Project schedule

Protecting the Coal Creek Natural Area

The existing Coal Creek Trunk is approximately 2.5 miles long and primarily follows the banks of Coal Creek in the Coal Creek Natural Area between Newcastle and I-405. The new pipeline alignment will move the active pipeline away from Coal Creek offering better protection to this sensitive environmental area.

The selected pipeline alignment also aims to decrease impacts to both the Natural Area and Coal Creek Parkway SE during construction.

Project elements

This map shows the project work areas and the construction methods King County’s contractor will use in each area. The contractor will install about 10,800 feet of pipe to build the new Coal Creek Trunk Sewer and re-establish connections to the City of Bellevue’s sewer collection system.

King County’s designers work to reduce community impacts and inconveniences where possible. But on large projects like this one, inconveniences are unavoidable. People can expect the Red Cedar trailhead to be closed for several years during construction, with a trail detour around the construction site. There will be traffic impacts during work close to the Parkway throughout construction.

Keep up to date to make sure you have the latest news and information.

View larger size.

Coal Creek Trail Detour

The Red Cedar trailhead is closed to all public use during construction. King County Wastewater Treatment Division coordinated early with the City of Bellevue to build a trail detour in 2021 around the work area in partnership with the City of Bellevue’s Well-KEPT program, a summer youth employment program. Please follow trail detour routes and stay out of fenced areas and the creek bank for your safety and to protect the Coal Creek Natural Area habitat.

Other trailheads in the area such as the Cinder Mine, Red Town, Coal Creek Family YMCA, and Forest Drive trailheads are available for trail users. Parking is available at Cinder Mine, Red Town, and Coal Creek Family YMCA trailheads.

After the pipe work is completed, the County’s contractor will restore the Coal Creek Natural Area to protect the creek, trails, and remaining infrastructure. The rebuilt Red Cedar Trailhead will retain the same look-and-feel while enhancing accessibility for visitors of all abilities. Visit our Trailhead Restoration StoryMap to learn more.