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Project updates

December 13, 2018

The project is almost done! (We have substantial completion on the project). The pipe lining is finished and the landscaping restoration has been planted. There are now only a few small items that need attention.

To all the residents nearby the project and users of Lake Hills Park - Thank you for your patience during our project. 

About the project - see the project newsletter (February 2018) to learn what this project was about.

Project description

Work began on this project in April 2018 and is expected to be completed by December. The project includes

  • Construction of access roads in the Lake Hills park to reach the project work areas
  • Dewatering operations where sewage flows are directed around where rehabilitation will be taking place in the pipes
  • Repair of corroded sections of the pipeline using a trenchless, below-ground construction method called ‘cured in place pipe’ lining 

(See ‘What does the project include?’ below, for more details.)

This project is a part of King County Wastewater Treatment Division’s Pipeline Corrosion Rehabilitation Program. Rehabilitating this line is less expensive and has fewer surface construction impacts when compared to building new replacement pipelines.

Why is King County rehabilitating the Eastgate Interceptor Pipeline in the Lake Hills Greenbelt Park?

The Eastgate Interceptor pipeline is a part of King County’s regional wastewater system. Pipelines carry wastewater from homes and businesses to our regional treatment plants.

The Eastgate line is about six miles long and consists of two parallel pipes. The first pipe was built in 1963, and the second pipe was added in 1983 to add capacity. A section of this sewer line runs through the Lake Hills Greenbelt in Bellevue.

Both Eastgate pipes are ageing and reaching the end of their service life. Substantial corrosion has been detected in the pipes, including the section which runs through the greenbelt. If these portions of the pipes are not fixed, the pipes could fail, which could disrupt service and result in wastewater overflows.

In order to protect the community and the environment, King County is rehabilitating both pipes along a 2,400 foot-long section of the Eastgate line. This project will extent the useful life of this pipeline another 50 years..

Project area

Download map and map with aerial background .

Project work areas and access road

King County used a pipe lining method called ‘cured in place pipe’ lining, or CIPP. This involved inserting a resin-coated liner into the pipes at manholes. The liner was rolled out and inflated to take the shape of the pipe. The liner was then cured with hot water to harden it in place.

The pipes needed to be dry during lining, so a temporary ‘bypass’ pipe was used during construction to carry wastewater around this section of the pipe.

The work in Lake Hills Greenbelt Park begin in early 2018 and is expect to take eight to nine months to complete. Two other lining projects along other sections of the Eastgate line have already been completed.

King County built temporary access roads and work pads around the existing manholes within the park. The work took place within some areas of the community Pea Patch and the Master Gardener’s demonstration garden, near the ranger station, and along parts of the Lake to Lake trail which runs through the park. The trail was kept open most of the time during construction, though there were short periods when the trail was closed to move construction vehicles and equipment..

  • Access roads, staging and work in parts of the park & garden area
  • Noise, odors, some tree and vegetation removal
  • Short-term and intermittent closures of the “Lake to Lake” trail to move construction equipment
  • Temporarily construction impacts to some park uses, activities, and programs
  • Construction traffic delays and disruptions on Southeast 16th Street
  • Temporary use of portions of the Lake Hills Greenbelt parking areas off Southeast 16th Street

King County is now working to restore all affected areas, including the demonstration and pea patch gardens, trails, and wetlands within the park. The County will replace trees and vegetation that were removed, and restore these areas to an equivalent state as it currently exists.

Project timeline

The work in Lake Hills Greenbelt Park begin in early 2018 and is expected to be take eight to nine months to complete.

Being a good neighbor

King County is committed to being a good neighbor and will work directly with the community throughout the project to minimize construction impacts whenever possible. During the project we send out project information, notices and updates about the work when available. Residents can expect:

  • Advance notice of construction activities—by mail, email, phone, door hangers
  • Project construction updates
  • Phone and email contacts, so you can easily contact county staff about the project

Stay informed and sign up for project updates

Please see the ‘For information about the project’ box in the right-hand column on this page to sign up for email or text updates, or to contact us with any questions or comments about the project. 


For information about the project

Sign up for project email or text updates (or manage your King County subscriptions).

For questions about the project, contact David Freed at: or at 206-263-9453

Project location

Locator map for Eastgate Interceptor rehabilitation (lining) - Phase 3

Back to the capital projects overview map .

Sewer pipe liner being inserted at a manhole on the County's Beach Drive lining project in West SeattleSewer pipe liner being inserted at a manhole on the county’s Beach Drive lining project in West Seattle.