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Project update

August 2022

Construction is expected to be completed by fall of 2022. For more information on the estimated schedule, see project schedule below. Read more in our latest project newsletter .

Wondering what the new facility will look like? Here is our current rendering :

Rendering of the Loop Vehicle Maintenance Facility

What is the Loop Vehicle Maintenance Facility Project?

King County Wastewater Treatment Division (WTD) is designing a new vehicle maintenance and staging facility for transporting Loop biosolids. The new facility will be located in North Bend (exit 34 off I-90) on County-owned land.

Why is King County building this facility?

  • The current vehicle facility is located in south Seattle, on a space leased from the King County Airport. The lease on this land is now ending without the option to renew, requiring WTD to relocate the facility.
  • Helps meet new federal regulations that limit the time a driver can be on the road.
  • This facility reduces driving time and improves safety for every traveler on our highways and roads.

Learn more: view about this project and frequently asked questions.

What are Loop biosolids?

Loop biosolids are a nutrient-rich soil amendment created from King County wastewater. As it has for 40 years, the County produces Loop from solids extracted during the wastewater treatment process. Loop is used on farms and forests by commercial growers in both Eastern and Western Washington.

Learn more about Loop biosolids at:


Contact us

Construction hotline:  206-296-7432

Contact Eunice Lee at:

Project schedule

This schedule is subject to change and will be updated as the project moves forward.

Fall 2022
  • June 2021: install clearing limit fencing; begin clearing site, install fencing
  • July 2021: site preparation continues, selective tree removal and disposal of topsoil
  • August 2021: begin laying sewer lines and storm drains
  • Fall 2021: begin concrete slabs and foundations and structural work
  • Winter 2022: install pre-engineered metal erect steel building and metal roof and siding
  • Spring 2022: begin mechanical, plumbing, HVAC, and electrical
  • Summer 2022: landscaping and plantings
  • Fall 2022: project scheduled for completion by November 2022
  • Daily operation hours will be 6 a.m. to 6 p.m. with activities on site 24 hours a day
  • New trees will be planted and landscaping will be completed at the project site
  • Loop biosoilds will be fully contained; they will not be processed at this facility

Working with the community

King County will work with the public, community groups, and other key stakeholders to provide project information, identify potential impacts, and involve the community during construction where possible.

Community members can expect:

  • Advanced notice of meetings and construction
  • Community group and neighbor briefings
  • Project newsletters and fliers
  • Project web page updates, including frequently asked questions
  • Construction hotline

Project location

Back to the capital projects overview map .

project site mapThis project is located in North Bend, WA. The site is between 468th Avenue SE, SE 144th Street, and SE 146th Street, off I-90 east, exit 34. View larger version of map .