- Basin c sanitary sewer rehabilitation project
Project Title: Basin C Sanitary Sewer Rehabilitation Project
Project Type: Collection System
Approximate Construction Start & End Dates: July 2019 to April 2020
San Mateo’s stormwater and wastewater collection system includes a network of 240 miles of pipe divided into five major sewer basins. Basin C includes areas between J Hart Clinton Drive and Kimberley Way on the eastern side of Highway 101. Basin C is the collection system for public and commercial centers, including the Bridgepointe Shopping Center and the San Mateo Wastewater Treatment Plant, as well as several residential neighborhoods, including Shoreview, Parkside, Marina Lagoon, Marina Gardens, Lakeshore, Mariner’s Green, Harbor Town, and Laguna Vista.
The work in Basin C will occur at multiple sites, including within the public right-of-way (ROW). Approximately 90% of the sites are in easements on private property, including front yards, backyards, and driveways.
The Basin C Sewer Rehabilitation project will upgrade and rehabilitate aging pipes and manhole covers and includes:
- Gravity Sewer System – Spot and segment repairs
- Manholes – Repairs and replacements
Cracked sewer pipes and laterals, as well as faulty manhole covers, allow rainwater and groundwater to flow into the sewer system. Improvements are needed for proper operation of the system, to repair leaks to meet regulatory requirements, and to prevent high flows that can cause sewer overflows.
A condition assessment was the first step toward finding cost-effective and technically feasible fixes to minimize inflow and infiltration. Closed-circuit television studies were conducted using a remote-controlled camera, and the resulting information was analyzed to identify problem areas in the collection system and design spot repairs.
Gravity Sewer Spot Repairs and Replacement
Gravity mains offer reliable conveyance of sewage and some inevitable surface runoff through a sewer system. However, over time, the ground can shift, roots can penetrate, and traffic can impact sewers, causing them to settle and crack. During this project, our contractors will spot-repair damaged or displaced 6-inch, 8-inch, 10-inch, 18-inch, and 21-inch-diameter sanitary sewer main with the same size polyvinyl chloride (PVC) pipe at 259 locations. Work also includes rehabilitating manholes with lining, repairing channels and benches, and fully removing and replacing select manholes. The work is located within the San Mateo public ROW and within easements on private property.
Manhole Repair and Replacement
Manholes need to be easily accessible for sewer maintenance and related emergencies. Over time, manholes can become covered with grass or can sink below the grade level of lawns, roads, or sidewalks. In total, 118 manholes in the basin have been identified for rehabilitation, repair, replacement, or manhole frame and cover replacement.
There are several ways to rehabilitate manholes. The method selected depends on the manhole’s condition. Common rehabilitation methods used for projects such as this include:
- Replacing the frame and cover
- Applying cement mortar as a binding agent to the inside
- Applying epoxy liner to the inside for resurfacing