Sinkhole Growing In McAlester

They're on shaky ground in McAlester.  Quite literally.  The News On 6's Steve Berg reports a large sinkhole has opened up in an inconvenient spot, between a busy highway, and the town's expo center.

They know what's causing it.  The county has thousands of old coal mines.  There's just not a lot they can do about it.  At first glance, the sinkhole looks like a nice, country pond.  The problem is it wasn't there three days ago.

"It's sunk approximately a foot to a foot-and-a-half today, which is more than what it was three days ago," said Henry Roye with the Oklahoma Conservation Commission.

Then you notice the sign is leaning.  And, the road is developing some ominous-looking cracks.  If you had X-ray vision, Henry Roye says you would see a honeycomb pattern of old coal mines below the surface.

Where the coal was taken out there are empty voids.  The miners left walls of coal in place between the voids to support the earth above.  But eventually, time takes over.

"These old mines were actually mined out in the early 1900's," said Henry Roye.  "We're talking about over a hundred years, so you can just hold a void up for so many years until it'll cave in."

The big concern now is that the sinkhole has spread to within a few feet of Highway 270, and they say if it gets beneath the level of the roadway, they'll have no choice but to shut it down.

"So we'll be watching that and monitoring that real close, couple times a day," said Henry Roye.

And, seeing it so close to their multi-million dollar Expo Center gives them a sinking feeling.

"Whooo, we don't want to talk about that.  It would damage it severely," said Henry Roye.

To make things more complicated, they don't know exactly where this particular coal mine is.

"We couldn't find a map.  We've got a guy in Oklahoma City that does that, and we couldn't find a map," said Henry Roye.

The only way to find out the extent of the sinkhole is to start digging.  The ground could sink as much as 7 feet.