Biosolids Digesters Facilities
Overview
Built in 1952, the Southeast Treatment Plant is the City's largest wastewater treatment facility handling nearly 80% of San Francisco's combined storm and wastewater every year, however, many of its facilities are past their useful life and generate odors that impact the neighborhood.
The SFPUC is currently investing over $3 billion in critical upgrades to transform this facility in the Bayview into a modern resource recovery center, including construction of the Biosolids Digesters Facilities Project and Biogas Utilization System. By doing so, we will continue to protect our communities and the environment while creating an attractive workplace and neighborhood asset that serves the entire City for decades to come.
When complete, the plant will work better, look better, and smell better for the neighborhood, our staff, and the entire City!
CONSTRUCTION UPDATES (Late 2025)
New Digester Painting Complete
Aesthetic upgrades to five new digesters at the Southeast Treatment Plant are now complete! As part of the Biosolids Digester Facilities Project, crews finished painting the exterior of each 60-foot digester in a vibrant pattern of muted blues and greens designed to evoke the wastewater cleaning process. The newly painted digesters will be particularly visible to commuters traveling on Caltrain and the I-280 overpass on the west side of the plant. The colorful transformation began in late July and was completed in Fall 2025.
Biosolids' Biogas Utilization Project
The Biogas Utilization Project is a key component of the Biosolids Digester Facilities Project, designed to transform how biogas—a byproduct of wastewater treatment—is managed and reused. Instead of using biogas for on-site energy generation as originally planned, the SFPUC will upgrade it to pipeline quality renewable natural gas for injection into PG&E’s natural gas pipeline.
Duration: Construction on this project began in late 2025 with an anticipated completion date of early 2027.
Questions? Contact our team by calling our hotline at 415-551-4SEP (4737) or email
ssip@sfwater.org.
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Project Background
The Biosolids Digester Facilities Project (BDFP) will replace and relocate the outdated existing solids treatment facilities with more reliable, efficient, and modern technologies and facilities. The new facilities will produce a higher quality biosolids, capture and treat odors more effectively, and maximize biogas utilization and energy recovery. In addition, the project will locate the digesters farther away from existing residences and make visual improvements in and around the Southeast Treatment Plant.
What are Biosolids?
Biosolids are the nutrient-rich soil-like product of the wastewater treatment process that can be used as a synthetic fertilizer-replacement and soil amendment.
Project Benefits
This project will provide significant operational and functional improvements to this critical facility:
- Produce higher quality, Class A biosolids that have greatly expanded beneficial uses.
- Reduce odors from the treatment process.
- Improve the ability for these critical facilities to withstand a 7.8 earthquake on the San Andreas fault, and a 7.1 earthquake on the Hayward fault.
- Ensure that the Southeast Treatment Plant can accommodate or adapt to the expected sea level rise of 36 inches by 2100.
The SFPUC is also leveraging these investments to provide opportunities to local residents and businesses who are most impacted by having this facility in the neighborhood:
- Provide a more attractive look to the facilities to better fit in with the neighborhood.
- Fund local public art guided by the Bayview Arts Master Plan.
- Support local hire and local contracting goals and requirements.
Funding for this project has been provided in full or in part through an agreement with the State Water Resources Control Board. California’s Clean Water State Revolving Fund is capitalized through a variety of funding sources, including grants from the United States Environmental Protection Agency and state bond proceeds. The contents of this document do not necessarily reflect the views and policies of the foregoing, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.
CONSTRUCTION UPDATES (Winter 2024-2025)
2024 saw the majority of the concrete and steel work on the Solids Pretreatment and Biosolids Dewatering Buildings completed. The domed steel covers were installed on all five digesters, and testing is well underway in the Digester Building.
The focus for 2025 will be construction of the remaining facilities for the Thermal Hydrolysis Process, Odor Control, Steam Generation and ancillary facilities, as well as mechanical, electrical and controls work in all facilities.
Testing will begin in 2026, with the introduction of prices fluids to the new digesters in the Fall of that year. Substantial Completion is anticipated in 2027, with Final Completion in 2028.
Office Hours and Contact Information
We want to hear from you. Use any of the below methods to connect with our team!
Construction Hotline: (415) 551-4737
Email: ssip@sfwater.org
After hours: Call 311 -
What to Expect During Construction
- Noise: Noise, vibration, dust, and traffic impacts in the work zone
- Access: Residents near the work zone will maintain access to their homes and businesses
- Construction Hours: Monday through Friday from 7:00 a.m. to 8:00 p.m. with occasional weekend work from 7:00 a.m. to 8:00 p.m. Residents and businesses will be notified in advance when weekend, nighttime, holiday or 24-hour work is required
- Transportation Impacts: Streets will be open for traffic throughout construction, with optional detour routes available. Delays should be expected. No impacts to Muni service are expected at this time
- Sewer Service: No interruptions to sewer service will occur during construction
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Project Materials
Headworks Project Page
The Biosolids Digester Facilities Project is being constructed at the Southeast Treatment Plant along with the New Headworks Facility. To learn more visit, sfpuc.gov/headworks
Combined, both projects will upgrade and modernize these aging facilities with more reliable, efficient, and modern technologies and facilities.