A GPR survey uses ground-penetrating radar technology to understand what’s below your feet before you dig, build or make other time-consuming or expensive decisions. GPR images the area below ground (or another surface, such as concrete), letting work teams and others understand what obstacles, resources or infrastructure might be located out of sight.
GPR surveys can yield highly accurate results, and the rapid nature of the data acquisition makes it actionable for field teams. Find out more about GPR surveying below to decide if this technology might be the right choice for your needs.
What Is a GPR Survey?
A GPR survey is a method of gathering data about what’s below the ground in a certain area. It uses ground-penetrating radar technology, which sends electromagnetic energy signals into the subsurface. The GPR equipment receives feedback related to the signals it sends. By parsing the data associated with that feedback, it can return information and images that tell a story about what’s below the surface being surveyed.
Typically, GPR surveys require some version of the following:
- A transmitting device. This is what sends the signal into the ground.
- A receiver. This is what receives feedback from the signal.
- A signal digitizer. This technology turns the data captured by the receiver, including how long signals took to return and how strong they were when they arrived, into useful data for a team, such as images.
- A display or tablet PC. This is used to display data in the field and perform real-time processing.
- An encoder or other distance measuring device. This is used to trigger scans.
What Can a GPR Survey Detect?
The way the signal flows through certain materials and how it returns to the receiver helps the GPR technology detect a variety of subsurface infrastructure. GPR surveying is capable of detecting:
- Metal, such as copper pipes, rebar or naturally-occurring metals that might be useful as resources
- Concrete, such as buildings or other infrastructure buried by the passing of time, parts of cemetery structures or concrete drainage pipes
- Natural materials, such as rock obstructions and other geological structures, bedrock and water tables
- PVC, such as pipes used for underground plumbing
- Plastic, including pipes and other infrastructures
GPR can also tell a story about ground strata, including changes in various layers of the earth. The technology can also detect when something is not there, making it possible to discover air pockets that might indicate a cave or sinkhole is in the area.
Common Applications for GPR Surveys
GPR surveying has a wide range of applications, including in practical utility matters, historical research, geological studies and construction. Check out some examples of times when a GPR survey may be beneficial below.
Create Efficiencies for Archaeologists
Ground penetrating radar lets archaeologists and other historical research teams gather information about what’s below the surface before they ever start digging. This can drive efficiencies because teams won’t dig in areas where there’s nothing of interest. They can also manage resources more effectively by assigning the right tools and people with applicable skills to certain areas of the dig site that might hold unique, fragile or valuable finds.
Streamline Safe Utility Work
Utility contractors may need to install (or uninstall) equipment in areas that have seen a lot of upgrades through the years. Mapping out the infrastructure that came before is important to ensuring safety of workers and functionality of the new installation. GPR doesn’t require any digging, so teams can quickly get the lay of the (under)land before making practical decisions and conducting their work.
Conduct Structural Surveys
Before new construction can begin on old infrastructure, questions must be answered. Where are the pipes? What’s under the concrete basement floor? Is the foundation safe, or are there cracks hiding below the surface? GPR surveying can peek below what’s seen with concrete and other infrastructure surface just as it can look underground. Structural surveys can also be used to understand the integrity of infrastructure such as bridges.
Detect and Manage Environmental Hazards
GPR surveys let you understand what’s underground that might be hazardous or problematic for the environment, the safety of new construction or public works needs. That can range from something like understanding the limitations of a landfill area to locating buried drums of hazardous waste for appropriate removal. Environmental GPR surveys can be used for conservation, regulatory or safety purposes.
GPR Surveys for Law Enforcement
Police and other law enforcement agencies can use GPR surveying technology to assess crime scenes or conduct forensic investigations. GPR doesn’t have to be used vertically to assess what’s down below, so law enforcement can also use it to understand what’s behind walls and other structures. This can help them find secret caches or structural voids in buildings that indicate something illicit may be hidden inside.
Many Other Uses for GPR Survey Technology
This flexible technology can be deployed anytime you need to see what’s below ground or beyond certain types of barriers. Some other applications for GPR survey technology include:
- Mapping cemeteries and grave sites. GPR is used to map out historical sites where bones might be buried or understand the limitations and needs of modern cemeteries.
- Understanding the geophysical qualities of various areas. These types of surveys are often done for research purposes to understand the strata layers and what stories they might tell about the geological history of an area. They could also be used to find ground water sources for construction or public works reasons.
- Resource management. In cases where natural resources might be located just below the surface, GPR surveys may be used to help locate sites of interest for mining or other operations. GPR may also be used when efforts have already dug below the surface and there’s a need to look just behind that region to map out safe or profitable approaches.
Choosing GPR Survey Equipment for Your Purpose
If a GPR survey sounds like the right approach to answering your questions about what lies below (or just beyond) certain barriers, there are plenty of equipment options to choose from. The type of GPR surveying technology and equipment you need depends on the tasks you want to accomplish and factors such as how far down you need to look, the conditions of soil and other barriers, and what you’re looking for.