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Project update

February 22, 2019

You may have noticed that our conveyance project area has jumped to the top of the update this month. That’s because we have some big news to share – crews are preparing for roadway work starting as early as March. We are working closely with the Seattle Department of Transportation and King County Metro to minimize pedestrian, driver, and bus rider impacts, and keep folks moving safely through our work area.

road detourBeginning in early March, South River Street underneath the First Avenue South Bridge will be closed for approximately three months. Crews will complete necessary conveyance work, including surveying in the roadway, trenching, placing pipe, and backfilling. A detour route for trucks and commuters is shown in blue on the map above. The detour uses Occidental Avenue South and South Michigan Street.

The pipe was floated into position and then sunk at night to take advantage of the tide. Earlier this month, crews successfully installed the first portion of a 54-inch outfall pipe in the Duwamish River. The pipe was installed on the evening of February 4 by crews using two small flat boats to tow segments along the Duwamish River. Once the pipe was in place, a crane and excavator were used to sink the pipe into the Duwamish River. Then, divers helped connect the new pipe to the pipe that had been installed previously.

Read the latest project update for more information.

What to expect during construction:

  • Excavation activities and pipe installation continue at treatment station, conveyance, and outfall sites through the end of the year.
  • Increased truck traffic going in and out of all construction sites.
  • Increased noise and vibration levels as sheet piles are installed.
  • Work is completed weekdays during the following hours:
    • Station and outfall: 7 a.m. to 6 p.m.
    • Conveyance pipes: 6 a.m. to 2:30 p.m.
  • Drills, pumps, excavators, cranes and trucks working on project sites.
  • Hotline staffed 24/7: 206-205-9286

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:


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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. View more project videos in the Library.

Project location


Back to the capital projects overview map .