HomeMy WebLinkAboutRESO 9630160928 jb 6053825 1
Resolution No. 9630
Resolution of the Council of the City of Palo Alto Approving the
inancial Assistance Application to the State Water
Resources Control Board for Capital Improvement Projects Applicable
to the Regional Water Quality Control Plant
R E C I T A L S
A.
the Board makes funds available for various capital waterrelated projects.
B.
and maintain the Plant.
C. The City wishes to apply for State Revolving Fund funds to cover the cost of certain
capital improvement projects identified in the attached Long Range Facility Plan, Exhibit A.
D. The first State Revolving Fund application the City submits will cover the sludge
dewatering and loadout facility construction project. City staff anticipates seeking multiple
State Revolving Fund applications for other capital improvement projects identified in the Long
Range Facility Plan, under the authority granted by Council via this resolution.
The Council of the City of Palo Alto RESOLVES as follows:
SECTION 1. The Council hereby finds that
health, safety and welfare of the community to file Financial Assistance Application(s) with the
Board to seek funds made available under the State Revolving Fund for any of the CIP projects
listed in Exhibit A.
SECTION 2. The Council hereby authorizes and directs the City Manager or his designee,
the Director of Public Works or the Manager of the Plant, to:
(a) File and sign, for and on behalf of the City of Palo Alto, a Financial Assistance
Application for a financing agreement from the Board for the planning, design, and construction
(b) Provide the assurances, certifications, and commitments required for the financial
assistance application, including executing a financial assistance agreement from the Board and
any amendments or changes thereto.
(c) Represent the City in carrying out the Cit
agreement, including certifying disbursement requests on behalf of the city and compliance
with applicable state and federal laws.
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SECTION 3. The Council finds that the filing of a Financial Assistance Application with
the State Water Resources Control Board does not constitute a project requiring California
Environmental Quality Act (CEQA) review. This action does not meet the definition of a project
under Public Resources Code Section 21065 and CEQA Guidelines Section 15378(b)(5), because
it is an administrative governmental activity which will not cause a direct or indirect physical
change in the environment. An Initial Study/Mitigated Negative Declaration was prepared for
the sludge dewatering and loadout facility project and approved by Council on March 28, 2016
(Staff Report ID# 6424). Implementation of the primary sedimentation tanks, fixed film
reactors, and the laboratory/environmental service building projects is subject to future CEQA
analysis.
INTRODUCED AND PASSED: October 17, 2016
AYES: BERMAN, BURT, DUBOIS, FILSETH, HOLMAN, KNISS, SCHARFF, SCHMID, WOLBACH
NOES:
ABSENT:
ABSTENTIONS:
ATTEST:
City Clerk Mayor
APPROVED AS TO FORM: APPROVED:
Senior Deputy City Attorney City Manager
Director of Public Works
Director of Administrative Services
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2700 YGNACIO VALLEY ROAD • SUITE 200 • WALNUT CREEK, CALIFORNIA 94598 • 925.932.1710 • 925.930.0208
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City of Palo Alto
LONG RANGE FACILITIES PLAN FOR THE
REGIONAL WATER QUALITY CONTROL PLANT
FINAL
August 2012
08/20/2012 08/20/2012
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PARWQCP Long Range Facilities Plan – Final Report
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City of Palo Alto
LONG RANGE FACILITIES PLAN
TABLE OF CONTENTS
Page No.
CHAPTER 1 - EXECUTIVE SUMMARY ....................................................................... 1-1
1.1 INTRODUCTION .................................................................................................... 1-1
1.2 BACKGROUND ...................................................................................................... 1-1
1.3 PARTNER AGENCY AND PUBLIC REVIEW PROCESS ................................... 1-3
1.4 PLAN DEVELOPMENT .......................................................................................... 1-4
1.5 PROJECTED FUTURE NEEDS .............................................................................. 1-5
1.6 EXISTING FACILITIES AND CAPACITY ........................................................... 1-7
1.7 CONDITION ASSESSMENT .................................................................................. 1-7
1.8 REGULATORY REQUIREMENTS ...................................................................... 1-10
1.9 SOLIDS TREATMENT ALTERNATIVES .......................................................... 1-12
1.10 LIQUID TREATMENT ALTERNATIVES ........................................................... 1-20
1.11 RECOMMENDATIONS ........................................................................................ 1-22
1.12 IMPLEMENTATION PLAN FOR RECOMMENDED PROJECTS .................... 1-26
1.12.1 Financing .................................................................................................... 1-28
1.12.2 Partner Agencies Shares ............................................................................. 1-28
ATTACHMENTS ............................................................................................................. 1-30
CHAPTER 2 - INTRODUCTION/BACKGROUND ...................................................... 2-1
2.1 PLANT HISTORY AND LOCATION .................................................................... 2-1
2.1.1 Early History (1894-1934) ............................................................................ 2-1
2.1.2 Palo Alto Treatment Plant (1934-1972) ........................................................ 2-1
2.1.3 Regional Water Quality Control Plant (1968 - present) ............................... 2-2
2.1.4 Recycled Water Plant (1975 – present) ........................................................ 2-4
2.2 PARTNERS AND SERVICE AREA ....................................................................... 2-5
2.3 ENVIRONMENTAL SETTING AND LAND USES .............................................. 2-5
2.3.1 Palo Alto Baylands Setting ........................................................................... 2-7
2.3.1 Biological and Regulatory Setting .............................................................. 2-10
2.4 OVERVIEW OF THE LRFP PROCESS ................................................................ 2-10
2.5 DECISION PROCESS AND EVALUATION CRITERIA .................................... 2-11
2.5.1 “Long Term Goals” ..................................................................................... 2-12
2.5.2 Evaluation Criteria and Minimum Alternative Requirements .................... 2-13
2.5.3 Initial Qualitative Screening ....................................................................... 2-14
2.5.4 Viable Alternative Evaluation .................................................................... 2-15
2.5.1 Prioritization and Presentation to the Public .............................................. 2-15
2.6 STAKEHOLDER PROCESS ................................................................................. 2-17
2.7 TECHNICAL ADVISORY GROUP REVIEW ..................................................... 2-17
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2.8 MEETING WITH THE PARTNERS ..................................................................... 2-18
CHAPTER 3 - HISTORICAL AND PROJECTED FLOWS AND LOADS ................ 3-1
3.1 BACKGROUND ...................................................................................................... 3-1
3.2 HISTORICAL POPULATION, FLOWS, AND LOADS ........................................ 3-1
3.3 PROJECTED POPULATION .................................................................................. 3-7
3.4 PROJECTED FLOWS AND LOADS ...................................................................... 3-7
3.4.1 Projections Based on Per Capita Flows and Loads ....................................... 3-7
3.4.2 Partner Agency Projections .......................................................................... 3-8
3.4.3 Wet Weather Flow Projections ................................................................... 3-11
3.4.3.1 Collection System ......................................................................... 3-11
3.4.3.2 Climate Change – Precipitation Patterns ...................................... 3-13
3.4.3.3 Projection of Wet Weather Flows ................................................ 3-14
3.5 UPSTREAM INTERVENTION ............................................................................. 3-16
3.5.1 Diversions ................................................................................................... 3-16
3.5.2 Distributed Treatment ................................................................................. 3-16
3.6 RECYCLED WATER DEMAND SCENARIOS ................................................... 3-17
3.6.1 Background ................................................................................................. 3-17
3.6.2 Historical Demands ..................................................................................... 3-17
3.6.3 Projected Demands ..................................................................................... 3-18
CHAPTER 4 - EXISTING FACILITIES AND CAPACITY EVALUATION ............. 4-1
4.1 HISTORY OF THE RWQCP FACILITIES ............................................................. 4-1
4.2 EXISTING FACILITIES DESCRIPTION ............................................................... 4-1
4.2.1 Interceptor ................................................................................................... 4-12
4.2.2 Influent Junction Box and Septage ............................................................. 4-13
4.2.3 Headworks .................................................................................................. 4-15
4.2.3.1 Bar Screens ................................................................................... 4-15
4.2.3.2 Old and New Pumping Plant ........................................................ 4-15
4.2.3.3 Grit Removal ................................................................................ 4-15
4.2.4 Primary Treatment ...................................................................................... 4-16
4.2.5 Secondary Treatment .................................................................................. 4-17
4.2.5.1 Fixed Film Reactors ..................................................................... 4-17
4.2.5.2 Activated Sludge Process (Aeration Basins and Secondary
Clarifiers) ...................................................................................... 4-18
4.2.6 Tertiary Treatment ...................................................................................... 4-18
4.2.7 Disinfection ................................................................................................. 4-19
4.2.8 Outfalls ........................................................................................................ 4-20
4.2.9 Recycled Water ........................................................................................... 4-20
4.2.10 Solids Treatment and Handling .................................................................. 4-21
4.2.10.1 Sludge and Scum Handling .......................................................... 4-21
4.2.10.2 Ash Handling ................................................................................ 4-22
4.2.11 Utility Systems ............................................................................................ 4-23
4.2.11.1 Water Systems .............................................................................. 4-23
4.2.11.2 Compressed Air Systems .............................................................. 4-25
4.2.11.3 Heating, Ventilating, and Air Conditioning Systems ................... 4-25
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4.2.11.4 Power Systems .............................................................................. 4-25
4.2.11.5 Instrumentation and Control System ............................................ 4-26
4.3 PLANT PERFORMANCE AND CRITERIA REVIEW ........................................ 4-26
4.3.1 Overall Performance Summary ................................................................... 4-26
4.3.2 Process Performance Summary .................................................................. 4-28
4.3.2.1 Headworks and Influent Pumping ................................................ 4-28
4.3.2.2 Primary Sedimentation Tanks ...................................................... 4-33
4.3.2.3 Fixed Film Reactors ..................................................................... 4-34
4.3.2.4 Aeration Basins ............................................................................ 4-34
4.3.2.5 Secondary Clarifiers ..................................................................... 4-35
4.3.2.6 Dual Media Filters ........................................................................ 4-37
4.3.2.7 Recycled Water Filters ................................................................. 4-37
4.3.2.8 Recycled Water Chlorine Contact Basin ...................................... 4-37
4.3.2.9 Ultraviolet Disinfection ................................................................ 4-37
4.3.2.10 Gravity Thickening ....................................................................... 4-38
4.3.2.11 Solids Dewatering ........................................................................ 4-38
4.3.2.12 Incineration ................................................................................... 4-38
4.4 CAPACITY ANALYSIS ........................................................................................ 4-39
4.4.1 Peak Flow Capacity .................................................................................... 4-39
4.4.2 Organic Loading Capacity .......................................................................... 4-39
4.4.3 Operational Data Collection ....................................................................... 4-41
CHAPTER 5 - EXISTING PLANT ASSESSMENT ....................................................... 5-1
5.1 INTRODUCTION .................................................................................................... 5-1
5.2 CONDITION ASSESSMENT .................................................................................. 5-1
5.2.1 Summary ....................................................................................................... 5-2
5.2.2 Headworks .................................................................................................... 5-2
5.2.3 Primary Treatment ........................................................................................ 5-7
5.2.4 Secondary Treatment .................................................................................... 5-9
5.2.5 Tertiary Treatment ...................................................................................... 5-11
5.2.6 Disinfection / Recycled Water .................................................................... 5-12
5.2.7 Solids Treatment and Handling .................................................................. 5-12
5.2.8 General ........................................................................................................ 5-15
5.3 OCCUPIED BUILDING DEFICIENCIES ............................................................ 5-16
5.3.1 Administration Building ............................................................................. 5-16
5.3.2 Maintenance Building and Warehouse ....................................................... 5-16
5.3.3 Operations Building .................................................................................... 5-17
5.4 OVERALL PLANT SPATIAL CONSIDERATIONS ........................................... 5-17
5.5 INFLUENT JOINT INTERCEPTOR SEWER ANALYSIS .................................. 5-19
5.6 OUTFALL CAPACITY ANALYSIS ..................................................................... 5-20
5.7 PLANT PIPELINE ANALYSIS ............................................................................. 5-21
5.8 IMPROVED OPERATIONS AND ENERGY EFFICIENCY ............................... 5-28
5.8.1 Source Control for Energy Savings ............................................................ 5-28
5.8.2 Miscellaneous Energy Saving Projects ....................................................... 5-28
5.8.3 2012 Tertiary Upgrade Project ................................................................... 5-29
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CHAPTER 6 - REGULATORY REQUIREMENTS ...................................................... 6-1
6.1 SUMMARY OF THE EXISTING NPDES PERMIT .............................................. 6-1
6.1.1 Permit Effluent Limits .................................................................................. 6-1
6.1.1.1 Mercury Effluent Limits ................................................................. 6-2
6.1.1.2 Dioxin-TEQ Effluent Limits .......................................................... 6-3
6.1.1.3 PCB Effluent Limitations ............................................................... 6-3
6.1.2 Other Permit Provisions ................................................................................ 6-4
6.1.3 Wet Weather Discharges ............................................................................... 6-5
6.1.4 Recycled Water ............................................................................................. 6-5
6.2 REGULATORY CONSIDERATIONS .................................................................... 6-6
6.2.1 Nutrient Removal .......................................................................................... 6-7
6.2.1.1 Nationwide ..................................................................................... 6-7
6.2.1.2 State of California ........................................................................... 6-8
6.2.1.3 San Francisco Bay .......................................................................... 6-8
6.2.2 Microconstituents and Bioaccumulative Constituents .................................. 6-9
6.2.3 Toxicity ....................................................................................................... 6-10
6.2.4 Recycled Water ........................................................................................... 6-10
6.2.4.1 California State Recycled Water Policy ....................................... 6-10
6.2.4.2 Title 22 Draft Groundwater Recharge Reuse Regulations ........... 6-12
6.2.4.3 Filter Loading Rates ..................................................................... 6-12
6.2.5 Land Application and Beneficial Use/Disposal of Biosolids ..................... 6-13
6.2.5.1 Governing Regulations ................................................................. 6-13
6.2.6 Governing Regulations for Sewage Sludge Incineration ............................ 6-15
6.2.7 Air Emissions .............................................................................................. 6-19
6.2.7.1 Federal Regulations ...................................................................... 6-20
6.2.7.2 State Regulations .......................................................................... 6-21
6.2.7.3 Bay Area Air Quality Management District Regulations ............ 6-22
6.2.7.4 Greenhouse Gas Emissions .......................................................... 6-23
6.2.8 Cross-Media Impacts .................................................................................. 6-25
6.2.9 Hazardous Materials and Wastes ................................................................ 6-25
6.3 FUTURE REGULATORY SCENARIOS .............................................................. 6-26
6.3.1 Approach to Development of Regulatory Scenarios .................................. 6-26
6.3.2 Long Term Regulatory Scenario Through 2062 ......................................... 6-27
6.3.3 Summary ..................................................................................................... 6-28
CHAPTER 7 - SOLIDS TREATMENT ALTERNATIVES DEVELOPMENT AND
SCREENING ....................................................................................................................... 7-1
7.1 PURPOSE AND OVERVIEW ................................................................................. 7-1
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7.2 BASIS FOR EVALUATION/PLANNING CONSIDERATIONS .......................... 7-1
7.2.1 Projected Flow and Loads ............................................................................. 7-1
7.2.2 Regulatory Requirements ............................................................................. 7-2
7.2.3 Site Considerations ....................................................................................... 7-2
7.2.4 Solids Treatment Alternatives Development Process ................................... 7-2
7.3 SOLIDS DISPOSITION OPTIONS ......................................................................... 7-2
7.3.1 Landfill Disposal ........................................................................................... 7-4
7.3.1.1 Direct Landfill of Solids ................................................................. 7-4
7.3.1.2 Alternative Daily Cover ................................................................. 7-4
7.3.1.3 Ash Disposal ................................................................................... 7-4
7.3.2 Land Application .......................................................................................... 7-4
7.3.3 Marketable Products ..................................................................................... 7-5
7.3.3.1 Biosolids Compost .......................................................................... 7-5
7.3.3.2 Dried Biosolids ............................................................................... 7-5
7.3.3.3 Pyrolysis Char/Oil .......................................................................... 7-7
7.3.4 Regional Opportunities ................................................................................. 7-8
7.3.5 Comparison of Disposition Implementation and Longevity ......................... 7-8
7.4 SOLIDS TREATMENT PROCESS ALTERNATIVES .......................................... 7-8
7.4.1 Summary of Existing Solids Treatment Facilities ........................................ 7-9
7.4.2 Sludge Thickening and Dewatering .............................................................. 7-9
7.4.3 Thermal Conversion.................................................................................... 7-10
7.4.3.1 Multiple Hearth Furnace Incineration .......................................... 7-10
7.4.3.2 Fluidized Bed Incineration ........................................................... 7-11
7.4.3.3 Plasma Arc Assisted Oxidation .................................................... 7-12
7.4.3.4 Gasification ................................................................................... 7-13
7.4.3.5 Pyrolysis ....................................................................................... 7-14
7.4.4 Anaerobic Digestion ................................................................................... 7-14
7.4.5 Composting On-site .................................................................................... 7-16
7.4.6 Composting Off-site .................................................................................... 7-17
7.4.7 Thermal Drying ........................................................................................... 7-17
7.4.7.1 Direct Drying ................................................................................ 7-18
7.4.7.2 Indirect Drying ............................................................................. 7-19
7.4.7.3 Storage of Dried Biosolids ........................................................... 7-19
7.4.8 Regional Opportunities for Solids Handling and Disposal ......................... 7-19
7.4.8.1 Bay Area Biosolids-to-Energy Project ......................................... 7-20
7.4.8.2 San Jose/Santa Clara Water Pollution Control Plant .................... 7-20
7.5 INITIAL SCREENING OF SOLIDS TREATMENT ALTERNATIVES ............. 7-21
7.6 COMPARISON OF VIABLE ALTERNATIVES .................................................. 7-24
7.6.1 Assumptions for Evaluating the Viable Biosolids Alternatives ................. 7-24
7.6.2 Alternatives Evaluation ............................................................................... 7-25
7.6.3 Net Present Value ....................................................................................... 7-28
7.6.4 Greenhouse Gas Emissions Analysis .......................................................... 7-28
7.6.5 Sensitivity of Biosolids Alternatives to Changes in Assumptions ............. 7-32
7.6.5.1 Enhanced Primary ........................................................................ 7-32
7.6.5.2 Liquid Treatment Alternatives ..................................................... 7-32
7.6.5.3 FOG, Food Waste, and Other Import Materials ........................... 7-33
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7.7 PROMISING TECHNOLOGIES ........................................................................... 7-35
7.7.1 Thermal Conversion Processes ................................................................... 7-35
7.7.2 Microscreen-Gasification Process .............................................................. 7-35
7.7.3 Fuel Cells .................................................................................................... 7-36
7.8 SUMMARY AND RECOMMENDATIONS ......................................................... 7-36
7.8.1 Recommendations ....................................................................................... 7-39
CHAPTER 8 - LIQUIDS TREATMENT ALTERNATIVES DEVELOPMENT
AND SCREENING ............................................................................................................. 8-1
8.1 PURPOSE AND OVERVIEW ................................................................................. 8-1
8.2 BASIS FOR EVALUATION/PLANNING CONSIDERATIONS .......................... 8-1
8.2.1 Projected Flow and Loads ............................................................................. 8-1
8.2.2 Regulatory Requirements ............................................................................. 8-1
8.2.3 Site Considerations ....................................................................................... 8-2
8.2.4 Alternatives Development Process ............................................................... 8-3
8.3 SUMMARY OF EXISTING LIQUIDS TREATMENT FACILITIES AND
FUTURE NEEDS ..................................................................................................... 8-3
8.3.1 Preliminary Treatment .................................................................................. 8-6
8.3.2 Primary Treatment ........................................................................................ 8-6
8.3.3 Secondary/Tertiary Treatment ...................................................................... 8-6
8.3.4 Recycled Water Facilities ............................................................................. 8-7
8.3.5 Advanced Treatment ..................................................................................... 8-9
8.3.6 Support Facilities .......................................................................................... 8-9
8.3.7 Summary of Recommendations for Common Facilities ............................. 8-15
8.4 LIQUIDS TREATMENT ALTERNATIVES ........................................................ 8-15
8.4.1 Suspended Growth Processes ..................................................................... 8-16
8.4.2 Attached Growth Processes ........................................................................ 8-16
8.4.3 Hybrid of Suspended and Attached Growth Processes .............................. 8-17
8.4.4 Anaerobic Liquid Treatment Processes ...................................................... 8-17
8.5 INITIAL QUALITATIVE SCREENING OF ALTERNATIVES .......................... 8-17
8.6 COMPARISON OF VIABLE ALTERNATIVES .................................................. 8-19
8.6.1 Assumptions for Evaluating the Viable Liquids Alternatives .................... 8-19
8.6.2 Alternatives Evaluation and Site Layouts ................................................... 8-21
8.6.2.1 Alternative 2 – Membrane Bioreactors ........................................ 8-21
8.6.2.2 Alternative 3 – Trickling Filters/Aeration Basins/
Denitrification Filters ................................................................... 8-23
8.6.2.3 Alternative 5 – Integrated Fixed-Film Activated Sludge (IFAS) . 8-25
8.6.3 Alternative Cost Comparison ...................................................................... 8-25
8.6.4 Greenhouse Gas Emissions Analysis .......................................................... 8-27
8.6.4.1 Alternative Carbon Sources for Denitrification ........................... 8-30
8.6.5 Sensitivity of Liquids Alternatives to Changes in Assumptions ................ 8-30
8.6.5.1 Changes in Flow and Load Projections ........................................ 8-30
8.6.5.2 Impact of Solids Treatment Alternatives ...................................... 8-31
8.7 SUMMARY AND RECOMMENDATIONS ......................................................... 8-31
8.7.1 Summary of Recommended Projects .......................................................... 8-31
8.7.2 Promising Technologies ............................................................................. 8-34
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8.7.2.1 Microscreens................................................................................. 8-34
8.7.2.2 Anaerobic Treatment .................................................................... 8-34
8.7.2.3 Alternative Nitrogen Reduction Processes ................................... 8-34
CHAPTER 9 - RECOMMENDATIONS AND IMPLEMENTATION PLAN ............. 9-1
9.1 INTRODUCTION .................................................................................................... 9-1
9.2 SUMMARY OF NEEDS AND OPPORTUNITIES ................................................ 9-1
9.3 RECOMMENDED PROGRAMS AND PROJECTS ............................................... 9-2
9.3.1 Projected Flows/Loads and Capacity Projects .............................................. 9-2
9.3.2 Solids Handling Project ................................................................................ 9-5
9.3.2.1 Dry Digestion and Measure E ........................................................ 9-6
9.3.3 Replacement Projects .................................................................................... 9-7
9.3.4 Rehabilitation Projects .................................................................................. 9-9
9.3.5 Future Regulatory Requirement Projects .................................................... 9-10
9.3.6 Future Recycled Water Projects ................................................................. 9-11
9.3.7 Other Recommendations ............................................................................. 9-12
9.3.8 Site Plan for Recommended Facilities ........................................................ 9-12
9.3.9 Summary of Overall Costs for Recommended Facilities ........................... 9-14
9.4 IMPLEMENTATION PLAN ................................................................................. 9-14
9.4.1 Cash Flow ................................................................................................... 9-16
9.4.2 Operations and Maintenance Costs ............................................................. 9-16
9.4.3 Total Annual Cost Projection ..................................................................... 9-20
9.4.3.1 Minor CIP Projects ....................................................................... 9-20
9.4.3.2 Major CIP Projects ....................................................................... 9-22
9.4.3.3 Future CIP Projects....................................................................... 9-22
9.5 FUNDING OPTIONS ............................................................................................. 9-23
9.5.1 CIP Cost Recovery ...................................................................................... 9-25
9.5.2 Pay-As-You-Go Financing ......................................................................... 9-25
9.5.2.1 Utility Fees and Benefit Assessment Fees.................................... 9-26
9.5.2.2 General Fund ................................................................................ 9-26
9.5.2.3 Development Charges/Connection Fees ....................................... 9-26
9.5.3 Debt Financing ............................................................................................ 9-27
9.5.3.1 Revenue Bonds ............................................................................. 9-27
9.5.3.2 Certificates of Participation .......................................................... 9-27
9.5.3.3 General Obligation Bonds ............................................................ 9-27
9.5.3.4 Assessment District Bonds ........................................................... 9-28
9.5.4 Grants and Loans ........................................................................................ 9-28
9.5.4.1 The Clean Water State Revolving Fund (CWSRF) Funding ....... 9-28
9.6 DEBT SERVICING ................................................................................................ 9-29
9.6.1 Capital Projects Debt Servicing Estimates ................................................. 9-29
9.6.2 Partner Cost Allocation ............................................................................... 9-31
LIST OF REFERENCES
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LIST OF APPENDICES
APPENDIX A Environmental Setting and Land Uses
APPENDIX B Public Workshops 2-5 and City Council Study Session Presentations
APPENDIX C RWQCP Facility Condition Assessment Final Report, Appendix N: Facility
Assessment Summaries
APPENDIX D RWQCP Facility Condition Assessment Final Report, Appendix H: Retrofit
Recommendations – Final Report
APPENDIX E RWQCP Condition Assessment Summary
APPENDIX F Incineration – Seismic Evaluation Technical Memorandum
APPENDIX G Seismic Evaluation of the Piles Supporting the Incinerator and Operations
Buildings Technical Memorandum
APPENDIX H Sewer Interceptor Rehabilitation and Replacement Study Technical
Memorandum
APPENDIX I Outfall Capacity Analysis Technical Memorandum
APPENDIX J National Pollutant Discharge Elimination System Permit
APPENDIX K Anaerobic Digestion Options
APPENDIX L Initial Qualitative Screening Matrix for the Solids Alternatives
APPENDIX M Basis of Cost Technical Memorandum
APPENDIX N Solids Treatment Alternatives Cost Estimates Detail
APPENDIX O Greenhouse Gas Emissions Estimates Detail
APPENDIX P Ozone Sizing and Cost Estimate for TOrC Removal
APPENDIX Q Liquid Treatment Alternative Cost Estimates Detail
APPENDIX R Technology Installation Lists
APPENDIX S Summary of Recommended Projects
APPENDIX T Yearly O&M Projections for Solids and Liquids Treatment
APPENDIX U LRFP Finance Overview
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LIST OF TABLES
Table 1.1 Recycled Water Demands in the Near, Intermediate and Long Term .......... 1-6
Table 1.2 Summary of Needs and Opportunities for Existing Facilities .................... 1-11
Table 1.3 Summary of Potential Regulatory Issues and Solutions ............................. 1-14
Table 1.4 Biosolids Treatment and Disposition Alternatives Comparison ................. 1-16
Table 1.5 Liquid Treatment Alternatives Comparison ............................................... 1-21
Table 1.6 Summary of Recommended Projects and Estimated Costs ........................ 1-26
Table 1.7 Summary of Preliminary Partner Cost Allocation for Major CIP
Projects ........................................................................................................ 1-29
Table 2.1 Average Partner Flow into the RWQCP and 72-inch Joint Intercepting
Sewer Wet Weather Flow Capacity Rights .................................................. 2-5
Table 2.2 Evaluation Criteria Used to Evaluate Alternatives ..................................... 2-14
Table 3.1 Historical Average Dry Weather Influent Flows, Loads, and
Concentrations .............................................................................................. 3-3
Table 3.2 Historical Populations Per Partner Agency .................................................. 3-5
Table 3.3 Historical Average Dry Weather Per Capita Flows and Loads .................... 3-5
Table 3.4 Historical Flow Peaking Factors ................................................................... 3-6
Table 3.5 Historical Maximum Month to Average Dry Weather Peaking Factors ...... 3-6
Table 3.6 Historic and Projected Populations Served by the RWQCP ......................... 3-7
Table 3.7 Projected Service Area Flows, Loads, and Concentrations (based on Per
capita Values and ABAG projections) .......................................................... 3-8
Table 3.8 Projected Partner Agency Wastewater Flows in Million Gallons per Day .. 3-9
Table 3.9 Alternate Projections of Service Area Flows, Loads, and Concentrations . 3-10
Table 3.10 Projected Peak Wet Weather Flows in Million Gallons per Day ............... 3-15
Table 3.11 Historical Recycled Water Supply Flows ................................................... 3-18
Table 3.12 Recycled Water Demands in the Near, Intermediate and Long Term ........ 3-18
Table 4.1 Summary of Existing Facilities ..................................................................... 4-4
Table 4.2 Overall Pollutant Removal Performance Summary .................................... 4-27
Table 4.3 Plant Design Criteria and Performance Summary ...................................... 4-30
Table 4.4 Influent Pumping Capacity ......................................................................... 4-33
Table 4.5 Peak Hour Wet Weather Flow Capacity ..................................................... 4-39
Table 4.6 Organic Loading Capacity .......................................................................... 4-40
Table 5.1 Summary of Condition Assessment Findings ............................................... 5-4
Table 5.2 Summary of Existing Pipeline Material Types ........................................... 5-22
Table 5.3 Pipe Replacement Unit Costs ..................................................................... 5-22
Table 5.4 Plant Pipeline Analysis ............................................................................... 5-24
Table 6.1 Effluent Limits in 2009 NPDES Permit ........................................................ 6-2
Table 6.2 Mercury Effluent Limits in San Francisco Bay Mercury Watershed
Permit ............................................................................................................ 6-3
Table 6.3 PCB Effluent Limits in San Francisco Bay Mercury and PCB Watershed
Permit ............................................................................................................ 6-4
Table 6.4 Approved Uses of Recycled Water ............................................................... 6-6
Table 6.5 Pollutant Limits for Land Applied Biosolids .............................................. 6-14
Table 6.6 Emission Limits for Existing Sewage Sludge Incinerators ........................ 6-18
Table 6.7 Emission Limits for New Sewage Sludge Incinerators .............................. 6-19
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Table 6.8 Emission Limits for Existing Sewage Sludge Incinerators and RWQCP
Performance ................................................................................................ 6-21
Table 6.9 ATCM Emission Standards for New Stationary Emergency Standby
Diesel-Fueled CI Engines in g/bhp-hr (g/kW-hr) ....................................... 6-22
Table 6.10 Greenhouse Gas Emissions Thresholds for Reporting Years 2010, 2011
and Beyond ................................................................................................. 6-24
Table 6.11 Summary of Potential Regulatory Issues and Solutions ............................. 6-28
Table 7.1 Comparison of Disposition Options ............................................................. 7-9
Table 7.2 Summary of the Initial Qualitative Screening Evaluation .......................... 7-23
Table 7.3 Comparison of Energy Use for Biosolids Treatment
Alternatives (2045) ..................................................................................... 7-26
Table 7.4 Comparison of Energy Use for Biosolids Treatment
Alternatives (2019) ..................................................................................... 7-27
Table 7.5 Biosolids Treatment and Disposition Alternatives Cost Estimates ............ 7-28
Table 7.6 Solids Treatment Alternatives Annual On-site CO2e Emissions in
Metric Tons ................................................................................................. 7-30
Table 7.7 Sensitivity Analysis of FOG and Food Waste Addition ............................. 7-34
Table 7.8 Biosolids Treatment Alternatives Summary of Considerations ................. 7-37
Table 8.1 Existing and Potential Future Regulatory Requirements .............................. 8-2
Table 8.2 Recycled Water Demands in the Near and Long Term ................................ 8-8
Table 8.3 Summary of Iterations to Meet Effluent Goal of 600 mg/L TDS ................. 8-9
Table 8.4 Summary of RO System Capital Costs in Millions of 2015 Dollars ............ 8-9
Table 8.5 Summary of Recommended Project Costs for Common Facilities ............ 8-15
Table 8.6 Secondary Processes to Meet Future Discharge Requirements .................. 8-16
Table 8.7 Summary of the Initial Qualitative Screening Evaluation .......................... 8-20
Table 8.8 Liquid Treatment Alternatives Cost Estimates ........................................... 8-27
Table 8.9 Liquids Treatment Alternatives Annual On-site CO2e Emissions in
Metric Tons for 2035 .................................................................................. 8-28
Table 8.10 Liquid Treatment Alternatives Summary of Considerations ...................... 8-32
Table 9.1 Summary of Needs and Opportunities .......................................................... 9-3
Table 9.2 Summary of Recommended Solids Project Costs (only one to be
selected) ........................................................................................................ 9-6
Table 9.3 Summary of Recommended Replacement Project Costs .............................. 9-8
Table 9.4 Summary of Recommended Support Facilities Project Costs ...................... 9-8
Table 9.5 Summary of Recommended Rehabilitation Projects .................................... 9-9
Table 9.6 Summary of Recommended Future Regulatory Project Costs ................... 9-11
Table 9.7 Summary of Recommended Recycled Water Projects ............................... 9-12
Table 9.8 Summary of Recommended Project Costs ................................................. 9-14
Table 9.9 Summary of Minor Projects ........................................................................ 9-22
Table 9.10 Summary of Major Projects ........................................................................ 9-23
Table 9.11 Summary of Future Major Projects............................................................. 9-23
Table 9.12 Summary of Estimate of Aggregate Debt Service for Major CIP .............. 9-30
Table 9.13 Summary of Preliminary Partner Cost Allocation for Major CIP
Projects ........................................................................................................ 9-32
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LIST OF FIGURES
Figure 1.1 RWQCP Service Area and Partner Agency Boundaries............................... 1-2
Figure 1.2 Categories and Evaluation Criteria Considered For Alternative
Evaluation ..................................................................................................... 1-5
Figure 1.3 Existing and Projected Average Dry Weather Flow into RWQCP .............. 1-6
Figure 1.4 Existing Facilities Liquid and Biosolids Process Flow Diagram ................. 1-8
Figure 1.5 Aerial Top View Showing the Layout of Existing Facilities ........................ 1-9
Figure 1.6 Regulatory Scenarios for RWQCP Long Range Facilities Plan ................. 1-13
Figure 1.7 Thermal Solids Process ............................................................................... 1-15
Figure 1.8 Digestion Solids Process ............................................................................. 1-15
Figure 1.9 Regional Opportunities Solids Process ....................................................... 1-15
Figure 1.10 Net Present Value for Solids Alternatives in 2015 Dollars ........................ 1-17
Figure 1.11 Greenhouse Gas Emission Estimates for Solids Alternatives in 2045 ....... 1-18
Figure 1.12 Annual Energy Usage/Production for Solids Alternatives in 2019 ............ 1-19
Figure 1.13 Membrane Bioreactor Process .................................................................... 1-20
Figure 1.14 Trickling Filters/Activated Sludge/Denitrification Filters Process ............ 1-20
Figure 1.15 Integrated Fixed-Film Activated Sludge Process ....................................... 1-21
Figure 1.16 Overall RWQCP Space Requirements for Future Facilities ....................... 1-25
Figure 1.17 Contributions and Cost of Project Categories to Overall CIP Program ..... 1-27
Figure 1.18 Cash Flow for the Major Project Categories of CIP Program .................... 1-27
Figure 1.19 Distribution of Major Project Categories and Costs to Overall CIP
Program ....................................................................................................... 1-28
Figure 2.1 RWQCP Neighbors and Land Use ............................................................... 2-3
Figure 2.2 RWQCP Service Area and Partner Agency Boundaries............................... 2-6
Figure 2.3 Palo Alto Baylands Map ............................................................................... 2-8
Figure 2.4 Palo Alto Baylands Management Units ........................................................ 2-9
Figure 2.5 Project Alternatives Evaluation and Prioritization Process ........................ 2-12
Figure 2.6 Initial Qualitative Screening Matrix and Criteria for Solids
Alternatives ................................................................................................. 2-16
Figure 2.7 Initial Qualitative Screening Matrix and Criteria for Liquids
Alternatives ................................................................................................. 2-16
Figure 2.8 Example Resulting Matrix from the Initial Qualitative Screening
Process ........................................................................................................ 2-17
Figure 3.1 RWQCP Service Area and Partner Agency Boundaries.............................. 3-2
Figure 3.2 Historical Average Monthly Influent Flows ................................................. 3-4
Figure 3.3 Historical Average Monthly Influent BOD, TSS, and Ammonia Loads ...... 3-4
Figure 3.4 Existing and Projected Average Dry Weather Flow into RWQCP ............ 3-11
Figure 4.1 Existing Facilities Liquid and Biosolids Process Flow Diagram ................. 4-2
Figure 4.2 Aerial top View Showing the Layout of Existing Facilities ......................... 4-3
Figure 4.3 72-inch Joint Intercepting Sewer ................................................................ 4-14
Figure 4.4 Monthly Average Effluent BOD, TSS, and Ammonia ............................... 4-29
Figure 4.5 Minimum Recommended Solids Retention Time ....................................... 4-35
Figure 4.6 Allowable Clarifier Overflow Rates ........................................................... 4-36
Figure 5.1 Aerial Top View Showing the Layout of Existing Facilities with
Major Pipelines ............................................................................................. 5-3
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Figure 5.2 Cracks Observed on the Primary Sedimentation Tanks Roof ...................... 5-8
Figure 5.3 Top Layers of Fixed Film Reactor Media are Aging and Showing
Buildup .......................................................................................................... 5-9
Figure 5.4 Visible Corrosion on the Secondary Clarifier Equipment .......................... 5-10
Figure 5.5 Corrosion Inside the Hearths of the Multiple Hearth Furnaces .................. 5-14
Figure 6.1 Status of Biosolids Land Application Ordinances by County .................... 6-16
Figure 6.2 Cross-Media Impacts: Key Wastewater Regulatory Issues ........................ 6-26
Figure 6.3 Regional Water Board Future Regulatory Scenarios .................................. 6-27
Figure 7.1 Existing and Future Solids Area Identified ................................................... 7-3
Figure 7.2 Status of Biosolids Land Application Ordinances by County ...................... 7-6
Figure 7.3 Dried Biosolids Pellets and Marketable Products ........................................ 7-7
Figure 7.4 Existing and Future Thermal Solids Processing ......................................... 7-10
Figure 7.5 Digestion Solids Process ............................................................................. 7-14
Figure 7.6 Drying Solids Process ................................................................................. 7-18
Figure 7.7 Regional Opportunities Solids Process ....................................................... 7-19
Figure 7.8 Annual On-site Greenhouse Gas Emissions for Each Biosolids
Treatment Alternative in 2045 .................................................................... 7-31
Figure 8.1 Existing Facilities Layout ............................................................................. 8-4
Figure 8.2 Existing Facilities Liquid Process Flow Diagram ........................................ 8-5
Figure 8.3 Preliminary Layout for the New Laboratory and Environmental
Services Building ........................................................................................ 8-11
Figure 8.3 Preliminary Layout for the New Laboratory and Environmental
Services Building (Continued) .................................................................... 8-12
Figure 8.4 Preliminary Layout for the Remodeled Operations Building ..................... 8-13
Figure 8.5 Preliminary Layout for the Expanded Warehouse Storage Space .............. 8-14
Figure 8.6 Membrane Bioreactor (Alternative 2) Process Flow Diagram ................... 8-21
Figure 8.7 Potential Membrane Bioreactor (Alternative 2) Layout ............................. 8-22
Figure 8.8 Trickling Filters/Activated Sludge/Denitrification Filters
(Alternative 3) Process Flow Diagram ....................................................... 8-23
Figure 8.9 Potential Trickling Filter/Activated Sludge/Denitrification Filter
(Alternative 3) Layout ................................................................................ 8-24
Figure 8.10 Integrated Fixed-Film Activated Sludge (Alternative 5) Process Flow
Diagram ....................................................................................................... 8-25
Figure 8.11 Potential Integrated Fixed-Film Activated Sludge (Alternative 5)
Layout ......................................................................................................... 8-26
Figure 8.12 Liquids Treatment Alternatives 2035 Annual CO2e Emissions in
Metric Tons ................................................................................................. 8-29
Figure 8.13 Overall RWQCP Space Requirements for Future Facilities ....................... 8-33
Figure 9.1 Overall RWQCP Space Requirements for Future Facilities ....................... 9-13
Figure 9.2 Contribution and Cost of Major Project Categories to Overall CIP
Program ....................................................................................................... 9-15
Figure 9.3 Schedule for Implementation of Recommended Projects ........................... 9-17
Figure 9.4 Contribution and Cost of Major CIP Categories to Overall CIP
Program ....................................................................................................... 9-18
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Figure 9.5 Cash Flow for the Major Project Categories of CIP Program from 2012
through 2062 ............................................................................................... 9-19
Figure 9.6 Incremental O&M Costs from 2015 through 2045 (in 2015 $) .................. 9-21
Figure 9.7 Cost of Major and Future Major CIP Categories to Overall CIP
Program ....................................................................................................... 9-24
Figure 9.8 Total Aggregate Debt Service for Existing and Major CIP Programs ....... 9-33
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CHAPTER 1
EXECUTIVE SUMMARY
1.1 INTRODUCTION
The City of Palo Alto operates the Regional Water Quality Control Plant (RWQCP) for the
benefit of the City and the surrounding communities. The City has provided wastewater
treatment services for 78 years. The RWQCP is located at the end of Embarcadero Road on
Embarcadero Way adjacent to the Palo Alto Airport, Byxbee Park, and the Emily Renzel
Wetlands.
The RWQCP prepared a comprehensive planning document in 1966 for a regional plant to move
to full secondary treatment; this is the first long range plan for RWQCP facilities since that plan.
The planning horizon for this study is 50 years and is focused on RWQCP’s on-site needs. The
RWQCP is facing several key issues: 1) aging infrastructure, 2) increasing regulatory
requirements and 3) increasing interest in finding alternatives to the existing solids incineration
process. For these reasons, the City decided to embark upon a planning process to look at the
long-term needs for the RWQCP facility to continue to provide reliable treatment and satisfy
regulations. To do this, the LRFP must determine the future needs (flows and loads), assess the
existing facilities capacity, condition and deficiencies, assess the treatment impacts of potential
future regulatory scenarios, develop alternatives for both solids and liquid treatment processes,
develop layouts for whole plant scenarios (leaving room for potential future facilities), and
develop recommendations and a financial plan for implementation.
1.2 BACKGROUND
The City of Palo Alto has provided wastewater collection services since 1899 and completed
construction of the first the Palo Alto Treatment Plant in 1934. In 1968, the Cities of Mountain
View and Los Altos agreed to retire their treatment plants and partner with the City of Palo Alto
to construct a regional secondary treatment plant – the Regional Water Quality Control Plant
(RWQCP). The original Palo Alto Treatment Plant site was expanded from a 3-acre site to a
25-acre site. The 25-acre site is located within the Palo Alto Baylands between Highway 101 and
San Francisco Bay. The 1968 agreement is good through July 1, 2035 and states Palo Alto is the
owner and operator of the plant. This agreement, and agreements with East Palo Alto Sanitary
District, Stanford University, and Los Altos Hills, require all six agencies to proportionately
share in the costs of building and maintaining the facilities. The service area for the RWQCP is
shown in Figure 1.1.
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The RWQCP was designed in 1969 and construction of the RWQCP was completed in 1972
providing secondary treatment to the City of Palo Alto and the partner agencies. Construction in
1980 added fixed film reactors and dual media filters. Construction in 1988 added additional
secondary clarifiers. Construction in 2010 added ultraviolet light disinfection.
The RWQCP has provided recycled water for landscape irrigation since 1975. Recycled water
use at Mountain View’s Shoreline Golf Course (Shoreline Golf Links) began in 1980, but was
suspended in 2001 due to failure of the recycled water pipeline. In 1992, the Water Reclamation
Master Plan (WRMP) was prepared and the distribution line was subsequently extended to Palo
Alto's Municipal Service Center (MSC) yard and a new pipeline was installed to the Palo Alto
Golf Course. In 2009, a new pipeline was installed to serve recycled water to existing and new
customers including Palo Alto’s Greer Park, Shoreline Park (and Golf Course) in Mountain
View, and other landscape irrigation customers in the North of Bayshore business area of
Mountain View. An expansion to Palo Alto’s Stanford Research Park area is being considered
and environmentally assessed.
1.3 PARTNER AGENCY AND PUBLIC REVIEW PROCESS
The City established a public workshop process as part of this LRFP to solicit input from the
stakeholders and partner agencies. Five (5) stakeholder workshops were held during the LRFP
development to provide an opportunity for interested parties to provide their input and/or
feedback throughout the LRFP process. The workshop topics are listed below in chronological
order and were publicly advertised on the City’s website a minimum of two (2) weeks prior to
the scheduled meeting. Presentation materials used for each workshop and notes taken to capture
public input were also posted on the City’s website.
Introduction and Goals (October 27, 2010).
Biosolids Options (February 9, 2011).
Decision Process and Liquid Treatment/Recycled Water (May 4, 2011).
Biosolids Alternatives (November 16, 2011).
Liquid Treatment Alternatives and Overall Recommendations (March 1, 2012).
In addition to the public workshops, special meetings were held with staff from the partner
agencies to keep them informed and to gather input. Partner meetings were held on
November 10, 2011 and April 23, 2012. At the conclusion of this LRFP project, the partner
agencies were provided administrative draft reports. Comments from the partner agencies were
incorporated into the Draft Report, which was also posted on the City of Palo Alto’s website.
The RWQCP staff also made public presentations on the LRFP at city council meetings
including:
Palo Alto City Council Study Session – May 7, 2012
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EPASD Study Session – June 7, 2012
Los Altos City Council Study Session – June 26, 2012
Palo Alto City Council Meeting – July 2, 2012
Los Alto Hills presentation – July 31, 2012
The City of Mountain View did not schedule a special study session.
As the projects recommended in this LRFP move forward, there will be additional opportunities
for public and partner agency review and input in future planning and design efforts, public
workshops and council updates.
1.4 PLAN DEVELOPMENT
Development of a long range facilities plan requires projection of future flows and loads,
evaluation of the existing facilities’ condition and capacity, and consideration of regulatory
changes that could require new or modified facilities. This information is then used to determine
future facility needs and alternatives for meeting those needs. Recommendations are developed
after a thorough comparison of alternatives. For this LRFP, a systematic process was used to
identify, screen, and evaluate the LRFP project alternatives (both solids and liquids). This
process consisted of five basic steps:
1. Establish “Long Term Goals.”
2. Establish evaluation criteria.
3. Initial qualitative screening.
4. Detailed alternative evaluation.
5. Prioritization and presentation of recommendation to the public.
The goals were largely set by previous efforts (The Long Term Goals (LTG) study conducted in
2001) and were presented at the first public workshop. Comments received at that workshop
were used to refine the goals. The goals were then used to develop evaluation criteria and
minimum project alternative requirements. Minimum alternative requirements included sizing
alternatives to meet projected influent flow and loads, meeting the projected capacity needs, and
meeting existing regulatory requirements. Evaluation criteria were developed and categorized
into four main categories, as shown in Figure 1.2. The overall decision process was presented to
stakeholders during the third public workshop.
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Figure 1.2 Categories and Evaluation Criteria Considered For Alternative Evaluation
1.5 PROJECTED FUTURE NEEDS
Future capacity needs of the RWQCP were developed by projecting influent flow and loads into
the plant. The projections were based on historical per capita flows and loads and the projected
service area population. Population estimates were based on projections by the Association of
Bay Area Governments (ABAG). Two different flow projections were developed, one based on
historical average per capita flows, and one based on projections provided by the partner
agencies to account for planned conservation measures, as shown in Figure 1.3. While these
different methods affect the projection of dry weather flows, as the population projection is
unchanged, the loadings will remain the same. In addition, the peak wet weather flow projections
are unchanged by conservation measures, as they are largely a result of inflow and infiltration
into the collection system during wet weather events.
In addition to evaluating the need for treatment capacity to handle projected influent flows and
loads, the project capacity needed to provide for recycled water demands in the service area was
also evaluated. The City of Palo Alto has implemented two of the identified four phases of its
recycled water system and currently serves users in both the City of Palo Alto and the City of
Mountain View. Estimates for future recycled water demands were based on past planning
efforts and are shown in Table 1.1. As the decision to expand the recycled water system is a
policy decision, a specific timeline has not been assigned to these phases.
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Figure 1.3 Existing and Projected Average Dry Weather Flow into RWQCP
Table 1.1 Recycled Water Demands in the Near, Intermediate and Long Term
(1)
Annual Average Flow
Rate (mgd)
Peak Month Flow
Rate (mgd)
Peak Hour Flow Rate
(mgd)
Near Term: Demand
for Phases 1-3 2.5 5.6 15.9
Intermediate Term:
Recommended Project
- 1992 WRMP
4.2 9.8 21.9
Long Term: Target
Users - 1992 WRMP 5.3 12.4 27.8
(2)
Notes:
(1) The planning horizon of the near, intermediate, and long term recycled water demands
depends on the timing of City Council decisions to implement.
(2) Estimated based on the peaking factors from the 1992 Water Reclamation Master Plan
(WRMP).
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1.6 EXISTING FACILITIES AND CAPACITY
The existing treatment processes at the RWQCP consist of headworks, primary sedimentation,
two-stage secondary treatment with fixed film reactors and aeration basins followed by clarifiers,
tertiary, disinfection, and recycled water treatment, as well as solids treatment and handling.
A process flow diagram showing the path of the liquid and solids streams through the RWQCP is
shown in Figure 1.4. Figure 1.5 shows an aerial view of the existing facilities, the location of its
boundaries as well as existing headworks, primary, secondary and tertiary treatment,
disinfection, recycled water, and biosolids treatment facilities. The existing facilities were found
to be operating within normal ranges, based on typical values used in engineering designs.
The RWQCP also has a good record for meeting its effluent discharge permit limits, for
discharge to the San Francisco Bay. There were only a few permit violations over the time period
analyzed (2005-2010). These violations were primarily for chlorodibromomethane, a by-product
of chlorine disinfection. In 2010, the new ultraviolet light disinfection system came on-line and
use of chlorine was eliminated for disinfection of effluent for Bay discharge.
Projected dry weather flows are anticipated to be between 28 and 34 mgd in the year 2062.
Based on the treatment processes design criteria and historical performance, it is anticipated that
the existing facilities will provide adequate capacity to meet dry weather and maximum month
flows into the near future (2035) assuming the same level of treatment is required. Higher levels
of treatment would require additional facilities as discussed in Section 1.9.
Capacity of peak wet weather flows appears to be limited not by the treatment facilities but in the
influent sewer and the outfall. Previous estimates of peak hour wet weather flow capacity for the
RWQCP were 80 mgd, but are not well documented. An evaluation of the 72-inch joint
interceptor sewer (which carries a large portion of the plant’s flow) as part of this LRFP indicates
a sewer capacity of between 63 and 69 mgd. An evaluation of the outfall also showed a potential
peak flow capacity restriction during extremely high tides and high flows. A collection system
estimate for all the contributing areas into the interceptor should be developed to determine the
flows during wet weather. This can then be used to determine the needed peak wet weather
capacity of the influent sewer, the treatment facilities, and the outfall.
