The Assumption Parish sinkhole, which regulators say was caused by an “unprecedented” failure of a man-made cavern deep underground, has exposed gaps in state rules governing how industry uses salt domes.
Scientists suspect a Texas Brine Co. cavern collapsed because it was too close to the outer face of the Napoleonville Dome, creating the sinkhole and causing natural gas to permeate aquifers and bubble up in bayous. About 350 people have been under evacuation orders for more than seven months.
The state Office of Conservation and state legislators are considering new regulations to prevent a similar disaster.
“Nothing is more important to me than those people who have been put in the middle of a catastrophe they had nothing to do with except to live there,” said Rep. Karen St. Germain, a Pierre Part Democrat who is helping shape bills on salt dome regulation for the upcoming legislative session.
Louisiana has at least 204 onshore and offshore salt domes grouped in two bands along the northern and southern ends of the state. Twenty-six domes have a combined 350 active and closed caverns in them, state records show. Caverns are used for producing brine for industrial use and for storing oil, natural gas and chemicals.
A review of the regulatory record, academic literature and lawsuits shows that existing state regulations are tougher in some ways and weaker in other aspects than rules in neighboring Texas and Mississippi.
According to the U.S. Environmental Protection Agency, the rules enforced by Louisiana’s Office of Conservation meet or exceed federal regulations. Even so, Louisiana’s regulatory eyes also only see so far.
As is also the case in Texas and Mississippi, the Louisiana Office of Conservation lacks its own research arm and relies heavily on industry and academia for research into salt dome geology and on safely locating and operating caverns.
Also like its peers in other states, the office does not randomly do safety retests on caverns to spot check the testing done by private contractors hired by cavern operators. The agency does review testing plans and the subsequent testing reports, state officials said.
Robert Bea, a University of California at Berkeley professor emeritus of engineering and risk management, said regulators in the United States have historically done a poor job of managing risk and deducing potentially broad troubles from the interpretative and limited data often available in the regulation of companies. He said U.S. regulators often fail to establish a “happy family” relationship between the regulator and the regulated, or parent and child.
“Here in the United States, we have not done such a good job of focusing on responsible, accountable ownership,” Bea said.
John Voigt, executive director of the Solution Mining Research Institute in Clarks Summit, Pa., an industry research group, said at some level, the state must rely on industry and salt dome operators to appropriately assess risk because industry will always be pushing ahead of regulators for the most economical and safest way of producing salt.
“It is impossible for them to pass a law that is going to cover all the future little changes or potential improvements or problems,” said Voigt, who sits on a state panel that will assess long-term risks posed by the sinkhole.
Changes proposed by the Office of Conservation and legislators include a rule that Texas and Mississippi impose but Louisiana lacks — an official limit for how close brine caverns can be to the edge of salt domes.
The proposed 300-foot buffer zone would match the rule in Mississippi and exceed the limit in Texas by 100 feet.
Other proposed rules for Louisiana would be stricter than those in other states.
The office would require at least five years of monitoring before caverns are closed and at least 10 years afterward, bringing the state closer to the 2004 recommendation of a French panel of international experts who said at least 20 years of monitoring should be done before caverns are closed for good.
The Texas Brine cavern that eventually failed was permanently closed five months after company officials reported problems to the Office of Conservation.
No monitoring followed, though company tests that led to the closure raised questions about how close the cavern was the salt dome’s outer face.
Office of Conservation officials have said that, at the time, experts thought the cavern’s proximity to the dome’s edge posed at worst the risk of a harmless brine leak, not the catastrophic failure that occurred.
Patrick Courreges, spokesman for the Louisiana Department of Natural Resources, which includes the Office of Conservation, said that under current law, state regulators would have to specifically order long-term monitoring of a permanently closed cavern.
He said such an order “would be highly susceptible to challenge without some foundation in scientific or other factual basis.”
Another change proposed by the Office of Conservation would require that no later than a week after a cavern has been taken out of service for 30 days, operators would have to report why it was closed.
Currently, companies must give the Office of Conservation a one-page form when closing caverns permanently. The form calls for technical details about the closure process, known as plugging and abandoning a cavern.
But that “plug and abandon” report has no line asking why a cavern is being closed or what might be left inside it.
Mississippi, Texas and Kansas do not require declaration of the reason for closure, though Kansas officials say they make it their business to know.
