can
cause undesirable flow reductions when multiple faucets or water using appliances are used at
once.
Excessively high pressures can cause faucets to leak and valve seats to wear out prematurely.
Additionally, high service pressures can cause unnecessarily high flow rates, which can result in
March 2023 3-8 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 545 of 768
wasted water and high utility bills. The criteria for pressures in the domestic water system include
the following:
Maximum pressure, usually experienced during low demands and winter months
Minimum pressure, usually experienced during peak hour demands and summer months
Minimum pressure during fire flows and during the maximum day demand
The American Water Works Association Manual on Computer Modeling and Water Distribution
System (AWWA M-32) indicates that maximum pressures are usually in the range of 90-110
pounds per square inch (psi). In some communities, the maximum pressure may be limited to 80
psi to mitigate the impact on internal plumbing. In this case, the distribution system is usually
sized for the higher pressures, and individual pressure-reducing valves are installed on service
lines where the pressure may be exceeded.
The minimum acceptable pressure is usually in the range of 40-50 psi, which generally provides
for sufficient pressures for second story fixtures. When backflow preventers are required, they
may reduce the pressures by approximately 5-15 psi. The recommended minimum pressure
during fire flows is 20 psi, as established by the National Fire Protection Association (NFPA).
The City’s pressure criteria are summarized as follows:
Maximum pressure: 80 psi
Minimum pressure: 40 psi during maximum day and 35 psi during peak hour demands,
and 40 psi for new developments during peak hour demands
Minimum pressure during fire flows: 20 psi
3.5 UNIT FACTORS
Domestic water demand unit factors are coefficients commonly used in planning level analysis to
estimate future average daily demands for areas with predetermined land uses. The unit factors
are multiplied by the number of dwelling units or gross acreages for residential categories, and by
the gross acreages for non-residential categories, to yield the average daily demand projections.
There are several methods for developing the unit factors. This analysis relied on the City’s 2019
Public Water System Statistics (PWSS) report, which lists the monthly water consumption by land
use type in the City, to estimate the unit factors within the City service area.
The total domestic water demand was calculated from the consumption data. The demand was
adjusted to balance with current production records, and to account for transmission main losses
and vacancies in existing land uses. The demand unit factor was then calculated using the total
water production and total number of residential and non-residential land use acreages.
March 2023 3-9 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 546 of 768
The analysis generally indicates that existing single family residential, multiple family residential,
public and park land uses have higher consumptive use factors than that of other land uses. The
existing unit factor analysis is shown on Table 3.4. The recommended water unit factors for the
City’s General Plan land use designations are summarized in Table 3.5.
3.6 SEASONAL DEMANDS AND PEAKING FACTORS
Domestic water demands within municipal water systems vary with the time of day and month of
the year. It is necessary to quantify this variability in demand so that the water distribution system
can be evaluated and designed to provide reliable water service under these variable demand
conditions.
Water use conditions that are of particular importance to water distribution systems include the
average day demand (ADD), the maximum month demand (MMD), the maximum day demand
(MDD), the peak hour demand (PHD), and the minimum month demand (MinMD).
The average day demand represents the annual water demand, divided by 365 days, since it is
expressed in daily units. The minimum month demand typically represents the low month water
demands (winter) and is used for simulating water quality analysis.
3.6.1 Maximum Month Demand
The maximum month demand (MMD) is the highest demand that occurs within a calendar month
during a year. The City’s MMD usually occurs in the summer months in either July or August. The
MMD is used primarily in the evaluation of supply capabilities.
Historical monthly water production records, obtained for the period between 2000 and 2019
(Table 3.1), indicate the maximum month to average month ratio ranging between 1.2 and 1.6.
Over the reviewed period, this ratio neither showed significant increasing or decreasing trends.
Therefore, an MMD factor of 1.5 was deemed representative of trends in the City of Gilroy. This is
a slight decrease in the peaking factor of 1.6 used in the 2004 master plan. The following equation
is recommended for estimating the maximum month demand, given the average day demand:
Maximum Month Demand = 1.5 x Average Day Demand
3.6.2 Maximum Day Demand
The maximum day demand (MDD) is the highest demand that occurs within a 24 hour day during
a year. The City’s MDD, which usually occurs during the summer months, is typically used for the
evaluation and design of storage facilities, distribution mains, pump stations, and pressure
reducing valves. The MDD, when combined with fire flows, is one of the highest demands that
these facilities should be able to service while maintaining acceptable pressures within the
system.
March 2023 3-10 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 547 of 768
Table 3.4 Water Demand Unit Factor Analysis
Water System Master Plan
City of Gilroy
Existing Average Daily Water Demand Unit Factors
Existing
Development within
City Limits
Consumption1 Production2 Production at 100% Occupancy3,4,5 Recommended Water Unit Factor
Balance Using
Existing Land Use Classification
Unadjusted Water
Unit Factors
Unadjusted Water Production (w/o
Vacancy rate)
Projected Production at 100%
Occupancy
Recommended
FactorAnnual Consumption Vacancy Rate Recommended Unit
FactorUnit Factors
(acres)(gpd/acres)(kgal/year)(gpd)(gpd/acres)(gpd)(%)(gpd/acres)(gpd)(gpd/acres)(gpd)
Residential
Hillside Residential 444
1,704
100
1,128
1,785
2,923
3,799
182,582
1,110,017
106,181
500,226
3,041,144
290,906
1,219
1,929
3,160
4,107
540,815
3,287,904
314,510
3.5%
3.5%
3.5%
3.5%
1,262
1,997
3,271
4,251
559,743
3,402,981
325,518
1,270
2,000
3,280
4,260
563,307
3,408,180
326,448
Low Density Residential
Medium Density Residential
High Density Residential
Subtotal - Residential
249 345,322 946,088 1,022,855
5,166,084
1,058,655
5,346,897
1,061,015
5,358,9512,496 1,744,103 4,778,364
Non-Residential
Office and Commercial6 623
376
608
94
938
892
213,440
122,486
35,256
584,767
335,578
96,592
1,014
964
632,216
362,807
104,430
102,759
1,202,212
7.5%
2.0%
2.0%
3.5%
1,090
983
679,632
370,064
106,519
106,356
1,262,570
1,100
990
685,641
372,542
109,388
106,774
1,274,344
Industrial7
Public Facility / Institution8 159 172 175 180
Neighborhood District 1,015 34,692 95,047 1,097 1,136 1,140
Subtotal - Non-Residential
Other
1,701 405,875 1,111,985
Park and Recreation Facility 1,232
2,391
374
0
168,058
0
460,432
0
404
0
497,792
0
0
0
0
404
0
497,792
0
410
0
505,174
0Vacant
Open Space 1,282 0 0 0 0 0 0 0 0 0
Subtotal - Other 4,905 168,058 460,432 497,792 497,792 505,174
6,866,088 7,138,469Total Developed Area 9,102 2,318,035 6,350,781 7,107,258
4/27/2021
Notes:
1. 2019 Water Consumption provided by City staff on August 12, 2020.
2. In order to account for water system losses and other unmetered consumption, production was assumed to be equal to consumption increased by 8% based on Akel Engineering Group experience.
3. Residential vacancy rate extracted from California Department of Finance Sheet E-5 published 2020.
4. Office and Commercial vacancy rate extracted from Cushman & Wakefield Silicon Valley Retail MarketBeat report published Q2 2020.
5. Industrial vacancy rate extracted from Cushman & Wakefield Silicon Valley Industrial MarketBeat report published Q2 2020.
6. "Office and Commercial" contains development and consumption for "Visitor Serving Commercial", "General Services Commercial", and "Professional Office".
7. "Industrial" contains development and consumption for "General Industrial" and "Campus Industrial".
8. "Public Facility / Institution" contains development and consumption for "Public/Quasi-Public Facility" and "Educational Facility".
Agenda Item 9.2
Page 548 of 768
Table 3.5 Recommended Water Unit Factors
Water System Master Plan
City of Gilroy
Land Use
Classification
Recommended
Factor
(gpd/net acre)
Residential
Hillside Residential 1,270
2,000Low Density Residential
Medium Density Residential
High Density Residential
Non-Residential
3,280
4,260
Office and Commercial
Industrial
1,100
990
Public Facility / Institution
Neighborhood District
Park and Recreation Facility
180
1,140
410
4/27/2021
Agenda Item 9.2
Page 549 of 768
Daily production records were not available for the period between 2000 to 2019. Due to the
limited daily production data, it was determined that a ratio of 2.0 (as recommended by California
Water Board standards) would be used in this master plan. The following equation is then used to
estimate the maximum day demand, given the average day demand:
Maximum Day Demand = 2.0 x Average Day Demand
3.6.3 Peak Hour Demand
The peak hour demand (PHD) is another high demand condition that is used in the evaluation and
design of water distribution systems. The peak hour demand is the highest demand that occurs
within a one hour period during a year. The peak hour demand is considered to be the largest
single measure of the maximum demand placed on the distribution system. The PHD is often
compared to the MDD plus fire flow to determine the largest demand imposed on the system for
the purpose of evaluating distribution mains.
In general, the PHD ranges between 2.5 and 3.5 times greater than the average annual demand.
In the absence of City metering records to assess the City's peak hour factor, and in accordance
with direction from City staff this study recommends a peaking factor of 3.0. This is slightly lower
than the peak use factor of 3.5 used in the previous master plan. The peak hour demand can then
be calculated using the average day demand and the following equation:
Peak Hour Demand = 3.0 x Average Day Demand
3.7 TRANSMISSION AND DISTRIBUTION MAIN CRITERIA
Transmission and distribution mains are usually designed to convey the maximum expected flow
condition. In municipal water systems, this condition is usually the greater of either the peak hour
demand or the maximum day demand plus fire flow. The hydrodynamics of pipe flow create two
additional parameters that are taken into consideration when evaluating or sizing water mains:
head loss and velocity.
Head loss is a loss of energy within pipes that is caused by the frictional effects of the inside
surface of the pipe and friction within the moving fluid itself. Head loss creates a loss in pressure
which is undesirable in water distribution systems. Head loss, by itself, is not an important factor
as long as the pressure criterion has not been violated. However, high head loss may be an
indicator that the pipe is nearing the limit of its carrying capacity and may not have sufficient
capacity to perform under stringent conditions. The City’s criterion for maximum pipeline head loss
is summarized as follow:
Greater of PHD or MDD + Fire Flow: 10 feet per 1,000 feet of pipe.
Since high flow velocities can cause damage to pipes and lead to high head loss, it is desirable to
keep the velocity below a predetermined limit. The City’s criterion for maximum pipeline velocity
used in this master plan is 8 feet per second. This criterion also ensures that the head loss is kept
March 2023 3-13 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 550 of 768
below an acceptable limit, as the head loss in a pipe is a function of the flow velocity. The City’s
criterion. The City’s criteria for maximum pipeline velocity is summarized as follow:
Greater of PHD or MDD + Fire Flow: 8 feet per second.
A summary of the criteria pertaining to transmission and distribution mains is included in Table
3.3. It should be noted that the head loss criteria in transmission mains may be relaxed, where
feasible, to account for transmission main redundancy and reliability. Relaxing of the criteria
requires the review and approval of the City Engineer.
March 2023 3-14 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 551 of 768
2023City of Gilroy
CHAPTER 4 – EXISTING DOMESTIC WATER FACILITIES
This chapter provides a description of the City’s existing domestic water system facilities including
the existing wells, distribution mains, storage reservoirs, and booster station pumps.
4.1 EXISTING WATER SYSTEM OVERVIEW
The City’s municipal water system consists of 9 groundwater wells, 10 storage reservoirs that
have a cumulative capacity of 14.1 MG, and over approximately 202 miles of distribution
pipelines. The City’s generally flat topography slopes up from east to west at approximately 180
feet in the east to approximately 250 feet in the west. Even with this generally flat topography, the
City utilizes three separate pressure zones due to the slopes on the west side.
The City’s existing domestic water distribution system is shown in Figure 4.1, which displays the
existing system by pipe size. This figure provides a general color coding for the distribution mains,
as well as labeling the existing wells and the storage reservoir.
4.2 SOURCE OF SUPPLY
The City currently uses groundwater as the sole source of supply. There are 9 existing
groundwater wells in the City that have been used for supply (Figure 4.1). The rated capacities for
the existing groundwater wells were extracted from the City’s 2004 Water System Master Plan as
well as information provided by City staff. During the summer months, which are typically the peak
for domestic water use, the City operates most available existing wells in some capacity. During
the winter months, which are typically the minimum system demand, all of the wells operate.
During the preparation of this master plan, City operations staff provided well capacity ratings. It
should be noted that, over time, well efficiencies may vary based on equipment conditions and
groundwater levels. In periods of prolonged drought, well efficiency ratings may decrease due to a
decline in groundwater levels. The opposite may occur in wet periods, as well efficiencies may
increase as the groundwater levels recover. As such, the City should monitor the well efficiencies
on a frequent basis to adequately manage the groundwater supply. If periods of prolonged
drought persist, it may be necessary to construct additional wells to maintain adequate supply
capacity.
Table 4.1 lists the City’s current total rated supply at approximately 18.8 million gallons per day
(MGD). Consistent with the system performance and design criteria, the firm capacity was
calculated as the capacity with the largest well out of service. Well No. 3 is the highest typical
yield well with at a capacity of 2,300 gallons per minute (gpm). The firm capacity of the well supply
is estimated at 15.5 MGD.
March 2023 4-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 552 of 768
Legend
Existing System
Tanks
Wells
Booster Pumps
Existing Pipes by Diameter
4" - 6"
8
101
8"
10" - 30"Booster
Station 4Tanks: 2C-1
2C-2 RoadsBooster
Station 3 & 23D-1
3D-2 Booster
Station 1 Railroads
12 Well 5-2
Tank 1A City Limits
Well 7 Urban Growth Boundary
Rivers & Creeks
Waterbodies
152 24 152 Well 2 Well 12424 Well 8
Well 8A
8
152
Well 3-2
Tanks: 2E-1
2E-2
Booster
Station 5
Well 4
Well 6
Booster
Station 6
Tanks: 1B
2F-1
1G-1
1G-2
Figure 4.1
Existing System
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: January 27, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig4-1_ExistingSystem_012721.mxd
Agenda Item 9.2
Page 553 of 768
Table 4. Existing Groundwater Supply Capacity
Water System Master Plan
City of Gilroy
1 2 Additional InformationSpecificationsPump Test Data
Supply Well Well Location Total Dynamic
Head
Ground
ElevationRated Capacity Design Head Pump Test Date Flow Rate Pumping Level Horsepower
(gpm)
1,200
(mgd)(ft)(gpm)
1,113
(ft)(ft)
83
(HP)
107
(ft)
Well 1
Well 2
Well 3
Well 4
Well 5
Well 6
Well 7
Well 8
Well 8A
100 Ioof Avenue
660 1st Street
1.73
1.58
3.31
1.73
2.30
2.16
2.45
3.17
0.35
235 7/23/2020
8/23/2018
7/23/2020
7/23/2020
7/23/2020
9/19/2016
7/23/2020
7/23/2020
7/23/2020
263 200
1,100
2,300
1,200
1,600
1,500
1,700
2,200
240
219
357
266
312
204
206
230
339
841
2,075
1,179
1,718
1,697
1,296
2,414
228
259
290
266
311
253
241
184
646
120
110
105
145
75
97
231
122
204
64
211
192
202
196
189
196
188
188
7325 Forrest Street
695 9th Street
8295 Rosanna Street
6552 Brem Lane
7820 Arroyo Circle
701 Gilliam Road
700 Gilliam Road
71 150
250
94
108
470
Total and Firm Supply Capacity
Total Supply Capacity 13,040
10,740
18.78
15.47
12,561
Firm Capacity (Excluding
largest Well)10,147
5/12/2021
Notes:
1. Unless noted otherwise, information extracted from City of Gilroy 2004 Water System Master Plan, Table 4.1
2. Pump test data extracted from pump efficiency test received from City staff August 20, 2020.
Agenda Item 9.2
Page 554 of 768
4.3 PRESSURE ZONES
The City’s current water system serves communities located between an elevation of 180 feet
above sea level to more than 600 feet. To adequately provide water in the City’s service area, the
water distribution system is divided into multiple pressure zones that operate with varying
pressures between 45 and greater than 100 psi. Figure 4.2 shows the water distribution system
and names for these pressure zones.
4.4 WATER DISTRIBUTION PIPELINES
Groundwater is pumped directly into the City’s distribution system via more than 200 miles of
pipeline with diameters ranging from pipelines 1.0-inches to 30-inches in diameter. The existing
system pipelines are documented on Figure 4.1, and color coded by pipe size. Similarly, Figure
4.2 documents the existing system and color coded by pressure zone serviced
The City’s domestic water system consists mainly of looped network connections. Looped
connections provide an increased capacity and reliability of the distribution system. These
connections allow peak demands and fire flows to be serviced from multiple directions, which
typically relieves the need for large mains.
An inventory of existing pipes, extracted from the GIS-based hydraulic model and used in this
analysis, is included in Table 4.2. For each pipe diameter, the inventory lists the length in feet, as
well as the total length in units of miles. Additionally, standard Hazen-Williams pipe roughness
coefficients used for various materials are included for reference on Table 4.3.
4.5 STORAGE RESERVOIRS
Storage reservoirs are typically incorporated in the water system to provide water supply for
operation during periods of high demand, for meeting fire flow requirements, and for other
emergencies, as defined in the City’s planning criteria.
The City’s existing storage reservoirs are summarized in Table 4.4, along with their volumes,
height, diameter, bottom elevations, SHGL, overflow height and locations. The reservoirs are also
shown on the hydraulic profile schematic (Figure 4.3), with the high-water level and bottom tank
elevation. The City maintains a robust system storage capacity, in excess of 14 million gallons.
4.6 BOOSTER STATIONS
Water is conveyed from the lower supply pressure zones to the higher pressure zones via a series
of booster pump stations. There are a total of 6 booster stations located in the City and listed in
Table 4.5. This table also indicates booster station ground elevation, source and destination
pressure zone, total pump capacity and additional information.
March 2023 4-4 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 555 of 768
Legend
Existing System
Tanks
Wells
Booster Pumps
Existing Pipes by Pressure Zone
Pressure Zone 1
Pressure Zone 2N
Pressure Zone 2S
Pressure Zone 3
Roads
8
101
Booster
Station 4Tanks: 2C-1
2C-2 Booster
Station 3 & 23D-1
3D-2 Booster
Station 1 12 Well 5-2
Tank 1A Railroads
Well 7 City Limits
Urban Growth Boundary
Rivers & Creeks
Waterbodies
152 24 152 Well 2 Well 12424 Well 8
Well 8A
8
152
Well 3-2
Tanks: 2E-1
2E-2
Booster
Station 5
Well 4
Well 6
Booster
Station 6
Tanks: 1B
2F-1
1G-1
1G-2
Figure 4.2
Pipelines by Pressure Zone
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: May 13, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\2014MP\GL_Fig4-2_PipesByPZ_070721.mxd
Agenda Item 9.2
Page 556 of 768
700'
600'
500'
400'
300'
200'
100'
700'
600'
500'
400'
300'
200'
100'
3D-1 3D-2
644 644
0.41 0.41621 MG MG 621
540'
2E-1 2E-2 2F-1 2C-1 2C-2 BS2
533.5 533.5 533.5 533.5 533.5 Mantelli Dr.
540'ZONE 3
SHGL =
644'
BS30.71 0.71 0.71 0.41 0.41510.5 MG MG 510.5 MG 510.5 510.5 MG MG 510.5 Country Club Dr.
490'
430'430'
430'PRV 21G1B1A PRV 3374374374ZONE 2S
SHGL =
533.5'
ZONE 2N
SHGL =
533.5'
BS6 2.00 2.00Miller Ave.3.00347.5 MG MG 347.5 MG 342.5
340'
BS5 BS1
Club Dr.Rancho Hills Ct.PRV 5 280'BS4280'280'280'PRV 6
W 4
Rancho Hills Dr.PRV 1260'PRV 4250'ZONE 1
SHGL =
374'W 1 W 2 W 3 W 5 W 6 W 7 W 8 W 8A W 9
1,200 gpm 1,100 gpm 2,300 gpm 1,200 gpm 1,600 gpm 1,500 gpm 1,700 gpm 2,200 gpm 240 gpm 700 gpm
140'
LEGEND Figure 4.3
ID HIGH
LOW
Reservoir Pressure Zone
HIGH: Highest Service Elevation (ft)
ZONE: Zone ID
SHGL: Static Hydraulic Grade Line
HWL: Lowest Service Elevation (ft)
Existing Hydraulic ProfileHWLID:Tank ID ZONE
SHGL
ID Proposed WellHWL: High Water Level (ft)
VOL: Reservoir Capacity (MG)
LOW: Bottom Elevation (ft)
ID:Well ID
VOL GPM: Well Production (gpm)Schematic
Water System Master Plan
City of Gilroy
LOW MG
GPM
IDBooster Pumping Station Existing Well
ID ID:Booster Station ID ID:Well ID
ELEV: Station Elevation (ft)GPM: Well Production (gpm)
ELEV GPM
ID Pressure Regulating Valve Transmission MainID:Valve ID
Last Updated: 11/29/2021
Agenda Item 9.2
Page 557 of 768
Table 4.2 Existing Modeled Pipe Inventory
Water System Master Plan
City of Gilroy
Pipe Length by MaterialPipe Diameter
C.I.P.D.I.P.P.V.C.C.M.P.Unknown Total
(in)
1
(ft)(ft)(ft)(ft)(ft)(ft)(miles)
0 182
0
1,009
146
0
0
0
0
1,192 0.2
1.25
2
0
0
146
1,579
0.03
0.38872660426
3 0 174 594 0 0 768 0.1
4 5,928
64,482
82,156
15,286
31,728
0
22,174
98,096
325,392
38,486
169,851
283
8,562
10,753
15,155
2,274
12,737
0
0 2,262
15,332
25,885
1,110
16,193
0
38,926
188,776
448,588
57,155
230,509
283
7.4
6 113
0
35.8
85.0
10.8
43.7
0.1
8
10
12
15
16
24
30
Total
0
0
0
0 44,340
48,658
0
3 0 0 44,343
54,876
1,836
8.4
0 341 0 5,877
0
10.4
0.31,836 0 0
202.5
5/11/2021
201,416 748,523 51,840 113 67,085 1,068,976
Agenda Item 9.2
Page 558 of 768
Table 4. Pipe Roughness Coefficients
Water System Master Plan
City of Gilroy
Age (years)Pipe Material 0 10 20 30 40 50
Cast Iron
Ductile Iron
Plastic (PVC)
120 110 100
120
140
90 85 80
130
145
125
145
115
140
110
135
105
135
5/12/2021
Note:
1. At an age of zero, the roughness coefficients are commonly used values for new pipes. Roughness coefficients decrease with age at a rate that depends on
pipe material. For planning purposes, the hydraulic analysis assumed an average pipe age of 15 20 years for both existing and future scenarios.
2. Pipes with an unknown material or age were assigned a roughness coefficient of 111 or 121.
Agenda Item 9.2
Page 559 of 768
Table 4. Existing Storage Reservoirs
Water System Master Plan
City of Gilroy
Hydraulic Information
OverflowPressure
Zone
Tank
Number
Location Bottom
Elevation Height
(ft)
SHGL Diameter
(ft)
Volume
(MG)
Height
(ft)(ft)(ft)
Zone 1 1A
1B
Welburn Ave. at Rancho Real
Santa Teresa Blvd. at Miller Ave.
Santa Teresa Blvd. at Miller Ave.
Mantelli Dr. at Periwinkle Dr.
Mantelli Dr. at Periwinkle Dr.
South end of Hoylake Court
South end of Hoylake Court
Walton Heath Court
342.5 34 32
27
27
24
24
24
24
24
24
24
374 128 3.00
347.5
347.5
510.5
510.5
510.5
510.5
510.5
621.0
621.0
29
29
25
25
25
25
25
25
25
374
374
112 2.00
5.30
0.41
0.41
0.71
0.71
0.71
0.41
0.41
1G 165 x 165
Zone 2N
Zone 2S
2C-1
2C-2
2E-1
2E-2
2F-1
3D-1
3D-2
533.5
533.5
533.5
533.5
533.5
644
54
54
70
70
70
54
54
Zone 3 South end of Periwinkle Drive
South end of Periwinkle Drive 644
Total Storage 14.1
1/26/2021
Note:
1. Source: City of Gilroy 2004 Water System Master Plan, Table 4.2
Agenda Item 9.2
Page 560 of 768
Table 4. Existing Booster Pumping Stations
Water System Master Plan
City of Gilroy
Operational Controls
(Reservoir Levels)
Source
Elevation Pressure
Zone
Destination
Pressure
Zone
Pump Station Pump Station Individual
Classification Horsepower
Operational
Capacity2 Pump Head2Pump
NumberNameDescriptionCapacityHorsepower Pump Test Date Operational On
(ft)
20.0
Off
(ft)Reservoir(ft)(gpm) (mgd)(hp)(hp)(gpm)
641
(gpm)
162
Priority
Booster Station 1 Rancho Hills Court 280
540
490
250
260
340
1 (374')
2 (533.5')
2 (533.5')
1 (374')
1 (374')
1 (374')
2 (533.5')
3 (644')
1,710
870
2.5
1.3
1.3
2.5
2.5
2.5
138.6 7/23/2020
7/23/2020
7/23/2020
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Lead
Lag
45.1
45.2
48.3
15
2C-1
2C-1
2C-1
3D-1
3D-1
3D-1
3D-1
3D-1
3D-1
2C-1
2C-1
2C-1
2E-1
2E-1
2E-1
2E-2
2E-2
2E-2
Lead 22.5
585
655
290
290
290
290
290
290
438
440
443
622
605
611
410
536
524
176
166
Lag 1
Lag 2
Lead
Lag 1
Lag 2
Lead
Lag 1
Lag 2
Lead
Lag 1
Lag 2
Lead
Lag 1
Lag 2
Lead
Lag 1
Lag 2
18.0
18.0
20.0
18.0
18.0
20.0
18.0
18.0
20.0
18.0
18.0
20.0
18.0
18.0
20.0
18.0
18.0
20.0
20.0
22.5
20.0
20.0
22.5
20.0
20.0
22.5
20.0
20.0
22.5
20.0
20.0
22.5
20.0
20.0
Standby
LeadBooster Station 2
Booster Station 3
Booster Station 4
Booster Station 5
Booster Station 6
Mantelli Dr. at Periwinkle
Country Club Dr.
45
45
Lag 15
Standby
Lead
15
3 (644')870 15
Lag 15
Standby
Lead
15
Rancho Hills Dr.2 (533.5')
2 (533.5')
2 (533.5')
1,710
1,710
1,710
150
150
150
7/23/2020
7/23/2020
7/23/2020
7/23/2020
7/23/2020
7/23/2020
7/23/2020
7/23/2020
7/23/2020
48.1
46.9
42.3
41.9
40.8
41
203
203
203
180
178
178
199
194
171
Lag
Standby
LeadClub Dr.
Lag
Standby
LeadMiller Ave. at Santa Teresa Blvd 30.6
36.4
35.8
Lag
Standby
1/26/2021
Notes:
1. Unless noted otherwise, data extracted from City of Gilroy 2004 Water System Master Plan, Table 4.3
2. Operational capacity for booster stations 1, 4, 5, 6 extracted from 2020 Pump efficiency tests, received from City staff August 20, 2020.
3. Booster station information based on location provided in updated City of Gilroy Water System GIS, provided August 20, 2020.
Agenda Item 9.2
Page 561 of 768
4.7 PRESSURE REDUCING VALVES
Some pressure zones are served from higher pressure zones through pressure reducing valves
(PRVs), which are summarized on Table 4.6. PRVs constructed at pressure zone intersections,
allow the conveyance of water from higher pressure zones to the lower pressure zones in the City.
Additionally, some PRVs provide a source of emergency supply to reduce service pressures in the
case of booster station failure or other operational issues. The City currently operates 6 pressure
reducing valves throughout its water system.
March 2023 4-11 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 562 of 768
Table 4.6 Existing Pressure Reducing Valves
Water System Master Plan
City of Gilroy
Pressure Zone Downstream
SetpointSizeLocationPRV ID
Upstream Downstream(in)(psi)
Rancho Hills Court Valve_BS1
Valve_BS2
Valve_BS3
Valve_BS4
10"2N
3
1
2N
2N
1
15.0
Mantelli Dr. at Periwinkle
Country Club Dr.
8"5.0
10"
12"
3 10.0
20.0Rancho Hills Dr.2N
Club Dr.Valve_BS5
Valve_BS6
8"2S
2S
1
1
20.0
Miller Ave. at Santa Teresa Blvd 16"1.0
1/26/2021
Agenda Item 9.2
Page 563 of 768
2023City of Gilroy
CHAPTER 5 – WATER DEMANDS AND SUPPLY CHARACTERISTICS
This chapter summarizes exiting domestic water demands and projects the future domestic water
demands.
5.1 EXISTING DOMESTIC WATER DEMANDS
The existing water demands used for this master plan were based on the City’s 2019 PWSS
consumption records, which included the monthly demands for each land use category, as well as
total annual production. These existing water demands in this analysis are adjusted to match the
annual production records and account for system losses.
The existing demand distribution, by pressure zone, was obtained from the water billing records.
Using GIS, each customer account was geocoded to its physical location within its existing
pressure zone. The accounts were then stored by pressure zone and total demand in each zone
was calculated.
The City’s existing average day domestic water demand, as extracted from water billing records,
were lower than total demand listed in the annual production records due to system losses that
occurred between groundwater wells and customer service connections. The total domestic water
demand was increased proportionally to 4,768 gpm to reflect the total 2019 production and
account for transmission main losses. The existing domestic water demands, for each pressure
zone for 2019 SCADA and designed criteria peaking factors, are summarized on Table 5.1.
5.2 FUTURE DOMESTIC WATER DEMANDS
Future demands were projected using the unit factors for residential and non-residential land uses
and included the anticipated developments within the City’s service area. Table 5.2 organizes the
future land use categories and their corresponding domestic water demands. It should be noted
that the existing domestic water demands in Table 5.2 were calculated using the recommended
water unit factors, which account for future water conservation practices, and are intended to
represent the water use of existing users at buildout of the master plan horizon (2040). The
average day domestic water demands from existing and future developments is calculated at 11.2
MGD.
These demands were used in sizing the future facilities, including distribution mains, storage
reservoirs, and booster stations. Demands were also used for allocating and reserving capacities
in the existing or proposed facilities.
March 2023 5-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 564 of 768
Table 5.1 Existing Water Demands
Water System Master Plan
City of Gilroy
Existing Water Demands
SCADA Based Peaking Factors Design Criteria Peaking FactorsAverage DayPressure Zone 1Demand
Maximum Day Peak Hour Maximum Day Peak Hour
2 3 4 5DemandDemandDemandDemand
(gpm)
4,200
(gpm)
6,702
(gpm)(gpm)
8,400
(gpm)
Zone 1
Zone 2N
Zone 2S
Zone 3
Total
10,215 12,600
170
307
271
490
413
747
339
615
509
922
91 145 222 182 273
4,768 7,609 11,597 9,536 14,304
5/12/2021
Note:
1. Total demand was adjusted to reflect the total production for 2019, from Groundwater well production records. The distribution is based on 2019 water billing reco
2. Maximum Day Demand = 1.6 x Average Day Demand, as based on 2019 SCADA.
3. Peak Hour Demand = 2.4 x Average Day Demand, as based on 2019 SCADA .
4. Maximum Day Demand = 2.0 x Average Day Demand
5. Peak Hour Demand = 3.0 x Average Day Demand
Agenda Item 9.2
Page 565 of 768
Table 5.2 Buildout Water Demands
Water System Master Plan
City of Gilroy
Total Water Demand Buildout of Service AreaWater Unit
Land Use Classification Factor Average Day
DemandExisting Unchanged Redeveloped Area New Development Total Area
(gpd/acre)(acres)(acres)(acres)(acres)(gpd)
Residential
Hillside Residential
Low Density Residential
Medium Density Residential
High Density Residential
1,270
2,000
442
1,583
58
112
122
177
18
353
89
907
1,794
240
1,151,593
3,587,897
788,7433,280 6
4,260 67 18 104 442,583
Subtotal - Residential 2,151 429 466 3,045 5,970,816
Non-Residential
Office and Commercial 1
Industrial 2
1,100
990
465 281
213
153
38
100
643
129
358
7
846
1,149
841
395
27
930,592
1,137,375
151,310
450,832
31,122
293
Public Facility / Institution
Neighborhood District
City Gateway District
180 559
1,140
1,140
Varies
1,100
Varies
Varies
990
0
0 20
Downtown Specific Plan Area 3
Mixed Use Corridor High
0 57 32 89 210,626
35,976025733
Hecker Pass Special Use District 4
Glen Loma Ranch 4
0 328
103
43
88 416
341
83
528,763
577,791
82,587
0
0
237
40Industrial Park
Employment Center 1,100 0 279
1,541
251
1,893
530
4,750
583,081
4,720,055Subtotal - Non-Residential 1,317
Other
Park and Recreation Facility 410
0
995
0
0
0
0
154
0
1,149
0
471,009
Vacant 0
0Open Space
Rural County
0 253 1,045 1,298
0 0 28 3 30 0
Subtotal - Other 1,247 28 1,202 2,477 471,009
Total
4,714 1,997 3,561 10,272 11,161,880
4/20/2022
Notes:
1. Office and Commercial accounts for Visitor Serving Commercial and General Services Commercial Land Use types.
2. Industrial accounts for General Industrial and Campus Industrial Land Use types.
3. Downtown Specific Plan Water Unit Factors vary based on land use.
4. Glen Loma and Hecker Pass water demand estimated separately, based on itemized land use plan and associated land use factors.
Agenda Item 9.2
Page 566 of 768
5.3 MAXIMUM DAY AND PEAK HOUR DEMANDS
The maximum day and peak hour demands for the existing and future demands were calculated
using the average day demands and City peaking factor criteria. The maximum day to average
day ratio of 2.0, and peak hour to average day ratio of 3.0, were applied to the average day
demands to obtain estimates of the higher demand conditions. The maximum day and peak hour
demand estimates for the buildout of the Urban Growth Boundary are 22.3 mgd and 33.5 mgd,
respectively.
5.4 DIURNAL DEMAND PATTERNS
Water demands vary with the time of day and by account type according to the land use
designation. These fluctuations were accounted for in the modeling effort and evaluation of the
water distribution system. The diurnal demand patterns are a collection of unit factors that are
applied to the demand, and which reflect the variable hourly fluctuation. Due to the sufficient
SCADA data, the City was able to generate diurnal demand curve. Figure 5.1 shows the city’s
diurnal, developed based on SCADA data observed June 2020 through August 2020.
March 2023 5-4 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 567 of 768
EPS 2020 Demand Diurnal
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
LEGEND
Notes:
Figure 5.1
Diurnal Curve
Water System Master Plan
City of Gilroy
Water Demand
1. Diurnal curve was developed based on SCADA data observed June 2020 through August
2020.
May 12, 2021
Agenda Item 9.2
Page 568 of 768
2023City of Gilroy
CHAPTER 6 – HYDRAULIC MODEL DEVELOPMENT
This chapter describes the development and calibration of the City’s domestic water distribution
system hydraulic model. The hydraulic model was used to evaluate the capacity adequacy of the
existing system and to plan its expansion to service anticipated future growth.
6.1 OVERVIEW
Hydraulic network analysis has become an effectively powerful tool in many aspects of water
distribution planning, design, operation, management, emergency response planning, system
reliability analysis, fire flow analysis, and water quality evaluations. The City’s hydraulic model
was used to evaluate the capacity adequacy of the existing system and to plan its expansion to
service anticipated future growth.
6.2 MODEL SELECTION
The City’s hydraulic model combines information on the physical characteristics of the water
system (pipelines, groundwater wells, and storage reservoirs) and operational characteristics
(how they operate). The hydraulic model then performs calculations and solves series of
equations to simulate flows in pipes and calculate pressures at nodes or junctions.
There are several network analysis software products that are released by different
manufacturers, which can equally perform the hydraulic analysis satisfactorily. The selection of a
particular software depends on user preferences, the distribution system’s unique requirements,
and the costs for purchasing and maintaining the software.
The City’s previous hydraulic model was developed using the Environmental Protection Agency’s
EPANET software, which allows the use of a single modeling scenario, and basic simulation
options for steady-state and extended period simulations. As part of this master plan, the
hydraulic model has been updated for consistency the City’s current GIS database and
redeveloped using the InfoWater hydraulic modeling software, available from Innovyze Inc. This
software is directly integrated with ESRI’s ArcGIS (GIS) environment, providing a useful modeling
tool linked to the City’s newly developed GIS database.
6.3 HYDRAULIC MODEL DEVELOPMENT
Developing the hydraulic model included skeletonization, digitizing and quality control, developing
pipe and node databases, and water demand allocation, as described in detail below.
March 2023 6-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 569 of 768
6.3.1 Skeletonization
Skeletonizing the model refers to the process where pipes not essential to the hydraulic analysis
of the system are stripped from the model. Skeletonizing the model is useful in creating a system
that accurately reflects the hydraulics of the pipes within the system, while reducing complexities
of large systems, which will reduce the time of analysis while maintaining accuracy, but will also
comply with limitations imposed by the computer program.
In the City of Gilroy’s case, skeletonizing was kept to a minimum due to the availability of the
existing model, which has been maintained and updated since the completion of the 2004 Water
System Master Plan.
6.3.2 Pipes and Nodes
Computer modeling requires the compilation of large numerical databases that enable data input
into the model. Detailed physical aspects, such as pipe size, pipe elevation, and pipe lengths,
contribute to the accuracy of the model.
Pipes and nodes represent the physical aspect of the system within the model. A node is a
computer representation of a place where demand may be allocated into the hydraulic system,
while a pipe represents the distribution and transmission aspect of the water demand. In addition,
reservoir dimensions and capacities, and groundwater well capacity and design head, were also
included in the hydraulic model.
6.3.3 Digitizing and Quality Control
The City’s existing domestic water distribution system was digitized in GIS using several sources
of data and various levels of quality control. The data sources included the City’s existing system
as maintained by staff in GIS, as well as the previously developed hydraulic model and
subsequent updates.
After reviewing the available data sources, the hydraulic model was updated and verified by City
staff. Resolving discrepancies in data sources was accomplished by graphically identifying each
discrepancy and submitting it to engineering and public works staff for review and comments. City
comments were incorporated in the verified model.
6.3.4 Demand Allocation
Demand allocation consists of assigning water demand values to the appropriate nodes in the
model. The goal is to distribute the demands throughout the model to best represent actual
system response.
Allocating demands to nodes within the hydraulic model required multiple steps, incorporating the
efficiency and capabilities of GIS and hydraulic modeling software. Existing land use water
demand factors were used in conjunction with the existing land use map. Each demand factor was
March 2023 6-2 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 570 of 768
applied to the appropriate land use and then multiplied by the acreage. In the absence of
complete water billing records, this methodology was considered the best approach to allocate
existing water demands.
Domestic water demands from each anticipated future development, as presented in a previous
chapter, were also allocated to the model for the purpose of sizing the required future facilities.
The demands from the greater Planning Area were allocated based on proposed land use and the
land use acreages. Since many of the areas were very large in size, demands were allocated
evenly to the demand nodes within each area. Infill areas, redevelopment areas, and vacant lands
were also included in the future demand allocation.
6.4 MODEL CALIBRATION
Calibration is intended to instill a level of confidence in the pressures and flows that are simulated.
Calibration generally consists of comparing model predictions to field measured results and
making necessary adjustments.
6.4.1 Calibration Plan and SCADA
In order to calibrate the hydraulic model, pressure SCADA data was collected for points
throughout the water distribution system, as well as water level data for the City’s storage
reservoirs. City staff provide 10-minute pressure and flow data for each groundwater well and
booster station as well as 10-minute water level data for the City’s storage reservoirs, for the
period between June and August 2020.
