The Wastewater Enterprise mission is to operate and maintain the City's water pollution control plants, pumping stations and collection system in full compliance with our Discharge Permits to protect public health and the environment.  We also minimize impacts or wastewater treatment on San Francisco neighborhoods, oversee Southeast Community Facility and Earl P. Mills Facility to provide social services for area residents, and promote health, safety, professional development and diversity of its employees.

Scope

San Francisco has a combined sewer system that collects sewage and storm water in the same network of pipes.  This pipe system is over 900 miles long. Many large cities around the country use combined sewers, including Boston, New York, and Philadelphia. Through a vast network of underground pipes and structures, San Francisco's wastewater is pumped, treated, and discharged to the San Francisco Bay and Pacific Ocean. Combined sewers are, in many ways, superior to separate systems because storm water is treated before passing directly to the bay or ocean. Once collected, there are 17 pump stations that move the wastewater or storm water to the treatment plants.

The Southeast Water Pollution Control Plant, near Third Street and Jerrold Avenue, treats wastewater from the eastern side of the City. The Oceanside Water Pollution Control Plant, located adjacent to the zoo, treats wastewater from the western side of the City. The North Point Wet Weather Treatment Facility, located on Bay Street, operates during wet weather to treat combined storm flows. During dry weather, the Plants treat approximately 85 million gallons of wastewater each day. During wet weather, with additional facilities and increased operations, the system can treat approximately 575 million gallons of combined flow each day. The Division’s Maintenance Section maintains over 10,000 pieces of mechanical equipment and approximately 8,500 control and monitoring loops. They are supported by a warehouse with over 6,500 items valued at $3.5 million. Wastewater Enterprise's 395 employees maintain and operate wastewater facilities 24 hours a day, 365 days a year.

In addition, Wastewater Enterprise operates the Treasure Island collection and treatment facilities under a cooperative agreement with the U.S. Navy.

Treatment Facilities

Southeast Water Pollution Control Plant (SEP): This facility treats wastewater generated by two-thirds of the City's citizens. The plant also treats most of the commercial (downtown) wastewater, as well as the bulk of all industrial discharges. The SEP can treat up to 250 million gallons of wastewater per day during wet weather, while continuing to protect the environment. SEP treats about 80% of the total wastewater flow generated within San Francisco and removes over 90% of the solids and biodegradable organics.

Oceanside Water Pollution Control Plant (OSP): This is San Francisco's newest treatment plant. It is one of few plants in the United States built largely underground and is the first Plant with a zoo on its roof. During peak wet weather, the plant treats 60 million gallons per day from the City's west side. OSP meets all federal and state discharge standards. Approximately 95% of the pollutants are removed from the wastewater stream before discharge into the Pacific Ocean through the 4.5 miles Southwest Ocean Outfall.

North Point Wet Weather Treatment Facility: WPCD's wet weather facility is staffed when the chance of rain is greater than 30% to provide primary-level treatment and disinfection for northern area flows. In one hour, the operators can increase the flow rate from zero to 150 million gallons per day.

Storage and Transports

Storage/transports are huge underground rectangular tanks or tunnels that surround the City like a moat. During rainstorms, storage/transports prevent untreated shoreline discharges. Up to 193 million gallons of combined sewage and storm water is stored in these facilities citywide for later treatment. Storage/transports have three functions: 1) Capture the runoff: at the City's perimeter, the storage/transports catch the combined storm water and sewage; 2) Storage: storage/transports hold storm water and sewage for later treatment; 3) Treatment: storage/transports provide treatment consisting of settling and removal of floatable materials prior to shoreline discharge when wastewater flow exceeds the system's total storage capacity.

Most rainstorms do not completely fill storage/transports and the wastewater is held for later treatment. The solids retained in storage/transports are flushed to the treatment plants after storms. When treatment plants are at full capacity and all storage elements are full and rain continues to fall, shoreline-treated discharges occur. The treated discharge is approximately 6% sewage and 94% storm water. Treated discharges can occur from one to ten times per year, depending on location.

Pump Stations

Pump stations move the combined flows to treatment plants or to storage/transports. Every storm is different and staff adjust pumping rates to accommodate differing rainfall conditions and thus are able to achieve maximum use of available facilities.

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