Update to
San Mateo City Council
By Public Works
March 2, 2026
1 Clean Water Program and Wastewater
Treatment Plant Upgrade & Expansion
• Clean Water Program Overview and Update
• Wastewater Treatment Plant Upgrade & Expansion Update 2 Agenda
Clean Water Program - Driver & Goals
Replace aging
infrastructure and
facilities
Build wet weather
sewer system capacity
assurance to prevent
overflows
Meet current and
future regulatory
requirements
Align with the City of
San Mateo and Foster
City’s sustainability goals
Driver: Regional Water Quality Control Board issued 2009 Cease & Desist Order to the City of San Mateo, Town of Hillsborough, and the Crystal Springs County Sanitation District requiring the elimination of sanitary sewer overflows (SSOs) Post
CWP
Clean Water Program Schedule Highlights
4 Recurring WWTP and Collection System Rehabilitations and Repairs WWTP & Collection System Capacity Improvements
Start WWTP
Upgrade & Expansion
Construction
2019
WWTP Upgrade & Expansion
New Facilities in Service &
Project Closeout
2026
Start UFES
Construction
2020
UFES Project
Closeout
2026
Program
Closeout
2026
2019 2020 2021 2022 2023 2024 2025 2026 2027
Finish WWTP Upgrade &
Expansion Construction
2026
Clean Water
Program
Initiated
2015
Budget
Baselined
2017
Clean Water
Program
5 • ~$1 billion, 10-year effort
• Wet Weather Management
• Collection System
Rehabilitation and Capacity
Improvements
• WWTP Upgrades
• Nutrient Removal
Note: Image shown displays the estimated
scope during April 2018.
Status of CWP
Capacity
Improvements
COLOR LEGEND
Projects Completed
Projects in Construction
Projects in Design
Notes:
Some project segments were eliminated
due to design optimizations.
Status of projects shown as of February
2026.
6 Rev. 03/03/2022
92 UFES
101
ECR
DAPS WWTP
Expansion -
Treatment
Process Facility
Existing WWTP
East 3rd Ave.East 3rd Ave.
Detroit Dr.Detroit Dr.
SF BaySF Bay
Objectives
• Replace the existing liquids treatment process
with a new facility:
• Headworks, primary sedimentation, secondary
treatment (biological nutrient removal), tertiary
(membrane bioreactors), equalization basins
• Achieve early actor status on nutrient removal
• Increase wet weather management to 78
million gallons per day
• Title 22 ready / future recycled water
WWTP Upgrade & Expansion
Largest Capital Improvement Project in the History of the City
9 Excavation May 2020
10 New Headworks
Fine Screens
11 Primary Clarifiers
12 Biological Nutrient Removal (BNR)
Membrane Bioreactor (MBR)
14 BioActiflo
15 WWTP SCADA Control Room
16 Ribbon Cutting September 24, 2025
17 New Administration Building
18 WWTP Upgrade & Expansion
19 Wastewater in BNR process
Water Sample from the
Membrane Bioreactor (MBR)
20 WWTP Effluent Comparison
Existing Effluent BioActiflo Effluent MBR Permeate
CWP 2017 BASELINE vs ESTIMATE AT COMPLETION (EAC)
UPDATEClean Water Program Projects Original 2017
Budget Current EAC Variance %
Variance
Program Management Clean Water Program $ 85,092,559 $ 70,292,204 $ (14,800,355) (17.4%) Basin 2 & 3 Collection System Improvements $ 150,269,411 $ 167,561,559 $17,292,148 11.5% East SM Sewer Lift Station Improvements $ 23,635,177 $ 26,097,536 $2,462,359 10.4% Annual Sewer Rehabilitations $ 53,105,656 $ 58,042,920 $4,937,264 9.3% Sewer CCTV Inspection $ 4,904,937 $ 5,873,987 $969,050 19.8% Other Collection System Projects $ 26,885,605 $ 25,868,407 ($1,017,198) (3.8%) WWTP Immediate Action Proj (IAP) Package 1 $ 21,678,855 $ 18,621,628 ($3,057,227) (14.1%) WWTP IAP Package 2 $ 13,021,372 $ 14,838,328 $1,816,956 14.0% WWTP IAP Package 3 $ 2,469,442 $ 21,758,410 $19,288,968 781.1% WWTP Annual Major Components $ 8,919,114 $ 19,998,036 $11,078,922 124.2% WWTP Upgrade & Expansion $ 532,708,966 $ 603,372,165 $70,663,199 13.3% Other WWTP Projects $ 2,119,969 $ 2,858,296 $738,327 34.8% Program Contingency $ 66,299,227 $ - ($66,299,227) (100.0%) TOTALS $ 991,110,290 $1,035,183,476 $ 44,073,186 4.4% WWTP Upgrade & Expansion
Reviewing and Negotiating Known & Potential Changes/Risks Construction Costs/Risks (~$18.5M less $14.65M
