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Project update

July 2022

We held property owner briefings in May 2022 to inform community members with properties located within the immediate vicinity of the Lake Hills sewer relining project about the project overview and schedule. Thank you to those who attended! If you missed it, you can view the recording here and check out the presentation slides .

Read more about the Lake Hills sewer relining project in our Winter 2022 newsletter , including information on where the temporary pipes may go during construction in spring/summer 2023.

If you would like to schedule an informational briefing for your community group, contact Eunice Lee at 206-263-1614 or

The Lake Hills Sewer Relining Project is part of King County Wastewater Treatment Division’s Pipeline Corrosion Rehabilitation Program.

Why is King County rehabilitating the Lake Hills sewer pipe?

The Lake Hills Interceptor is a sewer pipe that collects and carries wastewater from homes and businesses in Bellevue to the South Treatment Plant in Renton for treatment.

Now over 50 years old, the Lake Hills sewer pipe is experiencing corrosion, and needs to be relined so it does not fail, overflow, or disrupt service. To protect the community and the environment, King County is planning to rehabilitate a 7,200-foot-long section of the pipe. This project will extend the useful life of this pipeline for another 50 years.

We have selected to rehabilitate instead of replace this sewer pipe because it is less expensive and has fewer surface construction impacts when compared to building new replacement pipes.

What are the benefits?

  • Extend the useful life of the pipe for another 50 years
  • Maintain reliable service for our customers
  • Improve water quality in our region

Project description

As part of the project, King County will install pipe lining along approximately 7,200 feet of the 48-inch and 54-inch diameter concrete pipe. We will use a spiral wound technology, which allows crews to rebuild the pipe from the inside. Crews can feed the spiral wound lining in through maintenance holes, which speeds up the construction process and helps to minimize impacts to the community by repairing the pipe in its current placement.

The pipes need to be dry during lining, so we will need to reroute existing wastewater into a smaller temporary pipe. This temporary pipe would likely be routed above ground along streets, partially trenched, or be outfitted with ramps to help people and vehicles safely travel across. The map below shows the proposed route for where the temporary pipe will be located during construction that is planned to begin in 2023. Construction is expected to take up to six months.

While the sewer line is being relined, there are temporary bypass sewer lines in place.

Learn more below about how we extend the life of our pipes by lining them:

Courtesy of Sekisui

What temporary impacts can you expect during construction?

Construction impacts will likely include lane closures, detours, and equipment staging along the project area. Additional impacts may include noise and odors from the diversion pumps. This project may include overnight work. We will share more details as plans develop and will keep the community informed.


This project will have multiple phases:
2021: During predesign, we will:
  • Decide what methods we will use to reline the pipe
  • Determine the location of the temporary pipe, which will carry wastewater during the relining project
  • Identify impacts on the surrounding community
Spring 2022 – Spring 2023: This year, we will begin designing the project. During this phase, we will:
  • Design the temporary pipe
  • Determine what permits are needed
  • Communicate plans with impacted neighbors and the surrounding community
Spring – Fall 2023: We will begin project construction in the dry season (May-October) of 2023. During construction, we will:
  • Prepare the site for construction
  • Install the temporary pipe
  • Line the pipe in place
  • Restore and clean up from construction
  • Provide updates to impacted neighbors and the surrounding community

Planning Phase

Contact us

Contact Eunice Lee at:

If you’d like to receive email or text updates on the Lake Hills sewer relining project:

Project location

Project Area MapProject area map

Back to the capital projects overview map .

Library and resources

Thursday, March 3, 2022
12:00 pm
Zoom meeting