Louisiana sinkhole threatens gas pipeline explosion
06 August 2012
Local officials put in place an evacuation order for the inhabitants of 150 homes in the Bayou Corne community south of Baton Rouge in the Mississippi Delta on August 4, after an acre-sized swampland sinkhole appeared and threatened to rupture gas pipelines in the area. A four-mile stretch of the LA70 south highway was also closed.
The acre-wide sinkhole has swallowed a large number of trees and has affected nearby gas pipelines
John Boudreaux, director of the parish Office of Homeland Security and Emergency Preparedness, told local media the pipeline was not leaking but presented an explosion risk if there were any breaks.
Crosstex Energy of Dallas worked to depressurise its own 36-inch line, which was bent by the sinkhole, and two 20-inch natural gas pipelines owned by Acadian Gas running parallel to the Crosstex line were also said to be at risk.
Some 350 people are affected by the evacuation order.
Boudreaux said the compromised section of pipeline stretches about 400 feet in length about a half-mile south of La. 70. The pipeline has bent 16 feet downward and 15 feet to the east toward the sinkhole.
Crosstex isolated and shut down the pipeline, and depressurising was expected to take until late on April 5. The sinkhole turned a formerly forested area into a watery mud flat with tree tops sticking out of the mud.
Louisiana Department of Natural Resources officials believe a potentially failed salt cavern well owned by Texas Brine Co. LLC, of Houston, could be the cause of the sinkhole, as well as natural gas releases which had been bubbling up in Bayou Corne and Grand Bayou for more than two months.
Joe S. Ball Jr., director of DNR’s Injection and Mining Division, said some scientists are suggesting that a large gas bubble belched upward from underground and reached the surface, liquefying the overlying soil and creating the slurry.
Governor Bobby Jindal declared an emergency for Assumption Parish on April 3 and the state Office of Conservation issued its own emergency order directing Texas Brine to evaluate the structural integrity of its salt cavern and to begin remediation efforts in 24 hours.
Texas Brine says it is working with state and parish authorities to find out what caused the eruption and perform any remediation deemed appropriate.
None of Texas Brine’s three brine caverns are used for hydrocarbon storage, but DNR officials have speculated that naturally occurring gas could have filled the cavern in question after it was plugged.
The cavern’s solid salt deposits were dissolved with injected water from the western flank of the Napoleonville Dome and extend from about 3,400 feet deep to 5,650 feet deep.