1.7 CONDITION ASSESSMENT
An assessment of the physical condition and remaining useful life of the existing mechanical
equipment was performed as part of this Long Range Facilities Plan (LRFP). The assessment
used a standard asset management approach as established in the International Infrastructure
Management Manual (IIMM), Version 3.0, 2006, written by the Association of Local
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Government Engineering New Zealand, Inc (INGENIUM) and the Institute of Public Works
Engineering of Australia (IPWEA).The results of the assessment are used to estimate the cost to
modify or rehabilitate existing facilities.
The structural components of the facilities were assessed in 2006 and results of that assessment
were also considered as part of this LRFP in order to determine future process and equipment
needs and to develop data for comparing existing facilities/equipment with alternative
technologies.
The general findings of the condition assessment are that while the facilities have been well-
maintained, much of the RWQCP unit processes and equipment are nearing the end of their
useful life and will be considered for replacement or major rehabilitation. Repairing or replacing
the aging facilities will require a significant investment in the next 15 years. A summary of the
major findings and replacement needs are shown in Table 1.2.
The most significant finding affecting the RWQCP is that the existing incinerators, which are
40 years old, are at or near the end of their useful life. Units are difficult to maintain as they age;
the steel structure holding the refractory bricks together is stressed and rusting from within.
Existing repair efforts have focused on patching and rewelding problem areas that have stressed
due to decades of thermal stress. In addition, a seismic analysis of the incinerators and the
incinerator building indicate that an earthquake could render the incinerator process
nonfunctional. A backup raw sludge hauling contract needs to be in place.
1.8 REGULATORY REQUIREMENTS
Through the planning horizon of 2062, the RWQCP will consider many strategies to deal with
emerging regulations. At this level of planning, it is more practical to review groups of similar
contaminants, rather than individual constituents, to determine ways to control their discharge. In
general, the future regulations that have the greatest impact on the RWQCP long range planning
and facility layout are those requiring major process changes, namely increased nutrient removal
standards and incineration regulations that would drive the RWQCP to consider alternative
process technologies.
Throughout the nation and California, attention is being focused on regulation for nutrients
(nitrogen and phosphorus) in our natural water bodies. Excess nutrients to the San Francisco Bay
could harm marine life. Research suggests that the Bay has changed over the last 20 years and
although it is not currently impaired, additional research is needed. There are many sources of
nutrients to the Bay including, stormwater runoff and wastewater treatment plant discharges. If
regulations are implemented requiring wastewater treatment plants to reduce nutrient discharges
to the Bay (most likely nitrogen), the RWQCP would need to install new tanks and equipment.
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Table 1.2 Summary of Needs and Opportunities for Existing Facilities
Driver Process Need/Opportunity Reason
Capacity Interceptor Clean, CCTV, repair.
Study to determine
needed capacity.
Corrosion and leakage.
Appears to have inadequate
capacity.
Outfall Inspect and perform
study to determine
existing and future
capacity needs.
Appears to have inadequate
capacity and is aging.
Replacement Headworks New headworks Near end of useful life.
Solids Process Replace incinerators End of useful life.
Support
Facilities
New Laboratory and
Environmental Services
Building
Existing facilities have
inadequate space.
Administration building is at
end of its useful life. Lab is
outdated.
Recycled
Water Facilities
Need additional
pumping, storage, and
new RW filter and CCT
Limited capacity and aging
infrastructure.
Rehabilitation Primaries Rehabilitate
tanks/channels
Concrete cracks and exposed
rebar.
Secondary Rehabilitate fixed film
reactors, aeration
basins and clarifiers
Structural and media damage
to FFR. Corrosion of concrete
and equipment.
Tertiary Dual media filters and
pumps
Pumps and piping near end of
useful life.
Sludge pumps
and thickeners
WAS, sludge and scum
pumps. Thickener #4
End of useful life. Need new
equipment.
Piping In plant piping End of useful life.
Misc. buildings,
power/electrical
Generators, MCCs,
tunnels, storage
buildings
End of useful life.
Support
Facilities
Remodel Operations
Building and
Maintenance Building
and expand Warehouse
Existing facilities are
inadequate and have
inefficient use of space. Need
additional space for staff and
equipment storage.
Recycled
Water
Pumping, storage Limited capacity and aging
infrastructure
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New regulations affecting incineration facilities were implemented in March 2011 by the U.S.
Environmental Protection Agency (EPA), which require stricter air emissions for incineration.
Per these regulations, if in the future a significant investment is made to repair or upgrade the
City’s existing incinerators, then the strictest air limits are triggered and the current furnaces
would need to be replaced. The final regulations also included stricter air emissions for existing
incineration facilities to match the top 12 percent of air pollution control performance of existing
U.S. multiple hearth furnaces; Palo Alto can currently meet these standards due to the 1999
incinerator rehabilitation of the air pollution control system. The final regulations were appealed
by both Sierra Club and NACWA (National Association of Clean Water Agencies). The Sierra
Club / NACWA litigation is still working through the judicial process in the DC courts; a ruling
on both suits is expected in early 2013. It is unknown at this time what the results of these
appeals and potential litigation will be. In developing the initial rule, EPA indicated the
regulations will be reevaluated every five years. It is considered likely that these regulations will
continue to get more stringent in the future.
Figure 1.6 summarizes the primary regulatory scenarios that will affect the LRFP alternative
development. Ranges of permit cycles during which future regulations are likely to be
implemented are shown for each regulatory scenario. Actual implementation dates for future
regulations are projected and not certain. Table 1.3 summarizes solutions that can be
implemented at the RWQCP to comply with current and future potential regulatory issues.
1.9 SOLIDS TREATMENT ALTERNATIVES
The existing solids process of thickening, dewatering and incineration (with a multiple hearth
furnace) has served the RWQCP for 40 years, but is nearing the end of its useful life. Recent
regulations by the EPA have further restricted the air emissions from incineration processes,
although the plant can currently meet these requirements. The existing incineration process
produces ash that is classified as a hazardous waste, requiring special disposal. In addition, the
public has expressed concern over use of an incineration process. Therefore, the recommendation
of this LRFP is to retire the existing incineration process as soon as a new solids process can be
selected and implemented. As such, solids treatment options that could be implemented at the
RWQCP in the near term have been comprehensively evaluated. A range of potential solids
treatment and disposal options was considered and screened down to the most viable alternatives.
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Table 1.3 Summary of Potential Regulatory Issues and Solutions
Topic Issue Potential Solution
Nutrient Removal Federal and State consideration of
nutrient removal regulations. Data
collection and studies are ongoing to
evaluate eutrophication of the Bay
that may result in effluent limits.
Add processes and/or capacity
to remove nutrients and
maximize source control.
Microconstituents
and
Bioaccumulative
Constituents
There is a trend of increasing
regulation and it is anticipated that
new effluent limits will be added to
permits in the distant future.
Maximize removal through
increased source control and
pollution prevention programs.
Consider advanced oxidation.
Recycled Water State of California goal to increase
water reuse to offset potable use.
Expand use of recycled water.
Biosolids Landfilling of ash and land application
of biosolids is becoming increasingly
restricted and fewer landfills are
accepting biosolids.
Consider diversifying biosolids
management alternatives.
Incineration EPA’s new regulations impose strict
requirements for new and modified
incineration units. Based on this
permitting cycle, these will only
become more stringent.
Begin to diversify incrementally
as opportunities arise and
phase out the use of the current
incinerators.
Air Emissions New sewage sludge incineration (SSI)
standards require RWQCP to apply
for a Title V permit. Air emissions
regulations increasing for standby
engines.
Plan for increasingly stringent
emissions requirements and
need for emissions control
equipment for stationary
combustion facilities/engines.
Greenhouse
Gases (GHG)
POTWs are not directly required to
report GHG emissions but may need
to report general stationary
combustion emissions.
Monitor GHG emissions
regulations and comply.
Implement energy efficiency
and green energy projects.
The viable solids alternatives that were considered in more detail include the following and are
shown in Figures 1.7 to 1.9:
1. Thermal processes: fluidized bed incineration or gasification.
2. Anaerobic Digestion (Wet) with biosolids reuse/disposal.
3. Regional opportunities to haul dewatered solids to San Jose/Santa Clara Water Pollution
Control Plant (SJ/SC WPCP) for digestion or to the Bay Area Biosolids to Energy (BAB2E)
project for treatment/disposal (process undecided but it is likely to be gasification).
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Figure 1.7 Thermal Solids Process
Figure 1.8 Digestion Solids Process
Figure 1.9 Regional Opportunities Solids Process
A summary of the solids alternatives evaluation is shown in Table 1.4. The net present values for
the solids alternatives are shown in Figure 1.10 (detailed breakdown of the net present values are
provided in Table A.1 at the end of this section). A summary of the GHG emission estimates are
shown in Figure 1.11 (further breakdown of GHG emissions sources can be found in Figure A.1
and Table A.2 at the end of this section). The annual energy usage/production comparison is
shown in Figure 1.12 (detailed breakdown of the energy usage/production values are provided in
Table A.3 at the end of this section).v
The solids treatment alternatives are compared in Table 1.4. It is clear that the regional options
represent the lowest capital cost and net present value costs. Of the two regional options,
delivery to the SJ/SC WPCP has the lowest net present value and GHG emissions. However, the
decision to send solids to an off-site treatment facility needs to be a policy decision by the City
and its Partners. Therefore, the recommendation for solids treatment is to continue operating and
maintaining the existing incineration processes and initiate a Solids Facility Plan that will
include discussions with Partner Agencies and potential regional partners (i.e. SJ/SC WPCP and
the potential regional BAB2E facility). The RWQCP staff should also continue to track future
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regulations and potential new technologies, such as gasification, that may be considered more
viable in the future. The RWQCP should also consider participating in regional and local pilots
of processes, such as the gasification pilot planned at SJ/SC WPCP, which would provide
information on how well the process handles undigested solids (which would be required for
design of the process) and what are requirements and costs for operation and maintenance of the
process. If the preference is to keep treatment of the solids at the facility then a preliminary
design should be initiated to evaluate this option in more detail.
Table 1.4 Biosolids Treatment and Disposition Alternatives Comparison(1)
Treatment
Alternative(2)
Annual
O&M Costs
($MM/yr)
Capital
Costs
($MM)
Net Present
Value(3)
($MM)
Total GHG
emissions(4)
, mt CO2e/yr
Site Layout,
acres
Fluidized Bed
Incineration
5.0 130.5 240.3 31,516 0.4
Gasification 4.5 49.8 138.5
(5)20,385 0.7
Anaerobic
Digestion
4.4 89.0 182.0 10,755 1.5
Delivery to SJ/SC
WPCP (regional
digestion)
4.0 39.5 115.4 10,821 0.2
BAB2E (regional
gasification)
6.1 12.8 124.2 20,565 0.2
Notes:
(1) Alternative costs and impacts include treatment and disposition for the year 2045.
(2) Costs presented in 2015 dollars
(3) Present value cost represents the value of the total cash flow occurring over 30 years with
a 5 percent interest.
(4) Greenhouse gas emissions in 2045, including biogenic carbon dioxide emissions.
(5) Based on a similar project it was determined that the capital portion of the O&M fee was
approximately 85 percent. To be consistent with our capital cost estimates, a 30 percent
contingency was applied to the capital cost portion of the annual contract for gasification.
Another solids disposal option that is being considered independent of the LFRP is dry anaerobic
digestion. The City hired consultants Alternative Resources, Inc. (ARI), to complete a dry
anaerobic digestion study for solids generated by the RWQCP and for handling green and food
wastes collected in the City. ARI concluded that a dry anaerobic digester could indeed be
cheaper than the exporting options for green and food wastes, but only if such factors as carbon
adders, state and federal grants and contingency costs for exports are added into the mix. A
public vote in November 2011 passed Measure E, which undedicated ten (10) acres of Byxbee
Park for the exclusive purpose of considering dry digestion processing. City staff and Alternative
Resources, Inc. (ARI) are developing an Action Plan to layout the process and timeline for
considering the facility.
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1.10 LIQUID TREATMENT ALTERNATIVES
The existing liquid treatment processes are performing well and meeting current regulatory
requirements. As part of this LRFP, the needed facilities to meet potential future regulations have
been identified. The most pressing future regulation for liquid treatment is nutrient (nitrogen)
removal as it has the potential to require significant expense to construct new facilities. A range
of potential liquid treatment alternatives to meet low total nitrogen limits was considered and
screened down to the most viable alternatives. The viable liquid alternatives that were considered
in more detail include the following and are shown in Figures 1.13 to 1.15, respectively:
1. Membrane Bioreactors
2. Trickling Filters/Activated Sludge/Denitrification Filters
3. Integrated Fixed Film Activated Sludge (IFAS) Reactors
A summary of the liquid treatment alternatives evaluation is shown in Table 1.5.
Figure 1.13 Membrane Bioreactor Process
Figure 1.14 Trickling Filters/Activated Sludge/Denitrification Filters Process
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Figure 1.15 Integrated Fixed-Film Activated Sludge Process
The liquid treatment alternatives for meeting future regulations for total nitrogen control are
compared in Table.1.5. All of the alternatives for nitrogen reduction have a significant capital
cost and require a large increase in energy consumption and chemical use. It is clear that
continued investment in the existing processes of tricking filters followed by activated sludge
and filtration is appropriate in that denitrification processes (denitrification filters) can be added
on as the lowest capital cost alternative. Therefore, the recommendation for liquid treatment is to
continue operating and maintaining the existing processes while continuing to track future
regulations and potential new technologies that may be considered in the future.
Table 1.5 Liquid Treatment Alternatives Comparison
Treatment Alternative
Capital Cost,
$ millions
Annual O&M
Cost, $
millions
GHG
Emissions,
CO2e mt/yr
Site Layout,
acres
Membrane Bioreactor $135.9 $10.4 3,085 2.5
TF/AS/Denitrification Filter $68.5 $8.3 6,600 1.0
Integrated Fixed Film
Activated Sludge
$114.5 $9.9 3,106 1.0
Notes:
(1) Costs presented in 2015 dollars
(2) O&M costs and GHG emissions shown for liquid treatment alternative operations for year
2035, assuming a requirement of total nitrogen < 8 mg/l.
In addition to considering facilities needed for future total nitrogen removal, facilities needed to
remove emerging contaminants from the effluent and salinity from recycled water were
considered and costs and site needs developed for advanced oxidation with ozone and for reverse
osmosis facilities.
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1.11 RECOMMENDATIONS
In general, the RWQCP is able to treat the existing wastewater flows to meet current effluent
discharge limits and provide recycled water to users. With the exception of the interceptor and
outfall during peak wet weather events, the plant capacity is adequate to meet the anticipated
growth in the service area over the next 50 years. Alternatives have been developed for solids
and liquid treatment facilities in response to changing regulatory requirements for incineration
and for complying with more restrictive effluent discharge limits such as total nitrogen limits and
the potential removal of emerging contaminants.
Findings from treatment evaluations show that while continued investment in the incineration
process is not warranted due to its age, condition, and lack of regulatory flexibility; continued
investment in the existing liquid treatment processes is appropriate in the light of changing
regulatory requirements. Therefore, the major recommendation is to rehabilitate and replace
existing facilities that are nearing the end of their useful life, and not switch the current liquid
treatment processes for the foreseeable future. However, since a significant portion of the plant
was built in 1972 (e.g., the Main Structure), many facilities are aging and are in need of
significant investment in rehabilitation and replacement.
The recommendations for the RWQCP are as follows:
Model Influent Sewer Flows
Determine peak wet weather flow: Work with RWQCP partner agencies to understand
sewer flows. Develop a sewer system estimate of the key components of the wastewater
collection system to determine the peak wet weather flows that will reach the RWQCP.
Knowing peak flows will inform sewer rehabilitation options, inform plant capital
improvement sizing for wet weather flows (note: not pollutant loads), and inform effluent
outfall capacity evaluation. Understanding peak flows will also inform infiltration and
inflow management needs, if necessary, to reduce capital sizing.
Inspect and Clean Influent Sewer:Following the development of the sewer system
flow estimate to determine needed capacity, clean and inspect the 72-inch diameter
interceptor sewer to decide the best option for rehabilitation.
Outfall:Following the development of the collection system flow estimate, the capacity
of the outfall should be reviewed. Additionally the outfall should be inspected to
determine rehabilitation needs for the near future.
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Continue Source Control and Flow Reduction Efforts
Continue to evaluate options for source control and flow reduction measures for cost-
effective options to reduce costs at the RWQCP for treatment of flow and loads.
Continue traditional source control efforts; source control is more cost effective at
removing some pollutants than traditional wastewater treatment technology (e.g., toxic
heavy metals) and will reduce the potential need for more expensive capital facilities.
Source control for emerging contaminants should be considered before advanced
treatment.
Continue support of water conservation efforts as well as infiltration and inflow reduction
efforts, which reduce operating costs, preserve surplus wet-weather capacity, reduce
energy consumption, and reduce the wear and tear on existing capital investments,
thereby extending their life.
Consider alternative source control methods to reduce pollutant loads, as necessary, to
reduce the sizing of potentially necessary capital facilities. Commercial garbage disposals
are already banned in Palo Alto and Mountain View to reduce sanitary sewer overflows.
If the food waste collection system is expanded, the program would include outreach and
education for residents and businesses.
Continue strategic analysis of salinity infiltration to reline and rehabilitate sewers with
highly saline groundwater infiltration.
Consider banning or working with others on regional/state-wide solutions related to
specific household products that pass through the treatment plant and have ecological
impacts on the Bay to reduce the need for large capital improvements to reduce pollutants
better reduced through source control.
Rehabilitate and Replace Critical Infrastructure
Solids Treatment: Continue using the existing Multiple Hearth Furnace for the
immediate future, but initiate a detailed Solids Facility Plan immediately. In light of the
many regulatory and cost uncertainties, this plan should develop a portfolio of
management options.
Preliminary Treatment:Replace the headworks (screenings, pumping and grit).
Primary Treatment:Rehabilitate existing primary clarifiers.
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Secondary/Tertiary Treatment: Continue operating and maintaining existing processes.
Rehabilitate existing fixed film reactors, aeration basins, secondary clarifiers, and dual
media filters.
Recycled Water:Replace recycled water filters and chlorine contact tank.
Support Facilities: Replace the administration building with a new Laboratory and
Environmental Services Building to house a new laboratory and staff office space. This
new building can be onsite or off-site at a neighboring commercial property. The City
should look into the availability of any neighboring properties that can be used for siting
this new building. Remodel the operations building and maintenance building and expand
the maintenance building to include additional warehouse space.
Prepare for Regulatory Action
Nutrient (nitrogen) Removal: RWQCP and Partner agencies to participate in ongoing
studies of the Bay and continue to track regulations and emerging technologies that
would reduce nitrogen with lower energy and chemical requirements. If total nitrogen
removal is required, construct denitrification filters.
Incineration: Move expeditiously on incinerator retirement as new regulations
potentially force more difficult environmental compliance; 5-year regulatory reviews
and/or lawsuits on US EPA regulations may force an accelerated and costly capital
compliance schedule.
Emerging Contaminants: Leave space for ozonation facilities if a higher quality
effluent for emerging contaminants is required.
Respond Strategically
Emerging Technologies: Continue to track emerging technologies that may have
potential for meeting new regulations or for providing an opportunity to save energy and
costs.
Recycled Water: If recycled water demands increase, provide additional storage and
pumping to be able to meet peak-hour demands for future recycled water users. Reserve
space on the site for reverse osmosis should source control measures on sewer infiltration
prove ineffective. Alternatively, an inter-connection with other recycled water systems
may also be more effective than reverse osmosis.
The recommended layout to reserve space for new facilities is shown in Figure 1.16.
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1.12 IMPLEMENTATION PLAN FOR RECOMMENDED PROJECTS
The recommendations of this LRFP result in a significant investment in projects at the RWQCP
over the next 50 years. However, many projects, such as reverse osmosis to remove salts from
recycled water or ozonation to meet emerging contaminants regulations, may not need to be
implemented in the future unless by regulation or City policy. Improvements to the liquid
treatment to remove nitrogen have been identified, but the recommendation is to continue
participating in data collection and investigation of the Bay and not to move forward
immediately with a nitrogen reduction project. In addition, a final decision has not been made on
which solids handling process should be implemented, which has a large impact on the overall
capital improvement project (CIP) program cost estimates, as shown in Table 1.6 and
Figure 1.17. Figure 1.18 shows the overall cash flow for all projects identified in the CIP
program, which is based on the proposed implementation schedule.
Table 1.6 Summary of Recommended Projects and Estimated Costs(1)
Project Category Project Costs in 2015, millions
Solids Handling Projects $13 to 89
Replacement Projects $54
Rehabilitation Projects $78
Support Facilities Project $25
Future Regulatory Requirement Projects $69
Future Recycled Water Projects $77
Total $315 - 392
(1) Cost sharing allocations and cost control measures will be evaluated for each individual
project.
Of the total identified potential project CIP of $315 to $392 million, future projects that may or
may not be implemented amount to $146 million. To represent how the RWQCP intends to
implement the projects, they have been divided into three (3) main categories: Major CIP (larger
capital cost projects that require debt financing), Minor CIP (smaller capital cost projects that
can be done under the existing plant annual CIP budget) and Future Major CIP (may be required
in the future based on some potential regulatory requirement). Figure 1.19 shows the
contribution of each CIP category to the overall CIP program, assuming costs for the anaerobic
digestion option for the solids project (see Table A.4 at the end of this section for the detailed
breakdown of values).
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Figure 1.17 Contributions and Cost of Project Categories to Overall CIP Program
Figure 1.18 Cash Flow for the Major Project Categories of CIP Program
$
$10
$20
$30
$40
$50
FYB 2012 FYB 2022 FYB 2032 FYB 2042 FYB 2052
Recycled Water Facilities
Future Regulatory Requirements
Rehabilitation
Replacement
Support Facilities
Solids Handling
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Figure 1.19 Distribution of Major Project Categories and Costs to Overall CIP Program
1.12.1 Financing
As discussed above, the Minor CIP projects are smaller rehabilitation projects that will be funded
through the existing RWQCP ongoing CIP budget that is currently funded by the partner
agencies’ contributions of $2.6 million/year (2011), adjusted annually to an inflation index. The
Major CIP projects will require funding through other mechanisms such as a low interest State
Revolving Fund (SRF) loans or water revenue bonds. The financing options and the resulting
debt service for the Major CIP projects are discussed in Chapter 9 of the report. Financing for
Future CIP projects is not being considered now because of the tentative nature of the projects. A
separate financing plan will be developed to consider how best to finance the recommended
improvements from this LRFP. Preparation of the financing plan will require coordination and
input by the all the partner agencies.
1.12.2 Partner Agencies Shares
Major capital improvement project costs are shared by all the partner agencies that contribute to
the RWQCP. A preliminary allocation has been made as to each partner’s share of the Major CIP
project costs based on the current capacity allocations, as shown in Table 1.7. However, the final
cost allocation will need to be re-evaluated for each major project as a different cost share
approach may be warranted. For example, the solids project is dependent on solids loading and a
cost allocation will need to be worked out between partner agencies. Additional details on the
cost of financing for each partner is included in Chapter 9 and will be evaluated in more detail in
Major CIP ($M),
$217.5
Minor CIP ($M),
$28.7
Future Major CIP
($M), $146.1
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the Financing Plan. Costs for projects are planning level estimates and do not consider potential
measures for cost control. As each project moves forward, a more detailed analysis will be
performed and cost saving measures will be explored. For example, the first major project will
be the solids project, which will be evaluated in more detail during preparation of the Solids
Facility Plan (to be prepared in 2013) and in subsequent predesign and design efforts. Partner
agencies will be encouraged to participate and provide input into these efforts.
Table 1.7 Summary of Preliminary Partner Cost Allocation for Major CIP Projects(1)
Partner Shares Palo Alto
Mountain
View Los Altos
East Palo
Alto Stanford
Los Altos
Hills
Percent Cost Share Based on Capacity
Sewer 18.24%62.50%15.00%0.00%0.00%4.26%
Wastewater
Treatment
38.16% 37.89% 9.47% 7.64% 5.26% 1.58%
Project Cost Allocation in Millions
Solids Project
(cost shown for
Anaerobic
Digestion)
$33.98 $33.74 $8.43 $6.80 $4.68 $1.41
Laboratory and
Environmental
Services Building
$7.81 $6.19 $1.55 $1.25 $0.86 $0.26
Headworks Facility
(including Grit
Removal System)
$14.83 $14.72 $3.68 $2.97 $2.04 $0.61
Recycled Water
Filters and
Chlorine Contact
Tank
$5.42 $5.38 $1.35 $1.09 $0.75 $0.22
Primary
Sedimentation
Tanks Structure
$2.79 $2.77 $0.69 $0.56 $0.38 $0.12
Fixed Film
Reactors Structure
and Equipment
$7.41 $7.36 $1.84 $1.48 $1.02 $0.31
Joint Interceptor
Sewer $5.62 $19.25 $4.62 $ - $- $1.31
Total $77.85 $89.41 $22.16 $14.15 $9.74 $4.24
(1) Preliminary allocation. Cost sharing allocations and cost control measures will be evaluated
in more detail for each individual project.
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Chapter 2
INTRODUCTION/BACKGROUND
The City of Palo Alto operates the Regional Water Quality Control Plant (RWQCP) for the
benefit of the City and the surrounding communities. The City has provided wastewater
treatment services for 78 years. The RWQCP is located at the end of Embarcadero Road on
Embarcadero Way adjacent to the Palo Alto Airport, Byxbee Park, and the Emily Renzel
Wetlands.
This chapter of the LRFP introduces the history of the RWQCP, its location and the service area.
The environmental and biological setting of the RWQCP is also presented. This chapter also
explains the overall LRFP planning and decision processes as well as the public stakeholder and
technical advisory group processes.
2.1 PLANT HISTORY AND LOCATION
2.1.1 Early History (1894-1934)
Palo Alto was incorporated in 1894. Palo Altans started public sewage improvements in 1898 by
approving $28,000 in bond money to fund construction of the City's first sewer network, which
was completed in 1899. Private cesspools and privies were banned, and the City health officer
had residents connected to the sewer system within a few years. The sewer system served
approximately 3,000 people and discharged raw sewage from a 12-inch diameter outfall pipe into
the Mayfield Slough at the edge of South San Francisco Bay.
While public health in the town of Palo Alto was improved, public heath in the Baylands was
not. During the 1920s the Baylands park and yacht harbor were being planned, but City leaders
feared health contamination to boaters and park enthusiasts. In addition, tide-induced sewage
backflows on City streets prevented population growth in Palo Alto. As a result, the State Board
of Public Health decided to require a primary treatment plant with a new outfall discharging
further from shore into the bay.
2.1.2 Palo Alto Treatment Plant (1934-1972)
The Palo Alto Treatment Plant began operating July 1, 1934, and was the first wastewater
treatment plant in South San Francisco Bay. At a cost of $63,324, the plant could treat 3 million
gallons of wastewater per day (mgd), serving a cannery and approximately 20,500 residents of
Palo Alto and Stanford University. The plant discharged primary effluent 700 feet offshore, and
the raw sludge was digested in an anaerobic digester, placed in sludge drying beds that were
located in place of the current landfill, then used as a soil amendment in parks of Palo Alto.
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In 1946, immediately after World War II, $299,000 was spent to increase treatment capacity to 5
mgd in order to handle the seasonal Sutter Packing Company cannery wastes. To keep up with
the post-war boom in population, the plant increased capacity again to treat up to 10 mgd with
some secondary treatment at a cost of $528,000 in 1957.
Meanwhile, the neighboring City of Mountain View had constructed a primary treatment plant
(in 1951) that was upgraded to provide enhanced primary treatment in 1961. The City of Los
Altos also constructed a primary treatment plant in 1957.
2.1.3 Regional Water Quality Control Plant (1968 - present)
Over the years, residents observed increased signs of pollution and stress on the environment of
South San Francisco Bay. In December 1962, the Palo Alto plant received its first discharge
permit from the California Regional Water Pollution Control Board. In response, the plant built a
new outfall in 1964 to prevent periodic discharges near the (now defunct) Yacht Harbor. A 1966
long range plan recommended adoption of secondary treatment in anticipation of state
regulations requiring disinfection of effluent and higher oxygen levels in receiving waters. The
study also recommended possible consolidation with neighboring communities.
In October 1968, the Cities of Mountain View and Los Altos agreed to retire their treatment
plants and partner with the City of Palo Alto to construct a cost-effective regional secondary
treatment plant – the Regional Water Quality Control Plant (RWQCP). The original Palo Alto
Treatment Plant site was expanded from a 3-acre site to a 25-acre site. The 25-acre site is located
within the Palo Alto Baylands between Highway 101 and San Francisco Bay, as shown in
Figure 2.1. The 1968 agreement is good through July 1, 2035 and states Palo Alto is the owner
and operator of the plant. This agreement, and the agreements with East Palo Alto Sanitary
District, Stanford University, and Los Altos Hills, require all six agencies to proportionately
share in the costs of building and maintaining the facilities.
During the mid-1960s, heavy metals from the electronics industries were causing digester upsets
at the former Palo Alto plant. The digester upsets caused problematic odors. Incineration was not
subject to these shock load upsets and odors. It was deemed that incinerator air pollution control
technologies had evolved sufficiently to remove ash from the exhaust gases (i.e., wet scrubbers).
Incineration had a small footprint on the Baylands. Furthermore, incinerator ash was much more
easily disposed of than anaerobically digested sludge due to the large volume reduction caused
by thermal destruction. Consequently, sludge dewatering followed by sewage sludge incineration
was selected as the biosolids treatment technology.
The RWQCP was designed in 1969 and construction of the RWQCP was completed in October
1972 for a cost of $11 million. Since then the plant has provided complete secondary treatment
of wastewater and incineration of sewage sludge. Disinfected effluent has been discharged to an
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unnamed slough near the Palo Alto Airport, which flows into San Francisco Bay, approximately
1,500 feet distant from the point of discharge.
To further protect the Bay, in October of 1980 the RWQCP was upgraded to an advanced
(tertiary) wastewater treatment facility to improve ammonia removal. This was accomplished
through the addition of two fixed film reactor towers and dual media filters at a cost of
$8.8 million. When there is a need for essential maintenance or to handle wet weather flows
exceeding 40 mgd, provisions were made to bypass the advanced wastewater treatment
processes.
In August 1988, another capacity expansion project was completed to assure that the RWQCP
effluent standards could be met during periods of heavy rainfall. As part of this project, two
round secondary clarifiers were added to the RWQCP. In 2010, construction of the advanced
ultraviolet disinfection system was complete.
2.1.4 Recycled Water Plant (1975 – present)
In 1975, the Santa Clara Valley Water District (SCVWD) constructed an advanced reclamation
facility. Recycled water use at Mountain View’s Shoreline Golf Course (Shoreline Golf Links)
began in 1980 (but was suspended in 2001 due to failure of the recycled water pipeline). In 1986,
SCVWD transferred operations to the RWQCP. Palo Alto continued to operate the facilities for
landscape irrigation in Mountain View. In 1990, recycled water distribution was extended to
Greer Park from the existing line. In 1992, the Water Reclamation Master Plan (WRMP) was
prepared. In 1993, a distribution line was extended to Palo Alto's Municipal Service Center
(MSC) yard and a new pipeline was installed to the Palo Alto Golf Course. Then, in 2008 the
recycled water pump station was upgraded and a distribution system was built to supply new
customers in Mountain View. The goal of the new pump station and pipeline was to deliver
1,503 acre-feet per year (or 489 million gallons per year). As of February 2012, the recycled
water system was delivering 39 percent of this goal.
In 2009, a new pipeline was installed to serve recycled water to Greer Park, Shoreline Park (and
Golf Course) in Mountain View, and other landscape irrigation customers in the North of
Bayshore business area of Mountain View. In 2010, construction of the advanced ultraviolet
disinfection system was complete, which increased potential recycled water treatment capacity
by 6 mgd. An Environmental Impact Report (EIR) is currently being developed for Palo Alto’s
Stanford Research Park area as part of Phase 3 of the recycled water program identified in the
2008 Recycled Water Facility Plan (RWFP) for the Palo Alto RWQCP.
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2.2 PARTNERS AND SERVICE AREA
The RWQCP partner agencies (Partners) include the Cities of Palo Alto, Mountain View
(including some flow from Moffet Field) and Los Altos, the Town of Los Altos Hills, East Palo
Alto Sanitary District (EPASD), and Stanford University. Flow capacity rights for the RWQCP
and 72-inch joint intercepting sewer have been allocated to each of the partner agencies based on
an agreement signed in 1968. In Table 2.1, the flow capacity rights assigned to each partner
agency are shown – average annual flow for the RWQCP and peak wet weather flow for the 72-
inch joint intercepting sewer.
Table 2.1 Average Partner Flow into the RWQCP and 72-inch Joint Intercepting
Sewer Wet Weather Flow Capacity Rights
City
RWQCP Average
Annual Flow Capacity
Rights (mgd)
72-inch Sewer Peak Wet
Weather Flow Capacity
Rights (mgd)
Total
The RWQCP service area including the boundaries of each of the partner agencies is shown in
Figure 2.2.
2.3 ENVIRONMENTAL SETTING AND LAND USES
This section provides a brief description of the environmental setting of and land uses adjacent to
the Palo Alto RWQCP. It is important to consider the setting surrounding the RWQCP as any
improvements recommended by this Plan could result in construction activity at the RWQCP.
Therefore, it is important to consider what are the potential beneficial uses of the area that could
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be impacted by a construction project or on-going operation of the RWQCP. A more detailed discussion
of the environmental setting and land uses, including biology of the Palo Alto Baylands is included in
Appendix A.
2.3.1 Palo Alto Baylands Setting
The Baylands is one of the largest expanses of tidal salt marsh currently remaining in San
Francisco Bay. Historically the Baylands were a small part of a vast contiguous marshland that
stretched from what is now San Mateo to Hayward. This once contiguous habitat has been
fragmented by conversion to salt ponds and development, leaving only “islands” of tidal marsh.
The loss of 85 to 90 percent of the original marshlands around the Bay increases the importance
of the Palo Alto Baylands.
The Palo Alto Baylands provide a very diverse setting for the RWQCP as shown in Figure 2.3.
Embarcadero Road, a four-lane boulevard that passes through a small commercial area and
research office park before paralleling the southern edge of the municipal golf course,
approaches the RWQCP from Highway 101. At Embarcadero Way, the entrance to the golf
course and regional airport are on the left and the RWQCP entrance is to the right. Embarcadero
Road continues along the north side of the RWQCP to an intersection with Harbor Road. Harbor
Road defines the eastern edge of the RWQCP and the airport, and is the extent of current
landward development in the Baylands. Historically, the harbor was across Harbor Road from
the RWQCP, but it was closed in 1986 due to the high cost of dredging. Much of the Baylands
area surrounding the RWQCP is salt marsh in varying degrees of naturalization.
South of the RWQCP is Byxbee Park and former landfill area, the former ITT Property with the
Emily Renzel Marsh, backed up by the Flood Basin of the Natural Unit shown in Figure 2.4. A
lease access is maintained to the ITT Property from East Bayshore Road. Both the ITT Property
and the former landfill area are part of Byxbee Park. In 2010, Palo Alto began accelerating
conversion of phase IIc of the landfill so this part of Byxbee Park could be opened. On July 28,
2011, the landfill closed permanently. Final capping, restoration planting, and trail construction
will take an additional year to complete the conversion from landfill to parkland. The entire area
south of the plant is Byxbee Park with the exception of 10 acres that were undedicated in a
public election process in November of 2011 to be able to consider the siting of an
energy/compost facility on the 10 acres. A new 36-acre section of the Byxbee Park was opened
in July of 2011 for recreation, as well as another 10 acres in December 2011, and by 2013 an
additional 51 acres will be opened (City of Palo Alto, 2011).
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Figure 2.4
PALO ALTO BAYLANDS MANAGEMENT UNITS
LONG RANGE FACILITIES PLAN FOR THE RWQCP
CITY OF PALO ALTO
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2.3.1 Biological and Regulatory Setting
The RWQCP site does not currently support any natural plant communities, though landscaping
with native plant materials and a wildlife corridor on the southern perimeter (near Byxbee Park)
are currently being developed. The salt marshes to the east of the RWQCP (across Harbor Road)
are abundant in wildlife diversity. The Palo Alto Baylands contain some of the most productive
and densely populated marshlands in the Bay Area for the endangered California clapper rails
and the mudflats along the Bay margin provide important feeding and resting habitat for
shorebirds. Stream and riparian habitat benefit anadromous fishes, amphibians, small mammals,
and birds. The marshes may also provide habitat for the endangered salt marsh harvest mouse.
Migratory waterfowl and shorebirds, raptors, and a diversity of songbirds are also common in
these marshes.
A total of 44 special-status plant species are known to occur within the project vicinity. Of these
species, eight species have the potential to occur within the project area and 36 species are not
likely to be on the project site due to lack of habitat, elevation requirements, and/or the site is
geographically removed from the species range.
There are ten special-status wildlife species observed near the project area including: Monarch
butterfly, Pallid bat, Hoary bat, Yuma myotis bat, Burrowing owl, Cooper’s hawk, Northern
harrier, White-tailed kite, Black-crowned night heron, and Great blue heron. Special-status
species and other species of concern are protected under several statutes. The Federal
Endangered Species Act (FESA) requires consideration of whether a project would potentially
have significant impacts on any federally listed species or their critical habitat. Species listed as
threatened or endangered under California Endangered Species Act (CESA) must also be
evaluated for potentially significant impacts.
Trees within the project area are subject to regulation under Title 8 of the City of Palo Alto
Municipal Code, which protects specific trees on public or private property from removal or
disfigurement. The City’s Tree Technical Manual: Standards and Specifications (City of Palo
Alto, 2001) establishes procedures and standards for the purpose of encouraging the preservation
of trees.
2.4 OVERVIEW OF THE LRFP PROCESS
The RWQCP prepared a Long Range Plan in 1966. The RWQCP has not prepared a
comprehensive planning document for its facilities since the time of the 1966 Long Range Plan.
The LRFP is the plant’s first formal planning effort since that plan; the planning horizon is 50
years (through 2062). The RWQCP is facing several key issues: 1) aging infrastructure, 2)
increasing regulatory requirements, and 3) increasing public interest in finding alternatives to the
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existing solids incineration process. For these reasons, the City decided to embark upon a
planning process to look at the long-term needs for the RWQCP facility to continue to provide
reliable treatment and satisfy regulations. To do this, the LRFP must determine the future needs
(flows and loads), assess the existing facilities capacity, condition and deficiencies, estimate
future regulatory scenarios that require additional treatment, develop alternatives for both solids
and liquid treatment processes, develop layouts for whole plant scenarios (leaving room for
potential future facilities), and develop recommendations and a financial plan for
implementation.
The main scope elements for the LRFP and associated chapters of this report are as follows:
Historical and Projected Flows and Loads – Chapter 3
Existing Facilities and Capacity Evaluation – Chapter 4
Existing Plant Assessment – Chapter 5
Regulatory Requirements (Existing and Future) – Chapter 6
Solids Treatment Alternatives Development & Screening – Chapter 7
Liquid Treatment Alternatives Development & Screening – Chapter 8
Recommendations and Implementation Plan – Chapter 9
2.5 DECISION PROCESS AND EVALUATION CRITERIA
The purpose of this section is to describe the systematic process by which the preliminary LRFP
project alternatives (both solids and liquids) were developed, evaluated, and eventually
combined to create viable treatment scenarios for the LRFP. This process consisted of five basic
steps described in this section, and is illustrated in Figure 2.5.
Establish “Long Term Goals”
Establish evaluation criteria
Initial qualitative screening
Detailed alternative evaluation
Prioritization and presentation of recommendation to the public
Each step of the process is described in the following sections. The goals were largely set by
previous efforts and presented at the first public workshop. The LRFP project team created a
preliminary list of minimum project alternative requirements and evaluation criteria during three
meetings and presented these and the overall decision process to stakeholders during the third
public workshop.
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Figure 2.5 Project Alternatives Evaluation and Prioritization Process
2.5.1 “Long Term Goals”
A Long Term Goals (LTG) study was conducted in 2001 with extensive input from the
community and other stakeholders. That effort identified 14 LTGs to guide future RWQCP
planning efforts. The RWQCP staff proposed four additional LTGs and the LRFP project team
proposed two additional LTGs. The complete list of LTGs used in the LRFP process was
presented at the first stakeholder workshop held in December 2010. The LTGs are as follows:
1. Meet Future Capacity Needs
2. Meet or Exceed Regulatory Requirements
3. Minimize or Eliminate Toxins in the Influent (e.g. dioxin)
4. Minimize Energy Consumption and Maximize Energy Life Cycle Efficiency
5. Minimize or Eliminate Potentially Hazardous Chemical Usage
6. Minimize or Eliminate Total Release of Toxins to the Environment
7. Minimize Impact on Ecosystem
8. Minimize Impacts on Community, Including Neighboring Communities
9. Minimize or Justify Financial Impacts on Ratepayer
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10. Involve Stakeholders in the Decision Making Process
11. Immobilize or Beneficially Reuse Persistent Toxins
12. Take Leadership Role in Promoting Beneficial Reuse and Environmental Enhancement
13. Maximize Worker Safety
14. Maximize Recycled Water as a Supplemental Water Source
15. Minimize the Plant’s Life Cycle Greenhouse Gas Emissions
16. Address Climate Change and Sea Level Rise
17. Minimize Recycled Water Salinity
18. Treat Biosolids with Other Organic Waste Streams, Where Practical
19. Provide Reliable, Safe Treatment Now and in Future
20. Maintain and Improve an Efficient Municipal Infrastructure
The development and selection of evaluation criteria used throughout the evaluation process
stems from and is in support of the LTGs.
2.5.2 Evaluation Criteria and Minimum Alternative Requirements
The LRFP project team created a preliminary list of minimum project alternative requirements
and evaluation criteria during three meetings and presented it to stakeholders during the third
public workshop held in May 2011. As shown in Figure 2.5 there is a stepwise process for
evaluating alternatives. The complete list of criteria is provided in Table 2.2.
While the evaluation criteria were being developed and selected, the solids and liquids
alternatives were also developed. The Minimum Alternative Requirements subset of evaluation
criteria were used in the early development of solids and liquids alternatives. These criteria must
be satisfied by any solids and liquids alternative in order to be considered in the next stage of
evaluation.
The list of minimum alternative requirements is as follows:
Meet projected influent flow
Address sea level rise
Meet projected discharge flow/outfall capacity
Meeting existing regulatory requirements
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Table 2.2 Evaluation Criteria Used to Evaluate Alternatives
Evaluation Criteria Units of Measure (Metrics)
2.5.3 Initial Qualitative Screening
An initial qualitative screening step was completed to help narrow down the list of alternatives to
those that are viable. A subset of the evaluation criteria were used to screen (eliminate) any
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solids and liquids alternative that is not viable for the RWQCP operations and site footprint. The
criteria for this step are organized into four categories – treatment, community/neighbors,
environment, and cost. The result of the evaluation is a shorter list of viable solids and liquids
treatment alternatives that can be combined to form viable solids/liquids treatment scenarios for
a more detailed evaluation.
The initial qualitative screening of the solids and liquids treatment alternatives was done using
the matrices shown in Figures 2.6 and 2.7, respectively. The matrices show the criteria organized
into the four categories with the alternatives listed in the left-most column. The LRFP project
team (i.e., RWQCP staff and Carollo) held a meeting to qualitatively screen the solids and
liquids treatment alternatives based on these criteria. The project team reviewed the list of
alternatives and filled in the matrices by providing the reasoning for whether each did or did not
satisfy each screening criteria. Then a summary matrix (example shown in Figure 2.8) was
created showing how well each alternative satisfied the overall categories. The resulting matrices
for the initial comparison of solids and liquids treatment alternatives are provided in Chapters 7
and 8, respectively.
2.5.4 Viable Alternative Evaluation
The viable alternative evaluation is a more detailed evaluation than the initial qualitative
screening since there are additional criteria in each of the four categories (shown in Table 2.2)
and the evaluation is a mix of qualitative and quantitative analyses. The units of measure
(metrics) for each criterion are listed in Table 2.2. It is noted when the evaluation of a unit of
measure is qualitative. The criteria are used to evaluate how well each viable treatment scenario
satisfies the LTGs.
Results of the detailed evaluations were presented at the fourth and fifth stakeholder workshops
for solids and liquids alternatives, respectfully. The slides used in these workshops that presented
the results of the evaluation are included in Appendix B. As some of the initial list of criteria
summarized in Table 2.2 were not actually differentiators for the alternatives considered, not all
the criteria were used in the presentation of the comparison of alternatives.
2.5.1 Prioritization and Presentation to the Public
The result of the alternatives evaluation is a comparison and prioritization of projects and
alternatives based on their overall scores. The prioritization and overall recommendations were
presented to the public for their opinion and feedback at the fifth stakeholder workshop.
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Figure 2.8 Example Resulting Matrix from the Initial Qualitative Screening
Process
2.6 STAKEHOLDER PROCESS
The City established a public workshop process as part of this LRFP to solicit input from the
stakeholders and partner agencies. Five (5) stakeholder workshops were held during the LRFP
development to provide an opportunity for interested parties to provide their input and/or
feedback throughout the LRFP process. The workshop topics are listed below in chronological
order and were publicly advertised on the City’s website a minimum of two weeks prior to the
scheduled meeting.
Introduction and Goals (October 27, 2010)
Biosolids Options (February 9, 2011)
Decision Process and Criteria/Liquid Treatment/ Recycled Water (May 4, 2011)
Biosolids Alternatives (November 16, 2011)
Liquid Treatment Alternatives and Overall Recommendations (March 1, 2012)
Presentation materials used for each workshop and notes taken to capture public input were also
posted on the City’s website and are included in Appendix B. Appendix B also contains
presentation materials used during a Palo Alto City Council Study Session held May 7, 2012 on
the results of this LRFP.
2.7 TECHNICAL ADVISORY GROUP REVIEW
The City arranged for a Technical Advisory Group (TAG) to meet with the LRFP project team to
offer their knowledge and opinions related to new or prospective technologies that might be of
use to the RWQCP. The TAG was comprised of two local professors – Craig Criddle and Perry
Alternative Treatment Environment
Community/
Neighbors Cost
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McCarty of Stanford University. Professors Criddle and McCarty made public presentations to
the City at Stanford University on April 25, 2011. The ideas presented were included in the
considerations for alternatives for liquid and solids treatment, presented in Chapters 7 and 8,
respectively.
2.8 MEETING WITH THE PARTNERS
The City met with the partner agencies on November 10, 2011 to discuss the preliminary findings
of the LRFP and in particular the remaining useful life and capacity of the incinerators. A second
meeting was held on April 23, 2012. This meeting reviewed the overall LFRP recommendations,
the impact to the rates, and cost sharing allocations of the recommended CIP to the partners.
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Chapter 3
HISTORICAL AND PROJECTED FLOWS AND LOADS
The purpose of this chapter is to project the wastewater flows and loads that are expected at the
Palo Alto Regional Water Quality Control Plant (RWQCP). Historical population and
wastewater flows and loads are summarized and used to project future flows and loads through
2062. This chapter also presents projections of recycled water flows based on anticipated
demands. These projections allow the City to identify and plan for new wastewater treatment
plant infrastructure needed in the future.
3.1 BACKGROUND
The Palo Alto RWQCP treats domestic, commercial, and industrial wastewater from the cities of
Mountain View, Palo Alto and Los Altos, the Town of Los Altos Hills, East Palo Alto Sanitary
District and Stanford University (the partners). The service area covers approximately 37,800
acres and includes a residential population of approximately 217,000 people. The community
served by the Plant is composed primarily of low-density residential housing. In addition, there
are several industrial areas and commercial districts within the service area. Figure 3.1 shows the
service area. Note that not all the area within the boundary shown for Stanford University sends
flow to the RWQCP – this is accounted for in the flows and loads data. For the most part, the
service area has been fully developed and major increases in population or industrial flows are
not anticipated at this time. Recent decades have seen a trend towards high-density infill and the
conversion of under-utilized light industrial and commercial properties into residential and
mixed commercial residential. There has also been a shift from manufacturing to office space,
software, and research and development facilities. In the last few years, several larger industrial
facilities have left the service area including a centralized hazardous waste treatment facility,
Romic Environmental Technologies Inc., as well as metal finishing facilities including Sanmina,
Meta Technologies, and Technitron (City of Palo Alto, 2010).
3.2 HISTORICAL POPULATION, FLOWS, AND LOADS
Approximately six years of data from the RWQCP (January 1, 2005 - August 31, 2010) was
analyzed to evaluate historical influent flows and loadings. Average Dry Weather Flow
(ADWF), representing the lowest consecutive three-month average during the months of June
through October, was analyzed to evaluate the per capita ADWF. Per capita flow and load values
are used to project future flows and loads as discussed in Section 3.4. Table 3.1 summarizes the
historical flows and loads.
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Table 3.1 Historical Average Dry Weather Influent Flows, Loads, and Concentrations
(1)
2005 2006 2007 2008 2009 2010 Average
Figures 3.2 and 3.3 illustrate the historical influent flow and loading trends. The historical flow
trend, Figure 3.2, shows that the ADWF has been continuously decreasing over the period 2005
to 2009. This could be due to a reduction and shift in commercial activity in the service area,
stemming from the current economic recession as well as recent conservation efforts by the City
and its Partners. In Figure 3.3, the BOD, TSS, and ammonia loading trends show that the
loadings have steadily increased over the period. This coupled with the reducing flows would
indicate that the water conservation efforts implemented by the City and its Partners have been
successful.
Per capita values of ADWF and loads were calculated using estimated historical populations and
historical influent flow and load values from RWQCP data. For each partner agency population
estimates from the California Department of Finance (DOF) were compared to estimates from
the Association of Bay Area Governments (ABAG) and the U.S. Census (shown in Table 3.2).
The 2010 U.S. Census shows a lower total population (217,331) for the service area than the
DOF (223,616), and is more in line with the ABAG estimates. Therefore, the historical
population estimates used to determine per capita values are based on the 2009 ABAG
projections and the 2010 U.S. Census estimates (interpolating the years in between). The average
of per capita values over the last six years was subsequently used for dry weather projections into
the future. Table 3.3 shows the dry weather flow and load per capita values.
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Figure 3.2 Historical Average Monthly Influent Flows
Figure 3.3 Historical Average Monthly Influent BOD, TSS, and Ammonia Loads
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Table 3.2 Historical Populations Per Partner Agency
2005 2006 2007 2008 2009 2010
California Department of Finance Estimates
TOTAL 215,283 216,783 219,229 222,304 226,244 223,616
Association of Bay Area Governments and U.S. Census
TOTAL 219,900 219,386 218,872 218,359 217,845 217,331
Table 3.3 Historical Average Dry Weather Per Capita Flows and Loads
(1)
2005 2006 2007 2008 2009 2010 Average
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Average Annual, Maximum Month, Maximum Day, and Peak Hour Wet Weather conditions
were also analyzed for the same 2005 to 2010 period. Table 3.4 presents the historical flow
peaking factors for the 2005 to 2010 period. The average ratio of average annual flow (AAF) to
ADWF is 1.06 and is used for projecting the AAF in future years. Similarly, peaking factors for
maximum month flow and loads are used to project future influent flows and loads. Hourly data
from the two wettest years (2006 and 2009) were analyzed for peak hour wet weather flow
(PHWWF). The PHWWF during each event (67.6 and 64.3 mgd, respectively) did not exceed
the rated wet weather design capacity of 80 mgd.
