BAYOU CORNE — The potential failure of an inactive and plugged Texas Brine Co. LLC mining cavern in a massive salt dome is likely the cause of “a slurry area” that emerged overnight Thursday in northern Assumption Parish, state emergency preparedness and state Department of Natural Resources officials said Friday.
In response, Gov. Bobby Jindal declared an emergency Friday and the state Office of Conservation issued an order directing Texas Brine of Houston to evaluate the structural integrity of the salt cavern and begin to remediate any problems within 24 hours, state emergency preparedness officials said in a news release.
DNR officials, in consultation with scientists, determined the potential failure may have caused the slurry area, or sinkhole, which swallowed full-grown trees and denuded a formerly forested patch of cypress swamp, emergency preparedness officials said.
The potentially failed cavern may also be the source of natural gas that has bubbled up on nearby bayous and from an abandoned water well, emergency preparedness officials said.
For more than two months, federal, state and parish officials had been unable to pin down the source of the natural gas releases — despite a battery of tests on the oil, gas and brine production infrastructure in the area — or the cause of earthquakes.
“Final determination of a positive link between the Texas Brine Co. cavern and either the natural gas bubbling or the slurry area has not been made,” the news release from the Governor’s Office of Homeland Security and Emergency Preparedness says.
But fearing the slurry area could widen farther and threaten nearby wells storing flammable hydrocarbons, Assumption Parish officials declared an emergency and called for an evacuation of residents living near the nearly 1-acre muddy site.
The evacuation was effective about 6 p.m. Friday, though sheriff’s deputies would not be forcing people to leave their homes and La. 70 South would remain open, parish officials said Friday.
Assumption Parish Police Jury President Martin “Marty” Triche said during a Friday evening community meeting that the evacuation area extends from a point just west of Bayou Corne and La. 70 eastward to the point where La. 69 intersects La. 70.
The American Red Cross plans to open a shelter at 8 a.m. Saturday at Belle Rose Middle School, Red Cross spokeswoman Nancy Malone said in a news release.
All pipelines in the area also have been ordered shut, Triche said.
The slurry area is 600 feet from nearby pipelines and, from the air, a Texas Brine salt cavern wellhead could be seen nearby.
The formation of the slurry area was accompanied early Friday by a diesel-like odor that some residents said burned their eyes and noses but dissipated by midmorning.
The odor prompted parish officials to call in a variety of state agencies. The diesel odor could be smelled later in the afternoon in helicopter overflights of the slurry area, parish officials said.
Jindal issued the emergency declaration because of the risk of subsidence and subsurface instability threatening lives and property.
The slurry area is 2,500 feet from the nearest residence in Bayou Corne and a half-mile south of La. 70 on land owned by Texas Brine, sitting on the western flank of the Napoleonville Salt Dome.
Texas Brine has mined the salt dome since 1973 for brine used by industry, using water to wash out salt deep in the dome and selling the resulting brine mix, company and DNR officials have said.
Texas Brine and other salt dome operators use salt-dome cavities left behind from mining operations to store hydrocarbons such as natural gas for companies that lease the wells, company and DNR officials have said.
Texas Brine ceased operating the cavern in 2011 and plugged and abandoned the well used to access it, state officials said.
Bob Gresser, a spokesman for Texas Brine, said employees detected a hydrocarbon odor resembling diesel around 6:30 a.m. in the vicinity of a plugged well tied to a salt cavern.
He said company officials are cooperating with authorities.
Triche gave residents a stark warning of the risks posed by the slurry area as he announced the evacuation. He reported a conference call with DNR officials revealed that the slurry area could quickly enlarge and possibly sheer off nearby wellheads, releasing harmful gases.
Triche said DNR officials reported that the 200-by-200-foot area — which may have been expanding somewhat Friday — could grow to dimensions of 1,000 to 2,000 feet very quickly.
“At this time, we’re just telling you they advised us there is a significant risk,” Triche said.
Linda Cavalier, 52, of Bayou Corne, said the foul odor irritated her eyes and nose on her way to work 7 a.m. Friday.
After listening to Triche and other parish officials Friday evening, Linda Cavalier said she and her husband, Wallace, 57, planned to evacuate.
But Wallace Cavalier said they just moved to the Bayou Corne area three months ago and do not have the money to move away.
“So we don’t know where we’re going. We don’t have the money to go,” he said. “I have no idea, but we got to get out of here.”