Oxy Geismar Well No. 3 (serial number: 180708) is the cause of the sink hole.
The well was first permitted in April 15, 1982 for the mining of salt water brine from the Napoleonville Salt Dome.
In 1995 Texas brine received permission from Louisiana Department of Natural Resources to pump soil contaminated with Naturally Occurring Radioactive Material (NORM) into the well.
In early September 2010, Texas Brine began reworking the cavern well, milling a section of salt higher than the existing cavern roof, at 3,400 feet deep, to see if the upper strata could be mined. A DNR permit for that work was issued in May 2010.
In 2011 the well failed a pressure test showing that the integrity of the well had been lost. Texas Brine Company sent a letter to Louisiana Department of Natural Resources reporting the failed test and expressing concern over the possibility that "a breach out of the salt dome appears possible."
On June 6, 2011 the well bore above the cavern was plugged with cement.

Louisiana Department of Environmental Quality reported that tests done on August 8, 2012 showed "no detectable levels for naturally occurring radioactive material" at the surface of the sinkhole or in water samples from the sink hole.

Diesel fuel at the sink hole site is from the "diesel blanket;" a layer of diesel fuel put atop the brine-filled cavern to protect the cavern roof and steel well casings.

get ready...