Attachment 2 - Final Draft Wastewater Master Plan — Manteca City Council, December 5, 2023 (part 1 of 4)

City of Manteca
Wastewater Master Plan

FINAL DRAFT
November 2023
Prepared for:

City of Manteca
Prepared by:

Stantec Consulting Services Inc.
2250 Douglas Blvd., Suite 260
Roseville, CA 95661
ATTACHMENT 2
City of Manteca Wastewater
Master Plan

FINAL DRAFT
November 2023
Prepared for:

City of Manteca
Prepared by:

Stantec Consulting Services Inc.

Disclaimer: Presently, the latest General
Plan Update relied upon for purposes of
this Master Plan is stayed, subject to a
potential referendum and litigation. As
such, the information from the General
Plan relied upon herein may be subject
to change.
______________________________
Recommended for Approval
Somporn Boonsalat
Acting Deputy Director of Engineering
______________________________
Approved by
Kevin Jorgensen II
Director of Engineering/City Engineer
ATTACHMENT 2
This document entitled City of Manteca Wastewater Master Plan was prepared by Stantec Consulting Services Inc. (“Stantec”) for the account of the City of Manteca (the “Client”). Any reliance on this document by any third party is strictly prohibited. The material in it reflects Stantec’s professional judgment in light of the scope, schedule and other limitations stated in the document and in the contract between Stantec and the Client. The opinions in the document are based on conditions and information existing at the time the document was published and do not take into account any subsequent changes.

In preparing the document, Stantec did not verify information supplied to it by others. Any use which a third party makes of this document is the responsibility of such third party. Such third party agrees that Stantec shall not be responsible for costs or damages of any kind, if any, suffered by it or any other third party as a result of decisions made or actions taken based on this document.

Prepared by
Signature
Steven L. Beck
Printed Name
Prepared by
Signature
Breanna Webb
Printed Name
Prepared by
Signature
Kelly McGartland
Printed Name
Prepared by
Signature
Akram Botrous
Printed Name
Reviewed by
Signature
Mike Van Doorn
Printed Name
ATTACHMENT 2
This page left blank intentionally.

ATTACHMENT 2
Table of Contents
EXECUTIVE SUMMARY ......................................................................................................... ES.1 ES.1 Introduction and Background ............................................................................... ES.1 ES.1.1 Scope of Work ......................................................................................... ES.1 ES.1.2 Study Area ............................................................................................... ES.1 ES.1.3 Background Information & Review ........................................................... ES.2 ES.2 Existing Wastewater Collection System............................................................... ES.4 ES.2.1 Collection System Overview..................................................................... ES.4 ES.2.2 Existing Sewer Flows ............................................................................... ES.6 ES.3 Hydraulic Model Development & Calibration........................................................ ES.6 ES.3.1 Hydraulic Model Approach ....................................................................... ES.6 ES.3.2 Model Inputs and Structure ...................................................................... ES.7 ES.3.3 Flow Allocation......................................................................................... ES.7 ES.3.4 Model Calibration ..................................................................................... ES.9 ES.4 Basis for Collection System Analysis ................................................................... ES.9 ES.4.1 Design Criteria ......................................................................................... ES.9 ES.4.2 Future Growth Assumptions................................................................... ES.10 ES.5 Collection System Capacity Evaluation.............................................................. ES.13 ES.5.1 Modeled Design Horizon Scenarios ....................................................... ES.13 ES.5.2 Scenario 1 – Existing Development Results........................................... ES.13 ES.5.3 Scenarios 2 to 4 – Future Growth Analysis............................................. ES.19 ES.5.4 Phasing Strategies and Potential Alternatives ........................................ ES.25 ES.5.5 Conceptual Opinion of Probable Cost .................................................... ES.25 ES.6 Wastewater Collection System Condition Assessment ...................................... ES.30 ES.6.1 Background............................................................................................ ES.30 ES.6.2 Summary of Sewer Condition Assessment............................................. ES.30 ES.6.3 Cost Summary of Rehabilitation and Replacement Projects................... ES.31 ES.7 Wastewater Quality Control Facility (WQCF) Background and Regulatory Requirements .................................................................................................... ES.33 ES.7.1 WQCF Background................................................................................ ES.33 ES.7.2 Regulatory Requirements....................................................................... ES.35 ES.7.3 Thermal Plan Compliance ...................................................................... ES.38 ES.8 WQCF Wastewater Flows and Loads ................................................................ ES.41 ES.8.1 Historical Flows and Loads and Changed Conditions............................. ES.41 ES.8.2 Plant Recycled Flows and True Influent Flows ....................................... ES.43 ES.8.3 Summary of Existing and Future Wastewater Characteristics ................ ES.44 ES.8.4 Equivalent Population Served ................................................................ ES.46 ES.9 WQCF Assessment of Existing Facilities and Recommended Interim Improvements.................................................................................................... ES.46 ES.9.1 Headworks and Influent Pump Station ................................................... ES.47 ES.9.2 Aerated Grit Tanks and Primary Sedimentation Basins.......................... ES.47 ES.9.3 Secondary Treatment Facilities .............................................................. ES.48 ES.9.4 Secondary Effluent Equalization Pond (SEEP)....................................... ES.49 ES.9.5 UV Disinfection System.......................................................................... ES.49 ES.9.6 Biosolids Handling Facilities................................................................... ES.49 ATTACHMENT 2
ES.9.7 Instrumentation and Electrical Controls .................................................. ES.50 ES.9.8 Biogas Utilization Facilities..................................................................... ES.50 ES.9.9 Cost Summary of Recommended Interim Improvements ....................... ES.51 ES.10 WQCF Phase IV Expansion Project................................................................... ES.53 ES.10.1 Evaluation of Shortlisted Alternatives ..................................................... ES.54 ES.10.2 Recommended Phase IV Expansion Project.......................................... ES.57 ES.10.3 Phase IV Expansion Costs..................................................................... ES.61 ES.11 Staffing Plan ...................................................................................................... ES.63 ES.12 Capital Improvement Program ........................................................................... ES.64 ES.12.1 Background............................................................................................ ES.64 ES.12.2 Project Prioritization ............................................................................... ES.64 ES.12.3 Cost Estimating Methodology................................................................. ES.64 ES.12.4 Proposed Capital Improvement Program ............................................... ES.65 ES.12.5 Conclusions and Recommendations ...................................................... ES.68

1.0 INTRODUCTION AND BACKGROUND ......................................................................1.1

1.1 Scope of Work ........................................................................................................1.1

1.2 Study Area..............................................................................................................1.2

1.3 Background Information and Review ......................................................................1.4

1.3.1 Sewer System Management Plan (SSMP)..................................................1.4

1.3.2 Service Agreements....................................................................................1.5

1.3.3 2012 Collection System Master Plan...........................................................1.6

1.3.4 Manteca General Plan Update ....................................................................1.7

2.0 EXISTING WASTEWATER COLLECTION SYSTEM ..................................................2.1

2.1 Collection System Overview ...................................................................................2.1

2.1.1 Service Areas..............................................................................................2.1

2.1.2 Gravity Sewers............................................................................................2.4

2.1.3 Force Mains ................................................................................................2.9

2.1.4 Pump and Lift Stations ................................................................................2.9

2.1.5 WQCF Headworks and Influent Structure..................................................2.13

2.2 Existing Sewer Flows............................................................................................2.15

2.2.1 Wastewater Flow Characterization Definitions ..........................................2.15

2.2.2 Flow Monitoring Study...............................................................................2.16

2.2.3 Dry Weather Flows....................................................................................2.21

2.2.4 Wet-Weather Flows...................................................................................2.22

2.2.5 Per-Capita Flow Assessment ....................................................................2.24

3.0 HYDRAULIC MODEL DEVELOPMENT AND CALIBRATION.....................................3.1

3.1 Hydraulic Model Approach and Software ................................................................3.1

3.1.1 Modeling Software ......................................................................................3.2

3.2 Model Inputs...........................................................................................................3.2

3.2.1 Geodatabases.............................................................................................3.3

3.2.2 Record Drawings.........................................................................................3.5

3.2.3 Manhole Survey ..........................................................................................3.5

3.3 Model Structure ......................................................................................................3.8

3.3.1 Manholes ....................................................................................................3.8

3.3.2 Sewers........................................................................................................3.8 ATTACHMENT 2

3.3.3 Lift Stations & Force Mains .......................................................................3.10

3.3.4 Boundary Conditions.................................................................................3.10

3.4 Flow Allocation .....................................................................................................3.11

3.4.1 Sanitary Loading .......................................................................................3.11

3.5 Dry Weather Calibration........................................................................................3.12

3.5.1 Criteria for Dry Weather Flow Calibration ..................................................3.12

3.5.2 Diurnal Pattern Development ....................................................................3.12

3.5.3 Flow Calibration ........................................................................................3.15

3.5.4 Velocity and Depth Calibration ..................................................................3.18

3.6 Wet Weather Calibration.......................................................................................3.21

3.6.1 Methodology .............................................................................................3.21

3.6.2 Criteria for Wet-Weather Flow Calibration .................................................3.21

3.6.3 Rainfall Event Analysis..............................................................................3.22

3.6.4 Flow Calibration ........................................................................................3.23

3.6.5 Velocity and Depth Calibration ..................................................................3.27

3.7 Model Calibration Summary..................................................................................3.27

4.0 BASIS FOR COLLECTION SYSTEM ANALYSIS........................................................4.1

4.1 Design Criteria........................................................................................................4.1

4.1.1 Wastewater Generation Factors for General Plan Land Use .......................4.1

4.1.2 Design Storm ..............................................................................................4.3

4.1.3 Target Level of Service (LOS).....................................................................4.4

4.2 Future Growth Assumptions ...................................................................................4.5

4.2.1 Future Study Area and Servicing Strategy...................................................4.5

4.2.2 Population Projections.................................................................................4.8

4.2.3 Design Horizons..........................................................................................4.8

5.0 COLLECTION SYSTEM CAPACITY EVALUATION....................................................5.1

5.1 Modeled Design Horizon Scenarios........................................................................5.1

5.2 Scenario 1 – Existing Development Results............................................................5.3

5.2.1 Dry Weather Flows......................................................................................5.3

5.2.2 Peak Flows and Residual Capacity .............................................................5.3

5.2.3 Lift Station Performance..............................................................................5.7

5.2.4 LOS Deficiencies.......................................................................................5.10

5.2.5 Recommended Capacity Improvements....................................................5.12

5.3 Scenarios 2 to 4 – Future Growth Analysis ...........................................................5.18

5.3.1 Impacts of Growth on Existing Infrastructure.............................................5.18

5.3.2 Previously Identified System Improvements..............................................5.22

5.3.3 Recommended Capacity Improvements....................................................5.25

5.3.4 System Infrastructure to Serve Future Development ................................. 5.28

5.4 Phasing Strategies and Potential Alternatives.......................................................5.35

5.5 Conceptual Opinion of Probable Cost...................................................................5.38

5.5.1 Cost Estimating Assumptions....................................................................5.38

5.6 Recommended Projects and Costs.......................................................................5.39

6.0 WASTEWATER COLLECTION SYSTEM CONDITION ASSESSMENT......................6.1

6.1 Background ............................................................................................................6.1 ATTACHMENT 2

6.2 Summary of Sewer Conditions Assessment ...........................................................6.1

6.2.1 Project Summaries......................................................................................6.4

6.3 Summary of Recommendations..............................................................................6.7

7.0 WASTEWATER QUALITY CONTROL FACILITY (WQCF) BACKGROUND AND REGULATORY REQUIREMENTS...............................................................................7.1

7.1 WQCF Background................................................................................................. 7.1

7.2 Regulatory Requirements .......................................................................................7.5

7.2.1 Order Limitations.........................................................................................7.5

7.2.2 Competing Regulations...............................................................................7.9

7.2.3 Future Compliance Considerations ...........................................................7.13

7.3 Thermal Plan Compliance.....................................................................................7.14

8.0 WQCF WASTEWATER FLOWS AND LOADS............................................................8.1

8.1 Historical and Design Flows and Loads ..................................................................8.1

8.2 Recycled Flows and True Influent Characteristics...................................................8.4

8.3 City of Lathrop Flow Impacts ..................................................................................8.5

8.4 Summary of Existing and Future Wastewater Characteristics................................. 8.7

8.5 Solids Mass Balance ..............................................................................................8.9

8.6 Equivalent Population Served...............................................................................8.13

9.0 WQCF ASSESSMENT OF EXISTING FACILITIES AND RECOMMENDED INTERIM IMPROVEMENTS.........................................................................................9.1

9.1 Headworks and Influent Pump Station....................................................................9.1

9.1.1 Influent Gravity Sewer Trunks .....................................................................9.2

9.1.2 Influent Screening .......................................................................................9.2

9.1.3 Screenings Washer Compactor System......................................................9.3

9.1.4 Influent Pump Station..................................................................................9.3

9.1.5 Headworks and IPS Biofilter........................................................................9.6

9.1.6 Assessment of Headworks, IPS and Biofilter...............................................9.6

9.2 Aerated Grit Tanks..................................................................................................9.7

9.2.1 Assessment of Aerated Grit Tanks..............................................................9.9

9.3 Primary Sedimentation Basins..............................................................................9.10

9.4 Secondary Treatment Facilities.............................................................................9.12

9.4.1 Secondary Treatment Aeration Basins ......................................................9.15

9.4.2 Secondary Clarifiers..................................................................................9.16

9.4.3 RAS/WAS Pump Stations .........................................................................9.17

9.4.4 Assessment of Secondary Treatment Facilities.........................................9.17

9.5 Secondary Effluent Equalization Pond (SEEP) .....................................................9.18

9.5.1 Performance Assessment of SEEP...........................................................9.20

9.6 Filter Feed Pump Station ......................................................................................9.20

9.6.1 Performance Assessment of Filter Feed Pump Station .............................9.21

9.7 Rapid Mix and Flocculation Tanks ........................................................................9.22

9.7.1 Performance Assessment of Rapid Mix and Flocculation Tanks ...............9.23

9.8 Tertiary Filters.......................................................................................................9.23

9.8.1 Performance Assessment of Tertiary Filters..............................................9.24 ATTACHMENT 2

9.9 UV Disinfection System ........................................................................................9.24

9.9.1 Performance Assessment of UV Disinfection System ...............................9.25

9.10 Effluent Handling and Disposal Facilities ..............................................................9.28

9.10.1 Irrigation Pump Station and Secondary Effluent Storage Pond (SESP).....9.29

9.10.2 Onsite Land Disposal System ...................................................................9.29

9.10.3 Outfall .......................................................................................................9.29

9.10.4 Recycled Water System............................................................................9.29

9.10.5 Effluent Pump Station ...............................................................................9.30

9.10.6 Performance Assessment of Effluent Handling and Disposal Facilities .....9.31

9.11 Biosolids Handling Facilities .................................................................................9.31

9.11.1 Waste Activated Sludge Thickening ..........................................................9.31

9.11.2 Anaerobic Digesters..................................................................................9.32

9.11.3 Anaerobic Digester Control Building..........................................................9.34

9.11.4 FOG and Food Waste Receiving Stations.................................................9.35

9.11.5 Biosolids Dewatering Facilities ..................................................................9.37

9.11.6 Biosolids Drying Facilities..........................................................................9.38

9.11.7 Performance and Capacity Assessment of Biosolids Facilities..................9.39

9.12 Biogas Utilization Facilities ...................................................................................9.39

9.12.1 Floating Steel Gas Covers ........................................................................9.40

9.12.2 Biogas H2S Removal System ...................................................................9.40

9.12.3 Biogas Booster Blowers ............................................................................9.40

9.12.4 Hot Water Boilers......................................................................................9.41

9.12.5 Bio-CNG System.......................................................................................9.41

9.12.6 Waste Gas Boiler ......................................................................................9.42

9.12.7 CNG Fueling Station .................................................................................9.42

9.12.8 400 kW Generator.....................................................................................9.43

9.12.9 Performance Assessment of Biogas Utilization Facilities...........................9.43

9.13 Electrical Supply and Distribution..........................................................................9.44

9.13.1 Normal Electrical Power System ...............................................................9.44

9.13.2 Emergency Electrical Power System.........................................................9.44

9.13.3 Performance Assessment of Electrical Supply and Distribution.................9.45

9.14 Instrumentation and Electrical Controls................................................................. 9.45

9.14.1 Performance Assessment of Instrumentation and Electrical Controls........9.46

9.15 Auxiliary Systems ................................................................................................. 9.46

9.15.1 Chemical Handling Facilities .....................................................................9.46

9.15.2 Biofilter Systems .......................................................................................9.46

9.15.3 Plant Water Well System...........................................................................9.47

9.15.4 Performance Assessment of Auxiliary Systems.........................................9.47

9.16 Recommended Interim Improvements ..................................................................9.47

10.0 WQCF PHASE IV EXPANSION PROJECT ...............................................................10.1

10.1 Treatment Process Selection................................................................................10.2

10.1.1 Alternative 1: Conventional Activated Sludge (CAS) Process....................10.2

10.1.2 Alternative 2: Membrane Bioreactor (MBR) Process ................................. 10.3

10.1.3 Alternative 3: Sequencing Batch Reactor (SBR) Process..........................10.3

10.1.4 Alternative 4: Integrated Fixed-Film Activated Sludge (IFAS) System. ......10.4

10.1.5 Alternative 5: Activated Granular Sludge (AGS) Process ..........................10.4

10.1.6 Screening Criteria Matrix...........................................................................10.5 ATTACHMENT 2

10.1.7 Evaluation of Shortlisted Alternatives ........................................................10.6

10.2 Recommended Phase IV Expansion Project.......................................................10.26

10.2.1 Headworks and Influent Pump Station ....................................................10.28

10.2.2 Aerated Grit Tanks ..................................................................................10.29

10.2.3 Primary Sedimentation Basins ................................................................10.30

10.2.4 Existing Secondary Treatment Process Improvements ...........................10.31

10.2.5 New Membrane Bioreactors (MBR).........................................................10.34

10.2.6 Biosolids Handling Facilities....................................................................10.36

10.2.7 Effluent Cooling and Disposal ................................................................. 10.40

10.2.8 New Municipal Utilities Building and Entrance Road ...............................10.47

10.3 Phase IV Expansion Project Costs .....................................................................10.47

11.0 STAFFING PLAN.......................................................................................................11.1

11.1 Introduction...........................................................................................................11.1

11.2 Purpose................................................................................................................11.1

11.3 Plant Classification and Operator Certification......................................................11.1

11.3.1 Operator Certification ................................................................................11.2

11.4 Staff Responsibilities ............................................................................................11.5

11.4.1 Operations ................................................................................................11.5

11.4.2 Maintenance .............................................................................................11.5

11.4.3 Laboratory & Regulatory Compliance........................................................11.5

11.4.4 SCADA .....................................................................................................11.5

11.4.5 Supervisory...............................................................................................11.5

11.5 Current Staffing ....................................................................................................11.6

11.6 Future Expansion ................................................................................................. 11.8

11.7 Staffing for Current and future expansions............................................................11.8

11.7.1 Operations and Maintenance for WQCF ...................................................11.8

11.7.2 Laboratory & Regulatory Compliance......................................................11.11

11.7.3 Wastewater Collection.............................................................................11.12

11.7.4 Supervisors/Administration......................................................................11.13

11.7.5 SCADA ...................................................................................................11.13

11.8 Summary ............................................................................................................11.13

12.0 CAPITAL IMPROVEMENT PROGRAM.....................................................................12.1

12.1 Background ..........................................................................................................12.1

12.2 Project Prioritization..............................................................................................12.1

12.3 Cost Estimating Methodology ...............................................................................12.2

12.4 Proposed Capital Improvement Program..............................................................12.2

12.4.1 On-going Collection System Rehabilitation and Replacement Projects .....12.2

12.4.2 Existing Wastewater Collection System Capacity Improvements ..............12.3

12.4.3 Previously Identified Wastewater Collection System Projects....................12.3

12.4.4 Future Wastewater Collection System Improvements ...............................12.4

12.4.5 WQCF Capacity Assessment Interim Improvements................................. 12.4

12.4.6 Instrumentation and Electrical Improvement Projects................................12.5

12.4.7 Other WQCF Interim Projects....................................................................12.6

12.4.8 WQCF Phase IV Expansion Projects ........................................................12.6

12.5 Conclusions and Recommendations.....................................................................12.8 ATTACHMENT 2

13.0 REFERENCES...........................................................................................................13.1

LIST OF TABLES
Table ES-1. Design Horizon Flow Projections..................................................................... ES.11 Table ES-2. Summary of Modeled Scenarios...................................................................... ES.13 Table ES-3. Recommended Collection System Improvements – Scenario 1....................... ES.26 Table ES-4. Recommended Collection System Improvements – Scenario 2....................... ES.27 Table ES-5. Recommended Collection System Improvements – Scenario 3....................... ES.28 Table ES-6. Recommended Collection System Improvements – Scenario 4....................... ES.29 Table ES-7. Summary of Project Repair/Rehabilitation/Replacement Costs....................... ES.31 Table ES-8. Select Order Effluent Limitations for Discharge to San Joaquin River.............. ES.35 Table ES-9. Breakdown of Existing and Projected Interim Flows ........................................ ES.43 Table ES-10. Existing and Future Flows and Loads............................................................ ES.45 Table ES-11. Recommended Interim Improvements Project Costs1 ..................................... ES.52
Table ES-12. Alternatives Rating and Ranking ................................................................... ES.56 Table ES-13. Phase IV Expansion Project Costs ................................................................... ES.62 Table ES-14. Summary of Staffing Recommendations........................................................ ES.63 Table ES-15. Summary of Wastewater Collection System CIP Projects............................. ES.66 Table ES-16. Summary of WQCF CIP Projects.................................................................. ES.67 Table 1-1. Manteca General Plan Land Use ............................................................................1.8 Table 2-1. Collection System Service Areas ............................................................................2.3 Table 2-2. Gravity Mains by Diameter1.....................................................................................2.4 Table 2-3. Gravity Mains by Pipe Material 1
..............................................................................2.5 Table 2-4. Gravity Mains by Installation Year 1.........................................................................2.5 Table 2-5. Force Mains by Diameter 1 ......................................................................................2.9 Table 2-6. Wastewater Pump and Lift Stations.......................................................................2.12 Table 2-7. Flow Monitoring Shed Characteristics ...................................................................2.17 Table 2-8. Summary of Rainfall Data .....................................................................................2.20 Table 2-9. V&A Flow Monitoring and I/I Analysis Summary....................................................2.21 Table 2-10. V&A ADWF Summary .........................................................................................2.22 Table 2-11. V&A PWWF Summary ........................................................................................2.23 Table 2-12. Historical Per-Capita Wastewater Generation .....................................................2.26 Table 3-1. Manhole Data Gap Assessment..............................................................................3.3 Table 3-2. Pipeline Data Gap Assessment...............................................................................3.4 Table 3-3. Structures Gap Data Assessment ...........................................................................3.4 Table 3-4. Modeled Manholes Summary..................................................................................3.8 Table 3-5. Modeled Sewers Summary .....................................................................................3.9 Table 3-6. Modeled Force Mains Summary............................................................................3.10 Table 3-7. Flow Calibration Results – Dry Weather Period #1 (4/1/2022 - 4/8/2022)..............3.16 Table 3-8. Flow Calibration Results – Dry Weather Period #2 (5/2/2022 - 5/9/2022)..............3.17 Table 3-9. Depth and Velocity Calibration Results – Dry Weather Period #1 (4/1/2022 - 4/8/2022) ..............................................................................................................3.19 Table 3-10. Depth and Velocity Calibration Results – Dry Weather Period #2 (5/2/2022 - 5/9/2022).............................................................................................................3.20 Table 3-11. Rainfall Calibration and Validation Events...........................................................3.23 Table 3-12. Flow Calibration Results – Wet Weather Period #1 (3/27/2022 - 3/28/2022) .......3.24 Table 3-13. Flow Calibration Results – Wet Weather Period #2 (12/26/2022 - 1/16/2023) .....3.25 ATTACHMENT 2
Table 3-14. WQCF Influent Flow Calibration Results – Wet Weather Period #2 (12/26/2022 - 1/16/2023) .........................................................................................3.27 Table 4-1. General Plan Residential Density Update................................................................4.2 Table 4-2. Wastewater Generation Factors (WGF) ..................................................................4.3 Table 4-3. Allowable Surcharge Criteria...................................................................................4.5 Table 4-4. Collection System Service Areas and General Plan Boundaries .............................4.6 Table 4-5. MSR Population Projections....................................................................................4.8 Table 4-6. Design Horizon General Plan Land Use..................................................................4.9 Table 4-7. Design Horizon Flow Projections...........................................................................4.10 Table 5-1. Summary of Modeled Scenarios .............................................................................5.1 Table 5-2. Summary of Modeled Scenarios .............................................................................5.4 Table 5-3. Modeled Pump Station Results, 10-year, 24-hour Design Storm.............................5.7 Table 5-4. Modeled Force Main Results, 10-year, 24-hour Design Storm ................................5.8 Table 5-5. Theoretical Upsizing Improvements to Alleviate Existing Gravity Sewer Capacity Deficiencies – Scenario 1..........................................................................5.13 Table 5-6. Alternative Capacity Improvements for the Woodward Park Lift Station (Existing Conditions)................................................................................................5.15 Table 5-7. Modeled Pump Station Results, 10-year, 24-hour Design Storm...........................5.21 Table 5-8. Previously Identified System Improvements..........................................................5.23 Table 5-9. Theoretical Upsizing Improvements to Alleviate Existing Sewer Capacity Deficiencies – Future Scenarios ..............................................................................5.26 Table 5-10. System Infrastructure to Serve Future Development ...........................................5.31 Table 5-11. Dependent CIP Project Phasing..........................................................................5.35 Table 5-12. Recommended Capital Improvement Plan – Wastewater Collection System ......5.40 Table 5-13. Alternative Project Costs – Project 7B: Expand North Shed Lift Stations.............5.44 Table 6-1. Summary of Project Repair/Rehabilitation/Replacement Costs...............................6.7 Table 7-1. Select Order Effluent Limitations for Discharge to San Joaquin River .....................7.5 Table 7-2. Maximum Turbidity Limits........................................................................................7.8 Table 7-3. Water Conservation Effect on Salinity ...................................................................7.12 Table 7-4. Stepwise Unit Processes to Achieve RO Treatment..............................................7.13 Table 8-1. WQCF Existing and Near-Term Future Flows and Loads Compared to Phase III Basis of Design Report ..........................................................................................8.4 Table 8-2. Recycle Flow Streams and True Influent Characteristics.........................................8.5 Table 8-3. Breakdown of Existing and Projected Interim Flows ................................................8.7 Table 8-4. Existing and Future Flows and Loads......................................................................8.8 Table 8-5. Solids Production Summary for Current and Interim Flows ...................................8.11 Table 8-6. Solids Production Summary for Future Flows........................................................8.12 Table 8-7. Population Projections and Associated Flows and BOD Loads .............................8.14 Table 9-1. Existing Secondary Treatment Facilities................................................................. 9.12 Table 9-2. UV Disinfection System Duron 6 vs Duron 8 Comparison .....................................9.27 Table 9-3. Recommended Interim Improvements Project Costs1............................................9.48 Table 10-1. Secondary Treatment Alternative Screening .......................................................10.5 Table 10-2. Influent and Secondary Treatment Flows and Loads for 4.65 Mgal/d Design Expansion................................................................................................................10.7 Table 10-3. Conventional Activated Sludge Process Design................................................10.12 Table 10-4. Fine Screens Design Criteria.............................................................................10.16 Table 10-5. MBR Design Criteria for Stage 1 Expansion......................................................10.20 Table 10-6. Facilities Descriptions and Costs.......................................................................10.23 ATTACHMENT 2
Table 10-7. Alternatives Rating and Ranking .......................................................................10.26 Table 10-8. Overall Loading Design Criteria for Phase IV Project Expansion.......................10.27 Table 10-9. Design Criteria for Influent Pumps for the Phase IV Expansion Project.............10.28 Table 10-10. Design Criteria for Aerated Grit Tanks for Phase IV Expansion Project...........10.29 Table 10-11. Primary Sedimentation Basins Design Criteria for Phase IV Expansion Project ...................................................................................................................10.30 Table 10-12. Design Criteria for DAFTs for the Phase IV Expansion Project........................10.36 Table 10-13. Design Criteria for Centrifuges for the Phase IV Expansion Project.................10.37 Table 10-14. Design Criteria for Digesters for the Phase IV Expansion Project....................10.39 Table 10-15. Design Criteria for Cooling Towers for the Phase IV Expansion Project ..........10.44 Table 10-16. Design Criteria for Effluent Pumps for the Phase IV Expansion Project...........10.46 Table 10-17. Design Criteria for Cooling Basin Effluent Pumps for the Phase IV Expansion Project..................................................................................................10.46 Table 10-18. Phase IV Expansion Project Costs.....................................................................10.48 Table 11-1. Wastewater Treatment Plants Classification 1,2 ...................................................11.3 Table 11-2. Minimum Required CPO and DOIC 1,2................................................................. 11.3 Table 11-3. Operator Certification Requirements Table 1,2 .....................................................11.4 Table 11-4. WQCF Operations and Maintenance Staff Requirements for Stage 1 1 ...............11.9 Table 11-5. WQCF Operations and Maintenance Staff Requirements for Stage 2 1 .............11.10 Table 11-6. Direct Labor Required for WQCF Laboratory ....................................................11.11 Table 11-7. Summary of Staffing Recommendations ...........................................................11.13 Table 12-1. Ongoing Collection System Rehabilitation and Replacement Projects................12.3 Table 12-2. Existing Wastewater Collection System Capacity Improvements........................12.3 Table 12-3. Previously Identified Wastewater Collection System Improvements....................12.4 Table 12-4. Future Wastewater Collection System Improvements .........................................12.4 Table 12-5. WQCF Capacity Assessment Interim Projects....................................................12.5 Table 12-6. Instrumentation and Electrical Improvement Projects .........................................12.6 Table 12-7. Other WQCF Interim Improvement Projects .......................................................12.6 Table 12-8. WQCF Phase IV Expansion Project....................................................................12.7

LIST OF FIGURES
Figure ES-1. Existing Sewer Collection System Overview .................................................... ES.3 Figure ES-2. Sewer Collection System and Service Area ..................................................... ES.5 Figure ES-3. Flow Monitoring Locations and Modeled Facilities............................................ ES.8 Figure ES-4. Modeled Scenario Planning Areas ................................................................. ES.12 Figure ES-5. Residual System Capacity, 10-year, 24-hour Design Storm ........................... ES.14 Figure ES-6. Residual System Capacity, Area of Concern.................................................. ES.16 Figure ES-7. Recommended Improvements to Address Existing Capacity Deficiencies...... ES.18 Figure ES-8. Recommended Future System Improvements................................................ ES.24 Figure ES-9. Condition Assessment (2017) Improvements ................................................. ES.32 Figure ES-10. WQCF Existing Site Layout.......................................................................... ES.34 Figure ES-11. WQCF Outfall Discharge Location................................................................ ES.39 Figure ES-12. Historical Influent Flow ................................................................................. ES.41 Figure ES-13. Historical Influent BOD Load ........................................................................ ES.42 Figure ES-14. Estimated Population Growth and Proposed WQCF Phase IV Expansion.... ES.53 Figure ES-15. Site Plan of Recommended Phase IV Expansion Project ............................. ES.58 Figure ES-16. Proposed CIPs Annual Estimated Expenditures........................................... ES.68 Figure 1-1. Existing Sewer Collection System – Overview .......................................................1.3 ATTACHMENT 2
Figure 1-2. Manteca General Plan ...........................................................................................1.9 Figure 2-1. Sewer Collection System and Service Areas .........................................................2.2 Figure 2-2. Existing Sewer Collection System – Pipe Size .......................................................2.6 Figure 2-3. Existing Sewer Collection System – Pipe Material .................................................2.7 Figure 2-4. Existing Sewer Collection System – Installation Year.............................................2.8 Figure 2-5. Existing Sewer Collection System – Pump Stations, Lift Stations, and Forcemains..............................................................................................................2.10 Figure 2-6. Existing Sewer Collection System – Service Areas Pump Stations and Lift Stations ...................................................................................................................2.11 Figure 2-7. Existing Sewer Collection System – Main Trunks and WQCF Discharge .............2.14 Figure 2-8. Existing Sewer Collection System Flow Monitor...................................................2.18 Figure 2-9. Flow Monitoring Basins & Sewersheds ................................................................2.19 Figure 2-10. City of Manteca Influent Flow Data.....................................................................2.25 Figure 3-1. Initial Gap Assessment Results..............................................................................3.6 Figure 3-2. Surveyed Manholes ...............................................................................................3.7 Figure 3-3. Residential – Diurnal Flow Pattern at Flow Meter Site 1.......................................3.13 Figure 3-4. Pump Station Influence – Diurnal Flow Pattern at Flow Meter Site 4....................3.14 Figure 3-5. Metered versus Modeled Flows at Site 1..............................................................3.18 Figure 3-6. Rainfall and WQCF Influent Data .........................................................................3.22 Figure 3-7. Modeled Versus Observed WQCF Influent Flow Data .........................................3.26 Figure 3-8. Calibration Event: WWF – Peak Sewer Flow .......................................................3.29 Figure 3-9. Calibration Event: WWF – Peak Pipe Utilization (% of FPC)................................3.30 Figure 3-10. Calibration Event: WWF – Residual Capacity ....................................................3.31 Figure 3-11. Calibration Event: WWF – Manhole Surcharging (Depth Below Rim).................3.32 Figure 4-1. 10-year, 24-hour Design Storm..............................................................................4.4 Figure 4-2. Service Area Collection Strategies.........................................................................4.7 Figure 5-1. Modeled Scenario Planning Areas .........................................................................5.2 Figure 5-2. Residual System Capacity, 10-year, 24-hour Design Storm...................................5.6 Figure 5-3. Modeled Forcemain Velocity, 10-year, 24-hour Design Storm................................5.9 Figure 5-4. Scenario 1 – Modeled Capacity Deficiencies, 10-year 24-hour Design Storm ......5.11 Figure 5-5. Recommended Improvements to Address Existing Capacity Deficiencies ...........5.17 Figure 5-6. Scenarios 2-4 – Modeled Capacity Deficiencies, 10-year 24-hour Design Storm.......................................................................................................................5.20 Figure 5-7. Previously Identified System Improvements.........................................................5.24 Figure 5-8. Recommended Improvements to Address Future Capacity Deficiencies .............5.27 Figure 5-9. System Infrastructure to Serve Future Development............................................5.32 Figure 5-10. Future CIP Service Areas ..................................................................................5.33 Figure 5-11. Recommended Improvements vs. 2012 Master Plan Recommendations...........5.34 Figure 6-1. Condition Assessment Improvements....................................................................6.3 Figure 7-1. WQCF Existing Site Layout....................................................................................7.3 Figure 7-2. Existing WQCF Process Flow Diagram..................................................................7.4 Figure 7-3. WQCF Outfall Discharge Location .......................................................................7.15 Figure 8-1. Historical Influent Flow...........................................................................................8.1 Figure 8-2. Historical Influent BOD Load..................................................................................8.2 Figure 8-3. Existing Manteca WQCF Generalized Flow Diagram .............................................8.6 Figure 8-4. Solids Mass Balance Diagram of Existing Loading Conditions.............................8.10 Figure 9-1. Headworks and Influent Pump Station ...................................................................9.2 Figure 9-2. WQCF Influent Pump Station Bottom Plan.............................................................9.4 ATTACHMENT 2

CITY OF MANTECA WASTEWATER MASTER PLAN
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Figure 9-3. WQCF Influent Pump Station Section View ............................................................ 9.5 Figure 9-4. Aerated Grit Tanks .................................................................................................. 9.9 Figure 9-5. Primary Sedimentation Basins .............................................................................. 9.11 Figure 9-6. Aeration Basins ..................................................................................................... 9.13 Figure 9-7. Secondary Clarifiers .............................................................................................. 9.14 Figure 9-8. RAS Pump Stations ............................................................................................... 9.15 Figure 9-9. Secondary Effluent Storage and Equalization Ponds ............................................ 9.20 Figure 9-10. Filter Feed Pump Station ..................................................................................... 9.21 Figure 9-11. Rapid Mix and Flocculation Tanks ....................................................................... 9.22 Figure 9-12. Tertiary Filters ...................................................................................................... 9.24 Figure 9-13. UV Disinfection .................................................................................................... 9.25 Figure 9-14. Effluent Pump Station .......................................................................................... 9.31 Figure 9-15. Digesters ............................................................................................................. 9.33 Figure 9-16. Digester Control Building ..................................................................................... 9.35 Figure 9-17. FOG and Food Waste Receiving Stations ........................................................... 9.36 Figure 9-18. Solids Dewatering Facilities ................................................................................. 9.38 Figure 9-19. Bio CNG System ................................................................................................. 9.41 Figure 9-20. CNG Fueling Station ............................................................................................ 9.43 Figure 10-1. Estimated Population Growth and Proposed WQCF Phase IV Expansion ......... 10.1 Figure 10-2. Total SRT with and Without Factor of Safety ...................................................... 10.8 Figure 10-3. BioWin Flow Diagram of Conventional Activated Sludge Expansion Secondary Treatment .............................................................................................. 10.10 Figure 10-4. Dynamic Simulation Results for Effluent Nitrogen – Conventional Activated Sludge ..................................................................................................................... 10.11 Figure 10-5. Preliminary Site Layout for CAS Alternative ...................................................... 10.14 Figure 10-6. MBR Process Flow Diagram ............................................................................. 10.18 Figure 10-7. Dynamic Simulation Results for Effluent Nitrogen – MBR ................................. 10.19 Figure 10-8. Preliminary Site Layout for MBR Alternative ..................................................... 10.21 Figure 10-9. WQCF Southside Aeration Basins Expansion Plan View .................................. 10.32 Figure 10-10. WQCF Southside Aeration Basins Expansion Section View ........................... 10.33 Figure 10-11. Proposed MBR for Phase IV Expansion Project ............................................. 10.35 Figure 10-12. New Sludge Dewatering Centrifuges ............................................................... 10.38 Figure 10-13. Tertiary Storage Basin Temperatures ............................................................. 10.41 Figure 10-14. Effluent Cooling Towers .................................................................................. 10.43 Figure 10-15. Effluent Pump Station Modifications ............................................................... 10.45 Figure 11-1. Current Organization Chart ................................................................................. 11.7 Figure 11-2. Correlation Between Total Sewer Length and Number of Maintenance Employees ............................................................................................................... 11.13 Figure 11-3. Recommended Organization Chart ................................................................... 11.15 Figure 12-1. Proposed CIPs Annual Estimated Expenditures ................................................. 12.7

APPENDICES
Appendix A City of Manteca 2020 Sewer System Management Plan Appendix B City of Manteca Sewer Flow Monitoring and Inflow/Infiltration Study (V&A Consulting Engineers, 2022)
Appendix C Model Selection TM
Appendix D F3 Survey Results
ATTACHMENT 2

CITY OF MANTECA WASTEWATER MASTER PLAN
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Appendix E Manteca Design Standards
Appendix F Hydraulic Model Calibration & Scenario Results Appendix G Collection System Capacity Improvement Cost Estimate Details Appendix H Solids Mass Balances Flow Diagrams
Appendix I 2017 Sanitary Sewer Condition Assessment Executive Summary Report Appendix J CIP Schedule and Costs

ATTACHMENT 2
Abbreviations
3W plant effluent
AACE Association for the Advancement of Cost Engineering AAF annual average flow
ABS acrylonitrile butadiene styrene
ACP asbestos cement pipe
ADWF average dry weather flow
ADMMF average day maximum monthly flow
ADMML average day maximum month load
AOI area of interest
ATS automatic transfer switch
BioCNG biogas renewable compressed natural gas
BOD biochemical oxygen demand
BWWF base sanitary wastewater flow
CalOSHA California Occupational Safety and Health Administration CAS chemical
CCTV closed-circuity television
CCS83 California Coordinate System of 1983
CEC contaminants of emerging concern
CEQA California Environmental Quality Act
cfm cubic feet per minute
CIMIS California Irrigation Management Information System CIP capital improvement project
CIP cast iron pipe
CIPP cured in place pipe (lining for sewer rehabilitation) City City of Manteca
CIWEM Chartered Institution of Water and Environmental Management CIWQS California Integrated Water Quality System
ATTACHMENT 2
CMCS Central Manteca Collection Strategy
CNG compressed natural gas
DAFT dissolved air flotation thickener
d/D flow depth/ pipe diameter
DEIR Draft Environmental Impact Report
DGE diesel gallon equivalents
DIP ductile iron pipe
DO dissolved oxygen
DTRW disinfected tertiary recycled water
D/V drain/vent
DWF dry weather flow
EC Electrical Conductivity
Eckert Eckert Cold Storage
EDR electrodialysis reversal
EDU equivalent dwelling unit
ENRCCI Engineering News-Record Construction Cost Index
EPA Environmental Protection Agency
F3 F3 & Associates
FFPS Filter Feed Pump Station
FOG fats, oil, and grease
FPC full pipe capacity
FRP fiberglass reinforced plastic
fps foot per second
ft feet
ft/ft foot per foot
GIS geographic information system
gpd gallons per day
gpcd gallons per capita day
GWI ground water infiltration
ATTACHMENT 2
H2S hydrogen sulfide
HDPE high-density polyethylene
HGL hydraulic grade line
HP horse power
IMLR internal mixed liquor recycle
IFAS integrated fixed-film activated sludge
I/I inflow and infiltration
in inches
IPP-3 Industrial Pipeline Project
IPS Influent Pump Station
kW kilowatt
lb/d pounds per day
LF linear feet
LiDAR light detection and ranging
LOS level of service
LS lift station
MBR membrane bioreactor
MCC motor control centers
MCL maximum contaminant levels
Mgal/d million gallons per day
mg/L milligrams per liter
MLSS mixed liquor suspended solids
MSCA Manteca Sewer Conditions Assessment
MSR Municipal Services Review
NAD 83 North American Datum of 1983
NASSCO National Association of Sewer Service Companies
NAVD 88 National Geodetic Vertical Datum of 1988
NF nanofiltration
NGVD 29 National Geodetic Vertical Datum of 1929
ATTACHMENT 2
NMCS North Manteca Collection Strategy
NOAA National Oceanic and Atmospheric Administration
NPDES National Pollution Discharge Elimination System
NTU nephelometric turbidity units
NWRI National Water Research Institute
O&M operation and maintenance
OIT operator interfaced terminal
OIT Operator-in-Training
OPCC opinion of probable construction costs
ORP oxidation reduction potential
PAC poly aluminum chloride
PCSWMM personal computer storm water management model
PDF peak day flow
PDL peak day load
PDWF peak dry weather flow
PFAs per- and polyfluorinated substances
PG&E Pacific Gas & Electric
PHF peak hour flow
PLC programmable logic controller
PPIG Public Project Infrastructure Group
PS pump station
PVC polyvinyl chloride
PWWF peak wet weather flow
RAS return activated sludge
RCP reinforced concrete pipe
RDI rainfall dependent infiltration
RDII rainfall dependent inflow and infiltration
RO reverse osmosis
ROW right of way
ATTACHMENT 2
RWQCB/Regional Board Regional Water Quality Control Board SBR sequencing batch reactor
SCADA supervisory control and data acquisition
SEEP Secondary Effluent Equalization Pond
SESP Secondary Effluent Storage Pond
SMCS South Manteca Collection Strategy
SND simultaneous nitrification and denitrification
SOI sphere of influence
SP steel pipe
SRT solids retention time
SS sanitary sewer
SSMP Sanitary Sewer Management Plan
SVI sludge volume index
SWRCB State Water Resources Control Board
TDH total dynamic head
TDS total dissolved solids
TKN Total Kjeldahl Nitrogen
TM technical memorandum
TMDL total maximum daily load
TSS total suspended solids
TWAS thickened waste activated sludge
URPS Union Road Pump Station
UTS Utility Technology Services
UVT UV transmittance
V&A V&A Consulting Engineers, Inc.

VCP vitrified clay pipe
VFD variable frequency drive
WAS Waste Activated Sludge
WDR Waste Discharge Requirements
ATTACHMENT 2
WGF wastewater generation factors
WRF Water Research Foundation
WWF wet weather flow
WWMP Wastewater Master Plan
WQCF Wastewater Quality Control Facility
WQO water quality objectives
ATTACHMENT 2
Acknowledgements
Stantec wishes to acknowledge the following City staff: Elba Mijango (Associate Engineer), Somporn Boonsalat (Acting Deputy Director of Engineering), Carl Brown (Public Works Director), George Montross (Deputy Director of Public Works - Water Resources), Dustin Valiquette (Plant Manager), Greg Showerman (Deputy Director of Engineering), and Kevin Jorgensen (Director of Engineering/City Engineer) for providing the information, access, history, and guidance that were vital to developing this Wastewater Master Plan. Their pride and dedication as stewards of the community’s resources is evident and commendable.

ATTACHMENT 2
Executive Summary
ES.1 INTRODUCTION AND BACKGROUND
ES.1.1 Scope of Work
The City of Manteca Wastewater Master Plan (WWMP) encompasses the City’s wastewater collection system and Wastewater Quality Control Facility (WQCF). The objectives of this WWMP are to evaluate the available capacity of existing facilities, determine what facility improvements are required to meet the demands for near-term and long-term growth, and develop a comprehensive road map for the City’s Capital Improvement Program.

The on-going update to the City’s General Plan, in conjunction with changing wastewater generation rates over time, have created a need to reassess the City’s wastewater collection infrastructure and treatment capacity needs for existing and future conditions. The primary goals of this WWMP are: 1) to evaluate historical and existing wastewater flows; 2) to refine collection system performance and planning criteria; 3) to build and calibrate the City’s wastewater collection system hydraulic model; 4) to evaluate the need for new wastewater collection and treatment facilities to meet existing and future needs; and 5) to update and prioritize the City’s Capital Improvement Program for wastewater collection and treatment improvements.

This WWMP report is organized into the following chapters, which are summarized in this Executive Summary:
• Chapter 1.0 Introduction and Background
• Chapter 2.0 Existing Wastewater Collection System
• Chapter 3.0 Hydraulic Model Development and Calibration • Chapter 4.0 Basis for Collection System Analysis
• Chapter 5.0 Collection System Capacity Evaluation
• Chapter 6.0 Wastewater Collection System Condition Assessment • Chapter 7.0 WQCF Background and Regulatory Requirements • Chapter 8.0 WQCF Wastewater Flows and Loads
• Chapter 9.0 WQCF Assessment of Existing Facilities and Recommended Interim Improvements • Chapter 10.0 WQCF Phase IV Expansion Project
• Chapter 11.0 Staffing Plan
• Chapter 12.0 Capital Improvement Program
• Chapter 13.0 References
ES.1.2 Study Area
The City of Manteca (Manteca) is located in the Central Valley of California within San Joaquin County, approximately 70 miles east of San Francisco, with an estimated population of 85,792 people (2021 US Census Bureau). The existing City limits encompasses an area of 13,728 acres or approximately 21.5 ATTACHMENT 2
square miles. The existing wastewater collection system includes residential (69%), commercial (8%), industrial (9%), municipal (9%), and mixed-use (4%) areas within the City. The Manteca WQCF also services surrounding member jurisdictions including a portion of the City of Lathrop, Oakwood Shores, and Raymus Village in San Joaquin County.

Manteca operates its own sewer collection system serving connections within City boundaries while member jurisdictions (Lathrop, Raymus Village, and Oakwood Shores) own and operate their own collection systems which convey wastewater flows to the City’s collection system. Figure ES-1 shows an overview of the existing sewer collection system, including city limits and member jurisdiction service areas, sewer lines, sanitary sewer pump stations, and the location of the WQCF.

ES.1.3 Background Information & Review
The following information was reviewed and incorporated into the development of this WWMP, including regulatory plans, service agreements, technical reports, and City planning documents. • The City’s collection system is currently permitted to operate under State Water Resources Control Board General Order No. 2006-0003-DWQ, Statewide General Waste Discharge Requirements for Sanitary Sewer Systems, which requires the City to develop and implement a Sewer System Management Plan (SSMP) that describes how the City operates and maintains the collection system in compliance with General Order requirements. The City of Manteca’s current SSMP dated January 8, 2020, is included in Appendix A. • The City provides sanitary sewer service to the City of Lathrop in accordance with a regional service agreement, most recently amended on May 26th, 2016, originally signed on March 5th, 1985. The terms of the current agreement outline the rights and responsibilities of each party, treatment capacities, costs, discharge limitations, and define the legal parameters associated with the regional treatment agreement. The agreement allocates 14.7% of the Manteca WQCF capacity to flows discharged from Lathrop. The City also provides sanitary sewer service to the Oakwood Lake Water District in accordance with a regional service agreement, amended in 2020, originally signed May 9, 2019. Like the agreement with Lathrop, the agreement outlines terms of the regional service agreement.
• The City’s previous Wastewater Collection System Master Plan Update (2012 Master Plan) was completed by NV5 Global Inc. in January 2013 as an update to the City’s 2006 Wastewater Collection System Master Plan (2006 Master Plan). The recommended overall trunk sewer strategy consisted of a combination of trunk sewer gravity collection system with lift stations located along the alignment to convey wastewater to an influent pump station at the WQCF. • The City of Manteca is currently working on updating their General Plan. The General Plan is a long-range (20-30 years) planning document that is considered the City’s “constitution” or blueprint, because it identifies the City’s goals and vision for growth, traffic patterns, economic development, housing, and more. Land uses within the General Plan serve as the basis to estimate wastewater flow rates from future development. Population projections from the City’s General Plan indicate a build out population of 211,003 people.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
WQCF
Outfall
4557000 4554000 4551000 4548000 4545000
4557000 4554000 4551000 4548000 4545000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Lift Station
City Owned
Privately Owned
Modeled Sanitary Sewer
Sanitary Network
Private Sanitary Network
Water Quality Control Facility Structures
City of Lathrop Discharge
City of Lathrop Collection Boundary
Raymus Village Collection Boundary
Oakwood Shores Collection Boundary
City of Manteca Limit
ES-1
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Existing Sewer Collection System
Overview
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

ES.2.1 Collection System Overview
The Manteca WQCF is located southwest of downtown Manteca at 2450 West Yosemite Avenue. The WQCF treats typical municipal wastewater generated in the City of Manteca, a portion of the City of Lathrop, and the surrounding communities of Raymus Village and Oakwood Shores. A separate industrial line accepts food processing wastewater seasonally from Eckert Cold Storage from May through November. The sewer collection system is contiguous with city limits and includes more than 19,500 service connections, 4,672 manholes, approximately 250 miles of 4-inch to 60-inch diameter collector and trunk sewer mains, and 21 miles of sewer force main that the City of Manteca is responsible for operating and maintaining. There are several privately and publicly owned lift stations in the system, data was collected for 18 of the largest pump stations.

Information regarding these conveyances and facilities is presented in this WWMP as reported by the City’s GIS database and provided by City staff. The GIS database provides pipeline diameter, material, and installation year information of sewer lines. Approximately 77% of the existing gravity sewer system is comprised of 6-inch and 8-inch diameter sewers. The most common sewer pipe materials are polyvinyl chloride (PVC) and vitrified clay pipe (VCP), which combined account for almost 88% of the system by pipe length. Approximately 40% of the existing sewer lines were installed after the year 2000, with the earliest installation year listed as 1906. The GIS database indicates that half of the sewer force mains are 12-inches in diameter and a quarter of them are 6-inches in diameter with the largest being 24-inches.

Over 80% of force mains are PVC material and 95% have unknown installation years. The GIS database included 39 sewer lift stations, data was provided for 18 lift stations, after reviewing the data 10 of which were included in the hydraulic model.

The existing sewer service area can be divided into North, South, and Central service sewershed areas.

The North Shed contributes 10 percent of the total flow, the South Shed contributes 30 percent, and the Central Shed contributes 60 percent. The majority of the collection system serves the core of the City (Central Shed), approximately bounded by State Highway 120 (SR-120) to the south, Austin Road to the east, Airport Way to the west, and Lathrop Road to the north. Within the Central Shed, the majority of the collection system flows by gravity to the Union Road Pump Station (URPS). The North Shed includes the City planning area north of SR120 and Yosemite Avenue outside of the Central Shed. Much of the predicted development is within the North Shed which is largely undeveloped and lacking infrastructure needed to serve development of this area. The South Shed includes the City planning area south of SR120 and Yosemite Avenue outside of the Central Shed. Like the North Shed, much of the South Shed remains undeveloped, though many subdivisions have been constructed and expanded along the Woodward Avenue corridor in the last 10 to 15 years. Two primary trunk sewers discharge flow into the WQCF headworks, the North Trunk Sewer collects flow discharged from the North Shed and Central Shed service areas and the South Trunk Sewer conveys flow from the South Shed service area.

The sewer service areas and the existing collection system are presented in Figure ES-2.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4560000 4557000 4554000 4551000 4548000 4545000
4560000 4557000 4554000 4551000 4548000 4545000
-13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 -13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 Legend
Modeled Sanitary Manholes
Water Quality Control Facility
Forcemain
Lift Station Status
Active
Unmodeled
Inactive
Abandoned
Modeled Sanitary Sewer
Private Sanitary Network
Water Quality Control Facility Structures
City of Lathrop Discharge
Oakwood Shores Collection Boundary
Raymus Village Collection Boundary
City of Lathrop Collection Boundary
Service Area
Central Shed
North Shed
South Shed
City of Manteca Limit
ES-2
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Sewer Collection System and Service Area
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

The flow monitoring program revealed that backwatered conditions (i.e., gravity sewer surcharging during periods when flows are well below the full pipe capacity) routinely occur at the Union Road Lift Station, surcharging was also observed at the Chadwick Unit 5 and Woodward Park pump stations. The I/I analysis revealed that basins 7, 9, and 10 had the highest I/I contributions. Basin 7 includes the Louise Avenue corridor. Basins 9 and 10 are along the south side of Moffat Boulevard on each side of SR-120.

Influent flow data recorded at the WQCF from 2016 to 2021 was used in conjunction with United States Census Bureau population data to calculate the average dry weather flow (ADWF) per capita for the service area. The average per capita flow discharged to the WQCF is 61 gallons per person per day (gpcd).

ES.3 HYDRAULIC MODEL DEVELOPMENT & CALIBRATION
This section highlights the content of Chapter 3, which documents the approach used to develop and calibrate the collection system hydraulic model.

Open channel flow hydraulic modeling software platforms were reviewed for purposes of efficiently executing the collection system components of this WWMP. Based on the City’s needs, the model of the collection system was developed using PCSWMM software by Computational Hydraulics Inc. This effort is summarized in Technical Memorandum (TM) No. 1: Hydraulic Model Software Selection, which is included in Appendix C.

The collection system model only considers the City of Manteca’s collection system. Although the City’s WQCF accepts flows from neighboring jurisdictions, the hydraulic model only simulates the City’s collection system and flows.

ES.3.1 Hydraulic Model Approach
The hydraulic modeling approach included the following:
• Develop the model using Manteca’s existing GIS and survey data. Manhole rim and invert elevations were also updated and incorporated into the model.

ATTACHMENT 2
• Assign initial sewer loads based on water meter data and then update the loads based on individual flow monitoring data.
• Identify dry and wet weather events to use for calibration. • Undertake rainfall dependent inflow and infiltration analysis for each of the meter subcatchments. • Calibrate the model using the collected flow monitoring data.

ES.3.2 Model Inputs and Structure
The hydraulic model of the collection system includes all gravity mains of 8-inch diameter and larger, plus smaller force mains and gravity sewers required for connectivity of the system. The model also includes a total of 10 pump stations and their associated force mains. Modeled facilities are shown in Figure ES-3.

During model development, the physical network of sewers, manholes, pump stations, and structures were established based on the City’s GIS database, specifically the physical information contained therein for the existing collection system. This physical network becomes the underlying framework for the model. Therefore, it is crucial that the infrastructure is reviewed for completeness and proper connectivity.

Pipe invert elevations are derived from a combination of field survey data, record drawings, and City GIS data, with adjustments applied as described in Chapter 3.0. Ground surface elevations are derived from a combination of City GIS data, field survey, and LiDAR (Laser Imaging, Detection, and Ranging) data.

Stantec subcontracted with F3 & Associates (F3) to conduct a manhole survey of 50 manholes in the system. A complete list of manholes surveyed is included in Appendix D along with the information provided by F3. Missing pipe inverts for manholes that are not surveyed are interpolated using the closest upstream and downstream manhole invert data. The model includes a total of 2,132 manholes, which includes some nodes that reflect elevation changes along force mains, clean outs or lamp holes to complete the network. A total of 2,103 sewer segments are included in the model with a total length of approximately 107 miles. A total of 10 city owned sewer lift stations are included in the model with approximately 10 miles of force main.

ES.3.3 Flow Allocation
This section describes how flows are assigned to the appropriate nodes within the collection system model. Flow inputs are assumed to originate at a parcel level. Parcels were assigned to modeled manholes based on proximity and associated water meter billing records. Sanitary flow loadings for users i.e., Base Wastewater Flow (BWWF) were developed based on water meter billing records. City of Manteca staff supplied Stantec with average daily water usage data from 2016 to 2021 for address points within the service area. These totals were used to distribute the percentage of sewer flow recorded at each of the sewer system flow monitoring locations. The groundwater infiltration (GWI) component was assumed to be 80 percent of the minimum nighttime flow and was distributed to manholes proportionally based on contributing area.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

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HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
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LOUISE AV
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Site 01
Site 02
Site 03
Site 04
Site 05
Site 06
Site 07
Site 08
Site 10
Site 11
Site 12
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Site 18
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-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Modeled Sanitary Manholes
Water Quality Control Facility
Modeled Lift Station
Other Lift Station
Flow Monitor
Modeled Forcemain
Modeled Sanitary Sewer
City of Manteca Limit
ES-3
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Flow Monitoring Locations and Modeled
Facilities
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

The assignment of parcel-based flows to the model, the calibration process, and the rainfall analysis are all described in detail in Chapter 3. Comparisons of the metered versus modeled dry weather results for the 18 monitoring locations are presented in Appendix F. A comparison of the modeled vs. measured wet weather influent response at the WQCF is shown in Figure 3-7 in Chapter 3. The model was successfully calibrated such that the simulated flows satisfactorily matched the conditions observed during the flow monitoring period and influent flow data based on calibration guidelines developed by the Chartered Institution of Water and Environmental Management (CIWEM).

