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Project update

June 29, 2021

Progress continues on final design

King County’s final design for the Interbay sewer and odor control upgrade is well underway. We expect to hire and contractor and start construction in 2022. We will be in touch in the coming months with information on what you can expect during construction.

SEPA public comment period complete

King County issued a State Environmental Policy Act (SEPA) Determination of Non-Significance (DNS) on June 11, 2021. King County accepted public comments on the DNS through June 28, 2021. Thank you to those who reviewed and provided comment.

Copies of the DNS and environmental checklist will remain available as a resource on the project’s library page.

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

planning phase

Contact us

Contact Kelly Foley Kruse at:



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Project location

Interbay-Sewer-location-mapView higher resolution version.

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project fact sheetProject fact sheet