I-90 'dips' continue to plague motorists

By CHANSE WATSON

Managing Editor

KELLOGG — Work crews from a variety of state and federal agencies continue to work on and investigate the depressions or “dips” present on Interstate 90 near Kellogg.

These dips, which have been affecting both westbound and eastbound lanes near milepost 48.6 for the last few weeks, have been putting the suspensions of any vehicle that has gone over them to the test.

Days after the depressions had been reported, personnel with the Idaho Transportation Department, Environmental Protection Agency, Idaho Department of Environmental Quality and U.S. Army Corps of Engineers arrived on scene to investigate and possibly fix the issue.

On Feb. 14, a temporary solution was put into motion that involved adding layers of asphalt to the depressions to create a smoother driving surface.

Since that time though, the depressions have once again returned in both new and previous filled areas.

“The depressions are still getting deeper,” said Megan Sausser, ITD communications officer. “So it is likely that ITD will make more temporary repairs similar to what motorists saw last week.”

A failure to determine the exact cause of the dips and adverse weather currently hinders ITD from initiating any long-term fix.

“Until we identify the source of the water, all we can do is monitor the road and make safety adjustments — such as reducing the speed limit — or temporary road repairs,” Sausser said.

In a previous interview with the News-Press, Sausser stated 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. It does look like it’s a wide swath that is cutting through because those depressions are about 700 feet apart.”

It 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 Groundwater Collection System Project has been in progress on primarily the south 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.

EPA Senior Public Information Officer Mark MacIntyre told the News-Press that “EPA, IDEQ and the ACOE are working on a parallel study of the groundwater to see if the construction work just south of the freeway is related in any way to the subsidence in the road bed.”

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.

“We are still in the data collection phase,” Sausser said. “After we have all the data, we’ll review it with the involved agencies and can start tackling the underlying issue. (The) key to solving this problem will be understanding what is causing it.”

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