ES.4 BASIS FOR COLLECTION SYSTEM ANALYSIS
This section highlights the content of Chapter 4, which includes the planning, design, and performance criteria applicable to the City’s wastewater collection system.

ES.4.1 Design Criteria
The criteria presented in this chapter are considered adjunct to the existing City Standards and Specifications and are not intended to replace or supersede those standards unless specifically stated otherwise. The City’s Standards can be found in Appendix E of this report. Key criteria addressed in this WWMP include wastewater generation factors (WGF) for General Plan land use categories, modeling of PWWF conditions, and capacity assessment of existing facilities.

Land-use based wastewater generation rates are used to establish ADWF estimates for future development. To match the modeling assumptions included in the existing system model and general development patterns observed in the City, it was determined that approximately 80% of the gross area contributes to wastewater flow generation, leaving 20% open for open space and right of way (ROW).

Therefore, the net area was used to calculate wastewater flow estimates from future developments using the WGFs presented in Chapter 4.0.

The WGFs presented in the City’s 2012 Master Plan were reviewed and updated based on the most recent General Plan land use densities and an updated wastewater unit rate of 195 gpd/EDU. This unit rate was derived from the calculated per capita flow of 61 gpcd and average household density reported by US census data from 2017 to 2021 of 3.19 persons per EDU. No adjustments were made to WGFs for non-residential land use designations from those presented in the 2012 Master Plan, aside from that of parks which was reduced from 400 gpd/acre to 100 gpd/acre. Parks typically have very low to no ATTACHMENT 2
wastewater generation component because they generally consist of open space with the majority of water use attributed to irrigation.

The estimation of PWWFs in the collection system is based on the use of a 10-year, 24-hour design storm event, per standard practice. According to the National Oceanic and Atmospheric Administration (NOAA), the 10-year, 24-hour storm for Manteca has a magnitude of 2.20 inches. For this analysis the target level of service (LOS) is based on the capacity in the collection system and the risk of surcharging that may result, as defined in Chapter 4. Pump stations are considered undersized if the associated firm capacity (i.e., with the largest pump out of service) is not sufficient to accommodate modeled peak flows.

Force mains are considered undersized of the maximum velocity exceeds 8 fps at modeled peak flows.

ES.4.2 Future Growth Assumptions
The study area considered in this Master Plan encompasses the planning areas to which the City of Manteca will provide sewer service and ultimately be responsible for operating and maintaining under build-out development conditions. This includes the North, Central, and South service areas previously described in this report each having their own collection strategy. This assumes that future development flows outside of the existing City Limits boundary and sewer service area will be routed through their respective systems. For example, future flows originating from within the North Shed boundary should flow through the North Trunk system down Airport Way to the WQCF, while flows from within the Central Shed boundary should pass through the Union Road Sewage Lift Station and Central trunk network, and flow originating from the South Shed area should be routed through the South Trunk that follows Woodward Avenue.

Future population projections from the City’s General Plan and Municipal Services Review (MSR) were reviewed for consistency with future flow projections and of level of development scenarios. The General Plan projects a buildout population of 211,003 people and the MSR projects a buildout population of 236,000 people. This WWMP assessed system performance for existing level of development conditions as well as the following projected growth scenarios, the areas served in each scenario are presented in Figure ES-4. ADWF projections for each scenario are summarized in Table ES-1.

Scenario 1 – Existing Conditions Model: This modeled scenario simulates flow in the existing collection system during a 10-year, 24-hour design storm event. This model was constructed using the calibrated wet weather flow model and applying a 10-year, 24-hour rainfall event.

Scenario 2 – Buildout of City Limits: This scenario simulates PWWF in the future collection system upon development of infill areas within the existing city limits. The majority of infill development is in the South Shed.

Scenario 3 – Buildout of the SOI Boundary: This scenario simulates PWWF in the future collection system upon development of the SOI that lies outside City Limits, as shown in Figure ES-4. The majority of SOI development is in the North Shed and South Shed.

ATTACHMENT 2
Scenario 4 – Full General Plan Buildout: This scenario simulates PWWF in the future collection system upon development of the remaining general plan development area. The majority of the remaining development area is in the North Shed.

Table ES-1. Design Horizon Flow Projections
Scenario Area (Acres) ADWF (Mgal/d) Total ADWF (Mgal/d) 2 1 – Existing 6,522 4.79 1 4.79
2 – City Limits 5,101 4.09 8.88
3 – SOI 6,254 3.84 12.72
4 – Full General Plan 6,434 2.57 15.29
Total: 24,311 15.29
Note:
1 Actual measured flows from V&A flow monitoring study. 2 Flow projections exclude City of Lathrop flows, flows presented in the table reflect modeled flows from the City of Manteca service area..

Key:

Mgal/d = Million Gallons per Day
The development of the servicing strategy for future areas prioritized gravity sewers over lift stations and forcemains to the extent deemed feasible for this WWMP. Lift stations and forcemains were identified in recommended improvements when the depth of gravity sewers exceeded approximately 25-feet.

ATTACHMENT 2
C ali fo rni a
Sacramento
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MAIN ST

AIRPORT WY
I5

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Modeled Sanitary Manholes
Lift Station Status
Active
Unmodeled
Inactive
Abandoned
Water Quality Control Facility
City of Manteca Limit
Modeled Sanitary Sewer
Forcemain
Water Quality Control Facility Structures
Private Sanitary Network
City of Manteca Limit
Scenario 1 - Existing Service Area
Scenario 2 - City Limits
Scenario 3 - Sphere of Influence
Scenario 4 - Remaining Planning Area
ES-4
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Modeled Scenario Planning Areas
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

The results of each of these scenarios are evaluated using the LOS performance criteria described in Chapter 4. The model results are used to evaluate system capacity, hydraulic performance, identify system deficiencies, and develop recommended improvements. These recommended improvements are summarized in a prioritized CIP for the collection system which includes an estimate of probable costs.

ES.5.1 Modeled Design Horizon Scenarios
This WWMP assessed collection system level of service and capacity under four different scenarios.

Each scenario represents the cumulative development of growth areas within the service area. Simulated scenarios are summarized below and in Table ES-2.

Table ES-2. Summary of Modeled Scenarios
Scenario Description Cumulative Planning
Areas
ADWF 1
(Mgal/d)
Simulated
Peak Flow 2
(Mgal/d)
Scenario 1 Existing Conditions • Existing Service Area 4.8 18.6 Scenario 2 Buildout of City
Limits
• Vacant Areas within
City Limits 8.9 30.8
Scenario 3 Buildout of SOI • SOI Planning Areas 12.7 42.6 Scenario 4 Buildout of General
Plan
• Remaining Planning
Area 15.3 49.8
Note:
1 The modeled ADWF represents only the City of Manteca service area. 2 Unattenuated peak wet weather flow for 10-year design storm after including recommended improvements.

ES.5.2 Scenario 1 – Existing Development Results
The model simulates an ADWF of approximately 4.8 Mgal/d, with a daily dry weather peak flow of 7.1 Mgal/d (existing conditions in 2022). The existing system has adequate capacity to convey dry weather flows without surcharging.

For wet weather conditions in the existing system, the model simulates a PWWF of 17.6 Mgal/d at the WQCF for the existing system 10-year, 24-hour design storm (prior to considering capacity improvements). The peak wet weather flows result in several sections within the existing system surcharging due to inadequate gravity capacity or from limited capacity of a downstream lift station.

Figure ES-5 shows the existing PWWF LOS of the calculated residual capacity for each modeled sewer segment for the 10-year, 24-hour design storm condition. Residual pipe capacity is defined as the remaining capacity in a sewer under peak flow conditions or the calculated full pipe capacity (FPC) subtracted by the peak simulated flow.

ATTACHMENT 2
C ali fo rni a
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Fresno

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MAIN ST

AIRPORT WY
I5

UNION RD
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LATHROP RD
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Modeled Sanitary Manholes
Modeled Lift Station
Other Lift Station
Water Quality Control Facility
Water Quality Control Facility Structures
Forcemain
Residual Capacity
No Residual Capacity
< 0.0 Mgal/d - 0.5 Mgal/d
< 0.5 Mgal/d - 2.0 Mgal/d
< 2.0 Mgal/d - 5.0 Mgal/d
< 5.0 Mgal/d
City of Manteca Limit
ES-5
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/25/2023
TR by MA on 10/25/2023
IR Review by MVD on 10/25/2023
Residual System Capacity
10-year, 24-hour Design Storm
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-25 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

There are several sewer sections, primarily within the Central Shed, that have limited to no residual capacity under PWWF conditions including:
• A: The 15-inch trunk in Center Street from the Union Road lift station to Elm Avenue, • B: The 10-inch sewer upstream in Elm Avenue and W. North Street, • C: The 8-inch sewer in W. North Street between Charles and Cottage Avenue, • D: The 15-inch sewer in Garden Gate Drive between Edison and Jason Street, and • E: The 8-inch sewer in Oregon Street between Sequoia and Park Avenue • The 12-inch sewer upstream of the Chadwick Unit 5 pump station in Hastings Drive between South Airport Way and North Landreth Lane
• The 54-inch North Trunk sewer west of Airport Way is showing no residual capacity due to very flat sewers but does not cause surcharging under this condition.

Areas A through E are within the Central Shed and are identified on Figure ES-6. There are also some isolated sewer segments within the Central Shed that were identified as having no residual capacity due to very shallow slopes but are unlikely to cause upstream surcharging issues unless blockages occur.

These segments should be checked condition and maintained through O&M activities.

Exceedances of the pump station firm capacity are predicted at two lift stations:
• The Woodward Park lift station, where PWWF exceeds the firm and total capacity of the station. • The Chadwick Unit 5 lift station, where PWWF exceeds the firm capacity of the station by 0.03 Mgal/d.

In addition, while not specifically a capacity constraint, the Shadowbrook lift station forcemain velocity exceeds 8 fps (maximum LOS velocity) when operating at the firm capacity, which can result in high headlosses and energy consumption as well as potential waterhammer effects. It is recommended that the pumping capacity and efficiency of the Shadowbrook Park lift station be further evaluated.

ATTACHMENT 2
J3
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205
Ripon
Manteca
4551000
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Legend
Modeled Sanitary Manholes
Modeled Lift Station
Other Lift Station
Water Quality Control Facility
Water Quality Control Facility Structures
Forcemain
Residual Capacity
No Residual Capacity
< 0.0 Mgal/d - 0.5 Mgal/d
< 0.5 Mgal/d - 2.0 Mgal/d
< 2.0 Mgal/d - 5.0 Mgal/d
< 5.0 Mgal/d
City of Manteca Limit
ES-6
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 11/2/2023
TR by MA on 11/2/2023
IR Review by MVD on 11/2/2023
Residual System Capacity
Area of Concern
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-11-02 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

3. Background: Esri, NASA, NGA, USGS, Esri Community Maps Contributors, San Joaquin County GIS/Planning, San Joaquin County Public Works, California State Parks, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, US Census Bureau, USDA, San Joaquin County GIS/Planning, California State Parks, Esri, HERE, Garmin, SafeGraph, FAO, METI/NASA, USGS, Bureau of Land Management, EPA, NPS
0 500 1,000
Feet
"($ $
¯ (At original document size of 11x17)
1:12,000
Residual Capacity = Full Pipe Flow - Peak Flow
A
E
C
D
B
ATTACHMENT 2
The deficiencies noted above were further analyzed against the severity of other LOS criteria and it was determined that the following improvements should be considered:
• Replacement of several segments of sewers upstream of the Union Road Lift Station including:
• Project 1: Replacement of the existing 15-inch sewer from the Union Lift Station from the Union Road lift station along W Center Street to Elm Avenue with an 18-inch sewer. • Project 2: Replacement of the existing 10-inch sewer along Elm Ave W North Stret and E North Street to W Fremont Ave with a 15-inch sewer.
• Project 3: Replacement of the existing 10-inch sewer along E North Street from W Fremont Ave to Marie Ave with a 12-inch sewer.
• Project 4: Replacement of the existing 8-inch sewer along E North Street from Charles Ave to Cottage Ave with a 10-inch sewer. The sewers within the gap between Project 3 and Project 4 should also be evaluated for condition and considered for replacement if required. • Project 5: Capacity improvements at the Woodward Park lift station. The two alternative improvements for the Woodward Park pump station are discussed in detail in Section 5.3.1, and include:

A installing 4,030 LF of 36-inch sewer to extend the existing South Trunk in Woodward Avenue to reach the unused existing 36-inch sewer at the intersection of Woodward Avenue and South Main Street.

B increasing the firm pumping capacity to meet the simulated maximum inflow of approximately

2.8 Mgal/d by adding an additional pump to the station or swapping out the existing pumps.

The recommended alternative is Alternative A which would allow the lift station to be taken offline.

These improvements as shown in plan-view on Figure ES-7 were incorporated into the model, which resulted in an approximate 1 MGD increase to the total peak flow at the WQCF at 18.6 Mgal/d as noted in Table ES-2. The increase in peak flow after the improvements are included is a result of less attenuation in the system due to capacity constraints. The other locations that were noted as residual capacity LOS deficiencies are not recommended for capital improvements but should be further evaluated and / or monitored regularly with O&M activities.

ATTACHMENT 2
J3
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205
Ripon
Manteca

YOSEMITE AV

WOODWARD AV

MAIN ST

UNION RD
15in
12in
18in
10in
36in
4551000 4548000
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ES-7
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/24/2023
TR by MA on 10/24/2023
IR Review by MVD on 10/24/2023
Recommended Improvements to Address
Existing Capacity Deficiencies
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-24 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

3. Background: Esri, CGIAR, USGS, Esri Community Maps Contributors, San Joaquin County GIS/Planning, San Joaquin County Public Works, California State Parks, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, US Census Bureau, USDA, San Joaquin County GIS/Planning, California State Parks, Esri, HERE, Garmin, SafeGraph, FAO, METI/NASA, USGS, Bureau of Land Management,

EPA, NPS
0 500 1,000
Feet
"($ $
¯ (At original document size of 11x17)
1:15,000
Union
Road
Legend
Modeled Lift Station
Other Lift Station
Forcemain
Modeled Sanitary Sewer
Master Plan Project
Project 1
Project 2
Project 3
Project 4
Project 5
City of Manteca Limit
Woodward
Park
Curran Grove
ATTACHMENT 2
ES.5.3 Scenarios 2 to 4 – Future Growth Analysis
Following the evaluation of the existing system capacity and identification of improvements in Scenario 1, the model was progressively expanded with sewage loading characteristics consistent with the future development conditions defined by the City’s General Plan, including:
• Scenario 2 – Buildout of City Limits
• Scenario 3 – Buildout of the SOI
• Scenario 4 – Full General Plan Buildout
The modeled results for the 10-year, 24-hour design storm conditions under each level of development scenario are included in Appendix F.

The following deficiencies and associated improvements were identified as part of this evaluation:

Woodbridge Park lift station: This pump station has the largest improvement need, requiring firm capacity to increase from 2.09 Mgal/d to 12.40 Mgal/d at buildout.

Chadwick Unit 5 lift station: Firm capacity would need to be expanded from 1.26 Mgal/d to 2.31 Mgal/d at buildout.

Villa Ticino lift station: Firm capacity would need to be expanded from 0.73 Mgal/d to 0.90 Mgal/d at buildout.

Roberts Estates lift station: Firm capacity would need to be expanded from 0.29 Mgal/d to 0.52 Mgal/d at buildout.

Evans Estates lift station: Firm capacity would need to be expanded from 1.05 Mgal/d to 4.52 Mgal/d and the existing 8-inch force main would need to be expanded to 14-inches at buildout.

Woodward Park lift station: If not addressed by gravity improvement recommended in Project 5A for existing system improvements, firm capacity will ultimately need to be expanded from 0.85 Mgal/d to 5.80 Mgal/d and the 12-inch force main would need to be expanded to at least 20-inches at buildout to accommodate flows from both Evans Estates and Woodward Park.

The City of Manteca has already made investments in their future collection system by preemptively installing oversized lines for future gravity sewers. The following improvements were previously identified by the City as system improvements required to complete the network of these gravity sewers.

Project 5A: South Woodward Trunk Extension – This project was presented as the recommended alternative to upgrading the Woodward Park lift station under existing conditions. The existing 36-inch South Trunk sewer in Woodward Avenue is missing a segment between Pagola Way and South Main Street. In the upstream, the City has already installed a 36-inch sewer to convey flows that currently conveyed through the Woodward Park pump station by gravity. This project would eliminate the need to expand both the Woodward Park and Evan’s pump stations under future development conditions. The 36- inch pipe has a capacity of approximately 10.6 Mgal/d at a slope of at least 0.0006 ft/ft.

ATTACHMENT 2
Project 6: Central Union Road Trunk Extension – The City recently completed a project replacing the North Trunk Sewer, which replaced the 36-inch trunk sewer with a larger and deeper 54-inch sewer. This project was the first leg of an overall project intended to take the Union Road lift station offline. The Central Trunk could be extended from the upstream point of North Trunk project to bypass the lift station and allow flow from the Central Shed to flow by gravity to the WQCF. City staff have noted many on-going issues with the lift station that were observed in the flow monitoring data collected as part of this WWMP.

Although the capacity of the lift station appears to be sufficient, this project is recommended to eliminate surcharge experienced during operating conditions and O&M costs associated with the station. There appears to be enough fall to achieve a slope greater than 0.002 ft/ft which would provide capacity greater than 19.0 Mgal/d.

Project 7A: North Trunk Extension on Airport Way – A 48-inch sewer exists at the upstream end of Airport Way, where flow is currently conveyed to the Woodbridge Park pump station. The City recently installed approximately 2,900 LF of 36-inch sewer in Airport Way between the Manteca Park Golf Course and Louise Avenue. Extending the North Trunk sewer along Airport Way to the Woodbridge Park pump station would allow the station to be taken offline in addition to those that lie within the project extents, including Chadwick Unit 5, Assieh Development, MUSD, and Villa Trinco. Another un-used existing line exists to take the Centerpoint Pump Station offline and serve the northern planning area. The 48-inch sewer should be constructed at a slope of 0.00057 ft/ft providing 22.2 Mgal/d of capacity.

Project 7B: Expand North Shed Lift Stations – As an alternative to Project 7A, the North Trunk Extension on Airport Way, the lift stations in the North Shed could be expanded to provide sufficient capacity for buildout flows. This would require expanding Woodbridge Park, Villa Ticino, and Chadwick Unit 5. No improvements to the existing 24-inch force main would be required. The Woodbridge Park lift station would require the most extensive improvements to expand it from its current capacity of 2.1 Mgal/d to approximately 12.4 Mgal/d. Villa Ticino would need to be expanded to approximately 1.0 Mgal/d and Chadwick Unit 5 would need to be expanded to approximately 2.4 Mgal/d. The Villa Ticino and Chadwick Unit 5 lift stations are located in the sidewalk and do not have room to expand and with such a large expansion at Woodbridge Park it’s likely that each of these lift station expansions would require land acquisition. The Villa Ticino lift station could currently be taken offline if flows were redirected to the existing 36-inch sewer in Airport Way.

Both Project 7A and Project 7B present their own unique challenges that warrant further investigation.

Therefore, costs for both alternatives are presented in the final section of Chapter 5.

ATTACHMENT 2
In addition to the previously identified improvements listed above, the following projects are also recommended:

Project 8: South Main Trunk to Evans (Evans) – Upon completion of Project 5, it is recommended that the City install a new 27-inch sewer in South Main Street to allow the Evans lift station to be taken offline.

Thereby avoiding future pump station expansions, force main improvements, and the O&M costs associated with the Evans lift station. The 27-inch sewer should be constructed with a minimum slope of

0.0007 ft/ft to achieve capacity of 5.1 Mgal/d.

Project 9: South Airport Way and Yosemite Avenue (Fishback) – The sewer downstream of the Fishback lift station collection shed is predicted to fail LOS criteria under future development conditions and was identified under all three future development scenarios. This deficiency is due to the large amount of infill added to the collection shed. The City’s GIS database indicates that the lift station discharges to a gravity line (8-inch) that is smaller than the gravity lines within the collection area (10-inch). As a result, surcharging is predicted to occur in the gravity line downstream of the force main discharge location in North Airport Way, south of the North Trunk Sewer. As an alternative to upsizing the 8-inch gravity line in Airport Way, the City could install a new 10-inch gravity line all the way to the lift station and take it offline.

The 10-inch sewer installed at standard slopes (0.0025 ft/ft) has a capacity of approximately 0.7 Mgal/d.

Project 10: South Airport Way Roberts Estates to Daniels (Roberts Estates) – The Roberts Estates lift station can be taken offline by extending a 10-inch sewer down Airport Way from the lift station at Wawona Street to the 12-inch sewer in Daniels Street. The 10-inch sewer installed at standard slopes (0.0025 ft/ft) has a capacity of approximately 0.7 Mgal/d.

The following projects are recommended to serve future development.

Project 11: Yosemite Square Lift Station and Improvements – To serve the area referred to as Yosemite Square a 2.4 Mgal/d lift station will be required to convey flow to the South Trunk in Woodward Avenue.

The new 8-inch force main should be routed to an existing 18-inch sewer crossing at the intersection of Woodward Avenue and Moffat Boulevard. It is assumed that the existing 18-inch force main crossing is not being used and will be tied into a new 15-inch sewer in Woodward Avenue to be installed as part of an upcoming roadway realignment project. The cost of this 15-inch sewer in Woodward Avenue is included in this project in addition to approximately 3,230 LF of 15-inch sewer needed to serve the area upstream of the lift station. The 1,425 LF 15-inch sewer in Woodward Avenue should be installed with the highest slope possible, assumed to be 0.006 ft/ft, providing a capacity of 3.2 Mgal/d.

Project 12: Austin Road Industrial Area Trunk – A new trunk extending east from the existing 24-inch sewer in South Main Street to Austin Road is recommended to serve the Austin Road Industrial Area.

This project assumes steeper than minimum slopes to follow the existing ground surface. The project assumes the following: 2,950 LF of 24-inch sewer at 0.0012 ft/ft, 5,300 LF of 21-inch sewer at 0.0012 ft/ft, and 2,350 LF of 18-inch sewer at 0.0015 ft/ft. It should be noted that larger pipe sizes may be required if these slopes are not achieved. The project should provide a minimum capacity of 3.8 Mgal/d at the downstream end.

ATTACHMENT 2
Project 13: North Industrial Area Trunk – A 15-inch sewer extending from the Austin Road Industrial Area Trunk in South Austin Road is recommended to serve the northern portion of the development. The 15- inch sewer at the standard slope (0.0015 ft/ft) has a capacity of approximately 1.6 Mgal/d.

Project 14: Yosemite Square Service Area – To serve the portion of the Yosemite Square lift station service area outside of City Limits a 15-inch sewer in is proposed in Austin Road. The 15-inch sewer at the standard slope (0.0015 ft/ft) has a capacity of approximately 1.6 Mgal/d.

Project 15: Oleander Avenue Extension – To serve the southern SOI area an extension of the existing 12-inch sewer in Oleander Avenue and a new 10-inch sewer in S. Airport Road are recommended. The 12-inch sewer at the standard slope (0.002 ft/ft) has a capacity of approximately 1.0 Mgal/d. The 10-inch sewer installed at standard slopes (0.0025 ft/ft) has a capacity of approximately 0.7 Mgal/d.

Project 16: Highway 99 Crossing at Northland Road – A new 24-inch trunk sewer crossing Highway 99 at Northland Road is recommended to serve the North Shed SOI area and accept flow bypassed from the Central Shed. This trunk ties into the existing 36-inch sewer stub that exists along the Manteca Tidewater Bikeway. A slope of 0.011 ft/ft is recommended for a capacity of 4.9 Mgal/d.

Project 17: East Lathrop Road Trunk – This project proposes a new 18-inch sewer in South Frontage Road extending from the Highway 99 Crossing at Northland Road (Project 16) to Lathrop Road and a 15- inch sewer continuing east to Cottage Avenue. The 18-inch and 15-inch portions of this sewer sit at a slope of 0.0015 ft/ft. The downstream end capacity is approximately 2.6 Mgal/d.

Project 18: Northland Road Trunk – An 18-inch sewer extending east down Northland Road from the proposed Highway 99 crossing in Project 16. The 18-inch sewer at the standard slope (0.0012 ft/ft) has a capacity of approximately 2.3 Mgal/d.

Project 19: Northland Road Branches – Two 12-inch sewers are included to direct flow from the Northern SOI area to the Northland Road Trunk recommended in Project 18. The 12-inch sewers at the standard slope (0.002 ft/ft) have a capacity of approximately 1.0 Mgal/d each.

Project 20: Louise/Nehemiah Branches – This project includes two 12-inch sewer extensions from the existing system to Austin Road to serve development east of the Central Shed. One that ties into the 18- inch sewer in East Louise Avenue at Pestana Avenue and one that ties in to the 18-inch sewer in Pestana Avenue at Nehemiah Drive. The 12-inch sewers at the standard slope (0.002 ft/ft) have a capacity of approximately 1.0 Mgal/d each.

Project 21: South Union Road Extension – To serve the southern SOI area an extension of the existing 12-inch sewer in South Union Road is recommended. The sewer should match the existing slope of 0.002 ft/ft having a capacity of approximately 1.0 Mgal/d.

Project 22: Cottage Avenue – To serve the SOI area south of Lathrop Road a 12-inch sewer is recommended to extend in Cottage Avenue from the 15-inch East Lathrop Road Trunk (Project 17). The 12-inch sewer installed at standard slopes (0.002 ft/ft) has a capacity of approximately 1.0 Mgal/d.

ATTACHMENT 2
Project 23: North Shed Union Road Trunk – Extending the existing 30-inch sewer north along Union Road to Lovelace Road is recommended to serve the remaining planning area. The 30-inch sewer should match the existing slope of 0.0006 ft/ft providing approximately 6.5 Mgal/d of capacity.

Project 24: Manteca Junction Trunk – This project recommends a 10-inch sewer extending further north along Union Road from Project 23. The 10-inch sewer installed at standard slopes (0.0025 ft/ft) has a capacity of approximately 0.7 Mgal/d.

Project 25: Lovelace Road Trunk - 99 Crossing – A 24-inch sewer extension east from Lovelace and Union Road crossing Highway 99 and a 15-inch sewer from Highway 99 to Castle Road. The sewers should be installed at standard slopes, the 24-inch sewer with a slope of 0.0008 ft/ft has a capacity of 4.1 Mgal/d and the 15-inch sewer with a slope of 0.0015 ft/ft has a capacity of approximately 1.6 Mgal/d, The newly installed 36-inch North Trunk Sewer in Airport Way is predicted to fail LOS criteria in Scenario 4 due to the addition of flow from the upstream buildout service area. Surcharging depth is predicted to reach 2.7 feet above the pipe crown between Crom Street and Geneva Way, however improvements are not recommended due to its recent installation and significant depth, which maintains freeboard depths greater than 19 feet despite surcharging, resulting in limited risk of impacts to the City. The system infrastructure needed to serve future development at each level of development is shown in Figure ES-8.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Project 5
Project 6
Project 7
Project 12
Project 20
Project 24
Project 15
Project 16
Project 18
Project 23
Project 19
Project 11
Project 13
Project 22
Project 25
Project 17
Project 14
Project 21
Project 10
Project 9
Project 8
15in
12in
18in
12in
12in
12in
24in
10in
15in
18in
24in
15in
12in
15in
15in
30in
12in
21in
24in
8in
18in
15in
12in
10in
10in
24in
36in
36in
48in
Chadwick U5
Fishback
Union Road
Villa Ticino
Woodbridge
Park
Woodward Park
Evans
4560000 4557000 4554000 4551000 4548000 4545000
4560000 4557000 4554000 4551000 4548000 4545000
-13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 -13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 ES-8
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 11/3/2023
TR by MA on 11/3/2023
IR Review by MVD on 11/3/2023
Recommended Future System
Improvements
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-11-03 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

3. Background: San Joaquin County GIS/Planning, California State Parks, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, USDA, Merced County Association of Gov, Esri, HERE, Garmin, FAO, NOAA, USGS, EPA, Esri, USGS
0 0.5 1
Miles
"($ $
¯ (At original document size of 11x17)
1:60,000
Legend
Modeled Lift Station
Other Lift Station
Removed with CIP
Water Quality Control Facility
Modeled Sanitary Sewer
Water Quality Control Facility Structures
Forcemain
General Plan Boundary
City of Manteca Limit
Master Plan Projects
Assumed Projects
Recommended Improvements to Address Future Capacity Deficiencies System Infrastructure to Serve Future Development
Project 11 Lift Station
Project 11 Forcemain
CIP 5
CIP 8
CIP 11
CIP 12
CIP 13
CIP 14
CIP 15
CIP 16
CIP 17
CIP 18
CIP 19
CIP 20
CIP 21
CIP 22
CIP 23
CIP 24
CIP 25
Tributary to
the Existing
System
CIP Service Area
ATTACHMENT 2
ES.5.4 Phasing Strategies and Potential Alternatives
The implementation of the recommended projects should prioritize existing system improvements, while the timing and need for the recommended future projects will depend on the location and rate of growth and development within the City’s General Plan service area. As such, the recommended project phasing strategy for the CIP as presented in Chapter 12 are subject to these variables and should be periodically reviewed as part of the City’s infrastructure planning processes. For the purposes of this WWMP, the collection system CIP projects are presented in the order they should be constructed based on the progression of the modeled scenarios.

Many of the recommended projects are interdependent or will trigger the implementation of the downstream improvements. Project 5 and Project 7 are larger deep gravity sewers that connect gaps in previously constructed oversized portions of the existing system that will facilitate decommissioning of several lift stations. These projects also serve as the major conduit for future growth in the South Shed (Project 5) and North Shed (Project 7), making these projects a key component of the overall collection system CIP. These projects will have significant construction challenges due to their depth, location in crowded utility corridors, and highway/railroad crossings. As such, alternatives for both Project 5 and Project 7 have been presented and included the OPC evaluation.

ES.5.5 Conceptual Opinion of Probable Cost
The purpose of this section is to present a conceptual opinion of probable cost for each of the recommended improvements to the City’s wastewater collection system. Cost estimates prepared for this Master Plan are developed in accordance with the guidelines of the Association for the Advancement of Cost Engineering (AACE) International for a Class 5 Estimate. Construction and capital cost estimates are presented in March 2023 dollars corresponding to an Engineering News-Record Construction Cost Index (ENRCCI) of 13,176. Subsequent preliminary and detailed design efforts will serve to refine and confirm the estimates presented herein. Detailed cost estimates and unit costs are included in Appendix G for each project.

The recommended CIP list for the wastewater collection system is presented in Tables ES-3 through ES6. The information presented in the tables includes:
• An ID number assigned to the improvement
• Name of the improvement
• Service Area
• Description of the improvement
• Justification for the improvement
• Level of development scenario identified/needed
• Project quantities involved
• Project actions/notes
• Estimated capital cost
ATTACHMENT 2
Table ES-3. Recommended Collection System Improvements – Scenario 1 ID Name Service Area Description Justification Quantities Actions/Notes Total Project Costs 1 W. Center Street Trunk Central Shed Upsize the existing 15-inch sewer to 18-inches
Existing system model shows
surcharge failing LOS criteria.
~3,800 LF of 18-inch sewer
pipe Also included in Chapter 6 condition projects $4,880,000 2 Elm/West North Street Trunk Central Shed Upsize existing 10-inch sewer to 15-inches
Existing system model shows
surcharge failing LOS criteria.
~4,510 LF of 15-inch sewer
pipe Also included in Chapter 6 condition projects $5,080,000 3 10-inch East North Street Trunk Central Shed Upsize existing 10-inch sewer to 12-inches
Existing system model shows
surcharge failing LOS criteria.
~1,325 LF of 12-inch sewer
pipe Also included in Chapter 6 condition projects $1,660,000 4 8-inch East North Street Trunk Central Shed Upsize existing 8-inch sewer to 10-inches
Existing system model shows
surcharge failing LOS criteria.
~560 LF of 10-inch sewer
pipe
This area could be monitored as projects 1-3
mitigate most surcharging identified in this
portion of the system.
$510,000
5A South Woodward Trunk Extension South Shed Complete existing south trunk with new 36-inch sewer.

Existing system model shows
insufficient capacity at Woodward Park
pump station.
~4,030 LF of 36-inch sewer
pipe
This is a previously identified project and
completes previous south trunk planning. $12,640,000
6 Central Union Road Trunk Extension Central Shed
Replace existing 36-inch sewer,
24-inch force main, and Union
Road LS with new deeper 36-
inch trunk.

Existing Union Road lift station suffers
from chronic mechanical failures,
deterioration, and operational
concerns.
~5,030 LF of 36-inch sewer
pipe Also included in Chapter 6 condition projects $16,170,000 ATTACHMENT 2
Table ES-4. Recommended Collection System Improvements – Scenario 2 ID Name Service Area Description Justification Quantities Actions/Notes Total Project Costs 7A North Trunk Extension on Airport
Way North Shed
Replace existing force main
system with 48-inch gravity
sewer
Insufficient capacity at Woodbridge
Park, Chadwick U5, and Villa Ticino
pump stations.
~7,670 LF of 48-inch sewer
pipe
Constructability of this project may be difficult in
an already crowded utility corridor $34,340,000
7B Expand North Shed Lift Stations North Shed
Alternative to Project 7 (North
Trunk Extension on Airport Way)
Expand Existing Lift Stations
Insufficient capacity at Woodbridge
Park, Chadwick U5, and Villa Ticino.

Woodbridge Park (12.4
Mgal/d)
Chadwick U5 (2.4 Mgal/d)
Villa Ticino (1.0 Mgal/d)
Land acquisition required. No force main
improvements. Note: costs exclude land
acquisition
$29,530,000
8 S. Main Trunk to Evans South Shed Replace existing 8-inch force main with 27-inch gravity sewer
Insufficient capacity at Evans pump
station and force main system.
~2,690 LF 27-inch sewer
pipe This project may be combined with Project 5. $7,180,000 9 S. Airport Way and Yosemite Ave.
(Fishback) South Shed
Replace existing 6-inch force
main and 8-inch gravity sewer
with 10-inch gravity sewer
Discharge from the Fishback lift station
overwhelms downstream gravity
sewer.
~2,665 LF 10-inch sewer
pipe
Force main routing in model may be incorrect
based on discussion with City staff, general
service design of surrounding area should
consider options to take lift station offline.
$3,100,000
10 S. Airport Way Roberts Estates to
Daniels South Shed Replace existing 6-inch force main with 10-inch gravity sewer Insufficient capacity at Roberts Estate
pump station.
~1,320 LF of 10-inch sewer
pipe
General service design of surrounding area
should consider options to take lift station offline. $1,750,000 11 Yosemite Square Lift Station and
Improvements South Shed
Construct new 2.4 Mgal/d lift
station and 15-inch service area
sewer. Extend 15-inch sewer
downstream of new 8-inch
forcemain.

Provide service to Yosemite Square
and surrounding area.
~4,660 LF 15-inch sewer
pipe, 2.4 Mgal/d pump
station, and ~4,860 LF 8-
inch force main
Force main should be routed to existing 18-inch
highway crossing. The highway crossing should
tie into the new 18-inch sewer in the realignment
of Woodard Avenue.
$12,880,000
12 Austin Road Industrial Area Trunk South Shed New 24 to 18-inch trunk sewer. Provide service to the Austin Road Industrial Area
~2,355 LF of 18-inch sewer
pipe, ~5,300 LF of 21-inch
sewer pipe, and ~2,945 LF
of 24-inch sewer pipe
Ties into existing 24-inch trunk upstream of
Evans lift station. $20,810,000
13 South Austin Road - Industrial Area South Shed Extend 15-inch sewer in Austin Road.

Provide service to the northern portion
of the Industrial Area
~4,335 LF of 15-inch sewer
pipe Ties into Austin Road Industrial Area Trunk. $5,780,000 ATTACHMENT 2
Table ES-5. Recommended Collection System Improvements – Scenario 3 ID Name Service Area Description Justification Quantities Actions/Notes Total Project Costs 14 Yosemite Square Service Area South Shed New 15-inch trunk sewer. Provide service to the southern portion of the Yosemite Square service area.
~3,575 LF of 15-inch sewer
pipe Ties into Yosemite Square lift station. $4,240,000 15 Oleander Avenue Extension/ S.

Airport Way Sewer South Shed
Extend existing 12-inch sewer in
Oleander Avenue into SOI.

Install a new 10-inch sewer in
Airport Way.

Provide service to southern SOI area.
~2,255 LF of 12-inch sewer
pipe
~3,365 LF 10-inch sewer
Match existing 12-inch slope, 0.002 ft/ft. 10-inch
at 0.0025 ft/ft or greater $6,660,000
16 Highway 99 Crossing at Northland
Road North Shed Construct new 24-inch sewer and highway crossing. Provide service to northern SOI area. ~3,515 LF of 24-inch sewer pipe Ties into existing system at Tidewater bike path.

Includes highway crossing $9,310,000
17 East Lathrop Road Trunk North Shed Construct new 18-inch and 15- inch sewer. Provide service to northern SOI area.
~4,000 LF of 15-inch sewer
pipe, ~3,340 LF of 18-inch
sewer pipe.

Assumes slope of 0.0015 ft/ft $12,060,000
18 Construct new 24-inch bypass
sewer
North Shed Construct new 18-inch sewer. Provide service to northern SOI area. ~3,790 LF of 18-inch sewer pipe
Drop manhole recommended at downstream end
to reduce depth. $6,630,000
19 Northland Road Branches North Shed Construct new 12-inch sewers. Provide service to northern SOI and planning area.
~5,255 LF of 12-inch sewer
pipe
Variable routing and pipe sizing depending on
actual development. $6,350,000
20 Louise/ Nehemiah Branches Central Shed Construct new 12-inch sewers. Provide service to eastern SOI area. ~5,250 LF of 12-inch sewer pipe Ties into Louise and Pestana Avenue lines. $5,160,000 21 South Union Road Extension South Shed Extend existing 12-inch sewer in South Union Road into SOI. Provide service to southern SOI area. ~3,940 LF 12-inch sewer pipe Match existing slope, 0.002 ft/ft. $4,590,000 22 Cottage Avenue North Shed Construct new 12-inch sewer. Provide service to northern SOI area. ~2,410 LF of 12-inch sewer, Ties into East Lathrop Road Trunk. $3,080,000 ATTACHMENT 2
Table ES-6. Recommended Collection System Improvements – Scenario 4 ID Name Service Area Description Justification Quantities Actions/Notes Total Project Costs 23 North Shed Union Road Trunk North Shed Construct new 30-inch sewer. Provide service to remaining planning area.
~4,695 LF of 30-inch sewer
pipe
Requires upsizing of existing 18-inch section of
Union Road sewer. $13,130,000
24 Manteca Junction Trunk North Shed Construct new 10-inch sewer. Provide service to remaining planning area.
~3,010 LF of 10-inch sewer
pipe
Variable pipe size depending on actual flow
routing and development conditions. $3,730,000
25 Lovelace Road - 99 Crossing North Shed Construct new 24 to 15-inch sewer.

Provide service to remaining planning
area.
~5,650 LF of 24-inch sewer
pipe, ~3,605 LF of 15-inch
sewer pipe
Includes highway crossing. $18,090,000
ATTACHMENT 2
ES.6 WASTEWATER COLLECTION SYSTEM CONDITION

ASSESSMENT
This section highlights the content of Chapter 6, which summarizes the sanitary sewer condition assessment conducted by Stantec Consulting Services Inc. (Stantec) in 2017. This previous assessment included 52,150 lineal feet sewer pipeline from 60-inches to 10-inches in diameter and inspection of 187 manholes. The assessment was summarized in a report titled City of Manteca Sewer Conditions Assessment dated August 2017 (MSCA). The purpose of including this summary is to ensure that the recommendations of the assessment are carried through in the overall wastewater Capital Improvement Program (CIP) developed as part of this WWMP.

This chapter is divided into the following sections:
• Background
• Summary of Sewer Conditions Assessment
• Cost Summary of Recommended Projects
ES.6.1 Background
The City of Manteca currently operates and maintains approximately a 250 miles of sanitary sewer gravity pipeline including 4,672 sanitary sewer manholes. The City is required to have a Sewer System Management Plan (SSMP) in accordance with the State Water Resources Control Board (SWRCB) General Waste Discharge Requirement (WDR) provisions that requires all publicly owned wastewater dischargers with a collection system greater than one mile in length develop a SSMP. Under Section 6.8 (WDR Section D.13.iv.c) the SSMP is required to develop a rehabilitation and replacement program (Program) to identify and prioritize collection system deficiencies and implement short-term and long-term rehabilitation actions to address each deficiency. This Program includes regular visual and television (TV) inspections of manholes and sewer pipes and a system of ranking the condition of the sewer pipes that are at risk of collapse or prone to more frequent blockages due to pipe defects. Also, the Program should include a capital improvement plan (CIP) that addresses proper maintenance and protection of the sewer collection system assets.

ES.6.2 Summary of Sewer Condition Assessment
The MSCA used the National Association of Sewer Service Companies (NASSCO) rating system to classify sewer collection system defects by the following groups: structural, operation, construction, and miscellaneous. Each individual pipeline segments and manholes were then bundled into areas to develop projects that could be included in a Capital Improvement Program. The original report identified 14 areas of which 3 are currently identified for upsizing the pipelines under CIP Projects 1, 2 and 6 described in Chapter 5. Ongoing project repair work completed by the City since the MSCA has reduced the areas needing rehabilitation or replacement (RR) to the following 7 areas. • Project No. 26: Alley between Center Street and Yosemite Avenue from west of Sherman Avenue to the intersection of the UPRR right of way and Center Street. Project includes point repair 4 segments of pipeline, dig and replace 3 segments of pipeline, and rehabilitate 9 manholes.

ATTACHMENT 2
• Project No. 27: Main Street from Garfield Avenue to Moffat Street then along Main Street to alley north of Yosemite Avenue. Project includes dig and replace 3 segments of pipeline and CIPP 5 segments of pipeline.
• Project No. 28: Oak Street from Main Street to Willow Avenue. Project includes point repair 4 segments of pipeline and rehabilitate 7 manholes.
• Project No. 29: Sequoia Avenue from Oregon Street to the alley north of Nevada Street. Project includes point repair 1 segment of pipeline, rehabilitate 1 manhole, and replace 2 manholes. • Project No. 30: Along Tidewater Bike Path from Sandalwood Lane to Louis Avenue. Project includes point repair 1 segment pipeline, dig and replace 2 segments of pipeline, and rehabilitate 9 manholes.
• Project No. 31: Walnut Avenue from the alley north of Nevada Street to the UPRR right of way.

Project includes point repair 3 segments of pipeline, dig and replace 1 segment of pipeline, CIPP 1 segment of pipeline, replace frame/cover on 2 manholes, and rehabilitate 7 manholes. • Project No. 32: Saint Dominic’s Drive from just north of Yosemite Avenue to just south of the golf course. Project includes rehabilitation of 4 manholes.

The RR project areas are shown on Figure ES-9.

ES.6.3 Cost Summary of Rehabilitation and Replacement Projects Table ES-7 summarizes the combined pipeline and manhole rehabilitation or replacement costs for each project area. In addition to the improvements to the existing areas, the City should continue inspecting the remainder of their system. Recommendations from the SSMP should be implemented to continue cleaning and inspecting the pipelines (250 miles) and manholes (4,700 manholes) within the system at a rate of approximately 5% to 10% per year, respectively.

Table ES-7. Summary of Project Repair/Rehabilitation/Replacement Costs ID Description Cost
26 UPRR Right of Way and Ally Between Center Street and Yosemite $489,000 27 Moffat Boulevard and Main Street $1,022,000
28 Oak Street from Main Street to Willow Avenue $98,000 29 Sequoia Avenue from Oregon Street to Alley north of Nevada Street $53,000 30 Tidewater Bike Path from Sandalwood Lane to Louis Avenue $348,000 31 Walnut Avenue from the alley north of Nevada Street to the UPRR $279,000 32 St. Dominic’s Drive from north of Yosemite Avenue to Golf Course $29,000 Total $2,318,000
ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Project 28
Project 6
Project 1
Project 30
Project 31
Project 2 & 3
Project 32 Project 29
Project 27
Project 26
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality
Control Facility
Forcemain
Sanitary Network
Water Quality
Control Facility
Structures
Lift Station
City Owned
Privately Owned
City of Manteca
Limit
Improvement
Project 1
Project 2 & 3
Project 6
Project 26
Project 27
Project 28
Project 29
Project 30
Project 31
Project 32
ES-9
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 11/2/2023
TR by MA on 11/2/2023
IR Review by MVD on 11/2/2023
Condition Assessment (2017)
Improvements
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-11-02 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

Refer to 320 Airport Way Subdivision
Plans for detailed alignment of CIP 6.

ATTACHMENT 2
ES.7 WASTEWATER QUALITY CONTROL FACILITY (WQCF)

BACKGROUND AND REGULATORY REQUIREMENTS
This section highlights the content of Chapter 7, which documents the history of the WQCF, its overall regulatory requirements and compliance, and details of the effluent discharge Thermal Plan.

ES.7.1 WQCF Background
The Manteca WQCF began operation in 1959. Since then, the plant has been upgraded and expanded multiple times. The last major expansion project (Phase III Expansion) was completed in 2008 which upgraded the WQCF to a Title 22 tertiary treatment facility. Preliminary and primary facilities include a headworks screening structure, influent pump station, aerated grit removal tanks, and primary sedimentation basins. Secondary treatment facilities include conventional activated sludge (CAS) system with aeration basins, return activated sludge (RAS) and waste activated sludge (WAS) pumping stations, secondary clarifiers, and secondary effluent equalization pond (SEEP). Tertiary treatment facilities include filter feed pump station, rapid mix and flocculation basins, cloth media filters, and ultraviolet (UV) disinfection facility. Effluent handling and disposal facilities include secondary effluent storage pond (SESP), irrigation pump station, on-site land application areas for crop irrigation, effluent outfall to the San Joaquin River, and plant recycled water pump station. Solids handling facilities include dissolved air floatation thickeners (DAFTs), centrifuge dewatering building, and anerobic digesters.

The Influent Pump station splits the wastewater flow to parallel treatment systems known as the Northside and Southside plants that include separate aerated grit tanks, primary and secondary treatment facilities.

In 2018, improvements were made to the Northside Plant aeration basins to improve energy efficiency and improve control of the aeration process to obtain additional denitrification capabilities. This included replacement of multistage blowers with high efficiency turbo blowers, replacement of the diffuser system with more reliable high efficiency fine bubble diffusers, and installation of control valves and DO controls to all basin zones. These improvements allowed influent flows to increase without violations of the NPDES permit. In 2020 these same improvements were made to the Southside Plant.

The WQCF Digester Improvements Phase I Project, completed in 2019, included new Digesters No. 3 and No.4 and a new Digester Control Building, rehabilitation of Digesters No. 1 and No. 2, replacement the existing gas flare, new FOG and food waste receiving stations. Also completed in 2019 was the Compressed Biogas Fueling Facilities Phase II Project, which included a new biogas renewable compressed natural gas (BioCNG) facility and fill station. A site plan showing the facilities of the Manteca Wastewater Quality Control Facility (WQCF) is shown in Figure ES-10.

ATTACHMENT 2

HEADWORKS/SCREENS

INFLUENT PUMP STATION

SEPTAGE RECEIVING STATION

FOG RECEIVING

FOOD WASTE RECEIVING

BIOGAS SULFATREAT SYSTEM

ODOR CONTROL BIOFILTER

CHLORINE BUILDING

NORTHSIDE AERATED GRIT TANKS

NORTHSIDE PRIMARY SEDIMENTATION BASINS

NORTHSIDE AERATION BASINS
SECONDARY CLARIFIER NO.1
SECONDARY CLARIFIER NO.2
SECONDARY CLARIFIER NO.3
NORTHSIDE RAS & N.S. WAS PUMP STATION

SOUTHSIDE AERATED GRIT TANKS

SOUTHSIDE PRIMARY SEDIMENTATION BASINS

SOUTHSIDE AERATION BASINS

SOUTHSIDE MCC BUILDING
SECONDARY CLARIFIER NO.4
SECONDARY CLARIFIER NO.5
SEC. CLARIFIERS NO.4 & NO.5 SPLITTER BOX

SOUTHSIDE RAS PUMP STATION

FILTER FEED PUMP STATION
CHEMICAL BUILDING 2

RAPID MIX AND FLOCCULATION TANKS

TERTIARY FILTERS

UV DISINFECTION

EFFLUENT PUMP STATION

EFFLUENT MCC/GENERATOR BUILDING

CHLORINE CONTACT TANK

IRRIGATION PUMP STATION

RECYCLE WATER PUMP STATION

SECONDARY EFFLUENT EQUALIZATION POND

SECONDARY EFFLUENT STORAGE POND

ECKERT POND

DISSOLVED AIR FLOTATION TANKS

COLLECTIONS STORAGE BUILDING
DIGESTER NO.1
DIGESTER NO.2

DIGESTER CONTROL BUILDING
DIGESTER NO.3
DIGESTER NO.4

SLUDGE BLENDING TANK

DEWATERING BUILDING

DEWATERED SLUDGE LOADING AREA

RCNG GAS STORAGE/CONDITIONING
BIOCNG

CNG/TRUCK LOADING
FLARE

NORTH SLUDGE DRYING BEDS

ADMIN BUILDING

LABORATORY

SHOP/MAINTENANCE BUILDING

TRAINING/LOCKER ROOM OPERATION BUILDING

BIOTOWERS

STAFF LOCKER ROOM
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56 V:\1840\active\184031483\drawing\graphics\__________.ai mlm 03-03-2022 City of Manteca

WASTEWATER QUALITY CONTROL FACILITY

OPERATIONS AND MAINTENANCE MANUAL DRAFT
U:\184031535\drawing\graphics\manteca_wqcf__________.ai mlm march-2023 Figure ES-10
WQCF Existing Site Layout
ATTACHMENT 2
ES.7.2 Regulatory Requirements
The City of Manteca WQCF is currently regulated by National Pollutant Discharge Elimination System (NPDES) CA0081558 Order R5-2021-0003 (Order). The Order serves as Waste Discharge Requirements (WDR) pursuant to the California Water Code (Section 13260) and Federal Clean Water Act (Section 402). NPDES orders are renewed on a five-year cycle to reflect changes in policy interpretation, updates to regulation and policy regarding the disposal of wastewater, variations in effluent quality, and public input. The current Order became effective on April 1, 2021, and expires on March 31, 2026.

The Order describes explicit effluent limitations for discharge to the San Joaquin River. Some of the key effluent limitations are summarized in Table ES-8.

Table ES-8. Select Order Effluent Limitations for Discharge to San Joaquin River Parameter Concentration
BOD5
Average Monthly, mg/L 10
Average Weekly, mg/L 15
TSS
Average Monthly, mg/L 10
Average Weekly, mg/L 15
Ammonia Nitrogen (as N) from April 1st to November 30th 1 Monthly Average, mg N/L 2.0
Weekly Average, mg N/L 4.2
Ammonia Nitrogen (as N) from December 1st to March 31st 1 Monthly Average, mg N/L 2.5
Weekly Average, mg N/L 6.2
Nitrate plus Nitrite as N
Average Monthly, mg N/L 10
Average Weekly, mg N/L 15.3
Note:
1 Loading limits for ammonia nitrogen are regulated based on the concentration (mg N/L) x average dry weather flow effluent limit (Mgal/d) x 8.34 conversion factor.

Key:

BOD5 = Biochemical Oxygen Demand, 5-day at 20°C
mg/L = milligrams per liter
TSS = Total Suspended Solids
The State of California has adopted competing regulations that will impact the WQCF capacity and effluent quality, in particular:
• SB 606 and AB 1688, Water Management Planning (which limits indoor potable water use to 50 gpd/capita by 2030)
ATTACHMENT 2
• SB 1383, Short-Lived Climate Pollutants Reduction Act (which limits methane emissions to 40% below 2013 levels and reducing disposal of organic waste by 75% from the 2014 levels by 2025) • Basin Plan Amendments, including salt control programs.

SB 606 and AB 1688, Water Management Planning
SB 606 and AB 1688 limit indoor potable water use to 50 gpd/capita by 2030. For the City of Manteca, this means the residents will have to reduce their current water use by approximately 22% (based on the current estimated usage of 61 gpd/capita). It is noted that when water is conserved, the mass of pollutants discharged by each person is then carried to the treatment plant in less water, resulting in higher pollutant concentrations. This level of water conservation will cause the design organic loading of the plant to be reached before the hydraulic design flow. This further complicates compliance with pollutants that are not removed from the existing process facilities, because they are in such low concentrations or they are not currently permitted (such as salinity, PFAS, pharmaceuticals, pesticides, etc.).

SB 1383, Short-Lived Climate Pollutants Reduction Act
SB 1383 limits methane emissions to 40-percent below 2013 levels and reduces disposal of organic waste by 75-percent from the 2014 levels by 2025. To achieve the goals of this regulation, a key strategy is to divert organic waste from landfills and send the food waste to municipal wastewater treatment facilities for co-digestion in anaerobic digesters, making beneficial use of biogas. However, the diverted organic waste will take up valuable volume in digesters and solids handling facilities that would otherwise be used for wastewater sludge. Further, food waste will increase salinity loading to the plant, as further discussed below.

Salinity
The Regional Water Quality Control Board (Regional Board) amended its Basin Plan to implement a longterm program to control salinity and nitrate build-up in the Central Valley, with input from all stakeholders (agriculture, cities, industries, environmentalists, economists, etc.) and as recommended by the CVSALTS Initiative. The Basin Plan amendments were approved by the EPA and Office of Administrative Law (OAL) on January 15, 2020, which became the effective date for the Basin Plan Amendments and policies identified therein. One of the major aspects of the amendments includes a Salt Control Program, described below.

Salt Control Program. The Salt Control Program established in the Basin Plan will be implemented in three phases, with each phase expected to take 10 to 15 years, according to the Basin Plan. The initial phase required the City to select either the “Conservative Salinity Permitting Approach” (which applies the Water Quality Objectives of 700 μS/cm, along with other requirements) or the “Alternative Salinity Permitting Approach” (which allows Agencies to join regional efforts to study salinity effects on the ecosystem). Since the City currently does not meet the water quality objectives, the WQCF is operating under the Alternative Approach.

ATTACHMENT 2
Future Salinity Compliance. Increased water conservation in the City, including State mandated reclamation and water conservation requirements (SB 606 and AB1688, described above), will inhibit compliance with water quality objectives for salinity. Additionally, if the City decides to receive food waste at the WQCF (to comply with SB1383) the concentrated food slurry may further inhibit compliance with water quality objectives. These external compliance pressures are noted herein to highlight the complexity of competing State interests and help make informed decisions about expansion options.

Notably, extreme water conservation has a direct effect on wastewater influent and will increase salinity concentrations entering the WQCF. The mass of pollutants (salt) discharged by each person remains unchanged regardless of water use, but because the mass is conveyed with less water (during water conservation measures), it results in higher pollutant concentrations arriving at the WQCF.

To ensure long-term compliance with the permit, it appears that the City should plan for some future salinity reduction. In this case (and considering the limits of current salt removal technologies), the City would likely install a reverse osmosis (RO) treatment system for only a portion of the total plant flow to remove just the amount of salt needed to comply with regulations.

To reduce salt at the WQCF, RO would be used most likely because other salinity reduction technologies such as nanofiltration (NF), electrodialysis reversal (EDR), and ion exchange tend to leave the more problematic ions, such as sodium and chloride, in the water. However, in 30 years there may be a completely new salt removal technology based on current world-wide research and development of new salt removal technologies, including those identified through the Department of Energy’s Water Security Grand Challenge. For now, the City should plan on possible future implementation of RO but can remain flexible to adapt to other technologies that may become available before salinity removal is implemented.

As the City moves forward with expanding the capacity of the WQCF, a reasonable question is whether the expansion should be “in kind” with the existing process, or should be with a newer technology, specifically an MBR (membrane bioreactor). In developing an answer, many factors were considered including near-term and long-term costs, best professional judgement by the design and operations team, and the Basin Plan amendments, Chapter 10 incorporates these issues into the detailed evaluation. It must be noted that an MBR would not remove any salinity but can act as a pretreatment step in conjunction with a salinity removal system.

Other Compliance Considerations
Long-term compliance is also dependent on future permit requirements, which may include more stringent or added provisions for salinity (described above), biological interferences, pesticides, and contaminants of emerging concern (CEC). These constituent considerations are discussed below.

Pesticides. The impacts of pesticides, including insecticides, herbicides, and fungicides, on water quality and aquatic habitats will continue to drive implementation of control programs and development of discharge limits. This has resulted in the inclusion of chlorpyrifos and diazinon limits in the WDR, even when there is no reasonable potential for impacts. Discharge limits for pyrethroid pesticides were adopted in the San Joaquin River Basin Plan and became effective in December 2006, but numerical limits are not specified in the WDR. The Basin is also listed as impaired by Group A pesticides, including organochlorine pesticides, but a TMDL has not been developed and numerical limits are not included in ATTACHMENT 2
the permit. Future developments in these types of chemicals will require additional analysis of effluent chemistry and potentially require additional treatment to comply.

