Murray Combined Sewer Overflow Control Facility

This $26 million project was designed to prevent sewer backups and eventual sewer overflows during heavy rain events in the West Seattle region of the greater Seattle area.

In solving this problem, Shimmick constructed a below grade, 100-foot-diameter, 50-foot-deep secant pile tank capable of holding one million gallons of sewage. This tank is the storage device that replaced the existing system set up for a raw sewage discharge to the Puget Sound. In addition to the large below grade tank construction, Shimmick constructed a facility building with the mechanical piping and electrical systems to properly handle the sewage and tie in to the existing sewer system.

Once the below grade tank and facility building was finished, the facility was capped with a green roof, sustainable rain garden, and viewing platform looking out onto the Puget Sound. The technical challenges of a cramped project site and tight access made this a project perfect for Shimmick.