City staff provided hourly pressure and flow data for each well, as well as the pressure at the base
of the water tank, for the period between June and August 2020. This data was further
consolidated and compared with daily demand data to best calibrate to average day conditions.
The calibration results are shown in Figure 6.1 and Figure 6.2.
6.4.2 EPS Calibration
Calibration can be performed for steady state conditions or for extended period simulations (EPS).
In steady state calibration, the model is compared to field monitoring results consisting of a single
value, such as a single hydrant test. EPS calibration consists of comparing model predictions to
diurnal operational changes in the water system.
The calibration process was iterative and resulted with satisfactory comparisons between the field
measurements and the hydraulic model predictions at each well site and the water tank. The
calibration results were graphically summarized for each site and included in Appendix A.
Representative extracts from Appendix A are shown on Figure 6.1 and Figure 6.2 for calibration
points at the water tank 1A, 1B, 1G-1, 1G-2 and well 3, 4, respectively.
March 2023 6-3 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 571 of 768
6.4.3 Use of the Calibrated Model
The calibrated hydraulic model was used as an established benchmark in the capacity evaluation
of the existing water distribution system. The model was also used to identify improvements
necessary for mitigating existing system deficiencies and for accommodating future growth. This
valuable investment will continue to prove its value to the City as future planning issues or other
operational conditions surface. It is recommended that the model be maintained and updated with
recent construction to preserve its integrity.
March 2023 6-4 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 572 of 768
Avg. % Difference = 4%Avg. % Difference = 3%Tank 1A Tank 1B
Pressure Zone 1 Pressure Zone 1
25
20
15
10
5
20
15
10
5
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
Avg. % Difference = 11%Avg. % Difference = 3%Tank 1G 1
Pressure Zone 1
Tank 1G 2
Pressure Zone 1
25
20
15
10
5
20
15
10
5
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure 6.1
Storage Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 573 of 768
Avg. % Difference = 0%Avg. % Difference = 3%Well 3 Flow
Pressure Zone 1
Well 3 Outlet Pressure
Pressure Zone 13,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12
Time (hours)
18 24
Time (hours)
Avg. % Difference = 1%Avg. % Difference = 3%Well 4 Flow Well 4 Outlet Pressure
Pressure Zone 1 Pressure Zone 1
3,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure 6.2
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 574 of 768
2023City of Gilroy
CHAPTER 7 – EVALUATION AND PROPOSED IMPROVEMENTS
This chapter presents a summary of the domestic water system evaluation and identifies
improvements needed to mitigate existing deficiencies, as well as improvements needed to
expand the system and service growth.
7.1 OVERVIEW
The calibrated hydraulic model was used for evaluating the distribution system for capacity
deficiencies during peak hour demand and during maximum day demands in conjunction with fire
flows. Since the hydraulic model was calibrated for extended period simulations, the analysis
duration was established at 24 hours for analysis.
The criteria used for evaluating the capacity adequacy of the domestic water distribution system
facilities (transmission mains, storage reservoirs, and booster stations) was discussed and
summarized in the System Performance and Design Criteria chapter.
7.2 LOW PRESSURE ANALYSIS
The hydraulic model was also used to determine if the existing domestic water distribution system
meets the City’s System Performance and Design Criteria for the maximum day and peak hour
pressures, as discussed in a previous chapter. During maximum day demands the minimum
pressure requirement is 40 psi, while during the peak hour demand, the minimum pressure
requirement is 35 psi. The hydraulic analysis indicated the City’s existing system performed
reasonably well during under maximum day (Figure 7.1) and peak hour (Figure 7.2) operating
conditions.
7.3 HIGH PRESSURE ANALYSIS
The hydraulic model was also used to identify areas that experience high pressure under
maximum day demand conditions, as shown on Figure 7.3. Areas of high pressure may be more
susceptible to pipeline breaks and ruptures. The City’s maximum desired pressure criterion is 80
psi. The hydraulic analysis indicated the City’s system observes some periods of high pressures,
primarily in the northwest, southwest and southeast sections of the City.
7.4 FIRE FLOW ANALYSIS
The fire flow analysis consisted of using the maximum day demand in the hydraulic model and
applying hypothetical fire flows. The magnitude and duration of each fire flow was based on the
governing land use type within proximity to the fire location. The criterion for fire flows was also
summarized in the System Performance and Design Criteria chapter.
March 2023 7-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 575 of 768
Legend
Node Pressures < 40 psi
Existing System
Tanks
Wells
Booster Pumps
Existing Pipes by Diameter
4" - 6"
8
101
8"
10" - 30"
Roads
Railroads
City Limits12
Urban Growth Boundary
Rivers & Creeks
Waterbodies152241522424
8
152
Figure 7.1
Minimum System Pressures
(Maximum Day Demand)
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: April 28, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig7-1A_MinPress_MaxDay_042821.mxd
Agenda Item 9.2
Page 576 of 768
Legend
Node Pressures < 35 psi
Existing System
Tanks
Wells
Booster Pumps
Existing Pipes by Diameter
4" - 6"
8
101
8"
10" - 30"
Roads
Railroads
City Limits12
Urban Growth Boundary
Rivers & Creeks
Waterbodies152241522424
8
152
Figure 7.
Minimum System Pressures
(Peak Hour)
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: April 28, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig7-1B_MinPress_Hour_042821.mxd
Agenda Item 9.2
Page 577 of 768
Legend
Node Pressures > 80 psi
Existing System
Tanks
Wells
Booster Pumps
Existing Pipes by Diameter
4" - 6"
8
101
8"
10" - 30"
Roads
Railroads
City Limits12
Urban Growth Boundary
Rivers & Creeks
Waterbodies152241522424
8
152
Figure 7.
Maximum System Pressures
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: April 23, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig7-2_MaxPress_042321.mxd
Agenda Item 9.2
Page 578 of 768
The hydraulic model indicates that the City’s existing distribution system performed adequately
during the fire flow analysis. The required fire flow, based on different types of land uses, are
presented on Figure 7.4. Areas where the City’s water system did not meet the fire flow criteria
are documented on Figure 7.5. The available fire flow at the City’s residual pressure criteria of 20
psi is shown on Figure 7.6.
7.5 WATER SUPPLY
The criteria for water supply should be capable of meeting maximum day demand, including a 2.6
million gallons per day (MGD) standby capacity.
The City’s existing water supply requirement for maximum day demands plus a 2.6 MGD standby
capacity is 16.3 MGD. The buildout water supply requirement for Planning Area demands is
projected at 25.0 MGD. Table 7.1 includes a supply analysis for the City through the buildout of
the Gilroy Planning Area.
It should be noted that the 2020 Urban Water Management Plan (UWMP) projected an average
daily supply requirement of 7.4 MGD for existing conditions and projected 21.8 MGD for future
conditions. This differs from the master plan average daily supply requirement of 6.9 MGD for
existing conditions and projected 11.2 MGD for 2040 General Plan buildout conditions. The
master plan demand projections have been reviewed and approved by City staff.
7.6 WATER SUPPLY REQUIREMENTS
The City’s existing domestic water supply capacity is identified in this section. Additionally, the
section identifies the additional supply capacity required to meet the supply requirement.
7.6.1 Existing Supply Requirements
Existing supply requirements were identified for the City and are summarized on Table 7.1. The
City’s existing water supply requirement is approximately 16.3 mgd, as based on existing land use
and recommended water demands. The existing available supply capacity is approximately 19.8
mgd, which results in a supply surplus of 3.5 mgd.
7.6.2 Future Supply Requirements
Future supply requirements were identified based on the buildout of the 2040 General Plan and
are summarized on Table 7.1. As shown on Table 7.1 the City’s existing firm supply capacity is
not sufficient to meet the City’s buildout supply requirement, and three (3) new wells are required
to be constructed. With the construction of three new wells (2.2 mgd capacity for each) in the City,
the City’s future firm supply capacity will meet the future supply requirement of 25 mgd under
buildout conditions. Figure 7.7 shows the projected population, required and available supply
capacity through year 2020 to year 2040, and identifies the time when the proposed groundwater
March 2023 7-5 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 579 of 768
Legend
Required Fire Flow
Industrial: 5,000 gpm for 3 Hours
Commercial: 2,500 gpm for
2 Hours
Residential: 1,500 gpm for
2 Hours
Existing System8
Tanks
Wells
101
Booster Pumps
Existing Pipes by Diameter
4" - 6"
8"
12
10" - 30"
Roads
Railroads
152 24 152 City Limits2424
Urban Growth Boundary
Rivers & Creeks
Waterbod
8
152
Figure 7.
Required Fire Flow
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: April 29, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig7-3_FFReq_042921.mxd
Agenda Item 9.2
Page 580 of 768
Legend
Residual Pressure < 20 psi
Residual Pressure = 0 psi
Existing System
Tanks
Wells
8 Booster Pumps
Existing Pipes by Diameter
4" - 6"
101
8"
10" - 30"
Roads
Railroads12
City Limits
Urban Growth Boundary
Rivers & Creeks
Waterbodies
152 24 1522424
8
152
Figure 7.
Fire Flow Analysis
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: July 7, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig7-4_FFAnalysis_070721.mxd
Agenda Item 9.2
Page 581 of 768
Legend
Available Fire Flow
Greater than 5,000 gpm
2,500 gpm - 5,000 gpm
1,500 gpm - 2,500 gpm
500 gpm - 1,500 gpm
Less than 500 gpm8
101 Existing System
Tanks
Wells
Booster Pumps
Existing Pipes by Diameter
4" - 6"12
8"
10" - 30"
Roads1522415224Railroads24
City Limits
8 Urban Growth Boundary
Rivers & Creeks
Waterbodies
152
Note:
It should be noted that available
fire flow values shown are based
on a residual pressure of 20 psi.
Figure 7.
Available Fire Flow
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: April 23, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig7-5_AvailFF_042321.mxd
Agenda Item 9.2
Page 582 of 768
Well Construction Schedule
100,000
90,000
80,000
70,000
60,000
50
45
40
35
30
25
20
15
10
5
88,633
82,274
76,372
70,893 Construct New Well
(2.2 mgd) by 204865,807 Construct New Well
(2.2 mgd) by 204161,086 Construct New Well
(2.2 mgd) by 203356,70450,000
40,000
30,000
20,000
10,000
0
Existing Supply Capacity = 19.8 MGD
0
2020 2025 2030 2035Year 2040 2045 2050
LEGEND Figure 7.7
Well Construction
Schedule
Water System Master Plan
City of Gilroy
Assumptions:Population
Required Supply Capacity
Available Supply Capacity
1. Water demand projections based on a demand factor of
126.35 gpcd.
2. Projected water demand based on Maximum Day
Demand + Standby Well Requirement (2.6 MGD).
April 22, 2022
Agenda Item 9.2
Page 583 of 768
Table 7.1 Supply Capacity Evaluation
Water System Master Plan
City of Gilroy
Well No.Rated Supply Capacity
Supply Capacity Criteria
Firm supply capacity to equal Maximum Day Demand +
Standby Well (2.6 mgd)
Groundwater Supply Capacity
No. 1
No. 2
No. 3
No. 4
No. 5
No. 6
No. 7
No. 8
No. 8A
1,200 gpm
1,100 gpm
2,300 gpm
1,200 gpm
1,600 gpm
1,500 gpm
1,700 gpm
2,200 gpm
240 gpm
1 700 gpmNo. 9
Supply vs. Demand Evaluation
Supply Balance Existing Buildout
Maximum Day Demand
(mgd)13.7
2.6
22.3
2.6Standby Well
(mgd)
Required Capacity
(mgd)16.3
19.8
3.5
24.9
19.8
-5.1
Available Supply Capacity
(mgd)
Capacity Surplus/Deficiency
(mgd)
Recommended New Wells
(at 2.2 mgd each 2)0 3.0
7/6/2021
Note:
1. Project is currently under way to construct Well No. 9.
2. Recommended new well capacity of 2.2 mgd is
consistent with the 2004 WSMP.
Agenda Item 9.2
Page 584 of 768
wells need to be constructed. The proposed groundwater well sites are shown graphically in
Figure 7.8 and described as follows:
GW-10: Construct a new 1,500 gpm groundwater well near the intersection of San Ysildro
Avenue and Las Animas Avenue (Anticipated Construction Year: 2033).
GW-11: Construct a new 1,500 gpm groundwater well near the intersection of Camino
Arroyo and Renz Lane (Anticipated Construction Year: 2041).
GW-12: Construct a new 1,500 gpm groundwater well near the intersection of Wren
Avenue and Vickery Lane (Anticipated Construction Year: 2048).
Akel recommends a feasibility study of each proposed site to confirm site-specific constraints such
as subsurface conditions, aquifer depth, water quality treatment requirements and overall
constructability.
7.7 WATER STORAGE REQUIREMENT
The City’s existing domestic water system storage capacity is identified in this section.
Additionally, this section identifies the existing and future storage requirements to meet the
storage capacity and compares it with the existing storage facilities in each zone and makes
recommendation for new storage facilities.
7.7.1 Existing Storage Requirements
Existing storage requirements were identified for each pressure zone and are summarized in
Table 7.2. The table lists the existing domestic water demands and identifies the operational,
emergency and fire storage for each pressure zone. The table also lists the total required storage
for existing domestic water demands at 8.8 MG.
7.7.2 Future Storage Requirements
Future storage requirements were identified based on the buildout of the 2040 General Plan and
summarized by pressure zone on Table 7.3. The table lists the future domestic water demands
and identifies the operational, emergency and fire storage for each pressure zones. The table also
lists the total required storage for future domestic water demands at 13.7 MG.
7.7.3 Recommended New Storage Facilities
The existing and future storage requirements, shown on Table 7.2 and Table 7.3, were compared
with existing City storage facilities in each pressure zone and requirement storage facility
improvements that were identified and listed on Table 7.4. The table lists existing storage facilities
for each pressure zone, identifies existing storage capacity deficiencies, and identifies future
storage capacity requirements to meet the needs from future growth.
March 2023 7-11 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 585 of 768
Legend
Recommended Improvements
Tanks
Wells
New Pipes
Pipe Replacements
Existing System
Tanks
8
101
GW-10GW-12 Wells
Booster Pumps
Existing Pipes by Diameter
4" - 6"
Booster
Station 4Tanks: 2C-1
2C-2 Booster
Station 3 & 23D-1
3D-2 Booster
Station 1 8"12 Well 5-2
Tank 1A 10" - 30"
3H-1 16 RoadsWell 7
Railroads15224152Well 2 Well 124 City Limits24Well 8
Well 8A
Urban Growth Boundary
Rivers & Creeks
Waterbodies
8
152
GW-11Well 3-2
Tanks: 2E-1
2E-2 (Planned Well)
Booster
Station 5
Well 4
Well 6
Booster
Station 6
Tanks: 1B
2F-1
1G-1
1G-2 16
Figure 7.8
Recommended System
Improvements
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: September 14, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig7-8_RecImp_091421.mxd
Agenda Item 9.2
Page 586 of 768
Table 7.2 Existing Storage Requirements
Water System Master Plan
City of Gilroy
1 Existing Water Storage RequirementsExisting Water Demands
Pressure Zone Average Day
Demand
Maximum Day Fire
Protection 3
Total, By
Pressure ZoneOperationalEmergencyDemand 2
(MGD)(MGD)(MG)(MG)(MG)(MG)
Zone 1
Zone 2N
Zone 2S
6.05 12.10 3.02 3.02 0.90 6.95
0.24
0.44
0.49
0.88
0.12
0.22
0.24
0.44
0.18
0.30
0.55
0.96
Zone 3 0.13 0.26 0.07 0.13 0.18 0.38
Total 6.87 13.73 3.43 3.84 1.56 8.83
5/11/2021
Notes:
1. Total demands reflect the average day production and escalated using the peaking factor. The distribution is based on 2019 water billing records.
2. Maximum Day Demand = 2.0 x Average Day Demand
3. Fire Protection requirement represents largest fire requirement for each zone, based on existing land use types.
Agenda Item 9.2
Page 587 of 768
Table 7.3 Buildout Storage
RequirementsWater System Master Plan
City of Gilroy
1 Buildout Water Storage
Requirements
Buildout Water Demands
Pressure Zone Average Day
Demand
Maximum Day Fire
Protection 3
Total, By
Pressure ZoneOperationalEmergencyDemand 2
(MGD)(MGD)(MG)(MG)(MG)(MG)
Zone 1
Zone 2N
Zone 2S
9.16 18.31 4.58 4.58 0.90 10.06
0.28
1.23
0.56
2.45
0.14
0.61
0.28
1.23
0.18
0.30
0.60
2.14
Zone 3 0.50 1.00 0.25 0.50 0.18 0.93
Total 11.16 22.32 5.58 6.58 1.56 13.72
5/17/2022
Notes:
1. Buildout water demands include existing and future demands.
2. Maximum Day Demand = 2.0 x Average Day Demand
3. Fire Protection requirement represents largest fire requirement for each zone, based on existing land use types.
Agenda Item 9.2
Page 588 of 768
Table 7.4 Storage Capacity Evaluation by Pressure Zone
Water System Master Plan
City of Gilroy
Proposed New Storage
Reservoirs
Existing Water StorageExisting Water Storage
Requirements Existing Storage Reservoirs Buildout Water Storage
Requirements
Buildout Water Storage
RequirementsRequirements
Pressure Zone
(MGD)(MGD)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MGD)(MGD)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)(MG)
Zone 1
Zone 2N
Zone 2S
Zone 3
Total
6.0 12.1 6.0
0.4
0.7
0.2
7.3
0.9 6.9
0.5
1.0
0.4
8.8
3.0 2.0 5.3 10.3 3.4 9.2 18.3 9.2 0.9 10.1 0.0 10.3 0.24
0.2
0.4
0.1
6.9
0.5
0.9
0.2
0.3
0.2
1.6
0.4 0.4 0.8
2.1
0.3
1.2
0.4
5.2
0.3
1.2
0.6
2.4
0.4
1.8
0.2
0.3
0.2
0.6
2.1
0.9
0.0
0.0
0.8
2.1
0.9
0.22
0.00
0.00
0.7 0.7 0.7
0.3 0.4 0.4 0.8 0.5 1.0 0.7 0.1 0.1
13.7 14.1 11.2 22.3 12.2 1.6 13.7 0.10 14.17 0.46
5/13/2021
Agenda Item 9.2
Page 589 of 768
The results of the storage analysis indicate that the existing storage volume is sufficient under
existing conditions but is unable to meet the requirements for both existing and future customers
at the buildout of the General Plan. Therefore, a new storage reservoir is recommended
specifically in Zone 3 to mitigate the storage deficiency.
The proposed storage reservoir is summarized on Table 7.4 and graphically shown on Figure
7.8. This reservoir is described as follows, with a preliminary capacity of 0.1 MG:
R 3H-1: Construct a new 0.1 MG storage reservoir at existing Zone 3 Tank site,
located on Periwinkle Drive, to provide additional storage for future demand.
It should be noted that a minimum storage capacity of 0.1 MG was required in pressure zone 3 to
meet the buildout requirements. Potential for additional capacity should be investigated during
subsequent design phases to provide resiliency, if feasible.
7.8 PUMP STATION CAPACITY ANALYSIS
The City’s existing station capacity is identified in this section. Additionally, this section identified
the existing and future pump station capacity requirements and compares it with the existing
pump station facilities in each zone and makes recommendations for new pump station facilities.
7.8.1 Existing Pump Station Capacity Requirements
Existing pump station capacities and requirements established from the City criteria are
summarized on Table 7.5. This table indicates the City’s existing pump stations have adequate
capacity to meet existing requirements.
7.8.2 Future Pump Station Capacity Requirements
Existing pump station capacities and future requirements established from the City criteria are
summarized on Table 7.6. This table indicates the City’s existing pump stations have sufficient
capacity to meet projected water demands under buildout conditions.
7.9 PIPELINE IMPROVEMENTS
The buildout of the 2040 General Plan includes development outside of the extents of the existing
domestic water distribution system. Distribution pipelines are recommended to serve future growth
as well as increase the hydraulic reliability of the domestic water distribution system. Each
pipeline improvement is assigned a uniquely coded identifier, which is intended to aid in defining
the location of the improvement for mapping purposes. These identifiers reflect the pressure zone,
improvement type, and sequence in the improvement schedule. The pipeline improvements are
summarized on Table 7.7 and described in detail on the following pages.
March 2023 7-16 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 590 of 768
Table 7.5 Existing Pump Station Capacity Evaluation
Water System Master Plan
City of Gilroy
Pressure Zone Pump Station Capacity Analysis
2Required Existing CapacityTotal
Capacity
Firm
Capacity
Surplus/
Deficiency
Supply
Dependent
Zones
Pump Station Supply
Dependent
Zones
Destination
ZoneSource Zone 1
Destination Zone Total
(gpm)(gpm)(gpm)(gpm)(gpm)(gpm)
Pressure Zone 2N
Booster Station 1 1
1
2N
2N
3
3
1,881
1,321
3,202
1,226
878Booster Station 4
Total 2,104 339
615
182
182 522
615
182
1,582
Pressure Zone 2S
Booster Station 5 1
1
2S
2S
1,838
1,470
3,308
1,216
934Booster Station 6
Total 2,150 0 1,535
Pressure Zone 3
Booster Station 2 2N
2N
3
3
870
870
580
580Booster Station 3
Total 1,740 1,160 0 978
5/7/2021
Notes:
1. Firm capacity for each pressure zone is defined as the sum of the total capacity of each pump station pumping into the pressure zone, with each pump station operating without their largest unit.
2. Pump stations to supply MDD of destination zone and all other supply dependent zones.
Agenda Item 9.2
Page 591 of 768
Table 7.6 Buildout Pump Station Capacity
Evaluation
Water System Master PlanCity of Gilroy
Pressure Zone Pump Station Capacity Analysis
2Required Buildout Capacity
Supply
Dependent
Zones
Total
Capacity
Firm
Capacity 1
Surplus/
DeficiencyPump Station Supply
Dependent
Zones
Destination
ZoneSource Zone Destination Zone Total
(gpm)(gpm)(gpm)(gpm)(gpm)(gpm)
Pressure Zone 2N
Booster Station 1 1
1
2N
2N
3
3
1,881
1,321
3,202
1,226
878Booster Station 4
Total 2,104 389
1,705
692
692 1,081
1,705
692
1,023
Pressure Zone 2S
Booster Station 5 1
1
2S
2S
-
-
1,838
1,470
3,308
1,216
934Booster Station 6
Total 2,150 0 445
Pressure Zone 3
Booster Station 2 2N
2N
3
3
-
-
870
870
580
580Booster Station 3
Total 1,740 1,160 0 468
5/17/2022
Notes:
1. Firm capacity for each pressure zone is defined as the sum of the total capacity of each pump station pumping into the pressure zone, with each pump station operating without their largest unit.
2. Pump stations to supply MDD of destination zone and all other supply dependent zones.
Agenda Item 9.2
Page 592 of 768
7.9.1 Pipeline Improvements to Serve Future Growth
This section documents pipeline improvements within the Pressure Zone 1.
P1-1. Construct approximately 3,860 feet of a new 12-inch pipeline in Day Road from
Santa Teresa Boulevard to Monterey Highway.
P1-2. Construct approximately 5,780 feet of a new 12-inch pipeline in Monterey Highway /
Orsetti Road / Highway 101 from 620 feet north of Day Road to Cohansey Avenue.
P1-12. Construct approximately 1,620 feet of a new 16-inch pipeline in ROW from Camino
Arroyo to approximately 1,800 feet east of Luchessa Avenue.
P1-13. Construct approximately 4,540 feet of a new 16-inch pipeline in ROW / Cameron
Boulevard from approximately 200 feet southeast of Venture Way to Southside Drive.
P1-17. Construct approximately 1,810 feet of a new 16-inch pipeline in ROW from
Luchessa Avenue to approximately 1,800 feet east of Luchessa Avenue.
P1-18. Construct approximately 2,890 feet of a new 16-inch pipeline in ROW from
approximately 1,800 feet east of Luchessa Avenue to Southside Drive.
P1-20. Construct approximately 660 feet of a new 16-inch pipeline in Southside Drive from
Arizona Circle to approximately 660 feet of Arizona Circle.
P1-21. Construct approximately 3,010 feet of a new 16-inch pipeline in Southside Drive
from approximately 660 feet east of Arizona Circle to Camaron Boulevard.
P1-22. Construct approximately 280 feet of a new 16-inch pipeline in Santa Teresa
Boulevard from approximately 160 feet west of Thomas Road to approximately 110 feet
east of Thomas Road.
7.9.2 Pipeline Improvement to Increase Fire Flow Reliability
Improvements to mitigate specific fire flow deficiencies are discussed below with the
corresponding coded identifier, which is also consistent with the capital improvements chapter:
P1-9. Replace approximately 1,730 feet of 12-inch pipeline from Camino Arroyo to
Cameron Boulevard along Pacheco Pass Highway with 16-inch pipeline.
P1-10. Replace approximately 3,040 feet of 12-inch pipeline from Pacheco Pass Highway
to Venture Way along Camino Arroyo with 16-inch pipeline.
P1-11. Replace approximately 2,100 feet of 12-inch pipeline from Pacheco Pass Highway
to 200 feet southeast of Venture Way along Cameron Boulevard with 16-inch pipeline.
March 2023 7-19 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 593 of 768
P1-14. Replace approximately 6,480 feet of 12-inch pipeline from Thomas Road to Rossi
Lane along Luchessa Avenue with 16-inch pipeline.
P1-15. Replace approximately 3,060 feet of 12-inch pipeline from Luchessa Avenue to
Santa Teresa Road along Thomas Road with 16-inch pipeline.
P1-16. Replace approximately 2,730 feet of 12-inch pipeline from Luchessa Avenue to
Southside Drive along Rossi Lane with 16-inch pipeline.
P1-19. Replace approximately 4,630 feet of 12-inch pipeline from Highway 101 to Arizona
Circle along Garlic Farm Way / Southside Drive with 16-inch pipeline.
7.9.3 Pipeline Improvements to Mitigate Existing System Deficiencies
The hydraulic model was also used to identify areas that experience high headloss or high
velocity under maximum day demand conditions. The areas of existing pipeline deficiencies are
shown graphically on Figure 7.9. Areas of high velocity or high headloss may be more susceptible
to pipeline breaks and ruptures. The City’s maximum desired velocity criterion is 8 feet per second
and maximum desired headloss is 10 ft per thousand feet. Improvements to mitigate existing
pipeline deficiencies are discussed below with the corresponding coded identifier, which is also
consistent with the capital improvements chapter:
P1-3. Replace approximately 230 feet of 12-inch pipeline from Second Street to Loof
Avenue along Monterey Highway with 16-inch pipeline.
P1-4. Replace approximately 2,200 feet of 12-inch pipeline from Well 5-02 to Loof Avenue
along Murray Avenue with 16-inch pipeline.
P1-5. Replace approximately 70 feet of 12-inch pipeline from Well 7 to Loof Avenue along
Arroyo Circle with 16-inch pipeline.
P1-6. Replace approximately 230 feet of 8-inch pipeline from approximately 180 east of
Forest Street to Chestnut Street along Lewis Street with 10-inch pipeline.
P1-7. Replace approximately 320 feet of 10-inch pipeline from Well 3 to Sixth Street along
Forest Street with 12-inch pipeline.
P1-8. Replace approximately 300 feet of 12-inch pipeline from Well 8 to approximately 80
feet southeast of Gilman Road along Gilman Road / Camino Arroyo with 16-inch pipeline.
March 2023 7-20 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 594 of 768
Table 7.7 Schedule of Improvements
Water System Master Plan
City of Gilroy
Pipeline ImprovementsExisting
Improv. No. Improv. Type Pressure Zone
Pipeline Improvements
Alignment Limits Diameter New/Parallel/Diam.LengthReplace
(in)(in)(ft)
P1-1
P1-2
Future Growth
Future Growth
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
FF Reliability
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Day Rd From Santa Teresa Blvd to Monterey Hwy
From approx. 620' n/o Day Rd to Cohansey Ave
From 2nd St to Ioof Ave
-
-
New
New
12
12
16
16
16
10
12
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
3,860
5,780
230
Monterey Hwy / Orsetti
Rd / Hwy 101
P1-3 Monterey Hwy
Murray Ave
Arroyo Cir
Lewis St
12
12
12
8
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
New
P1-4 From Well 5-02 to Ioof Ave 2,200
70P1-5 From Well 7 to Ioof Ave
P1-6 From approx. 180' e/o Forest St to Chestnut St
From Well 3 to 6th St
230
P1-7 Forest St 10
12
12
12
12
-
320
Gilman Rd / Camino
ArroyoP1-8 From Well 8 to approx. 80' se/o Gilman Rd
From Camino Arroyo to Cameron Blvd
From Pacheco Pass Hwy to Venture Wy
300
P1-9 Pacheco Pass Hwy
Camino Arroyo
Cameron Blvd
ROW
1,730
3,040
2,100
1,620
4,540
6,480
3,060
2,730
1,810
2,890
4,630
660
P1-10
P1-11
P1-12
P1-13
P1-14
P1-15
P1-16
P1-17
P1-18
P1-19
P1-20
P1-21
P1-22
FF Reliability
From Pacheco Pass Hwy to approx. 200' se/o Venture
WyFF Reliability
From Camino Arroyo to approx. 1,800' e/o Luchessa
AveFuture Growth
Future Growth
FF Reliability
ROW / Cameron Blvd From approx. 200' se/o Venture Wy to Southside Dr -New
Luchessa Ave
Thomas Rd
Rossi Ln
ROW
From Thomas Rd to Rossi Ln 12
12
12
-
Replace
Replace
Replace
New
FF Reliability From Luchessa Ave to Santa Teresa Rd
From Luchessa Ave to Southside DrFF Reliability
From Luchessa Ave to approx. 1,800' e/o Luchessa
AveFuture Growth
Future Growth
FF Reliability
From approx. 1,800' e/o Luchessa Ave to Southside
DrROW -New
Garlic Farm Wy /
Southside Dr From Hwy 101 to Arizona Cir 12
-
Replace
NewFuture Growth
Future Growth
Future Growth
Southside Dr
Southside Dr
From Arizona Cir to approx. 660' e/o Arizona Cir
From approx. 660' e/o Arizona Cir to Camaron Blvd -New 3,010
280From approx. 160' w/o Thomas Rd to approx. 110'
e/o Thomas RdSanta Teresa Blvd -New
Proposed Storage CapacityStorage Reservoir Improvements (MG)
3H-1 Storage Capacity Zone 3 Construct an additional 0.2 MG storage reservoir at existing 3D site New 0.10
Proposed Pumping CapacityGroundwater Well Improvements (gpm)
GW-10
GW-11
GW-12
Supply Capacity
Supply Capacity
Supply Capacity
Zone 1
Zone 1
Zone 1
Construct new well near the intersection of San Ysidro Ave and Las Animas Ave
Construct new well near the intersection of Camino Arroyo and Renz Lane
Construct new well near the intersection of Wren Ave and Vickery Ln
New
New
New
1,500
1,500
1,500
7/1/2021
Agenda Item 9.2
Page 595 of 768
Legend
Existing Pipeline Deficiencies
Headloss is Greater than 10 ft/kft
Velocity is Greater than 8 fps
Existing System
Tanks
8 Wells
101 Booster Pumps
Existing Pipes by Diameter
4" - 6"
8"
10" - 30"
Roads12
Railroads
City Limits
Urban Growth Boundary
Rivers & Creeks
Waterbodies
152 24 1522424
8
152
Figure 7.
Existing Pipeline Deficiencies
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: April 23, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig7-6_ExistDeficiencies_042321.mxd
Agenda Item 9.2
Page 596 of 768
2023City of Gilroy
CHAPTER 8 – CAPITAL IMPROVEMENT
PROGRAMThis chapter provides a summary of the recommended domestic water system improvements to
mitigate existing capacity deficiencies and to accommodate anticipated future growth. The chapter
also presents the cost criteria and methodologies for developing the capital improvement
program. Finally, a capacity allocation analysis, usually used for cost sharing purposes, is also
included.
8.1 COST ESTIMATE ACCURACY
Cost estimates presented in the CIP were prepared for general master planning purposes and,
where relevant, for further project evaluation. Final costs of a project will depend on several
factors including the final project scope, costs of labor and material, and market conditions during
construction.
The Association for the Advancement of Cost Engineering (AACE International), formerly known
as the American Association of Cost Engineers has defined three classifications of assessing
project costs. These classifications are presented in order of increasing accuracy: Order of
Magnitude, Budget, and Definitive.
Order of Magnitude Estimate. This classification is also known as an “original estimate”,
“study estimate”, or “preliminary estimate”, and is generally intended for master plans and
studies.
This estimate is not supported with detailed engineering data about the specific project,
and its accuracy is dependent on historical data and cost indexes. It is generally expected
that this estimate would be accurate within -30 percent to +50 percent.
Budget Estimate. This classification is also known as an “official estimate” and generally
intended for predesign studies. This estimate is prepared to include flow sheets and
equipment layouts and details. It is generally expected that this estimate would be
accurate within -15 percent to +30 percent.
Definitive Estimate. This classification is also known as a “final estimate” and prepared
during the time of contract bidding. The data includes complete plot plans and elevations,
equipment data sheets, and complete specifications. It is generally expected that this
estimate would be accurate within -5 percent to + 15 percent.
Costs developed in this study should be considered “Order of Magnitude” and have an expected
accuracy range of -30 percent and +50 percent.
March 2023 8-1 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 597 of 768
8.2 COST ESTIMATE METHODOLOGY
Cost estimates presented in this chapter are opinions of probable construction and other relevant
costs developed from several sources including cost curves, Akel experience on other master
planning projects, and input from City staff on the development of public and private cost sharing.
Where appropriate, costs were escalated to reflect the more current Engineering News Records
(ENR) Construction Cost Index (CCI).
This section documents the unit costs used in developing the opinion of probable construction
costs, the Construction Cost Index, the land acquisition costs, and markups to account for
construction contingency and other project related costs.
8.2.1 Unit Costs
The unit cost estimates used in developing the Capital Improvement Program are summarized on
Table 8.1. Domestic water pipeline unit costs are based on length of pipes, in feet. Storage
reservoir unit costs are based on capacity, per million gallons (MG). Pump Station costs are
based on an equation that replaces the pump curve.
The unit costs are intended for developing the Order of Magnitude estimate and do not account
for site-specific conditions, labor and material costs during the time of construction, final project
scope, implementation schedule, detailed utility and topography surveys for reservoir sites,
investigation of alternative routings for pipes, and other various factors. The capital improvement
program included in this report accounts for construction and project-related contingencies as
described in this chapter.
8.2.2 Construction Cost Index
Costs estimated in this study are adjusted utilizing the Engineering News Record (ENR)
Construction Cost Index (CCI), which is widely used in the engineering and construction
industries.
The costs in this Water System Master Plan were benchmarked using a 20-City national average
ENR CCI of 13,176, reflecting a date of March 2023.
8.2.3 Construction Contingency Allowance
Knowledge about site-specific conditions for each proposed project is limited at the master
planning stage; therefore, construction contingencies were used. The estimated construction
costs in this master plan include a 30 percent contingency allowance to account for unforeseen
events and unknown field conditions, as well as market uncertainty and unpredictable inflation.
8.2.4 Project Related Costs
The capital improvement costs also account for project-related costs, comprising of engineering
design, project administration (developer and City staff), construction management and
March 2023 8-2 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 598 of 768
Table 8.1 Unit Costs
Water System Master Plan
City of Gilroy
Pipelines
Pipe Size Cost1,2
(in)($/lineal foot)
6 $153
8 $187
$211
$254
$304
$312
$336
$400
$500
$560
$705
10
12
16
18
20
24
30
36
42
Pump Stations
Estimated Pumping Station Project Cost = 2.1*10(0.7583*log(Q)+3.1951)
where Q is in gpm
Storage Reservoirs ($/gallon)1,3
≤1.0 MG
1.1 MG-3.0 MG
3.1 MG - 5.0 MG
> 5 MG
$1.33
$2.11
$3.22
$4.89
Groundwater Wells1,4,5
1,500 gpm Capacity $3,922,000
3/28/2023
Notes:
1. Construction costs estimated using March 2023 ENR CCI of 13,176.
2. Pipeline cossts include utilities, construction staging, traffic control, and
lighting and signing
3. Source: City of Gilroy 2004 Water System Master Plan
4. Source: City of Gilroy 2021-2025 Capital Improvement Program
5. One new 1,500 gpm well costs $3,626,645, per City of Gilroy 2021-2025
Capital Improvement Program. The cost accounts for Design, CEQA,
Construction, Con. Support, and Land Acquisition
Agenda Item 9.2
Page 599 of 768
inspection, and legal costs. The project related costs in this master plan were estimated by
applying an additional 30 percent to the estimated construction costs.
8.3 CAPITAL IMPROVEMENT PROGRAM
This section documents the capital improvement program, contingencies included in the costs,
and the allocation of costs to meet the requirements of AB1600.
8.3.1 Capital Improvements Costs
The Capital Improvement Program costs for the projects identified in this master plan for
mitigating existing system deficiencies and for serving anticipated future growth throughout the
City are summarized on Table 8.2.
Each improvement was assigned a unique coded identifier associated with the improvement type,
and is summarized graphically on Figure 8.1. The estimated construction costs include the
baseline costs plus 30 percent contingency allowance to account for unforeseen events and
unknown field conditions, as described in a previous section. Capital improvement costs include
the estimated construction costs plus 30 percent project-related costs (engineering design,
project administration, construction management and inspection, and legal costs).
8.3.2 Recommended Cost Allocation Analysis
Cost allocation analysis is needed to identify improvement funding sources, and to establish a
nexus between development impact fees and improvements needed to service growth. In
compliance with the provisions of Assembly Bill AB1600, the analysis differentiates between the
project needs of servicing existing users and for those required to service anticipated future
developments. The cost responsibility is based on model parameters for existing and future land
use, and may change depending on the nature of development. Table 8.2 lists each improvement,
and separates the cost by responsibility between existing and future users.
8.3.3 Construction Triggers
As a part of this master planning process, construction triggers were developed in an effort to plan
the expansion of the water system in an orderly manner. The construction triggers for multiple
improvements are based on mitigating an existing system deficiency, increasing hydraulic
reliability, or continuing improvements currently planned by the City. Other improvements replace
existing infrastructure that is not currently deficient, but will violate master plan criteria with future
development. The construction triggers quantify the amount of additional development that may
occur before the improvement becomes necessary.
8.4 SUGGESTED PIPELINE REPLACEMENT
BUDGETThe suggested pipeline replacement budget alternatives are shown on Figure 8.2, and includes
the estimated costs for replacing pipelines phased by 5-year fiscal periods through the year 2055.
