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About the Loop® Vehicle Maintenance Facility

Get information about the Loop® vehicle maintenance facility.

King County Wastewater Treatment Division (WTD) has designed a new maintenance and staging facility to maintain Loop vehicles. The new facility provides the opportunity to improve working conditions for drivers, and helps the County meet new federal regulations. The facility will be located in North Bend (exit 34 off I-90) on County-owned land.

The current facility is located in south Seattle, on land leased from the King County Airport. The lease on this land is now ending without the option to renew, requiring the County to relocate the current facility to the previously purchased site in North Bend.

The new facility will help meet federal regulations on driving time to keep drivers and the public safe by reducing driving time to no more than 11 hours per day.

King County has worked with the City of North Bend to obtain all necessary permits for the project.

About the new facility

The new facility will be a pre-engineered metal building, screened by trees and a perimeter fence. Most likely, you will see very little of the new building if you are walking, biking, or driving by. The below image shows what someone might see if they looked directly into the site from SE 144th Street. 


  • The facility will include a maintenance shop, parking for staff, and Loop vehicles.
  • The site will retain a city-required buffer of existing trees surrounding the facility.
  • Vehicles will enter the site on SE 144th Street and exit the site on SE 146th Street.
  • The facility will be designed to reduce idling time, noise and emissions.
  • Normal maintenance hours are 6 a.m. to 6 p.m. daily. There will be activities at this site 24 hours daily with trucks leaving and entering from their trips at different times of the day.
  • The facility will be used by King County’s haul contractor. This includes drivers, mechanics, and operational managers.


What you can expect when the project is complete

The County recognizes that traffic in the area is a concern for neighbors and those living and working in North Bend, particularly in the area of I-90 exit 34. The County developed designated vehicle routes to minimize effects to the surrounding community. Once the new Loop facility is built:

  • The site will retain a City-required buffer of existing trees surrounding the facility.
  • All Loop vehicles will remain on-site, except when entering, exiting, or refueling.
  • Normal operating hours are 6 a.m. to 6 p.m. daily. There will be activity at this site 24 hours daily with trucks leaving and entering from their trips at different times of the day.

Learn more about King County project phases and how we work with the public.


Frequently asked questions

Loop biosolids are a nutrient-rich soil amendment created from King County wastewater. As it has for the past 40 years, King County produces Loop from solids extracted during the wastewater treatment process. Loop is used on agricultural crops and forests by commercial growers in both eastern and western Washington. As an ingredient in GroCo compost, Loop has been used on gardens and landscapes for decades.

Using Loop as a soil amendment closes the nutrient loop: harvested plants take nutrients from soil, humans obtain nutrients from the plants, and then we return nutrients to soil with Loop. Loop is an endlessly renewable resource restoring carbon and nutrients to the land for the good of plants, people, and Puget Sound.

Loop delivers a full suite of macro- and micronutrients, making it a superior source of plant food over synthetic fertilizers. It has a proven ability to improve soil structure, thereby reducing runoff and erosion. Loop biosolids are held to rigorous standards by the Environmental Protection Agency and the State of Washington. Choosing to use Loop as a soil amendment reduces greenhouse gas emissions into the atmosphere. It has enriched Pacific Northwest landscapes as an ingredient in the commercial product GroCo since 1976.

Learn more about Loop biosolids.

A Loop vehicle and attached trailer is approximately 75 feet long. You can identify a Loop vehicle by its Loop® logo on the side or back.

About 14 Loop vehicles and drivers will use the facility on a typical day. There will also be maintenance and operations staff on site daily.

Vehicles will enter and exit the facility at different times of the day.

Currently, Loop trucks transport material to our forestry projects within King County and agricultural projects in Douglas and Yakima counties. To accomplish this drivers navigate city traffic, mountain passes and inclement weather.

Occasionally, Loop biosolids may smell depending on how long the loaded trucks are parked on site. However, in over 20 years at the current facility King County received only one odor complaint. Loop biosolids are fully contained and enclosed by the transport vehicles. Loop biosolids will not be processed at the maintenance facility.

The site’s purpose is to provide facilities that better serve Loop staff and to prepare the vehicles to pick up and transport Loop product. Additionally, staff will perform routine vehicle maintenance, cleaning, and staging.

In late 2016-early 2017, the project team engaged the public to understand community perspectives on elements including choice of plants for landscaping and color of the building. The project team used the feedback collected to guide the final design of the facility and its landscaping. See the project renderings to preview what the facility will look like once construction is complete.


As part of the project, King County will plant new trees and landscaping on the project site. The County will also keep many of the existing trees, as required by the City of North Bend, around the perimeter of the facility. Below is a landscape design concept that illustrates where existing trees will be kept and where new plants will be installed.


Noise at the site will include Loop vehicles entering and exiting the facility. Other noise at the site could include sounds from typical vehicle maintenance activities.

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, with trucks arriving back from their trips at different times of the day.