GPR finds what is hidden: buried utilities, embedded concrete reinforcement, underground voids, pipes, and buried objects of all kinds. The answer depends on where you point it and who is reading the results.

Ground penetrating radar (GPR) is a non-destructive subsurface scanning technology that uses radio waves to detect and map objects and anomalies below the surface. The question of what GPR can find has as much to do with where you point it as it does with the technology itself.

One of the reasons GPR has become such a valuable tool across construction, infrastructure, environmental, and forensic applications is its ability to identify both metallic and non-metallic objects without disturbing the ground or structure being investigated. From underground utilities and embedded structural components to potential voids and buried objects, GPR provides critical insights into conditions that would otherwise remain hidden. Understanding what GPR can and cannot detect helps project teams choose the right investigative approach, reduce risk, and make more informed decisions before excavation, drilling, coring, or other intrusive activities begin.

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What Can Ground Penetrating Radar (GPR) Detect?

Buried Utilities 

GPR is used extensively in utility locating. It can detect both metallic and non-metallic buried utilities, including gas lines, water mains, electrical conduit, telecommunications lines, and fiber optic cable. Unlike electromagnetic (EM) locating, which requires a conductive material to trace, GPR can find PVC and other non-metallic utilities by detecting the dielectric contrast between the pipe and surrounding soil.

Pipes

In addition to utility lines, GPR can locate pipes embedded in concrete slabs, walls, and columns. This is critical for concrete scanning applications, where coring, cutting, or anchoring into an unknown pipe can cause water damage, structural compromise, or injury. GPR identifies the location and depth of embedded pipes so work can proceed safely around them.

Potential Void Spaces

GPR can detect potential voids beneath pavement, concrete slabs, and soil. Voids form for a number of reasons: soil erosion from leaking utilities, subsidence, dewatering, and karst geology. Locating voids before they cause surface failure is one of the most safety-critical applications of GPR. GPRS has used GPR to locate voids beneath active roadways, airport aprons, and building foundations.

Buried Items

GPR has a long history of use in archaeology and forensic investigation. It can locate buried foundations, underground storage tanks (USTs), buried debris, and in some cases, unmarked graves. GPRS has been consulted on forensic projects involving potential unmarked burial sites, and GPR technology has been featured in documentary television programs examining historical sites. A GPRS team also used GPR to help locate a 175-year-old church cornerstone that had been lost for decades.

Rebar and Structural Components

In concrete scanning, GPR locates rebar, wire mesh, post-tension cables, and other embedded structural elements. This is essential before any concrete penetration. Striking a post-tension cable releases the stored energy in the cable violently and can compromise the structural integrity of the slab. GPR identifies the location and depth of these elements so cores and cuts can be placed safely.

GPRS, the nation’s largest private utility locating company, deploys GPR for utility locating, concrete scanning, void detection, and subsurface investigation nationwide. All findings are stored in SiteMap®, GPRS’ secure infrastructure management platform, giving clients a permanent, accessible record of what is buried or embedded on their site.

Contact GPRS to schedule a service or request a quote.

GPRS does not provide geophysical, geological, land surveying or engineering services. If you need such services, please contact an appropriate professional.