Improvements Continue To Drive GPR Applications

By Jeff Griffin, Senior Editor | April 2009 Vol. 64 No. 4
Mala USA's GPR

A GPR locator can locate both metallic and nonmetallic objects. Soil conditions do limit the ability of a GPR. Moisture, clay and sand content are some of the primary factors that limit the depth a GPR can "see." GPR equipment works best in sandy loam soil conditions and in areas where soil conditions are consistent. It also works well on concrete and asphalt. The skill of the operator can either reduce or enhance the successful use of a GPR.

GPR technology continues to improve to make locators more effective in more soil conditions. Plus, the images presented are clear and easier to read. And the price continues to come down. (Ditch Witch markets the Model 2150GR, a dual frequency GPR locator.)

Underground Imaging Technologies (UIT), Mark R. Wallbom, chief executive officer (UIT provides geophysical services with proprietary equipment, including the TerraVision II GPR locating system). GPR is not a silver bullet for all challenges but it is one tool in the box of tools that should be employed as required. Given optimal soil conditions and non congested areas that are relatively flat, GPR surveys can be very effective and dramatically reduce field instances and safety concerns. When a correctly configured GPR unit is applied to a specific task, and the environment in which the GPR unit is used is conducive to achieving good results, the advantages of using GPR are enormous.

However, GPR's ability to locate buried pipe and cable is limited by soil conditions, and it has been estimated that about 50 percent of the U.S. is not suitable for achieving good results using GPR.

A multi array GPR provides much more information than is possible with a single channel/antenna system, and our multi array GPR unit employs 14 separate antennas. Comparative tests have reported that a multi antenna system achieved a probability of detection higher than 90 percent, rather than the 60 percent or less typical of traditional single antenna GPR systems.