King County’s planned sewer line upgrade through Bellevue has earned the nation’s first Salmon-Safe certification for a wastewater infrastructure project, according to county officials.
The $96.5 million Coal Creek Sewer Upgrade Project is designed not only to replace aging sewer infrastructure but also to restore the surrounding environment, improve fish habitat, and make local trails more accessible. Work is expected to begin this spring and continue for five years.
Salmon-Safe, a leading environmental certification organization, approved the project following a detailed, performance-based review.
The group praised the King County Wastewater Treatment Division’s design for minimizing ecological disruption while improving conditions for native salmon and other wildlife.
“This project is a perfect example of how we can achieve our environmental goals at the same time we improve quality of life for King County residents,” said King County Councilmember Claudia Balducci, who chairs the Regional Water Quality Committee.
The project will replace nearly two miles of sewer pipeline that was originally installed in the 1960s. The current pipe, which runs underneath Coal Creek and through the Coal Creek Natural Area, is approaching capacity as the population in Bellevue and Newcastle continues to grow.
Instead of following the creek’s path, the new pipeline will use a tunneling machine to bypass the sensitive natural area. This underground construction method is expected to reduce surface-level impacts. Portions of the current pipeline that lie within the creek will be removed. Native vegetation will be planted, and woody debris will be added to restore the creek’s natural functions.
Much of the existing pipe will be decommissioned and left in place to avoid unnecessary disruption.
The upgrade will also enhance the Red Cedar Trailhead, a popular entrance to the Coal Creek Natural Area. The trail will be improved to meet Americans with Disabilities Act standards and will include features like benches, a wider path surface suitable for wheelchairs and strollers, and a Braille trail with tactile signage.
Bellevue Mayor Lynne Robinson highlighted the partnership with King County as a model for combining environmental protection with public accessibility.
“We are thrilled to partner with King County on this vital wastewater project, which will also protect Coal Creek’s ability to support salmon and other wildlife,” Robinson said. “We are committed to creating recreational spaces that are inclusive and sustainable, ensuring they can be enjoyed by future generations.”
To protect fish and limit disruption to nearby neighborhoods, work in the creek will only occur during a three-month window each summer. A section of the hiking trail will be closed for at least three years, but an alternate path will be provided. Once construction is complete, the City of Bellevue will resume management of the restored areas.
The project was developed with input from the Muckleshoot Indian Tribe, the Washington Department of Fish and Wildlife, the City of Bellevue, and nearby residents.
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