March 2023 8-4 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 600 of 768
Legend
Recommended Improvements
Tanks
Wells
New Pipes
Pipe Replacements
Existing System
Tanks
8
101
GW-10 WellsGW-12
Booster Pumps
Existing Pipes by Diameter
4" - 6"
Booster
Station 4Tanks: 2C-1
2C-2 Booster
Station 3 & 23D-1
3D-2 Booster
Station 1 8"12 Well 5-2
Tank 1A 10" - 30"
3H-1 16P1-5 RoadsWell 7
Railroads1522416
Well 2 P1-315224 City Limits2410
P1-6
Well 8
Well 8AWell 1
16
P1-8 Urban Growth Boundary
Rivers & Creeks
Waterbodies
8 12P1-7 152
GW-11Well 3-2
Tanks: 2E-1
2E-2 (Planned Well)
Booster
Station 5
Well 4
Well 6
Booster
Station 6
Tanks: 1B
2F-1
1G-1
1G-2
16
P1-22
Figure 8.1
Capital Improvement
Program
Water System Master Plan
City of Gilroy101
GIS
0 0.25 0.5 1
Updated: September 14, 2021 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Water\200625-MP\GL_Fig8-1_CIP_091421.mxd
Agenda Item 9.2
Page 601 of 768
Table 8.2 Capital Improvement Program
Water System Master Plan
City of Gilroy
PRELIMINARY
Pipeline Information Infrastructure Costs Suggested Cost Allocation
Existing
Users
Cost SharingBaseline Constr. Estimated Const. Capital Improv.Pressure
Zone
Construction TriggerImprov. No.Improv. Type Alignment Limits Costs Costs1 Costs2New/Parallel/Existing Diameter Diameter Length Unit Cost Infr. Cost Future Users Existing Users Future UsersReplace
(in)(in)(ft)($)($)($)($)($)
Pipeline Improvements
P1-1
P1-2
Future Growth
Future Growth
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
FF Reliability
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Zone 1
Day Rd From Santa Teresa Blvd to Monterey Hwy
From approx. 620' n/o Day Rd to Cohansey Ave
From 2nd St to Ioof Ave
-
-
New
New
12
12
16
16
16
10
12
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
3,860
5,780
230
254
254
304
304
304
211
254
304
304
304
304
304
304
304
304
304
304
304
304
304
304
304
978,700
1,465,500
70,000
978,700
1,465,500
70,000
1,272,400
1,905,200
91,000
1,654,200
2,476,800
118,300
With Development
With Development
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
Existing Deficiency
As Funding is Available
As Funding is Available
As Funding is Available
With Development
With Development
As Funding is Available
As Funding is Available
As Funding is Available
With Development
With Development
As Funding is Available
With Development
With Development
With Development
0%
0%
100%
100%
0%
0
0
1,654,200
Monterey Hwy / Orsetti
Rd / Hwy 101 2,476,800
P1-3 Monterey Hwy
Murray Ave
Arroyo Cir
Lewis St
12
12
12
8
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
Replace
New
100%
100%
100%
100%
100%
100%
100%
100%
100%
0%
118,300
1,131,400
36,100
82,200
137,300
154,400
889,800
1,563,300
1,080,000
0
0
P1-4 From Well 5-02 to Ioof Ave 2,200
70
669,400
21,300
669,400
21,300
870,300
27,700
1,131,400
36,100
0%0
P1-5 From Well 7 to Ioof Ave 0%0
P1-6 From approx. 180' e/o Forest St to Chestnut St
From Well 3 to 6th St
230 48,600 48,600 63,200 82,200 0%0
P1-7 Forest St 10
12
12
12
12
-
320 81,200 81,200 105,600
118,700
684,400
1,202,500
830,700
640,800
1,795,700
2,563,100
1,210,300
1,079,800
716,000
1,143,100
1,831,400
261,200
1,190,600
110,800
137,300 0%0
Gilman Rd / Camino
ArroyoP1-8 From Well 8 to approx. 80' se/o Gilman Rd
From Camino Arroyo to Cameron Blvd
From Pacheco Pass Hwy to Venture Wy
300 91,300 91,300 154,400 0%0
P1-9 Pacheco Pass Hwy
Camino Arroyo
Cameron Blvd
ROW
1,730
3,040
2,100
1,620
4,540
6,480
3,060
2,730
1,810
2,890
4,630
660
526,400
925,000
639,000
492,900
1,381,300
1,971,600
931,000
830,600
550,700
879,300
1,408,700
200,900
915,800
85,200
526,400
925,000
639,000
492,900
1,381,300
1,971,600
931,000
830,600
550,700
879,300
1,408,700
200,900
915,800
85,200
889,800 0%0
P1-10
P1-11
P1-12
P1-13
P1-14
P1-15
P1-16
P1-17
P1-18
P1-19
P1-20
P1-21
P1-22
FF Reliability 1,563,300
1,080,000
833,100
0%0
0From Pacheco Pass Hwy to approx. 200' se/o Venture
WyFF Reliability 0%
Future Growth
Future Growth
FF Reliability
From Camino Arroyo to approx. 1,800' e/o Luchessa Ave 100%
100%
0%
833,100
2,334,500
0
ROW / Cameron Blvd From approx. 200' se/o Venture Wy to Southside Dr -New 2,334,500
3,332,100
1,573,400
1,403,800
930,800
0%0
Luchessa Ave
Thomas Rd
Rossi Ln
ROW
From Thomas Rd to Rossi Ln 12
12
12
-
Replace
Replace
Replace
New
100%
100%
100%
0%
3,332,100
1,573,400
1,403,800
0
FF Reliability From Luchessa Ave to Santa Teresa Rd
From Luchessa Ave to Southside Dr
0%0
FF Reliability 0%0
Future Growth
Future Growth
FF Reliability
From Luchessa Ave to approx. 1,800' e/o Luchessa Ave
From approx. 1,800' e/o Luchessa Ave to Southside Dr
From Hwy 101 to Arizona Cir
100%
100%
0%
930,800
1,486,100
0
ROW -New 1,486,100
2,380,900
339,600
0%0
Garlic Farm Wy /
Southside Dr 12
-
Replace
New
100%
0%
2,380,900
0Future Growth
Future Growth
Future Growth
Southside Dr
Southside Dr
From Arizona Cir to approx. 660' e/o Arizona Cir
From approx. 660' e/o Arizona Cir to Camaron Blvd
100%
100%
100%
339,600
1,547,800
144,100
-New 3,010
280
1,547,800
144,100
0%0
From approx. 160' w/o Thomas Rd to approx. 110' e/o
Thomas RdSanta Teresa Blvd -New 0%0
Subtotal - Pipeline Improvements 15,164,400 19,714,500 25,630,000 13,883,000 11,747,000
Proposed Storage CapacityStorage Reservoir Improvements (MG)
3H-1 Storage Capacity Zone 3 Construct an additional 0.1 MG storage reservoir at existing 3D site New 0.10 133,442 133,500 173,600 225,700 813 EDU 0%100%0 225,700
Subtotal - Storage Reservoir Improvements 133,500 173,600 225,700 0 225,700
Agenda Item 9.2
Page 602 of 768
Table 8.2 Capital Improvement Program
Water System Master Plan
City of Gilroy
PRELIMINARY
Pipeline Information Infrastructure Costs Suggested Cost Allocation
Existing
Users
Cost SharingBaseline Constr. Estimated Const. Capital Improv.Pressure
Zone
Construction TriggerImprov. No.Improv. Type Alignment Limits Costs Costs1 Costs2New/Parallel/Existing Diameter Diameter Length Unit Cost Infr. Cost Future Users Existing Users Future UsersReplace
(in)(in)(ft)($)($)($)($)($)
Proposed Pumping CapacityGroundwater Well Improvements (gpm)
GW-10
GW-11
GW-12
Supply Capacity
Supply Capacity
Supply Capacity
Zone 1
Zone 1
Zone 1
Construct new well near the intersection of San Ysidro Ave and Las Animas Ave
Construct new well near the intersection of Camino Arroyo and Renz Lane
Construct new well near the intersection of Wren Ave and Vickery Ln
New
New
New
1,500
1,500
1,500
-
-
-
-
-
-
-
-
-
3,922,000
3,922,000
3,922,000
9,500 EDU
15,550 EDU
21,600 EDU
0%
0%
0%
100%
100%
100%
0
0
0
3,922,000
3,922,000
3,922,000
Subtotal - Groundwater Well Improvements 0 0 11,766,000 0 11,766,000
Total Improvement Cost
Pipeline Improvements 15,164,400 19,714,500
173,600
0
25,630,000
225,700
13,883,000 11,747,000
225,700Storage Reservoirs
Groundwater Wells
133,500
0
0
011,766,000
37,621,700
11,766,000
Total Improvement Costs 13,883,000 23,738,70015,297,900 19,888,100
3/29/2023Notes:
1. Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.
2. Estimated construction costs plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal costs.
3. Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,176 for March 2023.
Agenda Item 9.2
Page 603 of 768
Costs are estimated based on the industry average goal of pipe R&R budgets, which is at 1.0%
per year for 100-year pipe replacement cycle. The estimated costs are starting from a base rate of
3.5 million dollars per year, with a pipe replacement rate of 1% of system length per year, which is
2.8 miles of new construction per year for the City. The future costs in 2055 are expected to be
approximately 4.2 million dollars per year.
March 2023 8-8 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 604 of 768
R&R Budget Alternatives
$5,000,000
$4,000,000
$3,000,000
$2,000,000
$1,000,000
$0
Industry Average
Pipe R&R Budgets
Industry Goal is at 1.0% per year for
100-year Pipe Replacement Cycle
2020 2025 2030 2035
Year
2040 2045 2050 2055
LEGEND
Industry Standard Replacement Schedule
Figure 8.
Pipeline Replacement
Budget Alternatives
Water System Master Plan
City of Gilroy
Assumptions:
1. System Growth: 2.8 miles of new construction per year (based
on historical construction)
2. All costs in 2021 dollars
3. Weighted average pipeline unit cost = $329/foot
4. 30% contengency added for estimated construction cost
5. 30% contengency added for capital improvement cost
August 6, 2021
Agenda Item 9.2
Page 605 of 768
City of Gilroy
APPENDICES
March 2023 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 606 of 768
City of Gilroy
APPENDIX A
Calibration Curves
March 2023 City of Gilroy
Water System Master Plan
Agenda Item 9.2
Page 607 of 768
Avg. % Difference = 4%Avg. % Difference = 3%Tank 1A Tank 1B
Pressure Zone 1 Pressure Zone 1
25
20
15
10
5
20
15
10
5
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
Avg. % Difference = 11%Avg. % Difference = 3%Tank 1G 1
Pressure Zone 1
Tank 1G 2
Pressure Zone 1
25
20
15
10
5
20
15
10
5
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure .1
Storage Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 608 of 768
Avg. % Difference = 5%Avg. % Difference = 6%Tank 2C 1 Tank 2C 2
Pressure Zone 2N Pressure Zone 2N
30
25
20
15
10
5
30
25
20
15
10
5
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
Avg. % Difference = 2%Avg. % Difference = 1%Tank 2E 1
Pressure Zone 2S
Tank 2E 2
Pressure Zone 2S
30
25
20
15
10
5
30
25
20
15
10
5
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure .
Storage Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 609 of 768
Avg. % Difference = 4%Avg. % Difference = 4%Tank 2F 1 Tank 3D 1
Pressure Zone 2S Pressure Zone 3
30
25
20
15
10
5
30
25
20
15
10
5
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
Avg. % Difference = 5%Tank 3D 2
Pressure Zone 3
30
25
20
15
10
5
0
0 6 12 18 24
Time (hours)
LEGEND Figure .
Storage Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 610 of 768
Avg. % Difference = 1%Avg. % Difference = 1%
Well 1 Flow
Pressure Zone 1
Well 1 Outlet Pressure
Pressure Zone 13,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12
Time (hours)
18 24
Time (hours)
Avg. % Difference = 0%Avg. % Difference = 149%
Well 2 Flow Well 2 Outlet Pressure
Pressure Zone 1 Pressure Zone 1
3,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure .
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 611 of 768
Avg. % Difference = 0%Avg. % Difference = 3%Well 3 Flow
Pressure Zone 1
Well 3 Outlet Pressure
Pressure Zone 13,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12
Time (hours)
18 24
Time (hours)
Avg. % Difference = 1%Avg. % Difference = 3%Well 4 Flow Well 4 Outlet Pressure
Pressure Zone 1 Pressure Zone 1
3,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure .
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 612 of 768
Avg. % Difference = 0%Avg. % Difference = 8%
Well 5 Flow
Pressure Zone 1
Well 5 Outlet Pressure
Pressure Zone 13,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12
Time (hours)
18 24
Time (hours)
Avg. % Difference = 4%Avg. % Difference = 2%
Well 6 Flow Well 6 Outlet Pressure
Pressure Zone 1 Pressure Zone 1
3,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure .
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 613 of 768
Avg. % Difference = 1%Avg. % Difference = 10%
Well 7 Flow
Pressure Zone 1
Well 7 Outlet Pressure
Pressure Zone 13,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12
Time (hours)
18 24
Time (hours)
Avg. % Difference = 2%Avg. % Difference = 13%
Well 8 Flow Well 8 Outlet Pressure
Pressure Zone 1 Pressure Zone 1
3,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
00
0 6 12 18 24 0 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 614 of 768
Avg. % Difference = 15%Avg. % Difference = 64%
Well 8A Flow BS1 Flow
Pressure Zone 1 Pressure Zone 2N
3,000
2,500
2,000
1,500
1,000
500
3,000
2,500
2,000
1,500
1,000
500
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
Avg. % Difference = 6%Avg. % Difference = 41%
BS1 Outlet Pressure BS2 Flow
Pressure Zone 3Pressure Zone 2N150
120
90
60
30
0
3,000
2,500
2,000
1,500
1,000
500
0
006121824 6 12
Time (hours)
18 24
Time (hours)
LEGEND Figure
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 615 of 768
Avg. % Difference = 25%Avg. % Difference = 38%
BS2 Outlet Pressure BS3 Flow
Pressure Zone 3 Pressure Zone 3150
120
90
60
30
0
3,000
2,500
2,000
1,500
1,000
500
0
00612
Time (hours)
18 24 6 12
Time (hours)
18 24
Avg. % Difference = 11%Avg. % Difference = 63%
BS3 Outlet Pressure BS4 Flow
Pressure Zone 2NPressure Zone 3150
120
90
60
30
0
3,000
2,500
2,000
1,500
1,000
500
0
006121824 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 616 of 768
Avg. % Difference = 17%Avg. % Difference = 2%
BS4 Inlet Pressure BS4 Outlet Pressure
Pressure Zone 2N Pressure Zone 2N150
120
90
150
120
90
60 60
30 30
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
Avg. % Difference = 92%Avg. % Difference = 1%
BS5 Flow BS5 Inlet Pressure
Pressure Zone 2S Pressure Zone 2S
3,000
2,500
2,000
1,500
1,000
500
150
120
90
60
30
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 617 of 768
Avg. % Difference = 0%Avg. % Difference = 35%BS5 Outlet Pressure BS6 Flow
Pressure Zone 2S Pressure Zone 2S150
120
90
60
30
0
3,000
2,500
2,000
1,500
1,000
500
0
00612
Time (hours)
18 24 6 12 18 24
Time (hours)
Avg. % Difference = 48%Avg. % Difference = 3%
BS6 Inlet Pressure BS6 Outlet Pressure
Pressure Zone 2S Pressure Zone 2S150
120
90
150
120
90
60 60
30 30
0
0
0
06121824 6 12 18 24
Time (hours)Time (hours)
LEGEND Figure
Pump Calibration
Water System Master Plan
City of Gilroy
Telemetry Data
Model Data
April 20, 2021
Agenda Item 9.2
Page 618 of 768
Table ES.3 Capital Improvement Program
Water System Master Plan
City of Gilroy
PRELIMINARY
Infrastructure Costs Suggested Cost Allocation Cost Sharing
Existing Diameter New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost
Existing
Users Future Users Existing Users Future Users
(in)(in)(ft)($)($)($)($)($)
Pipeline Improvements
P1-1 Future Growth Zone 1 Day Rd From Santa Teresa Blvd to Monterey Hwy - New 12 3,860 254 978,700 978,700 1,272,400 1,654,200 With Development 0% 100% 0 1,654,200
P1-2 Future Growth Zone 1
Monterey Hwy / Orsetti
Rd / Hwy 101 From approx. 620' n/o Day Rd to Cohansey Ave - New 12 5,780 254 1,465,500 1,465,500 1,905,200 2,476,800 With Development 0% 100% 0 2,476,800
P1-3 Existing Deficiency Zone 1 Monterey Hwy From 2nd St to Ioof Ave 12 Replace 16 230 304 70,000 70,000 91,000 118,300 Existing Deficiency 100% 0% 118,300 0
P1-4 Existing Deficiency Zone 1 Murray Ave From Well 5-02 to Ioof Ave 12 Replace 16 2,200 304 669,400 669,400 870,300 1,131,400 Existing Deficiency 100% 0% 1,131,400 0
P1-5 Existing Deficiency Zone 1 Arroyo Cir From Well 7 to Ioof Ave 12 Replace 16 70 304 21,300 21,300 27,700 36,100 Existing Deficiency 100% 0% 36,100 0
P1-6 Existing Deficiency Zone 1 Lewis St From approx. 180' e/o Forest St to Chestnut St 8 Replace 10 230 211 48,600 48,600 63,200 82,200 Existing Deficiency 100% 0% 82,200 0
P1-7 Existing Deficiency Zone 1 Forest St From Well 3 to 6th St 10 Replace 12 320 254 81,200 81,200 105,600 137,300 Existing Deficiency 100% 0% 137,300 0
P1-8 Existing Deficiency Zone 1
Gilman Rd / Camino
Arroyo From Well 8 to approx. 80' se/o Gilman Rd 12 Replace 16 300 304 91,300 91,300 118,700 154,400 Existing Deficiency 100% 0% 154,400 0
P1-9 FF Reliability Zone 1 Pacheco Pass Hwy From Camino Arroyo to Cameron Blvd 12 Replace 16 1,730 304 526,400 526,400 684,400 889,800 As Funding is Available 100% 0% 889,800 0
P1-10 FF Reliability Zone 1 Camino Arroyo From Pacheco Pass Hwy to Venture Wy 12 Replace 16 3,040 304 925,000 925,000 1,202,500 1,563,300 As Funding is Available 100% 0% 1,563,300 0
P1-11 FF Reliability Zone 1 Cameron Blvd From Pacheco Pass Hwy to approx. 200' se/o Venture
Wy 12 Replace 16 2,100 304 639,000 639,000 830,700 1,080,000 As Funding is Available 100% 0% 1,080,000 0
P1-12 Future Growth Zone 1 ROW From Camino Arroyo to approx. 1,800' e/o Luchessa Ave -New 16 1,620 304 492,900 492,900 640,800 833,100 With Development 0% 100%0 833,100
P1-13 Future Growth Zone 1 ROW / Cameron Blvd From approx. 200' se/o Venture Wy to Southside Dr -New 16 4,540 304 1,381,300 1,381,300 1,795,700 2,334,500 With Development 0% 100%0 2,334,500
P1-14 FF Reliability Zone 1 Luchessa Ave From Thomas Rd to Rossi Ln 12 Replace 16 6,480 304 1,971,600 1,971,600 2,563,100 3,332,100 As Funding is Available 100% 0% 3,332,100 0
P1-15 FF Reliability Zone 1 Thomas Rd From Luchessa Ave to Santa Teresa Rd 12 Replace 16 3,060 304 931,000 931,000 1,210,300 1,573,400 As Funding is Available 100% 0% 1,573,400 0
P1-16 FF Reliability Zone 1 Rossi Ln From Luchessa Ave to Southside Dr
12 Replace 16 2,730 304 830,600 830,600 1,079,800 1,403,800 As Funding is Available 100% 0% 1,403,800 0
P1-17 Future Growth Zone 1 ROW From Luchessa Ave to approx. 1,800' e/o Luchessa Ave -New 16 1,810 304 550,700 550,700 716,000 930,800 With Development 0% 100%0 930,800
P1-18 Future Growth Zone 1 ROW From approx. 1,800' e/o Luchessa Ave to Southside Dr
-New 16 2,890 304 879,300 879,300 1,143,100 1,486,100 With Development 0% 100%0 1,486,100
P1-19 FF Reliability Zone 1 Garlic Farm Wy /
Southside Dr From Hwy 101 to Arizona Cir 12 Replace 16 4,630 304 1,408,700 1,408,700 1,831,400 2,380,900 As Funding is Available 100% 0% 2,380,900 0
P1-20 Future Growth Zone 1 Southside Dr From Arizona Cir to approx. 660' e/o Arizona Cir - New 16 660 304 200,900 200,900 261,200 339,600 With Development 0% 100% 0 339,600
P1-21 Future Growth Zone 1 Southside Dr From approx. 660' e/o Arizona Cir to Camaron Blvd - New 16 3,010 304 915,800 915,800 1,190,600 1,547,800 With Development 0% 100% 0 1,547,800
P1-22 Future Growth Zone 1 Santa Teresa Blvd From approx. 160' w/o Thomas Rd to approx. 110' e/o
Thomas Rd -New 16 280 304 85,200 85,200 110,800 144,100 With Development 0% 100%0 144,100
Subtotal - Pipeline Improvements 15,164,400 19,714,500 25,630,000 13,883,000 11,747,000
Storage Reservoir Improvements
3H-1 Storage Capacity Zone 3 Construct an additional 0.1 MG storage reservoir at existing 3D site New 133,442 133,500 173,600 225,700 813 EDU 0% 100% 0 225,700
Subtotal - Storage Reservoir Improvements 133,500 173,600 225,700 0 225,700
Estimated Const.
Costs1
Proposed Storage Capacity
(MG)
0.10
Improv. No.
Pipeline Information Capital Improv.
Costs2 Construction TriggerBaseline Constr.
CostsImprov. Type Pressure
Zone Alignment Limits
Agenda Item 9.2
Page 619 of 768
Table ES.3 Capital Improvement Program
Water System Master Plan
City of Gilroy
PRELIMINARY
Infrastructure Costs Suggested Cost Allocation Cost Sharing
Existing Diameter New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost
Existing
Users Future Users Existing Users Future Users
(in)(in)(ft)($)($)($)($)($)
Estimated Const.
Costs1Improv. No.
Pipeline Information Capital Improv.
Costs2 Construction TriggerBaseline Constr.
CostsImprov. Type Pressure
Zone Alignment Limits
Groundwater Well Improvements
GW-10 Supply Capacity Zone 1 Construct new well near the intersection of San Ysidro Ave and Las Animas Ave New ---3,922,000 9,500 EDU 0% 100%0 3,922,000
GW-11 Supply Capacity Zone 1 Construct new well near the intersection of Camino Arroyo and Renz Lane New ---3,922,000 15,550 EDU 0% 100%0 3,922,000
GW-12 Supply Capacity Zone 1 Construct new well near the intersection of Wren Ave and Vickery Ln New ---3,922,000 21,600 EDU 0% 100%0 3,922,000
Subtotal - Groundwater Well Improvements 0 0 11,766,000 0 11,766,000
Total Improvement Cost
Pipeline Improvements 15,164,400 19,714,500 25,630,000 13,883,000 11,747,000
Storage Reservoirs 133,500 173,600 225,700 0 225,700
Groundwater Wells 0 0 11,766,000 0 11,766,000
Total Improvement Costs 15,297,900 19,888,100 37,621,700 13,883,000 23,738,700
Notes: 3/29/2023
1. Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.
2. Estimated construction costs plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal costs.
3. Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,176 for March 2023.
1,500
Proposed Pumping Capacity
(gpm)
1,500
1,500
Agenda Item 9.2
Page 620 of 768
4
3
0
RESOLUTION NO. 2023-XX
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF
GILROY ADOPTING THE WATER MASTER PLAN FOR
THE CITY OF GILROY
WHEREAS, the 2022 Water Master Plan (Plan) serves as a guide to assess the
current operations and functionality of the City’s existing water system; and
WHEREAS, the City last developed a Water Master Plan in 2004, which identified
capacity deficiencies in the existing water system and recommended improvements to
alleviate existing deficiencies and serve future developments in the Gilroy Planning Area;
and
WHEREAS, Akel Engineering Group, Inc. was retained by the City Council in
August 2019 to prepare the Plan; and
WHEREAS, the objective of the Plan is to review and make recommendations on
how the current water system can be upgraded within the City to best suit the water needs
of the City in the future; and
WHEREAS, the projects identified in the Plan will be added to the City’s Capital
Improvement Program; and
NOW, THEREFORE, BE IT RESOLVED that the City Council of the City of Gilroy
hereby adopts the Water Master Plan attached hereto and made a part hereof.
PASSED AND ADOPTED by the City Council of the City of Gilroy at a regular
meeting duly held on the 3rd day of April 2023 by the following roll call vote:
AYES:COUNCIL MEMBERS:
NOES:COUNCIL MEMBERS:
ABSTAIN:COUNCIL MEMBERS:
ABSENT:COUNCIL MEMBERS:
APPROVED:
ATTEST:__________________________
Marie Blankley, Mayor
__________________________
Thai Nam Pham, City Clerk
Agenda Item 9.2
Page 621 of 768
Page 1 of 4
City of Gilroy
STAFF REPORT
Agenda Item Title:Adopt the 2022 Storm Drainage System Master Plan
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:Public Works
Submitted By:Daryl Jordan, Public Works Director
Prepared By:Michael Lewis, Management Analyst
STRATEGIC PLAN GOALS Maintain and Improve City Infrastructure
RECOMMENDATION
Approve a resolution to adopt the 2022 Storm Drainage System Master Plan.
BACKGROUND
The City’s most recent storm drainage master plan was completed in 2004. This 2004
Master Plan included evaluation of the existing system and identifying storm drainage
improvements required to serve future growth. Additionally, the 2004 Master Plan
included the development of the hydrologic and hydraulic models, which were used for
evaluating the storm drainage system. Improvements were recommended for servicing
existing and future growth areas, and a corresponding Capital Improvement Program
was developed to quantify the costs associated with each improvement. With the
recent update to the 2040 General Plan, there was a need to update the 2004 Master
Plan to accommodate the expected growth and land use changes identified in the
updated plan.
Currently, stormwater runoff discharges to the Uvas Creek, Ronan Channel, Miller
Slough Channel, Princevalle Channel, and Lower Miller Slough Channel. The City
maintains a rich diversity of land use types, contributing to varying stormwater runoff
containment needs. Several creeks, a vast array of agricultural lands, and small
pockets of development, and the city comprises a wide array of runoff generation and
conveyance within the planning area.
Agenda Item 9.3
Page 622 of 768
Adopt the 2022 Storm Drainage System Master Plan
City of Gilroy City Council Page 2 of 4 April 3, 20239
2
6
The city has multiple major watersheds within the Urban Growth Boundary that collect
and convey stormwater runoff, and are as follows: Uvas Creek, Llagas Creek, and
Pajaro River. The portion of the Uvas Creek Watershed within the City Limits is
generally defined as the area bounded by Rancho Vista Drive to the west and Santa
Teresa Boulevard to the east, with the northern and southern boundaries approximately
represented by Uvas Creek and Santa Cruz Mountains, respectively.
The portion of the Lower Coyote Creek Watershed within the City Limits is generally
bounded by Olea Court to the west and Llagas Creek to the east, with the northern and
southern boundaries approximately represented by Fitzgerald Avenue and Luchessa
Avenue, respectively.
The Pajaro River Watershed within the City Limits is generally defined as the area
bounded by Uvas Creek to the west and Llagas Creek to the east, with the northern
and southern boundaries approximately represented by Luchessa Avenue and
Southside Drive, respectively.
To improve existing deficiencies and provide infrastructure to support future growth, it
became apparent that an updated Storm Drainage Master Plan was necessary. As
such, the City Council approved Akel Engineering Group, Inc. to prepare the 2022
Master Plan and a concurrent Sewer System Master Plan and Water Master Plan in
August 2019. These documents were coordinated for consistency with the City’s 2040
General Plan.
ANALYSIS
The 2022 Master Plan updates elements of the 2004 Master Plan to reflect current land
use conditions and 2040 General Plan updates.
The City Council authorized Akel Engineering Group, Inc. to perform the following tasks:
1. Summarize the City’s existing stormwater system facilities.
2. Document growth planning assumptions and known future developments.
3. Update the stormwater system performance criteria and design storm events.
4. Develop new hydrologic and hydraulic models.
5. Evaluate the storm drainage facilities to address hydraulic capacity requirements
from existing and projected developments.
6. Recommend a capital improvement program (CIP) with an opinion of probable
construction costs.
7. Perform a cost allocation analysis for cost-sharing purposes.
8. Develop a 2022 Storm Drainage System Master Plan Report.
Agenda Item 9.3
Page 623 of 768
Adopt the 2022 Storm Drainage System Master Plan
City of Gilroy City Council Page 3 of 4 April 3, 20239
2
6
RESULTS
The 2022 Master Plan provides recommendations for improvements needed to mitigate
existing deficiencies and improvements needed to expand the system to service future
growth identified in the 2040 General Plan. The recommended capital improvement
program (Table 6.2) is attached as Attachment 1.
The Master Plan indicates that overall that the City’s storm system is in fair condition but
in need of improvements to mitigate some specific deficiencies and that future capacity
projects will be development driven. In total, the plan recommends 43 pipeline
improvement and replacement projects in six (6) drainage areas. Seven out of forty-two
projects worth $2,300,000 were completed from the last master plan. The current list
includes projects carried over from the 2004 Master Plan that was not completed and
new projects needed to accommodate future growth based on the updated Storm
Drainage System modeling. The projects identified will be added to the City’s Capital
Improvement Program and budget.
Drainage
Basin
Number of
Improvements
Needed for
Capacity
Cost of
Needed
Capacity
Improvements
Number of
Improvements
to Support
Future Growth
Cost of Future
Improvements
Ronan
Channel 4 $5,061,676 5 $5,228,524
Miller Slough 6 $2,543,000 0 $0
North Uvas 4 $7,580,300 4 $2,808,900
South Uvas 1 $217,700 0 $0
Princevalle 12 $8,391,047 1 $79,253
Lower Miller
Slough 6 $2,926,500 0 $0
Total Cost $26,720,424 $8,116,676
ALTERNATIVES
Council may modify or reject the 2022 Storm Drainage System Master Plan. This is not
recommended due to the fact that this would restrict opportunities to update and
maintain the citywide storm drains system.
FISCAL IMPACT/FUNDING SOURCE
The City currently has one Storm Drain Impact Fee Fund which is utilized to fund the
capital improvements. The Fund, which collects revenues from impact fees from
developments that impact future growth, primarily funds infrastructure/capital costs
attributable to future users for future capacity needs. The Fund has a projected FY23
ending fund balance of $1.2 million. There is no current revenue source, other than
Agenda Item 9.3
Page 624 of 768
Adopt the 2022 Storm Drainage System Master Plan
City of Gilroy City Council Page 4 of 4 April 3, 20239
2
6
General Fund, to fund the annual operational, maintenance, and capital costs to repair
and maintain existing infrastructure.
Of the total $34.8 million in capital improvements identified in the Master Plan,
approximately $8.1 million is attributable to existing users, and $26.7 million is
attributable to future users - to be funded by Storm Drain Impact Fee Fund. The Master
Plan capital improvements are in addition to the existing capital improvements identified
by staff.
The Storm Drain Impact Fee Fund does not have sufficient fund balances to fund the
$8.1 million identified in future user costs. A typical next step after the Master Plans are
updated is to review and update the development impact fees to incorporate the
identified future growth capital improvements and adjust the fees accordingly to ensure
capital needs are adequately funded for a period of time. Staff will plan to review and
update the storm drain impact fee as a departmental work plan in the upcoming fiscal
year.
There is also a need to develop another revenue stream to pay for stormwater
improvements, as well as operations and maintenance. Additional funding mechanisms
are required since Storm Drainage is not an Enterprise Fund, like Sewer and Water,
funded by user fees. Because of this, storm drain maintenance and capital projects
must be paid out of the General Fund if it does not qualify for the use of storm drain
impact fees. This will be studied over the next year.
NEXT STEPS
With Council adoption of the 2022 Storm Drainage System Master Plan, staff will
incorporate the projects into the City’s Capital Improvement Program and plan for the
delivery of these projects.
Attachments:
1. Storm Drainage System Master Plan Attachment 1
2. Storm Drainage System Master Plan Capital Improvement Program List
3. Storm Drainage System Master Plan Resolution
Agenda Item 9.3
Page 625 of 768
Agenda Item 9.3
Page 626 of 768
CITY OF GILROY
2023
STORM DRAINAGE
SYSTEM
MASTER PLAN
Final
March 2023
Agenda Item 9.3
Page 627 of 768
Smart Planning Our Water Resources
March 29, 2023
City of Gilroy
7351 Rosanna Street
Gilroy, CA 95020
Attention: Gary Heap, P.E.
City Engineer
Subject: 2023 Storm Drainage System Master Plan – Final Report
Dear Gary:
We are pleased to submit the draft report for the City of Gilroy Storm Drainage System Master
Plan. This master plan is a standalone document, though it was prepared as part of the
integrated infrastructure master plans for the water, sewer, and storm drainage master plans.
The master plan documents the following:
•Existing system facilities, acceptable hydrologic and hydraulic performance criteria, and
projected stormwater runoff consistent with the Urban Planning Area
•
•
Development of the City’s GIS-based hydrologic and hydraulic stormwater models.
Capacity evaluation of the existing system with improvements to mitigate existing
deficiencies and to accommodate future growth.
•Capital improvement program (CIP) with an opinion of probable construction costs and
suggestions for cost allocations to meet AB 1600.
We extend our thanks to you, Daryl Jordan, Director of Public Works and other City staff whose
courtesy and cooperation were valuable components in completing this study.
Sincerely,
AKEL ENGINEERING GROUP, INC.
Tony Akel, P.E., D. WRE
President
Enclosure: Report
7 4 3 3 N . F I R S T S T R E E T , S U I T E 1 0 3 •F R E S N O , C A L I F O R N I A 9 3 7 2 0 •( 5 5 9 ) 4 3 6 - 0 6 0 0 •F A X ( 5 5 9 ) 4 3 6 - 0 6 2 2
www.akeleng.com
Agenda Item 9.3
Page 628 of 768
Acknowledgements
City Council
Marie Blankley, Mayor
Dion Bracco , Mayor Pro Tempore
Rebeca Armendariz
Tom Cline
Zach Hilton
Carol Marques
Fred Tovar
Management Personnel
Jimmy Forbis, City Administrator
Daryl Jordan, P.E., Director of Public Works
Gary Heap, P.E., City Engineer
Jorge Duran, P.E., Senior City Engineer
Sharon Goei, Community Development Director
Matt Jones, Deputy Director of Public Works
Other City Engineering, Planning, and Operations Staff
Agenda Item 9.3
Page 629 of 768
City of Gilroy
Storm Drainage System Master Plan
TABLE OF CONTENTS PAGE NO.
EXECUTIVE SUMMARY .................................................................................................ES-1
ES.1 STUDY OBJECTIVES .....................................................................................ES-1
ES.2 INTEGRATED APPROACH TO MASTER PLANNING ....................................ES-1
ES.3 STUDY AREA DESCRIPTION.........................................................................ES-2
ES.4 SYSTEM PERFORMANCE AND DESIGN CRITERIA.....................................ES-2
ES.5 HYDROLOGIC AND HYDRAULIC MODEL DEVELOPMENT..........................ES-6
ES.6 CAPACITY EVALUATION ...............................................................................ES-6
ES.7 CAPITAL IMPROVEMENT PROGRAM...........................................................ES-9
CHAPTER 1 - INTRODUCTION ......................................................................................1-1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
BACKGROUND...............................................................................................1-1
SCOPE OF WORK..........................................................................................1-1
INTEGRATED APPROACH TO MASTER PLANNING ....................................1-3
PREVIOUS MASTER PLANS..........................................................................1-3
RELEVANT REPORTS ...................................................................................1-3
REPORT ORGANIZATION..............................................................................1-4
ACKNOWLEDGEMENTS................................................................................1-4
UNIT CONVERSIONS AND ABBREVIATIONS...............................................1-5
GEOGRAPHIC INFORMATION SYSTEMS.....................................................1-5
CHAPTER 2 – PLANNING AREA CHARACTERISTICS ................................................2-1
2.1
2.2
STUDY AREA DESCRIPTION.........................................................................2-1
WATERSHEDS AND DRAINAGE AREAS ......................................................2-1
2.2.1 Watersheds .......................................................................................2-3
2.2.2 Drainage Areas..................................................................................2-3
FLOODPLAINS ...............................................................................................2-3
EXISTING SERVICE AREAS AND LAND USE ...............................................2-6
HISTORICAL AND PROJECTED POPULATION.............................................2-6
2.3
2.4
2.5
CHAPTER 3 – SYSTEM PERFORMANCE AND DESIGN CRITERIA.............................3-1
3.1 HYDROLOGIC CRITERIA...............................................................................3-1
3.1.1 Precipitation Characteristics ..............................................................3-1
3.1.2 Design Storms...................................................................................3-1
3.1.3 Design Storm Events.........................................................................3-4
3.1.4 Soil Imperviousness...........................................................................3-4
HYDRAULIC CRITERIA ..................................................................................3-8
3.2.1 Gravity Conveyance Facilities............................................................3-8
3.2
CHAPTER 4 – EXISTING FACILITIES AND MODEL DEVELOPMENT..........................4-1
4.1 HYDROLOGIC SYSTEM OVERVIEW.............................................................4-1
4.1.1 Watersheds .......................................................................................4-1
4.1.2 Drainage Areas..................................................................................4-1
4.1.3 Drainage Sub-catchment...................................................................4-3
HYDRAULIC SYSTEM OVERVIEW ................................................................4-4
4.2.1 Conveyance System..........................................................................4-4
4.2.2 Outfalls..............................................................................................4-4
MODEL DEVELOPMENT................................................................................4-8
4.3.1 Modeling Software.............................................................................4-8
4.2
4.3
March 2023 i City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 630 of 768
City of Gilroy
Storm Drainage System Master Plan
TABLE OF CONTENTS PAGE NO.
4.3.2 Land Use and Routing Methodology..................................................4-8
4.3.3 Hydrological Soil Classification..........................................................4-9
4.3.4 Typical Channel Cross-Section..........................................................4-9
4.3.5 Physical Hydraulic Model Elements...................................................4-9
CHAPTER 5 – EVALUATION AND PROPOSED IMPROVEMENTS ..............................5-1
5.1
5.2
5.3
5.4
OVERVIEW .....................................................................................................5-1
KNOWN AREAS OF CONCERN.....................................................................5-1
PIPELINE CONVEYANCE CAPACITY EVALUATION.....................................5-1
CAPACITY EVALUATION ANALYSIS.............................................................5-1
5.4.1 Alternative 1 - 8th Street 36-inch Pipeline Improvements....................5-4
5.4.2 Alternative 2 – Diverting Stormwater Runoff to Princevalle Channel..5-4
5.4.3 Ronan Channel Drainage Area..........................................................5-9
5.4.4 Miller Slough Drainage Area..............................................................5-9
5.4.5 North Uvas Drainage Area.................................................................5-10
5.4.6 South Uvas Drainage Area................................................................5-10
5.4.7 Princevalle Drainage Area.................................................................5-11
5.4.8 Lower Miller Slough Drainage Area ...................................................5-12
OUTFALLS......................................................................................................5-125.5
CHAPTER 6 - CAPITAL IMPROVEMENT PROGRAM ...................................................6-1
6.1
6.2
COST ESTIMATE ACCURACY.......................................................................6-1
COST ESTIMATE METHODOLOGY...............................................................6-2
6.2.1 Unit Costs..........................................................................................6-2
6.2.2 Construction Cost Index ....................................................................6-2
6.2.3 Construction Contingency Allowance.................................................6-2
6.2.4 Project Related Costs........................................................................6-2
CAPITAL IMPROVEMENT PROGRAM...........................................................6-4
6.3.1 Capital Improvement Costs................................................................6-4
6.3.2 Pipelines............................................................................................6-4
6.3.3 Recommended Cost Allocation Analysis............................................6-9
6.3
March 2023 ii City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 631 of 768
City of Gilroy
Storm Drainage System Master Plan
TABLE OF CONTENTS PAGE NO.
