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Wastewater Treatment

King County, Washington

For questions about the Wastewater Treatment Division website, please send an e-mail message or contact us at:

King Street Center
201 S. Jackson St., Suite 500
Seattle, WA 98104-3855
Phone: 206-477-5371
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

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Staff Contacts

Murray CSO control project -- Building a new storage tank to protect Puget Sound

Project Construction

September 13, 2016 project update - Restoration begins. Connection between sewer lines and underground storage tank nearing completion.

Roadway and sidewalk restoration

Restoration work will continue intermittently for the rest of the project. Flaggers will be present during any lane closures. Expect variable road conditions, including loose gravel, pavement cuts, uneven surfaces, and steel plates. Cyclists should use extreme caution when traveling near the project area.

Underground storage tank and sewer line connection

The County’s contractor is nearing completion of the connection between the underground storage tank, 5-foot-wide sewer line, and local sewer line. A temporary bypass system was used to maintain sewer service to the neighborhood when work on the connection pipe began in July. To complete the connection, the contractor will need to use the temporary system again.
Starting the week of September 12, a pump from the temporary system will run continuously for five days (day and night) to move flows around the work zone. Odors may be more noticeable while the pump is running. Air quality will be monitored to ensure safe conditions. A representative from the contractor will be on site at all times to monitor the pump.

More on this work and what to expect (PDF).

Please direct any questions or concerns to the project hotline: 206-205-9186. .

Murray Project Hotline: 206-205-9186

Learn more about Final Facility Design
Final Design
, December 2012

Haul routes
Project haul routes
, February 2014

Murray basin and project location
Murray basin and project location

Project description

King County is designing an underground storage tank across the street from Seattle’s Lowman Beach Park. The tank will store approximately one million gallons when the Murray Pump Station exceeds maximum capacity.

Why do we need this project?

Protect public health

Like many cities around the country, the older parts of King County's wastewater system uses a single set of pipes to carry untreated sewage and stormwater to a treatment plant. To prevent sewer backups into homes and streets, the system includes safety valves called “combined sewer overflows” that route excess sewage and polluted stormwater flow directly into Puget Sound during storms. Although CSOs reduce potential exposure to untreated sewage, they pose significant public health concerns.

Clean up Puget Sound

The Murray CSO control facility will reduce CSOs into Puget Sound. State regulations require no more than one untreated discharge per year. The Murray Pump Station averages five untreated CSO events per year, discharging 5 million gallons into Puget Sound off of Lowman Beach Park.

Project schedule

Construction schedule

How has the community shaped facility design?

Since October 2011 Lowman Beach Park neighbors and park users have worked with local designers, environmentalists and community advocates to help the King County project team design a facility that fits with the community. These discussions produced “common themes” for the design that reflect the community’s values for a safe, reliable facility. The common themes are:

  • Minimize the “industrial facility” feel
  • Encourage views of Puget Sound
  • Discourage through traffic on Beach Drive
  • Enhance continuous space between Lowman Beach park and the facility site

Southbound vehicles on Beach Drive SW can use the access road south of the park to turn around
Southbound vehicles on Beach Drive SW can use the access road south of the park to turn around.

Have a question or concern? Please use the project feedback form.

Project updates

Find out if a CSO is occurring in Murray

Related information

  • To learn more about the Project Planning Phase (CSO control alternatives selection process in the Murray basin, 2007 to 2010), please see the Facility Plan.
  • Protecting Our Waters (Combined Sewer Overflow Control Program), King County 

For more information

This project is funded in part by:

Department of Ecology, State of Washington