Under High Pressure—Relining a 90-Year-Old Pipeline

The Crystal Springs Pipeline No. 2 (CSPL2) is a 60-in. diameter lap-welded steel pipeline that is part of the San Francisco Public Utilities Commission's (SFPUC) regional water transmission system. The pipeline passes through eight regional jurisdictions (unincorporated San Mateo County; Town of Hillsborough; Cities of San Mateo, Burlingame, Millbrae, San Bruno, South San Francisco, and Daly City) before terminating at University Mound Reservoir in the City and County of San Francisco. Owned and operated by the SFPUC, the CSPL2 has supplied potable water to communities along the San Francisco Peninsula for 90 years. CSPL2 is divided into eight sections (reaches), with Reach 5 being 20,300 linear feet of 60-in. diameter, coal tar enamel (CTE) lined and coated 0.5 in. thick steel pipe running through backyards and narrow streets in a densely populated residential area. SFPUC plans to remove the CTE lining in the pipeline, which will extend the useful life of Reach 5. To lay a solid foundation for the final design, the project team initiated a multi-phased planning process addressing the environmental challenges, spatial constraints, and unique circumstances shaped by coal tar removal and disposal. The planning phase began in 2020, with the final design scheduled to be completed in the spring of 2025.