State transportation officials regularly monitor drainage pipes to guard against the formation of sinkholes, such as one that opened last month off highly traveled Interstate 85 near South Carolina.
But the Georgia Department of Transportation only can do so much.
“We can only inspect pipes visually. There is one camera statewide that can be sent into a drainage system so we can see what is happening in the pipes,” said Teri Pope, spokeswoman in the DOT’s Gainesville-based District 1, earlier this week.
“That camera is in high demand and is quite expensive to operate.”
DOT crews routinely check drainage structures for clogs, as well as examine surrounding property
and shoulders.
“We also look for dips in the roadway itself. That can be a clue to drainage problems,” Pope said.
District 1 alone has some 2,300 miles of interstates and state routes, translating to “thousands of miles of drainage pipes,” she added.
The good news is sinkholes don’t crop up often.
In the 21-county District 1, which includes Hall, the hole that opened off the southbound lanes about one mile from the border was the third such cavity in the past 11 years, Pope said.
A DOT crew found the most recent one Feb. 16 during a routine maintenance inspection of guardrail, about one mile north of Exit 177 in Hart County.
The DOT closed the outside shoulder and outside southbound lane of the interstate at milepost 178, then went on to spend about $587,000 to repair the sinkhole that measured 20 feet long by 30 feet wide by 10 feet deep.
Repairs were finished Feb. 22, but crews will continue to do shoulder work daily through Friday, Pope said.
The other two sinkholes — one on Ga. 120 in Duluth and Ga. 140 in Norcross — were discovered by local law enforcement.
All three were caused by “water finding a way out after a drainage pipe is collapsed or broken,” a problem heightened by surplus rainfalls in the past year, Pope said.
Another issue is age.
“In the case of this (most recent) sinkhole, the drainage system was built as part of the interstate about 40 years ago,” Pope said.
“The system is coming close to the end of its life expectancy. (The DOT) used mostly corrugated metal pipes for drainage then and those are the kind of pipes that we now see failing.”