Expect delays on Idaho 21 while rockslide repairs continue Thursday

A Boise man was injured when his truck hit a boulder on the road.

kterhune@idahostatesman.comNovember 20, 2013 

— Idaho Highway 21 will remain restricted to one lane Thursday near Lucky Peak Dam as state transportation workers repair guardrails along the runway.

Rockslides sent boulders and debris crashing down onto the highway early Wednesday, initially closing the entire road roughly 6 miles east of Interstate 84’s Gowen Road exit.

A collision with one of the fallen boulders sent a Boise man to the hospital shortly after 6:40 a.m. A truck driven by Richard Lovan, 36, drove over the boulder and came to rest in the middle of the road, Idaho State Police said.

Lovan, who was wearing a seatbelt, was taken by ambulance to St. Luke's Boise Medical Center. He was no longer listed as a patient there Wednesday evening.

The truck was the only vehicle involved in the crash, contrary to earlier reports from the Idaho Transportation Department that another vehicle had been involved.

Traffic for most of Wednesday was down to one lane, alternating eastbound and westbound vehicles with 15-minute waits. Road repairs are expected to be complete Thursday afternoon.

Reed Hollinshead with ITD said he didn't know exactly how much debris rolled onto the road.

Rain sent more rocks sliding down the slopes toward the highway after the initial slides, and the area was still classified as “unstable” Wednesday. Workers used a snowplow to push some of the boulders off the road.

Workers needed to wait until the ground dried before reopening the highway, Hollinshead said.

“We need the rain to stop so that hillside can dry up a bit. Once the hillside dries, then the hold on the rocks is better,” he said. “When it gets so wet, there is nothing to hold them back, and all the rocks are coming down.”

Seven sections of guardrail were cracked or damaged by the rocks and will have to be fixed, Hollinshead said.

Crews also hope to shore up the slopes to prevent future rockslides. But that could be difficult — the top of the hill overlooking the affected section of highway is privately owned, and ITD cannot make any repairs without the owner’s consent.

Hollinshead said ITD was attempting to contact the owner Wednesday and hoped to get permission for the work.

If they get the go-ahead, ITD will send “scalers” up the side of the ridge to remove or knock down any rocks that are teetering or loose.

After that, crews might use netting or a high-volume ground treatment to keep debris in place.

“We just need the rocks to stay embedded in the hillside instead of coming loose,” he said.

Rain, snowmelt or wildfires can all contribute to rockslides, Hollinshead said. Some areas are naturally more susceptible than others. The area of Wednesday’s slides, for example, doesn’t have a lot of vegetation, he said.

Though fires did burn near Lucky Peak Dam this summer, it wasn’t clear Wednesday if they contributed to the slides.

“In the areas where fires have affected the hillsides or there’s just a lack of vegetation, that’s generally where we see some of these rockfall problems, because there’s nothing to hold back any rocks,” Hollinshead said. “If there is vegetation, and it rains, the roots can soak in some of the water. But without the vegetation, it starts sloughing off the hillside and the rocks start to fall.”

Katie Terhune: 377-6219


View Rockslides block Idaho 21 east of Boise in a larger map

 

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