Sewer Pipeline Material Selection Is Easy, Right? It’s More Complex Than You Might Think

The City of San Mateo, CA, commissioned the planning, preliminary design, and final design of the Basins 2 and 3 Collection System Improvements (CSI) Project (herein referred to as the Project) with an objective of mitigating Sanitary Sewer Overflows (SSOs) within a large section of the City. To achieve the objective, the project identified locations in the City’s sewer system that were under capacity by utilizing hydraulic modeling to pinpoint areas of the sewer network prone to SSOs during wet weather events. Results of the hydraulic modeling led to development of several sewer design packages to enhance the collection system’s capacity to mitigate SSO occurrences. Each design package utilized various construction techniques and a variety of pipe materials. This paper provides a project case study and focuses on the details of the engineering solutions and the rationale behind why the selected pipeline materials were chosen.