Pump Station 22 Retrofit & Force Main Replacement Project

Photo of Salmon Bay Bridge over the Lake Washington Ship Canal.
Salmon Bay Bridge over the Lake Washington Ship Canal.

Project Description

The Magnolia Basin 60 is a combined sewer basin located south of the Ship Canal and directly to the east of Discovery Park. In this area, stormwater and sewage in the basin is collected and flows to Pump Station 22.
During heavy rain events, high volumes of stormwater can overwhelm the pump station causing an overflow into Salmon Bay. The combined mixture of stormwater and sewage can be harmful to humans, aquatic life, and other wildlife.
For the Pump Station 22 Retrofit and Force Main Replacement project, Seattle Public Utilities (SPU) will upgrade the pumping capacity of the pump station and the sewer pipeline in the Magnolia neighborhood.
This project will help reduce the number of overflows and improve water quality offshore. In addition, SPU will perform safety improvements to the pump station as part of the project.


Construction will occur along W Cramer St, 40th Ave W, and Commodore Way with most of the work occurring at the street end of W Cramer St.

What's Happening Now?

The contractor is working to finish installation of the sewer pipe connecting the pump station at W Cramer St to King County's sewer main under W Commodore Way.

Starting April 27, W Commodore Way will be fully closed to through traffic during daytime, working hours only. The contractor is currently scheduled to fully close of W Commodore Way to through traffic 24 hours a day starting May 7 for 2-4 weeks.

During this closure, please expect:

  • Local access for residents to be maintained on each side of the work zone, but no traffic will be able to travel directly through the work zone
  • Local access to driveways within the work zone will also be maintained, although this access may be temporarily restricted during work hours. The contractor will contact residents directly when temporary driveway restrictions are anticipated.
  • On-street parking within 100 ft on either side of the work area will be restricted
  • The sidewalk on the north side of the street will be restricted within 100 ft on either side of the work area and the sidewalk on the south side of the street will remain open

Following the pipe installation work, contractor crews will continue work at the pump station and complete pavement restoration.
Construction on this project is scheduled to be completed in late 2020.

Community Benefits

  1. New pavement and ADA ramps along the alignment of the new force main.
  2. Replacement of pump station infrastructure that is near the design life cycle.
  3. Better water quality by reducing combined sewer overflows.
  4. Improved safety conditions for SPU pump station maintenance crews.
  5. The creation of a shoreline viewpoint and public access at the street end of W. Cramer Street in accordance with Seattle Municipal Code 23.60A.578.

Anticipated Impacts

What you can expect during construction

  • Typical work hours are Monday through Friday, 7 a.m to 5:30 p.m.
  • Increased construction traffic, noise, dirt, and vibrations
  • Pavement excavation and restoration
  • Parking restrictions in areas adjacent to work zone
  • Local access to homes will be maintained to the extent possible
  • Lane reductions on 40th Ave W and W Commodore Way during force main replacement
    • During lane restrictions, flaggers will be onsite to maintain two-way traffic via the open lane.
    • When possible, the contractor will re-open travel lanes in both directions during nights and weekends
    • Access to driveways will generally be maintained through most of construction. The contractor will coordinate with impacted residents, as needed.
    • Starting in late April, W Commodore Way will be closed 24 per day for about 3-4 weeks while crews connect the new force main to King County's pipe. Local access and pedestrian access will be maintained. Through traffic will be detoured around the site. Please pay attention to onsite signage.
  • Regular solid waste pickup will be maintained
  • Emergency vehicles will continue to have access throughout construction

The contractor plans to stage equipment at Fort Lawton to mitigate construction equipment in the roadway. To access the potential staging area, the contractor will primarily use Texas Way and 40th Ave W.
SPU also performed work on an emergency force main replacement project in the area in 2019. That was a separate project to replace a damaged sewer force main that runs underneath the Shilshole Bay Waterway west of Commodore Park.

Community Engagement

SPU will provide updates to the community during construction. To receive updates about the project, please subscribe to the project email list.


Early 2018

  • Designed phase neighborhood outreach
  • Held community drop-in session
  • Project design continued

Mid 2018

  • Project design continued
  • Permitting and environmental review process

Late 2018

  • Conducted final design phase neighborhood outreach
  • Held community open house

Early 2019

  • Finalize design and award construction contract
  • Pre-construction community notification

Late 2019

  • Construction tentatively scheduled to begin in fall 2019 and take about 12 to 14 months*
  • Construction updates, as needed, via website and listserv

Mid- to Late 2020

  • Complete construction

*Schedule is dependent on weather and other factors.