Westside Water Main

Westside Water Main map

The majority of Mountlake Terrace’s water system was originally installed in the 1950s and 1970s. This system generally experiences significant water loss due to leakage from these aged pipes and also has areas that do not satisfy current firefighting needs. Several water mains were selected for replacement based on:

  • The City’s Water Comprehensive Plans
  • Public Works engineers’ evaluation of risks of failure (their likelihood and magnitude of consequences)
  • Recent break history
  • Known failing conditions
  • Potential for cost savings when coordinated with other projects
  • Opportunities to address deficiencies in capacity and fire flow demand
  • Grouping locations within a general region within the city

The Westside Water Main Improvements identified for various locations west of I‑5 and designed by Public Works engineers include:

  1. 226th Place SW from 70th Avenue W – 73rd Place W
  2. 68th Place W from 226th Place SW – Cul-De-Sac 
  3. 67th Place W from Cul-De-Sac – 224th Street SW
  4. 224th Street SW from 65th Avenue W – 66th Avenue W 
  5. 65th Avenue W from 224th Street SW – Cul-De-Sac
  6. 67th Avenue W from 222nd Street SW – Cul-De-Sac
  7. 61st Place W from 212th Street SW – 215th Street SW
  8. 213th Place SW from 61st Place W – Cul-De-Sac
  9. 64th Avenue W from 219th Street SW – 220th Street SW
  10. 219th Street SW from 60th Avenue W – 64th Avenue W
  11. 60th Avenue W from 21503 Block – 219th Street SW
  12. 66th Avenue W from 216th Street SW – 220th Street SW
  13. The intersection of 236th Street SW and 49th Place W

Across these locations, the project includes construction of approximately:

  • 9,500 linear feet of earthquake-resistant 8- and 12-inch diameter ductile iron water main pipe
  • The replacement or addition of:
    • 69 gate valves assemblies
    • 24 fire hydrants
    • 3 Blow-off Assemblies
    • 2 Combination Air Release/Air Vacuum Valve Assemblies
    • 108 water service connections
    • Pressure reducing valve assemblies

The project also rehabilitate or upgrades 35 linear feet of Sanitary Sewer Main across the project sites that are impacted by the primary work. The works include minor restoration of concrete traffic curb and gutter, concrete sidewalk, asphalt pavement and landscaping, as well as traffic and erosion control.

Cost & Funding

*Rounded to the nearest $1,000

Total Estimated Cost  $7,728,000
Funded by a Washington State Public Works Board loan supported by water utility service fees


Design and Contract Document Preparation – Completed fall 2021

Construction – Early 2022

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