Available Owners Contingency = $3.85M):
• Force mains configuration at headworks
• Flow equalization (FEQ) conversion and valve pit
differing site conditions
• HVAC material and labor escalation
• Stormwater pollution prevention (SWPP)
• Stormwater storage tank level controls
• Lighting at chlorine contact basins
• SCADA monitoring system programming
• UPS power for critical controls
• Tower Crane overrun
• Time impacts
• Additional risk contingency
Soft Costs due to Extended Schedule (~$2.05M):
• Project management
• Construction management
• Consultant support for analyzing time impact
requests
WWTP Upgrade & Expansion
Estimated Construction Contract Cost at Completion
Values based on available cost data as of February 9, 2026 Package/Phase Award Date
Awarded
Contract
Amount
Council
Authorized
Contingency
Potential
Contingency
Needed in
Future
Potential
Cumulative
Contingency
Potential
Construction
Contract Amount
1 - Site Preparation May 2019 $ 33,098,178 $ 1,725,000 $ 0 $ 1,725,000 2 - Foundation May 2020 $ 17,716,049 $ 1,645,000 $ 0 $ 1,645,000 3 - Process Facilities Sep 2020 $ 379,880,747 $57,823,702 $ 3,850,000 $ 61,673,702 TOTALS $430,694,974 $61,193,702 $3,850,000 $65,043,702 $495,738,676
14.2% 15.1%**
* The Potential Contingency amount is included in the ~$5.9 million FY 26-27 budget request for the WWTP Upgrade & Expansion project.
** For CIP Construction Contracts, a contingency amount equal to 10% of the construction contract is typically authorized.
For contracts with higher risks, contingencies of 20% have been authorized.
Upcoming WWTP Construction Key Milestones
Dates Subject to Change
Plant Performance Testing Ongoing to March 2026
New Processes Operational March 2026
Conversion of Existing Aeration Basins March 2026 to May 2026 Finish Remaining Site Work May 2026
Project Close Out May to June 2026
Project Name Current Committed
Budget
26-27
Proposed Total Project Budget
Program Management Clean Water Program $ 70,614,000 $(321,796) $ 70,292,204 Collection System SCADA $ 2,042,065 $(336) $2,041,729 East SM Lift Station Improvements $ 26,088,421 $9,115 $26,097,536 Basin 2&3 Collection System Improvements $165,597,185 $1,964,374 $167,561,559 Basin 4 Collection System Improvements $ 2,888,000 $(100,570) $2,787,430 Sewer Flow Monitoring & Hydraulic Modeling $ 490,000 $(28,236) $461,764 Annual Sewer Rehabilitations $ 57,020,000 $1,022,920 $58,042,920 Sewer CCTV Inspections $ 5,910,000 $(36,013) $5,873,987 WWTP Upgrade & Expansion $ 597,457,000 $5,915,165 $ 603,372,165 WWTP IAP Package II $14,695,372 $142,956 $14,838,328
WWTP IAP Package III $18,826,825 $2,931,585 $21,758,410 WWTP Annual Major Components $ 21,846,000 $(1,847,964) $19,998,036 TOTAL $9,651,200 $1,035,183,476
Note: Only project accounts associated with the Clean Water Program that have anticipated budget requests are shown.
UPCOMING BUDGET REQUESTS FOR CWP PROJECTS
Subject to Revisions
History of Economic and Financial Strategy
FY 16/17: 12% Sewer Rate Increase (100% Usage Based Rate Structure) Agreement with Estero Municipal Improvement District/Foster City FY 17/18: 36% Rate Increase (100% Usage Based Rate Structure) FY 18/19 to 22/23: 5-Year Rate Increases (12% to 14%) & Restructured with 50% Fixed Rate $270M Wastewater Revenue Bonds (SM/FC)
$277M WWTP EPA WIFIA Loan (SM/FC)
$85M Collection System WIFIA Loan (SM Only)
$137M WWTP State Revolving Fund Loan (SM/FC)
Agreement with Hillsborough for Payment of Capital Costs FY 23/24 to 27/28: 5-year inflationary rate increases (3% per year) Agreement with County and CSCSD for Payment of Capital Costs CWP Wrap-up and Future Projects
Dates Subject to Change
CWP Wrap-up
WWTP Completion June 2026
Reopening Rec Path June 2026
Other minor Projects End of year 2026
New Solids Handling Projects
Rotary Drum Thickeners Project In Design, Const. FY 26/27 Digestor 1 Improvements FY 26/27
Potential New Digestor 3 TBD
Potential New Projects TBD
Sewer Master Plan Update Starting July 2026
Thomas Williams, PE
Engineering Manager, Public Works Department
[email protected]
28 Thank you