Constituents of Emerging Concern (CES). CEC, including pharmaceuticals and endocrine disrupting compounds, such as hormones, at variable concentrations have been detected in treated effluent from conventional wastewater treatment plants. However, numeric requirements for removal of CEC appear to be unlikely for the foreseeable future. If CEC removal becomes an issue with the current surface water discharge, use of advanced oxidation processes, such as ozonation, combined with biological activated carbon filtration can be considered.

ES.7.3 Thermal Plan Compliance
The WQCF currently disposes of final effluent (the portion not delivered to reclamation) via a 36-inch diameter pipe discharging to the San Joaquin River just south of the railroad bridge upstream of the I-5 bridge at the I-5/CA-120 interchange. The WQCF outfall discharge location is shown on Figures ES-11.

ATTACHMENT 2
Manteca WQCF Outfall Discharge Location
Manteca WQCF Discharge into San Joaquin River
Figure ES-11. WQCF Outfall Discharge Location
ATTACHMENT 2
In compliance with the California Environmental Quality Act (CEQA), the City prepared and submitted for public review a Draft Environmental Impact Report (DEIR) that addressed the future Phase IV Upgrade and Expansion Project. Since the City determined that it is impracticable to acquire additional agricultural fields (though they are seeking to expand their Title 22 recycled water program through uses such as baseball fields and parks), the increased discharge will be primarily for effluent discharges to the San Joaquin River. The City performed extensive hydrodynamic and thermal modeling as part of the DEIR to determine the effects of the increased effluent discharge flow to the San Joaquin River and to the Sacramento-San Joaquin Delta downstream of the discharge. This modeling is detailed in the following reports.
• Technical Memorandum (TM) – CORMIX Investigation of Cooling Facilities Operations (DRAFT), Larry Walker Associates, February 2008.
• Thermal Plan Exception Analysis Final Report, Larry Walker Associates, Resource Management Associates, Hanson Environmental, Inc. February 2006.

The models showed that future flows greater than 9.87 Mgal/d discharged to the San Joaquin River could at times violate the Water Quality Control Plan for Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays and Estuaries of California known as the “Thermal Plan”. Based on these models, an exception to the Thermal Plan was requested by Manteca from the RWQCB. This request was denied and the permitted flow expansion greater than 9.87 Mgal/d is only allowed under the existing NPDES permit if compliance with the Thermal Plan limits is achieved. Construction of cooling towers was therefore included in the Phase IV Upgrade and Expansion Project description to the Regional Water Board. The cooling facilities would be designed to reduce temperature of the treated effluent such that the effluent discharge and associated size of the thermal plume will comply with Thermal Plan provisions as necessary to protect sensitive aquatic life.

Measurement of final effluent temperature and the river temperature upstream and downstream of the discharge location is also a requirement under the current NPDES permit. A comparison of recent effluent discharge and river temperatures from 2016 through 2021 has shown an increase in the temperature difference between the effluent and the river of 2°F to 5°F over what was used for all previous modeling.

Therefore, a new river modelling study is recommended before proceeding with the design and construction of cooling towers to validate compliance with the Thermal Plan.

ATTACHMENT 2
ES.8 WQCF WASTEWATER FLOWS AND LOADS
This section highlights the content of Chapter 8, which includes the following assessments:
• Historical Flows and Loads and Changed Conditions
• Plant Recycled Flows and True Influent Flows
• Summary of Existing and Future Wastewater Characteristics • Equivalent Population Served
ES.8.1 Historical Flows and Loads and Changed Conditions Historical influent flows from January 2016 through February 2021 are shown in Figure ES-12. The 365- day average flow values are centered averages based on available data extending one-half the averaging period before and after the date indicated (i.e., the 365-day average flow on the date indicated includes data beginning 182 days prior to the indicated date and data ending 182 days after the indicated date).

The 365-day average flow (annual average flow or AAF) has exhibited a mostly steady increasing trend over the period of record considered, however, the rate of increase accelerated in the final year. The AAF at the end of the study period was 7.13 Mgal/d. The ratio of the average dry weather flow to the annual average flow for each year was calculated. The average of this ratio from 2016 through 2021 is 0.992, which indicates that the ADWF is essentially equal to the AAF. For the intended purpose of this this master plan, the flow will be presented in terms of ADWF. The annual average BOD load was steadily increasing over the same period. The most recent annual average BOD load determined was 22,121 lb/d as shown in Figure ES-13.

Figure ES-12. Historical Influent Flow

5.0 5.5

6.0 6.5

7.0 7.5

8.0 8.5

9.0 9.5
Jan-16Jul-16Jan-17Jul-17Jan-18Jul-18Jan-19Jul-19Jan-20Jul-20Jan-21 Influent Flow, Mgal/d
Date
Daily 30d Avg 365d Avg
ATTACHMENT 2
Figure ES-13. Historical Influent BOD Load
The Phase III Expansion Basis of Design Report prepared by Nolte and Associates in July 2001 rated the existing WQCF at an average flow capacity of 9.87 Mgal/d. Of this capacity, 14.7% (1.45 Mgal/d) is contracted to the City of Lathrop. There have been several changed conditions at the WQCF since 2001 that affect the capacity of the WQCF, including the following:
• Drought conditions and water conservation in recent years have resulted in increased wastewater strength as the pollutants contributed by a given population are carried in less water to the WQCF.
• An effluent limit on Nitrate + Nitrite Nitrogen (10 mg/L monthly average) was added to the National Pollution Discharge Elimination System (NPDES) Permit for the WQCF. The Phase III design did not consider or provide adequate facilities to meet this requirement at the original 9.87 Mgal/d design flow.
• The biotowers in the Northside Plant, which provided a portion of the treatment capacity established in the Phase III Basis of Design Report, were removed from service in 2007 because they remove the carbon source needed for denitrification. Therefore, they were incompatible with meeting the new nitrogen permit limit.

Because of these changed conditions the WQCF does not have the treatment capacity to support ongoing growth within the City. The projected near-term future flow of 9.23 Mgal/d which includes the true influent flows from Manteca and Lathrop, as well as in-plant recycle streams from the WQCF corresponds to the likely achievable capacity with the Interim Improvements recommended in the WQCF 2021 Capacity Assessment which are described in Chapter 9.
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20,000
25,000
30,000
35,000
40,000
45,000
50,000
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ATTACHMENT 2
ES.8.2 Plant Recycled Flows and True Influent Flows
The WQCF 2021 Capacity Assessment analyzed in-plant recycle flow from March 2020 to February 2021 to quantify the total recycle flows to determine the true plant influent (without recycle streams) characteristics. The analysis indicates that the total in-plant recycle flow adds up to 0.772 Mgal/d out of the 7.13 Mgal/d measured at the headworks with a true influent flow of 6.358 Mgal/d (7.13 - 0.772).

Therefore, the recycle streams account for an approximate 12% increase to the true influent flow (0.772 /

6.358). The true influent flow also includes the flow received from Lathrop (measured directly by separate flow meter) which equaled 1.07 Mgal/d during this period. Therefore, the true average annual influent flow for Manteca was 5.29 Mgal/d.

As indicated in Table ES-9, Lathrop’s current flow contribution represents 16.8% of the total WQCF flow (1.07 / 6.358). If it is assumed that Lathrop’s flow contribution in the future condition will be at the contract amount of 14.7%, then Lathrop’s metered flow (not including recycle allowance) would increase from the current value of 1.07 Mgal/d to 1.21 Mgal/d, an increase of 0.14 Mgal/d. During the same time, Manteca’s base flow (without recycle allowance) would increase by 1.73 Mgal/d. Therefore, future flow increases would be allocated 7.5% to Lathrop and 92.5% to Manteca. The lower growth allowance for Lathrop is because the current Lathrop flow as a fraction of the total flow is substantially greater than 14.7% and is assumed to decrease to 14.7%.

Table ES-9. Breakdown of Existing and Projected Interim Flows Condition and Flow Category Annual Average Flow, Mgal/d Lathrop Manteca Total
Existing
Flow Excluding In‐Plant Recycle Streams 1 1.07 5.29 6.36 Flow Including In‐Plant Recycle Streams 2 1.20 5.93 7.13 Fraction of Total Flow 0.168 0.832 1.000
After Interim Improvements3
Flow Excluding In‐Plant Recycle Streams 1.21 7.02 8.23
Flow Including In‐Plant Recycle Streams 2 1.36 7.87 9.23 Fraction of Total Flow 0.147 0.853 1.000
Difference (Future ‐ Existing)
Flow Excluding In‐Plant Recycle Streams 0.14 1.73 1.87
Flow Including In‐Plant Recycle Streams 2 0.16 1.94 2.10 Fraction of Total Flow 0.075 0.925 1.000
Notes:
1 Existing Lathrop flow based on annual average from Dec 2019 through Nov 2020. Beginning Dec 2020 recorded Lathrop flows decreased and must be verified. 2 Flow including in‐plant recycle streams calculated as 1.121 x base flow. 3 Future based on total flow with recycle streams = 9.23 Mgal/d. Assuming Lathrop will represent 14.7% of total flow in future.

ATTACHMENT 2
ES.8.3 Summary of Existing and Future Wastewater
Characteristics
Wastewater flows and characteristics from January 2016 through February 2021 (over five years of data) were analyzed. The current wastewater flows and loads presented in this section are summarized and used for projecting future flows and loads as shown in Table ES-10. It is presumed that future expansion will provide build-out capacity flows for Manteca plus the Lathrop flow contribution totaling 17.5 Mgal/d (ADWF without recycle). The future projections assume that all average wastewater influent constituent concentrations and flow and load peaking factors remain unchanged from existing conditions. Therefore, future increases in all sewage flows and loads are expected to be proportional to increases in the annual average flow, which should be roughly proportional population growth.

ATTACHMENT 2
Table ES-10. Existing and Future Flows and Loads
Parameter 1 Existing 6.37 Mgal/d 2, 3 Interim 8.23 Mgal/d 2, 4 Future 17.5 Mgal/d 2, 4 ADWF (with Recycle) 7.13 9.23 19.6
ADWF (without Recycle) 6.37 8.23 17.5
Flow Ratios
ADMMF/ADWF 1.04 1.04 1.04
PDF/ADWF 1.25 1.25 1.25
PHF/ADWF 2.10 2.10 2.10
Load Ratios
ADMML/AAL 1.20 1.20 1.20
PDL/AAL 2.00 2.00 2.00
Flow, Mgal/d
ADWF 7.13 9.23 19.6
ADMMF 7.42 9.60 20.38
PDF 8.91 11.54 24.50
PHF 14.97 19.38 41.16
Annual Average Load, lb/d
BOD 22,121 28,636 60,809
TSS 16,591 21,477 45,608
TKN 3,568 4,619 9,808
Average Day Maximum Monthly Load, lb/d
BOD 26,545 34,363 72,971
TSS 19,909 25,772 54,729
TKN 4,281 5,542 11,770
Average Constituent Concentrations, mg/L
BOD 372 372 372
TSS 279 279 279
TKN 60 60 60
Constituent Concentrations with ADMMF and ADMML, mg/L
BOD 429 429 429
TSS 322 322 322
TKN 69 69 69
Constituent Concentrations with AAF and ADMML, mg/L
BOD 446 446 446
TSS 335 335 335
TKN 72 72 72
Notes:
1 ADWF = Average Dry Weather Flow, ADMMF = Average Day Maximum Monthly Flow, PDF = Peak Day Flow, PHF = Peak Hour Flow, AAL = Annual Average Load, ADMML = Average Day Maximum Monthly Load, PDL = Peak Day Load 2
All flows and loads include in‐plant recycle streams. Future projections assume recycle flow and load fractions remain unchanged. 3
Based on ADWF = 7.13 Mgal/d as of August 30, 2020. 4
The Future condition is based on likely achievable plant capacity with improvements as discussed in Chapter 10. Flow and load peaking factors assumed same as existing.

Key: mg/L = milligrams per liter
Mgal/d = million gallons per day
lb/d = pounds per day
ATTACHMENT 2
ES.8.4 Equivalent Population Served
Flows from a given population are subject to variation with water conservation (and infiltration and inflows into the sewage collection system, which is not a significant issue for Manteca). However, pollutant loads are generally proportional to population and do not vary with water conservation. Since design loads are the key criteria for sizing wastewater treatment facilities, it is useful to present plant capacities in terms of loading or equivalent population.

The average flow per capita was calculated using five years of plant data (January 2016 to February 2021) to calculate an average influent daily flow using the average BOD load (without in-plant recycle flows and Lathrop’s contribution) for each year divided by the State of California Department of Finance population estimates for the City of Manteca. Averaging the five years of data calculates to a per capita wastewater flow of 61 gallons/capita/day and a per capita BOD load of 0.203 lb BOD/capita/day. After the recommended Interim Improvements are completed increasing the true influent flow capacity to 8.23 Mgal/d, the equivalent population the WQCF can serve is 111,800.

Over the longer time horizon of 20 plus years, the City is projecting an annual population growth rate of

2.8%. Using a population growth rate of 2.8% for Manteca and subtracting 14.7% for Lathrop, the equivalent population for Manteca at the build-out flow of 17.5 Mgal/d ADWF would be approximately 236,000 people by the year 2057.

ES.9 WQCF ASSESSMENT OF EXISTING FACILITIES AND

RECOMMENDED INTERIM IMPROVEMENTS
This section highlights the content of Chapter 9, which provides an overview of the City’s existing Wastewater Quality Control Facility (WQCF), The information presented in this chapter is based on the review of previous studies, design reports, record drawings, operating records, and discussions with City staff. and presents an assessment of the performance of the existing treatment processes and recommendation for Interim Improvements to keep the plant in compliance with waste discharge requirements until the next major expansion project. Chapter 9 evaluates the following components of the WQCF:
• Headworks and Influent Pump Station
• Aerated Grit Tanks
• Primary Sedimentation Basins
• Secondary Treatment Facilities
• Secondary Effluent Equalization Pond (SEEP)
• Filter Feed Pump Station
• Rapid Mix and Flocculation Tanks
• Tertiary Filters
• UV Disinfection System
• Effluent Handling and Disposal Facilities
• Biosolids Handling and Drying Facilities
• Biogas Utilization Facilities
ATTACHMENT 2
• Electrical Supply and Distribution
• Instrumentation and Electrical Controls
• Auxiliary Systems
• Recommended Interim Improvements
ES.9.1 Headworks and Influent Pump Station
Currently, the IPS is designed with three duty pumps and one standby pump (the standby pump can convey screened wastewater to either the Northside Plant or the Southside Plant). The operators have noted that during recent severe storm events, all four pumps were needed to convey the high influent flows. There are currently four empty pump bays to facilitate expanding the capacity of the IPS.

Therefore, to ensure the IPS has firm capacity, it is recommended to install a fifth pump in one of the empty pump bays to serve as the second duty pump dedicated to the Southside Plant.

In 2022, two new headworks screens were installed to replace the older screens. The third mechanical screen is at the end of its useful life and will need replacing. The Headworks wet well, according to CalOSHA standards, is a hazardous environment in a confined space with improper ventilation, which makes it difficult for plant staff to do inspection and maintenance in this area. It is recommended that the ventilation system be upgraded where foul air from the junction structure, covered channels and room air will be exhausted to the existing biofilter for odor treatment.

On February 6, 2015, a study of the biofilter was prepared by HERWIT and Stantec. According to plant staff the biofilter operated effectively for approximately 5 years before exhibiting operational problems, primarily attributed to excessive head loss across the filter associated with media fouling. The biofilter has not been operational since that time. Air is being exhausted from the Headworks, IPS and Dewatering Building with the odor control fan and discharged without odor treatment. It is recommended that the odor control fan be replaced and the lava rock media in the biofilter be replaced by inorganic media provided by Biorem©, ECS or equivalent. The biofilter media cells (2 total) should be provided with a cover system.

The cover will help prevent the migration of dust, soil, and other particulates to the biofilter, and will also help to provide better climatic controls of the media bed.

ES.9.2 Aerated Grit Tanks and Primary Sedimentation Basins The existing covers for aerated grit tanks and primary sedimentation basins are Enduro XL6 fiberglass reinforced plastic (FRP) covers, which the operators have noted are too heavy to lift to perform routine maintenance inside the tanks and basins. It is recommended that lighter covers be installed. One option would be retractable arch-supported covers made of high-performance UV-protected membranes. The covers are supported on a low-profile aluminum arch frame so they can be quickly detached and reattached to provide easy access for operators.

ATTACHMENT 2
ES.9.3 Secondary Treatment Facilities
The existing Northside and Southside Plants are challenged to meet the effluent nitrate + nitrite (10 mg/L as nitrogen monthly average). As discussed in the WQCF 2021 Capacity Assessment, improvements are needed to the secondary treatment facilities to improve nitrogen removal performance and are a prerequisite to handle increased flows and loads. Improvements to the secondary treatment aeration basins are currently under design by Pacific Advanced Civil Engineering, Inc. (PACE) and improvements to the RAS/WAS pumping systems are currently under design by HERWIT Engineering.

The proposed Northside Plant improvements include increasing the volume of the aeration basins 22 percent by raising the water depth and reconfiguring the biological treatment zones so the first and fourth zones are anoxic. Cyclic aeration has been difficult to operate and therefore will be removed in the second zone so that there are three zones out of five with constant aerobic biological treatment. Exterior improvements will include installation of a new Internal Recycle Pump Station (IRPS) to replace the undersized existing internal mixed liquor recycle pumps, installation of a new Primary Effluent Pump Station (PEPS) to lift the hydraulic profile, and modifications to the existing Influent Channel to accommodate a two-train operation to replace the existing five parallel trains.

For the Southside Plant improvements, the aeration basins will be reconfigured so that the first and fourth biological treatment zones are anoxic. Cyclic aeration will be removed in the second zone so that there are three zones out of five with constant aerobic biological treatment. Exterior improvements will include installation of a new Internal Recycle Pump Station (IRPS) to replace the undersized mixed liquor recycle pumps.

Glycerin feed systems have been added to both the Northside and Southside Plants ahead of the first zone anoxic basins to improve denitrification performance.

To maximize the capacity of the existing secondary clarifiers, it is essential that return activated sludge (RAS) pumping capacity be adequate. Generally, the pumping capacity divided by the clarifier area should give an underflow rate greater than 500 gpd/ft2. The maximum underflow rates for the Northside and Southside clarifiers are 571 gpd/ft2 and 258 gpd/ft2, respectively, indicating a severe deficiency in the Southside Plant. The proposed improvements to the Secondary Clarifiers include the following:
• Replace the RAS pumps in the Southside Plant to obtain a reliable capacity of at least 4.8 Mgal/d per secondary clarifier (existing capacity is 1,700 gpm = 2.4 Mgal/d). • Replace the waste activated sludge (WAS) pumps in both the Northside and Southside Plants to provide reliable wasting as required under future design conditions. • Also noted by plant operations staff, the secondary clarifier ducking skimmers work poorly and require replacement with a more traditional skimmer rack arm design. • There are hydraulic issues at the Southside Plant clarifiers with large periodic flow surges. The effluent launder at the Southside Plant aeration basins traps air and then suddenly releases it, modifications are required to avoid pipe damage.

ATTACHMENT 2
Finally, as noted in the WQCF 2021 Capacity Assessment, sidestream treatment would greatly reduce the recycle TKN load from the solids handling system and would provide major benefits to assist in compliance with the effluent nitrate + nitrite limit, whether the plant accepts food waste or not into the anaerobic digesters. Food waste should not be accepted without providing sidestream treatment.

ES.9.4 Secondary Effluent Equalization Pond (SEEP)
The SEEP liner is in poor condition. When there is a puncture or tear in the liner it is difficult to repair because of the deteriorated condition of the liner material. It is recommended that the liner be replaced in-kind with a new liner.

ES.9.5 UV Disinfection System
In the last two years (January 2021-March 2023), there has been one total coliform violation in June 2022 (prior to 2021, there was one exceedance in 2020, one in 2019, and several in 2018). From January 2018 through March 2023, the daily average UV dose has averaged 206 mJ/cm2, which is significantly greater than the permit required minimum UV dose of 100 mJ/cm2. The width of the existing channels (10-feet

11.5-inches) makes it difficult to get access to the lamps and channels for maintenance and cleaning.

Three UV system alternatives were analyzed for upgrading the UV disinfection system: 1) A closed vessel system; 2) In-kind open channel system with four smaller width channels instead two wide channels; and 3) New higher intensity lamp open channel system with four deeper channels. The recommended alternative based on lowest capital cost and energy efficiency is the Wedeco Duron 8 (800W), or equal manufacturer, to achieve a UV dose of 100 mJ/cm2 based on a peak design flow of 31.08 Mgal/d at a minimum design UVT of 61.3-percent.

ES.9.6 Biosolids Handling Facilities
The existing biosolids handling facilities require the following improvements:
• Digesters No. 1 and 2 need an overflow box that discharges to the solids holding tank similar to Digesters No. 3 and 4.
• New grating and handrailing at the digester gas relief valves is needed for all four digesters. • The existing waste heat radiator is undersized and needs to be replaced with a larger radiator. • The existing FOG receiving station basket screen does not work very well. A replacement screening system is recommended for the FOG Receiving Station.

The impact of the centrate return on the nitrogen treatment capabilities of the main process is very significant. The main treatment process is currently overloaded on nitrogen treatment capacity. As a result of this, only one centrifuge can be run at a time with a flow limit of 115 gpm. This is well below the centrifuge capacity of 185 gpm. Side stream treatment of the centrate is needed to reduce the impacts of the dewatering centrate return on the main plant process and allow full use of the dewatering facility, Side stream treatment of the centrate is recommended and included in the Interim Improvement Projects.

ATTACHMENT 2
Even with side stream treatment, the centrifuge facility will be required to run both centrifuges with the increased plant loadings and will not have a redundant centrifuge. A third centrifuge, new sludge feed pump, and new polymer blending unit are recommended and included in the Interim Improvement Projects. The new centrifuge is recommended to have a minimum capacity of 260 gpm and 3,000 dry lb/hr.

Currently, the plant is required to run both DAFT units continuously to keep up with WAS loading. This will become more critical when the WAS system is expanded. A redundant DAFT is required to allow maintenance on the DAFT system. A new DAFT is recommended and included in the Interim Improvement projects.

ES.9.7 Instrumentation and Electrical Controls
A SCADA Master Plan for the WQCF was completed in 2020 by Carollo Engineers. The following is a list of recommended improvements:
• Provide new core SCADA server and network system migrating to Ignition SCADA HMI software. • Provide remote site PLC upgrades for sewer and stormwater lift stations. • Replace existing WQCF legacy PLC systems and associated network hardware as well as the operator interfaced terminals (OITs) for modernization and standardization of equipment and added system reliability.
• Upgrade switchgear and power systems PLCs to latest supported model.

ES.9.8 Biogas Utilization Facilities
Digester heat demand is less than anticipated and the waste gas boiler radiator is too small to handle the excess heat and a larger replacement radiator is recommended for system stability. Plant staff at times are forced to dump heat into the out of service digester which is not a desired long-term solution. It is recommended that the existing waste heat radiator be replaced with a larger radiator.

The H2S removal system works well. However, the two 1,500-gallon chemical tanks (ferric chloride) are too small for a full bulk chemical delivery, preventing some vendors from servicing the WQCF. The smaller tanks also increase the cost of the chemical as the freight charge on a per gallon basis is higher.

It is recommended to replace the two 1,500-gallon chemical tanks with two 2,700-gallon chemical tanks (ferric chloride) so a full bulk chemical delivery can be received, thereby reducing the per gallon cost of the chemical and making it possible for other vendors to service the WQCF.

ATTACHMENT 2
ES.9.9 Cost Summary of Recommended Interim Improvements The Interim Improvements project costs were developed from previous study cost estimates adjusted to the March 2023 Engineering News-Record Construction Cost Index (ENRCCI) 20-Cities Average of 13,176. Where previous cost estimates were not available, construction costs were developed using costs for similar construction at other wastewater treatment plants and equipment manufacturer quotes.

Project costs for each item in Table ES-11 were estimated as separate projects with 35 percent added to the construction estimate for engineering, construction management and administration.

ATTACHMENT 2
Table ES-11. Recommended Interim Improvements Project Costs1 WQCF
ID Description
Estimated
Project
Cost
Recommended Interim Improvements Needed Immediately
1 North and South Plant WAS Pump Replacement Project $2,827,000 2 South Plant RAS Pump Replacement Project $1,652,000
3 North and South Plant Aeration Basins Improvements $11,696,000 Subtotal $16,175,000
Interim Improvements for Additional Surety and Ability to Accept Food Waste 2 4 Add sidestream treatment of sludge dewatering return flows to reduce nitrogen loads to the secondary treatment system, thereby improving nitrogen compliance and sludge settleability and providing flexibility to accept food waste.
$20,205,000
5 Add Centrifuge No. 3 to process additional solids at the dewatering building. $5,130,000 6 Add DAFT No. 3 to provide redundant DAFT for thickening of sludge prior to digestion 2 $3,930,000 Subtotal $29,265,000
Instrumentation and Electrical Control Improvements 3
7 Core Supervisory Control and Data Acquisition (SCADA) System $1,127,000 8 Remote Site Process Logic Controller (PLC) Upgrades $1,727,000 9 PLC and Operator Interfaced Terminal (OIT) Replacement $1,374,000 10 Switchgear PLC Upgrades $127,000
Subtotal $4,355,000
Other Improvements
11 Add Influent Pump No. 5 $1,048,000
12 Lightweight Covers for aerated grit tanks, primary sed. basins, & chlorine contact tank $5,792,000 13 Repair Biofilter and modify ventilation system at Headworks and IPS 4 $2,080,000 14 UV Disinfection System Upgrade $15,583,000
15 Piping Modification to Separate Plant Water System from Off-Site Reclaimed Water $636,000 16 Replace Secondary Effluent Equalization Pond Liner $2,101,000 17 Headworks Screen No. 3 5 $900,000
18 FOG Receiving Station Screening System $200,000
19 Bulk Ferric Chloride Solution Tanks $351,000
20 Construct new overflow boxes and piping for Digesters No. 1 and 2 $706,000 21 Provide platform and handrail for gas pressure relief valves at all digesters $205,000 22 Install new waste heat radiator $198,000
Subtotal $29,800,000
Grand Total $79,595,000
Notes:
1 Total project cost includes 35% of the total construction cost for engineering, construction management and administration. 2 Costs escalated from WQCF 2021 Capacity Assessment. 3
Costs escalated from the report, City of Manteca WQCF SCADA Master Plan – Technology Drive Solutions for Safe and Reliable Water Quality (Carollo Engineers, Inc., April 2020). 4 Cost escalated from the technical memo, Manteca WQCF Biofilter Evaluation (HERWIT and Stantec, February 2015). 5 Cost obtained from the recent project, WQCF Bar Screen Project, which was started up in October 2022.

Key:

WAS = waste activated sludge
RAS = return activated sludge
IMLR = internal mixed liquor recycle
DAFT = Dissolved Air Flotation Thickener
ATTACHMENT 2
ES.10 WQCF PHASE IV EXPANSION PROJECT
Based on a population growth rate of 2.8% and assuming influent loadings to the WQCF increase proportional to population growth, the proposed Interim Improvements will provide treatment capacity until January 2030. The Phase IV Expansion Project would then increase the true ADWF capacity (without inplant recycle) from 8.23 Mgal/d to 17.5 Mgal/d and provide treatment capacity until the year 2057 as shown on Figure ES-14.

Figure ES-14. Estimated Population Growth and Proposed WQCF Phase IV Expansion Expansion from 8.23 Mgal/d to 17.5 Mgal/d (i.e., building 28 years of treatment capacity) in one stage is not recommended because discharge permit requirements are subject to change every five years and future wastewater treatment technologies could make the current treatment technologies obsolete a decade from now. It is recommended that Phase IV Expansion Project is constructed in two stages with each stage having an incremental treatment capacity of 4.65 Mgal/d ADWF (approximately 9.3 Mgal/d total of treatment capacity will be added when the two stages are completed).

The remainder of this chapter includes the following sections:
• Treatment Process Selection
• Recommended Phase IV Expansion Project
• Phase IV Expansion Costs
ATTACHMENT 2
ES.10.1 Evaluation of Shortlisted Alternatives
The following treatment process alternatives for the Phase IV Expansion Project are identified and described in Chapter 10:
• Alternative 1: Conventional Activated Sludge (CAS) Process. • Alternative 2: Membrane Bioreactor (MBR) Process.
• Alternative 3: Sequencing Batch Reactor (SBR) Process. • Alternative 4: Integrated Fixed-Film Activated Sludge (IFAS) System. • Alternative 5: Granular Activated Sludge (GAS) Process.

As described in Chapter 10, the top two alternatives selected for further evaluation were Alternative 1 - CAS Process and Alternative 2 – MBR Process.

Expansion with Conventional Activated Sludge (CAS)
The conventional activated sludge (CAS) system for biological nitrogen removal uses the Modified Lutzak Ettinger (MLE) process, similar to the existing Southside Plant. Key components of the MLE process include reactor basins, secondary clarifiers, and a RAS pump station. The reactor basins include preanoxic zone followed by aerobic zone. At the end of the aerobic zone, there is an internal mixed liquor recycle pumping system that recycle mixed liquor back to the beginning of the pre-anoxic zone. Mixed liquor flows to the secondary clarifiers where sludge settles to the bottom and returned to the anoxic zone, whereas clarified effluent flows over the clarifier weirs.

The CAS Process alternative would expand the WQCF south of the Southside Plant for the first stage expansion with similar facilities except that the aeration basins would have larger anoxic zones for robust denitrification. The proposed facilities would include five aeration basins, two secondary clarifiers, and RAS/WAS pump station. Because there is not enough land for further expansion south, the second stage expansion would be east of the existing Headworks and include similar facilities to the first stage expansion including five aeration basins, two secondary clarifiers, and RAS/WAS pump station.

Additional tertiary filters would also be required for the second stage expansion.

Expansion with Membrane Bioreactors (MBRs)
Like conventional activated sludge, the MBR process utilizes suspended growth biological treatment.

However, in the MBR, membrane filtration (instead of clarification) is used to achieve solids-liquid separation so that the solids can be returned to the reactor basin. This method of solids-liquid separation does not depend on solids settleability and is, therefore, much more reliable than clarification.

Additionally, the MBR eliminates the need for downstream tertiary filtration and provides a superior quality effluent as compared to conventional activated sludge followed by tertiary filtration. The superior quality effluent from the MBR is easier to disinfect and requires lower ultraviolet dosing as compared to a conventional treatment system. Additionally, membrane filtration would serve as a necessary ATTACHMENT 2
pretreatment step to possible future reverse osmosis for compliance with effluent salinity requirements (conventional treatment with tertiary filtration is not adequate).

Allowable mixed liquor suspended solids concentrations in an MBR are determined by membrane filtration characteristics, not by settling characteristics, and are much higher than those in conventional activated sludge. Typically, the biological reactors for an MBR are designed based on a MLSS concentration of 8,000 mg/L, compared to 3,000-4,000 mg/L in a conventional activated sludge system.

The higher MLSS provides the benefit of greater treatment capacity per unit volume of reactor basin reducing the area footprint required compared to conventional activated sludge. All MBR systems must be preceded by fine screening to protect the membranes from materials in the wastewater such as hair, stringy materials, paper, and small plastic objects that can pass through typical headworks screens and primary clarifiers.

Depending on the selected membrane supplier, maximum allowable screen openings are between 1 and 3 mm. For this analysis, a 2 mm screen is assumed, which is recommended by several leading MBR manufacturers and is the most common screen size based on Stantec experience. The 2 mm screen would be used for screening primary effluent ahead of the MBR.

Primary effluent would flow by gravity from the existing primary clarifiers effluent channel through the proposed new fine screens and to the MBR system. The MBR process flow would be controlled by a modulating gate or valve ahead of the fine screens. All remaining primary effluent flow not going to the MBR treatment system would go to the existing conventional treatment trains.

For this project, the MBR Screenings Facility would be equipped with two (2) in-channel 2-mm drum screens - one duty and one standby. Provisions for the addition of a third screen would be provided for future expansion.

Alternative Analysis
The capital cost and the total present worth cost of the MBR alternative is slightly less than that for the CAS alternative as detailed in Chapter 10. In addition to costs, other factors are also important in the evaluation of the alternatives. The two alternatives are rated with respect to several key economic and non-economic criteria, each of which has been assigned an importance weighting factor. The criteria and the weighting factors were developed with the input and review of Manteca staff in an effort to assure that they appropriately reflect the interests and concerns of the City. The criteria, weighting factors, and ratings are shown in Table ES-12 and discussed briefly below.

Costs: Three different cost criteria are included in Table ES-12. The Stage 1 capital cost is considered most important and is assigned a weighting factor of 20%, while the future expansion cost, which might occur 17 years after Stage 1 is less important with a weighting factor of 10%. The comparative annual cost was assigned a weighting factor of 5% in recognition of the fact that these costs are much less important than the capital costs in the overall present worth cost calculation.

ATTACHMENT 2
Adaptability of Future Permit Requirements: If more stringent salinity limits are enforced in the future, reverse osmosis (RO) will be required and the MBR would provide the pretreatment step necessary for RO. Therefore, the MBR is considered to be more adaptable to future permit requirements. This criterion was assigned a weighting factor of 20% of the total ranking score.

Plant Footprint: The MBR alternative would have the smallest footprint. This was assigned a weighting factor of 10%.

Robustness and Reliability: Robustness and reliability represent the degree to which the process is resilient and can perform consistently well, even in problematic conditions, such as influent flow or load spikes, extreme weather, or other challenging biological process conditions. Because the membranes provide an absolute barrier to the escape of particulate matter from the biological treatment system, very consistent performance can be assured. With a biological treatment system that relies on sludge settling in a clarifier, such as conventional activated sludge, there can be much more variability in effluent quality, which would lead to a higher probability (although still low if properly designed and operated) of potential permit violations. This factor was assigned a weighting factor of 20%.

Ease of Operation: This criterion was given a weighting factor of 15%. There are many considerations that go into ease of operation. The MBR has the benefit of being highly automated and requiring minimal routine operator activity. Sludge settleability monitoring, clarifier sludge blanket monitoring, and adjustments to RAS rates to control the sludge blanket are not required in the MBR. However, an MBR system added in parallel with conventional treatment trains results in operation of two types of processes simultaneously, which is a complication. Considering all factors, the MBR is the highest rated alternative.

Table ES-12. Alternatives Rating and Ranking
Criterion Weighting
Factor %
Alternatives Ratings 1
Alternative 1
CAS
Alternative 2
MBR
Phase 1 Capital Cost 20 10 9
Phase 2 Capital Cost 10 9 10
Annual Cost 5 10 6
Adaptability to Future Permit Requirements 20 8 10
Footprint 10 8 10
Robustness and Reliability 20 8 10
Ease of Operation 15 10 7
Overall Weighted Score 2 100 8.90 9.15
Rank 3 2 1
Notes:
1 The highest rated alternative is assigned 10. Other alternatives are scored lower, according to the relative concerns. 2 Summation of individual ratings multiplied by the corresponding weighting factors. 3 The alternative with the highest score is ranked “1.” Other alternatives are ranked according to their score.

ATTACHMENT 2
Recommended Treatment Process Alternative
Based on the rankings shown in Table ES-12, the recommended alternative for WQCF Phase IV Expansion based on the detailed evaluation is Alternative 2 – MBR. While the MBR has a higher operating cost than conventional activated sludge, it has slightly lower capital costs, a smaller footprint and is more adaptable to future regulations.

ES.10.2 Recommended Phase IV Expansion Project
The following is brief description of the project recommendations by process area. A more detailed description including design criteria and figures to illustrate these recommendations is provide in Chapter

10. A site plan of the Recommended Phase IV Project is shown on Figure ES-15.

ATTACHMENT 2

HEADWORKS, IPS, BIOFILTER

IMPROVEMENTS, INT

REPLACE SECONDARY EFFLUENT EQUALIZATION POND LINER, INT

AERATION
BASINS, S1

UV, INT
DIGESTER, S2

DIGESTER CONTROL
BUILDING, S1
DIGESTER, S1

NEW WAS

PUMPS, INT

NEW CENTRIFUGE, INT
NEW CENTRIFUGE, S1
NEW CENTRIFUGE, S2

NEW SIDESTREAM

TREATMENT, INT

NEW DAFT, INT
NEW DAFT, S1

NEW RAS PUMPS, INT

AERATED GRIT & PRIMARY

SEDIMENTATION BASINS

COVERS REPLACEMENT, INT

AERATED GRIT & PRIMARY

SEDIMENTATION BASINS

COVERS REPLACEMENT, INT
0 80 160 240 320 400
FEET

NORTH AND SOUTH

AERATION BASIN

IMPROVEMENTS, INT
BIO TOWERS DEMO, S1
ROAD DEMO, S1
MBR, S1
MBR, S2
PSB, S1
PSB, S2

AERATED GRIT
TANKS, S1

BIOSOLIDS DRYING
FACILITY, S1
SPLITTER STRUCTURE, S1
FINE SCREENS, S2
FINE SCREENS, S1

BLOWER AND

EQUIPMENT
BUILDING, S1

BLOWER AND

EQUIPMENT
BUILDING, S2

AERATED GRIT
TANKS, S2
COOLING TOWERS 1-4, S1

COOLING BASIN EFFLUENT
PUMP STATION, S1

COOLING

EFFLUENT
BASIN, S1

COOLING
TOWER 5, S2

PRIMARY

EFFLUENT PUMP

STATION, INT

COOLING BASIN
EFFLUENT PUMP 4, S2
EFFLUENT PUMP, S1
EFFLUENT PUMP, S2
CHECK VALVE, S1
INFLUENT PUMP, S2
INFLUENT PUMP, S1

INFLUENT PUMP, INT
MCC, S1

MUNICIPAL

UTILITIES
BUILDING, S1
LEGEND
Interim - 8.23 MGD
Stage 1 - 12.87 MGD
Stage 2 - 17.5 MGD
INT
S2
S1

NEW GATES

NEW ACCESS ROAD AT

INTERSECTION OF

W YOSEMITE &
SWANSON RD, S1
60” NORTH INFLUENT FLOW
METERING MANHOLE, S1

PARKING
AREA, S1

BIOSOLIDS DRYING
FACILITY, S2
60” SOUTH INFLUENT FLOW
METERING MANHOLE, S1
Figure ES-15
Site Plan of Recommended Phase IV Expansion Project

FOG RECEIVING STATION

SCREENING SYSTEM, INT

BULK FERRIC CHLORIDE

SOLUTION TANKS, INT
HEADWORKS SCREEN NO.3 , INT

DIGESTERS PRESSURE RELIEF VALVES

PLATFORM & HANDRAILING, INSTALL

NEW WASTE HEAT RADIATOR,
DIGESTERS NO.1 AND NO.2

OVERFLOW BOXES, INT
U:\184031535\drawing\graphics\manteca_wqcf__________.ai mlm march-2023 ATTACHMENT 2
Influent Flow Meters
It is recommended to install new flow meters upstream of the return of the in-plant recycle streams to measure the true influent flows (one on both the north trunk and south trunk of the sanitary sewers entering the WQCF).

Headworks and Influent Pump Station
In addition to the pump recommended to be installed during the Interim Improvement Projects, the Phase IV Expansion project will require one new IPS pump for Stage 1 and an additional IPS pump for Stage 2.

At the Stage 2 peak flow of 32.59 Mgal/d, the velocity in the 30-inch force main would be 10.3 fps, which will incur significant headloss. Therefore, for the Stage 2 expansion, it is recommended to also install a parallel 30-inch force main to the Southside Plant.

Aerated Grit Tanks
The Phase IV Expansion Project will require 2 new Aerated Grit Tanks for Stage 1 and additional 2 tanks for Stage 2.

Primary Sedimentation Basins
The Phase IV Expansion Project will require 2 new Primary Sedimentation Basins for Stage 1 and additional 2 for Stage 2. It is expected that the four additional primary sedimentation tanks will be constructed at the Southside Plant.

New Membrane Bioreactors (MBRs)
The proposed MBR for the Phase IV Expansion Project is based on two 4.65 Mgal/d stages. Each 4.65 Mgal/d expansion stage will consist of two biological trains and two membrane tanks. Membrane sizes and costs are based on a preliminary proposal by Veolia. To allow competitive bidding by multiple MBR manufacturers, an evaluated bid pre-selection process is recommended before selecting a final MBR system which would be used to develop detailed construction drawings and specifications for the overall construction of the wastewater treatment plant expansion.

Biosolids Handling and Disposal Facilities
Sludge thickening facilities are currently comprised of two DAFTs and a third DAFT is recommended to be installed during the Interim Improvement Projects. The Phase IV Expansion Project will require one new DAFT for the Stage 1 project to meet the estimated peak month flow (no additional DAFTs are needed for the Stage 2 project). The fourth DAFT is proposed to match the design of existing DAFTs.

Sludge dewatering facilities are currently comprised of two small centrifuges. A third larger centrifuge is recommended to be installed during the Interim Improvement Projects. Since the existing Dewatering Building only has space for three centrifuges, the Phase IV Expansion Project will require replacement of the existing two small centrifuges with larger centrifuges to avoid having to expand the Dewatering ATTACHMENT 2
Building. One centrifuge will be replaced for Stage 1 and the second existing centrifuge will be replaced for Stage 2.

A fifth and sixth digester is required for Stage 1 and Stage 2 of the Phase IV Expansion project, respectively. The fifth and sixth digesters are proposed to have a 65 ft diameter to hold 662,000 gallons of sludge. The existing Digester Control Building will be expanded and include sludge control equipment, sludge transfer pumps, hot water equipment, heated sludge pumps, plant air system, and the biogas management system.

Biosolids disposal alternatives were evaluated in the Biosolids and Biogas Utilization Plan by HERWIT Engineering, April 2016. The recommendation from this study is to process the biosolids to Class A, or to Exceptional Quality (EQ) criteria. This is most easily achieved by drying dewatered biosolids from the centrifuge to greater than 75% solids. The benefit of this is additional flexibility in reuse, and reduction in biosolid hauling costs. This level of processing allows for sales to the public, and reuse of the product in City landscaping. Site space at the WQCF should be preserved to allow for future drying options as shown on Figure ES-15.

Effluent Cooling and Disposal
The existing NPDES permit currently limits the maximum flow capacity to 9.87 Mgal/d average dry weather flow before cooling the effluent is required. This requirement is based on hydrodynamic and thermal modeling studies of the San Joaquin River in 2006 and 2008. A comparison of recent effluent discharge and river temperatures from 2016 through 2021 has shown an increase in the temperature difference between the plant effluent and the river of 2°F to 5°F over what was used for all previous modeling. Therefore, a new river temperature study is recommended before proceeding with the design of the effluent cooling system.

Instead of constructing cooling towers as recommended in the previous studies, effluent could be used for groundwater recharge to help mitigate overdraft of the Eastern San Joaquin Groundwater Basin.

However, because of the relatively shallow depth to groundwater in the Manteca area, this use is not considered feasible in the central Manteca area. An export pump station and pipeline several miles in length would have to be constructed to an area of the basin with a greater groundwater deficit. As discussed in the Reclaimed Water Facilities Master Plan (Woodard & Curran, January 2023), this alternative has not been carried forward to the level of project alternative development but could be studied further in the context of the Sustainable Groundwater Management Act of 2014 which will require implementation of a Groundwater Sustainability Plan in the region.

Another potential alternative to the cooling towers is tertiary storage ponds where natural cooling can occur. A model was developed to estimate the magnitude of heat losses and gains by various mechanisms. Heat loss to the environment is dependent on the altitude, ambient air temperature, humidity, wind speed, and cloud coverage. Monthly average values for these parameters in Manteca were used. Since these calculations are not exact, a pilot study would be required to verify cooling effectiveness by this method before embarking on the construction of a full-scale tertiary storage ponds.

ATTACHMENT 2
If a suitable groundwater recharge project is not found and effluent cooling basins can’t provide sufficient cooling, then effluent cooling towers are recommended. Because the plant must comply with the permit at all times, a redundant cooling tower is recommended to allow maintenance of the cooling towers.

Cooling towers are sized based on total effluent flow. To provide blending of the cooling tower effluent for temperature averaging, a cooling effluent storage basin will be constructed for storing the cooled effluent before delivery to the San Joaquin River. A new pump station will be required to pump the cooled effluent from the basin through the existing outfall pipeline to the San Joaquin River.

New Municipal Utilities Building and Entrance Road
The WQCF has inadequate building space for the existing plant staff. New building space will also be required for additional staff to operate and maintain new treatment facilities for the next plant expansion.

To provide the required building space, it is recommended that a new Municipal Utilities Building be constructed at the WQCF. The proposed building, as shown on Figure ES-15, would be located adjacent to a new entrance road at the northeast end of the WQCF property just south of the intersection of West Yosemite Avenue and Swanson Road where a new intersection with traffic signal lights is being planned.

The proposed Municipal Utilities Building will serve all departments in public works including water, solid waste, and wastewater. The estimated construction cost (in current dollars) is $30M which will be shared equally between the three departments.

The recommended project will also include an asphalt paved parking lot for the building and automated road access gates on the entrance road after the building to restrict public access to the main treatment plant as shown on Figure ES-15.

ES.10.3 Phase IV Expansion Costs
Preliminary estimates of total project costs are presented in the following Table ES-13. Construction costs were developed using costs for similar construction at other wastewater treatment plants and equipment manufacturer quotes. These costs are based on an Engineering News Record Construction Cost Index (ENRCCI) 20-Cities Average of 13,176 (representing costs in March 2023 dollars).

The total project costs (including project construction, engineering, administration, and construction management) are estimated at $146.3 million and $70.6 million for the Stage 1 and Stage 2 expansions, respectively. It should be noted that these costs will have to be escalated as appropriate to get costs at the actual times of construction.

ATTACHMENT 2
Table ES-13. Phase IV Expansion Project Costs
Description Stage 1 Project Cost Stage 2 Project Costs
Influent Flow Meter $896,000 $0
Influent Pumps $597,000 $989,000
Aerated Grit Tanks at Southside Plant $1,055,000 $1,055,000 Primary Sedimentation Basins at Southside Plant $4,611,000 $4,611,000 Extend Aeration Basins at Southside Plant $936,000 $0
Splitter Structure $468,000 $63,000
Fine Screens for MBRs $2,802,000 $900,000
MBRs Structure & Equipment $15,399,000 $15,399,000
MBR Blower Building and Equipment $1,878,000 $1,878,000 Effluent Pump Station Expansion & Pumps $806,000 $582,000 Cooling Effluent Basin $2,013,000 $0
Effluent Cooling Towers $11,835,000 $2,555,000
Cooling Basin Effluent Pump Station $2,658,000 $582,000 DAFTs $2,240,000 $0
Biotower Demolition $500,000 $0
Anaerobic Digesters $2,660,000 $2,660,000
Digester Control Building Extension & Equipment $1,095,000 $255,000 Centrifuge and Ancillary Equipment $2,923,000 $2,923,000 Municipal Utilities Building and Entrance Road $10,685,000 $0 Biosolids Drying Facilities $17,308,000 $5,769,000
Subtotal Construction Estimate $83,365,000 $40,221,000
Construction Estimating Contingency @30% $25,010,000 $12,066,000 Construction Cost with Contingency $108,375,000 $52,287,000 Engineering, CM, and Admin @35% $37,931,000 $18,300,000 Total Project Cost $146,306,000 $70,587,000
Key:

MBR = Membrane Bioreactor
DAFT = Dissolved Air Flotation Thickener
CM = Construction Management
ATTACHMENT 2
ES.11 STAFFING PLAN
The WQCF will undergo Interim capacity improvements that will increase capacity to 8.23 Mgal/d and then a proposed Phase IV Expansion in two stages. Stage 1 will expand the WQCF treatment capacity from about 8.23 Mgal/day to 12.9 Mgal/day and Stage 2 will expand it to a capacity of 17.5 Mgal/day.

The purpose of this chapter is to estimate the manpower requirements to operate the collection and treatment systems and to discuss the personnel qualifications, responsibilities, and certifications. Further, this chapter provides recommendations on staffing levels needed to manage the future WQCF and sewer collection infrastructure.

A summary of the staffing recommendations for before and after the expansions detailed in Chapter 11 are summarized in Table ES-14.

Table ES-14. Summary of Staffing Recommendations
Parameter
Persons
Existing Recommended for
Existing
Stage 1 (12.9
Mgal/d)
Stage 2 (17.5
Mgal/d)
WQCF Operations 8 10 13 13
WQCF Maintenance 10 10 13 16
Laboratory & Regulatory
Compliance 5 7 8 8
SCADA 1 1 1 1
Collection System 10 13 14 15
Supervisory/Admin 11 12 12 12
Net Total 45 53 61 65
A total of eight (8) more FTE are recommended for the existing WQCF and collection system. After the Stage 1 expansion, total personnel will increase to a total of 61 and after the Stage 2 expansion it will increase to a total of 65. SCADA and Supervisory staff will experience no change during the expansions unless it is deemed necessary.

ATTACHMENT 2
ES.12 CAPITAL IMPROVEMENT PROGRAM
This section highlights the content of Chapter 12, that presents a Capital Improvement Program (Program) that summarizes the Capital Improvement Projects (CIPs) identified in the previous chapters of this Master Plan. CIPs are presented chronologically to distribute costs over time in keeping with each project’s criticality or other City priorities, but final project inclusion in the adopted City CIP and associated dates are approximate and adjustable. No CIP is final until acted on by the City Council.

This chapter is divided into the following sections:
• Background
• Project Prioritization
• Cost Estimating Methodology
• Proposed Capital Improvement Program
ES.12.1 Background
Based on the completed hydraulic modeling and evaluation of the City of Manteca’s wastewater collection system and capacity assessment of the Manteca Wastewater Quality Control Facility (WQCF), a Capital Improvement Program (Program) was prepared. The Program includes recommended CIPs segmented into two categories: 1) Wastewater Collection System Projects (WCS), and 2) Wastewater Quality Control Facility Projects (WQCF).

ES.12.2 Project Prioritization
CIP prioritization is based on giving the highest priority to those projects that pose the most risk to the community. The priority raking is as follows: 1) The highest risk to the community is infrastructure that is in poor condition that could potentially cause failure such as a collapsed gravity sewer pipe or treatment process that is not functioning properly; 2) The second highest risk is failure to comply with regulatory requirements such as non-compliant wastewater discharged to the San Joaquin River subjecting the City to mandatory fines; 3) The third highest risk is limited capacity under current flows to convey and treat the wastewater such as gravity sewers that are surcharging at the manholes, 4) The fourth highest priority is limited capacity to serve future growth; and 5) The lowest priority are projects desired by City staff to improve operation and maintenance.

ES.12.3 Cost Estimating Methodology
A key element to the Program is determining budgets for each of the identified CIPs. The projects and associated costs identified herein are presented in March 2023 dollars (Engineering News Record Construction Cost Index [ENRCCI] of 13,176) and should be reviewed and updated on an annual basis using the ENRCCI or another recognized index.

Construction costs were developed based on a combination of equipment quotes supplied from manufacturers, bids on other City wastewater facilities projects, construction cost estimates from similar type construction projects, and standard cost estimating guidelines.

ATTACHMENT 2
Soft costs include a 30 percent mark-up for construction cost estimating and a 35 percent mark-up of the total construction cost for engineering, construction management and administration, which includes engineering design and engineering services during construction, construction administration, construction inspection services, and general administration costs by the City.

ES.12.4 Proposed Capital Improvement Program
The wastewater collection system CIPs are listed in Table ES-15 and WQCF CIPs are listed in Table ES16. Project costs for each CIP (in 2023 dollars) and a rough estimated of the project’s scheduled completion (calendar year) are provided for each CIP. Figure ES-16 shows the annual estimated expenditures for both wastewater CIP categories.

ATTACHMENT 2
Table ES-15. Summary of Wastewater Collection System CIP Projects CIP Description Project Costs Scheduled
Completion
Existing Wastewater Collection System Capacity Improvements WCS-01 W. Center Street Trunk $4,880,000 2031
WCS-02 Elm/West North Street Trunk $5,080,000 2031
WCS-03 10-inch East North Street Trunk $1,660,000 2031
WCS-04 8-inch East North Street Trunk $510,000 2031
Previously Identified Wastewater Collection System Improvements WCS-05 South Woodward Trunk Extension $12,640,000 2031
WCS-06 Central Union Road Trunk Extension $16,170,000 2026 WCS-07 North Trunk Extension on Airport Way $34,340,000 2035 Future Wastewater Collection System Improvements
WCS-08 S. Main Trunk to Evans $7,180,000 2032
WCS-09 S. Airport Way and Yosemite Ave. (Fishback) $3,100,000 2032 WCS-10 S. Airport Way Roberts Estates to Daniels $1,750,000 2032 WCS-11 Yosemite Square Lift Station and Improvements $12,880,000 2032 WCS-12 Austin Road Industrial Area Trunk $20,810,000 2035 WCS-13 South Austin Road - Industrial Area $5,780,000 2036 WCS-14 Yosemite Square Service Area $4,240,000 2037
WCS-15 Oleander Avenue Extension/ S. Airport Way Sewer $6,660,000 2036 WCS-16 Highway 99 Crossing at Northland Road $9,310,000 2038 WCS-17 East Lathrop Road Trunk $12,060,000 2040
WCS-18 Construct new 24-inch bypass sewer $6,630,000 2039 WCS-19 Northland Road Branches $6,350,000 2040
WCS-20 Louise/ Nehemiah Branches $5,160,000 2040
WCS-21 South Union Road Extension $4,590,000 2041
WCS-22 Cottage Avenue $3,080,000 2042
WCS-23 North Shed Union Road Trunk $13,130,000 2043
WCS-24 Manteca Junction Trunk $3,730,000 2044
WCS-25 Lovelace Road - 99 Crossing $18,090,000 2044
Ongoing Rehabilitation and Replacement Projects
WCS-26 UPRR Right of Way and Ally Between Center Street and Yosemite $489,000 2024 WCS-27 Moffat Boulevard and Main Street $1,022,000 2024 WCS-28 Oak Street from Main Street to Willow Avenue $98,000 2024 WCS-29 Sequoia Avenue from Oregon Street to Alley north of Nevada Street $53,000 2024 WCS-30 Tidewater Bike Path from Sandalwood Lane to Louis Avenue $348,000 2024 WCS-31 Walnut Avenue from the alley north of Nevada Street to the UPRR $279,000 2024 WCS-32 St. Dominic’s Drive from north of Yosemite Avenue to Golf Course $29,000 2024 Wastewater Collection System CIP Projects Total $222,128,000 - ATTACHMENT 2
Table ES-16. Summary of WQCF CIP Projects
CIP Description Project
Costs
Scheduled
Completion
WQCF Capacity Assessment Interim Projects
WQCF-01 North and South Plant WAS Pump Replacement Project $2,827,000 2024 WQCF-02 South Plant RAS Pump Replacement Project $1,652,000 2024 WQCF-03 North and South Plant Aeration Basins Improvements $11,696,000 2025 WQCF-04 Sidestream Treatment System $20,205,000 2028
WQCF-05 Add Centrifuge No. 3 $5,130,000 2026
WQCF-06 Add DAFT No. 3 $3,930,000 2026
Instrumentation and Electrical Improvements
WQCF-07 I&E Core Supervisory Control and Data Acquisition (SCADA) System $1,127,000 2026
WQCF-08 I&E Remote Site Process Logic Controller (PLC) Upgrades $1,727,000 2026 WQCF-09 I&E PLC and Operator Interfaced Terminal (OIT)
Replacement $1,374,000 2029
WQCF-10 I&E Switchgear PLC Upgrades $127,000 2027
Other Interim Improvement Projects
WQCF-11 Add Influent Pump No. 5 $1,048,000 2024
WQCF-12 Lightweight Covers for Process Basins $5,792,000 2029 WQCF-13 Headworks, IPS and Biofilter Improvements $2,080,000 2026 WQCF-14 UV Disinfection System Upgrade $15,583,000 2026 WQCF-15 Plant Water System Piping Modifications $636,000 2024 WQCF-16 Replace Secondary Effluent Equalization Pond Liner $2,101,000 2024 WQCF-17 Headworks Screen No. 3 $900,000 2027
WQCF-18 FOG Receiving Station Screening System $200,000 2024 WQCF-19 Bulk Ferric Chloride Solution Tanks $351,000 2024 WQCF-20 Digesters No. 1 and 2 Overflow Boxes $706,000 2024 WQCF-21 Digester Pressure Relief Valves Platform & Handrailing $205,000 2024 WQCF-22 Install New Waste Heat Radiator $198,000 2024
WQCF Phase IV Expansion Project
WQCF-23 WQCF Phase IV Stage 1 Expansion Project $146,306,000 2030 WQCF-24 WQCF Phase IV Stage 2 Expansion Project $70,587,000 2047 WQCF CIP Projects Total $296,488,000 -
ATTACHMENT 2
Figure ES-16. Proposed CIPs Annual Estimated Expenditures The following is a bulleted summary of the recommendations presented in this Wastewater Master Plan:

ES.12.5 Conclusions and Recommendations
Key conclusions and recommendations from this WWMP include:
• The average per capita ADWF discharged to the WQCF is 61 gallons per person per day (gpcd).

