The slow lane of Interstate 26 eastbound near Ridgeville will reopen Saturday morning if temporary sinkhole repairs are completed, officials said Friday.
If the work is not finished, only one eastbound lane will be open at Mile Marker 192.5. A westbound lane shut for the repairs reopened Friday after a crane used for the work was moved across the interstate.
The crane is being used to place sheet piling to block water flow to the sinkhole, said James Law, spokesman for the state Department of Transportation.
On Friday, a steel plate was placed over the sinkhole in the eastbound fast lane. The mouth of the sinkhole is 6-by-10 feet. The depth of the hole and the extent of the problem will not be known for sure until water is pumped out of it, he said.
Flowing water washed out soil beneath a 10-by-10-foot box-shaped drainage culvert 18 feet below the road. The erosion is believed to have contributed to formation of the sinkhole, Law said.
Traffic backed up for miles in both directions on Friday until the crane was moved from the westbound slow lane to the eastbound slow lane. Once that was done, both westbound lanes were reported to be flowing smoothly.
The sinkhole was first discovered July 5. Repairs have been underway since that time.
Michael Meadows, an associate professor at the University of South Carolina College of Engineering and Computing, said what caused the I-26 sinkhole depends on local conditions. Generally, something happens to underlying soil and geology to create the problem, he said.
Water may pool underground and flow laterally, washing away dirt underneath a road. A leaky box culvert may have washed away supporting soils. Or both things may have happened.
“This is something that may have been in progress for a number of years,” Meadows said.
Interstate sinkholes have been reported in other parts of the country. In May, a sinkhole formed on Vermont’s Interstate 89 in the northbound passing lane. Part of Interstate 44 in Oklahoma was shut down in 2010 because of a sinkhole. The same year, a large sinkhole formed on Interstate 24 in Tennessee.