(CNN) -- Officials in Pennsylvania may give the go-ahead Friday to exhume graves as a large sinkhole encroaches on a historic Allentown cemetery.
A court order has been secured so that Lehigh County Coroner Scott Grim can give the order if he deems such action necessary.
"It's a very sensitive issue. You are dealing with a cemetery," Grim said. "You are laid to rest and now it is being disturbed."
The sinkhole measures about 50 feet long and 30 feet wide, according to Allentown Fire Chief Robert C. Scheirer.
"They are pumping concrete into it right now," he said.
About 60 graves in Union and West End Cemetery are threatened, Grim said. Most graves in the cemetery date from the late 1800s to early 1900s.
The coroner has said that authorities could excavate graves if they detect shifts or collapses in the nearby soil.
A dozen homes on nearby 10th Street were vacated and 25 people evacuated because of the sinkhole, said Scheirer. A water main break probably caused the sinkhole.
"Three of homes have major shifting issues that you can physically see shifting," Assistant Fire Chief Lee Laubach told CNN affiliate WFMZ. "You can see the doors don't open, the cracks in the walls and in foundations."
Dwayne Glover, an evacuated resident, told the station that before evacuating his home, his foot had inadvertently gone through a concrete floor as he walked toward his washing machine.
Several headstones have tilted, and there were some breaks in the cemetery ground.
"We can see depressions where the ground has fallen as much as two feet," said Everette Carr, president of the Union and West End Cemetery Association, which maintains the 157-year old nonprofit burial ground.
There also could be unmarked graves, said Carr.
The cemetery holds about 20,000 graves, including those of 714 Civil War veterans. Among them is a Medal of Honor winner, Ignatz Gresser.
Carr did not know if any of the threatened graves included soldiers. Grim, whose office photographed the 60 markers, said he saw some belonging to soldiers.
Cemetery volunteers previously did a survey, but there are no detailed historical records of the dead beyond those whose graves have headstones. And some of those are difficult to read, Carr said.
"It's a very volatile situation," Carr said. "The ground is unstable. There is no question it is moving."