Table 3.4 Historical Flow Peaking Factors
2005 2006 2007 2008 2009 2010 Average
Table 3.5 presents the historical peaking factors for both flow and loads for the ADMMF
condition. Also presented in Table 3.5 is the maximum peaking factor that has occurred since
2005, which is used to project the future maximum month flows and loadings.
Table 3.5 Historical Maximum Month to Average Dry Weather Peaking Factors
2005 2006 2007 2008 2009 2010 Maximum
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3.3 PROJECTED POPULATION
The service area is a mix of residential, institutional, industrial, and commercial uses consisting
of 217,331 residents and approximately 168,620 jobs in 2010. As mentioned previously, new
growth in the service area is anticipated to be primarily infill development. The historic
population served in Los Altos, Mountain View, and Palo Alto, the Town of Los Altos Hills, the
East Palo Alto Sanitary District, and Stanford University was estimated using ABAG data for
2009 and U.S. Census data for 2010. Future population for each City was determined using
ABAG projections.
Table 3.6 presents the current population estimates and projected populations for the RWQCP
service area.
Table 3.6 Historic and Projected Populations Served by the RWQCP
2010(2)2020(3)2040(4)2060(4)2062(4)
(1)
Total Population Served 217,331 246,600 288,600 326,200 329,960
3.4 PROJECTED FLOWS AND LOADS
This section establishes the projections for flow and loads for both dry weather and wet weather
conditions to build-out in 2062.
3.4.1 Projections Based on Per Capita Flows and Loads
Using the historical flow and load data and the population projections presented in Section 3.3,
projections for flows and loads were made into the future through 2062. A moderate rate of
residential and commercial growth is predicted by the partner Cities’ General Plans and based on
ABAG projections. The projected increases in ADWFs are shown in Table 3.7 along with the
projected loads and concentrations for the RWQCP. These projections were calculated by
multiplying ABAG population projections by the historical average per capita flows and loads
and using the historical peaking factors for maximum month and annual average projections.
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Table 3.7 Projected Service Area Flows, Loads, and Concentrations (based on
Per capita Values and ABAG projections)
Current
(2005-2010
Average) 2020 2040 2060 2062
Flows
Loadings(2)
Concentrations(3)
3.4.2 Partner Agency Projections
Recognizing that individual partners may have planned projects that could affect future
wastewater flows (such as planned water conservation measures), each partner agency was
contacted by RWQCP staff to get an update of their wastewater flow projections. Based on the
planned expansion of the campus and the associated drinking water projections for the Stanford
University community, they are estimating they may exceed their 2.11 mgd AAF wastewater
treatment capacity limit as soon as 2022. The wastewater projections provided by Stanford
University through the year 2035 are shown in Table 3.8.
The City of Mountain View provided projections of wastewater flows based on their 2010 Urban
Water Management Plan (UWMP) and their 2010 Sewer System Master Plan (SSMP) through
the year 2035. These projections from Mountain View included anticipated flow reductions
resulting from planned conservation measures and are assumed to also reflect changes in their
service area affecting water demands and wastewater flows.
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Table 3.8 Projected Partner Agency Wastewater Flows in Million Gallons per Day
Current
(2010) 2015 2020 2025 2030 2035
Stanford University(2)
Mountain View(3)
Palo Alto(4)
East Palo Alto Sanitary District(5)
Los Altos/Los Altos Hills
(6)
The City of Palo Alto Utilities (CPAU) department provided alternate influent wastewater flow
projections through 2030 based on their 2011 UWMP as shown in Table 3.8. These flow
projections reflect planned conservation efforts and code changes for plumbing associated with
new construction.
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While East Palo Alto Sanitary District’s (EPASD) Sewer Master Plan was unavailable during the
analysis, the 2010 UWMP provided wastewater flows for 2010 through 2035 as shown in Table
3.8. The City of Los Altos and Town of Los Altos Hills provided wastewater flows in their 2005
SSMP for 2002 and build-out in 2020, which are shown in Table 3.8.
Based on these flow projections provided by the partner agencies and CPAU, an alternative flow
projection was developed for the RWQCP. It is assumed that the lower flow projections are due
to conservation and the ADWF loadings will remain the same. Therefore, the concentrations are
revised. Table 3.9 shows the alternate flow and loads projection for the RWQCP. Figure 3.4
shows both flow projections and represents the range of future flow scenarios that the RWQCP
will need to plan for as part of the LRFP.
Table 3.9 Alternate Projections of Service Area Flows, Loads, and Concentrations
(based on Partner projections, including planned conservation
measures)
Current
(2005-2010
Average) 2020 2040 2060 2062
Flows
Loadings(3)
Concentrations(4)
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Figure 3.4 Existing and Projected Average Dry Weather Flow into RWQCP
3.4.3 Wet Weather Flow Projections
Wet weather flows are influenced by precipitation in the form of infiltration and inflow (I/I). The
RWQCP has experienced several extreme wet weather events in the past 15 years. One extreme
flooding event in February 1998 led to permitted bypasses and upstream flooding. The following
sections describe the influences on I/I, which directly affect the RWQCP wet weather flows.
3.4.3.1 Collection System
The RWQCP service area consists of six partner agencies. Wet weather flows to the RWQCP
can be substantial, and they result from an increase in I/I occurring in the collection systems of
the service area during storm events. The City commissioned a few studies starting in the 1980s
to assess the capacity and condition of the collection system in an attempt to identify existing and
future deficiencies in the collection system and to develop improvement projects to alleviate
these deficiencies. These studies included:
1. Infiltration/Inflow (I/I) Study, conducted in phases from 1980 to 1987.
2. City of Palo Alto Wastewater Collection System Master Plan (CSMP) in 1988.
3. City of Palo Alto Wastewater Collection System Master Plan (CSMP) Update in 2004.
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Two additional studies not commissioned by the City were performed and considered as part of
this LRFP:
1. City of Los Altos Sewer System Master Plan (SSMP) in 2005.
2. City of Mountain View Sewer System Master Plan (SSMP) in 2010.
The I/I Study identified that over 40 percent of the City’s annual flow came from extraneous
groundwater and storm infiltration through direct surface drainage or damaged collection
pipelines. As a result, an extensive sewer rehabilitation program was recommended.
The 1988 master plan identified and recommended a number of capacity improvements totaling
$32 million in 1988 dollars. The City embarked on implementing these improvements and
completed about 40 percent of the recommended projects before commissioning the 2004 master
plan update.
A new hydraulic model of the collection system was developed for the 2004 CSMP Update. The
model used a design storm based on a 5-year event with a 6-hour duration, which is consistent
with prior City assumptions. The 5-year storm event was based on intensity-duration-frequency
statistics for a 6-hour nested storm event in Palo Alto. The CSMP also developed 10-year and
20-year design storm events. As a result of the sewer rehabilitation program undertaken by the
City prior to the 2004 CSMP, the 5-year storm event was used to identify capacity deficiencies,
while the 20-year storm event was used to size proposed relief facilities.
Based on recommendations from the 2004 CSMP, $21 million dollars (2003 dollars) of
improvements originally recommended in the 1988 CSMP were eliminated. However, the City is
continuing their sewer rehabilitation program to replace older collection system pipe to continue
to reduce I/I, as well as saltwater intrusion into the wastewater collection system.
The City of Los Altos’ 2005 SSMP was based on assessments of the hydraulics, physical
condition, and maintenance of the collection system and provided recommendations for
improvements to provide adequate hydraulic capacity and improve the reliability of the
collection system. A capital improvement program (CIP) was developed to mitigate hydraulic
and structural deficiencies over the next 20 years. The City’s collection system required a
number of improvements including modifications to pump stations, correcting structural
problems, remediating sulfide-related corrosion, and relieving hydraulic restrictions. The total
cost for all projects was approximately $47,439,000 in 2005 dollars. The SSMP is currently
being updated and is going to the City Council for adoption in the summer of 2012.
The City of Mountain View’s 2010 SSMP updates the 1991 SSMP with revised growth
assumptions, design criteria, and hydraulic modeling data. The SSMP provided
recommendations for hydraulic improvements in order to maintain service for existing and future
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development. It also provided infrastructure replacement recommendations to establish
monitoring and replacement priorities. The result of the SSMP was an approximately
$19,900,000 CIP to serve as a roadmap through 2030 for the City to invest in the sewer system
for recommended pipe hydraulic improvements, pipe replacements, and lift station repairs.
East Palo Alto Sanitary District’s Sewer Master Plan was unavailable during the analysis.
However, EPASD is finalizing an I&I Study and their Sewer Master Plan will be updated in late
2012.
3.4.3.2 Climate Change – Precipitation Patterns
The purpose of this section is to summarize the potential effects of future climate change,
specifically changes in precipitation patterns, on peak wet weather flows at the RWQCP. Climate
change has been predicted to result in increased extreme precipitation events in some areas,
which could result in increased I/I to the RWQCP.
Current Trends in Annual Precipitation and “Extreme” Events
The key climate variable that could impact wet weather flows is precipitation. The long-term
average precipitation in Palo Alto is 15.3 inches per year, while the U.S. average is 37 inches.
From 1910 to 1996 precipitation increased by about 10 percent across the contiguous United
States. Over half of this increase in precipitation is due to an increase in the extreme daily (i.e.,
24-hour) precipitation events – that is, daily precipitation events exceeding two inches (Karl and
Knight, 1998).
The Environment California Research and Policy Center (ECRPC) published a study in
December 2007 evaluating trends in the frequency of extreme precipitation events across the
contiguous U.S. The analysis considered daily precipitation records from 1948 through 2006 for
more than 3,000 weather stations in 48 states. Patterns in the timing of heavy precipitation
relative to the local climate at each weather station were examined (Madsen and Figdor, 2007).
The study focused on extreme daily precipitation totals with an average recurrence interval of
1 year or more. Records show a 26 percent average increase in frequency of these events across
California since 1948.
Detection of statistically significant trends becomes more difficult at the metropolitan level.
While the study did not show the results for areas in northern California, a review of extreme
precipitation for areas in southern California was provided for Bakersfield, Los Angeles, Santa
Barbara, and San Diego. Extreme precipitation events there increased in frequency by 51 to
93 percent since 1948 (Madsen and Figdor, 2007).
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Future Projections and Recommendations
While projected temperature changes due to climate change are broadly consistent across most
climate modeling efforts, projected changes in total annual precipitation across the U.S. have
varied widely across models and emissions scenarios (Kiparsky and Gleick, 2003; Madsen and
Figdor, 2007). In addition, as models are run at smaller scales (e.g., regional or metropolitan
level) the accuracy decreases.
Most model results for projected changes in the region are highly uncertain, but have shown a
small range of changes for Northern California (Dettinger, 2005). Therefore, it is recommended
that long-term planning be based on current trends of total annual precipitation.
Although projected changes in total annual precipitation are mostly small and uncertain, the
intensity of precipitation is likely to increase around the world, with the most significant
increases occurring in the middle to high latitudes (Meehl et al, 2005). Kharin and Zwiers show
the projected frequency of daily precipitation events considered to be extreme (i.e., exceeding
2 inches) will occur twice as often by the period of 2046 to 2065 and three times as often by the
end of the 21st century relative to those that occurred during the period of 1981 to 2000. This
means that 24-hour precipitation events with current return periods of 1, 5, 10, 20, 50, and 100
years will occur 2 or more times as often by the year 2100 due to climate change (Kharin and
Zwiers, 2005; Kharin et al, 2007). It is recommended that long-term planning include updates to
intensity-duration-frequency curves to track the recent changes in extreme events and the
potential impacts to the design and operation of the RWQCP.
In summary, it is important to consider the potential impact global climate change may have on
precipitation events (i.e., total annual average and extreme events) in order to anticipate
necessary modifications to RWQCP design and operations management for flood prevention.
Prudent planning for the RWQCP should consider the projected changes in extreme events due
to global climate change, which includes considering longer duration and increased frequencies
of precipitation events.
3.4.3.3 Projection of Wet Weather Flows
As a result of the repair and rehabilitation work that has been done on the collection system to
reduce I/I to the RWQCP, and the ongoing sewer rehabilitation programs, peak wet weather
events are not projected to increase beyond past wet weather events within the planning period of
the LRFP. The collection/sewer system master plans developed for partner agencies were
reviewed to estimate the total peak wet weather influent flows received by the RWQCP.
Projected peak wet weather flows estimated for each partner agency were not based on the same
storm events as shown in Table 3.10.
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Table 3.10 Projected Peak Wet Weather Flows in Million Gallons per Day
(1)
Baseline 2010 2020 2030
Palo Alto (includes Stanford University and Los Altos Hills)
Mountain View
Los Altos/Los Altos Hills
Previous design criteria indicate that the RWQCP was designed for a PHWWF of 80 mgd. The
total of the worst-case projected flows from the collection system master plans (from Table 3.10)
for each agency does not exceed 80 mgd. While recent peak hour flows have not reached
80 mgd, there was an event in February 1998 where plant influent reached 80 mgd. This was
estimated to be a storm event with a return period ranging between 50 to 75 years. Although this
was an extreme event that resulted in street flooding which aggravated inflow to the collection
system, for the purposes of this LRFP we will use a PHWWF projection of 80 mgd.
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A better understanding is needed of the peak flow potential for the RWQCP service area. The
existing collection system models do not interact with each other or reflect the timing of flows
that would occur in the system. It is recommended that a comprehensive collection system model
for the entire service area be developed and calibrated with flow data collected in the system
during wet weather events. This information would also be helpful to identify areas in the system
with high I/I, which may need to be rehabilitated.
3.5 UPSTREAM INTERVENTION
This section looks at the impacts that any significant future upstream diversion programs would
have on the future flows and loads to the RWQCP.
3.5.1 Diversions
Discussions with City staff and the partners indicated that there are two possible areas for
diversion of future inflows to the RWQCP. These are:
1. Implementation of Graywater Systems. Although the use of legal graywater systems is
encouraged and implemented in other cities, for the purposes of this LRFP, we are not
assuming a significant pollutant or flow reduction at the plant from graywater systems.
Palo Alto and Mountain View currently have five permitted graywater systems each. Gray
water systems are welcomed in the service area; however, they have an insignificant impact
on the long range flow projections.
2.Infiltration and Inflow Reduction. For the Palo Alto sewer collection system, no further
reduction in I/I is being assumed. Based on a review of the 2004 CSMP, sewer
rehabilitation programs have been implemented and resulted in a significant reduction in
I/I. We will assume that I/I levels will remain unchanged for the purposes of the LRFP and
in the absence of any developed modeling of the sewer system for design level storms (e.g.,
10-year storm). Efforts to implement best management practices (BMPs) for stormwater
management may also lead to reduced I&I in the future.
Therefore, no significant reductions due to diversions are being incorporated into the LRFP.
3.5.2 Distributed Treatment
Influent flows and some organic loading to the RWQCP could be reduced in the future as a result
of upstream treatment and recycling. Recycled water can be produced at upstream satellite plants
(i.e. scalping plants). These satellite plants would provide liquid treatment but be required to
send solids back to the sewer to be treated at the RWQCP. The recycled water would be
consumed by users close to the satellite plant and would result in a reduction on the hydraulic
load at the RWQCP when in use (primarily summertime), while the solids loading would remain
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unchanged. Operation of a satellite plant for recycled water use requires state certified operators
and an NPDES permit. Although some of the Stanford University professors have expressed an
interest in satellite (distributed) treatment and the Stanford campus has the greatest potential
based on demand for landscape irrigation, East Palo Alto Sanitary District is the only other
partner agency considering implementation of a satellite treatment system as stated in their 2010
Urban Water Management Plan. However implementation of a satellite facility for EPASD is
only estimated to offset approximately 100,000 gallons wastewater per day. Therefore, no
additional diversions are incorporated into the LRFP flow projections.
3.6 RECYCLED WATER DEMAND SCENARIOS
This section identifies the historical recycled water demands and projections for the future
recycled water demands. Historical recycled water demands are based on data for the period
January 2005 through August 2010.
3.6.1 Background
The City of Palo Alto has been producing and supplying recycled water since the 1980s. Phase 1
of the RWQCP’s recycled water program, in operation since the 1980s, supplies recycled water
to the Palo Alto Golf Course, Greer Park, the Emily Renzel Marsh, and the RWQCP. Mountain
View began using recycled water at the City golf course in 1980. Phase 2 of the City’s recycled
water program has been in operation since the spring of 2009 and supplies recycled water to the
Mountain View Recycled Water Project. The next phase of the recycled water program to be
implemented as identified in the Recycled Water Facilities Plan (RWFP) for the RWQCP in
2008 (RMC, 2008) is Phase 3 or the Palo Alto Recycled Water Project. An environmental impact
report (EIR) is being developed for the Phase 3 project in 2012.
All the phases of the recycled water program were first identified in the Water Reclamation
Master Plan (WRMP) for the RWQCP in 1992 (Brown and Caldwell, 1992). In 2006, the City of
Palo Alto completed a Recycled Water Market Survey Report (Market Survey) (RMC, 2006).
The 2006 Market Survey was a preliminary effort to determine the revised potential locations of
recycled water use within the City. This revised list of potential recycled water users was then
used in the RWFP as the basis for the recommended Phase 3 project. The proposed Phase 4
includes serving Stanford University and Medical Center Area and has not been fully developed
yet. According the Stanford University the WRMP overestimates the potential demands for
recycled water for Stanford.
3.6.2 Historical Demands
Based on the data from the plant for the period January 2005 to August 2010, Table 3.11 shows
the historical recycled water supply over the period.
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Table 3.11 Historical Recycled Water Supply Flows
2005 2006 2007 2008 2009
(1)(2)2010 Average
Note that for Phase 2, although the main pipeline has been installed, not all the connections to
users have been completed. As of February 29, 2012, annual recycled water use is 39 percent of
the estimated 489 million gallons per year of projected use. Additional connections continue to
be made over time to bring on identified users.
3.6.3 Projected Demands
The phasing for the recycled water program was initially identified in the 1992 WRMP and later
refined in the 2008 RWFP. The implementation of recycled water is greatly affected by political
processes. While there is commitment to continue use of recycled water, there is no adopted
schedule for its expansion, therefore, for the purposes of this 50-year planning horizon for the
LRFP, the recycled water demand was categorized into near, intermediate and long-term
demands as shown in Table 3.12.
Table 3.12 Recycled Water Demands in the Near, Intermediate and Long Term(1)
Annual Average
Flow Rate (mgd)
Peak Month Flow
Rate (mgd)
Peak Hour Flow
Rate (mgd)
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The near term demand includes the existing demand through Phase 3. The demand estimates are
derived from the 2008 RWFP. The intermediate demand represents the recommended project
from the 1992 WRMP. This includes Phase 4 and the connection to Moffett Field, both of which
were identified in the 2008 RWFP. The long-term demand is a build-out from the recommended
project and represents the target users from the 1992 WRMP, which is a sub-set of the total
identified users, but represents the fraction of potential users that are more likely to be
implemented due to size/demand and location.
These projected recycled water demands will be used for identifying and sizing recycled water
treatment facilities needed at the RWQCP and for identifying storage needs both on and offsite.
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Chapter 4
EXISTING FACILITIES AND CAPACITY EVALUATION
4.1 HISTORY OF THE RWQCP FACILITIES
The Regional Water Quality Control Plant (RWQCP) was originally constructed in 1934 with a
hydraulic capacity of 3 million gallons per day (mgd) and consisted of primary clarification,
digestion, and sludge drying beds. In 1948, the RWQCP was expanded to handle the seasonal
cannery waste load and a total hydraulic capacity of 5 mgd. In 1956, the RWQCP was expanded
to handle a hydraulic capacity of 10 mgd. In 1964, the new effluent outfall (54-inch diameter)
pipeline was added and discharged to an unnamed slough located directly to the north of the
airport runway. In 1972, the RWQCP was upgraded to a secondary treatment facility and
expanded to accept wastewater from the cities of Mountain View and Los Altos. This expansion
increased the average dry weather flow capacity to 35 mgd and the peak hour wet weather
capacity to 80 mgd.
In 1981, construction was completed for an upgrade to provide nitrification and tertiary
treatment. In case there is a need for essential maintenance or to handle wet weather flows
exceeding 40 mgd, provisions were made so the nitrification and tertiary treatment processes can
be bypassed. The tertiary facilities were designed to treat an average dry weather flow of
30.6 mgd; therefore, the RWQCP was derated from 35 mgd to 30.6 mgd. In 1988, a capacity
expansion project increased the overall permitted average dry weather flow capacity to 39 mgd.
4.2 EXISTING FACILITIES DESCRIPTION
The existing treatment processes at the RWQCP consist of headworks, primary, two-stage secondary,
tertiary, disinfection, and recycled water treatment, as well as solids treatment and handling.
A process flow diagram showing the path of the liquid and solids streams through the RWQCP is
shown in Figure 4.1. Figure 4.2 shows an aerial view of the existing facilities, the location of its
boundaries as well as existing headworks, primary, secondary and tertiary treatment,
disinfection, recycled water, and biosolids treatment facilities. The details of each unit process
are summarized in Table 4.1 and each is briefly described in the following sections of this
chapter.
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Table 4.1 Summary of Existing Facilities
Item Value
Influent Box and Septage
Headworks
Old Pumping Plant
New Pumping Plant
Bar Screens
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Table 4.1 Summary of Existing Facilities
Item Value
Screw Screenings Press
Grit Removal
Primary Treatment
Primary Sedimentation Tanks (PST)
Primary Sludge Pumps
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Table 4.1 Summary of Existing Facilities
Item Value
Secondary Treatment
Intermediate Lift Station (bypass)
Fixed Film Reactors
Aeration Basins 1-4
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Table 4.1 Summary of Existing Facilities
Item Value
Secondary Clarifiers 1-4 (Square)
Secondary Clarifiers 5-6 (Round)
RAS Pumps
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Table 4.1 Summary of Existing Facilities
Item Value
WAS Pumps
Tertiary
Dual Media Filters (DMF)
DMF Backwash Supply Pumps
DMF Surface Wash Pumps
DMF Backwash Waste Pumps
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Table 4.1 Summary of Existing Facilities
Item Value
DMF Lift Pumps
Recycled Water Filters
Recycled Water Filtration Backwash Supply
Pump
Disinfection
Ultraviolet (UV) Channels
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Table 4.1 Summary of Existing Facilities
Item Value
Recycled Water
Recycled Water Chlorine Contact Tank
Abandoned Chlorine Contact Tank
Palo Alto Golf Course Recycled Water Pump
Main Recycled Water Pumps
Solids Handling
Sludge Gravity Thickeners
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Table 4.1 Summary of Existing Facilities
Item Value
Sludge Transfer Pumps
Scum Transfer Pumps
Sludge Blend Tank
Belt Filter Presses (BFP)
BFP Sludge Feed Pumps
BFP Wash Pumps
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Table 4.1 Summary of Existing Facilities
Item Value
Multiple Hearth Furnaces
Combustion Air Fans
Induced Draft Fans
Air Pollution Control
Wet Scrubbers
Afterburner Combustion Air Fans
4.2.1 Interceptor
The 72-inch joint intercepting sewer (built in 1972) conveys wastewater from the cities of
Mountain View, Los Altos, Los Altos Hills, and the southern portion of Palo Alto to the
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RWQCP. As shown in Figure 4.3, the reinforced concrete pipe is approximately 8,600 linear feet
and runs from the intersection of Casey Avenue and San Antonio Road in Palo Alto, below the
flood control basin, and to the RWQCP.
The capacity of the trunk line is reported to be 80 mgd, although the interceptor was specifically
excluded from the capacity evaluation in the most recent collection system master plan
completed in 2004. As recently as January 2, 2006 at 12:45 p.m., and January 20, 2010 at
10:51 a.m., peak hourly influent flows to the RWQCP reached 67.9 mgd and 64.3 mgd
(respectively) with no overflows; typical flows at this time are 30 to 35 mgd.
The 72-inch diameter joint interceptor sewer experienced overflow conditions during an extreme
wet weather event lasting from February 1, 1998 through February 4, 1998. On February 2,
1998, at 7:00 am crews responded to sewer system overflows on Tallsman Drive, Louis Road,
Ross Road, and Corina Way. At noon, manholes at Center Drive and Martin Avenue and Center
Avenue and Telvis Place were reported overflowing. By 10:00 p.m., flows at the RWQCP
exceeded 70 mgd. In the early hours of February 3, 1998, water overflowed the banks of San
Francisquito Creek. Subsequent street flooding and submerged manholes led to additional sewer
flows and the RWQCP reached its maximum capacity of 80 mgd at 3:00 a.m. At this time, the
trunklines to the plant were throttled down to plant capacity to store the flows. The plant
continued to operate at 80 mgd for the remainder of the day. By February 4, 1998, at 9 a.m., no
manholes were overflowing and the RWQCP was operating at 65-70 mgd.
4.2.2 Influent Junction Box and Septage
There are two trunk sewers that direct raw influent wastewater into the influent junction box
from the City of Palo Alto and partner agencies. The 42-inch diameter trunk sewer carries the
combined flow from the East Palo Alto Sanitary District, the City of Palo Alto, and Stanford
University. The 72-inch diameter trunk sewer carries the combined flow from the City of Palo
Alto, Mountain View, Los Altos, Stanford University, and Los Altos Hills. Stanford and EPASD
flows enter into the very end of the 72-inch trunkline near the RWQCP. Many plant sewers
discharge into the lower reaches of the 72-inch trunkline. In addition, a 15-inch diameter clay
pipe takes liquid waste discharged from septic haulers into the influent junction box. The box has
two hydraulically operated sluice gates. One gate passes the wastewater to the old pumping plant
(OPP) 42-inch diameter pipe (built in 1956) and the other gate passes the wastewater to the new
pumping plant (NPP) 72-inch diameter pipe (built in 1972). Both gates are intended to be open
with both pumping plants operating at the same liquid level. During historic peak storm events
when influent flows reach 80 mgd, these gates have been partially closed to limit plant influent
flow, while surcharging the influent sewers. The wastewater level in the sewers is usually 15 to
20 feet below ground level. The raw wastewater influent is then screened and pumped 15 to
16 feet above ground level to treatment units.
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4.2.3 Headworks
The bar screens, OPP, NPP, and grit removal system are collectively referred to as the
“Headworks.”
4.2.3.1
Screening raw wastewater is necessary to reduce the size and volume of the solids, rags, and
debris that may interfere with operation of downstream equipment. The RWQCP returns recycle
stream flow (i.e., belt filter press filtrate, incinerator scrubber drain water, and scum concentrator
decant) to the raw influent wastewater downstream of the influent junction box and upstream of
the three raked bar screens. The bar screens and screenings press were designed for 30 mgd each
and were installed in 1993 to replace the three barminutors that had been in place since 1972.
The bar screens were retrofitted in 1995 from 1/2-inch to 3/4-inch spacing to decrease excessive
organics buildup on the screens. The screenings are raked off the bar screens for discharge into
the screw screenings press for dewatering. The dewatered screenings are picked up twice weekly
by the city’s waste hauler (currently Green Waste) and disposed of at a landfill.
Bar Screens
4.2.3.2
After screening, the wastewater is lifted through a 60-inch diameter force main to the primary
sedimentation tank influent channel via the OPP and NPP lift pumps. The original 1934 pumping
plant (now the “ops shop”) was retired in 1956 with the construction of the OPP. The “ops shop”
now serves as the motor control center (MCC) for the OPP. The OPP has three lift pumps
(Nos 7, 8, and 9). In 1972, the NPP was constructed with a motor room and four lift pumps
(Nos. 1, 3, 4, and 6) with space reserved for two additional lift pumps. During the 1988 capacity
expansion, two additional lift pumps (Nos. 2 and 5) were installed. The NPP pumps are operated
with a suction level setpoint, which causes a continuous backwater in the 72-inch joint
interceptor trunk line to prevent cavitation of the pumps. The NPP and OPP flow meters are in
the Meter Pit just before the tie-in to the 60-inch diameter force main.
Old and New Pumping Plant
During high flow (or backup) situations, some of the raw influent is directed through a channel
monster in the OPP to grind rags and debris. The ground solids flow with the wastewater and are
processed downstream.
4.2.3.3
Grit is removed from the wastewater in the primary sedimentation tank influent channel. Grit
consists of sand, gravel, cinders, and/or other heavy materials that settle. The grit removal system
was installed in 1988 to protect rotating equipment (e.g., pumps) from abrasion, excessive wear,
and to avoid heavy build-up of grit in downstream processes.
Grit Removal
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The grit enters a cyclone, which sends dewatered grit to the inclined screw grit classifier. The
grit classifier discharges the washed grit into a bin inside the grit building. The bin is emptied
into a waste container and hauled to a landfill twice weekly. The excess water from the cyclone
flows into the sewer of the grit building eventually entering the 72-inch interceptor trunk line.
The grit cyclone and classifier system was replaced in 2005.
4.2.4 Primary Treatment
The purpose of primary treatment is to remove most of the settleable and floatable solids by
gravity separation. Removal of these solids reduces the organic loading on the secondary
treatment process. This section describes the existing primary treatment process at the RWQCP,
which consists of the influent channel, primary sedimentation tanks (PST), sludge removal, scum
removal, effluent channel, and a bypass gate.
Primary treatment at the RWQCP begins as the 60-inch diameter force main discharges screened
wastewater into the 7-foot wide influent channel located at the head of the sedimentation tanks.
This channel also collects the effluent from the adjacent four sludge thickeners. Grit is removed
from the primary influent channel (see Section 4.2.3.3). Dual media filter (DMF) backwash as
well as secondary effluent channel scum is discharged into the southerly end of the primary
influent channel prior to entering the PSTs.
The wastewater flows into four PSTs, each 220 feet long by 41 feet wide by 14 feet deep, and
covered with a concrete slab. The purpose of these tanks is to remove the majority of the
settleable solids. Settled solids are removed from the floor by a collector system, which includes
longitudinal and cross collector mechanisms. The solids, or sludge, are pushed into a sludge
sump and pumped to three (of the original four) sludge thickeners. Floating solids, or scum, are
moved to the end of the sedimentation tank by the longitudinal sludge removal mechanism and
skimmer. The scum is collected and pumped to the scum concentrator and fed directly into the
incinerators.
Due to problems with corrosion, maintenance, operations, and safety, in 1985 plastic assemblies
replaced the original 1972 cast iron chain and redwood flights. The steel shafts and stub shafts
were replaced in 1998 along with new wear strips.
Downstream of the sludge and scum removal mechanisms, the wastewater flows into concrete
collector troughs, which discharge into an 8-foot wide effluent channel spanning the end of each
PST. A motor-operated 72-inch sluice gate is located at the upstream end of the primary effluent
channel providing an emergency bypass of secondary and tertiary treatment processes. A 72-inch
diameter pipeline carries the bypass flow to a junction box upstream of the ultraviolet (UV)
disinfection facility. Bypass of primary effluent is not allowed by the RWQCP NPDES permit.
There is no known use of the emergency bypass in the plant’s history. The primary effluent
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channel also has a 36-inch butterfly valve between PST Nos. 2 and 3. The valve provides an
alternate return activated sludge (RAS) discharge point. Normally, this valve is closed and the
RAS discharges into the RAS mixing box.
The primary clarifiers are providing adequate removal of BOD and TSS under the current flows
and loadings.
4.2.5 Secondary Treatment
The secondary treatment system uses two stages to remove organic material (i.e., BOD) – fixed
film reactors (FFR) followed by aeration basins and secondary clarifiers (activated sludge
process). The FFR (a.k.a., “roughing towers”) is a "fixed growth" biological process, compared
to the aeration basins and secondary clarifiers, which are "suspended growth" biological process.
The RWQCP’s discharge permit does not currently require nitrogen or phosphorous removal.
4.2.5.1
Primary effluent flows through a diversion box to each set of centrifugal feed pumps (3 each)
below the FFRs. The FFRs are trickling filter unit processes specially designed to operate at high
hydraulic loading rates. The feed pumps lift the primary effluent to the rotary distributor in each
of the two reactors (North and South Towers). The rotary distributors dispense the wastewater
over plastic media in the towers where a gelatinous coating of biological growth reduces the
carbonaceous biochemical oxygen demand (CBOD) in the primary effluent. This reduction of
CBOD makes nitrification possible in the activated sludge process. An underdrain collects the
treated wastewater below the media, where there is also ventilation to provide an aerobic
environment.
Fixed Film Reactors
An aerobic environment must be maintained in the reactor for a healthy bacterial film to grow on
the plastic media and reduce odors. The towers are ventilated either by natural draft or forced
draft. In the forced draft mode, the exhaust air is directed through biofilters of sand to remove
any potential odors. In case of emergency, the influent to the FFR can be chlorinated before it
flows to the tower lift pumps.
A continuous flow of water over the towers is needed to keep the biological growth healthy. A
manual or automatically operated recirculation valve can be opened to return tower effluent to
the towers for additional passes of treatment; the valve is normally set in a fixed position at the
SCADA tower screen and setup for single pass treatment. Tower effluent is directed to the
activated sludge facilities for further treatment.
When influent flows exceed the capacity of the towers, the excess flow bypasses the FFRs via
the Intermediate Pump Station (IPS) and flows directly into the aeration basins influent channel.
According to staff, when flow exceeds 60 mgd, the PSTs can start to flood. Flooding of PSTs
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causes undesirable carryover of floating scum and plastics to the secondary process, but does not
directly limit hydraulic throughput. The construction of the aeration basin effluent boxes in 1988
required the water level in the basins be raised in order to provide sufficient head to control the
flow to the secondary clarifiers. This made flooding more severe.
4.2.5.2
The activated sludge process is comprised of aeration basins and secondary clarifiers. Effluent
from the FFRs is mixed with solids (referred to as RAS) that have settled by gravity in the
secondary clarifiers in the RAS mixing box to create mixed liquor. The mixed liquor flows into
the aeration basins and is aerated to remove BOD by converting it to biological solids that can be
settled out of the flow. The aeration basins are continuously aerated and mixed in order to
provide a suitable environment for the activated sludge microorganisms. The microorganisms
convert the soluble organics, colloidal solids, and ammonia-nitrogen to settleable biomass. A
portion of the settled solids is wasted directly from the aeration basins to control the population
of the microorganisms in the activated sludge process. These solids are referred to as “waste
activated sludge” (WAS) and are pumped to the sludge thickeners. The remaining solids (RAS)
settle in the secondary clarifiers by gravity and are returned to the aeration basins via RAS
mixing box to seed the biological process. The effluent from the secondary clarifiers then flows
to the tertiary filter facilities.
Activated Sludge Process (Aeration Basins and Secondary Clarifiers)
Five centrifugal blowers supply compressed air to the aeration basins via ceramic fine bubble
dome diffusers to provide oxygen for the activated sludge microorganisms and mixing of the
mixed liquor. Blowers 1 and 3 run approximately 25 percent of the time on average, Blowers 2
and 4 are not currently in operation, and Blower 5 runs continuously providing the minimum air
requirements for the aeration basins. The fine bubble ceramic domes (19,000) were initially
installed in 1988 to replace an air sparger and mixer system installed in 1972. The fine bubble
ceramic domes have been replaced in 1999 and 2009, and will likely need to be replaced every
10 years.
4.2.6 Tertiary Treatment
Secondary effluent is lifted by four pumps to the 12 dual media filters (DMFs). The DMFs
remove suspended solids, oil, and grease carried over from the secondary clarifier effluent.
During filtration, solids and scum are trapped by the filter media as the wastewater flows
downward through it. The filter media consists (from top to bottom) of a 24-inch layer of
anthracite coal, 12 inches of sand, and 12 inches of graded gravel, ranging from #10 mesh to
1-inch size. The sand and coal make the filter a "dual media" filter. All filters are in use under
normal operating conditions; however, they are piped so that any single or combination of filters
can be removed from service for maintenance or backwashing.
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Eventually, the accumulation of the matter in the spaces between the media grains affects the
performance of the DMFs. The DMFs are backwashed regularly to flush out the accumulated
solids from the filter media grains and restore the filter to its full capacity/performance. The filter
backwash waste flows by gravity into one of the six mud wells and is pumped to the influent
channel of the PSTs. Six clear wells provide storage of filtered water for use in backwashing and
surface washing. Filter effluent flows in to the DMF final junction box (formerly the chlorine
mixing chamber), discharges into twin overflow weirs to the 96-inch diameter pipe, and on to
disinfection by ultraviolet (UV) light.
Wet weather flows exceeding the DMF lift pump capacity of 40 mgd can be directed to either the
empty secondary clarifiers or bypass the DMF directly to the UV disinfection facility.
4.2.7 Disinfection
From 1972 to 2008, final effluent was disinfected with gaseous chlorine and dechlorinated with
gaseous sulfur dioxide. In 2008, an interim disinfection system of liquid sodium hypochlorite
and sodium bisulfite was used. Ammonia was added to create a more stable chlorine residual and
reduce chlorodibromomethane levels in the final effluent, which is a byproduct of chlorination.
In August 2010, UV became the primary means of disinfection. Disinfection via sodium
hypochlorite, dechlorination via sodium bisulfite, and ammonia addition became unnecessary
and are now used for backup purposes only.
The RWQCP’s UV system is designed to disinfect water to meet the permit limit of 35 colonies
Enterococcus per 100 milliliters (mL) over a 30-day geometric mean set by the U.S. EPA for
coastal recreational waters and estuaries. Radiation from UV lamps penetrates an organism's cell
walls, permanently altering the DNA structure of the microorganism and destroying its ability to
reproduce. The system design meets the 35 MPN per 100 mL limit for flows up to 54 mgd when
TSS is less than 10 mg/L and can disinfect up to the peak wet weather flow of 80 mgd for short
periods.
From the UV disinfection system, most of the treated wastewater flows through the effluent
junction box to the 54-inch diameter outfall to the South San Francisco Bay, and the remainder
of flow is discharged through a controlled outfall to Matadero Creek. In the event the 54-inch
diameter outfall pipeline is out of service due to an emergency or for maintenance, a wall of stop
logs in the effluent junction box and a 36-inch diameter pipeline discharging to the old yacht
club harbor provide for emergency discharge location.
During recycled water mode, the recycled water will be taken from channel 4 of the UV facility.
When in outfall mode, channel 4 water is directed to the receiving waters and is disinfected at a
much lower dose.
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4.2.8 Outfalls
After UV disinfection, the final effluent flows into the former chlorine contact tank outlet box
and over a weir wall into the outfall box where final sampling takes place. The RWQCP
discharges to two receiving waters: South San Francisco Bay and Matadero Creek.
Approximately 95 percent of the treated wastewater is discharged to South San Francisco Bay
through a 2,100-foot long 54-inch diameter reinforced concrete outfall pipe directing final
effluent to an unnamed, manmade channel that is tributary to the Bay. The remaining
approximately 5 percent of the treated wastewater is discharged to the Emily Renzel Marsh Pond
where it flows through a controlled outfall to Matadero Creek.
4.2.9 Recycled Water
The RWQCP can produce recycled water (RW) meeting state standards (i.e., CCR Title 22 and
the NPDES permit) in two ways:
Dual media filtration followed by UV disinfection (6.3 mgd capacity).
Recycled water plant filtration followed by chlorination (4.5 mgd capacity – designed for
6.26 mgd, but limited due to the allowable hydraulic head over the top of the filters).
Production of RW using the DMF/UV system will serve as backup only to the
filtration/chlorination system.
The RW plant at RWQCP consists of both filtration and disinfection by sodium hypochlorite to
satisfy state reuse regulations. The filters were converted from a former vacuator. There are four
filters in compartments divided by steel walls and a steel floor (containing an underdrain
system). Each compartment contains deep-bed mono-media, which is a coarse sand, and can be
operated independently. The majority of filtration is accomplished at the DMFs, but coarse sand
is needed as a polishing filter to meet the State’s requirements for recycled water. Sodium
hypochlorite is injected into the two filter effluent lines that combine together before flowing
into the RW Chlorine Contact Tank.
Plans for providing RW to the Palo Alto Golf Course began during the RWQCP’s original
design in 1934. However, it was not until 1975, when Santa Clara Valley Water District
(SCVWD) built a state-of-the-art water treatment facility that could produce 2 mgd of water for
ground water recharge and some (treated to a lesser extent) for landscape irrigation, that RW was
used. Distribution systems were expanded from 1977 through 1979. Since there was no saltwater
barrier for the groundwater, the advanced treatment system was decommissioned by SCVWD
and transferred to Palo Alto in 1986. Palo Alto continued to operate the RW facilities for
landscape irrigation in Mountain View. In 1990, RW distribution was extended to Greer Park
from the existing line. In 1993, it was extended to Palo Alto's Municipal Service Center (MSC)
yard and a new pipeline was installed to the Palo Alto Golf Course.
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In 2008, the RW Pump Station was upgraded and a new distribution system was built to supply
new customers in Mountain View in addition to restoring an existing pipeline that had been out
of service since 2001. The goal of the new pump station and pipeline was to deliver 1,503 acre-
feet per year (or 489 million gallons per year). As of February 2012, the system was delivering
39 percent of this goal.
4.2.10 Solids Treatment and Handling
The RWQCP solids treatment and handling facilities consist of screenings handling (see
Section 4.2.3.1), grit handling (see Section 4.2.3.3), sludge and scum handling, and ash handling.
Sludge and scum handling and ash handling are described in this section.
4.2.10.1
Four gravity sludge thickeners (thickeners) were originally constructed in 1972 and are located
adjacent to (along) the PST influent channel. Each thickener is aligned with a PST (i.e.,
thickeners 1, 2, 3, and 4, align with PSTs 1, 2, 3, and 4, respectively). The thickeners provide
gravity thickening of the primary sludge and WAS. The thickener overflow is discharged into the
PST influent channel. Thickener No. 4 has never been used due to hydraulic issues, and its
mechanical equipment was removed in 2002. In addition, the rotating mechanisms for Nos. 1, 2,
and 3 were replaced in 2002.
Sludge and Scum Handling
A sludge blanket of about one foot is normal in the thickeners. Sludge depths less than one foot
deep can cause “rat holing” around the sludge hopper allowing water (instead of sludge) into the
sludge lines. Thickened sludge (approximately 3 to 6 percent solids) is pumped to the sludge
blend tank outside the Incinerator Building. After the thickened sludge is blended, it is pumped
to belt filter presses (BFPs) inside the Incinerator Building. The sludge blend tank and new
sludge feed pumps were installed in 1999 to address problems with diurnal variations in sludge
composition in the incinerator.
The BFPs along with polymer and sodium hypochlorite addition provide dewatering and odor
control of the thickened sludge before it is fed into one of the two multiple hearth furnaces
(MHF). Dewatering of the thickened sludge is necessary to reduce the need for auxiliary fuel
(i.e., natural gas) in the MHFs. The BFPs can produce up to a concentration of 38 percent solids
on average, however typical sludge cake is 28 percent solids for optimal MHF operation (i.e.,
higher percent solids cake can combust prematurely in the upper levels of the furnace).
Scum can be collected from the PSTs, grease deliveries, thickeners, and secondary effluent
channel. Existing operations regularly receive scum from the PSTs and grease deliveries. The
thickener's scum system is not used in order to avoid clogging the scum pipes and the scum
concentrator. Scum from the secondary effluent channel is removed seasonally and sent to the
primary influent channel for reprocessing by the PSTs. Collected scum is pumped into the scum
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concentrator, which was originally installed in 1980 (completely replaced in 2001), and sits
inside the Incinerator Building. It removes up to 50 percent of the water from the scum prior to
sending it into the MHFs. The scum is blended with dewatered sludge (i.e., after the BFPs) as it
is conveyed to the MHFs because incinerating scum in the absence of dewatered sludge cake is
unsafe.
Thermal destruction of dewatered sludge and scum takes place in two MHFs, which were
originally constructed in 1972 and rehabilitated in 1999. For operations and maintenance
reasons, only one MHF runs at a time for yearlong periods. The MHFs are capable of operating
at partial or full capacity.
The sludge cake in Hearth No. 1 (uppermost hearth of the MHF) is moved by rabble teeth on the
radial arms towards an opening near the central shaft. The sludge drops to Hearth No. 2 and the
feed material is rabbled to drop holes at the periphery. This alternating pattern causes a
countercurrent flow of sludge cake and hot gases of combustion. The rabble pattern was
improved in 1999 to increase the amount of time sludge spends in each hearth and avoid
problems with plowing and clinker formation.
The RWQCP air permit limits the total capacity of the MHFs to 32 dry tons per day in any
30-day period and 55 dry tons per day for any 24-hour period (i.e., monthly max and daily max,
respectively). Currently, the MHFs process approximately 18 dry tons per day. The flue gas is
cleaned in an afterburner followed by a wet-scrubber with a packed bed and multiple venturis
before discharging to the atmosphere. The scrubber waste washwater and the BFP filtrate are
discharged into a plant sewer and returned to the NPP barscreen channel.
As part of the LRFP, a seismic assessment of the incinerator’s anchorage was performed (see
Chapter 5). It was determined that the anchorage will withstand the 2009 CBC required ground
acceleration of the earthquake at its given location; however, localized damage may occur within
the furnace and become non-functional. Loss of natural gas could lead to thermal shock if the
furnace cooled down too quickly and created thermal stress upon the bricks, leading to collapse
of the hearths. An emergency/backup option needs to be established for solids processing and
handling, should localized damage or hearth collapse occur.
4.2.10.2
Ash is generated from the incineration of the dewatered sludge and scum. The ash is cooled in
Hearth No. 6 of each MHF and moved by the rabble arms to a drop chute in the Incinerator
Building basement. The original 1972 ash handling system was inside the Incinerator Building,
but a new ash handling system was installed outside the Incinerator Building adjacent to the
sludge blend tank in 2002. The ash is broken up, pneumatically conveyed into a storage hopper,
Ash Handling
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and trucked weekly to a landfill as non-Resource Conservation and Recovery Act (RCRA)
hazardous waste.
4.2.11 Utility Systems
The RWQCP has various utility systems that are important to the overall operation of the
facilities. These systems require careful operation and maintenance for achieving maximum
performance and producing an effluent meeting NPDES permit requirements. The utility systems
included in this section are:
Water systems
Compressed air systems
Plant drainage systems
Methane gas systems
Diesel fuel systems
Plant communication systems
Power and communication/SCADA systems
Heating, ventilating, and air conditioning systems
4.2.11.1
Water for the RWQCP is provided from two sources:
Water Systems
City of Palo Alto Utilities (CPAU) Department potable water supply, which supplies No. 1
Water (W1), No. 2 Water (W2), and fire sprinkler standpipe water.
RWQCP effluent process water, which supplies No. 3 Water (W3) and No. 4 Water (W4).
No. 1 Water (W1)
The CPAU supplies W1 to:
Operations Building – laboratory, toilets, sinks, floor drain trap primers, and the hot water
heater
Administration Building – laboratory, toilets, sinks, and the hot water heater
Maintenance Building
Incinerator Building bathroom
Water transmission shop sinks
Hose bibs – oil storage, septic haulers
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Eye wash stations
No. 2 Water (W2)
After W1 has passed through an onsite plant-owned backflow preventer, it becomes W2. W2 is
primarily used as pump seal water (except at the NPP, FFRs, DMFs, and blowers) and for other
in-plant processes, such as:
Seal water
–Normal operation – recycled water pump room
–Backup to W4 supply
Operations Building – boiler makeup water and the hot water storage tank
Alum mixing water
Reclamation plant air compressor water cooler
Hose bibs – street sweeper pad, equipment rooms
Nos. 3 and 4 Water (W3 and W4)
The W3 and W4 are supplied from the UV disinfection facility effluent bay or the recycled water
storage tank (not at the same time). W3 is low-pressure water, which is used for the air pollution
control quench unit, for the air pollution control packed bed in the wet scrubbers, and for backup
water to the belt filter press spray water system. W4 is high-pressure water used in the following
ways:
Process water: pump seal water, incinerator scrubber venturis, polymer mixing water and
dilution water, belt filter presses, ashveyor cooling water, and blower oil cooling.
Spray systems: gravity thickener launders, bar screens, secondary clarifiers (square),
outfall box (turned off due to chlorine residual in water), biofilters, and mud well cleaning.
Trough water: primary sedimentation tank scum trough, screenings press, and grit
classifier.
Washwater: hose bibs, flushing connections, blend tank, wash pads (liquid septic haulers,
grease haulers, street sweepers, etc.), and hydrants (closed landfill service road and salt-
water marsh intake screen).
Miscellaneous: plant landscaping (Operations Building, Administration Building, and
onsite redwood trees), Operations Building moat supply water, and Operations Building
chiller heat exchanger cooling water.
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4.2.11.2
The RWQCP produces high-pressure air through four compressors (one lead, one lag, and two
standby) that supply compressed air for:
Compressed Air Systems
Quick-connects throughout the RWQCP
Valve actuators at the Reclamation Plant, DMFs, and incinerator induced draft fan/exhaust
stack/bypass damper
Ash handling equipment
Level bubblers at the NPP and OPP influent wells
Tool power at the Maintenance Building
4.2.11.3
The RWQCP’s heating, ventilating, and air conditioning (HVAC) equipment services staff
facilities, which include Administration Building, Operations Building, Maintenance Building,
and the Incinerator Building’s control room. Programming logic control (PLC) cabinets are air-
conditioned, while most process and electrical areas are ventilated with exhaust fans to ensure air
circulation and changes. HVAC maintenance is provided through a service contract.
Heating, Ventilating, and Air Conditioning Systems
4.2.11.4
The RWQCP has two key sources of power: electricity and an onsite photovoltaic (PV) system.
Electricity is purchased from CPAU. The origin of CPAU electricity changes periodically. In
wetter years, the energy mix is comprised of more hydroelectric-derived energy; while in dryer
years, the energy mix is comprised of more fossil fuel-derived energy (such as natural gas and
oil). By 2015, CPAU electricity is expected to be 50 percent hydroelectric, 33 percent other
renewable energy sources, and 17 percent (i.e., the balance) from fossil fuel based energy
sources in the short-term electricity markets. The RWQCP purchases 50 percent of its energy
demand through CPAU’s PaloAltoGreen program supporting energy suppliers that provide
100 percent renewable energy resources.
Power Systems
A small portion of the RWQCP’s energy demand is met by the onsite PV system. In 2007,
SolFocus of Mountain View entered into an agreement with Palo Alto to provide free solar
power in exchange for use of the RWQCP site for research and development of solar arrays. In
2011, the UV disinfection facility rooftop began transmitting solar power to the RWQCP’s onsite
electrical grid.
