1:05 p.m. Update from DOTD

STATE OF LOUISIANA

DEPARTMENT OF TRANSPORTATION AND DEVELOPMENT

OFFICE OF OPERATIONS

Assumption Parish Sinkhole Status (9/5/2013)

Recent Developments

  • On 9/4/2013, DOTD became aware of a small area in the pavement surface which has become deformed
    • This area is located on LA 70 approximately 1/2 mile east of the Bayou Corne Bridge
    • In the eastbound lane, it is a circular area about 2 feet in diameter and about 1 inch high
    • In the westbound lane, there are two small ridges across the lane about ½” high.  The ridges are about 10 feet apart
  • There are many possibilities for why the small abnormalities have appeared and many of those may not be related to the sinkhole or seismic activity. These abnormalities (small ridges and a deformed area) are common on roadways throughout the state for various reasons, such as heat, drought and geological formations. The area is heavily monitored by DOTD, DNR and others. There has been no indication that La. 70 has been compromised or is unsafe. However, out of an abundance of caution and to continue a proactive approach, DOTD has started the following efforts to determine the cause and  to closely monitor changes:
    • All previous survey control points along LA 70 are being re-surveyed and compared to the original and last vertical survey data. This will give DOTD engineers an understanding as to how the recent developments compare to historical data.
    • Control points in a smaller grid are being established in the area of these surface abnormalities to monitor vertical changes in the  pavement surface. This will provide more localized information to where the two small abnormalities have occurred.
    • General roughness of the LA 70 pavement will be re-measured and  compared to the original and last measurements. This will provide information that engineers can use to compare the rest of the highway to the localized area.
    • Pavement Structural Value will be re-measured and  compared to the original and last measurements
    • All utilities are being located
    • Grass is being cut and underbrush removed to allow for closer observation of the ground with the right-of-way

Long Term Monitoring Efforts

  • Instrumentation is very sensitive and reads at least every second
    • Accelerometers can detect the movement of vehicles and equipment near the monitor locations
    • Designed to monitor transportation infrastructure only
  • Continuing to monitor and define “noise” in data
  • All movements thus far have been elastic, that is, have returned to the previous location
  • No significant permanent deformations have been detected thus far
  • On 8/22/2013, our instrumentation did measure some movements
    • they were elastic, that is, have returned to the previous location
    • At this time, cannot be directly connected to the seismic event
    • Continue to post process data to more precisely correlate with available seismic information
  • Using processed data to detect presence of trends
  • Future Plans
    • Finalize definitions of warnings and alerts for message system
    • Set triggers above the “noise”
    • Coordinate data from all DOTD instrumentation systems
    • Coordinate DOTD data with seismic data