SFPUC outlines sewer system operations and master plan, notes Southeast plant focus and $150 million capital program

Susan Layl, general manager of the San Francisco Public Utilities Commission, presented an overview of the city's combined sewer system and described the SFPUC's Sewer Master Plan work and ongoing wastewater capital projects.

Layl explained that San Francisco is the only California city with a citywide combined sewer system that collects both household wastewater and street runoff. She outlined system scale and operations: more than 1,000 miles of sewer pipe, pipe diameters from 8 inches to over 5 feet, and gravity-based conveyance using the city's topography. She said the city generates about 83 million gallons of wastewater on an average nonrainy day, and wastewater is routed to the Southeast Treatment Plant (serving about 80% of the city), the Oceanside Treatment Plant (about 20%), and an activated North Point facility used during rainy periods.

Layl described the treatment process from screening and grit removal through primary and secondary clarification, aeration with biological treatment, and final effluent discharge: Oceanside discharges via a 4.5-mile outfall into the Pacific and Southeast via a 900-foot outfall into the Bay. She described solids handling, including anaerobic digestion that produces biosolids and biogas; the SFPUC produces about 200 tons of biosolids per day and captures methane that supplies roughly 30% of each plant's energy needs.

She said more than 70% of the city's sewers are older than 70 years and face deterioration; the SFPUC has launched a Sewer Master Plan to guide investments over the next 30 to 50 years and identified the Southeast Treatment Plant as a center of focus for odor, aesthetics and seismic stability improvements. Layl said the SFPUC is implementing a roughly $150 million wastewater capital improvement program to address immediate needs, and further projects will be incorporated into the master plan.

Layl's presentation included descriptions of pollution prevention efforts such as programs to keep fats, oils and grease out of the sewer system and a FOG-to-biofuel program that converts collected grease into biofuel. She encouraged public participation in master-plan workshops and written comments via the SFPUC's website.

The presentation was informational; the transcript records no formal vote related to the master plan that evening. Layl's overview was part of the board's regular agenda presentation about city utilities and infrastructure.