King County About To Begin Construction on Murray Combined Sewer Project

Murray Timeline[This post contains updated information]

King County Wastewater Division has released additional information about the construction about to begin at the Lowman Beach Park combined sewer overflow location.

How will the facility be built?

  1. Stabilizing the hillside – the contractor will install soil nail walls by inserting steel rods into the hillside and attaching screens to them. Reinforcing the rods and screens with concrete adds stability to the walls and controls erosion.
  2. Controlling groundwater – A drill will install over 100 interlocking concrete cylinders called secant piles. These cylinders will extend into the ground to create a watertight ring that reduces the need for groundwater removal and safeguards against settlement.
  3. Positioning the storage tank underground – the watertight ring will measure nearly 100 feet wide and 80 feet deep. Building the tank will require excavating enough material to fill  Colman Pool twice!
  4. Building  the storage tank interior – to prevent the high groundwater from dislodging the tank, a 20-foot thick concrete slab will be installed below the tank. Crews will then build forms and pour concrete above the slab for the tank, the building walls and support columns, the tank’s roof, and a view deck.
  5. Connect the storage tank to the existing wastewater system – the tank’s power, water, ventilation and overflow pipes will run beneath Beach Drive Southwest to connect to the County’s pump station in Lowman Beach Park. The excavation in Beach Drive will be sequenced to keep the road open. A steel plate will cover the excavated trench after work hours.

What to expect

  • Work hours: 7 a.m. – 6 p.m., weekdays
  • Heavy equipment, increased activity and noise on and around the site
  • Beach Drive Southwest will remain open
  • No parking on the eastern side of Beach Drive Southwest
  • Lowman Beach Park facilities, beach remain open
  • Increased truck traffic, especially on Beach Drive Southwest and Lincoln Park Way Southwest

How will the facility fit into the neighborhood?

Lowman Beach and Lincoln Park users, community members and neighbors worked closely with the King County project team to develop a design that fi t with the community. The facility design incorporates the common themes the community identified:

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

Project Art

The facility’s public space and staircase to Lowman Beach Park will feature installations made out of “rammed earth” – highly compressed soils – taken from the site. Rammed earth is as durable as concrete and a much more environmentally sound material. All rammed earth features will be sealed to protect against graffiti and the marine environment.

Access to Lowman Beach Park facilities and beachfront will be maintained. Park users are encouraged to access the park through the 15-foot wide pathway north of the contractor project office. This pathway will remain open throughout construction. Parking on the west side of Beach Drive Southwest will be maintained once the trailers are installed.

Community members can call the project hotline at 206-205-9186 with any inquiries or concerns.

The Murray CSO Control Facility will safeguard Puget Sound by storing sewage and polluted stormwater during storms and preventing regional sewer system overflows into the water off of Lowman Beach Park. Construction is anticipated to start in December 2013 and be complete in the fall of 2016.

For more information about the new facility, please visit:

For more information contact Doug Marsano, Community Relations Lead, King County Wastewater Treatment Division, at 206-477-5549 or cell at 206-423-0480 or by email at