Sinkholes present an unregulated risk in Bowling Green

Geologic map of Kentucky depicting areas with high karst potential (shown in light red).  Warren County is indicated by a yellow box outlined in red.

By Brittiny Moore

Just over two years ago, on Feb. 12, 2014, the floor of the Corvette Museum Skydome collapsed into an underlying cave system, creating a 30-foot deep sinkhole and swallowing eight corvettes.  

Tens of thousands of dollars’ worth of damage was incurred to the museum and the corvettes after the floor plummeted into a cave the museum said was previously unknown.  While the sinkhole is now filled in, with an exhibit documenting the event resting on top of the previous void, parts of the museum still create overburden for other extents of the cave.

“It’s a safe zone now,” museum staffer Linda Russell said.  “That’s one place that’s never going to cave in again, ever.”

However, experts say the museum is still at risk for future collapses and it is cases such as the Corvette Museum that provide evidence for a need of regulations or guidelines for building in karst environments. Currently, there are no building regulations relating to sinkholes in Bowling Green or Warren County.   

“For what they remediated, it might be stable, but it’s an island in an ocean of problems,” said Dr. Patricia Kambesis, WKU instructor of geography and GIS, director for the Hoffman Environmental Research Institute and council member of the Cave Research Foundation.

The Kentucky landscape stretches 25,852,800 acres, with 9,343,293 of those acres making up a karst terrain, according to the Kentucky Geological Survey.  With 67 percent of Kentucky consisting of karst, having bedrock such as limestone that is dissolved out by water, 4,000 to 6,000 sinkholes are experienced annually, causing large amounts of structural and property damage.

Kambesis said with the amount of research done on Warren County karst, she is surprised that no regulations for building on karst exist.  She said an absence of regulations stems from a lack of education and understanding.    

“Unless you really understand it, then you don’t see any need,” Kambesis said.  “Sometimes the only way people will regulate things is when it starts to effect human life, if it causes fatalities.

“Why be reactive when you can be proactive?”

BMoore warrenco_karst

Some Kentucky cities have recognized a need for planning when building on karst.  Lexington’s city planning regulations have no sinkhole inclusive ordinances, but certain ordinances take sinkholes into account for general environmental protection.  

“Quantifying the benefits of environmental protection can be difficult, but sinkholes play a role in our overall hydrology,” said Brad Stone with the Lexington Public Works department. “With our karst topography surface waters become groundwater, and vice versa.

“Groundwater contamination can have a profound impact on that city’s drinking water,” he said.

Other states, such as Florida, offer sinkhole insurance, but most guidelines across the country are limited to the protection for water quality, said Dr. Jason Polk, WKU associate professor of geoscience and the director of the Center for HumanGeoEnvironmental Studies and the HydroAnalytical Lab.  However, both the Kentucky Geological Survey and the National Cave and Karst Research Institute offer guidelines for government agencies to work from or adopt. “We know a lot more now than when a lot of those policies were put in place,” Polk said.  “We are in dire need to update some of those things.”

Many of the sinkholes in southcentral Kentucky are subsidence sinkholes that create the rolling hill landscape appearance and don’t pose a great threat, Polk said.  However, more dramatic, collapse sinkholes also take place in Warren County.

“When they do happen they’re really, really intense because they are immediate,” Polk said.  “They can be quite catastrophic and destroy property and buildings, threaten farm life and human life.”

Such is the case for the 2002 sinkhole collapse of Dishman Lane in Bowling Green, a collapse that could have been avoided, according to Kambesis.

Kambesis said Dr. Nicholas Crawford, an adjunct professor for WKU, had mapped the proposed road prior to construction and showed the road to intersect a large cave passage – a map that developers claim to have never received.  After reviewing the map, Crawford had recommended that developers put a curve in the road in order to avoid building directly over a sinkhole – one that was already starting to form, according to Kambesis.   

“There are two sinkholes in the area, not very far from each other, and basically they just avoided one and went right over the other one to keep the road straight,” Kambesis said.  “When you keep the road straight it’s not as expensive as if you put a curve in it.”

According to Crawford’s report, he gave his recommendation to developers, including the map, which they did not follow.  According to documents, Crawford aided in the remediation of the sinkhole, a fix that cost $1 million.  

Josh Moore, the public information officer for the Bowling Green Public Works department, said while there are concerns for sinkholes, they do not pose a problem in the area.  

Warren County has no regulations for building on karst and instead take precautions for large commercial businesses, Moore said.  

“There are no regulations primarily because 90 percent of Warren County is built on karst,” Moore said.  “There is nothing special that you do in a karst area.”

Moore said all developers use known sinkholes to ensure they build around them and often times use geotechnical equipment to survey the subsurface, making regulations or guidelines unnecessary.  

“I don’t think it’s necessary if you use best management practices,” Moore said.

These practices are in question in the case of an apartment complex currently in construction over a cave system off of 31-W.  Developers have recently broken into the cave roof, creating a sinkhole.

“The cave is pretty close to the surface there,” Polk said.  “I provided some maps and information and went out to the site a few times just to generally provide information or be as much of a resource as possible as they have encountered some issues.”

Polk said after digging into the cave roof, construction to attempt to prevent further collapse had to be done.

“Even though it isn’t a large cave system, it doesn’t take much for there to be a problem with construction, foundations and buildings.” Polk said.  “There are a lot of implications because Bypass cave is basically an area where storm water is directed for a pretty good size area.

“Anything that changes that flow of water, could have some impact and cause things like flooding issues or contamination.”

Polk said any developer who works in Kentucky is aware of the risk, and in a dream world they would know everything about karst, knowledge that could help prevent poor planning for construction sites.  Even after construction, assessing the risk for sinkholes can lead to better protection.

“If people understood it or were willing to voluntarily do these things beforehand, like geophysical investigations, before they build then you don’t need any regulations, it would be just something that you do,” Polk said.  “If you build awareness and education, and at some point there is regulations – a need to sort of codify what they can and can’t do – it won’t be as hard for them to swallow if they’re required to take these certain steps and measures.”  

Kambesis said with economic concerns, the geology of a region is often ignored.  Calling money “the root of all evil,” she said as far as she can tell, the city has yet to learn from previous mistakes.  

“The fact is that there is ongoing development in Bowling Green and it pretty much ignores the fact that it’s over karst,” Kambesis said.  “The most convincing thing, of anything, in the world is money.”

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