NAPOLEONVILLE — Consultants working with Texas Brine Co. LLC to create finely detailed images of subsurface features beneath an 8.6-acre sinkhole and nearby swampland communities sought Wednesday night to allay concerns about potential effects from the seismic work.
Confronting the consultants were not only people worrying about what the seismic waves might do to their properties but also some audience members’ expressions of continuing frustration and skepticism stemming from the nearly six-month evacuation ordered just after the sinkhole erupted Aug. 3 in northern Assumption Parish swampland near Bayou Corne.
Under a modified order from the Louisiana Office of Conservation, Texas Brine is planning to create a three-dimensional seismic image peering as far down as 7,000 feet beneath the sinkhole area.
Scientists believe a Texas Brine salt cavern in the Napoleonville Dome failed far underground, causing the sinkhole to form and releasing crude oil and gas from the formations in contact with the big salt dome.
The seismic work will involve use of vibration trucks, air guns and M-80-style explosives to send energy waves into the ground to reflect off subsurface formations before being collected by a series of geophones.
Geophysical consultant Kevin Hill told more than 150 people attending the community meeting in the Assumption Community Center in Napoleonville that the work will collect 43,825 image points over 2.25 square miles, including in the Bayou Corne community along La. 70 South.
Hill said the vibrations would be less than the shaking caused by the 18-wheelers that regularly drive by on La. 70 South through the Bayou Corne area. He said that the new seismic images will be compared with 3-D seismic imagery taken of the same area in 2007.
“Now we’re trying to put together an image from before and after. We really don’t know what ‘right now’ looks like, and until we do, we’re kind of all guessing,” Hill said.
“So if we can get this picture, we’ll all have a lot better idea of what’s out there.”
Hill said the seismic imagery should reveal the face of the Napoleonville Dome, the location of any escaped oil and gas and display further underground details.
But Hill and the firm helping with the seismic shoot, Boone Exploration Inc., needs access to landowners’ property to install geophones that will record energy waves.
Texas Brine already has agreements for geophones involving about 85 percent of the land held mostly by large landowners but needs such agreements with owners of small lots in Bayou Corne.
But Hill and other Texas Brine consultants were confronted with questions about whether termites would be stirred up by the energy waves or whether the seismic could void their termite contracts. Residents also voiced concerns about the company’s agreement to allow access and what effect the seismic waves would have on residents’ property.
Hill said he designed the project to be as minimally invasive as possible and hired Boone, which he said has a reputation for environmentally sensitive work. Hill said the field work should be finished by early April.
One man in the audience, Tim Rathburn, 63, asked Hill for some sort of compensation for landowner access in recognition of evacuees’ lengthy evacuation.
Dennis Landry, who owns a boat launch and cabins in Bayou Corne, urged residents to keep sight of the big picture and the importance of the 3-D seismic work, saying he was not concerned about damage.
“I say go ahead with it. I am ready to sign,” Landry said.
Landry’s announcement was followed by applause as well as a shout from at least one man who indicated he disagreed with Landry.
Later, Mike Schaff, 63, who lived in Bayou Corne, evacuated for a time, but has since returned, told Hill that he noticed Hill’s and other consultants had seemed to become slightly angry under questioning from residents.
Schaff said Hill had to understand that it is the residents who are angry after six months of waiting to go home and going to similar meetings like the one they were attending Wednesday night.
“We are man enough and woman enough to accept the truth,” Schaff said. “Please tell us the truth.”