Wastewater Treatment Plant Outfall Relocation

Project overview

The wastewater treatment plant outfall project will extend the outfall up to 1,500 feet away to a depth that does not impact the commercial shellfish harvest zone. The Winslow Wastewater Treatment Plant provides secondary treatment followed by clarification and ultraviolet disinfection for a rated capacity of 1.2 million gallons per day maximum monthly average flow. Treated effluent is pumped through a 5,400-foot outfall extending onshore to Wing Point and then discharging into Puget Sound through a submerged 16-inch diameter concrete cylinder outfall pipeline. The outfall from the high-water mark off the east side of Wing Point to the terminus is 1,000 feet and -42 feet and is located in geoduck harvest track 07650, Tyee Shoal. This outfall extension is necessary to improve the closed shellfish harvesting zone and geoduck harvest track.