Crews breach cavern roof, begin testing at sinkhole

Crews drilling a well that will be used to examine a failed salt cavern believed to have caused the massive sinkhole in Assumption Parish reached the deep cavern’s roof Saturday night after a delay caused by equipment failure Friday, officials said.

Crews with Riceland Drilling Co., of Lafayette, had halted their efforts Friday morning because of an issue involving a mud pump near the bit at the tip of the drill pipe, John Boudreaux, director of the Assumption Parish Office of Homeland Security and Emergency Preparedness, has said.

Work restarted around 7:30 a.m. Saturday, said Sonny Cranch, a spokesman for Texas Brine Co. LLC of Houston, which owns the cavern.

Crews finally penetrated the cavern roof around 8 p.m., Cranch said. No gas pressure or brine pressure was detected, he said.

Breaching the cavern’s roof helps clear the way for a variety of tests to be performed to determine the cavern’s condition, Cranch said.

Personnel almost immediately initiated diagnostic work on the cavern and officials expect to have some results available within 48 to 72 hours, Cranch said.

State Department of Environmental Quality officials will try to pull samples from the cavern as quickly as possible, Boudreaux said.

“DEQ is on standby along with us,” Boudreaux said.

The sinkhole appeared Aug. 3 on Texas Brine property between the Bayou Corne and Grand Bayou communities south of La. 70 South, about two months after natural gas releases in nearby waterways and earth tremors began popping up.

The sinkhole’s appearance prompted the evacuation of residents from about 150 nearby homes.

The Louisiana Department of Natural Resources ordered Texas Brine to drill the well after scientists suspected Texas Brine’s salt cavern in the Napoleonville Dome failed and released its brine contents, which in turn possibly caused the sinkhole.

The drilling rig was fully assembled on site by Aug. 17, and the process has moved relatively quickly aside from the mechanical failure Friday and work stoppages related to Hurricane Isaac’s landfall in late August.

Parish officials and Texas Brine representatives had estimated the well would be finished about 40 days after drilling began.

Edges of the sinkhole caved in twice in three days last week, officials have said. A 25-foot-long section collapsed Thursday morning after a 200-foot-long section sloughed off Tuesday evening, officials have said.

No edges appear to have collapsed within the past couple of days, Boudreaux said.

Officials captured aerial images of the sinkhole Saturday and released a photo comparing the slurry area’s size to how it was about a month ago. The latest dimensions put the sinkhole’s unevenly-shaped perimeter at 486 feet at its longest diameter and 409 feet at its shortest diameter.

That represents a span of about 100 feet of total growth, Boudreaux said.

“In general, there’s been about 50-foot growth on about the east and the west,” he said.