Dept. of Natural Resources issues statement after sinkhole swallows trees

Another tree falls victim to the giant Louisiana sinkhole on August 22, 2013
Another tree falls victim to the giant Louisiana sinkhole on August 22, 2013
Trees being swallowed by giant Louisiana sinkhole on August 18, 2013 (Source: Assumption Parish OEP)
Trees being swallowed by giant Louisiana sinkhole on August 18, 2013 (Source: Assumption Parish OEP)
Photo map depicting the area (outlined in red) where yesterday’s slough in occurred. (Source: Assumption Parish OEP)
Photo map depicting the area (outlined in red) where yesterday’s slough in occurred. (Source: Assumption Parish OEP)

BAYOU CORNE, LA (WAFB) - The Louisiana Department of Natural Resources issued a statement Thursday afternoon to update the public on the response efforts in Bayou Corne and around the more than 24 acre sinkhole.

The statement came after video was released of the two slough-ins that happened Wednesday night and Thursday morning.

In the statement, DNR says "Although the footage reinforces the seriousness of the evolving situation in the area and the need to hold Texas Brine accountable, it does not represent a new threat to public safety in the area."

Work was ceased at the sinkhole site after a burp was reported Wednesday night.

Burps occur when air and gas from deep in the sinkhole bubbles up. It can cause debris to float to the top and, in the past, has caused more trees to be swallowed into the slurry.

Just hours after the burp, the sinkhole swallowed about a dozen trees.

It has been a year since hundreds living near the giant sinkhole were forced from their homes.

Bubbles were spotted in Bayou Corne and Grand Bayou in June 2012. Two months later, the ground opened up and left what is now a 24-acre sinkhole. Residents were evacuated and the most affected residents began receiving weekly checks from Texas-Brine in the amount of $875 per week.

On August 2, Gov. Bobby Jindal and Attorney General Buddy Caldwell announced the state will be suing Texas Brine for environmental damages caused by the failed Texas Brine cavern.

The previous burp and seismic activity was reported on August 8, 2013. On August 18, about 25 trees were swallowed by the sinkhole in an area measured at 50' x 25'.

Here is the statement released by the DNR Secretary Stephen Chustz:

"The sinkhole has continued to grow over time as we've expected. This growth is due to surface water, soil and broken rock that has moved down to fill the space created by the Texas Brine cavern operation that failed in August 2012. This movement is something we expect as the sinkhole shifts out into the predicted area. The failed cavern operation also created a pathway for underground oil and natural gas to rise to the surface. We have seen similar sloughing events several times in the past, often covering areas much larger than that which we saw Wednesday. Again, these movements are expected. We have the best experts in the world working to get this community back to normal as quickly and safely as possible.

"I can certainly understand the concerns of those who saw the slough footage released Wednesday who may be seeing the sinkhole movement for the first time. And for the people of Assumption Parish, as well as those from the outlying areas who are following the response to the situation, I want to assure you that the State of Louisiana has dedicated all possible resources to maintain the highest standard of safety for the public, as well as those who are on-site working on the ongoing emergency response. These movements do not present a new threat to public safety. The bottom line is that DNR and the coordinated state and parish response agencies will continue our efforts to hold Texas Brine accountable for the impact of its failed cavern, to keep the public safe during the response and to do all that we can to provide for the future safety of the public and the environment – and we are committed to that effort until the best available science confirms that the community is once again safe."

Additional Response Information:

The seismic monitoring systems ordered by the Office of Conservation in Bayou Corn are continuously monitoring for potentially hazardous subsurface developments. These systems detected seismic signals indicative of fluid and gas movement several hours before the slough-in, allowing the Assumption Parish Office of Emergency Preparedness On-Scene Commander to stop all work within the containment berms constructed around the sinkhole.

Chustz said that the ongoing study of the sinkhole's progression help experts respond accordingly and understand the sinkhole and natural gas movement better. This monitoring is being carried out by both the multi-agency Science Work Group, created to advise the coordinated response effort, and the Blue Ribbon Commission on Bayou Corne/Grand Bayou Safety created by Governor Bobby Jindal to determine the benchmarks that must be met to provide for a safe return home for members of the community who wish to do so.

Chustz also noted that the slough-in occurred along the eastern side of the sinkhole, away from the community to the west, bringing the sinkhole no closer to La. Hwy. 70 to the north. Though operations directly on the sinkhole have been temporarily halted due to the slough-in and accompanying seismic activity, other efforts ordered by the Office of Conservation continue, including:

• 42 vent wells currently planned/installed: 39 installed, 16 million+ cubic feet of natural gas vented to date (Of estimated 45-50 million cubic feet in aquifer)

• 30 pressure/water quality wells installed

• 5 air monitors installed around sinkhole, checked hourly

• 118 in-home LEL/H2S monitor sets installed by Texas Brine, per order, in 56 properties (all properties that have allowed access)

• 3D seismic survey being independently interpreted by DNR consultant to determine likely sources of natural gas and providing information on current and future stability

• In addition, La. DEQ conducts air/surface water monitoring: 20 DEQ air monitors checked daily for methane or other harmful gas concentrations, 6 located in community, 4 along Hwy 70 corridor, 10 on natural gas bubbling sites, 10 DEQ surface water samples tested daily at bubbling sites

• Seismic monitoring, pressure monitoring of caverns in place to provide early warning of impending stability issues

• Array of surface seismic monitors: 3 seismic monitoring wells – at depths of 450', 1,000', 3,000'

• 4 subsurface surveys to determine current status of caverns/edge of salt

• Ongoing area subsidence surveys

• DNR consultants modeling Oxy 3 collapse, other potential collapse scenarios – establishing early warning protocols

• DNR consultants provide computer modeling to determine likely long-term effects, potential risks to public

• Construction and maintenance of containment berm near maximum estimated sinkhole extent

• Sinkhole oil skimming and debris removal

• Installation of tiltmeters/inclinometers for sinkhole and nearby roadway and bridges

• Monthly sinkhole depth/extent surveys

External engagement:

• Federal agencies: EPA, Department of Energy, Department of Interior

• More than two dozen contractors/consulting companies involved

• Blue Ribbon Commission – made up of experts from across the U.S., Canada and Europe – including experienced EPA consultants, USGS and DOE-Sandia scientists, and experts in fields of solution-mining, gas migration through soil, ground-water remediation, rock mechanics

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