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King County Washington home

Interbay sewer and odor control upgrade

The Interbay Sewer and Odor Control Upgrade Project will replace aging sewer pipes in Seattle’s Interbay neighborhood and add new odor control technology.

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. Major construction is expected to begin in 2024. When complete, the sewer will provide reliable service for another 50 years or more.

Project update

Summer 2026

Construction work continues at the Interbay Pump Station

Construction continues on the new odor control facility near West Wheeler Street. Earlier this year, crews completed the concrete roof and continued excavation to remove the old force main. During excavation, crews also completed dewatering near the pump station next to the Magnolia Bridge. Dewatering removes water from the work area so crews can safely reach the pipes and complete construction.

Crews have also made good progress replacing and relining the two force mains that carry wastewater from the pump station to King County's regional treatment plant. A force main is a pressurized sewer pipe that carries wastewater uphill from a sewer pump. Work on the second force main is expected to be complete later this summer.

What's next: Crews will continue work on the second force main later this summer while construction progresses on the new odor control facility.

Project location

View project area map on the About page.