BAYOU CORNE, La. (AP) — Drillers punched into a failed salt cavern and then removed the equipment to make way for tests to learn whether the cavern's failure caused a huge sinkhole in Assumption Parish.
Although gauges first showed no pressure from gas or brine in the cavern, some gas was found and flared off, and an oily fluid began coming up through the drill hole Sunday, said Sonny Cranch, spokesman for Texas Brine Co. LLC.
The company and the Louisiana Department of Environmental Quality were analyzing samples of both, he said.
Cranch said crews expected to begin sonar and other tests Sunday night, but it could be one to three days before results were available.
The Louisiana Department of Natural Resources ordered Texas Brine to drill the well after scientists said the sinkhole might have been caused by escaped brine from the cavern hollowed out in the Napoleonville Dome — an underground mountain of salt.
Cranch said equipment lowered into the cavern would include sonar to show the cavern's shape and size, and equipment to check its content.
He said gas had been expected. "In this particular brine cavern, throughout its production life, every two weeks it would build up a pressure of about 900 pounds per square inch," he said.
"This was just gas that would escape form the sodium chloride as it was being mined," Cranch said. "That would be vented every two weeks or so. Twenty minutes — boom — it would be gone."
About 150 nearby homes were evacuated after the sinkhole appeared Aug. 3 on Texas Brine property between the Bayou Corne and Grand Bayou communities south of Louisiana Highway 70 South. Natural gas had been bubbling up in nearby waterways and people had been feeling occasional earth tremors for about two months.
Aerial photographs taken Saturday indicate that the irregular sinkhole ranges from 409 feet to 486 feet across, and is about 100 feet wider than it was a month ago, said John Boudreaux, director of the Assumption Parish Office of Homeland Security and Emergency Preparedness, told The Advocate (http://bit.ly/Pz5KLH).
"In general, there's been about 50-foot growth on about the east and the west," he said.