The United States Census Bureau identifies an average household density of approximately 3.19 persons per household, or persons per equivalent dwelling unit (EDU) within the City of Manteca and was used to translate the per capita flow into the ADWF unit rate of 195 gpd/EDU. • The Manteca full build-out flow (see Chapter 5) is approximately 15.3 Mgal/d (ADWF). Adding Lathrop’s flow contribution of 1.45 Mgal/d gives a total flow of 16.8 Mgal/d (ADWF). Master Planning for 17.5 Mgal/d (ADWF) would provide enough capacity for Manteca’s full build-out flow plus Lathrop and other flow contributions from developments outside of the City such as Oakwood Shores and Raymus Village. Based on an annual population growth rate of 2.8% and assuming influent loadings to the WQCF increase proportional to population growth, 17.5 Mgal/d would provide capacity until the year 2057 serving an equivalent Manteca population of 236,000. $0
$5,000,000
$10,000,000
$15,000,000
$20,000,000
$25,000,000
$30,000,000
$35,000,000
$40,000,000
$45,000,000
22/2323/2424/2525/2626/2727/2828/2929/3030/3131/3232/3333/3434/3535/3636/3737/3838/3939/4040/4141/4242/4343/4444/4545/4646/47 Wastewater CIP Expenditure
Wastewater Collection WQCF
ATTACHMENT 2
• Based on the review of the previous wastewater collection system planning documents, the City has alternated between two collection system strategies: 1) The 2012 Master Plan strategy includes a shallower collection system with a number of interim and permanent sewage lift stations; and 2) The 2006 Master Plan strategy which includes deeper trunk sewers minimizing the overall need for sewage lift stations. This WWMP assumes a deeper trunk strategy to avoid major upgrades to the existing sewage lift stations that would be required to accommodate growth, and to reduce the maintenance costs associated with operating numerous pump stations in the system.
• The City recently completed a project replacing the North Trunk Sewer. The project replaced the 36-inch trunk sewer with a larger and deeper 54-inch sewer. The Central Trunk should be extended from the upstream point of the North Trunk project to bypass the Union Road Sewage Lift Station and allow flow from the Central Shed to flow by gravity to the WQCF. This project identified as the Central Union Road Truck Extension (WCS-06) in the Capital Improvement Program would allow decommissioning of the Union Road Sewage Lift Station which is beyond its useful life and in very poor operating condition.
• The alternative improvements recommended for the Woodward Park Sewage Lift Station include:
1) increasing the firm pumping capacity to meet the maximum inflow of approximately 2.8 Mgal/d by adding an additional pump to the station or swapping out the existing pumps, or 2) installing 4,030 LF of 36-inch sewer to extend the existing South Trunk in Woodward Avenue to reach the unused existing 36-inch sewer at the intersection of Woodware Avenue and S. Main Street. The recommended project (WCS-05) is to install the 36-inch sewer pipe which would eliminate the Woodward Park Sewage Lift Station and the Evan’s Sewage Lift Station. • Seven rehabilitation and replacement projects identified in Chapter 6 were given the highest priority rating in the Capital Improvement Program due to the potential for failure such as a collapsed sewer pipe or sanitary sewer overflow due to blockage. It is recommended these projects be scheduled as soon as practical and to continue cleaning and inspecting the pipelines and manholes within the system at a rate of approximately 5% to 10% per year, respectively. • A capacity study of the WQCF completed in 2021 determined immediate improvements to the WQCF that are needed for nitrogen removal. Without these improvements, the WQCF will be challenged to meet permit discharge requirements. The proposed improvements, including sidestream treatment to remove nitrogen from the digester centrate, will provide an estimated 8.23 Mgal/d of ADWF capacity.
• Measured influent flows at the WQCF include plant recycle flows and are not the true influent flow from Manteca’s wastewater collection system and City of Lathrop. The measured influent flow at the WQCF includes plant recycle flows which are approximately 12% of the total measured flow.

From December 2019 through November 2020, the City of Lathrop’s average annual flow was

1.07 Mgal/d or 16.8% of the total true influent flow of 6.36 Mgal/d. Lathrop’s flow limit, if they participate in funding their share of the proposed Interim Improvements, would increase to 1.21 Mgal/d (14.7% x 8.23 Mgal/d).

ATTACHMENT 2
• Several other Interim Improvement projects to correct WQCF deficiencies are identified in Chapter 9. These projects, listed on Table ES-11, include safety items such as improving the ventilation system for the Headworks and Influent Pump Station, and permit compliance improvements such as upgrading the UV disinfection system. • The recommended WQCF Phase IV Expansion Project to increase the plant capacity to 17.5 Mgal/d ADWF will be constructed in two stages. The first stage project scheduled for completion in 2030, will add Membrane Bioreactors (MBRs) that will be operated in parallel with the existing Conventional Activated Sludge (CAS) treatment system. The project will also include in-kind expansion of pumps, aerated grit tanks, primary sedimentation basins, DAFT, dewatering equipment, digesters, and cooling towers.
• Instead of constructing cooling towers as recommended in the previous studies, effluent could be used for groundwater recharge to help mitigate overdraft of the Eastern San Joaquin Groundwater Basin. However, because of the relatively shallow depth to groundwater in the Manteca area, this use is not considered feasible in the central Manteca area. Further investigation of a suitable groundwater recharge site is recommended as the preferred alternative to cooling towers.

ATTACHMENT 2

1.0 INTRODUCTION AND BACKGROUND
The purpose of this chapter is to present the Master Plan scope of work, study area, and background information.

This chapter includes the following:
• Scope of Work
• Study Area Definition
• Background Information and Review

1.1 SCOPE OF WORK
This Wastewater Master Plan (WWMP) summarizes the comprehensive evaluation of the capacity and condition of the City of Manteca’s wastewater system’s to safely convey and treat current and projected future wastewater flows and develop a sustainable and defendable plan to address level of service deficiencies through a prioritized long-term Capital Improvement Program (CIP).

The objectives of the WWMP include:
• Review and incorporate information, analysis, and recommendations from previous relevant studies and reports.
• Collect and analyze sewer flow data at various locations within the collection system to determine both dry weather wastewater generation characteristics and influence on flows during wet weather conditions. This was completed through a temporary flow monitoring study that collected in-sewer flow data over a period of approximately two months at 18 locations throughout the system, which was analyzed and used as a critical input to the hydraulic modeling analysis and basis for projecting flows from future City growth. • Collect, analyze, and combine information from City supplied information including existing geographic information systems (GIS) databases, record drawings, operational information, and other related information to develop the representation of the collection system in a computational hydraulic model in the PCSWMM software. The flow data collected by the flow monitoring study as well as meter data obtained from the Wastewater Quality Control Facility (WQCF) was used as inputs to the model and the basis for calibration to varying flow conditions. • Using the PCSWMM model, assess the capacity of the existing collection system to safely convey peak dry weather flows (PDWF) and peak wet weather flows (PWWF), identify locations within the existing system that do not meet the minimum level of service (LOS) criteria, and evaluate potential conceptual solutions to address the identified deficiencies. • Conduct an evaluation of the capacity of the City’s existing system to convey projected flows from future City growth areas and infill developments as identified in the General Plan, under ATTACHMENT 2
three future design horizon scenarios (near term, interim and build-out) and identify capacity deficiencies and potential improvement requirements to meet the same LOS criteria as evaluated for the existing system.
• Review the 2017 Condition Assessment Study and update the summary of recommended improvements from this study.
• Conduct an evaluation of the City’s Wastewater Quality Control Facility (WQCF). The evaluation included 1) describing the WQCF background and regulatory requirements, 2) conducting a flow and load analysis (including a solids mass balance) to estimate the flows and loads needing to be treated under existing and future conditions, 3) assessing the WQCF existing facilities to determine what improvements (and the associated estimated budgetary project costs) are needed for the Interim Improvement Projects to meet permit requirements for the projected nearterm flows and loads, and 4) determining improvements and associated estimated budgetary project costs that are needed for the Phase IV Expansion Project to increase the WQCF treatment capacity to 17.5 million gallons per day (Mgal/d). • Prepare a prioritized Capital Improvement Plan (CIP) for strategic projects including capacity and rehabilitation upgrades to existing infrastructure and recommendations for construction of new infrastructure to meet system needs in the near-term (5 years) and long-term (20 years) along with conceptual opinions of probable construction costs (OPCC).

1.2 STUDY AREA
The City of Manteca (Manteca) is located in the Central Valley of California within San Joaquin County, approximately 70 miles east of San Francisco, with an estimated population of 85,792 people (Source:
2021 US Census). The City’s Municipal Services Review cites a population growth rate of 3.8% between 2000 and 2010, and approximately 2.6% over the last decade. The growth rate used in this WWMP is

2.8% to conservatively reflect more recent trends. The existing City limits encompasses an area of 13,728 acres or approximately 21.5 square miles. The existing wastewater collection system includes residential (69%), commercial (8%), industrial (9%), municipal (9%), and mixed-use (4%) areas within the City and accepts flow from surrounding member jurisdictions.

Manteca operates and maintains the WQCF which accepts flows from the City of Manteca, City of Lathrop, Oakwood Shores, and Raymus Village in San Joaquin County. Manteca operates its own sewer collection system serving connections within City boundaries while member jurisdictions (Lathrop, Raymus Village, and Oakwood Shores) own and operate their own collection systems which convey wastewater flows to the City’s collection system. Flow from the City of Lathrop discharges through a force main connecting to the north trunk influent sewer at Yosemite Avenue leading to WQCF influent headworks. Flow from Raymus Village discharges through a force main that ties into the existing system at Southland Road near Highway 99, and Oakwood Shores discharges through a force main that ties into the existing system at the intersection of Woodward Avenue and McKinley Avenue. Figure 1-1 shows an overview of the existing sewer collection system.

ATTACHMENT 2
C ali fo rni a
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YOSEMITE AV

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MAIN ST

AIRPORT WY
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LOUISE AV
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LATHROP RD
WQCF
Outfall
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-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Lift Station
City Owned
Privately Owned
Sanitary Network
Private Sanitary Network
Water Quality Control Facility Structures
City of Lathrop Discharge
City of Lathrop Collection Boundary
Raymus Village Collection Boundary
Oakwood Shores Collection Boundary
City of Manteca Limit
1-1
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/24/2023
TR by MA on 10/24/2023
IR Review by MVD on 10/24/2023
Existing Sewer Collection System
Overview
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-24 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

1.3 BACKGROUND INFORMATION AND REVIEW
The following provides a summary of the background information reviewed and incorporated into the development of this WWMP, including regulatory plans, service agreements, technical reports, and City planning documents.

1.3.1 Sewer System Management Plan (SSMP)
The City’s collection system is currently permitted to operate under State Water Resources Control Board General Order No. 2006-0003-DWQ, Statewide General Waste Discharge Requirements for Sanitary Sewer Systems, which requires the City to develop and implement a Sewer System Management Plan (SSMP) that describes how the City operates and maintains the collection system in compliance with General Order requirements.

The SSMP describes how the collection system is operated and maintained and includes the following sections:
• Introduction
• Organization
• Overflow Response Plan
• Fats, Oils and Grease Control Program
• Legal Authority
• Operations and Maintenance
• Design and Construction Standards
• Capacity Management
• Monitoring, Measurement and Program Modifications
• Outreach and Communications Program
• Sewer System Management Plan – Summary of Recommendations The City of Manteca’s current SSMP dated January 8, 2020, is included in Appendix A.

The General Order 2006-0003-DWQ has been recently updated (December 6, 2022) with the adoption of Order WQ 2022-0103-DWQ, which became effective on June 5, 2023. The new Order can be viewed and downloaded via the State Water Resources Control Board Website.

In particular, the new Order contains the following notable reporting changes (among others):
• Annual reports (formerly the sewer system questionnaire) must be submitted by April 1st. • All SSMPs must be updated on or before May 25, 2025, and at least every 6 years thereafter.

There are also new requirements for the content of SSMPs, and SSMP documents must be uploaded in CIWQS.
• The first Program Audit under the new Order must be performed within 2 years of the last audit performed under the existing Order, and at least every 3 years afterward. Audit Reports must be uploaded in California Integrated Water Quality System, CIWQS.

ATTACHMENT 2
• At a minimum the audit must:
o Evaluate the implementation and effectiveness of the enrollee’s SSMP in preventing spills; o Evaluate the Enrollee’s compliance with the General Order; o Identify SSMP deficiencies in addressing ongoing spills and discharges to waters of the State; and
o Identify necessary modifications to the SSMP to correct deficiencies.

1.3.2 Service Agreements
The City of Manteca provides sanitary sewer service to the City of Lathrop in accordance with a regional service agreement, most recently amended on May 26, 2016, originally signed on March 5, 1985. The terms of the current agreement outline the rights and responsibilities of each party, treatment capacities, costs, discharge limitations, and define the legal parameters associated with the regional treatment agreement. The agreement allocates 14.7 percent of the Manteca WQCF capacity to accommodate flows discharged to the plant from Lathrop. The City of Manteca maintains and operates the WQCF and its own wastewater collection system. Lathrop maintains its collection systems as well as its own wastewater treatment plant, the Lathrop Consolidated Treatment Facility which serves a portion of the City.

Lathrop’s wastewater generated east of I-5 and north of Louise Avenue in the Historic Lathrop area is conveyed via gravity sewers and lift stations to a regional pump station, the O Street PS. Wastewater generated in industrial parcels located near McKinley Avenue is conveyed to the McKinley Avenue PS.

Wastewater from the McKinley Avenue PS and O Street PS converge at the McKinley intertie, which is capable of sending converged flow via a 12-inch and/or a 16-inch diameter force main to the Manteca WQCF. These force mains discharge to the Manteca North Trunk sewer at Yosemite Avenue and also convey wastewater from the Louise Avenue and other private pump stations that serve the industrial areas east of I-5.

The City also provides sanitary sewer service to the Oakwood Lake Water District (which includes the Oakwood Shores Subdivision and the Islander Mobile Home Park) in accordance with a regional service agreement, amended in 2020, originally signed May 9, 2019. Like the agreement with Lathrop, the agreement outlines terms of the regional service agreement. The agreement includes the entitlement of up to 436 single family residences (Entitled Units) and related parks, semipublic sites, and open space facilities, together with any and all onsite and offsite private and public improvements. The agreement also entitles the 57 units within the Islander Mobile Home Park and allows as many as an additional 150 units ranging from low to high density residential that could possibly be approved by the County and included in the agreement.

In February 2022 the Oakwood Lake Water District commissioned new wastewater facilities and began to pump untreated wastewater to Manteca. This allowed the District to begin to decommission their existing wastewater treatment and disposal facilities. The new facilities include a pump station and an 8-inch force main that discharges to the existing City collection system at the intersection of West Woodward Avenue and South McKinley Avenue. This infrastructure was not included in the hydraulic model developed as part of this Master Plan.

ATTACHMENT 2

1.3.3 2012 Collection System Master Plan
The City’s previous Wastewater Collection System Master Plan Update (2012 Master Plan) was developed by NV5 Global Inc. in January 2013 as an update to the City’s 2006 Wastewater Collection System Master Plan (2006 Master Plan). The 2012 Master Plan update incorporated current planning and sewer alignment information, revised wastewater generation factors (WGF), and updated construction costs.

The primary objective of the 2012 Master Plan was to ensure that the City’s trunk sewer system can costeffectively meet the demands of development goals adopted in the General Plan with appropriate consideration for construction costs and operation and maintenance issues. The 2012 Master Plan goals were to address:

1. Current and future land uses from the General Plan 2023 Policy Document.

2. Design of trunk sewers, force mains, pump stations, and lift stations to accommodate service areas.

3. Capacity of the trunk sewer system.

4. Phased capital improvement plan (CIP) for the proposed conveyance option.

The 2006 Master Plan proposed the construction of three large diameter trunk sewers to collect wastewater from the north, central, and south sections of the City for conveyance to an influent pump station located at the WQCF. This strategy of deep gravity trunk sewers was consistent with previous master plans.

The depth and size of trunk sewers required to implement the strategy set forth in the 2006 Master Plan presented significant capital costs. A revised conveyance strategy including a combination of gravity sewers, force mains, lift stations, and pump stations was evaluated as part of the 2008 Addendum to the Wastewater Collection System Master Plan (2008 Addendum).

The 2012 Master Plan updated the 2008 Addendum with current planning and alignment information, revised WGFs incorporating water conservation requirements and historic commercial and industrial water use data, and updated construction costs. The conveyance strategy evaluated as part of this 2012 Master Plan was to minimize pipe size and depth based on pipes flowing 70-80% full at peak flows with lift or pump stations constructed as needed to reach the trunk sewers.

The recommended overall trunk sewer strategy consisted of a combination of trunk sewer gravity collection system with pump or lift stations located along the alignment to convey wastewater to an influent pump station at the WQCF. The 2012 Master Plan presents recommended improvements in the following categories the North Manteca Collection Strategy (NMCS), South Manteca Collection Strategy (SMCS), and Central Manteca Collection Strategy (CMCS). The NMCS and SMCS will collect flow from areas where future growth is expected, including Sphere of Influence (SOI) areas, while the CMCS will connect the existing system to the NMCS.

ATTACHMENT 2

1.3.4 Manteca General Plan Update
The City of Manteca is currently working on updating their General Plan. The General Plan is a longrange planning document that is considered the City’s “constitution” or blueprint, because it identifies the City’s goals and vision for growth, traffic patterns, economic development, housing, and more. The General Plan is intended to serve the following purposes:
• To identify Manteca’s land use, growth, transportation, environmental, economic, and social goals and policies as they relate to land use, conservation, development, and provision of community services and facilities.
• To enable the City Council and the Planning Commission to establish long-range conservation and growth goals and policies.
• To provide a basis for judging whether specific private development proposals and public projects are in harmony with these goals and policies.
• To inform citizens, developers, decision makers, and other jurisdictions of the policies that will guide development and conservation within the Manteca.

The General Plan process includes a comprehensive evaluation of the City’s planning boundaries, including the City’s Sphere of Influence (SOI). The City provided a copy of the Revised Public Review Draft of the Manteca General Plan Update (October 2022) report and GIS land use file. The City of Manteca’s Draft General Plan estimates a buildout population of 211,003 people. Land uses within the General Plan serve as the basis to estimate wastewater flow rates from future development. The total acreage, sorted by land use designation, within the existing City General Plan planning area is presented in Table 1-1. The City of Manteca General Plan land use map is shown on Figure 1-2.

ATTACHMENT 2
Table 1-1. Manteca General Plan Land Use
Land Use Description Area (Acres)
Agricultural Industrial 232
Agriculture 4,004
Business Industrial Park 597
Business Professional 83
Commercial 1,202
Commercial Mixed Use 673
Downtown 160
High Density Residential 489
Industrial 2,956
Low Density Residential 8,992
Medium Density Residential 707
Not in Planning Area 473
Open Space 475
Park 742
Public/Quasi-Public 1,375
Right of Way 179
Very Low Density Residential 1,267
Water 180
Total 24,786
ATTACHMENT 2
C ali fo rni a
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City of Manteca Limit
Land Use Designation
AI - Agricultural Industrial
AG - Agriculture
C - Commercial
CMU - Commercial Mixed Use
DW - Downtown
VLDR - Very Low Density Residential
LDR - Low Density Residential
MDR - Medium Density Residential
HDR - High Density Residential
BIP - Business Industrial Park
BP - Business Professional
I - Industrial
OS - Open Space
P - Park
PQP - Public/Quasi-Public
1-2
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Manteca General Plan
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

2.0 EXISTING WASTEWATER COLLECTION SYSTEM
This chapter provides an overview of the City’s existing wastewater collection system. The information presented in this chapter is based on the review of previous studies, design reports, maps, plans, operating records, GIS data, and discussions with City staff. This chapter also presents existing sewer flows and population data, including data collected as part of the collection system flow monitoring study.

This chapter is divided into the following sections:
• Collection System Overview
• Existing Sewer Flows

2.1 COLLECTION SYSTEM OVERVIEW
The Manteca WQCF is located southwest of downtown Manteca at 2450 West Yosemite Avenue. The WQCF treats typical municipal wastewater generated in the City of Manteca (City) and the neighboring City of Lathrop, which is discharged upstream of the WQCF influent meter at the intersection of the North Trunk sewer and Yosemite Avenue. A separate industrial line accepts food processing wastewater seasonally from Eckert Cold Storage from May through November.

The existing collection system consists of approximately 250 miles of 4-inch to 60-inch diameter gravity sewers, 3- to 24-inch diameter force mains, and a number of lift and pump stations. Information regarding these conveyances and facilities, as reported by the City’s GIS database and provided by City staff, is presented in the following sections. It is understood that these GIS databases may be subject to revision and confirmation, additional information regarding the City’s GIS database is provided in Section 3.2. All pipeline quantities discussed exclude lines indicated as either inactive or abandoned in the City’s GIS database.

2.1.1 Service Areas
The City’s Wastewater Quality Control Facility (WQCF) serves the City of Manteca, City of Lathrop, Oakwood Shores, and Raymus Village in San Joaquin County. According to the 2020 SSMP the City provided service through approximately 19,500 connections to a population of approximately 81,345. The City’s sewer service area is contiguous with city limits and is divided into North, South, and Central service sewershed areas. The North Shed contributes 10 percent, the South Shed contributes 30 percent, and the Central Shed contributes 60 percent of the total flow.

Figure 2-1 shows the boundaries of the different service areas.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4560000 4557000 4554000 4551000 4548000 4545000
4560000 4557000 4554000 4551000 4548000 4545000
-13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 -13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Lift Station Status
Active
Unmodeled
Inactive
Abandoned
Modeled Sanitary Sewer
Private Sanitary Network
Water Quality Control Facility Structures
City of Lathrop Discharge
Oakwood Shores Collection Boundary
Raymus Village Collection Boundary
City of Lathrop Collection Boundary
Service Area
Central Shed
North Shed
South Shed
City of Manteca Limit
2-1
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/24/2023
TR by MA on 10/24/2023
IR Review by MVD on 10/24/2023
Sewer Collection System and Service Area
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-24 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

2.1.1.1 Central Service Area
The majority of the collection system serves the core of the City (Central Shed), approximately bounded by SR-120 to the south, Austin Road to the east, Airport Way to the west, and Lathrop Road to the north.

Subdivisions located on the perimeter of the Central Shed have installed temporary pump stations, which have or will be decommissioned upon connection to gravity trunk sewers. Within the Central Shed, the majority of the collection system flows by gravity to the Union Road Pump Station (URPS). Downstream of the URPS, wastewater flows to the WQCF by gravity.

2.1.1.2 North Service Area
The North Shed includes the City planning area north of SR120 and Yosemite Avenue outside of the Central Shed. Much of the predicted development is within the North Shed which is largely undeveloped and lacking infrastructure needed to serve the area. Primary infrastructure in the North Shed includes the North Trunk gravity sewer which receives flow from the Central Shed as well as discharge flow from lift stations that exist within the North Shed. These lift stations include Centerpoint, Woodbridge Park, Chadwick, Villa Ticino, and private lift stations on E. Louise Avenue. A private lift station at Raymus Village Park also exists within the North Shed but discharges to a manhole in the Central Shed at Southland Road along with another private lift station serving a small subdivision on S. Frontage Road.

2.1.1.3 South Service Area
The South Shed includes the City planning area south of SR120 and Yosemite Avenue outside of the Central Shed. Like the North Shed, much of the South Shed remains undeveloped, though many subdivisions have been constructed and expanded along the Woodward Avenue corridor in the last 10 to 15 years. The Oakwood Shores subdivision recently decommissioned its onsite treatment system and started pumping wastewater to the South Shed. Primary infrastructure in the South Shed includes the South Trunk gravity sewer and smaller gravity sewers, force mains, and lift stations along Woodward Avenue. Many of these lift stations were considered temporary and have been taken out of service. A 36- inch gravity sewer in Woodward Avenue has allowed for many of the temporary pump stations to be decommissioned, including Airport Road, Tara Park, Belle Vista, and Antigua. The primary active pump stations in the South Shed include the Woodward Park and Evans Estates pump stations. Several subdivisions are currently being constructed in the western portion of the service area along with a new regional lift station.

The total acreages of the north, central, and south service areas including developed and undeveloped portions are summarized in Table 2-1 from City GIS data.

Table 2-1. Collection System Service Areas
Service Area Developed (Acres) Undeveloped (Acres) Total (Acres) North 1,166 9,145 10,312
Central 3,365 717 4,083
South 1,990 7,927 9,917
Total: 6,522 17,789 24,311
ATTACHMENT 2

2.1.2 Gravity Sewers
The City’s existing wastewater collection system comprises approximately 250 miles of gravity sewers ranging from 4-inch diameter to 60-inch diameter. Table 2-2 provides a summary of gravity sewers by diameter. As shown in Table 2-2, the majority of existing gravity system is comprised of 6-inch and 8-inch diameter sewers (77%). Approximately 2% of the sewers are of unknown diameter or have a reported diameter that is shown as non-standard and could therefore possibly have been misreported. Pipe diameters within the collection system are shown graphically in Figure 2-2.

Table 2-2. Gravity Mains by Diameter1
Pipe Diameter (in) Length (ft) Portion of Total Length (%) 4 1,330 0.1
6 719,713 54.6
8 293,358 22.3
10 78,243 5.9
12 58,893 4.5
15 32,953 2.5
18 19,609 1.5
21 9,239 0.7
24 13,211 1.0
27 1,100 0.1
30 17,772 1.3
36 37,073 2.8
42 5,777 0.4
48 5,119 0.4
54 1,614 0.1
60 2,670 0.2
Unknown/Non-Standard 20,121 1.5
Total 1,317,795 100
Note:
1 Data summarized from the City of Manteca’s GIS sanitary sewer line shapefile (wwConveyance.shp), March 2022. Excludes pipes designated as inactive or abandoned.

The gravity sewer materials are summarized in Table 2-3 and shown in Figure 2-3. The most common sewer pipe materials are polyvinyl chloride (PVC) and vitrified clay pipe (VCP), which combined account for almost 88% of the system by pipe length. Roughly 4% of the system consists of reinforced concrete pipe (RCP), less than 2% is of unidentified material, and the remaining 6% is of various other pipe materials.

ATTACHMENT 2
Table 2-3. Gravity Mains by Pipe Material 1
Pipe Material Length (ft) Portion of Total Length (%)
Polyvinyl Chloride (PVC) 707,620 53.7
Vitrified Clay (VCP) 450,453 34.2
Reinforced Concrete (RCP) 57,000 4.3
Steel Pipe (SP) 35,732 2.7
Asbestos Cement Pipe (ACP) 11,907 0.9
Acrylonitrile Butadiene Styrene (ABS) 8,009 0.6
Ductile Iron Pipe (DIP) 7,324 0.6
Cast Iron Pipe (CIP) 6,280 0.5
Unknown Material 22,149 1.7
Other / Unknown 11,321 0.9
Total 1,317,795 100
Note:
1 Data summarized from the City of Manteca’s GIS sanitary sewer line shapefile (wwConveyance.shp), March 2022. Excludes pipes designated as inactive or abandoned.

The installation years of gravity mains are summarized in Table 2-4 and presented on Figure 2-4.

According to the GIS database, approximately 14% of the system was constructed between 1951 and 1975, 29% was constructed between 1976 to 2000, and 40% of the system was constructed after the year 2000 or within the last 22 years. Data on installation year is limited for sewers constructed prior to 1951, the earliest installation year listed as 1906. Less than 1% of the system is identified as being constructed between 1906 and 1925 and approximately 17% of the system has an unknown installation year.

Table 2-4. Gravity Mains by Installation Year 1
Installation Year Age (Years) Length (ft) Portion of Total Length (%) 1906 to 1925 117 – 98 6,829 0.5
1926 to 1950 97 – 73 0 0.0
1951 to 1975 72 – 48 185,417 14.1
1976 to 2000 47 – 23 377,714 28.7
2001 to present 22 – 0 530,002 40.2
Unknown Unknown 217,833 16.5
Total 1,317,795 100
Note:
1 Data summarized from the City of Manteca’s GIS sanitary sewer line shapefile (wwConveyance.shp), March 2022. Excludes pipes designated as inactive or abandoned.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Lift Station
City Owned
Privately Owned
Water Quality Control Facility Structures
Wastewater Sewer Diameter (inches)
0" - 8"
9" - 12"
13" - 18"
19" - 24"
25" - 36"
37" - 60"
City of Manteca Limit
2-2
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Existing Sewer Collection System
Pipe Size
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Lift Station
City Owned
Privately Owned
Water Quality Control Facility Structures
Waterwater Sewer Material
Polyvinyl Chloride (PVC)
Vitrified Clay (VCP)
Reinforced Concrete (RCP)
Steel Pipe (SP)
Asbestos Cement Pipe (ACP)
Acrylonitrile Butadiene Styrene (ABS)
Ductile Iron Pipe (DIP)
Cast Iron Pipe (CIP)
Other Materials
Unknown
City of Manteca Limit
2-3
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Existing Sewer Collection System
Pipe Material
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Lift Station
City Owned
Privately Owned
Water Quality Control Facility Structures
Wastewater Sewer Installation Year*
Unknown
1906 - 1925
1951 - 1975
1976 - 2000
2001 - 2020
City of Manteca Limit
2-4
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Existing Sewer Collection System
Installation Year
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

ATTACHMENT 2

2.1.3 Force Mains
The existing collection system contains approximately 22 miles of active force mains ranging from 3-inch diameter to 24-inch diameter. Force main pipe diameters by pipe length are summarized in Table 2-5.

Approximately 50% of force mains in the system are 12-inches in diameter, and 26% are 6-inches in diameter.

Table 2-5. Force Mains by Diameter 1
Pipe Diameter (in) Length (ft) Portion of Total Length (%) 3 563 0.5
4 993 0.9
6 30,226 26.3
8 8,440 7.4
12 57,817 50.4
18 5,467 4.8
24 10,848 9.4
Unknown 450 0.4
Total 114,804 100
Note:
1 Data summarized from the City of Manteca’s GIS sanitary sewer line shapefile (wwConveyance.shp), March 2022.

Excludes pipes designated as inactive or abandoned.

Approximately 83% of force mains are listed as having PVC pipe material by length, 4% are asbestoscement pipe (ACP) material, 3% are high-density polyethylene (HDPE) pipe material, and 10% are of unknown material.

The installation year of collection system force mains are largely unknown based on the City’s GIS data.

Only 5% of force mains listed has being installed between 2016 and 2018, one pipe segment is listed as being installed in 2003, and the remaining 95% of active force mains have unknown installation years.

Sewer system force mains are shown on Figure 2-5 in addition to pump stations and lift stations in the collection system.

2.1.4 Pump and Lift Stations
Pump stations and force mains in the collection system from the City’s GIS database are shown on Figure 2-5 and the service area of each station is shown in Figure 2-6. The City’s GIS database includes 18 private and 21 city owned stations. One station was listed as abandoned and one was listed as being a wastewater flushing station. Limited data was available in the database. Therefore, key pump station information was taken from the City’s SSMP, record drawings, discussions with City staff, and other available resources. A summary of data collected for the 18 major wastewater pump and lift stations is shown as Table 2-6.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Antigua
Bella Vista
Chadwick U5
Curran Grove
Eckert
Fishback
Roberts
Estates
Tara Park
Union Road
Villa Ticino
Woodbridge
Park
Woodward Park
Northgate
Park
Frito Lay
Garden Gate
N. Union Rd
& Lathrop
MUSD
Centerpoint
Evans
Solera
Woodward &
Galleria
Shadowbrook
Park Assieh
Developments
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Sanitary Network
Water Quality Control Facility Structures
Lift Station Status
Active
Unmodeled
Inactive
Abandoned
City of Manteca Limit
2-5
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Existing Sewer Collection System
Pump Stations,Lift Stations, & Forcemains
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Antigua
Bella Vista
Chadwick U5
Curran Grove
Eckert
Fishback
Roberts
Estates
Tara Park
Union Road
Villa Ticino
Woodbridge
Park
Woodward Park
Northgate
Park
Frito Lay
Garden Gate
N. Union Rd
& Lathrop
MUSD
Centerpoint
Evans
Solera
Woodward &
Galleria
Shadowbrook
Park Assieh
Developments
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality Control
Facility
Forcemain
Sanitary Network
Water Quality Control
Facility Structures
Lift Station Status
Active
Unmodeled
Inactive
Abandoned
City of Manteca Limit
Lift Station Basin
Chadwick U5
Curran Grove
Evans
Fishback
Gravity
Private
Roberts Estates
Shadowbrook Park
Union Road
Villa Ticino
Woodbridge Park
Woodward Park
2-6
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Lift Stations Service Areas
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

3. Background: San Joaquin County GIS/Planning, California State Parks, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, USDA, Merced County Association of Gov, Esri, HERE, Garmin, FAO, NOAA, USGS, EPA, Esri, USGS
0 0.5 1
Miles
"($ $
¯ (At original document size of 11x17)
1:45,000
ATTACHMENT 2
Table 2-6. Wastewater Pump and Lift Stations
Lift Station Asset ID
No. of
Pumps Horsepower Design Flow
Design
Head
Firm Capacity
(2)
Activity
Status
QTY HP Gpm ft Mgal/d
Woodbridge
Park WWC-WW01 2, (4 future) 30.00 1,450 50.00 2.09 Active Chadwick
Unit 5 WWC-WW02 2 10.00 875 24.00 1.26 Active
Northgate
Park (1) WWC-WW03 1 Small sump pump and septic tank Active Villa Ticino WWC-WW04 2 7.50 510 23.00 0.73 Active
Fishback WWC-WW05 2 3.00 100 - 203 14.00 0.29 Active
Union Road WWC-WW06 3 50 hp x 2
25 hp x1
7,000 x 2
3,500
19 19 15.12 Active
Curran Grove WWC-WW09 2 3.00 140 18.00 0.20 Active
Roberts
Estates WWC-WW11 2 3.00 200 13.00 0.29 Active
Eckert Cold
Storage (1) WWC-WW12 2 20.00 750 51.00 1.08
Active/
Industrial
Discharge
Line
Frito Lay WWC-WW13 2 3.00 200 48.00 0.29 Inactive
Shadowbrook
Park WWC-WW21 2 10.00 812 32.90 1.17 Active
Bella Vista WWC-WW14 2 20.00 600 58.00 0.86 Inactive
Tara Park WWC-WW15 2, (3
future) 25.00 Temporary Lift Station Inactive
Antigua WWC-WW16 2 10.00 193 53.00 0.28 Inactive
Woodward &
Galleria WWC-WW18 1 10.00 500 15.00 0.72 Inactive
Evans
Estates WWC-WW19 2 25.00 729 87.10 1.05 Active
Solera WWC-WW20 2 10.00 220.00 66.00 0.32 Inactive
Woodward
Park WWC-WW17 2 10.00 590.00 38.00 0.85 Active
Notes:
1 Lift station, collection system, and/or service area is too small to be included in the hydraulic model. 2 Reliable capacity is defined as the maximum pumping capacity of the lift or pump station with the largest pump out of service.

ATTACHMENT 2

2.1.5 WQCF Headworks and Influent Structure
Understanding how flow is discharged from the collection system to the WQCF is important for correctly modeling the outfall conditions of collection system. There are two main trunks that collect flow from the upstream collection system. The North Trunk Sewer collects flow discharged from the North Shed and the Central Shed with most of the flow from both sheds being discharged through connecting force mains and lift stations. The South Trunk Sewer collects flows conveyed from the South Shed, which also primarily accepted flow from connecting force mains and lift stations although many have been taken offline with recent trunk extensions and improvements. The main collection system trunks are shown in Figure 2-7.

ATTACHMENT 2
J3
J5
205
Ripon
Manteca

YOSEMITE AV
4551000
4551000
-13497000
-13497000
Legend
Active Lift Station
Sanitary Network
Modeled Forcemain
Modeled Sewer
Water Quality Control Facility Structures
North Trunk
South Trunk
City of Manteca Limit
2-7
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Existing Sewer Collection System
Main Trunks and WQCF Discharge
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

3. Background: Esri Community Maps Contributors, San Joaquin County GIS/Planning, San Joaquin County Public Works, California State Parks, © OpenStreetMap, Microsoft, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, US Census Bureau, USDA, Esri, CGIAR, USGS, San Joaquin County GIS/Planning, California State Parks, Esri, HERE, Garmin, SafeGraph, FAO, METI/ NASA, USGS, Bureau of Land Management, EPA, NPS
0 500 1,000
Feet
"($ $
¯ (At original document size of 11x17)
1:7,000
Discharge from North
Shed Forcemains
Fishback
Roberts
Estate
South Trunk
North Trunk
Discharge from Central
Shed Lift Station
ATTACHMENT 2
These two 60-inch trunk sewers discharge directly into the WQCF Influent Pump Station (IPS), which is responsible for screening and pumping all wastewater entering the WQCF. A bottom plan and section of the WQCF Influent Pump Station are shown in Chapter 9.0 on Figure 9-2 and Figure 9-3.

Flows enter the IPS and combine in the influent room from two 60-inch trunk sewers, one from the west (North Trunk Sewer) and one from the south (South Trunk Sewer). Both influent trunk sewers enter the influent room at an elevation of -4.14 ft. Leaving the influent room, the combined flow passes through bar screens and into the IPS wet well. The influent room is separated from bar screens and the IPS wet well by a concrete wall that extends across the top of the flow channels.

2.2 EXISTING SEWER FLOWS
For this WWMP, a flow monitoring study was conducted in the collection system during the period of March 18, 2022, to May 19, 2022. The flow monitoring study provided data used to perform an assessment of dry and wet weather flow conditions throughout the City’s collection system. The flow monitoring study recorded flows using open channel flow monitors at 18 locations throughout the collection system. Historical influent flow data was used in conjunction with population data to establish the flow per capita wastewater statistics.

2.2.1 Wastewater Flow Characterization Definitions
This section describes definitions of the flow components used to characterize wastewater flow in this WWMP. Wastewater collection systems are designed to convey peak wet weather flows (PWWFs).

PWWFs are generally comprised of four elements: base sanitary wastewater flow (BWWF), inflow, groundwater infiltration (GWI), and rainfall dependent infiltration (RDI). Each component is described in more detail below.

2.2.1.1 Base Wastewater Flow (BWWF)
Sanitary flow or base flow is the component of wastewater generated directly by public, residential, commercial, and industrial users. BWWF can also be equated to the average dry weather flow (ADWF) which is the average of total flows measured during typically dry months between July and September of each year.

2.2.1.2 Inflow
Inflow is storm water that is discharged into the sewer system from direct connections. These connections could include private sewer laterals, roof downspouts, yard and area drains, holes in manhole covers, cross-connections from storm drains, or catch basins.

2.2.1.3 Groundwater Infiltration (GWI)
GWI is groundwater that enters the collection system through cracks in sewer pipes and manholes, leaky joints, and damaged sewer lateral connections. GWI tends to vary seasonally depending on groundwater depth in relation to the depth of sewer pipelines. GWI is more significant during the wet season when ATTACHMENT 2
groundwater elevations are higher. GWI is also more significant in sewers built-in low-lying areas near creeks and drainage courses where groundwater elevations may be high due to surface water conditions.

2.2.1.4 Rainfall Dependent Infiltration (RDI)
RDI is stormwater flow that enters the collection system due to precipitation events. Infiltration is an indirect introduction of rainfall into the collection system through cracked sewer pipes, joints, and manhole walls.

2.2.1.5 Diurnal Patterns
A diurnal flow pattern describes the variation in wastewater flow occurring over the course of a full day. In a 24-hour period, wastewater flow varies significantly with maximum flow typically occurring in the morning and early evening. During the flow monitoring study conducted by the City flow was recorded every 15 minutes. This monitoring provided detailed data allowing the City to evaluate these daily patterns throughout its service area. Each area of the City has its own unique pattern, which also varies between weekdays and weekends.

2.2.2 Flow Monitoring Study
Open channel flow monitoring was conducted at eighteen sites from March 18, 2022, to May 19, 2022.

This work was conducted by V&A Consulting Engineers (V&A) and is summarized in a technical report dated August 2022. The flow monitoring report and inflow and infiltration study provided by V&A is included in Appendix B (City of Manteca Sanitary Sewer Flow Monitoring and Inflow/Infiltration Study, August 2022, V&A Consulting Engineers).

The goals of the flow monitoring study included the following:
• Establish the baseline sanitary sewer flows.
• Establish the peak flow condition during rainfall events and estimate the available sewer capacity.
• Quantify inflow and infiltration (I/I) at the applicable flow monitoring sites and develop synthetic I/I hydrographs for a design storm event.

2.2.2.1 Flow Monitoring Sites
A total of 18 flow monitoring sites were used for model development and calibration. To distribute flow within the hydraulic model, flows from flow monitoring sheds in series are estimated by subtracting flow from upstream flow monitoring basins. There are inherent errors introduced when subtracting flow monitors in series due to variations in data quality, and travel time between monitors.

Table 2-7 summarizes the characteristics of the 18 sewer-sheds established for use in this WWMP and the sewer-shed isolation equations used to isolate flow. The locations of these flow monitors are shown on Figure 2-8 and the associated monitoring basins or sewer-sheds are shown on Figure 2-9.

ATTACHMENT 2
Table 2-7. Flow Monitoring Shed Characteristics
Monitoring
Site/
Sewershed
Manhole ID
Pipe
Diameter
(in)
Existing
Area
(Acres)
Service
Area Flow Isolation Equation
1 WWMH1266 12 207 North = Q1
2 WWMH2281 15 150 North = Q2
3 WWMH0348 15 892 Central = Q3
4 WWMH2372 18 646 South = Q4 – Q9
5 WWMH3748 18 427 South = Q5
6 WWMH0389 21 416 Central = Q6
7 WWMH3097 24 426 Central = Q7
8 WWMH5029 17.5 228 South = Q8
9 WWMH2650 27 290 South = Q9
10 WWMH0551 30 968 Central = Q10 – (Q6 + Q12 + Q18)
11 WWMH3166 30 533 Central = Q11 – Q7
12 WWMH3102 12 228 Central = Q12
13 WWMH3346 30 209 North = Q13
14 WWMH5147 48 992 South = Q14 – (Q8 + Q4)
15 WWMH1227 54 1020 North = Q15 – (Q1 + Q2 + Q3 + Q17 + Q13 + Q10 + Q11) 16 WWMH3117 15 162 South = Q16
17 WWMH3346 40 517 North = Q17
18 WWMH0383 21 749 Central = Q18
ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Site 01
Site 02
Site 03
Site 04
Site 05
Site 06
Site 07
Site 08
Site 10
Site 11
Site 12
Site 13
Site 14
Site 15
Site 16
Site 17
Site 18
Site 09
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Modeled Sanitary Manholes
Water Quality Control Facility
Modeled Lift Station
Other Lift Station
Flow Monitor
Modeled Forcemain
Modeled Sanitary Sewer
City of Manteca Limit
2-8
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/24/2023
TR by MA on 10/24/2023
IR Review by MVD on 10/24/2023
Flow Monitoring Locations and Modeled
Facilities
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-24 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4560000 4557000 4554000 4551000 4548000 4545000
4560000 4557000 4554000 4551000 4548000 4545000
-13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 -13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Lift Station Status
Active
Unmodeled
Inactive
Abandoned
Sanitary Network
Private Sanitary Network
Water Quality Control Facility Structures
City of Lathrop Discharge
Oakwood Shores Collection Boundary
Raymus Village Collection Boundary
City of Lathrop Collection Boundary
Service Area
Central Shed
North Shed
South Shed
City of Manteca Limit
2-1
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Existing Sewer Service Area
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

2.2.2.2 Rainfall Data
V&A analyzed rainfall data from five publicly available weather stations which provided sufficient coverage over the collection system. The cumulative precipitation for the average of the rain gauges was

1.03 inches, equating to approximately 40% of the historical long-term average precipitation over the duration of the study period. There was only one primary rainfall event that occurred over the flow monitoring period (March 27, 2022 – March 28, 2022) which produced 0.72 inches of rain when averaged over the five gauges. A summary of the rainfall data recorded over the flow monitoring period is shown in Table 2-8.

Table 2-8. Summary of Rainfall Data
Rain Gauge Primary Rainfall Event
Precipitation Total (in)
Flow Monitoring Period
Precipitation Total (in)
NW 0.71 1.17
EAST 0.61 0.94
SW 0.55 0.98
SOUTH 0.77 1.06
SE 0.76 1.06
This primary rainfall event was classified as a 1-year to less than 1-year storm event based on the National Oceanic and Atmospheric Association (NOAA) Rainfall Event Classifications.

2.2.2.3 Flow Monitoring Summary and I/I Analysis
V&A provided an analysis of I/I within the collection system. A summary of the results is provided in Table 2-9. V&A differentiated I/I flow from ADWFs to determine which components of I/I were more prevalent in each sewer-shed. After separating flow components, the I/I analysis metrics were normalized for an “apples-to-apples” comparison of each flow monitoring shed. Flows were normalized per-ADWF and peracre).

Based on the data collected during the study, four of the flow monitoring sites were significantly impacted by upstream and downstream lift stations in the collection system, these sites included:

Site 4 (Woodward Park), Site 5 (Frito Lay & Curran Grove), Site 13 (Centerpoint & Woodbridge Park), and Site 14 (Evans & Woodward Park). These sites, as well as Site 15 were excluded from I/I analysis. Site 15 was found to show very little I/I response because most of the peak I/I response originated from upstream basins.

Basins 1, 2, 8, 12, 16, and 17 showed a negligible amount of combined I/I and were ranked lowest for combined I/I. Basins 6, 7, and 18 had the highest weighted, normalized peak I/I rates which is an indicator of high inflow, with 7 being the highest.

Basins 7, 10, and 9 had the highest weighted, normalized combined I/I rates, indicating high combined I/I.

No evidence of GWI was found in any basin.

ATTACHMENT 2
Table 2-9. V&A Flow Monitoring and I/I Analysis Summary Monitoring
Basin ADWF (Mgal/d) Peak Inflow Rate (Mgal/d)
Combined I/I
(gallons)
Overall Inflow
Rank
Overall
Combined I/I
Rank
1 0.124 0.041 Negligible 9 8
2 0.093 0.033 Negligible 8 8
3 0.253 0.262 30,500 5 5
4 0.241 n/a n/a n/a n/a
5 0.048 n/a n/a n/a n/a
6 0.145 0.223 34,700 2 4
7 0.155 0.476 58,900 1 1
8 0.094 0.028 Negligible 12 8
9 0.326 0.187 49,400 4 3
10 0.849 0.297 138,500 6 2
11 0.372 0.053 11,700 13 7
12 0.110 0.036 Negligible 10 8
13 0.002 n/a n/a n/a n/a
14 0.599 n/a n/a n/a n/a
15 0.563 n/a n/a n/a n/a
16 0.092 0.029 Negligible 10 8
17 0.232 0.143 Negligible 6 8
18 0.396 0.365 34,700 3 6
Note:
1 Highlighted cells indicate where data exceeds typical values or high normalized GWI, inflow, RDI, and total I/I flows were identified, (i.e., Inflow/RDI/Total I/I Rankings = 1, 2, or 3). Additional information can be found in the V&A report (Appendix B).

Key:

I/I = inflow and infiltration
Mgal/d = million gallons per day
n/a = not applicable
V&A = V&A Consulting Engineers, Inc.

2.2.3 Dry Weather Flows
Average dry weather flows were established from the flow monitoring study during dry days when I/I had the least impact on the baseline flow. Table 2-10 summarizes dry weather flow data measured during the study as well as the observed sedimentation during the site visit. The flow metering sites use areavelocity technology that measures flow depth, flow velocity, and flow rate in 15-minute intervals. The measurement of both depth and velocity allows for an assessment of whether the sewer is flowing unimpeded, or whether backwater conditions exist.

ATTACHMENT 2
Table 2-10. V&A ADWF Summary
Monitored
Site
Sediment
(in)
Average d/D
Ratio (1)
Mon-Thu
ADWF
(Mgal/d)
Friday
ADWF
(Mgal/d)
Saturday
ADWF
(Mgal/d)
Sunday
ADWF
(Mgal/d)
Overall
ADWF
(Mgal/d)
Site 1 none 0.09 0.121 0.124 0.126 0.137 0.124
Site 2 none 0.10 0.091 0.089 0.095 0.100 0.093
Site 3 none 0.05 0.253 0.251 0.255 0.251 0.253
Site 4 none 0.04 0.606 0.606 0.624 0.651 0.615
Site 5 none 0.05 0.049 0.051 0.044 0.044 0.048
Site 6 none 0.06 0.136 0.154 0.159 0.160 0.145
Site 7 none 0.05 0.157 0.154 0.151 0.153 0.155
Site 8 none 0.06 0.092 0.091 0.097 0.107 0.094
Site 9 0.5 0.03 0.377 0.364 0.353 0.391 0.374
Site 10 none 0.07 1.481 1.466 1.521 1.593 1.501
Site 11 5 0.02 0.524 0.511 0.532 0.552 0.527
Site 12 none 0.12 0.109 0.106 0.109 0.117 0.110
Site 13 none 0.00 0.003 0.002 0.002 0.002 0.002
Site 14 none 0.02 1.286 1.264 1.335 1.413 1.308
Site 15 none 0.02 3.291 3.221 3.386 3.290 3.294
Site 16 none 0.04 0.087 0.088 0.105 0.105 0.092
Site 17 none 0.03 0.229 0.235 0.238 0.238 0.232
Site 18 none 0.05 0.388 0.387 0.407 0.425 0.396
System n/a n/a 4.664 4.574 4.826 4.807 4.695
Note:
1 The d/D ratio is the measured depth of flow (d) divided by the pipe diameter (D).

Key:

ADWF = average dry weather flow
d/D = depth over diameter ratio
Mgal/d = million gallons per day
V&A = V&A Consulting Engineers, Inc.

2.2.4 Wet-Weather Flows
Peak measured flows and flow depth can indicate the capacity limitations of a pipeline. While standards for peaking factors (calculated as ratio of peak flow to ADWF) vary, the Water Environment Federation Manual of Practice FD-6 and American Society of Civil engineers Manual No. 62 suggest typical peaking factor ratios range between 3.0 and 4.0, with higher values possibly indicating pronounced I/I flows. Table 2-11 summarizes the peak recorded flows, levels, d/D ratios, peaking factors, and surcharge depth per site during the flow monitoring period. For the purposes of this WWMP, peaking factors over 5.0 are highlighted orange, respectively, as shown in Table 2-11.

ATTACHMENT 2
Table 2-11. V&A PWWF Summary
Monitoring
Site
ADWF
(Mgal/d)
Peak
Measured
Flow
(Mgal/d)
Peaking
Factor
Pipe
Diameter,
D (in)
Peak
Measured
Depth, d (in)
Max
d/D
Ratio
Surcharge
Above Pipe
Crown (ft)
Site 1 0.12 0.31 2.5 12 18.1 1.51 0.51
Site 2 0.09 0.33 3.5 15 18.2 1.21 0.27
Site 3 0.25 0.48 1.9 15 9.2 0.62 -
Site 4 0.61 2.60 4.2 18 32.6 1.81 1.22
Site 5 0.05 0.17 3.7 18 3.0 0.17 -
Site 6 0.15 2.06 14.2 21 8.1 0.39 -
Site 7 0.16 0.58 3.7 24 4.6 0.19 -
Site 8 0.09 0.21 2.2 17.5 3.4 0.19 -
Site 9 0.37 0.97 2.6 27 9.3 0.34 -
Site 10 1.50 5.33 3.6 30 42.7 1.42 1.06
Site 11 0.53 2.33 4.4 30 80.1 2.67 4.17
Site 12 0.11 0.44 4.0 12 4.4 0.37 -
Site 13 0.002 0.20 84.2 30 2.9 0.10 -
Site 14 1.31 2.24 1.7 48 18.2 0.38 -
Site 15 3.29 6.11 1.9 54 30.6 0.57 -
Site 16 0.09 0.31 3.3 15 5.6 0.37 -
Site 17 0.23 1.03 4.5 40 10.1 0.25 -
Site 18 0.40 0.79 2.0 21 8.2 0.39 -
Key:

ADWF = average dry weather flow
d/D = depth over Diameter Ratio
Mgal/d = million gallons per day
PWWF = peak wet weather flow
V&A = V&A Consulting Engineers, Inc.

The following capacity analysis results are noted:
• Sites 6 and 13 had peaking factors over 5.
o Site 6 peak level, velocity, and flow occurred prior to a rainfall event, perhaps due to an industrial sewer release. It occurred only once during the flow monitoring period of over 2 months, and probably does not need further investigation. Flow, velocity, and depth graphs of the event are shown in the V&A Report as Figure 3-10. o The peaking factor of Site 13 may be skewed high due to low ADWF numbers. The peak flow event did not occur during a period of rainfall and therefore, isn’t attributed to inflow or infiltration. Site 13 is located downstream of the Centerpoint lift station which conveys mainly industrial discharge. This pump station influence is likely the cause of the large differential between average and peak recorded flows. During the calibration process, further discussed in Chapter 3.0, it was determined that the data collected from Site 13 is unsuitable for model ATTACHMENT 2
calibration. The erratic flow patterns and spikes in the data make it impossible to replicate within the model.
• d/D ratios of sites upstream of lift stations were surcharged during the study. o Sites 1 and 2 are immediately upstream of the Chadwick lift station. o Site 4 is immediately upstream of the Woodward Park lift station. o Sites 10 and 11 are upstream of the Union Road lift station, further upstream than sites referred to above. Site 10 is 2,490 LF upstream of the lift station and Site 11 is 1,040 LF upstream, with the others being less than 400 LF upstream of the respective lift stations. o Site 11 reached a peak surcharge depth of 4.17 ft above the pipe crown. Velocity data for a portion of the period was lost due to sediment covering the sensor and the site was noted as having 5-inches of sediment upon initial flow meter installation. The site was shown to surcharge regularly on nearly a daily basis. This in combination with data collected at Site 10 indicates that the Union Road lift station uses a significant portion of the upstream collection system as part of its operating volume.

2.2.5 Per-Capita Flow Assessment
The City of Manteca has two permanently installed flow meters at the WQCF, one measuring flow from Lathrop and one measuring the total flow discharged from the IPS. Average daily influent flow at the City’s WQCF from January 2016 to January 2023 is presented in Figure 2-10. Flows at the WQCF are further described in Chapter 8.0 of this WWMP.

ATTACHMENT 2
Figure 2-10. City of Manteca Influent Flow Data
The historical wastewater flows combined with United States Census Bureau population data were used to calculate the annual average flow (AAF) per capita for the service area, as tabulated in Table 2-12.

The average per capita AAF discharged to the WQCF is 61 gallons per person per day (gpcd). Note that per capita flow in California typically ranges from 60-85 gpcd. The United States Census Bureau identifies an average household density of approximately 3.19 persons per household, or persons per equivalent dwelling unit (EDU) within the City of Manteca and was used to translate the per capita flow into the unit rate of 195 gpd/EDU.

ATTACHMENT 2
Table 2-12. Historical Per-Capita Wastewater Generation Population Data 1 Flow (Mgal/d) Unit Rate (gpcd)
Year AAF 2 AAF/capita
2016 76,752 4.73 61.6
2017 78,784 4.77 60.6
2018 80,762 4.97 61.5
2019 83,323 5.01 60.1
2020 84,842 5.29 62.4
Averages 4.95 61.2
Calculated Unit Rate Per EDU @ 3.19 people/edu (gpd/EDU) 195 Notes: 1
Population data obtained from the United States Census Bureau. 2 AAF = Average Annual Flow; Key:

AAF = Average Annual Flow
EDU = Equivalent Dwelling Unit
gpcd = Gallons per Capita Day
gpd/EDU = Gallons per Day per EDU
Mgal/d = million gallons per day
ATTACHMENT 2

3.0 HYDRAULIC MODEL DEVELOPMENT AND

CALIBRATION
The purpose of this chapter is to outline details of the sewer collection system model development and calibration. The collection system model only considers the City of Manteca’s collection system. Although the City’s WQCF accepts flows from neighboring jurisdictions, the hydraulic model only simulates the City’s collection system and flows.

This chapter is divided into the following sections:
• Hydraulic Model Approach and Software
• Model Inputs
• Model Structure
• Flow Allocation
• Dry Weather Calibration
• Wet Weather Calibration
• Model Calibration Summary

3.1 HYDRAULIC MODEL APPROACH AND SOFTWARE
The City of Manteca’s hydraulic modeling needs were assessed to help define the software and approach needed in the development of the hydraulic model. The preferred approach was to develop a dynamic model that includes all sewers greater than or equal to 8-inches in diameter within the existing collection system. Smaller diameter force mains and 6-inch diameter gravity mains were also included where necessary to account for flow splits or overflows within the system.

The approach in development of a new hydraulic model included the following:
• Review available hydraulic model software and select a suitable option for this study and future updates to the WWMP.
• Develop the model using the existing GIS data, supplemented with new survey data to update the invert levels and rim elevations of the manholes.
• Assign parcel-based sanitary sewer flows to model manholes based on georeferenced average monthly water meter data, normalized to specific sewer shed flow monitoring data. • Identify dry and wet weather events to use for calibration. • Undertake rainfall dependent inflow and infiltration (RDII) analysis for each of the meter subcatchments.
• Calibrate the model using the collected flow monitoring data.

ATTACHMENT 2

3.1.1 Modeling Software
Commercially available open-channel flow hydraulic modeling software platforms were reviewed for the purpose of efficiently executing the collection system components of this WWMP. This included a highlevel comparative review of the potential software candidate capabilities, licensing requirements, training needs, and costs to select a software best fit for Manteca’s needs. This effort is summarized in Technical Memorandum (TM) No. 1: Hydraulic Model Software Selection, which is included in Appendix C.

Based on the City’s needs, the hydraulic model of the collection system was developed using PCSWMM software by Computational Hydraulics Inc. PCSWMM is a fully dynamic model software package using the EPA SWMM5 engine as its basis.

3.2 MODEL INPUTS
The City maintains a GIS database of its collection system facilities, as described in Chapter 2.0 of this report. During model development, the physical network of sewers, manholes, pump stations, and structures were established based on the City’s GIS database, specifically the physical information contained therein for the existing collection system. This physical network becomes the underlying framework for the model. Therefore, it is crucial that the infrastructure is reviewed for completeness and proper connectivity.

A review of the existing collection system in the GIS database was completed prior to model development which provides quality enhancements to the sanitary GIS data. The data review was undertaken in GIS in both ESRI ArcMap and hydraulic modeling software utilizing built-in PCSWMM analysis tools. Missing and inconsistent data identified in the physical network included manhole inverts and rim elevations, sewer diameters, and slopes. In addition, a review was conducted of the hydraulic continuity and suitability of physical sewer data in terms of profile connectivity.

