Frequently Asked Questions

About GPRS

Q: Why should I choose GPRS over a similar company?

A: GPRS is a leader in the field of subsurface scanning. Our focus on private utility locating and concrete scanning has enabled us to become highly specialized within these fields.

One key difference between GPRS and our competitors is the total area we are able to accurately scan within a given timespan. Rigorous training enables our Project Managers to work efficiently and meticulously to quickly provide you with the information you need.

When you contact GPRS to request a service, we put you in direct contact with a Project Manager local to your area. Their knowledge of the unique conditions that surround your project enables them to ask the right questions to determine if GPRS will be able to serve your project’s needs. Contact us today to experience the GPRS difference yourself.

Q: How quickly can you respond to an emergency need?

A: In most circumstances, we can have a project manager on your site within 24 hours.

Q: What is the farthest GPRS will travel to reach a site?

A: GPRS provides nationwide Ground Penetrating Radar services with offices in every major city from coast to coast. Simply put, we are willing to do what it takes to serve your project’s needs- including travel.

Q: Is GPRS available to work at night or on the weekend?

A: We, at GPRS, pride ourselves on customer service and our ability to meet your inflexible scheduling needs. We are willing to work nights and weekends, or any other time, in order to help you accomplish the goals of your project. Please contact your local GPRS representative for rates and schedule availability.

Q: What type of training do your project managers go through?

A. Each of our Project Managers goes through a two- to three-month training process. This includes two weeks at our Training Center, located at our corporate headquarters in Toledo, OH. The GPRS Training Center has a ~1,000 square foot test slab created to simulate nearly 90% of conditions encountered in the field. Trainings are led by our Director of Training and a partner- combined they have over 17 years of hands-on experience. Each trainee is paired with an experienced Project Manager until they have sufficiently demonstrated their technical expertise. This program enables the trainees to grow in knowledge and confidence while simultaneously allowing Project Managers the opportunity for career growth and advancement.

Q: What qualities set GPRS Team Members apart?

A: GPRS strongly believes that the key to our success is our incredible team. When hiring new team members GPRS looks for certain qualities which we feel set us apart from the competition. Our strong sense of integrity, proven competency in our field, and commitment to our customers are just a few of the qualities which make GPRS a cut above the rest.

Q: How does GPRS ensure quality of service?

A: GPRS focuses solely on the fields of utility locating and concrete scanning. All of our team members undergo a rigorous training program in order to ensure they are well prepared to meet your project’s needs. In order to ensure quality and accuracy, GPRS recently developed and began implementing SIM- subsurface investigation methodology. This is a comprehensive specification detailing training methods, equipment usage and means of minimizing error when performing subsurface investigations. This operating procedure was developed using our 18+ years of experience and data in the field of utility locating and concrete scanning.

Q: Does GPRS perform S.U.E. work?

A: Subsurface utility engineering (S.U.E.) is a method of reducing the risk and improving the accuracy of subsurface utility readings. It is broken down into four levels of quality, governed by ASCE Standard 38-02. GPRS is able to perform S.U.E. work in conjunction with other agencies, but does not currently provide a fully comprehensive in-house S.U.E. service. GPRS does not provide engineering services. If you need professional engineering services, please contact a professional engineer.

Q: What are your rates for different services?

A: Please visit our sales page to request a quote.

Q: Does GPRS purchase used equipment?

A: Yes, we buy used equipment from other GPR companies. Please call our corporate office at (419) 843-9804 and we would be happy to discuss equipment sales.GPRS uses only the best equipment. All of our units are carefully selected to serve the needs of the job in question. We routinely service and calibrate equipment to ensure the most accurate results for your project.

General Scanning

Q: What is ground penetrating radar (GPR)?

A: Ground penetrating radar is a detection method which uses radio waves to identify buried or hidden objects within a structure or beneath a surface. This non-destructive method uses antennas of varying strengths to transmit a signal into a surface. As the signal encounters different components within that surface, it is bounced back to a receiver at the surface. This action creates data which can be used by experienced GPRS Project Managers in order to determine the location of buried utilities and other subsurface features.

Q: How is GPR used?

A: GPR is used to identify the location of subsurface materials. GPRS uses this radar for utility locating and concrete scanning applications. Varying antenna strengths are used for different applications, depending on the type of material being scanned and how deep objects are buried.

Q: What type of GPR equipment is used?

A: GPRS uses a variety of ground penetrating radar and scanning tools according to a project’s needs. Our two most commonly used pieces of equipment are the concrete scanning antenna and the utility locating antenna. Read more about the different types of equipment we use here.

Q: Does GPR have any limitations?

A: GPR is extremely effective at locating subsurface utilities and othermaterials, however 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. GPRS Project Managers are skilled in determining if GPR is the right choice for you project. In the event that conditions are not suitable for GPR scanning, an alternative recommendation can be made.

Q: Is ground penetrating radar safe to use?

A: Ground penetrating radar (GPR) is a safe, non-invasive tool used in identifying subsurface objects. 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 the scan. Contact us with any questions regarding the safety of GPR usage- we would be happy to provide you with additional documentation.

Q: How can I determine if GPR is needed for my project?

A: Contact GPRS by phone or through our website and a local GPRS representative will be in touch with you as soon as possible. Our representatives and local Project Managers are skilled in assessing local conditions and can help you to figure out how GPR services can meet your needs.

