Posted: Aug 4, 2012 10:30 AM
Updated: Aug 4, 2012 10:30 AM
Source: Direct from Christina Stephens/ State of LA
Officials from the Governor's Office of Homeland Security and Emergency Preparedness, the Department of Natural Resources, Louisiana State Police, the Louisiana National Guard and the Department of Environmental Quality have engaged with local officials in Assumption parish who are responding to the threat of subsidence and subsurface instability in the area of Bayou Corner in Assumption parish. DNR has issued an emergency order to compel the Texas Brine Company to take all necessary steps to evaluate the integrity of its salt cavern which ultimately may help provide relief to the sink hole.
For several weeks, state, local and federal officials have been investigating reports of unexplained bubbling and tremors in the area. On Thursday, an area of wooded swamp located in this area began to subside, engulfing large trees and creating a several hundred foot diameter area of a slurry mixture of muddy water and soil where trees and vegetation were the day before.
Assumption parish has declared a state of emergency in order to monitor and respond to the threat posed by this incident to its citizens.
Governor Jindal issued an executive proclamation Friday evening that allows GOHSEP Director Kevin Davis to respond if Assumption parish leaders need support in their response to this continuing threat. It also directs state departments, commissions, boards, agencies and officers to cooperate in actions the State may take in response.
GOHSEP is coordinating information sharing between local, state and federal officials. Officials are determining if Highway 70 near the sinkhole will have to close. The nearest residence is around a half mile from the center of the sinkhole and the parish has ordered a mandatory evacuation of the area.
On Friday, Louisiana Department of Natural Resources Secretary Scott Angelle announced that the Office of Conservation has issued an emergency order requiring a brine solution company to take steps to evaluate the structural integrity of one its inactive salt caverns that may have played a role in both events and remediate any problems found.
Through consultation with all the scientists involved, DNR has determined that the potential failure of a portion of an inactive salt-mining cavern near the area that has been described as a "slurry area" or "sinkhole," is a likely cause of the occurrence and possibly the recent natural gas bubbling, based on the best available information.
The Texas Brine Company is the operator of record for the cavern in question, which was used from 1982 to 2011 as a brine mining cavern - in which water was used to dissolve salt from deep within the Napoleonville Salt Dome, with the resulting brine water marketed to supply various industry needs. The cavern was never used for storage of natural gas or any other hydrocarbon, though naturally occurring gas is sometimes encountered in such formations and may have accumulated in the cavern after it was no longer active.
The company ceased operating the cavern in 2011, plugging and abandoning the well that was used to access it.
The other regulated operating companies in the area will also be notified of the Office of Conservation's Emergency Order and additional orders may be issued.
Final determination of a positive link between the Texas Brine Company cavern and either the natural gas bubbling or the slurry area has not been made, the Emergency Order has given the company 24 hours to begin the evaluation and remediation efforts.
DNR officials have already been in contact with the company, and the company has indicated that it intends to cooperate fully to evaluate the status of its cavern and take action to address any potential failure in structural integrity.
SUPPORT AND TESTING
The Louisiana State Police Air Support Unit provided aerial assessment flights of the scene for local, parish and state officials. LSP air assets will return in the morning for additional assessments. Also, the Louisiana State Police Hazmat Unit continues to monitor developments and coordinate needs with stakeholders. The Louisiana National Guard is performing an overnight flight using night vision-equipped aircraft to assist local leaders in monitoring the sinkhole tonight.
Louisiana Department of Environmental Quality staff continues to take air samples at bubbling sites for flammability and hydrogen sulfide. Thus far, there have been no levels high enough to register on the monitoring equipment. DEQ staff is prepared to take sophisticated isotopic samples at bubbling sites to see if that data will provide more clues to the cause of the bubbling.
DEQ has conducted air monitoring at 92 residences to date with the homeowner's permission. No unsafe air-related pollutants were found. In addition, air monitoring was conducted by boat in the areas of the bubbles in Bayou Corne.