We use the latest ground penetrating technology to provide critical information on utilities, materials, and other potential obstructions within, or under existing structures. Fast and reliable, GPRS provides data in both two- and three-dimensions without delivering any radiation. All of our equipment is registered and meets all standard FCC regulations.
Utilizing GPR reduces risk and cost, and promotes a safe work environment by providing non-destructive testing for locating materials (such materials commonly include concrete, plastic, metal, and steel, although our equipment can be used in a variety of other applications). Our client base includes hospitals, universities, surveyors, engineers, homeowners, contractors, environmental firms, and excavators.
Concrete Scanning & Utility Locating
Using Ground Penetrating Radar To Perform Concrete Imaging: Common Questions Answered
GPRS continues to see an increase in the use of ground penetrating radar to scan or image concrete slabs. Concrete imaging with ground penetrating radar is typically a very successful process yield results that ensure construction, cutting, drilling, etc. can continue without impact to the facility or project. We wanted to take a moment and discuss some common questions with regards to using GPR to scan concrete.
1. Often we are asked if ground penetrating radar can scan/image concrete slab-on-grade. The answer, simply, is yes. This question often comes from someone who is familiar with concrete “X-Raying”. While X-Raying concrete is still a valid technique for determining the location of reinforcing steel it is limited to elevated concrete slabs only. This is because you need to have access to both sides of the concrete to perform an x-ray. One side for the radioactive isotope and the other for the film. Ground penetrating radar is a completely different technology.
GPR utilizes and electromagnetic pulse to determine the reflective values of objects in the concrete. It is a simple send/receive technology. The radar sends an electromagnetic pulse from the surface and the reflections are received, again, at the surface. Thus, it only needs access to one side of the concrete. This fact makes it ideal for scanning concrete slab-on-grade applications.
2. Can Ground Penetrating Radar determine the difference between rebar, post tension cables, electrical conduits, etc.? This is a more complicated answer than the question above. While the technology (ground penetrating radar) does not determine what type of object/anomaly is being located we (the technicians) are very good at determining what type of reinforcing steel or electrical conduit is present. Take the photo below for example…
This photo shows a typical post tension cable mark out. We are able to locate, using the radar, all of the reinforcing steel anomalies. We then mark the findings on the concrete and are quickly able to determine, based on the pattern, what each marking indicates. Most often when something is on an angle through a square layout it will be a conduit. Further, you will have a typical rebar pattern with 12-18” centers. Post tension cables tend to be spaced further apart depending on the design of the building and whether they are banded or uniform tendons.
As you can see, the real answer to the question of whether ground penetrating radar can tell the difference between rebar, post tension cables, electrical conduits, etc. is YES and NO. The radar can’t but an experienced technician can interpret the data the radar discovers to provide you with an accurate representation of what is in the concrete.
3. How Accurate is Ground Penetrating Radar with marking anomalies in concrete? We have found that our typical accuracy is +/- ¼” to the center of the object (conduit, post tension cables, rebar) being located. Additionally, GPR can also inform you of the depth of the object in the concrete. We have found that our typically accuracy when locating the depth of an object embedded in concrete is +/- 10%.
This photo, again, shows a typical elevated concrete slab layout after we finish scanning. You can see that all rebar, post tension cable, and walker duct were marked on this layout. Because the radar’s accuracy is so high we can confidently tell contractors where they are able to drill without the risk of hitting any of the objects shown in the picture. For safety and caution we instruct all contractors to stay 1 inch of any line they do not want to hit. This allows for bar/tendon thickness.
4. Is there any health risks associated with Ground Penetrating Radar? Again, this question often stems from someone who has experience with x-raying concrete. As mentioned, x-ray continues to be a viable and accurate testing method for mapping objects in concrete but it does come with an inherent health risk. Most x-ray companies recommend that you clear the area where the “shot” is taking place.
Because the typical power output of a radar system is less than the cell phone most of us carry in our pocket it is completely SAFE to work around. There is NO concern over health risks of our technicians, your employees/team members, or other tenants in the building. Further, the radar does not emit sound and operates almost silently so there is no noise disruption.
5. How long does it take to scan an area for core drilling? Ground penetrating radar is an extremely efficient and fast technology able to scan large areas in with ease. Our standard layout for a typical core drilling location is 2’x2’ in size. It will likely take us about 10 minutes to scan and mark this area.
6. Is there a reason why I should hire GPRS and not buy my own equipment? This is a GREAT question and one that we are getting more frequently. While the cost of a GPR system may seem inconsequential on a large project there is more to concrete imaging than just having the equipment. We truly believe that half of the job involves knowing how to read the GPR data screen. The other half is being able to determine what the data is telling you.
