BAYOU CORNE — Crosstex Energy LP of Dallas plans to begin on Tuesday shifting liquid butane from one underground storage cavern to another in the Napoleonville Salt Dome, moving the flammable product 1,000 feet farther away from a large sinkhole in northern Assumption Parish, company officials said.
Jill McMillan, Crosstex spokeswoman, said Friday that although the company believes the liquid butane in the cavern has not been affected by the sinkhole and poses no threat to the public, Crosstex is making the shift to the more distant location to address any community concerns.
“In an abundance of caution, we have decided to make some piping changes and move product from the well closest to the slurry to the well farthest from slurry to further alleviate any concerns from public,” McMillan said.
Crosstex has two caverns at its salt dome facility south of La. 70 South between Bayou Corne and Grand Bayou.
The cavern now holding the 940,000 barrels of liquid butane is 1,500 feet from the sinkhole.
The cavern Crosstex plans to move the butane into is 2,500 feet from the sinkhole, McMillan said.
Labeled “Well #1,” that cavern is filled with brine and empty of hydrocarbons, company officials told state regulators.
The cavern has a capacity of 1.7 million barrels and had held propane early this year, according to filings with the U.S. Securities and Exchange Commission.
The sinkhole emerged from the swamps in the same general area south of La. 70 South, swallowing up earth and trees along the way, and was found Aug. 3 about 200 feet from a plugged and abandoned cavern operated by Texas Brine Co. LLC of Houston.
Authorities quickly imposed an evacuation order covering about 150 residences in the Bayou Corne community.
DNR scientists suspect the Texas Brine cavern may have failed and caused the sinkhole and natural gas releases in the area, sometimes visible as bubbles surfacing in waterways.
The Crosstex and Texas Brine caverns were carved from the Napoleonville Dome, a 1-by-3-mile solid salt deposit steadily used for brine production and the kind of hydrocarbon storage Crosstex employs for its customers.
The large underground salt formation was pushed up vertically from ancient sea beds and, for decades, industry has used the dome for brine production.
The perimeter has also been the focus of intensive oil and gas exploration.
Hollowed from the solid salt formation, caverns left by brine production are often used later for storage of natural gas, butane and other hydrocarbons.
Brine is used for several industrial processes.
The liquid butane has been a source of community concern and focus of some media accounts — which some state regulators say were far overstated — that the sinkhole could damage the cavern or its related infrastructure and result in a large release of butane in gaseous form, possibly leading to a massive explosion.
Louisiana Department of Environmental Quality Secretary Peggy Hatch asked Crosstex last week to provide a more detailed analysis of a possible worst-case scenario involving the cavern.
With that analysis in hand, DEQ and Louisiana Department of Natural Resources officials announced there is little to no risk to the public.
In an Aug. 15 letter to Hatch, a Crosstex official wrote that the liquid product is more than a half-mile underground and is under downward pressures and gravitational and other forces holding the butane inside the cavern.
Due to these pressures, wrote Sean Atkins, Crosstex vice president of compliance, the liquid butane “will not free-flow upward to the surface without a mechanical means for doing so, such as pumping.”
Atkins added later in the letter to Hatch, “Again, there has never been a catastrophic failure of a salt dome storage cavern resulting in an instantaneous release of butanes at the surface.”
Atkins’ letter says the worst-case scenario would be, in fact, a pipe failure releasing 8,400 gallons of butane that could lead to a level of pressure change, at nearly 1,600 feet, that parish officials have said would break windows.
John Boudreaux, director of the Assumption Parish Office of Homeland Security and Emergency Preparedness, said that pressure change could result from an ignition of the butane.
But the caverns are in remote swamplands away from residences.
Despite assurances of safety by Crosstex and state regulators, some residents said they want to see the butane removed from the entire area.
Alicia Heilig said in an interview Friday that there are too many unknowns to take risks with the cavern, noting the widely suspected connection between the sinkhole and the Texas Brine cavern remains an unconfirmed theory.
“They don’t know is my point,” said Heilig, 27, who lives just outside the evacuation zone with her two young children.
John Achee Jr., 35, community activist who has become a fixture at the Bayou Corne command post and operates two Facebook pages that have become forums on the sinkhole, said many residents are concerned about the butane cavern’s proximity to the sinkhole and the possibility of a catastrophic explosion.
But he said in an email Saturday that while many may still think the butane should be removed from the area, Crosstex’s plan to move the butane to a cavern farther from the sinkhole will ease some concerns.
“We applaud Crosstex for taking this precautionary action,” Achee wrote.
In a separate development Saturday afternoon, people at the command post could hear the rhythmic hammering of well casing in the distance.
Crews were driving the casing into the ground in preparation for an observational well that DNR has ordered Texas Brine to drill.
DNR wants Texas Brine to use the well to carry out diagnostic testing for a better understanding of the company’s possibly failed salt cavern.
Sonny Cranch, spokesman for Texas Brine, said crews with Riceland Drilling Co. of Lafayette must to drive about 400 feet of metal casing until it halts at the 300-foot-thick caprock overlying the Napoleonville Dome.
More preparatory work will commence after that stopping point, which is called “refusal,” so drilling can proceed inside the hollow casing.
Cranch said that work on the casing is expected to be finished by midday Sunday. He said the casing went easily in the ground late Friday and did not need to be driven.
Workers were ahead of schedule at that point and did not start driving casing until Saturday morning, Cranch said.