Ground Penetrating Radar

Ground-penetrating radar (GPR) is a non-destructive geophysical method for locating subsurface features. It was commercially developed in the mid 1970s, and is offered by Terra Discovery in two main areas of application – utility locating and concrete scanning.

GPR uses electromagnetic radiation, typically in the UHF/VHF range. A transmitting antenna sends pulses into the ground and a receiving antenna picks up the reflected signals when the pulses hit a buried object or a boundary with different dielectric properties. GPR can be used through soil, rock, asphalt, concrete, ice and water, and is capable of detecting buried objects such as plastic pipes, fiber-optic cables and concrete tanks, as well as changes in material and voids.

The effectiveness of GPR is very much dependent on subsoil conditions in the target area. In one soil condition GPR may reveal features up to 5.0 metres below surface while in another it may only reveal features less than 1.0 metres below surface. Generally, dry sandy soils are the most favorable to work with and moist clayey soils are the most difficult to work with.

Concrete Scanning

Concrete Scanning is a particular application of GPR that uses higher frequency antennas usually in combination with special software designed to interpret scans taken on a grid pattern. Results are dependent on the quality of the return signal which is influenced by the type of concrete mix, thickness of slab, material under slab, and the presence & quantity of reinforcing bars or voids inside the slab. Lack of signal return or too much reflected signal may prevent identification of objects within the slab and produce a "no result" declaration for the scans.