How Does Ground Penetrating Radar Work?

Perhaps you’ve seen ground penetrating radar (GPR) services performed on documentary TV programs, and wondered how this technology is being harnessed to locate utilities and other buried objects. From a promising start in the early 20th century, using radar pulses to locate buried objects was largely employed by the military until the late 1980s, when the first equipment for consumer use was developed. While still utilized by geologists to study bedrock, soils, groundwater, and even ice, GPR is primarily the preferred tool used by law enforcement  and in engineering applications, such as utilities mapping.

A now standard application for ground penetrating radar is in locating underground utilities. Standard induction utility locating tools require conductivity with the buried object. However, as most utility lines and sewer pipelines are vinyl-clad conduits, or are constructed from concrete or PVC, such tools prove ineffective. As GPR detects variations in soil properties below the surface, it is ideal for locating these non-conductive utilities.

GPR is Not an Intuitive Technology

How do ground penetrating radar services work? These systems, which resemble a lawn mower, work by sending a small energy pulse into the soil via an antenna. A computer, which is integrated into the system records the time and strength required for the return of a reflected signal. A signal will only return if it encounters and reflects off a stationary object below the surface. Reflections are produced by many different natural and man-made materials below the surface including rocks, debris such as broken glass, building materials, and pipes and wires. Such reflections or bounce backs, are shown on the computer screen in real time as the GPR equipment passes over it. GPR equipment is sensitive to the point where it can indicate if the object is metal or not.

Ground penetrating radar equipment is not an intuitive technology. In fact, it can take days or even weeks of specialized training to use and interpret reflected findings with accuracy. Many municipalities now require that before homeowners and construction teams break ground, that the site’s utilities are mapped to prevent damage and more serious issues. As these sites fall outside of local One-Call system jurisdictions, private utility locating companies, such as PULS, Inc., provide accurate and reliable solutions using GPR and other supportive technologies to ensure the safety of any underground utilities at any worksite. For more information regarding our ground penetrating radar services, please contact us at (800) 883-6855.