Heavy Civil GC/CM Services for MDCSO Wet Weather Treatment Station

The contract pertains to the construction and preconstruction services for the Wet Weather Treatment Station (WWTS) at the mouth of the Duwamish River, designed to treat combined sewer overflows before discharge into the east waterway. The project involves the development of a comprehensive treatment facility that includes an underground 4 million-gallon equalization basin, screening systems, pumping infrastructure, ballasted sedimentation technology with ultraviolet (UV) disinfection, solids handling, odor control, and site surface improvements. The scope also encompasses demolition of existing structures, shoring, excavation, soil management—including contaminated soils—and the installation of influent piping, instrumentation, and controls. The facility aims to enhance water quality and environmental compliance, with an expected project completion date of December 31, 2034. The procurement process includes multiple addenda that update insurance requirements, scope of work, and project principles such as lean construction and Building Information Modeling (BIM) integration. The solicitation, issued by King County, seeks a heavy civil general contractor/construction manager (GC/CM) with a project size estimated between $50 million and $150 million, with the total project cost likely exceeding $1 billion. The contract documents feature draft agreements for both preconstruction and construction phases, outlining scope, schedule, cost, subcontracting, insurance, and compliance requirements. The process emphasizes collaboration, adherence to state regulations, and integrated project delivery methods, with a focus on timely completion and environmental stewardship. The project represents a significant infrastructure investment aimed at improving wastewater management and waterway health in the region.