Assumption Parish, La — The Louisiana Department of Transportation and Development will use enhanced monitoring along La. 70, near the Assumption Parish sinkhole.
The improvements will provide broader observation and greater accuracy in measuring the area for movement and subsidence.
DOTD will be able to use data from these monitoring systems and alert responders via DOTD’s Traffic Management Center in Baton Rouge to any significant movement or changes in the area near the site.
The installed equipment includes tilt and accelerometer sensors on the three bridges over Bayou Corne, Grand Bayou and Bayou Choupique, and Shaped-Accelerometer Arrays (SAA) located within the La. 70 right-of-way, and at the two closest bridge locations. Both the tilt and accelerometer sensors and the SAAs are in place to measure movement. All installed equipment is fully functional.
Three Continuously Operating GPS Reference Stations (CORS) have been installed for automated, continuous monitoring of subsidence near all three bridges, and is expected to be installed and fully functional by the end of June. A fourth station is planned for installation along the La. 70 right-of-way on private property. A fifth station is available for deployment, as needed.
DOTD will continue conducting visual inspections until all monitoring devices have been calibrated. So far, no changes in elevation have been found at any of the locations being monitored.
DOTD is conducting a feasibility study to determine if an alternate route could be built in the affected area in the event that La. 70 is compromised and help identify the cost. Multiple alignments are being studied, including a local “run around” alignment, alignments around the salt dome cap, and alignments around the entire salt dome. The study is expected to be complete in September 2013. The next step is the environmental assessment, which will take another 6 months.
The initial capital cost is $1.7 million: $1.2 million for the detection and motorist warning system, and $500,000 for the feasibility study. The annual operating and maintenance costs are $230,000 and includes daily, weekly, and monthly inspections; monthly surveys; traffic control and signage; and data collection and evaluation.
All costs are to be reimbursed by Texas Brine.