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Resolution No. 2023-17 | Sewer System Master Plan | Adopted 04/03/2023
RESOLUTION NO. 2023-17
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: ARMENDARIZ, BRACCO, CLINE,
MARQUES, TOVAR, BLANKLEY
NOES: COUNCIL MEMBERS: NONE
ABSTAIN: COUNCIL MEMBERS: NONE
ABSENT: COUNCIL MEMBERS: HILTON
APPROVED:
Marie Blankley, Mayor
ATTEST:
_______________________
Thai Nam Pham, City Clerk
Marie Blankley (Apr 4, 2023 14:49 PDT)
Marie Blankley
City of Gilroy APRIL 2023
2023 Sewer System Master Plan
CITY OF GILROY
2023
SEWER SYSTEM
MASTER PLAN
Final
March 2023
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
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
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
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
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
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
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
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
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
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.
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Figure ES.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
City of Gilroy
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Figure ES.2
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
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.
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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 & CreeksWaterbodies
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
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
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.
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
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.
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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
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18181010151212101010121818101215 1 21215
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2 4
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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.
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
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
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.
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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
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:
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.
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.
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
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
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.
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.
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
£¤101£¤101UV152UV152UV25L la g a s C r e e k
Miller SloughUvas CreekBuena Vista AveFitzgerald AveM o n te re y R d
Day RdSunrise DrMantelli DrS a n ta T e re s a Bl Wren AveLeavesley RdCa m ino Ar royoTenth StSouthside DrUvasPark D rCastro Valley RdF razier L ake 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.mxd
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 Development
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.
£¤101£¤101UV152UV152UV25L la g a s C r e e k
Miller SloughUvas CreekBuena Vista AveFitzgerald AveM o n te re y R d
Day RdSunrise DrMantelli DrS a n ta T e re s a Bl Wren AveLeavesley RdCa m ino Ar royoTenth StSouthside DrUvasPark D rCastro Valley RdF razier L ake 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.mxd
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
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
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.
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
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
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
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.
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
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.
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.
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
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
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.
January 26, 2021
LEGEND
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 2 4 6 8 10 12 14 16 18 20 22Peaking FactorTime (hours)
Site 2
0
0.2
0.4
0.6
0.8
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1.6
1.8
0 2 4 6 8 10 12 14 16 18 20 22Peaking FactorTime (hours)
Site 1
0
0.2
0.4
0.6
0.8
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1.4
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0 2 4 6 8 10 12 14 16 18 20 22Peaking FactorTime (hours)
Site 3
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 2 4 6 8 10 12 14 16 18 20 22Peaking FactorTime (hours)
Site 4
Figure 3.1
Hydraulic Model Diurnals
Sewer System Master Plan
City of Gilroy
Peaking Factor
3
January 26,2021
LEGEND
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Peaking FactorTime (hours)
Site 6
0
0.5
1
1.5
2
2.5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Peaking FactorTime (hours)
Site 5
0
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0.8
1
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1.6
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Peaking FactorTime (hours)
Site 7
0
0.2
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0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Peaking FactorTime (hours)
Site 8
Figure 3.2
Hydraulic Model Diurnals
Sewer System Master Plan
City of Gilroy
Peaking Factor
January 26, 2021
LEGEND
0
0.5
1
1.5
2
2.5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Peaking FactorTime (hours)
Site 10
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Peaking FactorTime (hours)
Site 9
0
0.5
1
1.5
2
2.5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Peaking FactorTime (hours)
Site 11
Figure 3.3
Hydraulic Model Diurnals
Sewer System Master Plan
City of Gilroy
Peaking Factor
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)
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.
!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 AVFR A ZIER LA 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 RDEAGLE RIDGE DRCLUB 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
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
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
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.
