Sinkhole collapses as large as the one last week at the National Corvette Museum are uncommon, but smaller collapses occur regularly in Warren County.
“It’s a very typical feature of a karst environment,” said Ken Kuehn, distinguished professor of geology at Western Kentucky University.
Bowling Green is part of what Kuehn calls “the sinkhole plain” that extends from Elizabethtown to Tennessee.
“It’s not just a Bowling Green problem. It’s a regional problem,” he said. “But Bowling Green is the largest city in the area.”
Warren County’s public works department gets calls about sinkholes weekly, according to public works Director Mac Yowell. Within the past week, at least four sinkhole collapses were reported in the county besides the one at the National Corvette Museum, including collapses on Cave Mill Road and the Lovers Lane Soccer Complex.
Collapses large enough to swallow eight Corvettes certainly don’t happen every day. Yowell called the collapse at the museum “one of the granddaddies of them all.” The only other collapse in Bowling Green he remembers being as significant occurred when a large section of Dishman Lane gave way in 2002.
Emmett Wood, who was city public works director during the Dishman Lane sinkhole collapse, believes another sizable collapse in town is virtually guaranteed, but it’s impossible to predict.
“I wouldn’t be surprised if one happened tomorrow and then didn’t happen again for 10 years,” Wood said.
Kuehn defines a sinkhole as a depression on the surface of the ground that gathers water and drains it into the subsurface. Sinkholes gradually erode as underground water trickles through, removing soil from the rock. When the soil gets too thin, the sinkhole collapses.
“It couldn’t support the weight on top,” Kuehn said of sinkholes in general.
Unlike other catastrophes caused by nature, such as tornadoes and hurricanes, scientists have no way to predict when sinkholes might collapse.
“It would be a great thing, but it’s really hard to know,” said Jason Polk, professor of geology and geography at WKU . “We just can’t see underground. We don’t have any X-ray vision.”
Sinkhole collapses can occur any time, but they often happen when there’s been a lot of rain, Yowell said. The county doesn’t have many surface water sites like creeks or streams, so rainwater tends to trickle below ground into crevices between rocks.
“The only place for water to go is down,” Yowell said.
Polk and other experts are still working to determine exactly what caused the sinkhole collapse at the museum.
“The important thing right now is to get folks on board and develop a plan to save the Corvettes,” Polk said.
Yowell feels sure water was involved. When rain falls on the yellow Skydome, it migrates down to the building’s foundation.
“Over a period of years, water has gotten under that building,” Yowell said.
Though sinkhole collapses can’t be predicted, there are steps people can take to minimize the risk of collapses. An important part of geologists’ work is educating the public, but it often takes a major incident like the sinkhole collapse at the museum to raise awareness, Kuehn said.
“We need to wake up in Bowling Green,” he said.
Geologists are usually called in after a sinkhole collapse, but they need to start being consulted before new building projects, Kuehn said.
“We have to be more prudent in our planning,” he said.
Planning before building can determine if an area is in danger of a sinkhole collapse, Kuehn said. If developers spend more money up front on investigating soil conditions, they could end up saving money in the long run by avoiding a costly sinkhole collapse.
“It involves getting geologists involved in planning and development of the site,” he said. “The most desirable spot for a business may not really be the most desirable spot for a geologist.”
If experts discover an area is at risk for a sinkhole collapse, engineers can repair it before disaster strikes.
“There are techniques to stabilize sites,” Kuehn said.
Homeowners should also get familiar with the danger signs of a sinkhole collapse, Polk said. Information is available on www.underbgky.org.
“Anywhere you build in Bowling Green, there’s a risk of sinkhole exposure,” he said.