Pulling the Plug on Lake Peigneur

by Dale H. Easley
Department of Natural and Applied Sciences
University of Dubuque

7/17/2000

In 1980, I was taking some of my first geology courses at Guilford College, NC. On the bulletin board outside my professor's office appeared an article about a Texaco drilling rig that was sucked down a hole, draining a lake in the process. It sounded like something out of a bad science-fiction movie. But for the people of Jefferson Island and New Iberia Parish, it was only too real.

In the early morning hours of November 20th, 1980, the drilling rig began to tilt. Not too unusual. The rig was on the soft bottom mud of Lake Peigneur, and the crew was exerting a lot of force as they tried to unstick the drill stem where it had just seized at about 1230 feet depth. Unsticking the drill stem at such a shallow depth should have been fairly easy, but it wasn't. As they tried, the tilt of the rig got worse, leaning two to three feet. Something was badly wrong. The crew decided to release the barges tied to the rig and get off. Shortly afterward, the rig overturned and then disappeared into the lake. A whirlpool one quarter mile in diameter formed, and the entire lake disappeared into a crater formed where the rig had been. Along with it went a second drilling rig located nearby, plus 11 barges and a tug from a canal that had connected the lake to the Gulf of Mexico, 40 acres of Lake Peigneur's Jefferson Island, a house trailer, and more. The canal reversed flow, and a 50-foot waterfall formed where the Gulf water flowed into the crater. Within two days, Lake Peigneur filled back up, and nine of the barges popped back up like toys in a bathtub.

Lake Peigneur held 3.5 billion gallons of water prior to the accident. It takes a mighty big hole in the ground to suck up that much water. It so happens that one was readily available---the Diamond Crystal Salt Mine. The Diamond Crystal mine had been operating since 1920, escavating salt from increasingly deep shafts. Pillars of salt were left to support the 80-foot-high roofs of the shafts, which were as wide as four-lane highways. Texaco had accidentally drilled into one of those shafts. Water dissolves salt, explaining the formation of the massive crater as water poured from the lake into the mine. Fortunately, the 50 miners who were in the lower levels of the mine when water started pouring in were able to evacuate safely, though three dogs died. Two fishermen on the Lake were able to walk through the mud to shore after their boat bottomed out as the lake drained.

How could such an accident happen? Apparently through miscommunication. Texaco was aware of salt mines in the area and had contacted the Corps of Engineers, which in turn contacted Diamond Crystal. Where the communication broke down is unclear. Texaco, Diamond Crystal, and a contractor operating the rig sued each other. In an out-of-court settlement, Texaco and the rig operator paid Diamond Crystal an estimated $45 million. Texaco paid Live Oak Gardens on Jefferson Island another $12.8 million for damages. The mine was closed, and Diamond Crystal soon got out of the salt business. It is now used for storing petroleum.

See another salt dome at Avery Island.