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Wastewater Treatment Division (WTD) operations and projects

WTD operations staff remain on the job 24/7 to ensure the region’s wastewater treatment service continues. More information on how to report a problem you believe may be related to the County’s wastewater treatment system is available here:

The King County Wastewater Treatment Division remains committed to sharing information and gathering feedback from community members about its work and projects. WTD staff remain available to answer questions via email and phone during regular business hours. Project information lines remain available and are being monitored for ongoing construction projects.

Project update

August 2020

King County to upgrade regional sewer pipelines in Interbay neighborhood

King County is planning to upgrade approximately one mile of its pipeline system extending from the Magnolia Bridge to just north of the Interbay Athletic Complex. Full construction for the project is expected to begin in 2022 with a small repair effort taking place in summer 2020. Learn more about this project here .

Some early construction taking place

Occurring now, summer 2020, the County is reinforcing a 200-foot section of sewer pipe from West Garfield Street (adjacent to the Interbay Pump Station) to just north of the Magnolia Bridge. View the construction notification and map here .

This section of pipe needs to be temporarily reinforced prior to the overall line replacement in 2022. Crews will dig down to the existing pipes and place additional concrete around several pipe joints that have been identified as potential weak spots.

This work will take approximately three months to complete and will not impact access to the Magnolia Bridge or its on and off ramps.

More information about this project:

Whether you work, live or recreate in the area, we know you may have questions or concerns. As the project proceeds, we’d like to get to know you better. The project team continues to reach out to neighbors and organizations in the project area. Interested in scheduling an individual meeting or briefing to learn more about the project? Contact Dana West at or call 206-477-5536 or TTY 711.

Sign up for project alerts

Be sure to sign up for project updates to stay up-to-date on the latest project information and upcoming events. To sign up for text alerts, text KING INTERBAY to 468-311.

Project description

King County plans to upgrade an aging sewer pipe in Seattle’s Interbay neighborhood. The existing pipe was built in 1967 and is nearing the end of its service life. New odor control technology will be added to the system while the sewer pipe upgrade is underway. When complete, the sewer will provide reliable service for another 50 years or more.

project site map

Project Timeline for Full Project

project timeline

Small Repair Effort, Summer 2020

schedule for temporary project, summer 2020

planning phase

Contact us

Dana West, Community Services:

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Project location

Interbay-Sewer-location-mapView higher resolution version.

Back to the capital projects overview map .

project fact sheetProject fact sheet