Subsidence in the median of I-70, shown here, occurred while the mine was being backfilled with grout (a mix of cement, fly ash, and water) to protect the roadway. In the background are two drill rigs used to drill holes down to the mine void to place the grout.
On March 4, 1995, a twelve-foot sinkhole developed in the eastbound lanes of Interstate 70 in Guernsey County, Ohio. Three cars and one truck struck the sinkhole, but no serious injuries resulted. The Ohio Department of Transportation (ODOT) immediately closed the interstate. ODOT officials eventually determined that the sinkhole resulted from an abandoned mine that existed under Interstate 70. It took ODOT approximately four months to strengthen the mine under the interstate and to repair the sinkhole.
As a result of this sinkhole, ODOT created the Abandoned Underground Mine Inventory and Risk Assessment process. Under this process, ODOT employees are to try and identify mines under roadways and to make any necessary repairs to the mines and roadways before other sinkholes develop. Thanks to this process, ODOT identified and repaired the Interstate 70 and Interstate 77 interchange in eastern Ohio in late 1995 before a sinkhole developed.