KELLOGG, Idaho — Nearly two months after a dip in I-90 near Kellogg was discovered, authorities still aren't entirely sure what is causing the depression. The section of road, meanwhile, continues to sink, albeit at a slower pace than before.
Since the dip appeared in both lanes of the highway, the Idaho Transportation Department has temporarily laid asphalt on a small section of I-90 in an effort to smooth out the road. Accompanying signage has warned drivers of the depression and ITD has temporarily lowered the speed limit in the area.
ITD initially suspected water running under the road to be the cause of the dip. But following initial tests and observations, a definitive cause behind the depressions has yet to be confirmed, according to ITD spokeswoman Megan Sausser.
Sausser directed additional questions regarding the depression to the Environmental Protection Agency, which has been working alongside ITD, the U.S. Army Corps of Engineers, and the Idaho Department of Environmental Quality to assess the area. The EPA has been conducting various tests in the area surrounding the dips, said Sausser.
"EPA continues to work in close coordination with the State of Idaho and the Army Corps. of Engineers to investigate groundwater dynamics near the site of the I-90 subsidence. We are drilling monitoring wells and will be installing new extraction wells within the next several weeks that are expected to offer more and better data about groundwater flow and what may be impacting the Interstate," said Bill Dunbar, spokesman for EPA Region 10.
Sausser said that the section of I-90 was continuing to dip, but the rate of "settlement" had appeared to slow. The rate could change depending on area runoff, she said.
On Friday, ITD was planning on laying more asphalt on the dips in an effort to temporarily fix them.
"We've got to keep it safe for everyone," said Sausser.
One lane closures on I-90 in the area would be in effect where necessary, she said.
Sausser added that a permanent fix to the highway wouldn't likely happen until late summer at the earliest. ITD was awaiting on EPA data before making any more decisions.
According to Sausser, ITD wasn't aware of any accidents or vehicle damage caused by the dips in the road. Staff at Nickerson Towing, located in nearby Smelterville, told KREM they hadn't responded to any accidents related to the dip but had witnessed at least two instances of trailers that had appeared to have been damaged after going over the depression.