Salt dome caverns can cost tens of millions of dollars to create and last for decades, either as brine mines or storage caverns. Some caverns are closed simply because they are no longer economically viable.
The form for the Texas Brine cavern does not say why it was abandoned. But company officials voluntarily gave the Office of Conservation test results and other information before the cavern failed that they say described why they were closing it.
For six of the 15 other caverns plugged and abandoned in Louisiana since May 1992, no reason was apparent from a review of DNR records. For three of the 15, only hints could be found.
Willie Fontenot, an environmentalist and longtime critic of DNR, said the agency should require better information on something like a cavern closure.
“You have to have detailed records because if somebody else, in the future, may want to do something with that salt dome, they need to know what they might encounter,” Fontenot said.
In August 2002, Martin Underground Storage plugged one of its liquefied petroleum caverns in Bienville Parish. Office of Conservation inspectors monitored the plugging job for a year.
In September 2003, inspector Dale Halverson found butane bubbling from the cement used to seal the cavern’s access well.
“The leakage is flammable,” Halverson wrote in a report.
The Office of Conservation ordered the company to vent off the gas and reseal the well. Courreges said that kind of incident demonstrates the strength of the agency’s oversight.
The Office of Conservation’s Injection and Mining Division has, in the past four years, met or exceeded the vast majority of EPA benchmarks for inspections and witnessing key structural testing, annual reports show.
“I commend your staff in effectively meeting or exceeding … program targets,” William K. Honker, acting director of the EPA Water Quality Protection Division, wrote in a February 2012 letter to the head of the state division.
The EPA letter, which addressed the 2011 fiscal year, was issued three months before the first reports of bubbling gas in Bayou Corne near where the sinkhole formed in August. The EPA report on the state Injection and Mining Division’s 2012 performance is pending.
The Office of Conservation conducts its own safety inspections of salt dome operations every five years.
Operators of hydrocarbon storage caverns must also do their own site inspections twice a year. State inspectors must be informed in advance but do not always observe the inspections, Courreges said.
That part of Louisiana’s inspection regimen is stronger than Texas’ but weaker than what is required by Mississippi and by Kansas, where a gas explosion from an underground salt cavern in 2001 led to a revamp of that state’s regulations.
Louisiana already requires key tests of cavern volume, shape and integrity more often than some states do. Integrity tests are required every five years, plus after upgrades or changes to caverns and wells.
Under its proposed rules, the Office of Conservation would eliminate an alternative to the integrity tests, which allows companies to simply report daily pressure readings instead.
Louisiana and other states do not do their own testing on the integrity of caverns. Regulators claim those third-party tests are done by professionals with their licenses on the line and note that follow-up reports are reviewed.
Sandia National Laboratories in Albuquerque, N.M., developed 3-D seismic imagery for the four salt domes used by the Strategic Petroleum Reserve in Texas and Louisiana.
Sandia, which has an annual research budget of about $3.2 million for underground storage, began developing the 3-D images about five years ago due to concerns about abandoned caverns next to active petroleum reserve caverns, primarily in Texas.
“We do that for all of our domes,” said David Borns, manager of Sandia’s Geotechnology and Engineering Department.
The 3-D imagery allows caverns to be seen in relation to one another and can be rotated for a closer look.
Louisiana Office of Conservation officials have no plans to conduct any similar research on salt domes, Courreges said. Mississippi, Texas and Kansas do not have such imagery capability, officials in those states said.
But in Louisiana, the Office of Conservation has ordered the state’s 34 salt dome operators to show how close their caverns are to the outer faces of the salt formations. The new data from the operators, which may include new 3-D seismic data, will help create a good picture of the state’s domes, Courreges said.
He added that almost all original research is done by the private sector or academia in the United States, not by state and federal regulatory agencies.
Courreges pointed out that Sandia is not a regulator but a contractor working for the U.S. Department of Energy, which oversees the Strategic Petroleum Reserve. The state Office of Conservation regulates the reserve’s caverns in Louisiana.
Courreges noted that having the state conduct 3-D seismic surveys of salt domes, which are typically under private land, would present significant legal issues.
The surveys would be public and give away valuable data on mineral rights, he argued.
“That kind of information is generally considered proprietary by the company conducting the survey, and private by the owner of the mineral rights,” Courreges wrote.
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