If you are in need of utility locating services before you excavate, or need to ensure clearance to cut or core into concrete, you may be considering your options when it comes to ground penetrating radar (GPR).
The technology and training needed to successfully operate GPR equipment and translate the results into usable data depends greatly on how you are applying it. For instance, if you are interested in concrete scanning and imaging, you would be considering a hand-held GPR unit with an accompanying mobile device like an iPad. If your needs require you to locate private and public utilities on site, the technology required is much larger in scale, although it operates on the same principles.
Can I Operate Ground Penetrating Radar Myself? The Pros and Cons of GPR D-I-Y for Utility Locating & Concrete Scanning
To D-I-Y GPR, utilizing the right kind of technology for your job is key. For instance, a compact, handheld GPR concrete scanning device won't accurately locate a sewer pipe buried three feet under the soil. That job would require a larger, wheeled GPR device like those from Impulse Radar, Proceq, or Leica, which cost anywhere from $14,000 to $100,000 to purchase, depending on features, with an average monthly rental cost of $400 -$1,750.
However, when it comes to a utility locate, GPR is not the only equipment you need to get a comprehensive picture of your subsurface infrastructure. Normally, an experienced professional utility locating company will employ both GPR and electromagnetic (EM) locating technology while scanning for underground utilities. The purchase price for an EM locator is approximately $800 - $5,000, depending on quality and features. You can rent an EM device for about $700 - $1,500 per month.
An EM locator, without assistance from a rodder to transmit a signal, will fail to detect a PVC storm sewer line, though it can independently locate metallic pipes. On the other hand, GPR can discern both metallic and non-metallic pipes, depending on soil type and depth. Both EM and GPR are often required to accurately locate all on-site underground utilities. The cost to rent a rodder/sonde combination to work with an EM locator to find non-metallic pipes is about $250 per month, and you can purchase rodder equipment for $975 - $3,000.
While GPR units and EM technology may be readily available for purchase or for rent near you, their accessibility doesn't guarantee ease in locating and mapping your subsurface utility infrastructure. Each has its advantages and disadvantages. Moreover, there is a significant disparity in cost among GPR and EM equipment, regardless of whether you're renting or buying. There are a wide variety of locating units available, so understanding which one is suitable for your specific task is essential. (A more in-depth discussion of training follows later in this article.)
Total average cost to purchase utility locating ground penetrating radar & complementary tools: $65,000 + training.
All GPR Devices Are Not Created Equal: GPR for Concrete Scanning & Imaging
Which brings us to the costs associated with utilizing GPR for concrete scanning & imaging. As previously noted, the GPR units used for locating post tension cables, rebar, electrical conduit, telecommunications fiber lines, and all manner of MPE features that may be encased in a concrete slab are very different from those used to locate underground utilities. Concrete scanning GPR is hand-held, usually about the size of a deck of playing cards on wheels, and wirelessly connects to a mobile device like an iPad so the operator can assess the “waves,” also known as hyperbolas, on screen to determine the position, width, depth, type, and intersection of encased features. In most cases, this kind of concrete imaging is completed to provide a “clear zone” for workers to saw or drill into the concrete without hitting and damaging utility lines.
When GPRS scans concrete, our Project Managers mark out the encased features, and provide clearly marked green boxes where you can cut or core with GPRS’ Green Box Guarantee. That means you have only a 0.02% chance of striking any encased feature, and if you do hit something, GPRS will pay the material damage costs for the strike.
Hand-held GPR devices from GSSI, Proceq, and others generally run from $11,000 to $17,000 to purchase and can be rented for $1,000 - $4,000 per month. Some models incorporate a display readout for you, but most connect wirelessly to a tablet. Mobile devices or tablets like iPads can be purchased for about $1,200.00 on average. This cost must be added to the cost of the GPR unit itself because otherwise, you could never “see” what you are scanning.
So, your total cost to purchase could be as high as $19,000 to create a complete concrete scanning GPR system. However, unlike the multiple technologies required for underground utility locating, additional complementary equipment is not required to visualize encasements in a concrete slab. It is important to note, though, that GPR cannot discern the structural integrity or condition of a slab. For that kind of structural analysis, you would have to turn to Ultrasonic Pulse Velocity (UPV) testing or tomography. You can learn more about various types of concrete testing, here.
Total average cost of purchasing concrete scanning GPR and complementary equipment: $15,000 + training.
Your Equipment Is Only as Good as The Hands It’s In: Education & Training Costs for GPR
In order to properly gauge the scope of your GPR-related job, and understand how to employ GPR technology properly, you must undergo some sort of expert training and education.
Why do you need to be trained? The implications of a bad utility locate are serious, possibly leading to significant delays, financial losses, and could put lives in danger. As per the Common Ground Alliance, there are around 1,100 instances of utility damage and/or utility strikes each day, highlighting the critical need for top-tier training for GPR use. A basic online GPR course, costing around $600, provides only rudimentary training without any field practice, and does not certify you to meet the industry's minimal standards. The Level 1 NDT certification—viewed as the minimum standard—requires eight hours of classroom learning and 60 hours of field practice, costing approximately $1,000, with additional levels similarly priced.
Total cost for non-destructive testing (NDT) training for GPR: $1,000 - $5,000 per person.
The GPRS Difference – Elite Performance & Guaranteed Results
GPRS Project Managers are mandated to achieve the SIM Certification, which far surpasses the usual industry training standards. SIM, which stands for Subsurface Investigation Methodology, is the reason behind GPRS' impressive 99.8%+ accuracy rate in concrete scanning and underground utility locating in over 350,000 projects. The SIM Certification requires more than three times the education and field training expected by the industry for underground utility locating, necessitating 80 hours in the classroom and 320 hours in the field. This robust training ensures every GPRS Project Manager is an expert in locating with a variety of tools, including GPR and EM, enabling them to efficiently tackle even the most complicated locates.
Unless you’re planning to start your own concrete scanning or utility locating company and are willing to invest the time, money, and effort to become fully cross-trained among GPR’s various applications, and the complementary technologies you may need to get a complete utility locate or concrete scan, it is far more cost effective and less risky to employ a professional GPR company. In almost every case, hiring a company like GPRS also proves to be significantly less expensive and more accurate.
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