Devices along La. 70 to monitor sinkhole activity

Monitors to detect earth subsidence or movement along a section of La. 70 South near the Assumption Parish sinkhole have been installed and are fully functional, state highway officials said Thursday.

Additional equipment that will allow automated, continuous monitoring of La. 70, a critical east-west link in Assumption, will be in place and operating by the end of June, highway officials said in a news release.

“The improvements will provide broader observation and greater accuracy in measuring the area for movement and subsidence,” Louisiana Department of Transportation and Development officials said.

DOTD officials said visual inspections will continue until all devices are installed and calibrated. The devices in place have not detected subsidence along La. 70 South.

The installed and fully functioning devices are located at three area bridges: Bayou Corne, Grand Bayou and Bayou Choupique, DOTD officials said.

Another type of measurement device also has been installed near two of the bridges and along the highway right of way.

DOTD officials said a $500,000 feasibility study of an alternative route around the sinkhole is due to be finished in September.

The new equipment has an upfront cost of $1.2 million and annual operating costs of $230,000. DOTD officials said they will seek reimbursement from Texas Brine Co. for all costs.

Gov. Bobby Jindal and DOTD officials said earlier this year that the new equipment would be installed to watch for any effects of the growing sinkhole on La. 70. It has undergone gradual growth and now has a surface area of 15.1 acres and a width of 1,000 feet.

Scientists believe a Texas Brine salt dome cavern failed, triggering the sinkhole in August in swamps south of La. 70 between the Bayou Corne and Grand Bayou areas.

The failed 19.2-million-barrel subterranean cavern, which is taller than all but the highest skyscrapers, has continued to fill with rock at an increasing rate.

The filling process has fueled growth of the hole but the cavern is almost full, scientists say.

The swampland hole is projected, at worst, to grow until its northern rim is within 700 feet south of the highway. Concerns have also been raised about a second Texas Brine cavern, but monitoring shows the cavity is stable, scientists say.