FIGURES
Figure ES.1
Figure ES.2
Figure ES.3
Figure ES.4
Figure 1.1
Figure 2.1
Figure 2.2
Figure 2.3
Figure 2.4
Figure 2.5
Figure 3.1
Figure 4.1
Figure 4.2
Figure 4.3
Figure 4.4
Figure 5.1
Figure 5.2
Figure 5.3
Figure 6.1
Regional Location Map......................................................................ES-3
Planning Area....................................................................................ES-4
Existing Storm Drainage System .......................................................ES-7
Capital Improvement Program...........................................................ES-8
Regional Location Map....................................................................................1-2
Planning Area..................................................................................................2-2
Waterways and Watersheds............................................................................2-4
FEMA 100 Year Flood Zones ..........................................................................2-5
Existing Land Use ...........................................................................................2-7
2040 General Plan Land Use ..........................................................................2-8
10-Year/24-Hour Unit Hyetograph ...................................................................3-5
Storm Drainage Areas.....................................................................................4-2
Existing Modeled Storm Drainage Systems.....................................................4-5
Hydrological Soil Classification........................................................................4-10
Typical Channel Cross-Section .......................................................................4-11
Existing System Analysis 10-Year Design Storm.............................................5-2
Proposed Improvements Alternative 1.............................................................5-5
Proposed Improvements Alternative 2.............................................................5-6
Capital Improvement Program.........................................................................6-5
TABLES
Table ES.1 Hydrologic and Hydraulic Design Criteria ........................................................ ES-5
Table ES.2 Unit Costs ....................................................................................................... ES-10
Table ES.3 Capital Improvement Program......................................................................... ES-11
Table 1.1
Table 1.2
Table 2.1
Table 2.2
Table 3.1
Table 3.2
Table 3.3
Table 3.4
Table 3.5
Table 4.1
Table 4.2
Table 5.1
Table 5.2
Table 6.1
Table 6.2
Unit Conversions............................................................................................. 1-6
Abbreviations and Acronyms........................................................................... 1-7
Existing and Future Land Use ......................................................................... 2-9
Historical and Projected Population................................................................. 2-10
Precipitation Depth-Duration-Frequency Data................................................. 3-2
Precipitation Depth-Duration-Frequency Comparison...................................... 3-3
Relevant Design Storms.................................................................................. 3-6
Soil Imperviousness and SCS Curve Numbers ............................................... 3-7
Hydrologic and Hydraulic Design Criteria ........................................................ 3-9
Existing GIS Storm Pipe Inventory .................................................................. 4-6
Existing Modeled Storm Pipe Inventory........................................................... 4-7
Storm Drainage System Problem Areas.......................................................... 5-3
Proposed Improvements ................................................................................. 5-7
Unit Costs ....................................................................................................... 6-3
Capital Improvement Program......................................................................... 6-6
March 2023 iii City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 632 of 768
City of Gilroy
Storm Drainage System Master Plan
TABLE OF CONTENTS
APPENDICES
Appendix A Hydrology Review
Appendix B Storm Drainage Area Hydrologic Routing
March 2023 iv City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 633 of 768
2023City of Gilroy
EXECUTIVE SUMMARY
This executive summary presents a brief background of the City of Gilroy’s (City) storm drainage
system, the planning area characteristics, the hydrology and hydraulic criteria, and the hydrology
and hydraulic model developments.
These hydrology and hydraulic models were used to evaluate the capacity adequacy of the
existing stormwater drainage system, for recommending improvements to mitigate existing
deficiencies and for servicing future growth. The prioritized capital improvement program accounts
for growth through the Gilroy Planning Area.
ES.1 STUDY OBJECTIVES
Recognizing the importance of planning, developing, and financing system facilities to provide
reliable stormwater system service to existing customers and for servicing anticipated growth
within the sphere of influence, the City initiated the 2022 Storm Drainage System Master Plan.
The City of Gilroy authorized Akel Engineering Group Inc. to complete the following tasks:
•
•
•
•
•
Summarize the City’s existing stormwater system facilities.
Document growth planning assumptions and known future developments.
Update the stormwater system performance criteria and design storm event.
Develop new hydrologic and hydraulic models.
Evaluate the storm drainage facilities to address hydraulic capacity requirements from
existing and projected developments.
•Recommend a capital improvement program (CIP) with an opinion of probable
construction costs.
•
•
Perform a cost allocation analysis for cost sharing purposes.
Develop a 2023 Storm Drainage System Master Plan Report.
ES.2 INTEGRATED APPROACH TO MASTER PLANNING
The City implemented an integrated master planning approach and contracted the services of
Akel Engineering Group Inc. to prepare the following documents:
•
•
•
2023 Water System Master Plan
2023 Sewer System Master Plan
2023 Storm Drainage System Master Plan
March 2023 ES-1 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 634 of 768
While each of these reports is published as a standalone document, it has been coordinated for
consistency with the City’s General Plan. Additionally, each document has been cross referenced
to reflect relevant analysis results with the other documents.
ES.3 STUDY AREA DESCRIPTION
The City of Gilroy is located in Santa Clara County near the west coast of California, south of City
of San Francisco. The City of Gilroy lies within the seismically active region of San Francisco Bay.
The City of Gilroy lies in the southern portion of the Santa Clara County and is the most southern
City located within the county. The City is located approximately 32 miles southeast of the City of
San Jose, 8 miles southeast of Morgan Hill, 25 miles east of City of Santa Cruz, and 16 miles
northwest of City of Hollister. The City limits currently encompass 16.5 square miles, with an
approximate population of 56,599 residents, according to Department of Finance as of January
2021. Figure ES.1 displays the City’s location.
The City’s service area is generally bound to the north by Fitzgerald Avenue, to the northeast by
San Ysidro Avenue, to the southeast by Camino Arroyo, to the west by Burchell Road and
Rancho Vista Drive, and to the south by Carnadero Avenue. U.S. Route 101 divides the City in a
southeast to northwest direction and the California State Route 152 (Hecker Pass Hwy) runs east-
west direction in the northern half of the City. The topography is generally flat in the middle of the
service area, with increasing slopes in the east and west side of the City due to the Santa Cruz
Mountains to the west and the Diablo Range to the east. Figure ES.2 displays the planning area
showing City limits, the Urban Growth Boundary (UGB) of the City and Planning Area / Sphere of
Influence (SOI).
The City operates and maintains a storm drainage system that covers the area within the City
Limits. Currently, stormwater runoff discharges to the Uvas Creek, Ronan Channel, Miller Slough
Channel, Princevalle Channel and Lower Miller Slough Channel.
ES.4 SYSTEM PERFORMANCE AND DESIGN CRITERIA
This report documents the City’s performance and design criteria that were used for evaluating
hydrologic and hydraulic systems within the City’s drainage watershed (Table ES.1). Hydrologic
criteria are developed to characterize the flood routing of rainfall runoff in a defined drainage
system. Akel Engineering Group Inc. obtained the services of Kasraie Consulting to review the
hydrologic modeling approach, applied rainfall depths and distributions, sub-catchment
delineations, model runoff, and outflow hydrographs of this project. The hydraulic criteria for the
storm drainage system were used to evaluate the capacity requirements of conveyance facilities.
Two design storms were used for the evaluation of the City’s existing storm drainage system, and
for the future drainage conveyance facilities. The 10-year 24-hour design storm was used for
evaluating the pipeline conveyance facilities as well as to size future pipeline while the 100-year
24-hour design storm was used to determine if street flooding exceeds one foot in depth.
March 2023 ES-2 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 635 of 768
Calero
Reservoir
Anderson
Reservoir£¤
101
Morgan Hill
!(
Coyote
Reservoir
Uvas
Reservoir £¤
101
UV152 Gilroy
UV152£¤
101
UV152
UV25
WatsonvilleUV!(UV152
129UV
1 £¤
101UVUV129129
Legend Figure ES.1
Regional Location Map!( Cities
Study Area
Elevation (ft)
9 - 50
1,001 - 2,000
2,001 - 3,000
3,001 - 3,792 Storm Drainage System Master Plan
City of Gilroy
City Limits 51 - 100
Urban Growth Boundary
Highway
101 - 250
251 - 500
501 - 1,000
Waterbodies 5RailroadsGIS
0 0.5 1 2Updated: September 21, 2020 Miles
Flie Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig1-1RLMap_092120.mxd
Agenda Item 9.3
Page 636 of 768
¤
101
Coyote
Reservoir
UV UV152152
City of Gilroy
£¤
101 UV152
£¤
101
V25
Legend Figure ES.2
Planning AreaCity Limits General Plan Area
RoadsCity Limits Area
Storm Drainage System Master Plan
City of Gilroy
Specific Plan Areas
Urban Service Area
Urban Growth Boundary
Sphere of Influence Boundary
Highways
Railroads
5Rivers & Creeks
Waterbodies GIS
0 0.5 1 2
Updated: April 15, 2022 Miles
File Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig2-1PlanningArea_041522.mxd
Agenda Item 9.3
Page 637 of 768
Table ES.1 Hydrologic and Hydraulic Design Criteria
Storm Drainage System Master Plan
City of Gilroy
Hydrology and Hydraulics Design Criteria
Conveyance Facilities
10-Year 24-Hour design storm to determine if storm water
Pipelines
Streets
have a minimum of one foot of freeboard between the top
of curb and the Hydraulic Grade Line.
100-Year 24-Hour design storm to determine if flooding
exceeds one foot in depth and can flood buildings or create
safety hazards.
FEMA 100-year water surface elevations used for
downstream control for facilities where 100-year flood maps
are available.
Receiving Waters
(Streams, Creeks, Channels)
9/16/2020
Agenda Item 9.3
Page 638 of 768
ES.5 HYDROLOGIC AND HYDRAULIC MODEL DEVELOPMENT
Factors critical to the hydrologic model development include watersheds, drainage areas within
each watershed, overland flow routing within drainage sub-catchments, and conveyance that
makes full use of pipes as well as streets for routing 100-year design storm events. The hydraulic
model was developed to evaluate the capacity adequacy of the City’s storm drainage system. The
model was used to identify capacity deficiencies and to recommend improvements to mitigate
those deficiencies.
The hydrologic and hydraulic modeling software used for evaluating the capacity adequacy of the
City’s storm drainage system, InfoSWMM by Innovyze Inc. The software uses the fully dynamic
St. Venant’s Equation, which has a more accurate engine for simulating backwater and surcharge
conditions. The software also incorporates the use of the Manning Equation in other calculations
including upstream pipe flow conditions.
The physical hydraulic model was thus developed, as shown on Figure ES.3. The model was
populated to include rim elevations at manholes, invert elevations of pipelines, pipe sizes, pipe
slopes, pipe lengths, and outfall elevations. Tributary catchments contributing runoff to the City’s
drainage system were delineated based on 1 feet contours. The hydrologic model developed in
InfoSWMM was used to generate runoff from these tributary catchments. Inflow hydrographs from
the hydrologic model were then imported to the hydraulic model to simulate runoff entering the
piped system.
ES.6 CAPACITY EVALUATION
The City’s hydrology and hydraulic models were used to evaluate the capacity adequacy of the
existing system and for sizing future improvements.
Using the criteria described in the System Performance and Design Criteria chapter, the
hydrology and hydraulic models were used to recommend capacity improvements. The
recommended pipe improvements to mitigate existing system deficiencies and to serve future
growth are shown on Figure ES.4.
March 2023 ES-6 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 639 of 768
¤
101 Legend
Existing Modeled System
Outfalls!C
Pipes by Diameter
18" or Less
Y R
DA
D
PUEBLO ST 21" - 36"
42" or Greater
Channels!C!C!C
!C Non-Modeled System
Pipes
Uvas Creek !C !C!C !C !C !C
!C
!C
!C !C
!C
!C
18!C !C!C
!C
!C
!C Channels!C!C
18!C
!C
Roads
!C Railroads!C !C !C!C
City LimitsV!CV152152
Urban Growth Boundary
Rivers & Creeks
Waterbodies
!C
!C !C!C V!C !C !C !C 152!C !C!C !C!C !C !C!C !C !C
!C!C !C!C !C!C ¤
101
Princevalle!C!C!C !C !C !C !C
!C
!C
!C!C
!C
!C
Figure ES.3
Existing Modeled Storm!C !C
Drainage System
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 14, 2022 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig4-1_ExistingSys_041422.mxd
Agenda Item 9.3
Page 640 of 768
¤
101 Legend
Proposed Improvements
!C Outfall
Pipes
Existing Modeled System
Y R
DA
D
PUEBLO ST Outfalls!C
Pipes by Diameter
18" or Less!C!C!C
Uvas Creek !C 21" - 36"!C !C!C !C !C !C
!C
!C
!C 42" or Greater
Channels
!C
!C
!C
18!C !C!C
!C
!C
!C !C!C
18!C
!C Non-Modeled System
Pipes!C!C !C !C!CMS-5 ChannelsVNU-2
!CV15224
MS-2
152
Roads!C
RailroadsPR-3 !C !C42
PR-2
!C V!C !C !C !C 152 City Limits!C !C!C !C!C !C LM-3 Urban Growth Boundary
Rivers & Creeks
Waterbodies
!C!C !C PR-6 !C
!C!C !C!C !C!C ¤
101
Princevalle!C!C!C !C !C !C !C
!C
!C
!C!C
!C
90
NU-8
!C
!C
Figure ES.4
Capital Improvement!C !C
Program
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 15, 2022 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig6-1_CIP_Scen2_041522.mxd
Agenda Item 9.3
Page 641 of 768
ES.7 CAPITAL IMPROVEMENT PROGRAM
The Capital Improvement Program costs for the projects identified in this master plan for
mitigating existing system deficiencies and for serving anticipated future growth throughout the
City are summarized on Table ES.3, and are graphically represented on Figure ES.4. Each
improvement was assigned a uniquely coded identifier corresponding to its respective hydrologic
drainage area. The baseline costs for pipelines are shown in Table ES.2.
The estimated construction costs include the baseline costs plus 30 percent contingency
allowance to account for unforeseen events and unknown field conditions. Capital improvement
costs include the estimated construction costs plus 30 percent project-related costs (engineering
design, project administration, construction management and inspection, and legal costs).
The costs in this Storm Drainage System Master Plan were benchmarked using a 20-City national
average ENR CCI of 12,647, reflecting a date of November 2021. In total, the CIP project cost
totals approximately $34.8 million dollars.
March 2023 ES-9 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 642 of 768
Table ES.2 Unit Costs
Storm Drainage System Master Plan
City of Gilroy
Pipelines
(in)($/Lineal Foot)
24 245
27
30
36
42
48
54
60
66
72
84
90
283
302
358
414
489
545
564
622
678
866
928
Pipeline Casings
$22 per inch diameter per liner foot
3/29/2023
Note :
1. Unit costs are based on an ENR CCI Index Value
of 13,176 (March 2023).
Agenda Item 9.3
Page 643 of 768
Table ES.3 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Suggested Cost
AllocationPipeline Improvements Infrastructure Costs Cost SharingImprov.
No.Alignment Limits Baseline
Constr. Costs Constr. Costs
Estimated Capital Improv.
CostsExisting
Diameter
(in)
New/Parallel/
Replace
Existing Future
Users
(%)
Diameter Length Unit Cost Infr. Cost Existing Users Future usersUsers
(in)(ft)($/lf)($)($)($)($)(%)($)($)
Ronan Channel Drainage Area
RC-1
RC-2
RC-3
RC-4
RC-5
RC-6
RC-7
RC-8
RC-9
Sunrise Dr
Mantelli Dr
Zamzow Ct
Cohansey Ave
Murray Ave
Murray Ave
From Dream Catcher Way to Golden Sky Way
From Muir Drive to Delta Dr
18
18
-
Replacement
Replacement
New
30
24
48
48
48
48
36
48
42
400
1,250
1,200
1,450
2,800
600
302
245
489
489
489
489
358
489
414
120,601
306,506
586,990
709,280
1,369,643
293,495
1,216,516
1,675,367
62,114
121,000
307,000
587,000
710,000
1,370,000
294,000
1,217,000
1,676,000
63,000
158,000
400,000
764,000
923,000
1,781,000
383,000
1,583,000
2,179,000
82,000
206,000
520,000
100%
100%
8%
0%
0%
206,000
520,000
74,621
0
0
0
From approx. 1,250' n/o Cohansey Ave to
Cohansey Ave
From approx. 350' e/o Monterey Rd to Murray
Ave
994,000 92%
100%
91%
87%
9%
919,379
1,200,000
2,096,660
430,822
182,080
605,415
14,341
-New 1,200,000
2,316,000
498,000
0%
From Cohansey Ave to Tomkins Ct
From Tomkins Ct to Ronan Channel
-New 9%219,340
67,178
1,875,920
2,227,585
92,659
24
-
Replacement
New
13%
91%
79%
87%
No Name Uno/Las Animas From approx. 1,500' s/o Buena Vista Ave to San 3,400
3,425
150
2,058,000
2,833,000
107,000
Ave Ysidro Ave
From Las Animas Ave to approx. 500' n/o
Leavesley Rd
From approx. 220' e/o Forest St to approx. 360'
e/o Forest St
San Ysidro Ave -New 21%
13%Leavesley Rd 18 Replacement
Subtotal - Ronan Channel Drainage Area 6,345,000 8,253,000 10,732,000 5,283,303 5,448,697
Miller Slough Drainage Area
MS-1
MS-2
MS-3
MS-4
MS-5
MS-6
Wren Ave
First St
From approx. 290' n/o First St to Lawrence Dr
From approx. 180' e/o Princevalle St to Sargent St
From First St to Broadway
24
18
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
30
24
24
30
30
27
2,325
525
302
245
245
302
302
283
700,991
128,732
104,212
324,114
120,601
190,847
701,000
129,000
105,000
325,000
121,000
191,000
912,000
168,000
137,000
423,000
158,000
249,000
1,186,000
219,000
179,000
550,000
206,000
324,000
100%
100%
100%
100%
100%
100%
0%
0%
0%
0%
0%
0%
1,186,000
219,000
179,000
550,000
206,000
324,000
0
0
0
0
0
0
Sargent St
Broadway
Church St
Monterey Rd
18 425
From Sargent St to Church St 18/21
21
1,075
400From Broadway to approx. 100' s/o Howson St
From Second St to First St 18/24 675
Subtotal - Miller Slough Drainage Area 1,572,000 2,047,000 2,664,000 2,664,000 0
North Uvas Drainage Area
From approx. 3,080' w/o Santa Teresa Blvd to
approx. 360' w/o Santa Teresa Blvd
From approx. 360' w/o Santa Teresa Blvd to
Santa Teresa Blvd
From approx. 70' s/o Hecker Pass Hwy to Uvas
Creek
NU-1
NU-2
NU-3
NU-4
Hecker Pass Hwy
Hecker Pass Hwy
Santa Teresa Blvd
Westwood Dr
-New 30
30
30
24
2,825
350
302
302
302
245
851,742
105,526
776,367
104,212
852,000
106,000
777,000
105,000
1,108,000
138,000
1,441,000
180,000
0%
0%
100%
100%
100%
0%
0 1,441,000
180,000
1,315,000
0
24
24
18
Replacement
Replacement
Replacement
0
02,575
425
1,011,000
137,000
1,315,000
179,000
0%
From approx. 150' s/o Third St to Kentwood Ct 100%179,000
Agenda Item 9.3
Page 644 of 768
Table ES.3 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Suggested Cost
AllocationPipeline Improvements Infrastructure Costs Cost SharingImprov.
No.Alignment Limits Baseline
Constr. Costs Constr. Costs
Estimated Capital Improv.
CostsExisting
Diameter
(in)
New/Parallel/
Replace
Existing Future
Users
(%)
Diameter Length Unit Cost Infr. Cost Existing Users Future usersUsers
(in)(ft)($/lf)($)($)($)($)(%)($)($)
NU-5
NU-6
NU-7
NU-8
Monterey Rd
Monterey Rd
ROW
From Princevalle Channel to Victoria Dr -
42
-
New
Replacement
New
90
90
90
90
775
2,175
975
928
928
928
928
718,859
2,017,443
904,371
927,560
719,000 935,000 1,216,000 100%
100%
100%
100%
0%
0%
0%
0%
1,216,000 0
From Victoria Dr to approx. 950' n/o Farman Ln 2,018,000
905,000
928,000
2,624,000
1,177,000
1,207,000
3,412,000
1,531,000
1,570,000
3,412,000
1,531,000
1,570,000
0
0
0
From Monterey Rd to approx. 970' n/o Uvas
Creek
ROW From approx. 970' n/o Uvas Creek to Uvas Creek -New 1,000
Subtotal - North Uvas Drainage Area 6,410,000 8,337,000 10,844,000 7,908,000 2,936,000
South Uvas Drainage Area
From Carnoustie Ct to approx. 380' nw/o
Carnoustie CtSU-1 St Andrews Cir 18 Replacement 36 375 358 134,175 135,000 176,000 229,000 100%0%229,000 0
Subtotal - South Uvas Drainage Area 135,000 176,000 229,000 229,000 0
Princevalle Drainage Area
PR-1
PR-2
PR-3
PR-4
PR-5
PR-6
PR-7
PR-8
PR-9
PR-10
PR-11
PR-12
PR-13
Third St
Third St
From Santa Paula Dr to Wren Ave 27
27
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
New
30
42
48
48
48
48
48
30
54
24
24
48
48
825
675
302
414
489
489
489
489
489
302
545
245
245
489
489
248,739
279,515
97,832
249,000
280,000
98,000
324,000
364,000
128,000
605,000
431,000
255,000
796,000
491,000
870,000
264,000
201,000
1,575,000
494,000
422,000
474,000
167,000
787,000
561,000
332,000
1,035,000
639,000
1,131,000
344,000
262,000
2,048,000
643,000
100%
100%
100%
100%
100%
100%
100%
100%
100%
84%
0%
0%
0%
0%
0%
0%
0%
0%
0%
16%
11%
0%
0%
422,000
474,000
167,000
787,000
561,000
332,000
1,035,000
639,000
1,131,000
288,575
234,103
2,048,000
643,000
0
From Wren Ave to approx. 170' e/o Santa
Theresa Dr
From approx. 170' e/o Santa Theresa Dr to Santa
Theresa Dr
0
Third St 27 200 0
Santa Theresa Dr
ROW
From Third St to approx. 300' s/o Fourth St
From Santa Theresa Dr to Miller Ave
From approx. 300' s/o Fourth St to Fifth St
From Miller Ave to Princevalle St
From Third St to Fifth St
27/30
30
950 464,700
330,182
195,663
611,448
376,877
668,183
202,294
153,253
1,210,667
379,098
465,000
331,000
196,000
612,000
377,000
669,000
203,000
154,000
1,211,000
380,000
0
675 0
Miller Ave
Fifth St
30 400 0
30 1,250
1,250
1,225
825
0
Princevalle St
Princevalle St
Alexander St
Banes Ln
18 0
From Fifth St to Seventh St 42 0
55,425
27,897
0
From Tenth St to Banes Ln 18
From Alexander St to Automall Pkwy
From approx. 380' n/o 8th St to Angra Way
From Angra Way to Princevalle Channel
18 625 89%
Monterey Rd
Monterey Rd
-2,475
775
100%
100%42 Replacement 0
Subtotal - Princevalle Drainage Area 5,225,000 6,798,000 8,845,000 8,761,678 83,322
Agenda Item 9.3
Page 645 of 768
Table ES.3 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Suggested Cost
AllocationPipeline Improvements Infrastructure Costs Cost SharingImprov.
No.Alignment Limits Baseline
Constr. Costs Constr. Costs
Estimated Capital Improv.
CostsExisting
Diameter
(in)
New/Parallel/
Replace
Existing Future
Users
(%)
Diameter Length Unit Cost Infr. Cost Existing Users Future usersUsers
(in)(ft)($/lf)($)($)($)($)(%)($)($)
Lower Miller Slough Drainage Area
LM-1
LM-2
LM-3
LM-4
LM-5
LM-6
Fourth St
Monterey Rd
Monterey Rd
Monterey Rd
ROW
From Eigleberry St to Monterey Rd
From Fourth St to Sixth St
18
27
27
33
18
24
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
30
36
42
42
24
36
400
1,250
425
302
358
414
414
245
358
120,601
447,248
175,991
320,924
275,855
465,138
121,000
448,000
176,000
321,000
276,000
466,000
158,000
583,000
229,000
418,000
359,000
606,000
206,000
758,000
298,000
544,000
467,000
788,000
100%
100%
100%
100%
100%
100%
0%
0%
0%
0%
0%
0%
206,000
758,000
298,000
544,000
467,000
788,000
0
0
0
0
0
0
From Sixth St to Hornlein Ct
From Hornlein Ct to approx. 240' n/o Eighth St
From Rosanna St to Monterey Rd
From Sixth St to Eighth St
775
1,125
1,300Alexander St
Subtotal - Lower Miller Slough Drainage Area 1,808,000 2,353,000 3,061,000 3,061,000 0
Total Costs
Subtotal - Ronan Channel Drainage Area
Subtotal - Miller Slough Drainage Area
Subtotal - North Uvas Drainage Area
Subtotal - South Uvas Drainage Area
Subtotal - Princevalle Drainage Area
Subtotal - Lower Miller Slough Drainage Area
6,345,000 8,253,000 10,732,000
1,572,000 2,047,000 2,664,000
6,410,000 8,337,000 10,844,000
5,283,303
2,664,000
7,908,000
229,000
5,448,697
0
2,936,000
135,000 176,000 229,000 0
83,322
0
5,225,000 6,798,000 8,845,000
1,808,000 2,353,000 3,061,000
8,761,678
3,061,000
Total Improvement Costs 21,495,000 27,964,000 36,375,000 27,906,981 8,468,019
3/29/2023
Notes:
1. Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,176 for March 2023
2. Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.
3. Estimated construction cost plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal costs.
Agenda Item 9.3
Page 646 of 768
2023City of Gilroy
CHAPTER 1 - INTRODUCTION
This chapter provides a brief background of the City of Gilroy’s (City) Storm Drainage system, the
need for this master plan, and the objectives of the study. Abbreviations, and definitions are also
provided in this chapter.
1.1 BACKGROUND
The City of Gilroy is located approximately 32 miles southeast of the City of San Jose, 8 miles
southeast of Morgan Hill, 25 miles east of the City of Santa Cruz, and 16 miles northwest of City
of Hollister (Figure 1.1). The City provides storm drainage services to approximately 17,000
residential, commercial, industrial, and institutional establishments. The City currently owns and
operates more than 132 miles of storm drainage pipelines, with up to 84-inch pipe sizes.
In 2004, the City of Gilroy developed a Storm Drainage System Master Plan that identified
capacity deficiencies in the storm drainage system and recommended improvements to alleviate
deficiencies and serve future developments in the Gilroy Planning Area.
Recognizing the importance of planning, developing, and financing system facilities to provide
enhanced stormwater drainage system service to existing customers and for servicing anticipated
growth within the Gilroy Planning Area, the City initiated updating elements of the 2004 Storm
Drainage System Master Plan, to reflect current land use conditions and General Plan updates.
1.2 SCOPE OF WORK
City Council approved Akel Engineering Group Inc. to prepare this 2022 Storm Drainage System
Master Plan (SDSMP) and a concurrent Water System Master Plan and Sewer System Master
Plan. The 2022 SDSMP evaluates the City’s storm drainage system and recommends capacity
improvements necessary to service the needs of existing users and for servicing the future growth
of the City. This 2022 SDSMP is intended to serve as a tool for planning and phasing the
construction of future storm drainage infrastructure for the projected buildout of the City’s service
area. The planning area and horizon for this master plan is based on the City’s 2040 General
Plan. Should planning conditions change, and depending on their magnitude, adjustments to the
master plan recommendations might be necessary.
The master plan included the following tasks:
•
•
•
•
Summarize the City’s existing stormwater system facilities.
Document growth planning assumptions and known future developments.
Update the stormwater system performance criteria and design storm event.
Develop new hydrologic and hydraulic models.
March 2023 1-1 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 647 of 768
Calero
Reservoir
Anderson
Reservoir£¤
101
Morgan Hill
!(
Coyote
Reservoir
Uvas
Reservoir £¤
101
UV152 Gilroy
UV152£¤
101
UV152
UV25
WatsonvilleUV!(UV152
129UV
1 £¤
101UVUV129129
Legend Figure 1.1
Regional Location Map!( Cities
Study Area
Elevation (ft)
9 - 50
1,001 - 2,000
2,001 - 3,000
3,001 - 3,792 Storm Drainage System Master Plan
City of Gilroy
City Limits 51 - 100
Urban Growth Boundary
Highway
101 - 250
251 - 500
501 - 1,000
Waterbodies 5RailroadsGIS
0 0.5 1 2Updated: September 21, 2020 Miles
Flie Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig1-1RLMap_092120.mxd
Agenda Item 9.3
Page 648 of 768
•
•
Evaluate the storm drainage facilities to address hydraulic capacity requirements from
existing and projected developments.
Recommend a capital improvement program (CIP) with an opinion of probable
construction costs.
•
•
Perform a cost allocation analysis for cost sharing purposes.
Develop a 2023 Storm Drainage System Master Plan Report.
1.3 INTEGRATED APPROACH TO MASTER PLANNING
This City implemented an integrated master planning approach and contracted the services of
Akel Engineering Group Inc. to prepare the following documents:
•
•
•
2023 Water System Master Plan
2023 Sewer System Master Plan
2023 Storm Drainage System Master Plan
While each of these reports is published as a standalone document, it has been coordinated for
consistency with the City’s 2040 General Plan. Additionally, each document has been cross
referenced to reflect relevant analysis results with the other documents.
1.4 PREVIOUS MASTER PLANS
The City’s most recent storm drainage master plan was completed in 2004. This master plan
included evaluation of servicing growth to the planning area, evaluating the existing system, and
identifying storm drainage improvements required to serve future growth. Additionally, the 2004
master plan included the development of the hydrologic and hydraulic models, which were used
for evaluating the storm drainage system. Improvements were recommended for servicing existing
and future growth areas, and a corresponding Capital Improvement Program was developed to
quantify the costs associated with each improvement.
1.5 RELEVANT REPORTS
The City has completed several special studies intended to evaluate localized growth. These
reports were referenced and used during the capacity analysis. The following lists relevant reports
that were used in the completion of this master plan, as well as a brief description of each
document:
•City of Gilroy 2040 General Plan, November 2020 (2040 GP). The City’s 2040 General
Plan provides future land use planning, and growth assumptions for the Planning Area.
Additionally, this report establishes the planning horizon for improvements in this master
plan.
March 2023 1-3 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 649 of 768
•City of Gilroy Storm Drainage System Master Plan, May 2004 (2004 SDSMP). This
report documents the planning and performance criteria, evaluates the storm drainage
system, recommends improvements, and provides an estimate of costs.
1.6 REPORT ORGANIZATION
The Storm Drainage System Master Plan report contains the following chapters:
Chapter 1 – Introduction. This chapter provides a brief background of the City’s Storm Drainage
system, the need for this master plan, and the objectives of the study. Unit conversions,
abbreviations, and definitions are also provided in this chapter.
Chapter 2 – Planning Area Characteristics. This chapter presents a discussion of the planning
area characteristics affecting the hydrologic and hydraulic analysis of this master plan. These
characteristics include soil, topography, floodplains, and land use.
Chapter 3 – System Performance and Design Criteria. This chapter presents the City’s
planning and design criteria that were used for evaluating hydrologic and hydraulic systems within
the City’s drainage watershed.
Chapter 4 –Existing Facilities Model Development. This chapter defines the hydrologic
delineation of storm drainage areas, routing to their respective receiving facilities, and includes the
hydrologic model development. Additionally, this chapter includes an overview of the storm
drainage system, and the hydraulic model development.
Chapter 5 – Evaluation and Proposed Improvements. This chapter presents a summary of the
storm drainage system evaluation and identifies improvements needed to mitigate existing
deficiencies, as well as improvements needed to expand the system and service future growth.
Chapter 6 – Capital Improvement Program. This chapter provides a summary of the
recommended storm drainage system improvements intended to mitigate existing capacity
deficiencies and for accommodating anticipated future growth. This chapter also presents the cost
criteria and methodologies for developing the Capital Improvement Program (CIP). Finally, a cost
allocation analysis, usually used for cost sharing purposes, is also included.
1.7 ACKNOWLEDGEMENTS
Obtaining the necessary information to successfully complete the analysis presented in this
report, and developing the long-term strategy for mitigating the existing system deficiencies and
for accommodating future growth, was accomplished with the strong commitment and very active
input from dedicated team members including:
•
•
•
Daryl Jordan, P.E.; Director of Public Works
Gary Heap, P.E.; City Engineer
Jorge Duran, P.E.; Senior City Engineer
March 2023 1-4 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 650 of 768
•Matt Jones, Deputy Public Works Director
1.8 UNIT CONVERSIONS AND ABBREVIATIONS
Engineering units were used in reporting flow rates and volumes pertaining to the design and
operation of various components of the storm drainage system. Where it was necessary to report
values in smaller or large quantities, different sets of units were used to describe the same
parameter. Values reported in one set of units can be converted to another set of units by
applying a multiplication factor. A list of multiplication factors for units used in this report are
shown on Table 1.1.
Various abbreviations and acronyms were also used in this report to represent relevant storm
drainage system terminologies and engineering units. A list of abbreviations and acronyms is
included in Table 1.2.
1.9 GEOGRAPHIC INFORMATION SYSTEMS
This master planning effort made extensive use of Geographic Information Systems (GIS)
technology, for completing the following tasks:
•
•
•
Developing the physical characteristics of the hydraulic model.
Delineating stormwater tributary areas, and outlining watershed areas.
Extracting ground elevations along the storm drainage system from available contour
maps and digital elevation models.
•Generating maps and exhibits used in this master plan.
March 2023 1-5 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 651 of 768
Table 1.1 Unit Conversions
Storm Drainage System Master Plan
City of Gilroy
Volume Unit Calculations
To Convert From:To:
gallons
cubic feet
million gallons
gallons
Multiply by:
325,857
43,560
0.3259
7.481
2.296 x 10-5
acre feet
acre feet
acre feet
cubic feet
cubic feet acre feet
7.481 x 10-6
0.1337
cubic feet
gallons
million gallons
cubic feet
3.069 x 10-6gallonsacre feet
1 x 10-6
1,000,000
133,672
3.069
gallons million gallons
gallons
cubic feet
acre feet
million gallons
million gallons
million gallons
Flow Rate Calculations
To Convert From:To:Multiply By:
8.93 x 10-4ac-ft/yr mgd
1.381 x 10-3
0.621
ac-ft/yr
ac-ft/yr
ac-ft/yr
cfs
cfs
cfs
cfs
gpm
gpd
mgd
gpm
ac-ft/yr
gpd
892.7
0.646
448.8
724
cfs 646300
1 x 10-6gpdmgd
1.547 x 10-6
6.944 x 10-4
1.12 x 10-3
1.44 x 10-3
gpd
gpd
gpd
gpm
cfs
gpm
ac-ft/yr
mgd
2.228 x 10-3
1.61
gpm
gpm
gpm
mgd
mgd
mgd
mgd
cfs
ac-ft/yr
gpd
cfs
gpm
1,440
1.547
694.4
1,120ac-ft/yr
gpd 1,000,000
9/16/2020
Agenda Item 9.3
Page 652 of 768
Table 1.2 Abbreviations and Acronyms
Storm Drainage System Master Plan
City of Gilroy
Abbreviation Expansion Abbreviation Expansion
2016 Storm Drainage System
Master Plan2016 SDSMP
10Yr-24Hr
100Yr-24Hr
AC
ft
fps
Feet
10-Year 24-Hour
100-Year 24-Hour
Acre
Feet per Second
Geographic Information Systems
High Density Polyethylene Pipe
Inch
GIS
HDPE
inACPAsbestos Cement Pipe
Akel Engineering Group, Inc.Akel in/hr
LF
Inch per Hour
California Department of
TransportationCaltrans
City
Linear Feet
City of Gilroy mi Miles
National Resource Conservation
Service
National Oceanic and Atmospheric
Administration
CCI Construction Cost Index
Cubic Feet per Second
Cast Iron Pipe
NRCS
NOAA
PVC
cfs
CI Polyvinyl Chloride Pipe
CIP Capital Improvement Program
County of Santa Clara
Corrugated Metal Pipe
Ductile Iron Pipe
RCP Reinforced Concrete Pipe
Right of WayCounty
CMP
ROW
SCS Soil Conservation Service
Sphere of InfluenceDIPSOI
DDF Depth Duration Frequency
Engineering News Record
Environmental Protection Agency
Department of Finance
SSURGO
SWMM
UGB
UWMP
VCP
Soil Survey Geographic database
Stormwater Management Model
Urban Growth Boundary
Urban Water Management Plan
ENR
EPA
DOF
Federal Emergency Management
AgencyFEMA Verified Clay Pipe
9/16/2020
Agenda Item 9.3
Page 653 of 768
2023City of Gilroy
CHAPTER 2 – PLANNING AREA CHARACTERISTICS
This chapter presents a discussion of the planning area characteristics affecting the hydrologic
and hydraulic analysis of this master plan. These characteristics include soil, topography,
floodplains, and land use.
2.1 STUDY AREA DESCRIPTION
The City of Gilroy is located in Santa Clara County near the west coast of California, south of City
of San Francisco. The City of Gilroy lies within the seismically active region of San Francisco Bay.
The City of Gilroy lies in the southern portion of the Santa Clara County and is the most southern
City located within the county. The City is located approximately 32 miles southeast of the City of
San Jose, 8 miles southeast of Morgan Hill, 25 miles east of City of Santa Cruz, and 16 miles
northwest of City of Hollister. The City limits currently encompass 16.5 square miles, with an
approximate population of 57,000 residents, according to Department of Finance as of January
2021. Figure 1.1 displays the City’s location.
The City’s service area is generally bound to the north by Fitzgerald Avenue, to the northeast by
San Ysidro Avenue, to the southeast by Camino Arroyo, to the west by Burchell Road and
Rancho Vista Drive, and to the south by Carnadero Avenue. U.S. Route 101 divides the City in a
southeast to northwest direction and the California State Route 152 (Hecker Pass Hwy) runs east-
west direction in the northern half of the City. The topography is generally flat in the middle of the
service area, with increasing slopes in the east and west side of the City due to the Santa Cruz
Mountains to the west and the Diablo Range to the east. Figure 2.1 displays the planning area
showing City limits, the Urban Growth Boundary (UGB) of the City and Planning Area / Sphere of
Influence (SOI).
The City operates and maintains a storm drainage system that covers the area within the City
Limits. Currently, stormwater runoff discharges to the Uvas Creek, Ronan Channel, Miller Slough
Channel, Princevalle Channel and Lower Miller Slough Channel, as describe in the following
section.
2.2 WATERSHEDS AND DRAINAGE AREAS
The City of Gilroy maintains a rich diversity of land use types, which contribute to a varying degree
of stormwater runoff containment needs. Several creeks, a vast array of agricultural lands, small
pockets of development, and the City itself comprises the wide array of runoff generation and
conveyance within the planning area.
March 2023 2-1 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 654 of 768
¤
101
Coyote
Reservoir
UV UV152152
City of Gilroy
£¤
101 UV152
£¤
101
V25
Legend Figure 2.1
Planning AreaCity Limits General Plan Area
RoadsCity Limits Area
Storm Drainage System Master Plan
City of Gilroy
Specific Plan Areas
Urban Service Area
Urban Growth Boundary
Sphere of Influence Boundary
Highways
Railroads
5Rivers & Creeks
Waterbodies GIS
0 0.5 1 2
Updated: April 15, 2022 Miles
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Agenda Item 9.3
Page 655 of 768
2.2.1 Watersheds
The City has multiple major watersheds within the Urban Growth Boundary that collect and
convey stormwater runoff, and are as follows: Uvas Creek, Llagas Creek, and Pajaro River
(Figure 2.2). The following are brief descriptions of the three watersheds:
•Uvas Creek Watershed – The portion of the Uvas Creek Watershed within the City limits is
generally defined as the area bounded by Rancho Vista Drive to the west and Santa
Teresa Boulevard to the east, with the northern and southern boundaries approximately
represented by Uvas Creek and Santa Cruz Mountain respectively.
•Llagas Creek Watershed – The portion of the Lower Coyote Creek Watershed within the
City limits is generally bounded by Olea Court to the west and Llagas Creek to the east,
with the northern and southern boundaries approximately represented by Fitzgerald
Avenue and Luchessa Avenue respectively.
•Pajaro River Watershed – The Pajaro River Watershed within the City limits is generally
defined as the area bounded by Uvas Creek to the west and Llagas Creek to the east, with
the northern and southern boundaries approximately represented by Luchessa Avenue
and Southside Drive respectively.
2.2.2 Drainage Areas
Watersheds are typically comprised of smaller drainage areas defined by topographical features.
