A panel of experts recently appointed to recommend when Assumption Parish sinkhole evacuees can safely return to their communities will face a “very aggressive” schedule but “huge challenges” in doing their new jobs, the response effort’s technical lead said Friday.
CB&I hydrogeologist Gary Hecox’s warnings framed the task before the 13-member body, which Gov. Bobby Jindal charged with recommending when residents can return home and establishing the benchmarks that indicate when that might be.
About 350 people have been under evacuation orders since Aug. 3, when the sinkhole was found in swamplands between the Bayou Corne and Grand Bayou communities.
The commission includes experts on underground storage from Paris, Albuquerque, N.M., and elsewhere; a longtime LSU petroleum engineer; other geologists; and experts in how gas moves through the earth.
The panel members, whom Louisiana Department of Natural Resources Secretary Stephen Chustz appointed March 22, gathered for the first time Friday at the Dalton J. Woods Auditorium in the LSU Energy, Coast and Environment Building. While some members were present, several were watching via a video link.
Chustz thanked the commissioners for convening so quickly, but reminded them how long sinkhole-area residents have been out of their homes.
“And we want you recognize the sense of urgency that is needed here so that we can let people return safely to their homes, those that wish to return,” Chustz said.
Hecox, who is one of the group’s 13 members, assured his fellow commissioners “that the schedule is going to have to be very aggressive.”
“We don’t have years to study this. These people have been out of their homes, and we have to get on with the program, so that’s kind of a heads up,” said Hecox, who reviewed the history and geology of the situation.
Although Hecox has worked in remediation since 1985, he added later, he has never encountered a situation such as the one involving the sinkhole and the kind of remediation benchmarks the commissioners will have to establish.
“The reason I fully supported the blue ribbon commission with the secretary was we’ve got huge challenges here, and we wanted to bring the best and brightest together to help us answer these questions,” Hecox said.
Scientists think a Texas Brine Co. salt dome cavern failed last year at a depth of more than 5,000 feet in the Napoleonville Dome, an ancient, subterranean salt deposit. That kind of failure, which experts say is unprecedented, led to the sinkhole’s emergence and the release of crude oil and gas from deposits along the edge of the Napoleonville Dome.
Gas has been found in a major industrial water aquifer, known as the Mississippi River Alluvial Aquifer, and in even shallower layers of underlying material such as sands and clays beneath Bayou Corne-area residences.
While the flammable methane that poses an explosive risk in enclosed spaces is being burned off by piping it from its underground sources into the open air and setting it ablaze, scientists also think the gas continues to be fed by oil and gas deposits.
Panel facilitator Perry Franklin said that plans are being developed to have commissioners visit the sinkhole in late April or early May as part of a three-day work session, which will include a public meeting.
Commission members will use the session to discuss what they have learned at that point as they work toward a final report, Franklin said.
The group is expected to produce its final public report “as soon as possible” in the form of recommendations to parish and state leaders and regulators, Franklin said, but no specific deadline was offered.
Among the factors the commission is expected to consider in its analysis are the levels of gas under the community, the current and future stability of the Napoleonville Dome’s western flank, and management of the sinkhole and possible void spaces underneath it, according to a news release about the meeting.
Hecox noted the difficulty, in particular, posed by setting a benchmark on remediating the gas, which underlies a 2-square-mile area.
“I think one of the biggest challenges to the commissioners is to figure out when this gas is remediated enough for people to go back in their homes,” Hecox said.
Martin “Marty” Triche, Assumption Parish Police Jury president, urged the commissioners to be honest because parish officials, who called for the evacuation eight months ago, have to make decisions about public safety.
“We are relying upon you,” Triche said, “but understand we expect full, honest interpretation of the data, and we want full, honest discussion.”
Franklin said public comments may be submitted to the commission by sending an email to firstname.lastname@example.org.