Report Says Slide Couldn’T Be Predicted But Corps Of Engineers Official Says Springs Near U.S. 95 Should Have Been Obvious

The massive construction-related mudslide that closed U.S. Highway 95 last fall could not have been reasonably predicted or prevented, according to a report released Friday.

The Idaho Department of Transportation had prepared for instability related to a historic landslide in the draw north of Bonners Ferry. But it was artesian springs that caused the October disaster, according to Landslide Technologies.

“The artesian water condition was not well known locally, nor designed for,” reported engineer George Machan.

Although more analysis of the site might have found greater problems, he wrote, “it would have been unreasonable to expect prediction of a massive and catastrophic landslide failure.”

That conclusion baffles Mike Doherty of the U.S. Army Corps of Engineers, whose agency permitted the work.

“There were artesian springs all over that hillside. You didn’t even need to do any drilling to see it,” Doherty said.

Stock ponds and horse troughs were located there precisely because they would fill with spring water, Doherty said.

The two-page executive summary of the report was released late Friday from the department’s Boise office. The full report will be available in the Coeur d’Alene district office on Monday, said spokeswoman Barbara Babic.

Landslide Technologies is a Portland consulting firm hired by the Transportation Department to investigate the cause of the slide. It occurred during widening of U.S. 95, a long-awaited $18 million project which began last summer and will continue this year.

The mudslide closed the highway for three weeks, causing commercial traffic to be routed through Montana. Because school buses couldn’t safely use the detour routes, Bonners Ferry schools were closed. There was major disruption to Boundary County lives and businesses.

It cost an estimated $1.5 million to reconstruct the highway and improve detour routes. The state is still seeking $8.3 million in federal emergency aid, which also covers such costs as traffic control, repairs to a damaged railroad and drainage district, restoration of farmland and power lines.

Despite the report, Doherty is convinced that different construction practices might have prevented the mudslide. Too much excavation was being done at once, he said, and construction that went on past mid-September risked wet weather and increased runoff.

“They shouldn’t have been opening up so much ground, they shouldn’t have been working so late in the year. They won’t be doing that under our permit in the future.”

He said he met this week with Jim Roletto, the state engineer in charge of the project, and “he agreed with me on that.”

Roletto could not be reached for comment late Friday.

The agencies will meet again this week to determine when work can safely start up again this spring, Doherty said.

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