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About the M Street Trunk Rehabilitation

Get information about the M Street Trunk Rehabilitation schedule and design elements.

Project need

King County Wastewater Treatment Division protects public health and the environment by collecting and cleaning wastewater and recovering valuable resources for a thriving Puget Sound region. The M Street Trunk is deteriorating and needs to be rehabilitated so the pipeline does not fail, overflow, or disrupt sewer service resulting to impacts to public health and the environment. Rehabilitating the M Street Trunk will support the reliability of a key part of the regional wastewater treatment system.

Condition of the M Street Trunk on Closed Circuit Television Video (CCTV)

The rehabilitation work will require sewer diversion pumping through temporary above-ground bypass piping and odor control. Sewer diversion pumping allows construction crews to reroute sewage from the M Street Trunk into a temporary system of above ground pipes (bypass piping) so that the existing M Street Trunk can be rehabilitated while maintaining sewer service to the community. Odor control will be installed at critical points in the sewer diversion system to control odor.

We plan to engage the community before work begins to limit surprises and answer questions.

Project Schedule

Project timeline: 2022 to 2023 is presdesign, 2024 to 2025 is design, and 2026 to 2027 is implementation & close-out

  • During the pre-design, we will:

    • Approve the project charter
    • Explore the preliminary permit planning
    • Community service planning and interested parties’ (or stakeholders) analysis 
  • 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
    • Implement Early Work Packages to expedite construction
    • Identify impacts on the surrounding community and develop appropriate outreach and communication plan
    • Launch project webpage
     
  • During the implementation phase, we will:

    • Prepare the site for construction
    • Install and operate the temporary diversion system
    • Rehabilitate the existing M Street Trunk 
    • 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
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