Electrical power serving the RWQCP is distributed through a 12,470-volt underground system to
nine load centers. Each load center consists of a fused disconnect switch, oil-cooled or dry-type
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transformer, and secondary power circuit breakers. The secondary power circuits feed motor
control centers and panels located in various buildings across the RWQCP.
4.2.11.5
The RWQCP instrumentation system provides operational control and surveillance of the facility
operation. Newer equipment at the RWQCP includes PLCs, SCADA, alarm text messaging,
digital radios, and advanced HMI graphics. The system includes various traditional instrument
loops (a computer system and main instrument console with an alarm annunciator panel and
graphic display) housed in the Operations Building Control Room. The types of instrumentation
operated and/or measurements taken at the RWQCP include: sludge density meters; wet well
level measurements; raw wastewater, primary effluent, and aeration basin influent pH
measurements; primary effluent channel level measurements; recirculation sump level
measurement and control; aeration tank air flow measurements; dissolved oxygen measurements;
secondary clarifier effluent channel level measurement and control; DMF influent channel level
measurement and control, clear well and mud well level measurements, backwash flow rate and
control, effluent flow measurements and control, loss of head measurements, effluent turbidity
measurements, and effluent flow measurement; MHF oxygen measurements and control, draft
measurement and control, and temperature measurements and control; and RWQCP air and
water pressure measurements.
Instrumentation and Control System
4.3 PLANT PERFORMANCE AND CRITERIA REVIEW
This section summarizes the overall performance of the RWQCP with respect to meeting
conventional, non-conventional, and effluent ammonia limits in the NPDES Discharge permit. In
addition, recommended criteria for estimating the RWQCP’s process capacity is summarized.
Since the existing facility’s performance provides an important benchmark for the planning of
new facilities, historical performance and capacities for each process are also reviewed using
operating data from January 2005 through August 2010.
4.3.1 Overall Performance Summary
Conventional and non-conventional pollutants regulated in the RWQCP’s NPDES permit include
5-day carbonaceous biochemical oxygen demand (CBOD5), total suspended solids (TSS), oil and
grease, pH, total chlorine residual, turbidity, and Enterococcus bacteria. In addition to these
pollutants, the RWQCP has established limits for various toxic pollutants including ammonia.
Table 4.2 provides a summary of the effluent concentrations for conventional, non-conventional,
and toxic pollutants during the review period, as well as the effluent limits in the most recent
NPDES permit. See Chapter 6 for a discussion of the RWQCP’s regulatory requirements and
toxic pollutants.
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Table 4.2 Overall Pollutant Removal Performance Summary
Constituent
NPDES Limit (Order
No. R2-2009-0032)
2005 – 2010
Performance
Conventional and Nonconventional Pollutants
Toxic Pollutants
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During the review period, the RWQCP has performed very well and met almost all pollutant
limits established in its NPDES permit There have been some violations of pH and
chlorodibromomethane limits over the review period. The implementation of UV disinfection
eliminated the formation of chlorodibromomethane.
Figure 4.4 shows the monthly average effluent concentrations for BOD5, TSS, and ammonia.
Note that concentrations for all of these constituents were consistently low. TSS concentrations
were consistently less than 2 mg/L with no observable trends during the review period. In the
spring of 2007, there was a small, but distinct increase in the effluent BOD5 and ammonia
concentration. This coincides with the time the RWQCP began adding ammonia to the
disinfection process, which would explain the minor increase in the effluent concentration for
these constituents. Even with this operational change, effluent BOD5 and ammonia have been
consistently less than 4 mg/L and 1.5 mg/L, respectively, for the last 3 years. In August 2010, the
City stopped practicing chloramination and staff has reported a slight decrease in ammonia and a
slight increase in BOD.
4.3.2 Process Performance Summary
Table 4.3 summarizes key performance (e.g., loading) data from 2009. Although data from prior
years was reviewed, they are not discussed in this section since data sets prior to 2009 were not
complete (e.g., the primary sedimentation tank removal rates were not available until September
of 2008). In addition to summarizing 2009 performance data, the original design criteria, as well
as the typical and recommended criteria used for the capacity analysis are provided.
The following sections review key findings from the performance review for each process.
4.3.2.1
The capacity of the headworks and influent pumping facilities is established by the firm pumping
capacity (i.e., capacity with the largest unit out of service) and the hydraulic capacity of the bar
screens and channels. The bar screens and channels have been sized to maintain a minimum and
maximum velocity during low and peak flow conditions, respectively.
Headworks and Influent Pumping
The influent pumping is divided into the NPP (Pump Nos. 1-6) and the OPP (Pump Nos. 7-9). A
hydraulic test was conducted on December 11, 2010 that established the NPP and OPP total and
firm capacities. Table 4.4 shows the results of the hydraulic tests.
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Figure 4.4
MONTHLY AVERAGE EFFLUENT BOD,
TSS, AND AMMONIA
LONG RANGE FACILITIES PLAN FOR THE RWQCP
CITY OF PALO ALTO
pa512f16-8510.ai
BOD and TSS Permit Limit (10 mg/L)
Ammonia Permit Limit (2.7 mg/L)
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Table 4.4 Influent Pumping Capacity
New Pumping Plant Old Pumping Plant
(2)Combined
During the data review period, maximum peak flows of 67.6 and 64.3 mgd were recorded on
January 1, 2006 and January 20, 2009, respectively. A peak hour wet weather flow (80 mgd) was
recorded and treated by the RWCQP during a February 1998 storm event.
Although the pumping capacity is higher, the limit is in the bar screens. The headworks are
comprised of three bar screens each with a capacity of 30 mgd each. A hydraulic analysis was
not performed to verify that maximum channel velocities are not exceeded during peak flow
conditions.
4.3.2.2
During the review period, the RWCQP typically operated with all four (4) primary sedimentation
tanks in service. They have performed well within the range for typical primary sedimentation
tanks with BOD5 and TSS removal in 2009 averaging 36 and 64 percent, respectively. This is
better than previous design criteria, which estimated BOD5 and TSS removal to be 30 and
60 percent, respectively. It is possible that the improved performance may be due to the fact that
the actual overflow rates are less than the original design criteria. Another plausible explanation
could be that the settleable solids have a higher volatile solids (VS) content than typical
settleable solids; however, additional wastewater characterization would be needed to confirm or
refute this explanation. Although performance has been better than original design criteria, it is
recommended that the capacity analysis be based on achieving slightly reduced removal
compared to the current operation. This is recommended since future operation will be at higher
overflow rates, which will likely result in reduced removal rates. At high overflow rates typical
removal rates for BOD and TSS removal range from 25 to 30, and 50 to 60 percent, respectively.
The capacity analysis will be based on these removal rates.
Primary Sedimentation Tanks
It should also be noted that the previous design overflow rate criteria are conservative when
compared to typical criteria used today in designing primary sedimentation tanks (see MOP-8
values in Table 4.3). Since the criteria are conservative and the primary sedimentation tanks have
demonstrated satisfactory performance to date, the recommended peak hour overflow rates for
establishing capacity are higher than the original design criteria.
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4.3.2.3
In 2009, the RWQCP had both FFRs in operation and averaged approximately 49 percent
removal of BOD5. Although this matches the original design objective of 50 percent removal, it
was achieved at BOD loading rate of 98 ppd BOD5/kcf (1,000 cubic feet) of media, which is
lower than the original design loading of 126 ppd BOD5/kcf during ADWF conditions. As flows
to the FFRs increase, they will be operating at higher loadings, which may result in reduced
BOD5 removal. However, with sufficient recirculation and forced air ventilation, practical
experience demonstrates that BOD5 loading rates of up to 200 ppd BOD5/kcf can be sustained by
the process as long as there is sufficient solids retention time (SRT) in the downstream activated
sludge process. In order to maximize the capacity of the FFRs, it is recommended that their
capacity be established based on an ADMM loading rate of 200 ppd BOD5/kcf. At this loading
rate, BOD removal is expected to be reduced to 35 to 40 percent.
Fixed Film Reactors
4.3.2.4
During the review period, the RWQCP typically operated with all four (4) aeration basins in
service. In 2009, this process has been operated at an average SRT of 11.8 days, an average
mixed liquor suspended solids (MLSS) concentration of 2,730 mg/L, and a dissolved oxygen
concentration of 4 mg/L.
Aeration Basins
As expected, the aeration basins have performed well with respect to removing soluble organics
from the mixed liquor stream. The process has also consistently removed ammonia as effluent
concentrations are typically less than 1 mg/L.
The key criterion for establishing aeration basin capacity for a nitrifying process is the aerobic
SRT. The SRT is defined as the total mass of solids in the aeration basins divided by the mass of
solids leaving the secondary process every day (i.e., WAS and secondary effluent solids). The
required SRT will depend on the minimum monthly temperatures and the required effluent
ammonia limits. In general, colder temperatures and lower effluent requirements will require
longer SRT’s to obtain adequate treatment. A review of 23 years of daily liquid temperature data
found that 20 degrees C is the 10th percentile value, which reflects a reasonable minimum month
condition. Accordingly, it is recommended that 20 degrees C be used as a basis for establishing
an appropriate SRT.
Figure 4.5 illustrates the relationship between temperature, effluent ammonia requirements, and
the minimum recommended aerobic SRT. If it is desired to only meet the City’s current NPDES
ammonia limit of 2.7 mg/L, a four-day SRT would be adequate, even during the cold weather
periods when minimum monthly temperatures drop down to 20 degrees C. However, experience
in the San Francisco Bay Area shows that maintaining nitrification at a four-day SRT will
require a very high degree of operator attention. In addition, operation at this SRT may result in
periodic ammonia breakthrough during cold weather periods.
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Figure 4.5 Minimum Recommended Solids Retention Time
At a five-day SRT, an effluent ammonia concentration of 1 mg/L would be achievable even
during cold weather periods. In addition, operating at a five-day SRT will improve process
stability and reduce the risk of periodic ammonia breakthrough.
The recommended maximum MLSS concentration is 3,500 mg/L, which is a typical upper limit
for this type of process. Operating above 3,500 mg/L will reduce the effective oxygen transfer
capacity of the aeration equipment. Also, unless an anaerobic selector is implemented, operating
above 3,500 increases the risk of having settleability issues. A solids flux analysis indicates that
the secondary clarifiers will be able to accommodate the solids loading associated with
increasing the MLSS concentration up to 3,500 mg/L.
4.3.2.5
During the review period, the plant has typically operated with four (4) of the six (6) secondary
clarifiers in operation and has achieved adequate removal of solids, even during wet weather
periods.
Secondary Clarifiers
A solids flux analysis was performed to develop a recommended overflow rate for establishing
the clarifier capacity. The allowable overflow rate depends on the operating MLSS concentration
and the settleability, or sludge volume index (SVI) of the mixed liquor. The SVI measurement
reflects the volume that solids in a mixed liquor sample will compress to after 30 minutes. In
general, the lower the SVI, the faster the solids will settle. As MLSS concentrations and SVI’s
increase, settling velocities will decrease and the clarifiers will need to be operated at lower
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overflow rates to prevent a solids loading failure. Using a solids flux analysis, allowable
overflow rates were estimated for a range of conditions. Figure 4.6 illustrates the relationship
between allowable clarifier overflow rates and the MLSS concentration and SVI.
Figure 4.6 Allowable Clarifier Overflow Rates
Although no SVI data was collected during the review period (2009), the SVI of 12 mixed liquor
samples were measured between 3/23/11 and 4/18/11 and used for the capacity analysis during
the LRFP effort. The SVI data collected ranged from 26 to 33 mL/g with an average of 28 mL/g.
SVI’s for this type of process typically range from 50 to 150 mL/g, therefore, it appears the plant
has a very well settling mixed liquor.
Based on the solids flux analysis, it is recommended that the peak overflow rate not exceed the
original criteria of 1,180 gpd/sf. It is also recommended that the rated capacity be based on the
radial area for the square clarifiers, as experience has shown the corners do not provide effective
settling area. At the recommended overflow rate, the clarifiers should be able to accommodate
the solids loading resulting from an MLSS of 3,500 mg/L at an SVI up to 100 mL/g. The rated
capacity of the secondary clarifiers is therefore 80 mgd. It should be noted that the secondary
clarifiers are currently operating below this rated capacity even at the peak wet weather flows
recorded, and this capacity is not expected to be exceeded at build out if there are no regulatory
changes.
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Subsequent to the capacity analysis, additional SVI data was collected through 2012 (almost one
year’s worth of data). The average of this SVI data from 2011 to 2012 is 33.2 mg/L. This is
consistently below 50 mg/L. This means that it is possible to increase the loading rate to the
secondary clarifiers. However, given the fact that these are square clarifiers with a relatively
shallow side water depth, it is not recommended to operate at higher overflow rates unless stress
testing is conducted. A stress test would determine if higher overflow rates are sustainable and
the re-rated capacity of the units.
If there are regulatory changes and the process changes in the future, the current SVI data will
not be applicable and any future evaluation will be based on an SVI value of 100 mg/L.
4.3.2.6
The dual media filters were originally designed for a peak hydraulic loading rate of 6 gpm/sf. In
2009, the average loading rate was 2.9 gpm/sf with short-term peak loading rates approaching
6 gpm/sf. Performance has been adequate during the review period and it is recommended that
the original design criteria of 6 gpm/sf be used for evaluating their capacity.
Dual Media Filters
4.3.2.7
The recycled water filters were originally designed for a peak hydraulic loading rate of 5 gpm/sf
based on Title 22 requirements. In 2009, the average loading rate was 0.5 gpm/sf with short-term
peak loading rates approaching 1.5 gpm/sf. This was based on the assumption that recycled water
flows occurred over an eight-hour period with one filter out of service. Performance has been
adequate during the review period and it is recommended that the original design criteria of
5 gpm/sf be used for evaluating future capacity.
Recycled Water Filters
4.3.2.8
Based on the recycled water flow rates in 2009, the average theoretical detention time in the
recycled water chlorine contact basin was significantly greater than the 90-minute minimum
modal time required by Title 22. The 2009 tracer study on the recycled water chlorine contact
basin determined that the 90-minute modal contact time was achieved at a flow rate of 8.25 mgd.
Based on the limitation of the recycled water filters however, the design capacity of the recycled
water chlorine contact chamber is rated at 4.5 mgd. At this flow rate, the modal contact time is
165 minutes, which is greater than the 90-minutes required by Title 22.
Recycled Water Chlorine Contact Basin
4.3.2.9
The UV disinfection system was designed to achieve a 30-day geometric mean of less than
35 colonies/100 mL of Enterococcus bacteria. The 2009 data show performance has been
adequate.
Ultraviolet Disinfection
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4.3.2.10
During the review period, the RWQCP has operated with two (2) of the four (4) gravity
thickeners in operation. In 2009, the average solids loading was 16.9 ppd TS/sf, which is higher
than its original design loading, and higher than the typical range of 5 to 14 as noted in MOP-8.
The average thickened solids concentration in 2009 was 3.3 percent, which is adequate, but
lower than expected. For a feed stream with WAS and primary sludge, a thickened solids
concentration ranging from 4 to 6 is more typical. The lower than expected concentration may be
partially explained by the relatively high solids loading rate. It may be possible to increase the
thickened solids concentration if another gravity thickener is brought on-line. It is recommended
that an average solids loading rate of 16.9 ppd TS/sf be used for establishing the rated capacity of
the gravity thickeners.
Gravity Thickening
Sufficient information was not available to estimate the solids capture across the process, which
is another important performance metric for a thickening process.
4.3.2.11
During the review period, the plant typically operated only one (1) of its three (3) BFPs.
Performance has been excellent, achieving an average cake solids concentration of 28 percent.
This is likely due to the fact that the solids have not been digested and are therefore more easily
dewatered. The typical range in solids loading rate is 1,600 to 2,000 lb TS/hr/m of belt per MOP-
8. While the original design rating is 1,670 lb TS/hr/m, it is recommended that an average solids
loading of 1,800 lb TS/hr/m of belt be used for establishing process capacity.
Solids Dewatering
Sufficient information was not available to estimate the solids capture across the process, which
is another important performance metric for a dewatering process.
4.3.2.12
During the review period, the plant typically operated only one (1) of its two (2) incinerators.
Each incinerator has six (6) multiple hearth furnaces with a total area of 2,200 sf. Based on the
1972 RWQCP construction, the incinerators have a design capacity rating of 7.6 lb cake/hr/sf.
Rehabilitation of the incinerators was done in 1999, and the capacity was re-rated at 5.2 – 6.9 lb
cake/hr/sf (based on the VonRoll process flow diagrams) In 2009, the average loading was 6.0 lb
cake/hr/sf. The typical range in solids loading rate is 8 to 10 lb cake/hr/sf per MOP-8. It is
recommended that an average solids loading of 8 lb cake/hr/sf be used for establishing process
capacity.
Incineration
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4.4 CAPACITY ANALYSIS
This section summarizes the results of the capacity analysis. Capacities were estimated for each
of the treatment processes based on the recommended criteria provided in Table 4.3.
4.4.1 Peak Flow Capacity
The Peak Hour Wet Weather Flow (PHWWF) capacity was estimated for facilities where sizing
is established by the peak flow. These facilities include influent pumping and bar screens,
primary sedimentation tanks, secondary clarifiers, dual media filtration, UV disinfection, and the
chlorine contact basins. Capacities for process units are estimated based on all units being in
service, while pumping capacities are based on the largest unit being out of service. Table 4.5
summarizes the PHWWF capacity for each of these processes.
Table 4.5 Peak Hour Wet Weather Flow Capacity
Process PHWWF Capacity (mgd)
4.4.2 Organic Loading Capacity
The organic loading capacity was estimated for facilities where sizing is established by influent
BOD5 and TSS loading to the plant. These facilities include the FFRs, aeration basins, gravity
thickeners, dewatering, and incineration.
To determine the capacity for these facilities, a plant process model was developed and
calibrated to historical operating data from the year 2009. Using the process model to simulate
maximum month conditions, the influent flow and load was increased until the operating limits
(as established in Table 4.3) were exceeded for each particular unit. This BOD5 load was taken
as the maximum month capacity limit for that particular unit. The maximum month load capacity
was converted to an equivalent maximum month flow based on the anticipated wastewater
strength identified from the flows and loads analysis. The maximum month capacity was also
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converted to an equivalent average dry weather capacity based on the historical peaking factors
observed (see the flows and loads analysis in Chapter 3).
Table 4.6 summarizes the calculated capacity for each process for all units in service and also
one unit out of service.
Table 4.6 Organic Loading Capacity
Process
ADMM Capacity
Equivalent ADWF
Capacity
Equivalent ADWF
Capacity – One Unit
Out of Service
Influent
BOD5,
lb/d mgd
(1)mgd (2)
Influent
BOD5,
lb/d(3)mgd (2)
Influent
BOD5,
lb/d(3)
Based on the ADWF projections of 28.6 to 34.0 mgd in 2062 (as presented in Chapter 3), it
appears there is adequate organic loading capacity at the plant for virtually the entire planning
period. Although the FFR capacity is noted as 31.7 mgd, it may be preferable to operate the units
at a slightly higher loading rate (less than 5 percent greater than recommended criteria) to avoid
the high cost of constructing another unit. Alternatively, when the FFRs are rehabilitated, the
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cost-effectiveness of raising the height of the media and walls should be considered in relation to
the potential process benefits. The gravity thickeners and incineration capacity fall short of the
projected 2062 flow if a unit is taken out of service. Should this occur, the City would need to
plan accordingly with temporary facilities or by constructing additional capacity.
It is important to note that the results of the organic loading capacity analysis are based on the
number and configuration of the existing process units at the plant. If the secondary process is
expanded in the future and the process configuration is changed to meet future regulations, the
capacity of the solids handling facilities (i.e., thickening, dewatering, and incineration) will
increase. This is due to the fact that the aeration basins would be operated at longer SRTs, which
will reduce the amount of sludge generated and increase the capacity rating of the solids
handling facilities.
The capacity ratings identified for the aeration basin are calculated based on the volume needed
to maintain a minimum SRT. To realize this rated capacity, the City may need to increase the
capacity of the aeration equipment if anaerobic digestion is implemented in the future. The
existing total capacity of the aeration system is 54,600 scfm with all blowers in service. This
much aeration would be necessary due to the increased ammonia load and oxygen demand
returned in the dewatering filtrate if anaerobic digestion were implemented. Additional aeration
equipment capacity may also be needed if the City desires to continue to operate the aeration
basins at a dissolved oxygen (DO) concentration of 4 mg/L, which was the average concentration
in 2009. The City began testing the performance of the existing activated sludge process at DO
levels of 2.0 mg/L and experienced rising nitrites, ammonia, and and breakpoint chlorination at
the recycled water plant. The City decided to return DO levels to 4.0 and lower them 0.1 mg/L
every 2 weeks to determine the lowest setpoint at which nitrite levels will not increase. The City
should continue to monitor the progress of lowering the DO levels in the basins. If lower DO
levels are not achievable, the sizing for aeration equipment may need to be revisited as loads
increase over time and when and if anaerobic digestion is implemented. Aeration air
requirements for each of the liquid treatment alternatives are presented in Chapter 8 of this
report.
4.4.3 Operational Data Collection
The RWQCP currently tests for approximately 70 different parameters in 10 different main
process sample streams. This monitoring allows for a very good assessment of the performance
of most unit processes. However, there was some additional special sampling required as part of
this LRFP to better assess the performance of more specific process units. SVI readings were
taken to characterize the settleability of the activated sludge to be used for assessing the capacity
of the secondary treatment system. In addition, primary sludge, DMF backwash, gravity
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thickener overflow, incinerator belt press filtrate and scum hopper overflow samples were also
collected to help assess the performance of the existing solids handling systems.
It is therefore recommended that SVI, primary sludge, DMF backwash, gravity thickener
overflow, incinerator belt press filtrate, and scum hopper overflow samples be included in the
regular sample schedule so that performance evaluations on these units can be trended, and
thickening and dewatering capture rates can be more accurately calculated in the future.
Additionally, because of the emphasis on solids treatment in this LRFP and the impact that
sludge flows can have on the treatment train capacity, it is also recommended that a flow meter
be installed on the primary sludge stream to the gravity thickeners.
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Chapter 5
EXISTING PLANT ASSESSMENT
5.1 INTRODUCTION
An assessment of the physical condition and remaining useful life of the existing mechanical
equipment was performed as part of this Long Range Facilities Plan (LRFP). This mechanical
assessment also provided the opportunity to identify operating deficiencies and potential
modifications or enhancements necessary to optimize operations including energy efficiency
measures. The results of the assessment are used to estimate the cost to modify or rehabilitate
existing facilities. The structural components of the facilities were assessed in 2006 and results
of that assessment were also considered as part of this LRFP in order to determine future process
and equipment needs and to develop data for comparing existing facilities/equipment with
alternative technologies.
5.2 CONDITION ASSESSMENT
Carollo Engineers, Inc (Carollo) performed a visual condition assessment on December 9, 2010
of the facilities with the focus on assessing mechanical equipment. The assessment used a
standard asset management approach as established in the International Infrastructure
Management Manual (IIMM), Version 3.0, 2006, written by the Association of Local
Government Engineering New Zealand, Inc (INGENIUM) and the Institute of Public Works
Engineering of Australia (IPWEA). The assessment team consisted of specialists in the process,
mechanical, and electrical engineering disciplines. The Regional Water Quality Control Plant
(RWQCP’s) veteran operator/assistant manager, Howard Yancey, accompanied the team
throughout the assessment and provided information on operations and maintenance history for
each process area. In some instances, operators of specific process areas were also available to
provide additional information. The mechanical equipment assessment findings are summarized
in this section.
The information provided in this chapter on existing RWQCP structures and some process piping
is based on the findings presented in the 2006 Facility Condition Assessment (FCA) Final Report
compiled by Kennedy/Jenks (K/J) Consultants. K/J performed a comprehensive FCA evaluating
the condition of concrete and metal structures and limited process piping that was of concern to
the RWQCP staff, but did not cover mechanical equipment. Appendix C contains K/J’s
assessment summary and Appendix D contains the list of recommended retrofits (costs in 2006
U.S. dollars) for RWQCP structures as presented in the 2006 FCA Final Report.
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5.2.1 Summary
The general findings of the condition assessment are that while much of the RWQCP unit
processes and equipment are nearing the end of their useful life and will be considered for
replacement, they have been well maintained and operated. Figure 5.1 shows an aerial view of
the existing facilities, major pipelines, and plant boundary. A summary of the major findings and
replacement costs by process area are shown in Table 5.1. Appendix E contains the complete and
detailed list of the facilities by asset, useful life, condition, assessment notes, the recommended
actions, and cost estimates. Condition of each asset is ranked on a scale that is an internationally
accepted, industry-wide standard for designating asset condition. The ranks range from 1 (very
good) to 5 (unserviceable). The repair/replacement cost estimates shown in Table 5.1 and
Appendix E are planning-level project cost estimates based on the standard procedure described
in the LRFP Basis of Cost TM (Appendix M). For those construction costs that are taken from
K/J’s 2006 FCA, the 20-Cities average ENR CCI for 2006 was assumed with a 40 percent
contingency to account for engineering, legal, administrative fees, construction management, and
environmental permitting/mitigation necessary. This additional contingency brings these
estimated construction costs to project costs. In Table 5.1, we are only showing the costs for
structural projects identified by K/J that have not been completed as of July 2010.
Appendix E also includes a repair and replacement schedule based on the results of the condition
assessment. The resulting recommendations were determined based on both the original useful
life of the equipment and the condition as noted/available during the assessment. Detailed
findings of the condition assessment are summarized in the following sections, organized by
process area.
5.2.2 Headworks
The following is a list of specific findings related to the headworks process area of the RWQCP.
1. The Motor Control Center (MCC) for the New Pumping Plant (NPP) pumps was originally
constructed with the NPP building and installed in 1972. The air duct piping clearance
within the building is not built to code since it is too close to the MCC.
2. The NPP Pump Nos. 1, 3, 4, and 6 were installed in 1972, and Pump Nos. 2 and 5 were
installed in 1987. The pumps have been well maintained since – regularly rotated based on
the number of hours operated and were rebuilt in the late 1990s. The pumps have minimal
vibration, but were a source of significant noise and require continuous backwater in the
72-inch diameter joint interceptor sewer line in order to prevent cavitation. The NPP pump
motors were upgraded to variable frequency drives (VFDs) – Pump Nos. 1 and 2 in 1987,
Pump Nos. 3, 5, and 6 in 1993, and Pump No. 4 in 1998. Motors do not have vibration
monitoring and their termination domes are too close to the MCC creating a work
clearance issue. The manual-auto VFDs on Pump Nos. 5 and 6 were not connected and
corrosion was showing at the coupling.
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3. The Old Pumping Plant (OPP) building was originally constructed in 1956 and the original
MCC is still in use. The OPP was not in operation during the assessment and is only used
during heavy wet weather events, for NPP maintenance, and for NPP isolation knife gate
valve exercising (i.e., the OPP is infrequently operated). However, there are reports of
excessive noise and vibration while the pumps (nos. 7, 8, and 9) are in operation. It is not
controlled by the RWQCP Supervisory Control and Data Acquisition (SCADA) system.
There has been flooding of the OPP in the past and electrical conduit is exposed within the
structure. There is existing budget to rehabilitate the OPP if it is decided to do so.
4. The three bar screens are nearing the end of their useful life (latest construction was
complete in 1993) and need better accessibility. The spray water is noisy at Bar Screen No.
1 and the exhaust fan is noisy at Bar Screen No. 3 (Bar Screen No. 2 was out of service
during the assessment).
5. The Meter Pit, originally constructed in 1972, is nearing the end of its useful life and needs
to be upgraded. However, the meters and gate valves were replaced in 2007 and are in
good functioning condition.
6. The Grit Handling facility was originally constructed in 1988 (refer to Appendices C and
D for K/J’s assessment and recommended retrofit). The electrical system panels are
corroded and in poor condition. The lighting in the facility needs to be replaced.
7. The 60-inch diameter force main taking screened influent to the Primary Sedimentation
Tanks was recently (2011) patched for repair at the meter pit due to a 0.5-inch hole in the
spool piece that was promptly replaced. It appears to be an isolated incident due to a post-
construction field weld.
5.2.3 Primary Treatment
1. Primary sludge Pump Nos. 3a and 3b were replaced with a single pump in 2001. Pump
Nos. 1 a/b, 2 a/b, and 4 a/b are at the end of their useful life and need to be replaced.
2. The four Primary Sedimentation Tanks (PSTs) Nos. 1 through 4 and their influent and
effluent channels are enclosed structures originally constructed in 1972 and are nearing the
end of their useful life. The plant staff stated there is corrosion and grease buildup in areas
inside, including corroded gates. Cracks and exposed rebar were observed on the roof of
the PSTs during the assessment. It is suspected that there is corrosion of concrete at the
water line as well.
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Figure 5.2 Cracks Observed on the Primary Sedimentation Tanks Roof
3. The Intermediate Pump Station (IPS) was incorporated into the plant for high flow events
to bypass the Fixed Film Reactors (FFRs) since the RWQCP staff found that the FFRs did
not perform well under high flow conditions. Pump motors are not high efficiency motors,
and are rarely used. The RWQCP needs to exercise the IPS at least weekly to maintain the
facility. Staff need to consider the life of the pumps before upgrading the IPS. Pump Nos. 2
and 3 currently have some vibration and noise during operation and are showing some
corrosion.
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5.2.4 Secondary Treatment
1. The North and South FFRs appear to have structural damage (e.g., leakage) and corrosion
and need to be re-assessed to determine the level of rehabilitation required (refer to
Appendices C and D for K/J’s assessment and recommended retrofits).
2. The North and South FFR Equipment/Pump Room’s lighting level is low and needs to be
increased.
3. There is a mobile 500-kilowatt (kW) generator with a manual transfer scheme outside the
FFRs – the City is planning to replace it with a stationary one that has an automated
transfer switch scheme.
4. The top layers (~3 feet deep) of the FFR media needs to be replaced since it is degrading
from age and exposure to the sun. There is also buildup of scum on the media resulting in
decreased performance.
Figure 5.3 Top Layers of Fixed Film Reactor Media are Aging and Showing Buildup
5. The Aeration Basin (AB) influent channel’s air piping needs to be checked for leaking
(i.e., efficiency) and needs to be recoated.
6. K/J’s assessment recommended retrofits on additional AB equipment and structures
(included in Appendices C and D).
7. A blower control project was completed in January 2012 led by Turblex (the manufacturer
replaced three of the five blowers in use).
8. The AB slide gates appear to be in good working condition.
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9. The AB fine bubble diffusers were last replaced in 2009 and have a 10-year original useful
life. The remainder of the air system will need to be replaced when the next bubble diffuser
replacement is due (2019). While the ceramic dome air diffuser system appeared to be
working sufficiently, the RWQCP staff would like to evaluate other diffuser technologies
in the future.
10. The coal tar epoxy coating of the MLSS steel piping is flaking.
11. The four Square Secondary Clarifier (Nos. 1 through 4) structures appear to be in working
condition (refer to Appendices C and D for K/J’s assessment and recommended retrofits),
but there is visible corrosion. A structural evaluation is recommended for the effluent
channel. There is also short-circuiting occurring due to the sidewalls not being deep
enough and the corners of the structures pose problems for the sweepers. The weirs need to
be checked to ensure they are level across the basins. In addition, the slide gate has visible
corrosion.
Figure 5.4 Visible Corrosion on the Secondary Clarifier Equipment
12. Square Secondary Clarifier collector mechanisms were rehabilitated in 1999 (inner rings
are rusting), but should have been replaced. Secondary Clarifier No. 2 has experienced
failure since rehabilitation. The RWQCP staff would like to replace existing mechanisms
with more stainless steel components at next replacement.
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13. The stationary generator serving the Round Secondary Clarifiers, Blower Room, and
Operations Building needs provisions for a permanent load bank, currently the City uses
the actual load to exercise the generator set which has automated transfer switches.
14. The torque switches at the Square Secondary Clarifiers need to be tested since the RWQCP
staff is not sure how well they perform/function. While the electric connection works, there
is uncertainty about whether the switches would activate in a high torque situation.
15. There is effective scum removal from the Square Secondary Clarifiers. Need to install a
mechanism at lower level to get scum out. Scum is sometimes entering the Dual Media
Filters (DMFs) negatively affecting its performance since the scum carries media away
and/or blinds the filter media reducing filtration capacity.
16. The City has not frequently taken the two Round Secondary Clarifiers (Nos. 5 and 6) out
of service since they were constructed in 1988 (refer to Appendices C and D for K/J’s
assessment and recommended retrofits). Weirs appear to be relatively level across the
round clarifiers. Bird droppings and sea air appear to be negatively affecting the metal
surfaces as is evident on the control panels and there is concern about the impact to the
rake arms. The slide gate has visible corrosion. The structures require paint and corrosion
protection for the motors and bull gear to extend their useful life.
17. The Round Secondary Clarifier electrical room contains MCC and needs new lighting. The
existing VFDs (Allen Bradley) replaced older ones (Eaton) that failed frequently. The
isolation transformers were disconnected after replacing the VFDs since the City said they
were too noisy.
18. The Round Secondary Clarifiers do not experience the same problems as the Square
Secondary Clarifiers – the energy dissipation sidewall depth is better (refer to Appendices
C and D for K/J’s assessment and recommended retrofits).
19. Return Activated Sludge (RAS) pumps 1, 2, and 4 are located indoors and appear to be in
good working condition. The pumps have minimal corrosion and are in much better
condition than equipment located outdoors.
5.2.5 Tertiary Treatment
1. The DMFs were originally constructed in 1980 and are functional (refer to Appendices C
and D for K/J’s assessment and recommended retrofits), but have since undergone some
modifications to the controls.
2. A 500-kW portable generator is outside the DMFs and needs to be replaced with a
permanent generator having automatic transfer switches.
3. Refer to Appendices C and D for K/J’s assessment and recommended retrofits for the
DMF Equipment Building.
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4. The DMFs had high efficiency motors installed in 1980. While the pumps are functional,
they are at the end of their useful life and piping is thin. Backwash supply water header is
24 inches. End cap blew out. Coating is coal tar epoxy. Penetrations project has been done
– there may be more pipe penetration issues at floor level. Piping needs to be rehabilitated
with an FRP pipe wrap.
5. Energy consumption is a concern at the DMFs. The RWQCP wants to reduce the Total
Suspended Solids (TSS) coming into the DMFs since the DMF media is clogging,
requiring backwash every 24 hours to achieve a TSS of 1 to 2 parts per million (ppm) out
of the DMFs and an Ultraviolet Transmittance (UVT) of 65-69 percent. A filter run time of
36 hours is a targeted goal.
5.2.6 Disinfection / Recycled Water
1. The UV disinfection system is new and started running in 2009, and is in excellent
condition.
2. The former and now abandoned Chlorine Contact Tank may be rehabilitated and retrofitted
with a cover in order to increase recycled water storage capacity and reduce algal growth
in the retrofitted storage tank.
3. While the Chlorine Contact Tank and Recycled Water Filters are functional, both facilities
were repurposed to function as they are now. Both facilities are nearing the end of their
useful lives, the RWQCP staff should consider relocating and replacing each facility to
accommodate future changes to RWQCP process/building layout.
4. Refer to Appendices C and D for K/J’s assessment and recommended retrofits for the
Water Reclamation Filters structure.
5. Refer to Appendices C and D for K/J’s assessment and recommended retrofits for the
Water Reclamation Tank.
5.2.7 Solids Treatment and Handling
1. The four Thickeners (Nos. 1 through 4) were originally constructed in 1972 and were
rehabilitated in the 1990s. Thickener No. 4 was never fully functional due to hydraulic
issues; therefore, its mechanical equipment was removed in 2002. The other units (Nos. 1
through 3) work well; however, reconditioning is required due to corrosion (refer to
Appendices C and D for K/J’s assessment and recommended retrofits).
2. The sludge muffin monsters are working well, but need to be rehabilitated to maintain
reliability.
3. Scum Pit A is clogged with debris and needs significant cleaning. Scum Pit B is well
maintained, but the concrete is showing some corrosion.
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4. The sludge feed pumps are located in the same room as some of the MCCs and require
considerable maintenance. Need to consider replacing the sludge feed pumps and
relocating them to a new pump room in the next 5 to 10 years.
5. The three mixed sludge pumps (installed in 1980) are nearing the end of their useful life,
but appear to be working well with some maintenance.
6. The Sludge Blend Tank appears to be functioning properly (refer to Appendices C and D
for K/J’s assessment and recommended retrofits). It is recommended to have a structural
assessment to better understand its remaining useful life.
7. The City wants a VFD for the Induced Draft (ID) fans as the motors consistently run at 100
percent and the furnace draft is controlled by the way of a damper valve, potentially
wasting energy. As part of adding a VFD, the fan would need to be replaced and the
controls system modified to accommodate a switch from damper control to VFD control.
8. Separate reports present results of the seismic analyses for the existing Multiple Hearth
Furnaces (MHFs) and the Incinerator Building – they are entitled “Incinerators - Seismic
Evaluation Technical Memorandum” (Appendix F) and the “Seismic Evaluation of the
Piles Supporting the Incinerator and Operations Buildings Technical Memorandum”
(Appendix G), respectively. The latter of the two technical memorandums found the piles
of the Incinerator Building are seismically deficient and need to be retrofitted.
9. The two MHFs were originally constructed in 1972 (are now 40 years old) and are one of
only two incineration operations at a wastewater treatment plant in California. They are of
an older generation and are not a good candidate for producing renewable bioenergy.
10. There is visible corrosion within the hearths of each MHF. The controls have been
upgraded and each MHF is regularly rehabilitated (i.e., the RWQCP rotates use of them
each year – while one is in operation for the year, the other is being cleaned and
rehabilitated). They need more complex repairs as they age (steel is rusting, bricks are
shifting, etc.).
11. While the MHFs could go offline for repairs due to an earthquake for example, temporarily
hauling the solids to a landfill is complicated.
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Figure 5.5 Corrosion Inside the Hearths of the Multiple Hearth Furnaces
12. The MHF’s original manufacturer (BSP Thermal Systems) is supporting manufacture of
replacement parts such as specialty refractory bricks, rabble arms and teeth, furnace doors,
center shaft lute caps, and bearings for the older sewage sludge MHFs around the U.S.
Multiple hearth furnaces continue to be used for industrial applications, but are no longer
designed for sewage sludge applications. A critical part of maintenance is manufacturer
support of legacy products. BSP Thermal Systems has indicated that they plan to remain in
business and support parts replacement. If BSP Thermal Systems was sold or went out of
business, engineering records would be transferred to a new owner and the cast iron parts
and brick designs would continue. Should this support system change, the furnaces would
need to be retired as soon as possible.
13. The MHFs produce a hazardous waste ash due to a high level of soluble copper, requiring
that it be hauled a long distance to a hazardous waste landfill.
14. The Ash Storage System is in good condition (refer to Appendices C and D for K/J’s
assessment and recommended retrofits).
15. The two Air Pollution Control Vessels (Nos. 1 and 2) appear to be functioning well (refer
to Appendices C and D for K/J’s assessment and recommended retrofits). However, U.S.
EPA air regulations are heading in a direction where compliance may not be possible. New
air pollution control equipment is costly and could be on an implementation timeline that
the RWQCP cannot meet.
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5.2.8 General
1. K/J found that loads transferred to the Operations Building piles during a design seismic
event may exceed the allowable axial and horizontal pile load capacities recommended by
ENGEO, Inc. by as much as 30 percent. Refer to Appendix G (Seismic Evaluation of the
Piles Supporting the Incinerator and Operations Buildings Technical Memorandum) for the
detailed analysis.
2. K/J found that the soil bearing pressure beneath a footing for one of the Maintenance and
Warehouse Facility’s lateral force resisting steel frames would exceed the allowable
pressure recommended by Treadwell & Rollo. It was also determined that the Mezzanine
Level Storage Platform located in the Maintenance and Warehouse Facility needed to be
bolted to the floor and the existing Platform cross-bracing system needed to be improved
in order to withstand a design seismic event.
3. There are seven Generators onsite at RWQCP (two inside the NPP, one north of the UV
structure, one south of the IPS, one northeast of the Ash Storage System, one adjacent to
Secondary Clarifier No. 1, and one near the southwest corner of the DMFs) – the older
generators do not work with transfer switches due to the age of the MCC and the
Adjustable Frequency Drives (AFDs) and VFDs at the NPP. The RWQCP wants to pair
VFDs with any new motor. The transfer switch at the NPP needs to be addressed as part of
the generator project (i.e., Arc Flash study).
4. In general, MCCs have not been replaced. The City wants to consider Smart MCCs.
5. In the 1970s, conductors were repaired and in 1988 a short-circuiting study was performed
on the conduits. However, no short circuiting study was conducted prior to or following
the construction of the UV system in 2010. A short circuit study needs to be performed to
ensure the equipment is adequately rated and can safely interrupt the worst-case fault.
6. The OPP, NPP, DMF, and Incinerator Buildings (i.e., areas of lift pumps having 2-inch
conduit) have conduit showing with visible corrosion. The RWQCP needs to replace the
conduit and wants to modify their specifications for the conduit to have a plastic cover.
7. Spiral weld steel and electric resistance welded (ERW) piping is not the standard wall
thickness - too thin.
8. Plant staff stated that the 12-kilovolt (kV) cable may not be in good condition and needs to
be assessed to determine if it needs to be replaced.
9. Plant air – need to check for leaks, may need to modify air storage and blowers. Largest
use of plant air is to transfer ash. Plant air accounts for approximately three percent of total
power use plant-wide.
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5.3 OCCUPIED BUILDING DEFICIENCIES
The Administration Building, Operations Building, and Maintenance Building and Warehouse
are the occupied buildings on the RWQCP site. This section documents each building’s
deficiencies and needs as determined by LRFP project team.
5.3.1 Administration Building
The Administration Building was originally constructed in 1975 as a recycled water process and
pumping facility with two deep open top rectangular tanks and one open top rectangular
equipment pit. During the three remodeling projects (in 1992, 1995, and 1998), administrative
offices were constructed over the open top equipment pit. The recycled water pumps are still in
the basement of the building. The building was originally constructed of cast-in-place reinforced
concrete roof, walls, and floors. The heavy concrete basement floor slab and walls are supported
on concrete piles. Each remodeling effort added office spaces with wood framed structures
constructed over the original open top equipment pit.
Based on K/J’s FCA, there was visible deterioration and a potential structural deficiency with the
wood framing at the anchorage to wall making it subject to cross-grain bending under seismic
loads. In general, the administration building is very cramped and inadequate for the number of
people utilizing the space.
Staff has identified the following issues and elements to be addressed for the Administration
facilities:
Need an office building for more people and uses (i.e., 35 people, a laboratory,
conference rooms, etc.).
There is no clear plant entrance/public access area for visitors and tour groups. Visitors
frequently go to the operations building instead of the administration building.
There is inadequate parking for visitors, especially educational tour groups.
Need to consider the building’s architecture, vegetation buffer, etc., especially if the
Administration Building is relocated to along Embarcadero Road.
Supervisors need walled-in offices for private conversations.
5.3.2 Maintenance Building and Warehouse
The maintenance building and warehouse structure was originally constructed in 1986. The
building is a steel-framed structure supported by a concrete slab-on-grade foundation with
continuous interior and exterior spread footings. Maintenance and storage areas are located on
the southeast side of the building and office spaces are located on the northwest side. While the
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structure has exceeded its original useful life, it is in relatively good condition with few visible
signs of damage or deterioration. Only one calculated structural deficiency was noted for this
structure in K/J’s FCA. Re-purposing has resulted in lack of maintenance and warehouse space.
Supervisors lack walled-in offices for private conversations. In general, the space utilization
could be improved if office space was provided elsewhere. Additional storage and warehouse
space is needed at the plant due to the increased need to store spare parts as a result of plant
expansions and discharge permit requirements to maintain the plant in a state of “operational
readiness.”
5.3.3 Operations Building
The operations building was originally constructed in 1972 and houses laboratory testing stations
and equipment, offices, a large lunchroom, and locker rooms. The building is constructed of
reinforced concrete supported by a structural slab-on-grade foundation with pier and grade
beams. As discussed in Appendix G, this building’s foundation piles are inadequate to resist
seismic loading and a structural retrofit is required. Additionally, staff has identified the
following issues:
The existing laboratory space and layout within the Operations Building is deficient given
current testing space requirements and number of laboratory staff.
Having a laboratory on the second floor of a building with no elevator causes issues for the
frequent deliveries required.
Laboratory needs to be relocated and expanded.
The lunch and training room should be combined.
Additional locker room space is needed.
The building should be retrofitted with dual-paned windows.
Supervisors require walled-in offices for private conversations.
5.4 OVERALL PLANT SPATIAL CONSIDERATIONS
Prior to, during, and following the condition assessment and project alternatives development,
meetings were held with plant staff to discuss the needs for both occupied/unoccupied and
process related structures. Because the RWQCP site is very limited in spatial extent, it was
important that the needs for staff and process operations were well documented and considered
throughout the LRFP process. This section describes the needs that were identified while
considering existing structural deficiencies and future needs.
The overall spatial considerations will be discussed starting from the north to the south end of the
plant site.
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In general, as permanent structures are being considered for the LRFP, the major pipelines within
the RWQCP site and Outfall Box need to be avoided, including the:
72-inch diameter joint interceptor sewer line
60-inch diameter line to the PSTs
72-inch diameter emergency bypass line
60-inch diameter line from Secondary Clarifiers to DMFs
60-inch diameter DMF bypass line
Two 96-inch diameter effluent lines (with the exception of implementing a new effluent
line)
The Administration Building needs to be replaced in the near term and the RWQCP staff prefers
that it be relocated closer to the Maintenance Building (i.e., north side of the RWQCP site) and
toward the periphery of the site. Therefore, space needs to be preserved for a two-story building
and parking lot west of the Maintenance Building and south of the outfall box. Alternative
locations include a commercial site nearby the RWQCP. Another potential location is adding to
the Operations Building and modifying the existing moat feature. Each option has tradeoffs.
Due to the Palo Alto Airport runway path, the buffer lands located on the east side of the plant
should not be utilized for any occupied space (per Airport Land Use Commission Guidelines
issued by Santa Clara County). Use of this area for unoccupied facilities such as additional
warehouse space or unit processes would be acceptable. Additional Warehouse space has been
identified for the area behind the existing Maintenance Building/Warehouse space.
The area between the Maintenance Building and the UV Disinfection process is limited and the
plant staff prefers to remove the parking spaces from that area to allow solids hauling trucks to
use the western entrance, if necessary. The existing Oil Storage Building can also be relocated as
necessary. However, the Chemical Storage area needs to remain in its location.
The structures (tanks and buildings) southwest of the Meter Pit and Chemical Storage area can
be removed and relocated as necessary to clean up the site. Specifically, the buildings that can be
removed or relocated include the Ops Training Building, Oil Storage Building, Recycled Water
Filters, Recycled Water Chlorine Contact Basin, Recycled Water Storage Tanks 1, 2, and 3,
Administration Building, and Utilities Department Transmission group field offices.
The Household Hazardous Waste (HHW) Building is currently sited southwest of the Operations
Building. The RWQCP staff needs to consider that it needs to be staffed and the use of it will
increase with the closing of the recycling center.
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The RWQCP staff prefers that unit process structures be placed toward the center of the site, if
possible. The solids treatment alternatives layouts are to be placed in the area southeast of the
existing incineration process (i.e., northwest of the PSTs). If the preferred liquids treatment
alternatives layouts require too much area onsite, the RWQCP staff will consider using a nearby
building for a new Laboratory and Environmental Services Building. It is assumed that the
existing commercial building would need to be demolished and rebuilt to satisfy the needs of the
new Laboratory and Environmental Services Building.
Space needs to be allocated for several structures common to all project alternatives, a new
Headworks building, new Recycled Water Filters, new Chlorine Contact Tank, and new
Recycled Water Storage in the northwest corner of the RWQCP site. Space also needs to be
allocated for the potential addition of an ozonation process (i.e., liquid oxygen tanks and an
ozone dissipation chamber) to meet potential future regulations.
The new facilities requirements and layouts will be discussed in more detail in the subsequent
chapters of this LRFP Report, specifically in Chapter 7 (Solids Treatment Alternatives
Development and Screening) and Chapter 8 (Liquid Treatment Alternatives Development and
Screening).
5.5 INFLUENT JOINT INTERCEPTOR SEWER ANALYSIS
The 72-inch diameter Joint Interceptor Sewer (Joint Interceptor) was built in 1972. The trunk
sewer receives wastewater from the Cities of Palo Alto, Mountain View (including flow from
Moffett Field) and Los Altos, as well as the Town of Los Altos Hills. East Palo Alto Sanitary
District (EPASD) and Stanford University do not discharge into this trunk sewer. The land above
the interceptor consists of primarily wetlands and parkland, varies from 3 to 18 feet in depth, and
has limited construction access.
The last inspection and cleaning of the Joint Interceptor took place in 2006. As part of this
LRFP, a separate analysis was performed on the interceptor to determine repair and replacement
needs. The complete details and findings of this analysis are provided in Appendix H (Technical
Memorandum No. 2: Sewer Interceptor Rehabilitation and Replacement Study). Major findings
are that the interceptor and manholes are deteriorated in sections and in need of repair. The
analysis includes evaluation of options for repair and replacement of the interceptor. Major
recommendations from this analysis are discussed below.
If the RWQCP staff decides that rehabilitation of the interceptor is the preferred alternative, then
cleaning and spot repairs should be made to allow for either spiral wound lining (SPR) or cured-
in-place pipe (CIPP) rehabilitation. If the SPR or CIPP rehabilitation method is selected, the
interceptor would require bypass pumping, cleaning, repair, and CCTV prior to construction.
This work could be done on a segment-by-segment basis. The information that can be obtained
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from a CCTV inspection of a sewer is only as good as the quality of the image. It is
recommended that the next CCTV inspection follow Pipeline Assessment and Certification
Program (PACP) guidelines.:
1. Use a camera lens with a minimum 65-degree viewing angle with either automatic or
remote focus and iris controls.
2. Camera lighting shall be sufficient for use with color inspection cameras with a minimum
of 1,000,000 candlepower lighting in the 3,200 degree Kelvin range.
3. The camera should be pulled through the interceptor not faster than 30 feet per minute.
4. Flow depths should be less than 20 percent at the time of inspection.
5. CCTV Operator should be certified by either NAASCO/PACP or WrC.
6. Sewer condition should be classified following the PACP guidelines.
7. CCTV footage should be labeled on screen by both manhole location and distance from
manhole along pipe.
A 3-D laser scan could be performed to provide an accurate description of the pipe geometry
above the water level. Internal diameter and deflection graphs are used to determine pipe-wall
material loss/gain or deformation at a given location. Pipe cross sections obtained from high
resolution scans are used to determine pipe ovality. This can help the City prioritize which
segments require replacement.
