Groundpenetrating Radar And High-Resolution Reflection Seismic Surveys Of Subsidence Features Along Interstate 44 Springfield, Missouri

In May of 1997, the Department of Geology and Geophysics at the University of Missouri-Rolla<br>conducted a reflection seismic survey and a ground penetrating radar (GPR) survey for the Missouri<br>Department of Transportation (MoDOT) along and adjacent to a 300 meter section of Interstate 44 in<br>Springfield, Missouri. In October of 1997, a second GPR survey was conducted along the same section of<br>interstate. The site was located approximately 1.5 kilometers west of Missouri Highway 266. The section of<br>interstate studied overlies an active sinkhole and has experienced continued, localized subsidence.<br>Seven 12-fold reflection seismic profiles were acquired along or near Interstate 44, using a Bison 24-<br>channel seismograph and an EWG weight drop source. Forty-live GPR profiles were acquired along paved<br>sections of Interstate 44 during the first survey. During the second GPR survey, the survey area was<br>expanded to include a total of seventy ground penetrating radar profiles. A GSSI SIR-S GPR unit equipped<br>with a 500 MHZ (megahertz) monostatic antenna/receiver was used to acquire the data.<br>The geophysical surveys were successful. The reflection seismic data established that sinkholes,<br>both active and nonactive are prevalent in the area. The seismic data also supports the interpretation that a<br>sinkhole lies immediately beneath the interstate. The ground-penetrating radar data also proved to be of<br>significant utility. Anomalous areas interpreted as voids on the GPR data were drilled and significant volumes<br>of grout were injected. The second GPR survey established the success of the grouting program.