GPR survey conducted. Survey objective was to map.
GPR survey conducted in Warren, PA. Survey objectives were to map failures in the asphalt liner and voids beneath the asphalt liner. The system shown is a G.S.S.I. Sir 2000 with a 400 Mhz antenna.
GPR survey at Amchitka Island, AK. Survey objective was to determine the thickness of bentontite and gravel layers at the bottom of the pond. The system shown is a G.S.S.I. SIR-2 with a 200 Mhz antenna.

  Ground Penetrating Radar Method
Ground-penetrating radar (GPR) is a high-frequency electromagnetic method that FPM Geophysical and UXO Services commonly applies to a number of engineering and environmental problems. GPR allows for the collection of large amounts of data in a short period of time, making it a cost-effective method for many projects.

A GPR system radiates short pulses of high-frequency EM energy into the ground from a transmitting antenna. This EM wave propagates in the ground at a velocity that is primarily a function of the relative dielectric permittivity of subsurface materials. When this wave encounters the interface of two materials having different dielectric properties, a portion of the energy is reflected back to the surface, where it is detected by a receiver antenna and transmitted to a control unit for processing and display. GPR provides a continuous profile of the subsurface.

Depth penetration is a function of antenna frequency and the electrical conductivity of the soils in the survey area. Lower frequency antennas achieve greater depth penetration than higher frequency antennas but have poorer spatial resolution. Conductive soils, such as clays, attenuate the radar waves much more rapidly than resistive sand and rock. GPR is typically employed to:

  • Locate conduit in concrete slabs
  • Detect former structural elements
  • Locate underground storage tanks (USTs)
  • Determine road bed and bridge deck quality
  • Location fill areas and former ground surfaces
  • Locate rebar and post tension cables in concrete
  • Determine location and depth of subsurface utilities
  • Detect and locate voids and cavities below concrete


    		•