This comes through experience. Only through experience can we interpret the data on the screen to tell you what anomaly indicates rebar, post tension cables, or electrical conduit. Only through experience and industry knowledge can we take our construction information and apply it to the data on we see after imaging the concrete and provide accurate answers to your questions.
There are many other questions that we are asked with reference to scanning concrete. Those questions involve other aspects of our scanning process including; can you locate voids below concrete? Can you scan walls or ceilings? Can you locate rebar in a CMU Block wall? For answers to these and other questions you can visit our FAQ page on the website or, better, call your local technician who would be happy to answer any and all questions as well as provide you with pricing and availability for service.
Why Should You Choose Ground Penetrating Radar For YOUR Project
EVERY project fights to maintain its projected and estimated schedule. Contractors spend much of their time in project scheduling meetings, making schedule revisions, and communicating with owners about changes to the schedule. The last several years have been a struggle in the construction industry and more than ever before the schedule can have a direct impact on the bottom line.
One of the biggest schedule busters is the “unforeseen” or “unpredictable”. This could be because a piece of equipment has a mechanical issue, the factory cannot supply the necessary building materials in a timely fashion, a utility is cut or damaged during excavation, or an electrical conduit was severed while cutting the concrete slab. While the “unforeseen” will always be…well…unforeseen Ground Penetrating Radar Systems can help to keep your project on schedule.
We help by providing a utility locating service that is one of the most accurate and dependable non-destructive testing methods for mapping underground obstructions prior to excavation. We help by locating embedments in concrete such as post tension cables and electrical conduit prior to core drilling. We help by mapping electrical conduits found just below the concrete slab-on-grade prior to saw cutting. Not only are these obstructions located but depth indications can also be provided to give you a distinct picture of where the objects are found both horizontally and vertically.
Lastly, these findings can be sketched, mapped, plotted, and reported in many different ways. These methods can help you pre-plan your dig to ensure that you take the path of least resistance. They can help you design a saw cut path that keeps you away from the electrical conduits and other strike hazards in or just below the concrete.
From start to finish the ability of ground penetrating radar to locate the schedule conflicts you can’t predict is phenomenal. Let us help you keep you project on schedule by provide expert locating services and concrete imaging for your concerns about what lies below the surface.
In as much as the disruption of the project schedule can cause a direct impact on the bottom line unforeseen repairs can cause equal impact. Material and repair cost for a damaged fiber optic cable can range for thousands to tens of thousands of dollars. The budget impact isn’t simply from the material and expertise needed to the repair the underground utility but to pay for the service interruption to local business and other entities which rely on that utility for day-to-day operations. Most contractors have heard the troubling stories of service interruptions whose “interrupt cost” put the at fault contractor out of business. Again, the “unforeseen” and “unpredictable” can dictate the overall profitability of the project.
Ground penetrating radar can also provide untold cost savings by locating the fiber optic line before the dig begins. It can help determine what main power feed is located below the concrete and ensure that there is zero downtime for the facility and owner of your project. By simply taking a few extra hours before the digging or cutting begin to have the area scanned, imaged, and inspected by an expert technician could represent tens of thousands of dollars in cost savings.
3. Knowledge and Information
The location of underground utilities or embedded objects in concrete doesn’t just help keep a project on schedule and under budget but it provides you with valuable information from which to make and adjust construction plans.
Ground Penetrating Radar Systems has been used on several occasions to minimize an environmental investigation area by locating the underground storage tank before the start of the project. GPR has been used to locate a sanitary sewer line prior to the contractor tying in to it. Instead of the utility repair company digging a 20’x20’ pit GPR has been used to locate the water line and shrink the dig area to a 5’x10’ area.
The knowledge and information that Ground Penetrating Radar Systems can provide is not just related to field markings or direct communication. GPRS is capable of putting the field findings onto sketches, CAD files, and thru the use of 3D Laser Scanning, into BIM models. These outputs ensure that you are receiving information that will last. It ensures that all information needed to make future decisions, with reference to the areas where scanning and inspection has taken place in the past, are accurate and available in the time of need.
The schedule, budget, and information concerns, as discussed previously, lead to the mitigation of risk. Ultimately, having a method or procedure in place that limits your exposure and controls risk is a valuable asset. Having the ability to control cost limits the risk of losing money or profit on your construction project. Have the ability to determine the precise locating of underground utilities limits the risk of having a utility strike, injury, project delay, or repair.
We, at Ground Penetrating Radar Systems, are finding more and more frequently that this type of testing and inspection is being called for in project specifications. The specs are typically drafted, in a combined effort, between the project designers (engineers and architects) and owners. These parties are typically very concerned with scheduling, budgeting, and correct information with regards to their projects. They want to be sure they limit the amount of unforeseen circumstances that could impact those three crucial areas in the project construction process. Thus, they write specifications that require ground penetrating radar, utility locating, concrete imaging, etc. Why? The answer is simple; ultimately, they want to limit the risk on the project. Limiting risk allows for better planning, proper budgeting and more money on the bottom line.
