Marin Water advances phase one of seismic stabilization for critical raw water line

Marin Water advances phase one of seismic stabilization for critical raw water lineThe district is preparing to bid out a $1.12 million project to replace aging 1957 infrastructure, ensuring uninterrupted flow to the San Geronimo Treatment Plant ahead of broader seismic upgrades.

Phase 1 replaces a 68-year-old control valve and 160 feet of 24-inch pipe to secure raw water transmission from the Kent and Nicasio reservoirs.

The district is repurposing 24-inch pipeline originally acquired for a Richmond-San Rafael Bridge project to supply materials for the upgrade.

Construction bids will open on August 18, 2026, with the engineer's estimate for construction set at $574,000.

The phase one work sets the stage for a second phase that will replace two seismically vulnerable creek crossings.

The Marin Municipal Water District in California is moving forward with Phase 1 of the North Marin Line Stabilization Project, a critical capital improvement effort designed to modernize raw water transmission and address seismic vulnerabilities. The North Marin Line, originally constructed in 1957, conveys raw water from the Kent and Nicasio reservoirs to the San Geronimo Water Treatment Plant. Phase 1 of the stabilization effort features a total budget of $1.12 million, with an engineer's estimate for construction set at $574,000. The project will install a new 24-inch control valve—known as the Shafter Valve—and approximately 160 feet of new 24-inch welded steel pipe near the Leo T. Cronin fish viewing area in Lagunitas. During a June 30, 2026 committee meeting, engineering staff noted a unique procurement advantage for the project. The district will utilize 24-inch pipeline that was previously purchased for a Richmond-San Rafael Bridge extension project. Staff confirmed that while the district sold back the unused remainder of that allotment, the retained pipe will be repurposed for the North Marin Line. Phase 1 is designed to install the necessary valves and piping to avoid disrupting water flow to the San Geronimo Treatment Plant. This continuity is critical for enabling Phase 2 of the project, which will replace two existing seismically vulnerable creek crossings, as well as a concurrent rehabilitation of the Tocaloma Pump Station. Construction for Phase 1 is estimated to last 424 days, with completion targeted for October 30, 2027. To comply with environmental regulations, the construction window is restricted to avoid the Northern Spotted Owl nesting season, which runs from February 1 to July 31. The project will require approximately 45 days of lane closures on Sir Francis Drake Boulevard. The district plans to open construction bids on August 18, 2026, and will recommend a contract award at a subsequent board meeting.