In 2006, approximately 119 vertical feet of 48-inch manholes and the influent box were
rehabilitated using PERMACAST MS with Con Shield liquid admixture and an epoxy coating of
Cor-GARD epoxy. Manholes were high pressure washed, joint sealed, and all voids sealed.
Exact locations of which manholes were rehabilitated were not available. A manhole condition
assessment is recommended to document what was completed and what needs to be done. This
will allow the RWQCP to include any rehabilitation or replacement required in the future
interceptor work. Significant leakage at several manholes can be seen on the CCTV footage,
making this a priority.
A collection system model for all the contributing areas into the interceptor should be developed
to determine the projected flows during wet weather. This can then be used to determine the
needed capacity of the sewer and whether options that reduce the inner diameter are viable.
5.6 OUTFALL CAPACITY ANALYSIS
The Palo Alto RWQCP relies on two existing outfalls for effluent discharge: one 54-inch
diameter reinforced concrete pipe (RCP) that is currently in use and one 36-inch diameter RCP
could be used during emergency peak flows. The existing 54-inch diameter outfall was identified
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in the 1983 Plant Capacity Study by WWi Consulting Engineers as potentially being capacity
constrained without the use of the supplemental emergency outfall. The Outfall Capacity
Analysis TM No. 3 (Appendix I) evaluates the capacity of the existing 54-inch diameter outfall
to convey existing and future peak wet weather flows up to 80 million mgd at all current tide
levels. It also analyzes the capacity of the outfall to handle 80 mgd flow under various global
climate change scenarios related to sea/tide level rise. The findings of this study were that the 54-
inch outfall capacity is not adequate to pass the peak wet weather flow of 80 mgd on its own.
Joint use of the 36-inch outfall would be needed during low tide; however, their combined
capacity during high tide is not adequate. Therefore, under the existing and 2050 conditions,
additional pumping capacity is required in order for the RWQCP to discharge 80 mgd through
the 54-inch and 36-inch diameter outfalls.
The projected ranges of sea level rise presented in the TM should be considered a minimum for
planning purposes. As the U.S. Army Corps of Engineers’ (ACE) South San Francisco Bay
Shoreline Study progresses, it is recommended that efforts be taken to coordinate results,
specifically with respect to any proposed projects and funding mechanisms. It is also
recommended that the projected range of sea level rise be evaluated regularly (at least every five
years), as models are improving and producing more accurate results.
The RWQCP site needs to be protected from flooding. Continued coordination with the U.S.
ACE South San Francisco Bay Shoreline Study and FEMA mapping is recommended. The City
should conduct a hydrology study to project water levels around the RWQCP site and to confirm
levee elevations surrounding the plant. The FEMA flood insurance study for the Palo Alto area
concluded that an Army Corps of Engineers approved sea wall system needs to have a minimum
height of 10 feet above mean sea level. Rebuilding the levees to meet future sea level rise would
protect the plant from future flooding and should be investigated further. It is recommended that
implementation and operations and maintenance costs be estimated as well.
5.7 PLANT PIPELINE ANALYSIS
Existing plant pipeline length between buildings and tanks, diameter, material and year
constructed were estimated based on existing drawings. In some cases pipeline material was not
shown on the drawings in the year it was built, and an educated guess was made based on later
drawings or similar use. A summary of the existing plant pipeline material types found within the
RWQCP site boundary and their original life expectancy is shown in Table 5.2.
The estimated remaining useful life (RUL) was calculated for each pipe for the year 2015 based
on the expected life by pipe material and pipe age. Based on pipe age, it was calculated whether
a pipeline would need replacement prior to year 2042. If the pipe required replacement, it was
replaced in kind if the material is still commonly used today. If a pipe material was used that is
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not available, a typical material for the pipe contents was assumed. Replacement cost was then
calculated based on a cost per linear foot ($/LF) basis shown in Table 5.3.
Table 5.2 Summary of Existing Pipeline Material Types
Pipe Material Expected Life (years)
Table 5.3 Pipe Replacement Unit Costs
Pipe Diameter
Ductile Iron
Pipe
Replacement
PVC
Replacement
Pipe
CML&C Steel
Pipe
Replacement
HDPE Pipe
Replacement
(inches) ($/LF)($/LF)($/LF)($/LF)
The following are the assumptions used for developing the replacement cost estimates for the
pipelines:
Only pipelines within the RWQCP property limits are included.
Chemical feed piping and water piping have not been included.
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Plant piping was defined as buried pipe located outside of buildings and tanks.
Recycled water pipelines with diameters smaller than 12 inches will be replaced with PVC
pipe.
Recycled water pipelines with diameters equal to or larger than 12 inches will be replaced
with cement mortar lined and coated steel pipe.
Acrylonitrile Butadiene Styrene (ABS) natural gas pipe will be replaced with high-density
polyethylene (HDPE) pipe. The Utilities Department already change the ABS pipe
throughout the RWQCP to HDPE.
AB Corrugated Pipe will be replaced with cement mortar lined and coated steel pipe.
Pipe depth is assumed to be 12 feet below ground.
Vertical shoring is required.
Pavement replaced is assumed to be 3-inch thick asphalt concrete (AC) on 6-inch thick
aggregate base course (ABC).
Trench width is assumed to be the pipeline outer diameter plus 8 inches on each side for
pipes with 30-inch diameters or less, and pipeline outer diameter plus 12 inches on each
side for pipes having greater than 30-inch diameters.
Pipeline bed depth is 4 inches for pipes with 10-inch outer diameters or less, and 6 inches
for pipes with 12-inch outer diameters or greater.
No corrosion protection is included.
Table 5.4 illustrates a summary of the plant pipeline analysis.
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5.8 IMPROVED OPERATIONS AND ENERGY EFFICIENCY
This section summarizes current or planned projects led by the plant staff for improving
operations and overall energy efficiency at the RWQCP.
5.8.1 Source Control for Energy Savings
The RWQCP seeks to reduce energy consumption through source control by supporting indoor
water use conservation with water agencies that send wastewater to the plant. The following
water agencies participate:
Purissima Hills Water District (uses Los Altos Hills wastewater system)
CalWater (uses Los Altos/East Palo Alto Sanitary District wastewater system)
Mountain View (uses Mountain View wastewater system)
Stanford University (uses Stanford University’s wastewater system)
City of Palo Alto Utilities (uses Palo Alto’s wastewater system)
The RWQCP also supports wastewater collection agencies in their efforts to develop inflow and
infiltration reduction strategies including groundwater pumping, source detection, tracking
illegal connections, lateral maintenance and replacement policies, CCTV surveillance, suspect
lateral programs, and mainline/lateral sewer rehabilitation
5.8.2 Miscellaneous Energy Saving Projects
The following list of potential energy savings projects were identified by RWQCP staff and have
already been identified and scheduled to be complete in the near future.
1. Turblex control system improvement for Blowers 1, 3, & 5 (completed January 2012)
2. Redesign the flare system to maximize landfill gas use (construction in 2013)
3. Submetering at each load center (construction in 2012)
The projects listed below are planned for some time in the next 10 years.
1. Develop and display cost data on a human-machine interface (HMI) screen for commodity,
electric loads, and gas loads.
2. Motor replacement should occur in groups based on age, reliability, efficiency gains, and
other criteria relevant to plant operations. Most existing large motors have efficiencies that
are near or higher than premium efficiency motors.
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3. Install variable frequency drive (VFD) motors in the DMF backwash supply pumps, the
recycled water backwash supply pump, and the induced draft fans (ID fan) at the
incinerators. Identify existing less efficient (or aging) VFDs and replace them with new
VFDs.
4. New buildings with over 5,000 square feet are to satisfy Leadership in Energy and
Environmental Design (LEED) silver certification, consistent with the City’s 2007 Climate
Protection Plan. Renovated buildings with over 5,000 square feet are to be evaluated by an
appointed Green Building professional. Renovated buildings with less than 5,000 square
feet should use a LEED or equivalent checklist as a guideline to enhance Green Building
features.
5. Installation of “cool roofs” as roofs of conditioned air spaces need to be replaced.
6. Just prior to 2019, consider ceramic disks (versus the existing ceramic domes) for next fine
bubble ceramic diffuser replacement project.
5.8.3 2012 Tertiary Upgrade Project
The Tertiary Upgrade Project is planned for 2013 and consists of the following major elements.
Clarifiers (Nos. 5 and 6) rehabilitation of weir and launder cleaning system, as well as
update and automation of scum system.
Clarifiers (Nos. 1, 2, 3, and 4) rehabilitation
–Installation of properly spaced weir notches for flow balancing and improved solids
removal to account for square clarifier shape .
–Rehabilitation of secondary effluent channel scum trough and pumping system.
–Installation of isolation slide gates on effluent launders not in service.
–Potentially filling in the corners of the square clarifiers.
Replacement of the DMF surface wash system with an air wash system. Consideration of
underdrain panel with integral airwash gravel replacement and additional media
installation.
DMF media replacement pilot with a larger effective size media.
DMF backwash waste valve replacement (leaking valves).
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Chapter 6
REGULATORY REQUIREMENTS
The purpose of this chapter is to summarize the existing discharge permit requirements and
consider potential future regulatory requirements that may affect the Palo Alto Regional Water
Quality Control Plant (RWQCP) discharge to the South San Francisco Bay and Matadero Creek.
6.1 SUMMARY OF THE EXISTING NPDES PERMIT
Under the Clean Water Act (CWA), the Environmental Protection Agency (EPA) regulates the
RWQCP’s effluent discharges through the issuance of National Pollutant Discharge Elimination
System (NPDES) permits. The NPDES permitting program for the San Francisco Bay drainage
basin has been delegated by EPA to the San Francisco Bay Regional Water Quality Control
Board (Regional Water Board). The RWQCP’s current permit – NPDES Permit No.
CA0037834, Order No. R2 2009-0032 – was adopted on April 8, 2009 and expires on May 31,
2014. The City of Palo Alto owns and operates the RWQCP and is the discharger subject to the
waste requirements set forth in the permit. The NPDES permit is included in Appendix J.
The RWQCP is permitted for an average dry weather flow (ADWF) design capacity of 39
million gallons per day (mgd) and a peak wet weather flow (PWWF) design capacity of 80 mgd.
The ADWF capacity provides tertiary treatment and the PWWF capacity provides secondary
treatment.
The RWQCP discharges to two receiving waters: South San Francisco Bay and Matadero Creek.
Approximately 95 percent of the treated wastewater is discharged to South San Francisco Bay
through an unnamed, manmade channel that is tributary to the Bay. Approximately 5 percent of
the treated wastewater is discharged to the Emily Renzel Marsh Pond where it flows through a
controlled outfall to Matadero Creek. The Emily Renzel Marsh Pond is a reclamation project
initiated by the City of Palo Alto to restore natural habitat that has been cut off from natural
freshwater and saltwater flows. The Emily Renzel Marsh Pond is not a water of the State or the
U.S. because its water levels are exclusively maintained by the RWQCP discharge and the pond
has a controlled outfall to Matadero Creek. As a result, Matadero Creek is considered to be the
receiving water for all flows discharged to the pond. Both Matadero Creek and the unnamed
manmade channel that is tributary to South San Francisco Bay are waters of the U.S.
The following sections summarize the City’s discharge permit requirements.
6.1.1 Permit Effluent Limits
Table 6.1 summarizes the current NPDES permit effluent limitations. In addition to the limits in
the table, the average monthly removal for biochemical oxygen demand (BOD) and total
suspended solids (TSS) must be at least 85 percent by concentration. The permit also contains
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limits for acute and chronic toxicity. The RWQCP has an excellent track record of meeting these
permit limits.
Table 6.1 Effluent Limits in 2009 NPDES Permit
(1)
Constituent Units(2)Average
Monthly
Maximum
Daily
Instantaneous
Min Max
°
µ
6.1.1.1
The RWQCP must also comply with mercury effluents limits set in the San Francisco Bay
Mercury Watershed Permit (NPDES Permit No. CA0038849, Order No. R2-2007-0077). This
permit sets mercury effluent limits for all discharges to the San Francisco Bay and its tributaries.
The current and future mercury limits for the RWQCP are included in Table 6.2.
Mercury Effluent Limits
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Table 6.2 Mercury Effluent Limits in San Francisco Bay Mercury Watershed
Permit(1)
Discharger
Average
Annual
Effluent
Limit
(kg/yr)
Effective in
2018 Average
Annual
Effluent Limit
(kg/yr)
Effective in
2028 Average
Annual
Effluent Limit
(kg/yr)
Average
Monthly
Effluent Limit
(µg/yr)
Average
Weekly
Effluent
Limit (µg/yr)
The permit requires the permitted dischargers to report mercury mass loads and source control
activities on an annual basis. In 2010, the RWQCP reported an estimated annual mercury mass
emission of 0.0633 kg/yr, which is well under the average annual effluent limit of 0.38 kg/yr.
They also reported that the following mercury source control projects were completed or
underway (2010 Mercury Watershed Permit Group Report, RMC Water and Environment):
Dental Amalgam Program
Fluorescent Light Recycling
Household Hazardous Waste Collection
Public Outreach/Education
Thermometer and/or Thermostat Exchange
Vehicle Service Facilities
6.1.1.2
When the NPDES permit was issued in 2009, the RWQCP was not immediately able to comply
with the dioxin and furan toxic equivalents (dioxin-TEQ) limit and was issued interim effluent
limits listed in Table 6.1. In February 2010, a blanket permit amendment for dioxin and furan
compounds was issued for dischargers in the San Francisco Bay area (Order No. R2-2010-0054).
The purpose of the amendment was to establish consistent standard requirements for all NPDES
wastewater permits and to revise the method for calculating dioxin-TEQ for permits that require
monitoring and reporting of dioxin-TEQ. Under the new method, all San Francisco Bay
dischargers, including the RWQCP are in compliance with their dioxin-TEQ permit limits.
Dioxin-TEQ Effluent Limits
6.1.1.3
The RWQCP must also comply with PCB waste discharge effluent limits set in the amendment
to the San Francisco Bay Mercury Watershed Permit (Order No. R2-2011-0012). This permit
sets PCB effluent limits for a subset of discharges to the San Francisco Bay and its tributaries.
The current PCB limits for the RWQCP are included in Table 6.3.
PCB Effluent Limitations
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Table 6.3 PCB Effluent Limits in San Francisco Bay Mercury and PCB Watershed
Permit
Discharger
Average Monthly Effluent
Limit (ug/L)
Maximum Daily Effluent
Limit (ug./L)
The permit requires the RWQCP to identify controllable sources of PCBs to its treatment system
by February 28, 2012. The controllable sources consist of PCB contributions to wastewater from
industrial equipment and PCB contributions to wastewater from buildings with PCB-containing
sealants that are scheduled for remodeling or demolition and identified as pilot projects required
by Provision C.12.b of the Municipal Regional Stormwater Permit (Order No. R2-2009-0074).
The RWQCP shall submit the results of this evaluation, including any proposed control actions
with an implementation schedule, in its annual pollution prevention reports.
6.1.2 Other Permit Provisions
Other provisions in the permit include the following:
Monitoring and reporting of selected constituents.
Participating in an ambient background receiving water study.
Investigating and studying sources of consistent toxicity and how they can be controlled or
reduced.
Conducting a receiving water ammonia characterization study.
Optional investigation of mass offset programs for 303(d)-listed pollutants.
Optional study of near-field, site-specific translators for chromium, zinc, and lead.
Pollution prevention/minimization program and reporting.
Evaluation and status reports for the wastewater facilities, the operations and maintenance
manual, the reliability of the wastewater facilities, and the facility contingency plan.
Implementation and enforcement of a pretreatment program.
Appropriate management of all biosolids.
Implementation of a sewer system management plan for operation and maintenance of the
collection system and mitigation of sanitary sewer overflows.
Implementation of action plans to control copper and cyanide discharges.
Continued implementation of existing reclamation programs.
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6.1.3 Wet Weather Discharges
The RWQCP wastewater treatment processes include screening, grit removal, primary
sedimentation, fixed film reactors, activated sludge treatment, secondary clarification, dual
media filtration, and UV disinfection. The fixed film reactors and dual media filters have a
design capacity of approximately 40 mgd.
During wet weather events when the influent flow exceeds 40 mgd, the fixed film reactors and
dual media filters treat the first 40 mgd. At the fixed film reactors, flows in excess of 40 mgd are
routed around the fixed film reactors, blended with fixed film reactor effluent and routed to the
activated sludge process. At the dual media filters, flows in excess of 40 mgd are routed around
the filters, blended with the filter effluent, and routed back to the disinfection process. The final
effluent produced during wet weather conditions is advanced secondary effluent. Bypass of the
fixed film reactors and dual media filters is only permitted when the primary effluent flow
exceeds the fixed film reactor capacity of 40 mgd, or when the effluent from the activated sludge
treatment process exceeds the dual media filter capacity of 40 mgd. The City must report all
incidents of blended effluent discharges and conduct additional monitoring of these discharges as
detailed in the permit.
6.1.4 Recycled Water
A portion of the tertiary treated effluent produced at the RWQCP undergoes additional filtration
and chlorination and is distributed for recycled water use throughout Palo Alto and the
surrounding area. Refer to Chapter 3 Section 3.6 for more information on recycled water use and
the City’s recycled water program.
The State Water Resources Control Board (SWRCB), the San Francisco Bay Regional Water
Board, and the California Department of Public Health (CDPH) have regulatory authority over
Palo Alto’s recycled water projects. The following sections summarize existing regulations that
govern recycled water systems. The CDPH is the primary state agency responsible for the
protection of public health, the regulation of drinking water, and the development of uniform
water recycling criteria appropriate to particular uses of water.1
Title 22 regulations define four types of recycled water, which is determined by the water
treatment level and total coliform, bacteria, and turbidity levels of the water. The four treatment
types of recycled water that are currently permitted by CDPH under Title 22 regulations are
summarized in Table 6.4. The RWQCP produces disinfected tertiary recycled water – the highest
quality of the four recycled water types.
1 The CDPH has promulgated regulatory criteria for recycled water use in Title 22, Division 4, Chapter 3, Section
60301 et seq., California Code of Regulations (Title 22). Additional information on recycled water regulations
and a link to Title 22 of the CCR can be found at:
http://www.cdph.ca.gov/CERTLIC/DRINKINGWATER/Pages/Lawbook.aspx.
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Table 6.4 Approved Uses of Recycled Water
Treatment Level Approved Uses
Total Coliform Standard
(median)
6.2 REGULATORY CONSIDERATIONS
This section provides insight into the existing and future regulatory considerations that may
impact the RWQCP’s discharges, biosolids production and disposal, and air emissions over the
course of the 50-year planning horizon. Because continued regulatory compliance is a major
objective of the LRFP, identifying future regulatory trends is critical for:
developing treatment scenarios and alternatives
planning for space requirements for future regulatory compliance
making budget considerations for major design/construction projects
In identifying future pollutants of concern (POCs), such as metals, nutrients, and/or pathogens,
the LRFP can be developed to include alternatives that are flexible and can be easily expanded or
upgraded to treat future POCs. For example, the LRFP may include an alternative that reserves
space in the site layout for membrane filtration, advanced oxidation, or an alternative
disinfection method that would provide treatment of future POCs.
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The following review of current environmental issues and regulatory developments describes the
overall anticipated trends that are important considerations in the planning process for future
wastewater facilities at the RWQCP.
6.2.1 Nutrient Removal
6.2.1.1
Nutrients, including nitrogen and phosphorus, are the leading cause of impairments to the
nation’s surface waters and as a result are receiving greater regulatory scrutiny regarding their
contribution to the overall quality of the nation’s receiving waters. Although appropriate
amounts of nutrients are vital for the health and proper functioning of waterbodies, excessive
nutrient concentrations can cause water quality degradation.
Nationwide
In November 2007, the National Resources Defense Council (NRDC) filed a petition with the
EPA to require that nutrient removal be included in the definition of secondary treatment. The
petition stated that “there are many [biological processes] which can achieve total phosphorus
levels of 1.0 milligram per liter (mg/L) as a monthly average, and a total nitrogen of 6 to 8 mg/L
as an annual average.” In response to the petition by NRDC, the National Association of Clean
Water Agencies (NACWA) wrote to the EPA in February 2008, September 2009, and June 2010
urging the EPA to deny the petition to modify the secondary treatment regulations for several
legal, technical, and political reasons including but not limited to: the potentially exorbitant cost
to publicly owned treatment works (POTWs), the impact on energy demands and greenhouse gas
emissions from additional treatment requirements and the inappropriateness of establishing
national limits for local and regional water quality issues.
Due to the scientific uncertainties associated with the development of numeric nutrient criteria
and the magnitude of the expected costs of compliance, nutrient water quality policies are very
controversial and have sparked several legal actions across the country. The State of Florida has
become the initial focus of environmental groups’ efforts to push the EPA to develop federal
numeric nutrient criteria to be imposed on the states. The EPA has agreed to a consent decree in
the environmental suit, and has made a determination that numeric nutrient standards are
necessary in Florida. Proposed criteria for total nitrogen and total phosphorus were released in
January 2010. This action is possibly precedential, and may result in environmental groups suing
the EPA to impose nutrient criteria in other areas of the country.
In 2011, EPA stated their goal is to assist with the development and adoption of numeric
nitrogen and phosphorus criteria, which will help states move toward establishing water quality
standards for nitrogen and phosphorus.
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6.2.1.2
The State Water Resources Control Board (SWRCB) intends to develop narrative nutrient
objectives, with numeric guidance to translate the narrative objectives. This numeric guidance
could include the Nutrient Numeric Endpoint (NNE) framework, which establishes numeric
endpoints based on the response of a water body to nutrient over-enrichment. The technical
foundation of the nutrient for freshwater lakes and streams has been developed and the SWRCB
is initiating public scoping and peer review. The SWRCB held a scoping meeting in October
2011 to seek input on content for a proposed Nutrient Numeric Endpoint (NNE) framework and
policy for inland surface waters. The SWRCB is working on similar projects to develop the
nutrient policies for enclosed bays and estuaries.
State of California
6.2.1.3
There is ongoing controversy concerning the impact of nutrient loadings to San Francisco Bay.
Although the impact of nutrient loadings to San Francisco Bay, including those from wastewater
treatment plant discharges, are not fully characterized or understood, it is known that nutrients do
play a key role in the phytoplankton ecology of the Bay. Currently, there are information gaps
about how the productivity rates of phytoplankton affect the higher organisms in the San
Francisco Bay food webs, and how nitrogen and phosphorus loadings affect the Bay’s beneficial
uses. Additionally, there is some evidence that the Bay, which has been historically light-limited
(i.e., sun-limited), is becoming nutrient-limited, and is therefore at risk of algal blooms. If future
research shows that nutrient loadings need to be reduced in San Francisco Bay, water quality
standards may be developed.
San Francisco Bay
In March 2012, the Regional Water Board issued a Water Code Section 13267 Technical Report
Order to Bay Area wastewater dischargers, including the RWQCP, requiring submittal of
information on nutrients in wastewater discharges. This order requires submission of historical
nutrient data. New data will be collected over a two-year period to aid in the understanding of
loadings and development of nutrient water quality objectives for the San Francisco Bay estuary.
In the current NPDES permit, the RWQCP is given an effluent limit for ammonia, but not for
total nitrogen or phosphorus. As the nutrient criteria for the Bay are developed, the RWQCP may
need to implement nutrient removal. Initial issuance of nutrient criteria in the San Francisco Bay
Region is expected to require nitrogen removal only. Issuance of phosphorus removal criteria is
possible but is expected to be much less imminent. If phosphorous removal were required, the
RWQCP would be well served by a meaningful discussion with the Regional Water Boards over
the lack of nutrient impairment in the receiving waters, and the fact that phosphorus removal can
have substantial impacts on energy consumption, greenhouse gas emissions, and production of
sludge from chemical co-precipitation.
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6.2.2 Microconstituents and Bioaccumulative Constituents
There is a trend towards increasing regulation of some inorganic constituents (e.g., ammonia),
emerging microconstituents, and bioaccumulative pollutants (e.g., mercury, polychlorinated
biphenyls (PCBs), and dioxins) in treated effluent discharges.
Microconstituents, also referred to as “contaminants of emerging concern” (CECs) by the EPA
Office of Water, are substances that have been detected in surface waters and the environment
and may potentially cause deleterious effects on aquatic life and the environment at relevant
concentrations. CECs include:
Persistent organic pollutants (POPs) such as polybrominated diphenyl ethers (PBDEs; used
in flame retardants, furniture foam, plastics, etc.) and other organic contaminants.
Pharmaceuticals and personal care products (PPCPs), including a wide suite of human
prescribed drugs, over-the-counter medications, bactericides, sunscreens, and synthetic
musks.
Veterinary medicines such as antimicrobials, antibiotics, anti-fungals, growth promoters
and hormones.
Endocrine-disrupting chemicals (EDCs), including synthetic estrogens and androgens,
naturally occurring estrogens, as well as many other compounds capable of modulating
normal hormonal functions and steroidal synthesis in aquatic organisms.
Nanomaterials such as carbon nanotubes or nano-scale particulate titanium dioxide.
Bioaccumulative constituents are substances that are taken up by organisms at faster rates than
the organisms can remove them. As a result, these constituents accumulate in the organism, the
food chain, and therefore in the environment and can remain there for long periods of time.
Mercury, PCBs, and dioxins are some bioaccumulative constituents that are being increasingly
regulated.
Monitoring requirements for these trace pollutants are increasing, including requirements to
analyze constituents at lower detection limits. Over the 50-year horizon of the LRFP, it is likely
that water quality criteria followed by new effluent limits will be added to permits. End-of-pipe
requirements, with no dilution allowance, will likely continue to be required for bioaccumulative
pollutants to the San Francisco Bay. Implementation of CEC standards is not expected to be
imminent as the EPA is currently focused on assessing the potential impact CECs have on the
environment and human health.
The RWQCP is considering options and alternatives that minimize sources of these pollutants
and remove them from the influent wastewater through increased source control and pollution
prevention programs, where practicable. However, many of these compounds of emerging
concern are ubiquitous, such as those found in PPCPs, and will be difficult to control at the
source. The RWQCP can work with legislative and industry representatives to reduce or restrict
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the use of certain products where feasible, and continue public outreach efforts to discourage
improper disposal of consumer products. The RWQCP has already installed ultraviolet (UV)
disinfection to reduce disinfection by-products.
Current pollution prevention efforts for mercury, PCBs, and dioxins may be close to the
maximum extent practicable (MEP) for the service area of the RWQCP.
6.2.3 Toxicity
The SWRCB is developing an updated approach to assess toxicity in wastewater and stormwater.
Toxicity testing is used to determine the toxic effects of pollutants in a water sample. A draft
policy issued in 2011 is entitled “Policy for Toxicity Assessment and Control” and is intended to
improve testing of water samples, as well as monitoring and reporting requirements, in a
consistent manner. The draft policy establishes or requires:
Numeric limits for chronic and acute toxicity for wastewater dischargers. (the new version
separates out stormwater - in attachment D)
Use of the Test of Significant Toxicity (TST) as the statistical method to determine
toxicity.
Single test failures triggering violation and accelerated monitoring.
RWQCB discretion on inclusion of acute toxicity in permits and evaluation of toxicity tests
using Instream Waste Concentration (IWC).
The SWRCB conducted an external peer review of the draft policy. The expert’s comments are
posted on the SWRCB’s website. Local organizations are currently negotiating compliance
provisions with the SWRCB. The revised policy may be released for public review in late May
to early June 2012, with possible adoption by the SWRCB in the fall of 2012.
6.2.4 Recycled Water
6.2.4.1
The SWRCB has recognized that a burdensome and inconsistent permitting process can impede
the implementation of recycled water projects. In response, the SWRCB adopted a Recycled
Water Policy (RW Policy) in 2009 to establish more uniform requirements for water recycling
throughout the State and to streamline the permit application process in most instances.
California State Recycled Water Policy
The RW Policy includes a mandate that the State increase the use of recycled water over 2002
levels by at least 200,000 acre-feet per year (AFY) by 2020 and by at least 300,000 AFY by
2030. It also includes goals for stormwater reuse, conservation and potable water offsets by
recycled water. The onus for achieving these mandates and goals is placed on both recycled
water purveyors and potential users.
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Absent unusual circumstances, the RW Policy puts forth that recycled water irrigation projects
that meet CDPH requirements, and other State or Local regulations, are to be adopted by
Regional Boards within 120 days. These streamlined projects will not be required to include a
monitoring component.
The RW Policy requires that salt/nutrient management plans for every basin in California be
developed and adopted as Basin Plan Amendments by 2015. These management plans will be
developed by local stakeholders and funded by the regulated community. Salt/nutrient
management plans have not yet been developed in the Palo Alto area. However, the Santa Clara
Valley Water District has provided research funds to the University of California to assess
appropriate treatment levels for recycled waters to be used for irrigation of landscapes
throughout Santa Clara County.
The RW Policy also specifies that “blue ribbon” advisory panels (Panels) be convened to guide
future actions with respect to monitoring CECs in both recycled water and inland and coastal
discharges. The two Panels of scientific experts will provide the State with recommendations for
addressing CEC issues related to recycled water applications and inland and coastal ecosystems.
The recommendations will be based on state-of-the-science information. The Southern California
Coastal Water Research Project (SCCWRP) will collate and synthesize the recommendations for
the SWRCB, CDPH, and the California Ocean Protection Council in two reports (one for
recycled water and one for ecosystems).
This is the third year of the three-year project. The first year focused on engaging the Panel in a
series of meetings to introduce and address the RW Policy and ambient environment issues. The
second year focused on formulation and documentation of Panel recommendations for the RW
Policy, and continued discussions with the inland and coastal systems Panel. The third year will
focus on formulation and documentation of the recommendations for inland and coastal
ecosystems.
The Panel completed their recycled water analysis and submitted a report of recommendations to
the SWRCB in June of 2010. The SWRCB is currently reviewing the recommendations. If any
regulations arise from new knowledge of risks associated with CECs, then projects will be given
compliance schedules. Regulations are not expected to arise in the imminent future.
The Draft Report for Monitoring Strategies of Chemical of Emerging Concern (CECs) in
California’s Aquatic Ecosystems was released in February 2012. In this draft document, a risk
based screening approach was taken to identify CECs with the greatest environmental risk.
Recommendations were made for monitoring of eleven compounds (17, beta-estradiol, estrone,
cis-androstenen-dione, bifenthrin, permethrin, chlorpyrifos, fipronil, ibuprofen, bisphenolA,
galaxolide, diclosfenac and triclosan) for freshwater discharges and another four compounds
(bifenthrin, permethrin, and PBDEs 47 and 99) were identified for monitoring for sediments in
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coastal embayments. The Panel urges the State to incorporate CEC monitoring into regional and
local monitoring programs and recommends a five-year re-evaluation.
6.2.4.2
Groundwater recharge with recycled water is the practice of spreading or injecting recycled
water into groundwater aquifers to augment groundwater supplies and to prevent salt-water
intrusion in coastal areas. While recycled water produced at the RWQCP is not currently being
used for groundwater recharge, it may be in the future as the City expands its recycled water
program.
Title 22 Draft Groundwater Recharge Reuse Regulations
Existing regulations and policies that pertain to groundwater recharge reuse include the Title 22
Draft Groundwater Recharge Reuse Regulations (November 2011), the Water Quality Control
Plan for the San Francisco Bay Basin (Basin Plan), and the California State Recycled Water
Policy. The following websites include additional information about these regulations and
policies:
Title 22 Draft Groundwater Recharge Reuse Regulations -
http://www.cdph.ca.gov/healthinfo/environhealth/water/Pages/Waterrecycling.aspx
Water Quality Control Plan (Basin Plan) for the San Francisco Bay Basin
http://www.waterboards.ca.gov/sanfranciscobay/basin_planning.shtml
The latest CDPH draft recharge reuse regulations (November 2011) set treatment standards
regarding pathogen microorganisms, nitrogen removal, total organic (TOC) carbon
concentrations, and maximum contaminant limits (MCLs) for other organic and inorganic
constituents. The Draft Groundwater Recharge Reuse Regulations (2011) have not been finalized
and adopted as part of the Title 22 regulations. The California Water Code was revised via SB
918 to require that the CDPH must adopt uniform water recycling criteria for groundwater
recharge by December 31, 2013.If the City begins to consider groundwater recharge alternatives
it will be important to track any changes in status or updates to the draft regulations.
6.2.4.3
Current Title 22 regulations allow filter loading “[a]t a rate that does not exceed 5 gallons per
minute per square foot of surface area in mono, dual or mixed media gravity, upflow or pressure
filtration systems.” While CDPH has recommended to the Regional Water Board to approve
increased loading rates for Monterey Regional, others will be approved on a case by case basis
(as an “Other Methods of Treatment” under Section 60320.5) until such time as an actual
regulatory change to Title 22 is made. However, CDPH has indicated that they do not have
any specific plans to allow greater than 5 gallons per minute per square foot as a general rule in
the near-term (per personal communication with Jeff Stone at CDPH on June 29, 2011).
Filter Loading Rates
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6.2.5 Land Application and Beneficial Use/Disposal of Biosolids
6.2.5.1
Solids generated at a wastewater treatment facility comprise screenings, grit, primary or raw
sludge (PS) and secondary or waste activated sludge (WAS). The screenings and grit are
typically dewatered and disposed in a landfill. The PS and WAS are typically described as solids
prior to stabilization.
Governing Regulations
Biosolids are defined as treated organic solid residuals resulting from the treatment of domestic
sewage at a wastewater treatment facility. Biosolids are a product with a high carbon content and
other beneficial use properties. Sludge generated by a wastewater treatment facility is defined as
biosolids once beneficial use criteria, as determined by compliance with the EPA’s 40 CFR 503
regulations, have been achieved through stabilization processes. Stabilization processes are
described as those that help reduce pathogens and reduce vector attraction.
Biosolids are classified by the 40 CFR 503 regulations as Class B or Class A, according to the
level of treatment to reduce pathogens. Biosolids must also meet vector attraction and metal
concentration limits. All biosolids must meet the Ceiling Concentration Limits for pollutants.
Class A biosolids that meet vector attraction criteria and the more stringent pollutant
concentration limits for heavy metals are called exceptional quality (EQ) biosolids. Table 6.5
summarizes the ceiling pollutant concentration limits described above and shows how the
RWQCP existing sludge compares. At this point, it appears that the RWQCP solids would meet
the EQ pollutant loading concentration limits.
6.2.5.1.1 Class B Biosolids
Class B biosolids can be produced through any of the defined Processes to Significantly Reduce
Pathogens (PSRP). The quantity and quality of the processed sludge and biosolids produced must
be monitored and recorded by each biosolids producer. Quality parameters include pathogen
reduction, vector attraction reduction, and inorganic content (i.e., heavy metals).
Land appliers must follow application restrictions and pollutant loading restrictions for Class B
biosolids at the time of application with regard to public contact, animal forage, and production
of crops for human consumption. For example, Class B biosolids may only be applied at sites
where there is no possibility of contact with the general public. These sites include certain types
of agriculture, landfills, etc. Additional restrictions associated with Class B prevent crop
harvesting, animal grazing, and public access for a defined period of time until environmental
conditions have further reduced pathogens.
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Table 6.5 Pollutant Limits for Land Applied Biosolids
Pollutant
EPA Ceiling
Concentration
Limits, mg/kg
dry weight
basis
EPA Class A
Pollutant
Concentration
Limits, mg/kg
dry weight basis
RWQCP
Sludge Cake
2011 Average,
mg/kg 26.6%
Solids
RWQCP
Calculated
mg/kg dry
weight basis
(Cake/26.6%)
Theoretical
Anaerobic
Digestate, mg/kg
dry weight basis
(Cake/(1-43%))
The PSRPs considered in this study include mesophilic anaerobic digestion and static aerated
pile composting. To meet Class B standards, the mesophilic anaerobic digestion process must be
operated between 15 days at 35 to 55 degrees Celsius and 60 days at 20 degrees Celsius.
Composting operations are required to raise the temperature of biosolids to 40 degrees Celsius or
higher for five days. The temperature in the compost pile must also exceed 55 degrees Celsius
for four hours during the five-day period.
6.2.5.1.2 Class A Biosolids
Class A biosolids can be produced through any of the defined Processes to Further Reduce
Pathogens (PFRP). Class A biosolids have more stringent treatment requirements than Class B
biosolids for pathogen reduction and may be land applied where contact with the general public
is possible (i.e., nurseries, gardens, golf courses, etc.).
The PFRPs considered in this study include thermophilic anaerobic digestion, static aerated pile
composting, heat drying, and pasteurization. To meet Class A standards, the thermophilic
anaerobic digestion process must be operated at 50 degrees Celsius or higher for 30 minutes or
longer. Composting operations are required to operate at 55 degrees Celsius or higher for three
days. Heat drying must reduce the moisture content of the biosolids to 10 percent or lower.
Pasteurization processes must maintain the temperature of the biosolids at 70 degrees Celsius for
30 minutes or longer.
6.2.5.1.3 Vector Attraction Reduction Requirement
In addition to reducing pathogen levels, 40 CFR 503 requirements mandate that biosolids
undergo treatment to reduce the risk of vectors such as flies, mosquitoes, fleas, rodents, and birds
that can get into the biosolids. In order to prevent the spread of disease-laden pathogens,
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biosolids must be treated to reduce their attractiveness to these types of vectors. The alternatives
considered for this study are expected to reduce the volatile solids by a minimum of 38 percent,
which would meet the vector attraction reduction requirements. Alternatively, drying the
biosolids would reduce the moisture content to 10 percent or lower, which also meets the
requirement.
6.2.5.1.4 Exceptional Quality Biosolids
Biosolids that meet the pollutant concentration limits, one of the Class A pathogen reduction and
one of the vector attraction reduction requirements, may be classified as EQ. EQ biosolids may
be used and distributed in bulk or bag form and are not subject to general requirements and
management practices other than monitoring, recordkeeping, and reporting to substantiate that
the quality criteria have been met.
6.2.5.1.5 Non- Hazardous Waste
The biosolids must also be tested with a frequency based on the amount generated to
demonstrate that they are non-hazardous.
6.2.5.1.6 California County Ordinances for Land Application
Use or disposal of biosolids is becoming progressively difficult in California. Land application of
biosolids is being restricted by many California counties, and fewer landfills are accepting
biosolids. Dewatered sludge is currently incinerated onsite at the RWQCP. Ash is hauled offsite
to a hazardous waste landfill in Beatty, Nevada.
Numerous counties in California have developed or are currently developing ordinances for
biosolids land application. Figure 6.1 summarizes the current status of County ordinances that
affect land application of biosolids.
To comply with possible future restrictions, the planning process will need to consider
alternative biosolids use and/or disposal scenarios that are cost effective and will operate within
the existing RWQCP facilities.
6.2.6 Governing Regulations for Sewage Sludge Incineration
Sewage sludge incinerators are regulated under EPA’s 40 CFR 60 Standards of Performance for
New Stationary Sources and Emission Guidelines: Sewage Sludge Incineration Final Rule (40
CFR 60). Sewage sludge or biosolids that are incinerated are classified as solid waste by these
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Figure 6.1 Status of Biosolids Land Application Ordinances by County
new EPA regulations. Consequently, sewage sludge incinerators (SSI) are considered solid waste
incinerators. The final rule sets limits for nine pollutants under section 129 of the Clean Air Act
(CAA), which include cadmium, lead, mercury, carbon monoxide, hydrogen chloride, oxides of
nitrogen, particulate matter, sulfur dioxide, and dioxins and furans. Specific limits are established
for multiple hearth and fluidized bed incinerators, both existing and new units. This section
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required the US EPA to establish new source performance standards (NSPS) for new and
modified SSIs, and emission guidelines (EG) for existing units.
The emission limits for SSIs were based on a Maximum Achievable Control Technology
(MACT) floor methodology, or the minimum stringency level. Limits for new SSIs were based
on the most recent SSI installations with advanced air pollution controls. Conversely, existing
SSI limits were based on the best performing SSIs. Limits for either new or existing SSIs were
specific to either multiple hearths or fluidized bed incinerators. Under section 129 of the CAA,
the EPA is required to review and revise these limits as necessary every five years.
New and modified SSIs are subject to the requirements of Subpart LLLL of 40 CFR 60.
Construction of a new SSI requires a preconstruction analysis; operator training and
qualification; emission limits and standards; operating limits; initial and continuous compliance
requirements; performance testing, monitoring, and calibration requirements; record keeping and
reporting. New SSIs are those for which construction commenced after October 14, 2011.
Modified SSIs are those for which modification commenced after September 21, 2011 and that
meet one of the two following criteria:
The cumulative costs of the changes made to a SSI unit exceed 50 percent of the original
construction cost, updated in to current dollars, not including the cost of land.
Physical changes in a SSI unit or operational changes to the SSI system that increase the
amount of any air pollutant emitted for which section 129 and 111 of the CAA have
established standards.
A SSI unit includes the solids feed system, auxiliary fuel feed system, grate system, flue gas
system, waste heat recovery equipment, and bottom ash system, and the ash handling system.
The ash handling system ends at the truck loading system. The air pollution control system is not
considered part of the SSI unit.
Existing SSIs are subject to the requirements of Subpart MMMM of 40 CFR 60. Use of the
Model Rule will address the regulatory requirements of this Subpart. The model rule includes
requirements for increments of progress to achieve compliance, operator training and
qualification; emission limits, standards, and operating limits; initial compliance requirements;
continuous compliance requirements; performance testing, monitoring, and calibration
requirements; and record keeping and reporting.
Sewage solids incineration must also comply with Subpart E of 40 CFR 503 and 40 CFR 61.
Subpart E regulates total hydrocarbons and seven metals: arsenic, beryllium, cadmium,
chromium, lead, mercury, and nickel. Limits for beryllium and mercury must meet the National
Emission Standards for Hazardous Air Pollutants under 40 CFR 61. Mercury limits under section
129 of the CAA are more stringent than 40 CFR 61. Cadmium, lead, and mercury limits are
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listed in both 40 CFR 503 and 40 CFR 60. Under 40 CFR 503, these limits must be calculated.
The lowest pollutant limit listed in any of the regulations must be used for the SSI to be in
compliance.
Emission limits are specific to either multiple hearth or fluidized bed incinerators (MHI and FBI,
respectively). Tables 6.6 and 6.7 summarize the emission limits for existing and new SSIs under
40 CFR 60. Emission limits for gasification systems have not been formerly established.
Thermal conversion technologies other than multiple hearths and fluidized bed incinerators may
be subject to 40 CFR 503. The EPA has suggested that the inclusion of other thermal conversion
technologies into this regulation will be considered on a case-by-case basis. Biosolids
gasification are assumed to follow 40 CFR 60 emission standards for new fluidized bed
incinerators for the purposes of the LRFP.
Table 6.6 Emission Limits for Existing Sewage Sludge Incinerators
Pollutant Units(1)Existing MHI Existing FBI
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Table 6.7 Emission Limits for New Sewage Sludge Incinerators
Pollutant Units(1)New MHI New FBI
These new incinerator regulations have been challenged in court by NACWA and the Sierra
Club; they may be revised as a result of the lawsuits.
6.2.7 Air Emissions
The federal Clean Air Act (CAA) requires EPA to set national air quality standards to protect
human health and welfare. The California Air Resources Board (ARB) is the agency responsible
for coordination and oversight of State and local air pollution control programs in California and
for implementing the CAA. The ARB has developed State air quality standards that are generally
more stringent than federal standards. Other ARB duties include monitoring air quality in
conjunction with local air districts, setting emissions standards for new motor vehicles, and
reviewing district input or the State Implementation Plan (SIP). The SIP consists of emission
standards for vehicles and consumer related sources set by ARB, and attainment plans and rules
adopted by local air districts.
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The following sections provide summaries of the relevant federal, state, and local air quality
standards that need to be considered in the LRFP.
6.2.7.1
The EPA recently (March 21, 2011) promulgated new source performance standards and
emissions guidelines for sewage sludge incineration (SSI) units at domestic wastewater treatment
facilities (discussed in Section 6.2.5). Under Section 129, the CAA requires EPA to determine
the maximum achievable control technology (MACT) for each subcategory of sources. The
MACT floor analysis for existing sources results in emissions levels that each existing SSI unit is
required to meet. These performance standards were set based on surveys of facilities operating
SSI units across the country.
Federal Regulations
The existing emissions limits for multiple hearth incinerator units are shown alongside 2010
sampling results for those operating at the RWQCP in Table 6.8. The emissions limits apply at
all times an incinerator is operating, including during start-up and shut-down.
As shown in Table 6.8 the RWQCP is currently in compliance with the newly adopted air
emissions limits. However, EPA’s draft regulation for 40 CFR 60 originally had more stringent
mercury standards (0.02 mg/dscm) that were modified for the final version (0.28 mg/dscm).
Since the EPA is required to review and revise these limits as necessary every five years (per
section 129 of the CAA), lower mercury standards may be implemented in the future. The
regulations require annual performance emissions testing or continuous emissions monitoring or
sampling. The operation also sets operator training and qualification standards.
All SSI units subject to the MACT rule are required to obtain a Title V operating permit. Title V
is one of several programs authorized by the U. S. Congress in the 1990 Amendments to the
federal CAA.
The primary intent of the Title V program is threefold: enhance nationwide compliance with the
CAA, provide the basis for better emission inventories, and provide a standard means to
implement other programs in the federal CAA.
The Title V program requires State and local air quality agencies to issue comprehensive
operating permits to facilities that emit significant amounts of air pollutants. For all
implementing agencies in the country, there are standard requirements for permit programs and
permit content. The MACT rule describes a variety of timing scenarios; however, the latest the
Title V permit can be submitted is March 21, 2014.
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Table 6.8 Emission Limits for Existing Sewage Sludge Incinerators and RWQCP
Performance
Pollutant Emission Limit
(1)RWQCP(2)Units
6.2.7.2
Palo Alto currently operates seven standby diesel engines ranging in size from 740 to 1103
horsepower. Replacement engines will need to comply with the Airborne Toxic Control Measure
(ATCM) for Stationary Compression-Ignition (CI) Engines. The ARB originally approved the
ATCM in 2004. Subsequent to the adoption of the 2004 ATCM, the U.S. EPA promulgated new
federal “Standards of Performance for Stationary Compression-Ignition Internal Combustion
Engines” (referred to as “NSPS”). In October 2010, ARB approved amendments to the ATCM to
closely align California’s requirements with those in the federal NSPS. The amended ATCM
became effective May 19, 2011.
State Regulations
The ATCM requires a 0.15 gram per boiler horsepower-hour (g/bhp-hr) particulate matter (PM)
emission limit for all new emergency standby stationary compression ignition engines greater
than or equal to 50 hp. Annual maintenance and testing hours are limited to 50 hours per
calendar year. New emergency standby engines are required to meet the applicable non-methane
hydrocarbon plus nitrogen oxides (NMHC+NOx), hydrocarbon (HC), and carbon monoxide
(CO) tier 2 or tier 3 non-road CI engine emission standards, and tier 4 standards that do not
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require add-on controls. Table 6.9 shows emission limits for engine sizes comparable to those
currently in use at Palo Alto.
Table 6.9 ATCM Emission Standards for New Stationary Emergency Standby
Diesel-Fueled CI Engines in g/bhp-hr (g/kW-hr)(1)
Maximum Engine
Power
Particulate
Matter
Non-Methane
Hydrocarbon plus
Nitrogen Oxides
Carbon
Monoxide
6.2.7.3
The RWQCP is also subject to the regulations of the Bay Area Air Quality Management District
(BAAQMD). The BAAQMD activities include rule development and enforcement, monitoring
of air quality, a permit system for stationary and mobile sources, air quality planning, protection
of the public from adverse affects for toxic air contaminants, and responses to public requests for
information regarding air quality issues.
Bay Area Air Quality Management District Regulations
The BAAQMD administers rules and regulations that apply to stationary and mobile sources that
emit air contaminants in the Bay Area. Generally, new and existing stationary sources are
governed by requirements in Regulations 2 (Permits), 8 (Organic Compounds), 9 (Inorganic
Gaseous Pollutants), and 10 (Standards of Performance for New Stationary Sources).
The RWQCP currently holds a permit to operate from the BAAQMD. The existing permit allows
operation of numerous stationary sources, including several emergency standby diesel engines.
Under the recently promulgated emissions guidelines for existing SSIs, the RWQCP will need to
apply for a Title V permit through the BAAQMD.
Title V operating permits differ from other Air District issued operating permits in that they
explicitly include the requirements of all regulations that apply to operations at Title V facilities.
The important features of Title V operating permits include the following:
Must include all federally enforceable requirements that apply to operations at the facility.
Proposed permits undergo public notice.
EPA has authority to terminate, modify or revoke and re-issue a permit if cause exists.
Permits are federally enforceable and may also be enforced via citizen lawsuits.
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Permits must be renewed every five years with the full public notice and EPA review
process.
Modification procedures are dictated by EPA regulations.
Regulation 2, Rule 2 implements Federal New Source Review (NSR) and Prevention of
Significant Deterioration requirements. This permitting process governs the construction,
replacement, operation, or alteration of any source that emits or may emit contaminants. The
process involves an Authority to Construct, followed by a Permit to Operate. Any new or
modified source is required to comply with new source review requirements, including
application of Best Available Control Technology (BACT), and emission offsets.
BACT is the level of emission control or reduction for new and modified sources of emissions
that have the potential to emit 10 or more pounds of any criteria pollutant per day. BACT is
intended to reduce emissions to the maximum extent possible considering technological and
economic feasibility. The BAAQMD maintains a BACT/TBACT (Toxics-BACT) Workbook,
and the California Air Pollution Control Officers Association (CAPCOA) also maintains a
clearinghouse for statewide BACT determinations.
Emission Offsets, or Emission Reduction Credits (ERCs), are generated by reducing emissions
beyond what is required by regulation, or by curtailing or shutting down a source. ERCs may be
used to provide offsets for emission increases from a new or modified source, as required by
New Source Review. The ERCs may be banked and the banking certificates may be traded or
sold to another facility for use as offsets for that facility. These credits can be very valuable and
consideration should be given to retaining them for future projects.
6.2.7.4
6.2.7.4.1 State and Federal Mandatory Reporting
Greenhouse Gas Emissions
The ARB adopted the Global Warming Solutions Act (also referred to as Assembly Bill 32, AB
32) in September 2006. This Act was the first regulatory program in the U.S. to require public
and private agencies statewide to reduce greenhouse gas (GHG) emissions. The GHGs regulated
under AB 32 are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated
gases. The Act does not affect wastewater treatment process emissions, but it does cover
cogeneration facilities and onsite general stationary combustion sources. ARB’s Proposed
Scoping Plan (released October 2008) listed two thresholds by which agencies are to check if
they are required to report. The reporting thresholds shown in Table 6.10 include combustion
emissions from both fossil fuel (i.e., natural gas and diesel) and non-fossil fuel (i.e., biogas)
sources.
