Geological Applications for GPR

Many agree that Ground Penetrating Radar (GPR) is a non-destructive, extremely effective method of discovering the presence or lack of suspected underground objects. However, few realize the geological applications. Civil and environmental engineering design projects often require soil stratigraphy and shallow geologic structure mapping.

In general geological applications of GPR in central MS, investigators are generally looking for information related to formation boundaries, stratigraphic contacts, and bedding structures. In much of the surrounding areas in Fl, GA, AL, TN, and AR where hard rock is more abundant faults, and joints can be evaluated with no adverse impact on the environment. Most major geological features are characterized by sharp vertical and horizontal contacts that are easily imaged in the subsurface. If depth and major structural information is sought TeaCo will tailor a low frequency survey in the 25Mhz – 100Mhz range to characterize the geologic conditions at depth. Should details such as the structure and direction of foreset bedding be a concern, TeaCo recommends mid range frequencies, in the range of 100Mhz – 500Mhz, to best characterize these delicate surficial geologic structures.

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Based on the actual physical properties and limits of the GPR electronics our surveys are designed to stay within these physical boundaries. The most important trade off to remember is that if you wish to image large objects at depth a lower frequency has the best wave properties to realize the goal. Whereas, if the scope is to image very small scale structures in higher resolution a high frequency has the appropriate wave properties to achieve this desired goal.

In some cases more than one frequency will be used to survey an area, to provide a more conclusive report of variously sized objects at varying depths. GPR reflection surveys conducted using the 25-100 MHz frequency antennas are ideal for detection of large scale objects at a 10m to 50m depth. A shallow GPR survey can be conducted using the 200 to 500 MHz antennas to locate smaller objects with a higher resolution at a depth of 2-5m. Very high frequency surveys collected in the 1000 Mhz range provides even better resolution, however this is limited to approximately ½ m in depth of penetration into the subsurface.

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GPR is one of the most cost effective methods of data acquisition. Many targets can be identified as the survey is conducted allowing site work to continue without costly delays, or placing workers at risk. Survey maps can be produced from GPR data collected on site, which is analyzed relatively quickly, providing a permanent reference of underground objects. This makes Geophysical surveying using GPR one of the safest, most efficient, and cost effective methods of data acquisition available.

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Mining Applications
  • Sand & Gravel volumetric evaluations
  • Bedrock depth

Environmental Applications
  • DNAPL remediation mapping
  • UST locating
  • Water table depth
  • Mapping habitats of burrowing animals (Gopher, Tortoise, Snakes)

Forensic Applications
  • Locating remains
  • Locating buried weapons or other contraband
Subsurface Void Application
  • Locating depth and size of voids below runways, roadways, and concrete slab floors
  • Locating washouts around pipes and sewer lines

*Much less invasive or costly than taking multiple core samples to determine location and size.