Folsom Area Stormwater Improvement Project
Overview
The Folsom Area Stormwater Improvement Project is a part of the San Francisco Public Utilities Commission's (SFPUC) flood resilience efforts.
The low-lying Inner Mission neighborhood surrounding 17th, 18th, and Folsom streets has been historically subject to flooding during moderate to heavy storms. The Folsom Area Stormwater Improvement Project will increase collection system capacity and reduce the risk of flooding by constructing and upsizing sewer pipes and boxes, as well as constructing a new stormwater tunnel.
NOTE: Even after this work is complete, this area will still be at risk of flooding during heavy rains. Additional resources are available at sfpuc.gov/rain-ready.
Overall Project Status Update and Timeline
- Tunnel construction plans are being finalized for Phase 2.
- We anticipate having a contractor on board for the next phases of work in 2026. At that time, we expect to have more information to share on the timeline and sequencing on the Phase 2 and Phase 3 construction impacts.
- Major construction activity on the remaining phases 2 and 3 are anticipated to begin in Spring 2027.
-
Project Background
The San Francisco Public Utilities Commission operates a combined sewer system that collects and treats San Francisco’s wastewater (sewage and stormwater). We are upgrading and modernizing our system to ensure we can continue to protect public health and the environment. One key area of investment includes enhancing flood resilience across the City through operational improvements, capital projects, and resources to help the public prepare for and recover from intense but inevitable storm events.
In late 2023, the San Francisco Public Utilities Commission began construction on the Folsom Area Stormwater Improvement Project, which will be constructed in several overlapping phases. The first phase of work upsized and upgraded sewers around the 17th and Folsom area, and will be followed by future phases in 2027.
The Folsom Area Stormwater Improvement Project will be constructed in four overlapping phases:
- Phase 1 (Sewer Pipe Upgrades): Upsize or construct approximately 2,855 linear feet of smaller sewer pipes (60-inch diameter and smaller). Completed in 2025.
- Phase 2 (Tunnel Construction): Construct a new 12-foot diameter stormwater tunnel, with a length of 4,000 linear feet, from approximately the intersection of Alameda Street and Florida Street to the intersection of 7th Street and Berry Street. Crews will excavate an entrance shaft, two exit shafts, and a turning spot for a tunnel boring machine. Extensive analysis has been done to evaluate the location of the tunnel and portals, and monitoring equipment will be used during construction.
- Phase 3 (Sewer Box Upgrades): Upsize and construct 3,200 linear feet of large box sewers along Florida Street, Treat Avenue, and Harrison Street, from Florida Street to 18th Street. Crews will excavate a portion of the block to install a large, approximately 20-foot wide sewer box to provide additional underground storage and conveyance capacity. Traffic detours and alternate access will likely be needed for several months in work areas.
- Phase 4 (Sewer Pipe Upgrades): Upsize or construct approximately 1,950 linear feet of larger sewer pipes and structures (larger than 60-inch diameter).
State Revolving Fund
Funding for the Folsom Area Stormwater Improvement Project has been provided in full or in part by the Clean Water State Revolving Fund 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.
-
What to Expect During Construction
As construction begins, regular project updates will be shared via mail, email, and Nextdoor.
- Noise: Noise, vibration, and dust in the work zone
- Traffic: Partial and/or full lane closures may be necessary to ensure safety of workers and the public. Advance notice and detour signage will be provided, as needed.
- Parking: Street parking may be impacted near construction zones. “No-parking” signs will be posted 72 hours in advance.
- Muni: Bus stops and schedules may be impacted during construction. Notice will be provided to riders in advance regarding any possible stop or schedule changes.
- Access: Access to driveways and entrances may be impacted during construction.
Notification to residents and businesses will be provided in advance.
Contact Information:
- Fill in the information box on the right to sign up for email updates.
- Project questions and SFPUC General Hotline: (877) 972-3569 (FLOW) or ssip@sfwater.org.
-
Project Materials
Sorry, no materials match your search.
