Ground Penetrating Radar

Four Oaks Geophysics uses GSSI ground penetrating radar. Depending on the target (utilities, rebar or karst features) an array of antennas can and will be deployed.

Rebar/post tension cable surveys typically require a high frequency antenna (1600 to 2600 MHz) to investigate to a maximum depth of 20 inches. The resolution of these antennas allows the geophysicist to identify rebar, post tension cable, conduit and voids within the concrete slab. The resolution of these antennas also allow the geophysicist to determine the approximate thickness of the concrete as well as the approximate diameter of the rebar.

Utility surveys require mid-range antenna. Four Oaks Geophysics uses the GSSI 350 MHz Hyper-Stacking antenna for utility location surveys. This antenna gives Four Oaks personnel the ability to obtain data even with the adverse soils of the Mid-Atlantic region. Ideally GPR can penetrate to a depth of 6 to 8 feet for utility investigations. However, in the Northeast and Mid-Atlantic United States, GPR can be limited due to the clayey soils. On average, Four Oaks Geophysics is capable of imaging to a depth of 4 feet below land surface.

When conducting a karst survey, achieving the greatest possible depth while still providing the best possible resolution is always the goal. For this, Four Oaks Geophysics can deploy a 200 MHz antenna. This "big boy" can generate a powerful signal that can help penetrate soils to the greatest possible depth.