Q: What far into the ground can GPR penetrate?

A: This answer depends on the type of application in which you are interested. For concrete scanning, the antenna can typically penetrate 18-24” into the ground. For private utility locating needs on grass, asphalt, or concrete the type of antenna used can generally penetrate up to 8', but can vary greatly depending on site conditions.

In certain situations, a larger antenna can be used for greater penetration. Please contact your local GPRS representative for more information on selecting the right GPR service for your project.

Q: How accurate are the results of ground penetrating radar?

A: GPR is extremely accurate! While accuracy is reliant upon various external factors such as ground and soil conditions, GPRS standards ensure that we are able to obtain the best results possible in each situation. Through past experience we have found that when using a concrete antenna for scanning, the accuracy is +/- ¼” to the center of the object being located and +/- ½” to the actual depth. When using a utility locating antenna for scanning, the accuracy is +/- 6” to the center of the object being located and +/- 10% to the actual depth.

The results of the concrete antenna are generally higher resolution, and therefore considered to produce better quality results. However the concrete antenna is not able to penetrate the ground as deeply as the utility locating antenna- it is critical to understand the benefits and limitations of both when performing scanning work.

GPRS Project Managers are skilled at assessing local conditions to determine if they will allow for correct GPR usage. Results are based on over 18 years of GPR experience.

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

A: GPR 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.

Q: Can GPR equipment be used to scan CMU walls?

A: Yes, GPR equipment can be used on concrete masonry unit (CMU) walls and structures. GPR can be used to determine the presence of grout and vertical rebar within the CMU structure.

Q: Can GPR equipment be used on vertical surfaces or ceilings?

A: Yes, GPR equipment 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.

Q: Can GPR be used to locate unmarked grave sites?

A: Yes, ground penetrating radar can be used to determine the location of unmarked graves for site planning purposes. We are able to locate most grave sites, even those that have experienced material decomposition.

Utility Locating

Q: Is GPRS able to distinguish between each type of underground utility which is located?

A: GPRS uses ground penetrating radar and other tools to locate and identify subsurface utilities. In most situations, we are able to locate the utility in question without any problems, although it is not always possible to identify what type of utility it is. When this happens we attempt to trace the utility to a valve, meter, control box, or other type of signifying marker in order to determine the type of utility that has been located. GPRS takes all possible steps in order to successfully locate and identify buried utilities.

Q: Can GPR be used to verify known measurements?

We are able to use GPR to cross-check the measured depth and location of a located utility with existing as-built plans in order to verify the accuracy of plans.

Q: Can you find PVC piping and other non-conductive utilities?

A: GPR scanning is extremely effective at locating all types of subsurface materials. While PVC and other non-conductive materials produce a weaker signal than conductive materials, GPRS Project Managers are skilled at identifying these signals in order to accurately locate buried utilities.

Q: What type of informational output is provided when locating utilities?

A: Our typical survey output is to flag and paint our findings directly on the surface. This is the most accurate form of marking when excavation is expected to commence within a few days of service.

GPRS also uses global positioning system (GPS) to collect data points of findings. This data can be used to generate a plan, Google Earth image, or CAD file to permanently preserve findings for future use. GPRS does not provide land surveying services. If you need land surveying services, please contact a professional land surveyor. Please contact us to discuss pricing and marking options that your project may need.

Concrete Scanning

Q: Can GPR determine the difference between rebar and electrical conduit?

A: In most cases, ground penetrating radar can accurately be used to differentiate between rebar and electrical conduit, though the two materials produce similar readings. We have an extremely high success rate in identifying electrical conduits in supported slabs or in slabs-on-grade prior to saw cutting or core drilling.

Additionally, GPRS has the capability of using electromagnetic induction to determine the location of conduits in the concrete. If we are able to induce a tone onto the metal conduit we can locate it with pinpoint accuracy. We can also locate the conduit if it has “live” electrical current running through it.

The combined use of GPR and EM induction allows us to provide one of the most comprehensive and accurate conduit locating services available.

Q: How is GPR used to identify tendons vs. rebar in a post-tensioned slab?

A: In post-tensioned structures, we typically find one mat of support rebar near the base of the slab. This mat is generally consistently spaced and remains at a constant elevation. Post-tension cables are generally found above this support mat and “draped” throughout the rest of the structure. The elevation of the cable is usually high near the beams and column lines and drapes lower through the span between beams and column lines. Knowledge of these structural differences allows us to accurately differentiate between components. Our Project Managers will leave you feeling confident in the survey findings and in your ability to drill or cut without issue.

Disclaimer

GPRS does not conduct an investigation, analysis, or interpretation of soil composition, soil conditions, or geological or geophysical information. GPRS reports retrieved data and does NOT provide geophysical, geological, engineering, or land surveying services. Customer should contact a professional in those fields if such services are needed.

5 Cost Factors In Your Concrete Scanning Project

  1. Your project location and concrete imaging objective
  2. Type of concrete structure we are scanning – hollow core, post tension, slab-on-grade, etc.
  3. Amount, or quantity, of wire mesh, rebar and post-tension reinforcement suspected to be found in the scan area(s).
  4. Number of locations that need to be scanned and distance between them
  5. Whether a lift or scaffolding is available if scanning involves a concrete wall or ceiling