Pipe and manhole invert elevations from the City’s GIS database do not specify what vertical datum is being used. The City uses the National Geodetic Vertical Datum of 1929 (NGVD 29), although a number of manholes had the following comment attribute field: 'RIM elev. based on 1988 vertical datum'. These rim elevations were assumed to use the National Geodetic Vertical Datum of 1988 (NAVD 88). It was assumed that all other elevations listed in the GIS database are listed in the City’s standard datum.

Comparisons between surveyed rim elevations (NGVD 29) and those indicated as being in the NAVD 88 in City GIS data show a difference of approximately 2.31 feet above the NGVD 29 datum. This correlates well with a conversion rate of -2.37 feet when going from NAVD 88 to NGVD 29 provided by the NOAA Online Vertical Datum Transformation website.

Laser imaging detection and ranging (LIDAR) data was used to fill gaps where rim elevations were missing from the database. A comparison of LIDAR results with those of rim elevation surveys indicates that LIDAR data generally provide a reasonable approximation of actual rim elevations.

A data verification program was developed to obtain missing or inconsistent data in an efficient manner, through the use of drawing review, survey, field verification, and inference. As a final resort data was inferred based on the surrounding network.

ATTACHMENT 2

3.2.1 Geodatabases
The following primary physical asset data was received from the City:
• Manholes – wwManholes.shp
• Pipes – wwConveyance.shp
• Pump Stations – wwStation.shp
• Structures – wwStructures.shp

3.2.1.1 Manholes
The City’s manhole shapefile contains a number of attribute fields used to define physical parameters and provide additional relevant information. Based on the data provided there are 4,672 manholes in the City’s sanitary geodatabase. A summary of the relevant attribute fields for manholes and initial gap assessment is provided in Table 3-1.

Table 3-1. Manhole Data Gap Assessment
Field Name Description Gap Assessment Percent of Total (%) AssetID Unique Identifier No duplicate or blank fields 0 Status Activity Status 31 abandoned, inactive, or other 1 RIM_Elev Rim Elevation 180 blanks 4
Invert_1 Invert Elevation 687 blanks 15
Invert_2 Invert Elevation 1,707 blanks 37
Invert_3 Invert Elevation 3,379 blanks 72
Invert_4 Invert Elevation 4,461 blanks 95
All Invert Fields Invert Elevations 634 blanks 14
Inst_Year Installation Year 401 blanks 9

3.2.1.2 Sewers
The City’s sewer line shapefile contains a number of attribute fields used to define physical parameters and provide additional relevant information. Based on the data provided there are 5,545 sewer pipes in the City’s sanitary geodatabase. A summary of the relevant attribute fields for manholes and initial gap assessment is provided in Table 3-2.

ATTACHMENT 2
Table 3-2. Pipeline Data Gap Assessment
Field Name Description Gap Assessment Percent of Total (%) AssetID Unique Identifier 31 duplicate or blank fields 1 MATERIAL Pipe Material 183 blanks 3
Status Activity Status 82 abandoned or inactive 1
Slope1 Pipe Slope 3,353 blanks 60
DownElev Downstream Elevation 975 blanks 18
UpElev Upstream Elevation 1,026 blanks 19
PipeSize Pipe Size 161 blanks 3
Inst_Year Installation Year 797 blanks 14

3.2.1.3 Lift Stations
There are 39 lift stations in the City’s GIS database. The database is limited to providing the assets physical location, activity status, and ID. It does not include pump station capacity, force main information, or other information necessary for building the model, a summary of additional lift station information is provided in Chapter 2.0. The database also indicates that there are 21 city owned lift stations and 18 private lift stations. One lift station is listed as a flushing station and one is listed as abandoned, although discussions with operators indicated many other lift stations have been abandoned or taken offline.

3.2.1.4 Structures
The structures database includes a total of 580 sewer valves, lamp holes, clean-outs, and plugs. These elements were added to the model as needed to complete the systems physical layout (i.e., added to the end of a line where no manhole existed). In addition to categorizing these elements into type, the structures shapefile also includes the attributes shown in Table 3-3.

Table 3-3. Structures Gap Data Assessment
Structure Type Quantity
Number of Blank GIS Attribute Fields
RIM_Elev Invert_1 Inst_Year PipeSize
Air Release Valve 67 66 65 16 56
Gate Valve 18 18 18 1 0
Plug 33 33 33 33 33
Lamp Hole 412 44 412 147 402
Cleanout Vertical 35 13 16 12 13
Cleanout Horizontal 6 2 6 1 6
Cleanout 9 2 1 0 0
Key:

GIS = Geographic Information Systems

3.2.1.5 GIS Database Summary
Stantec reviewed the City’s GIS database to import upstream, downstream, rim, and invert elevations available in the data set. The majority of invert and rim elevations were available for manholes, where a ATTACHMENT 2
single manhole invert elevation was missing in an alignment, the missing invert was interpolated between the available data upstream and downstream. The remaining gaps in the dataset primarily existed north and south of Yosemite Ave. in what is assumed to be the oldest part of the system. Manhole survey needs within the system were divided into three categories including:
• Primary Survey Needs: Missing manhole invert elevations along primary trunk sewers, those 10- inches and larger. [Total Manholes: 111]
• Secondary Survey Needs: Missing manhole invert elevations in the remaining trunks, along sewers 8-inches in diameter. [Total Manholes: 105]
• Remaining Data Gaps: Missing manhole invert elevations in the remaining system, along sewers less than 8-inches in diameter. [Total Manholes: 257]
An overview of the initial manhole data needs is shown in Figure 3-1, along with where manhole invert elevations that were interpolated. The primary survey needs were those necessary to build and use the hydraulic model, elevations needed to simulate the City’s main trunk network. The primary survey needs existed along the main northern influent trunk, having an alignment running from the WQCF and the Union Road Lift Station as well as the upstream trunks. After providing this information to the City for review, additional record drawings for primary and secondary survey needs were provided. After importing these invert elevations and interpolating additional invert elevations based on the new information, the remaining gaps were limited to 50 manholes that needed to be surveyed.

3.2.2 Record Drawings
Record drawings provided by the City were reviewed to fill in gaps in the GIS database and define physical lift station parameters. Lift station record drawings were provided for the majority of public and private lift stations in the collection system. These drawings were used to identify force main size, discharge elevation, wet-well size, invert and rim elevations, as well as any available pump information including horsepower (HP), pumping capacity, number of pumps, and operating levels. Although a number of lift station drawings were provided, generally the force main records were not included. Record drawings were provided, as noted above, for manholes identified as having missing invert elevations in the City’s GIS database. Record drawings were provided for 96 manholes, resulting in approximately 85 invert elevation gaps filled. In addition to these records the City also provided drawings for the North Manteca Trunk Sewer Project from November 2019. The trunk’s alignment, diameter, and elevations were updated in the GIS database.

3.2.3 Manhole Survey
Stantec subcontracted with F3 & Associates (F3) to conduct a manhole survey of the remaining gaps in the City’s GIS database. Survey is based on North American Datum of 1983 (NAD83)/ California Coordinate System of 1983 (CCS83) horizontal datum and City of Manteca vertical datum (NGVD 29) with ties to physical City of Manteca benchmarks. Of the 50 requested manholes for survey, 11 inverts could not be determined. The City was able to provide rim to invert depth information for surcharged and inaccessible manholes. Surveyed manholes are shown on Figure 3-2 and a complete list of manholes surveyed is included in Appendix D along with the information provided by F3.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality Control Facility
Forcemain
Water Quality Control Facility Structures
Lift Station
City Owned
Privately Owned
Primary Survey Needs
Secondary Survey Needs
Remaining Data Gaps
Interpolated Invert
Sanitary Gravity Sewer (< 6")
Sanitary Trunk (> 6")
City of Manteca Limit
3-1
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Initial Gap Assessment Results
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

E YOSEMITE AV W YOSEMITE AV S MAIN ST
SB
HWY 99
HWY 99
NB

N MAIN ST
4551000
4551000
-13494000
-13494000
Legend
Forcemain
City Owned Lift Station
Surveyed Manhole
Manhole
Sanitary Sewer (< 6")
Sanitary Trunk (> 6")
3-2
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Surveyed Manholes
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

EPA, NPS
0 500 1,000
Feet
"($ $
¯ (At original document size of 11x17)
1:9,500
ATTACHMENT 2

3.3 MODEL STRUCTURE

3.3.1 Manholes
There are a total of 2,132 manholes modeled in the wastewater collection system. This includes some nodes to reflect elevation changes along force mains. Table 3-4 below provides a summary of the node inputs in the model.

Table 3-4. Modeled Manholes Summary
Nodes
Count 2,132
Manhole Invert Range -4.18 feet – 40.43 feet
Manhole Rim Range 15.6 feet – 49.91 feet
Manhole Depth Range 0.93 feet – 31.45 feet
Surcharge Depth (Gravity) 0 feet
Surcharge Depth (Force main) 1,000 feet
Note:

The “Surcharge Depth (Force main)” is an arbitrary model parameter required by the SWMM engine that is applied to the nodes along force mains, to allow the computation of the hydraulic gradeline to rise above the manhole rims in a pressurized system.

3.3.2 Sewers
In general, only sewers 8-inch or larger have been modeled with some exceptions of 6-inch sewers where needed to account for connectivity. There are a total of 2,103 gravity sewer segments included in the model, with diameters ranging from 6-inch to 60-inch. Table 3-5 below provides a summary of the gravity sewer input in the model.

ATTACHMENT 2
Table 3-5. Modeled Sewers Summary
Diameter
(in)
Material (ft)

ABS ACP CI CIP DIP PVC PVC
LINED PVS RCP S SP SP/CIP SS VCP VCP/ABS VCP/CIP Unknown Total (ft) 6 2,041 8,171 4,377 1,764 16,353
8 3,598 4,990 212 1,156 1,834 139,218 403 165 17,482 142 714 108,638 220 912 1,867 281,551 10 994 1,444 172 38,844 750 219 34,975 28 77,413
12 29,953 1,122 419 1,504 27,422 414 60,834
15 80 16,598 1,556 13,568 769 32,571
18 6,272 227 11,006 8 17,513
21 400 3,338 751 266 4,222 8,977
24 1,751 2,570 8,818 13,139
27 1,100 1,100
30 481 12,215 4,587 17,283
36 4,601 13,687 260 18,548
42 364 5,413 5,777
48 5,119 5,119
54 142 4,092 4,234
60 2,670 988 3,658
Total (ft) 6,633 6,514 384 1,156 1,834 241,688 364 403 39,888 419 19,956 142 980 232,400 220 912 10,189 564,082 ATTACHMENT 2
As shown, 564,000 feet of gravity sewers are included in the model (approximately 43% of all sewers).

After importing the City’s GIS layers into the model, the geometry was evaluated for connectivity and continuity errors. Flow tracing tools were used to verify and correct network connectivity and flow direction. The sewer profile tool was used to inspect continuity of sewers and manholes attributes such as diameters, inverts, and rim elevations. Interpolation had to be used to fill gaps in known invert elevations, but generally will provide an adequate representation of the system.

3.3.3 Lift Stations & Force Mains
There is a total of 10 City owned lift stations included in the model. Seven private lift stations are modeled however the capacities are unknown and therefore are included for connectivity purposes only. Any inflows to the private lift stations are passed directly to the gravity system and will need to be confirmed.

Table 3-6 below provides a summary of the force mains included in the model.

Table 3-6. Modeled Force Mains Summary
Diameter (in)
Material
AC PVC Unknown Grand Total (ft)
6 12,349 12,349
8 4,643 3,644 8,287
12 18,788 2,959 21,747
24 10,693 10,693
Total (ft) 4,643 34,781 13,652 53,076
Key:

AC = Asbestos Cement
PVC = Polyvinyl Chloride

3.3.4 Boundary Conditions
No external boundary conditions have been included in the model. Flow data available at the WQCF includes additional inflows from Lathrop as well as recycle flows from the WQCF internal processes.

These flows must be subtracted from the metered flows at the WQCF to provide flows from the upstream collection system only. The true influent flow was determined by subtracting the in plant recycle flows from the WQCF flow data provided. In plant recycle flows were calculated as approximately 12 percent of the WQCF flow provided. To get the true City of Manteca flow, flow from Lathrop was subtracted from the calculated true influent flow. Flow from Lathrop was estimated as 16 percent of the true influent flow.

Additional discussion of plant influent flows is included in Chapter 8.0 of this report.

ATTACHMENT 2

3.4 FLOW ALLOCATION
Flow monitoring was performed to provide data from specific locations within the collection system for use in calibration of the hydraulic model. Using a flow data from throughout the collection system for calibration allows the actual distribution of dry weather flows (DWF) to be assessed and provides information needed to develop a system specific distribution of wet-weather flow.

This section describes how flows are assigned to the appropriate nodes within the collection system model. Flow inputs are assumed to originate at a parcel level. Parcels were assigned to modeled manholes based on proximity and associated water meter billing records.

3.4.1 Sanitary Loading
Average sanitary load for all property connections, or water meter connections within each subsewershed were aggregated and loaded to the closest modeled manhole associated with the upstream connected properties. The manholes or sanitary load points for each sub-sewershed are identified based on the manhole location and engineering judgement. The upstream sub-sewersheds are loaded to the most upstream sanitary manhole to avoid empty pipes in the model. Each manhole within a subsewershed upstream of a flow meter was assigned the same diurnal pattern generated using the observed flow meter data.

Sanitary flow loadings for base wastewater flow (BWWF) were developed based on 2021 winter water meter billing records and flow recorded during the flow monitoring study. The City provided water usage data from 2016 to 2021 for address points within the City of Manteca. The total water use of parcels assigned to the same strategic manhole node in the model were determined. These totals were used to distribute the percentage of sewer flow recorded at each of the sewer system flow monitoring locations.

This formed the initial sanitary BWWF for each property connection. This approach was selected over monitored collection system flow meter allocation by area as it kept the difference in water use observed between users correlating it to sewer system discharge.

The dry weather flow analysis also includes determination of the individual groundwater infiltration (GWI) component for assessing the impact of GWI on the system conveyance capacity. This is accomplished by identifying the minimum nightly monitored flow for a day, usually occurring during the early morning hours. In residential areas, the experience indicates that about 10 to 20 percent of this minimum nightly flow is attributable to wastewater, with the remaining flow to GWI. GWI was estimated as 80 percent of the minimum nighttime flow and was distributed to manholes proportionally based on contributing area. A number of sanitary sewer hydraulic modeling resources cite GWI as approximately 80 to 90 percent of minimum nighttime flows.

ATTACHMENT 2

3.5 DRY WEATHER CALIBRATION
One of the most important steps of the hydraulic modeling effort is the calibration of the model. Adequate calibration establishes the level of confidence in the predictive capabilities of a hydraulic model. Model calibration is the adjustment of parameters in a hydraulic model so that modeled flows correlate with observed (metered) flows within an acceptable range.

3.5.1 Criteria for Dry Weather Flow Calibration
The criteria used for assessing the accuracy of the dry weather flow calibration are taken from the Chartered Institution of Water and Environmental Management (CIWEM) guidelines, which are summarized below:
• The volume of the modeled verses metered flow should be in the range of ±10%. • The modeled versus metered peak flow rate should be in the range of ±10%. • The modeled versus metered peak flow depth should be in the range of ±0.5 feet.

In general, for this analysis, the above criteria are viewed as objectives rather than as inviolable standards. If one or more of these criteria are not met, any such deviation is viewed in terms of whether the model maintains acceptable accuracy while remaining adequately conservative in its predictive capabilities using engineering judgement. Velocity data is also considered during the calibration process.

3.5.2 Diurnal Pattern Development
Data recorded from rain gauges were used to identify dry weather days suitable for calibration. If rainfall was not recorded at all rain gauges during and for 48 hours prior to that day, it was identified as a dry weather day. Dry weather flow periods observed in the data were identified for the eighteen flow meters in the service area. The average flow per timestep for all weekdays and weekends in each of these dry weather periods was calculated to generate hydrographs for weekday and weekend flow.

Diurnal patterns for weekdays and weekend days were generated for each flow monitoring basin using the observed flow meter data corresponding to DWF periods observed during the study. These derived patterns were further adjusted to account for travel time during the dry weather flow calibration process. If the resultant model diurnal curve has a time lag (due to the effect of long travel times), a time offset is applied to the input curve to achieve better agreement between the meter and modeled diurnal flow patterns. Similarly, if the resultant model diurnal curve is flattened (due to the effect of flow attenuation), an exponential “amplification factor” is applied to the input curve to achieve better agreement between the metered and modeled results.

Note that each diurnal pattern represents the characteristics of the contributing service area i.e., residential, or commercial or industrial flow patterns. The contributing area for most of the Manteca meters was predominantly residential and the diurnal pattern behavior reflected the service area as shown in Figure 3-3.

ATTACHMENT 2
Figure 3-3. Residential – Diurnal Flow Pattern at Flow Meter Site 1 Exceptions were made for flow metering areas in which the observed diurnal flow pattern was significantly distorted by upstream or downstream pump operations (specifically meters 4, 5, 13, and 14). Based on the observed data, flow spikes due to pump operations (pump failure, wet-well back-ups, etc.) were omitted by through the review of graphed meter data over time and the diurnal curve was smoothed out to match the predominate pattern in the data observed. An example of flow spikes and pump station influence and the resulting diurnal pattern is shown in Figure 3-4.

ATTACHMENT 2
Figure 3-4. Pump Station Influence – Diurnal Flow Pattern at Flow Meter Site 4 The metered versus modeled diurnal flow patterns for all 18 flow monitoring sites and for the WQCF are presented in Appendix F. In general, very close agreement was achieved between the modeled and metered diurnal patterns. Notable disparities include the following:
• Site 4 as shown above.
• Site 5 shows significant pump station influence that is not replicated in the model. This results in significant flattening of the diurnal pattern.
• Site 11 shows significant pump station influence. It appears that the Union Road PS downstream of Site 11 experiences temporary flow disruption resulting in variability in the DWF pattern. This was verified through discussion with City staff.
• Site 13 show significant pump station influence that is not replicated in the model. This results in significant flattening of the inconsistent diurnal pattern. As previously discussed, data from Site 13 was considered unsuitable for model calibration purposes. • Additional pump station influence is observed in other flow meter sites however not to the same degree as those listed above.

Pump Station Influence
ATTACHMENT 2

3.5.3 Flow Calibration
The flow monitoring study positioned one flow meter along each of the City’s primary influent trunk sewers, the north trunk (Site 15), and the south trunk (Site 14). The sum of these meters and Site 16 provides a more accurate measure of to the true influent flow from the City of Manteca alone than data collected from the WQCF influent flow meter, which includes flow from the City of Lathrop and recycled flows from treatment operations. Therefore, the flow monitoring study data was used as the primary data for dry weather calibration.

The model calibration process began by calibrating the most upstream flow meters in the collection system and working downstream. Base flow data and sewer attributes were modified, within reasonable ranges, until there was less than a 10% difference between modeled average flow and measured average flow at each flow monitoring location. The adjustment process continued downstream and was repeated until the model reached an acceptable level of calibration with respect to the recorded ADWFs.

The model was calibrated to two 7-dry weather day periods (Event 1: April 1, 2022 – April 8, 2022 and Event 2: May 2, 2022 – May 8, 2022).

Modeled versus metered flows are compared to assess the accuracy of the dry weather calibration and to determine where unexplained disparities exist. The 1-hour rolling average of observed data was used for the comparison of peak flows. Modeled versus metered flows for all 18 metering sites are compared for Event 1 in Table 3-7 and Event 2 in Table 3-8.

ATTACHMENT 2
Table 3-7. Flow Calibration Results – Dry Weather Period #1 (4/1/2022 - 4/8/2022) Volume Peak Flow
Goal: -10% to +10% of observed values Goal: -10% to +10% of observed values Observed
(Mgal/d)
Simulated
(Mgal/d)
Error
(%)
Observed
(Mgal/d)
Simulated
(Mgal/d)
Error
(%)
SITE 01 0.13 0.13 1.5 0.22 0.20 -6.9
SITE 02 0.09 0.09 -2.4 0.19 0.16 -15.7
SITE 03 0.24 0.24 4.1 0.41 0.37 -9.6
SITE 04 0.61 0.61 0.4 1.00 0.89 -10.3
SITE 05 0.05 0.05 -0.9 0.11 0.09 -15.3
SITE 06 0.15 0.15 0.1 0.27 0.25 -8.8
SITE 07 0.16 0.16 -0.6 0.26 0.24 -8.4
SITE 08 0.09 0.10 2.9 0.19 0.16 -14.0
SITE 09 0.39 0.38 -1.4 0.64 0.59 -8.4
SITE 10 1.50 1.52 0.9 2.39 2.36 -1.3
SITE 11 0.53 0.53 -1.2 1.05 0.73 -31.0
SITE 12 0.12 0.11 -5.4 0.22 0.18 -18.0
SITE 13 Data from Site 13 could not be used for calibration SITE 14 1.29 1.31 1.0 2.09 1.82 -12.9
SITE 15 3.37 3.39 0.6 5.20 5.07 -2.4
SITE 16 0.10 0.10 -3.0 0.20 0.18 -12.8
SITE 17 0.23 0.23 0.8 0.40 0.40 -0.5
SITE 18 0.40 0.40 0.4 0.65 0.65 0.6
Key:

Mgal/d = Million Gallons per Day
ATTACHMENT 2
Table 3-8. Flow Calibration Results – Dry Weather Period #2 (5/2/2022 - 5/9/2022) Volume Peak Flow
Goal: -10% to +10% of observed values Goal: -10% to +10% of observed values Observed
(Mgal/d)
Simulated
(Mgal/d)
Error
(%)
Observed
(Mgal/d)
Simulated
(Mgal/d)
Error
(%)
SITE 01 0.13 0.13 -2.8 0.23 0.20 -10.8
SITE 02 0.09 0.09 -3.6 0.21 0.16 -25.6
SITE 03 0.26 0.24 -4.7 0.45 0.37 -18.2
SITE 04 0.60 0.61 2.2 1.05 0.89 -15.0
SITE 05 0.05 0.05 -1.7 0.10 0.09 -9.0
SITE 06 0.15 0.15 -3.7 0.27 0.25 -10.1
SITE 07 0.16 0.16 -0.8 0.26 0.24 -10.0
SITE 08 0.09 0.10 5.3 0.17 0.16 -2.1
SITE 09 0.38 0.38 0.1 0.64 0.58 -9.6
SITE 10 1.49 1.52 1.9 2.42 2.35 -3.0
SITE 11 0.53 0.53 -0.7 1.25 0.73 -42.1
SITE 12 0.11 0.11 2.5 0.20 0.18 -11.2
SITE 13 Data from Site 13 could not be used for calibration SITE 14 1.29 1.31 0.9 2.14 1.82 -14.9
SITE 15 3.40 3.39 -0.4 5.38 5.07 -5.9
SITE 16 0.10 0.10 0.5 0.18 0.18 -3.1
SITE 17 0.22 0.23 2.6 0.40 0.40 0.6
SITE 18 0.40 0.40 -1.3 0.68 0.65 -4.3
Key:

Mgal/d = Million Gallons per Day
As shown in the table, modeled versus metered dry weather flow volumes compare very well for all metering sites except Site 13. This demonstrates that the average DWF in the model matches very closely with the metered data. Modeled versus metered peak flows show a larger discrepancy. This is generally due to data outliers, or “flow spikes” that are observed in the data, and daily variation in flow patterns, an example this type of outlier or flow spike is shown in Figure 3-5. All modeled vs metered flow for each site can be found in Appendix F. The modeled flows will be identical for all weekdays (Mon – Fri) and weekends (Sat – Sun), where the metered flow is bound to see variations from day to day. This can also be a result of PS influence which cannot be duplicated in the model. An example of metered versus modeled flow for Site 1 can be seen below in Figure 3-5.

ATTACHMENT 2
Figure 3-5. Metered versus Modeled Flows at Site 1
As shown above, a flow spike on April 2, 2022 results in a peak observed flow of approximately 0.3 Mgal/d as compared to the modeled flow of 0.2 Mgal/d. Taking the hourly rolling average of the 15-minute observed data helps to smooth out these sporadic spikes in the raw data. As shown in the tables, the peak modeled flows are generally within 20 percent of the hourly rolling average of the observed data aside from Site 11 which experienced frequent flow interruption due to operating conditions of the Union Road Lift Station. Visually reviewing graphs of model results and metered data also demonstrates a very close match of the metered versus modeled flows.

3.5.4 Velocity and Depth Calibration
Modeled versus metered velocities and depths are also compared to assess the accuracy of the dry weather calibration and to determine where unexplained disparities exist. There are no CIWEM guidelines for velocity, but a goal of +/- 1.0 fps was established. Peak flow depth was evaluated using the CIWEM guideline of +/- 0.5 feet of observed values. Modeled versus metered velocities and depths for all 18 metering sites are compared for Event 1 in Table 3-9 and Event 2 in Table 3-10.

0.00 0.05

0.10 0.15

0.20 0.25

0.30 0.35
4/1/2022 4/2/2022 4/3/2022 4/4/2022 4/5/2022 4/6/2022 4/7/2022 4/8/2022 Flow (Mgal/d)
Date
Measured Data Rolling Average (Hourly) Flow
Data Outlier/Flow Spike
ATTACHMENT 2
Table 3-9. Depth and Velocity Calibration Results – Dry Weather Period #1 (4/1/2022 - 4/8/2022)
Peak Velocity Peak Depth
Goal: -1 fps to +1 fps of observed values Goal: -0.5 ft to +0.5 ft of observed values Observed
(fps)
Simulated
(fps) Error (fps) Observed (ft) Simulated (ft) Error (ft) SITE 01 1.59 1.38 -0.21 0.38 0.33 -0.06
SITE 02 2.24 1.57 -0.67 0.22 0.23 0.01
SITE 03 1.02 1.40 0.38 0.74 0.46 -0.28
SITE 04 1.60 2.34 0.74 2.22 0.55 -1.66
SITE 05 1.27 0.46 -0.81 0.22 0.35 0.12
SITE 06 1.71 1.24 -0.47 0.30 0.32 0.03
SITE 07 1.74 1.26 -0.48 0.27 0.30 0.03
SITE 08 1.34 1.23 -0.11 0.28 0.26 -0.02
SITE 09 1.11 1.08 -0.03 0.67 0.56 -0.10
SITE 10 2.62 2.23 -0.39 0.98 0.92 -0.06
SITE 11 1.00 1.39 0.39 3.95 0.38 -3.57
SITE 12 1.82 1.31 -0.51 0.30 0.31 0.01
SITE 13 0.59 0.25 -0.34 0.12 0.03 -0.08
SITE 14 1.35 1.27 -0.08 1.03 0.93 -0.10
SITE 15 1.32 1.47 0.15 1.89 1.66 -0.23
SITE 16 1.14 1.02 -0.12 0.46 0.34 -0.13
SITE 17 1.88 1.11 -0.77 0.37 0.38 0.01
SITE 18 1.33 1.30 -0.03 0.64 0.63 -0.01
Key:
fps = feet per second
ATTACHMENT 2
Table 3-10. Depth and Velocity Calibration Results – Dry Weather Period #2 (5/2/2022 - 5/9/2022)
Peak Velocity Peak Depth
Goal: -1 fps to +1 fps of observed values Goal: -0.5 ft to +0.5 ft of observed values Observed
(fps)
Simulated
(fps) Error (fps) Observed (ft) Simulated (ft) Error (ft) SITE 01 1.66 1.38 -0.28 0.38 0.33 -0.06
SITE 02 2.54 1.57 -0.97 0.26 0.23 -0.03
SITE 03 1.22 1.40 0.18 0.62 0.46 -0.17
SITE 04 1.73 2.33 0.60 2.51 0.55 -1.95
SITE 05 1.44 0.46 -0.98 0.22 0.35 0.13
SITE 06 1.81 1.24 -0.57 0.30 0.32 0.02
SITE 07 1.70 1.26 -0.44 0.28 0.30 0.02
SITE 08 1.26 1.23 -0.03 0.28 0.26 -0.02
SITE 09 1.19 1.08 -0.11 0.65 0.56 -0.09
SITE 10 2.63 2.22 -0.41 0.86 0.92 0.05
SITE 11 0.93 1.39 0.46 3.57 0.38 -3.19
SITE 12 1.97 1.31 -0.66 0.27 0.31 0.04
SITE 13 1.30 0.25 -1.05 0.24 0.03 -0.21
SITE 14 1.36 1.27 -0.09 1.06 0.93 -0.13
SITE 15 1.32 1.47 0.15 1.91 1.66 -0.25
SITE 16 0.96 1.02 0.06 0.41 0.34 -0.08
SITE 17 1.83 1.11 -0.72 0.29 0.38 0.08
SITE 18 1.34 1.30 -0.04 0.66 0.63 -0.03
Key:
fps = feet per second
As shown in the tables, modeled versus metered depths and velocities vary significantly across the sites.

Sites that fall outside of the calibration goals are heavily influenced by pump stations in the system that control velocity and flow depth in the metered sewers. Pump station influence creates spikes or noise in the data which will result in larger mismatch of metered vs modeled results. This is why the flows are used as the primary means of calibration for DWF. Based on the results of the metered vs modeled comparisons and CIWEM guidelines, the calibration was deemed sufficient for this analysis using best engineering judgement.

Of note, recorded data for Site 13 appears to be unsuitable for calibration. The data shows very high pump influence, and the modeled flow is very low for a 30-inch sewer therefore confidence in the precision of the measured values would be difficult to achieve. Site 13 shows significant pump station influence that cannot not be replicated in the model.

ATTACHMENT 2

3.6 WET WEATHER CALIBRATION
As described in Chapter 2.0 of this report, the most significant storm event that occurred during the flow monitoring period was on March 27, 2022 – March 28, 2022 and produced 0.72 inches of rain when averaged over the five gauges. This storm event provided the basis for initial wet weather flow (WWF) calibration of the collection system model. The results of this calibration were validated using influent flow data from the WQCF collected during larger more recent storm events.

Based on the results presented below, the model is calibrated to a degree adequate to provide basis for sound collection system capacity analysis and planning. It should be understood, however, that the collection system response to major storm events may be highly variable, based on factors such as total event rainfall, peak storm intensity, antecedent rainfall, and possibly other factors. It is therefore appropriate in collection system planning to use an adequately conservative design storm condition.

3.6.1 Methodology
The analysis makes use of the RTK method for wet-weather calibration of the PCSWMM model. The RTK parameters are defined as follows:
• R: The portion of total rainfall within the tributary area that enters the collection system in the form of I/I.
• T: The time from the onset of rainfall to the peak of the I/I response. • K: The ratio of the time to recession to the time to peak of the hydrograph, where the time to recession is defined as the time from the peak to the point in time where there is no longer any appreciable I/I response.

The RTK parameters are derived for each flow monitoring basin identified in the flow monitoring study.

The resultant RTK parameters established through calibration are then applied to the collection system model using the 10-year, 24-hour design storm for both existing and buildout development conditions.

The 10-year, 24-hour design storm is further described in Section 4.1. RTK values for future development areas are conservatively approximated from those developed in the wet weather calibration process.

3.6.2 Criteria for Wet-Weather Flow Calibration
The criteria used for assessing the accuracy of the wet weather flow calibration are taken from CIWEM guidelines noted for dry weather calibration and are summarized below:
• The modeled versus metered peak flow rate should be in the range of -15% to +25%. • The volume of the modeled versus metered flow during and following the calibration of the storm should be in the range of -10% to +20%.
• The modeled versus metered flow non-surcharged depth should be in the range of ± 0.5 feet.

ATTACHMENT 2
• The modeled versus metered flow of surcharge should be in the range of -0.5 feet to +1.6 feet.

As with the dry weather calibration, these criteria should be viewed as objectives rather than as inviolable standards. If one or more of these criteria is not met, any such deviation should be viewed in terms of whether the model is adequately conservative in its predictive capabilities. Of the above criteria, agreement between modeled and metered peak flows and volumes are considered the most important criteria, given that peak flows and volumes are what define the sizing needs of the existing and future collection system and treatment facilities.

3.6.3 Rainfall Event Analysis
As previously discussed, only one primary rainfall event occurred during the flow monitoring period. This event is used as the primary event for model calibration. To validate the calibration, rainfall data from the California Irrigation Management Information System (CIMIS) was downloaded to evaluate more recent and severe rainfall events in conjunction with influent flow data from WQCF. Between December 2022 and January 2023, 12.11 inches of rain fell in Manteca based on data from CIMIS Station 70. This amount of rainfall over 60-days is considered to have a return frequency of between 1 in 25-years (11.5 inches) and 1 in 50-years (12.4-inches) based on the NOAA point precipitation frequency atlas. Several storm events during this period had a significant impact on influent flows observed at the WQCF. The hourly rainfall and influent flow data for this period is shown in Figure 3-6.

Figure 3-6. Rainfall and WQCF Influent Data
ATTACHMENT 2
The most significant influent flow response and corresponding rainfall event occurred between December 29, 2022, and January 1, 2023, where 3.29-inches of rain was recorded at the CIMIS 70 station. During this event hourly influent flow peaked at approximately 16.3 Mgal/d. This event was classified as approximately 20-year, 3-day event, and a 20-year, 24-hour event based on the NOAA frequency atlas.

The bulk of this rainfall fell during a 12-hour period starting at 6am on December 31, 2023, where 1.99 inches of rain was recorded. This was classified as a 30-year, 12-hour event based on NOAA frequency atlas.

Rainfall events used for model calibration and validation are summarized in Table 3-11.

Table 3-11. Rainfall Calibration and Validation Events
Rainfall
Event Duration Total Rainfall (in) 24-hour Return Frequency Peak
Influent
Flow
(Mgal/d)
Data Source
1 Start: 3/27/2022 22:00
End: 3/28/2022 14:30
Duration: 16.5 hours
NW: 0.71
EAST: 0.61
SW: 0.55
SOUTH: 0.77
SE: 0.76
Overall: 0.72
<1-year 8.1 V&A Report
2 Start: 12/29/2022 1:00
End: 12/31/2022 22:00
Duration: 70 hours
12-hour: 1.99
24-hour: 2.49
Overall: 3.29
~20-year 16.3 CIMIS 70 -
Manteca
3 Start: 01/14/2023 2:00
End: 01/16/2023 08:00
Duration: 54 hours
12-hour: 1.36
24-hour: 1.51
Overall: 2.24
~2-year 12.3 CIMIS 70 –
Manteca
Key:

CIMIS = California Irrigation Management Information System Mgal/d = Million Gallons per Day
NW = Northwest Rain Gauge
SE = Southeast Rain Gauge
SW = Southwest Rain Gauge
V&A = V&A Consulting Engineers, Inc.

3.6.4 Flow Calibration
Modeled versus metered flows are compared to assess the accuracy of wet weather flow calibration and to determine where unexplained disparities exist. As already noted, the March 2022 event was used to perform the initial calibration, which was then verified against the more significant rainfall events from December 2022 and January 2023. Upon review of the modeled response against the observed influent data at the WQCF, the calibration from the March 2022 event did not provide a representative response in the collection system as observed in the rainfall events in December and January. It was determined that the model should be recalibrated to using the more severe rainfall. This provided a challenge in terms of calibration as there is no flow meter data to use as a basis of comparison other than the influent data at the WQCF. However, our team felt it important to establish model parameters that would result in a similar response in the model at the WQCF as was observed in the influent data.

ATTACHMENT 2
In order to calibrate the model with the lack of flow meter data during the same time period, the proportion of flows observed in the flow meters relative to the total flow at the WQCF during the initial calibration to the March 2022 rainfall, were used as a basis of comparison.

This ratio was calculated as follows:

Site Target Flow Proportion = Site Qmax / WQCF Qmax
The modeled peak flows for each meter site versus the modeled influent flow for the initial March 2022 calibration are compared in Table 3-12.

Graphical comparisons of modeled versus metered calibration data are presented in Appendix F.

Table 3-12. Flow Calibration Results – Wet Weather Period #1 (3/27/2022 - 3/28/2022)

Peak Flow (Mgal/d)
Observed (Including Upstream
Basins)
% of
Total
Observed (Upstream Basins
Removed)
% of
Total
SITE 01 0.201 2.8% 0.201 2.8%
SITE 02 0.156 2.2% 0.156 2.2%
SITE 03 0.402 5.6% 0.402 5.6%
SITE 04 0.922 12.9% 0.345 4.8%
SITE 05 0.102 1.4% 0.102 1.4%
SITE 06 0.268 3.8% 0.268 3.8%
SITE 07 0.576 8.1% 0.576 8.1%
SITE 08 0.162 2.3% 0.162 2.3%
SITE 09 0.577 8.1% 0.577 8.1%
SITE 10 2.363 33.2% 1.271 17.9%
SITE 11 0.848 11.9% 0.272 3.8%
SITE 12 0.178 2.5% 0.178 2.5%
SITE 13 0.05 0.7% 0.05 0.7%
SITE 14 1.833 25.7% 0.749 10.5%
SITE 15 5.037 70.7% 0.615 8.6%
SITE 16 0.176 2.5% 0.176 2.5%
SITE 17 0.402 5.6% 0.402 5.6%
SITE 18 0.646 9.1% 0.646 9.1%
WQCF 7.12 100.0% 7.12 100.0%
The values presented above for the % of Total were the targets used to calibrate the model to the observed influent data for December 2022 and January 2023. The model parameters were adjusted until the modeled flows at the WQCF closely matched those observed in the influent data. The modeled peak ATTACHMENT 2
flows for each meter site versus the modeled influent flow for the December 2022 and January 2023 rainfall calibration are compared in Table 3-13.

Table 3-13. Flow Calibration Results – Wet Weather Period #2 (12/26/2022 - 1/16/2023)

Peak Flow (Mgal/d)
Observed (Including Upstream
Basins)
% of
Total
Observed (Upstream Basins
Removed)
% of
Total
SITE 01 0.716 4.3% 0.716 4.3%
SITE 02 0.453 2.7% 0.453 2.7%
SITE 03 1.113 6.7% 1.113 6.7%
SITE 04 1.51 9.0% -0.164 -1.0%
SITE 05 0.424 2.5% 0.424 2.5%
SITE 06 0.892 5.3% 0.892 5.3%
SITE 07 1.364 8.2% 1.364 8.2%
SITE 08 0.623 3.7% 0.623 3.7%
SITE 09 1.674 10.0% 1.674 10.0%
SITE 10 6.234 37.3% 3.092 18.5%
SITE 11 2.82 16.9% 1.456 8.7%
SITE 12 0.461 2.8% 0.461 2.8%
SITE 13 0.05 0.3% 0.05 0.3%
SITE 14 2.665 15.9% 0.532 3.2%
SITE 15 13.359 79.9% 0.77 4.6%
SITE 16 0.48 2.9% 0.48 2.9%
SITE 17 1.203 7.2% 1.203 7.2%
SITE 18 1.789 10.7% 1.789 10.7%
WQCF 16.721 100.0% 16.721 100.0%
A comparison of the modeled influent hydrograph versus the measured influent flow for the Wet Weather Period #2 is shown in Figure 3-7.

ATTACHMENT 2
Figure 3-7. Modeled Versus Observed WQCF Influent Flow Data ATTACHMENT 2
As shown on Table 3-12 and Table 3-13, the calibration leads to generally higher flow proportion than was observed with the initial calibration. It is preferrable to have a conservative result given the limited data available for calibration. As shown on Figure 3-7 above, the modeled flows match the pattern and generally the timing of the peak flows observed at the WQCF. The model overestimates the peak flows, however this provides a conservative result and given the limited data with which to calibrate, it is preferrable to have a conservative result. A summary of the peak flows and volumes for the WWF period above is shown on Table 3-14 below.

Table 3-14. WQCF Influent Flow Calibration Results – Wet Weather Period #2 (12/26/2022 - 1/16/2023)
Date
Peak Flow (Mgal/d) Volume (Mgal)
Modeled Observed Error (%) Modeled Observed Error (%)
12/26/2022 - 12/27/2022 13.15 11.95 10.0% 12.25 13.5 -9.3% 12/29/2022 - 12/31/2022 17.67 16.29 8.5% 23.92 22.74 5.2% 01/04/2023 - 01/05/2023 9.72 9.98 -2.6% 12.75 14.61 -12.7% 01/09/2023 - 01/12/2023 14.36 12.07 19.0% 20.82 19.68 5.8% 01/14/2023 - 01/17/2023 14.07 12.27 14.7% 23.6 22.3 5.8% 12/26/2022 - 01/17/2023 17.67 16.29 8.5% 147.6 152.3 -3.1% As shown, the model peak flows are within the range of -15% to +25% and the volume is within the range of -10% to +20% noted in Section 3.6.2.

3.6.5 Velocity and Depth Calibration
Modeled versus metered velocities and depths are also compared to assess the accuracy of the wet weather calibration and to determine where unexplained disparities exist. Modeled versus metered velocities and depths for all 18 metering sites are compared for Event 1, however since the model was recalibrated for the second wet weather period and velocity and depth data was unavailable for comparison, this step could not be carried out.

3.7 MODEL CALIBRATION SUMMARY
The model was calibrated for DWF and compared to metered results for two different periods: April 1, 2022 – April 8, 2022, and May 2, 2022 – May 9, 2022. The model results showed good correlation with the shape and timing of the flow observed at most metering sites, other than those impacted by strong pump station influence as discussed in section 3.5. The modeled volumes for DFW were all within 10% of the metered volumes. The modeled peak flows showed a larger variation from the metered flows however this is due to inconsistencies in the daily flows, and spikes in the data. The DWF calibration is deemed sufficient for the analysis.

The model was initially calibrated for WWF for a single event on March 27, 2022 – March 28, 2022. This calibration was verified against additional rainfall and influent flow data from December 1, 2022 – ATTACHMENT 2
February 1, 2023. It was determined that the model needed to be recalibrated for the larger rainfall events as the response in the model from the initial calibration was not within an acceptable error tolerance.

Meter data was not available for the same time period for the recalibration; therefore an alternate approach was employed to attempt to match the proportion of flows observed at each meter site as compared to the influent flow at the WQCF. The calibrated model showed a strong correlation to the flows observed at the WQCF for the second WWF period of December 26, 2022 – January 16, 2023. The model generally over-estimates the peak flows observed, however the peak flows and volumes are within the error ranges noted in Section 3.6.2. The WWF calibration is deemed sufficient for the analysis. Level of service results for the calibrated WWF model can be seen on Figure 3-8 through 3-11.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Modeled Sanitary Manholes
Water Quality Control Facility
Modeled Lift Station
Other Lift Station
Modeled Forcemain
Peak Flow (Mgal/d)
<= 0.5 Mgal/d
> 0.5 Mgal/d - 1.0 Mgal/d
> 1.0 Mgal/d - 2.0 Mgal/d
> 2.0 Mgal/d - 5.0 Mgal/d
> 5.0 Mgal/d
City of Manteca Limit
3-8
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Calibration Event: WWF - Peak Sewer Flow
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Modeled Sanitary Manholes
Water Quality Control Facility
Modeled Lift Station
Other Lift Station
Modeled Forcemain
Peak Pipe Utilization (% of FPC)
<= 50%
> 50% - 75%
> 75% - 50%
> 100%
City of Manteca Limit
3-9
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Calibration Event: WWF - Peak Pipe
Utilization (% of FPC)
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Modeled Sanitary Manholes
Water Quality Control Facility
Modeled Lift Station
Other Lift Station
Modeled Forcemain
Residual Capacity
No Residual Capacity
< 0.0 Mgal/d - 0.5 Mgal/d
< 0.5 Mgal/d - 2.0 Mgal/d
< 2.0 Mgal/d - 5.0 Mgal/d
< 5.0 Mgal/d
City of Manteca Limit
3-10
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Calibration Event: WWF - Residual
Capacity
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Water Quality Control Facility
Modeled Lift Station
Other Lift Station
Modeled Forcemain
Modeled Sanitary Sewer
Manhole Freeboard (ft)
<= 2 ft
> 2 ft - 6 ft
> 6 ft - 10 ft
> 10 ft
City of Manteca Limit
3-11
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Calibration Event: WWF - Manhole
Surcharging (Depth Below Rim)
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

4.0 BASIS FOR COLLECTION SYSTEM ANALYSIS
The purpose of this chapter is to present planning, design, and performance criteria applicable to the City’s wastewater collection system. These criteria are relevant to the analysis of the existing system, as well as the assessment of future capacity needs. Planning and growth assumptions for evaluation of the system at future levels of development is also presented. The criteria presented in this chapter serve as the basis for the recommended capital improvement program (CIP) presented later in this report.

This chapter is divided into the following sections:
• Design Criteria
• Future Growth Assumptions

4.1 DESIGN CRITERIA
The criteria presented in this chapter are considered adjunct to the existing City Standards and Specifications and are not intended to replace or supersede those standards unless specifically stated otherwise. The City should consider revising their peaking factor standards based on monitored flows.

The City Standards exist as Standard Specifications and Drawings for the sewer, storm drain, water and street utilities and infrastructure. The City’s Standards can be found in Appendix E of this report.

The Standard Specifications for sewers address pipe materials, maintenance holes, trenching and construction related topics. The Standards Drawings include various drawings related to pipe and maintenance hole construction, as well as system criteria such as pipe slope, diameter, velocity, and Manning’s “n” for pipe sizing.

The City of Manteca design criteria require that wastewater sewer system design shall be in conformance with the City of Manteca’s current Wastewater Sewer System Master Plan on Drawing No. S-2. This drawing presents sanitary sewer design data including the following various system criteria:
• Dry weather flow factors for various land use categories • Calculations of flow peaking factors and I/I rates
• Design flow calculations

4.1.1 Wastewater Generation Factors for General Plan Land Use As described in previous chapter, winter water meter demands, and data collected during the flow monitoring period serve as the basis for developing existing ADWF throughout the City. Land-use based wastewater generation factors (WGF) are used to establish ADWF estimates for future development.

Based on review of existing development trends within Manteca and the City’s General Plan, it was determined that approximately 80-percent of the gross area contributes to wastewater flow generation, leaving 20-percent for rights-of-way and open spaces. Therefore, the net area, equal to 80-pecent of the ATTACHMENT 2
gross total area, was used to estimate wastewater flow from future development areas using the WGFs presented below. This net to gross area ratio was determined by reviewing areas of the existing system that are already fully developed or considered built out.

Presented in Chapter 2.0 is a per-capita flow assessment that identifies that the average per-capita flow in the existing system is approximately 61 gpcd. This unit rate was used to derive the WGFs by land use category by considering the City’s average household density and the development densities presented in the General Plan for each land use designation. According to the US Census data from 2017 to 2021, the average household or equivalent dwelling unit (EDU) density in the City of Manteca is approximately

3.2 persons per EDU, resulting in an approximate wastewater unit rate of 195 gpd/EDU.

The land use-based WGFs presented in the City’s 2012 Master Plan were reviewed and updated based on proposed changes to the City’s General Plan and the updated WGFs presented above. The General Plan EDU densities presented in the 2012 Master Plan, and those in the 2023 General Plan are summarized in Table 4-1. The midpoint of each density range is used in both the 2012 Master Plan and this WWMP update, aside from very low density where 2 EDU/acre is used in the 2012 Master Plan.

Table 4-1. General Plan Residential Density Update
Residential Land Use
Category
2012 General Plan Density
(EDU/acre)
2023 General Plan Density
(EDU/acre)
Very Low Density 0 to 2 0 to 2
Low Density 2.1 to 8 2.1 to 8
Medium Density 8.1 to 15 8.1 to 20
High Density 15.1 to 25 20.1 to 30
Key:

EDU = Equivalent Dwelling Unit
The 2012 Master Plan used lower WGFs for future development to reflect water conservation legislation that was upcoming at the time. Assumptions for existing development were 265 gpd/EDU for very low to low density residential and 189 gpd/EDU for medium and high density residential. Assumptions for future development were 160 gpd/EDU for very low to low density residential and 117 gpd/EDU for medium and high density residential. Unlike the 2012 Master Plan, this report uses the calculated historical per-capita unit rate (195 gpd/EDU) consistently for each future residential land use designation.

The results of the update to WGFs are presented in Table 4-2. The higher density ranges in the updated General Plan and a fixed data-based unit rate result in a higher WGF for low, medium, and high density residential land uses.

No adjustments were made to non-residential land use designation WGFs. Neighborhood commercial and urban reserve land use designations are no longer used in the updated General Plan, and downtown, agricultural industrial, and business professional were added. The WGF of downtown development was equated to that used for commercial mixed use. Agricultural industrial was equated to industrial land use and business professional was equated to general commercial land use. The WGF of parks was reduced from 400 gpd/acre to 100 gpd/acre to better reflect typically observed values. Parks typically have very ATTACHMENT 2
low to no wastewater generation component because they generally consist of open space and the majority of water use is attributed to irrigation. This is seen when comparing seasonal water use records.

Table 4-2. Wastewater Generation Factors (WGF)
Land Use 2012 Master Plan (gpd/acre) 2023 Master Plan (gpd/acre) Residential – New Development
Very Low Density Residential 320 195
Low Density Residential 808 985
Medium Density Residential 1,346 2,740
High Density Residential 2,337 4,885
Other – Existing and New Development
Commercial Mixed Use 2,473 2,473
General Commercial 750 750
Heavy Industrial 1,000 1,000
Light Industrial 1,000 1,000
Public/Quasi-Public 425 425
Park 400 100
Agriculture 0 0
Open Space 0 0
Neighborhood Commercial 1,120 NA
Business Industrial Park 1,200 1,200
Urban Reserve 320 NA
Downtown New Designations 2,473
Agricultural Industrial New Designations 1,000
Business Professional New Designations 750
Water New Designations 0
ROW New Designations 0
Note:

NA = not appliable, land use designation no longer included in General Plan.

Key:
gpd = gallons per day

4.1.2 Design Storm
The existing City Standards describe how to perform design flow calculations for collection system facilities. The design standards do not address flow modeling methodologies and assumptions related to the simulation of PWWFs in the collection system. After establishing ADWF conditions based on existing flow monitoring data and projecting future conditions with WGFs, the hydraulic model is used to apply a diurnal flow pattern to the ADWF and then the I/I resulting from a simulated severe storm event is superimposed on the dry weather flow pattern.

PWWFs simulated in the hydraulic model are used to evaluate the LOS of the collection system and provide recommendations for future servicing and improvement strategies. These computational models ATTACHMENT 2
use simulated design rainfall events representing a reasonable worst-case condition. For purposes of this WWMP, PWWFs in the collection system were evaluated using a 10-year, 24-hour design storm with a Huff distribution (distributing rainfall by hour) shown in Figure 4-1. According to the NOAA Rainfall Frequency Atlas a 10-year, 24-hour storm in the City of Manteca has a rainfall total of approximately 2.20 inches.

Figure 4-1. 10-year, 24-hour Design Storm
It is expected that for existing development conditions, the modeled 10-year, 24-hour design storm should produce peak flows at the WQCF that are consistent with historical results. Calibrated unit hydrographs from the existing system model were used to determine flows within the existing sewer service areas.

The 18 calibrated unit hydrographs were averaged to create a single hydrograph which was used to simulate peak flows outside of the existing service area and within the future system planning areas.

4.1.3 Target Level of Service (LOS)
The level of service (LOS) is based on the capacity in the collection system and the risk of surcharging that may result in service connection flooding. Surcharging occurs when flow exceeds the open channel flow capacity of a gravity flow pipeline, which causes the water level in manholes to begin rising above the adjacent pipe crown elevation. Under surcharged conditions, the pipe flows under pressure and can carry additional flow. Gravity sewers are generally designed to flow partially or full without surcharging.

However, short periods of surcharging can be accommodated within certain limits without justifying the cost of upsizing an existing pipeline. Such limits are described in Table 4-3 which summarizes the criteria for dry and wet weather flow analyses.

ATTACHMENT 2
Table 4-3. Allowable Surcharge Criteria
Criteria Dry Weather Flow Analysis Wet Weather Flow Analysis Target Level of Service
(LOS)
• Ratio of maximum depth
• versus full depth (d/D) < 0.8 • When the rim elevation is less than or equal to 8-feet above the pipe crown:

Ratio of maximum depth versus full depth
(d/D) < 1.0, no surcharging allowed.
• When the rim elevation is more than 8-feet
above the pipe crown: Ratio of maximum
depth versus full depth (d/D) = 1.0 is
allowable, with a maximum surcharge
depth of 1-foot above the pipe crown.

For dry weather flow (DWF) analysis, the ratio of maximum depth versus full depth (d/D) of the sewer shall be used to identify capacity constraints, as it is more representative of system capacity for a dynamic model. Based on industry best practices, any sewers with a d/D equal to or greater than 0.8 (80%) shall be identified as having capacity constraints under dry weather conditions.

For wet weather flow (WWF) events, surcharging (d/D of greater than 1) is considered acceptable provided the water level remains at least 8-feet below ground elevation. Freeboard in a manhole is defined as the distance between the rim elevation and the hydraulic grade line (HGL). Surcharging occurs when the HGL exceeds the pipe crown elevation. The maximum allowable surcharge in the gravity portion of the existing collection system is 1-foot. Manholes in the existing system must also maintain at least 8 feet of freeboard during a design storm event.

The following collection system capacity assessment criteria are used in this WWMP:
• Gravity mains are considered undersized if they do not meet the criteria presented in Table 4-3. • Pump stations are considered undersized if the associated firm capacity (capacity with largest pump out of service) is not sufficient at modeled PWWF conditions. • Force mains are considered under sized if the maximum velocity exceeds 8 feet per second (fps) at modeled PWWF conditions.

4.2 FUTURE GROWTH ASSUMPTIONS
The purpose of this section is to present the assumptions used in developing the future system model.

4.2.1 Future Study Area and Servicing Strategy
The study area considered in this WWMP encompasses the planning areas to which the City of Manteca will provide sewer service and ultimately be responsible for operating and maintaining under buildout development conditions. This is considered all areas covered by the City’s General Plan. The 2012 Master Plan presents recommended improvements in the following categories the North Manteca Collection Strategy (NMCS), South Manteca Collection Strategy (SMCS), and Central Manteca Collection Strategy (CMCS). Like the 2012 Master Plan, this WWMP Update evaluates the collection system needs of these three major service areas or sewer-sheds described in Chapter 2.0 of this report. A summary of ATTACHMENT 2
the areas of each service area within each boundary of the City’s General Plan are summarized in Table 4-4. The boundaries of the Central Shed, North Shed, and South Shed are shown on Figure 4-2.

Table 4-4. Collection System Service Areas and General Plan Boundaries Service Area Existing
(Acres)
City Limits
Infill (Acres) SOI (Acres)
Remaining
General Plan
(Acres)
Total (Acres)
North Shed 1,166 773 2,783 5,590 10,312
Central Shed 3,365 681 36 0 4,083
South Shed 1,990 3,647 3,435 845 9,917
Total 6,522 5,101 6,254 6,434 24,311
This strategy assumes that future development flows outside of the existing City Limits boundary and sewer service area will be routed through their respective systems. For example, future flow originating from within the North Shed boundary should flow through the North Trunk system down Airport Way to the WQCF, while flows from within the Central Shed boundary should pass through the Union Road lift station and Central trunk network, and flow originating from the South Shed area should be routed through the South Trunk that follows Woodward Avenue.

The 2012 Master Plan recommended an overall trunk sewer strategy consisting of a combination trunk sewer gravity collection system with pump or lift stations located along the alignment to convey wastewater to an influent pump station located at the WQCF. Prior to development of the 2012 Master Plan, the 2006 Master Plan recommended three deep large diameter sewers to collect wastewater from the north, central, and south sections of the City for conveyance to an influent pump station located at the WQCF. This strategy of deep gravity trunk sewers was consistent with earlier master plans.

Based on the review of the existing collection system it appears that the City has alternated between these two collection system strategies: 1) The 2012 strategy including a shallower collection system with a number of interim and permanent lift or pump stations; and 2) The 2006 strategy including deeper trunk sewers minimizing the overall need lift or pump stations. This WWMP re-evaluates a deeper trunk strategy to eliminate pump and lift stations within the system using the new hydraulic model and highresolution LIDAR surface elevation data. The development of the servicing strategy for future areas prioritized gravity sewers over lift stations and forcemains to the extent deemed feasible for this WWMP.

Lift stations and forcemains were identified in recommended improvements when the depth of gravity sewers exceeded approximately 25-feet.

ATTACHMENT 2
C ali fo rni a
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San Francisco
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Service Area
Central Shed
North Shed
South Shed
Existing Service Area
City Limits
Sphere of Influence
Remaining Planning Area
4-2
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/17/2023
TR by MA on 10/17/2023
IR Review by MVD on 10/17/2023
Service Area Collection Strategies
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-17 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

4.2.2 Population Projections
The City of Manteca had a population of 85,792 people in 2021 according to US Census Bureau.

Population projections from the City’s General Plan indicate a build out population of 211,003 people. The City’s Municipal Services Review (MSR) dated July 2022 cites the City’s 2020 population estimated at 84,800 by the California Department of Finance and the latest population projections for Manteca are 134,248 people by 2035. The MSR projects an additional population of 64,773 people within City Limits at buildout. The MSR defines the SOI as the 10 and 30-year planning horizon providing population growth of up to 74,475 people. The remaining General Plan area, referred to as the Area of Interest (AOI) would provide population growth of an additional 12,415 people. A summary of the MSR population projections is shown in Table 4-5.

Table 4-5. MSR Population Projections
Area Acres Added Population Total Population
2020 Existing City Area 11,583 - 84,800
Within City Limits 64,773 149,573
10-Year Planning Horizon 5,630 56,184 205,757
30-Year Planning Horizon 2,685 18,291 224,048
Area of Interest (Remaining General Plan) 4,506 12,415 236,463 Total 24,404
Key:

MSR = Manteca Municipal Services Review (July 2022)

4.2.3 Design Horizons
This WWMP assessed system performance for existing level of development conditions as well as the following projected growth scenarios for the City of Manteca’s wastewater collection system.

Scenario 1 – Existing Conditions Model
This modeled scenario simulates flow in the existing collection system during a 10-year, 24-hour design storm event. This model was constructed using the calibrated wet weather flow model and applying a 10- year, 24-hour rainfall event. The results of this simulation evaluate the existing collection system under ADWF and PWWF conditions.

