Skip to page body Home Customer Service How To Environment Projects & Programs About Us

Biosolids Digester Facilities Project


Click on the image to hear project managers talk about the project at our open house event in January.

What is the Biosolids Digester Facilities Project?

In the fall of 2013, the San Francisco Public Utilities Commission (SFPUC) initiated the planning and design efforts for the New Biosolids Digester Facilities Project at the Southeast Treatment Plant.

The proposed project includes the planning, design, and construction of new digestion and solids handling processes, which would replace the existing and aging facilities that are in need of structural replacement and seismic upgrades.

When completed, the New Biosolids Digester Facilities Project will implement modern technologies for treatment and improve odor control and seismic safety. The treated biosolids will be reused for beneficial purposes. In addition to reducing odors, the project will work to minimize impacts to the neighborhood through visual and aesthetic improvements.

In late 2014, the project team evaluated and selected the best suited technologies for sludge pumping, odor control, thickening and dewatering. After careful evaluation, a new location for the facilities has been proposed. The environmental review process began in June 2015, and a draft environmental impact report is expected spring 2017. Community presentations will continue through planning and construction along with more information about how the new facilities might be integrated into the Southeast community.

Are you interested in hosting a presentation for your group? Contact us at

Image of New Location for Digesters

The new facilities will be moved to the north side of the plant, away from homes.

To learn more about our project, read our factsheet.


  • To address aging infrastructure. The existing digesters are over 60 years old. Even now, the digesters require millions of dollars of repairs to keep them functioning until the new digesters come online.
  • To maintain regulatory compliance. The new facilities will be built to the very latest and predicted regulatory standards.
  • To protect public health and safety by having an operationally reliable wastewater treatment system.
  • To improve seismic reliability.
  • To utilize modern, proven and efficient technologies.
  • To upgrade biosolids treatment from Class B to Class A, allowing 100% of biosolids produced at the facility to be beneficially used in agricultural or horticultural applications such as soil amendment, fertilizer or compost.
  • To allow 100% of biogas produced to be converted into heat and energy to be used to power the Plant.
  • To improve odor, noise and visual quality.
Image of Red and Green Pipes
Originally built in 1952, the Southeast Treatment Plant (SEP) is San Francisco’s largest wastewater facility. Much of the biosolids facilities at the SEP rely on technology and engineering from the 1940s. To ensure our sewer system continues to operate successfully without interruption, we are committed to upgrading our largest treatment facility.


Past Engagement

In 2008, the SFPUC moved into a multi-year environmental review process for the San Francisco Sewer System Master Plan, a long-term planning document addressing needs of the city sewer system. As part of this master planning process, a community group was formed called the Digesters Task Force. This advisory group reviewed information on the replacement of the seismically unreliable Southeast Treatment Plant digesters and provided their concerns and recommendations to the SFPUC Wastewater Enterprise. With their efforts and input, the SFPUC was able to successfully launch into the next critical phase for the replacement of the digesters: planning and design.

In the news: Check out this article about the upcoming improvements at the Southeast Plant in the Potrero View!

Take A Tour!

Image of Kids on a Treatment Plant TourOur Southeast Treatment Plant tours are free, fun, and held on the 4th Saturday of the month. RSVP ahead, as they fill up fast! Tour attendees must be over the age of 10.

For tour information, visit:


Last updated: 3/9/2017 1:47:08 PM