FAQ – WWTP – Clean Water Program San Mateo

Frequently Asked Questions

Wastewater Treatment Plant FAQ – Project Overview

What improvements are being made at the wastewater treatment plant (WWTP)? Why are they necessary and how do these improvements benefit the community?

The Clean Water Program is a comprehensive plan to upgrade San Mateo’s wastewater collection system and wastewater treatment plant to benefit and protect the public and environmental health of the communities served which include San Mateo, Foster City, Crystal Springs County Sanitation District, a portion of unincorporated San Mateo County, and a portion of the town of Hillsborough. The improvements at the wastewater treatment plant will replace aging infrastructure, meet current and future regulatory requirements, increase system capacity during heavy rains, and align with long-term sustainability goals to provide reliable service for decades to come.
What is the current construction schedule of the wastewater treatment plant? How long is the construction upgrade and expansion of the WWTP expected to last?

Phase 1 (Site Preparation) of the construction began in summer 2019 and is complete. Phase 2 (Foundation Piles) construction began in July 2020 and is underway. Phase 3 (WWTP Facilities) construction overlaps with Phase 2 construction and began in fall 2020. Construction is expected to be completed in approximately five years for all three phases, including testing, startup, and commissioning of the new treatment processes at the wastewater treatment facility.
What are the construction work hours?

General construction work hours are Monday through Friday, 7 AM to 7 PM. Pile driving will be limited to 8 AM to 5 PM on weekdays. Workdays are expected to be 8 to 10 hours. Certain types of work may be approved by the City to occur on Saturdays 9 AM – 5 PM; Sunday/Holidays 12 pm – 4 pm. No night work is planned. If emergency containment type of work is required, there is no restriction on work hours.
Why are wastewater treatment plant upgrades so urgently needed?

Changing regulatory requirements protecting our communities mandate that these capital improvements be made or the City of San Mateo, and its regional partner agencies, will be in non-compliance with the Regional Water Quality Control Board’s Cease and Desist Order (CDO) and the National Pollutant Discharge Elimination System (NPDES) permit requirements. Failure to comply with the CDO and NPDES permit requirements, by mandated deadlines, could result in large fines that will be passed on to ratepayers, infrastructure will continue to deteriorate and have failures including sanitary sewer overflows that leak diluted raw sewage and pollutants onto our communities’ streets and into our creeks, beaches, lagoon, and the San Francisco Bay. During heavy rains, the wastewater treatment plant can be overwhelmed and must blend, or partially treat, the wastewater, which does not meet current and future regulatory discharge permit requirements. Sanitary sewer overflows and blending at the treatment plant are significant health concerns that negatively impact the community and the environment.
Will there be a change in the height of the new structures?

The height of the upgraded and expanded facilities will be no taller than the existing digesters, which are the egg-shaped structures and the tallest facilities on the existing plant. The new facilities will comply with maximum height limitations per the City of San Mateo General Plan and Municipal Code. Below is a conceptual rendering of the new facilities.
Where is the new wastewater treatment plant being constructed and what happens to the old plant after completion?

The new wastewater treatment facilities (for liquids treatment only) are being constructed on the adjacent undeveloped parcel north of the existing treatment plant. The existing plant must remain in operation while the new plant is constructed. When construction is complete, the solids handling facilities on the existing site will be integrated with the new liquids treatment facilities, and similar existing outdated facilities that are no longer needed will be demolished or repurposed.
How will the wastewater treatment plant incorporate green and sustainable practices?
Does the design account for sea level rise?

Yes, sea level rise was a consideration in the design. The primary protection for the wastewater treatment plant is provided by an existing levee system that is operated and maintained by the City of San Mateo and the City of Foster City. As a secondary level of protection, all openings and critical components of the new facilities will be elevated above the forecasted levels for sea level rise based on year 2100.
Will other collection system projects, such as pipes and/or pump stations, be under construction near the wastewater treatment plant site?

The Clean Water Program is a comprehensive Capital Improvement Program that, in addition to the wastewater treatment plant upgrade and expansion project, includes various collection system pipe improvements throughout San Mateo. For example, projects are planned for Dale Avenue and near the Dale Avenue Pump Station. The illustration shows the locations of the collection system improvements. See the WWTP page for project details and updates, answers to frequently asked questions and live webcam feeds showing construction progress.

Traffic/Access

What traffic impacts will construction have on neighborhood streets by the WWTP, and how will they be mitigated?

The Clean Water Program developed a Traffic Management Plan to minimize the impacts of construction activities on traffic and public access to recreational facilities. The Traffic Management Plan ensures established truck routes comply with “Chapter 11 – Vehicles and Traffic” of the City’s Municipal Code. Approximately 20 – 25 pile delivery trucks per day are expected during Phase 2 of construction, but they will be delivered “just-in-time” for pile driving, no trucks will be queued on J. Hrt Clinton Dr. or East 3rd Avenue, and delivery trucks are prohibited on-site between 4 PM – 5:30 PM to minimize impacts during peak commute hours.
Will construction impact public access to the dog parks and Bay Trail? Will public access improvements be provided as part of the project?

Various routes have been developed to provide temporary and permanent access to the parks and Bay Trail both during and after construction. The paths around the construction site have been closed since 2019 and there is signage that guides walkers and bikers to use alternate routes. Parking on Detroit Drive has been restricted for public safety. Alternate parking is maintained around the area.