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Table 6.10 Greenhouse Gas Emissions Thresholds for Reporting Years 2010,
2011 and Beyond
Facilities Reporting Year 2010 Reporting Year 2011 and Beyond
In addition, the U.S. EPA’s Mandatory GHG Reporting Rule (Reporting Rule) was adopted
October 30, 2009. The Reporting Rule explicitly states that centralized domestic wastewater
treatment systems are not required to report emissions; however, any stationary combustion of
fossil or non-fossil fuels taking place at a wastewater treatment facility may be considered a
“large” source of GHGs if they emit a total of 25,000 metric tons or more of CO2 equivalent
(CO2e) emissions per year.
The RWQCP’s 2009 general stationary combustion (including combustion of natural gas and
biogas from the nearby landfill) GHG emissions were approximately 4,200 metric tons of CO2e
emissions. This is well below the emissions thresholds set for both State and Federal mandatory
reporting.
6.2.7.4.2 State Cap-and-Trade Program
In addition to mandatory reporting of GHGs, the ARB adopted a GHG cap-and-trade program
becomes effective in January 2012. This program states that agencies emitting 25,000 metric
tons or more of fossil fuel-based (i.e., natural gas and diesel) CO2e emissions per year beginning
in 2011 or any subsequent year will be capped and required to reduce their emissions over time.
As long as the RWQCP maximizes its use of renewable fuels and stays below this threshold, the
current regulations may only require the RWQCP to report GHG emissions and will not subject
it to being a capped entity.
6.2.7.4.3 New Source Review Prevention of Significant Deterioration and Title V GHG
Tailoring Rule
On May 13, 2010, the U.S. EPA adopted the final rule, which sets thresholds for GHG emissions
that define when permits under the New Source Review (NSR) Prevention of Significant
Deterioration (PSD) and Title V Operating Permit programs are required for new and existing
industrial facilities. The rule “tailors” the permit programs to limit which facilities are required to
obtain PSD and Title V permits.
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Defining GHG emission sources at wastewater treatment plants that are covered in this final rule
is open to air district interpretation (e.g., whether combustion and/or process emissions are
included); however, the Bay Area Air Quality Management District (BAAQMD) is only
considering stationary combustion emission sources. In addition, this Rule only looks at fossil
fuel related emissions at this time – as of January 12, 2011, EPA deferred GHG permitting
requirements for non-fossil fuel (i.e., biogas) and biomass emission sources (including process
emissions) for three years.
The RWQCP currently does not trigger reporting under this rule.
6.2.8 Cross-Media Impacts
The interconnection of regulations between various areas related to wastewater is an important
consideration. Recently representatives from various air districts, Regional Water Quality
Control Boards (Regional Water Boards), Caltrans, and the EPA came to an agreement to
develop a cross-media checklist for use during the development of regulations. To discuss cross-
media issues and solutions, the California Association of Sanitation Agencies (CASA) along
with other Clean Water Summit Partners organized a Biosolids Cross-Media Roundtable for a
wide range of state and federal officials on May 16, 2008. As a result of the roundtable, CASA
has coordinated efforts to develop the cross-media checklist. Components of the cross-media
checklist include biosolids, compost processing, recycled water, California’s AB 32 (regulating
GHG emissions), California Environmental Quality Act (CEQA), regulatory processes,
development of Water Quality Control Plans (Basin Plans) and water quality
standards/regulations, and impact assessments to air, water, and land media. The process of
getting the checklist implemented by the various California air, water, and waste control boards
is still underway.
Figure 6.2 shows the key wastewater components and their corresponding regulatory issues.
6.2.9 Hazardous Materials and Wastes
The RWQCP manages onsite hazardous wastes. Regulations for hazardous wastes are overseen
by state disposal rules, the Palo Alto Fire Department, and Santa Clara County’s Department of
Environmental Health. Hazardous wastes onsite include laboratory materials, waste oil,
Household Hazardous Waste (HHW) items, fluorescent lamps, and paints.
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Figure 6.2 Cross-Media Impacts: Key Wastewater Regulatory Issues
6.3 FUTURE REGULATORY SCENARIOS
6.3.1 Approach to Development of Regulatory Scenarios
The development of regulatory scenarios for the LRFP is based on several factors, including:
Other waste discharge requirements (WDRs) issued to dischargers in the San Francisco
Bay area and California.
Pending regulations.
Discussions with regulators.
Examination of growth and other non-regulatory developments that may affect areas where
the RWQCP is currently in compliance.
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These factors provide a basis for decision-making on regulatory issues to meet the needs of the
RWQCP through the planning horizon in 2062.
6.3.2 Long Term Regulatory Scenario Through 2062
Through the planning horizon of 2062, the RWQCP will consider many strategies to deal with
emerging regulations. At this level of planning, it makes sense to review groups of similar
contaminants, rather than individual constituents, to determine ways to control their discharge. In
general, the future regulations that have the greatest impact on the RWQCP long range planning
and facility layout are those requiring major process changes, namely increased nutrient removal
standards and incineration regulations that may drive the RWQCP to using different solids
treatment processes.
Figure 6.3 summarizes the primary regulatory scenarios that will affect the LRFP alternative
development. Ranges of permit cycles during which future regulations are likely to be
implemented are shown for each regulatory scenario. Actual implementation dates for future
regulations are projected and not certain.
Figure 6.3 Regional Water Board Future Regulatory Scenarios
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6.3.3 Summary
Table 6.11 summarizes solutions that can be implemented at the RWQCP to comply with current
and future potential regulatory issues.
Table 6.11 Summary of Potential Regulatory Issues and Solutions
Topic Issue Potential Solution
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Chapter 7
SOLIDS TREATMENT ALTERNATIVES
DEVELOPMENT AND SCREENING
7.1 PURPOSE AND OVERVIEW
As a critical function of treating wastewater at the RWQCP, solids removed from the liquid
treatment processes must undergo additional treatment before they leave the site for beneficial
use or disposal. The current solids treatment and handling system at the RWQCP includes
gravity thickening, dewatering with belt filter presses, and multiple hearth furnace (MHF)
incineration. The ash from the MHF is disposed of in a landfill. Due to the age of the MHFs and
the increasing regulatory and community pressure on incineration, evaluating solids alternatives
was a primary focus of this LRFP. As discussed in Chapter 5, long term operation of the MHF is
not recommended due to the age, deteriorating condition and future regulatory compliance
issues.
This chapter describes the solids alternative screening process, the alternatives considered, and
the alternative solids treatment processes that will be considered for further evaluation. The
solids treatment alternatives development and screening process began with considering
available solids disposition options. Solids treatment alternatives that could achieve the required
solids stabilization for a particular disposition option were evaluated using a set of initial
screening criteria. Alternatives that best satisfied the initial screening criteria were selected for
further evaluation.
7.2 BASIS FOR EVALUATION/PLANNING CONSIDERATIONS
The solids alternatives were evaluated for several key considerations: to meet the projected
solids loading to the RWQCP, to meet regulatory requirements and to fit on the RWQCP existing
plant site. Each of these considerations is discussed briefly below along with the overview of the
alternatives development process.
7.2.1 Projected Flow and Loads
Influent flows and loads have been projected through the year 2062, as presented in Chapter 3.
Based on population projections and current per capita flow rates, the projected average dry
weather flow for 2062 is 34 mgd and the maximum month flow is 41 mgd. An alternate flow
projection was developed using anticipated flow reductions from conservation and building code
changes provided by member agencies. This alternate projection is 28.6 mgd for average dry
weather and 34.6 mgd for maximum month. Influent loadings are not anticipated to change with
conservation and are projected at maximum month as 72,874 ppd for TSS and 78,870 ppd for
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BOD. These projections were used (along with estimates of additional solids from liquid
treatment processes) for sizing the biosolids alternatives discussed herein.
7.2.2 Regulatory Requirements
Existing and future regulatory requirements for the RWQCP are presented in Chapter 6. Relevant
requirements for solids treatment facilities include EPA’s 2011 Sewage Sludge Incineration
Rule, EPA’s 40 CFR 503 regulations for contaminant limitations, and pathogen and vector
control for biosolids, State and local use and disposal requirements, and the Bay Area Air
Quality Management District’s requirements for air emissions. All alternatives discussed were
developed to meet anticipated regulatory requirements.
7.2.3 Site Considerations
The RWQCP has a very compact site that is already filled with treatment processes. Due to
adjacent neighbors (such as the nearby parkland, business parks, and airport), odors, noise,
emissions, truck traffic, and visual impacts are a concern. As a result, during a meeting with the
LRFP project team (including City staff and Carollo) it was determined that siting all new solids
treatment facilities near the center of the plant rather than the periphery was preferable.
Figure 7.1 shows the existing facilities and the area identified for future solids facilities.
7.2.4 Solids Treatment Alternatives Development Process
In developing the solids alternatives, the LRFP project team presented the alternatives to the
stakeholders on several occasions. In February 2011, the biosolids disposition options and solids
treatment alternatives were presented to the stakeholders in a public meeting. At this meeting,
each alternative was briefly presented along with its general benefits and disadvantages. At the
November 2011 public meeting, the biosolids alternatives were presented in greater detail with
descriptions of costs and greenhouse gas emissions for each. A summary of the
recommendations for solids was presented at the March 1, 2012 final public meeting. Input was
taken at each of these public meetings and used to develop the overall recommendations
presented herein.
7.3 SOLIDS DISPOSITION OPTIONS
Solids can be disposed of or beneficially used depending on their material content and the extent
they have been stabilized. The solids disposition options considered for this study are described
below and include direct landfill of solids, use of biosolids as an alternative daily cover, ash
disposal resulting from thermal conversion of solids, land application of biosolids, producing
marketable products from biosolids, and regional opportunities that would require exportation of
solids to an off-site solids processing facility.
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7.3.1 Landfill Disposal
7.3.1.1
Some landfills allow disposal of untreated solids or biosolids. Each landfill has its own
requirements for disposal of these materials with respect to solids content and specific chemical
constituent concentrations. Generally, dewatered cake is an acceptable form of material that can
be landfilled. Biosolids cake is typically anaerobically digested and then mechanically dewatered
to between 18 and 30 percent solids.
Direct Landfill of Solids
However, the trend in California is to move towards the prohibition of organics sent to landfills.
In addition, capacity is becoming an issue with many landfills, including the City’s landfill,
which was not considered because of its closure July 28, 2011.
Treatment processes that can produce acceptable materials for landfill disposal include anaerobic
digestion and solids dewatering.
7.3.1.2
Soil is typically used as daily cover for the solid waste placed in a landfill. Biosolids can be
mixed with other materials to serve as an alternative daily cover (ADC) for the solid waste,
reducing the use of soil for that purpose. ADC is considered to be a beneficial use, even though
the materials are ultimately entombed within the landfill. ADC use is regulated by CalRecycle,
and is limited to 25 percent of the total landfill cover requirements. Treatment processes that can
produce acceptable materials for ADC include anaerobic digestion and solids dewatering.
Alternative Daily Cover
7.3.1.3
Ash is the end product of combusted sewage sludge and can be classified as either non-
hazardous or hazardous based on its pollutant concentrations. The ash is typically landfilled;
however, it can be beneficially used in the production of brick or cement products if (a) a nearby
facility can be identified, (b) price is right, and (c) the quality of ash is consistent so that it meets
manufacturer’s and end user expectations. Multiple hearth and fluidized bed incineration produce
ash. Plasma arc oxidation, pyrolysis, and gasification produce a biochar that may be used as soil
amendment or disposed in a landfill, similar to ash.
Ash Disposal
7.3.2 Land Application
Land application refers to the agricultural use of biosolids in bulk as a soil amendment or
fertilizer to grow crops. The biosolids add organic matter to the soil, which is a valuable addition
to many California soils that lack this material. Biosolids are applied at or below the agronomic
rates, required by the Federal Regulations 40 CFR 503, to ensure that the nitrogen in the
biosolids are used up by the crop rather than accumulating in the soil and leaching to
groundwater.
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Biosolids are classified as Class A or Class B, which correspond to the level of treatment to
reduce pathogens. Class A biosolids that meet more stringent requirements for pollutant
concentrations required by the 40 CFR 503 regulations are called Exceptional Quality (EQ).
Class B biosolids can be applied only at sites where the general public could not come into
contact with the material (e.g., agriculture, landfills). Class A biosolids can be applied where the
general public may come in contact with the biosolids (e.g., nurseries, gardens, golf courses). EQ
biosolids can be used in bulk form or distributed in bags.
As discussed in Chapter 6, there has been increasing pressure to ban land application, especially
of Class B biosolids. Twenty-two counties in California have implemented either a complete or a
partial ban on biosolids land application through either a direct ban or impracticable requirement.
Only three counties specifically allow Class B biosolids land application: Sonoma, Solano and
Merced Counties as shown in Figure 7.2. Dewatered cake represents the most basic and most
common form of land-applied biosolids.
7.3.3 Marketable Products
7.3.3.1
Dewatered cake can be mixed with various other materials (e.g., soil) and processed to create soil
amendments (i.e., compost) or topsoil replacement products. In general, compost products are
considered the most acceptable beneficial use products available to the public. This is because
compost products are associated with food, yard, and agricultural wastes that the public is more
familiar with and so are more likely to accept biosolids compost.
Biosolids Compost
The list of potential feedstock materials that can be used include green waste, wood chips,
sawdust, sand, lime, cement kiln dust, wood ash, and others. Soil amendment products are
generally treated to Class A pathogen density standards. The soil amendment class of products
usually has a pleasant, earthy odor and pleasing overall appearance to the general public.
7.3.3.2
Dewatered cake can be dried to form fertilizer products. Thermally dried biosolids products
generally contain less than 10 percent moisture. The product appearance can range from uniform
spherical pellets to less uniform granules. The overall appearance of thermally dried products is
generally acceptable to the public.
Dried Biosolids
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ARIZONA
NEVADA
MEXICO
OREGON
DEL
MENDOCINO
SAN FRANCISCO
SISKIYOU MODOC
LASSENSHASTA
TEHAMA PLUMAS
GLENN BUTTE SIERRA
NEVADA
PLACERYUBA
EL DORADOALPINE
COLUSA
LAKE
SONOMA
NAPA
YOLO
SOLANO
MARIN CONTRACOSTA
ALAMEDA
SANMATEO SANTACLARA
SANJOAQUIN TUOLUMNE
TRINITY
SANBENITO
TULAREMONTEREY
MERCED
MONO
FRESNO INYO
SAN LUISOBISPO
KERN
KINGS
SAN BERNARDINO
SANTABARBARA
LOSANGELES
VENTURA
RIVERSIDE
IMPERIALSANDIEGO
ORANGE
pa911f4-8510.ai
Figure 7.2
STATUS OF BIOSOLIDS LAND APPLICATION
ORDINANCES BY COUNTY
LONG RANGE FACILITIES PLAN FOR THE RWQCP
CITY OF PALO ALTO
SANTA CRUZ
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Dried biosolids can be used as a soil amendment or fertilizer for agricultural purposes as a Class
A product. Conventional spreading equipment is used to apply the product. The pellets are
similar in size and shape to, and can be blended with, conventional synthetic fertilizer materials.
Figure 7.3 Dried Biosolids Pellets and Marketable Products
Dried biosolids can also be used as an alternative fuel source, which can offset fossil fuel usage.
Dried biosolids have an energy content that ranges between approximately 7,000 to 10,000 Btu
per pound depending on the stabilization process used. Potential future markets for dried
biosolids pellets include electrical power plants and cement kilns. The cement industry has
recently become interested in biosolids as a renewable fuel source not only because of the
biogenic fuel value, but because the combustion ash adds needed chemicals that can be
integrated into the cement. User requirements are specific to each cement kiln.
There is a large operating cement kiln located approximately 13 miles from the RWQCP. A
Lehigh Hanson Cement Plant representative was contacted. The representative explained that the
facility is currently upgrading their air pollution control system and they have no interest in using
dried biosolids granules as a fuel at this time.
7.3.3.3
Pyrolysis is a thermal conversion technology that can convert sludge into a char or oil having an
energy content ranging from 4,500 to 9,000 Btu per pound. The process also produces a syngas
Pyrolysis Char/Oil
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that can be used as a fuel. These materials can be used in waste-to-energy facilities and cement
kilns. Since there are no currently operating pyrolysis facilities in the U.S. that take in sludge or
biosolids, evaluation of uses of pyrolysis char or oil will be tracked for future consideration, but
not considered further in the LRFP process.
7.3.4 Regional Opportunities
Two regional opportunities to process the City’s sewage sludge have been considered in this
LRFP: 1) Bay Area Biosolids-to–Energy (BAB2E) Project and 2) the San Jose/Santa Clara
Water Pollution Control Plant (SJ/SC WPCP). For each of these, solids would be hauled from
the RWQCP to the facility. The BAB2E facility could utilize the solids as a fuel to produce
energy. This could be implemented either with or without digestion at the RWQCP.
Alternatively, the solids could be anaerobically digested at the SJ/SC WPCP. Each of these
alternatives would require upgrading the RWQCP’s dewatering capabilities, as well as providing
solids storage and loading facilities.
Other opportunities with adjacent wastewater treatment facilities were considered (e.g.
Sunnyvale and South Bayside System Authority), but none other than the SJ/SC WPCP have
adequate capacity in their solids treatment facilities.
7.3.5 Comparison of Disposition Implementation and Longevity
As discussed in the sections above, the different disposition options have differing regulatory and
policy pressures that affect whether they are viable long-term alternatives. Based on our current
understanding of these pressures we anticipate the approximate remaining life (and rationale) for
each of the options to be as shown in Table 7.1.
In general, the future appears to hold limited options for landfill disposal and land application of
biosolids in California, unless public perception is changed. Continued landfill disposal of ash is
less problematic due to the small volume and lack of organics. Long term, reliable options for
biosolids include developing marketable products and collaborating on regional solutions.
7.4 SOLIDS TREATMENT PROCESS ALTERNATIVES
This section identifies and evaluates alternative treatment schemes to satisfy potential future
biosolids beneficial use/disposal requirements and to comply with air emission requirements.
These alternatives include solids thickening and dewatering processes, thermal conversion
technologies (i.e., multiple hearth furnace incineration, fluidized bed incineration, plasma arc
assisted oxidation, gasification, and pyrolysis), anaerobic digestion, solids drying, and regional
opportunities. These solids treatment alternatives and associated energy recovery opportunities
are described in this section.
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Table 7.1 Comparison of Disposition Options
Estimated
Remaining Life Reason Issue/Driver
Landfill Disposal
Land Application
Marketable Products
Regional Opportunities
7.4.1 Summary of Existing Solids Treatment Facilities
The current solids treatment and handling system at the RWQCP includes gravity thickening,
dewatering with belt filter presses, and multiple hearth furnace (MHF) incineration. The ash
from the MHF is disposed of in a landfill.
7.4.2 Sludge Thickening and Dewatering
All of the disposition options discussed in Section 7.3 will require solids thickening and
dewatering. The RWQCP currently utilizes gravity thickening followed by belt filter presses for
dewatering. These processes are working well for the RWQCP and require a relatively low
energy input as opposed to other options such as dissolved air flotation thickening or centrifuge
dewatering. As discussed in Chapter 5, based on the age and condition of the existing thickening
and dewatering facilities, the RWQCP will need to plan for rehabilitation and/or replacement of
these processes during the 50-year LRFP implementation period. However, at this time the
RWQCP staff decided to assume continuation of gravity thickening and belt filter press
dewatering. It is recommended that each time the equipment is replaced and when significant
changes are made to the sludge being dewatered that this decision be reevaluated.
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7.4.3 Thermal Conversion
The following section describes the thermal conversion technologies considered for the initial
qualitative screening evaluation. Thermal conversion technologies would be utilized following
thickening and dewatering of the solids. Thermal conversion options considered include multiple
hearth furnaces (the existing process), fluidized bed incineration, plasma arc assisted oxidation,
gasification, and pyrolysis. A process schematic of how existing and future thermal processing
would be configured is shown in Figure 7.4. Opportunities for energy and/or heat recovery are
discussed for each process alternative.
Figure 7.4 Existing and Future Thermal Solids Processing
7.4.3.1
Multiple hearth furnace (MHF) incineration is the current solids processing technology
employed at the City’s RWQCP. The system is composed of two MHFs and air pollution control
systems. Each MHF is a cylindrical tower consisting of six evenly stacked hearths. Solids are fed
through the top of the furnace and they pass downward through each hearth. The MHF operates
with three primary zones: 1) drying zone, 2) combustion zone, and 3) cooling zone. Dewatered
cake is fed into the drying zone located at the top of the furnace. Dried solids enter the
combustion zone located in the middle. The solids are combusted and reduced to ash, which is
cooled in the lower part of the MHF.
Multiple Hearth Furnace Incineration
Combustion air and fuel can be introduced into hearths 1, 2, 4, and 5. Combustion air is added to
these hearths to provide adequate oxygen for the combustion process. Fuel in the form of natural
gas is introduced to control combustion temperatures. The operating temperature range for the
MHFs is 760 to 930 degrees Celsius.
Cooling air is blown through the center shaft to protect rotating steel equipment from warping
within the MHFs. The cooling air does not come into contact with the solids. As the cooling air
reaches the top of the shaft, it is used for mist suppression and exhausted to atmosphere.
Two streams of air are discharged from the MHF. Combustion air and any air that comes in
contact with solids are treated to remove pollutants. The flue gas is treated in an afterburner
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maintained over 1,300oF to complete combustion on flue gases not completely combusted within
the furnace. The exiting afterburner air is pulled into a wet scrubber where heat, moisture, and
particulate matter are removed. Exhaust gases are sent to a stack where the stack gas is
continuously monitored for total hydrocarbon levels.
A condition assessment and seismic stability analysis were performed on the both the MHF
incinerators and the incinerator building, as discussed in Chapter 5. While the facilities have
been well maintained , based on the age the MHFs are estimated to have approximately 10 years
of remaining useful life. The earthquake used for the seismic evaluations were consistent with
the ground motion at the site that has a 10 percent probability of being exceeded in a 50-year
period. Results of these evaluations concluded that the MHFs at RWQCP are not anticipated to
collapse or suffer extensive structural failure that would affect the safety or long-term operation
of the incinerators. However, there could be some localized interior damage to the refractory
bricks due to seismic force. The seismic review of the incinerator and dewatering building found
that the building piles lacked the shear strength required to resist the seismic loading. During a
large earthquake, the piles are likely to shear off below the top of the pile and the building could
then experience unpredictable movement potentially resulting in significant lateral displacement
and/or rotation. Construction costs to rehabilitate the building with new piles and connections
were estimated at $0.55 million.
There is limited opportunity to recover heat from the existing MHF system.
7.4.3.2
Fluidized bed incineration is a well-established sludge treatment technology in the U.S. It is the
preferred technology for new incineration systems because they are more energy efficient, easier
to control, and produce less air emissions than MHFs. Fluidized bed incinerators are refractory-
lined steel cylinders with three distinct zones: 1) a windbox, 2) the bed section typically
composed of sand, and 3) the freeboard. Combustion air is preheated and introduced into the
windbox, which distributes air to an orifice plate. The plate separates the windbox from the
fluidized bed, provides structural support for the sand bed, and is comprised of air distribution
tubes. Fluidizing air is passed through the tubes to the bed section, which fluidizes the sand.
Dewatered cake is fed into the fluidized sand bed, the water in the solids is evaporated, and the
combustible matter is oxidized in seconds. Oxidation gas and water from this process flow
upward into the freeboard where the gas combusts and completes the process.
Fluidized Bed Incineration
The operating temperature range for the freeboard is 650 to 850 degrees Celsius. A high-pressure
spray system is located in the freeboard zone to control process temperatures. This is more
efficient and less costly than the existing MHF process that uses auxiliary fuel to control process
temperatures.
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Air from the incineration process is recycled to preheat the combustion air. Prior to discharging
the air to the atmosphere, it is treated to remove pollutants. Carbon is injected upstream of a
baghouse filter to remove mercury from the air stream. The air is conveyed to the baghouse filter
where the mercury-containing carbon is removed as it passes through the filter. These steps are
followed by a tray scrubber and wet electrostatic precipitator to remove the particulate matter
(ash). Then the air is condensed to remove moisture and clean air is discharged to the
atmosphere.
Energy and heat recovery from a FBI system would typically consist of a waste heat recovery
boiler to generate steam, which is used to turn either process equipment (such as pumps or
blowers) or a generator. Based on discussions with vendors, for a facility the size of the Palo
Alto RWQCP, it is not cost effective to incorporate energy generation. Inherent to the FBI
system is recirculation of the heated air to reduce energy input required for operation. This
reduction in energy is included in the overall energy required for operation of the FBI system.
7.4.3.3
Plasma arc assisted oxidation is an emerging technology with no commercially operating
installations for wastewater solids. This technology uses a plasma torch that could heat, dry, and
oxidize sludge. The torch is created in an electrode with an electrical current and combustion
gas. The electrical current is passed through the combustion gas. The current ionizes the gas until
an arc of light called plasma is created, similar to lightning. Combustion gas is projected through
the end of the electrode creating the plasma torch. The torch creates enough energy to preheat the
incoming sludge and combustion air, which makes the process more energy efficient. The
plasma torch is located at the end of a rotary kiln.
Plasma Arc Assisted Oxidation
Dewatered sludge and oxidation air are fed into the rotary kiln after being preheated. Drying and
oxidation occur inside the kiln with the presence of the plasma torch located at the opposite end.
Ash accumulates in the kiln and acts as a heating media for the incoming material. As it builds
up, ash is extracted and could be trucked to a landfill or beneficially used. Process air is
exhausted through an air pollution control system and ultimately discharged to the atmosphere.
Plasma arc assisted oxidation is similar to incineration except that no auxiliary fuel is needed to
start or sustain the operation, required additional energy is provided as electricity through the
electrodes. Other differences include the operating temperature and feed solids concentration.
The operating temperature (600 to 700 degrees Celsius) is lower than either of the other
incineration processes considered – multiple hearth (760 to 930 degrees Celsius) and fluidized
bed (650 to 850 degrees Celsius). Feed solids must have a minimum 9,500 Btu heating value and
20 percent solids concentration. The air pollution control system for a plasma arc assisted
oxidation process would be similar to FBI.
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Fabgroups Technologies Inc./Hydro Quebec have a demonstration unit in operation that can
process up to 48 wet tons per day. The facility is expected to be commercially ready for
operation in the near future. Due to the lack of operating systems, it is unknown whether a
plasma arc system could be configured to recover heat for potential energy generation, although
because of the high electrical usage to provide the plasma arc, it is doubtful that it could produce
more energy than it consumes.
7.4.3.4
Gasification of sludge/biosolids is a technology that has been widely used for the last twenty
years on coal, wood, and municipal solid waste. However, it is an emerging technology for
processing wastewater sludge, with only one installation in the U.S. (in Sanford, Florida). The
Sanford installation has been intermittently operated since 2010, during which they tested and
optimized the gasification process. MaxWest began officially reporting biosolids processing data
to the EPA in early 2011, upon which they considered the installation to be a commercial
operation. However, the facility has operated intermittently throughout the year, much like the
pattern prior to this year. The process involves applying a controlled amount of air to supply a
small amount of oxygen to control the heat to a fuel rich sludge providing a temperature-
controlled environment (greater than 800 degrees Celsius). Most of the volatile portion of the
sludge is converted into synthesis gas, also called “syngas.” However, complete combustion is
not realized in the gasifier because gasification operates in an oxygen-starved environment. An
estimated 80 percent of the solids are converted to syngas. The remaining ash has little value and
is usually disposed of similar to incinerator ash, though there are ongoing studies evaluating its
use as a fertilizer.
Gasification
Dewatered sludge is fed into a dryer to reduce the moisture content to approximately 10 percent.
Dried solids are conveyed into the gasifier at a controlled rate to optimize syngas production.
The majority of the volatile content of the solids is converted to syngas and conveyed to a
thermal oxidizer where it is blended with air and burned. The heated flue gas from the thermal
oxidizer is used to heat the solids dryer. Flue gas is conveyed through a bag house filter and
scrubber prior to atmospheric discharge. In addition, flue gas from the solids dryer is conveyed
to an odor control system prior to atmospheric discharge.
As currently implemented, while the syngas produced in a wastewater solids gasification process
has a high fuel value, it is all utilized to dry the solids prior to the gasification unit. Because of
this, there is little recoverable energy, and it is actually a net user of power since electrical power
is used for dewatering, conveyance, and odor control, even though this is a relatively small
power use.
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7.4.3.5
Pyrolysis is an emerging technology with no commercially operating installations in the U.S.
The process is similar to gasification in that it involves applying a controlled amount of heat to
sludge except that it operates in an oxygen free environment. Because it operates in this type of
environment, there is little or no combustion. The incomplete combustion of the sludge produces
a char with an energy content ranging from 4,500 to 9,000 Btu per pound and a gas similar to
syngas created with gasification. In comparison, the energy content of coal is in the 8,000 to
12,000 Btu per pound range. The char and gas from pyrolysis can be used to fuel a waste-to-
energy facility or as a fuel alternative for cement kilns.
Pyrolysis
Similar to the gasification process, dewatered cake is dried to 90 percent solids and fed into the
pyrolysis system. The cake is subjected to high temperatures (less than 700 degrees Celsius) in
the absence of oxygen. Char and gas are created from this process and can be used as a fuel. The
air pollution control system for pyrolysis would consist of equipment similar to a gasification
process.
Due to the lack of operating systems, it is unknown whether a pyrolysis system could be
configured to recover heat for potential energy generation. Based on discussions with a German
company that has two operating pyrolysis facilities for solid waste, these system are not net
energy producers.
7.4.4 Anaerobic Digestion
Anaerobic digestion is a widely used sludge stabilization process in the U.S. Thickened sludge is
heated and fed into a digester where it is degraded in the absence of oxygen. The sludge is heated
and mixed in the digester for at least 15 days as it is decomposed by anaerobic bacteria.
Anaerobic digestion can meet Class A or B pathogen reduction requirements based on
temperature and time requirements as described in the 40 CFR 503 regulations. Digestion is a
suitable process for a variety of disposition options. Typically, solids are thickened prior to
digestion and dewatered after digestion and before any other processing or disposition, as shown
in Figure 7.5.
Figure 7.5 Digestion Solids Process
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The anaerobic digestion process can be divided into three stages: 1) hydrolysis – the
solubilization of particulate matter, 2) acidification – production of volatile acids, and 3)
methane formation. During hydrolysis, the proteins, cellulose, lipids, and other complex organics
are made soluble. During acidification, acetogens convert the biodegradable organics into low
molecular weight volatile fatty acids (VFAs). In the last stage, methanogens convert the VFAs
into methane and carbon dioxide. In conventional anaerobic digestion, all of these processes
occur within one reactor even though both groups of bacteria have considerably different optimal
conditions for growth.
Conventional mesophilic anaerobic digestion involves insulated digesters, operated at increased
temperatures from 95 to 105 degrees Fahrenheit, with a hydraulic residence time (HRT) of 15
days or more. Waste heat from a cogeneration system or boilers and heat exchangers are required
to attain mesophilic temperatures. Mesophilic digestion is typically used to produce Class B
biosolids.
Odor control has been a concern with the anaerobic digestion process. Methane and carbon
dioxide are the primary end products of an anaerobic digestion process, but hydrogen sulfide and
ammonia are also produced under anaerobic conditions.
The anaerobic conditions in digesters also release ammonia from the solids back into liquid,
which stays with the liquid recycle stream during dewatering and is usually returned to the liquid
treatment processes. This ammonia recycle stream adds load to the secondary treatment process,
requiring an additional input of energy for treatment. The additional liquid treatment required
due to digestion is discussed further in Chapter 8, Liquid Treatment Alternatives Development
and Screening.
The anaerobic digestion process can be modified to operate at higher temperatures or to
incorporate additional phases to produce Class A biosolids. Anaerobic digestion in general was
considered for this screening evaluation. Variations on anaerobic digestion processes will be
evaluated further during a preliminary design phase if anaerobic digestion is selected for
implementation. The anaerobic digestion processes that should be included in this type of
evaluation would be: mesophilic, thermophilic, temperature-phased, acid-phased, and a
combination of thermal hydrolysis and anaerobic digestion. Descriptions of these alternative
anaerobic digestion processes are included in Appendix K.
Anaerobic digestion presents an opportunity to produce energy at the RWQCP. Energy recovery
from an anaerobic digestion process consists of using the digester gas in a co-generation process
and using waste heat to heat the digesters. For most wastewater facilities, cogeneration consists
of reciprocating engines, which have an overall efficiency (as a percent of fuel input energy) of
30 to 38 percent conversion to electrical energy and 40 to 45 percent efficiency to recoverable
heat. Emissions from engines are limited by the Bay Area Air Quality Management District, with
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limits continuing to get more restrictive. It is assumed that, in the future, a digester gas scrubbing
system and exhaust gas scrubbing equipment will be required for cogeneration.
An alternative to engines is the use of fuel cells, which are electrochemical devices that combine
hydrogen from the digester gas and oxygen from the air to produce electricity and recoverable
heat with little emissions. Fuel cells have an overall efficiency of 45 to 47 percent conversion to
electrical energy and 20 to 25 percent efficiency to recoverable heat. Fuel cells require gas
conditioning systems to remove contaminants from the gas and to convert the methane to
hydrogen. The gas conditioning systems are fairly complex and require regular maintenance.
There are several fuel cell systems that have been installed in California with significant grant
funding from the state. Some of these installations have experienced difficulty with the fuel
conditioning systems. It is also unknown how long grant funding will remain available for fuel
cells. Due to the limited installations of fuel cells, we recommend keeping this technology on the
promising technology list, but we are including reciprocating engines for the alternatives
evaluation.
7.4.5 Composting On-site
Composting is a stabilization process normally performed after biosolids are dewatered and after
subsequent mixing with a bulking agent. The bulking agent raises the initial solids content of the
mixture and provides a carbon source for the organisms and bulk porosity important for
maintaining aerobic conditions. High temperatures achieved during the microbial decomposition
reduce pathogenic organisms in the solids. When composting is complete, the compost material
is typically screened to retrieve a portion of the bulking agent. The product is then allowed to
cure for several days and the resulting humus-like material can be used as a soil amendment. As
identified in the 40 CFR 503 regulations, composting operations can meet either Class A or Class
B pathogen reduction requirements dependent upon time and temperatures met during the
process.
In general, compost products are considered the most acceptable beneficial use products
available to the public. This is because compost products are associated with food, yard, and
agricultural wastes that the public is more familiar with and so are more likely to accept biosolids
compost. In addition, biosolids compost does not have an objectionable odor or sludge-like
appearance. The two most common types of composting processes are windrow composting and
aerated static piles.
In windrow composting, the biosolids and bulking agent mixture is formed into long, open-air
piles. The biosolids are turned frequently to ensure an adequate supply of oxygen throughout the
compost pile and to guarantee high, uniform temperatures throughout the pile for optimal
pathogen reduction. Windrows are the lowest-cost composting process. However, this technique
can have high odor emissions and composting the plant’s sludge would take significantly more
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land than is available on the site. Therefore, windrow composting will not be considered for
further evaluation.
Aerated static piles rely on forced air to supply air for both decomposition and moisture removal.
Air is supplied by blowers connected to perforated pipes running under the piles. The blowers
draw or blow air into the piles, assuring even distribution of air throughout the composting
biosolids mixture. A layer of previously composted biosolids is often placed over the surface of
the pile to help to insulate the pile and assure that sufficient temperatures are achieved
throughout the pile. Positive pressure aerated static pile composting is often conducted within an
enclosed building in order to collect and scrub the gases emitted from the process. An aerated
static pile composting facility would require a large parcel of land and as such will not fit on the
RWQCP site and as such, aerated static pile composting will not be further evaluated.
There is no opportunity for energy and/or heat recovery from a composting operation. Due to the
limited land available on-site, composting options will only be considered for an off-site
location.
7.4.6 Composting Off-site
Another option to produce biosolids compost is to haul dewatered cake to a private composting
facility. Synagro operates a composting facility in Merced County that could accept solids from
the City.
Also, the City of Palo Alto is considering processing its green waste and food waste in a dry
digestion/composting facility that might be located at the parklands (former landfill site) adjacent
to the RWQCP. Co-mixing the green waste and food waste with biosolids is being considered as
one of the options.
There is no opportunity for energy and/or heat recovery from a composting operation whether
onsite or offsite.
7.4.7 Thermal Drying
Thermal drying is a well-established solids treatment technology. Drying technologies use
thermal energy to evaporate almost all moisture from biosolids to create a Class A product.
There are wide varieties of dryer technologies available; for master planning purposes, the
technologies can be divided into direct and indirect heat transfer technologies. The process flow
schematic for a dry operation at RWQCP is shown in Figure 7.6, although either digested or
undigested biosolids could be dried. Although drying of undigested solids leaves more of the fuel
and fertilizer value in the dried product (pellet), there are greater public perception and odor
issues as a result of the drying process and final product rewetting.
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Figure 7.6 Drying Solids Process
There is no opportunity for energy production using heat recovery from a dryer. In fact, dryers
require considerable input of fuel, which could be supplied by natural, digester or landfill gas.
On the other hand, the dried solids can be used as a biogenic fuel source for use in coal or coke
fired power plants or cement kilns.
7.4.7.1
Direct drying of solids typically takes place in a rotary kiln or a fluidized bed dryer. For a facility
the size of the RWQCP, a fluidized bed dryer is probably the equipment of choice and is
discussed here, although both should be evaluated during final design if drying technology is to
be implemented.
Direct Drying
In fluidized bed dryers, moisture removal is achieved predominantly by convective heat transfer.
A natural gas or biogas fired furnace heats oil or other heating media. The oil is pumped into a
heat exchanger where the heat is transferred to the fluidizing air. The heated fluidizing air comes
into direct contact with the cake solids, causing the water to evaporate. Fluidized bed dryers are
equipped to produce a high-quality biosolids product consisting of uniform, hard, spherical
pellets similar in appearance (with the exception of color and odor) to commercial inorganic
fertilizer products.
Dewatered biosolids are pumped directly into the dryer. An extrusion and cutting system is used
to form pellets for the drying process. Heated, fluidized air is blown through the bed of the dryer.
Once the pellets are dried, they are discharged from the fluidized bed. The pellets are separated
from the air stream and conveyed to storage.
Air from the dryer is conveyed to a bag house to remove particulate matter. The solids from the
baghouse are collected and mixed with a stream of cake solids fed to the dryer. The remaining air
is condensed and recycled to heat the fluidization air. Exhaust air is treated in a regenerative
thermal oxidizer to remove volatile organic compounds prior to atmospheric discharge.
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7.4.7.2
Indirect dryers achieve moisture removal predominantly by conductive heat transfer, and the
biosolids are kept separate from the primary heated drying medium (typically oil or steam). The
drying medium is heated in a boiler or heat exchanger by the hot combustion gases from a fuel-
burning furnace. Dewatered biosolids are introduced to the drying chamber, which is heated with
hot oil or steam. Moisture evaporates from the biosolids as they move through the machine.
Dried biosolids exit the dryer and are cooled prior to being put into temporary storage.
Indirect Drying
Vapor from the dryer passes through a condenser prior to treatment in a biofilter or other odor
control process and discharged to the atmosphere. The volume of air that must be treated is
significantly smaller than the direct drying systems because the furnace air does not come into
contact with the drying biosolids.
Indirect dryers can be equipped to produce pellets, similar to the direct dryers. However,
pelletizing would require recycling 50 to 70 percent of the dried material to initiate the pellet
forming process.
7.4.7.3
Heat dried biosolids products must be stored properly or they can ignite. If a pile of heat-dried
biosolids absorbs moisture, it can autoheat and combust. Therefore, proper design of product
storage facilities is vital. Product storage silos are generally equipped with temperature sensors
and inert gas blanketing to reduce fire potential.
Storage of Dried Biosolids
7.4.8 Regional Opportunities for Solids Handling and Disposal
Regional solutions for biosolids handling and disposal would entail taking either digested or
undigested solids produced at the RWQCP and transporting them to an offsite regional facility.
Depending on the distance, solids could either be pumped and piped or trucked to a regional
facility location. For this evaluation, we have assumed dewatered solids would be trucked to the
regional facilities as shown in Figure 7.7. Regional opportunities considered for the LRFP
include the Bay Area Biosolids-to-Energy (BAB2E) Project and the SJ/SC WPCP. It should be
noted that at the time of this report’s publication, the BAB2E site had not been determined.
Figure 7.7 Regional Opportunities Solids Process
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Regional opportunities have some implications to the existing landfill gas used at the plant. The
RWQCP will no longer be able to utilize landfill gas if a regional solids handling options is
implemented; instead, the landfill will need to use its flare continuously. Use of fuel cells or
generator engines is not recommended since the volume of landfill gas is expected to steadily
decline once the landfill is closed.
7.4.8.1
Sixteen bay area agencies have formed a coalition to implement a regional biosolids-to-energy
facility that will be located within the nine-county bay area. Following a request for
qualifications process completed in 2010, the coalition has selected the following teams to
participate in a subsequent request for proposals process:
Bay Area Biosolids-to-Energy Project
Synagro – for a dryer that would use waste heat from engines in Solano County to dry
biosolids then use the dried biosolids as a fuel in a biomass plant in Woodland.
MaxWest – for a gasification facility that would recycle heat from the gasifier but would
not produce energy at a site or sites yet to be determined.
Intellergy – for a steam reformation plant that would use the steam reformation process to
produce hydrogen fuel at a site or sites yet to be determined.
Selection criteria for the request for proposals (RFP) will require that a technology can
effectively and efficiently process biosolids. Prior to issuing the RFP, the coalition has elected to
pilot Intellergy’s steam reformation technology. The pilot will be used to demonstrate that the
technology can effectively and efficiently process biosolids. Based on the results of this pilot, the
coalition will issue an RFP for a regional biosolids to energy facility. The RFP is expected to be
released in 2012.
The solids going to the BAB2E facility could either be digested or undigested sludge. The cost
for this alternative will not be finalized until a technology is selected and the amount of grant
funding is determined.
7.4.8.2
The SJ/SC WPCP solids treatment process is currently comprised of anaerobic digestion, solids
storage lagoons, and drying beds. As part of their 2010 WPCP master plan
(
San Jose/Santa Clara Water Pollution Control Plant
www.rebuildtheplant.org), the solids treatment process will be upgraded. Nine of their sixteen
digesters will be upgraded, mainly to provide better mixing to match the biosolids needs. The
existing solids stabilization lagoons will be replaced with smaller covered lagoons that will store
digested solids for up to six months. Sludge from the lagoons will be extracted and mechanically
dewatered. A new centrifuge dewatering facility will be provided to dewater all biosolids. The
solids will then be dried either mechanically or via greenhouses.
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The SJ/SC WPCP would consider accepting sludge from the RWQCP; however, capacity would
need to be added to the SJ/SC WPCP solids treatment process. In addition, a receiving and
storage facility would need to be constructed to accept the sludge. The raw biosolids (over
90,000 lbs TSS/day at build out in 2062) would most likely be transported at a higher
concentration and would need to be diluted before incorporation into the WPCP digesters. At
2.89 million gallon (MG) of digester volume with submerged fixed cover and 0.2 lbs VS/ft3
loading, between one and two digesters would be needed to handle the RWQCP solids. The
RWQCP partner agencies would be responsible to finance these upgrades.
Various disposition alternatives will be available for biosolids from the SJ/SC WPCP. These
include landfill and agricultural uses, which require biosolids that are dewatered or dried.
Dewatered biosolids cake can be used as ADC at landfills. Composting processes typically
require dewatered cake. Composting facilities can be provided on-site or dewatered biosolids can
be sent to an off-site facility. Biosolids can also be dried and used for agricultural purposes.
Drying can be accomplished on-site with greenhouses or thermal dryers. Finally, the SJ/SC
WPCP Master Plan includes the option that the dewatered biosolids could go to the BAB2E
facility when it is constructed.
The two plants are located about 11 miles by freeway from each other. For this evaluation, it was
assumed that a solids loading facility would be constructed at the RWQCP site and the
dewatered solids would be trucked to the SJ/SC WPCP site where an unloading facility would be
constructed and additional solids handling facilities would be upgraded to handle the additional
capacity.
7.5 INITIAL SCREENING OF SOLIDS TREATMENT
ALTERNATIVES
A qualitative screening evaluation was performed on the alternative solids treatment processes.
The alternatives were evaluated against a set of criteria that included: treatment, environment,
community/neighbors, and cost.
Treatment criteria considered included: the process footprint, flexibility, and whether the primary
technology is proven. The RWQCP has limited area in which a solids treatment process can be
constructed. As a result, the overall footprint requirement of each alternative was evaluated.
Flexibility considered the ability for a technology to adapt to anticipated changes in regulations
or future regulations. A technology was considered proven if (a) it is commercially installed and
processing wastewater sludge successfully at full scale at one or more facilities and (b) it has
been in operation for 2 to 3 years.
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Environment criteria considered the amount of energy required to operate the system. This
included electrical and fuel demands. In addition, air quality effects of each technology were
evaluated.
Community/neighbors considered the visual and odor impacts from each alternative. Visual
impacts were based on how the technology and associated equipment and buildings fit the
landscape of the RWQCP. Odor impacts were based on emissions from the process or related
activities (e.g., hauling).
Table 7.2 summarizes the initial qualitative screening results based on the above criteria (detailed
results are provided in Appendix L).
Based on the results of the screening, plasma arc assisted oxidation, pyrolysis, dried pellets as
cement kiln fuel, and composting on-site will not be considered for further. Some of the reasons
for the decisions on whether to eliminate or further consider a process are listed below:
There are no existing plasma arc assisted oxidation or pyrolysis installations that
commercially process wastewater sludge. However, these processes should be watched as
emerging technologies that could potentially be implemented in the future.
The local cement kiln is not interested in using dried sludge pellets as fuel. There is not a
developed market for pellets and drying is an expensive process to implement.
There is not enough room at the RWQCP for on-site composting.
Gasification appears to be a promising process for wastewater solids. At the May 2012
IFAT Conference in Munich Germany (16th International Symposium on Water,
Wastewater, Solid Waste and Energy), there were 15 vendors advertising gasification
processes and there is a lot of interest in the wastewater field in furthering the application
of this technology on wastewater solids. Understanding gasification’s emerging level of
development and proper application represents both an opportunity and a challenge as this
technology improves for sewage sludge treatment.
Therefore, the viable alternatives remaining are the baseline (MHF) and Alternatives 1, 3, 5, 8, 9,
and 10, that is:
Thermal Conversion: MHF (Baseline), FBI (Alternative 1), and Gasification
(Alternative 3)
Anaerobic Digestion (Alternative 5)
Regional Options: Composting Off-site (Alternative 8), SJ/SC WPCP (Alternative 9) and
BAB2E Facility (Alternative 10)
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Table 7.2 Summary of the Initial Qualitative Screening Evaluation
Treatment
Process Treatment Environment
Community/
Neighbors Cost
Thermal
Digestion
Anaerobic
Digestion
Drying
Regional Options
However, several of these alternatives are not discrete, mutually exclusive alternatives. Namely,
composting off-site would require digestion prior to hauling off-site to a composting facility.
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Similarly, anaerobic digestion alone is not a full alternative as a final disposition option must be
included. Based on the discussion in section 7.3 and the longevity of the disposition options
shown in Table 7.1, we have combined off-site composting with the anaerobic digestion
alternative.
The alternatives eliminated from further consideration could be evaluated in the future when
more information is available and more interest develops (i.e., market develops for biosolids
pellets).
7.6 COMPARISON OF VIABLE ALTERNATIVES
This section presents a comparison of the viable biosolids alternatives for the RWQCP and the
assumptions used in their development.
7.6.1 Assumptions for Evaluating the Viable Biosolids Alternatives
The following assumptions were used in developing and analyzing the plant-wide biosolids
alternatives:
The baseline of using the existing MHF facilities is not a viable long-term option, as the
facility is near or at the end of its useful life. The baseline option assumes continuing with
the required maintenance (including a seismic retrofit to the building) to keep the facility
operational until a new solids facility can be constructed (before or by 2025).
All solids alternatives are sized for projected influent flows in year 2062 assuming
secondary solids production from an activated sludge process with nitrification and
denitrification – a worst case scenario of 94,000 ppd of thickened solids for digestion
alternatives and 91,000 ppd of thickened solids for all other alternatives.
All solids facilities are sized using reliability/redundancy criteria similar to the existing
MHF operation, such that the processes can operate with one unit out of service during
annual average conditions to allow for routine maintenance and cleaning.
Continued use of gravity thickeners and belt filter presses for thickening and dewatering,
respectively. Costs are included for replacement of dewatering equipment.
Costs basis as established in the Basis of Cost Technical Memorandum.
While many digestion options are available, this evaluation considers mesophilic digestion
in a standard-shaped configuration, as representative of footprint and cost required. Other
digestion options would be considered during the preliminary design phase if digestion
were to be implemented.
Cogeneration is included for the digestion alternative assuming use of reciprocating
engines with a gas scrubbing and gas exhaust system to comply with future emission
requirements.
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Gasification costs are based on quotes from MaxWest, the company running the Sanford,
Florida installation. MaxWest does not sell the gasification units, but instead sells a service
of solids processing for an annual fee. The City would be responsible for providing a
location, utilities, and piping of dewatered sludge to the gasification process. Capital costs
included dewatering facilities, a building, and utility connections for the vendor supplied
gasification system.
Demolition costs were assumed for the existing MHFs and incinerator building for the
alternatives that include digestion, gasification, and FBI as the new facilities would be
sited in the same location.
Operation and maintenance (O&M) costs are based on 2015 dollars. Assumed annual
replacement costs of equipment based on 5 percent of the original capital costs. Electricity
based on 50 percent City of Palo Alto Utility (CPAU) green power mix ($0.017/kWh) and
50 percent CPAU standard power mix ($0.14421/kWh).
7.6.2 Alternatives Evaluation
The alternatives evaluation was narrowed to a baseline and five alternatives based on the results
in Section 7.5. For alternatives costing, the final disposition must be incorporated into the
alternative. The alternatives include thermal conversion with landfilling of the ash; anaerobic
digestion with beneficial use to an off-site composting facility or the BAB2E facility; and
sending solids to SJ/SC WPCP. Thus the alternatives to be evaluated further are:
Baseline – Continued use of the MHF until the useful life is exceeded, with landfill
disposal of the ash.
Alternative A – Convert to FBI with landfill disposal of the ash.
Alternative B – Convert to gasification with landfill disposal of the ash.
Alternative C – Anaerobic Digestion with off-site beneficial use (either land application or
composting).
Alternative D – Send dewatered solids to SJ/SC WPCP for digestion and disposition.
Alternative E – Send dewatered solids to BAB2E.
Table 7.3 presents the solids production, gas production, and energy consumption for each of the
alternatives based on annual average conditions in year 2045. In addition, Table 7.4 presents the
gas production, and energy consumption for each of the alternatives based on annual average
conditions in year 2019 when the solids alternative is anticipated to be on-line.
