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About Interbay Sewer and Odor Control Upgrade

Find information about the Interbay Sewer and Odor Control Upgrade Project, including the project schedule and methods to upgrade the sewer pipes and control odors.

Project schedule

Project timeline for the Interbay Sewer and Odor Control Upgrade

Project design began in 2017 and was completed in 2023. Construction began in 2024 and will continue through 2027. View 2024 project newsletter for more information about the project.

Improving odor control and upgrading sewer pipes

King County’s project team has evaluated different methods for upgrading the sewer pipes and controlling odor, as not every method is right for every neighborhood.

Controlling Odor

Part of the sewer being upgraded consists of two parallel pipes. These pipes converge to become one larger pipe in a partially underground building, called a discharge structure, at the west end of the West Wheeler Street right-of-way (see project area map). Where the pipes converge, smells can be released into the air. To improve odor control, the County will install a pair of scrubbers (filters) at the discharge structure at the West Wheeler Street right-of way. 

Upgrading the sewer pipes

Most of the sewer will be repaired by lining the inside of the pipe using an innovative approach that involves blowing the new liner into the pipe with water pressure. The new liner covers any cracks or holes and strengthens the existing pipes.
 
Lining the pipe is more efficient and less expensive than replacing it and minimizes construction impacts. Instead of digging up the entire length of pipe, repair crews can access the pipe at a few key locations and blow in the new liner.
 
A small section of the pipes near Magnolia Bridge will be completely replaced because the pipes in that area need to be increased in size. We are also upgrading approximately 2,000 feet of pipe north of the discharge structure. The 35-year-old lining in this section of pipe is aging and needs to be replaced. 

Videos

EBI-8

FM #1 - West

FM #2 - East

 

Project area map

Interbay project site map

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