AC Water Main Replacements

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The City’s water distribution system includes more than 113 miles of water mains of varying age, size, material, and condition. Most of the system is composed of cast iron and ductile iron pipe, but there are nearly five miles of asbestos-cement (AC) pipe and one mile of steel pipe. Pressurized AC pipe is a material known for developing leaks and breaks as it nears the latter part of its expected life. The AC pipe in the Mercer Island water system was primarily installed in the late 1950s and early 1960s, making it some of the oldest piping within the distribution system.

The purpose of this project is to systematically eliminate all AC water mains within the City of Mercer Island over a six-year period by replacing approximately 5,000 feet of AC pipe per year. This is the first replacement project within the new AC Water Main Replacement Program.

New locations for AC pipe replacement will be added yearly until all AC mains have been replaced. This page is dedicated to information on all AC pipe replacement projects.

The City’s water distribution system includes more than 113 miles of water mains of varying age, size, material, and condition. Most of the system is composed of cast iron and ductile iron pipe, but there are nearly five miles of asbestos-cement (AC) pipe and one mile of steel pipe. Pressurized AC pipe is a material known for developing leaks and breaks as it nears the latter part of its expected life. The AC pipe in the Mercer Island water system was primarily installed in the late 1950s and early 1960s, making it some of the oldest piping within the distribution system.

The purpose of this project is to systematically eliminate all AC water mains within the City of Mercer Island over a six-year period by replacing approximately 5,000 feet of AC pipe per year. This is the first replacement project within the new AC Water Main Replacement Program.

New locations for AC pipe replacement will be added yearly until all AC mains have been replaced. This page is dedicated to information on all AC pipe replacement projects.

  • 2024 AC Water Main Replacements

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    Project Details/Neighborhood
    • SE Gallagher Hill Rd (3700 Block to 3600 Block)
    • Greenbrier Lane (SE 40th St, north to Gallagher Hill Rd)
    • SE 40th St from Greenbrier Lane to 93rd Ave SE
    • 93rd and 94th Ave SE from SE 40th St to SE 43rd St
    • Crestwood Place

    Project Timeline

    • Planning/Design (Q4 2023 – Q2 2024)
    • Construction Timeline (Q3 2024– Q2 2025)

    Estimated Budget

    • $3.159 M

    Project ID: WU0135



    Status Updates

    Week of April 1, 2025

    As of the beginning of April, the contractor is expecting additional connection work on April 1, 8, 15 and 22. The April 8 and 15 connection work will require shutdowns of water service for some residents in the area. Residents will be notified in advance of any shutdowns that may affect their water service with postcards and doorhangers.

    March 2025

    On Greenbrier Lane, the new water main is in service. For 93rd and 94th Avenues in Mercerwood, the installation of all water main line is complete and Kar-Vel Construction crews have installed approximately 40 percent of the new water services. This week, the contractor installed a new valve cluster at Mercerwood Drive and 93rd Avenue. Next week, crews will connect their new water main into the existing City system at this location, which will charge all the new mains and allow the contractor to begin switching homes over to the new water mains. There will be additional water shutdowns in the project area throughout April to complete the remaining connections between the new water mains and the existing City water system. Residents will be notified in advance of any shutdowns that may affect their water service. Pavement restoration work will commence once the watermain connections and water service work on the project is mostly complete.


    December 12, 2024

    Kar-Vel Construction has completed water main installation on Greenbrier Lane just north of SE 40th Street. They are scheduled to flush the new system next week and will begin connecting the new water services to residents’ water meters. In addition, the contractor is starting to install new water main on 93rd Ave SE, heading south from SE 40th Street into the Mercerwood neighborhood.

    October 4, 2024

    Construction work is scheduled to begin at the end of October to replace old asbestos cement water mains in the upper Mercerwood neighborhood, east of the high school. Construction will take several months, with project completion anticipated in spring of 2025.

    September 2024

    An onsite preconstruction meeting was performed last week with Kar-Vel Construction. Notice To Proceed for the project will be given for the end of October 2024 to start work on Greenbrier Lane, as well in the upper Mercerwood neighborhood, just east of the high school. This project begins a multi-year effort to replace all of the asbestos cement (AC) watermain within that neighborhood.

    July 2024

    This project is scheduled to be awarded at the July 16 City Council meeting to by Kar-Vel Construction. The City anticipates that work on this project will begin in September 2024

    March 2024
    Design work for replacing asbestos cement (AC) water mains is in the 90% design stage, with bidding planned for late May. A second water main project to replace aging and undersized mains is in the 60% design stage. Staff plan to stagger the construction of these two major projects, with the AC main starting in summer and the other project following a few months later. There will be additional AC main replacement projects over the next 6 years.

    January 2024

    This project has just completed a 15% review meeting and is moving forward to 60% design. Project is scheduled to advertise for construction bids in late spring 2024.

    December 2023

    The site survey for this project has been completed and staff will be meeting with the consultant soon to discuss preliminary location and alignments for the new water mains. A significant amount of this project is located within the Mercerwood neighborhood.

    Planning/Design
    In September of 2023, Consor North America, Inc was hired as the design consultant. Survey for this project begins in early November 2023 and should continue over the next several weeks.

Page last updated: 02 Apr 2025, 04:35 PM