TREMORS, BUBBLES IN THE BAYOU, AND A SINKHOLE

 

A 381-foot-deep sinkhole that emerged last week near the Bayou Corne community is filled primarily with salt water mixed with traces of diesel fuel, while the muck and vegetation visible at the surface is only six inches deep, Assumption Parish [Louisiana] officials said Monday.

A nearby 20-million-barrel Texas Brine Co. LLC of Houston salt cavern, which was plugged in 2011, was filled with brine, a water-salt mixture, for structural integrity, company officials have said.

Some closed salt caverns also have diesel fuel at the top as a “pad” to prevent erosion of the salt from the brine, said John Boudreaux, director of the Assumption Parish Office of Homeland Security and Emergency Preparedness.

The disclosures Monday may further point to Louisiana Department of Natural Resources officials’ suggestions Friday that the sinkhole, which has a diameter of 372 feet, was caused by the possibly failed cavern.

“It’s suspect,” Boudreaux said.

In an earlier story in the Baton Rouge Advocate, people who lived in the area of Bayou Corne reported  tremors and gas bubbles in the bayou, as in the photo above.  You may or may not know that earthquakes are extremely rare occurrences in Louisiana.  Gas bubbling up in a Louisiana bayou is also an unusual event.  So what's going on?

Assumption Parish emergency officials have asked to meet with an expert from the U.S. Geological Survey and for portable seismic equipment to get a better understanding of new tremors reported in the Bayou Corne and Grand Bayou areas, officials said Friday.

The earth tremors are being reported by residents in a swampy area of northern Assumption Parish where venting streams of natural gas have been roiling the surface of waterways for about a month.

The source of the natural gas remains uncertain and is not an explosive risk but detailed tests to fingerprint the source of the leaking gas are pending, said John Boudreaux, director of the parish Office of Homeland Security and Emergency Preparedness.

The word from the state at that time was that tests show the gas was not explosive, and no connection has been made between the tremors and the gas bubbles.
  

Then comes the sinkhole. Who would ever have expected...?  But wait! Maybe the sinkhole should not have been so much so much of a surprise to state officials.  

In a Jan. 21, 2011, letter, Mark J. Cartwright, Texas Brine Co. Saltville LLC president, informed DNR about a failed integrity test of the cavern and company officials’ subsequent suspicion that the cavern may have breached the Napoleonville Dome’s outer wall, possibly explaining a loss of pressure in the cavern during the test. (Read letter.)

“One obvious concern is the cavern’s proximity to the edge of salt,” Cartwright wrote to DNR’s Joseph “Joe” S. Ball Jr. “There have been several studies in this regard, and Texas Brine has mapped the salt boundary near the cavern applying available well log data, seismic data, and most recently, vertical seismic data gathered during the workover. At this time, a breach out of the salt dome appears possible.”

Ball is the director of the DNR Injection and Mining Division, which oversees salt caverns.

Neither parish officials nor the public was informed that the integrity of the salt cavern may have been compromised.  Over 300 people have been evacuated from their homes, and more may have to go.  In addition to concerns about natural gas and diesel leaks, we learn that some years ago, Texas Brine was allowed to pump radioactive waste into the cavern which may now be leaking.

As I read the Advocate story linked at the beginning of the post yesterday morning, I noted another story on the same page of the announcement by the governor's office that Scott Angelle, Secretary of the Department of Natural Resources, resigned, no reason given.  We could maybe take a guess as to the reason.

I've been trying to post about the story since there was only one report, but I have not had time.  Now I have four links expanding the story, and I could probably find more.  The story grows and grows, and the situation looks grimmer and grimmer.

Question: If we extract large amounts of materials from beneath the ground, why are we surprised, when the ground collapses?