GPR provides information, which can be used to help determine construction
conditions without disrupting the site. GPR will image a wide range of subsurface conditions such as:

Ground Penetrating Radar (GPR) uses FM-frequency radio energy to echolocate subsurface features. The technique was originally developed to investigate subsurface features below ice sheets. The GPR method has since been adapted for use over land and water. Over-water surveys are done by passing the radar antenna over the area in a small wooden or fiberglass boat. The signal is then sent through the hull and water column to the sub-bottom material. Signal strength is adjusted depending on type of water, fresh or salt, and depth of the water. As on land, the image is stored on-board in the main computer for printing and review. In a GPR survey, high frequency (10mhz to 3,OOOMHz) electromagnetic (EM) pulses are used to detect changes in EM properties (dielectric permitivity, conductivity and magnetic permeability) as a function of depth. Energy is propagated into the ground, from a transmitting antenna and is reflected back to a receiving antenna from subsurface boundaries at which there are EM property contrasts. As the antennas are moved along the survey line, a series of scans are collected and positioned side by side to form a profile of the subsurface.