Friday, May 15, 2020

Rock fall leads to emergency closure on US 97A near Chelan


June 3, 2020
Granite Construction, LLC has been selected as the contractor for the emergency repair project above the Knapps Hill Tunnel. Work will begin on June 15 inside the current closure between mileposts 223-230 and is scheduled for 20 working days, weather permitting. This section of the highway will remain fully closed until this work is complete.

By Lauren Loebseck and Mike Allende

It's no secret that rocks falling onto US 97A south of Lake Chelan has been an ongoing issue. And while a project is scheduled to begin on May 20 to improve safety in that area, an increase in the frequency and severity of rockfalls at Knapps Hill Tunnel has made it necessary to close that section of road from milepost 223-230 to all traffic until mitigation can be made to the slope above the tunnel.
Rocks that have fallen onto US 97A. These rocks have exposed larger boulders higher up
the cliff that present significant hazards to traffic.

Inspection work by our crew determined that ongoing rockfalls has exposed and undermined larger boulders that are now at risk of falling onto the roadway, making it potentially too hazardous for travelers. We don't have a date yet on when this stretch of road will reopen.

Work on a rock slope scaling project to improve safety on that route was scheduled to begin on April 1, but the Stay Home, Stay Healthy proclamation paused most construction and maintenance work. That work is now ready to begin and crews will begin flagging traffic through the area during the day on May 20 and 21, with delays expected to last up to 20 minutes. Starting May 26, day-long closures of the highway will be in place from 8 a.m. to 5 p.m. through June 15.
Left: A drone’s-eye look at the cliff high above Knapps Hill Tunnel where large rocks that could come down from the cliff have forced a closure of the highway. Right: The path that rocks are falling off the cliff into US 97A
near Knapps Hill Tunnel, leading the highway to be closed.

Repair of the Knapps Hill Tunnel area was not part of the rock slope scaling project and instead was a separate project scheduled to begin in August or September of this year. But with the emergency closure now in place, we are working to expedite that project as soon as possible, though we don't have a schedule yet.

This situation is developing, and details will become clear as we work through moving the emergency work to construction. Updates will be provided via travel advisories and social media. We know this creates logistical challenges for many, and we are eager to safely reopen the tunnel once it is safe to do so.