Nearly four years after the Bayou Corne sinkhole appeared, Assumption Parish emergency officials on Wednesday eliminated all mandatory evacuation orders around the swampland hole but have not given a full all-clear for the small part of the largely vacated community where people still live.
The move is the latest, most significant dialing back of parish evacuation orders around the 34-acre lake-like hole and comes more than five months after parish officials last reduced evacuation parameters.
Officials have said for a few years that the risk from catastrophic subsidence around the sinkhole has diminished greatly as the hole is settling, but flammable methane gas released when the hole formed still posed a risk to homes.
Parish officials, who had kept their evacuation order in place due to that risk, said in a statement Wednesday that “the preponderance of evidence” led to the latest change.
“The area has been deemed no longer at risk due to the sinkhole and gas associated with its creation,” parish officials said.
But the part of the Bayou Corne community with a few camps and homes occupied by about a dozen families still remains under a voluntary parish evacuation order until further notice. Those areas include the Sportsman’s Drive neighborhood south of La. 70 and part of Crawfish Stew Street north of the highway.
These homes were where some of the heaviest underground gas accumulations had been found.
In the first years after the sinkhole appeared, the rest of Bayou Corne’s residents were bought out by Texas Brine Co. through private settlements and as part of a class-action lawsuit. Those bought-out areas include now-vacant homes north of La. 70 that were made free of any evacuation orders Wednesday.
The parish changes came one day after Louisiana Commissioner of Conservation Richard Ieyoub agreed to lessen the frequency with which Texas Brine contractors must check and report on many of the monitoring devices the company had been required to lay out since the sinkhole emerged in August 2012.
John Boudreaux, director of Assumption Parish Office of Homeland Security and Emergency Preparedness, said that in lifting the evacuation orders, the parish was following the Office of Conservation’s lead.
“As we said in the beginning, we’re going to rely on the experts,” he said.
While the area still has about 15 to 20 sites of bubbling gas — one of the precursors of the sinkhole — Boudreaux said the amount of gas that Texas Brine still removes through special wells has been greatly reduced.
State scientists have attributed the sinkhole’s formation and the appearance of flammable methane gas to the failure of an underground salt dome cavern operated by Texas Brine.
The state office made the monitoring changes Tuesday a few months after Texas Brine requested it be allowed to conduct no further action around the sinkhole. Ieyoub, in his letter, though, said the agency would not go that far and gave requirements before he would consider no further action for the still-inhabited parts of Bayou Corne.
Ieyoub wrote that Texas Brine must submit written statements from a licensed geoscientist or engineer saying, in his or her professional opinion, the remaining gas still under the inhabited areas “does not pose a serious threat to life or safety based upon the data and information available.”
Ieyoub also would not agree to relieve Texas Brine of some of the seismic monitoring requirements for the sinkhole and surrounding salt dome caverns, as he noted “seismic events” continue in those areas.
Texas Brine officials said in a statement that lifting the parish orders was “another positive step for the community of Bayou Corne” but added that the company has submitted hundreds of thousands of “data points” to the state and the change should have gone further.
“Given what we’ve learned, Texas Brine believes the data supports the lifting of all remaining evacuation orders,” the company said.
In another sign that the risk is lessening from the methane gas bubbling up in the Bayou Cor…
In January, parish officials lifted a voluntary evacuation order in largely unpopulated Grand Bayou, east of the sinkhole and the Bayou Corne community.
For years, Texas Brine had been pumping fresh water into the Napoleonville salt dome, a giant underground salt deposit, to dissolve and mine the salt for industrial customers. In the process, a large, elongated cavity was carved from inside the remaining salt.
But that cavern was also mined near the end of the salt deposit and left the cavern with relatively thin supporting walls of salt.
One of those walls of salt broke open and allowed surrounding earth and rock to flow inside the cavern. That eventually led to the appearance of the sinkhole in early August 2012 after months of then-unexplained tremors and gas bubbling in the swamps and waterways of Bayou Corne. The failure also cracked open natural gas deposits.
In litigation over the failure, Texas Brine has blamed past oil drilling near the company’s cavern for the sinkhole’s formation.