When residents of Bayou Corne, Louisiana, reported the smell of methane and area boaters noticed streams of bubbles deep in the swamp water, geological experts began to search for a source of seismic activity. They were unable to do so until a massive 4046-sq. metre (one acre) sinkhole opened on land leased by the Texas Brine Company, August 3, 2012.
Geologists discovered the sinkhole was a result of an underground structural failure. The affected area was located over a vast, cavernous, underground salt deposit, known as a salt dome. Companies extract the saline brine associated with salt deposits for use in industrial applications like oilfield borehole drilling. A fissure opened in the cavern’s supporting wall, causing rock and sediment to fall into the void, which created the sinkhole on the surface.
The sinkhole eventually grew to over 30 acres in size. According to an official statement issued by Texas Brine, the area of the stabilized sinkhole was roughly the size of 25 American Football fields. A year later, in August 2013, the sinkhole was estimated to be approximately 230 m (750 ft.) deep. The sinkhole’s edge lay only 275 m (900 ft.) from LA 70, threatening an important part of the state’s traffic infrastructure and the only entrance and exit to the town of Bayou Corne.
After further investigation, authorities discovered a second cavern located closer to LA 70, which prompted LA DOTD to adopt “enhanced and automated, continuous monitoring of LA 70 […] for movement and subsidence.”1
As part of this monitoring program, LA DOTD installed two 50 m horizontal SAAFs between the sinkhole and the roadway, and several others around the slopes of three nearby bridges. These ShapeArrays continue to monitor the area for movement. To date, the monitoring data has not indicated the sinkhole currently poses a threat to the integrity of LA 70 or other surrounding infrastructure.