PIERRE PART — A U.S. Environmental Protection Agency aircraft is expected to make back-and-forth aerial passes at 300 feet as soon as Saturday over the Bayou Corne and Grand Bayou areas in an attempt to detect possible plumes of natural gas leaking from the land and water below.
The Louisiana Department of Natural Resources has hired a firm to drill a ground water observation well to test whether natural gas may be in a water aquifer underneath the same area.
And, a science advisory team has recommended a battery of tests for Texas Brine Co. LLC to conduct with the investigatory well that Texas Brine is already drilling to peer inside one of the company’s salt caverns.
Louisiana Department of Natural Resources officials detailed these and other steps during a public meeting Friday.
All are aimed at getting to the bottom of a large sinkhole that was found between Bayou Corne and Grand Bayou on Aug. 3 and prompted an ongoing mandatory evacuation of people living in about 150 homes.
DNR was one of several agencies providing an overview Friday at the parish hall of St. Joseph the Worker Catholic Church in Pierre Part about recent developments in response to the sinkhole and the continuing natural gas releases that preceded the sinkhole by about two months.
DNR scientists think the cavern inside the Napoleonville Dome may have failed and released its brine contents, causing the sinkhole.
The 1-mile-by-3-mile dome is a large salt deposit pushed up from an ancient sea bed under the earth.
The cavern was used in solution mining for nearly three decades to produce brine for industry. In the process, the cavern was hollowed out of the salt dome with water into the shape of a narrow, upside-down vase 3,400 feet underground.
Brent Campbell, DNR Pipeline Division director, told a few hundred people in the church hall that the Office of Conservation and DNR are committed to be in the Bayou Corne area for the long haul.
“We are going to continue to provide any resources that we need to personnel so we can find the cause and try to resolve this problem,” he said.
The group also learned about other theories being considered as a possible causes of the sinkhole or natural gas releases.
Officials with the Louisiana departments of Environmental Quality and Health and Hospitals also continued to say that samples collected from the air and water in and around the sinkhole do not pose a risk to public health.
“While there are a lot of interesting things happening here, one of them is not health risk from pollution. I’d like to make that very clear and the Health Department will point that out when they come as well,” said Chris Piehler, DEQ Inspection Division administrator, adding: “Your health is not threatened from air pollution.”
Piehler noted that the agency’s equipment is sensitive and picking up a variety of chemicals but they are at very low levels, including traces of carcinogenic benzene, or are not toxic, such as natural gas.
“These are incredibly low levels. In fact, I confirmed before coming here tonight that the air quality as indicated by those samples is better than it is in Baton Rouge,” Piehler said.
But residents also received some unsettling news as well.
Michel Cernuska, 36, of Brule St. Martin, asked DNR officials what was being considered by the science advisory group to fix the cavern or its well casing if either has had a failure.
“If it’s as simple as a casing, yes (it can be fixed). If it’s a cavern fracture, failure, whatever, there’s little that you can do,” said Chris Knotts, a civil engineer with DNR who is coordinating the science group studying the sinkhole.
A low but audible rumble in the crowd followed that statement.
Cernuska also asked about the “oxymoronic” evacuation order in light of DEQ and DHH are saying people’s health is not at risk.
But Assumption parish Police Jury President Martin “Marty” Triche said parish officials are not comfortable lifting the order with so many unknowns about the cavern’s cause.