High risk from rocks

High risk from rocks

November 18th, 2009 by Adam Crisp in News

Staff Photo by Dan Henry Traffic passes an area of Cummings Highway, SR 2, on Tuesday that has been designated as rock slide prone according to local officials.

Staff Photo by Dan Henry Traffic passes an area...

Thirty-five locations in Tennessee are ripe for a rock slide -- including three in Hamilton County, according to a Tennessee Department of Transportation report.

But funding and the incentive to shore up the problems appear to be low.

The fragile Ocoee Gorge mountainside that collapsed and closed a scenic two-lane road in Polk County was on a high-risk list of problem slopes for at least five years, and 10 other spots along the gorge also are on the list.

"Based on the history, that was an area that had been reported to us (as having repeated rock slides) over the years," said Len Oliver, a civil engineering manager and coordinator of the statewide effort to map potential rock slides. "But it's not that we can predict these slides will occur."

In Hamilton County, three mountainsides are inspected and tracked regularly for potential slides and are considered as the most susceptible for future slides. Two are on Lookout Mountain -- Cummings Highway and Scenic Highway -- and another is along a busy stretch of Signal Mountain Boulevard heading up Signal Mountain.

Last Tuesday's slide closed U.S. Highway 64 and effectively cut Polk County in half. The slide, which increased some residents' commutes by an hour or more, will cost $2.1 million and take at least two months to clear the 3,000 dump truck loads of rock and debris, state officials estimate.

The state is trying to mitigate damage from future slides, but TDOT has only allocated about $2 million annually to the task, Mr. Oliver said.

Gov. Phil Bredesen said Tuesday that 92 to 93 percent of federal stimulus money for roads already has been spent, but it "could conceivably play a role" in projects that reduce the risk posed by rock slides. Such projects would have to qualify as "shovel-ready" for stimulus funds to be used, he said.

Gov. Bredesen said he has spoken with TDOT Commissioner Gerald Nicely about options for increasing funds for preventing rock slides, but now is not the time to raise funds by increasing the gas tax, which pays for roadwork across the state.


Despite the list of hazardous sites, one geologist said the danger to motorists and residents is negligible because odds are long that anyone will be caught up in a rock slide.

"Living around these things is not a big safety concern. Most rock slides are over within seconds," said Dr. Robert Hatcher Jr., distinguished scientist and geologist at the University of Tennessee.

"If you had an infinite amount of money, you could get in there and take out all that rock," he said.

State officials began trying to track and head off rock slides nearly a decade ago, Mr. Oliver said, mostly because closed roads are an inconvenience and a threat to commerce.

"When rock slides close a road, that's a major socio-economic impact," Mr. Oliver said. "All the sites on the list ... one component of that considers what is the impact if rock did fall in that area."

But in some cases, making repairs would be as troublesome as having a rock slide.

"At the Ocoee Gorge, because the rockface is right at the road, you would have to do that under a road closure," Mr. Oliver said.


Residents and political leaders say the closure of U.S. 64 proves that there needs to be an alternative to the tiny, winding road, which is traveled by both truckers, commuters and sightseers.

But an alternative route currently being studied -- a four-lane project known as Corridor K -- would cost more than $1 billion, said Julie Oaks, TDOT spokeswoman.

Politicians that represent the area say the project deserves increased attention now.

"Our constituents and residents in Polk County, as well as residents of North Carolina, Georgia and, most of all Tennessee, are finding this to be a big inconvenience," said Rep. Eric Watson, R-Cleveland. "If this (rock slide) would have happened during the rafting season, and someone was hurt on the river, it would have delayed emergency assistance by an hour or more."

Staff Writer Matt Wilson contributed to this story.


A state report lists 35 spots that might be at high risk for rock slides. Three of those are in Hamilton County and 18 are in the counties surrounding Chattanooga.

* Bledsoe County: On U.S. 30, one mile from its intersection with Cove Road. There was severe rock slide at this location previously.

* Grundy County: Monteagle Mountain, where a rock slide in 2000 closed all four lanes of Interstate 24.

* Marion: Three sites on Interstate 24 near the Grundy County line at Monteagle Mountain.

* Polk County: Eleven sites along U.S. 64 from mile marker 10 to mile marker 18. The site of a massive rock slide last Tuesday is one of the 11 sites.

* Rhea County: Along State Route 68 at mile marker 4 on Grandview Mountain on the Cumberland County line.

* Sequatchie County: On State Route 8 at mile marker 20 on Cagle Mountain.


Wet weather experienced since September is a major cause of last week's rock slide in Polk County, state geologists say.

"The heavy rains played a large role," said Dr. Robert Hatcher Jr., distinguished scientist and geologist at the University of Tennessee. "Another potential cause are earthquakes, but I don't think the minor earthquakes we've had recently would have contributed."

Slopes that are cut too steep when the road is built, and freezing-then-thawing temperatures also can lead to rock slides, said Randy Jones, a TDOT geologist. Tree roots that grow into rocks and push them apart can also be a contributor.