Date
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/2014
3/8/20140
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
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
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
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-
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 AVFR A ZIER LA 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 RDEAGLE RIDGE DRCLUB DRDAY RDMANTELLI DRUV152UV152UV25£¤10133/18331812
1 5
12
15103333183333/241833/2433/4233/42Uvas CreekUvas CreekLlag as C reekPajaro RiverLlagas CreekUvas Creek3 0 3 0 2 7
1 8
18332 7
18181010151212101010101818101215 1 21215
1 5 10 LN10101010101 218
33 2 7
10103 3 121 212 302715121010881010101 0 1 0 10
18181212122424242418151 8 181810101010121215181218121218
81 8
121 8 18181 8 27/181212181027/1818271018182733/42181212 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 & CreeksWaterbodies
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 AVFR A ZIER LA 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 RDEAGLE RIDGE DRCLUB DRDAY RDMANTELLI DRUV152UV152UV25£¤10133/18331812
1 5
12
15103333183333/241833/2433/4233/42Uvas CreekUvas CreekLlag as C reekPajaro RiverLlagas CreekUvas Creek3 0 3 0 2 7
1 8
18332 7
18181010151212101010101818101215 1 21215
1 5 10 LN10101010101 218
33 2 7
10103 3 121 212 302715121010881010101 0 1 0 10
18181212122424242418151 8 181810101010121215181218121218
81 8
121 8 18181 8 27/181212181027/1818271018182733/42181212 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 & CreeksWaterbodies
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
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.
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.
March 2023 4-7 City of Gilroy
Sewer System Master Plan
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
March 2023 4-8 City of Gilroy
Sewer System Master Plan
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.
March 2023 4-9 City of Gilroy
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
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
March 2023 4-11 City of Gilroy
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.
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.
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
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.
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 Classification
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.
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.
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.
March 2023 6-2 City of Gilroy
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.
(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
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.
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.
Figure 6.1
Site 1 Calibration
Inside WWTP
Sewer System Master Plan
City of Gilroy
LEGEND
June 29, 2016
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Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring
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
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.
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2 4 ².WWTPSS-33 6 363 6 Figure 7.1Existing Modeled SewerSystem Analysis for PDWFSewer System Master PlanCity of Gilroy5Updated: September 17, 2021File Path: P:\xGIS\GIS_Projects\Gilroy\Sewer\200625-MP\GL_Fig7-1_PDWF_091721.mxdGIS00.510.25MileLegendPipe 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 & CreeksWaterbodies
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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 & CreeksWaterbodies
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
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.
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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
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.
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.
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.
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
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.
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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
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
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.
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$5.1 M
Table 8.3 Joint Trunk Condition Assessment, Cost Estimates
Sewer System Master Plan
City of Gilroy
Pipeline Improvements1 Infrastructure Costs1 Suggested Cost
Allocation5,6 Cost Allocation
Existing
Diameter
New/Parallel/
Replace Diameter Length Unit Cost Infr. Cost Gilroy Morgan
Hill Gilroy Morgan Hill
(in)(in)(ft)($)($)($)($)(%)(%)($)($)
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
March 2023 City of Gilroy
Sewer System Master Plan
2023 City of Gilroy
APPENDICES
March 2023 City of Gilroy
Sewer System Master Plan
City of Gilroy
APPENDIX A
Sewer Flow Monitoring and Inflow/Infiltration Study, 2014
(V&A)
SANITARY SEWER FLOW MONITORING AND
INFLOW / INFILTRATION STUDY
City of Gilroy, CA
May 2014
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
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx TOC - i
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
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx TOC - ii
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
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx TOC - iii
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
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx TOC - iv
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
City of Gilroy
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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:
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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.
City of Gilroy
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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
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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.
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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
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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
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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.
City of Gilroy
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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.
City of Gilroy
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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
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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
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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.
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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
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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
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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%
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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
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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)
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Page 21 of 46
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)
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
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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)
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Page 23 of 46
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 -
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
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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 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
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Figure 18. Peak Measured Flow (Flow Schematic)
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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.
City of Gilroy
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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
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
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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
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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.
City of Gilroy
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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
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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.
City of Gilroy
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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
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Figure 23. Inflow Temperature Map (by Rank)
Legend
Inflow Ranking
1-2
3-4
5-6
7-8
9-11
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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.
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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 (%)
City of Gilroy
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Figure 25. RDI Temperature Map (by Rank)
Legend
RDI/I Ranking
1-2
3-4
5-6
7-8
9-11
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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
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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
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Figure 28. Basins with Groundwater Infiltration
Legend
Groundwater Infiltration
Above typical rates
At or below typical rates
City of Gilroy
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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.