The following sections present additional information on the alternatives.
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7.6.3 Net Present Value
Table 7.5 shows the net present value analysis for the baseline and each of the five alternatives
evaluated, respectively. The evaluation includes O&M costs, capital costs (based on millions of
2015 dollars), net present value, annualized cost, and cost per dry ton for treatment and
disposition. All capital and O&M costs were developed based on the procedures and guidelines
presented in the Basis of Cost Technical Memorandum shown in Appendix M. The details of
these costs are provided in Appendix N.
Table 7.5 Biosolids Treatment and Disposition Alternatives Cost Estimates
(1)
Treatment Alternative(2)
O&M
Costs(3)
($/yr)
Capital
Costs(4)
($)
Net Present
Value(1)
($)
Annualized
Cost(5)($)
$/Dry
Ton(6)
7.6.4 Greenhouse Gas Emissions Analysis
A greenhouse gas (GHG) emissions analysis of each alternative operating in 2045 was
completed and compared to baseline (existing MHFs) conditions using Carollo’s GHG emissions
estimating tool. A summary of the detailed analysis is provided in this section. Details of the
GHG analysis is provided in Appendix O.
The following assumptions were used in developing the GHG emissions analysis for the
alternatives:
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GHG emissions included in the analysis are a result of electricity or natural gas
consumption for necessary operations onsite. Operations emissions at an off-site location
(i.e., SJ/SC WPCP and BAB2E) were not
GHG emissions estimated for this evaluation include the direct (fuel combustion at the
RWQCP, as well as sewage sludge incineration) and indirect (electricity use at the plant,
energy use to produce polymer and natural gas consumed on-site, and fuel combustion for
biosolids and chemical hauling) emissions generated by RWQCP operations.
included in this evaluation.
Electricity related emissions are estimated using an emission factor of 400 lbs per
megawatt-hour (MWh) of fossil fuel based electricity per the City’s request. This emission
factor was determined by the City of Palo Alto Utilities (CPAU) Department. CPAU’s
existing electricity is generated from a mix of 81 percent renewable energy sources and 19
percent fossil fuel sources. In 2045, it is assumed that only 9 percent of annual electricity
consumption is fossil fuel based. Therefore, only 9 percent of the entire demand is
evaluated at 400 lbs per MWh for the alternatives comparison.
Emissions resulting from incineration of sewage sludge are estimated per the methods and
emission factors provided in the 2006 IPCC Good Practice Guidance and Uncertainty
Management in National Greenhouse Gas Inventories. Since there are no data available for
methane and nitrous oxide emissions from U.S. incinerators, default values for methane
and nitrous oxide emission factors are used. The uncertainty ranges are estimated to be
±100 percent or more.
Trucks hauling biosolids and chemicals are assumed to achieve 5.65 miles per gallon on
average consuming California Diesel fuel.
Table 7.6 and Figure 7.8 show the results of the GHG emissions analysis for the biosolids
treatment alternatives in terms of carbon dioxide equivalent (CO2e) emissions. The ranking of
alternatives based on estimates of the GHG emissions are largely affected by the incineration of
sewage sludge estimates. FBI incineration is shown in Table 7.5 as having a higher annual GHG
emission than MHF due to the evaluation of the baseline (MHF) at current solids loading rates
and the other alternatives at the 2045 solids loading rates. The last column in Table 7.5 attempts
to normalize the alternatives by showing the emissions per dry ton. Even without the emissions
estimates from incineration, the use of natural gas in the existing MHF causes the GHG emission
estimates to be higher than the other alternatives per dry ton.
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7.6.5 Sensitivity of Biosolids Alternatives to Changes in Assumptions
The solids alternatives have been compared using the high end of solids production from the
various liquid treatment alternatives being considered. There are several things that could change
the amount of solids to be treated and the composition of those solids, namely the use of
chemically enhanced primary treatment, different liquid treatment alternatives and the addition
of FOG, Food Waste, and Other Import Material. In addition, the ranking of alternatives based
on costs may change with a different assumption of energy costs in the future. Each of these
items is discussed below in terms of the sensitivity of the solids alternatives sizing and costs
presented.
7.6.5.1
For the alternatives compared above, an estimate of 94,000 ppd (for digestion) and 91,000 ppd
(for thermal processing) of solids generated from the primary and secondary systems was used
for sizing and developing costs for digestion and non-digestion alternatives, respectively. These
estimates were based on 2062 flows and assuming that a TN<3 mg/L was required. One idea
presented by the City’s Technical Advisory Committee of Perry McCarty and Craig Criddle
(professors at Stanford University) was to use chemical addition in the primary sedimentation
tanks to maximize the solids sent to a digestion facility that could produce methane gas. While
chemically enhanced primary treatment (CEPT) would increase removal rates in the primary
treatment process, it is anticipated that the overall solids sent to the digesters would remain about
the same. The composition of the sludge would change slightly as it would contain more primary
sludge, which has a higher volatile solids content. Based on a sensitivity analysis, it is estimated
that the addition of chemicals to the primaries would only increase gas in an anaerobic digester
by approximately 5 percent. Additional testing of the primary and secondary solids streams and a
pilot of CEPT would be required to confirm this potential benefit. The impacts of CEPT are
potentially more significant to the secondary treatment process as the activated sludge system
becomes less loaded. However, if the RWQCP is required to reach a TN<3 mg/L, adding
chemicals to the primaries would reduce a necessary source of carbon to the secondary process.
The impact of CEPT on the liquid treatment processes are discussed in Chapter 8.
Enhanced Primary
7.6.5.2
Depending on the liquid treatment process utilized at the RWQCP in the future, different
amounts of solids will be produced. For the biosolids treatment alternatives compared in this
chapter, we used a solids generation rate from the primary and secondary processes that was on
the upper end of the future liquid treatment alternatives for sizing and developing costs. The
range of anticipated solids from the primary and secondary processes for all the liquid treatment
alternatives (discussed in Chapter 8) are 94,000 ppd (for digestion) and 91,000 ppd (for thermal
processing) TS. Implementation of a liquid treatment alternative with lower solids production
Liquid Treatment Alternatives
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would mean that the solids facilities could potentially be downsized. Alternatively, the RWQCP
may wish to conservatively size solids facilities to be able to handle a variety of potential future
liquid treatment options. For example, if digesters were implemented as sized in this chapter, the
effect of using one of the liquid treatment alternatives with a lower projected solids generation
rate is that the HRT in the digestion process would be longer by up to 4 days and the final
disposal tonnage of either ash or biosolids would be reduced by 20 to 25 percent. Gas production
and energy generation would also be reduced by 20 to 25 percent.
7.6.5.3
Food waste such as food scraps from the restaurant industry, produce or fish markets, school
cafeterias, etc., is an attractive high-energy feedstock for anaerobic digestion systems. However,
scraps from residential communities are currently not a viable source due to limitations in
collection and separation.
FOG, Food Waste, and Other Import Materials
With proper training and participation, food scrap collection from sources outside the residential
community is viable. Typical sources include restaurants. The material would be hauled to a pre-
processing facility located outside of the wastewater treatment plant. The waste would be
screened to remove packaging materials, utensils, or other inorganic objects. After grinding the
scraps to a uniform mixture, they would be hauled to the wastewater facility.
At the wastewater facility, processed food waste would be pumped from the delivery truck to
storage tanks. The food waste would need to be conditioned to 10 percent solids content prior to
being fed to the anaerobic digesters, which would increase methane gas production. Based on
testing at the East Bay Municipal Utilities District, the methane potential of food waste is about
367 cubic meters/ton (13,000 cubic feet/ton).
7.6.5.3.1 Impacts on Addition of FOG and Food Wastes at RWQCP
Food waste streams (including FOG) were included in this evaluation to determine the effect on
digester sizing, ability to achieve the required HRT, and digester loading rates. The City
currently accepts 46,167 gallons per month of FOG that is added at the head of the plant. If
digesters are selected as the preferred solids treatment alternative, FOG can be added directly to
the digesters. On average, this could provide 770 lbs of total solids per day and 740 lbs volatile
solids per day. In 2062, the FOG to be sent to the RWQCP is estimated at 130,000 gallons per
month. On average, this would provide 2,200 lbs of total solids per day and 2,100 lbs volatile
solids per day.
The potential for food and food processing waste is even greater. The City-Wide Waste Stream
Review projected that 18,000 tons per year of compostable waste could be diverted to the
RWQCP. Of the 18,000 tons per year of compostable waste identified, 13,000 tons is generated
from commercial sources and 5,000 are generated from residential sources. Of the 13,000 tons
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per year only 7,758 tons are food waste, the remainder consists of leaves and grass, compostable
organics, compostable paper, prunings and trimmings and branches and stumps.
As previously mentioned, only food waste from commercial sources are viable for collection.
For the purposes of this LRFP, it was assumed that 7,758 tons per year of food waste could be
currently sent to the RWQCP and this would increase proportionally to the flow increase to the
plant. On average, this would provide 42,500 lbs of total solids per day and 36,100 lbs volatile
solids per day. In 2062, the food waste to be sent to the RWQCP is estimated at 13,094 tons/year.
On average, this would provide 71,800 lbs of total solids per day and 61,000 lbs volatile solids
per day.
The impacts of adding FOG and food waste to the RWQCP solids processes is that for a given
digester size, HRT is reduced, the volatile solids loading is increased and the gas production and
energy generation is also increased. Table 7.7 shows the impacts of FOG and food waste on the
digesters at 2035 and 2062 wastewater influent flows. The HRT shown in Table 7.7 is based on
building three digesters, with typical operation of two in service. To meet Class B biosolids
designation a 15-day HRT is required. Class A biosolids are created by post digestion treatment
usually involving composting or heat drying. This sensitivity analysis showed that the addition of
FOG and food waste would require that all digesters be in service in 2062 to allow for receiving
the maximum estimated quantities of FOG and food waste. If a digester needed to be taken out of
service during this build-out condition, the RWQCP would have to stop accepting FOG and food
waste to prevent the HRT from dropping too low or build additional or larger digesters.
Table 7.7 Sensitivity Analysis of FOG and Food Waste Addition
Treatment
Alternative
Wastewater
Volatile
Solids
(ppd)
FOG
Volatile
Solids
(ppd)
Food
Waste
Volatile
Solids
(ppd)
HRT
(days)
VSS
Loading
Rate (lbs
VSS/ ft3-day)
Gas
Production
(SCFM)
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7.7 PROMISING TECHNOLOGIES
As discussed in earlier sections, there are several technologies that look promising, but are not
sufficiently developed for confidently sizing and costing alternatives. The approach for the LRFP
is to develop a list of promising technologies to watch and potentially include when preliminary
design efforts are underway to finalize technology and design concepts. The City should also
seek to pilot test these new technologies to determine whether they would be suitable for the
RWQCP or participate in pilot testing that is scheduled to take place at neighboring facilities
such as SJ/SC WPCP and the BAB2E regional facility.
7.7.1 Thermal Conversion Processes
There are several thermal conversion processes that look promising for future application in
biosolids treatment but that have no real experience in this field to date. These include pyrolysis
and plasma arc assisted oxidation. Even gasification is a newer process for wastewater solids that
is just starting to get installations in wastewater applications in the U.S. All of these processes
should continue to be watched and evaluated further when they have been proven at other
wastewater treatment plant locations. Alternatively, the RWQCP can participate in the regional
efforts to examine these types of processes, such as BAB2E. The City of San Jose Solid Waste
Division is also investigating the feasibility of doing a gasification pilot with both solid waste
and sewage sludge.
Installation lists for gasification and pyrolysis thermal conversion processes are included in
Appendix R. As discussed above, as more data becomes available, these processes should be
considered further.
7.7.2 Microscreen-Gasification Process
M2 Renewables (M2R) is developing a system that comprises a belt screen filter coupled with a
gasification process. Raw wastewater flows into the belt screen filter, which removes the solids
from the water. Approximately 55 to 70 percent of the total suspended solids (TSS) and
biological oxygen demand (BOD) are removed by the screen. The solids are dewatered to
between 30 and 35 percent and conveyed to the gasification process. Effluent is discharged to the
downstream secondary treatment process. Due to the projected high BOD removal rates across
the microscreens, downstream secondary treatment systems would be less loaded and could
potentially either be downsized, or run at lower energy demands due to less air required for BOD
removal.
The dewatered solids and secondary solids are combined, pretreated, and mixed. Pretreatment
consists of sorting, sizing, and optimizing the moisture content of the combined stream. The
pretreated mixture is conveyed to the gasifier by an auger in an oxygen-free environment. The
gasifier uses electricity to induce a thermal energy capable of generating reaction temperatures of
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1200 to 1700 degrees Celsius. Oxygen is controlled within the reactor for efficient syngas
production. A scrubbing system is used to clean the syngas prior to use.
M2R has one microscreen operating system at the City of Adelanto, CA wastewater treatment
plant (a 1.5 mgd plant), but no commercially operating gasification system. A M2R
demonstration test was conducted at the City of Palo Alto between February 13th and 15th, 2012.
The demonstration unit was a MS-28 Microscreen with 160 and 105 micron meshes/28 inches
wide belt. During the test period, the average TSS and BOD removal rates were 82% and 55%
respectively and a fresh solids production of up to 56% was achieved. This test data indicates
that installation of the M2R Microscreen system could have benefits to the City’s RWQCP such
as increasing the plant TSS and BOD removal rates, reducing primary sludge disposal costs,
reduction of aeration requirements, reduce operational costs and lower odor generation.
However, the requirement of a nitrogen limit in the future would require that BOD removal be
minimized since the BOD is required downstream in the liquid treatment process for a
denitrification step.
M2R has a batch test gasification unit operating in Munich, Germany, which processes a variety
of wastes, including sewage sludge. In addition, they have plans to construct a five ton per day
test unit at their manufacturing facility in Carson, Nevada. The purpose of this testing facility is
to demonstrate the gasification process capabilities, determine the power generation potential,
and design optimization based on client provided sludge samples.
Because the microscreen has limited operating experience, and the gasifier has no operating
installations, development of these technologies will be closely tracked but not included as a
solids alternative for this study location.
7.7.3 Fuel Cells
Fuel Cells are gaining interest in California for facilities with digester gas as a way to produce
energy with low emissions. Fuel cells are electrochemical devices that combine hydrogen from
the digester gas and oxygen from the air to produce electricity and recoverable heat with little
emissions. Recent installations have had difficulty with the required fuel conditioning systems. If
the RWQCP decides to implement digestion, fuel cells should be considered, particularly if
additional FOG or food waste will be fed to the digester.
7.8 SUMMARY AND RECOMMENDATIONS
A summary of the major considerations and the impact on the overall strategic plan for the LRFP
are presented in Table 7.8.
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Table 7.8 Biosolids Treatment Alternatives Summary of Considerations
Future Considerations Impact on Strategic Plan
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Table 7.8 Biosolids Treatment Alternatives Summary of Considerations
Future Considerations Impact on Strategic Plan
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7.8.1 Recommendations
Based on the information presented in the sections above, the following is recommended for the
LRFP:
1. Continue to use the existing incinerators until they can be retired and a new solids handling
facility and disposal option implemented. Retire incinerators based on following
conclusions:
a. Units are difficult to maintain as they age; the steel structure holding the refractory
bricks together is stressed and rusting from within. The steel skin of the furnace will
need to be completely replaced to ensure heat remains within the furnace. Existing
efforts have focused on patching and rewelding problem areas that have stressed due
to decades of thermal stress.
b. Incinerators may experience damage from an earthquake (per Chapter 5) rendering
the incinerators nonfunctional. A backup ash hauling contract needs to be in place.
The complex logistics and costs to implement a backup contract while trying to
repair a 40-year old furnace after a major earthquake are problematic.
c. EPA air regulations are becoming stricter for older incinerator units. The existing
incinerator units cannot be upgraded more than 50 percent of their original
construction cost (i.e., planned obsolescence in regulations). Regular 5-year EPA
reviews of emission limits and the threat of lawsuits to force stricter emission limits
remain a potential issue. Reacting to such regulatory changes or lawsuits on a
compressed regulatory compliance timeline will greatly increase the capital costs and
may result in sunk assets (e.g., expensive air pollution control equipment that will be
used only for a few years until a new solids handling system is implemented).
d. The existing incinerators produce ash that is hazardous waste due to the soluble
copper levels exceeding a state of California limit at 25 ppm. While ash hauling costs
and state and local hazardous waste fees for the RWQCP’s hazardous waste ash are
relatively low compared to operating costs and the debt service on a new project,
moving away from production of a hazardous waste is consistent with the City’s
goals of minimizing production of hazardous waste.
e. The existing furnaces are not good candidates for energy recovery potential on the
exhaust flue gas stream; this is inconsistent with the plant’s long term goal of energy
reduction. Upgrade potential for the existing units is limited to minor optimization
projects.
f. The Solids Incineration Building’s foundation piles are not expected to perform well
in a design earthquake (see Chapter 5). Approximately $0.55 million is needed to
upgrade this building’s foundation piles. Retiring the incinerators will make
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maintenance and capital re-investment decisions on the incinerator clear and remove
outdated infrastructure from the RWQCP systems.
2. Initiate a Solids Facility Plan
a. Develop the scope of a Solids Facility Plan to choose a technology and onsite or
offsite option for the replacement technology for the RWQCP’s solids handling
systems
b. Given the issues foreseen regarding disposition of solids with a limited future for
landfilling and land applying biosolids, beneficial uses locally would provide the
ability to control the RWQCP’s destiny. However, the lack of a local market and
space on-site limit options to off-site beneficial use or privatization. For the purposes
of the LRFP, proceed with detailed evaluation (including layouts) for the following
solids alternatives:
a) Alternative B – Onsite gasification
b) Alternative C – Anaerobic Digestion with off-site beneficial use (either land
application or composting).
c) Alternative D – Send dewatered solids to SJ/SC WPCP.
d) Alternative E – Send dewatered solids to BAB2E.
c. Enter into further discussions with the SJ/SC WPCP to determine conditions of an
agreement to send solids to their facility. In addition, participate in San Jose’s
piloting of gasification, if that project proceeds.
d. Consider joining the BAB2E consortium and participate in their ongoing evaluation
of promising technologies.
e. If the City and Partner decision makers have a strong preference to keeping solids
treatment within the control of the RWQCP, begin a preliminary design study for
anaerobic digestion facilities to evaluate in more detail the advantages and
disadvantages of different anaerobic digestion configurations.
f. If an anaerobic digestion process is implemented on-site, consider efforts to develop
a marketable product and local users through either drying or composting.
g. Investigate in greater detail the installations and operating history of gasification
systems, including performance, reliability and operational challenges. While the
United States has very limited experience with gasification of biosolids, there are
existing gasification systems in the US utilizing other feedstocks including wood
wastes and municipal solid wastes. Abroad, especially in Europe and Japan,
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numerous entities have gasification systems utilizing various feedstocks, including
wastewater solids.
3. Develop backup plans for raw sludge disposal with a local waste hauler should the furnace
systems fail to operate.
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Chapter 8
LIQUIDS TREATMENT ALTERNATIVES
DEVELOPMENT AND SCREENING
8.1 PURPOSE AND OVERVIEW
The purpose of this chapter is to discuss the liquid treatment alternatives that can provide
reliable treatment at the RWQCP and meet current and potential future regulatory requirements.
More specifically, the RWQCP must accommodate the projected flows over the 50-year
planning horizon (through 2062) as well as meet regulatory requirements for effluent discharge,
reuse, air and biosolids. This chapter shows the results of the qualitative and quantitative
screening of the liquid treatment alternatives.
8.2 BASIS FOR EVALUATION/PLANNING CONSIDERATIONS
8.2.1 Projected Flow and Loads
Influent flows and loads have been projected through the year 2062, as presented in Chapter 3.
Based on population projections and current per capita flow rates, the projected average dry
weather flow (ADWF) for 2062 is 34.0 million gallons per day (mgd) and the maximum month
flow (MMF) is 41.1 mgd. An alternate flow projection was developed using anticipated flow
reductions from conservation and building code changes provided by member agencies and
resulted in a projection of 28.6 mgd ADWF and 34.6 mgd for MMF. Influent loadings are not
anticipated to change with the alternative flow condition and are projected to be 78,870 pounds
per day (ppd) for TSS and 72,874 ppd for BOD at maximum month flow.
The alternatives being evaluated in this chapter to meet future regulations are sized primarily
based on loading, and therefore, the alternate flow projection does not influence the alternatives.
For the purposes of this study, the peak wet weather flows were assumed to be 80 mgd. For a
more detailed analysis of the peak wet weather flow, a comprehensive estimate of wet weather
flows (e.g. collection system model) should be developed for all the contributing areas to
determine the projected flows during wet weather events. On going and planned efforts to
reduce infiltration and inflow (I&I) need to be incorporated into this wet weather estimate.
Additionally, as conservation measures will not reduce the peak wet weather flow that drives
the hydraulic capacity sizing of the plant, the alternate projections will also not reduce the need
for other common facilities.
8.2.2 Regulatory Requirements
The regulatory scenarios for future treatment compliance were developed in Chapter 6. The
future regulatory scenarios that would affect liquid treatment processes are the potential
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regulations for nutrient reduction (in the form of total nitrogen limits) and emerging
contaminants, including pharmaceuticals, personal care products and endocrine disruptors.
Table 8.1 shows the current and future potential regulatory requirements that would require
additional liquids treatment facilities along with estimated dates for when the regulations would
be required.
Table 8.1 Existing and Potential Future Regulatory Requirements
Parameters Units
Current Monthly
Limits
Potential 2035
Limit
Potential 2050
Limit
Nutrient limitations are considered the most likely regulation to be imposed in the near future.
Current research efforts are focusing on nutrient impacts to the Bay, which will inform policy
makers. The Regional Water Quality Control Board recently issued a technical report order
requiring submittal of information on nutrients in wastewater discharges. This order is to aid in
the development of nutrient water quality objectives for the San Francisco Bay estuary. It is
unknown exactly how nutrients may be regulated in future. The U.S. Environmental Protection
Agency (EPA) has indicated in general, that requiring monthly nutrient limits would be
impracticable though the recent federal and state framework is built around annual nutrient
limits (e.g. the Chesapeake Bay, Wisconsin, Colorado). However, current NPDES discharge
permits issued by the State of California through permit authority by Regional Water Quality
Control Boards, typically structure effluent limitations with monthly, weekly, and daily limits.
Therefore, all alternatives discussed in this chapter are sized based on facilities needed to meet
effluent limits during the maximum month flow. If annual limitations are anticipated instead of
monthly limitations, there would be a good opportunity to plan for reduced capital costs.
8.2.3 Site Considerations
The RWQCP has a very compact site that is already filled with existing treatment processes and
underground piping that makes placement of new treatment facilities challenging. As discussed
in Chapter 7, space for new solids facilities has been reserved near the center of the plant. Due
to adjacent neighbors (such as the nearby business parks and Palo Alto airport), odors, noise,
emissions, truck traffic, and visual impacts are a concern. However, any new facilities need to
be constructed while existing processes are operating. Therefore, new liquid treatment facilities
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are primarily located at the periphery of the plant in areas where few existing facilities are
located. Figure 8.1 shows the existing facilities layout.
8.2.4 Alternatives Development Process
The evaluation criteria and process for comparison of alternatives were developed in Chapter 2.
The evaluation process consists of two levels of evaluation: an initial qualitative screening and a
more detailed quantitative evaluation.
In developing the liquid treatment alternatives, the LRFP project team met on several occasions
and presented the alternatives to the stakeholders twice. In May 2011, the liquids treatment
alternatives were presented to the stakeholders for the first time in a public meeting. At this
meeting, each alternative was briefly presented along with its general benefits and
disadvantages. During a March 2012 public meeting, the liquid treatment alternatives were
presented in greater detail with descriptions of costs and greenhouse gas emissions for each.
Input was taken at each of these public meetings and used to develop the overall
recommendations presented herein.
8.3 SUMMARY OF EXISTING LIQUIDS TREATMENT FACILITIES
AND FUTURE NEEDS
As described in Chapter 4, the existing liquid treatment processes include screening, settling in
primary clarifiers, biological treatment through fixed film reactors and aeration basins, settling
in secondary clarifiers, filtration in dual media filters and disinfection with ultraviolet light (see
Figure 8.2). Each process performs key steps in the wastewater treatment process:
Preliminary Treatment (Headworks):Remove debris, rags, and grit that clog or cause
wear on downstream equipment and processes.
Primary Clarifiers: Remove readily settled and floatable solids.
Fixed Film Reactors (Trickling Filters): Remove a large portion of the carbonaceous
BOD.
Aeration Basins: Remove additional carbonaceous BOD, inorganic compounds, and
ammonia.
Secondary Clarifiers: Remove additional carbonaceous BOD in the form of colloidal
solids and ammonia-nitrogen in the form of settable biomass.
Dual Media Filters:Remove residual solids and BOD to meet final effluent limits.
Disinfection:Destroy or inactivate pathogens.
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The current biological treatment process is one method of meeting the current discharge permit
requirements, particularly for BOD and ammonia. However, as described in Chapter 5, there are
certain recommended improvements necessary for the RWQCP to continue to reliably meet the
current discharge requirements in the near and intermediate future. Additionally, in the future,
more stringent discharge permit requirements for total nitrogen and/or ammonia may require
further modifications and/or new treatment processes.
8.3.1 Preliminary Treatment
As discussed in Chapter 5, the useful life of the headworks facilities will be exceeded during the
50-year planning horizon. For the purposes of the LRFP, construction of new headworks is
recommended that would include influent pumping, grit removal and screening to remove rags
that clog downstream equipment. A preliminary design is required for a more detailed
evaluation of the grit and screening options. For the purposes of estimating costs, a vortex grit
removal system and 3/4 inch screening was assumed.
8.3.2 Primary Treatment
While the primary sedimentation tanks need rehabilitation, they are sufficiently sized to meet
future treatment needs. Options that could be considered are use of Chemically Enhanced
Primary Treatment (CEPT) or use of microscreens.
CEPT requires the use of chemical coagulants to improve settling of solids in the primary
process. While use of CEPT could decrease loading to the downstream secondary processes,
when and if future regulations require total nitrogen removal, CEPT would remove too much
carbon (as carbon is needed for total nitrogen removal) and not be a good choice for liquid
treatment. If the secondary processes were capacity limited, CEPT would be a good interim
solution, but at this time, there is no need to take on the additional operation and maintenance
costs for CEPT.
The use of microscreens in place of primary treatment is a newer technology that is showing
promise for providing an equal level of treatment. However, due to the large peak wet weather
flows experienced at the plant (up to 80 mgd), a large number of screens would be required. At
this time, since primary sedimentation tanks already exist at the RWQCP, it does not make
sense to switch to microscreens. However, this technology should be watched for potential
future implementation, particularly if found to have an advantage for certain solids alternatives.
8.3.3 Secondary/Tertiary Treatment
The existing secondary and tertiary treatment system is adequately treating the wastewater to
meet the existing discharge requirements. Chapter 5 identified rehabilitation needs for the fixed
film reactors, aeration basins, secondary clarifiers and the dual media filters. In general, these
facilities have adequate capacity and can continue to provide sufficient treatment. The existing
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fixed film reactors are only required for one of the liquid alternatives, but have a rated capacity
that is slightly less that the estimated build-out flow. Although bypassing is an option, for
continued use through 2062, the fixed film reactor units will need to have all the media replaced
as part of the rehabilitation effort, to ensure that these units reliably operate at their maximum
efficiency. Therefore, the costs for the fixed film reactor rehabilitation as part of the liquid
treatment alternatives includes a total media replacement.
The existing ultraviolet light disinfection facilities were constructed in 2010 and therefore are in
excellent condition and have adequate capacity in the near future. Where improvements to the
secondary and tertiary processes would be required is in meeting new regulatory requirements.
The existing facilities were not designed to remove total nitrogen or emerging contaminants.
Alternatives to meet new regulatory requirements are discussed in section 8.4 of this chapter.
8.3.4 Recycled Water Facilities
As discussed in Chapter 3, the City of Palo Alto has been producing and supplying recycled
water since the 1980s. A Water Reclamation Master Plan was developed in 1992 that identified
potential users and a Recycled Water Facilities Plan was developed in 2008 that established a
phased implementation program. The Phase 2 system was developed in 2009 to provide water
to Mountain View. The Phase 3 expansion to Palo Alto is being considered but is on hold at the
moment due to concerns over salinity levels. If the City were to implement all the recommended
projects as outlined in the 1992 Master Plan, the annual average and maximum month recycled
water demands would be 4.2 mgd and 9.8 mgd respectively, as shown in Table 8.2.
Based on the capacity of the existing recycled water facilities (approximately 10.8 mgd); both
average and peak month project flows are achievable for the Phase 1-3 and Recommended
project from the 1992 plan. However, as discussed in Chapter 5, some of these facilities (recycle
water filters, chlorine contact basins and recycle water storage tanks) are aging and will need to
be replaced in the next 10-20 years. In addition, the recycled water storage and pumping
facilities are inadequate for the peak hour flow rates anticipated for the Phase 1-3 and the 1992
MP Recommended Projects. Therefore, the storage and pumping facilities will require an
increased capacity to handle peak hour demands. For the purposes of this LRFP, new recycled
water facilities are sited and costs are estimated to be able to serve a peak month flow of
9.8 mgd.
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Table 8.2 Recycled Water Demands in the Near and Long Term
Annual Average Flow
Rate (mgd)
Peak Month Flow
Rate (mgd)
Peak Hour Flow
Rate (mgd)
In addition to the need to replace aging facilities and provide adequate capacity, the recycled
water treatment system may need to be improved in the future to meet more stringent water
quality requirements. Some of the identified recycle water customers have landscaping and/or
facilities that require lower salinity levels than the recycled water currently provides. The City
of Palo Alto and its partner agencies have set a policy goal to meet salinity levels of 600 mg/L
total dissolved solids (TDS) in its recycled water. The RWQCP currently produces recycled
water with TDS levels ranging from 800 mg/L to 1000 mg/L and averaging 917 mg/L. In the
first step towards achieving this objective, the City is implementing source control and is
working with the RWQCP partner agencies to line sewers in an attempt to reduce infiltration of
bay water. If source control proves to be unsuccessful in lowering the salinity to the desired
salinity limits, a reverse osmosis (RO) system may be required. To protect the RO membrane
and improve flux rates, RO processes are always preceded by an ultra-filter or micro-filter
membrane process.
For the purposes of this LRFP, four scenarios were used to size an RO system as shown in
Table 8.3. Costs presented in Section 8.3.6 are based on assuming that source control to
800 mg/L TDS will be effective. Details of the cost for just the RO system with and without
pre-treatment are shown in Table 8.4. An alternative to putting in RO at the RWQCP would be
to either serve users requiring lower salts with a satellite treatment facility located at the point of
use, or with service from other providers (e.g., South Bay Water Recycling, Santa Clara Valley
Water District, etc.) who have already made the investment in RO for their recycled water.
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Table 8.3 Summary of Iterations to Meet Effluent Goal of 600 mg/L TDS
RW flow, peak month,
mgd
Influent TDS Assumptions
RO size,
mgd
TDS,
mg/L Basis
Table 8.4 Summary of RO System Capital Costs in Millions of 2015 Dollars
RO System Design Basis, mgd
With Ultrafiltration
Pretreatment, $M
Without Ultrafiltration
Pretreatment, $M
1.5 43 27
2.5 62 39
8.3.5 Advanced Treatment
Removal of emerging contaminants including endocrine disruptors and pharmaceuticals
requires either a fine membrane process such as RO that eliminates constituents through size
exclusion or an oxidation process such as ozonation. If regulatory requirements in the future
require removal of emerging contaminants for Bay discharge, then adding ozone ahead of the
existing UV disinfection process would provide removal of most constituents and would
increase the efficiency of the UV system by improving UV transmittance. A technical
memorandum describing the recommended ozone process for the RWQCP is included in
Appendix P.
Facilities required would include liquid oxygen tanks, an ozone generator, and an ozone contact
chamber. The ozone would be injected into the water after tertiary filtration and prior to the UV
disinfection.
8.3.6 Support Facilities
As identified in Chapter 5, the existing administration, laboratory and maintenance buildings are
inadequate for the number of staff and space needs for laboratory, and storage needs for
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equipment for normal operations and maintenance. Therefore, new buildings have been
identified for the site including a new Laboratory and Environmental Services Building, which
will house the administration, engineering, watershed protection, IT, and solid waste staff as
well as provide a new laboratory. For the purposes of site planning, it is assumed that the new
Laboratory and Environmental Services Building would be located on the RWQCP site adjacent
to Embarcadero Road. One alternative to a new building on site is to acquire a neighboring
commercial property for the new Laboratory and Environmental Services Building. This would
preserve the limited space on site for future processes. Another option is to expand the
operations building to house the new Lab and Environmental Services. Once the laboratory has
been moved out of the operations building, the operations building will be renovated to provide
additional locker space, operations office space, and a lunchroom/conference room. In addition,
the maintenance building will be expanded to accommodate the need for additional warehouse
space. Preliminary layouts of the new Laboratory and Environmental Services Building,
remodeled Operations Building, and expanded Warehouse developed by Michael Willis
Architects are shown in Figures 8.3, 8.4, and 8.5, respectively.
Based on the condition and lack of space available in the existing blower building, for each of
the liquid alternatives, a new blower building is required. A different sized building is needed
for each of the different alternatives, depending on required blower capacity. Costs and layouts
for these blower buildings are included in each alternative discussed in Section 8.4.
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8.3.7 Summary of Recommendations for Common Facilities
The recommended projects and costs for the common liquid treatment elements discussed in the
earlier part of this section are presented below in Table 8.5 and in Appendix Q.
Table 8.5 Summary of Recommended Project Costs for Common Facilities
(1)
Project Elements Included Reason/Driver
When
needed
Project
Costs(2)
(3)
8.4 LIQUIDS TREATMENT ALTERNATIVES
This section will evaluate alternatives for secondary/tertiary liquids treatment processes to meet
the projected flows, loads, and regulatory scenarios discussed in Section 8.2. There are several
processes that can be used to provide the required level of treatment either alone or in
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combination to achieve the desired effluent water quality. Table 8.6 below shows the list of
secondary treatment processes that are commonly considered along with the constituents they
most commonly remove.
Table 8.6 Secondary Processes to Meet Future Discharge Requirements
Process
Ability to remove
Organics (BOD) Ammonia Total Nitrogen
Suspended Growth
Attached Growth
Hybrid
Anaerobic Treatment
8.4.1 Suspended Growth Processes
Suspended growth systems, whether they are activated sludge or membrane bioreactor (MBR),
have been used and proven not just in California but also at municipal wastewater facilities
worldwide. A list of MBR installations from two major vendors is presented in Appendix R.
Suspended growth systems have also been in use for a number of decades at Palo Alto. The
existing aeration basins are suspended growth technology that have been operating at the
RWQCP since 1972 to provide BOD removal and ammonia removal since 1980.
8.4.2 Attached Growth Processes
Nitrifying trickling filters have been used at numerous locations in California such as the City
of Sunnyvale, the City of Stockton and in the wider United States such as Cities of Reno and
Sparks Truckee Meadows Water Reclamation Facility and the Cities of Englewood and
Littleton Wastewater Treatment Plant. Attached growth systems have also been in use for a
number of decades including at Palo Alto. The existing FFRs are an example of attached growth
technology that has been operating at the RWQCP since 1980 as a set-up stage for the aeration
basin nitrification system.
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Denitrification filters are also being used more extensively to help reduce wastewater treatment
plants’ total nitrogen limits. Denitrification filters have been used by the Cities of Reno and
Sparks Truckee Meadows Water Reclamation Facility for over 20 years to meet effluent total
nitrogen limits of less than 2 mg/L. Lists of denitrification filters from several vendors are
included in Appendix R.
8.4.3 Hybrid of Suspended and Attached Growth Processes
Hybrid systems that consist of both suspended and fixed film growth have been employed in
situations where footprint is limited, as it provides biological treatment with a reduced footprint.
The addition of a fixed film media into an aeration basin provides opportunities for both
suspended and attached growth types of micro-organisms to inhabit the basin and remove BOD
and nitrogen. One such system is the Integrated Fixed-Film Activated Sludge (IFAS) system. A
list of IFAS installations is presented in Appendix R.
8.4.4 Anaerobic Liquid Treatment Processes
Anaerobic systems provide biological removal of organics (BOD) in the absence of oxygen.
Due to the lack of oxygen, anaerobic systems have a lower energy requirement than aerobic
suspended or attached growth processes. Anaerobic processes have the downside of requiring a
longer detention time than aerobic processes, thereby requiring more space. Anaerobic
processes also require a higher temperature and for this reason have been successfully utilized
in warm countries like Brazil, but have not been utilized in the United States. Lastly, anaerobic
bacteria are not able to remove or transform nitrogen in the water, and therefore must be paired
with other processes for ammonia and total nitrogen removal.
8.5 INITIAL QUALITATIVE SCREENING OF ALTERNATIVES
This chapter identifies and evaluates alternative liquid treatment schemes to satisfy potential,
future discharge requirements for ammonia and total nitrogen (TN < 3 mg/L). Six secondary
and tertiary alternative treatment schemes were evaluated:
1. Alternative 1 – Aeration Basins
This alternative will add more aeration basins and subsequently decommission the fixed
film reactors as future total nitrogen limits are imposed. All the carbonaceous removal and
nutrient removal will occur in the aeration basins. Up to ten aeration basins (six new
basins approximately the size of the existing basins) would be required to provided
treatment for the 2062 projections assuming an effluent TN < 3 mg/L. Because of the
limited space available onsite, these basins cannot be located in the same area, but will
need to be spread over the entire RWQCP site. This will make routing to and from the
aeration basins difficult and a hydraulic challenge. Supplemental carbon would be
required to meet the projected TN limits.
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2. Alternative 2 – Membrane Bioreactors
This alternative will use the existing aeration basins and add membranes to replace the
existing secondary clarifiers and dual media filters. The existing aeration basins will be
used for nitrification (conversion of ammonia to nitrate) and denitrification (conversion of
nitrate to nitrogen gas) to meet projected future TN limits. The fixed film reactors would
be decommissioned. Supplemental carbon will be required to meet the projected TN
limits. Buildings will be required to house the new membrane support equipment and new
tanks will be required for the membranes.
3. Alternative 3 – Trickling Filters/Aeration Basins/Denitrification Filters
This alternative will use the existing fixed film reactors (trickling filters) and existing
aeration basins for carbonaceous removal and nitrification. The existing 12 dual media
filters would be converted to denitrification filters and 24 more denitrification filters
would be added. Supplemental carbon will be required for the denitrification filters to
meet the projected TN limits.
4. Alternative 4 – Aeration Basins/ Nitrifying Trickling Filters/Denitrification Filters
This alternative will use the existing aeration basins for carbonaceous removal, the two
existing fixed film reactors would be converted to nitrifying trickling filters (NTFs) and
two new NTFs would be constructed. The existing 12 dual media filters would be
converted to denitrification filters and 24 more denitrification filters would be added.
Supplemental carbon will be required for the denitrification filters to meet the projected
TN limits.
5. Alternative 5 – Integrated Fixed-Film Activated Sludge (IFAS)
This alternative will convert the existing aeration basins to IFAS reactors by adding the
appropriate equipment and media. The IFAS reactors will provide both carbonaceous and
nutrient removal. One additional IFAS reactor will be required along with supplemental
carbon to meet the projected TN limits. The existing fixed film reactors would be
decommissioned.
6. Alternative 6 – Upflow Anaerobic Sludge Blanket (UASB) Reactor/Aeration Basin/
Denitrification Filters
This alternative will use UASB reactors for carbonaceous and solids removal. The new
UASB reactors would replace the primary sedimentation tanks, which would be
decommissioned. Nitrification and residual carbonaceous removal would be provided in
the existing aeration basins, the dual media filters would be converted to denitrification
filters, and 24 more denitrification filters would be added. Supplemental carbon will be
required for the denitrification filters to meet the projected TN limits. Initial estimates are
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that up to eight UASB reactors would be required that are approximately the same size as
the existing aeration basins.
These six secondary and tertiary treatment alternatives developed to meet new regulatory
requirements were initially compared on a qualitative basis for the four major categories of
treatment, environment, community/neighbor impacts, and costs. Treatment criteria considered
included: the process footprint, flexibility for future regulations, and whether the primary
technology is proven. The RWQCP has limited area in which treatment processes can be
constructed. As a result, the overall footprint requirement of each alternative was evaluated.
Flexibility considered the ability for a technology to adapt to anticipated changes in regulations
or future regulations. A technology was considered proven if it is commercially installed and
processing wastewater successfully at full scale in the United States at one or more facilities and
has been in operation for 2 to 3 years.
Environment criteria considered the amount of energy required to operate the system and
chemical use required to meet the regulatory requirements. Community/neighbors considered
the visual and odor impacts from each alternative. Visual impacts were based on how the
technology and associated equipment and buildings fit the landscape of the RWQCP. Table 8.7
summarizes the initial qualitative screening results based on the above criteria.
Based on this qualitative screening and evaluation of layout considerations, Alternatives 1, 4,
and 6 were not carried forward for further evaluation due to excessive land requirements
(Alternatives 1 and 6), unproven processes (Alternatives 6) and no distinct advantage
(Alternative 4). Therefore, the remaining viable alternatives for liquid treatment to meet future
nutrient limits are Alternatives 2, 3, and 5.
8.6 COMPARISON OF VIABLE ALTERNATIVES
8.6.1 Assumptions for Evaluating the Viable Liquids Alternatives
All alternatives assume anaerobic digestion of solids, which requires the consideration of
treating higher ammonia loads due to the recycle stream. As discussed under the common
facilities, a new blower building will be required for each alternative. The costs and energy use
for the new blowers are included in this comparison of the alternatives. All alternatives are sized
for maximum monthly flows to meet total nitrogen limits of TN < 3 mg/l.
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Table 8.7 Summary of the Initial Qualitative Screening Evaluation
Treatment
Process Treatment Environment
Community/
Neighbors Cost
Suspended Growth
Combined Fixed Film Suspended Process
Hybrid (Suspended and Fixed Film Processes)
Anaerobic Treatment
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8.6.2 Alternatives Evaluation and Site Layouts
8.6.2.1
This alternative will add approximately 14 membrane bioreactor trains to replace the existing
secondary clarifiers and dual media filters. The existing aeration basins will be used for
nitrification and denitrification to meet projected future total nitrogen limits. The aeration basins
will be operated at approximately a 5-day solids retention time and a mixed liquor concentration
of between 8,000 to 9,500 mg/l. A supplemental carbon source, such as methanol, will be
needed in the aeration basins to reach the projected low total nitrogen future requirements.
Alternative 2 – Membrane Bioreactors
Although the secondary clarifiers will no longer be used for this alternative, these tanks can be
used for equalization of wet weather flows. A new 10,700 square foot (sf) blower building
would be required to house new blowers with 66,000 standard cubic feet per minute (scfm)
capacity. A proposed plant process schematic and layout for the MBR alternative are shown in
Figures 8.6 and 8.7, respectively.
The use of membranes for MBRs (shown in Figure 8.6) has the advantage of providing a high-
quality water for the entire flow that would meet Title 22 unrestricted reuse requirements. If the
RWQCP should have to implement RO to reduce salts in the recycled water, an additional
membrane process before the RO units would not be needed with an MBR alternative.
Figure 8.6 Membrane Bioreactor (Alternative 2) Process Flow Diagram
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8.6.2.2
This alternative will require rehabilitation of the existing fixed film reactors (trickling filters).
The plant process model was reviewed to determine if the RWQCP could operate with only one
reactor while the other was being rehabilitated; it was determined feasible if the rehabilitation
occurred during the dry season. No new aeration basins are required for this alternative. The
existing dual media filters will be converted to denitrification filters and twenty-four additional
denitrification filters are required. A supplemental carbon source, such as methanol, will be
needed in the filters to reach the projected low total nitrogen future requirements. A new 6,215
square foot (sf) blower building would be required to house new blowers with 60,000 scfm
capacity.
Alternative 3 – Trickling Filters/Aeration Basins/Denitrification Filters
This alternative will continue to operate the facilities similar to current operation where flows in
excess of 40 mgd have to be bypassed around the fixed film reactors due to hydraulic limitation.
The NPDES permit has provisions to allow this bypass during wet weather events with
requirements for sampling to prove that effluent and receiving water limitations are still met.
The process schematic and the layout for this alternative are shown in Figure 8.8 and 8.9,
respectively.
Figure 8.8 Trickling Filters/Activated Sludge/Denitrification Filters (Alternative 3)
Process Flow Diagram
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8.6.2.3
This alternative will require the existing aeration basins be converted to IFAS reactors (to
accommodate the media and equipment) and construction of one additional aeration basin
(IFAS reactor). A supplemental carbon source, such as methanol, will be needed in the IFAS
reactors to reach the projected low total nitrogen future requirements. An additional secondary
clarifier will be needed. A new 11,400 square foot (sf) blower building would be required to
house new blowers with 120,000 scfm capacity. The process schematic and the layout for this
alternative are shown in Figure 8.10 and 8.11, respectively.
Alternative 5 – Integrated Fixed-Film Activated Sludge (IFAS)
Figure 8.10 Integrated Fixed-Film Activated Sludge (Alternative 5) Process Flow
Diagram
8.6.3 Alternative Cost Comparison
The viable liquid treatment alternatives were compared in 2015 dollars using capital costs,
O&M costs and a calculated net present value. Table 8.8 is a summary of the capital and O&M
costs for Alternatives 2, 3 and 5. Details of these costs are presented in Appendix Q. The O&M
costs used in the Net Present Value evaluation consist of the process components associated
with the alternatives and not the whole plant O&M. All capital, O&M, and repair and
replacement costs were developed based on the procedures and guidelines presented in the
Basis of Cost Technical Memorandum shown in Appendix M.
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Table 8.8 Liquid Treatment Alternatives Cost Estimates
(1)
Treatment Alternative
O&M
Costs(2)
($/yr)
Capital
Costs
($)
Net Present
Value(3)
($) Annualized Cost(3)($)
Based on these costs, Alternative 3 has the lowest capital and O&M costs, while Alternative 2
has the highest capital and O&M costs. Alternative 3 is therefore ranked as the most favorable
option based on cost. There are, however, additional considerations that need to be taken into
consideration and these are evaluated below.
8.6.4 Greenhouse Gas Emissions Analysis
A greenhouse gas (GHG) emissions analysis of each alternative was completed using Carollo’s
GHG emissions estimating tool. A summary of the detailed analysis is provided in this section.
The following assumptions were used in developing the GHG emissions analysis for the
alternatives:
GHG emissions included in the analysis are a result of electricity consumption for
necessary operations onsite.
GHG emissions estimated for this evaluation include the direct (process emissions) and
indirect (electricity use at the plant, energy use to produce chemicals, and chemical
hauling) emissions generated by RWQCP operations.
Electricity related emissions are estimated using an emission factor of 400 lbs per
megawatt-hour (MWh) of fossil fuel based electricity per the City’s request. This
emission factor was determined by the City of Palo Alto Utilities (CPAU) Department.
CPAU’s existing electricity is generated from a mix of 81 percent renewable energy
sources and 19 percent fossil fuel sources. In 2035, it is assumed that only 9 percent of
annual electricity consumption is fossil fuel based. Therefore, only 9 percent of the entire
demand is evaluated at 400 lbs per MWh for the alternatives comparison.
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Process emissions are estimated per the methods and emission factors provided in the
2006 IPCC Good Practice Guidance and Uncertainty Management in National
Greenhouse Gas Inventories.
Trucks hauling chemicals are assumed to achieve 6 miles per gallon on average
consuming California Diesel fuel.
Table 8.9 and Figure 8.12 show the results of the GHG emissions analysis for the liquid
treatment alternatives in terms of carbon dioxide equivalent (CO2e) emissions. The ranking of
alternatives based on estimates of the GHG emissions are largely affected by the chemical
production GHG estimates. The details of these GHG emissions estimates are provided in
Appendix O.
Table 8.9 Liquids Treatment Alternatives Annual On-site CO e Emissions in
Metric Tons for 2035
Alternative
Purchased
Electricity(1)
Nitrification/
Denitrification(2)
Effluent
Discharge(2)
Chemical
Production
and
Handling(3)
Annual
GHG
Emissions
IPCC Good Practice Guidance and Uncertainty
Management in National Greenhouse Gas Inventories
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8.6.4.1
Use of a supplemental carbon source is necessary for denitrification if there is not enough
carbon in the wastewater. Meeting low TN limits, such as TN < 8 or 3 mg/l, typically requires a
supplemental carbon source depending on the wastewater. The most commonly used source of
carbon supplement is methanol. However, creation of methanol requires a significant amount of
energy and therefore, methanol use has a relatively high GHG emission rate. Methanol vapors
are also highly explosive and can pose a safety concern. Alternatives to methanol include
ethanol, glycerin/glycerol, high fructose corn syrup, and MicroCg. While these options may
have lower GHG emissions, they are less proven as a carbon supplement having different
denitrification rates and kinetics, and have uncertain impacts to the emissions levels of nitrous
oxide (a high global warming potential GHG) from treatment processes. It is recommended that
when and if the RWQCP has to build facilities for low TN limits, a survey be performed to
determine current use status and performance of other carbon sources.
Alternative Carbon Sources for Denitrification
8.6.5 Sensitivity of Liquids Alternatives to Changes in Assumptions
The potential impact of changes in assumptions on the liquid alternatives evaluation is
discussed in this section.
8.6.5.1
The liquids alternatives have been compared using the baseline projections for flows and loads.
The main condition that could change the amount of liquid to be treated is water conservation.
While water conservation efforts could lead to reduction in flows, the loads are not expected to
change. It is estimated that flow reductions could be as much as 16 percent. However, because
the capital costs for the secondary treatment are more load based, a reduction in flows will not
result in a reduction in the capital costs. The operating costs are impacted by both load and
flows, however for a comparison of the liquid treatment alternatives focused on nutrient
removal, the costs associated with the loads are controlling. Therefore, the reduction in liquids
treatment operating costs due to conservation will be negligible.
Changes in Flow and Load Projections
In the event a residential garbage disposal ban were to be adopted, some organic loading to the
RWQCP would be reduced (note that commercial garbage disposals are already banned in Palo
Alto and Mountain View to avoid sanitary sewer overflows). This could lead to the potential
reduction in sizing of future treatment process needs. Similarly, the implementation of an
upstream satellite treatment facility could reduce BOD loading to the RWQCP. However, at this
time the are no plans for any of the partners to adopt a garbage disposal ban or to implement an
upstream treatment facility, therefore, no reduction in loadings were assumed as part of the
alternative analysis.
