Commission to study return for Bayou Corne residents

Advocate staff photo by ARTHUR D. LAUCK -- Crews with Faucheux Drilling drive pipe 40 feet down at one of the 2,200 sites where 2.2 pounds of the explosive pentolite will be placed to conduct a seismic shoot of the failed Texas Brine salt cavern. The workers, from left, are Miguel Garcia, Shane Landry and Derrick Ross.
Advocate staff photo by ARTHUR D. LAUCK -- Crews with Faucheux Drilling drive pipe 40 feet down at one of the 2,200 sites where 2.2 pounds of the explosive pentolite will be placed to conduct a seismic shoot of the failed Texas Brine salt cavern. The workers, from left, are Miguel Garcia, Shane Landry and Derrick Ross.

Louisiana Department of Natural Resources Secretary Stephen Chustz will appoint the members of a “blue ribbon commission” by the end of this week to determine when Bayou Corne residents can safely return home, an agency spokesman said.

Experts are being sought from federal and state government, academic institutions and consulting firms to fill an estimated 12 to 17 spots, said Patrick Courreges, DNR spokesman.

“The commission will make recommendations on what the safety benchmarks should be and on when they have been sufficiently met,” Courreges said in an email.

The appointments will cap a busy week of meetings, buyout talks, a governor’s visit to Bayou Corne and key seismic testing related to the failure of the Texas Brine Co. LLC cavern believed to have caused a 9-acre sinkhole in the area, state, parish and Texas Brine officials said.

Scientists think the Texas Brine cavern was mined too closely to the western face of the Napoleonville Dome, sometimes called “the edge of salt,” and had a sidewall failure more than 5,000 feet underground.

This failure of the cavern’s supporting salt structure allowed millions of cubic feet of rock outside the dome to flood into the cavern.

That set in motion the creation of the sinkhole, scientists suspect.

The scrambled subsurface also unleashed oil and gas from natural traps alongside the salt dome to the surface and a shallow aquifer, scientists have said.

Scientists think the 140-foot-deep sinkhole is reaching its final, stable state. Tremors indicating underground fluid and rock movement increased in frequency last week, halting work for a day.

On Sunday morning, another belch of oily hydrocarbons and debris surfaced, parish officials reported in a blog post.

The methane gas is in the aquifer and could leak undetected, raising an explosive risk in enclosed spaces, such as closets, in homes in the Bayou Corne and Grand Bayou communities.

Under Office of Conservation orders, Texas Brine is installing vent wells to burn off the gas and in-home monitors.

Sonny Cranch, Texas Brine spokesman, said the company had 29 vent wells installed and as many as 24 burning off gas by Friday.

He and parish officials said that over the weekend, the wells were expected to have removed a total of 10 million cubic feet since the first well began burning gas in November.

Fifty to 100 million cubic feet of methane is believed underground.

Jindal announced plans for the blue ribbon commission last week after meeting with Assumption Parish leaders and legislators.

Chustz will consult with Louisiana Office of Conservation Commissioner James Welsh, the Governor’s Office of Homeland Security and Emergency Preparedness Director Kevin Davis and others to select the members, Courreges said.

He said the commission will look at three key areas: shallow gas in the aquifer, the current and future stability of the western side of Napoleonville Dome, and management and containment of the sinkhole.

Experts also will weigh the potential for void spaces that could lead to instability under the sinkhole.

Courreges said the commission will have public meetings but have private gatherings to work through data.

As part of a court settlement with Texas Brine in mid-January, the Office of Conservation ordered Texas Brine to conduct the 3-D seismic work now hitting a key phase.

The seismic imaging is expected to allow scientists to see the western face of the Napoleonville Dome, a theorized collapse zone outside that face where underground voids are feared and the source of oil and gas is believed to be escaping from underground formations.

Seismic waves created by the vibroseis truck and, in more remote areas, by buried charges, will help make the underground images.

Boudreaux said heavy operations that could cause vibrations and interfere with the seismic work will be halted through March 25.

Cranch said the vibroseis truck is expected to continue Monday. Underground charges will begin being fired Tuesday.

The Office of Conservation has ordered that Texas Brine turn over the 3-D data by April 21.

Editor’s note: This story was modified on March 18, 2013, to reflect that the deadline to submit data to the state Office of Conservation from the state’s 34 salt dome operators that could show if other caverns in Louisiana are in similar positions inside salt domes as the Texas Brine cavern before it failed was Monday, not this Wednesday. The Advocate regrets the error.