Repairs to ID-11 Slide Near Headquarters to Start Next Week
Idaho Department of Transportation
LEWISTON--Repairs to the Idaho Highway 11 slide south of Headquarters will begin Monday, October 4, and last through mid-November.
“Monitoring devices have shown no movement since we installed them in the spring, so we are now able to start work,” Project Manager Erin Buck said.
The highway first sank in April, eventually creating an eight-foot drop-off. ITD bored underneath the highway to collect soil samples in May to determine the severity of the issue and identify the best long-term repair.
Download a photo of the slide from April 16.
Download a photo of the slide from April 19.
Download a photo of the slide from April 23.
“We will construct a soil nail wall,” Buck said. “At a high level, this involves boring into the slope and using 40-foot nails to connect the failing material to the stable material.”
One lane of the highway will remain closed, but traffic will be guided by temporary signals rather than the yield signs that have been in place.
This type of repair has been used successfully to mitigate other slides in the region, including the 2017 slide at Bear Ridge Grade north of Kendrick on Idaho Highway 3.
Knife River, the contractor that resurfaced seven miles of ID-11 between Grangemont Road and Headquarters earlier this summer, will complete the repairs for $1.1 million.