Additionally, these drainage areas may comprise multiple soil types as defined by Natural
Resources Conservation Service (NRCS). The City’s storm drainage system consists of a series
of conveyance networks. These networks have different means of disposing of stormwater runoff,
which include outfall points to Uvas Creek or Llagas Creek, or being conveyed to the canals and
sloughs throughout the City.
2.3 FLOODPLAINS
Floodplains are important for delineating the extent of water-level rise during major floods.
Typically, floodplains are estimated for the historic 100-Year and 500-Year flood. Most of the
floodplains for the City are located southeast boundary of the City limits, as shown on Figure 2.3.
The Federal Emergency Management Agency (FEMA) produces Flood Insurance Rate Maps that
show areas subject to flooding during major storm events. The flood risk information shown on
these maps is based on historical data, including meteorological, hydrological, and hydraulic data
for the specified area. The map creation is a result of the 1968 National Flood Insurance Program,
aimed at reducing or preventing property owner losses due to flooding by allowing premiums to be
paid for those in need of protection.
March 2023 2-3 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 656 of 768
£¤
101 Legend
Existing Modeled System
Llagas Creek
Watershed
Outfalls!C
Pipes by Diameter
18" or Less
Y R
DA
D
PUEBLO ST 21" - 36"
Uvas Creek
Watershed
42" or Greater
Channels!C!C!C!C !C !C Non-Modeled System
Pipes
Uvas Creek !C !C !C !C !C
!C Pajaro River
Watershed
!C
!C18!C
!C
!C !C !C
!C Channels!C!C!C
18!C
!C Watershed Boundaries
Llagas Creek
Pajaro River
Uvas Creek
!C!C !C !C!C !CUV!CUV152152
!C
Roads!C !C!C UV!C Railroads!C !C !C 152!C !C!C !C!C !C City Limits!C!C !C !C
!C!C !C!C Urban Growth Boundary
Rivers & Creeks
Waterbodies
!C!C £¤
101
Princevalle!C!C!C !C !C !C !C
!C
!C
!C!C
!C
!C
Figure 2.2
Waterways!C !C
and Watersheds
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 14, 2022 Mile
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Agenda Item 9.3
Page 657 of 768
¤
101 Legend
FEMA 100 Year Flood Zones
0.2% Annual Chance Flood Hazard
1% Annual Chance Flood Hazard
Regulatory Floodway
Area of Minimal Flood Hazard
Area with Reduced Risk Due to Levee
Area of undetermined Flood Hazard
Existing Modeled System
Y R
DA
D
PUEBLO ST
!C!C!C
!C Outfalls
!C
!C
Uvas Creek !C !C!C !C !C !C Pipes by Diameter
18" or Less
21" - 36"
!C
!C !C
!C
!C
18!C
!C
!C !C !C
!C !C!C
18!C
42" or Greater
Channels
!C
!C!C Non-Modeled System
Pipes
!C !C!C
V !CUV152152 Channels
!C Roads
!C !C Railroads!C UV!C !C!C !C !C 152 City Limits!C!C !C!C !C !C Urban Growth Boundary!C !C !C
!C Rivers & Creeks
Waterbodies
!C !C!C !C!C £¤
101
Princevalle!C!C!C !C !C !C !C
!C
!C
!C!C
!C
!C
Figure 2.3
FEMA 100 Year!C !C
Flood Zones
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 14, 2022 Mile
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Agenda Item 9.3
Page 658 of 768
2.4 EXISTING SERVICE AREAS AND LAND USE
The City’s storm drainage system services residential and non-residential lands within the City
limits, as summarized on Table 2.1, and shown graphically on Figure 2.4. Areas within the City
limit include 4,197 acres of developed lands and 4,905 acres of undeveloped lands.
At ultimate development of the General Plan, the City’s storm drainage system is anticipated to
service approximately 3,045 acres of residential land use, 4,750 acres of non-residential land use,
and 2,477 acres of open space land use, for a total of 10,272 acres inside the City’s Urban
Growth Boundary (Table 2.1). The land use designations utilized in this master plan are
consistent with the Land Use Element of the City’s 2040 General Plan received from the City’s
planning division, and shown on Figure 2.5.
2.5 HISTORICAL AND PROJECTED POPULATION
According to California Department of Finance (DOF) population estimates, the 2021 City
population is approximately 57,000 people. From 2015 to present, the City’s service area has
observed an average annual growth rate of approximately 0.7%. This 2022 SDSMP is consistent
with the City’s 2020 Urban Water Management Plans (UWMP’s) annual growth rate factor of
1.5%. The current and projected service area population is summarized in Table 2.2.
March 2023 2-6 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 659 of 768
¤
101
Legend
Existing Land Use
Low Density Residentia
Medium Density Residential
High Density Residential
Neighborhood District
Public/Quasi-Public Facility
Educational Facility
Professional Office
General Services Commercial
Visitor-Serving Commercial
Industrial
Open Space
Park and Recreation Facility
VacantV152
UV City Limits152
Roads
Railroads
Rivers & Creeks
Waterbodies
UV25£¤
101
Figure 2.4
Existing Land Use
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.5 1 2
Updated: April 15, 2022 Miles
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Agenda Item 9.3
Page 660 of 768
¤
101
Legend
Planning Area/Sphere of Influence
Urban Growth Boundary
City Limits
General Plan Land Use
Hillside Residential
Low Density Residential
Medium Density Residential
High Density Residential
General Services Commercial
City Gateway District
Visitor Serving Commercial
General Industrial
Employment Center
Industrial ParkV152
UV Public and Quasi-Public Facility
Neighborhood District
Mixed Use
152
Rural County
Open Space
Park and Recreation Facility
Specific Plan Areas
Downtown
Glen Loma Ranch
Hecker Pass
Roads
Railroads
Rivers & CreeksUV25Waterbodies£¤
101
Figure 2.5
2040 General Plan
Land Use
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.5 1 2
Updated: April 15, 2022 Miles
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Agenda Item 9.3
Page 661 of 768
Table 2.1 Existing and Future Land Use
Storm Drainage System Master Plan
City of Gilroy
Existing Development
Within City Limits
Future Development
Total
Development
Subtotal
Existing
Within City Limits Subtotal
Future
Development
General Plan Land Use
Classification
Existing Land Use
Classification
Urban Growth
BoundaryDevelopment -
UnchangedExisting Lands -
Redeveloping
New Lands -NewExistingRedevelopment Development
(acre)(acre)(acre)(acre)(acre)(acre)(acre)(acre)
Residential
Rural Residential
Hillside Residential
-0 0 0 0 0
344
45
4
0
8
0 0
Hillside Residential 444 -1 442
1,583
58
112
122
177
18
464
211
183
36
907
Low Density Residential
Medium Density Residential
High Density Residential
Low Density Residential
Medium Density Residential
High Density Residential
Subtotal - Residential
1,704
100
-121
-42
44
2
1,794
240
249 -182
-346
67 15
408
3 104
2,496 2,151 429 58 895 3,045
Non-Residential
Visitor Serving Commercial
General Services Commercial
Visitor Serving Commercial 99
524
1
-67
-91
0
32
432
1
176
106
0
0
55
0
0
44
0
176
205
0
208
637
1
General Services Commercial
Professional Office
General Industrial General Industrial 320
56
12
596
94
0
-71
-12
-5
249
44
7
213
0
255
0
389
0
856
0
1,105
44Campus Industrial
Educational Facility
Public/Quasi-Public Facility
Neighborhood District
City Gateway District
Educational Facility 1 0 0 1 8
Public/Quasi-Public Facility -44
-94
0
552
0
152
38
102
22
7
28
336
0
281
395
27
833
395
27
Neighborhood District
-0 20
Downtown Specific Plan Area
Mixed Use Corridor High
Hecker Pass Special Use District
Glen Loma Ranch
-0 0 0 57 32
7
0 89 89
-0 0 0 25 0 33 33
-0 0 0 328
103
43
88
237
40
30
876
0 416
341
83
416
341
83
-0 0 0 0
Industrial Park -0 0 0 0
Employment Center -0 0 0 279
1,541
222
1,017
530
3,434
530
4,750Subtotal - Non-Residential 1,701 -384 1,317
Other
Agriculture
Park and Recreation Facility
Vacant
-
Park and Recreation Facility
Vacant
0 0 0
995
0
0
0
0
66
0
88
0
0
154
0
0
1,232
2,391
1,282
0
-238
-2,391
-1,030
0
1,149
000
Open Space Open Space
-
253
0
0 1,041
0
4 1,045
30
1,298
30Rural County 28
28
3
Subtotal - Other 4,905 -3,658 1,247 1,107 95 1,230 2,477
Total
Total Developed Area 9,102 -4,388 4,714 1,997 2,391 1,170 5,558 10,272
3/10/2022
Notes:
1. Source: City of Gilroy General Plan Alternatives Report, Public Review Draft July 2019.
2. Specific Plan land use types (Downtown, Hecker Pass, Glen Loma) are comprised of multiple land use types. As such, existing land use acreages reflect existing Specific Plan development under current existing land use designations.
Agenda Item 9.3
Page 662 of 768
Table 2.2 Historical and Projected Population
Storm Drainage System Master Plan
City of Gilroy
Annual GrowthYearPopulation1,2
(%)
Historical
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
41,464
42,436
43,144
43,866
45,026
45,782
46,446
47,047
48,353
48,627
48,821
49,622
50,716
52,475
53,325
54,233
54,849
55,811
56,030
56,635
56,704
-
2.3%
1.7%
1.7%
2.6%
1.7%
1.5%
1.3%
2.8%
0.6%
0.4%
1.6%
2.2%
3.5%
1.6%
1.7%
1.1%
1.8%
0.4%
1.1%
0.1%
Projected
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
57,555
58,418
59,294
60,184
61,086
62,003
62,933
63,877
64,835
65,807
66,794
67,796
68,813
69,845
70,893
71,957
73,036
74,131
75,243
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
1.5%
76,3722040 1.5%
8/31/2021
Notes:
1. Historical populations extracted from California Department of Finance, Population Estimates E-4.
2. Projected population assuming medium annual growth rate of 1.5% per the City of Gilroy 2020 Urban Water Management Plan.
Agenda Item 9.3
Page 663 of 768
2022City of Gilroy
CHAPTER 3 – SYSTEM PERFORMANCE AND DESIGN CRITERIA
This chapter presents the City’s planning and design criteria that were used for evaluating
hydrologic and hydraulic systems within the City’s drainage watershed.
3.1 HYDROLOGIC CRITERIA
Hydrologic criteria are developed to characterize the flood routing of rainfall runoff in a defined
drainage system. Akel Engineering Group obtained the services of Kasraie Consulting to review
the hydrology modeling approach, applied rainfall depths and distributions, sub-catchment
delineations, model runoff, and outflow hydrographs of this project. The hydrology sub-catchments
review is shown graphically in Appendix A. This section discusses the precipitation
characteristics, the design storms used in this master plan, and soil imperviousness.
3.1.1 Precipitation Characteristics
A dominating factor in the generation of rainfall in California is the oscillation of the semi-
permanent high pressure area of the north Pacific Ocean. This high pressure center moves north
in the summer and south in the winter, adjusting the flow of moisture into California. In the winter,
when the high pressure center moves further south, moisture can move south and bring
widespread rainfall.
In certain instances when circulation patterns allow for subtropical moisture to enter California
from a southwesterly direction, rainfall amounts can be quite heavy, and can result in widespread
flooding. The City receives an average 20.5 inches of total precipitation per year. The City’s wet
weather season typically starts in November and ends in April.
3.1.2 Design Storms
Design storms are typically defined by three important features: depth, duration and frequency.
•Depth. The depth of the storm identifies the amount of precipitation occurring during a
specific time interval.
This master plan uses the precipitation depth-duration-frequency equations included in the Santa
Clara County Drainage Manual, and converted to reflect City of Gilroy specific precipitation
documented on Table 3.1. The depth-duration-frequency values reflect rainfall events specific to
the City and lists precipitations, in inches and inches per hour, for return intervals up to 100 years.
For comparison purposes, Table 3.2 lists the difference in precipitation between the 2004 Master
Plan, County Drainage Manual and NOAA Atlas 14 Volume 6 Version 2. While 2004 Master Plan
and Santa Clara Drainage Manual values are relatively close, NOAA precipitation values have
March 2023 3-1 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 664 of 768
Table 3.1 Precipitation Depth-Duration-Frequency
Storm Drainage System Master Plan
City of Gilroy
2-Year 5-Year 10-Year
(in/hr)
25-Year
(in/hr)
100-Year
(in/hr)Duration
5-min
10-min
15-min
30-min
1-hr
(in)(in/hr)
1.78
(in)(in/hr)
2.50
(in)(in)(in)
0.15 0.21 0.24 2.93
1.99
1.57
1.06
0.73
0.54
0.46
0.35
0.24
0.16
0.29 3.43
2.33
1.85
1.25
0.85
0.62
0.53
0.40
0.29
0.20
0.34 4.12
2.79
2.26
1.51
1.02
0.74
0.63
0.48
0.35
0.21
0.24
0.33
0.48
0.73
0.94
1.36
1.83
2.29
1.24
0.97
0.67
0.48
0.36
0.31
0.23
0.15
0.10
0.29
0.33
0.45
0.63
0.95
1.22
1.80
2.51
3.27
1.71
1.33
0.91
0.63
0.47
0.41
0.30
0.21
0.14
0.33
0.39
0.53
0.73
1.09
1.39
2.08
2.94
3.91
0.39
0.46
0.62
0.85
1.25
1.60
2.40
3.44
4.69
0.47
0.56
0.76
1.02
1.48
1.88
2.85
4.15
5.81
2-hr
3-hr
6-hr
12-hr
24-hr 0.24
10/20/2021
Note:
1. Source: Santa Clara County Drainage Manual.
Agenda Item 9.3
Page 665 of 768
Table 3.2 Precipitation Depth-Duration-Frequency Comparison
Storm Drainage System Master Plan
City of Gilroy
2004 Master Plan Santa Clara County Drainage Manual NOAA Atlas 141
Duration
10-Year 100-Year 10-Year 100-Year 10-Year 100-Year
(in)(in/hr)(in)(in/hr)(in)(in/hr)(in)(in/hr)(in)(in/hr)(in)(in/hr)
5-min
10-min
15-min
30-min
1-hr
0.18
0.26
0.32
0.47
0.69
1.01
1.26
1.84
2.69
3.93
2.16 0.27
0.39
0.49
0.71
1.04
1.52
1.89
2.77
4.05
5.92
3.24 0.24
0.33
0.39
0.53
0.73
1.09
1.39
2.08
2.94
3.91
2.93 0.34
0.47
0.56
0.76
1.02
1.48
1.88
2.85
4.15
5.81
4.12 0.26
0.37
0.45
0.62
0.87
1.33
1.68
2.39
3.40
4.69
3.10 0.41
0.59
0.72
0.99
1.40
2.14
2.71
3.86
5.46
7.51
4.97
1.56
1.28
0.94
0.69
0.51
0.42
0.31
0.22
0.16
2.34
1.96
1.42
1.04
0.76
0.63
0.46
0.34
0.25
1.99
1.57
1.06
0.73
0.54
0.46
0.35
0.24
0.16
2.79
2.26
1.51
1.02
0.74
0.63
0.48
0.35
0.24
2.22
1.79
1.24
0.87
0.67
0.56
0.40
0.28
0.20
3.56
2.87
1.98
1.40
1.07
0.90
0.64
0.46
2-hr
3-hr
6-hr
12-hr
24-hr 0.31
10/20/2021
Note:
1. Source: NOAA Atlas 14 Volume 6 Version 2 for Gilroy.
Agenda Item 9.3
Page 666 of 768
been consistently increasing over the years. City staff selected to maintain consistency with Santa
Clara Drainage Manual.
•Duration. The duration of the storm can be little as 5-minutes and as high as 24-hours as
documented on Table 3.1. This storm drainage master plan uses 24-hours as the
duration, and the distribution is based on NOAA Atlas 14 Balanced Centered Hyetograph.
The balance centered hyetograph provides a design storm with the peak intensity
occurring during the middle of the day (Figure 3.1).
•Frequency. The frequency of the storm is the recurrence interval at which the storm may
occur at a given area.
3.1.3 Design Storm Events
The design storms used in this evaluation, and which are specific to the City, are listed on Table
3.3. The values used in evaluating the storm drainage system are as follows:
•10-year 24-hour. This design storm is used to evaluate pipeline conveyance facilities as
well as to size future ones. This storm was quantified at 3.91 inches.
•100-year 24-hour. This design storm is used in evaluating City street performance for
conveying stormwater flows, while allowing up to one foot of street flooding; this storm was
quantified at 5.81 inches.
3.1.4 Soil Imperviousness
In determining the quantity of rainfall runoff generated from a given land use type, three factors
dictate the volume of water that enters the storm drainage system: effective imperviousness,
ineffective imperviousness, and effective pervious area.
•
•
•
Effective Impervious. An effective impervious area is the percentage of impervious area
that generates stormwater runoff entering the storm drainage system. The effective
impervious percentages are based on land uses identified in the 2040 General Plan, and
are included in Table 3.4.
Ineffective Impervious. An ineffective impervious area is land that has no flow path, or
the flow path results in delayed timing of the runoff, to the storm drainage system. These
areas are typically noted as residential backyards, pools, or dense shrub landscaping. The
values for these areas are shown on Table 3.4.
Effective Pervious. Effective pervious areas contribute to runoff based on the National
Resource Conservation Service (NRCS) Soil Classification Group, and the subsequent
SCS Curve Number. The Curve Number is listed by soil group in Table 3.4.
March 2023 3-4 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 667 of 768
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0 2 4 6 8 10 12 14 16 18 20 22
Time (hours)
LEGEND Figure 3.1
10-Year/24-HourRainfall Unit Intensity (Design Storm: 3.91 inches)
Unit Hyetograph
Storm Drainage System Master
Plan
January 15, 2021
Agenda Item 9.3
Page 668 of 768
Table 3.3 Relevant Design Storms
Storm Drainage System Master Plan
City of Gilroy
Design Criteria Design Storm
Used to evaluate if Hydraulic Grade Line have a minimum
of one foot of freeboard between top of curb. Quantified
at 3.91 inches.
10-year 24-hour
Used in evaluating street conveyance capacity and
determining if street flooding exceeds one foot in depth.
Quantified at 5.81 inches.
100-year 24-hour
10/20/2021
Agenda Item 9.3
Page 669 of 768
Table 3.4 Soil Imperviousness and SCS Curve Numbers
Storm Drainage System Master Plan
City of Gilroy
Effective Pervious
Effective Percent Ineffective Percent
AMC-II Pervious AMC-II Pervious AMC-II PerviousLand Use Category Impervious Impervious
Soil B Soil C Soil D
(%)
5
(%)
0
(CN)
63
(CN)
73
(CN)
82Rural Residential
Hillside 15
35
50
60
2
5
15
5
65
67
69
71
78
80
76
61
75
77
79
81
85
87
84
73
83
83
84
86
89
90
88
80
Low Density
Medium Density
High Density
Neighborhood District
Commercial
Industrial
0
0
95
70
1
0
0
Hecker Pass Special Use
Other Uses
0
Water Surface, Ponds, Streams, Canals 100
1
0
0
99
65
55
83
79
99
77
70
87
83
99
82
76
0
Natural Grassland
Floodplains 1 0
Parks, Athletic Fields, Cemetaries
Government, Schools
0 74
080 89
9/16/2020
Note:
1. Source: City of Gilroy 2004 Storm Drainage System Master Plan.
Agenda Item 9.3
Page 670 of 768
3.2 HYDRAULIC CRITERIA
The hydraulic criteria for the storm drainage system were used to evaluate the capacity
requirements of conveyance facilities.
3.2.1 Gravity Conveyance Facilities
Gravity pipeline capacities depend on several factors including: material and roughness of the
pipe, the limiting velocity and slope, and the maximum allowable depth of flow. The hydraulic
modeling software used for evaluating the capacity adequacy of the City storm drainage system is
InfoSWMM by Innovyze Inc. This software uses the fully dynamic St. Venant’s Equation, and has
a more accurate engine for simulating backwater and surcharge, in addition to manifolded force
mains. The software also incorporates the use of the Manning Equation in other calculations
including upstream pipe flow conditions.
Storm Hydraulic Design
The 10-year 24-hour design storm was used to evaluate the City’s existing stormwater system as
well as to size pipelines to serve areas of future growth. (Table 3.5). For the the 100-year 24-hour
design storm, City streets were allowed to flood in some cases to provide reasonable conveyance
and storage capacity, thus reducing additional costly improvements.
Manning’s Equation for Pipe Capacity
The Continuity Equation and the Manning’s Equation for steady-state flow are used for calculating
pipe capacities in open channel flow. Open channel flow can consist of either open conduits or, in
the case of gravity pipelines, partially full closed conduits. Gravity full flow occurs when the
conduit is flowing full but has not reached a pressure condition.
•Continuity Equation:Q = V A
Where:
Q = peak flow, in cubic feet per second (cfs)
V = velocity, in feet per second (fps)
A = cross-sectional area of pipe, in square feet (sq. ft.)
•Manning Equation:V = (1.486 R2/3 S1/2)/n
Where:
V = velocity, in feet per second (fps)
n = Manning’s roughness coefficient
R = hydraulic radius, area divided by wetted perimeter (ft)
S = slope of pipe, in feet per foot (ft/ft)
March 2023 3-8 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 671 of 768
Table 3.5 Hydrologic and Hydraulic Design Criteria
Storm Drainage System Master Plan
City of Gilroy
Hydrology and Hydraulics Design Criteria
Conveyance Facilities
10-Year 24-Hour design storm to determine if storm water
Pipelines
Streets
have a minimum of one foot of freeboard between the top
of curb and the Hydraulic Grade Line.
100-Year 24-Hour design storm to determine if flooding
exceeds one foot in depth and can flood buildings or create
safety hazards.
FEMA 100-year water surface elevations used for
downstream control for facilities where 100-year flood maps
are available.
Receiving Waters
(Streams, Creeks, Channels)
9/16/2020
Agenda Item 9.3
Page 672 of 768
St. Venant’s Equation for Pipe Capacity
A dynamic type of modeling facilitates the analysis of unsteady and non-uniform flows (dynamic
flows) within a gravity conveyance system. Some hydraulic modeling programs have the ability to
analyze these types of flows using the St. Venant Equation, which take into account unsteady and
non-uniform conditions that occur over changes in time and cross-section within system pipes.
The St. Venant Equations are a set of two equations, a Continuity Equation and a Dynamic
Equation, used to analyze dynamic flows within a system. The first equation, the Continuity
Equation, relates the continuity of flow mass within the system pipes in terms of: (A) the change in
the cross-sectional area of flow at a point over time, and (B) The change of flow over the distance
of piping in the system. The continuity equation is shown as follows:
휕퐴
휕푡
휕푄
휕푥•Continuity Equation:+= 0
(A)(B)
Where:
t = time
x = distance along the longitudinal direction of the channel
Q = discharge flow
A = flow cross-sectional area perpendicular to the x directional axis
The second equation, the Dynamic Equation, relates changes in flow to fluid momentum in the
system using: (A) Changes in acceleration at a point over time, (B) Changes in convective flow
acceleration, (C) Changes in momentum due to fluid pressure at a given point, (D) Changes in
momentum from the friction slope of the pipe, and (E) Fluid momentum provided by gravitational
forces. The Dynamic Equation is provided as follows:
2휕푄
휕푡
휕 푄 휕푦
휕푥•Dynamic Equation:+ (훽 ) + 푔퐴 + 푔퐴푆 − 푔퐴푆 = 0 푓 표휕푡 퐴
(A)(B)(C)(D)(E)
Where:
t = time
x = distance along the longitudinal direction of the channel
Q = discharge flow
A = flow cross-sectional area perpendicular to the x directional axis
y = flow depth measured from the channel bottom and normal to the x
directional axis
Sf = friction slope
So = channel slope
β = momentum
g = gravitational acceleration
Use of this method of analysis provides a more accurate and precise analysis of flow conditions
within the system compared to steady state flow analysis methods. It must be noted that two
March 2023 3-10 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 673 of 768
assumptions are made for use of St. Venant Equations in the modeling software. First, flow is one
dimensional. This means it is only necessary to consider velocities in the downstream direction
and not in the transverse or vertical directions. Second, the flow is gradually varied. This means
the vertical pressure distribution increases linearly with depth within the pipe.
Manning’s Roughness Coefficient (n)
The Manning Roughness Coefficient ‘n’ is a friction coefficient that is used in the Manning formula
for flow calculation in open channel flow. In conveyance systems, the coefficient can vary between
0.011 and 0.017 depending on pipe material, size of pipe, depth of flow, root intrusion,
smoothness of joints, and other factors.
For the purpose of this evaluation, an “n” value of 0.013 was used for both existing and proposed
gravity pipes unless directed otherwise by City staff based on pipe structural condition. This “n”
value is an acceptable practice in planning studies.
March 2023 3-11 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 674 of 768
2023City of Gilroy
CHAPTER 4 – EXISTING FACILITIES AND MODEL DEVELOPMENT
This chapter defines the hydrologic delineation of storm drainage areas, routing to their respective
receiving facilities, and includes the hydrologic model development. Additionally, this chapter
includes an overview of the storm drainage system, and the model development.
4.1 HYDROLOGIC SYSTEM OVERVIEW
Factors critical to the hydrologic model development include watersheds, drainage areas within
each watershed, overland flow routing within drainage sub-catchments, and conveyance that
makes full use of pipes as well as streets for routing 100-year design storm events. This section
discusses the existing watersheds, and the delineation of drainage areas and sub-catchments.
4.1.1 Watersheds
Watersheds within the City Planned Area Boundary and outlying areas were defined based on the
receiving tributary creek or river system, with topographical or physical barriers dictating the limits
of the watershed. The City has multiple natural watersheds that collect and convey stormwater
runoff within Urban Growth Boundary: Uvas Creek Watershed, Llagas Creek Watershed, and
Pajaro River Watershed (Figure 2.2).
4.1.2 Drainage Areas
Drainage areas are typically defined by existing or natural conveyance systems within each
watershed. The City’s drainage area boundaries are generally dictated by the open channel
conveyance facilities throughout the City (Figure 4.1). Drainage areas in the City discharge
stormwater runoff into creeks, channels or sloughs that flow through the City.
Each drainage area was assigned a unique identifier intended for cross-referencing purposes.
The identifier reflects the name of the receiving water body or storm drainage infrastructure that
receives the stormwater runoff. The project divided the City into seven drainage areas, which are
briefly summarized as follows:
•Llagas Drainage Area: The Llagas drainage area is generally defined as the area east of
Highway 101 and west of Llagas Creek, with the northern and southern boundaries
approximately represented by Miller Slough Channel and Southside Drive respectively.
•Miller Slough Drainage Area. The Miller Slough drainage area is generally defined as the
area east of Santa Teresa Boulevard and west of Highway 101, with the northern and
southern boundaries approximately represented by La Primavera Way and First Street
respectively. This drainage area generally flows in a northerly direction towards the Miller
Slough Channel.
March 2023 4-1 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 675 of 768
¤
101 Legend
Hydrologic Drainage Areas
Llagas
Miller Slough
Lower Miller Slough
North UvasRonan
Channel Princevalle
Ronan Channel
South UvasUvas Creek
Channels
Roads
RailroadsMiller
Slough City Limits
North
Uvas
V Urban Growth Boundary
Rivers & Creeks
Waterbodies
UV152152
Ronan
Channel VPrincevalle152Lower
Miller Slough Lower
Miller Slough£¤
101
Princevalle
South
Uvas North
Uvas
Llagas
Figure 4.1
Storm Drainage
Areas
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 15, 2022 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig4-2_DrainageBasins_41522.mxd
Agenda Item 9.3
Page 676 of 768
•Lower Miller Slough Drainage Area. The Lower Miller Slough drainage area is generally
defined as the area east of Carmel Street and west of Highway 101, with the northern and
southern boundaries approximately represented by Second Street and Tenth Street
respectively. This drainage area is generally flows in easterly direction towards the Lower
Miller Slough Channel.
•
•
North Uvas Drainage Area. The North Uvas drainage area is generally defined as the
area east of Burchell Road and Santa Barbara Drive, with northern and southern
boundaries approximately represented by Olea Court and Uvas Creek respectively. This
drainage area is generally flows in southerly direction towards the Uvas Creek.
Princevalle Drainage Area. The Princevalle drainage area is generally defined as the
area east of Santa Barbara Drive and west of Cameron Boulevard, with the northern and
southern boundaries approximately represented by First Street and Luchessa Avenue
respectively. This drainage area generally flows in a southeasterly direction, though it
currently is drained, via storm drainage system, in a southerly direction, towards the
Princevalle Channel.
•
•
Ronan Channel Drainage Area. The Ronan Channel drainage area is generally defined
as the area east of Jean Ellen Court and west of Highway 101, with northern and southern
boundaries approximately represented by Fitzgerald Avenue and First Street respectively.
South Uvas Drainage Area. The South Uvas drainage area is generally defined as the
area east of the Rancho Vista Drive and west of Highway 101, with the southeastern
boundaries approximately represented by Uvas Creek. This drainage area generally flows
in a northeasterly direction towards the Uvas Creek.
4.1.3 Drainage Sub-catchment
Each drainage area shown on Figure 4.1 was further divided into smaller sub-catchments for the
purpose of routing tributary hydrologic stormwater flows to appropriate stormwater manhole. The
connectivity within each sub-catchment is very critical for accurate analysis and was thus
graphically documented on exhibits included in Appendix B. Each sub-catchment included
hydrologic modeling information to mimic Overland Flow Routing and Combined Pipe Street
Conveyance.
•Overland Flow Routing. This element consists of routing rainfall runoff from sub-
catchments to stormwater manhole. Overland flow routing is dependent on many factors
such as land use, subsurface soil infiltration characteristics and physical barriers blocking
the flow paths within the drainage sub-catchment. The nonlinear reservoir method is
typically used to calculate overland flow and was built into the hydrologic component of the
model.
March 2023 4-3 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 677 of 768
•Combined Pipe Street Conveyance. During typical storm events, and up to 10-year 24-
hour design storms, streets are used to convey rainfall runoff from house gutters to
nearest catchments where it enters the conveyance system.
To mitigate very costly conveyance facility improvements during more intense storm
events and up to the 100-year 24-hour design storm, this analysis assumed that existing
streets may also provide additional capacity for routing rainfall runoff at a flood depth not to
exceed one foot.
4.2 HYDRAULIC SYSTEM OVERVIEW
The City’s storm drainage system consists of approximately 132 miles of up to 84-inch diameter
gravity pipelines that convey stormwater runoff as shown on Figure 4.2. A system-wide pipeline
inventory, listing the total length by pipe diameter and material, is shown on Table 4.1. This table
is based on information extracted from the City’s GIS database and was updated to reflect the
review of construction drawings provided by City staff. The 15-inch and 18-inch diameter pipeline
accounts for 50 percent of the total storm drainage pipeline lengths. The following section
discusses the components of the storm drainage system.
4.2.1 Conveyance System
The modeled storm drainage system includes approximately 55 miles of stormwater conveyance
to local water bodies, or channels (Table 4.2). Pipe sizes range from 18-inches to 84-inches in
diameter, and are shown on Figure 4.2. The modeled storm conveyance system is predominantly
composed of 18-, 24-, and 36-inch diameter pipelines.
The City-owned open channel conveyance systems includes the following: Ronan Channel, Miller
Slough and Princevalle Channel. These channels play an important role in relieving stormwater
runoff during intense rainfall events.
4.2.2 Outfalls
The modeled system consists of more than 60 outfall points that discharge runoff to natural
creeks, sloughs, and channels. These outfalls were located along the Uvas Creek, Princevalle
Channel, Miller Slough Channel, Lower Miller Slough Channel, Ronan Channel, and Llagas Creek
as shown in Figure 4.2.
March 2023 4-4 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 678 of 768
¤
101 Legend
Existing Modeled System
Outfalls!C
Pipes by Diameter
18" or Less
Y R
DA
D
PUEBLO ST 21" - 36"
42" or Greater
Channels!C!C!C
!C Non-Modeled System
Pipes
Uvas Creek !C !C!C !C !C !C
!C
!C
!C !C
!C
!C
18!C !C!C
!C
!C
!C Channels!C!C
18!C
!C
Roads
!C Railroads!C !C !C!C
City LimitsV!CV152152
Urban Growth Boundary
Rivers & Creeks
Waterbodies
!C
!C !C!C V!C !C !C !C 152!C !C!C !C!C !C !C!C !C !C
!C!C !C!C !C!C ¤
101
Princevalle!C!C!C !C !C !C !C
!C
!C
!C!C
!C
!C
Figure 4.2
Existing Modeled Storm!C !C
Drainage System
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 14, 2022 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig4-1_ExistingSys_041422.mxd
Agenda Item 9.3
Page 679 of 768
Table 4.1 Existing GIS Storm Pipe Inventory
Storm Drainage System Master Plan
City of Gilroy
Length In MaterialPipe Size Total Length
RCP CMP CIP Concrete HDPE PVC VCP ACP DIP Unknown
(in)(ft)(ft)(ft)(ft)(ft)(ft)(ft)(ft)(ft)(ft)(ft)
Unknown Diameter 32,806
19
88
0
0
0
83 0 12
3,165
5,802
500
362
3,996
1,397
8,219
0
0 0
0
0
0
33,525 66,514
4 0
0
71 0 0
944
817
0
3,255
10,214
7,661
6 2,733 0 0 16 603 115
351
354
197
41
0
0
8 5,816 0 177
226
283
157
19
0
0 0 0 0
10 2,200 27 0 0 0 0 3,169
12 22,978
110,396
204,862
12,428
74,554
14,574
27,537
3,829
491
576
609
257
810
147
112
0
1,031
608
1,666
362
0
2,205 39 0 377
1,024
551
0
31,597
116,910
220,720
13,047
79,163
15,625
28,285
4,242
15 1,614 1,097 0
18 4,399 0 394
021000
24 0 2,705 446
0
0 0 0 648
0270904
192
0
0 0 0 0
30 0 0 22 0
0
0 0 422
03300413
0
0 0
36 31,597
18,409
22,485
3,028
180
0
1,144
0
0 333 0 0 0 0 33,254
18,743
23,293
3,028
42 0 0 0 335
0
0 0 0
48 808
0
0 0 0 0 0 0 0
54
60
0 0 0 0 0 0 0 0
7,495 162
0
0 0 0
0
0 0 0 0 0 7,656
72 4,208 174
0
0 2,281
0
0 0 0 0 6,664
84 1,137 0 0 0 0 0 0 0 1,137
Total (ft)
Total (miles)
603,090
114.2
4,268
0.8
2,179
0.4
4,846
0.9
11,343
2.1
26,617
5.0
2,073
0.4
1,058
0.2
394
0.1
38,309
7.3
694,176
131.5
9/28/2020
Note:
1. Source: GIS information provided by City Staff on September 04, 2020.
Agenda Item 9.3
Page 680 of 768
Table 4.2 Existing Modeled Storm Pipe Inventory
Storm Drainage System Master Plan
City of Gilroy
Percent of Total
SystemPipe Size Length
(in)
18
(ft)(miles)
19.3
(%)
101,964 35.14%
21
24
12,908
58,024
12,974
23,095
3,609
2.4
11.0
2.5
4.4
0.7
5.3
3.5
3.1
0.5
1.3
0.8
0.2
55.0
4.45%
19.99%
4.47%
7.96%
1.24%
9.73%
6.45%
5.56%
0.90%
2.35%
1.37%
0.38%
27
30
33
36 28,224
18,721
16,129
2,624
42
48
54
60 6,830
72 3,976
84 1,117
Total 290,194 100%
10/5/2021
Agenda Item 9.3
Page 681 of 768
4.3 MODEL DEVELOPMENT
A GIS-based model of the City’s storm drainage system was developed to identify capacity
deficiencies and to recommend improvements to mitigate those deficiencies. This section
discusses the modeling software, land use and routing methodology.
4.3.1 Modeling Software
The hydrologic component of the drainage model generates runoff through synthetic design storm
events and sub-catchment parameters that mimic actual surface response to rainfall. The
hydraulic component of the drainage model routes stormwater runoff from source (loading
manholes) to the discharge points (outfalls) by using physical characteristics of the storm drainage
system (pipelines). The hydraulic model then performs calculations and solves series of equations
to simulate flows in pipes, including backwater calculations for surcharged conditions.
There are several network analysis software products released by different manufacturers that
can equally perform the hydrologic and hydraulic analysis satisfactorily. The selection of a
particular software depends on user preferences, the storm drainage system’s unique
requirements, and the costs for purchasing and maintaining the software.
The modeling software used for evaluating the capacity adequacy of the Gilroy storm drainage
system, InfoSWMM by Innovyze Inc. This software uses the fully dynamic St. Venant’s Equation,
and has a more accurate engine for simulating backwater and surcharge. The software also
incorporates the use of the Manning Equation in other calculations including upstream pipe flow
conditions. The St Venant’s and Manning’s Equations were discussed in the System Performance
and Design Criteria chapter.
4.3.2 Land Use and Routing Methodology
The sub-catchment parameters in the model were populated to account for land use types, flood
routing, and routing methodology.
•Land Use. Land use was used to define impervious area and the SCS Curve Number for
pervious runoff. Residential areas included soil classifications to define non-effective
runoff mostly confined in backyards.
•
•
Flood Routing. Flood routing consists of determining the flow path and connectivity to the
storm drainage collection system.
Routing Methodology. Nonlinear reservoir method is used for transforming precipitation
into runoff for overland flow routing, street flow, and pipe conveyance. This is typically
defined by the time of concentration, which represents the time it takes for overland flow to
reach from the furthest point in a sub-catchment to the outfall. It is calculated as the sum of
the inlet time required to reach a manhole and the travel time in the conveyance system
from the manhole to the outfall.
March 2023 4-8 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 682 of 768
4.3.3 Hydrological Soil Classification
Soils are classified into four hydrologic soil units. These groups are A, B, C, and D, where A soil
are characterized by having high infiltration rates and low potential runoff and D soil are
characterized by having very slow infiltration rates and high runoff potential. The City hydrological
soil classification extracted from Soil Survey Geographic database (SSURGO) is shown
graphically on Figure 4.3.
4.3.4 Typical Channel Cross-Section
The majority of the City’s storm drainage system are pipelines that drain into the major channels
discussed in the previous section. Typical channel cross-sections are shown graphically on
Figure 4.4 and were used to represent some of the channels in the models.
4.3.5 Physical Hydraulic Model Elements
The City’s GIS database was used as a primary source to define physical hydraulic model
elements. Data gaps related to inverts and ground elevations were resolved through review of as-
built drawings. The physical hydraulic model was populated to include rim elevations at manholes,
invert elevations of pipelines, pipe sizes, pipe slopes, pipe lengths, and outfall elevations.
March 2023 4-9 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 683 of 768
¤
101 Legend
Subbasin Soil Type
Type B
Type C
Type D
Channels
Roads
Railroads
City Limits
Urban Growth Boundary
Rivers & Creeks
Waterbodies
V UV152152
V152
£¤
101
Princevalle
Figure 4.3
Hydraulical Soil
Classification
Storm Drainage System Master Plan
City of Gilroy
5GIS
0 0.25 0.5 1
MileUpdated: February 9, 2022
File Path & Name: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig4-3_SoilClassification_020922.mxd
Agenda Item 9.3
Page 684 of 768
Miller Slough Ronan
9
8
7
6
5
4
3
2
1
0
14
12
10
8
T =102'T = 40'
y = 8'61 1 y = 13'
41.75 2
2
0
b = 12'b = 50'
Lower Miller Slough Princevalle
14
12
10
8
10
9
8
7
6
5
4
3
2
1
0
T = 30'T = 67'
y = 9'y = 12'161
4 1.52.2
2
0
b = 14'b = 3'
LEGEND Figure 4.4
T: Top Width
b: Bottom Width
y: Depth
Channel Cross-Section
Storm Drainage System Master
Plan
Note:
Channel cross-section estimated using SCVWD contours.City of Gilroy
February 26, 2021
Agenda Item 9.3
Page 685 of 768
2023City of Gilroy
CHAPTER 5 – EVALUATION AND PROPOSED IMPROVEMENTS
This chapter presents a summary of the storm drainage system evaluation and identifies
improvements needed to mitigate existing deficiencies as well as improvements needed to
expand the system to service future growth.
