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What Lies Beneath
Mon March 4, 2013
Kentucky Geological Survey Mapping Sinkholes Across The State
HART CO., Ky - Sinkholes have been back in the news of late. The Kentucky Geological Survey's Mike Lynch has this report on KGS's effort to monitor and map sinkholes across the Commonwealth.
Geologist Jim Currens of the Kentucky Geological Survey was literally poking around a Hart County property in March checking for sinkholes… One had opened up after a few days of heavy rain.
It was only about 4 feet wide and 5 feet long, but Melody Chaney, who lives here with her parents, (Dixie and James Eastin Chaney), says a friend driving a truck through the side yard to pick up rolls of hay discovered the sink hole—the hard way.
Like many others around Kentucky, the Chaneys contacted Currens to evaluate the sinkhole and suggest some solutions… ..Though it scared the driver of the truck that punched through it, Currens says he’s seen MUCH worse cases.
Pets and livestock have also been rescued from sinkholes. The most Currens has seen paid for an engineered solution to a sinkhole was $12,000. (But he’s also seen greater costs resulting from damage to property.)
Currens has been collecting information about Kentucky sinkholes to build a database on their development and distribution.
Limestone rock underlies about half of Kentucky. Sinkholes form when a cave occurs in the limestone with a natural conduit or pipe going up toward the surface. If the soil above the conduit is repeatedly wetted by rain, or by human development activities, such as gutter downspouts, the covering soil erodes from below, forming an underground soil arch. It eventually collapses when the layer of soil gets too thin to support its own weight or something punches through it—like a truck.
A “fix” for a sinkhole can range from simply fencing it off and letting it complete the process of formation, to carefully filling it with different-sized rocks separated from the top layer of soil by a synthetic material called a geotextile. (A geotextile allows water to drain while holding the material filling the sinkhole in place.) But Currens will tell anyone who asks that throwing trash, tree limbs or other debris into sinkholes, or filling them with concrete is NOT the solution.
After carefully documenting the dimensions and location of the Hart County sinkhole, Currens leaves the Chaneys several pages describing their options for resolving the problem.
Currens is collecting information about Kentucky sinkholes and is building a data base so he can better understand how they develop and possibly predict where they might happen.