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Project update

February 2023

Three county staff in construction vests viewing the exterior to the new Loop Vehicle Maintenance facility.   

The new Loop Vehicle Maintenance Facility is located at 47009 SE 144th in North Bend.

King County Wastewater Treatment Division completed construction of the new Loop Vehicle Maintenance Facility located at 47009 SE 144th, North Bend, WA 98045. The facility allows staff to maintain and stage vehicles that deliver nutrient-rich biosolids created from the wastewater treatment process to WTD’s forestry and agriculture customers in the Snoqualmie area and Eastern Washington.

After receiving its certificate of occupancy from the City of North Bend in November 2022, WTD relocated its Loop vehicle maintenance operations from the former site leased at the King County Airport in the Georgetown neighborhood of Seattle to the new 12,500 square feet facility in North Bend. The former site lease at the airport ended without the option to renew, and thus WTD relocated to County-owned property in North Bend.

The Loop Vehicle Maintenance Facility will help meet federal regulations for driving time to keep drivers and the public safe by reducing driving time to no more than 11 hours per day. It can be challenging for Loop trucks transporting biosolids to forestry projects within King County and agricultural projects across the state to work within that hourly limit.

Loop biosolids are fully contained and enclosed within the trucks and will not be processed at this site. Watch this video to learn how Loop gets made at a treatment plant and learn more about Loop here.

Man in yellow construction vest next to truck and trailer with "loop" logo on side of truck. Truck & trailer are inside new Loop vehnicle maintenance facility.  

The facility has three truck bays.

The facility maintenance building includes three truck bays, parking, equipment storage, landscaping and fencing. The project team used feedback collected from the community to guide the final design of the facility, including the color of the building and its landscaping. We planted native trees such as western red cedar and shrubs including vine maple, cascara, and pacific rhododendron. 

About 14 Loop vehicles and drivers will use the facility to maintain and stage vehicles on a typical day. Normal hours of operation will be between 6 a.m. and 6 p.m. daily. However, there will be activities at the site 24 hours daily due to trucks arriving from trips at different times of the day.

The Loop Vehicle Maintenance Facility is pursuing LEED Platinum Certification, which means the facility will improve efficiency, lower carbon emissions and create a healthier workplace. Certification will be completed in 2023. Additionally, reducing truck traffic in congested areas near the former site at the airport will also help reduce carbon emissions

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 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 .

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