Ground Penetrating Radar is another tool in their toolbox for helping to limit the risk associated with construction projects. Further, they want to know that all options have been exercised to limit these risks. Join them. Pick up the phone or shoot a quick email to the team at Ground Penetrating Radar Systems and let us tell you what information we can provide to your project that will help limit the overall risk and exposure you as the contractor/owner are carrying.
The #1 concern on construction projects in the 21st century has been safety; safety for the community where the project is being conducted, safety for the workers, tradesman, and contractors, and safety for those that occupy the project after its completion. The last several decades have seen an increase in OSHA standards and policies. Individual contractors are taking it on themselves to raise the bar even further than the aggressive OSHA standards and commit to injury free projects. There are many ways that these safety standards are being achieved; uncompromising project management, personal protective equipment, advancements in technology for the tools being used, project condition analysis, tagging procedures, etc. The list of improvements is seemingly endless.
Ground penetrating radar can be a part of your company’s commitment to safety. We have talked, previously, of the different ways that GPR can help determine the location of underground utilities or how it can image the concrete to determine where post tension cables are located. To date we have discussed them in terms of scheduling, budgeting, information, and risk. The concluding peace of mind that GPR can provide is that of the safety of those on your job site or in the community.
In many cases ground penetrating radar can be used to locate live electrical conduit or other hazardous utility lines prior to cutting, digging, or construction. This information will ensure that potentially unsafe utilities or obstructions below the surface are known prior to engaging in the work. Further, ground penetrating radar can be used to perform concrete imaging services there by informing you where post tension cables and other structurally dangerous embedments may be.
While there isn’t a technology, science, or procedure that can guarantee safety on a job site there are services that can be used to make the job safer. Consider ground penetrating radar the next time your project presents unknown issues or safety concerns. GPR may just be able to keep you on schedule, under budget while providing you valuable information that limits risk and keeps your project SAFE.
GPRS Aids Local Law Enforcement Officials in the Search for Human Remains
Ground penetrating radar is most commonly known for its utility locating ability or its capacity to find embedded objects in concrete. We at Ground Penetrating Radar Systems tend to spend our days looking for water lines and electrical conduits, performing concrete imaging, locating post tension cables, and searching out other objects such as underground storage tanks. However, there are additional uses for ground penetrating radar that are not as widely discussed: The science behind GPR makes it a great tool for grave/cemetery mapping as well as forensic investigations.
The regional branch of GPRS in Florida was contacted by a law enforcement office on the east coast of the state. The officers and detectives had reason to believe that a body had been buried in the backyard of a residence. However, they had been informed by the judge that they would not receive a search warrant without evidence that pointed more specifically to potential areas where the body might be buried. So, the office contacted GPRS of Florida and contracted our services to perform a forensic investigation.
We mobilized to the site and surveyed the entire yard on a tight grid pattern. The grid pattern was spaced in such a way as to ensure that the survey was accurate and complete. The survey revealed three potential “areas of concern," spots where the GPR technician believed further investigation was warranted. While still on site, the officers received permission to gently excavate the areas in question.
One of the three areas DID contain the body they were searching for. The law enforcement agency was very pleased with the results of the survey, and GPRS is glad to have been able to help serve justice in this matter.
As you can see, there are many uses for ground penetrating radar. You may not have a forensic investigation to perform, but you may need to locate a pipe or find a post tension cable. Consider hiring the most experienced GPR company around.
Ground Penetrating Radar Quick Links
GPRS Inc. provides service for the following applications:
Let me take this opportunity to provide a exemplory recommendation for Ground Penetrating Radar Systems, Inc. and the professional service they have delivered. Turner was the General Contractor for the Democratic National Convention in Denver Colorado. We utilized GPRS to ensure safe drilling areas in over 150 locations at the Pepsi Center through very congested floor slabs. The project schedule was extremely tight and the accuracy of the information provided was remarkably very sound. GPRS was instrumental in assisting in a very successful project for the entire design / build team. Turner has since and certainly will continue to use Ground Penetrating Radar Systems, Inc. prior to cutting into existing slabs and walls.
Turner Construction Company
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your local GPRS Inc. technician.
Penetrating Radar technology provides critical
information concerning anything that lies below the surface.
This technology has been used for a variety of scanning
purposes, but it is commonly used to determine the location
of underground utilities, rebar, post-tension
conduit and other impediments.
works in a fast and reliable manner. It is also
very safe, as it uses no radiation.
We are able to provide a 2
Dimensional and a 3 Dimensional image of the areas we
of our equipment is registered and meets all standard
Our Mission is to provide solutions to the critical problems our customers
face regarding the location of hidden elements in concrete and underground.