Louisiana officials last Friday called for the capture or venting of natural gas in the area of the compromised Napoleonville Salt Dome in South Louisiana. The salt dome is in the area of a mysterious sinkhole that developed earlier this summer, threatening some natural gas pipelines in the area.

Louisiana Commissioner of Conservation James Welsh ordered companies working on the salt dome to assess the presence of natural gas in both the ground water aquifer and the salt dome cap rock beneath their operations; capture, vent or flare any natural gas that is encountered; and analyze any potential impacts to groundwater in the Mississippi River Alluvial Aquifer.

Welsh asked the Shaw Group to oversee the evaluation of gas concentrations in the ground water aquifer and to oversee the removal of any gas found.

The order was issued as part of a declaration of emergency after the state's Office of Conservation found two shallow pockets of gas in an area between the western edge of the salt dome and the Bayou Corne community. A contractor hired by the Office of Conservation drilled monitoring wells to sample for gas, and encountered the gas pockets at a depth of less than 50 feet from surface last Thursday.

The Office of Conservation also has analyzed new data from salt dome owner Texas Brine LLC that indicated that there were pockets of gas within the Mississippi River Alluvial Aquifer and the cap rock above the salt dome.

"This is the reason that the Office of Conservation ordered Texas Brine to take steps to evaluate the below ground conditions near its operation and the reason we have hired contractors and negotiated with land owners to get observation wells drilled near the Bayou Corne community. This will help us gather information that gives a clearer understanding of potential threats to public safety and what the underlying causes are," Welsh said. "This new data indicates the presence of natural gas in the aquifer and cap rock near the existing salt dome operations, and the Office of Conservation is ordering immediate action to assess that risk and take actions where necessary."

The sinkhole and salt dome drama began early this summer with reports of unexplained bubbling in Bayou Corne and Grand Bayou.

In early August the sinkhole appeared and devoured cypress trees and forced the evacuation of area residents. Facilities of Florida Gas Transmission, Enterprise Products Partners LP's Acadian Gas Pipeline LLC, Crosstex Energy LP and a gas storage facility were affected (see Daily GPI, Aug. 7). Early this month an aerial survey of the area by the Environmental Protection Agency found no detectable concentrations of natural gas or chemicals and no elevated radiation in the area of the sinkhole (see Daily GPI, Sept. 5).

Companies with facilities in the area of the sinkhole include Acadian, Crosstex, K/D/S Promix, Chevron Corp., Dow Chemical and Occidental Chemical, as well as Texas Brine. The Louisiana Department of Natural Resources is posting on its website reports by the companies on facilities in the area and their plans to address the sinkhole threat.

Assumption Parish has declared a state of emergency related to the sinkhole, and Louisiana Gov. Bobby Jindal recently declared a statewide emergency as a result of the threat of subsidence and subsurface instability.

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