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Project update

May 2, 2022

Weekend lane closures extended through May 8

map displaying lane closure (westbound) along South Michigan Street, between 4th Ave South and West Marginal Way S.Expect temporary lane closures while crews form and pour curbs and sidewalks on East Marginal Way and South Michigan Street.

King County crews will close a lane of traffic on East Marginal Way and South Michigan Street over the next couple of weekends to complete curb and sidewalk installation near the new wet weather treatment station in Georgetown. As part of this work, crews will demolish existing concrete to prepare for curbs/sidewalk installation. After the install, crews will allow curbs and sidewalks to dry before removing forms and traffic control.

Crews will also restore a roadway panel on S. Michigan St. that was previously demolished to make connections to the new treatment station site.

To keep people traveling near the work area safe during this time, the sidewalk will be closed 24/7 until a new sidewalk has been installed.

Read the April 29 Project Update .

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

If you’d like to receive email or text updates on the Georgetown Wet Weather Treatment Station:

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.