What Is Ground Penetrating Radar?
Ground Penetrating Radar (GPR) is a non-destructive geophysical method that uses electromagnetic radar pulses to image the subsurface. A GPR system consists of a transmitter antenna that sends radar energy into the ground and a receiver antenna that captures the reflections as that energy bounces back off buried objects, interfaces between different materials, and changes in soil properties. The result is a real-time cross-sectional image of everything below the surface.
How GPR Detects Buried Utilities
When a GPR radar pulse encounters a buried object — like a utility pipe, conduit, or cable — the change in material creates a reflection that is picked up by the receiver. The time it takes for the pulse to travel down to the object and back up tells the technician how deep the object is buried. By systematically scanning across a site, the technician builds up a complete picture of all buried objects in the area.
GPR vs Electromagnetic Locating
The most common utility locating method — electromagnetic (EM) locating — works by tracing an electrical signal along a conductive utility line. EM locating is fast and very accurate for metallic utilities like copper wire, steel pipe, and metallic conduit. However, EM cannot detect non-conductive utilities like PVC water pipe, concrete sewer, HDPE conduit, or fiber optic cable in plastic conduit. GPR detects all of these — making it an essential complement to EM locating on any comprehensive utility locate.
What GPR Can and Cannot Detect
GPR can detect metallic and non-metallic utility pipes and conduits, electrical cables, fiber optic cables, concrete structures and slabs, voids and sinkholes, buried tanks, rebar in concrete, and changes in soil composition. GPR depth penetration is limited by soil conditions — dry sandy soils allow deeper penetration, while wet clay soils limit GPR effectiveness. In typical Florida sandy soils, GPR can achieve utility detection depths of 3–10 feet.
When GPR Is Required
GPR scanning is strongly recommended — and often required — whenever the project involves non-conductive utilities that EM locating cannot detect, when precise depth information is needed for critical crossings, for SUE Level B quality designation projects, for concrete scanning before core drilling or cutting, for projects near high-risk utilities where comprehensive detection is essential, and for any site where EM locating alone may not provide complete coverage.
GPR in Florida's Soil Conditions
Florida's predominantly sandy soils are among the most favorable in the United States for GPR performance. The low clay content and generally dry subsoils allow for excellent GPR penetration depths and good signal clarity. Our GPR technicians are trained to interpret GPR data in Florida's specific soil conditions, and we adjust our methodology to account for any site-specific factors that may affect scan performance.
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