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Project update

February 12, 2018

Station construction is expected to begin in Spring 2018!

Read the latest project update for more information.

Ground-breaking celebration on March 1st

Please join King County’s project team and Executive Dow Constantine on March 1st, 2018 to celebrate the start of construction on the treatment station! View invite .

March 1, 2018
1 p.m. to 2 p.m.
Treatment station site
6185 4th Avenue South, Seattle

We recommend wearing appropriate closed-toe footwear. Refreshments from a local Georgetown bakery will be provided. For special accommodations please contact Bibiana Ocheke-Ameh.

Project description

Georgetown Wet Weather Treatment StationSite of future Georgetown Wet Weather Treatment Station at the corner of 4th Avenue South and South Michigan Street.

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 year, King County’s contractor completed demolition and site preparation activities. Demolition activities included removing buildings, underground structures, asphalt, and utilities. The site has been graded and prepared for treatment station construction.

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 Treatment Station construction contract to Flatiron West Inc. Major construction will start in 2018. Through two additional competitive processes, the County will award two construction contracts to build the new pipes and outfall structure into the Duwamish River in late 2017 and early 2018. 

Project timeline


Contact us

Construction hotline:

Contact Kristine Cramer at:


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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.

Project location


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