BAYOU CORNE, La. (AP) - Authorities say state and parish agencies are testing to see whether newly discovered gas bubbles northeast of the Bayou Corne-area sinkhole are tied to the swampland hole.
The Advocate reports (http://bit.ly/1fqFs7T) the state Office of Conservation and contractor CB&I; have taken samples of the gas bubbles to determine their source, though officials acknowledge the bubbles likely are connected to the sinkhole.
The new bubble site in Grand Bayou is about one-third of a mile north of La. 70 and La. 69, parish officials said. Most bubble sites tied to the sinkhole have been discovered in the Bayou Corne and Grand Bayou waterways and elsewhere farther to the west and south.
Previous sinkhole-related testing below Grand Bayou shows a 1- to 2-foot-thick gas layer exists in shallow sands under the new bubble site, said Patrick Courreges, spokesman for the state Department of Natural Resources.
Scientists believe when the wall of an underground salt dome cavern collapsed in 2012, the failure shattered surrounding strata. This created the sinkhole but also unleashed natural deposits of oil and gas that percolated up.
Texas Brine Co. officials say the oil leaking in the sinkhole stopped last year, but methane gas bubbles have proliferated in bayous and even on dry land where water is standing.
Parish officials said 100 such sites had been found prior to the latest discovery.
Scientists think the gas presents an explosion risk for residents and the area remains under an evacuation order 18 months after the sinkhole appeared.
Texas Brine, which managed and developed the failed cavern, has burned off 25 million cubic feet of gas, parish officials said, and may have another 10 million cubic feet that is recoverable.
Many residents have taken buyouts from Texas Brine. Others filed suit.
Recent pipeline work under Grand Bayou could have provided a path for the gas to escape, according to John Boudreaux, director of the Assumption Parish Office of Homeland Security and Emergency Preparedness.
Acadian Gas Pipeline System was boring under the bayou to reroute a pipeline damaged by the sinkhole.
Boudreaux said that three weeks ago, survey crews marked the area and did not see bubbles.
Acadian Gas tested two other pipelines in the same Grand Bayou crossing and found no leaks, state officials said.
Information from: The Advocate, http://theadvocate.com