Last Modified: Thursday, December 06, 2012 1:58 PM
BAYOU CORNE (AP) — Officials say vent wells burning off gas trapped in an aquifer in Assumption Parish have removed slightly more than 2.7 million cubic feet of gas since flaring began.
But those same officials told The Advocate what remains unclear is what kind of progress that figure represented toward diminishing the gas threat for the Bayou Corne and Grand Bayou communities.
About 150 homes in the area have been under an evacuation order since Aug. 3.
Scientists believe the gas migrated upward from natural formations along the Napoleonville Dome after a Texas Brine Co. LLC cavern in the salt dome failed this summer and caused a large sinkhole to form in swamps south of La. 70 South.
Methane had been bubbling up in area waterways for more than two months before the sinkhole was found Aug. 3 and continued to bubble up Wednesday with no significant decrease, parish officials said.
John Boudreaux, director of the parish Office of Homeland Security and Emergency Preparedness, told The Advocate more information is needed about what has happened to the free methane believed in the aquifer under the area.
"It's to be determined," he said Wednesday.
Boudreaux and Texas Brine officials have noted that the rate of gas flow from vent wells has declined since flaring began.
Sonny Cranch, spokesman for Houston-based Texas Brine, said there is an indication the gas flow is diminishing but noted, as Boudreaux did, that water in the vent wells or other restrictions might be limiting the flow.
However, the reduced vent well flow may not necessarily reflect a reduction of gas volume in the aquifer, he cautioned.
The failure of the Texas Brine cavern also unleashed crude oil from pockets along the salt dome that found its way upward and into the sinkhole, which now has a surface area of more than 8 acres, as well as into the broken Texas Brine cavern, scientists believe.