 November 2024
King County Wastewater Treatment Division is planning to build a wastewater and stormwater storage tank near the First Avenue South Bridge to reduce combined sewer overflows into the Duwamish River, with construction expected to begin in summer 2025. Starting as early as December 2, 2024, crews will spend up to three days potholing, or digging small holes, near the future storage tank site in preparation for upcoming construction. This work will help King County to better understand the locations and condition of existing utility lines.
 What you can expect
- Work hours 7:30 a.m. to 5 p.m. daily for up to three days, starting as early as Monday, December 2. Work on Highland Park Way SW may happen at night to avoid disrupting traffic.
- Temporary lane closures with flaggers on site to assist vehicle and pedestrian movement.
- One drill rig and up to four service vehicles on site.
- Noise and slight vibrations during work hours, including engine noise and periodic hammering.
- Occasional truck traffic accessing the site during work hours.
Please watch for equipment and signs in the area, travel slowly to stay safe and follow direction from flaggers.
About the project
During storms, sewer pipes can fill with storm water that runs off roofs, driveways, and streets. When the system is overwhelmed, it is designed to overflow to rivers, lakes, and the Puget Sound. These events are called Combined Sewer Overflows, or CSOs. Even though CSOs help prevent backups into homes and businesses, they pose a risk to public health and the environment.
King County is working to reduce CSOs from the South Park drainage basin into the Duwamish River to no more than one overflow per year on average. To help accomplish this, King County is designing an underground storage tank near the First Avenue South bridge. The storage tank will hold stormwater and wastewater during large storms, which will prevent raw sewage from overflowing into the Duwamish River. After the storm, the water will flow to West Point Treatment Plant for cleaning.
The project is in the design phase, with construction estimated to begin in summer 2025.
 Project timeline.
 Questions?
Contact Daniel Arauz at 206-477-9953 or daarauz@kingcounty.gov
Visit the project website to learn about the project and the survey route map at kingcounty.gov/westduwamish-cso
Interpretation and translation services are available to you at no cost.
Alternative Formats Available: 206-477-5371 or TTY Relay: 711
|
