San Mateo Wastewater Treatment Plant on schedule

Pile driving construction consists of steel beams driven into the ground to support a structure. Stage two will consist of around 400 piles driven down starting the first week of July and lasting around 2 1/2 months. Around 1,600 piles have been driven in to support new structures, and approximately 2,000 piles 80 to 105 feet long will go under the structure that the facility will rest on. Piles will prevent the future site from uplifting due to groundwater and keep the building in place during earthquakes.

The Wastewater Treatment Plant project is being completed in three phases over five years and is part of the Clean Water Program, the most significant upgrade to the city’s infrastructure in its modern history. The project started in 2019 and will be completed in 2024. The existing system takes wastewater from homes and businesses to the wastewater treatment plant. The Wastewater Treatment Plant then removes solids and disinfects the water to meet regulations to put into the Bay. However, the current system sees sewer overflows during heavy rains dangerous to the environment and people.

Phase one of site preparation and stage one of phase two focused on constructing the building foundation and were both completed in December. Phase two will finish in the winter. Phase three of plant construction will finish in 2024. Site work and ongoing construction include predrilling in preparation for pile driving, formwork and rebar, concrete pours, under-slab process piping, and in-slab electrical work for the treatment structures.

Noise remains a concern the city is monitoring. Benz said the city had received a few individual complaints about noise, and the city was making tremendous efforts to mitigate sound and vibration, including letting neighbors know as much as it could.

“We are trying to not disturb our neighbors as much as possible,” Benz said.

During phase two, stage two, noise levels will vary depending on location and distance. It may range between 90 and 110 decibels, comparable to a heavy truck, jackhammer and rock band, although some days may exceed 110 decibels. However, the noise will be affected by distance. The Shoreview area is around 310 feet away from the closest pile, while the Mariners Island area is about 1,700 feet away. The noise levels drop to below 90 decibels when 200 feet away.

Potholing and temporary rerouting of pipes are occurring. Phase three construction is underway and consists of the installation of formwork for slabs and walls, concrete placement, installation of rebar and piping. Increases in personnel and traffic at the worksite will occur, along with more parking at the temporary staging area on Anchor Road.

When completed, the area will have a new treatment process facility and administrative building. A bike and pedestrian path, indoor education and exhibit space, outdoor education signs and an interpretive area will be part of the administrative building.

The construction site is open Monday through Friday from 7 a.m. to 7 p.m. Pile driving activities will be restricted from 8 a.m. to 5 p.m., with no weekend construction planned, although exemptions were not ruled out. Around 10 to 12 trucks per day will be taking and delivering materials.

The city held a June 15 public meeting to provide updates and answer questions. Members of the public asked about walking and biking trails opening, with staff noting the Dale Avenue walking path is closed for the entire five-year construction period. Public access is permanently closed through Detroit Drive and temporarily closed through Joinville Road.

People can email info@CleanWaterProgramSanMateo.org or call (650) 727-6870 for more information about the project.

curtis@smdailyjournal.com

(650) 344-5200 ext. 102