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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

Project area

King County plans to design and build a one million gallon underground storage tank on private property across from Lowman Beach Park along Beach Drive Southwest. This facility will store peak flows when the Murray Pump Station reaches capacity. The project also involves an underground diversion structure located under Beach Drive Southwest and an ancillary equipment facility (mechanical and electrical unit) above ground on the storage tank site.

Facility Site Plan
Murray CSO Control Facility Site Plan
 (PDF) -- slide 3 from the Final Facility Design Presentation (PDF), December 11, 2012

Project elements

The project includes the following elements.

  • Property acquisition
  • An underground diversion structure located in Beach Drive Southwest 
  • A pipe connecting the diversion structure to the storage tank to convey peak flows during a wet weather event
  • An approximately 6,000 square foot underground storage tank across from Lowman Beach Park
  • Retaining wall to protect the existing hillside along the northeast, east, and south edges of the storage tank site
  • One story equipment facility including mechanical and electrical facilities, located above the storage tank 
  • Landscape restoration in Lowman Beach Park and above ground at the storage tank site
  • A green roof with viewing areas
  • Public walkway through the site with rain garden
  • 3,500 square foot public use space north of facility

Project design

Public walkway and rain garden
Public walkway and rain gardens (PDF), September 2012

Viewing areas and green roof
Viewing areas and green roof (PDF), September 2012

Draft Interpretive Sign Locations, Murray CSO Control Project
Draft interpretive sign location (PDF), September 2012

Learn more

Project site
Project site
 (PDF). King County plans to design and build an underground storage tank beneath private property across the street from Seattle’s Lowman Beach Park.

Underground storage tank facility concept.
Underground storage tank facility concept (PDF). This is a typical profile of an underground storage tank facility used for controlling flows in a wastewater conveyance system.

How the facility controls CSOs
How the underground storage facility control CSOs (PDF), September 2012

Final Facility Plan, September 2011