A permanent pedestrian and bicycle access route around the wastewater treatment is in the final design phase and will be constructed to allow pedestrians and bicyclists to cross between the east and west sides of the plant.
My children walk to school near the construction area. Will their walk to school be impacted?

For pedestrian safety, paths around the construction site were closed in 2019 and will remain closed until construction is completed. Signage indicating safe alternate routes has been posted. Efforts were made to minimize pedestrian impacts to adjacent schools, residents, and businesses.
Will the construction area be fenced and secured?

Impacts

Will a lot of dust be generated from the construction and how will it be mitigated?
Is the dust from the construction site and demolition toxic? What hazardous materials will be generated? How will it be handled?

Environmental studies were performed at the project site to identify contaminants of concern, including testing for asbestos and lead at the facilities to be demolished. The contractor is required to implement proper abatement, handling and disposal procedures according to the requirements for any contaminants on the site.
Will noise be generated from the construction? What is the anticipated noise level for pile-driving activities?

The City of San Mateo Municipal Code states that the construction noise level at any point outside of the property plane of the project shall not exceed 90 decibels (dBA). All construction activities are expected to be within this maximum noise level except for pile driving. The project team conducted a thorough evaluation of pile types, installation methods, noise abatement techniques, and construction scheduling, and concluded that the pile driving work will generate noise levels exceeding 90 dBA outside the site. Noise modeling results indicate that anticipated peak noise levels would range between 90 dBA (similar to noise from a heavy truck) and 100 dBA (similar to noise from a jack hammer) at the property plane for majority of the pile driving phase. During Stage 2 of pile driving (piles at ground level), noise at the property plane is anticipated to exceed 110 dBA (similar to noise from a rock band) on some days.
How will construction noise be mitigated?

Approved work hours for construction activities and best practices will be employed to reduce sound levels from construction activities as much as practical. Notification protocols will be established to notify the surrounding neighborhood of construction activities, times, and contact information for feedback/complaints.
Will odors be emitted during construction? How will odor be mitigated? Will odor increase after construction of the larger facility?

The new treatment facilities are being constructed on a vacant parcel.  Shutdowns and connections to operations at the existing plant will be limited so they do not affect existing functions or cause additional odors. The Contractor is required to plan and schedule work to maintain plant operations.

New liquid treatment facilities will replace existing, outdated treatment processes. A new enhanced odor control system will be provided for the new facilities and therefore future odor generation is expected to decrease compared to current conditions. The new facilities will be located farther away from residential areas. However, the existing solids treatment facilities and its associated odor control system are not being upgraded as part of the project. Best practices will continue to be employed by the WWTP staff to continue efficient operation of the existing odor control system that will remain in use.

Please note that the odors generated in the vicinity of the existing WWTP are also contributed by the adjoining lagoon which is beyond our control and therefore will remain similar to current conditions.
Will the construction cause vibration?

During the pile driving phase, the contractor will install continuous vibration monitors at four locations around the perimeter of the project site. Vibration monitoring during on-site test pile driving that was conducted in 2018 indicated low risk – meaning, very low levels of vibration were detected. We do not anticipate residents feeling any vibration from the pile driving activities. However, if vibration readings reach predetermined limits, the activity will be temporarily shut down and assessed.

Pile Driving

What criteria did the City use to select the pile installation types/methods?

Several methods and pile types were considered during the design phase of this project. Precast prestressed concrete piles were selected as the most appropriate foundation system for the WWTP structures based on technical suitability for the soil conditions at the site, structural stability, and cost effectiveness.
What method of installation will be used for pile driving? What are the noise mitigation methods to be used for pile driving?

Piles will be driven by a pile-driving rig using a hydraulic hammer fitted with a noise shroud (sound absorbing material). Noise control measures being implemented during pile driving include: use of hydraulic hammer, use of noise-reducing shroud on the hydraulic hammer, and temporary sound wall on the western side of the construction site to absorb sound and minimize impact on the residential neighborhood.
How many piles will be driven and how long will it take?

Outreach and Funding

Who do I call if I have issues during construction?
Will there be more opportunities community input and comments?

Yes, the Clean Water Program staff hosts community meetings and reaches out to neighborhood and community organizations when important topics that affect the community need to be communicated. Public outreach and transparency are important components of the Clean Water Program. In addition, this website contains project documents, presentations, and videos posted to inform and educate the community. Please click here to sign up for our WWTP newsletter.
The City of San Mateo's sewer rates have gone up. Does this new rate cover this WWTP project or will the rates continue to go up in the future?

Yes, the City approved a sewer rate restructure to incorporate a fixed fee component, plus a multi-year rate adjustment to improve the stability and predictability of sewer revenues needed to fund the $991 million Clean Water Program to upgrade San Mateo’s wastewater collection system and the treatment plant. The program is funded by sewer use fees paid by all properties that tie into the sewer collection system. The City is seeking grants and low-interest loans to finance the capital improvements needed, while minimizing the impacts on sewer rates.
Since the San Mateo wastewater system provides services to neighboring agencies, will these other jurisdictions be paying their fair share?

Yes, all jurisdictions using the WWTP will pay their share. Capital improvements at the wastewater treatment plant are owned by the City of San Mateo and Foster City/Estero Municipal and paid for based on their ownership distribution of the new improvements. The wastewater treatment plant also treats wastewater for Crystal Springs County Sanitation District, a portion of unincorporated San Mateo County, and the southern portion of the Town of Hillsborough and those customer agencies pay the City of San Mateo for the sewer services provided.