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8.6.5.2
Depending on the solids treatment process utilized at the RWQCP in the future, different
amounts of constituents will be recycled back to the liquid treatment process. For the liquids
treatment alternatives compared in this chapter, we assumed that anaerobic digestion was the
chosen solids treatment process since this generated higher ammonia recycle and therefore had a
larger impact on the liquid treatment. Implementation of a solids treatment alternative that is not
anaerobic digestion would mean that the liquids facilities could potentially be downsized and
there could be some savings on capital costs for the future liquid treatment alternatives to meet
low nitrogen limits. By the time regulatory requirements for nutrient reduction are adopted, the
RWQCP should have a decision made on the solids process and either have the project
implemented or well underway.
Impact of Solids Treatment Alternatives
8.7 SUMMARY AND RECOMMENDATIONS
The major finding and recommendation from the liquid treatment alternatives analysis is that
the existing treatment process (Alternative 3) is adequate for the near term and can be modified
to incorporate future regulations. The RWQCP needs to invest in rehabilitating the existing
liquid treatment facilities to keep them in good condition and operating well into the future. As
regulatory limits are developed and promulgated that require reduction of total nitrogen, the
City may want to consider re-evaluating the alternatives to see if new technologies have been
implemented full scale and if costs for equipment (such as membranes) have decreased.
8.7.1 Summary of Recommended Projects
The recommendations for the liquid treatment at RWQCP are as follows:
Preliminary Treatment: Replace the headworks (grit, screenings, and pumping).
Primary Treatment:Rehabilitate existing primary clarifiers.
Secondary/Tertiary Treatment:Continue with existing process until there is a
regulatory trigger. Rehabilitate existing fixed film reactors, aeration basins, secondary
clarifiers, and dual media filters.
Recycled Water: Replace recycled water filters and chlorine contact tank. Provide
storage and pumping to be able to meet peak-hour demands. Continue source control for
salinity reduction and plan for reverse osmosis, if needed.
Advanced Treatment: Leave space for ozonation facilities if a regulatory trigger should
require higher quality effluent for emerging contaminants.
Buildings:Replace the administration building with a new Laboratory and Environmental
Services Building for all office staff and a new laboratory. Rehabilitate the operations
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building and expand the maintenance building and warehouse to include additional
warehouse space.
The recommended layout to reserve space for new facilities is shown in Figure 8.13. A
summary of considerations for future liquid treatment at RWQCP is presented in Table 8.10.
Table 8.10 Liquid Treatment Alternatives Summary of Considerations
Future Considerations Impact on Strategic Plan
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8.7.2 Promising Technologies
In addition to the alternatives considered, there are several promising types of technologies that
should be tracked and evaluated as the technologies mature and are proven in similar types of
applications. The City should also seek to pilot test these new technologies, as feasible, to
determine whether they would be suitable for the RWQCP.
8.7.2.1
Microscreens have the potential to remove as much or more solids than a primary clarifier and
then dewater those solids to a suitable dryness for direct incineration or gasification without
additional thickening or dewatering. However, this technology is still emerging and has not
been installed at any facilities near the size of the RWQCP, and pairing it with gasification has
also not yet been proven full-scale. As mentioned previously in Chapter 7, the City had a
microscreen demonstration unit on site between February 13th and 15th, 2012.
Microscreens
8.7.2.2
Anaerobic treatment for liquid processes would provide biological treatment at a much lower
power requirement than conventional aerobic processes, such as activated sludge. However,
anaerobic liquid treatment has not been successfully applied at full scale in a climate similar to
Palo Alto. Anaerobic treatment also has the disadvantage of providing only BOD treatment and
thus needs to be followed by a process that can remove ammonia and total nitrogen.
Anaerobic Treatment
Upflow Anaerobic Sludge Blanket – The UASB process was evaluated as Alternative 6 in the
discussion in section 8.5 of this chapter. While it was eliminated for both a large footprint and
being an unproven process, if this process becomes proven at cooler temperatures comparable to
Palo Alto, consideration of the process may be warranted due to lower energy requirements of
the anaerobic process.
Anaerobic MBR with Granular Activated Carbon (GAC) - Anaerobic fluidized bed membrane
bioreactors for secondary treatment of domestic wastewater would replace the activated sludge
process. In research studies, the fluidized GAC was found to efficiently prevent membrane
fouling, providing highly efficient wastewater treatment (5 mg/L BOD and zero TSS). Power
usage is estimated to be 50 percent less than conventional MBR processes and methane
production is projected to increase by ~75 percent due to increased digestion of solids in the
anaerobic secondary process.
8.7.2.3
Another promising technology class is use of other types of bacteria or organisms to remove
nitrogen from the wastewater. There is ongoing research and development of several of these
Alternative Nitrogen Reduction Processes
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processes including use of ammonia oxidizing archea (AOA) and the anammox process for
nitrogen reduction.
Ammonia oxidizing archea (AOA) is being used in MBR processes with a low oxygen
environment to reduce energy use in MBR facilities by up to 40 percent while meeting low
nutrient requirements. Anammox uses a select organism for the conversion of ammonia to
nitrate and then to nitrogen gas, skipping the nitrite step. This process eliminates carbon needed
for denitrification (such as methanol) but requires extensive SRTs of 30+ days. Estimates of
energy use for Anammox are in the range of 40 – 60 percent less than conventional activated
sludge. Anammox has been implemented full scale for side-stream treatment of high ammonia
recycled streams.
While both of these processes show promise, additional research is underway and full-scale
applications are still needed to demonstrate reliable treatment.
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Chapter 9
RECOMMENDATIONS AND IMPLEMENTATION PLAN
9.1 INTRODUCTION
This section provides a summary of recommendations for the near, mid, and long term capital
improvement of the Regional Water Quality Control Plant (RWQCP), as well as a phased
implementation plan for the needed improvements over the 50-year planning horizon (2012 to
2062). The projects presented herein have been identified in previous chapters.
Major findings and recommendations of the Long Rang Facilities-Plan (LRFP) fall into four
major categories that drive all facility planning efforts:
1. Capacity needs to accommodate the service area.
2. Replacement and rehabilitation of existing facilities due to aging and inadequate
infrastructure.
3. Future regulations.
4. Policy directives.
9.2 SUMMARY OF NEEDS AND OPPORTUNITIES
The RWQCP is able to treat the existing wastewater flows to meet current effluent discharge
limits and provide recycled water to users. With the exception of the interceptor and outfall
during peak wet weather events, the plant capacity is adequate to meet the anticipated growth in
the service area over the next 50 years provided that there are no regulatory changes. In
Chapters 7 and 8, alternatives were developed for solids facilities in response to changing
incinerator regulatory requirements and for complying with more restrictive effluent discharge
limits (e.g., total nitrogen limits and the potential removal of emerging contaminants).
Findings from treatment evaluations show that continued investment in the incineration process
is not warranted due to its age, condition, and lack of regulatory flexibility. The existing
incinerators are rusting, requiring significant patching and maintenance, continued use of the
building will require seismic improvement, and new regulations continue to be stricter and
difficult to meet. Therefore, a new solids process needs to be selected and implemented for the
RWQCP.
Continued investment in the existing liquid treatment processes is appropriate even in light of
changing regulatory requirements. The existing liquid treatment process performs well and is
flexible for modification to meet future regulatory requirements.
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Therefore, the major recommendation of this LRFP is to rehabilitate and replace existing
facilities that are nearing the end of their useful life, and not switch liquid treatment processes
until there is a regulatory driver. Since a significant portion of the plant was built in 1972 (e.g.,
the Main Structure), many facilities are aging and are in need of significant investment in
rehabilitation or replacement. In addition, increasing use of recycled water in the service area is a
policy directive that will drive the need to provide adequate treatment, storage and distribution
capacity and potentially to remove salts from the liquid stream to better meet the needs of the
recycled water users.
A summary of the RWQCP needs and opportunities is presented in Table 9.1.
9.3 RECOMMENDED PROGRAMS AND PROJECTS
There are near term, mid-term, and long-term recommendations that have been provided
throughout the course of the facilities plan project for maintaining reliable wastewater treatment
for the RWQCP’s customers. This section provides a summary of the recommended projects
organized into the four major categories of capacity, replacement, regulatory and policy
directive. In addition, solids handling was given its own category to reflect that it represents a
significant cost and a detailed decision process. The recommended projects are summarized in
Table 9.2 at the end of this section. The projects were prioritized based on condition and critical
need. Timing assumptions for the recommended projects were developed in conjunction with
RWQCP staff recognizing the need for minimizing multiple projects ongoing at the same time
for ongoing plant operation and due to funding capacity.
9.3.1 Projected Flows/Loads and Capacity Projects
The dry weather flow and loads to the RWQCP were projected based on population projections
from the Association of Bay Area Governments (ABAG) and historical influent characteristics.
While growth may in fact occur at a slower rate than projected, it is prudent to plan for the
population estimates identified for the long-term planning horizon. Similarly, upstream
intervention measures may be implemented that could reduce flow and/or loadings to the
RWQCP, but facilities were evaluated for the full projected flows and loads (especially since
flow reduction measures would not reduce plant loadings).
In general, the RWQCP existing facilities provide adequate capacity for average dry weather
flows anticipated over the planning period. The projection of wet flows was based on historical
events and previous design criteria for peak hour wet flows of 80 mgd. While the RWQCP
appears to have adequate hydraulic capacity to pass peak flows of 80 mgd, evaluation of the
influent sewer (72-inch diameter Joint Interceptor Sewer) and the outfall indicate less than
80 mgd peak capacity. Before deciding to replace these pipelines, a comprehensive estimate of
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Table 9.1 Summary of Needs and Opportunities
Driver Process Need/Opportunity Reason
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wet weather flows (e.g. collection system model) should be developed for all the contributing
areas to determine the projected flows during wet weather events. On going and planned efforts
to reduce I&I need to be incorporated into this wet weather estimate.
Recommendations for the project flows and loads and capacity are based on Chapters 3 and 5 of
this LRFP and include:
Model Influent Sewer Flows
Determine peak wet weather flow: Work with RWQCP partner agencies to understand
sewer flows. Develop a sewer system estimate of the key components of the wastewater
collection system to determine the peak wet weather flows that will reach the RWQCP.
Knowing peak flows will inform sewer rehabilitation options, inform plant capital
improvement sizing for wet weather flows (note: not pollutant loads), and inform effluent
outfall capacity evaluation. Understanding peak flows will also inform infiltration and
inflow management needs, if necessary, to reduce capital sizing.
Inspect and clean influent sewer: Following the development of the sewer system flow
estimate to determine needed capacity, clean and inspect the 72-inch diameter interceptor
sewer to decide the best option for rehabilitation.
Outfall: Following the development of the collection system flow estimate, the capacity
of the outfall should be reviewed. Additionally the outfall should be inspected to
determine rehabilitation needs for the near future.
Continue Source Control and Flow Reduction Efforts
Continue to evaluate options for source control and flow reduction measures for cost-
effective options to reduce costs at the RWQCP for treatment of flow and loads.
Continue traditional source control efforts; source control is more cost effective at
removing some pollutants than traditional wastewater treatment technology (e.g., toxic
heavy metals) and will reduce the potential need for more expensive capital facilities.
Source control for emerging contaminants should be considered before advanced
treatment.
Continue support of water conservation efforts as well as infiltration and inflow reduction
efforts, which reduce operating costs, preserve surplus wet-weather capacity, reduce
energy consumption, and reduce the wear and tear on existing capital investments,
thereby extending their life.
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Consider banning residential garbage disposals to reduce pollutant loads, as necessary, to
reduce the sizing of potentially necessary capital facilities. Commercial garbage disposals
are already banned in Palo Alto and Mountain View to reduce sanitary sewer overflows.
Continue strategic analysis of salinity infiltration to reline and rehabilitate sewers with
highly saline groundwater infiltration.
Consider banning specific household products that pass through the treatment plant and
have ecological impacts on the Bay to reduce the need for large capital improvements to
reduce pollutants better reduced through source control.
9.3.2 Solids Handling Project
Based on the information presented in Chapters 5, 6, and 7, the existing incineration process
needs to be retired due to deteriorating condition, limited remaining useful life, regulatory
pressures, and available alternatives for future solids processing. The capital costs to implement
alternative solids processes ranged from approximately $12 million (to send dewatered solids to
the BAB2E facility, which is likely to be a gasification process) to $89 million (to provide
anaerobic digestion on the RWQCP site). The annual operating costs for the solids treatment
alternatives range from $4 million to $6 million in 2045 (based on a 30 year CIP planning
horizon). The overall recommendations for solids processing facilities include:
1. Continue to use the existing incinerators until they can be retired and a new solids handling
facility and disposal option implemented.
2. Initiate a Solids Facility Plan
a. Develop the scope of a Solids Facility Plan to choose a technology and onsite or offsite
option for the replacement technology for the RWQCP’s solids handling systems
b. Given the issues foreseen regarding disposition of solids with a limited future for
landfilling and land applying biosolids, beneficial uses locally would provide the ability
to control the RWQCP’s destiny. However, the lack of a local market and space on-site
limit options to off-site beneficial use or privatization. For the purposes of the LRFP,
proceed with detailed evaluation including layouts for the following solids alternatives:
(1) Alternative B – Onsite gasification.
(2) Alternative C – Anaerobic Digestion with off-site beneficial use (either land
application or composting).
(3) Alternative D – Send dewatered solids to SJ/SC WPCP.
(4) Alternative E – Send dewatered solids to BAB2E.
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c. Enter into further discussions with the SJ/SC WPCP to determine conditions of an
agreement to send solids to their facility. In addition, participate in San Jose’s piloting
of gasification, if that project proceeds.
d. Consider joining the BAB2E consortium and participate in their ongoing evaluation of
promising technologies.
e. If the City and Partner decision makers have a strong preference to keeping solids
treatment within the control of the RWQCP, begin a preliminary design study for
anaerobic digestion facilities to evaluate in more detail the advantages and
disadvantages of different anaerobic digestion configurations.
f. If an anaerobic digestion process is implemented on-site, consider efforts to develop a
marketable product and local users through either drying or composting.
g. Investigate in greater detail the installations and operating history of gasification
systems, including performance, reliability and operational challenges. While the
United States has very limited experience with gasification of biosolids, there are
existing gasification systems in the US utilizing other feedstocks including wood
wastes and municipal solid wastes. Abroad, especially in Europe and Japan, numerous
entities have gasification systems utilizing various feedstocks, including wastewater
solids.
3. Develop a contingency plan for raw sludge disposal with a local waste hauler should the
furnace systems fail to operate.
A summary of the recommended solids project costs is shown in Table 9.2.
Table 9.2 Summary of Recommended Solids Project Costs (only one to be
selected)
Project Project Start Date Estimated Project Cost, millions
Total Range $12.8 to 89
9.3.2.1
Another solids disposal option that is being considered independent of the LRFP is dry anaerobic
digestion. With the closing of the Palo Alto landfill in 2011, the City wanted to look at options
for their solid waste disposal, particularly for green wastes. The City hired consultants
Alternative Resources, Inc. (ARI), to complete a dry anaerobic digestion study for solids
generated by the RWQCP and for handling green and food wastes collected in the City. ARI
Dry Digestion and Measure E
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concluded that a dry anaerobic digester could indeed be cheaper than the exporting options for
green waste, but only if such factors as carbon adders, state and federal grants and contingency
costs for exports are added into the mix. A citizen led initiative was placed on the ballot as
Measure E, which was to undedicate ten (10) acres of Byxbee Park for a ten year period for the
exclusive purpose of considering an Energy/Compost Facility to treat yard trimmings, food
waste and/or other organic material, including solids from the RWQCP. In November 2011, a
public vote resulted in a majority “yes” vote on Measure E, which means that the ten acres has
been undedicated and the site is available if the City Council decides to proceed with an
Energy/Compost Facility. City staff and Alternative Resources, Inc. (ARI) are developing an
Action Plan to layout the process and timeline for considering the facility.
9.3.3 Replacement Projects
Major facility replacement needs were identified in Chapter 5 of this Report based on the
condition of existing facilities and the alternatives considered in Chapters 7 and 8. Minor
projects are included in the Rehabilitation Projects list. Recommended major replacement
projects include:
Solids Treatment:Replacement of the existing solids handling facilities (discussed in the
previous section).
Headworks/Preliminary Treatment:Replace the existing headworks facilities and add
grit removal.
Recycled Water:Replace recycled water filters and chlorine contact tank.
Support Facilities: Replace the administration building with a new Laboratory and
Environmental Services Building to house a new laboratory and staff office space.
Remodel the operations building and maintenance building and expand the maintenance
building to include additional warehouse space.
The existing headworks will reach the end of their useful life within the next 15 to 20 years. It is
recommended to consolidate the facilities from two facilities into one and to add grit removal
capabilities at the headworks. The replacement of the recycled water facilities is primarily driven
by aging facilities and the need to better allocate space for treatment processes at the RWQCP
site. The existing recycled water filters, chlorine contact tank, and storage tank should be
replaced. Additional recycled water storage and pumping are required to meet the demands of
future users but these projects are listed under Future Recycled Water projects.
A summary of the recommended replacement project costs is shown in Table 9.3. A table
showing all the recommended projects is listed in Appendix S.
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Table 9.3 Summary of Recommended Replacement Project Costs
Project
Project Start
Date
Estimated Project
Cost, millions
Total $54.4
The existing Administration Building and Laboratory spaces are not adequate. The existing
Administration Building was originally built as an industrial concrete structure for recycled
water processing, including pumping (still exists in the basement). The industrial environment is
not suitable for offices. The existing laboratory in the operations building is inadequate for the
number of staff that needs to be housed and for the types of laboratory testing that is conducted.
It is recommended to build a new Laboratory and Environmental Services Building that includes
a laboratory and sufficient space to house all the administrative, purchasing, IT, engineering,
solid waste, and watershed protection staff in one location. Alternatives for the Environmental
Services Building include siting it onsite along Embarcadero Road, siting it offsite at a building
adjacent to the RWQCP, or expanding the Operations Building around the building’s perimeter
moat.
It is recommended for the Operations Building, which currently houses the laboratory, to be
remodeled following removal of the laboratory to accommodate larger locker rooms, a
training/conference room, and lunchroom. It is recommended that the Maintenance Building be
remodeled to better accommodate the maintenance staff office and electrical bench needs, as
well as to expand the Warehouse for additional storage space.
A summary of the recommended replacement project costs is shown in Table 9.4.
Table 9.4 Summary of Recommended Support Facilities Project Costs
Project
Project
Start Date
Estimated Project
Cost, millions
Total $24.5
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9.3.4 Rehabilitation Projects
Needs for rehabilitation of existing facilities and replacement of equipment were identified in
Chapter 5 of the Report and are driven by aging infrastructure that is reaching the end of its
useful life over the planning horizon. Overall recommendations for rehabilitation include:
Primary, secondary, and tertiary treatment: Rehabilitation of the existing major liquid
treatment processes including equipment replacement and structural/concrete repair for the
primary sedimentation tanks, fixed film reactors, aeration basins, secondary clarifiers, and
dual media filters.
Miscellaneous power and piping: Rehabilitation/replacement of pumps, in-plant piping,
and electrical/power support facilities such as MCCs and generators.
Joint influent sewer: Rehabilitation of the influent joint interceptor sewer line and the
outfall should follow an evaluation of the estimated existing and future wet weather flows.
Many of the rehabilitation projects are small and should be grouped together during execution.
For the purposes of this Report, most projects are grouped together by process area. A summary
of the recommended rehabilitation projects is shown in Table 9.5.
Table 9.5 Summary of Recommended Rehabilitation Projects
Project
Project
Start Date
Estimated Project
Cost, millions
Total $77.7
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9.3.5 Future Regulatory Requirement Projects
Future regulations for total nitrogen and emerging contaminants removal are expected for Bay
discharges over the 50-year planning horizon. This Report has identified treatment alternatives to
meet the anticipated regulations, developed cost estimates to build those facilities, and has
reserved space if new facilities are needed. Chapter 8 summarizes the liquid treatment
alternatives to meet the identified future regulations. The lowest cost alternative for removal of
total nitrogen was to add denitrification filters onto the existing liquid treatment processes. For
removal of emerging contaminants, an advanced oxidation step (i.e., ozonation) was considered
and the costs and space needs were estimated. Overall recommendations from Chapter 8 include:
Continue use of and investment in existing liquid treatment processes. Cost for
rehabilitating existing facilities that are also required for meeting future regulatory
requirements are included in the rehabilitation projects.
Participate in ongoing regional efforts to better characterize the water quality issues in the
San Francisco Bay by participating in effluent and receiving water quality data collection,
including the March 2, 2012 RWQCB Water Code Section 13267 technical report order
requiring submittal of information on nutrients in wastewater discharges. Data provided
under this order, along with data from all other Bay area dischargers, will serve as a tool
for the RWQCB and the San Francisco Estuary Institute (SFEI) to understand nutrient
loadings within the Bay. Data will include some historical and monthly sampling, testing,
and reporting for the next two years.
Participate in ongoing regulatory discussions regarding nutrients in the Bay and the
benefits and impacts of moving toward advanced nutrient removal. Impacts of nutrient
removal with current technologies include increased energy use and greenhouse gas
emissions. Engage in discussions regarding how nutrients would be regulated (on an
annual or monthly basis) as this has an impact on sizing treatment facilities. Continue
efforts to reduce nutrient nonpoint sources from entering local creeks and Bays.
Participate in discussions and efforts to reduce nutrients to the Bay through non-point
source control in the watershed.
Plan for the space and costs of nutrient removal and advanced oxidation facilities should
the facilities be required.
Continue to track other regulatory development for emerging contaminants and other
pollutants of concern.
Continue to track emerging technologies and revisit process decisions when and if nutrient
removal and/or emerging contaminant removal are needed.
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A summary of the recommended future regulatory project costs is shown in Table 9.6. There is
regulatory uncertainty associated with both the denitrification project for nitrogen removal and
the ozonation project to meet CEC removal. Therefore both projects were given a late start date,
but actual implementation would be regulatory or policy driven.
Table 9.6 Summary of Recommended Future Regulatory Project Costs
Project
Project
Start Date
Estimated Project
Cost, millions
Total $69.4
9.3.6 Future Recycled Water Projects
Recycled water demands and facility needs were discussed in Chapters 3, 5, and 8. While the
existing recycled water facilities are sufficient for current demands, it was found that additional
storage and pumping are required to provide service to future users. In addition, the existing
recycled water filters, chlorine contact tank and storage basins are aging and in need of
replacement, as discussed in Section 9.3.3.
To expand the recycled water market, it has been identified that the recycled water quality needs
to be lower in salts (i.e., total dissolved solids or TDS) to be protective of some of the
landscaping needs. The City of Palo Alto and the RWQCP Partners have set a goal of reducing
TDS from the existing average TDS of 917 mg/L to 600 mg/L. Source control measures, such as
sewer lining, are being implemented to reduce intrusion of salty Bay water into the system. If
these measures do not prove successful, salt reduction facilities consisting of ultrafiltration and
reverse osmosis (UF/RO) can be implemented at the RWQCP site.
Recommendations for recycled water projects include:
Replacement of filters and chlorine contact tanks, as identified under replacement projects.
Construction of new storage facilities and booster pumps to expand capacity for peak flow
demands.
Implementation of source control measures to reduce influent TDS and, in turn, reduce
TDS in the recycled water.
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If source control is unsuccessful, reserve space and funds for implementing UF/RO
facilities.
A summary of the recommended recycled water project costs is shown in Table 9.7. Due to the
uncertainty associated with the need for the reverse osmosis project for salinity reduction, it was
given a late start date, but actual implementation would be policy driven.
Table 9.7 Summary of Recommended Recycled Water Projects
Project
Project
Start Date
Estimated Project
Cost, millions
Total $76.7
9.3.7 Other Recommendations
The RWQCP currently tests for approximately 70 different parameters at 10 different (main
process) sample stream locations. This monitoring allows for a very good assessment of the
performance of most unit processes. However, there was additional special sampling required as
part of this LRFP to better assess the performance of specific process units. It is recommended
that SVI, primary sludge, filter backwash, gravity thickener overflow, incinerator belt press
filtrate, and scum hopper overflow samples be included in the regular sampling schedule so that
performance evaluations on these units can be trended, and thickening and dewatering capture
rates can be more accurately calculated in the future.
Additionally, because of the emphasis on solids treatment in this LRFP and the impact that
sludge flows can have on the treatment train capacity, it is also recommended that a flow meter
be installed on the primary sludge stream to the gravity thickeners to better determine the solids
capture and a more accurate solids balance around the solids handling equipment. The sludge
density meter on the blend tank discharge should be replaced with a more reliable instrument; a
more reliable and accurate meter is needed to better understand solids loadings that will be used
in the projections for the Solids Facility Plan.
9.3.8 Site Plan for Recommended Facilities
Space has been allocated on the RWQCP site for each category of projects that have been
recommended. It is important to reserve space not just for the facilities that are needed in the
near term, but also for potential future needs. Figure 9.1 shows the overall RWQCP site plan
with space reserved for future projects.
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9.3.9 Summary of Overall Costs for Recommended Facilities
The recommendations discussed in the previous sections of this chapter result in a significant
investment in projects at the RWQCP over the next 50 years. However, many projects, such as
reverse osmosis to remove salts from recycled water or ozonation to meet emerging
contaminants regulations, may not be implemented in the future unless required by regulatory
changes or deemed needed per policy decisions. In addition, a final decision has not been made
on which solids handling process should be implemented, which has a large impact on the
overall capital improvement project (CIP) program cost estimates. A summary of the total costs
for the recommended facilities over the 50 year planning horizon is shown in Table 9.8.
Figure 9.2 shows the percent contribution of the major project categories to the overall CIP
program, including the most expensive solids handling project (i.e., anaerobic digestion),
ozonation for removal of emerging contaminants, and UF/RO for removal of salt from recycled
water.
Table 9.8 Summary of Recommended Project Costs
Project Estimated Project Cost, millions
Total $315 - 392M
9.4 IMPLEMENTATION PLAN
The recommended projects for this LRFP are spread over the 50-year planning horizon and some
projects are dependent on either a policy decision or a regulatory directive. For the purposes of
long term CIP planning, a schedule for implementation of the recommended projects was
developed with the best available information and input from City staff. The schedule for
implementation is shown in Figure 9.3.
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Figure 9.2 Contribution and Cost of Major Project Categories to Overall CIP Program
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For the purposes of implementation, the projects have also been divided into three (3) main
categories: Major CIP (larger capital cost projects that are required), Minor CIP (smaller capital
cost projects that are required and can be done under the existing plant annual CIP budget) and
Future Major CIP (may be required in the future based on some potential regulatory
requirement). Figure 9.4 shows the contribution of the major CIP categories to the overall CIP
program, including the most expensive solids handling project (i.e., anaerobic digestion),
ozonation for removal of emerging contaminants, and UF/RO for removal of salt from recycled
water.
9.4.1 Cash Flow
The costs for implementation of all the identified projects over the 50-year horizon are $392
million, assuming costs for anaerobic digestion for the solids project. However, as many of these
projects may not be constructed until directed by a regulatory authority or the City Council, the
costs for the recommended Major CIP is $218 million assuming anaerobic digestion or
$141 million assuming the BAB2E solids project. Clearly, the decision on solids process has a
major impact on the overall CIP costs.
Many of the identified projects are smaller rehabilitation projects that will be funded through the
existing RWQCP ongoing CIP budget that is funded by the partner agencies’ contributions of
$2.6 million/year (in 2011 $) adjusted annually by an inflation index, which has been averaging
about 2.6%.
Larger CIP projects identified will require funding through other mechanisms such as State
Revolving Fund (SRF) loans, or bonds. Figure 9.5 shows the overall cash flow for all projects
identified in the CIP program regardless of the funding source based on the schedule of
implementation presented in Figure 9.3.
9.4.2 Operations and Maintenance Costs
The RWQCP O&M costs were developed for each alternative based on the process components.
Only the O&M costs for the recommended alternative are shown in the cash flow summary
(Appendix T). For the solids alternatives, anaerobic digestion was used as the recommended
project for the purposes of developing an O&M estimate. For the liquids alternatives, trickling
filters, activated sludge and denitrification filters was used as the recommended project. Current
O&M costs provided by the City were projected based on flow projections until either the solids
or liquids project is implemented.
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Figure 9.4 Contribution and Cost of Major CIP Categories to Overall CIP Program
Major CIP ($M),
$217.5
MinorCIP ($M),
$28.7
FutureMajor CIP
($M), $146.1
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The RWQCP currently expends approximately $12.8 million for its O&M expenses, this is not
including costs associated with administration, engineering and pretreatment and source control.
Appendix T presents the O&M cost projection for the RWQCP for both solids and liquids
alternatives.
Figure 9.6 shows the projected incremental increase in O&M costs from 2015 through 2045. The
O&M costs were estimated based on existing treatment for both solids and liquids staring in
2015, new anaerobic solids digestion with cogeneration facilities in 2019, and with no change to
the liquids treatment over the selected period. Based on this scenario there is an anticipated
decrease in plant O&M in 2019 once anaerobic digestion comes on line due to the offset of
energy production with the cogeneration facilities. The O&M is then expected to increase as
flow to the RWQCP increases.
9.4.3 Total Annual Cost Projection
A total annual cost projection was developed to help determine financing options and
categorization into the groupings discussed above. This total annual projection was developed by
combining the estimated annual capital costs for the recommended CIP and the estimated annual
O&M costs. Based on the total annual cost projection, The CIPs identified in Section 9.3 above
were divided into groupings based on three (3) pay approaches to the capital projects needed:
Minor CIP - Pay as you go
Major CIP - Debt service/grants and loans
Future Major CIP - No firm timeline and no funding defined.
Each one of these CIP categories will be funded and planned for differently.
9.4.3.1 Minor CIP Projects
The projects that were placed on the minor CIP list were smaller projects that could be
accommodated within the RWQCP’s existing funding structure for small CIP items. Presently,
all the partners contribute money for an annual CIP budget in the amount of $2.6 million (for
2011). This annual CIP budget is allowed to increase each year based on inflation index. The
assumption used for determining which projects could fit within this annual CIP budget is that
this annual budget will increase to $2.8 million in 2015. Projects were evaluated for expenditures
over their anticipated project duration. The RWQCP staff did not want to use all of the annual
budget for planned projects but instead wanted to leave at least $0.5 M for other projects. The
RWQCP has other energy and process efficiency projects that they would like to continue
implementing as well as certain periodic repair and replacement needs that would need to be met
with this minor CIP budget. Table 9.9 shows the projects that fall into the minor CIP budget.
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Table 9.9 Summary of Minor Projects
Project Title
Project
Start Year
Project
Duration
Year On-
line
Total Project
Cost ($M)
Remodel Operations Building 2023 5 2028 3.3
Expand Warehouse 2029 4 2033 1.6
Remodel Maintenance Building 2034 2 2036 1.7
Recycled Water Piping 2022 5 2027 1.3
Electrical/Power Support Facilities 2012 3 2015 2.8
In-Plant Piping 2014 15 2029 2.1
Collection System Modeling 2015 2 2017 0.5
Secondary Clarifiers Structure 2015 4 2019 1.5
Dual Media Filter Equipment 2016 3 2019 0.5
Dual Media Filter Structure 2016 3 2019 0.6
Sludge Thickeners Structure 2017 3 2020 1.0
Sludge Thickeners Equipment 2017 3 2020 1.5
Aeration Basins Equipment 2019 3 2022 1.7
Aeration Basins Structure 2019 3 2022 2.5
Secondary Clarifiers Equipment 2021 4 2025 6.1
Total 28.7
9.4.3.2 Major CIP Projects
The projects which were too large to be implemented within the annual CIP budget were termed
Major CIP projects. The Major CIP projects will need to be funded via means that are more
traditional. Table 9.10 shows the projects that fall into Major CIP grouping. Funding for these
projects is discussed in more detail in the following section.
9.4.3.3 Future CIP Projects
The Future CIP project grouping includes those projects that will be regulatory or policy driven.
Currently no funding is planned for these projects. Future CIP projects are shown in Table 9.11.
Section 9.5 presents the funding alternatives that are available to the City. As discussed in this
section, the RWQCP has several financing instruments available to pay for the implementation
of the CIP projects. It is assumed that the RWQCP will cash finance the capital projects using
revenues from rates, SRF funds and alternate financing mechanisms. Figure 9.7 shows the
projects that would need these alternate funding mechanisms and have been separated into two
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categories: (1) the must do category (Major CIP) (2) and do not have to do category (Future
Major CIP).
Table 9.10 Summary of Major Projects
Project Title
Project
Start Year
Project
Duration
Year On-
line
Total Project
Cost ($M)
Anaerobic Digestion 2013 6 2019 $89.0
Laboratory and Environmental
Services Building
2014 6 2020 $17.9
Headworks Facility (including Grit
Removal System)
2020 6 2026 $38.9
Recycled Water Filters and
Chlorine Contact Tank
2022 5 2027 $14.2
Primary Sedimentation Tanks
Structure
2014 3 2017 $7.3
Fixed Film Reactors Structure and
Equipment
2017 4 2021 $19.4
Joint Interceptor Sewer 2022 5 2027 $30.8
Total $217.5
Table 9.11 Summary of Future Major Projects
Project Title
Project
Start Year
Project
Duration
Year On-
line
Total Project
Cost ($M)
Trickling Filter/Activated
Sludge/Denitrification Filters
2028 7 2035 $49.4
Ozonation 2045 5 2050 $20.0
Storage Tank and Booster Pump
Station
2030 3 2033 $14.3
Ultrafiltration/Reverse Osmosis 2050 5 2055 $62.4
Total $146.1
9.5 FUNDING OPTIONS
The adequate funding of capital projects is a primary constraint in project implementation. The
RWQCP has several funding options available for the financing of its projects. The term
“funding” refers to the method of collecting funds; the term “financing” refers to methods of
addressing cash flow needs. The following sections provide examples of several instruments that
can be utilized to fund the CIP capital costs.
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Figure 9.7 Cost of Major and Future Major CIP Categories to Overall CIP Program
MajorCIP
$217.5 M
FutureMajor CIP
$146.1M
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9.5.1 CIP Cost Recovery
Rarely does a city or an agency have sufficient revenue to fund large capital improvements
directly from user fees, which is the case with pay-as-you-go financing. Therefore, it is common
to use financing instruments to meet necessary funding requirements. The main financing
instruments available to the RWQCP for funding the capital costs include:
Pay-as-you-go financing
Debt financing
Grants and loans
Pay-as-you-go financing refers to upfront collection of project costs from existing and new users
for future capital improvement projects. Pay-as-you-go financing generally requires large rate
increases and creates cash flow problems. This method can be used with smaller CIP projects.
Debt financing refers to the acquisition of funds through borrowing mechanisms. Debt financing
requires the borrower to raise money for working capital or capital expenditures by selling
bonds, bills, or notes to individual and/or institutional investors. In return for borrowed money,
the individuals or institutions become creditors and receive a promise to repay principal and
interest on the debt.
Grants and loans provide an alternate source of funds at no or minimal cost. Federal, State, and
local grants provide funding at no cost for projects that meet select criteria. Grant funding is
limited and is generally not a long-term solution to meet financing needs. State and Federal loan
programs provide low-cost methods of borrowing for projects that meet select criteria. Most
projects receiving grant and loan funding generally will need to secure supplemental funding
sources.
All of these funding sources are discussed in additional detail in the following sections.
9.5.2 Pay-As-You-Go Financing
Pay-as-you-go financing involves periodic collection of capital charges or assessments from
customers within the municipality’s jurisdiction for funding future capital improvements. These
revenues are accumulated in a capital reserve fund and are used for capital projects in future
years. Pay-as-you-go financing can be used to finance 100 percent or only a portion of a given
project.
One of the primary advantages of pay-as-you-go financing is that it avoids the transaction costs
(e.g., legal fees, underwriters’ discounts, etc.) associated with debt financing alternatives, such as
revenue bonds. However, there are two common disadvantages associated with this method.
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First, it is difficult to raise the required capital within the allowable time without charging
existing users elevated rates. Second, it may result in inequities in that existing residents would
be paying for facilities that would be utilized by, and benefit, future residents.
Several existing funding sources can be utilized to pay-as-you-go finance the project costs. These
are the current fees, existing general funds, existing reserve funds, and connection fees.
The City has an existing annual CIP budget of $2.6 million that escalates according the
Consumer Price Index rate (currently averaging 2.6 percent). While it is possible to fund small
CIPs through this annual CIP, capital expenditures exceeding this value will need to be financed
through other mechanisms.
9.5.2.1 Utility Fees and Benefit Assessment Fees
Utility fees or benefit assessments, sometimes called service fees or user fees, consist of a fee
imposed on each property in proportion to the service provided to that property. Benefit
assessment fees are usually included as a separate line item on the annual property tax bill sent to
each property owner.
Utility fees are usually billed on a monthly or bi-monthly interval. In all other respects, benefit
assessments, utility fees, and service charges are essentially identical. A utility has the authority
to collect a benefit assessment fee, but only after approval by a majority of the voters, affected
property owners, or rate payers.
9.5.2.2 General Fund
The City’s general fund is one type of fund available if not earmarked by law for a specific
purpose. In Palo Alto, general fund money comes largely from hotel tax, title transfer taxes,
property taxes, and sales taxes. The demand for general funds by other city functions (e.g., police
/ fire) will exceed the supply available for wastewater treatment expenses, and therefore, these
funds are not considered available for these projects.
9.5.2.3 Development Charges/Connection Fees
The system development charges/connection fees/impact fees represent the cost of providing
regional conveyance and treatment facilities to serve the new recycled water customers. They are
one-time fees charged to customers at the time of system connection approval or permit/contract
issuance. The charges for individual properties may be based on whatever assessment measures
the City desires for equity.
A disadvantage to utilizing impact fees is that the fees cannot be collected until the system
constructions permit stage at the earliest. The amount collected each year depends solely on the
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rate of growth of the City. Consequently, funds may not be available to construct new capacity at
the time it is needed.
9.5.3 Debt Financing
There are several different options for debt financing of wastewater and recycled water projects,
such as issuance of bonds. Bonds used for financing public works projects are generally local
government tax-exempt bonds.
9.5.3.1 Revenue Bonds
Revenue bonds are historically the principal method of incurring long-term debt. This method of
debt obligation requires specific non-tax revenues pledged to guarantee repayment. Because non-
tax revenues, such as user charges, facility income, and other funds are the bondholder’s sole
source of repayment, revenue bonds are not considered general obligations of the issuer.
Revenue bonds are secured solely by a pledge of revenues. Usually the City’s revenues are
derived from the facility that the bonds are used to acquire, construct, or improve. There is no
legal limitation on the amount of authorized revenue bonds that may be issued, but from a
practical standpoint, the size of the issue must be limited to an amount where annual interest and
principal payments are well within the revenues available for debt service on the bonds. Revenue
bond covenants generally include coverage provisions, which require that revenue from fees
minus operating expenses be greater than debt service costs.
9.5.3.2 Certificates of Participation
Certificates of participation provide long-term financing through a lease agreement that does not
require voter approval. The legislative body of the issuing agency is required to approve the lease
arrangement by a resolution. The lesser may be a redevelopment agency, a non-profit
organization, a joint powers authority, a for-profit corporation or other agency. The lessee is
required to make payments typically from revenues derived from the operation of the leased
facilities. The amount financed may include reserves and capitalized interest for the period that
facilities will be under construction. One disadvantage with certificates of participation, as
compared with revenue bonds, is that interest rates can be slightly higher than with revenue
bonds due to the insecurity associated with the obligation to make lease payments.
9.5.3.3 General Obligation Bonds
General obligation (GO) bonds are municipal securities secured by the issuer’s pledge of its full
faith, credit, and taxing power. GO bonds are backed by the general taxing authority of local
governments and are often repaid using utility revenues when issued in support of a sewer or
water enterprise fund.
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9.5.3.4 Assessment District Bonds
Financing by this method involves initiating assessment proceedings. Assessment proceedings
are documents in “Assessment Acts” and “Bond Acts”.
An assessment act specifies a procedure for the formation of a district (boundaries), the ordering,
and making of an acquisition or improvement, and the levy and confirmation of an assessment
secured by liens on land. A bond act provides the procedure for issuance of bonds to represent
liens resulting from proceedings taken under an assessment act. Procedural acts include the
Municipal Improvements Acts of 1911 and 1913. The commonly used bond acts are the 1911
Act and the Improvement Bond Act of 1915. The procedure most prevalent currently is a
combination of the 1913 Improvement Act with the 1915 Bond Act. Charges for debt service can
be included as a special assessment on the annual property tax bill. The procedure necessary to
establish an assessment district may vary depending on the acts under which it is established and
the district size.
9.5.4 Grants and Loans
Several grant and loan programs can be utilized to finance wastewater projects. The grant and
loan options include State funded programs such as the SRF and Federal programs such as grants
and loans through the Environmental Protection Agency (EPA) and US Bureau of Reclamation
(USBR). There are program websites that provide the most up to date information for each of
these grants and loans. It is possible that some of these grant and loan programs are discontinued
and/or that new programs become available.
The advantage of these grant and loan programs is the lower cost of borrowing. However, these
grant and loan programs are highly competitive and dependent upon State and Federal budget
cycles.
9.5.4.1 The Clean Water State Revolving Fund (CWSRF) Funding
The Clean Water State Revolving Fund (CWSRF) program, established by the Federal Water
Pollution Control Act (Clean Water Act or CWA), offers low interest loans for water quality
projects. Annually, the program disburses between $200 and $300 million to eligible
projects. Eligible projects include construction of publicly-owned facilities such as wastewater
treatment facilities and water reclamation facilities. Any city, town, district, or other public body
created under state law is eligible to apply for the CWSRF loan. Interest rate is ½ of the most
recent General Obligation (GO) Bond Rate at time of Preliminary Funding Commitment. The
current rate is 2.2 percent. The RWQCP has utilized the CWSRF loans for two of its projects in
recent years – the MV/Moffett area recycled water pipeline project and the UV disinfection
facility project. The interest rate for the MV/Moffett RW pipeline was 1.6 percent, and the rate
for the UV disinfection facility project was 2.6 percent.
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The financing Term is 20 years with a maximum $50 million per agency per year. A project may
be of a multiple year duration so long as the expenses and reimbursements do not exceed the
maximum $50 million per year limit. Repayment of the loan would begin one year after
completion of the construction. The CWSRF loan is a reimbursement loan and would reimburse
eligible expenses for project planning, design, and construction.
All proposed projects must be placed on the CWSRF competitive project list. Project placement
and application is a continuous open process. Projects on the list are classified by categories as
follows:
I. Treatment and delivery of treated wastewater or ground water for uses to offset State
water supply and benefits the Delta.
II. Treatment and delivery of treated wastewater or ground water for uses to offset State
water supply.
III. Treatment and delivery of treated wastewater for uses to offset local water supply
IV. Treatment and delivery of treated ground water for uses to offset local water supply
V. Construction of wastewater treatment facilities
VI. Miscellaneous
Wastewater treatment facilities would be classified as category V, which has a lower
priority. However, it was rare that an eligible project with a properly prepared and qualified
application be turned down for the SRF loan.
9.6 DEBT SERVICING
The debt incurred for any CIP projects will be serviced by the City of Palo Alto and its partners.
For capital projects, the partner allocations will be determined for each project based on whether
the project is a sewer or wastewater treatment plant project.
9.6.1 Capital Projects Debt Servicing Estimates
The minor CIP of $2.6M (in 2011 $) is made of contributions by the partners and as a result any
projects that are completed under the minor CIP budget is already allocated to the contributing
partners. Major CIP projects that will require funding will need to be paid for by the City of Palo
Alto and its partners. Table 9.12 shows the aggregate estimated debt service for the projects on
the Major CIP list for both Bonds and SRF funding. For Revenue Bonds, a 30-year repayment
period at 4.56 percent interest was assumed. For an SRF loan, a 20-year repayment period at
2.6 percent interest was assumed.
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Table 9.12 Summary of Estimate of Aggregate Debt Service for Major CIP
Year Revenue Bond(1) SRF Payment(2)
2013 $- $-
2014 $452,343 $-
2015 $452,343 $-
2016 $5,959,800 $-
2017 $6,969,801 $473,551
2018 $8,171,044 $473,551
2019 $8,171,044 $6,239,223
2020 $8,171,044 $7,296,577
2021 $8,171,044 $8,554,140
2022 $8,171,044 $8,554,140
2023 $10,574,506 $8,554,140
2024 $13,358,522 $8,554,140
2025 $13,358,522 $8,554,140
2026 $13,358,522 $11,070,287
2027 $13,358,522 $13,984,831
2028 $13,358,522 $13,984,831
2029 $13,358,522 $13,984,831
2030 $13,358,522 $13,984,831
2031 $13,358,522 $13,984,831
2032 $13,358,522 $13,984,831
2033 $13,358,522 $13,984,831
2034 $13,358,522 $13,984,831
2035 $13,358,522 $13,984,831
2036 $13,358,522 $13,984,831
2037 $13,358,522 $13,511,281
2038 $13,358,522 $13,511,281
2039 $13,358,522 $7,745,608
2040 $13,358,522 $6,688,254
2041 $13,358,522 $5,430,691
2042 $13,358,522 $5,430,691
2043 $13,358,522 $5,430,691
2044 $12,906,180 $5,430,691
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Table 9.12 Summary of Estimate of Aggregate Debt Service for Major CIP
Year Revenue Bond(1) SRF Payment(2)
2045 $12,906,180 $5,430,691
2046 $7,398,722 $2,914,544
2047 $6,388,722 $-
2048 $5,187,478 $-
2049 $5,187,478 $-
2050 $5,187,478 $-
2051 $5,187,478 $-
2052 $5,187,478 $-
2053 $2,784,017 $-
Notes:
(1) Bonds are based on a 30 year repayment period at 4.56 percent interest.
(2) SRF loan is 20 year repayment period at 2.6 percent interest.
In addition, there is existing debt for major projects already completed. These projects include:
1. 1999 Refunding of 1990 Utility Revenue Bonds
2. 1999 Incinerator Rehabilitation Revenue Bonds
3. CPA, CMV / Moffett Area Reclaimed Water Pipeline Project SRF Loan
4. UV Disinfection Facility SRF Loan
Appendix U shows a summary of the Wastewater Treatment Fund existing and aggregate debt
service. Figure 9.11 shows the total aggregate debt service required for the existing and major
CIP as well as the minor CIP.
9.6.2 Partner Cost Allocation
The share that the partners will need to contribute to each project will be determined by the
project type and will be based on flow and/or load allocations. The percentage allocations are
different for sewer and wastewater projects and these allocations along with the cost share to
each partner for each major CIP project is shown in Table 9.13 below. The amount to be
contributed by each partner will also depend on the type of funding that is secured and the
interest rate and payment period. The contributions required by each partner agency for the
Major CIP projects for both Revenue Bonds and SRF loans are presented in Appendix U.
Costs for projects are planning level estimates and do not consider potential measures for cost
control. As each project moves forward, a more detailed analysis will be performed and cost
saving measures will be explored. For example, the first major project will be the solids project,
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which will be evaluated in more detail during preparation of the Solids Facility Plan (to be
prepared in 2013) and in subsequent predesign and design efforts. Partner agencies will be
encouraged to participate and provide input into these efforts.
Table 9.13 Summary of Preliminary Partner Cost Allocation for Major CIP Projects(1)
Partner Shares Palo Alto
Mountain
View Los Altos
East Palo
Alto Stanford
Los Altos
Hills
Percent Cost Share Based on Capacity
Sewer 18.24% 62.50% 15.00% 0.00% 0.00% 4.26%
Wastewater
Treatment
38.16% 37.89% 9.47% 7.64% 5.26% 1.58%
Project Cost Allocation in Millions
Solids Project
(cost shown for
Anaerobic
Digestion)
$33.98 $33.74 $8.43 $6.80 $4.68 $1.41
Laboratory and
Environmental
Services Building
$7.81 $6.19 $1.55 $1.25 $0.86 $0.26
Headworks Facility
(including Grit
Removal System)
$14.83 $14.72 $3.68 $2.97 $2.04 $0.61
Recycled Water
Filters and
Chlorine Contact
Tank
$5.42 $5.38 $1.35 $1.09 $0.75 $0.22
Primary
Sedimentation
Tanks Structure
$2.79 $2.77 $0.69 $0.56 $0.38 $0.12
Fixed Film
Reactors Structure
and Equipment
$7.41 $7.36 $1.84 $1.48 $1.02 $0.31
Joint Interceptor
Sewer $5.62 $19.25 $4.62 $ - $ - $1.31
Total $77.85 $89.41 $22.16 $14.15 $9.74 $4.24
(1) Preliminary allocation. Cost sharing allocations and cost control measures will be evaluated
in more detail for each individual project.
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Figure 9.8 Total Aggregate Debt Service for Existing and Major CIP Programs
$-
$2
$4
$6
$8
$10
$12
$14
$16
2013 2018 2023 2028 2033 2038 2043 2048 2053
Existing Debt
Aggr. Debt w/ Bond
Aggr. Debt w/ SRF
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City of Palo Alto
REFERENCES
Brown and Caldwell (April 1992) Water Reclamation Master Plan for the Regional Water
Quality Control Plant.
City of Palo Alto (2010) Annual Pretreatment Report. Regional Water Quality Control Plant
- Environmental Compliance Division.
City of Palo Alto (2011) Website accessed 6/22/11
http://www.cityofpaloalto.org/news/displaynews.asp?NewsID=1809&TargetID=268
Dettinger, M.D. (2005) From Climate Change Spaghetti to Climate-Change Distributions for
21st Century California. San Francisco Estuary and Watershed Science. Vol. 3, Issue 1,
March 2005, Article 4.
Karl, T.R. and R.W. Knight (1998) Secular trends of precipitation amount, frequency, and
intensity in the U.S.A. Bulletin of the American Meteorological Society, Vol. 79, pp. 231-
241.
Kharin, V.V., and F.W. Zwiers (2005) Estimating Extremes in Transient Climate Change
Simulations, Journal of Climate 18: 1156–1173.
Kharin, V.V., F.W. Zwiers, X. Zhang, and G.C. Hegerl (April 2007) Changes in temperature
and precipitation extremes in the IPCC ensemble of global coupled model simulations.
Journal of Climate 20:1419-1444.
Kiparsky, M. and P. Gleick (July 2003) Climate Change and California Water Resources: A
Survey and Summary of the Literature. Pacific Institute for Studies in Development,
Environment, and Security.
Madsen, T. and E. Figdor (2007) When it Rains, it Pours - Global Warming and the Rising
Frequency of Extreme Precipitation in the United States, a report by Environment California
Research & Policy Center. December.
Meehl, G. A., J. M. Arblaster, and C. Tebaldi (September 2005) Understanding Future
Patterns of Increased Precipitation Intensity in Climate Model Simulations. Geophysical
Research Letter, 32, L18719.
RMC (July 2006) City of Palo Alto – Recycled Water Market Survey Report.
RMC (December 2008) The City of Palo Alto Recycled Water Facility Plan.
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