GPR Explained

What is ground penetrating radar?

Ground penetrating radar (GPR) is a non-destructive detection and imaging method which can be used to identify subsurface elements either underground or within a surface such as concrete.

How does ground penetrating radar work?

Ground penetrating radar sends a signal from a receiver into a surface. The signal is bounced off of any materials it encounters within the surface, and creates a reading. This reading can be interpreted by experienced GPR technicians in order to determine what type of material has been located.

What is ground penetrating radar used for?

Ground penetrating radar is used to identify depth and location of subsurface elements. Underground utility locating and concrete scanning are two of the major applications of GPR.

Why is ground penetrating radar used?

Ground penetrating radar is used to create a map of underground utilities and other findings, as well as to scan for materials within concrete. Both applications are necessary before performing any work which would disrupt or damage these elements. Scanning and locating services enable contractors or homeowners to get a clear picture of what lies beneath before continuing with a project.

How accurate is ground penetrating radar?

Ground penetrating radar is extremely accurate! While GPR use can be impacted by external factors such as ground and soil conditions, proper use of equipment and interpretation of readings should result in a high accuracy rate.

Can ground penetrating radar determine the exact size of a subsurface void cavity?

Ground penetrating radar equipment can be used to identify the area where a void is occurring and can identify a void’s boundaries. However, the depth from the top of the void to the bottom of the void cannot be accurately measured.

Can ground penetrating radar be used to scan concrete masonry unit (CMU) walls?

Yes, ground penetrating radar can be used on CMU walls and structures. GPR can be used to determine the presence of grout and vertical rebar within the CMU structure.

Can ground penetrating radar be used on vertical surfaces or ceilings?

Yes, ground penetrating radar is regularly used to scan for the location of rebar in concrete columns and walls. It can also be used to scan the underside of a floor to mark out the reinforcing steel and any embedded conduits.

Can ground penetrating radar be used to locate unmarked grave sites?

Yes, ground penetrating radar can be used to determine the location of unmarked graves for site planning purposes. While older grave sites can be harder to locate because of material deterioration, in most cases the grave sites can be accurately marked out.

What can ground penetrating radar find?

Ground penetrating radar can locate all types of utilities, including electric, steam, communications, gas & oil, water, sewer & storm, and many others. It can also be used to locate void spaces, unmarked graves, and other buried elements. GPR is used in concrete scanning applications to locate the presence of voids, rebar, conduit, post-tension cables, and other structural elements.

How far can ground penetrating radar go?

The depth of ground penetrating radar depends on the application. For concrete scanning, the radar used can typically penetrate depths of 18-24”. For private utility locating needs on grass, soil, asphalt, or concrete the type of antenna used can penetrate up to 8’.

Does ground penetrating radar have any limitations?

While ground penetrating radar is extremely effective, it does have certain limitations. Ground and soil conditions, weather, and type of material being located are just a few of the potential limiting factors. An experienced GPR technician will be able to assess your site’s condition to determine if GPR can be used accurately.

Is ground penetrating radar safe to use?

Ground penetrating radar is a safe, non-invasive, non-destructive tool. GPR does not emit any harmful radiation or other byproducts. The scanning process does not create any noise and the area can remain undisturbed during the course of GPR usage.

How can I determine if ground penetrating radar is needed for my project?

Ground penetrating radar is commonly used to scan and identify subsurface elements. It’s always wise to conduct a GPR scan prior to beginning any destructive work. This typically includes any excavation work deeper than 18”, or any coring, cutting, or drilling of concrete.