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Mar
25

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)

During construction, all the wastewater carried through the M Street Trunk must be sent into a temporary system of pumps and diversion pipes above and below ground to maintain sewer service to the community. Where the diversion pipe is above ground, the project will use ramps to help people walking, rolling and driving safely across. Noise and odor control will be installed at critical points in the sewer diversion system.

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

Project Schedule

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

The construction schedule is organized by zones according to the different pipe diameters along the M Street Trunk. 

We will use spiral-wound lining technology for Zones 18 and 24 which allows crews to rehabilitate 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. We will also use the cure-in-place pipe (CIPP) technology for the rehabilitation of Zones 30 and 36 where this relining is most suited. Selection of those technologies consider cost, life span, impact on the public, constructability and future maintenance and operation.

  • During the pre-design phase, we will:

    • Approve the project charter
    • Explore the preliminary permit planning
    • Community service planning and interested parties’ (or stakeholders) analysis 

  • During the design phase, 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
    • Identify impacts on the surrounding community and develop appropriate outreach and communication plan
    • Launch project webpage
     

  • During the construction and close out 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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