Sinkhole bends, shifts natural gas pipeline
Officials close portion of La. 70
BAYOU CORNE — Assumption Parish officials said powerful underground forces unleashed by the formation of an acre-sized swampland sinkhole had bent and shifted an adjacent 36-inch natural gas pipeline, posing an explosion risk to nearby motorists.
As a result, the officials said, they shut down vehicular traffic about 7:30 p.m. Saturday over a four-mile stretch of La. 70 South in Pierre Part and Bayou Corne while the pipeline operator, Crosstex Energy L.P., of Dallas, worked to depressurize the line.
John Boudreaux, director of the parish Office of Homeland Security and Emergency Preparedness, said the pipeline was not leaking but presented an explosion risk if it would rupture.
Assumption Parish Sheriff Mike Waguespack noted that two 20-inch natural gas pipelines owned by Acadian Gas run parallel to the Crosstex line and also were at risk from Crosstex’s line.
“If one of them goes, probably all three of them go,” Waguespack said.
He said the Crosstex pipeline has an operating pressure of 800 pounds per square inch.
An evacuation order remained in place Saturday but area residents were not being forced to leave their homes, Waguespack said.
Officials handling the emergency estimated about 350 people occupy about 150 residences in the Bayou Corne community.
Fears that the sinkhole area could expand, shear off nearby wellheads and release flammable materials prompted Friday’s evacuation order by parish officials.
But Assumption Parish President Martin “Marty” Triche said the slurry area had not grown in size as of Saturday evening.
Boudreaux said the decision to close La. 70 — a major east-west corridor — was required because the pipeline crosses under the highway just east of Bayou Corne.
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 spokeswoman Jill McMillan said in an email that company personnel have responded and “their highest priority is to ensure the safety of all involved.”
“As a precautionary measure, Crosstex has isolated and shut down the pipeline,” McMillan wrote. “We’re currently depressurizing the pipeline, and we expect this to be complete by Sunday evening.”
Waguespack said the road closure would extend from La. 69 and La. 70 southwest to Derrick Street in Pierre Part. He said Derrick is the closest point to the pipeline crossing where 18-wheelers can turn around and find a suitable departure route.
He said that while residents have been advised of the risk of remaining, they would be able to continue to access their homes off La. 70 but would not be able to drive into the area where the pipeline crosses under La. 70.
News of the endangered pipeline emerged Saturday afternoon after officials and curious residents had taken airboats down the Crosstex pipeline corridor to get a closer look at the slurry area and take air and soil samples.
The big sinkhole swallowed and toppled trees overnight Thursday, turning the formerly forested patch of swamp into a watery mud flat flecked with bits of green foliage and tree tops peeking out of the dark-brown muck.
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 bubbling 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.
Ball said Louisiana Geological Survey officials have called a meeting for 9 a.m. Monday at LSU where geologists and scientists would be able see all the data at one time.
Parish officials also are planning to hold a community meeting at 6:30 p.m. Tuesday in the St. Joseph the Worker Catholic Church Hall on La. 70 in Pierre Part, a parish government news release says.
Gov. Bobby Jindal declared a statewide emergency Friday and the state Office of Conservation issued its own emergency order Friday directing Texas Brine to evaluate the structural integrity of its salt cavern and to begin remediation efforts in 24 hours.
Sonny Cranch, spokesman for Texas Brine, said the company is committed to working with state and parish authorities to find out what caused the eruption and perform any remediation deemed appropriate.
Cranch said company employees were working on a plan Saturday. He declined to provide details before DNR looked at the document.
While DNR officials have pointed to the cavern as a possible, though not confirmed, cause, Cranch said Texas Brine does not know if the salt cavern is related one way or the other.
“We’re saying, ‘We’re not sure, but we want to find out,’ ” he said.
Cranch said none of Texas Brine’s three brine caverns are used for hydrocarbon storage. DNR officials have speculated that naturally occurring gas could have filled the cavern in question after it was plugged.
The slurry area is on Texas Brine’s 40-acre facility on the south side of La. 70. The sinkhole could be seen Saturday through a patch of cypress trees from the pad of the salt cavern well drawing DNR officials’ attention.
The cavern under that pad, which has a capacity of 20 million barrels, each holding 42 gallons of brine, has been plugged since 2011. It has been out of service for brine production for three years but is filled with brine for structural integrity, Cranch said.
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.
Texas Brine and other brine producers in the area use the salty mix to supply industry. Texas Brine has been operating in the area since 1973 and began using the well in 1982, DNR officials said.
Cranch said the cavern, which is in roughly the shape of a narrow vase, is overlain by a salt cap 1,000 feet thick. More than 2,400 feet of dirt and rock lie atop the cap. The cavern well extends through this upper layer from the surface to the cavern’s top.
He said the cavern has a diameter of 150 feet at the top and 310 feet at the bottom.
While Cranch said he could not say if the cavern had collapsed — as some residents fear — DNR’s Ball suggested it was not likely, given the amount of earth and salt over the top.
Nancy Malone, American Red Cross spokeswoman, said a shelter at Belle Rose Middle School remained open but no one had used it by Saturday afternoon. She said residents were staying mostly with friends and relatives.
While some residents remained in Bayou Corne and could be seen cutting grass Saturday, many others have left.
Abbie and Jason Hue and their daughter departed after a community meeting Friday when the evacuation order was given, Abbie Hue said.
Abbie Hue, 31, said her family was staying with relatives in Belle Rose, at least until school starts late next week. She said her husband has been checking on their residence.
“He just kind of goes back and forth to check it out,” Abbie Hue said. “I mean it’s our home, you know.”