Temporary fix begins for I-90 road 'dips'

KELLOGG — Work crews with the Idaho Transportation Department and other assisting agencies applied a temporary fix to the depressions on Interstate 90 near Kellogg on Thursday.

These depressions (or “dips”), which have been affecting both west and eastbound lanes near milepost 48.6, gradually appeared over the course of the last couple weeks. In that time, they have been putting the suspensions of any vehicle that has gone over them to the test.

Signage had even been placed in the area to remind drivers to slow down from 75 mph to 45 mph when coming up on the dips.

ITD reported on Feb. 14 that crews with Interstate Concrete and Asphalt began performing a “mill and inlay” at 5 a.m. that morning.

This temporary fix involved adding layers of asphalt to the depressions to create a smoother driving surface. The process was completed one lane at a time and required traffic to be shifted over to the other lane.

While officials are hopeful that this temporary fix will hold, further work may be necessary throughout the winter to correct the dipping until a more permanent repair can be done in the spring or summer.

Neither ITD or the Environmental Protection Agency have determined an exact cause of the depressions as of Thursday.

ITD Communications Officer Megan Sausser stated in a previous interview with the News-Press that the damage could be the result of naturally accumulating water flowing deep under the ground toward the Coeur d’Alene River.

“Water under the roadway appears to be kind of washing deeply underneath it and deteriorating the road base there,” Sausser said. “It does look like it’s a wide swath that is cutting through because those depressions are about 700 feet apart.”

It also has not been confirmed or denied that the dips are a result of work associated with the Bunker Hill Central Treatment Plant Upgrade and Groundwater Collection System project.

“The Idaho Transportation Department is coordinating with other agencies in the area to investigate the cause of the damage and to develop a long-term fix for the depressions,” ITD Communications Officer Reed Hollinshead said in a news release.

The Groundwater Collection System Project has been in progress on the north side of Interstate 90 in that area since the summer of 2018. As part of the project, work crews have been installing a 20-30 foot underground wall between I-90 and the Central Impoundment Area (CIA, or locally referred to as the “slag pile”) to catch contaminated runoff that attempts to flow into the river.

The project has also included installing various wells and pipes for water extraction and collection.

Personnel with several different agencies have been surveying and investigating the affected areas since Feb. 9.

The Shoshone News-Press will continue to follow this story as it develops further.