Ground Penetrating Radar (GPR) is traditionally used to locate utilities, pipes, voids, and obstacles on construction projects - but what else can GPR locate? How do GPR technicians work with non-construction companies on occasion?
How Law Enforcement Uses GPR
The use of ground penetrating radar (GPR) as a law enforcement technology has increased widely, primarily due to GPR’s ability to detect both non-metallic and metallic objects. Police use GPR to find everything from buried weapons to unmarked graves.
The ability to quickly discover hidden objects such as human remains using GPR offers real-time results that will hopefully lead to quick arrests and convictions. The use of GPR as police technology for this purpose can be seen in our neighboring state of Oklahoma where the Oklahoma State Bureau of Investigation officials were able to find the remains of a mother they’d been searching for 3 years prior. The Pottawatomie County District Attorney stated that “without that technology, it’s possible that we would not have found the remains.”
Another common use for GPR by law enforcement is to find objects hidden in walls. While most applications of GPR technology are seen on the ground, ground penetrating radar equipment can be used on walls or other surfaces. This is especially useful for law enforcement where it’s important to avoid damaging the evidence they are attempting to retrieve.
How can GPR help with material investigations?
The use of ground penetrating radar is one of many geotechnical survey methods available to detect objects underground. It’s the most versatile of the methods for material investigations. In this context, material investigations refers to the examination of various materials to determine qualities such as material thickness and composition.
GPR is able to detect the depth (and therefore thickness) of pavement, allowing individuals to see any wear and tear. This is helpful in evaluating roads, bridges, and airports. One of the benefits of using GPR for this purpose is that it limits downtime; results from a ground penetrating radar device are seen instantly and scanning is done quickly. Quick results mean roads, bridges, and airports require shorter closures and delays to complete the analysis.
Using GPR for Environmental Studies
When it comes to environmental impact studies and other environmental applications, one common use of GPR is as a non-invasive method of studying and predicting water contamination. Traditionally, drilling and direct sampling were used to identify contaminated regions, but these methods have the risk of contacting or spreading the contaminant. GPR systems do not have this concern as they are used on the surface of the ground, making them ideal for environmental surveys.
There are 3 ways in which GPR can be used for these purposes:
- To locate the specific location of the contaminant
- To obtain a large-scale model of the geologic structure of the subsurface (providing a framework for the development of a hydrogeologic model)
- To assign values of hydrogeologic properties within the framework referenced above
GPR for Grave Location
Ground Penetrating Radar is used for grave location by a variety of parties including law enforcement, individuals with older family cemeteries, and those looking for native burial sites.
You may have seen in the news that in Canada, over 1,000 indigenous children’s graves and remains have been found at formal residential schools. Ground penetrating radar was used by first nations communities to find these sites in British Colombia and Saskatchewan and similar work is being done in the US. Initiatives such as the Federal Indian Boarding School Initiative are working to locate burial sites and identify the names and tribal affiliations of children who went to these schools. In 2017, a GPR survey conducted as a part of one of these initiatives, assisted in the exhumation of the remains of at least 23 children who were then able to be returned to their home communities.
As mentioned earlier, law enforcement also uses GPR for the sensitive task of locating graves and remains. Additionally, those with unmaintained or older family cemeteries can employ the help of a GPR technician to help them identify and mark the graves.
GPR for Archaeological Digs & Research
Archaeologists use a variety of tools and techniques to assist with their projects; these include lidar, gradiometers, magnetometers, and ground penetrating radar. These are used to map archeological features below the surface of archeology sites and GPR is one of the best archeology tools available.
- Lidar is one of the common tools used for archeological projects, it can be done with an instrument on the ground but is usually done with the assistance of a plane making it an expensive option. Lidar examines the surface of the Earth using light detection and ranging, a pulsed laser uses light to measure variable distances to the Earth.
- A gradiometer or magnetometer can be used for studying subsurface magnetics which is useful in identifying metal artifacts (and anything that has an aligned magnetism toit). However, it’s a passive technique, it doesn’t send any information into the ground via a radar wave the way GPR does, it just receives whatever magnetic information is coming in.
- GPR provides the greatest detail in comparison to any of the other techniques used for archaeological projects. It is especially useful due to its ability to detect depth, which allows archeologists to look at features in both profiles and with slice maps they make. Once the information from GPR scans is processed, it can be used to create three-dimensional imagery.
While the most common use case for ground penetrating radar technology continues to be subsurface analysis for construction, non-traditional uses of the technology continue to grow in popularity. GPR is affordable, quick, and provides detailed information such as depth, location, and size readings, which other technologies simply cannot.
There are many unique uses for GPR technology beyond those listed above. If you are interested in using GPR for any of the purposes above or would like to find out if it can be used for something else, please contact us to tell us more about your project.
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