Fremont to Queen Anne Water Main Replacement

What & Why

The Fremont to Queen Anne Water Main Replacement Project will construct a new 24-inch drinking water feeder main in a utility tunnel (or “utilidor”) under the Ship Canal between Fremont and Queen Anne. Feeder mains provide drinking water service to several neighborhoods. The new feeder will replace an existing main that had served Seattle for almost 100 years and was taken out of service in 2011 because it had reached the end of its service life.


In July 2011, the existing water main was taken out of service due to a leak. During this service outage, SPU agreed not to replace the utility until the expected 2017 completion of King County’s Fremont Siphon project to minimize construction impacts to the community. The purpose of the Fremont Siphon project was to install a new King County siphon to transport combined sewage (wastewater & stormwater) under the Ship Canal and retire two combined sewage pipelines co-located within the Seattle utilidor that provided that purpose.

What’s happening now?

Construction planned to start in October 2018. The majority of Phase 1 work will take place south of the waterway in Queen Anne.

Phase 1: Fall 2018 and Winter 2018/9

  • Site mobilization and preparation
  • Remove water and existing pipes from the tunnel beneath the Ship Canal
  • Replace pipe support structures and install electrical conduits systems
  • Install new 24-inch water main pipe
  • Begin building valve chambers (which allow operations and maintenance staff to safely access water valves close to the surface) on both sides of the Ship Canal  
  • Traffic and Burke-Gilman Trail detours in Fremont

Phase 2: Spring and Summer 2019

  • Reconfigure traffic and Burke-Gilman Trail detours
  • Install water main connections to the existing system
  • Install water main components in the valve chambers
  • Install monitoring and electrical equipment
  • Site restoration
  • Site demobilization

Construction Impacts

Work will occur in Fremont near Fremont Canal Park and in West Ewing Mini Park in Queen Anne. The latter will be closed for the duration of construction. SPU will continue providing updates to nearby neighbors in advance of and during construction. In general, customers can anticipate the following construction impacts:

  • Increased noise, dust and construction traffic
  • Temporary staging of equipment and construction vehicles near the project area
  • Burke-Gilman Trail detour for part of construction (detour signage will be posted for pedestrians and cyclists)
  • Roadway detours on or near 2nd Ave NW and NW Canal St (detour signage will be posted) 

Project goals and benefits

In addition to conveying drinking water across the Ship Canal, the new feeder main will:

  • Improve service levels as far north as Ballard, west to Interbay and Magnolia, and to neighborhoods in the immediate vicinity including the base of Queen Anne hill on the east, north and west side, and Fremont
  • Improve water system pressure and fire flow (the flow rate of water from hydrants used by firefighters) Ensure service reliability in the event other drinking water infrastructure is disrupted