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About ESI 8
Get information about the ESI 8 Rehabilitation Project schedule, project need, and construction process.
Project need
King County Wastewater Treatment Division protects public health and the environment by collecting and cleaning wastewater and recovers valuable resources for a thriving Puget Sound region. ESI 8 is breaking down due to age and corrosion and needs to be repaired to prevent failure, overflow, or disruption of service. Completing this project will support the reliability of a key part of the regional wastewater treatment system on the Eastside for 50 years to come.
See video footage and LiDAR scans 1, 2, and 3 of the pipe.
Maintaining sewer service during the repair
To repair ESI Section 8, all the sewage it carries (approximately 55 million gallons per day during the dry season) will need to be sent into a temporary diversion system of pumps and pipes above ground. This temporary system will allow crews to work inside the existing pipe while maintaining sewer service to the community.
To limit disruptions to neighbors and commuters, the temporary diversion system will run at the ground surface along an inactive segment of the Eastside Rail Corridor (ERC) and will then cross below I-405 via a deep tunnel. The temporary system will reconnect with the standard wastewater system near Coal Creek Parkway, on the east side of I-405.
An example of a temporary wastewater diversion system. This system is used to maintain services while pipes are rehabilitated.
How we rehabilitate
After installing the temporary diversion system, we will then rehabilitate ESI 8 by “sliplining,” a rehabilitation method that pushes a slightly smaller reinforced pipe inside of the existing pipe. This method allows us to repair the pipeline without disturbing roads, trails, or sensitive environmental areas.
Construction crews inspect a new reinforced pipe as it is installed through a process called “sliplining.”
Most of the construction activity will take place at the north and south ESI 8 access points, and along the temporary diversion system alignment. We plan to engage the community before work begins to limit surprises and answer questions.
We have an opportunity to implement a different contracting method that other agencies, including other King County Departments, have successfully used before. One key component of this delivery method is the early collaboration on constructability with the contractor.
Project schedule
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Pre-design
During the pre-design, we will:
- Approve the project charter
- Explore the preliminary permit planning
- Community service planning and interested parties’ (or stakeholders) analysis
- Contracting KC’s project advisor
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Design
During the design stage, we will:
- Develop the design and construction schedule.
- Complete design including determining the location of the temporary diversion pipe which will carry wastewater during pipe rehabilitation, and the sewer rehabilitation approach and staging areas
- Acquire permits and local agency coordination
- Implementation of Early Work Packages to expedite construction.
- Identify impacts on the surrounding community and develop appropriate outreach and communication plan
- Launch project webpage
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Implementation and close out
During the implementation phase, we will:
- Prepare the site for construction
- Install and operate the temporary diversion system
- Rehabilitate the existing ESI 8 pipeline
- Demobilization of the temporary diversion systems once rehabilitation activities are complete
- Restore and clean up from construction
- Provide update to impacted neighbors and the surrounding communities.
- Close out