5.1 OVERVIEW
The City’s stormwater model was used to evaluate the current storm drainage system, identify
capacity deficiencies and to recommend improvements required to serve future growth based on
the relevant design storms. The criteria used for evaluating the capacity adequacy of the storm
drainage system and used for sizing recommended improvements were discussed and
summarized in the System Performance and Design Criteria chapter.
5.2 KNOWN AREAS OF CONCERN
The capacity evaluation phase also considered a detailed review of known areas of concern. City
staff have maintained an inventory of known areas of concern that may experience surface water
ponding during large storm events. The known areas of concern provided by City staff are
documented on Table 5.1. The capacity improvement recommended in this chapter are intended
to alleviate some of these problem areas.
5.3 PIPELINE CONVEYANCE CAPACITY EVALUATION
The 10-year 24-hour design storm was used for evaluating the capacity adequacy of pipeline
conveyance facilities. The existing capacity analysis indicates that the conveyance facilities are
generally adequate to accommodate the design storm, with certain areas experiencing
surcharging and flooding as shown on Figure 5.1.
As part of the Master Plan, an analysis of the recently updated NOAA Atlas 14 precipitation was
completed and corresponding recommendations were presented to City staff for review. City staff
reviewed and requested a similar analysis using the precipitation data from the Santa Clara
County Drainage Manual. City staff chose to maintain the precipitation data from the Santa Clara
County Drainage Manual for the purposes of developing the capital improvement program (CIP)
discussed in a later chapter.
5.4 CAPACITY EVALUATION ANALYSIS
This Master Plan evaluated the storm drainage system infrastructure and recommend
improvements to mitigate existing system deficiencies and future development at the buildout.
Two alternatives were considered and evaluated, discussed as follows:
March 2023 5-1 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 686 of 768
¤
101 Legend
Flooding Manholes
Surcharging Manholes
!(
!(
Existing Modeled System
Outfalls!C
Y R
DA
D
PUEBLO ST Pipes by Diameter
18" or Less!(!(!!((!(!(!(!(!(!(!(!(!(!(!(!(!(!( !(!(!( !!(!(!((!(!( !(!(
21" - 36"!C!C!C!(
!C 42" or Greater
Channels
Uvas Creek !C !( !C!C !C !C !C!!((!(!(!C!(!( !(!(!(!(!(!(!(
!(!(!(!(!( !(!(!(!(
!C !C
!C
!C
!(!18 !(!(!(
!(
(!(!(!(!C
!C
!C !C !(!(!(
!C
!C!( !(!(!(!(!(!(!(Roads!(
!(
!(!(!(!( !(
!(!C!C
18
!!((!(!(!(!C!(!(!(!( !( !( !(!(!(!(!((
!!((!(!(Railroads!(!(!(
!(!(!C!(!(!(!(!(!!(!(!(!(!(!(!!((!(!(!(!(!(!(
!(!C !C!(!(!(
!( !(!(!(!(!(!(
!(!( !(!(!(City Limits!C !(!C!(!(!(!(!( !(!C!(
!(
!(!(!(!(!(!(!C!C!(!(!( !(!(!(Urban Growth Boundary
Rivers & Creeks
Waterbodies
V !(!(!(V !(!(
!(!(!(!(152 152 !!(!(!(!(!(!(!C!(!(!(!(!(!(!(!(!(!( !(!(
!(!( !(!( !(!C !C!(!(!( !( !(!(!(!(!(!C !(!(!(
!(!(!(!(!( !( !(!(!(!(!(!(
!( !( !(
!(!(!(
!(!(V!!( !( !(!C !(!(
!(!(!(
!(!(!(
!(!(!C!C !C !(!C 152!(!( !( !(!(!(!(
!(!C!(!C !C!C
!( !(!(!( !( !(!(!(
!(!(!( !( !(!(!(!!( !((!(!(!(!(
!( !(!(!(!(!( !( !(
!( !( !(!(!( !(!(!(!(!(!( !(!(!(!(
!(!(!(!(!(
!(!(
!( !(!(!(!C !C !(!(!(!(!(!(!C !(!(!(!(!(!(!(!C !(!(!(!(
!( !(!(!(!(!(!!((!(!(!(
!(!C
!C
!(!(!(!(!C !C!C
!( !(!(!(!(
!(!(
!(!(
!(
!(
!C !(!(!C !(!(!(!(¤
101
!(!(
!(!(!( !(!(!(!(!(
!(!(
Princevalle!C!C!C !C !C !C !C !(
!(!C !(!(!(!(!(!(!(
!(!C !( !(!(!(!(!( !(!(!(
!C!C !((
!(
!(!(!(
!C
!( !(!(!(
!(!(!C !(
!(
Figure 5.1
Existing System Analysis
!(!(
!C!C
10-Year Design Storm
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 15, 2022 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig5-1_10YrStorm_041522.mxd
Agenda Item 9.3
Page 687 of 768
Table 5.1 Storm Drainage System Problem Areas
Storm Drainage System Master Plan
City of Gilroy
No.Type of Concern Location
1
2
3
4
5
Leaves on Catch Basin
Flooding
Monterey Road & First Street
First Street & Church Street
Third Street & Church Street
Sixth Street & Church Street
Seventh Street & Church Street
Flooding
Leaves on Catch Basin
Flooding
Luchessa Avenue between Monterey Road &
Chestnut Street6
7
Flooding
Flooding Chestnut Street between Eighth Street & Ninth
Street
8 Leaves on Catch Basin
Flooding
Church Street & Howson Street
Welburn Avenue & Hanna Street
Welburn Avenue & Westwood Drive
Wren Avenue & Ronan Avenue
Driftwood Terrace & Westwood Drive
Hanna Street & Broadway
9
10
11
12
13
14
15
16
17
18
19
20
21
Leaves on Catch Basin
Flooding
Leaves on Catch Basin
Flooding
Flooding Hanna Street & Third Street
Rosanna Street & Third Street
Dowdy Street & Fifth Street
Fourth Street & Filice Drive
Fourth Street & Monte Vista Way
Fourth Street & Miller Avenue
Sixth Street & Princevalle Street
Forest Street & Martin Street
12/8/2021
Flooding
Flooding
Leaves on Catch Basin
Leaves on Catch Basin
Leaves on Catch Basin
Leaves on Catch Basin
Flooding
Note:
1. Storm drainage problem locations provided by City staff on March 24, 2021.
Agenda Item 9.3
Page 688 of 768
5.4.1 Alternative 1 - 8th Street 36-inch Pipeline Improvements
This alternative consists of a total 10.1 miles of pipeline improvements, including paralleling the
existing 36-inch diameter storm drainage pipeline along 8th Street under Highway 101. However,
this alternative requires coordination with the California Department of Transportation (Caltrans)
for the 36-inch diameter parallel pipeline. In summary, this alternative will require the following
improvements, which are shown graphically on Figure 5.2.
•10.1 miles of new pipeline ranging in size from 24 to 90 inches in diameter.
As part of this master plan, preliminary costs were prepared as a means of comparing
infrastructure improvements alternatives. The total approximate cost estimate for this alternative is
at $40.7 million.
5.4.2 Alternative 2 – Diverting Stormwater Runoff to Princevalle Channel
Following the review of the first alternative improvements, city staff requested Akel to evaluate the
feasibility of diverting stormwater runoff south to Princevalle Channel, as a second alternative.
This alternative consists of a total 9.3 miles of pipeline improvements, none of the which
improvements are crossing Highway 101 and therefore do not require coordination with Caltrans.
In summary, this alternative will require the following improvements, which are shown graphically
on Figure 5.3.
•9.3 miles of new pipeline ranging in size from 24 to 90 inches in diameter.
The total estimated cost for this alternative is estimated at
$36.4 million. This alternative was selected by City staff
due to the lower capital improvement costs and
construction feasibility. In comparison, alternative 1 costs
were estimated at $40.7 million and that alternative
require the construction of 36-inch pipeline under
Highway 101.
Alternative 1
Proposed Improvement Costs: $40.7
million dollars. Also requires construction
of 36-inch pipeline under Highway 101.
Alternative 2 (Recommended)
Recommended Improvement Costs:
$36.4 million dollars
Since Alternative 2 is the recommended alternative, a
more detailed listing of improvements is summarized on Table 5.2, and which are shown
graphically and cross reference on Figure 5.3. Each pipeline has been assigned a uniquely coded
identifier corresponding to the drainage area in which it resided; this unique identifier is intended
to aid in defining the location of the improvement for mapping purposes. The Alternative 2
improvements are also briefly described in this section, by drainage area:
March 2023 5-4 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 689 of 768
¤
101 Legend
Proposed Improvements
!C Outfall
Pipes
Pipeline Casing
Y R
DA
D
PUEBLO ST Existing Modeled System
Outfalls!C
Pipes by Diameter
18" or Less
!C!C!C !C
!C
Uvas Creek !C !C!C !C !C !C !C
!C 21" - 36"!C
!C
!C
18!C
!C
!C !C !C
!C 42" or Greater
Channels
!C!C
18!C
!C
!C Non-Modeled System
Pipes
!C !C !C!C
V !CV15224152
Channels!C
48 Roads!C !C42!C V!C !C !C !C 152 Railroads!C !C!C !C!C !C City Limits!C!C !C !C
!C!C !C!C Urban Growth Boundary
Rivers & Creeks
Waterbodies
!C!C ¤
101
Princevalle!C!C!C !C !C !C !C
!C
!C
!C!C
!C
!C
!C
Figure 5.2
Proposed Improvements!C !C
Alternative 1
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 15, 2022 Mile
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Agenda Item 9.3
Page 690 of 768
¤
101 Legend
Proposed Improvements
!C Outfall
Pipes
Existing Modeled System
Y R
DA
D
PUEBLO ST Outfalls!C
Pipes by Diameter
18" or Less!C!C!C
Uvas Creek !C 21" - 36"!C !C!C !C !C !C
!C
!C
!C 42" or Greater
Channels
!C
!C
!C
18!C !C!C
!C
!C
!C !C!C
18!C
!C Non-Modeled System
Pipes!C!C !C !C!C
ChannelsV!CV15224152
Roads!C
48 Railroads!C !C42!C V!C !C !C !C 152 City Limits!C !C!C !C!C !C Urban Growth Boundary
Rivers & Creeks
Waterbodies
!C!C !C !C
!C!C !C!C !C!C ¤
101
Princevalle!C!C!C !C !C !C !C
!C
!C
!C!C
!C
!C
!C
Figure 5.3
Proposed Improvements!C !C
Alternative 2
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 15, 2022 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig5-3_PropImpAlt2_041522.mxd
Agenda Item 9.3
Page 691 of 768
Table 5.2 Proposed Improvements
Storm Drainage System Master Plan
City of Gilroy
Improv.
No.
Existing
Diameter
Pipeline ImprovementsAlignmentLimits
New/Parallel/Diameter Length
(in)Replace (in)(ft)
Ronan Channel Drainage Area
RC-1
RC-2
RC-3
RC-4
RC-5
RC-6
RC-7
RC-8
RC-9
Sunrise Dr
Mantelli Dr
Zamzow Ct
Cohansey Ave
Murray Ave
Murray Ave
From Dream Catcher Way to Golden Sky Way
From Muir Drive to Delta Dr
18
18
-
Replacement
Replacement
New
30
24
48
48
48
48
36
48
42
400
1,250
1,200
1,450
2,800
600
From approx. 1,250' n/o Cohansey Ave to
Cohansey Ave
From approx. 350' e/o Monterey Rd to Murray
Ave -New
From Cohansey Ave to Tomkins Ct
From Tomkins Ct to Ronan Channel
-New
24
-
Replacement
NewNo Name Uno/Las Animas From approx. 1,500' s/o Buena Vista Ave to San 3,400
3,425
150
Ave Ysidro Ave
From Las Animas Ave to approx. 500' n/o
Leavesley Rd
From approx. 220' e/o Forest St to approx. 360'
e/o Forest St
San Ysidro Ave -New
Leavesley Rd 18 Replacement
Miller Slough Drainage Area
MS-1
MS-2
MS-3
MS-4
MS-5
MS-6
Wren Ave
First St
From approx. 290' n/o First St to Lawrence Dr
From approx. 180' e/o Princevalle St to Sargent St
From First St to Broadway
24
18
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
30
24
24
30
30
27
2,325
525
Sargent St
Broadway
Church St
Monterey Rd
18 425
From Sargent St to Church St 18/21
21
1,075
400From Broadway to approx. 100' s/o Howson St
From Second St to First St 18/24 675
North Uvas Drainage Area
From approx. 3,080' w/o Santa Teresa Blvd to
approx. 360' w/o Santa Teresa Blvd
From approx. 360' w/o Santa Teresa Blvd to Santa
Teresa Blvd
From approx. 70' s/o Hecker Pass Hwy to Uvas
Creek
NU-1
NU-2
NU-3
NU-4
NU-5
NU-6
NU-7
NU-8
Hecker Pass Hwy
Hecker Pass Hwy
Santa Teresa Blvd
Westwood Dr
Monterey Rd
Monterey Rd
ROW
-
24
24
18
-
New
Replacement
Replacement
Replacement
New
30
30
30
24
90
90
90
90
2,825
350
2,575
425From approx. 150' s/o Third St to Kentwood Ct
From Princevalle Channel to Victoria Dr 775
From Victoria Dr to approx. 950' n/o Farman Ln 42
-
Replacement
New
2,175
975From Monterey Rd to approx. 970' n/o Uvas
Creek
ROW From approx. 970' n/o Uvas Creek to Uvas Creek -New 1,000
South Uvas Drainage Area
From Carnoustie Ct to approx. 380' nw/o
Carnoustie CtSU-1 St Andrews Cir 18 Replacement 36 375
Agenda Item 9.3
Page 692 of 768
Table 5.2 Proposed Improvements
Storm Drainage System Master Plan
City of Gilroy
Improv.
No.
Existing
Diameter
Pipeline ImprovementsAlignmentLimits
New/Parallel/Diameter Length
(in)Replace (in)(ft)
Princevalle Drainage Area
PR-1
PR-2
PR-3
PR-4
PR-5
PR-6
PR-7
PR-8
PR-9
PR-10
PR-11
PR-12
PR-13
Third St
Third St
From Santa Paula Dr to Wren Ave 27
27
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
New
30
42
48
48
48
48
48
30
54
24
24
48
48
825
675From Wren Ave to approx. 170' e/o Santa Theresa
Dr
From approx. 170' e/o Santa Theresa Dr to Santa
Theresa DrThird St 27 200
Santa Theresa Dr
ROW
From Third St to approx. 300' s/o Fourth St
From Santa Theresa Dr to Miller Ave
From approx. 300' s/o Fourth St to Fifth St
From Miller Ave to Princevalle St
From Third St to Fifth St
27/30
30
950
675
Miller Ave
Fifth St
30 400
30 1,250
1,250
1,225
825
Princevalle St
Princevalle St
Alexander St
Banes Ln
18
From Fifth St to Seventh St 42
From Tenth St to Banes Ln 18
From Alexander St to Automall Pkwy
From approx. 380' n/o 8th St to Angra Way
From Angra Way to Princevalle Channel
18 625
Monterey Rd
Monterey Rd
-2,475
77542Replacement
Lower Miller Slough Drainage Area
LM-1
LM-2
LM-3
LM-4
LM-5
LM-6
Fourth St
Monterey Rd
Monterey Rd
Monterey Rd
ROW
From Eigleberry St to Monterey Rd
From Fourth St to Sixth St
18
27
27
33
18
24
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
30
36
42
42
24
36
400
1,250
425From Sixth St to Hornlein Ct
From Hornlein Ct to approx. 240' n/o Eighth St
From Rosanna St to Monterey Rd
From Sixth St to Eighth St
775
1,125
Alexander St 1,300
4/11/2022
Agenda Item 9.3
Page 693 of 768
5.4.3 Ronan Channel Drainage Area
This section documents improvements within the Ronan Channel drainage service area.
•
•
•
•
•
•
•
RC-1: Replace the existing 18-inch diameter pipeline on Sunrise Drive with a new 30-inch
diameter pipeline from Dream Catcher Way to Golden Sky Way.
RC-2: Replace the existing 18-inch diameter pipeline on Mantelli Drive with a new 24-inch
diameter pipeline from Muir Drive to Delta Drive.
RC-3: Construct a new 48-inch diameter pipeline on Zamzow Court from approximately
1,250 feet north of Cohansey Avenue to Cohansey Avenue.
RC-4: Construct a new 48-inch diameter pipeline on Cohansey Avenue from
approximately 350 feet east of Monterey Road to Murray Avenue.
RC-5: Construct a new 48-inch diameter pipeline on Murray Avenue from approximately
Murray Avenue to Tomkins Court.
RC-6: Replace the existing 24-inch diameter pipeline on Murray Avenue with a new 48-
inch diameter pipeline from Tomkins Court to Ronan Channel.
RC-7: Construct a new 36-inch diameter pipeline along No Name Uno and Las Animas
Avenue from approximately 1,500 feet south of Buena Vista Avenue to San Ysidro
Avenue.
•
•
RC-8: Construct a new 48-inch diameter pipeline on San Ysidro Avenue from Las Ysidro
Avenue to approximately 500 feet north of Leavesley Road.
RC-9: Replace the existing 18-inch diameter pipeline on Leavesley Road with a new 42-
inch diameter pipeline from approximately 220 feet east of Forest Street to approximately
360 feet east of Forest Street.
5.4.4 Miller Slough Drainage Area
This section documents improvements within the Miller Slough drainage service area.
•
•
•
MS-1: Replace the existing 24-inch diameter pipeline on Wren Avenue with a new 30-inch
diameter pipeline from approximately 290 feet north of First Street to Lawrence Drive.
MS-2: Replace the existing 18-inch diameter pipeline on First Street with a new 24-inch
diameter pipeline from approximately 180 feet east of Princevalle Street to Sargent Sreet.
MS-3: Replace the existing 18-inch diameter pipeline on Sargent Street with a new 24-inch
diameter pipeline from First Street to Broadway.
March 2023 5-9 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 694 of 768
•
•
MS-4: Replace the existing 18 and 21-inch diameter pipeline on Broadway with a new 30-
inch diameter pipeline from Sargent Street to Church Street.
MS-5: Replace the existing 21-inch diameter pipeline on Church Street with a new 30-inch
diameter pipeline from Broadway to approximately 100 feet south of Howson Street.
•MS-6: Replace the existing 18 and 24-inch diameter pipeline on Monterey Road with a
new 27-inch diameter pipeline from Second Street to First Street.
5.4.5 North Uvas Drainage Area
This section documents improvements within the North Uvas drainage service area.
•
•
•
•
NU-1: Construct a new 30-inch diameter pipeline on Hecker Pass Highway from
approximately 3,080 feet west of Santa Teresa Boulevard to approximately 360 feet west
of Santa Teresa Boulevard.
NU-2: Replace the existing 24-inch diameter pipeline on Hecker Pass Highway with a new
30-inch diameter pipeline from approximately 360 feet west of Santa Teresa Boulevard to
Santa Teresa Boulevard.
NU-3: Replace the existing 24-inch diameter pipeline on Santa Teresa Boulevard with a
new 30-inch diameter pipeline from approximately 70 feet south of Hecker Pass Highway
to Uvas Creek.
NU-4: Replace the existing 18-inch diameter pipeline on Westwood Drive with a new 24-
inch diameter pipeline from approximately 150 feet south of Third Street to Kentwood
Court.
•NU-5. Construct a new 90-inch diameter pipeline on Monterey Road from Princevalle
Channel to Victoria Drive.
•
•
NU-6: Replace the existing 42-inch diameter pipeline on Monterey Road with a new 90-
inch diameter pipeline from Victoria Drive to approximately 950 feet north of Farman Lane.
NU-7. Construct a new 90-inch diameter pipeline in right-of-way from Monterey Road to
approximately 970 feet north of Uvas Creek.
•NU-8. Construct a new 90-inch diameter pipeline in right-of-way from approximately 970
feet north of Uvas Creek to Uvas Creek.
5.4.6 South Uvas Drainage Area
This section documents improvements within the South Uvas drainage service area.
March 2023 5-10 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 695 of 768
•SU-1: Replace the existing 18-inch diameter pipeline on St Andrews Circle with a new 36-
inch diameter pipeline from Carnoustie Court to approximately 380 feet northwest of
Carnoustie Court.
5.4.7 Princevalle Drainage Area
This section documents improvements within the Princevalle drainage service area.
•PR-1: Replace the existing 27-inch diameter pipeline on Third Street with a new 30-inch
diameter pipeline from Santa Paula Drive to Wren Avenue.
•PR-2: Replace the existing 27-inch diameter pipeline on Third Street with a new 42-inch
diameter pipeline from Wren Avenue to approximately 170 feet east of Santa Theresa
Drive.
•
•
PR-3: Replace the existing 27-inch diameter pipeline on Third Street with a new 48-inch
diameter pipeline from approximately 170 feet east of Santa Theresa Drive to Santa
Theresa Drive.
PR-4: Replace the existing 27 and 30-inch diameter pipeline on Santa Theresa Drive with
a new 48-inch diameter pipeline from Third Street to approximately 300 feet south of
Fourth Street.
•
•
•
•
•
•
•
•
PR-5: Replace the existing 30-inch diameter pipeline in right-of-way with a new 48-inch
diameter pipeline from Santa Theresa Drive to Miller Avenue.
PR-6: Replace the existing 30-inch diameter pipeline on Miller Avenue with a new 48-inch
diameter pipeline from approximately 300 feet south of Fourth Street to Fifth Street.
PR-7: Replace the existing 30-inch diameter pipeline on Fifth Street with a new 48-inch
diameter pipeline from Miller Avenue to Princevalle Street.
PR-8: Replace the existing 18-inch diameter pipeline on Princevalle Street with a new 30-
inch diameter pipeline from Third Street to Fifth Street.
PR-9: Replace the existing 42-inch diameter pipeline on Princevalle Street with a new 54-
inch diameter pipeline from Fifth Street to Seventh Street.
PR-10: Replace the existing 18-inch diameter pipeline on Alexander Street with a new 24-
inch diameter pipeline from Tenth Street to Banes Lane.
PR-11: Replace the existing 18-inch diameter pipeline on Banes Lane with a new 24-inch
diameter pipeline from Alexander Steet to Automall Parkway.
PR-12: Construct a new 48-inch diameter pipeline on Monterey Road from approximately
380 feet north of Eighth Street to Angra Way.
March 2023 5-11 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 696 of 768
•PR-13: Replace the existing 42-inch diameter pipeline on Monterey Road with a new 48-
inch diameter pipeline from Angra Way to Princevalle Channel.
5.4.8 Lower Miller Slough Drainage Area
This section documents improvements within the Lower Miller Slough drainage service area.
•
•
•
•
LM-1: Replace the existing 18-inch diameter pipeline on Fourth Street with a new 30-inch
diameter pipeline from Eigleberry Street to Monterey Road.
LM-2: Replace the existing 27-inch diameter pipeline on Monterey Road with a new 36-
inch diameter pipeline from Fourth Street to Sixth Street.
LM-3: Replace the existing 27-inch diameter pipeline on Monterey Road with a new 42-
inch diameter pipeline from Sixth Street to Hornlein Court.
LM-4: Replace the existing 33-inch diameter pipeline on Monterey Road with a new 42-
inch diameter pipeline from Hornlein Court to approximately 240 feet north of Eighth
Street.
•
•
LM-5: Replace the existing 18-inch diameter pipeline in right-of-way with a new 24-inch
diameter pipeline from Rosanna Street to Monterey Road.
LM-6: Replace the existing 24-inch diameter pipeline on Alexander Street with a new 36-
inch diameter pipeline from Sixth Street to Eighth Street.
5.5 OUTFALLS
The City’s storm drainage system discharges stormwater runoff into several outfalls that discharge
into: Ronan Channel, Miller Slough Channel, Princevalle Channel, Uvas Creek, and Llagas Creek.
As part of this master plan, outfalls were assumed in adequate condition, and capable of
conveying stormwater flows from upstream facilities.
March 2023 5-12 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 697 of 768
2023City of Gilroy
CHAPTER 6 - CAPITAL IMPROVEMENT PROGRAM
This chapter provides a summary of the recommended storm drainage system improvements to
mitigate existing capacity deficiencies and for accommodating anticipated future growth. This
chapter also presents the cost criteria and methodologies for developing the Capital Improvement
Program (CIP). Finally, a cost allocation analysis, usually used for cost sharing purposes, is also
included.
6.1 COST ESTIMATE ACCURACY
Cost estimates presented in the Capital Improvement Program were prepared for general master
planning purposes and, where relevant, for further project evaluation. Final costs of a project will
depend on several factors including the final project scope, costs of labor and material, and
market conditions during construction.
The Association for the Advancement of Cost Engineering (AACE International), formerly known
as the American Association of Cost Engineers, has defined three classifications of assessing
project costs. These classifications are presented in order of increasing accuracy: Order of
Magnitude, Budget, and Definitive.
•Order of Magnitude Estimate. This classification is also known as an “original estimate”,
“study estimate”, or “preliminary estimate”, and is generally intended for master plans and
studies.
This estimate is not supported with detailed engineering data about the specific project,
and its accuracy is dependent on historical data and cost indices. It is generally expected
that this estimate would be accurate within -30 percent to +50 percent.
•
•
Budget Estimate. This classification is also known as an “official estimate” and generally
intended for pre-design studies. This estimate is prepared to include flow sheets and
equipment layouts and details. It is generally expected that this estimate would be
accurate within -15 percent to +30 percent.
Definitive Estimate. This classification is also known as a “final estimate” and prepared
during the time of contract bidding. The data includes complete plot plans and elevations,
equipment data sheets, and complete specifications. It is generally expected that this
estimate would be accurate within -5 percent to + 15 percent.
Costs developed in this study should be considered “Order of Magnitude” and have an expected
accuracy range of -30 percent and +50 percent.
March 2023 6-1 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 698 of 768
6.2 COST ESTIMATE METHODOLOGY
Cost estimates presented in this chapter are opinions of probable construction and other relevant
costs developed from several sources including cost curves, Akel experience on other master
planning projects, and input from City staff on the development of public and private cost sharing.
Where appropriate, costs were escalated to reflect the more current Engineering News Records
(ENR) Construction Cost Index (CCI).
This section documents the unit costs used in developing the opinion of probable construction
costs, the Construction Cost Index, the land acquisition costs, and markups to account for
construction contingency and other project related costs.
6.2.1 Unit Costs
The unit cost estimates used in developing the Capital Improvement Program are summarized on
Table 6.1. The unit costs are intended for developing the Order of Magnitude estimate, and do not
account for site specific conditions, labor or material costs during the time of construction, final
project scope, implementation schedule, detailed utility and topography surveys, investigation of
alternative routes for pipelines, and other various factors. These factors are assumed included in
the contingencies applied to the final capital improvement cost.
6.2.2 Construction Cost Index
Costs estimated in this study are adjusted utilizing the Engineering News Record (ENR)
Construction Cost Index (CCI), which is widely used in the engineering and construction
industries.
The costs in this Storm Drainage System Master Plan were benchmarked using a 20-City national
average ENR CCI of 12,176, reflecting a date of March 2023.
6.2.3 Construction Contingency Allowance
Knowledge about site-specific conditions for each proposed project is limited at the master
planning stage; therefore, construction contingencies were used. The estimated construction
costs in this master plan include a 30 percent contingency allowance to account for unforeseen
events and unknown field conditions.
6.2.4 Project Related Costs
The capital improvement costs also account for project-related costs, comprising of engineering
design, project administration (developer and City staff), construction management and
inspection, and legal costs. The project related costs in this master plan were estimated by
applying an additional 30 percent to the estimated construction costs.
March 2023 6-2 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 699 of 768
Table 6.1 Unit Costs
Storm Drainage System Master Plan
City of Gilroy
Pipelines
(in)($/Lineal Foot)
24 245
27
30
36
42
48
54
60
66
72
84
90
283
302
358
414
489
545
564
622
678
866
928
Pipeline Casings
$22 per inch diameter per liner foot
3/29/2023
Note :
1. Unit costs are based on an ENR CCI Index Value
of 13,176 (March 2023).
Agenda Item 9.3
Page 700 of 768
6.3 CAPITAL IMPROVEMENT PROGRAM
This section documents the capital improvement program, contingencies included in the costs,
and the allocation of costs to meet the requirements of AB1600.
6.3.1 Capital Improvement Costs
The Capital Improvement Program costs for the projects identified in this master plan for
mitigating existing deficiencies and for servicing future growth throughout the City are summarized
on Table 6.2.
Each improvement was assigned a unique code identifier associated with the improvement
pipelines drainage area, and is summarized graphically on Figure 6.1. The estimated construction
costs include the baseline costs plus 30 percent contingency allowance to account for unforeseen
events and unknown field conditions, as described in a previous section. Capital Improvement
Costs include the estimated construction costs plus 30 percent project-related costs (engineering
design, project administration, construction management and inspection, and legal costs).
6.3.2 Pipelines
The recommended pipeline improvements are grouped by drainage area and listed on Table 6.2.
Each improvement includes a general description of the street alignment and limits, as well as
existing pipe diameter and length. Improvements are shown on Figure 6.1.
The following pipeline improvements categories were identified:
•
•
New Pipeline. A new pipeline is proposed where none exists.
Replacement Pipeline. This improvement is intended as a replacement to an existing
pipeline, and along the same alignment. The existing pipeline should be abandoned when
the replacement pipeline has been constructed.
The opinion of probable construction costs, for the projects included in this master plan, are based
on the pipe unit costs summarized on Table 6.1.
It is assumed that any replacement pipes will be in the same alignment and at the same slope as
the existing pipe. However, this study recommends a field survey of the alignment during the pre-
design stage of each project.
March 2023 6-4 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 701 of 768
¤
101 Legend
Proposed Improvements
!C Outfall
Pipes
Existing Modeled System
Y R
DA
D
PUEBLO ST Outfalls!C
Pipes by Diameter
18" or Less!C!C!C
Uvas Creek !C 21" - 36"!C !C!C !C !C !C
!C
!C
!C 42" or Greater
Channels
!C
!C
!C
18!C !C!C
!C
!C
!C !C!C
18!C
!C Non-Modeled System
Pipes!C!C !C !C!CMS-5 ChannelsVNU-2
!CV15224
MS-2
152
Roads!C
RailroadsPR-3 !C !C42
PR-2
!C V!C !C !C !C 152 City Limits!C !C!C !C!C !C LM-3 Urban Growth Boundary
Rivers & Creeks
Waterbodies
!C!C !C PR-6 !C
!C!C !C!C !C!C ¤
101
Princevalle!C!C!C !C !C !C !C
!C
!C
!C!C
!C
90
NU-8
!C
!C
Figure 6.1
Capital Improvement!C !C
Program
Storm Drainage System Master Plan
City of Gilroy5GIS
0 0.25 0.5 1
Updated: April 15, 2022 Mile
File Path: P:\xGIS\GIS_Projects\Gilroy\Storm\200626-MP\GL_Fig6-1_CIP_Scen2_041522.mxd
Agenda Item 9.3
Page 702 of 768
Table 6.2 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Suggested Cost
AllocationPipeline Improvements Infrastructure Costs Cost SharingImprov.
No.Alignment Limits Baseline
Constr. Costs Constr. Costs
Estimated Capital Improv.
CostsExisting
Diameter
(in)
New/Parallel/
Replace
Existing Future
Users
(%)
Diameter Length Unit Cost Infr. Cost Existing Users Future usersUsers
(in)(ft)($/lf)($)($)($)($)(%)($)($)
Ronan Channel Drainage Area
RC-1
RC-2
RC-3
RC-4
RC-5
RC-6
RC-7
RC-8
RC-9
Sunrise Dr
Mantelli Dr
Zamzow Ct
Cohansey Ave
Murray Ave
Murray Ave
From Dream Catcher Way to Golden Sky Way
From Muir Drive to Delta Dr
18
18
-
Replacement
Replacement
New
30
24
48
48
48
48
36
48
42
400
1,250
1,200
1,450
2,800
600
302
245
489
489
489
489
358
489
414
120,601
306,506
586,990
709,280
1,369,643
293,495
1,216,516
1,675,367
62,114
121,000
307,000
587,000
710,000
1,370,000
294,000
1,217,000
1,676,000
63,000
158,000
400,000
764,000
923,000
1,781,000
383,000
1,583,000
2,179,000
82,000
206,000
520,000
100%
100%
8%
0%
0%
206,000
520,000
74,621
0
0
0
From approx. 1,250' n/o Cohansey Ave to
Cohansey Ave
From approx. 350' e/o Monterey Rd to Murray
Ave
994,000 92%
100%
91%
87%
9%
919,379
1,200,000
2,096,660
430,822
182,080
605,415
14,341
-New 1,200,000
2,316,000
498,000
0%
From Cohansey Ave to Tomkins Ct
From Tomkins Ct to Ronan Channel
-New 9%219,340
67,178
1,875,920
2,227,585
92,659
24
-
Replacement
New
13%
91%
79%
87%
No Name Uno/Las Animas From approx. 1,500' s/o Buena Vista Ave to San 3,400
3,425
150
2,058,000
2,833,000
107,000
Ave Ysidro Ave
From Las Animas Ave to approx. 500' n/o
Leavesley Rd
From approx. 220' e/o Forest St to approx. 360'
e/o Forest St
San Ysidro Ave -New 21%
13%Leavesley Rd 18 Replacement
Subtotal - Ronan Channel Drainage Area 6,345,000 8,253,000 10,732,000 5,283,303 5,448,697
Miller Slough Drainage Area
MS-1
MS-2
MS-3
MS-4
MS-5
MS-6
Wren Ave
First St
From approx. 290' n/o First St to Lawrence Dr
From approx. 180' e/o Princevalle St to Sargent St
From First St to Broadway
24
18
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
30
24
24
30
30
27
2,325
525
302
245
245
302
302
283
700,991
128,732
104,212
324,114
120,601
190,847
701,000
129,000
105,000
325,000
121,000
191,000
912,000
168,000
137,000
423,000
158,000
249,000
1,186,000
219,000
179,000
550,000
206,000
324,000
100%
100%
100%
100%
100%
100%
0%
0%
0%
0%
0%
0%
1,186,000
219,000
179,000
550,000
206,000
324,000
0
0
0
0
0
0
Sargent St
Broadway
Church St
Monterey Rd
18 425
From Sargent St to Church St 18/21
21
1,075
400From Broadway to approx. 100' s/o Howson St
From Second St to First St 18/24 675
Subtotal - Miller Slough Drainage Area 1,572,000 2,047,000 2,664,000 2,664,000 0
North Uvas Drainage Area
From approx. 3,080' w/o Santa Teresa Blvd to
approx. 360' w/o Santa Teresa Blvd
From approx. 360' w/o Santa Teresa Blvd to
Santa Teresa Blvd
From approx. 70' s/o Hecker Pass Hwy to Uvas
Creek
NU-1
NU-2
NU-3
NU-4
Hecker Pass Hwy
Hecker Pass Hwy
Santa Teresa Blvd
Westwood Dr
-New 30
30
30
24
2,825
350
302
302
302
245
851,742
105,526
776,367
104,212
852,000
106,000
777,000
105,000
1,108,000
138,000
1,441,000
180,000
0%
0%
100%
100%
100%
0%
0 1,441,000
180,000
1,315,000
0
24
24
18
Replacement
Replacement
Replacement
0
02,575
425
1,011,000
137,000
1,315,000
179,000
0%
From approx. 150' s/o Third St to Kentwood Ct 100%179,000
Agenda Item 9.3
Page 703 of 768
Table 6.2 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Suggested Cost
AllocationPipeline Improvements Infrastructure Costs Cost SharingImprov.
No.Alignment Limits Baseline
Constr. Costs Constr. Costs
Estimated Capital Improv.
CostsExisting
Diameter
(in)
New/Parallel/
Replace
Existing Future
Users
(%)
Diameter Length Unit Cost Infr. Cost Existing Users Future usersUsers
(in)(ft)($/lf)($)($)($)($)(%)($)($)
NU-5
NU-6
NU-7
NU-8
Monterey Rd
Monterey Rd
ROW
From Princevalle Channel to Victoria Dr -
42
-
New
Replacement
New
90
90
90
90
775
2,175
975
928
928
928
928
718,859
2,017,443
904,371
927,560
719,000 935,000 1,216,000 100%
100%
100%
100%
0%
0%
0%
0%
1,216,000 0
From Victoria Dr to approx. 950' n/o Farman Ln 2,018,000
905,000
928,000
2,624,000
1,177,000
1,207,000
3,412,000
1,531,000
1,570,000
3,412,000
1,531,000
1,570,000
0
0
0
From Monterey Rd to approx. 970' n/o Uvas
Creek
ROW From approx. 970' n/o Uvas Creek to Uvas Creek -New 1,000
Subtotal - North Uvas Drainage Area 6,410,000 8,337,000 10,844,000 7,908,000 2,936,000
South Uvas Drainage Area
From Carnoustie Ct to approx. 380' nw/o
Carnoustie CtSU-1 St Andrews Cir 18 Replacement 36 375 358 134,175 135,000 176,000 229,000 100%0%229,000 0
Subtotal - South Uvas Drainage Area 135,000 176,000 229,000 229,000 0
Princevalle Drainage Area
PR-1
PR-2
PR-3
PR-4
PR-5
PR-6
PR-7
PR-8
PR-9
PR-10
PR-11
PR-12
PR-13
Third St
Third St
From Santa Paula Dr to Wren Ave 27
27
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
New
30
42
48
48
48
48
48
30
54
24
24
48
48
825
675
302
414
489
489
489
489
489
302
545
245
245
489
489
248,739
279,515
97,832
249,000
280,000
98,000
324,000
364,000
128,000
605,000
431,000
255,000
796,000
491,000
870,000
264,000
201,000
1,575,000
494,000
422,000
474,000
167,000
787,000
561,000
332,000
1,035,000
639,000
1,131,000
344,000
262,000
2,048,000
643,000
100%
100%
100%
100%
100%
100%
100%
100%
100%
84%
0%
0%
0%
0%
0%
0%
0%
0%
0%
16%
11%
0%
0%
422,000
474,000
167,000
787,000
561,000
332,000
1,035,000
639,000
1,131,000
288,575
234,103
2,048,000
643,000
0
From Wren Ave to approx. 170' e/o Santa
Theresa Dr
From approx. 170' e/o Santa Theresa Dr to Santa
Theresa Dr
0
Third St 27 200 0
Santa Theresa Dr
ROW
From Third St to approx. 300' s/o Fourth St
From Santa Theresa Dr to Miller Ave
From approx. 300' s/o Fourth St to Fifth St
From Miller Ave to Princevalle St
From Third St to Fifth St
27/30
30
950 464,700
330,182
195,663
611,448
376,877
668,183
202,294
153,253
1,210,667
379,098
465,000
331,000
196,000
612,000
377,000
669,000
203,000
154,000
1,211,000
380,000
0
675 0
Miller Ave
Fifth St
30 400 0
30 1,250
1,250
1,225
825
0
Princevalle St
Princevalle St
Alexander St
Banes Ln
18 0
From Fifth St to Seventh St 42 0
55,425
27,897
0
From Tenth St to Banes Ln 18
From Alexander St to Automall Pkwy
From approx. 380' n/o 8th St to Angra Way
From Angra Way to Princevalle Channel
18 625 89%
Monterey Rd
Monterey Rd
-2,475
775
100%
100%42 Replacement 0
Subtotal - Princevalle Drainage Area 5,225,000 6,798,000 8,845,000 8,761,678 83,322
Agenda Item 9.3
Page 704 of 768
Table 6.2 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Suggested Cost
AllocationPipeline Improvements Infrastructure Costs Cost SharingImprov.
No.Alignment Limits Baseline
Constr. Costs Constr. Costs
Estimated Capital Improv.
