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Introduction City of Redwood City (0011239.02)1-3 Woodard & Curran, Inc. Sanitary Sewer Capacity Master Plan November 2023 The study area for this Master Plan also includes San Mateo County Sewer Maintenance Districts (SMDs), which serve unincorporated areas of San Mateo County that are adjacent to the City, as well as portions of the Towns of Woodside and Atherton. The City does not own sewer facilities located in these SMDs and is not responsible for the maintenance or capacity of these pipes. However, these SMDs discharge flow into the City’s sewer system, and the City is responsible for conveyance of this flow. The locations of these County SMDs, which include Fair Oaks, Emerald Lake Heights, Oak Knoll, and Kensington Square, are also shown on Figure 1-1. Note that a portion of the Fair Oaks SMD also includes some areas within the Redwood City limits. 1.3 EXISTING SEWER SYSTEM The City’s sewer system consists of approximately 190 miles of pipe, ranging in size from 4 to 60 inches in diameter. Like most cities, the majority of City’s gravity sewer pipes are 6 or 8 inches in diameter. Table 1-1 summarizes the footage of pipe by diameter. As noted in the table, over 80 percent of the gravity sewer mains are 8 inches or smaller in diameter, and almost 40 percent are 6 inches and smaller. Figure 1-2 and Figure 1-3 show the City’s existing sanitary sewer system. The City also owns and operates 31 pump stations. Twenty-six of these pump stations are located in Redwood Shores, and the remainder are located in Seaport/Pacific Shores. The locations of the pump stations are also shown on Figure 1-3. The City is a member agency of the Silicon Valley Clean Water (SVCW), which provides conveyance and treatment of flows from its member agencies. Wastewater from the main area of the City is conveyed generally northeast through gravity sewers to the Maple Street Pump Station, operated by SVCW. Wastewater from Seaport/Pacific Shores is partially conveyed to the Maple Street Pump Station and partially discharged directly into the SVCW conveyance system at Seaport Boulevard south of Blomquist Street (depending on a valve setting). SVCW pumps wastewater from the Maple Street Pump Station to its transmission force main (48-inch to 54-inch diameter), which conveys the flow to the SVCW Wastewater Treatment Plant in Redwood Shores for treatment and disposal. Wastewater from Redwood Shores is collected and pumped by the City directly to the SVCW treatment plant. Treated effluent from SVCW discharges to lower San Francisco Bay. A portion of the secondary effluent is filtered and disinfected for use as non-potable recycled water. 1.3.1 Main City Area Sewer System The Main City Area sewer system, shown in Figure 1-2, includes 149 miles of gravity pipelines (not including tributary sewers from the County SMDs) ranging from 4 to 60 inches in diameter. Wastewater from the Main City Area is conveyed generally northeast through gravity sewers to the Maple Street Pump Station, operated by SVCW. Flow from the County’s Fair Oaks Sewer Maintenance District (FOSMD) enters the Main City Area system on Veterans Boulevard near Highway 101 and is monitored at a County-owned metering structure at that location. From there, it is conveyed through City pipes to the Maple Street Pump Station. Flows from other SMDs in the study area, including Emerald Lake Heights, Kensington Square, and Oak Knoll SMDs, enter the City’s system in numerous places on the southwest side of the city, and are also conveyed through City pipes to the Maple Street Pump Station, but are not specifically metered. A portion of flow from the Emerald Lake Heights SMD enters a sewer main known as the Hassler line (part of the Scenic Heights County Sanitation District), which runs along Edgewood Road and Cordilleras Road and discharges to the City of San Carlos sewer system at the Alameda de las Pulgas. The Hassler line and the portions of Emerald Lake Heights SMD tributary to it are not addressed in this study. ATTY/RESO.0077/CC RESO SEWER SYSTEM MANAGEMENT PLAN - EXHIBIT A REV: 07-14-25 LF Page 109 of 317