Scenario 2 – Buildout of City Limits
This scenario simulates PWWF in the future collection system upon development of infill areas within the existing city limits. The majority of infill development is in the South Shed.

Scenario 3 – Buildout of the SOI Boundary
This scenario simulates PWWF in the future collection system upon development of the SOI that lies outside City Limits, as shown in Figure 4-2. The majority of SOI development is in the North Shed and South Shed.

ATTACHMENT 2
Scenario 4 – Full General Plan Buildout
This scenario simulates PWWF in the future collection system upon development of the remaining general plan development area. The majority of the remaining general plan development area is in the North Shed.

General Plan land use information for future development areas serve as the basis to estimate future wastewater flow evaluated in this WWMP. A summary of the land use areas for each scenario is provided as Table 4-6.

Table 4-6. Design Horizon General Plan Land Use
General Plan Land Use Gross Area (Acres)
Planning Horizons Scenario 1 Scenario 2 Scenario 3 Scenario 4 Total
Description Existing Infill SOI Remaining GP
Agricultural Industrial 0 0 0 232 232
Agriculture 0 118 724 3,162 4,004
Business Industrial Park 23 79 145 349 597
Business Professional 22 17 33 10 83
Commercial 501 452 192 56 1,202
Commercial Mixed Use 118 457 84 0 659
Downtown 157 3 0 0 160
High Density Residential 204 151 79 55 489
Industrial 581 444 399 1,532 2,956
Low Density Residential 4,016 1,724 2,794 470 9,004
Medium Density Residential 270 241 143 53 707
Open Space 0 370 97 8 475
Park 66 497 153 26 742
Public/Quasi-Public 526 450 332 67 1,375
Right of Way 8 82 75 14 179
Very Low Density Residential 28 15 823 400 1,267
Water 0 0 180 0 180
Total: 6,522 5,101 6,254 6,434 24,311
Key:

GP = General Plan
SOI = Sphere of Influence
The ADWF flow is calculated using the net area (80-percent of the gross area) and the WGFs from Table 4-2. Residential land uses use the mid-point of the general plan development densities to first calculate the projected number of EDUs for each parcel, rounding to the nearest EDU and a unit rate of 195 gpd/EDU to determine the projected ADWF. The resulting ADWF projections for each scenario are summarized in Table 4-7.

ATTACHMENT 2
Table 4-7. Design Horizon Flow Projections
Scenario Area (Acres) ADWF (Mgal/d) Total ADWF (Mgal/d) 1 – Existing 6,522 4.79 4.79
2 – City Limits 5,101 4.09 8.88
3 – SOI 6,254 3.84 12.72
4 – Full General Plan 6,434 2.57 15.29
Total: 24,311 15.29
Key:

Mgal/d = Million Gallons per Day
ATTACHMENT 2

5.0 COLLECTION SYSTEM CAPACITY EVALUATION
The purpose of this chapter is to present the results of the Manteca wastewater collection system model, evaluate the system’s ability to meet the LOS performance criteria under existing and future development conditions, and present recommended system improvements to address existing deficiencies and serve future development.

The results of each level of development scenario are evaluated using the LOS performance criteria described in Chapter 4.0. The primary criterion used in the evaluation is surcharge depth, with a maximum allowable surcharge of 1-foot above the pipe crown in manholes with sufficient depth.

Manholes in the existing system must maintain at least 8 feet of freeboard during a design storm event.

The model results are used to evaluate system capacity, hydraulic performance, identify system deficiencies, and develop recommended improvements. These recommended improvements are summarized in a prioritized CIP for the collection system which includes an estimate of probable costs.

This chapter is divided into the following sections:
• Modeled Design Horizon Scenarios
• Scenario 1 – Existing Development Results
• Scenarios 2 to 4 – Future Growth Analysis
• Phasing Strategies and Potential Alternatives
• Conceptual Opinion of Probable Cost
• Recommended Projects and Costs (Table 5-12)

5.1 MODELED DESIGN HORIZON SCENARIOS
This Wastewater Master Plan (WWMP) assessed collection system level of service and capacity under four different scenarios described in Section 4.2 of this report. Each scenario represents the cumulative development of growth areas within the General Plan. Simulated scenarios are summarized in Table 5-1.

The results of Scenario 1 – Existing Conditions are detailed in Section 5.2 and the results for Scenarios 2 to 4, which simulate future levels of development, are discussed in Section 5.3 of this chapter. Future development areas and the associated scenario in which they are added is presented in Figure 5-1.

Table 5-1. Summary of Modeled Scenarios
Scenario Description Cumulative Planning Areas ADWF
(Mgal/d)
Simulated Peak
Flow 1 (Mgal/d)
Scenario 1 Existing Conditions • Existing Service Area 4.79 18.6 Scenario 2 Buildout of City Limits • Vacant Areas within City Limits 8.88 31.0 Scenario 3 Buildout of SOI • SOI Planning Areas 12.72 42.2 Scenario 4 Buildout of General Plan • Remaining Planning Area 15.29 48.6 Note:
1 Unattenuated flow, peak flow with recommended improvements.

ATTACHMENT 2
C ali fo rni a
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-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Modeled Sanitary Manholes
Lift Station Status
Active
Unmodeled
Inactive
Abandoned
Water Quality Control Facility
City of Manteca Limit
Modeled Sanitary Sewer
Forcemain
Water Quality Control Facility Structures
Private Sanitary Network
City of Manteca Limit
Scenario 1 - Existing Service Area
Scenario 2 - City Limits
Scenario 3 - Sphere of Influence
Scenario 4 - Remaining Planning Area
5-1
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/24/2023
TR by MA on 10/24/2023
IR Review by MVD on 10/24/2023
Modeled Scenario Planning Areas
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-24 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

5.2 SCENARIO 1 – EXISTING DEVELOPMENT RESULTS
Scenario 1 simulates flow in the existing collection system during a 10-year, 24-hour design storm event.

The results of this simulation evaluate the existing collection system under ADWF and PWWF conditions.

The results of the existing collection system model simulations and LOS evaluations are presented below.

5.2.1 Dry Weather Flows
The dry weather flow model simulates an ADWF of approximately 4.7 Mgal/d, with a diurnal peak flow of

7.1 Mgal/d. Dry weather flows simulated at each flow metering location are presented in Section 3.5 of this report. Surcharging is not predicted to occur in the existing system under dry weather conditions as a result of gravity sewer capacity. As noted for the flow monitoring study, lift stations in the system cause surcharging to occur as a result of operating conditions.

For dry weather flow (DWF) analysis, the ratio of maximum depth versus full depth (d/D) of the sewer is used to identify capacity constraints, as it is more representative of system capacity for a dynamic model.

Based on industry best practices, any sewers with a d/D equal to or greater than 0.8 (80%) shall be identified as having capacity constraints under dry weather conditions. The majority of sewers in the system have a d/D ratio of less than 0.8 under dry weather conditions, with the exception of sags and mismatched pipe crowns in the system.

5.2.2 Peak Flows and Residual Capacity
Model results for existing conditions at the WQCF and at the eighteen collection system flow monitoring sites are summarized in Table 5-2. The table shows:
• Modeled ADWF
• Modeled PWWF from the calibration storm event (December 2022), • Modeled PWWF from the 10-year, 24-hour design storm described in Chapter 3.0. • Peaking factors are shown in the last two columns for the calibration storm and 10-year, 24-hour design storm. The PWWF peaking factor is defined as the PWWF divided by the ADWF.

ATTACHMENT 2
Table 5-2. Summary of Modeled Scenarios
Modeled Flows (Mgal/d) PWWF Peaking Factor
ADWF Calibration
PWWF
10-year, 24-hour
PWWF
Calibration
PWWF
10-year, 24-hour
PWWF
Site 1 0.127 0.72 0.80 5.6 6.3
Site 2 0.091 0.45 0.49 5.0 5.4
Site 3 0.244 1.11 1.07 4.6 4.4
Site 4 0.616 1.51 1.85 2.5 3.0
Site 5 0.046 0.42 0.35 9.2 7.6
Site 6 0.149 0.89 0.84 6.0 5.6
Site 7 0.156 1.36 1.30 8.7 8.4
Site 8 0.096 0.62 0.60 6.5 6.2
Site 9 0.381 1.67 1.57 4.4 4.1
Site 10 1.519 6.23 6.14 4.1 4.0
Site 11 0.529 2.82 2.54 5.3 4.8
Site 12 0.110 0.46 0.44 4.2 4.0
Site 13 0.001 0.05 0.03 50.0 34.0
Site 14 1.301 2.67 3.35 2.0 2.6
Site 15 3.391 13.36 13.55 3.9 4.0
Site 16 0.097 0.48 0.47 4.9 4.8
Site 17 0.230 1.20 1.16 5.2 5.1
Site 18 0.399 1.79 1.75 4.5 4.4
WQCF 4.796 16.72 17.63 3.5 3.7
As shown in Table 5-2, the model predicts a peak flow of 17.6 Mgal/d at the WQCF for the 10-year, 24- hour design storm. The peaking factor associated with this result is 3.7. Sixteen of the flow metering locations indicate peaking factors above the overall WQCF peaking factor, and two meters indicate peaking factors below the WQCF value. In general, there is little variance between the peaking factors simulated in the calibration event and those simulated under the 10-year, 24-hour design storm.

Residual pipe capacity is defined as the remaining capacity in a sewer under peak flow conditions or the calculated full pipe capacity (FPC) subtracted by the peak simulated flow. The residual system capacity under 10-year, 24-hour design storm conditions is shown on Figure 5-2. The figure color codes pipeline capacity as follows:
• Red lines indicate that there is no residual capacity remaining. These lines are flowing either at or over their FPC. Those over capacity are further discussed in the following sections. • Orange lines indicate that there is less than 0.5 Mgal/d of capacity available. • Yellow lines indicate that there is 0.5 to 2.0 Mgal/d of capacity available. • Green lines indicate that there is 2.0 to 5.0 Mgal/d of capacity available.

ATTACHMENT 2
• Blue lines indicate that there is more than 5.0 Mgal/d of capacity available.

Below is a summary of residual capacity notes:
• Areas without any residual capacity (shown in red on Figure 5-2) primarily exist in the Central Shed, apart from:
o the 12-inch sewer upstream of the Chadwick Unit 5 pump station in Hastings Drive between S. Airport Way and N. Landreth Lane which also does not have any residual capacity. • Areas of the Central Shed without residual capacity include the pipelines described below. These pipelines are shown as red lines in Figure 5-2:
o 15-inch sewer in Center Street from the Union Road lift station to Elm Avenue, o 10-inch sewer upstream in Elm Avenue and W. North Street, o 8-inch sewer in W. North Street between Charles and Cottage Avenue, o 15-inch sewer in Garden Gate Drive between Edison and Jason Street, o 8-inch sewer in Oregon Street between Sequoia and Park Avenue.

Other individual shallow sloped segments within the Central Shed also have no residual capacity as shown on Figure 5-2.

ATTACHMENT 2
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MAIN ST

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Modeled Sanitary Manholes
Modeled Lift Station
Other Lift Station
Water Quality Control Facility
Water Quality Control Facility Structures
Forcemain
Residual Capacity
No Residual Capacity
< 0.0 Mgal/d - 0.5 Mgal/d
< 0.5 Mgal/d - 2.0 Mgal/d
< 2.0 Mgal/d - 5.0 Mgal/d
< 5.0 Mgal/d
City of Manteca Limit
5-2
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/24/2023
TR by MA on 10/24/2023
IR Review by MVD on 10/24/2023
Residual System Capacity
10-year, 24-hour Design Storm
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-24 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

5.2.3 Lift Station Performance
Peak flow results for the 10-year, 24-hour design storm at the 10 modeled pump stations are summarized in Table 5-3. The information in the table includes the pump station firm capacity and modeled maximum inflows to each station.

Table 5-3. Modeled Pump Station Results, 10-year, 24-hour Design Storm Lift Station Asset ID Firm Capacity (1) (Mgal/d) Max Station Inflow (Mgal/d) Woodbridge Park WWC-WW01 2.09 1.30
Chadwick Unit 5 WWC-WW02 1.26 1.29
Villa Ticino WWC-WW04 0.73 0.60
Fishback WWC-WW05 0.29 0.17
Union Road WWC-WW06 15.12 10.99
Curran Grove WWC-WW09 0.20 0.06
Roberts Estates WWC-WW11 0.29 0.12
Shadowbrook Park WWC-WW21 1.17 0.25
Evans Estates WWC-WW19 1.05 0.64
Woodward Park WWC-WW17 0.85 2.78
Note:
1 Firm capacity represents the maximum pumping capacity of the lift station with the largest pump out of service.

The firm capacity is defined as the maximum pumping capacity of the lift station with the largest pump out of service. The total pumping capacity is defined as the total maximum capacity of the lift station with all pumps in operation. For purposes of evaluating the firm capacity of pump stations, the model treats pump stations as pumping all incoming flows regardless of station capacity to adequately represent peak inflow conditions.

For the 10-year, 24-hour design storm condition, exceedances of the pump station firm capacity are indicated at two lift stations: Chadwick Unit 5 and Woodward Park. The largest exceedance occurs at the Woodward Park lift station, where flow exceeds the firm and total capacity of the station. Force main diameters and calculated maximum force main velocities are shown in Table 5-4 and shown schematically on Figure 5-3.

ATTACHMENT 2
Table 5-4. Modeled Force Main Results, 10-year, 24-hour Design Storm Lift Station Asset ID Force Main Size (in) Velocity (fps) Flow (Mgal/d) Woodbridge Park WWC-WW01 24 1.03 2.09
Chadwick Unit 5 WWC-WW02 24 0.62 1.26
Villa Ticino WWC-WW04 12 1.44 0.73
Fishback WWC-WW05 6 2.29 0.14
Union Road WWC-WW06 24 7.45 15.12
Curran Grove WWC-WW09 4 3.55 0.20
Roberts Estates WWC-WW11 6 2.29 0.29
Shadowbrook Park WWC-WW21 6 9.22 1.17
Evans Estates WWC-WW19 8 4.66 1.05
Woodward Park WWC-WW17 12 1.68 0.85
The maximum force main velocity criterion of 8 fps is exceeded at the Shadowbrook lift station when operating at the firm capacity. Velocities of less than 2 fps are observed at lift stations that are part of force main systems with varying velocities that range between 0.0 – 2.0 fps and 2.0 – 8.0 fps as shown in Figure 5-3.

ATTACHMENT 2
C ali fo rni a
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Fresno

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LOUISE AV
HWY 99

0.0 fps - 2.0 fps

2.0 fps - 8.0 fps
> 8.0 fps
City of Manteca Limit
5-3
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Modeled Forcemain Velocity
10-year, 24-hour Design Storm
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

5.2.4 LOS Deficiencies
A schematic of modeled gravity sewer and pump station capacity deficiencies for the 10-year, 24-hour design storm conditions are presented in Figure 5-4. The highlighted gravity lines are shown as belonging to the following categories. The first two categories fail LOS criteria as presented in Chapter

4.0 of this report.
• LOS Failure 1: Peak flow exceeds full pipe capacity (FPC), resulting in major surcharging (>1- foot depth).
• LOS Failure 2: Peak flow exceeds FPC, resulting in minor surcharging (<1-foot depth) without sufficient depth (<8-feet of available freeboard).
• Minor Surcharging: Peak Flow exceeds the FPC, resulting in minor surcharging (<1-foot depth) with sufficient depth (>8-feet of available freeboard). • Backwatered: Peak flow does not exceed the FPC, but downstream capacity restrictions result in surcharging. Downstream restrictions include under capacity gravity sewers and/or lift station capacity or operation.
• Design Issue: Simulated surcharging resulting from a design issue, including things such as mismatched pipe crown elevations, individual negative or zero pipe slopes, and/or minor pipe sags.

The primary LOS deficiencies include the following portions of the system:
• 15-inch Center Street Trunk,
• 10-inch Elm/North Street Trunk, and
• Woodward Park pump station pumping capacity.

Recommended improvements for these portions of the system are included in the collection system CIP presented in this WWMP and are described in the following section.

ATTACHMENT 2
C ali fo rni a
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Over Capacity

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-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Modeled Lift Station
Other Lift Station
Water Quality Control Facility
Water Quality Control Facility Structures
Forcemain
Modeled Sanitary Sewer
City of Manteca Limit
Manhole Issues
LOS Failure 1
LOS Failure 2
Minor Surcharging
Backwatered
Design Issue
Other Sanitary Manhole
5-4
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Scenario 1 – Modeled Capacity Deficiencies,
10-year 24-hour Design Storm
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

5.2.5 Recommended Capacity Improvements
Theoretical pipe upsizing improvements to eliminate gravity sewer capacity deficiencies are listed in Table 5-5 and are shown schematically in Figure 5-5. The improvements are sized to accommodate PWWF under buildout development conditions. As indicated in the table, the only recommended gravity sewer improvement is to the main branch of the trunk system in the Central Shed. The capacity constraint identified on Oregon Street is not recommended for improvements because surcharging is minor and predicted to remain under 0.22 feet above the pipe crown, monitoring is recommended under existing conditions.

ATTACHMENT 2
Table 5-5. Theoretical Upsizing Improvements to Alleviate Existing Gravity Sewer Capacity Deficiencies – Scenario 1 ID Description Service
Area
GIS
Install
Year
Upstream
MH ID
Upstream
MH
Location
Downstream
MH ID
Downstream
MH Location
GIS
Pipe
Size
(in)
Ave.

Slope
(ft/ft)
Upsized
Pipe
Size (in)
Total
Length
(LF)
Depth to
Pipe
Crown (ft)
Max
Flow
(Mgal/
d)
Max
Surcharge
(ft)
1 W Center
Street Trunk
Central
Shed Unknown WWMH0349
W. Center
Street and
Elm Avenue
WWMH3125 Union Road
Lift Station 15 0.0012 18 3,802 6.5 to 17.2 2.28 0.5
2 Elm/West
North Street
Trunk
Central
Shed Unknown WWMH0883
E. North
Street and
Fremont
Street
WWMH0349
W. Center
Street and
Elm Avenue
10 0.0013 15 4,510 5.1 to 14.1 1.43 3.44
3 10-inch East
North Street
Trunk
Central
Shed
1951-
1955 WWMH0901
E. North
Street and
Marie
Avenue
WWMH0883
E. North and
Fremont
Street
10 0.0014 12 1,325 4.1 to 7.9 0.74 1.6
4 8-inch East
North Street
Trunk
Central
Shed 1957 WWMH1432
E. North
Street and
Cottage
Avenue
WWMH0896
E. North
Street and
Charles
Avenue
8 0.0014 10 560 6.4 to 6.8 0.37 2.5
ATTACHMENT 2
It should be noted that these theoretical improvements do not necessarily equate to a recommendation to proceed forward with design and construction of replacement sewers. While the model indicates potential for surcharging and/or SSOs in the indicated lines during peak flow conditions, most of the identified pipes were not directly flow metered, but rather the peak flows are inferred from downstream flow measurements based on the model calibration process described in Chapter 3.0 of this report.

Moreover, the collection system geometry (especially pipe diameters, pipe invert elevations, and surface elevations) have not generally been confirmed by field surveys. In all cases, system geometry (including pipe depths, diameters, and rim elevations) should be confirmed by field surveys. In addition, it is recommended that the modeled capacity exceedances at the Woodward Park pump station be confirmed through flow metering and/or pump run time logging. The improvements in this section are included in the recommended CIP but are still subject to survey and field verification described above.

The alternative improvements considered for the Woodward Park pump station under existing conditions include: 1) increasing the firm pumping capacity to meet the simulated maximum inflow of approximately

2.8 Mgal/d by adding an additional pump to the station or swapping out the existing pumps for larger ones, or 2) installing 4,030 LF of 36-inch sewer to extend the existing South Trunk in Woodward Avenue to reach the unused existing 36-inch sewer at the intersection of Woodware Avenue and S. Main Street, additional discussion of this project is presented in Section 5.3.1 of this report. Further improvements would be required beyond Project 5B under buildout conditions therefore, Project 5A is ultimately recommended. Alternative improvements for the Woodward Park Lift station under existing conditions are summarized in Table 5-6.

ATTACHMENT 2
Table 5-6. Alternative Capacity Improvements for the Woodward Park Lift Station (Existing Conditions) ID Description Service
Area
GIS Install
Year
Upstream MH
ID
Upstream MH
Location
Downstream
MH ID
Downstream
MH Location
Ave.

Slope
(ft/ft)
Upsized Pipe
Size (in)
Total Length
(LF)
5A South Woodward
Trunk Extension
South
Shed
2001/
2011 WWMH0481
Woodward
Avenue and S.

Main Street
WWMH4162
East of Pagola
and Woodward
Avenue

0.0006 36 4,030
ID Description Service
Area
GIS Install
Year
Existing Firm
Capacity
(Mgal/d)
Expanded Firm
Capacity
(Mgal/d)
Existing No.

Pumps
Design Flow
(gpm)
Design
Head (ft)
Existing
Force Main
Size (in)
New Force
Main
Velocity (fps)
5B
Expand Woodward
Park Pump Station
Capacity
South
Shed 2001 0.85 2.8 2 590 38 12 5.48
ATTACHMENT 2
Additional lift station concerns include backwatered surcharging in the trunk lines north and south along Union Road due to the general operating configuration of the Union Road lift station, the firm capacity of Chadwick Unit 5, and high velocity in the Shadowbrook Park force main when pumping at firm capacity.

Significant improvements to the Union Road lift station would be required to eliminate surcharge in the north and south Union Road gravity trunk lines. Surcharging is predicted to be around 1-foot with more than 12-feet of available freeboard. A future project to take the Union Road lift station offline has previously been identified by the City, which would eliminate this concern. Additional discussion of this project is also presented in Section 5.3.1 of this report.

The Chadwick Unit 5 pump station is recommended for monitoring as firm capacity is only predicted to be exceeded by 0.03 Mgal/d. It’s also recommended that the pumping capacity of the Shadowbrook Park pump station be verified. Firm capacity was taken from the original record drawings. It’s possible that the drawings include an error or that a smaller pump has replaced the originally specified pump. No improvements are recommended for these stations in Scenario 1, under existing conditions.

ATTACHMENT 2
J3
J5
205
Ripon
Manteca

YOSEMITE AV

WOODWARD AV

MAIN ST

UNION RD
4551000 4548000
4551000 4548000
-13494000 -13491000
-13494000 -13491000
5-5
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/24/2023
TR by MA on 10/24/2023
IR Review by MVD on 10/24/2023
Recommended Improvements to Address
Existing Capacity Deficiencies
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-24 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

EPA, NPS
0 500 1,000
Feet
"($ $
¯ (At original document size of 11x17)
1:15,000
Union
Road
Woodward
Park
Curran Grove
Legend
Modeled Lift Station
Other Lift Station
Forcemain
Modeled Sanitary Sewer
Master Plan Project
Project 1
Project 2
Project 3
Project 4
Project 5
City of Manteca Limit
ATTACHMENT 2

5.3 SCENARIOS 2 TO 4 – FUTURE GROWTH ANALYSIS
The purpose of this section is to present the results of the hydraulic model of the wastewater collection system under future development conditions defined by the City’s General Plan (Scenarios 2 to 4).

Scenario 1 – Existing Development results are provided in Section 5.2. Modeled conditions for the ultimate planning area consist of flow for existing conditions, plus future flows from areas that do not discharge to the City’s wastewater system. The following level of development scenarios were considered.
• Scenario 1 – Existing Development (refer to Section 5.2) • Scenario 2 – Buildout of City Limits
• Scenario 3 – Buildout of the SOI
• Scenario 4 – Full General Plan Buildout
The hydraulic model of the existing collection system was adjusted to include flow from future development projects within the planning area at each level of development scenario. The land uses, WGFs, and other assumptions of the areas added to each scenario have been described in Section 4.2 of this report. A summary of simulated flow conditions for each scenario is presented in Section 5.1.

5.3.1 Impacts of Growth on Existing Infrastructure
As discussed in Chapter 4 the general approach to flow routing is that flows originating from future development will be routed through their respective service area or sewer shed. The majority of flow from infill developments within City Limits is routed through the existing system in Scenario 2. In Scenarios 3 and 4, flow originating from within the City’s SOI and remaining planning area is primarily routed through new trunks in the North and South Sheds because the Central Shed exists within City Limits and is largely built out. After laying out the future system and evaluating future system results, this flow routing approach was slightly modified to minimize future improvement needs and take advantage of residual capacity within the existing system. The SOI area within the North Shed that exists immediately to the east of the Central Shed was ultimately routed through existing infrastructure in the Central Shed.

The modeled system deficiencies for future development conditions are only slightly more severe than those described for existing conditions. Key information is summarized below:
• The recommended improvements described under existing conditions also serve buildout flows, aside from Project 5B which expands the Woodward Park pumping capacity to meet existing needs.
• Figure 5-6 shows areas of the existing system that fail LOS criteria under future conditions. • The modeled results for the 10-year, 24-hour design storm, under each level of development scenario, are included in Appendix F.

ATTACHMENT 2
• The impacts of future growth on existing pump stations are shown in Table 5-7. • Pump and lift stations that would need improvements to expand the firm capacity at each level of development to meet future system flow conditions are highlighted in Table 5-7.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Woodward Park
Over Capacity
Roberts Estates
Over Capacity
Villa Ticino
Over Capacity
Chadwick U5
Over Capacity
Woodbridge Park
Over Capacity
Evans
Over Capacity
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Modeled Lift Station
Other Lift Station
Water Quality Control Facility
Water Quality Control Facility Structures
Forcemain
Modeled Sanitary Sewer
City of Manteca Limit
Manhole Issues
LOS Failure 1
LOS Failure 2
Minor Surcharging
Backwatered
Design Issue
Other Sanitary Manhole
5-6
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/19/2023
TR by MA on 10/19/2023
IR Review by MVD on 10/19/2023
Scenarios 2-4 - Modeled Capacity
Deficiencies, 10-year 24-hour Design Storm
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-19 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

3. Background: San Joaquin County GIS/Planning, California State Parks, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, USDA, Merced County Association of Gov, Esri, HERE, Garmin, FAO, NOAA, USGS, EPA, Esri, USGS
0 0.5 1
Miles
"($ $
¯ (At original document size of 11x17)
1:45,000
ATTACHMENT 2
Table 5-7. Modeled Pump Station Results, 10-year, 24-hour Design Storm Maximum Modeled Inflow (Mgal/d)
Lift Station
Firm
Capacity
(Mgal/d)
Scenario 1 -
Existing
Scenario 2 - City
Growth
Scenario 3 - SOI
Growth
Scenario 4 -
Buildout
Woodbridge Park 2.09 1.30 2.05 6.07 12.39
Chadwick Unit 5 1.26 1.29 1.33 2.31 2.31
Villa Ticino 0.73 0.60 0.90 0.90 0.90
Fishback 0.29 0.17 0.25 0.25 0.25
Union Road 15.12 10.99 12.44 13.50 13.56
Curran Grove 0.20 0.06 0.06 0.06 0.06
Roberts Estates 0.29 0.12 0.52 0.52 0.52
Shadowbrook Park 1.17 0.25 0.25 0.25 0.25
Evans Estates 1.05 0.64 3.44 4.52 4.52
Woodward Park 0.85 2.78 4.37 5.59 5.80
Based on the results presented in Table 5-7, the following lift stations will also require expansions or alternative improvements:
• Woodbridge Park – To support the addition of infill, SOI, and additional planning areas in the North Shed, the largest lift station improvements would be required at the Woodbridge Park pump station. The ultimate firm capacity would need to be expanded to over 12 Mgal/d. • Chadwick Unit 5 – No improvements were recommended for this lift station under existing conditions because it was only predicted to be slightly over its existing firm capacity. Under future conditions improvements to expand firm capacity to 2.31 Mgal/d would be required to support infill development.
• Villa Ticino – To support infill development the firm capacity will need to be expanded to 0.90 Mgal/d.
• Roberts Estates – To support infill development the firm capacity will need to be expanded to

0.52 Mgal/d, roughly double the current capacity.
• Evans Estates – This lift station will require significant improvements to serve the Austin Road Industrial Area, as assumed in this WWMP. In addition to expanding the pumping capacity to

4.52 Mgal/d, the existing 8-inch force main would also require improvements. The velocity in the force main would be greater than 18 fps under the firm capacity needs predicted at buildout. • Woodward Park – if not addressed by gravity improvement recommended in Project 5A for existing system improvements, firm capacity will need to be expanded to 5.8 Mgal/d. This scenario would also require improvements Woodward Park 12-inch force main as the velocity would exceed 11 fps, but also to the joint 12-inch force main of the Evans and Woodward Park ATTACHMENT 2
pump stations considering the velocity of the combined total flow contributions which is predicted to be 20 fps.

The following LOS deficiencies were identified in the gravity collection system under future development conditions:

Fishback Lift Station Tie-in (Scenarios 2 – 4): Surcharging was identified under all three future development scenarios. This deficiency is due to the large amount of infill added to the Fishback lift station collection shed. The City’s GIS database indicates that the lift station discharges to a gravity line (8-inch) that is smaller than the gravity lines within the collection area (10-inch). Therefore, surcharging is predicted to occur in the gravity line downstream of the force main discharge location in North Airport Way, south of the North Trunk Sewer. An improvement project to take this lift station offline and upsize this sewer is recommended in the following sections (Project 9).

North Trunk Sewer (Scenario 4): Surcharging in the newly installed 36-inch North Trunk Sewer in Airport Way is predicted to exceed 1-foot in Scenario 4 with the addition of flow from the buildout service area and recommended improvements discussed in the following sections. Surcharge depth is predicted to reach 2.7 feet above the pipe crown between Crom Street and Geneva Way. No improvements are recommended to address this deficiency due to its recent installation and depth. Freeboard is expected to remain greater than 19 feet despite surcharging.

5.3.2 Previously Identified System Improvements
The City of Manteca has already made investments in their future collection system by preemptively installing oversized lines for future gravity sewers. Projects that would complete the construction of these gravity sewers are described below.

Project 5A: South Woodward Trunk Extension
This project was presented as an alternative to upgrading the Woodward Park lift station under existing conditions. The 36-inch South Trunk sewer in Woodward Avenue conveys wastewater flow to the treatment plant by gravity. It is currently missing a segment between Pagola Way and South Main Street.

In the upstream, the City has already installed a 36-inch sewer to convey flows that currently conveyed through the Woodward Park pump station by gravity. Installing this remaining segment of sewer would allow the Woodward Park pump station to be taken offline and also allow the Evan’s pump station to be taken offline through additional projects. This project would mitigate the need to expand both the Woodward Park and Evan’s Pump Stations.

Project 6A: Central Union Road Trunk Extension
The City recently completed a project replacing the North Trunk Sewer as shown on Figure 5-7. The project replaced the 36-inch trunk sewer with a larger and deeper 54-inch sewer. Based on review of previous Master Plans and discussions with the City, this project was the first leg of an overall project intended to take the Union Road lift station offline. The Central Trunk could be extended from the upstream point of North Trunk project to bypass the lift station and allow flow from the Central Shed to ATTACHMENT 2
flow by gravity to the WQCF. City staff have noted many on-going issues with the lift station that were observed in the flow monitoring data collected as part of this WWMP. The station frequently experiences pump failure and uses the upstream collection system as part of its operating volume, which has contributed to catastrophic failures in the upstream trunk network. In addition to O&M issues the station is beyond its useful life, pumps currently installed in the station are from 1960. Although the capacity of the lift station appears to be sufficient, this project is recommended to eliminate surcharge experienced during operating conditions and O&M costs associated with the station.

Project 7A: North Trunk Extension on Airport Way
A 48-inch sewer exists at the upstream end of Airport Way, where flow is currently conveyed to the Woodbridge Park pump station. The upstream trunk in Daisywood Drive is also oversized to accommodate future flows from the North Shed. Based on review of prior Master Plans this trunk was planned to ultimately connect through an extension of the North Trunk sewer along Airport Way. The City recently installed approximately 2,900 LF of 36-inch sewer in Airport Way between the Manteca Park Golf Course and Louise Avenue.

Continuing the North Trunk sewer along Airport Way to the Woodbridge Park pump station would allow the station to be taken offline in addition to those that lie within the project extents, including Chadwick Unit 5, Assieh Development, MUSD, and Villa Trinco. Another un-used existing oversized line exists to take the Centerpoint Pump Station offline and serve the northern planning area. Although the benefits of taking six lift stations offline and avoiding future expansions are high there are also constructability concerns with the potential project. The trunk extension would be over 20-feet deep in already crowded utility corridor. There are also surface features, such as water drainages, railroad crossings, and major intersections. The previously identified system improvement projects are summarized in Table 5-8. These projects and existing oversized portions of the system are shown in Figure 5-7.

Table 5-8. Previously Identified System Improvements
ID Description Service
Area
GIS
Install
Year
Upstream
MH ID
Upstream
MH
Location
Downstream
MH ID
Downstream
MH Location
Ave.

Slope
(ft/ft)
Pipe
Size
(in)
Total
Length
(LF)
5A
1 South
Woodward
Trunk
Extension
South
Shed
2001/
2011 WWMH0481
Woodward
Avenue and
S. Main
Street
WWMH4162
East of
Pagola and
Woodward
Avenue

0.0006 36 4,030
6A
Central Union
Road Trunk
Extension
Central
Shed 1960 WWMH3125
Inlet to
Union Rd
PS
SSMH-13
Upstream
End of North
Trunk at
Airport Way

0.0027 36 5,031
7A
North Trunk
Extension on
Airport Way
North
Shed
2022/
2006 WWMH3392
Inlet to
Woodbridge
Park PS
SSMH-12
Upstream
End of the
existing 36-
inch sewer.

0.0006 48 7,670
Note:
1 Project 5A also listed under existing system improvements.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Lift Station Status
Active
Unmodeled
Inactive
Abandoned
Removed with CIP
Water Quality Control Facility
Water Quality Control Facility Structures
Modeled Forcemain
Sanitary Network
North Trunk
South Trunk
Oversized Trunk
Trunk
Assumed Projects
Project 5
Project 6
Project 7
City of Manteca Limit
5-7
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/25/2023
TR by MA on 10/25/2023
IR Review by MVD on 10/25/2023
Previously Identified System
Improvements
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-25 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

5.3.3 Recommended Capacity Improvements
In addition to the previously identified system improvements, the following projects have been identified to address the predicted capacity constraints at each future level of development in the existing collection system.

Project 8: South Main Trunk to Evans (Evans)
Upon completion of Project 5A, it is recommended that the City install a new 27-inch sewer in South Main Street to allow the Evans pump station to be taken offline. Thereby avoiding future pump station expansions, force main improvements, and the O&M costs associated with the Evans pump station. This project is dependent on the completion of the South Woodward Trunk Extension project as it would tie into the upstream end of the project at South Main Street and Woodward Avenue.

Project 9: South Airport Way and Yosemite Avenue (Fishback) Although capacity improvements were not identified for the Fishback lift station, the downstream collection system was identified as being undersized. As an alternative to upsizing the 8-inch gravity line in Airport Way, the City could install a new 10-inch gravity line all the way to the lift station and take it offline.

Project 10: South Airport Way Roberts Estates to Daniels (Roberts Estates) The Roberts Estates lift station can be taken offline by extending a 10-inch sewer down Airport Way from the lift station at Wawona Street to the 12-inch sewer in Daniels Street. This eliminates O&M costs associated with the station as well as the need to almost double its firm capacity to support infill development.

These projects to address existing collection system capacity constraints under future conditions are summarized in Table 5-9 and shown on Figure 5-8.

ATTACHMENT 2
Table 5-9. Theoretical Upsizing Improvements to Alleviate Existing Sewer Capacity Deficiencies – Future Scenarios ID Description Service
Area
GIS
Install
Year
Upstream
MH ID
Upstream
MH
Location
Downstream
MH ID
Downstream
MH Location
GIS
Pipe
Size
(in)
Ave.

Slope
(ft/ft)
Upsized
Pipe
Size (in)
Total
Length
(LF)
Depth to
Pipe
Crown (ft)
Max
Flow
(Mgal/
d)
Max
Surcharge
(ft)
Scenario 2 Improvements
8 S. Main Trunk
to Evans
South
Shed
2016/
2001 WWMH5022 Inlet to Evans PS WWMH0481
Woodward
Avenue and
S. Main Street
8FM 0.0007 27 2,688 Mitigates lift station
improvements. (Evans)
9 S. Airport Way
and Yosemite
Ave.
(Fishback)
South
Shed 1978 WWMH2665
W Yosemite
and
Fishback,
PS inlet
SSMH-13
Upstream End
of North Trunk
at Airport Way
8 0.0025 10 2,664 7.5 to 5.1 0.511 3.077
10 S. Airport Way
Roberts
Estates to
Daniels
South
Shed 1996 WWMH2754
S. Airport
Way and
Wawona
Street
WWMH2321
S. Airport Way
and Daniels
Street
6FM 0.0047 10 1,317 Mitigates lift station
improvements. (Roberts)
ATTACHMENT 2
J3
J5
205
Ripon
Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MAIN ST

AIRPORT WY

UNION RD
4551000 4548000
4551000 4548000
-13497000 -13494000
-13497000 -13494000
Legend
Modeled Lift Station
Other Lift Station
Removed with CIP
Water Quality Control Facility
Water Quality Control Facility Structures
Modeled Sanitary Sewer
Master Plan Project
Project 8
Project 9
Project 10
City of Manteca Limit
5-8
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/25/2023
TR by MA on 10/25/2023
IR Review by MVD on 10/25/2023
Recommended Improvements to Address
Future Capacity Deficiencies
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-25 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

EPA, NPS
0 1,000 2,000
Feet
"($ $
¯ (At original document size of 11x17)
1:18,000
Woodward
Park
Union
Road
Fishback
Roberts
Estates
Evans
ATTACHMENT 2

5.3.4 System Infrastructure to Serve Future Development Modeled future system infrastructure, including pump stations, force mains, and gravity sewers 10-inches in diameter and larger were considered in the development of this WWMP. The considered infrastructure layouts are based on an analysis of surface topography, critical surface features (such as highways, railroads, and surface water), and sewer pipe depths. The exact configuration of collection system facilities serving future areas is subject to change as development proceeds. For modeled future flow conditions, all existing infrastructure is assumed to remain unchanged aside from improvements identified for the existing system in Section 5.2. Moreover, the model treats pump stations as passing all incoming flows regardless of station capacity such that capacities of pump stations and downstream gravity lines can be properly evaluated.

5.3.4.1 Scenario 2 – Buildout of City Limits
There are approximately 4,962 acres of undeveloped area with the existing city limits boundary, 73 percent of which exists in the South Shed of the collection system. Much of this area is already planned for development or currently being developed.

Project 11: Yosemite Square Lift Station and Improvements To serve the area north of the Austin Road Industrial Area, across Highway 99, referred to as Yosemite Square, a 2.4 Mgal/d lift station will be required to convey flow to the South Trunk in Woodward Avenue.

The new 4,855 LF of 8-inch force main should be routed to an existing 18-inch sewer crossing at the intersection of Woodward Avenue and Moffat Boulevard. It is assumed that the existing 18-inch force main crossing is not being used and will be tied into a new 15-inch sewer in Woodward Avenue to be installed as part of an upcoming roadway realignment project. The cost of this 15-inch sewer in Woodward Avenue is included in this project in addition to approximately 3,230 LF of 15-inch sewer needed to serve the area upstream of the lift station. The 1,425 LF 15-inch sewer in Woodward Avenue should be installed with the highest slope possible, assumed to be 0.006 ft/ft.

Project 12: Austin Road Industrial Area Trunk
The largest planned development is the Austin Road Industrial area which is approximately 2,066 acres located in the southeast corner of city limits. A new trunk extending east from the existing 24-inch sewer in South Main Street to Austin Road is recommended to serve the Austin Road Industrial Area. This project assumes steeper than minimum slopes to follow the existing ground surface. The project assumes the following: 2,950 LF of 24-inch sewer at 0.0012 ft/ft, 5,300 LF of 21-inch sewer at 0.0012 ft/ft, and 2,350 LF of 18-inch sewer at 0.0015 ft/ft. It should be noted that larger pipe sizes may be required if these slopes are not achieved.

Project 13: South Austin Road - Industrial Area
A 15-inch sewer extending from the Austin Road Industrial Area Trunk in South Austin Road is recommended to serve the northern portion of the development.

ATTACHMENT 2

5.3.4.2 Scenario 3 – Buildout of the SOI
The existing city SOI includes 6,393 acres of undeveloped land surrounding city limits. Approximately 1,076 acres of that land is designated as agriculture, ROW, water, or open space and are assumed to not contribute wastewater flow to the existing system. Approximately 2,859 acres are added to the North Shed, 3,473 acres are added to the South Shed, and the remaining 62 acres are within the central shed.

As previously discussed, a portion of the eastern South and North Shed areas is directed through the Central Shed to utilize residual capacity in the existing system.

Project 14: Yosemite Square Service Area
The Yosemite Square lift station is proposed to be located centrally within its ultimate service area. To serve the portion of the service area outside of City Limits approximately 3,575 LF of 15-inch sewer in is proposed in Austin Road from Highway 99 to the lift station.

Project 15: Oleander Avenue Extension/ S. Airport Way Sewer To serve the southern SOI area an extension of the existing 12-inch sewer in Oleander Avenue and a new sewer in S. Airport Road are recommended. This project includes approximately 2,250 LF of new 12-inch sewer in Oleander Avenue and 3,365 LF of new 10-inch sewer in S. Airport Road.

Project 16: Highway 99 Crossing at Northland Road
A new 24-inch trunk sewer crossing Highway 99 at Northland Road is recommended to serve the North Shed SOI area. This trunk ties into the existing 36-inch sewer stub that exists along the Manteca Tidewater Bikeway. This project assumes approximately 3,515 LF of 24-inch sewer. The depth at the highway crossing is estimated to be approximately 25-feet.

Project 17: East Lathrop Road Trunk
This project proposes a new 18-inch sewer in South Frontage Road extending from the Highway 99 Crossing at Northland Road (Project 16) to Lathrop Road and a 15-inch sewer continuing east to Cottage Avenue.

Project 18: Northland Road Trunk
An 18-inch sewer extending east down Northland Road from the proposed Highway 99 Crossing at Northland Road (Project 16).

Project 19: Northland Road Branches
Two 12-inch sewers are included to direct flow from the Northern SOI area to the Northland Road Trunk recommended in Project 18.

ATTACHMENT 2
Project 20: Louise/Nehemiah Branches
This project includes two 12-inch sewer extensions from the existing system to Austin Road to serve development east of the Central Shed. One that ties into the 18-inch sewer in East Louise Avenue at Pestana Avenue and one that ties in to the 18-inch sewer in Pestana Avenue at Nehemiah Drive.

Project 21: South Union Road Extension
To serve the southern most portion of the SOI its recommended that the existing 12-inch sewer in South Union Road be extended by approximately 3,940 LF.

Project 22: Cottage Avenue
To serve the SOI area south of Lathrop Road a 12-inch sewer is recommended to extend in Cottage Avenue from the 15-inch East Lathrop Road Trunk (Project 17).

5.3.4.3 Scenario 4 – Full General Plan Buildout
The remaining planning area consists of 6,424 acres of land which primarily expands the North Shed service area. Approximately 50 percent of this area is designated with land uses that will contribute wastewater to the future service area. There are approximately 5,590 acres added to the North Shed and 845 acres added to the South Shed. The majority of the area added to the south shed will not contribute wastewater flow, therefore, no new infrastructure is included beyond that identified in Scenario 3 in the South Shed.

Project 23: North Shed Union Road Trunk
Extending the existing 30-inch sewer north along Union Road to Lovelace Road is recommended to serve the remaining planning area.

Project 24: Manteca Junction Trunk
This project recommends a 10-inch sewer extending further north along Union Road from Project 23.

Project 25: Lovelace Road Trunk - 99 Crossing
A 24-inch sewer extension east from Lovelace and Union Road crossing Highway 99 and a 15-inch sewer from Highway 99 to Castle Road.

The system infrastructure needed to serve future development at each level of development is summarized in Table 5-10 and shown in Figure 5-9. The service area of each CIP is shown in Figure 5-

10. A comparison of these recommended improvements and those presented in the 2012 Master Plan is presented in Figure 5-11.

ATTACHMENT 2
Table 5-10. System Infrastructure to Serve Future Development ID Description Service
Area
Upstream
MH ID
Upstream
MH Location
Downstream
MH ID
Downstream
MH Location
Ave.

Slope
(ft/ft)
Pipe
Size
(in)
Total
Length
(LF)
Scenario 2 Improvements
11 Yosemite
Square Lift
Station and
Improvement
South
Shed BOSSMH41 Yosemite Square WWMH3342
E. Woodward
and Atherton
Drive

0.006

0.0015
15 8FM 9,514
12 Austin Road
Industrial
Area Trunk
South
Shed BOSSMH6
Sedan
Avenue and
Austin Road
WWMH5167
S. Main Street
and Sedan
Avenue

0.0012

0.0015
24/21/
18 10,598
13 South Austin
Road -
Industrial
Area
South
Shed BOSSMH50
Moffat Blvd
and Austin
Road
BOSSMH6
Sedan Avenue
and Austin
Road

0.0015 15 4,333
Scenario 3 Improvements
14 Yosemite
Square
Service Area
South
Shed BOSSMH49
South 99
Frontage
Road
Yosemite
Square LS
Yosemite
Square 0.0015 15 3,575
15 Oleander
Avenue
Extension
South
Shed BOSSMH19
Oleander
Avenue
between
Peach/Fig
WWMH4922
End of existing
Oleander
sewer

0.0015 15 2,250
16 Highway 99
Crossing at
Northland
Road
North
Shed BOSSMH020
Northland and
Frontage
Road
WWMH3470
Green Valley
and Happy
Valley Lane

0.0011 24 3,515
17 East Lathrop
Road Trunk
North
Shed
BOSSMH001
1 Lathrop and
Cottage
Avenue
BOSSMH020 Northland and
Frontage Road 0.0015 18/15 7,335
18 Northland
Road Trunk
North
Shed BOSSMH89 Northland and Castle Road BOSSMH020 Northland and Frontage Road 0.0012 18 3,789 19 Northland
Road
Branches
North
Shed
BOSSMH168/
BOSSMH178
North on
Castle Road,
East on
Northland
BOSSMH89 Northland and
Castle Road 0.002 12 5,255
20 Louise/
Nehemiah
Branches
Central
Shed BOSSMH99
Austin Road
and E. Louise
Avenue
WWMH2114
E. Louise and
Pestana
Avenue

0.002 12 5,252
21 South Union
Road
Extension
South
Shed BOSSMH20 Union Road South of Fig WWMH4954 Union Road and Lavender 0.002 12 3,940 22 Cottage
Avenue
North
Shed BOMH00029 Cottage and Southland
BOSSMH001
1 Cottage and
Lathrop 0.002 12 2,410
Scenario 4 Improvements
23 North Shed
Union Road
Trunk
North
Shed BOSSMH18
Lovelace and
S. Union
Road
WWMH3782
S. Union Road
at Abbey Mist
Street

0.0006 30 4,692
24 Manteca
Junction
Trunk
North
Shed BOSSMH4
S. Union
Road north of
Coelho Road
BOSSMH18 Lovelace and
S. Union Road 0.0025 10 3,008
25 Lovelace
Road - 99
Crossing
North
Shed BOSSMH88 Castle Road Corner BOSSMH18 Lovelace and S. Union Road

0.0008

0.0015 24/15 9,257
ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Project 20
Project 24
Project 21
Project 15
Project 16
Project 18
Project 12
Project 23
Project 19
Project 11
Project 13
Project 22
Project 25
Project 14
Project 17
4557000 4554000 4551000 4548000 4545000
4557000 4554000 4551000 4548000 4545000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 5-9
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/20/2023
TR by MA on 10/20/2023
IR Review by MVD on 10/20/2023
System Infrastructure to Serve Future
Development
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-20 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Project 5
Project 6
Project 7
Project 12
Project 20
Project 24
Project 15
Project 16
Project 18
Project 23
Project 19
Project 11
Project 13
Project 22
Project 25
Project 17
Project 14
Project 21
Project 10
Project 9
Project 8
15in
12in
18in
12in
12in
12in
24in
10in
15in
18in
24in
15in
12in
15in
15in
30in
12in
21in
24in
8in
18in
15in
12in
10in
10in
24in
36in
36in
48in
Chadwick U5
Fishback
Union Road
Villa Ticino
Woodbridge
Park
Woodward Park
Evans
4560000 4557000 4554000 4551000 4548000 4545000
4560000 4557000 4554000 4551000 4548000 4545000
-13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 -13506000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13485000 5-10
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 11/3/2023
TR by MA on 11/3/2023
IR Review by MVD on 11/3/2023
Recommended Future System
Improvements
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-11-03 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Project 5
Project 6
Project 7
Project 12
Project 20
Project 24
Project 15
Project 16
Project 18
Project 23
Project 19
Project 11
Project 13
Project 22
Project 25
Project 17
Project 14
Project 21
Project 10
Project 9
Project 8
4557000 4554000 4551000 4548000 4545000
4557000 4554000 4551000 4548000 4545000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 5-11
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 10/25/2023
TR by MA on 10/25/2023
IR Review by MVD on 10/25/2023
Changes from 2012 Master Plan
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-10-25 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

5.4 PHASING STRATEGIES AND POTENTIAL ALTERNATIVES
The growth rate of development within the City’s planning area will dictate the time horizon for buildout of the ultimate service area. However, it is possible that full buildout may not occur within the time frame of the General Plan or in the order assumed in this Master Plan. This section presents the assumed project phasing strategy and presents alternative improvements to key CIP projects recommended for buildout.

The collection system CIP projects are generally presented in the order they should be completed based on the assumed order of development presented in model scenarios. Many of the future system improvement projects are dependent on the implementation of other recommended projects. Primarily the previously identified improvements discussed in Section 5.3.2 of this report, including Project 5, and Project 7. Table 5-11 presents the recommended collection system CIP projects and lists the dependent projects that need to be implemented prior to their construction.

Table 5-11. Dependent CIP Project Phasing
ID Name Dependent Projects
Scenario 1 Improvements
1 W Center Street Trunk Existing System Need
2 Elm/West North Street Trunk Existing System Need
3 10-inch East North Street Trunk Existing System Need
4 8-inch East North Street Trunk Existing System Need
5A South Woodward Trunk Extension Existing System Need
6 Central Union Road Trunk Extension Existing System Need Scenario 2 Improvements
7 North Trunk Extension on Airport Way None
8 S. Main Trunk to Evans 5
9 S. Airport Way and Yosemite Ave. (Fishback) None
10 S. Airport Way Roberts Estates to Daniels None
11 Yosemite Square Lift Station and Improvements None
12 Austin Road Industrial Area Trunk 5, 8
13 South Austin Road - Industrial Area 5, 8
Scenario 3 Improvements
14 Yosemite Square Service Area 5
15 Oleander Avenue Extension/ S. Airport Way Sewer None 16 Highway 99 Crossing at Northland Road 7
17 East Lathrop Road Trunk 7, 16
18 Northland Road Trunk 7, 16
19 Northland Road Branches 7, 16, 18
20 Louise/ Nehemiah Branches None
21 South Union Road Extension None
22 Cottage Avenue None
Scenario 4 Improvements
23 North Shed Union Road Trunk 7
24 Manteca Junction Trunk 7, 23
25 Lovelace Road - 99 Crossing 7, 23
ATTACHMENT 2
As shown in Table 5-11, the greatest number of projects are dependent on the implementation of Project 5 and Project 7. As previously discussed, both of these projects consist of large, deep, gravity sewers that connect oversized portions of the existing system to the North and South Trunk sewers which flow by gravity to the WQCF, thereby allowing for the decommissioning of several lift stations. These projects also serve as the major conduit for future growth in the South Shed (Project 5) and North Shed (Project 7), making these projects a key component of the overall collection system CIP.

These previously identified system improvement projects pose construction challenges due to their depth, location in crowded utility corridors, and need for highway/railroad crossings, with the most significant challenges associated with Project 7. The following alternatives improvements to expand existing lift stations are presented for the previously identified improvement projects described in Section 5.3.2.

Rebuilding the Union Road lift station as alternative to Project 6 is also discussed.

Project 5C: Expand Woodward Park and Evans Lift Stations Project 5B was described in Section 5.2 and included upgrading the Woodward Park lift station to meet capacity needs under existing conditions as an alternative to Project 5A which would extend the South Woodward Trunk and take the lift station offline. This alternative, Project 5C, also proposes an alternative to Project 5A with enough capacity to provide service under buildout conditions. As discussed, further improvements to the Woodward Park lift station would be needed to meet flows under buildout conditions.

Additionally, without implementing Project 5A, Project 8 which would take the Evans lift station offline could not be implemented. Therefore, expanding both lift stations would be required under this alternative.

The projected buildout flow at the Woodward Park lift station is approximately 6.0 Mgal/d and the projected buildout flow at the Evans lift station is approximately 4.2 Mgal/d. The individual lift station force mains and combined force main system for these stations would also require improvements. The 12-inch Woodward Park lift station force main would need to be expanded to 16-inches in diameter, the 8-inch Evans lift station force main would need to be expanded to 14-inches in diameter, and the combined 12- inch force main would need to be expanded to 18-inches in diameter. The force main system could be shorted and tie into the upstream end of the existing 36-inch sewer in Woodward Avenue east of Pagola Avenue.

Implementing Project 5A, to extend the South Woodward Trunk and take the lift stations offline, is ultimately recommended for the following reasons:
• O&M costs of two major lift stations would be eliminated. • Avoids expanding these lift stations to meet future capacity needs. • The replacement of these forcemains would run a longer length than replacing them with gravity lines, due to the preemptively installed 36-inch gravity line that runs from S. Main Street to the Woodward Park Lift Station.
• Takes advantage of otherwise unused preemptively installed system capacity.

ATTACHMENT 2
Project 6B: Rebuild the Union Road Lift Station
Project 6B is presented as an alternative to Project 6A, the Central Union Road Trunk Extension, which would replace the existing Union Road lift station force main and take the station offline. This alternative would rebuild the existing Union Road lift station at its current capacity, 15.2 Mgal/d, which is sufficient for buildout capacity needs. It would also require that the existing force main be rehabilitated or replaced as identified in Chapter 6.0 of this report (North of Yosemite Avenue in Golf Course and Field). A new deeper wet-well would be required to eliminate surcharging in the collection system which occurs during general operation.

Replacing the Union Road lift station and discharge line with Project 6A, the Central Union Road Trunk Extension is ultimately recommended for the following reasons:
• Based on discussions with City staff, rebuilding the station in its existing location would pose challenges on such a confined site.
• The City has recently invested in constructing the North Trunk Sewer Project which extended the North Trunk sewer to meet the discharge location of the Union Road Lift Station at a depth that would allow the station to be taken offline.
• The lift station is beyond its useful life, has a high O&M impact, and consistently surcharges the upstream system. The upstream collection system will be left at risk of additional catastrophic failures if sufficient depth cannot be provided to allow the lift station to operate without surcharging the upstream system.
• The need to replace or rehabilitate discharge line that follows the same alignment as the proposed project. The alignment is generally open space with limited utility conflicts and crossings. • Eliminates associated lift station improvement and O&M costs.

Project 7B: Expand North Shed Lift Stations
As an alternative to Project 7A, the North Trunk Extension on Airport Way, the lift stations in the North Shed could be expanded to provide sufficient capacity for buildout flows. This would require expanding Woodbridge Park, Villa Ticino, and Chadwick Unit 5. No improvements to the existing 24-inch force main would be required. The Woodbridge Park lift station would require the most extensive improvements to expand it from its current capacity of 2.1 Mgal/d to approximately 12.4 Mgal/d. Villa Ticino would need to be expanded to approximately 1.0 Mgal/d and Chadwick Unit 5 would need to be expanded to approximately 2.4 Mgal/d. The Villa Ticino and Chadwick Unit 5 lift stations are located in the sidewalk and do not have room to expand and with such a large expansion at Woodbridge Park it’s likely that each of these lift station expansions would require land acquisition. The Villa Ticino lift station could currently be taken offline if flows were redirected to the existing 36-inch sewer in Airport Way.

Both Project 7A and Project 7B present their own unique challenges that warrant further investigation.

Therefore, costs for both alternatives will be presented in the final section of this Chapter.

ATTACHMENT 2

5.5 CONCEPTUAL OPINION OF PROBABLE COST
The purpose of this section is to present a conceptual opinion of probable construction cost (OPCC) for each of the recommended improvements to the City’s wastewater collection system in development of the overall Capital Improvement Program (CIP) presented in Chapter 12.0 of this WWMP. Cost estimates prepared for this WWMP are developed in accordance with the guidelines of the Association for the Advancement of Cost Engineering (AACE) International for a Class 5 Estimate. The AACE International defines a Class 5 Estimate as:

Class 5 Estimate: This estimate is prepared based on limited information, where little more than proposed plant type, its location, and the capacity are known. Strategic planning purposes include, but are not limited to, market studies, assessment of viability, evaluation of alternate schemes, project screening, location and evaluation of resource needs and budgeting, and longrange capital planning. Examples of estimating methods used would include cost/capacity curves and factors, scale-up factors, and parametric and modeling techniques. The expected accuracy ranges for this class estimate are -20 to -50 percent on the low side and +30 to +100 percent on the high side.

5.5.1 Cost Estimating Assumptions
Construction and capital cost estimates are presented in March 2023 dollars corresponding to an Engineering News-Record Construction Cost Index (ENRCCI) of 13,176 (all Cities). The project cost estimates include base construction costs and soft costs. The engineering opinion of probable costs for the wastewater collection system falls under Classification Four (Class 5, as defined by Association for the Advancement of Cost Engineering, AACE) with an expected accuracy range of -50% to +100%.

