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Oceanside Treatment Plant

  OSP Digesters (from factsheet)

Snapshot of OSP


Built in 1993.

Treats 20% of the City's flows.

Capacity to treat 17 million gallons per day (MGD) of wastewater and up to 65 MGD during rain storms. 

Treated water is released into the Pacific Ocean through deep ocean outfall.

12 acres with 70% underground. 

Located off Great Highway under the San Francisco Zoo.


   OSP Fact Sheet July 2019

 Treatment Plant Factsheet

Located on the Great Highway near the SF Zoo, the Oceanside Treatment Plant (OSP) is one of a few plants in the United States built almost entirely underground. It is the City's newest wastewater facility, providing all-weather wastewater collection and treatment of 20% of the City's flows.

Wastewater on the west side of the City, from the Presidio to Lake Merced, is pumped from the Westside Pump Station to the OSP. On an average day, the OSP can treat 17 million gallons per day (MGD); during rain events, the wet-weather treatment capacity is 65 MGD.

Constructed in 1993 as result of the Clean Water Act upgrade, the OSP uses the latest technology in wastewater management, such as egg-shaped digesters for solids treatment, more sophisticated odor control and a higher level of seismic safety.


The Need for Improvement

Although the OSP is the most recently constructed of the City’s three treatment facilities, the harsh marine environment surrounding the facility make it vulnerable to accelerated corrosion that reduces the life of the equipment and performance of the plant. The facility requires replacement or upgrades to maintain efficient operation and seismic reliability and to extend the useful life of the equipment. The Sewer System Improvement Program (SSIP) will address deterioration, system performance, and reliability of existing facilities of the OSP.

Planned Improvements

  • Upgrading electrical and instrumentation system 
  • Enhanced corrosion control
  • Upgrades to existing digesters
  • Structural and seismic improvements

Project Benefits

  • Seismic improvements
  • Improved grit removal during pre-treatment 
  • Improve operating reliability and efficiency


    Last updated: 7/26/2019 9:50:13 AM