North Marin Line Stabilization Project Final Supplemental IS/MND

Marin Municipal Water District is undertaking the North Marin Line Stabilization Project to replace two seismically unsound pipeline crossings of the North Marin Line in San Geronimo Creek, located near Sir Francis Drake Boulevard in Fairfax, California. One crossing will be replaced with approximately 1,700 feet of new pipeline installed beneath Sir Francis Drake Boulevard using open-cut methods, while the other will be replaced with a 36-inch diameter steel truss pipeline spanning the creek, supported by drilled piers and rising 2 to 3 feet above ground level before crossing. The existing pipelines and piles in the creek will be removed, and all work must be completed between August and November 2026. The new pipeline segments will maintain the same function as the current system, delivering water to Marin Water customers without interruption. Construction will occur within a 20-foot-wide pipeline easement and at designated staging areas including Kent Lake, Peters Dam, and the Leo T. Cronin parking lot, with strict adherence to CAL/OSHA safety standards and environmental protections. All work must comply with detailed soil compaction standards requiring 95% of maximum density for backfill materials, using Class II Aggregate Base, select sand, and native materials under ASTM and California Test Method specifications. Inspection and acceptance occur on-site at the construction locations by the District’s Engineer, with the contractor responsible for compliance, permit acquisition, debris removal, and correction of deficiencies at their own expense. Environmental mitigation measures are central to the project, including obligations to obtain a Lake or Streambed Alteration Agreement, pay CDFW filing fees, report species data to the California Natural Diversity Database, and implement erosion, dust, and noise controls. The project has undergone environmental review under CEQA as a Supplemental IS/MND, with no federal acquisition clauses, FAR provisions, or structured pricing in CLIN format identified; instead, the focus is on technical construction specifications, environmental compliance, and site-specific execution under the agency’s direct administration without designated COR, COTR, or PCO roles. Payments for environmental fees are directed to the California Department of Fish and Wildlife, but no federal accounting codes or invoicing systems are applicable.