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Page 41 of 46
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
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Page 42 of 46
Figure 30. Combined I/I Temperature Map (by Rank)
Legend
Combined I/I Ranking
1-2
3-4
5-6
7-8
9-11
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Page 43 of 46
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
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Page 44 of 46
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)
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Page 45 of 46
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
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Page 46 of 46
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.
City of Gilroy
Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study
13-0053 AEG CofGilroy FM Rpt.docx Appendix A
APPENDIX A
FLOW MONITORING SITES: DATA, GRAPHS, INFORMATION
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
13-0053 AEG Gilroy FM and II Rpt.doc Page S3 - 8
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
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
Page S3 - 1013-0053 AEG Gilroy FM and II Rpt.doc
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
13-0053 AEG Gilroy FM and II Rpt.doc Page S4 - 8
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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
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
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.doc
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.doc
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.doc
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.doc
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
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
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
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
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
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.doc
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.doc
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.doc
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
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02/2502/2602/2702/2803/0103/0203/0303/0403/0503/0603/0703/0803/0903/1003/1103/1203/1303/1403/1503/16Flow (mgd)0.0
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1.2 Rain (in/hr)Rainfall: 2.29 inches
Event 1
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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
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
March 2023 City of Gilroy
Sewer System Master Plan
City of Gilroy
APPENDIX B
Hydraulic Model Calibration Exhibits
City of Gilroy
Figure 6.5
Site 1 Calibration
Inside WWTP
Sewer System Master Plan
City of Gilroy
LEGEND
June 29, 2016
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Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring
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
Figure 6.7
Site 3 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
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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Rain Event
Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
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
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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Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
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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Hydraulic Model
V&A Flow Monitoring
V&A Flow Monitoring June 29, 2016
Figure 6.12
Site 8 Calibration
Renz Ln. and Highway 101 On-ramp
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
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
Figure 6.14
Site 10 Calibration
Welburn Ave. and Church St.
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
Figure 6.15
Site 11 Calibration
Wren Ave. and Mantelli 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
March 2023 City of Gilroy
Sewer System Master Plan
APPENDIX C
Joint Trunk Condition Assessment Report
CITY OF MORGAN HILL
JOINT TRUNK PIPELINE
CONDITION ASSESSMENT REPORT
January 2021 PAGE | 1
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
CITY OF MORGAN HILL
JOINT TRUNK PIPELINE
CONDITION ASSESSMENT REPORT
January 2021 PAGE | 2
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
CITY OF MORGAN HILL
JOINT TRUNK PIPELINE
CONDITION ASSESSMENT REPORT
January 2021 PAGE | 3
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
CITY OF MORGAN HILL
JOINT TRUNK PIPELINE
CONDITION ASSESSMENT REPORT
January 2021 PAGE | 4
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-
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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.
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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
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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
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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
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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
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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.
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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
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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
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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
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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
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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
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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
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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.
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• 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
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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
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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
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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.
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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”
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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
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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
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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”
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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
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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
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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
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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
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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
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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
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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
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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
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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.
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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
CITY OF MORGAN HILL
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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
CITY OF MORGAN HILL
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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
CITY OF MORGAN HILL
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January 2021 PAGE | 56
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
CITY OF MORGAN HILL
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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.
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January 2021 PAGE | 58
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
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January 2021 PAGE | 59
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
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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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January 2021 PAGE | 61
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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CONDITION ASSESSMENT REPORT
January 2021 PAGE | 62
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
CITY OF MORGAN HILL
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January 2021 PAGE | 64
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
CITY OF MORGAN HILL
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CONDITION ASSESSMENT REPORT
January 2021 PAGE | 65
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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CONDITION ASSESSMENT REPORT
January 2021 PAGE | 66
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.
CITY OF MORGAN HILL
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CONDITION ASSESSMENT REPORT
January 2021 PAGE | 67
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
CITY OF MORGAN HILL
JOINT TRUNK PIPELINE
CONDITION ASSESSMENT REPORT
January 2021 PAGE | 68
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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CONDITION ASSESSMENT REPORT
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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
CITY OF MORGAN HILL
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CONDITION ASSESSMENT REPORT
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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
CITY OF MORGAN HILL
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January 2021 PAGE | 85
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.
CITY OF MORGAN HILL
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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
CITY OF MORGAN HILL
JOINT TRUNK PIPELINE
CONDITION ASSESSMENT REPORT
January 2021 PAGE | 88
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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CONDITION ASSESSMENT REPORT
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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.