Construction costs were developed based on a combination of equipment quotes supplied from manufacturers, bids on other City wastewater facilities projects, construction cost estimates by Stantec from similar type construction projects, and standard cost estimating guidelines.

Soft costs include a 30 percent mark-up for construction cost estimating and a 35 percent mark-up of the total construction cost for Engineering, Construction Management and Administration which includes engineering design and engineering services during construction, construction administration, construction inspection services, and general administration costs by City.

It is assumed that the recommended facilities will be developed in public ROW or on public property; therefore, land acquisition costs have not been included. Construction costs estimates do not include costs for annual O&M or any allowance for project financing costs.

The development of cost estimates for this recommended CIP involves the following cost estimation methods and assumptions:

1. All of the cost estimates presented in this chapter are expressed in current (March 2023) dollars.

Escalation should be considered in the financial analysis for projects occurring in future years.

ATTACHMENT 2

2. Where the basis for costs was previously estimated, those earlier estimates are escalated to the current ENRCCI value for March 2023.

3. For open-cut gravity sewer construction projects, Stantec’s depth vs diameter unit cost table was used to estimate costs. Stantec’s unit cost database was calibrated to match recent bid estimates provided by the City. These unit costs are included in Appendix G and are assumed to include manholes, excavation/backfill, sheeting and shoring, pipe construction, dewatering, lateral/sewer main connection, repaving, and mobilization/demobilization.

4. For future pump station facilities, construction costs are capacity-based estimates using cost curves, supplemented with cost information from pump station projects in California. The estimates are representative of average site conditions and normal difficulty of construction.

5. For pump station force main piping the assumed unit rates are also included in Appendix G.

These costs are assumed to include excavation/backfill, sheeting and shoring, pipe construction, dewatering, repaving, and mobilization/demobilization.

5.6 RECOMMENDED PROJECTS AND COSTS
The recommended CIP list for the wastewater collection system is presented as Table 5-12. The alternative Project 7B to expand lift stations in the north shed presented in Table 5-13.

The information presented in the tables includes:
• An ID number assigned to the improvement
• Name of the improvement
• Service Area
• Description of the improvement
• Justification for the improvement
• Level of development scenario identified/needed
• Project quantities involved
• Project actions/notes
• Estimated capital cost

ATTACHMENT 2
Table 5-12. Recommended Capital Improvement Plan – Wastewater Collection System ID Name Service
Area Description Justification Quantities Actions/Notes Total
Project
Costs
Scenario 1 Improvements
1 W. Center
Street Trunk
Central
Shed
Upsize the existing 15-
inch sewer to 18-inches
Existing system
model shows
surcharge failing
LOS criteria.
~3,800 LF of
18-inch sewer
pipe
Also included in Chapter 6
condition projects $4,880,000
2 Elm/West North
Street Trunk
Central
Shed
Upsize existing 10-inch
sewer to 15-inches
Existing system
model shows
surcharge failing
LOS criteria.
~4,510 LF of
15-inch sewer
pipe
Also included in Chapter 6
condition projects $5,080,000
3 10-inch East
North Street
Trunk
Central
Shed
Upsize existing 10-inch
sewer to 12-inches
Existing system
model shows
surcharge failing
LOS criteria.
~1,325 LF of
12-inch sewer
pipe
Also included in Chapter 6
condition projects $1,660,000
4 8-inch East
North Street
Trunk
Central
Shed
Upsize existing 8-inch
sewer to 10-inches
Existing system
model shows
surcharge failing
LOS criteria.
~560 LF of 10-
inch sewer pipe
This area could be
monitored as projects 1-3
mitigate most surcharging
identified in this portion of
the system.
$510,000
5 South
Woodward
Trunk Extension
South
Shed
Complete existing south
trunk with new 36-inch
sewer.

Existing system
model shows
insufficient capacity
at Woodward Park
pump station.
~4,030 LF of
36-inch sewer
pipe
This is a previously
identified project and
completes previous south
trunk planning.
$12,640,000
6 Central Union
Road Trunk
Extension
Central
Shed
Replace existing 36-inch
sewer, 24-inch force main,
and Union Road LS with
new deeper 36-inch trunk.

Existing Union Road
lift station suffers
from chronic
mechanical failures,
deterioration, and
operational
concerns.
~5,030 LF of
36-inch sewer
pipe
Also included in Chapter 6
condition projects $16,170,000
ATTACHMENT 2
ID Name Service
Area Description Justification Quantities Actions/Notes Total
Project
Costs
Scenario 2 Improvements
7 North Trunk
Extension on
Airport Way
North
Shed
Replace existing force
main system with 48-inch
gravity sewer
Insufficient capacity
at Woodbridge Park,
Chadwick U5, and
Villa Ticino pump
stations.
~7,670 LF of
48-inch sewer
pipe
Constructability of this
project may be difficult in
an already crowded utility
corridor
$34,340,000
8 S. Main Trunk
to Evans
South
Shed
Replace existing 8-inch
force main with 27-inch
gravity sewer
Insufficient capacity
at Evans pump
station and force
main system.
~2,690 LF 27-
inch sewer pipe
This project may be
combined with Project 5. $7,180,000
9 S. Airport Way
and Yosemite
Ave. (Fishback)
South
Shed
Replace existing 6-inch
force main and 8-inch
gravity sewer with 10-inch
gravity sewer
Discharge from the
Fishback lift station
overwhelms
downstream gravity
sewer.
~2,665 LF 10-
inch sewer pipe
Force main routing in
model may be incorrect
based on discussion with
City staff, general service
design of surrounding
area should consider
options to take lift station
offline.
$3,100,000
10 S. Airport Way
Roberts Estates
to Daniels
South
Shed
Replace existing 6-inch
force main with 10-inch
gravity sewer
Insufficient capacity
at Roberts Estate
pump station.
~1,320 LF of
10-inch sewer
pipe
General service design of
surrounding area should
consider options to take
lift station offline.
$1,750,000
11 Yosemite
Square Lift
Station and
Improvements
South
Shed
Construct new 2.4 Mgal/d
lift station and 15-inch
service area sewer.

Extend 15-inch sewer
downstream of new 8-inch
forcemain.

Provide service to
Yosemite Square
and surrounding
area.
~4,660 LF 15-
inch sewer pipe,

2.4 Mgal/d
pump station,
and ~4,860 LF
8-inch force
main
Force main should be
routed to existing 18-inch
highway crossing. The
highway crossing should
tie into the new 18-inch
sewer in the realignment
of Woodard Avenue.
$12,880,000
ATTACHMENT 2
ID Name Service
Area Description Justification Quantities Actions/Notes Total
Project
Costs
12 Austin Road
Industrial Area
Trunk
South
Shed
New 24 to 18-inch trunk
sewer.

Provide service to
the Austin Road
Industrial Area
~2,355 LF of
18-inch sewer
pipe, ~5,300 LF
of 21-inch
sewer pipe, and
~2,945 LF of
24-inch sewer
pipe
Ties into existing 24-inch
trunk upstream of Evans
lift station.
$20,810,000
13 South Austin
Road -
Industrial Area
South
Shed
Extend 15-inch sewer in
Austin Road.

Provide service to
the northern portion
of the Industrial Area
~4,335 LF of
15-inch sewer
pipe
Ties into Austin Road
Industrial Area Trunk. $5,780,000
Scenario 3 Improvements
14 Yosemite
Square Service
Area
South
Shed New 15-inch trunk sewer.

Provide service to
the southern portion
of the Yosemite
Square service area.
~3,575 LF of
15-inch sewer
pipe
Ties into Yosemite Square
lift station. $4,240,000
15 Oleander
Avenue
Extension/ S.

Airport Way
Sewer
South
Shed
Extend existing 12-inch
sewer in Oleander Avenue
into SOI. Install a new 10-
inch sewer in Airport Way.

Provide service to
southern SOI area.
~2,255 LF of
12-inch sewer
pipe
~3,365 LF 10-
inch sewer
Match existing 12-inch
slope, 0.002 ft/ft. 10-inch
at 0.0025 ft/ft or greater
$6,660,000
16 Highway 99
Crossing at
Northland Road
North
Shed
Construct new 24-inch
sewer and highway
crossing.

Provide service to
northern SOI area.
~3,515 LF of
24-inch sewer
pipe
Ties into existing system
at Tidewater bike path.

Includes highway crossing
$9,310,000
17 East Lathrop
Road Trunk
North
Shed
Construct new 18-inch
and 15-inch sewer.

Provide service to
northern SOI area.
~4,000 LF of
15-inch sewer
pipe, ~3,340 LF
of 18-inch
sewer pipe.

Assumes slope of 0.0015
ft/ft $12,060,000
18 Northland Road
Trunk
North
Shed
Construct new 18-inch
sewer.

Provide service to
northern SOI area.
~3,790 LF of
18-inch sewer
pipe
Drop manhole
recommended at
downstream end to
reduce depth.
$6,630,000
ATTACHMENT 2
ID Name Service
Area Description Justification Quantities Actions/Notes Total
Project
Costs
19 Northland Road
Branches
North
Shed
Construct new 12-inch
sewers.

Provide service to
northern SOI and
planning area.
~5,255 LF of
12-inch sewer
pipe
Variable routing and pipe
sizing depending on
actual development.
$6,350,000
20 Louise/
Nehemiah
Branches
Central
Shed
Construct new 12-inch
sewers.

Provide service to
eastern SOI area.
~5,250 LF of
12-inch sewer
pipe
Ties into Louise and
Pestana Avenue lines. $5,160,000
21 South Union
Road Extension
South
Shed
Extend existing 12-inch
sewer in South Union
Road into SOI.

Provide service to
southern SOI area.
~3,940 LF 12-
inch sewer pipe
Match existing slope,

0.002 ft/ft. $4,590,000
22 Cottage Avenue North
Shed
Construct new 12-inch
sewer.

Provide service to
northern SOI area.
~2,410 LF of
12-inch sewer,
Ties into East Lathrop
Road Trunk. $3,080,000
Scenario 4 Improvements
23 North Shed
Union Road
Trunk
North
Shed
Construct new 30-inch
sewer.

Provide service to
remaining planning
area.
~4,695 LF of
30-inch sewer
pipe
Requires upsizing of
existing 18-inch section of
Union Road sewer.
$13,130,000
24 Manteca
Junction Trunk
North
Shed
Construct new 10-inch
sewer.

Provide service to
remaining planning
area.
~3,010 LF of
10-inch sewer
pipe
Variable pipe size
depending on actual flow
routing and development
conditions.
$3,730,000
25 Lovelace Road -
99 Crossing
North
Shed
Construct new 24 to 15-
inch sewer.

Provide service to
remaining planning
area.
~5,650 LF of
24-inch sewer
pipe and ~3,605
LF of 15-inch
sewer pipe
Includes highway
crossing. $18,090,000
ATTACHMENT 2
Table 5-13. Alternative Project Costs – Project 7B: Expand North Shed Lift Stations ID Name Service
Area Description Justification Quantities Actions/Notes Total
Project
Costs
Scenario 2 Improvements
7B
Expand North
Shed Lift
Stations
North
Shed
Alternative to Project 7
(North Trunk Extension on
Airport Way) Expand
Existing Lift Stations
Insufficient capacity
at Woodbridge
Park, Chadwick U5,
and Villa Ticino.

Woodbridge Park (12.4
Mgal/d)
Chadwick U5 (2.4
Mgal/d)
Villa Ticino (1.0 Mgal/d)
Land acquisition
required. No force
main
improvements.

Note: costs exclude
land acquisition
$29,530,000
ATTACHMENT 2

6.0 WASTEWATER COLLECTION SYSTEM CONDITION

ASSESSMENT
This chapter includes a summary of the sanitary sewer condition assessment conducted by Stantec Consulting Services Inc. (Stantec) in 2017. This assessment included 52,150 lineal feet sewer pipeline from 60-inches to 10-inches in diameter and inspection of 187 manholes. The assessment was summarized in a report titled City of Manteca Sewer Conditions Assessment dated August 2017 (MSCA).

A summary of the MSCA is included to ensure that the recommendations of the assessment are carried through in the overall wastewater Capital Improvement Program (CIP) developed as part of this WWMP.

This chapter is divided into the following sections:
• Background
• Summary of Sewer Conditions Assessment
• Cost Summary of Recommended Projects

6.1 BACKGROUND
The City of Manteca currently operates and maintains approximately a 250 miles of sanitary sewer gravity pipeline including 4,672 sanitary sewer manholes. The City is required to have a Sewer System Management Plan (SSMP) in accordance with the State Water Resources Control Board (SWRCB) General Waste Discharge Requirement (WDR) provisions that requires all publicly owned wastewater dischargers with a collection system greater than one mile in length develop a SSMP. Under Section 6.8 (WDR Section D.13.iv.c) the SSMP is required to develop a rehabilitation and replacement program (Program) to identify and prioritize collection system deficiencies and implement short-term and long-term rehabilitation actions to address each deficiency. This Program includes regular visual and television (TV) inspections of manholes and sewer pipes and a system of ranking the condition of the sewer pipes that are at risk of collapse or prone to more frequent blockages due to pipe defects. Also, the Program should include a capital improvement plan (CIP) that addresses proper maintenance and protection of the sewer collection system assets.

6.2 SUMMARY OF SEWER CONDITIONS ASSESSMENT
The MSCA used the National Association of Sewer Service Companies (NASSCO) rating system to classify sewer collection system defects by the following groups: structural, operation, construction, and miscellaneous. Each individual pipeline segments and manholes were then bundled into areas to develop projects that could be included in a CIP. The report identified the following 14 areas.

1. Heartsong Drive (Project Completed)

2. UPRR Right of Way and Ally Between Center Street and Yosemite Avenue

3. Alley Between Yosemite Avenue and Nevada Street (Project Completed) ATTACHMENT 2

4. West Center Street Trunk (Addressed through capacity improvement Project 1, see Chapter 5.0)

5. Moffat Boulevard and Main Street

6. Elm/West North Street Trunk and 10-inch East North Street Trunk (Addressed through capacity improvement Projects 2 & 3, see Chapter 5.0)

7. Oak Street from Main Street to Willow Avenue

8. Sequoia Avenue from Oregon Street to Alley north of Nevada Street

9. Tidewater Bike Path from Sandalwood Lane to Louis Avenue

10. Walnut Avenue from the alley north of Nevada Street to the UPRR

11. Central Union Road Trunk Extension (Addressed through capacity improvement Project 6, see Chapter 5.0)

12. Louise Avenue (Project Completed)

13. St. Dominic’s Drive from North of Yosemite Avenue to Golf Course

14. Union Road (Project Completed)
Ongoing project work by the City since the MSCA has reduced this list to 10 projects. The projects are shown in Figure 6-1. The following sections provide summaries of each of the 10 remaining projects.

ATTACHMENT 2
C ali fo rni a
Sacramento
San Francisco
Fresno

YOSEMITE AV

WOODWARD AV
HWY 120

MCKINLEY AV

MAIN ST

AIRPORT WY
I5

UNION RD
HWY 120

LOUISE AV
HWY 99

LATHROP RD
Project 28
Project 6
Project 1
Project 30
Project 31
Project 2 & 3
Project 32 Project 29
Project 27
Project 26
4557000 4554000 4551000 4548000
4557000 4554000 4551000 4548000
-13503000 -13500000 -13497000 -13494000 -13491000 -13488000 -13503000 -13500000 -13497000 -13494000 -13491000 -13488000 Legend
Sanitary Manhole
Water Quality
Control Facility
Forcemain
Sanitary Network
Water Quality
Control Facility
Structures
Lift Station
City Owned
Privately Owned
City of Manteca
Limit
Improvement
Project 1
Project 2 & 3
Project 6
Project 26
Project 27
Project 28
Project 29
Project 30
Project 31
Project 32
6-1
City of Manteca
Wastewater Servicing Master Plan
184031535
Manteca,
California
Prepared by EH on 11/2/2023
TR by MA on 11/2/2023
IR Review by MVD on 11/2/2023
Condition Assessment (2017)
Improvements
C:\Users\ehewko\OneDrive - Stantec\Collection_System_MP\02_GIS\Figures\Manteca_Figures.aprx Revised: 2023-11-02 By: ehewko Disclaimer: This document has been prepared based on information provided by others as cited in the Notes section. Stantec has not verified the accuracy and/or completeness of this information and shall not be responsible for any errors or omissions which may be incorporated herein as a result. Stantec assumes no responsibility for data supplied in electronic format, and the recipient accepts full responsibility for verifying the accuracy and completeness of the data.

Project Location
Client/Project
Figure No.

Title
Notes

1. Coordinate System: NAD 1983 StatePlane California III FIPS 0403 Feet

2. Data Sources: City of Manteca

Refer to 320 Airport Way Subdivision
Plans for detailed alignment of CIP 6.

ATTACHMENT 2

6.2.1 Project Summaries
This section provides a brief description of the remaining projects being recommended as future CIPs.

The location of each project area is shown on Figure 6-1.

Project No. 26: UPRR Right of Way and Alley Between Center Street and Yosemite Avenue Location: Alley between Center Street and Yosemite Avenue from west of Sherman Avenue to the intersection of the UPRR right of way and Center Street.

Pipe Material: Vitrified Clay
Pipe Diameter: 12-inch
Approximate Length: 2,750 feet
Number of Manholes: 9
Manhole Material: Unlined Concrete and Brick
Recommendation: Point repair 4 segments of pipeline, dig and replace 3 segments of pipeline, and rehabilitate 9 manholes.

Project No. 1: West Center Street Trunk
Location: Center Street from the intersection of the UPRR right of way to just west of Union Road.

Pipeline Material: Vitrified Clay
Pipe Diameter: 12-inch and 15-inch
Approximate Length: 3,950 feet
Number of Manholes: 16
Manhole Material: Unlined Concrete and Brick
Recommendation: Replace entire alignment with new 18-inch gravity pipeline (See Chapter 5).

Project No. 27: Moffat Boulevard and Main Street
Location: Main Street from Garfield Avenue to Moffat Street then along Main Street to alley north of Yosemite Avenue.

Pipeline Material: Vitrified Clay and one segment of Truss Pipe Pipe Diameter: 10-inch
Approximate Length: 2,900 feet
ATTACHMENT 2
Number of Manholes: 10
Manhole Material: Unlined Concrete and Brick
Recommendation: Dig and replace 3 segments of pipeline, CIPP 5 segments of pipeline.

Project No. 2 and 3: Elm/West North Street Trunk and 10-inch East North Street Trunk Location: North Street from Roosevelt Avenue to Elm Avenue then along Elm Avenue to Center Street.

Pipeline Material: Vitrified Clay
Pipe Diameter: 10-inch
Approximate Length: 7,150 feet
Number of Manholes: 34
Manhole Material: Unlined Concrete and Brick
Recommendation: Replace entire alignment with new 15-inch and 12-inch gravity pipeline (See Chapter 5).

Project No. 28: Oak Street from Main Street to Willow Avenue Location: Oak Street from Main Street to Willow Avenue.

Pipeline Material: Vitrified Clay
Pipe Diameter: 10-inch
Approximate Length: 1,600 feet
Number of Manholes: 7
Manhole Material: Unlined Concrete and Brick
Recommendation: Point repair 4 segments of pipeline and rehabilitate 7 manholes.

Project No. 29: Sequoia Avenue from Oregon Street to Alley North of Nevada Street Location: Sequoia Avenue from Oregon Street to the alley north of Nevada Street.

Pipeline Material: Vitrified Clay
Pipe Diameter: 10-inch
Approximate Length: 1,000 feet
Number of Manholes: 3
ATTACHMENT 2
Manhole Material: Brick
Recommendation: Point repair 1 segment of pipeline, rehabilitate 1 manhole, and replace 2 manholes.

Project No. 30: Tidewater Bike Path from Sandalwood Lane to Louis Avenue Location: Along Tidewater Bike Path from Sandalwood Lane to Louis Avenue.

Pipeline Material: Vitrified Clay
Pipe Diameter: 12-inch
Approximate Length: 3,150 feet
Number of Manholes: 9
Manhole Material: Unlined Concrete
Recommendation: Point repair 1 segment pipeline, dig and replace 2 segments of pipeline, and rehabilitate 9 manholes.

Project No. 31: Walnut Avenue from the alley north of Nevada Street to the UPRR Location: Walnut Avenue from the alley north of Nevada Street to the UPRR right of way.

Pipeline Material: Vitrified Clay
Pipe Diameter: 10-inch
Approximate Length: 1,900 feet
Number of Manholes: 7 and 1 Lamphole
Manhole Material: Unlined Concrete and Brick
Recommendation: Point repair 3 segments of pipeline, dig and replace 1 segment of pipeline, CIPP 1 segment of pipeline, replace frame/cover on 2 manholes, and rehabilitate 7 manholes.

Project No. 6: Central Union Road Trunk Extension
Location: From the golf course maintenance yard located west of Union Road, north of Center Street to 1,300 feet north of Yosemite Avenue just west of Airport Way.

Pipeline Material: Reinforced Concrete and Spiral Wound Lined Pipe Pipe Diameter: 30-inch and 36-inch
Approximate Length: 5,200 feet
Number of Manholes: 16
ATTACHMENT 2
Manhole Material: Unlined Concrete
Recommendation: Replace with new gravity pipeline and decommission Union Road Pump Station (See Chapter 5).

Project No. 32: St. Dominic’s Drive from North of Yosemite Avenue to Golf Course Location: Saint Dominic’s Drive from just north of Yosemite Avenue to just south of the golf course.

Pipeline Material: Polyvinyl Chloride
Pipe Diameter: 12-inch
Approximate Length: 900 feet
Number of Manholes: 4
Manhole Material: Unlined Concrete
Recommendation: Rehabilitate 4 manholes.

6.3 SUMMARY OF RECOMMENDATIONS
Table 6-1 summarizes the combined pipeline and manhole repair, rehabilitation, and replacement costs for each project area. Costs for projects that overlap with recommended capacity improvements are presented in Chapter 5. In addition to the improvements to the existing areas, the City should continue inspecting the remainder of their system. Recommendations from the SSMP should be implemented to continue cleaning and inspecting the pipelines (250 miles) and manholes (4,700 manholes) within the system at a rate of approximately 5% to 10% per year, respectively.

Table 6-1. Summary of Project Repair/Rehabilitation/Replacement Costs ID Description Cost
26 UPRR Right of Way and Ally Between Center Street and Yosemite $489,000 27 Moffat Boulevard and Main Street $1,022,000
28 Oak Street from Main Street to Willow Avenue $98,000 29 Sequoia Avenue from Oregon Street to Alley North of Nevada Street $53,000 30 Tidewater Bike Path from Sandalwood Lane to Louis Avenue $348,000 31 Walnut Avenue from the alley north of Nevada Street to the UPRR $279,000 32 St. Dominic’s Drive from North of Yosemite Avenue to Golf Course $29,000 Total $2,318,000
ATTACHMENT 2

7.0 WASTEWATER QUALITY CONTROL FACILITY (WQCF)

BACKGROUND AND REGULATORY REQUIREMENTS
The Manteca Wastewater Quality Control Facility (WQCF) is located southwest of downtown Manteca at 2450 West Yosemite Avenue. The WQCF treats typical municipal wastewater generated in the City of Manteca (City), Raymus Village, Oakwood Shores, and the neighboring City of Lathrop. The plant also receives seasonal discharges from a local food processor (Eckert Cold Storage).

This chapter includes the following sections:
• WQCF Background
• Regulatory Requirements
• Thermal Plan Compliance

7.1 WQCF BACKGROUND
The Manteca WQCF began operation in 1959. The original facility was an oxidation pond that discharged effluent to the surrounding land for agricultural irrigation. In 1970, the facility was upgraded with preliminary and primary treatment facilities and aerobic sludge digestion. Effluent continued to be used for agricultural irrigation. In 1986-1988, as part of the Clean Water Grant Program, a major expansion to the facility was constructed. This Phase I Expansion Project included the construction of primary sedimentation basins, secondary treatment facilities (biological towers and aeration basins), secondary clarifiers, anaerobic sludge digesters, sludge drying beds, a chlorine disinfection system, and an outfall to the San Joaquin River. In 1992-1993 a Phase II Expansion Project added a primary sedimentation basin, secondary clarifier, and four sludge drying beds. Starting in 2001 the Phase III Expansion Project was constructed in a series of Schedules (A, B, C, and D) over a period of several years.

The Phase III Expansion Project separated the main treatment processes into the Northside and Southside Plants. Schedule A improvements included the construction of two new aeration basins, modifications to three existing secondary clarifier sludge collection mechanisms, and replacement of two existing centrifugal blowers with larger units within the Northside plant. As part of the Schedule A improvements, the City also procured a skid-mounted centrifugal dewatering system to dewater anaerobically digested primary and secondary sludges to augment the existing drying bed facilities.

Schedule A improvements were completed in 2003.

Phase III Schedule B improvements included the construction of a new headworks and influent pump station, two aerated grit tanks, three primary sedimentation basins, five aeration basins, two secondary clarifiers, and an odor control biofilter for the Northside plant. Schedule B improvements also included the expansion of the existing Laboratory and Administration Building. Schedule B improvements were substantially completed in 2005.

Phase III Schedule C improvements included a mechanical dewatering facility. The skid-mounted centrifugal dewatering system acquired under Schedule A was relocated to a new dewatering building.

ATTACHMENT 2
Other improvements included a Shop Maintenance Building and a paved biosolids stockpile area.

Schedule C improvements were completed in 2008.

Phase III Schedule D improvements included the construction of a secondary effluent equalization pond, filter feed pump station, coagulation and flocculation facilities, tertiary filters, a chemical storage and handling facility, a UV disinfection system, an effluent pumping station, and two odor control biofilters. In addition to flow attenuation, the secondary effluent equalization pond was designed to store water during periods of reverse river flow due to tidal influence in the San Joaquin River. Schedule D improvements were completed in 2007. The biological towers completed during Phase 1 were taken out of service after the completion of the Phase II Schedule D improvements.

Under the Industrial Pipeline Project (IPP-3), the existing secondary effluent storage pond was modified to create a second lined pond for food processing wastewater from Eckert Cold Storage (Eckert). High strength Eckert wastewater had been co-mingled with domestic wastewater and processed through the WQCF prior to disposal. lPP-3 was the final component in a source separation program designed to allow independent treatment of Eckert wastewater prior to land application at the WQCF. The IPP-3 was completed in 2009.

An aerial view of the Manteca Wastewater Quality Control Facility (WQCF) is shown in Figure 7-1. A process flow diagram of the WQCF is shown on Figure 7-2.

ATTACHMENT 2

HEADWORKS/SCREENS

INFLUENT PUMP STATION

SEPTAGE RECEIVING STATION

FOG RECEIVING

FOOD WASTE RECEIVING

BIOGAS SULFATREAT SYSTEM

ODOR CONTROL BIOFILTER

CHLORINE BUILDING

NORTHSIDE AERATED GRIT TANKS

NORTHSIDE PRIMARY SEDIMENTATION BASINS

NORTHSIDE AERATION BASINS
SECONDARY CLARIFIER NO.1
SECONDARY CLARIFIER NO.2
SECONDARY CLARIFIER NO.3
NORTHSIDE RAS & N.S. WAS PUMP STATION

SOUTHSIDE AERATED GRIT TANKS

SOUTHSIDE PRIMARY SEDIMENTATION BASINS

SOUTHSIDE AERATION BASINS

SOUTHSIDE MCC BUILDING
SECONDARY CLARIFIER NO.4
SECONDARY CLARIFIER NO.5
SEC. CLARIFIERS NO.4 & NO.5 SPLITTER BOX

SOUTHSIDE RAS PUMP STATION

FILTER FEED PUMP STATION
CHEMICAL BUILDING 2

RAPID MIX AND FLOCCULATION TANKS

TERTIARY FILTERS

UV DISINFECTION

EFFLUENT PUMP STATION

EFFLUENT MCC/GENERATOR BUILDING

CHLORINE CONTACT TANK

IRRIGATION PUMP STATION

RECYCLE WATER PUMP STATION

SECONDARY EFFLUENT EQUALIZATION POND

SECONDARY EFFLUENT STORAGE POND

ECKERT POND

DISSOLVED AIR FLOTATION TANKS

COLLECTIONS STORAGE BUILDING
DIGESTER NO.1
DIGESTER NO.2

DIGESTER CONTROL BUILDING
DIGESTER NO.3
DIGESTER NO.4

SLUDGE BLENDING TANK

DEWATERING BUILDING

DEWATERED SLUDGE LOADING AREA

RCNG GAS STORAGE/CONDITIONING
BIOCNG

CNG/TRUCK LOADING
FLARE

NORTH SLUDGE DRYING BEDS

ADMIN BUILDING

LABORATORY

SHOP/MAINTENANCE BUILDING

TRAINING/LOCKER ROOM OPERATION BUILDING

BIOTOWERS

STAFF LOCKER ROOM
0 60 120 180 240 300
FEET
123456789
10 11
12 13
14 15
16 17
18 19
20 21
22 23
24 25
26 27
28 29
30 31
32 33
34 35
36 37
38 39
40 41
42 43
44 45
46 47
48 49
50 51
52 53
54 55
56 57
57 12
3 4
5 6
7 8
9 10
11 12
13 14
15 17 16
18 19
21 20
22 23
25 24
26 29 28 27
30 31
32 33
34 36 35
37 38
39 40
41 42 43
44 45
46 47
48 49
50 51
52 53
54 55
56 Figure 2-1
WQCF Site Layout
V:\1840\active\184031483\drawing\graphics\__________.ai mlm 03-03-2022 City of Manteca

WASTEWATER QUALITY CONTROL FACILITY
OPERATIONS AND MAINTENANCE MANUAL DRAFT Figure 7-1
WQCF Existing Site Layout
U:\184031535\drawing\graphics\manteca_wqcf__________.ai mlm march-2023 ATTACHMENT 2
ML
ML
DWS
ML

CENTRATE

BACKWASH
FEF

BACKWASH

CENTRATE
3 GAS

CONDITIONING

CNG/TRUCK

CHLORINE

CONTACT RECLAIMED
FLOW
BIOCNG
4 ML
BILL
VALVE
SEE CHAPTER 18

FOR DETAILED

DIGESTER DIAGRAM

NORTHSIDE FACILITIES

SOUTHSIDE FACILITIES
Equipment
or
Legend
Pump
Butterfly Valve (BFV)
Motorized Operator
Gate
Valve
Mag Meter
Palmer Bowlus Flume
Sanitary Sewer (SS)
Primary Effluent (PE)
Mixed Liquor (ML)
Secondary Effluent (SE)
Tertiary Effluent (TE)
Final Effluent (FE)
Return Activated Sludge (RAS)
Waste Activated Sludge (WAS)
Scum (SC)
Primary Sludge (PS)
Thickened Sludge (TS)
Thickened Sludge Overflow (TSO)
Digested Sludge (DS)
Dewatered Sludge (DWS)
Digester Gas (DG)
Sanitary Drain (SD)/Backwash/Centrate
Screenings/Grit
Foul Air (FA)
Figure 2-2
WQCF Process Flow Diagram
V:\1840\active\184031483\drawing\graphics\__________.ai mlm 03-03-2022 City of Manteca

WASTEWATER QUALITY CONTROL FACILITY
OPERATIONS AND MAINTENANCE MANUAL DRAFT Figure 7-2
Existing WQCF Process Flow Diagram
U:\184031535\drawing\graphics\manteca_wqcf__________.ai mlm march-2023 ATTACHMENT 2

7.2 REGULATORY REQUIREMENTS
The purpose of this section is to provide an overview of the regulatory requirements for the WQCF and provide insight into potential changes that may be adopted with future regulations.

The City WQCF is currently regulated by National Pollutant Discharge Elimination System (NPDES) CA0081558 Order R5-2021-0003 (Order). The Order serves as Waste Discharge Requirements (WDR) pursuant to the California Water Code (Section 13260) and Federal Clean Water Act (Section 402).

NPDES orders are renewed on a five-year cycle to reflect changes in policy interpretation, updates to regulation and policy regarding the disposal of wastewater, variations in effluent quality, and public input.

The current Order became effective on April 1, 2021 and expires on March 31, 2026.

7.2.1 Order Limitations

7.2.1.1 Effluent Discharge Limitations to San Joaquin River The Order describes explicit effluent limitations for discharge to the San Joaquin River. Some of the key effluent limitations are summarized in Table 7-1.

Table 7-1. Select Order Effluent Limitations for Discharge to San Joaquin River Parameter Concentration
BOD5
Average Monthly, mg/L 10
Average Weekly, mg/L 15
TSS
Average Monthly, mg/L 10
Average Weekly, mg/L 15
Ammonia Nitrogen (as N) from April 1st to November 30th 1 Monthly Average, mg N/L 2.0
Weekly Average, mg N/L 4.2
Ammonia Nitrogen (as N) from December 1st to March 31st 1 Monthly Average, mg N/L 2.5
Weekly Average, mg N/L 6.2
Nitrate plus Nitrite as N
Average Monthly, mg N/L 10
Average Weekly, mg N/L 15.3
Note:
1 Loading limits for ammonia nitrogen are regulated based on the concentration (mg N/L) x average dry weather flow effluent limit (Mgal/d) x 8.34 conversion factor.

Key:

BOD5 = Biochemical Oxygen Demand, 5-day at 20°C
mg/L = milligrams per liter
TSS = Total Suspended Solids
ATTACHMENT 2
Additional effluent discharge limitations include:
• pH: The pH shall not be depressed below 6.5 nor raised above 8.5. • Percent Removal: The average monthly percent removal of BOD5 and TSS shall not be less than 85%.
• Acute Whole Effluent Toxicity: Survival of aquatic organisms in a 96-hour bioassay of effluent shall equal or exceed 70% in each assay and 90% as a median for any three consecutive assays.
• Temperature: The maximum temperature of the discharge shall not exceed the natural receiving water temperature by more than 20°F.
• Total Coliform: Total coliform organisms shall not exceed 2.2 most probable number per 100 mL (MPN/100mL) as a 7-day median, 23 MPN/100mL more than once in a 30-day period, or 240 MPN/100mL at any time.
• Chlorpyrifos and Diazinon: The sum of average monthly effluent limitation (Samel) shall be less than 1.0, and the sum of average weekly effluent limitation (Sawel) shall be less than 1.0 using the following equations:

Samel = Average Monthly Diazinon (µg/L)

0.079
+ Average Monthly Chlorpyrifos (µg/L)

0.012
≤ 1.0
Sawel = Average Weekly Diazinon (µg/L)

0.14 + Average Weekly Chlorpyrifos (µg/L)0.021
≤ 1.0
• Electrical Conductivity (EC) at 25°C: The effluent calendar year annual average EC shall not exceed 1,000 μmhos/cm.
• Methylmercury: Effective 31 December 2030, the effluent calendar year annual methylmercury load shall not exceed 0.38 grams, in accordance with the Delta Mercury Control Program. • Mercury, total: Effective immediately and until 30 December 2030, for a calendar year, the total annual mass discharge of total mercury shall not exceed 90 grams/year. This interim effluent limitation shall apply in lieu of the final effluent limitation for methylmercury.

7.2.1.2 Receiving Water Limitations
Receiving water limitations have been implemented to prevent discharge of materials that cause or contribute to nuisance or to adverse impacts on beneficial uses of the San Joaquin River. There are also limitations to prevent detrimental responses in human, plant, animal, or aquatic life. Some of these limitations have specific and/or numerical limits and are presented below.

ATTACHMENT 2
The discharge shall not cause the following in San Joaquin River:
• Biostimulatory Substances: Water to contain biostimulatory substances which promote aquatic growths in concentrations that cause nuisance or adversely affect beneficial uses. • Chemical Constituents: Chemical constituents to be present in concentrations that adversely affect beneficial uses.
• Color: Discoloration that causes nuisance or adversely affects beneficial uses. • Dissolved Oxygen: The dissolved oxygen concentration to be reduced below 5.0 mg/L at any time.
• Floating Material: Floating material to be present in amounts that cause nuisance or adversely affect beneficial uses.
• Oil and Grease: Oils, greases, waxes, or other materials to be present in concentrations that cause nuisance, result in a visible film or coating on the surface of the water or on objects in the water, or otherwise adversely affect beneficial uses.
• pH: The pH to be depressed below 6.5 nor raised above 8.5. • Pesticides: Should not be present in water, sediments, or aquatic life in concentrations that affect beneficial uses. Total identifiable persistent chlorinated hydrocarbon pesticides should not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by U.S. EPA or the Executive Officer. Pesticide concentrations should be the lowest technically and economically achievable and consistent with antidegradation policies.

Pesticide concentrations should not exceed maximum contaminant levels (MCLs). Thiobencarb shall be 1.0 µg/L or less.
• Radioactivity: Radionuclides shall be below MCLs specified in Table 64442 of section 64442 and Table 64443 of section 64443 of Title 22 of the California Code of Regulations, and their concentration in water and the food web shall be below levels that are harmful to human, plant, animal, or aquatic life.
• Suspended Sediments: The suspended sediment load and suspended sediment discharge rate of surface waters to be altered in such a manner as to cause nuisance or adversely affect beneficial uses.
• Settleable Substances: Substances to be present in concentrations that result in the deposition of material that causes nuisance or adversely affects beneficial uses. • Suspended Material: Suspended material to be present in concentrations that cause nuisance or adversely affect beneficial uses.

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• Taste and Odors: Taste- or odor-producing substances to be present in concentrations that impart undesirable tastes or odors to fish flesh or other edible products of aquatic origin, or that cause nuisance, or otherwise adversely affect beneficial uses. • Temperature: 1) The creation of a zone, defined by water temperatures of more than 1°F above natural receiving water temperature, which exceeds 25% of the cross-sectional area of the river channel at any point; and 2) a surface water temperature increase greater than 4°F above the natural temperature of the receiving water at any time or place. • Toxicity: Toxic substances to be present, individually or in combination, in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. • Turbidity: Shall not exceed 2 Nephelometric Turbidity Units (NTU) where natural turbidity is less than 1 NTU, nor the limits presented in Table 7-2.

Table 7-2. Maximum Turbidity Limits
Natural Turbidity (NTU) 1 - 5 5 - 50 50 – 100 >100
Increase limit <1 NTU <20% <10 NTU <10%
In addition to the above surface water limitations, the Order contains groundwater limitations. Release of waste constituents from any portion of the WQCF shall not cause groundwater to:
• Contain any of the below constituents in concentrations statistically greater than water quality objectives (WQO) or natural background quality, whichever is greater. − Total Coliforms Organisms
 WQO: less than 2.2 MPN/100mL as a 7-day median
 Ambient background quality: less than 2 MPN/100mL
− TDS
 WQO: 1,070 mg/L
 Ambient background quality: 280 mg/L
− Total Nitrate Nitrogen (effective 1 April 2026)
 WQO: 10 mg/L
 Ambient background quality: 15.3 mg/L
• Exhibit a pH less than 6.5 or greater than 8.4.
• Impart taste, odor, chemical constituents, toxicity, or color that creates nuisance or impairs any beneficial use.

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7.2.1.3 Land Application Limitations
Recycled water applied to Land Application Areas (City owned agricultural fields) contains undisinfected secondary municipal wastewater and food processing wastewater from Eckert Cold Storage. In addition to complying with specifications detailed in the Order (e.g., setback requirements, use requirements, use area management requirements, etc.), the WQCF must also comply with the following loading limitations and triggers for the application of recycled water to the Land Application Areas. Section 9.10 describes the existing effluent handling and disposal facilities, including the existing land disposal system. • Hydraulic Loading. The volume of recycled water and supplemental irrigation water (if any) applied to the use areas shall not exceed agronomic rates based on the vegetation grown, predischarge soil moisture conditions, and weather conditions. • Total Nitrogen. Crops shall be grown on the use areas and cropping activities shall be managed to take up the nitrogen applied, including any fertilizers and manure. The total nitrogen mass loading to the land Application Areas shall not exceed the agronomic rate for the crop grown. • BOD5 Loading. The maximum daily mass of BOD5 applied to the Land Application Areas shall not exceed 300 lbs/acre/day.
• Total Dissolved Solids (TDS) Trigger. If the calendar annual average TDS concentration exceeds 600 mg/L, this represents an increase over current performance-based discharge levels, and therefore the City must conduct an evaluation to determine the reason(s) for the increased TDS concentration. The evaluation shall include an explanation of the increased concentrations and the City’s determination if it represents an increase in mass loading of TDS to the Land Application Areas that would require an Antidegradation Analysis update to demonstrate the increased mass loading is consistent with the Antidegradation Policy.

7.2.1.4 Recycled Water Limitations
The WQCF also produces Title 22 disinfected tertiary recycled water for construction purposes and dust control, sanitary sewer cleaning, and landscape irrigation. The use of the Title 22 disinfected tertiary recycled water is regulated under the State Water Resources Control Board Recycled Water General Order WQ 2016-0068-DDW. The use of the recycled water is beyond the scope of this report. The production of the recycled water is regulated under the NPDES permit. Regarding production, in addition NPDES permit effluent total coliform limitation, the NPDES permit includes the following limitation. • Turbidity. The filter effluent turbidity shall not exceed 2 NTU as a daily average, 5 NTU more than 5% of the time within a 24-hour period, and 10 NTU at any time.

7.2.2 Competing Regulations
The State of California has adopted competing regulations that will impact the WQCF capacity and effluent quality, in particular:

ATTACHMENT 2
• SB 606 and AB 1688, Water Management Planning (which limits indoor potable water use to 50 gpd/capita by 2030)
• SB 1383, Short-Lived Climate Pollutants Reduction Act (which limits methane emissions to 40% below 2013 levels and reducing disposal of organic waste by 75% from the 2014 levels by 2025) • Basin Plan Amendments, including salt control programs

7.2.2.1 SB 606 and AB 1688, Water Management Planning
SB 606 and AB 1688 limit indoor potable water use to 50 gpcd by 2030. For the City of Manteca, this means the residents will have to reduce their current water use by approximately 22% (based on the current estimated usage of 61 gpcd). It is noted that when water is conserved, the mass of pollutants discharged by each person is then carried to the treatment plant in less water, resulting in higher pollutant concentrations. The complication of increasing wastewater influent concentrations is documented in the flows and loads section, Section 7-2, and described herein to note the important implications that water conservation has on the capacity of the WQCF.

This level of water conservation will cause the design organic loading of the plant to be reached before the hydraulic design flow. This further complicates compliance with pollutants that are not removed from the existing process facilities, because they are in such low concentrations or they are not currently permitted (such as salinity, PFAS, pharmaceuticals, pesticides, etc.). A discussion of appropriate treatment technologies for removal of these pollutants is provided in Chapter 10.

7.2.2.2 SB 1383, Short-Lived Climate Pollutants Reduction Act SB 1383 limits methane emissions to 40-percent below 2013 levels and reduces disposal of organic waste by 75-percent from the 2014 levels by 2025. To achieve the goals of this regulation, a key strategy is to divert organic waste from landfills and send the food waste to municipal wastewater treatment facilities for co-digestion in anaerobic digesters, making beneficial use of biogas. However, the diverted organic waste will take up valuable volume in digesters and solids handling facilities that would otherwise be used for wastewater sludge. Further, food waste will increase salinity loading to the plant, as further discussed below. The impacts of food waste were considered when evaluating improvements options at the WQCF, as detailed in Chapters 9 and 10.

7.2.2.3 Salinity
The Regional Water Quality Control Board (Regional Board) amended its Basin Plan to implement a longterm program to control salinity and nitrate build-up in the Central Valley, with input from all stakeholders (agriculture, cities, industries, environmentalists, economists, etc.) and as recommended by the CVSALTS Initiative. The Basin Plan amendments were approved by the EPA and Office of Administrative Law (OAL) on January 15, 2020, which became the effective date for the Basin Plan Amendments and policies identified therein. One of the major aspects of the amendments includes a Salt Control Program, described below.

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Salt Control Program
The Salt Control Program established in the Basin Plan will be implemented in three phases, with each phase expected to take 10 to 15 years, according to the Basin Plan. The initial phase required the City to select either the “Conservative Salinity Permitting Approach” (which applies the Water Quality Objectives of 700 μS/cm, along with other requirements) or the “Alternative Salinity Permitting Approach” (which allows Agencies to join regional efforts to study salinity effects on the ecosystem). Since the City currently does not meet the water quality objectives, the WQCF is operating under the Alternative Approach. For more information and updates in the Salt Control Program (such as outcomes and recommendations from Phase 1 and plans for Phases 2 and 3), the City may visit the Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) website.

Future Salinity Compliance
Increased water conservation in the City, including State mandated reclamation and water conservation requirements (SB 606 and AB1688, described above), will inhibit compliance with water quality objectives for salinity. Additionally, if the City decides to receive food waste at the WQCF (to comply with SB1383) the concentrated food slurry may further inhibit compliance with water quality objectives. These external compliance pressures are noted herein to highlight the complexity of competing State interests and help make informed decisions about expansion options. Notably, extreme water conservation has a direct effect on wastewater influent and will increase salinity concentrations entering the WQCF, as identified in Table 7-3. The mass of pollutants (salt) discharged by each person remains unchanged regardless of water use, but because the mass is conveyed with less water (during water conservation measures), it results in higher pollutant concentrations arriving at the WQCF.

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Table 7-3. Water Conservation Effect on Salinity
Parameter 1 Existing
Conditions
Interim
Conditions
Future
Conditions
Flow (Mgal/d) 2 7.13 9.23 19.6
Indoor Water Usage (gpcpd) 61 50 50
Potable Water Source EC (µS/cm) 3 505 505 505
EC added after Potable Water Use (µS/cm) 4 597 730 730
Influent EC (µS/cm) 2 1102 1236 1236
Effluent EC (µS/cm) 5 789 884 884
Maximum Permitted EC 1000 700 700
Required Salinity Reduction No Yes Yes
Fraction of Salinity to be Removed 0% 21% 21%
Required Reverse Osmosis (Mgal/d) 6 -- 2.4 5.0
Notes:
1 Does not include impacts from food waste or FOG, as quantity and quality of food/FOG receiving is currently unknown. 2 Includes in-plant recycle flows. 3
Increasing EC from any source (potable water or downstream water uses) will further exacerbate permit compliance. 4 Salinity is added to potable water concentrations through people’s diets, cleaning products, agricultural runoff, etc. 5 Assumes current treatment plant EC removal efficiency will remain (28.4% based on the average influent and effluent EC concentrations from 2010-2022. 6
Assumes brine flow is negligible. Based on an RO EC removal efficiency of 90% and a safety factor of 1.1.

Key:

Mgal/d = million gallons per day
gpcpd = gallons per capita per day
EC = electrical conductivity
µS/cm = microsiemens per centimeter
As shown in Table 7-3, the wastewater effluent salinity concentration (as estimated with EC) would be expected to increase to 884 µS/cm with the mandated water conservation. This exceeds the anticipated future permit limits (700 µS/cm). The other items that may increase salinity materially are described below:
• The salinity of the City’s potable water supply increases, such as by deterioration of existing sources and/or by acquisition of new, more saline sources. • The City permits commercial/industrial salt loads and/or concentrations to increase, such as by new “salt” industries, increased water conservation by existing industries, salt-impacting changes in processes used by existing industries, etc.
• The introduction of food waste and/or fats, oil, and grease (FOG).

To reduce salt at the WQCF, RO would be used most likely because other salinity reduction technologies such as nanofiltration (NF), electrodialysis reversal (EDR), and ion exchange tend to leave the more problematic ions, such as sodium and chloride, in the water. However, in 30 years there may be a ATTACHMENT 2
completely new salt removal technology based on current world-wide research and development of new salt removal technologies, including those identified through the Department of Energy’s Water Security Grand Challenge. For now, the City should plan on possible future implementation of RO but can remain flexible to adapt to other technologies that may become available before salinity removal is implemented.

As the City moves forward with expanding the capacity of the WQCF, a reasonable question is whether the expansion should be “in kind” with the existing process, or should be with a newer technology, specifically an MBR (membrane bioreactor). In developing an answer, many factors will be considered including near-term and long-term costs, best professional judgement by the design and operations team, and the Basin Plan amendments, Chapter 10 incorporates these issues into the detailed evaluation. It must be noted that an MBR would not remove any salinity but can act as a pretreatment step in conjunction with a salinity removal system. This is illustrated in Table 7-4, which shows treatment steps needed to facilitate RO based on plant expansion in-kind versus plant expansion with MBR.

Table 7-4. Stepwise Unit Processes to Achieve RO Treatment

1. In-Kind Treatment 1. MBR-Based Treatment
a. Headworks a. New Headworks for MBR Train
b. Primary Clarifiers b. Primary Clarifiers
c. “Large” Reactor Basins (including anoxic
basins for denitrification)
c. “Small” Reactor Basins (including anoxic
basins for denitrification)
d. Clarifiers d. MBR basins
e. Disc filters

2. Side-Stream RO Pretreatment 2. Side-Stream RO Pretreatment a. Microfiltration/ultrafiltration (MF/UF) a. Cartridge filters b. Cartridge filters b. Chemical conditioning (acid, biocide, chloramine, etc.)
c. Chemical conditioning (acid, biocide,
chloramine, etc.)

3. Side-Stream RO treatment 3. Side-Stream RO treatment

4. Full Stream Disinfection 4. Full Stream Disinfection As shown above, in order to reduce salinity at the WQCF, side-stream treatment (i.e., reverse osmosis) is required, which requires a pre-treatment step that includes membrane filtration, cartridge filters, and chemical conditioning. A potential benefit of installing an MBR in the next expansion project is that it would serve the dual purposes of providing the City with additional capacity and a pre-treatment step for a possible future RO salinity reduction process. This potential benefit and the likelihood of needing to implement RO in the foreseeable future is recognized in the overall treatment system alternative analysis detailed in Chapter 10.

7.2.3 Future Compliance Considerations
Long-term compliance is also dependent on future permit requirements, which may include more stringent or added provisions for salinity (described above), biological interferences, pesticides, and contaminants of emerging concern (CEC). These constituent considerations are discussed below.

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7.2.3.1 Pesticides
The impacts of pesticides, including insecticides, herbicides, and fungicides, on water quality and aquatic habitats will continue to drive implementation of control programs and development of discharge limits.

This has resulted in the inclusion of chlorpyrifos and diazinon limits in the WDR, even when there is no reasonable potential for impacts. Discharge limits for pyrethroid pesticides were adopted in the San Joaquin River Basin Plan and became effective in December 2006, but numerical limits are not specified in the WDR. The Basin is also listed as impaired by Group A pesticides, including organochlorine pesticides, but a TMDL has not been developed and numerical limits are not included in the permit.

Future developments in these types of chemicals will require additional analysis of effluent chemistry and potentially require additional treatment to comply.

7.2.3.2 Constituents of Emerging Concern (CEC)
CEC, including pharmaceuticals and endocrine disrupting compounds, such as hormones, at variable concentrations have been detected in treated effluent from conventional wastewater treatment plants.

However, numeric requirements for removal of CEC appear to be unlikely for the foreseeable future. If CEC removal becomes an issue with the current surface water discharge, use of advanced oxidation processes, such as ozonation, combined with biological activated carbon filtration can be considered.

7.3 THERMAL PLAN COMPLIANCE
The WQCF currently disposes of final effluent (the portion not delivered to reclamation) via a 36-inch diameter pipe discharging to the San Joaquin River just south of the railroad bridge upstream of the I-5 bridge at the I-5/CA-120 interchange. There is no diffuser and the pipe discharges on the side of the bank with a concrete apron. The discharge location is shown on Figures 7-3.

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Manteca WQCF Outfall Discharge Location
Manteca WQCF Discharge into San Joaquin River
Figure 7-3. WQCF Outfall Discharge Location
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The existing NPDES permit currently limits the maximum flow capacity of the WQCF to 9.87 Mgal/d ADWF. However, it should be noted that what is missing from the permit’s capacity definition is that the secondary treatment processes are limited by biological loading rates (not hydraulic loading). Based on the report titled, City of Manteca WQCF 2021 Capacity Assessment, prepared by HERWIT Engineering and Stantec in March 2022 (hereafter referred to as the WQCF 2021 Capacity Assessment), the actual capacity of the existing secondary treatment system with interim improvements is 8.23 Mgal/d ADWF (excluding in-plant recycle flows), as discussed in Chapter 8. The NPDES permit allows for a ADWF increase up to 17.5 Mdal/d. In order to increase the permitted ADWF to 17.5 Mgal/d (and subsequently increase the allowable flow to be discharged to the San Joaquin River), the City is required by permit complete the following actions 1) complete construction of the Phase IV Upgrade and Expansion Project (as described in the Discharger’s April 2014 NPDES Permit Renewal); 2) submit a request to the Central Valley Water Board to increase the permitted discharge flow rate; and 3) demonstrate compliance with the effluent limitations and the receiving water limitations. The increase in the permitted discharge flow rate shall not be effective until the Executive Officer verifies the Phase IV Upgrade and Expansion Project was completed as described and approves the City’s request.

In compliance with the California Environmental Quality Act (CEQA), the City prepared and submitted for public review a Draft Environmental Impact Report (DEIR) that addressed the future Phase IV Upgrade and Expansion Project. Since the City determined that it is impracticable to acquire additional agricultural fields (though they are seeking to expand their Title 22 recycled water program through uses such as baseball fields and parks), the increased discharge will be primarily for effluent discharges to the San Joaquin River. The City performed extensive hydrodynamic and thermal modeling as part of the DEIR to determine the effects of the increased effluent discharge flow to the San Joaquin River and to the Sacramento-San Joaquin Delta downstream of the discharge. This modeling is detailed in the following reports.
• Technical Memorandum (TM) – CORMIX Investigation of Cooling Facilities Operations (DRAFT), Larry Walker Associates, February 2008.
• Thermal Plan Exception Analysis Final Report, Larry Walker Associates, Resource Management Associates, Hanson Environmental, Inc. February 2006.

The models showed that 9.87 Mgal/d discharge at times could violate the “Thermal Plan” provisions without special operation of the effluent discharge pumping system when low river flows and high effluent temperatures were encountered. The referenced “Thermal Plan” is the “Water Quality Control Plan for Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays and Estuaries of California”. The models also showed that the 17.5 Mgal/d discharge would violate the Thermal Plan limits.

The purpose of these two reports were to analyze the impact of the effluent discharge on the San Joaquin River aquatic species, including salmon runs. Based on these reports, an exception to the Thermal Plan was requested by Manteca from the RWQCB. This request was denied and the permitted flow expansion to 17.5 Mgal/d is only allowed under the existing NPDES permit if compliance with the Thermal Plan limits is achieved. Construction of cooling towers was therefore included in the Phase IV Upgrade and Expansion Project description to the Regional Water Board. The cooling facilities would be designed to reduce temperature of the treated effluent such that the effluent discharge and associated size of the ATTACHMENT 2
thermal plume will comply with Thermal Plan provisions as necessary to protect sensitive aquatic life.

The cooling towers are described in more detail in Chapter 10.

Measurement of final effluent temperature, and the river temperature upstream and downstream of the discharge location is also a requirement under the current NPDES permit. A comparison of recent effluent discharge and river temperatures from 2016 through 2021 has shown an increase in the temperature difference between the effluent and the river of 2°F to 5°F over what was used for all previous modeling.

Therefore, a new river modelling study is recommended before proceeding with the design and construction of cooling towers, or other methods of cooling, to validate compliance with the Thermal Plan.

Thermal Plan compliance and possible options for compliance are further discussed in Chapter 10.

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8.0 WQCF WASTEWATER FLOWS AND LOADS

8.1 HISTORICAL AND DESIGN FLOWS AND LOADS
Historical influent flows from January 2016 through February 2021 are shown in Figure 8-1. The 365-day average flow values are centered averages based on available data extending one-half the averaging period before and after the date indicated (i.e., the 365-day average flow on the date indicated includes data beginning 182 days prior to the indicated date and data ending 182 days after the indicated date).

The 365-day average flow (annual average flow or AAF) has exhibited a mostly steady increasing trend over the period of record considered, however, the rate of increase accelerated in the final year. The AAF at the end of the study period was 7.13 Mgal/d. The ratio of the average dry weather flow to the annual average flow for each year was calculated. The average of this ratio from 2016 through 2021 is 0.992, which indicates that the ADWF is essentially equal to the AAF. For the intended purpose of this this Master Plan, the flow will be presented in terms of ADWF. The annual average BOD load was steadily increasing over the same period. The most recent annual average BOD load determined was 22,121 lb/d as shown in Figure 8-2.

Figure 8-1. Historical Influent Flow

5.0 5.5

6.0 6.5

7.0 7.5

8.0 8.5

9.0 9.5
Jan-16Jul-16Jan-17Jul-17Jan-18Jul-18Jan-19Jul-19Jan-20Jul-20Jan-21 Influent Flow, Mgal/d
Date
Daily 30d Avg 365d Avg
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Figure 8-2. Historical Influent BOD Load
The Phase III Expansion Basis of Design Report prepared by Nolte and Associates in July 2001 rated the existing WQCF at an average flow capacity of 9.87 Mgal/d. Of this capacity, 14.7% (1.45 Mgal/d) is contracted to the City of Lathrop. There have been several changed conditions at the WQCF since 2001 that affect the capacity of the WQCF, including the following:
• Drought conditions and water conservation in recent years have resulted in increased wastewater strength as the pollutants contributed by a given population are carried in less water to the WQCF.
• An effluent limit on Nitrate + Nitrite Nitrogen (10 mg/L monthly average) was added to the National Pollution Discharge Elimination System (NPDES) Permit for the WQCF. The Phase III design did not consider or provide adequate facilities to meet this requirement at the original 9.87 Mgal/d design flow.
• The biotowers in the Northside Plant, which provided a portion of the treatment capacity established in the Phase III Basis of Design Report, were removed from service because they remove the carbon source needed for denitrification. Therefore, they were incompatible with meeting the new nitrogen permit limit.
• A portion of the previous aeration basin volume in each plant (Zone B in each aeration basin) was converted to operate at low dissolved oxygen environment needed for nitrogen removal by cycling the dissolved oxygen on and off (part of the aeration efficiency improvements in 2015 and 2018).
• To improve process control, an automated solids retention time (SRT) controller was installed for both plants in 2020. This allows the WQCF to reliably operate at a lower SRT than previously possible, thereby increasing process capacity.
0 5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
Jan-16Jul-16Jan-17Jul-17Jan-18Jul-18Jan-19Jul-19Jan-20Jul-20Jan-21 Influent BOD Load (lb/d)
Date
Daily 30d Avg 365d Avg
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Because of these changed conditions the WQCF has limited treatment capacity to support ongoing growth within the City. Current and projected future average influent characteristics, including flow, biochemical oxygen demand (BOD), total suspended solids (TSS), and total Kjeldahl nitrogen (TKN) are shown in Table 8-1. For comparison, corresponding values from the Phase III Basis of Design Report are also shown. The projected near-term future flow of 9.23 Mgal/d which includes the true influent flows from Manteca and Lathrop, as well as in-plant recycle streams from the WQCF corresponds to the likely achievable capacity with the Interim Improvements recommended in the WQCF 2021 Capacity Assessment which are described in Chapter 9.

