Emergency declared for salt cavern in southwest Louisiana over stability concerns

Gov. John Bel Edwards declared an emergency Wednesday over stability concerns in a southwestern Louisiana salt cavern that has been operated by a chemical company, but said there were no signs of imminent collapse.

Natural gas has been bubbling to the surface and subsidence has occurred at the inactive cavern within the Sulphur Mines Salt Dome in Calcasieu Parish. Edwards said in a statement that the emergency declaration will free funding to determine what if any action the state should take.

It is located in a fairly remote area and no evacuations have been ordered, said Patrick Courreges, spokesman for the state Department of Natural Resources. The cavern has been unable to maintain stable pressure, he said.

Edwards said state scientists and inspectors “are telling us they are seeing significant early warning signs of a potential subsurface problem” in the salt dome.

“I want them to have access to every tool available to best understand what is going on in and around these caverns and map out the best response to ensure protection of our people and the environment,” Edwards said.

The salt dome has been used by petrochemical plants in the area; the cavern’s operator is Westlake US 2 LLC, a subsidiary of Houston-based Westlake Corp. A second nearby cavern, also operated by Westlake, is being monitored as well.

It is not the type of mine requiring workers to descend down a shaft. Water is injected that absorbs salt and emerges as brine, said Courreges.

Salt dome stability issues will bring back memories of the Bayou Corne giant sinkhole incident that occurred northwest of Napoleonville in 2012. The sinkhole’s appearance overnight led operator Texas Brine to eventually agree to buy out dozens of home and camp owners. 

State officials addressed that issue, saying lessons have been learned in the interim and regulations have evolved.

“In this case, we have seen some markers that are similar to what was seen then, but nowhere near as severe,” state Conservation Commissioner Monique Edwards said in a statement. “We also still have direct access to the caverns we are concerned with.”

The commissioner cited the threat of subsidence as key in the declaration. The statement said that gas bubbling and integrity concerns “are indicators of a potential threat to groundwater in the area.”

It noted that her office intended to hire contractors and experts to assist in the response following the emergency declaration.

Pressure anomalies were noted in the area in 2021. The following year, the cavern in question failed a mechanical integrity test.

In response, Westlake began pumping brine into the cavern to maintain minimum pressure. Gas bubbling, oil seepage and subsidence eventually led to the emergency declaration, the statement from Edwards’ office said.

The two caverns were originally drilled as brine-mining wells to supply salt water for petrochemical processes in the mid-1950s, the statement said.

In 1979, the U.S. Department of Energy took them over as part of the Strategic Petroleum Reserve. They were transferred back to a private use in the mid-1990s. Brine mining was reported to have ended for both caverns by 2014.