By CHANSE WATSON
KELLOGG — The Idaho Transportation Department is advising drivers to reduce their speed on Interstate 90 near Kellogg due to several dips in the road.
ITD Communications Officer Megan Sausser reports that two separate depressions have formed on the roadway and are affecting both east and westbound lanes around milepost 48.6. Signage has been placed in the area to remind drivers to slow down from 75 mph to 45 mph when coming up on the depressions.
The first western most dip going eastbound appeared some time ago, but has gotten noticeably worse since Feb. 5. The eastern most eastbound dip is relatively new and not as severe.
It is believed that these depressions are 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.”
Sausser would not confirm or deny that the depressions were caused by work associated with Bunker Hill Central Treatment Plant Upgrade and Groundwater Collection System project.
“We have not confirmed the source. The DEQ is helping us out with that. EPA is involved, Army Corp. of Engineers is involved.”
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 run-off that attempts to flow into the river.
The project also includes installing various wells and pipes for water extraction and collection.
EPA Senior Public Information Officer Mark MacIntyre told the News-Press On Feb. 8 that his agency is also working to fix the issue and identify the cause.
“We can confirm that EPA is mobilizing experts and equipment to the scene of a dip in the I-90 roadway near Kellogg, Idaho,” he said. “We are still gathering information about the situation, working with the Idaho Department of Environmental Quality, the Idaho Transportation Department and the U.S. Army Corps of Engineers to support the investigation as to the cause. Right now, we are assessing what expertise and technology we can provide that will be most useful in this response.”
Work crews could be seen near the problem areas along the interstate on Saturday and Sunday, and Sausser notes that “no further movement was noticed over the weekend.”
As for the road and a path to fix the damage, ITD will continue to monitor the area and investigate the source of the water to develop a long-term solution.
“Roadway issues like this typically require deep excavation and reconstruction of the road base,” Sausser said.
Temporary fixes to even out the roadway are scheduled to begin today and would involve laying more asphalt in the affected areas to create a flat surface. A major long-term solution will most likely not come about until spring, when the weather is more favorable for construction and the shifting has ceased.
The Shoshone News-Press will update this story when contact with other state and federal agencies can be made.