Skip to main content
King County logo


Natural Resources and Parks
Public Affairs

Geotechnical work starts in January for sewer line replacement near Coal Creek Parkway


Work to collect soil samples along the proposed alignment for a King County replacement sewer line near Coal Creek Parkway will require temporary travel lane closures beginning in early January. The work is expected to extend into mid-February.


Preliminary work is about to get underway on planned upgrades to an aging and undersized regional sewer line that is a critical part of King County’s clean-water infrastructure in Bellevue and Newcastle.

While construction on the Coal Creek Trunk sewer upgrade isn’t expected to begin until 2021, crews will begin drilling test holes in early January near Coal Creek Parkway to help determine soil conditions along the new line’s recommended alignment.

Starting Jan. 4, crews will perform two to four days of test drilling per week at five locations along Coal Creek Parkway.

The work is expected to take about five weeks to complete and will require travel lane, bicycle lane and sidewalk closures near drilling locations from 7 a.m. to 3:30 p.m., Monday through Friday. Some work could also occur on weekends to minimize weekday traffic impacts.

The proposed alignment for the 2 1/2-mile-long Coal Creek Trunk replacement sewer line protects sensitive areas by moving the line out of the Coal Creek Natural Area. The preferred route for the new sewer runs west of Coal Creek Parkway Southeast between I-405 and the parking lot at the Upper Coal Creek West Trail trailhead.

King County is committed to keeping interested citizens informed about this project:

• Sign up for text alerts by entering KING COALCREEK to 468-311;
• Project updates will be posted at;
• Call or email Monica Van der Vieren at 206-477-5502 or

This release is also posted on the Department of Natural Resources and Parks website: