Washington Park Stormwater Tank Maintenance

Aerial image of SPU’s stormwater detention tank in Washington Park.
Aerial image of SPU’s stormwater detention tank in Washington Park.

Project Description

Seattle Public Utilities (SPU) owns and operates a stormwater storage tank in Washington Park near the Washington Park Playfield.

SPU is performing a maintenance project to improve the way this facility manages flows during rain events. This work will improve SPU's ability to monitor and control stormwater flows and allow us to use our existing infrastructure more efficiently.


SPU's stormwater storage tank is located near the Washington Park Playfield in the southern portion of Washington Park near E Roy Street, 29th Avenue E, and E Madison Street.

What's Happening Now?

SPU Contractor Crews began performing maintenance upgrades to the belowground storage tank in Washington Park in May 2021.

The maintenance upgrades are nearly complete. However, significant, ongoing shipment delays of equipment has delayed the project schedule. Therefore, the contractor will need to pause work in late December and resume in early 2022 (tentatively scheduled for February).

Prior to pausing work, SPU and the contractor will do the initial inspection and testing as well as perform landscape restoration in the park.

When the contractor resumes work in early 2022, they will install the remaining equipment. Once final installation, inspection, and testing are complete, the contractor will finish any remaining landscape restoration in the park and miscellaneous work in the tank.

Construction is expected to be completed within 1-2 months of resuming work.

SPU will share updates prior to resuming work in 2022, please sign up for the project email list to receive email updates about this maintenance project.

Community Benefits

SPU is performing this work to enhance the functionality of the stormwater tank and to improve SPU's ability to manage flows more efficiently while improving regional water quality.

Anticipated Impacts

Construction activities will be limited to the area of Washington Park closest to the stormwater storage tank, and much of the work will be performed belowground in the storage tank. When work is occurring, you can expect:

  • Crews to work 8 to 10-hour days Monday through Friday. Work hours and days may vary based on work being performed, and night or weekend work may be required.
  • Construction noise, dirt, dust, and vibrations
  • The contractor has reopened the southern section of the park, including pedestrian paths, and they will try to maintain access to the extent possible 
  • For safety reasons, the contractor may periodically fence off sections of the park near active construction zones
  • Increased construction traffic in the southern section of Washington Park near E Roy Street, 29th Avenue E, and E Madison Street
  • Staging of large equipment near the construction site
  • Landscape restoration to areas impacted by construction activities

Community Engagement

If you're interested in receiving updates about this maintenance project, please sign up for the project email list.


Late 2020

  • SPU awarded the contract and worked to bring the Contractor onboard

Early 2021

  • SPU and Contractor perform pre-construction activities
  • Construction begins in mid-May

Late 2021

  • Wrap up a majority of the storage tank upgrades and perform landscape restoration activities
  • Contractor will pause work in late December (delay in construction due to equipment shipping delays)

Early 2022

  • Contractor will return to install remaining equipment and will work with SPU to perform final inspection, testing, and restoration
  • Once the upgrades and restoration are complete (about 1-2 months after resuming work), the contractor will demobilize
  • Additional notice will be provided prior to and during this phase of construction

Project Documents