Crew evaluates falling Rimrocks

2014-05-13T20:00:00Z 2014-05-21T16:42:24Z Crew evaluates falling RimrocksBy CHRIS CIOFFI ccioffi@billingsgazette.com The Billings Gazette

Tuesday morning on Timberline Drive, Barbara Herda was planting a row of golden beans in her neighbor's garden plot just feet from where sandstone boulders came to rest Monday after tumbling from the Rimrocks. 

"They come down on you, and they're a lot bigger than you think they are," Herda said. 

Rocks broke free from the Rims twice in less than 24 hours on Monday west of Zimmerman Trail. The first fell overnight and a second group fell at about 1:30 p.m.

The road has been closed since a rock slide took out part of a guardrail on March 25.

"I heard it at night about 2 or 2:30 a.m.," Herda said, but in the dark of night she didn't see much. "I didn't pay attention to it."

A neighbor told her exactly what the sound was on Monday morning. It's the first time they've seen rocks of this magnitude come down from the Rims near their homes.

"It's unnerving," she said. 

The new rock movement has made folks nervous, especially on Herda's street. In her backyard, a natural ridge in the Rims makes the likelihood of rocks falling onto her home unlikely, but two houses down, her neighbors had rocks in their backyard. They packed up their RV and spent the night somewhere else, she said.

"It's never been like this," she said. "I think some of these people are a little surprised."

She said her insurance policy likely does not cover rock slides, but she won't put a for sale sign in her yard any time soon. 

"The view up here is beautiful," she said. "I guess it's a risk you take for living up here."

Rock slides, usually referred to as earth movement by insurance companies, aren't typically covered in homeowner's policies, said Brian Fennern, an insurance agent at HUB International, which has an office in Billings.

"Our Rims are unique," he said. He said his firm searched for coverage on the issue last time rocks fell several years ago, but they came up empty. 

They reached out to large international insurance companies to help create a policy, but it never materialized because few people are willing to pay for the coverage. 

"There’s just not a lot of those situations," he said. When so few people want a certain type of coverage, not enough people are able to pay to share the risk. 

To minimize the risk, the Montana Department of Transportation has partnered with consulting engineering firm Terracon to come up with a plan to remove rocks in danger of falling.

"There’s five different rock block locations and eight scaling sites," said Paul Rieger, the project manager for MDT. Workers will rappel over the face of the Rims and use crowbars and expandable air bags to break the rock.

Earthen berms will be erected on the ditch and roadway of Zimmerman Trail to prevent rocks from sliding onto homes below. 

They plan to remove at least one block of sandstone with explosives, he said. The well-known, "Monkey Rock," a rock which has eroded in a way that resembles the face of a primate, will be "trim blasted." 

Workers will secure the site and six homes will be evacuated during the work to ensure no one gets hurt, he said.

The work will be done by Geostabilization International, costing the state $718,220. The work will begin soon, although an exact schedule has not been set, Rieger said. 

"The completion date in the contract, it’s June 13," he said.

A $9,000 per-day incentive has been established if the work gets done early, and the firm will be charged $9,000 each day the work goes over that date. 

While crews are in town, the city plans to take advantage of their services to remove rocks along where Sixth Avenue North and Main Street intersect. The City of Billings has also contracted with Terracon to survey the area below and above Sixth Avenue North. 

City of Billings Engineer Debi Meling said the situation is not as dire as over by Zimmerman Trail, but rocks have fallen onto the sidewalk or in the first lane of traffic.

"It’s very, very hard to give any indication on how soon we may see movement," she said. 

She said Terracon recommended that they should do some scaling along the face to break away sections of rock that pose a risk of falling, and they found one larger block that would need to be removed.

"In their opinion, they found a rock that would need to be dealt with," she said. In the next few days she said Terracon, the city and GSI will meet to talk specifics. "We are in discussions with them on how extensive the work will be and what the price will be." 

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