CostsExisting
Diameter
(in)
New/Parallel/
Replace
Existing Future
Users
(%)
Diameter Length Unit Cost Infr. Cost Existing Users Future usersUsers
(in)(ft)($/lf)($)($)($)($)(%)($)($)
Lower Miller Slough Drainage Area
LM-1
LM-2
LM-3
LM-4
LM-5
LM-6
Fourth St
Monterey Rd
Monterey Rd
Monterey Rd
ROW
From Eigleberry St to Monterey Rd
From Fourth St to Sixth St
18
27
27
33
18
24
Replacement
Replacement
Replacement
Replacement
Replacement
Replacement
30
36
42
42
24
36
400
1,250
425
302
358
414
414
245
358
120,601
447,248
175,991
320,924
275,855
465,138
121,000
448,000
176,000
321,000
276,000
466,000
158,000
583,000
229,000
418,000
359,000
606,000
206,000
758,000
298,000
544,000
467,000
788,000
100%
100%
100%
100%
100%
100%
0%
0%
0%
0%
0%
0%
206,000
758,000
298,000
544,000
467,000
788,000
0
0
0
0
0
0
From Sixth St to Hornlein Ct
From Hornlein Ct to approx. 240' n/o Eighth St
From Rosanna St to Monterey Rd
From Sixth St to Eighth St
775
1,125
1,300Alexander St
Subtotal - Lower Miller Slough Drainage Area 1,808,000 2,353,000 3,061,000 3,061,000 0
Total Costs
Subtotal - Ronan Channel Drainage Area
Subtotal - Miller Slough Drainage Area
Subtotal - North Uvas Drainage Area
Subtotal - South Uvas Drainage Area
Subtotal - Princevalle Drainage Area
Subtotal - Lower Miller Slough Drainage Area
6,345,000 8,253,000 10,732,000
1,572,000 2,047,000 2,664,000
6,410,000 8,337,000 10,844,000
5,283,303
2,664,000
7,908,000
229,000
5,448,697
0
2,936,000
135,000 176,000 229,000 0
83,322
0
5,225,000 6,798,000 8,845,000
1,808,000 2,353,000 3,061,000
8,761,678
3,061,000
Total Improvement Costs 21,495,000 27,964,000 36,375,000 27,906,981 8,468,019
3/29/2023
Notes:
1. Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,176 for March 2023
2. Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.
3. Estimated construction cost plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal costs.
Agenda Item 9.3
Page 705 of 768
6.3.3 Recommended Cost Allocation Analysis
Cost allocation analysis is needed to identify improvement funding sources, and to establish a
nexus between development impact fees and improvements needed to service growth. In
compliance with the provisions of Assembly Bill AB 1600, the analysis differentiates between the
project needs of servicing existing users and for those required to service anticipated future
developments. Table 6.2 lists each improvement and separates the cost by responsibility between
existing and future users. The cost responsibility is based on model parameters for existing and
future land use, and may change depending on the nature of development.
March 2023 6-9 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 706 of 768
2023City of Gilroy
APPENDIX A
Hydrology Review
March 2023 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 707 of 768
RC001 RC058
RC056
RC005A RC084RC005DRC062
RC060
NU002A RC085RC082RC003RC005B
RC008
RC005CRC004
RC066 RC086RC006
RC007
RC064 RC064A
RC054
RC055
RC002
RC011
RC050A RC067
RC068
RC019 RC090
RC088RC024
RC013 RC019A RC009
RC025RC018 RC020
RC023
RC083
RC074
RC012 RC068ARC050BRC050NU004C
NU004B RC016 RC026
RC028 RC051RC017
RC022 RC070RC052ARC052RC021A
RC021
MS100AMS100 RC072 RC098RC051BNU004A
NU004 MS092A RC092RC014
RC015
RC027
RC039RC014A
RC014B
RC051A MS092 MS100BMS100CMS104MS092BNU006RC036
RC032 RC038 MS098A
MS098
MS109 RC093RC046
RC048 MS091 MS102
MS106
RC099
RC100NU005RC030NU009 RC110
RC106RC044
RC031 RC044A
RC043 MS090MS090A MS096RC029 MS110NU012 RC100A
MS120
RC112ANU010RC042MS108NU019
NU020
MS082 MS107MS094RC041 MS116 RC102 RC112 RC114NU011NU013
NU015
RC040NU016
NU017
MS107A
MS115
MS086
NU023
NU022
MS122MS130PR005PR004 MS124 RC116RC120
RC118
NU014 PR020NU018 NU021 NU028 PR002 PR008
PR006 LM020 MS128MS126
MS126A
MS128A
RC108
NU024
NU026
NU030
MS132
LM022SU008SU033 RC121SU011SU020
SU021
PR010
PR014
NU032
PR012 LM021 LM030
LM028
LM032
RC123
SU030A
SU030
SU042A
SU042B PR016
PR024
PR022 PR028 LM035
LM038
LM040SU032LM024SU010RC122SU050SU018SU036SU038SU040SU014SU059NU034PR026SU042LM037
PR085SU036A
SU035A
SU035
PR034 PR066
PR068
SU028 PR051
PR052
SU048 PR032
PR040A PR036
PR084
LM033SU002SU026
SU034
PR031
PR030
LM042SU069
SU060 PR098SU046PR054PR063
PR071
PR070
PR086
PR075
PR091
PR080PR090PR061
PR055
PR054A
PR062
SU012 SU058 SU070 PR040 PR046PR050
PR042 LM046
LM054PR044
NU038
NU043
PR064
LM044SU044SU057
SU056
NU036 PR047 PR078SU068 LM052PR053 NU042 PR076
PR074SU071SU084A
SU084B LM050
LL050
SU067 NU040SU024SU084 LL042 LL051SU088SU080NU045SU083A
SU079
LL044SU074SU083SU055NU040ASU076 LL048SU080ALL046SU066NU048
SU078 NU050SU091
SU092
LL047
SU096
SU098 NU052 NU053SU072
SU100
SU090
Legend
10-Year Yield (CFS/ACRE)
Hydrology Subcatchments
10 YEAR YIELD CFS/ACRE ≤0.59
≤0.69
≤0.86
0 2,000 4,000
Feet≤0.26
≤0.43
1 inch equals 4,000 feet
Agenda Item 9.3
Page 708 of 768
2023City of Gilroy
APPENDIX B
Storm Drainage Area Hydrologic Routing
March 2023 City of Gilroy
Storm Drainage System Master Plan
Agenda Item 9.3
Page 709 of 768
LEGENDPR002
PR008
PR004
PR020 Flow Combination
PR014 PR010
Hydrologic Sub-
catchment AreaPR002PR006
PR094 PR100PR018PR016PR012
PR022
PR072 PR076PR026PR024
PR090
PR028 PR096PR074
PR034 PR030 PR032
PR098
PR092
PR058
PR042 PR036
PR056
PR088
PR060 PR066
PR064PR040 PR068
PR082
PR078
PR038
PR044
PR054
Princevalle DrainagePR048PR062PR102
Area
Storm Drainage System Master
PlanPrincevalle Channel
City of Gilroy
PR046 PR050 PR052 PR070 PR080 PR084 PR086
March 3, 2022
Agenda Item 9.3
Page 710 of 768
LEGENDNU002NU004NU006NU060NU062
Flow CombinationNU008
Hydrologic Sub-
catchment AreaNU002
NU012 NU010
NU014 NU016
NU064NU030NU018NU020NU028
NU066NU032
NU036
NU034
NU068
NU070
NU038
NU040
NU024
NU022
NU072
NU074NU048
NU054NU042
NU050NU044 NU076NU026NU058
North Uvas DrainageNU046NU052NU056
Area
Storm Drainage System Master
Plan
City of Gilroy
North Uvas Creek
March 4, 2022
Agenda Item 9.3
Page 711 of 768
LEGEND
Flow CombinationLM006LM002LM008
LM026 Hydrologic Sub-
catchment AreaLM002LM004
LM024
LM012 LM010
LM032 LM036
LM014
LM020 LM022 LM028
LM034
LM038
LM016
LM018
LM030
Lower Miller Slough
Drainage Area
Storm Drainage System Master
PlanLower Miller Slough City of Gilroy
March 4, 2022
Agenda Item 9.3
Page 712 of 768
LEGEND
Flow Combination
LL004 LL008 Hydrologic Sub-
catchment AreaLL002
LL006 LL002
LL014 LL012 LL010
LL016
Llagas Drainage Area
Storm Drainage System Master
Plan
City of Gilroy
Llagas Creek
March 4, 2022
Agenda Item 9.3
Page 713 of 768
LEGEND
MS004 MS006 Flow CombinationMS008
MS018 MS016 MS012
Hydrologic Sub-
catchment AreaMS002
MS066
MS030MS002 MS068MS062
MS028
MS032
MS010
MS014
MS038
MS064
MS036
MS034
MS042
MS022
MS020 MS050 MS054
MS044
MS046 MS060
MS052MS024
MS026
MS048
Miller SloughMS056MS058
MS040 Drainage Area
Storm Drainage System Master
Plan
City of Gilroy
Miller Slough
March 8, 2022
Agenda Item 9.3
Page 714 of 768
LEGENDRC016RC014
RC178 Flow Combination
RC162
RC014 RC012 RC006 RC002 RC180
RC182
RC186
Hydrologic Sub-
catchment AreaRC002
RC164
RC166
RC168
RC010 RC008 RC004
RC146
RC148 RC184
RC188
RC190
RC118
RC170
RC120
RC130
RC018 - RC114
(See Ronan Channel Drainage Area
- 2)
RC122 RC192
RC158
RC132
RC136
RC196
RC160
RC134
RC194RC138
RC140RC124
RC156
RC176RC152
RC144
RC142
RC128
RC174
RC172
RC150
Ronan Channel
Drainage Area -1
Storm Drainage System Master
Plan
RC116
RC126
RC154
City of Gilroy
Ronan Channel
March 4, 2022
Agenda Item 9.3
Page 715 of 768
LEGEND
RC028
RC034
RC026 RC024 RC018 RC060 RC062 Flow Combination
Hydrologic Sub-
catchment AreaRC002
RC030 RC032
RC076 RC098
RC068
RC078
RC080
RC020 RC070 RC096
RC094
RC022 RC064
RC072
RC036
RC074
RC082
RC084
RC086
RC038
RC092
RC090RC050RC040
RC042
RC054
RC048
RC052
RC088
RC058
RC056RC044
RC046 RC100
RC102
RC106
RC108RC112
RC104
RC110 RC114
Ronan Channel
Drainage Area -2
Storm Drainage System Master
Plan
City of Gilroy
Ronan Channel
March 4, 2022
Agenda Item 9.3
Page 716 of 768
LEGENDSU040SU044SU066
Flow CombinationSU042SU068
SU062
SU086
SU088
SU092
Hydrologic Sub-
catchment AreaSU002
SU034 SU032
SU094
SU096
SU038 SU064
SU054
SU084
SU090
SU108
SU036 SU056
SU058
SU008 SU026 SU098
SU112
SU048
SU050
SU046
SU022
SU018
SU010
SU014
SU060
SU110SU020
SU024
SU028
SU052
SU078
SU120
SU016
SU114
SU070 SU072
SU004 SU030 SU100SU116
SU012
SU102
SU122
SU074
SU080
SU104 SU118
SU006
SU106 South Uvas Drainage
Area
Storm Drainage System Master
Plan
SU082
SU076SU002
City of Gilroy
South Uvas Creek
March 9, 2022
Agenda Item 9.3
Page 717 of 768
Table 6.2 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Existing
Diameter
New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost
Existing
Users
Future
Users Existing Users Future users
(in)(in)(ft)($/lf)($)($)($)($)(%)(%)($)($)
Ronan Channel Drainage Area
RC-1 Sunrise Dr From Dream Catcher Way to Golden Sky Way 18 Replacement 30 400 302 120,601 121,000 158,000 206,000 100% 0% 206,000 0
RC-2 Mantelli Dr From Muir Drive to Delta Dr 18 Replacement 24 1,250 245 306,506 307,000 400,000 520,000 100% 0% 520,000 0
RC-3 Zamzow Ct From approx. 1,250' n/o Cohansey Ave to
Cohansey Ave -New 48 1,200 489 586,990 587,000 764,000 994,000 8% 92% 74,621 919,379
RC-4 Cohansey Ave From approx. 350' e/o Monterey Rd to Murray
Ave -New 48 1,450 489 709,280 710,000 923,000 1,200,000 0% 100% 0 1,200,000
RC-5 Murray Ave From Cohansey Ave to Tomkins Ct -New 48 2,800 489 1,369,643 1,370,000 1,781,000 2,316,000 9% 91% 219,340 2,096,660
RC-6 Murray Ave From Tomkins Ct to Ronan Channel 24 Replacement 48 600 489 293,495 294,000 383,000 498,000 13% 87% 67,178 430,822
RC-7 No Name Uno/Las Animas
Ave
From approx. 1,500' s/o Buena Vista Ave to San
Ysidro Ave -New 36 3,400 358 1,216,516 1,217,000 1,583,000 2,058,000 91% 9% 1,875,920 182,080
RC-8 San Ysidro Ave From Las Animas Ave to approx. 500' n/o
Leavesley Rd -New 48 3,425 489 1,675,367 1,676,000 2,179,000 2,833,000 79% 21% 2,227,585 605,415
RC-9 Leavesley Rd From approx. 220' e/o Forest St to approx. 360'
e/o Forest St 18 Replacement 42 150 414 62,114 63,000 82,000 107,000 87% 13% 92,659 14,341
Subtotal - Ronan Channel Drainage Area 6,345,000 8,253,000 10,732,000 5,283,303 5,448,697
Miller Slough Drainage Area
MS-1 Wren Ave From approx. 290' n/o First St to Lawrence Dr 24 Replacement 30 2,325 302 700,991 701,000 912,000 1,186,000 100% 0% 1,186,000 0
MS-2 First St From approx. 180' e/o Princevalle St to Sargent St 18 Replacement 24 525 245 128,732 129,000 168,000 219,000 100% 0% 219,000 0
MS-3 Sargent St From First St to Broadway 18 Replacement 24 425 245 104,212 105,000 137,000 179,000 100% 0% 179,000 0
MS-4 Broadway From Sargent St to Church St 18/21 Replacement 30 1,075 302 324,114 325,000 423,000 550,000 100% 0% 550,000 0
MS-5 Church St From Broadway to approx. 100' s/o Howson St 21 Replacement 30 400 302 120,601 121,000 158,000 206,000 100% 0% 206,000 0
MS-6 Monterey Rd From Second St to First St 18/24 Replacement 27 675 283 190,847 191,000 249,000 324,000 100% 0% 324,000 0
Subtotal - Miller Slough Drainage Area 1,572,000 2,047,000 2,664,000 2,664,000 0
North Uvas Drainage Area
NU-1 Hecker Pass Hwy From approx. 3,080' w/o Santa Teresa Blvd to
approx. 360' w/o Santa Teresa Blvd -New 30 2,825 302 851,742 852,000 1,108,000 1,441,000 0% 100% 0 1,441,000
NU-2 Hecker Pass Hwy From approx. 360' w/o Santa Teresa Blvd to
Santa Teresa Blvd 24 Replacement 30 350 302 105,526 106,000 138,000 180,000 0% 100% 0 180,000
NU-3 Santa Teresa Blvd From approx. 70' s/o Hecker Pass Hwy to Uvas
Creek 24 Replacement 30 2,575 302 776,367 777,000 1,011,000 1,315,000 0% 100% 0 1,315,000
NU-4 Westwood Dr From approx. 150' s/o Third St to Kentwood Ct 18 Replacement 24 425 245 104,212 105,000 137,000 179,000 100% 0% 179,000 0
Cost Sharing
Baseline
Constr. Costs
Estimated
Constr. Costs
Capital Improv.
Costs
Improv.
No.Alignment Limits
Pipeline Improvements Infrastructure Costs Suggested Cost
Allocation
Agenda Item 9.3
Page 718 of 768
Table 6.2 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Existing
Diameter
New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost
Existing
Users
Future
Users Existing Users Future users
(in)(in)(ft)($/lf)($)($)($)($)(%)(%)($)($)
Cost Sharing
Baseline
Constr. Costs
Estimated
Constr. Costs
Capital Improv.
Costs
Improv.
No.Alignment Limits
Pipeline Improvements Infrastructure Costs Suggested Cost
Allocation
NU-5 Monterey Rd From Princevalle Channel to Victoria Dr -New 90 775 928 718,859 719,000 935,000 1,216,000 100% 0% 1,216,000 0
NU-6 Monterey Rd From Victoria Dr to approx. 950' n/o Farman Ln 42 Replacement 90 2,175 928 2,017,443 2,018,000 2,624,000 3,412,000 100% 0% 3,412,000 0
NU-7 ROW From Monterey Rd to approx. 970' n/o Uvas
Creek -New 90 975 928 904,371 905,000 1,177,000 1,531,000 100% 0% 1,531,000 0
NU-8 ROW From approx. 970' n/o Uvas Creek to Uvas Creek -New 90 1,000 928 927,560 928,000 1,207,000 1,570,000 100% 0% 1,570,000 0
Subtotal - North Uvas Drainage Area 6,410,000 8,337,000 10,844,000 7,908,000 2,936,000
South Uvas Drainage Area
SU-1 St Andrews Cir From Carnoustie Ct to approx. 380' nw/o
Carnoustie Ct 18 Replacement 36 375 358 134,175 135,000 176,000 229,000 100% 0% 229,000 0
Subtotal - South Uvas Drainage Area 135,000 176,000 229,000 229,000 0
Princevalle Drainage Area
PR-1 Third St From Santa Paula Dr to Wren Ave 27 Replacement 30 825 302 248,739 249,000 324,000 422,000 100% 0% 422,000 0
PR-2 Third St From Wren Ave to approx. 170' e/o Santa
Theresa Dr 27 Replacement 42 675 414 279,515 280,000 364,000 474,000 100% 0% 474,000 0
PR-3 Third St From approx. 170' e/o Santa Theresa Dr to Santa
Theresa Dr 27 Replacement 48 200 489 97,832 98,000 128,000 167,000 100% 0% 167,000 0
PR-4 Santa Theresa Dr From Third St to approx. 300' s/o Fourth St 27/30 Replacement 48 950 489 464,700 465,000 605,000 787,000 100% 0% 787,000 0
PR-5 ROW From Santa Theresa Dr to Miller Ave 30 Replacement 48 675 489 330,182 331,000 431,000 561,000 100% 0% 561,000 0
PR-6 Miller Ave From approx. 300' s/o Fourth St to Fifth St 30 Replacement 48 400 489 195,663 196,000 255,000 332,000 100% 0% 332,000 0
PR-7 Fifth St From Miller Ave to Princevalle St 30 Replacement 48 1,250 489 611,448 612,000 796,000 1,035,000 100% 0% 1,035,000 0
PR-8 Princevalle St From Third St to Fifth St 18 Replacement 30 1,250 302 376,877 377,000 491,000 639,000 100% 0% 639,000 0
PR-9 Princevalle St From Fifth St to Seventh St 42 Replacement 54 1,225 545 668,183 669,000 870,000 1,131,000 100% 0% 1,131,000 0
PR-10 Alexander St From Tenth St to Banes Ln 18 Replacement 24 825 245 202,294 203,000 264,000 344,000 84% 16% 288,575 55,425
PR-11 Banes Ln From Alexander St to Automall Pkwy 18 Replacement 24 625 245 153,253 154,000 201,000 262,000 89% 11% 234,103 27,897
PR-12 Monterey Rd From approx. 380' n/o 8th St to Angra Way -New 48 2,475 489 1,210,667 1,211,000 1,575,000 2,048,000 100% 0% 2,048,000 0
PR-13 Monterey Rd From Angra Way to Princevalle Channel 42 Replacement 48 775 489 379,098 380,000 494,000 643,000 100% 0% 643,000 0
Subtotal - Princevalle Drainage Area 5,225,000 6,798,000 8,845,000 8,761,678 83,322
Agenda Item 9.3
Page 719 of 768
Table 6.2 Capital Improvement Program
Storm Drainage System Master Plan
City of Gilroy
Existing
Diameter
New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost
Existing
Users
Future
Users Existing Users Future users
(in)(in)(ft)($/lf)($)($)($)($)(%)(%)($)($)
Cost Sharing
Baseline
Constr. Costs
Estimated
Constr. Costs
Capital Improv.
Costs
Improv.
No.Alignment Limits
Pipeline Improvements Infrastructure Costs Suggested Cost
Allocation
Lower Miller Slough Drainage Area
LM-1 Fourth St From Eigleberry St to Monterey Rd 18 Replacement 30 400 302 120,601 121,000 158,000 206,000 100% 0% 206,000 0
LM-2 Monterey Rd From Fourth St to Sixth St 27 Replacement 36 1,250 358 447,248 448,000 583,000 758,000 100% 0% 758,000 0
LM-3 Monterey Rd From Sixth St to Hornlein Ct 27 Replacement 42 425 414 175,991 176,000 229,000 298,000 100% 0% 298,000 0
LM-4 Monterey Rd From Hornlein Ct to approx. 240' n/o Eighth St 33 Replacement 42 775 414 320,924 321,000 418,000 544,000 100% 0% 544,000 0
LM-5 ROW From Rosanna St to Monterey Rd 18 Replacement 24 1,125 245 275,855 276,000 359,000 467,000 100% 0% 467,000 0
LM-6 Alexander St From Sixth St to Eighth St 24 Replacement 36 1,300 358 465,138 466,000 606,000 788,000 100% 0% 788,000 0
Subtotal - Lower Miller Slough Drainage Area 1,808,000 2,353,000 3,061,000 3,061,000 0
Total Costs
Subtotal - Ronan Channel Drainage Area 6,345,000 8,253,000 10,732,000
5,283,303 5,448,697
Subtotal - Miller Slough Drainage Area 1,572,000 2,047,000 2,664,000
2,664,000 0
Subtotal - North Uvas Drainage Area 6,410,000 8,337,000 10,844,000
7,908,000 2,936,000
Subtotal - South Uvas Drainage Area 135,000 176,000 229,000
229,000 0
Subtotal - Princevalle Drainage Area 5,225,000 6,798,000 8,845,000
8,761,678 83,322
Subtotal - Lower Miller Slough Drainage Area 1,808,000 2,353,000 3,061,000
3,061,000 0
Total Improvement Costs 21,495,000 27,964,000 36,375,000 27,906,981 8,468,019
Notes:
3/29/2023
1. Cost estimates are based on the Engineering News Record (ENR) construction cost index (CCI) of 13,176 for March 2023
2. Baseline construction costs plus 30% to account for unforeseen events and unknown conditions.
3. Estimated construction cost plus 30% to cover other costs including: engineering design, project administration (developer and City staff), construction management and inspection, and legal costs.
Agenda Item 9.3
Page 720 of 768
3
2
9
RESOLUTION NO. 2023-XX
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF
GILROY ADOPTING THE STORM DRAINAGE SYSTEM
MASTER PLAN FOR THE CITY OF GILROY
WHEREAS, the 2022 Storm Drainage System Master (Plan) serves as a guide to
assess the current operations and functionality of the City’s existing storm drain system;
and
WHEREAS, the City last developed a Storm Drainage System Master Plan in
2004, which identified capacity deficiencies in the existing storm drain system and
recommended improvements to alleviate existing deficiencies and serve future
developments in the Gilroy Planning Area; and
WHEREAS, Akel Engineering Group, Inc. was retained by the City Council in
August 2019 to prepare the Plan; and
WHEREAS, the objective of the Plan is to review and make recommendations on
how the current sewer system can be upgraded within the City to best suit the sewer
needs of the City in the future; and
WHEREAS, the projects identified in the Plan will be added to the City’s Capital
Improvement Program; and
NOW, THEREFORE, BE IT RESOLVED that the City Council of the City of Gilroy
hereby adopts the Storm Drain System Master Plan attached hereto and made a part
hereof.
PASSED AND ADOPTED by the City Council of the City of Gilroy at a regular
meeting duly held on the 3rd day of April 2023 by the following roll call vote:
AYES:COUNCIL MEMBERS:
NOES:COUNCIL MEMBERS:
ABSTAIN:COUNCIL MEMBERS:
ABSENT:COUNCIL MEMBERS:
APPROVED:
Marie Blankley, Mayor
ATTEST:
______________________
Thai Nam Pham, City Clerk
Agenda Item 9.3
Page 721 of 768
Page 1 of 2
City of Gilroy
STAFF REPORT
Agenda Item Title:Appointment to City Boards, Commissions, and
Committees with Open Vacancies
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:City Clerk
Submitted By:Thai Nam Pham, City Clerk
Prepared By:Thai Nam Pham, City Clerk
STRATEGIC PLAN GOALS Not Applicable
RECOMMENDATION
Appoint members to Boards, Commissions, and Committees with open vacancies.
BACKGROUND
Five of the City’s Boards, Commissions, and Committees (Arts & Culture Commission,
Library Commission, Personnel Commission, Parks and Recreation Commission, and
Physically Challenged Board of Appeals) currently have seats vacant as of April 3,
2023. At the close of the recruitment period, no new applications were received for any
of the commissions and boards referenced above. Staff did receive notice of interest
from previous applicants Vincent Saso and Terrence Fugazzi for the Parks and
Recreation Commission with a term expiring December 31, 2023. On March 20, 2023,
staff received a letter of resignation from Parks and Recreation Commissioner Eric
Arredondo, leaving another seat vacant for a term ending on December 31, 2025. On
March 27, 2023, staff received a letter of resignation from Parks and Recreation
Commissioner Sergio Patterson, leaving another seat vacant for a term ending on
December 31, 2025.
The Council interviewed both applicants at the March 20, 2023 Regular Meeting. The
Council is now asked to consider their appointments to the Parks and Recreation
Commission.
Agenda Item 10.1
Page 722 of 768
Appointment to City Boards, Commissions, and Committees with Open Vacancies
City of Gilroy City Council Page 2 of 2 April 3, 20235
6
9
It should be noted that the City has previously adhered to a practice that did not allow
an individual board/commission/committee member to serve simultaneously as a
member of two different boards/commissions/committees. This was incorporated to
allow as many residents as possible to participate in advisory roles. Currently, there are
numerous commission vacancies, and Mr. Fugazzi has shown an interest in serving on
two commissions simultaneously. As there are no legal hurdles (and no apparent
conflicts of interest) to Mr. Fugazzi serving on two separate commissions
simultaneously, Council should consider his appointment to a second commission
should he be deemed a suitable appointee.
Attachments:
1. Parks and Recreation Application – Vincent Saso
2. Parks and Recreation Application – Terence Fugazzi
Agenda Item 10.1
Page 723 of 768
Agenda Item 10.1
Page 724 of 768
Agenda Item 10.1
Page 725 of 768
Agenda Item 10.1
Page 726 of 768
Agenda Item 10.1
Page 727 of 768
Page 1 of 4
City of Gilroy
STAFF REPORT
Agenda Item Title:Enhancing the Access to the Internet and Technology
for Gilroy’s Youth
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:Administration
Submitted By:Bryce Atkins, Assistant to the City Administrator
Prepared By:Bryce Atkins, Assistant to the City Administrator
STRATEGIC PLAN GOALS Not Applicable
RECOMMENDATION
Council provide direction.
BACKGROUND
This topic was discussed at the February 20, 2021 and March 29, 2021 special
meetings for strategic planning and the Council’s Legislative Agenda for Fiscal Year
2022 and Fiscal Year 2023. At these meetings, the topic was raised regarding
challenges for school children who, due to economic challenges, were not able to
access the internet to attend school virtually. Additional concerns that were raised
included businesses requiring a greater scope of accessibility to the internet for
business attraction, the challenges that were resolved at the Ochoa Camp to bring
internet to their site from the Sewer Treatment Plant so they could attend school, and
discussions about potential downtown Wi-Fi service being provided, and looking at the
potential for partnerships with Amazon and other possible partners in providing
services. There was also discussion about partnering with the County on a multi-
jurisdictional group to establish better internet access for communities in the County.
ANALYSIS
Assessing If There is a Continuing Need
Agenda Item 11.1
Page 728 of 768
Enhancing the Access to the Internet and Technology for Gilroy’s Youth
City of Gilroy City Council Page 2 of 4 April 3, 2023
At the time when this matter was discussed, the pandemic was fully underway and
classes by the Gilroy Unified School District (GUSD) were being held virtually. During
the pandemic and after the Legislative Agenda was adopted, GUSD invested
significantly to provide their students the technology and internet access to attend
school virtually. At this time, the classes are also back to in-person instruction,
lessening the critical need that was present at the time of the Legislative Agenda
adoption as it relates to youth access to attend classes. Additionally, since the adoption
of the Legislative Agenda, Frontier Communications has submitted plans and has
begun deploying a citywide fiber optic network, which will enhance the speeds and
bandwidth for internet service in the community.
There are no set metrics available to the City to provide a defined level of access to
technology, nor a detailed description of what technology or technological services may
be lacking. As such, staff is not able to provide a quantitative or qualitative analysis on
this topic to advise Council on the level of need present in the community.
While the newer developments may not address those currently experiencing economic
challenges and an ability to pay for high-speed internet, the question is if this is
something the City should be involved in addressing, and if so, to what extent.
Possible City Actions
Council could determine that a market failure is present. As staff has begun a cursory
analysis of this topic, there are many different approaches that the City could undertake.
Before spending significant staff time and resources to vet every option thoroughly, staff
wishes to gain Council consensus on what levels of financial and operational
commitment it is willing to consider. This will help determine if there are options that are
not to be evaluated to allow a greater focus on other areas. The options that have been
identified are broken down into the following three categories based on financial and
operational commitment.
Direct Service Provision
This would involve the City in directly providing the service. This may take several
forms. For example, some cities provide regional Wi-Fi access for free, such as in
downtown areas or designated zones. Others provide internet access by providing the
infrastructure, such as a fiber optic data network, and charge for services similar to
other utilities (water, sewer, etc.).
These types of direct services carry a higher cost than the other categories and require
higher commitments of operational resources and staff time. This category is also likely
to result in the highest level of dependency on the service and present a higher level of
risk of abuse of the service. This category does, however, provide the most control over
providing equitable access to technology. Depending upon the type of service being
provided, fair rates within the service and competitive rates compared to market
services would need to be analyzed.
Agenda Item 11.1
Page 729 of 768
Enhancing the Access to the Internet and Technology for Gilroy’s Youth
City of Gilroy City Council Page 3 of 4 April 3, 2023
Direct provision of service is typically made when there is a market failure, which is a
need where the services available in the market are either unable to provide service
adequate to meet the need, the cost of the service in the private market is too great for
a need that is fundamental to health and safety, or where a private company is not a
proper source to provide the service. These typically are heavily regulated services or
needs involving health and safety, such as fire, police, emergency medical, public
health, and other services where it is not in the best interest of the public to rely on
private companies for the service or to achieve cost savings for all members utilizing
such a service.
Subsidization
The Council may also consider providing a form of subsidy to either a service provider
to expand their services to areas that are not connected or directly to those currently
challenged to pay the costs associated with access to the internet to attempt to grant
additional access points for residents. This could take the form of a benefit provided to
others already on discounted utility or other services or some other program that
provides a stipend to provide the connection. The details of such a program, including
eligibility, amount, length of term, etc., will be an important element of any eventual
analysis should Council determine to pursue a program in this category.
This type of program has fewer financial and operational commitments than direct
service provision and produces less dependency as it respects scale but may produce
the same level of dependency at the individual level. The operational and staff time
costs are much reduced compared to direct service provision. Additionally, the chance
of liability is also reduced to nominal levels compared to direct service provision. The
level of ability to influence access to technology is reduced compared to direct service,
as it is dependent upon others to provide the access points.
Advocacy and Support
This category would include activities such as meeting with service providers to raise
concerns about access to the internet or other technology needs, as well as meeting
with non-profit organizations and other governmental agencies to see if collaboratives or
alternate service delivery models are possible to meet the need. The goal would be to
convince other organizations to either subsidize or directly provide the service for our
residents who lack access to technology.
This option would not require any financial support from the City but may require more
staff time than some subsidization options. There would be no financial commitments,
liability, or dependency on the City to maintain a service or program to retain residents’
access to technology. However, this category does not grant much, if any, ability to
directly influence the means or ability to access technology for our residents.
Workforce Ability to Take on Tasks
As evidenced in the recent strategic planning sessions and assessing the staffing levels
and work plans for the budget process, any activity listed above will need staff
resources to deliver. Direct Service Provision would require the most, while
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Enhancing the Access to the Internet and Technology for Gilroy’s Youth
City of Gilroy City Council Page 4 of 4 April 3, 2023
subsidization and advocacy will consume some staff time that may detract from current
Council priorities or mandated and core projects or services. Staff is recommending that
Council:
1. Determine if this is a need that will warrant the staff time to dig into deeper
analysis, let alone for carrying out the activity; then
2. If determined that the need warrants analysis of options, identify for staff what
category or types of programs Council wants to be evaluated and options
explored.
Staff will then, if the direction is to proceed into analysis, evaluate the options based on
Council feedback.
ALTERNATIVES
Council may provide direction to pursue or discontinue any work relating to policies or
activities relating to enhancing the access for Gilroy’s youth to the internet and
technology.
FISCAL IMPACT/FUNDING SOURCE
None. This report is seeking Council direction. Based upon the direction received, any
programs or projects proposed would be brought back to Council after analysis,
including a fiscal report at the time of Council consideration.
PUBLIC OUTREACH
This item was included in the publicly posted agenda for this meeting.
NEXT STEPS
Staff will take direction from Council, and if the direction is to analyze and report back
on a potential policy, program or project, staff will return to Council for consideration of
the same.
Agenda Item 11.1
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Page 1 of 3
City of Gilroy
STAFF REPORT
Agenda Item Title:Consideration of Creating a Job Protection Policy
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:Administration
Submitted By:Bryce Atkins, Assistant to the City Administrator
Prepared By:Bryce Atkins, Assistant to the City Administrator
STRATEGIC PLAN GOALS Not Applicable
RECOMMENDATION
Council provide direction.
BACKGROUND
At the February 20, 2021 and March 29, 2021 special meeting regarding strategic
planning and the formation of the City Council’s FY22 and FY23 Legislative Agenda, the
topic of a potential job protection policy was raised. The statements at those meetings
involving this subject included:
•Other cities in the County and State have such policies
•Helps workers during pandemics and recessions
•If a worker gets laid off, allows such workers to be first in line to be
retained/rehired
•If a company/contractor sells to another, would require new contractor to retain
the purchased company’s employees for a brief time period, 90 days was given
as an example
ANALYSIS
Staff has conducted research and found several cities that had adopted Right of Recall
Ordinances (ROROs). These ordinances were established as COVID responses to the
layoffs of service, tourism, and other industries impacted by the shutdowns as a
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Consideration of Creating a Job Protection Policy
City of Gilroy City Council Page 2 of 3 April 3, 2023
protection mechanism during the pandemic. Most of the ROROs found are from larger
cities, including cities such as San Diego, Los Angeles, San Francisco, and others.
These typically establish a timeframe from the point of layoff, usually within a few
months after layoff, to when they would have to be offered their position back before
recruitment could be done of a new employee. The laid-off employee would have five or
so days to accept the position, or the business could hire whomever they desire to
employ. Some of these ordinances, like San Diego’s, have sunset provisions where the
ordinance automatically ends (March 8, 2022, in this example). Others, like Los
Angeles’ ordinance, have a review report to determine if the ordinance’s provisions are
still necessary. In all of the ordinances reviewed, none appear to be designed to be
perpetual and only applied to layoffs or restructuring due to the pandemic stay-at-home
orders and impacts.
Later during the pandemic, the State of California enacted SB 93, which implemented
similar requirements state-wide. The law is still in effect and sunset on December 31,
2024, roughly a year and eight months from this meeting. The Bill requires that an
employer, as defined, offer its laid-off employees specified information about job
positions that become available that the laid-off employees are qualified for and to offer
positions to those laid-off employees based on a preference system. Positions that
qualify are those whose most recent separation from active service was due to a reason
related to the COVID-19 pandemic, including a public health directive, government
shutdown order, lack of business, a reduction in force, or other economic, non-
disciplinary reason related to the COVID-19 pandemic.
Based on the nature of these example ordinances and the current state law, staff
believes that there is not currently a need for this type of ordinance unless Council
desires to have these protections extend beyond December 31, 2024 timeframe or
wishes to have a policy cover conditions that are not contained in SB 93. If Council
wishes to proceed, depending upon what terms of the possible job protection ordinance
are being requested, a legal analysis will be needed to determine what is acceptable, as
well as what resources, both staff time and financial, are going to be expended to
monitor these conditions, what triggers the requirement, and what penalties for non-
compliance might be.
ALTERNATIVES
Council may direct staff to cease activity on this task or direct certain research or
actions to be undertaken to develop a job protection policy.
FISCAL IMPACT/FUNDING SOURCE
None. This item seeks Council direction before expending staff time on further detailed
research and policy development. No financial resources are anticipated to be spent.
Any fiscal impact of any proposed policy at the completion of this process would be
analyzed and reported at the recommendation of adopting such a policy.
Agenda Item 11.2
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Consideration of Creating a Job Protection Policy
City of Gilroy City Council Page 3 of 3 April 3, 2023
PUBLIC OUTREACH
This item was included in the publicly posted agenda for this meeting.
NEXT STEPS
Staff will take the Council’s direction, and either pursue or cease work on this potential
policy as it so directs.
Attachments:
1. California SB 93 adopted bill language.
Agenda Item 11.2
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Agenda Item 11.2
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Agenda Item 11.2
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Agenda Item 11.2
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Agenda Item 11.2
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Page 1 of 3
City of Gilroy
STAFF REPORT
Agenda Item Title:Review and Approve an Extension to the
Memorandum of Understanding and Related Salary
Schedules for the Gilroy Police Officers Association
for the Period Ending June 30, 2025
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:Administrative Services
Submitted By:LeeAnn McPhillips, Administrative Services and Human
Resources Director / Risk Manager
Prepared By:LeeAnn McPhillips, Administrative Services and Human
Resources Director / Risk Manager
STRATEGIC PLAN GOALS Not Applicable
RECOMMENDATION
1. Approve the Extension and Supplemental Agreement to the Memorandum of
Understanding with the Gilroy Police Officers Association for the Period Ending
June 30, 2025.
2. Adopt by Resolution the Salary Schedules Associated with the Gilroy Police
Officers Association Memorandum of Understanding/Supplemental Agreement
for the Period July 1, 2023 - June 30, 2025.
EXECUTIVE SUMMARY
The Gilroy Police Officers Association (GPOA) requested to engage in discussions with
the City regarding the terms of their current Memoranda of Understanding (MOU).
Although in a closed agreement, the City Council authorized City negotiators to hold
discussions with the GPOA because the GPOA had agreed to concessions during the
Covid recession and was the only labor group that did not discuss MOU terms following
the Covid recovery period. As a result of the discussions, a Supplemental Agreement to
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Review and Approve an Extension to the Memorandum of Understanding and Related Salary
Schedules for the Gilroy Police Officers Association for the Period Ending June 30, 2025.
City of Gilroy City Council Page 2 of 3 April 3, 2023
the GPOA Memorandum of Understanding is being presented to the City Council for
review and approval.
BACKGROUND
In 2020, as a result of the Covid recession, the GPOA agreed to financial concessions
that were memorialized in a Supplemental Agreement. Of note, the GPOA gave up a
four percent (4%) salary increase that was scheduled for July 1, 2020 and agreed to a
reduced salary increase from 4% to 3% for FY 22. In addition, the parties agreed to
extend the MOU for two additional years through June 30, 2024 with a 3% salary
increase each year.
At the beginning of the current fiscal year (FY 23), all the other labor groups reached
agreements on new labor contracts. These contracts focused on recruitment and
retention of employees and provided various salary and benefit improvements. As noted
above, the GPOA was the only group that did not negotiate a new MOU at the start of
FY 23 as the GPOA agreement was not scheduled to expire until June 30, 2024.
