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Coal Creek sewer upgrade
The Coal Creek Sewer Upgrade Project will install new sewer pipes to carry more wastewater and meet the growing needs of Bellevue and Newcastle.
Project description
The Coal Creek Sewer Upgrade Project will upgrade a regional sewer line that serves Bellevue and Newcastle. Built between 1966 and 1991, the existing pipeline is nearing its maximum capacity and needs to be upgraded to carry more wastewater and meet the growing needs of the community.
Once installed, the new sewer pipe will serve the area for another 50 years or more.
Project update
January 16, 2026
Construction on Coal Creek Parkway SE starting this month
King County’s contractor is continuing to prepare work areas for active construction in Bellevue.
As early as January 26, King County’s contractor will start drilling north of the Coal Creek Parkway SE and Forest Drive SE intersection. Drilling work will last at least three weeks. We will provide updates on any changes to the expected work on our website and by email.
View work area and lane closure map, and what to expect.
Reminder: do not enter construction zones
The Red Cedar trailhead and other work areas are active construction zones and remain closed to all public use. 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. Stay out of fenced areas and the creek bank for your safety and to protect the Coal Creek Natural Area and salmon habitat.
Interested in a project briefing for your community group?
We are available to meet with you or come to your next community event. The project team will share the latest project information and talk about what will happen over the next several years of construction. Please contact Frances Kuo 206-492-6499 or CoalCreekProject@kingcounty.gov.
Sign up for the project email list to get updates, learn about construction, and find outreach activities that you can participate in!
Previous project updates
- Lane closure on Coal Creek Parkway SE, near I-405, starts December 9, December 9, 2025
- Lane closure on Coal Creek Parkway SE near Factoria Boulevard SE to begin as early as Dec. 1, November 26, 2025
- Early morning closure of Coal Creek Parkway SE on Nov. 19 and 20, November 12, 2025
- Southbound single-lane closures on Coal Creek Parkway SE begin as early as October 13, October 7, 2025
- Lane closure on Coal Creek Parkway SE near Red Cedar Trailhead, September 18, 2025
- Pre-construction survey closing soon!, August 29, 2025
- Red Cedar Trailhead closure beginning as early as June 17, June 16, 2025
- Red Cedar Trailhead closure and traffic impacts beginning as early as summer 2025, May 16, 2025
- Coal Creek project awarded Salmon-Safe Certification, April 17, 2025
- News release: King County’s major sewer upgrade in Bellevue is the first project of its kind to earn Salmon-Safe certification, simultaneously modernizing infrastructure and improving habitat, April 9, 2025
- King County's Coal Creek Sewer Upgrade Project is heading into construction in 2025!, April 2025
- Survey work in the Coal Creek Sewer Upgrade Project area beginning this month, March 11, 2025
- Heads up: Work in Coal Creek Natural Area beginning mid-July, July 9, 2024
- Crews will install equipment to monitor conditions in the Coal Creek Natural Area as early as April 24, April 26, 2024
- Construction starting this year!, March 3, 2025
- Protecting and restoring the Coal Creek project area, Winter 2023
- Protecting and restoring the Coal Creek project area, February 16, 2023
- Did you see the latest project updates? June 3, 2022
- Winter 2022 newsletter, March 2022
- Opportunities for input- one ends, another begins, January 6, 2022
- Bringing in the New Year with a project update, January 3, 2022
- Neighbor feedback needed on parking/transportation options on Forest Drive Southeast, August 16, 2021
- Tree surveys starting, and more time to add your input! August 9, 2021
- Reaching out to the community: Accessibility ideas for the Red Cedar Trailhead, July 27, 2021
- Crews will carry out surveys in the Coal Creek Natural Area beginning June 18, June 16, 2021
- Crews will carry out surveys in the Coal Creek Natural Area beginning April 14, April 8, 2021
- Upcoming geotechnical surveying near 130th Ave SE, March 1, 2021
- Field work continuing for the Coal Creek Sewer Upgrade Project, February 5, 2021
- Self-Guided Tour Signs, October 2020
- Project newsletter, September 2020
- Field work complete by Friday, August 28, trail impacts reduced on Thursday and Friday, August 26, 2020
- Field work making progress; expected to wrap up Friday, August 28, August 2020
- Field work underway in August- weekday trail closures beginning Monday August 3rd, July 2020
- Sewer upgrades in the works: Join us June 17 & 23 to learn more! June 2020
- Work coming up in Coal Creek Natural Area, May 2020
- Utility location with lane closure on Coal Creek Parkway starting as early as May 15, May 2020
- Final design is underway for the Coal Creek Sewer Upgrade Project! April 2020
- Roadwork with lane closures on Coal Creek Parkway starting as early as April 27, April 23, 2020
- Planned Coal Creek Natural Area surveying at the end of March and in early April, March 23, 2020
- Data gathering at pre-existing survey locations will start as early as February 26, February 19, 2020
- Minor maintenance activity in Coal Creek Parkway tomorrow, December 18, December 17, 2019
- Fall 2018 newsletter
- Field survey update: Work begins on Coal Creek Parkway Monday, July 15, July 12, 2019
- Field investigations coming up in Summer 2019, June 7, 2019
- Tree surveying for the Coal Creek Sewer Upgrade Project beginning May 7, May 2019
- Survey work in the Coal Creek Natural Area beginning March 11, February 2019
- A King County sewer upgrade project is coming to your area, December 2018.
(View online version.) - Tree surveying in Coal Creek Natural Area Wednesday-Thursday, September 5-6, August 2018
- Field work for a new sewer line in Coal Creek Area continues in July, July 2018
- Survey activity week of May 14, 2018, May 2018
- Geotechnical work in the Coal Creek Parkway area begins in January, updated January 9, 2018
- Geotechnical work in the Coal Creek Parkway area begins in January, December 2017