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Project update

April 6, 2021

Construction for the Georgetown Wet Weather Treatment Station is now 77 percent complete! View the March construction update to learn more!

Crew in a pit next to pipe casing.In early March, crews successfully installed 72-inch steel casing pipe underneath the First Avenue Bridge near the intersection of South River Street and South Michigan Street.


As of January 5, 2021, conveyance construction is now 92% complete! Work is expected to wrap up May 2021 when all pipes are installed along South River Street and the work areas are fully restored.

Once complete, underground pipes will carry treated flows from the station to the outfall structure where they will be released into the Duwamish River.

Treatment Station

Construction work at the treatment station continues to progress into 2021 and is anticipated to wrap up in 2022!

A view of crews erecting steel reinforcement beams for the treatment station’s ballasted sedimentation and ultraviolet disinfectant building roofA view of the treatment station’s ballasted sedimentation and ultraviolet disinfectant buildings at the treatment station site.

Take a look at our virtual construction progress on the Georgetown Wet Weather Treatment Station!

Mire nuestro video de recorrido virtual para enterarse de lo que hemos logrado en los sitios de desagüe, transporte y la estación de tratamiento.

King County’s Georgetown Wet Weather Treatment Station celebrates Platinum Achievement Award for Sustainability

King County’s Georgetown Wet Weather Treatment Station earned the coveted “Platinum” rating from the Institute for Sustainable Infrastructure’s Envision rating system. This is the first Platinum-awarded Envision project in Washington and recognizes the County’s commitment to sustainable communities and the environment. View news release.

Project description

Rendering of Georgetown Wet Weather Treatment SystemSite of future Georgetown Wet Weather Treatment Station at the corner of 4th Avenue South and South Michigan Street. (View other wet weather treatment facilities.)

The Georgetown Wet Weather Treatment Station Project includes the construction of a combined sewer overflow (CSO) wet weather treatment station between the Brandon Street and South Michigan Street Regulator Stations, related pipes and a new outfall structure to release the treated water into the Duwamish River. When constructed, the station can treat up to 70 million gallons of combined rain and wastewater a day that would otherwise have discharged directly to the Duwamish without treatment during storm events.

This project will help clean up the Duwamish River by treating stormwater runoff and sewage during heavy rains. Right now, heavy rains can fill up our sewer pipes, sending polluted runoff and sewage through a pipe into the river. King County began on-site work in April 2017 and expects to finish construction in 2022.

Wet Weather Treatment StationWet weather treatment stations clean overflows locally on-site during heavy rain storms.


Through a competitive process, King County awarded the construction contracts to three separate contractors.

In spring 2018, King County’s contractor Flatiron West, Inc. started treatment station construction. In the summer of 2018, Pacific Pile and Marine began the construction on the new outfall structure and in the fall of 2018, JW Fowler Company also began preparation work to construct the conveyance pipeline which will connect the treatment station to the outfall.

project timeline


Contact us

Construction hotline:

Contact Bibiana Ocheke-Ameh at:


 Feedback form

Facility Address:
6185 4th Ave S, Seattle, 98108

Sign up for email or text updates on the public involvement page.

King County partnered with Nature Consortium and Seattle Public Schools to teach 5th graders at Maple Elementary about water conservation and create art for the construction fence. View more project videos in the Library.

Project location


Back to the capital projects overview map .

aerial map of the project area