San Francisco’s Combined Sewer Grit Management Approach at the Southeast Plant

The San Francisco Public Utilities Commission (SFPUC) has embarked upon a multi-billion dollar Sewer System Improvement Program (SSIP) to upgrade or replace its aging infrastructure. The SSIP carried out a system-wide condition assessment and process evaluation to establish the current baseline for the City and County of San Francisco’s (City) sewer system. One of the major issues identified during this effort was the significant impact of grit on the operation of the collection system and treatment facilities. The wastewater delivered by the collection systems carries significant quantities of grit to the treatment plants. The existing headworks grit removal systems at the Southeast Water Pollution Control Plant (SEP) captures less than half of the grit load in the raw influent. This incomplete removal in the headworks facilities adversely affects the operation and performance of downstream process equipment. This paper discusses the grit management strategy adopted by the SFPUC to improve grit removal performance at the SEP.