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Table 8-1. WQCF Existing and Near-Term Future Flows and Loads Compared to Phase III Basis of Design Report
Parameter Current
Condition 1
Future Condition
with Interim
Improvements 2
Phase III
Design 3
Annual Average Flow, Mgal/d 4 7.13 9.23 9.87
Average Constituent Concentrations, mg/L 4
BOD 372 372 310
TSS 279 279 315
TKN 60 60 35
Annual Average Load, lb/d 4
BOD 22,121 28,636 25,500
TSS 16,591 21,477 25,900
TKN 3,568 4,619 2,900
Notes:
1 Based on annual average conditions centered on August 30, 2020. 2 Based on future likely achievable capacity (9.23 Mgal/d including recycle flow) with recommended improvements. 3 Design criteria from Phase III Basis of Design Report, July 2001. 4 All data for current and future conditions include the impacts of in‐plant recycle steams. 5 Phase III data are presumed to include the impacts of in‐plant recycle streams, although not explicitly stated in the Phase III Basis of Design Report
Key:

BOD = Biochemical Oxygen Demand
lb/d = pounds per day
mg/L = milligram per liter
Mgal/d = million gallons per day
TKN = Total Kjeldahl Nitrogen
TSS = Total Suspended Solids
WQCF = Wastewater Quality Control Facility

8.2 RECYCLED FLOWS AND TRUE INFLUENT CHARACTERISTICS
The WQCF 2021 Capacity Assessment analyzed in-plant recycle flow stream data to quantify the total recycle flows to determine the true plant influent (without recycle streams) characteristics. The analysis is shown in Table 8-2. As indicated, the total in-plant recycle flow adds up to 0.772 Mgal/d out of the 7.13 Mgal/d measured at the headworks with a true influent flow of 6.358 Mgal/d (7.13-0.772). Therefore, the recycle streams account for approximately 12% of the true influent flow of 6.358 Mgal/d (0.772/6.358) or the true plant influent flow is about 89% (6.358 / 7.13) of the monitored and reported plant influent flow, which includes the plant recycle flows. Based on known and estimated return flow characteristics, the true plant influent has a somewhat higher BOD and lower TKN than the monitored influent with recycles flows included.

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Table 8-2. Recycle Flow Streams and True Influent Characteristics Flow Component
2020
Typical
Flow,
Mgal/d
Ratio to
True
Influent
Flow
BOD,
mg/L
TSS,
mg/L
TKN,
mg/L
BOD,
lb/d
TSS,
lb/d
TKN,
lb/d
DAFT Subnatant 1 0.21 0.033 114 114 11 200 200 20
North Scum + Other 2 0.21 0.033 150 150 10 263 263 18
Filter BW + South Scum + Other 3 0.16 0.025 223 223 22 297 297 30 South Grit Wash Water 4 0.13 0.020 372 279 60 403 302 65 Centrate 5 0.062 0.010 75 250 1,000 39 129 517
Total Return 0.772 0.121 187 185 101 1,202 1,191 649
Total Influent Flow with Recycles 6 7.13 1.121 372 279 60 22,121 16,591 3,568 True Influent Flow w/o Recycles 6.358 1.000 395 290 55 20,919 15,399 2,919 Load with Recycles Ratio to True Influent 1.057 1.077 1.222 Notes:
1 Presume 98% TSS capture in TWAS at 12.5% of WAS flow. Subnatant contains 2% of WAS TSS load in 87.5% of WAS flow.

Presume WAS TSS = 5000 mg/L
Subnatant TSS = 5000*0.02/0.875 = 114 mg/L
Presume Subnatant BOD = Subnatant TSS = 114 mg/L
Presume Subnatant TKN = 0.1 x TSS = 11.4 mg/L 2
Estimated characteristics as shown. 3
Presume characteristics equal to estimated filter backwash characteristics. Presume filters remove equivalent of 5 mg/L BOD and TSS in total influent with recycles. Presume TKN = 0.1 x TSS. 4 Presume grit wash characteristics same as total influent flow characteristics. 5 Based on typical sampling data and BioWin evaluations, presume Centrate BOD=75 mg/L, TSS=250 mg/L, TKN=1,000 mg/L. 6 Annual Average Flow Centered on August 30, 2020.

Key:

BOD = Biochemical Oxygen Demand
DAFT = Dissolved Air Flotation Thickener
lb/d = pounds per day
mg/L = milligram per liter
Mgal/d = million gallons per day
TKN = Total Kjeldahl Nitrogen
TSS = Total Suspended Solids
TWAS = Thickened Waste Activated Sludge
WAS = Waste Activated Sludge

8.3 CITY OF LATHROP FLOW IMPACTS
As previously noted, the City of Lathrop is contracted to 14.7% of the flow capacity for the Phase III Expansion. In this subsection, flows from Lathrop are evaluated and compared to Manteca and total flows, with and without allowances for in-plant recycle flows.

To understand how Lathrop flows can be compared to Manteca and total flows, it is helpful to consider the generalized flow diagram shown in Figure 8-3. As shown in the figure, the flow meter that is used to measure the WQCF influent flow is located downstream from the return of in-plant recycle streams. The flows thus measured are reported as the plant influent flows, but they do not represent the true influent flows, which would exclude in-plant recycle streams. The Lathrop flow, by contrast, is the true Lathrop influent flow, excluding recycle impacts. Therefore, when determining the fraction of the total plant flow represented by Lathrop, it is not appropriate to divide the reported Lathrop flow by the reported WQCF influent flow. Instead, the reported WQCF influent flows must first be adjusted to eliminate the recycle ATTACHMENT 2
flows before determining the Lathrop fraction. Alternatively, the Lathrop flows can be adjusted to include a proportional share of in-plant recycle flows before they are compared to the reported WQCF influent flows. This concept is developed further in Table 8-3, which is discussed below.

Figure 8-3. Existing Manteca WQCF Generalized Flow Diagram Table 8-3 provides a breakdown of Lathrop, Manteca, and total flows under existing conditions (total flow of 7.13 Mgal/d) and under anticipated future conditions at the target capacity of 9.23 Mgal/d, assuming that Lathrop will represent 14.7% of the total flow in that future condition. As shown in Table 8-2, in-plant recycle flows are expected to add approximately 12% to base flows. As mentioned above, this recycle flow allowance must be added to metered Lathrop base flows to attain Lathrop’s total contribution to metered WQCF influent flows, which include the recycle streams. As indicated in Table 8-3, Lathrop’s current flow contribution represents 16.8% of the total WQCF flow. If it is assumed that Lathrop’s flow contribution in the future condition will be at the contract amount of 14.7%, then Lathrop’s metered flow (not including recycle allowance) would increase from the current value of 1.07 Mgal/d to 1.21 Mgal/d, an increase of 0.14 Mgal/d. During the same time, Manteca’s base flow (without recycle allowance) would increase by 1.73 Mgal/d. Therefore, future flow increases would be allocated 7.5% to Lathrop and 92.5% to Manteca. The lower growth allowance for Lathrop is because the current Lathrop flow as a fraction of the total flow is substantially greater than 14.7% and is assumed to decrease to 14.7%.

ATTACHMENT 2
Table 8-3. Breakdown of Existing and Projected Interim Flows Condition and Flow Category Annual Average Flow, Mgal/d Lathrop Manteca Total
Existing
Flow Excluding In‐Plant Recycle Streams 1 1.07 5.29 6.36 Flow Including In‐Plant Recycle Streams 2 1.20 5.93 7.13 Fraction of Total Flow 0.168 0.832 1.000
After Interim Improvements 3
Flow Excluding In‐Plant Recycle Streams 1.21 7.02 8.23
Flow Including In‐Plant Recycle Streams 2 1.36 7.87 9.23 Fraction of Total Flow 0.147 0.853 1.000
Difference (Future ‐ Existing)
Flow Excluding In‐Plant Recycle Streams 0.14 1.73 1.87
Flow Including In‐Plant Recycle Streams 2 0.16 1.94 2.10 Fraction of Total Flow 0.075 0.925 1.000
Notes:
1 Existing Lathrop flow based on annual average from Dec 2019 through Nov 2020. Beginning Dec 2020 recorded Lathrop flows decreased and must be verified. 2 Flow including in‐plant recycle streams calculated as 1.121 x base flow. 3 Future based on total flow with recycle streams = 9.23 Mgal/d. Assuming Lathrop will represent 14.7% of total flow in future.

8.4 SUMMARY OF EXISTING AND FUTURE WASTEWATER

CHARACTERISTICS
Wastewater flows and characteristics from January 2016 through February 2021 (over five years of data) were analyzed. The current wastewater flows and loads presented in this section are summarized and used for projecting future flows and loads as shown in Table 8-4. It is presumed that future expansion will provide build-out capacity flows for Manteca plus the Lathrop flow contribution totaling 17.5 Mgal/d (ADWF without recycle). The future projections assume that all average wastewater influent constituent concentrations and flow and load peaking factors remain unchanged from existing conditions. Therefore, future increases in all sewage flows and loads are expected to be proportional to increases in the annual average flow, which should be roughly proportional population growth.

The assumption that future influent average constituent concentrations and flow and load peaking factors will remain the same as existing presumes that inside water use practices (mainly water conservation within homes) will remain the same as existing. If, due to drought, regulatory requirements, and/or other factors, inside water use practices within the community change, wastewater characteristics will also change, which could impact plant capacity.

Therefore, the analyses and findings in this WWMP should be reviewed if substantial changes in wastewater characteristics occur.

ATTACHMENT 2
Table 8-4. Existing and Future Flows and Loads
Parameter 1 Existing 6.37 Mgal/d 2, 3 Interim 8.23 Mgal/d 2, 4 Future 17.5 Mgal/d 2, 4 ADWF (with Recycle) 7.13 9.23 19.6
ADWF (without Recycle) 6.37 8.23 17.5
Flow Ratios
ADMMF/ADWF 1.04 1.04 1.04
PDF/ADWF 1.25 1.25 1.25
PHF/ADWF 2.10 2.10 2.10
Load Ratios
ADMML/AAL 1.20 1.20 1.20
PDL/AAL 2.00 2.00 2.00
Flow, Mgal/d
ADWF 7.13 9.23 19.6
ADMMF 7.42 9.60 20.38
PDF 8.91 11.54 24.50
PHF 14.97 19.38 41.16
Annual Average Load, lb/d
BOD 22,121 28,636 60,809
TSS 16,591 21,477 45,608
TKN 3,568 4,619 9,808
Average Day Maximum Monthly Load, lb/d
BOD 26,545 34,363 72,971
TSS 19,909 25,772 54,729
TKN 4,281 5,542 11,770
Average Constituent Concentrations, mg/L
BOD 372 372 372
TSS 279 279 279
TKN 60 60 60
Constituent Concentrations with ADMMF and ADMML, mg/L
BOD 429 429 429
TSS 322 322 322
TKN 69 69 69
Constituent Concentrations with ADWF and ADMML, mg/L
BOD 446 446 446
TSS 335 335 335
TKN 72 72 72
Notes:
1 ADWF = Average Dry Weather Flow, AAF = Annual Average Flow, ADMMF = Average Day Maximum Monthly Flow, PDF = Peak Day Flow, PHF = Peak Hour Flow, AAL = Annual Average Load, ADMML = Average Day Maximum Monthly Load, PDL = Peak Day Load 2
All flows and loads include in‐plant recycle streams. Future projections assume recycle flow and load fractions remain unchanged. 3
Based on AAF = 7.13 Mgal/d as of August 30, 2020. 4
The Future condition is based on likely achievable plant capacity with improvements as discussed in Chapter 10. Flow and load peaking factors assumed same as existing.

Key: mg/L = milligrams per liter
Mgal/d = million gallons per day
lb/d = pounds per day
ATTACHMENT 2

8.5 SOLIDS MASS BALANCE
A solids balance diagram of the existing loading conditions at the WQCF is shown on Figure 8-4. Based on the existing and future flows and loads listed in Table 8-4, the estimated solids production was developed by preparing solids mass balances, including the in-plant recycle flows and loads, for the average annual and peak month loading conditions. The raw and digested sludge flows determined from the solids mass balance calculations were then used to determine the sizing requirements for the solids handling facilities. Solids mass balance calculations for the current and interim average annual plant influent flows are summarized in Table 8-5 for the average day and average day maximum month (ADMM) loading conditions with and without imported food waste. Solids mass balance calculations for futures flows are summarized in Table 8-6 when the average annual plant influent flows are at 12.89 Mgal/d and 17.5 Mgal/d, respectively. Solids mass balance diagrams for all loading conditions are provided in Appendix H.

ATTACHMENT 2
Figure 8-4. Solids Mass Balance Diagram of Existing Loading Conditions ATTACHMENT 2
Table 8-5. Solids Production Summary for Current and Interim Flows Description
Existing 6.37 Mgal/d
Average
Existing 6.37 Mgal/d
Peak Month
Interim 8.23 Mgal/d
Average
Interim 8.23 Mgal/d Peak
Month
No Food
Waste
With Food
Waste
No Food
Waste
With Food
Waste
No Food
Waste
With Food
Waste
No Food
Waste
With Food
Waste
Annual Average Influent Flow, Mgal/d 6.36 6.36 6.36 6.36 8.23 8.23 8.23 8.23 Primary Influent Flow, Mgal/d 7.18 7.19 7.21 7.22 9.29 9.29 9.33 9.34 Primary Influent BOD, lb/d 22,184 22,207 26,420 26,443 28,704 28,727 34,185 34,208 Primary Sludge, gpd 40,037 40,251 47,569 47,784 51,789 52,003 61,536 61,750 Primary Sludge Solids, lb/d 10,685 10,742 12,695 12,753 13,821 13,879 16,423 16,480 TWAS, gpd 26,865 26,891 31,786 31,812 34,237 34,263 40,605 40,631 TWAS Solids, lb/d 11,203 11,214 13,255 13,266 14,277 14,288 16,932 16,943 Food Waste Flow, gpd 0 7,226 0 7,226 0 7,226 0 7,226
Food Waste TSS Mass, lb/d 0 4,821 0 4,821 0 4,821 0 4,821 Digested Sludge Flow, gpd 66,902 74,368 79,356 86,822 86,025 93,491 102,141 109,607 Digested Sludge Solids Dry Mass, lb/d 12,866 14,689 15,253 17,076 16,513 18,336 19,602 21,426 Key:

BOD = Biochemical Oxygen Demand
gpd = gal/d = gallons per day
lb/d = pounds per day
Mgal/d = million gallons per day
TWAS = Thickened Waste Activated Sludge
ATTACHMENT 2
Table 8-6. Solids Production Summary for Future Flows
Description
Future 12.89 Mgal/d
Average
Future 12.89 Mgal/d
Peak Month
Future 17.5 Mgal/d
Average
Future 17.5 Mgal/d Peak
Month
No Food
Waste
With Food
Waste
No Food
Waste
With Food
Waste
No Food
Waste
With Food
Waste
No Food
Waste
With Food
Waste
Annual Average Influent Flow, Mgal/d 12.89 12.89 12.89 12.89 17.5 17.5 17.5 17.5 Primary Influent Flow, Mgal/d 14.51 14.52 14.58 14.59 19.37 19.37 19.46 19.47 Primary Influent BOD, lb/d 44,922 44,945 53,503 53,526 60,408 60,430 72,058 72,081 Primary Sludge, gpd 80,897 81,111 96,144 96,358 109,325 109,539 130,025 130,239 Primary Sludge Solids, lb/d 21,590 21,647 25,659 25,716 29,177 29,234 34,701 34,758 TWAS, gpd 48,271 48,296 57,761 57,785 64,927 64,951 77,810 77,834 TWAS Solids, lb/d 20,129 20,139 24,086 24,096 27,074 27,085 32,447 32,457 Food Waste Flow, gpd 0 7,226 0 7,226 0 7,226 0 7,226
Food Waste TSS Mass, lb/d 0 4,821 0 4,821 0 4,821 0 4,821 Digested Sludge Flow, gpd 129,168 136,633 153,905 161,369 174,251 181,716 207,835 215,299 Digested Sludge Solids Dry Mass, lb/d 24,492 26,314 29,206 31,028 33,021 34,844 39,421 41,244 Key:

BOD = Biochemical Oxygen Demand
gpd = gal/d = gallons per day
lb/d = pounds per day
Mgal/d = million gallons per day
TWAS = Thickened Waste Activated Sludge
ATTACHMENT 2

8.6 EQUIVALENT POPULATION SERVED
Flows from a given population are subject to variation with water conservation (and infiltration and inflows into the sewage collection system, which is not a significant issue for Manteca). However, pollutant loads are generally proportional to population and do not vary with water conservation. Since design loads are the key criteria for sizing wastewater treatment facilities, it is useful to present plant capacities in terms of loading or equivalent population.

The average flow per capita was calculated using five years of plant data (January 2016 to February 2021) to calculate an average influent daily flow using the average BOD load (without in-plant recycle flows and Lathrop’s contribution) for each year divided by the State of California Department of Finance population estimates for the City of Manteca. Averaging the five years of data calculates to a per capita wastewater flow of 61 gal/capita/day and a per capita BOD load of 0.203 lb BOD/capita/day. After the recommended Interim Projects are completed increasing the true influent flow capacity to 8.23 Mgal/d, the equivalent population the WQCF can serve is 111,800.

From 2017 through 2020 (fiscal year ending), the City approved an average of 553 single family home permits per year, while an average of 167 multi-family units per year were approved from 2018 through 2020 (2017 data not provided). Assuming 3.2 people per single family unit and 2.5 people per multi-family unit, the occupants of the new dwelling units would be expected to increase the City population by about

2.5% per year (based on a 2020 population of 84,842). This is substantially lower than the rate of increase in WQCF flows over roughly the same period that averaged around 3.4% per year, and the influent biological loading (based on BOD) that increased by an average of 4.1% annually. There are several possible explanations why the increase in reported influent flows and loads at the WQCF were higher than the expected increase in City population including:
• Occupancies for new dwelling units could be higher than assumed; however, reasonable increased occupancies in new residential units would have only a minor impact on the overall City population.
• Flows and loads could be increasing for existing residential units due to increased occupancy per unit.
• Non-residential (commercial, industrial, governmental, etc.) flows and loads could be increasing at a higher rate than residential flows and loads.
• Lathrop flows and loads could be increasing faster than Manteca residential flows and loads.

Over the longer time horizon of 20 plus years, the City is projecting an annual population growth rate of

2.8%. Using a population growth rate 2.8% for Manteca and subtracting 14.7% for Lathrop, the equivalent population for Manteca at the build-out ADWF would be approximately 236,000 people by the year 2057 as summarized in Table 8-7.

ATTACHMENT 2
Table 8-7. Population Projections and Associated Flows and BOD Loads Date Manteca Population
(capita)
Manteca BOD Load
w/o Lathrop or InPlant Recycle (lb/d)
Manteca Flow w/o
Lathrop or In-Plant
Recycle (Mgal/d)
BOD/capita
(lb/d/capita) Flow/Capita (gpcd)
Lathrop
Contribution
Population (capita)
Lathrop Flow
(Mgal/d)
Total Flow w/o
Recycle (Mgal/d)
Lathrop Population
Contribution/
Total Population
Total Population
12/31/2016 76,752 15,673 4.73 0.204 62 15,616 0.95 5.68 16.9% 92,368 12/31/2017 78,784 15,648 4.77 0.199 61 15,591 0.96 5.74 16.5% 94,375 12/31/2018 80,762 16,449 4.97 0.204 61 16,389 1.00 5.97 16.9% 97,151 12/31/2019 83,323 16,797 5.01 0.202 60 16,735 1.01 6.02 16.7% 100,058 12/31/2020 84,842 17,412 5.29 0.205 62 17,349 1.07 6.36 17.0% 102,191 12/31/2021 87,218 17,676 5.34 0.203 61 15,030 1.08 6.42 14.7% 102,248 12/31/2022 89,660 18,171 5.49 0.203 61 15,451 1.11 6.60 14.7% 105,111 12/31/2023 92,170 18,679 5.64 0.203 61 15,884 1.14 6.78 14.7% 108,054 12/31/2024 94,758 19,204 5.80 0.203 61 16,330 1.17 6.97 14.7% 111,088 12/31/2025 97,411 19,741 5.96 0.203 61 16,787 1.20 7.17 14.7% 114,198 12/31/2026 100,139 20,294 6.13 0.203 61 17,257 1.24 7.37 14.7% 117,396 12/31/2027 102,943 20,862 6.30 0.203 61 17,740 1.27 7.57 14.7% 120,683 12/31/2028 105,833 21,448 6.48 0.203 61 18,239 1.31 7.79 14.7% 124,072 12/31/2029 108,796 22,049 6.66 0.203 61 18,749 1.34 8.00 14.7% 127,546 12/31/2030 111,843 22,666 6.85 0.203 61 19,274 1.38 8.23 14.7% 131,117 12/31/2031 114,974 23,301 7.04 0.203 61 19,814 1.42 8.46 14.7% 134,788 12/31/2032 118,203 23,955 7.24 0.203 61 20,370 1.46 8.70 14.7% 138,573 12/31/2033 121,512 24,626 7.44 0.203 61 20,941 1.50 8.94 14.7% 142,453 12/31/2034 124,915 25,315 7.65 0.203 61 21,527 1.54 9.19 14.7% 146,441 12/31/2035 128,412 26,024 7.86 0.203 61 22,130 1.59 9.45 14.7% 150,542 12/31/2036 132,018 26,755 8.08 0.203 61 22,751 1.63 9.71 14.7% 154,769 12/31/2037 135,714 27,504 8.31 0.203 61 23,388 1.68 9.98 14.7% 159,102 12/31/2038 139,514 28,274 8.54 0.203 61 24,043 1.72 10.26 14.7% 163,557 12/31/2039 143,421 29,066 8.78 0.203 61 24,716 1.77 10.55 14.7% 168,137 12/31/2040 147,448 29,882 9.03 0.203 61 25,410 1.82 10.85 14.7% 172,858 12/31/2041 151,576 30,719 9.28 0.203 61 26,122 1.87 11.15 14.7% 177,698 12/31/2042 155,820 31,579 9.54 0.203 61 26,853 1.93 11.46 14.7% 182,673 12/31/2043 160,183 32,463 9.80 0.203 61 27,605 1.98 11.78 14.7% 187,788 12/31/2044 164,681 33,374 10.08 0.203 61 28,380 2.04 12.12 14.7% 193,061 12/31/2045 169,292 34,309 10.36 0.203 61 29,175 2.09 12.45 14.7% 198,466 12/31/2046 174,032 35,269 10.65 0.203 61 29,991 2.15 12.80 14.7% 204,023 12/31/2047 178,905 36,257 10.95 0.203 61 30,831 2.21 13.16 14.7% 209,736 12/31/2048 183,928 37,275 11.26 0.203 61 31,697 2.27 13.53 14.7% 215,625 12/31/2049 189,078 38,319 11.57 0.203 61 32,584 2.34 13.91 14.7% 221,662 12/31/2050 194,372 39,392 11.90 0.203 61 33,497 2.40 14.30 14.7% 227,869 12/31/2051 199,815 40,495 12.23 0.203 61 34,435 2.47 14.70 14.7% 234,249 12/31/2052 205,425 41,632 12.57 0.203 61 35,402 2.54 15.11 14.7% 240,827 12/31/2053 211,177 42,797 12.93 0.203 61 36,393 2.61 15.54 14.7% 247,570 12/31/2054 217,090 43,996 13.29 0.203 61 37,412 2.68 15.97 14.7% 254,502 12/31/2055 223,168 45,228 13.66 0.203 61 38,459 2.76 16.42 14.7% 261,628 12/31/2056 229,435 46,497 14.04 0.203 61 39,539 2.84 16.88 14.7% 268,974 12/31/2057 235,859 47,799 14.44 0.203 61 40,646 2.92 17.35 14.7% 276,505 12/31/2058 242,463 49,138 14.84 0.203 61 41,784 3.00 17.84 14.7% 284,247 12/31/2059 249,252 50,514 15.26 0.203 61 42,954 3.08 18.34 14.7% 292,206 12/31/2060 256,250 51,932 15.68 0.203 61 44,160 3.17 18.85 14.7% 300,410 ATTACHMENT 2

9.0 WQCF ASSESSMENT OF EXISTING FACILITIES AND

RECOMMENDED INTERIM IMPROVEMENTS
This chapter provides an overview of the City’s existing Wastewater Quality Control Facility (WQCF). The information presented in this chapter is based on the review of previous studies, design reports, record drawings, operating records, and discussions with City staff. This chapter also presents an assessment of the performance of the existing treatment processes and recommendation for Interim Improvements to keep the plant in compliance with waste discharge requirements until the next major expansion project.

This chapter is divided into the following sections:
• Headworks and Influent Pump Station
• Aerated Grit Tanks
• Primary Sedimentation Basins
• Secondary Treatment Facilities
• Secondary Effluent Equalization Pond (SEEP)
• Filter Feed Pump Station
• Rapid Mix and Flocculation Tanks
• Tertiary Filters
• UV Disinfection System
• Effluent Handling and Disposal Facilities
• Biosolids Handling Facilities
• Biogas Utilization Facilities
• Electrical Supply and Distribution
• Instrumentation and Electrical Controls
• Auxiliary Systems
• Recommended Interim Improvements

9.1 HEADWORKS AND INFLUENT PUMP STATION
Photos of the Headworks and Influent Pump Station (IPS) are shown on Figure 9-1. The purpose of the Headworks and IPS is to provide flow control to the treatment plant and remove rags and other debris that would otherwise clog and prematurely wear out equipment used in downstream processes.

ATTACHMENT 2
Influent Pump Station Headworks Screens
Headworks Biofilter Headworks Screenings Dumpsters
Figure 9-1. Headworks and Influent Pump Station

9.1.1 Influent Gravity Sewer Trunks
Raw wastewater from the City’s sewer collection system enters an influent box structure at the WQCF from two gravity sewer trunks, the 60-inch North Manteca Sewer Trunk and 60-inch South Manteca Sewer Trunk. Each sewer trunk has an isolation gate at the influent box. Wastewater flows out of the influent box through three parallel channels into a common influent channel. The common influent channel is connected to the screen distribution channels for flow splitting to the headworks bar screens.

9.1.2 Influent Screening
Influent screening system consists of one manual bar rack and three mechanical bar screens. Slide gates upstream and downstream allow for isolation of each bar screen and bar rack. The mechanical bar screens are designed to remove coarse solids and non-biodegradable materials. Two of the recently replaced mechanical bar screens have 1/4-inch openings and the third older screen has 3/8-inch ATTACHMENT 2
openings. Solids caught on the screen are continuously transferred to the top of the screen for discharge to the screenings washer compactor system. The manual bar screen has 3/8-inch openings and permits shutdown and bypass of the mechanical bar screens during periods of equipment failure and maintenance.

9.1.3 Screenings Washer Compactor System
Collected screenings from the mechanical bar screens are discharged onto a shaftless screw conveyor and fed to the hopper of a screenings washer compactor. Screenings are sprayed and passed through a grinder for particle reduction to provide a greater exposed surface area during the washing process.

Ground solids are passed through an auger, which washes and separates soft organics from undesirable solids. A reversing sequence causes the ground solids to be washed multiple times before being transferred to the compaction zone. The undesirable solids are compacted, dewatered, and finally discharged to the screenings dumpster.

9.1.4 Influent Pump Station
Bottom plan view and section of the Influent Pump Station (IPS) is shown on Figure 9-2 and Figure 9-3, respectively. Screened wastewater collected in the IPS wet well is pumped by four pumps, two pumps to the Northside Plant, a dedicated pump to the Southside Plant, and a standby pump that can convey wastewater to both the Northside and Southside Plant. The IPS dry well has additional room for four future pumps. Pumped flow to the Southside Plant is measured with a magnetic flow meter located inside the IPS. Flows to the Northside Plant are measured at the Northside Plant aerated grit tanks.

ATTACHMENT 2
09 10 MBSN-03-03
MBSN-03-02
MBSN-03-01
0 2 4 6 8 10

SCALE IN FEET
A
FIG 9-3
A
FIG 9-3
LEGEND

SANITARY SEWER (SS)
PLANT EFFLUENT (3W)

DRAIN/VENT (D/V)

CHEMICAL (CAS)

PRIMARY EQUIPMENT
FUTURE

STRUCTURE
m ipsum
Figure 9-2
WQCF Influent Pump Station Bottom Plan
U:\184031535\drawing\graphics\manteca_wqcf__________.ai mlm march-2023 ATTACHMENT 2

REDUCED RECORD SET

NOT TO SCALE

SECTION
A
FIG 9-2
LEGEND

SANITARY SEWER (SS)
PLANT EFFLUENT (3W)

DRAIN/VENT (SD/D/V)

PRIMARY EQUIPMENT
FUTURE

STRUCTURE
m ipsum
Figure 9-3
WQCF Influent Pump Station Section View
U:\184031535\drawing\graphics\manteca_wqcf__________.ai mlm march-2023 ATTACHMENT 2

9.1.5 Headworks and IPS Biofilter
The Headworks and IPS uncovered biofilter was originally constructed to treat air from the Headworks and Influent Pump Station and was later also connected to the Dewatering Building. The biofilter is sized to treat an airflow of 33,000 cubic feet per minute (cfm) of air and is distributed to the following areas:
• Influent Junction Structure, Screen Room and IPS Wet Well • Dewatering Building
Lava Rock media was selected due to longer media life potential compared to organic media. Media is installed to a depth of 4 feet and the unit provides an empty bed residence time of 100 seconds. The unit is provided with a single variable frequency drive (VFD) controlled odor control fan to remove air from the IPS and Dewatering Buildings for treatment. Airstream humidification is provided upstream of the biofilter using in-duct water spray nozzles and surface sprinklers are provided to irrigate the media bed. The biofilter and odor control system have not been operating at optimal conditions since 2015.

9.1.6 Assessment of Headworks, IPS and Biofilter
Currently, the IPS is designed with three duty pumps and one standby pump (the standby pump can convey screened wastewater to either the Northside Plant or the Southside Plant). The operators have noted that during recent severe storm events, all four pumps were needed to convey the high influent flows. There are currently four empty pump bays to facilitate expanding the capacity of the IPS. For pumping to the Southside Plant, there are two 200 hp pumps (one duty and one standby), each with a design capacity of 10 Mgal/d. The peak hour flow to the Southside Plant for the Interim Improvement Projects is 10.82 Mgal/d, which is greater than the capacity of the one duty pump for the Southside Plant.

Therefore, to ensure the IPS has firm capacity, it is recommended to install a fifth pump in one of the empty pump bays to serve as the second duty pump dedicated to the Southside Plant. The fifth Influent Pump Station pump is included with the Interim Improvement Projects listed in Table 9-3.

In 2022, two new headworks screens were installed to replace the older screens. The third mechanical screen is at the end of its useful life and will need replacing. The third mechanical screen replacement is included with the Interim Improvement Projects listed in Table 9-3.

The Headworks screening channel and wet well are covered by aluminum grating. Water in the ducting from the wet well flooding has mixed with the sulfides in the air ventilation system producing sulfuric acid.

The acid in the ducting has leaked onto the grating requiring replacement of the grating in 2022. On February 6, 2015, a study of headworks ventilation system and biofilter was prepared by HERWIT and Stantec. According to plant staff the biofilter operated effectively for approximately 5 years before exhibiting operational problems, primarily attributed to excessive head loss across the filter associated with media fouling. The biofilter has not been functioning properly since that time. Air is being exhausted from the Headworks, IPS and Dewatering Building with the odor control fan and discharged without odor treatment. The study made the following recommendation to improve ventilation and bring the biofilter back into service:

ATTACHMENT 2
• Provide a new ventilation where foul air from the junction structure, covered channels and room air will be exhausted to the biofilter for treatment. Exhausting 10,000 cfm of air from the junction structure, 3,000 cfm of air from the channels, and 5,500 cfm from the operating space, results in 18,500 cfm of air treated in the biofilter.
• Ventilate the operating space at 5,500 cfm (12 air changes per hour) to the upgraded biofilter for treatment. Supply air will only be provided to the operating space (5,500 cfm at 12 ach), so air exhausted from the channels will come from the room thereby creating a pressure differential between the two spaces. This will contain odors in the channels and junction structure and improve indoor air quality.
• Replace existing exhaust ductwork in the Influent Junction Structure, Screen Room and Wet Well to accommodate revised airflows and distribution. In addition, a new exhaust ductwork system should be provided for the operating space. All ductwork should be provided with air balancing/isolation dampers for all pickup points.
• The existing odor control fan should be replaced with a spark and corrosion resistant, FRP unit that is sized for the planned odor control capacity of the system (i.e. 18,500 cfm, as discussed above). This will prolong the useful life of the unit, better match the revised airflow scheme, and reduce the overall horsepower of the unit ultimately saving on power costs. • The lava rock media in the biofilter should be replaced by inorganic media provided by Biorem©, ECS or equivalent. Three (3) feet of media should be replaced in two (2) cells to provide an EBRT of 55 seconds.
• The biofilter media cells (2 total) should be provided with a cover system. The cover will help prevent the migration of dust, soil and other particulates to the biofilter, and will also help to provide better climatic controls of the media bed.
• The exhaust duct from the odor control fan should be reconfigured downstream of the existing grease/particulate filter. Specifically, the ductwork should be routed above grade to feed the two biofilter cells that will be refurbished and provided with an accessible balancing isolation damper.

Improvements to the headworks ventilation system and biofilter are included with the recommended Interim Improvement Projects listed in Table 9-3.

9.2 AERATED GRIT TANKS
There are four total aerated grit tanks: two at the Northside Plant and two at the Southside Plant. All aerated grit tanks are similar in operation. The purpose of the aerated grit tanks is to remove relatively high-density inorganic particles (e.g., sand) from the wastewater stream. This reduces wear on downstream mechanical equipment and minimizes the accumulation of inorganic materials in the digesters. Aeration of the tanks improves the treatability of the wastewater, grease separation, and removal of biochemical oxygen demand (BOD) in the primary sedimentation basins.

ATTACHMENT 2
Screened sewage from the Headworks is conveyed to the aerated grit tanks by the Influent Pump Station (IPS). Each grit removal tank consists of two parallel aerated grit chambers. Slide or stop gates located at the entrance to each grit tank allows for shutdown and isolation of an individual tank.

Grit is separated from the influent flow as it passes through the sloped chambers with heavier sand and grit particles settling to the bottom and lighter organic materials remain in suspension. Coarse bubble air diffusers are located near to the bottom of the tanks, which induces a circulation pattern in the liquid stream. The rising air produces a spiral motion of flow through the tank that helps grit settle and collect at the grit collection sump (hopper). Grit classifiers separate the grit from the organics and water. The North Plant grit classifier was replaced in 2022. The south plant grit classifier is still the original unit.

Settled grit in the bottom of the hopper is conveyed to a grit classifier by grit pumps at the Northside Plant and by gravity at the Southside Plant. The grit classifier separates the heavier grit particles and lighter organic particles from the liquid. The grit classifier washes, dewaters, and conveys the grit to a dumpster.

Effluent from the grit tanks flows into a common distribution channel leading to the primary sedimentation basins.

Photos of the Aerated Grit Tanks are shown on Figure 9-4.

ATTACHMENT 2
Southside Plant Grit Basins Southside Plant Grit Collection Hopper Northside Plant Grit Classifier Southside Plant Aerated Grit Basin Blower Figure 9-4. Aerated Grit Tanks

9.2.1 Assessment of Aerated Grit Tanks
The existing Aerated Grit Tanks are performing satisfactorily as designed and will not require major upgrades until the next expansion project. However, the covers for the aerated grit tanks are too heavy for the operators to lift for operation and maintenance so they are left open, and therefore, the biofilters are not in operation.

The current aerated grit tank covers are the Enduro XL6 fiberglass reinforced plastic (FRP) covers, which the operators have noted are too heavy. The existing covers are recommended to be replaced with Evoqua’s Geomembrane Technologies brand tank covers, which are retractable arch-supported covers made of high-performance UV-protected membranes. The covers are supported on a low-profile aluminum arch frame so they can be quickly detached and re-attached to provide easy access for operators. Since the Phase III Expansion Project (when the current covers were installed), Enduro has started to manufacturer the XL3 FRP covers, which can also be considered during preliminary design.

ATTACHMENT 2
The individual spans of the XL3 cover are lighter than the XL6 cover because the XL3 cover spans a maximum distance of approximately 10 ft while the XL6 cover spans a maximum distance of approximately 20 ft. A possible, less expensive alternative to replacing all existing covers that could be investigated during preliminary design is to only replace some of the panels with XL6 panels with larger hatches for access. The cost of replacing the XL6 covers with Evoqua’s Geomembrane Technologies brand tank covers is included in the Interim Improvements Project.

New covers for the aerated grit tanks are included with the recommended Interim Improvement Projects listed in Table 9-3.

9.3 PRIMARY SEDIMENTATION BASINS
There are six total primary sedimentation basins: three at the Northside Plant and three at the Southside Plant. All primary sedimentation basins are similar in operation. The purpose of the primary sedimentation basins is to remove readily settleable solids and floatable materials, such as oil and grease, to reduce the wastewater suspended solids content for downstream treatment processes.

Screened and de-gritted wastewater enters the primary sedimentation basins through a common influent channel. Flumes located at the entrance of each basin provide even flow distribution into each train from the influent channel. Basins are designed to present low velocity, idle flow conditions, and have baffles to disperse flow and prevent short circuiting. This allows suspended solids and floatable material, such as oil and grease, to gradually separate from the wastewater. Suspended solids settle to the bottom of the of the basin where they form a semi-solid sludge. Settled sludge is pushed by a collector mechanism into a channel or hopper located at the inlet of each basin. Primary sludge pumps periodically withdraw and convey collected sludge to the anaerobic digesters for treatment.

Floatable materials such as oil and grease rise to the surface where they form a scum layer. Mechanical skimmers and telescopic valves collect the scum and convey it to a common collection box. Primary scum pumps periodically withdraw and convey collected scum to the anaerobic digesters for treatment.

Clarified primary effluent overflows a series of v-notch weirs located at the outlet end of each basin into an effluent launder. Flow from the effluent launders collect in a common primary effluent channel from which wastewater is conveyed downstream to the aeration basins for further treatment.

Photos of the Primary Sedimentation Basins are shown on Figure 9-5.

ATTACHMENT 2
Southside Plant Primary Sedimentation Basin Southside Plant Primary Sedimentation Basin Launders
Southside Plant Aerated Grit Pumps Southside Plant Primary Sludge Pumps Figure 9-5. Primary Sedimentation Basins

9.3.1.1 Assessment of Primary Sedimentation Basins
The existing Primary Sedimentation Basins are performing satisfactorily as designed. Recently the chain and flight collectors at the Northside Plant were replaced. The covers for the sedimentation basins are too heavy for the operators to lift for operation and maintenance so they are left open, and therefore, the biofilters are not in operation.

The current primary sedimentation basin covers are the Enduro XL6 FRP covers, which the operators have noted are too heavy. The existing covers are recommended to be replaced with Evoqua’s Geomembrane Technologies brand tank covers (same as the aerated grit tanks), which are retractable arch-supported covers made of high-performance UV-protected membranes. The covers are supported on a low-profile aluminum arch frame so they can be quickly detached and re-attached to provide easy access for operators. Similar to the aerated grit tanks, alternative solutions that could be investigated during preliminary design include the Enduro XL3 covers or only replacing some of the panels with XL6 ATTACHMENT 2
panels with larger hatches for access. New covers for the primary sedimentation basins are included with the recommended Interim Improvement Projects listed in Table 9-3.

9.4 SECONDARY TREATMENT FACILITIES
Photos of the Secondary Treatment Facilities are shown on Figures 9-6, 9-7 and 9-8. The Secondary Treatment Facilities include the Aeration Basins, Secondary Clarifiers, and RAS/WAS Pumps Stations.

There are ten aeration basins (all similar in configuration and operation): Five at the Northside Plant (Aeration Basin Nos. 1-5) and five at the Southside Plant (Aeration Basin Nos. 6-10). There are five secondary clarifiers (all similar in configuration and operation): Three at the Northside Plant and two at the Southside Plant. There are two Return Activated Sludge (RAS) Pump Stations and one Waste Activated Sludge (WAS) Pump Station. The primary components of the existing secondary treatment systems for both the Northside and Southside Plants are indicated in Table 9-1.

Table 9-1. Existing Secondary Treatment Facilities
Item North Plant South Plant
Number of Aeration Basins 5 5
Zone Volumes in Each Reactor Basin, Mgal
Zone A (Anoxic) 0.054 0.074
Zone B (Aerobic/Anoxic) 0.054 0.103
Zone C (Aerobic) 0.054 0.087
Zone D (Aerobic) 0.067 0.071
Zone E (Aerobic) 0.067 0.071
Total 0.296 0.406
IMLR Pumps
Number of IMLR Pumps per Reactor 1 1
Approximate Capacity of Each IMLR Pump, Mgal/d 2 2
Secondary Clarifiers
Number of Secondary Clarifiers 3 2
Diameter of Each Clarifier, feet 85 110
RAS Pumps
Number of Duty RAS Pumps per Clarifier 1 1
Capacity of Each RAS Pump, gpm 2,250 3,400
RAS Underflow Rate, gpd/ft2 571 515
Key:
gpd/ft2 = gallons per day per square foot
gpm = gallons per minute
IMLR = Internal Mixed Liquor Recycle
Mgal = million gallons
Mgal/d = million gallons per day
RAS = Return Activated Sludge
ATTACHMENT 2
Southside Plant Aeration Basin Fine Bubble
Diffusers
Southside Plant Aeration Zone E
Southside Plant Aeration Basin Aerobic Zones Southside Plant Aeration Basin Blowers Figure 9-6. Aeration Basins
ATTACHMENT 2
Northside Plant Secondary Clarifiers Southside Plant Secondary Clarifier Southside Plant Secondary Clarifier Effluent
Launder
Southside Plant Secondary Clarifier Launder
Covers
Figure 9-7. Secondary Clarifiers
ATTACHMENT 2
Northside Plant RAS Pump Station Northside and Southside Plants WAS Pump Station
Southside Plant RAS Pump Station Southside Plant RAS Pump Station Figure 9-8. RAS Pump Stations
The purpose of the secondary treatment facilities is to complete the biological treatment of the wastewater (carbonaceous oxidation, nitrification, and energy saving denitrification). Effective operation of the secondary treatment process is critical for the WQCF to produce effluent that complies with BOD, total suspended solids (TSS), and nitrogen requirements of the NPDES permit.

9.4.1 Secondary Treatment Aeration Basins
The aeration basins (also referred to as Reactor Basins) are one component of the secondary treatment process. Other major systems include the Secondary Clarifiers and RAS/WAS Pump Stations.

The primary function of the aeration basins is to provide the optimum environment required to produce and maintain an adequate biomass of selected biologically active microorganisms. This biomass is commonly termed “Activated Sludge.” The activated sludge microorganisms feed and grow on soluble carbonaceous and nitrogenous compounds. In so doing, they convert the soluble compounds into ATTACHMENT 2
settleable particulate that can be removed in the secondary clarifiers. This mass of activated sludge solids in the aeration basin is commonly called the mixed liquor suspended solids (MLSS).

A mixture of screened raw sewage and return activated sludge (RAS) flows to the aeration basins. To optimize the capacity of the aeration basins, attain an effluent nitrate-nitrogen concentration of 10 mg/L, and to control sludge bulking and to save energy, the process is run to allow cyclic aeration to promote simultaneous nitrification and denitrification (SND) in this zone. Oxygen is required for microorganisms to respire and to allow for nitrification to take place. Dissolved oxygen (DO) probes monitor the DO concentration and are used to control the blowers that provide air to the diffusers. Substantial denitrification will occur in the aerobic zones that has low dissolved oxygen concentration or operating with cyclical (High/Low) DO concentrations. By so doing, a dual zone phenomenon occurs within the activated sludge floc itself. The outer zone, where oxygen is available, is nitrifying while the inner zone, where oxygen is absent, is denitrifying.

The most important species of the organisms in the MLSS are the heterotrophic bacteria and the nitrifiers which are responsible for BOD, ammonia, and nitrate removal. Nitrification (conversion of influent ammonia to nitrite and nitrate) generally occurs in the aeration basins when and where oxygen is present, while denitrification (conversion of nitrate to nitrogen gas) occurs when and where oxygen is absent. If the bulk liquid dissolved oxygen concentration in the aeration basins is maintained above 2 mg/L, nitrification is optimized, but very little denitrification will occur. If the dissolved oxygen concentration is lowered to less than 0.3 mg/L, nitrification will be slowed somewhat, but significant denitrification will likely be promoted. This is because the low bulk liquid dissolved oxygen concentration would not penetrate completely into bacterial flocs, and this would create anoxic (oxygen absent, but nitrate present) areas in the interior of flocs where denitrification can occur. Another method to promote denitrification is to cycle DO concentrations up and down, for example, between 0.1 and 2 mg/L. In this case, nitrification would be promoted during times with high DO and denitrification would be promoted at low or zero DO.

9.4.2 Secondary Clarifiers
The purpose of the secondary clarifiers is to separate settleable solids from aeration basin effluent, also known as mixed liquor, leaving a high-quality secondary effluent. Suspended solids in the mixed liquor settle to the bottom while the clarified effluent overtops a weir into a collection trough for conveyance to downstream processes. Effective operation of the secondary clarifiers is critical for the WQCF to produce effluent that complies with BOD, TSS, and nitrogen requirements of the NPDES permit.

The secondary clarifiers are circular concrete tanks with a center drive mechanism supported on a stationary center-feed influent column. Mixed liquor influent from the aeration basins enters the secondary clarifiers through the influent column in the center of each unit where energy dissipation occurs.

Suspended solids in the mixed liquor settle to the bottom while the clarified effluent overtops a peripheral weir into an effluent launder for conveyance downstream. Sludge and scum collection systems remove settable and floatable solids.

ATTACHMENT 2

9.4.3 RAS/WAS Pump Stations
The purpose of the Return Activated Sludge (RAS) pump station is to recycle settled sludge from the bottom of the secondary clarifiers back to the aeration basins. By controlling the amount of recycled RAS, a desirable mixed liquor suspended solids (MLSS) concentration is achieved in the aeration basins and the sludge blanket is maintained at the appropriate level in the secondary clarifiers.

The purpose of the Waste Activated Sludge (WAS) pump station is to waste solids from the RAS system to maintain the desired Solids Retention Time (SRT). The WAS system is controlled by a HACH controller with automatic SRT control. The RAS/WAS Pump Stations need higher capacity pumps as described in the WQCF 2021 Capacity Assessment Study.

The Northside Plant RAS pump station and the WAS pump station are in the RAS/WAS Building between the Northside Plant aeration basins (Aeration Basin Nos. 1-5) and the secondary clarifiers (Secondary Clarifier Nos. 1-3). The Southside Plant RAS pump station is located outdoors adjacent to the South Plant secondary clarifiers (Secondary Clarifier Nos. 4-5).

The RAS pump stations return settled solids in the secondary clarifiers back to the aeration basin influent channels. They are only capable of conveying return sludge within the same facility (e.g. the Northside Plant RAS pump station cannot return sludge to the Southside Plant aeration basins or vice versa). A 4- inch reseeding line is being incorporated into the Interim Improvement Projects to allow seeding of sludge back and forth between the North and South Plants.

The WAS Pump Station is responsible for pumping WAS from the Northside Plant and Southside Plant secondary clarifiers to the sludge thickening facilities.

9.4.4 Assessment of Secondary Treatment Facilities
The existing Northside and Southside Plants are challenged to meet the effluent nitrate + nitrite (10 mg/L as nitrogen monthly average). As discussed in the WQCF 2021 Capacity Assessment, improvements are needed to the secondary treatment facilities to improve nitrogen removal performance and are a prerequisite to handle increased flows and loads. Improvements to the secondary treatment aeration basins are currently under design by Pacific Advanced Civil Engineering, Inc. (PACE) and improvements to the RAS/WAS pumping systems are currently under design by HERWIT Engineering.

ATTACHMENT 2
For the Southside Plant improvements, the aeration basins will be reconfigured so that the first and fourth biological treatment zones are anoxic. Cyclic aeration will be removed in the second zone so that there are three zones out of five with constant aerobic biological treatment. Exterior improvements will include installation of a new Internal Recycle Pump Station (IRPS) to replace the undersized mixed liquor recycle pumps.

Glycerin feed systems have been added to both the Northside and Southside Plants ahead of the first zone anoxic basins to improve denitrification performance.

Finally, as noted in the WQCF 2021 Capacity Assessment, sidestream treatment would greatly reduce the recycle TKN load from the solids handling system and would provide major benefits to assist in compliance with the effluent nitrate + nitrite limit, whether the plant accepts food waste or not into the anaerobic digesters. Food waste should not be accepted without providing sidestream treatment.

Secondary treatment improvements described above are included with the recommended Interim Improvement Projects listed in Table 9-3.

9.5 SECONDARY EFFLUENT EQUALIZATION POND (SEEP)
Photos of the Secondary Effluent Equalization Pond (SEEP) are shown on Figure 9-9. The Secondary Effluent Equalization Pond (SEEP) is a 5.9-million-gallon (Mgal) storage pond. The SEEP is used to dampen diurnal peak and low flow conditions to the tertiary filters and UV disinfection system, and to store secondary effluent when discharge to the San Joaquin River is unavailable due to temperature conditions.

The SEEP is a lined and covered earthen storage pond that is sized based on the following design criteria:

ATTACHMENT 2
• Diurnal flow equalization (approximately 1.9 Mgal of storage). • Low flow conditions in the San Joaquin River at times of high tidal influence when discharge is restricted (approximately 3.7 Mgal of storage).

ATTACHMENT 2
Secondary Effluent Storage Pond Electrical Transformer & Switchgear for Irrigation Pump Station
Irrigation Pumps Secondary Effluent Equalization Pond
Figure 9-9. Secondary Effluent Storage and Equalization Ponds

9.5.1 Performance Assessment of SEEP
The SEEP liner is in poor condition. When there is a puncture or tear in the liner it is difficult to repair because of the deteriorated condition of the liner material. Also, it is difficult to clean the pond or remove sludge underneath the liner, so it is currently full of sludge. Plant operations staff report that last time the pond was out of service 6 to 12 inches of sludge had accumulated in the bottom of pond.

Replacement of the liner is included with the recommended Interim Improvement Projects listed in Table 9-3.

9.6 FILTER FEED PUMP STATION
Photos of the Filter Feed Pump Station are shown on Figure 9-10. Secondary effluent is pumped to the tertiary filters and UV disinfection system through the Filter Feed Pump Station (FFPS). The FFPS is comprised of four vertical mixed flow impeller pumps housed within individual pump barrels. The pumps ATTACHMENT 2
tee off of a common 36-inch manifold. A magnetic flow meter and VFD units are used to control the pumps to obtain the filter flow desired by the operator. When needed, coagulant and polymer are added to secondary effluent immediately following the FFPS through a chemical injection line at the pump station.

Filter Feed Pumps Filter Feed Pump Station
Filter Feed Pumps
Figure 9-10. Filter Feed Pump Station

9.6.1 Performance Assessment of Filter Feed Pump Station The existing FFPS is performing satisfactorily as designed and will not require major upgrades until flows reach a peak hourly flow of approximately 25.1 Mgal/d (one low flow pump with a maximum design capacity of approximately 5.0 Mgal/d and three high flow pumps in a two duty plus one standby pump configuration, each with a maximum design capacity of approximately 10.0 Mgal/d).

ATTACHMENT 2

9.7 RAPID MIX AND FLOCCULATION TANKS
Photos of the Rapid Mix and Flocculation Tanks are shown on Figure 9-11. Following the FFPS, secondary effluent can be routed to a rapid mix tank and/or three flocculation tanks prior to tertiary filtration and UV disinfection. The purpose of the rapid mix and flocculation tanks is to provide coagulation and flocculation to condition or pre-treat secondary effluent for enhanced tertiary filtration. Coagulation and flocculation are particularly important when secondary effluent quality deteriorates as evidenced by increasing turbidities. The use of chemicals for pre-treatment is required by State Board when filter influent turbidity exceeds 5 NTU for more than 15 minutes. The flocculation process should generate strong pin-point floc that are easily and efficiently removed by the tertiary filters.

Flocculation Tanks
Rapid Mix and Flocculation Tanks and Filter Structure
Figure 9-11. Rapid Mix and Flocculation Tanks
ATTACHMENT 2

9.7.1 Performance Assessment of Rapid Mix and Flocculation Tanks
The existing Rapid Mix and Flocculation Tanks are performing satisfactorily as designed. The Rapid Mix Tanks were designed for an average flow of 9.87 Mgal/d and a peak flow of 19.15 Mgal/d, which provides hydraulic residence times of 40 seconds and 20 seconds, respectively. The Flocculation Tanks were also designed for an average flow of 9.87 Mgal/d and a peak flow of 19.15 Mgal/d, which provides hydraulic residence times of 45 minutes and 23 minutes, respectively.

9.8 TERTIARY FILTERS
Photos of the Tertiary Filters are shown on Figure 9-12. The purpose of the tertiary filters is to reduce suspended solids and organic loading to the San Joaquin River and increase the reliability of the UV disinfection system. Filtration followed by UV disinfection allows the WQCF to achieve NPDES effluent quality requirements and comply with Title 22 requirements for producing disinfected tertiary recycled water (DTRW). The Tertiary Filters consists of six cloth disk filters enclosed in concrete basins. A five foot wide filter inlet channel allows flow to be directed to any combination of filters. Each filter is equipped with a drive assembly, center tube assembly, filter cloth disk assembly, backwash/sludge discharge assembly, level switches and sensors, and filter controls. The filter backwash pumps, turbidity equipment and other associated piping and appurtenances are contained in three pump galleries. Following tertiary filtration, filtered effluent can be routed to the UV disinfection system or directed to the Secondary Effluent Storage Pond (SESP) for storage and/or re-treatment under abnormal conditions.

ATTACHMENT 2
Cloth Media Filters Filter Feed Trough
Tertiary Filters Control Panel Tertiary Filter Concrete Tank Figure 9-12. Tertiary Filters

9.8.1 Performance Assessment of Tertiary Filters
The PLCs for the filters were replaced with Modicon M340s, since this upgrade the Tertiary Filters are performing satisfactorily and will not require expansion until flows reach the design capacity of 9.87 Mgal/d as an average flow and 19.15 Mgal/d as a maximum flow.

9.9 UV DISINFECTION SYSTEM
The purpose of UV disinfection (photos shown in Figure 9-13) is to disinfect the tertiary treated effluent and produce DTRW. The UV light inactivates pathogens in the filtered wastewater by damaging the genetic material. Tertiary filtration along with UV disinfection allows the WCQF to achieve NPDES effluent quality and Title 22 requirements. The UV disinfection system consists of three components: 1) disinfection channels (currently two concrete channels), 2) electrical system (lamps, wiring/cabling, power distribution, and control system, which includes the UV detection system, on-line UV transmittance ATTACHMENT 2
monitor, and ballasts), and 3) mechanical system (quartz sleeves, frames, UV modules, automatic wiping system, motorized inlet/outlet gates, and reactor configuration).

UV Disinfection Facility Influent Gates UV Lamp Modules UV Disinfection Facility Effluent Gates UV Lamp Modules Figure 9-13. UV Disinfection

9.9.1 Performance Assessment of UV Disinfection System
In the last two years (January 2021-March 2023), there has been one total coliform violation in June 2022 (prior to 2021, there was one exceedance in 2020, one in 2019, and several in 2018). From January 2018 through March 2023, the daily average UV dose has averaged 206 mJ/cm2, which is significantly greater than the permit required minimum UV dose of 100 mJ/cm2. The width of the existing channels (10-feet

11.5-inches) with no added means of access, makes it difficult to get access to the lamps and channels for maintenance and cleaning.

Stantec recently coordinated with Wedeco (the UV lamp manufacturer) to determine the proposed UV system upgrade for the Interim Improvement Projects. While it is recommended to complete the UV system improvements during the Interim Improvement Projects to facilitate maintenance and improve treatment (reduce the likelihood that a coliform violation could occur), the proposed UV system is ATTACHMENT 2
recommended to be designed to handle future build-out flows. The 2012 Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse (third edition) published by the National Water Research Institute (NWRI) in collaboration with Water Research Foundation (WRF) (hereafter referred to as the 2012 NWRI UV Guidelines) specifies that a different minimum design UV transmittance (UVT) value is appropriate when using media filtration compared to membrane filtration upstream of the UV system.

Therefore, assuming the secondary treatment system at the WQCF will be expanded with MBRs (discussed further in Chapter 10), the UV system influent flow for the expanded WQCF will be a combined flow from both the existing filters and the new MBR system, and it is appropriate to use combined peak flow and UVT design values. The required peak build-out flow for the new UV system is

Manteca City CouncilDecember 5, 2023

Manteca City Council
December 5, 2023