CITY OF MORGAN HILL
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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
Appendix A – Summary of Pipeline Work Completed
¯
0 3,000 6,0001,500 Feet
Summary of Pipeline
Work Completed
Appendix A
Joint Trunk Pipeline
Condition Assessment ReportLegend
CCTV & Cleaning
Abandoned
No CCTV/Cleaning
Work Description
Monte
rey
Rd
Californi
a
A
v
e
Highlan
d
A
v
eHard
ing
Ave
Fitzgerald
A
v
e
Day Rd
Wren Ave
Leavesl
e
y
R
d
SR-152
SCRWA WWTP
Appendix B – Pipeline Structural Quick Ratings
¯
0 3,000 6,0001,500 Feet
Structural
Quick Ratings
Appendix B
Joint Trunk Pipeline
Condition Assessment Report
Monte
rey
Rd
Californi
a
A
v
e
Highlan
d
A
v
eHard
ing
Ave
Fitzgerald
A
v
e
Day Rd
Wren Ave
Leavesl
e
y
R
d
SR-152
SCRWA WWTP
Legend
5000 - 5999
4000 - 4999
3000 - 3999
2000 - 2999
1000 - 1999
0000
Not Inspected
Structural Quick Rating
Appendix C – Pipeline Maintenance Quick Ratings
¯
0 3,000 6,0001,500 Feet
Maintenance
Quick Ratings
Appendix C
Joint Trunk Pipeline
Condition Assessment Report
Monte
rey
Rd
Californi
a
A
v
e
Highlan
d
A
v
eHard
ing
Ave
Fitzgerald
A
v
e
Day Rd
Wren Ave
Leavesl
e
y
R
d
SR-152
SCRWA WWTP
Legend
5000 - 5999
4000 - 4999
3000 - 3999
2000 - 2999
1000 - 1999
0000
Not Inspected
Maintenance Quick Rating
Appendix D – Pipeline Overall Risk Ratings
¯
0 3,000 6,0001,500 Feet
Overall Risk
Ratings
Appendix D
Joint Trunk Pipeline
Condition Assessment Report
Monte
rey
Rd
Californi
a
A
v
e
Highlan
d
A
v
eHard
ing
Ave
Fitzgerald
A
v
e
Day Rd
Wren Ave
Leavesl
e
y
R
d
SR-152
SCRWA WWTP
Legend
Overall Risk Rating
5
4
3
2
1
Appendix E – Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 – All-at-Once
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
Appendix F – Cost Estimate for Structural CIPP Lining & JT-P2 through JT-P9 – Phased
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
Appendix G – Recommended Emergency/Immediate Projects
¯
0 3,000 6,0001,500 Feet
Recommended
Emergency/Immediate
Projects
Appendix G
Joint Trunk Pipeline
Condition Assessment Report
Monte
rey
Rd
Californi
a
A
v
e
Highlan
d
A
v
eHard
ing
Ave
Fitzgerald
A
v
e
Day Rd
Wren Ave
Leavesl
e
y
R
d
SR-152
SCRWA WWTP
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
Appendix H – Recommended Intermediate Projects
¯
0 3,000 6,0001,500 Feet
Recommended
Intermediate
Projects
Appendix H
Joint Trunk Pipeline
Condition Assessment Report
Monte
rey
Rd
Californi
a
A
v
e
Highlan
d
A
v
eHard
ing
Ave
Fitzgerald
A
v
e
Day Rd
Wren Ave
Leavesl
e
y
R
d
SR-152
SCRWA WWTP
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
Appendix I –Mapbook, Pipeline Inspection Findings
CERTIFICATE OF THE CLERK
I, THAI NAM PHAM, City Clerk of the City of Gilroy, do hereby certify that the
attached Resolution No. 2023-17 is an original resolution, or true and correct copy of a
city Resolution, duly adopted by the Council of the City of Gilroy at a Regular Meeting of
said held on Council held Monday, April 3, 2023, at which meeting a quorum was
present.
IN WITNESS WHEREOF, I have hereunto set my hand and affixed the Official
Seal of the City of Gilroy this Monday, April 3, 2023.
____________________________________
Thai Nam Pham, CMC, CPMC
City Clerk of the City of Gilroy
(Seal)