The GPOA Supplemental Agreement, like the other employee agreements approved
earlier this fiscal year, contain retention salary steps added to the upper end of the
salary schedule. These retention steps are designed to encourage employee retention
as the employee can only earn the retention steps through years of service and a good
employee performance evaluation.
The additional year added to the MOU provides important labor stability for the
organization. In addition, the employees know what salary increases are scheduled so
they can plan for the future. Also, the future salary increases are an important tool when
recruiting new Police Officers and Detention Services Officers as this information is
shared with job applicants and the future compensation increases are very attractive to
new hires.
ANALYSIS
The new Supplemental Agreement to the GPOA MOU being presented includes the
following changes:
•Term of MOU is extended for one year through June 30, 2025.
•The salary increases scheduled for FY 24 (1.5% - 7/1/23; 1.5% 1/1/24) are
deleted and replaced with a 4% increase effective 7/1/23.
•A 2.5% retention step (Step F) is added effective 1/1/24. To access this step the
employee must have one year at Step E, must have completed five years of
service, and must have a good performance evaluation.
•A 3% cost of living increase effective 7/1/24 (COLA).
Agenda Item 11.3
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Review and Approve an Extension to the Memorandum of Understanding and Related Salary
Schedules for the Gilroy Police Officers Association for the Period Ending June 30, 2025.
City of Gilroy City Council Page 3 of 3 April 3, 2023
•A 2.5% retention step (Step G) is added effective 1/1/25. To access this step the
employee must have one year at Step F, must have completed five years of
service, and must have a good performance evaluation.
•Added two new specialty assignments to qualify/requalify for the existing Master
Officer Program.
•Small increase ($2 per employee per month) to the City-paid portion of the Long-
Term Disability insurance program.
•Continue existing Retiree Medical Trust contributions through term of MOU.
FISCAL IMPACT/FUNDING SOURCE
The new cost associated with the Supplemental Agreement provisions is estimated to
be $225,000 for FY 24 and approximately $592,000 for FY 25. These amounts will be
included in the FY 24 and FY 25 budget that will be presented to Council in June 2023.
NEXT STEPS
Following Council approval of the Supplemental Agreement and related Salary
Schedules, City representatives will sign-off on the Supplemental Agreement document.
The two minor benefit changes will go into effect immediately (LTD & Master Officer
Program changes) while the salary changes included in the Agreement are not effective
until FY 24 and 25 and will not be implemented until the effective dates noted in the
Supplemental Agreement.
Attachments:
1. Gilroy Police Officers Association Supplemental Agreement – April 3, 2023
2. Salary Resolution and Related Salary Schedules for the period July 1, 2023 – June
30, 2025
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City of Gilroy/Gilroy Police Officers Association 2023
1
MEMORANDUM OF UNDERSTANDING EXTENSION
SUPPLEMENTAL AGREEMENT
EFFECTIVE UPON GILROY CITY COUNCIL APPROVAL
APRIL 3, 2023
At this time, the City of Gilroy (“City”) and the Gilroy Police Officers Association (“GPOA”)
have agreed to extend the current Memorandum of Understanding (MOU) for represented
employees and intend to maintain the terms of the MOU subject to the below changes. On a
non-precedent setting basis, the parties agreed to the below changes considering the
concessions that were agreed upon in 2020 because of Covid-19. Due to the prior GPOA MOU
extension with concessions, the GPOA was the only Gilroy labor group that did not have
formal negotiations with the City since the time of the 2020 concessions.
Approval of Parties
The terms of this Tentative Agreement are subject to final approval of the City Council. The
members of the GPOA approved the terms of this Tentative Agreement on February 23, 2023.
Term of Agreement
This Agreement shall be effective upon ratification and approval by the members of the GPOA
(occurred on February 23, 2023) and upon approval by the Gilroy City Council (scheduled for
April 3, 2023). The Term of the Memorandum of Understanding shall be extended from the
effective date through June 30, 2025.
Salaries
MOU Article IV, Sections A and B as amended by the Supplemental Agreement approved by
the Gilroy City Council on August 3, 2021, are amended as follows:
1. Effective the start of the pay period beginning July 1, 2021 the salaries for all
bargaining unit members (except those who are Y-rated) shall be increased by one and
one-half percent (1.5%).
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2. Effective the start of the pay period beginning January 1, 2022 the salaries for all
bargaining unit members (except those who are Y-rated) shall be increased by one and
one-half percent (1.5%).
3. Effective the start of the pay period beginning July 1, 2022 the salaries for all
bargaining unit members (except those who are Y-rated) shall be increased by one and
one-half percent (1.5%).
4. Effective the start of the pay period beginning January 1, 2023 the salaries for all
bargaining unit members (except those who are Y-rated) shall be increased by one and
one-half percent (1.5%).
5. Effective the start of the pay period beginning July 1, 2023 the salaries for all
bargaining unit members (except those who are Y-rated) shall be increased by one and
one-half percent (1.5%).
6. Effective the start of the pay period beginning January 1, 2024 the salaries for all
bargaining unit members (except those who are Y-rated) shall be increased by one
point five percent (1.5%).
5. Effective the start of the pay period beginning July 1, 2023 the salaries for all
bargaining unit members (except those who are Y-rated) shall be increased by three
percent (3%). In addition, effective the start of the pay period beginning July 1, 2023,
the salaries for all bargaining unit members (except those who are Y-rated) shall be
further increased by a one percent (1.0%) Equity Adjustment. (Exhibit A to this
Supplemental Agreement incorporates both the Salary and Equity Adjustment).
6. Effective the start of the pay period beginning July 1, 2024 the salaries for all
bargaining unit members (except those who are Y-rated) shall be increased by three
percent (3%). (Exhibit B to this Supplemental Agreement incorporates this Salary
Adjustment).
Retention Steps:
Step F (5 Years)
Effective January 1, 2024, the City will add a new Step F to the salary schedule for each
bargaining unit classification. Step F will be set approximately 2.5% higher than the
existing Step E. In addition to the normal requirements for Step Advancement (12
months of “meets standards” or better performance at Step E), an employee must have
completed five (5) years of service in the bargaining unit.
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City of Gilroy/Gilroy Police Officers Association 2023
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Employees who qualify for Step F as of January 1, 2024 (i.e., have both 5 years of service
and 12 months at Step E) will be eligible to advance to Step F on January 1, 2024. For
these employees, January 1 will become their new evaluation date. All other employees
will be eligible to advance to Step F on their regularly scheduled evaluation date.
b. Step G (5 Years)
Effective the first full pay period following January 1, 2025, the City will add a new Step
G to the salary schedule for each bargaining unit classification. Step G will be set
approximately 2.5% higher than the existing Step F. In addition to the normal
requirements for Step Advancement (12 months of “meets standards” or better
performance at Step F), an employee must have completed five (5) years of service in
the bargaining unit.
Employees will be eligible to advance to Step G on their regularly scheduled evaluation
date.
Master Officer Program:
1. Bargaining unit members who meet the following requirements shall receive a
5% Master Officer pay differential (5% of base pay only) in lieu of specialty pays.
2. Initial Program Requirements for any employee in this Unit wishing to join the
Master Officer Program.
a. Ten (10) years with Gilroy Police Department (GPD). Up to five (5) years of
the ten (10) year full-time classification requirement may be met by the
employee having held full-time employment in the same classification with
another law enforcement agency. The lateral time must be in the same
classification the employee holds with Gilroy Police Department.
b. Nine (9) years in designated specialties with GPD.
(1) Must have at least one (1) year each in at least three (3) different
specialties. MSO’s may qualify with two (2) different specialties.
(2) Specialty assignments must be at least one year in length to initially
qualify. Thereafter, partial years may count toward requalification.
(3) “Full time” specialties count one year per year of time in specialty. Officers
hired in as a lateral officer may count one full-time specialty from their
prior law enforcement agency subject to the review and acceptance by the
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City of Gilroy/Gilroy Police Officers Association 2023
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city at the city’s sole discretion. Lateral officers will be required to submit
written documentation for the City’s consideration.
(4) “Half time” specialties count one-half of year per year of time in specialty.
(5) “Quarter time” specialties count one-quarter of year per year of time
actively serving as an instructor in one or more of the areas noted below.
(6) Three (3) years of qualifying time must be full-time specialties (per the list
below). The City, at it’s sole discretion, may consider an application for
Master Officer with less than three years in full-time specialties when the
employee’s participation in the full-time specialty assignment ends prior
to three years as a result of budget reductions causing the specialty
assignment to be eliminated.
(7) Employee can simultaneously perform up to three (3) specialties.
(8) Supervisors coordinating specialty units who are also members of those
specialty units get credit for being a member of the specialty, or for being
the coordinator, but not for both simultaneously.
3. Qualifying Specialties:
a. Full Time
(1) Traffic
(2) Detectives
(3) SCCSET, RATTF, REACT, DEA, AB 109, or other full-time task force
position
(4) Canine
(5) School Resource Officer (SRO)
(6) Administration Sergeant (Internal Affairs, PIO, etc.)
(7) ACT
(8) FTO (not including Corporal)
Note: Employees who have at least one year as a Corporal prior
to 7/1/06 may use one year of Corporal time as FTO time for
Master Officer Program purposes.
(9) Community Engagement Team
b. Half Time
(1) CIRT (SOG & HNT)
(2) CSI
(3) Arson
(4) MAIT
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City of Gilroy/Gilroy Police Officers Association 2023
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(5) Firearms Instructor
(6) Defensive Tactics/Less Lethal Instructor
(7) Specialty Assignment Coordinators (including, but not limited to,
Reserves, MSO, CSI, FTO, etc.)
(8) Mounted Unit
(9) Honor Guard
(10) Drug Recognition Expert
(11) Electronic Forensic Examiner
(11)(12) Drone Unit
c. Quarter Time
(1) First Aid/CPR Instructor
(2) Driving Instructor
(3) Explorer Advisor
(4) Critical Incident Stress Debrief (CISD) Team Member
(5) Parent Project Instructor
(6) Fitness Program Coordinator
(7) Homeless Liaison Officer
(8) Specialty Assignment Coordinator (Bike Team, Dual Sport)
(9) SCC Crowd Control Task Force
4. Application Process:
a. Employee must submit application with appropriate backup information
documenting their qualifications.
b. Employees are responsible for maintaining their qualifications and for
providing written proof of compliance to Police Administration.
5. Timeline for Submission of Master Officer Documentation.
a. Master Officer Pay starts the first of the month following submission (of a
complete packet) and approval of the Master Officer qualification packet
provided that the packet is submitted to Field Operations Captain by the 15th
of the prior month.
6. The number and type of specialty assignments (full-time or collateral) shall
remain at the discretion of the Chief of Police.
7. Per General Order 5.4, specialty assignments (full-time and collateral) shall
continue to be one year and may be extended by the Chief of Police for an
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additional one year period to a maximum of five years. No maximum tenure for
collateral, part-time assignments as listed in GO 5.4.
8. Maintenance of Master Officer Status and Related Pay. In order for an employee
to maintain their Master Officer Status and Related Pay once they have originally
qualified, Master Officers must complete a. AND b. below:
a. Starting January 1, 2007, every three years, complete at least one “update
class” (at least 24 hours) in a “qualifying specialty” (i.e., a specialty which the
employee used to qualify for Master Officer status). The 24 hour requirement
does not need to be at the same class or at the same time.
b. Every five years, complete at least one full year in any qualifying specialty.
Employees may count time in half time and quarter time specialties, however,
the time must total a full year, i.e. employee must complete two years in an
assignment that is in the half time category and four years in an assignment
that is in the quarter time category.
9. Re-Institution of Master Officer Pay. In order to have Master Officer Pay re-
instituted, the employee must complete both a. AND b. below:
a. Completion of an “update class” (at least 24 hours) in a “qualifying specialty”
(i.e., a specialty which the employee used to qualify for Master Officer status).
b. Completion of a full year in any qualifying specialty. Employees may count
time in half time and quarter time specialties, however, the time must total a
full year, i.e. employee must complete two years in an assignment that is in
the half time category and four years in an assignment that is in the quarter
time category.
c. Master Officer Pay will be re-instituted effective the July 1 or January 1
following the successful completion of the requirement noted above.
Retiree Medical Trust
MOU Article IV, Section O shall be amended as follows:
1. The Association intends to join the PORAC Retiree Medical Trust (Trust), the sole purpose
of which is to provide funding for medical expenses and health insurance costs for eligible
retirees or qualified family members of eligible retirees as established by the Trust.
Participation in the Trust shall be the complete and sole responsibility of the Association.
The City shall not have any involvement in the Trust’s design, its administration, or in the
benefits paid; nor shall the City have any responsibility for any actions of the Trust or its
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trustees or of Association with respect to the Trust. The Association will indemnify, defend
and hold harmless the City, its agents, officers, and employees, against any and all claims
or legal proceedings regarding the operation of the Trust.
2. In lieu of continuing the additional personal leave hours in section VI. J, effective July 1,
2018 and for the term of this agreement, City will contribute $150 per month on behalf of
each bargaining unit member, in one aggregate check, to the Trust, which will include a
report on the employees covered by the aggregate contribution.
Effective July 1, 2022 through June 30, 2023, City will contribute $225 per month on
behalf of each bargaining unit member, in one aggregate check, to the Trust, which will
include a report on the employees covered by the aggregate contribution. Effective July 1,
2023 through June 30, 20245, City will contribute $300 per month on behalf of each
bargaining unit member, in one aggregate check, to the Trust, which will include a report
on the employees covered by the aggregate contribution. Effective June 30, 20245, this
paragraph will sunset and the City contribution will revert to $150 per month as described
above.
3. The Association shall have the option, during the life of this agreement, to establish a
mandatory employee contribution to the Trust including, but not limited to, an active
employee contribution and/or a percentage of accrued vacation at retirement. The
Association will notify the City at least thirty (30) days prior to the beginning of any
mandatory employee contributions, and the City will transfer that amount to the Trust in
one aggregate check. Future changes to the mandatory employee contribution amount
will occur at the start of a calendar year and POA will notify the Human Resources
Department of the new contribution rate at least thirty (30) days prior to changing the
mandatory employee contributions.
Employee Contribution: Beginning with the payroll cycle following the establishment of
the Retiree Medical Trust, the City shall deduct, on a pre-tax basis, from each covered
employee’s payroll $150.00 per month to the Trust. Effective July 1, 2022 through June
30, 2023, the City shall deduct, on a pre-tax basis, from each covered employee’s payroll
$75.00 per month to the Trust. Effective July 1, 2023 through June 30, 20245, employees
will not make a monthly pre-tax contribution to the trust.
a. No employee election forms will be allowed or requested and there is no option
for the employee to receive these funds in cash. This employee contribution
amount may change in future calendar years following the procedure noted in 3.
above.
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b. Vacation Cash Out: Effective October 1, 2021, Uupon a covered employee’s
separation from City of Gilroy employment, twentyone hundred percent
(2100%) of the dollar amount of the employee’s vacation cash out shall be
deducted on a pre-tax basis and transferred to the Trust. There is no option for
the employee to receive the twentyone hundred percent (2100%) portion of the
vacation cash out in cash. The percentage amount noted above may change in
future calendar years following the procedure noted in 3. above. (The edits
noted in b. Vacation Cash Out are incorporated from a prior side letter
agreement dated September 30, 2021.)
4. The parties recognize the complexity of maintaining both the Trust and the
Retention/Recognition Program and agree that successor MOU negotiations will include
negotiations over continued contributions to the Trust and the potential transition from
the Retention/Recognition Program to the Trust.
Long Term Disability Insurance:
The City shall contribute up to thirty-fivesix dollars ($356.00) per employee per month
toward the Long Term/Short Term Disability Insurance Program currently offered through
the Association for unit members. The premiums paid by the city on behalf of the members
will be considered taxable income so that any benefits received by the member are non-
taxable.
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Existing MOU and Supplemental Agreements.
This Tentative Agreement identifies those articles, sections, and subsections of the
Memorandum of Understanding and Supplemental Agreements between the City and the
Gilroy Police Officers Association that the parties have mutually agreed to revise. All other
terms of the Memorandum of Understanding and Supplemental Agreements remain in full
force and effect. If approved by the parties, they may generate a new MOU incorporating the
terms set forth above.
For the City of Gilroy:
Signature/Date
For the Gilroy Police Officers Association:
Signature/Date
___________________________________
LeeAnn McPhillips, Assistant City
Administrator/Administrative Services &
Human Resources Director
____________________________________
Brian Dutton, GPOA Negotiator
___________________________________
Jimmy Forbis, City Administrator
____________________________________
Jesus Cortez, GPOA President
___________________________________
Jason Smith, Police Captain
____________________________________
Andrew Lopez, GPOA Vice President
DocuSign Envelope ID: 49E687FD-02C1-4B01-BA7A-5B3359E1AC96
3/27/2023
3/27/2023
3/27/2023
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City of Gilroy
STAFF REPORT
Agenda Item Title:Updates to Employment Agreement for City
Administrator Jimmy Forbis
Meeting Date:April 3, 2023
From:Marie Blankley, Mayor
Department:City Council
Submitted By:Marie Blankley, Mayor
Prepared By:LeeAnn McPhillips, Administrative Services and Human
Resources Director / Risk Manager
STRATEGIC PLAN GOALS Not Applicable
RECOMMENDATION
Approve updates to City Administrator’s Employment Agreement effective April 3, 2023
and authorize the Mayor to sign the Employment Agreement on behalf of the City/City
Council.
EXECUTIVE SUMMARY
The City Council recently completed the City Administrator’s annual performance
evaluation process. Following that process, a brief contract negotiations process was
completed with the Mayor serving as the negotiator. At this time, the Mayor is
presenting an updated Employment Agreement with two changes for the City Council’s
consideration.
BACKGROUND
The two recommended changes to the City Administrator’s Employment Agreement are
effective January 1, 2023 as follows:
•Increase vacation accrual from three weeks per year to four weeks per year.
•Increase City’s contribution to the City Administrator’s 457 deferred
compensation plan from 50% of the regular annual maximum ($11,250 annually)
Agenda Item 11.4
Page 757 of 768
Updates to Employment Agreement for City Administrator Jimmy Forbis
City of Gilroy City Council Page 2 of 2 April 3, 20231
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contribution to 100% of the regular annual maximum ($22,500 annually). This
annual amount adjusts each year with the maximum limit set by the Internal
Revenue Code.
All other terms and conditions of employment will remain as is.
A copy of the City Administrator’s employment agreement with these two changes noted
in the track changes format is attached for reference.
FISCAL IMPACT/FUNDING SOURCE
The new cost associated with the above changes is $11,250 annually for the increased
cost of the City contribution to the deferred compensation plan. The increase in vacation
does not have a direct hard cost as the benefit is in the form of time off and is only paid
out in cash upon separation from employment.
NEXT STEPS
Upon Council approval of the amended employment agreement, the agreement will be
put in the final (non-track changes) form and signed by the City Administrator and
Mayor.
Attachments:
1. Revised Employment Agreement for City Administrator, Jimmy Forbis
Agenda Item 11.4
Page 758 of 768
DRAFT AGREEMENT
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Employment Agreement
This Employment Agreement is made and entered into this 5th3rd day of OctoberApril, 20203, by
and between the CITY OF GILROY, California, a municipal corporation, (hereinafter called
"Employer") and JIMMY FORBIS, (hereinafter called "Employee") both of whom agree as follows:
Section 1: Term
This agreement shall remain in full force and effect from AprilOctober 63, 20203 until terminated
as provided in Sections 6 or 7 of this agreement.
Section 2: Duties and Authority
Employer employs Jimmy Forbis as City Administrator to perform the functions and duties
specified in the City of Gilroy charter and to perform other legally permissible and proper duties
and functions.
Section 3: Compensation
A. Base Salary: Employer agrees to pay Employee an annual base salary of $277,614.00
payable in monthly installments ($23,134.37) on the first business day of the month for the prior
month of service.
B. Future Salary Increases: Employee’s annual base salary will be ten percent (10%) above
the highest paid executive-level position in the City. If the highest paid executive-level employee
receives a cost-of-living percentage increase approved by the City Council, the same cost-of-
living percentage increase will be provided to the Employee.
C. Effective January 1, 2023October 6, 2020, Employer shall contribute to the Employee’s
457 Deferred Compensation Plan (employee must select from an already established city plan)
an amount equivalent to one hundredfifty percent (5100%) of the Internal Revenue Code regular
maximum annual 457 plan contribution limit. The 2023 limit is $22,500 and this amount may
change annually. Employer’s 457 plan contribution shall be made monthly with Employee’s
payroll.
D. Other than the above, there is no guarantee or promise of any increase in salary or
deferred compensation benefit.
Section 4: Benefits, Vacation and Leaves of Absence
A. Except as specifically provided herein, Employer agrees to provide Employee the same level of
health insurance, disability and life insurance, retirement, sick leave (accrue 8 hours per month/12
days per year) and other benefits provided to department head employees of the City of Gilroy.
B. Effective January 1, 2023, employee shall accrue vacation at the rate of 1520 days/1260 hours
per working year (accrued at rate of 13.330 hours per month). Future vacation accrual changes
shall be at the same rate and schedule as other department head employees of the City of Gilroy.
C. Employee shall have a bank of 44 hours paid personal leave benefits, which shall be
replenished on the first day of each fiscal year. Unused personal leave hours shall carry over from
Agenda Item 11.4
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year to year and there shall be no cap on personal leave accrual.
D. Employee shall have a bank of 80 hours of paid administrative leave benefits (beginning with FY
21), which shall be replenished on the first day of each fiscal year. Unused administrative leave
hours shall carry over from year to year and there shall be no cap on administrative leave accrual.
E. Once per fiscal year, the Employee may elect to cash out up to eighty (80) hours of available
personal leave and/or administrative leave.
F. Employee may not use accrued leave to extend their employment prior to resignation or
retirement.
G. Upon termination of Employee's employment for whatever reason, Employee or his estate, shall
be compensated for all accrued, but unused vacation time, paid holidays and other benefits, to the
fullest extent provided by state law and City of Gilroy policy. Administrative leave hours and
personal leave hours shall only be compensated to the maximum of eighty (80) hours plus the
current fiscal years’ accrual as indicated in 4C, 4D, and 4E above. Upon termination, unused sick
leave (if any) is not compensated, but is reported to California Public Employees Retirement
System (“CalPERS”) for service credit if Employee retires from the City of Gilroy consistent with
CalPERS regulations.
Section 5: Use of City Pool Vehicle
For the term of this agreement, Employer agrees to assign Employee, a city pool vehicle to utilize
for City of Gilroy business. In addition, Employee may take vehicle home (Morgan Hill, CA) and
may drive vehicle to and from work.
Section 6: General Business Expenses
Employer agrees to budget for and to pay for professional dues and subscriptions of the Employee
necessary for continuation and full participation in the League of California Cities and ICMA.
Subject to budgeting approved by the City Council, Employer will also pay for professional dues
and subscriptions of the Employee necessary for his membership and participation in other similar
national, regional, state, and local associations, and organizations necessary and desirable for the
Employee's continued professional participation, growth, and advancement, and for the good of
the Employer.
Employer agrees to budget for and to pay for travel and subsistence expenses of Employee for
professional and official travel, meetings, and occasions to adequately continue the professional
development of Employee and to pursue necessary official functions for Employer, through the
League of California Cities, and the ICMA, and committees of the League of California Cities and
ICMA in which Employee serves as a member. Subject to budgeting approved by the City Council,
Employer will also pay for travel and subsistence expenses of Employee for professional and
official travel, meetings and occasions of other similar national, regional, state, and local
governmental groups and committees in which Employee serves as a member.
C. Subject to budgeting approved by the City Council, Employer also agrees to budget for and to
pay for travel and subsistence expenses of Employee for short courses, institutes, and seminars
that are necessary for the Employee's professional development and for the good of the
Employer. At least annually, the Employee will provide Employer with a written report of such
professional development activities.
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D. Employer recognizes that certain expenses of a non-personal but job-related nature are
incurred by Employee and agrees to reimburse or to pay said general expenses. Subject to
appropriation, the finance director is authorized to disburse such moneys upon receipt of duly
executed expense or petty cash vouchers, receipts, statements or personal affidavits.
Section 7: Performance Evaluation
Employer shall provide a written performance appraisal to Employee not less than annually. The
appraisal process shall be in accordance with specific job criteria to be developed jointly by
Employer and Employee. Job criteria may be added, modified or deleted by the Employer, in
consultation with Employee. At a minimum the appraisal process shall include the opportunity for
both parties to: (1) prepare a written evaluation, (2) meet and discuss the evaluation, and (3)
present a written summary of the evaluation results. The final written evaluation should be
completed and delivered to the Employee within 30 days after the evaluation meeting. Receipt of a
performance appraisal does not guarantee an increase in compensation.
Section 8: Hours of Work
It is recognized that the Employee must devote a great deal of time outside the normal hours of
business for the City, and to that end Employee shall be allowed to establish an appropriate work
schedule.
Section 9: Outside Activities
The employment provided for by this Agreement shall be the Employee's sole employment.
Recognizing that certain outside consulting or teaching opportunities provide indirect benefits to
Employer and the community, subject to prior approval by the City Council, Employee may elect
to accept limited teaching, consulting or other business opportunities which do not interfere with
nor create a conflict of interest (or the appearance of a conflict of interest) with the performance of
his duties or obligations under this Agreement, or place the City, the City Council or the Employee
in an unfavorable light.
Section 10: Involuntary Termination
For the purpose of this agreement, involuntary termination of employment shall occur:
A. Upon the death or continued inability of Employee to perform the essential functions and duties
of the job for a period greater than twelve-work weeks in any twelve-month period, whether such
inability results from Employee's physical or mental disability, or a serious health condition, unless
a longer disability period is agreed to by the City Council.
B. Following a vote by a majority of the City Council to terminate the Employee which vote occurs
at a duly authorized public meeting. If the City Council is not able to provide Employee with thirty
(30) days’ notice, the Employer shall continue to compensate the employee as described by this
agreement for a period of thirty (30) days.
C. If the Employee resigns following an offer made by a majority of the City Council to accept
resignation.
Section 11: Severance
Agenda Item 11.4
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A. If after the commencement of the Term of this Agreement set forth in Section 1 above,
employment under this Agreement is involuntarily terminated as defined in Section 10 above, for
reasons other than death or disability as provided in Section 10A above, and for reasons that do
not constitute “Cause” as defined below, provided that Employee signs a release of claims for the
benefit of Employer, and its officers, agents and representatives, Employer shall pay to Employee
(in addition to any other amounts that may be due to Employee for salary earned as of the date of
termination, or accrued but unused vacation or leaves), as consideration for such release, a lump
sum cash payment as severance in an amount equal to six months base salary in effect at the time
of termination. In addition, and provided that Employee is eligible to and elects to continue his
health insurance and life insurance benefits, Employer will pay on Employee's behalf the premiums
for such benefits for the same six-month period. At Employee's option, payment of such funds may
be made (i) by lump sum payment upon the eighth (8 th) day after Employee signs the release
of claims; (ii ) by lump sum payment up on the later of the eighth (8th) day after Employee signs
the release of claims or the first (1st) business day of January thereafter; or (iii) in six (6) equal
monthly installments starting the last day of the month after Employee signs the release of claims.
Employer shall make all required employment and tax withholdings and deductions prior to making
any payments to Employee pursuant to the provisions of this Section 11A.
B. Concurrently with Employee’s execution of the release identified in Section 11.A above, and so
long as Employee represents and warrants, in writing, to Employer that Employee is unaware of
any facts which support Employee’s involuntarily termination for reasons that may or in fact
constitute or lead to a finding of “Cause” as defined below, and there are no facts known to
Employer which may or in fact constitute or lead to a finding of “Cause” as defined below,
Employer shall execute a release of claims for the benefit of Employee and his heirs, estate,
administrators and executors, consistent in scope to the release of claims signed by Employee.
C. If Employee is involuntarily terminated as defined in Section 8 for reasons constituting "Cause",
then Employer is not obligated to pay severance under this section. "Cause" constitutes the
conviction (including entry of guilty plea or plea of nolo contendere) of any misdemeanor or felony
criminal act committed in the course of employment, a crime of moral turpitude, or crime which
resulted in personal gain to the Employee; gross neglect or willful failure to perform the duties of
the City Administrator, which neglect or failure persists for thirty (30) days after the date of receipt
of written notice from Employer to Employee.
D. Employee agrees that the payment of severance payments by the City under this section shall
constitute his sole remedy for any claim based upon the termination of his employment with City.
Section 12: Resignation
In the event that Employee voluntarily resigns his position with Employer, he shall provide a
minimum of 30 days’ notice unless the parties agree otherwise. In the event of resignation,
Employer shall owe Employee nothing other than amounts that may be due to Employee for salary
earned as of the date of termination and accrued but unused vacation or leaves. Upon notice of
resignation, Employer shall have the option of relieving Employee of his duties and responsibilities
prior to the effective date of resignation, provided that Employer continues to pay all amounts due
to Employee for salary and benefits through and including the date of resignation
Section 13: Indemnification
A. To the fullest extent permitted by law, Employer shall defend, save harmless and indemnify
Employee against any and all claims, losses, damages, judgments, interest, settlements, fines,
Agenda Item 11.4
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court costs and other reasonable costs and expenses of legal proceedings including attorneys
fees, and any other liabilities incurred by, imposed upon, or suffered by Employee in connection
with or resulting from any claim, action, suit, or proceeding, actual or threatened, arising out of or in
connection with the performance of his duties. Said duty to defend, indemnify and save harmless
shall include, without limitation, any tort, professional liability claim or demand or other legal action,
whether groundless or otherwise, that is asserted by a third-party other than the Employer and
arises out of an alleged act or omission occurring in the performance of Employee's duties or
resulting from his exercise of judgment or discretion in connection with the performance of his
duties or responsibilities, unless the act or omission involved Employee's criminal act, intentional
misconduct, or willful or wanton misconduct. The Employee shall promptly give written notice of
any claim, threatened claim or litigation. Provided that prompt written notice is given, Employee
may request, and the Employer shall not unreasonably refuse to provide independent legal
representation with legal counsel selected by Employer at Employer's expense and subject to
Employee's approval of the choice of legal counsel, which approval shall not be unreasonably
withheld. Legal representation, provided by Employer for Employee, shall extend until a final
determination of the legal action including all appeals brought by either party, and will be provided
under a reservation of rights to not pay any judgment, compromise or settlement if it is established
by a judicial decision or jury verdict after completion of all appeals that the claim arose out of an act
that fell outside the scope of Employee's duties and employment or was the result of a criminal act,
or willful or wanton misconduct of the Employee.
B. The duty of defense shall include reimbursement of any out-of-pocket expenses incurred by
Employee in connection with his service as a witness, party or other participant in litigation,
whether such service occurs during or after the termination of Employment.
C. Any duty of Employer to defend or indemnify Employee is contingent upon Employee's full,
open and honest cooperation with defense counsel for Employer and Employee. Said duties of
defense, indemnity and cooperation shall survive the termination of employment under this
Agreement.
D. Employer may elect, at its expense, to obtain policies of insurance that provide coverage for
liabilities that are the subject to the foregoing indemnification and defense provisions. The
contractual indemnity and defense provisions set forth above are in addition to any defense or
indemnity that may be provided to Employee under any contract of insurance, and are not intended
to in any way limit , waive or relinquish any right to defense or coverage from a third-party insurer.
Section 14: Bonding
Employer shall bear the full cost of any fidelity or other bonds required of the Employee under any
law or ordinance.
Section 15: Notices
Notice pursuant to this Agreement shall be given by depositing in the custody of the United
States Postal Service, postage prepaid, addressed as follows:
(1) EMPLOYER: City of Gilroy, Attention: Mayor, 7351 Rosanna Street, Gilroy, CA
95020
(2) EMPLOYEE: Jimmy Forbis, 17010 Holiday Drive, Morgan Hill, CA, 95037
Agenda Item 11.4
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Alternatively, notice required pursuant to this Agreement may be personally given by hand-delivery
to the designated person. Notice shall be deemed given as of the date of personal service or as
the date of deposit of such written notice in the course of transmission in the United States Postal
Service.
Section 16: General Provisions
A. Integration. This Agreement sets forth and establishes the entire understanding and
agreement between the Employer and the Employee relating to the employment of the
Employee by the Employer. Any prior discussions or representations by or between the parties
are merged into and rendered null and void by this Agreement. The parties by mutual written
agreement may amend any provision of this agreement during the life of the agreement. Such
amendments shall be incorporated and made a part of this agreement.
B. Binding Effect. This Agreement shall be binding on the Employer and the Employee as well as
their heirs, assigns, executors, personal representatives and successors in interest.
C. Severability. The invalidity or partial invalidity of any portion of this Agreement will not affect
the validity of any other provision. In the event that any provision of this Agreement is held to be
invalid, the remaining provisions shall be deemed to be in full force and effect as if they have
been executed by both parties subsequent to the expungement or judicial modification of the
invalid provision.
D. This agreement was the subject of negotiation in which each side was advised by
professional advisors of his/its own choosing. Accordingly, any presumption that any provision of
this agreement should be construed for or against one side or the other is expressly disclaimed.
E. This Agreement is entered into under the laws of the State of California, and venue for any
action concerning this Agreement shall be limited to the Superior Court of the County of Santa
Clara. Employer and Employee have both read and understand and agree to the provisions of
California Government Code Sections 53243 through 53243.4, which are required by law to be
included in this Agreement. Said provisions are incorporated into this Agreement by reference as
though set out in full herein.
Executed at Gilroy, California, on the date and year first above written.
EMPLOYEE: EMPLOYER:
JIMMY FORBIS MARIE BLANKLEY, MAYOR
By: ____________________________ By: _____________________________
APPROVED AS TO FORM: ATTEST:
_________________________________ ________________________________
City Attorney City Clerk
Agenda Item 11.4
Page 764 of 768
Page 1 of 4
City of Gilroy
STAFF REPORT
Agenda Item Title:Report on Potential Temporary/Emergency Housing at
Gilroy Transit Center
Meeting Date:April 3, 2023
From:Jimmy Forbis, City Administrator
Department:Administration
Submitted By:Jimmy Forbis, City Administrator
Prepared By:Jimmy Forbis, City Administrator
STRATEGIC PLAN GOALS Promote Safe Affordable Housing for All
RECOMMENDATION
Receive report.
BACKGROUND
Homelessness is a growing local, regional, and state-wide trend and a challenge for all
governments, especially for local governments.
Gilroy’s point-in-time homeless count (unsheltered and sheltered) increased by 16%
from 2019 to 2022 (704 to 814), continuing the trend that even though Gilroy is only the
8th (out of 15) most populous city in Santa Clara County, it retains the 2nd highest
homeless population in the County. The impacts of Covid-19 are still being felt as the
pandemic put an economic strain on many of our community’s lowest wage earners and
has placed the local government in a role normally held by the County.
This growing population, coupled with Gilroy being one of the lowest-income cities in
Santa Clara County, puts enormous stress on already limited local government financial
resources. It also strains the entire Community as the unhoused population requires
significant resources and support, and there are very few providers able to assist,
leaving the City as the safety net by default for our unhoused residents.
Agenda Item 11.5
Page 765 of 768
Report on Potential Temporary/Emergency Housing at Gilroy Transit Center
City of Gilroy City Council Page 2 of 4 April 3, 2023
Much has been said about the conditions that cause homelessness, and the intent of
this report is not to outline the underlying conditions but to focus on the impacts of
certain social, economic, and/or health issues that have resulted from the number of
individuals having no place to reside.
The outbreak of Covid impacted all residents of Gilroy, but the unhoused population
faced the challenge of being unable to ”shelter-in-place.” Fortunately, several
government-funded programs were able to provide additional temporary housing
options, but as the Covid-19 pandemic subsided, many of those programs have had
their funding lapse and are no longer offered to leave a significant gap between what is
provided and what is needed with the City looking at options for housing that is both
emergency/temporary and permanent. This is a service that the County has historically
provided as they receive the tax revenues to address these issues.
In September 2020, the City Council created the Un-Housed Ad Hoc Committee
(UAHC) comprising three sitting Council members and City staff. After several months
of meeting with the community and unhoused stakeholders, the Committee received
approval from the entire City Council to implement 14 different strategies to help the
Gilroy community address these challenging issues.
ANALYSIS
The work of the UAHC identified many priorities, including the need to advocate for
affordable housing, establish safe parking, adopt the Community Plan to End
Homelessness, and partner with the Santa Clara County Office of Supportive Housing
(OSH) to access more of their programs and services.
As the Committee sunsetted, staff began evaluating opportunities for
emergency/temporary housing to give the City options for locating unhoused individuals
into temporary housing, defined as housing that can be relocated as necessary and
intended as shelter for up to 6 months per individual. This process began with
discussions initiated by the Mayor with the Founder and Chief Executive Officer of
Dignity Moves, Elizabeth Funk, whose company mobilizes investment capital to address
unsheltered homelessness. Their focus is on temporary/emergency housing at the
Gilroy Transit Center, a site previously identified as a potential Measure A permanent
housing site that the City and Office of Supportive Housing have moved to the County-
owned site at 8th and Alexander.
As Dignity Moves is currently partnering with the City of San Francisco to develop
interim housing communities, in November 2022, Mayor Blankley and members of the
City’s Department Head team visited a site at 33 Gough Street in San Francisco to tour
the pilot project that included 70 private rooms for individuals experiencing
homelessness. Each room contains a bed, desk, chair, heating, a window, and a door
that locks. The community also includes case manager offices, extensive dining and
community spaces, a computer lab, a pet area, community gardens, and storage. The
site receives 24/7 property management and security services.
Agenda Item 11.5
Page 766 of 768
Report on Potential Temporary/Emergency Housing at Gilroy Transit Center
City of Gilroy City Council Page 3 of 4 April 3, 2023
As part of the visit, the City looked to understand how a similar concept could work in
Gilroy from a public safety, public works, and service point of view. As the site receives
federal funding, it is prohibited from denying active drug users, and thus this site does
permit the use of illicit drugs. This was a considerable concern of public safety staff due
to the secondary challenges with permitting drug use in a housing community (drug-
related crime, addiction/overdose, infection, etc.). The housing community had
receptacles for needles, needle exchange, and biohazard cleanup program and had
medical personnel (and Narcan) onsite, which helps with these challenges, but also
significantly adds to the operational costs.
The residents also receive counseling, addiction, mental health, and medical care
services at the site. This is funded through HUD, the City of San Francisco, and others.
On December 14, 2022, the Mayor and City Administrator visited an Emergency Interim
Housing (EIH) site in South San Jose, which is operated by HomeFirst. This site is a
different model than the San Francisco site in that it is completely funded by the City of
San Jose at the cost of approximately $3.4 million annually and houses 78 individuals or
$44,000 per resident. These single-occupancy units each have a private restroom and
shower.
The EIH model focuses on transitioning residents to permanent housing using resident
advocates, case managers, and clinicians. The site also has 24-hour-a-day security.
In discussions with EIH staff, it was noted that although the site opened in 2021 with the
concept that the program offered initial stays of 60 days, the program did not transition
residents, with many residing for nearly two years.
In discussions with EIH staff, it was noted that although the initial concept for this
program was to offer stays of up to 60 days, the program has not transitioned many
residents, with most residing for nearly two years and continuing to do so.
Understanding exactly how these housing facilities operate is important to both staff and
the City Council as establishing temporary/emergency housing is costly and, in the
examples, has evolved into permanent housing. At this time, per Council direction, City
staff will continue to work on permanent, affordable housing projects in residential areas
of the City while engaging our local and County partners to provide emergency housing
through the Gilroy Armory and emergency shelter at the Gilroy Senior Center and Gilroy
library.
ALTERNATIVES
None.
FISCAL IMPACT/FUNDING SOURCE
None currently.
Agenda Item 11.5
Page 767 of 768
Report on Potential Temporary/Emergency Housing at Gilroy Transit Center
City of Gilroy City Council Page 4 of 4 April 3, 2023
PUBLIC OUTREACH
N/A.
NEXT STEPS
None, unless Council provides direction.
Agenda Item 11.5
Page 768 of 768