Windermere Basin
Reinforcement steel bars placed at the bottom of the tank - May 2013.
Tank under-drain system completed – April 2013.
Completed excavation for the 2.05 million gallon underground storage tank in Magnuson Park – March 2013.
Tree stumps on display along Sportsfield Drive.
Construction of 2.05 million gallon underground storage tank in Magnuson Park taken in January 2013.
Sewer and Stormwater Pollution
Currently, during normal weather conditions in Seattle, existing barriers in the sewer system in the Windermere Basin prevent combinations of wastewater and stormwater from overflowing into nearby Lake Washington. However, during episodes of heavy rainfall, these mixtures overcome the sewer barriers and flow into the lake.
Project Update June 14, 2013
Work to begin on Sand Point Way NE between NE 60th Street and NE 65th Street
Work to install a 60-inch diameter casing under Sand Point Way NE will begin on June 20. This work will require the north bound lanes of Sand Point Way NE to be closed between NE 60th St and NE 64th St for about 3 months. The current southbound lanes will be revised to allow traffic on one lane each direction during the closure. Motorists should expect traffic delays. See Sand Point Way NE traffic re-route map (pdf).
In order to expedite the work and minimize traffic and construction impacts to the public, crews will be working 6 days a week during the closure. Working hours will be 7 a.m. to 8 p.m., Monday through Friday, and 9 a.m. to 7 p.m. on Saturday. We hope to return this part of Sand Point Way NE to normal operating conditions in September.
Project Description and Benefits
The Windermere Sewage Overflow Prevention Project will improve these existing sewer systems to reduce the frequency and volume of sewer overflows into Lake Washington during periods of heavy rainfall.
Near Magnuson Park on the south side of NE 65th Street, the project team will install:
- A 2.05 million gallon (MG) underground storage tank
- A facility vault with mechanical and electrical equipment
Beneath NE 65th Street and Sand Point Way NE, the project team will install:
- A 2,250-foot-long gravity sewer and parallel forcemain
- Motor-operated gates to control the flow of wastewater into the tank
Map of construction area with pipeline sections color-coded by installation method.View an area map of where construction will occur (right). The staging area, tank site, and pipeline alignment are all displayed here. Sections of the pipeline are color-coded according to installation method.
After project completion, the local sewer system will divert sewage and stormwater into the new storage tank during heavy downpours. Once the rainfall subsides, the storage tank will empty the contents back into the sewer system for regular processing. Consequently, this new sewer system will reduce sewage and stormwater pollution in Lake Washington.
View Engineering Plans for the project (pdf)
Project Schedule
Onsite activities will last approximately two years, from September 2012 onwards. Level of onsite activities and potential temporary impacts in the community will vary by season and construction phase; the overall construction schedule is subject to change. Below is a visual sequence of when project activities begin.
Community Engagement
For more than two years prior to construction, the project team has reached out to Windermere residents, businesses, and community groups to discuss how the project will reduce sewer and stormwater pollution in Lake Washington. For a detailed list of these efforts, view the History of Windermere Basin Community Engagement (pdf).
Project Brochure
To learn more about this pollution prevention project, download the Windermere Basin project brochure (pdf).
Contact Us
Email the Windermere CSO project team at SPU_WCSO@seattle.gov to join our mailing list to receive regular updates or call us at (206) 386-9778 if you have specific questions or concerns.