Major construction for shafts begins in late September at SVCW’s Front of the Plant (FoP) project at 1400 Radio Road at the southeastern tip of Redwood Shores.
The FoP project is a major part of SVCW’s Regional Environmental Sewer Conveyance Upgrade (RESCU) program that includes conveyance system improvements to transport wastewater from member agencies’ collection systems to SVCW’s wastewater treatment plant.
The FoP project includes a 1) Receiving Lifting Station (RLS) to lift the wastewater from the gravity pipeline to the surface to be 2) screened and de-gritted by the new Headworks before flowing to the plant in 3) the new influent pipeline (IPL). Besides these three components, the FoP project is composed of site civil improvements, electrical, chemical storage, and odor control projects.
Movement of wastewater flows from the gravity pipeline to the headworks requires that it be pumped. To do this, two shafts need to be built at the front of the plant site. The larger of the shafts will support the RLS, which will pump flow from the tunnel to the new headworks for the first steps in wastewater treatment. The second shaft, to be constructed adjacent to RLS shaft, will be used for tunnel boring machine (TBM) retrieval after tunneling is complete for the gravity pipeline from a shaft site at Redwood Shores Parkway/Shoreway Road. After the TBM is removed, the smaller shaft will have multiple functions, including as an access into the tunnel, and as a surge tower for managing wastewater flows. The RLS shaft is 75-feet in diameter and the smaller shaft is 47-foot in diameter. There will be two stairways as well as a freight elevator in the RLS shaft.
Work beginning in late September includes installing groundwater dewatering wells, ground movement sensors known as inclinometers, and pressure sensors known as piezometers. Work that will be started in September, but which will be completed in 2019, includes construction of slurry wall panels and load bearing elements (both of which make up the shaft walls), excavation of both shafts and placement of large concrete slabs at the bottom of the shaft excavations.
The concrete wall thickness of the shafts is approximately four-feet and the excavated depth of both shafts is approximately 100 feet.
The shaft construction project was approved at $16.745 million by the SVCW Commission last month. The Commission will authorize additional components of the FoP project in December.
The shaft construction is expected to take 12 months to complete.
Truck traffic coming along Redwood Shores Parkway to the plant will be directed to not exceed the 25-mph speed limit in Redwood Shores and to drive in the right-hand lanes whenever possible. Excavated soils from the new shafts is expected to stay at the SVCW site to minimize truck traffic in Redwood Shores.
Construction noise should not be a distraction to neighboring uses with the possible exception to those at The Pointe, who may hear slightly louder than normal sounds due to trucks entering the site and the related construction.
Most work will be performed from 7 a.m. to 6 p.m. Mondays through Friday with some 12-hour days and some Saturday work when necessary.