Ground Penetrating Radar (GPR) is a noninvasive geophysical investigation method that produces a virtual cross-sectional profile of soil and bedrock layers.   GPR is ideally suited to imaging structural features in electrically resistive materials such as sand, limestone, sandstone, coal, igneous and metamorphic rocks, concrete, and ice.  

Example of GPR profile conducted on a roadway. 

Note the downward layers indicative of karst erosion.

Typical depths of investigation capabilities range widely from 12 inches in concrete, 10 to 40 feet below ground surface in most soil materials, too upwards of 100 feet in dry sand or ice.  Radar signals are most attenuated by clay, most shales, saltwater and other electrically-conductive materials.

Additionally, SEI conducts GPR surveys to determine the depth of subsurface interfaces or to determine the lateral continuity of soil and sediment layers, delineate geologic features such as buried sinkholes, lenses of organic soil, soil voids, caves, as well as to locate buried man-made objects such as pipes, drums, underground storage tanks (USTs) and landfill trenches. The method can also be used to profile stream and lake bottoms and sandy sub-bottom sediment layers. Concrete evaluations include the identification of structural reinforcing steel (rebar) including field marking and preparation of AutoCAD maps.

For the GPR surveys as well as the other geophysical survey methods, SEI uses Trimble™ Differential Global Positioning Systems (DGPS) for geologic and feature mapping. Location data is collected concurrently with the acquisition of geophysical data to provide real-time, corrected coordinate data. This DGPS data can be provided in Latitude/Longitude coordinates as well as UTM (metric), and State Plane coordinates systems. The Trimble™ DGPS system has a horizontal accuracy of less than one meter.  

Since 1987, we have evaluated thousands of sites in Florida, Georgia, South Carolina, Tennessee, Colorado, Alaska, Bahama Islands, Belize, Mexico, and Hawaii.  SEI performs over 400 GPR surveys per year.