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The Assumption Parish Underground

Photo by Claire Bangser

Though not technically an island, New Orleans can resemble one. One need, however, only take a quick look at the leagues of coal-cars that stop traffic on St. Claude once a day, or the gravel-loaded barges that are pushed daily up the Mississippi, to remember that we are a part of an industrial network, one of several Gulf Coast cities that keep the minerals moving.

One of Louisiana’s more curious and less-told stories is the development of Bayou Corne’s sink-hole. Located an hour and a half outside the city on one of the precious islands of land that interrupts the sunken cypress stands and marshland, Belle-Rose is being evacuated. The residents of Jambalaya, Sauce Piquante, Gumbo and Crawfish Stew streets are being given $875 a week to stay away. Many do not.

In late May, natural gas was found to be bubbling out of the bayou’s waters. The effusions were tested and determined harmless. On August 3, after locals were alerted by a diesel smell, a large swath of bayou was found to be missing. The area was isolated enough, and if, for instance, local birds sang snatches from the final aria of Don Giovanni that day, nobody would be around to report it.

The sink-hole, however, continued expanding. Geologically speaking, an ancient process was ending with an uncommon bang. This requires a word about underground salt-deposits.
The salt, remains of long-evaporated oceans, is significantly more buoyant than recent layers of sediment. As a result, over the course of millennia the salt slowly extrudes toward the surface. The geological form is a diaper, and in this case the diapiric salt obeys the precepts of the Rayleigh-Taylor Instability equations, which dictate the interface between liquids of different densities. The outcome is the shape of the crab nebula or a mushroom cloud. It becomes a salt dome.

For months before the sink hole occurred, Texas Brine had been pumping slurry of natural-gas and petroleum underground to take the space of the salt that it was extracting from the dome. The pressure, however, proved too much for the well, and the upper level of the dome collapsed, threatening to collapse the remainder of the dome.

Now, eight months after the sink-hole began expanding, the mandatory evacuation wears on. Its well compensated attrition has left some unfazed. One fisherman we spoke to scoffed at the money; with no spite, he matter-of-factly pointed out that crawfish could bring in $2,000 per week.

When we asked why he didn’t relocate to a city, maybe Thibodaux, he laughed, “This is paradise…where else would I go?” Motioning to a house down the block, he told us that his neighbor was 70, and he’s not going anywhere.

Photo by Claire Bangser

Walking through the streets of the small town, a boat in every yard it seemed, one is struck by the eerie sensation that the whole place could enter the underworld that very day. In case of such an event, sensors around the town detect natural gas levels to provide early warning.

Erik Vande Stouwe writes about the New Orleans region for NolaVie.