The Kentucky Transportation Cabinet says a geotechnical study did not find a definite cause for dip that developed along the Audubon Parkway in Henderson County.
Back in April, drivers reported a drop of about a foot along the roadway. A drilling crew was brought in to check the stability of soil under the road.
Historic mine maps show there was a tunnel about 120 feet below the dip, which led engineers to suspect mine subsidence was the likely cause.
The geotech drilling team located the tunnel but it showed no signs of subsidence that might have contributed to the sag.
Soil and rock samples also indicated an old stream bed about 60 feet below the surface and turned up a number of natural gas pockets, but did not provide any clear cause of the dip.
Engineers plan to run a camera through nearby drainage structures to determine if leaks could be eroding soil under the road. They expect that work to be completed in the next two to four weeks.
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