Frequently Asked Questions

Ground penetrating radar is a technology that uses radar pulses to create images underground. It is also known as GPR, ground radar, subsurface scanning, radar, or ground probing radar. Radar is also used for utility locating and archaeology purposes. It can penetrate up to 100 feet, depending on the antenna used. Depending on the soil type and moisture level, a typical utility application configuration will go 10 – 15 ft deep in scanning. Radar can be highly accurate at location, while identifying underground objects requires experience and skill.

GPR works by sending a tiny pulse of energy into a material and recording the strength and the time required to return any reflected signal. A series of pulses over a single area make up a scan. Reflections are produced whenever the energy pulse enters a material with different electrical conduction properties or dielectric permittivity from the material it left. The strength, or amplitude, of the reflection, is determined by the contrast in the dielectric constants and conductivities of the two materials. This means that a pulse that moves from dry sand (dielectric of 5) to wet sand (dielectric of 30) will produce a very strong reflection, while moving from dry sand (5) to limestone (7) will produce a relatively weak reflection.

While some of the GPR energy pulse is reflected to the antenna, energy travels through the material until it either dissipates (attenuates) or the GPR control unit has closed its time window. The signal attenuation rate varies widely and is dependent on the material's properties through which the pulse is passing.

A Ground-Penetrating Radar can be used in freshwater. However, it cannot be used in places where salt water is present. It can also be used in snow and ice. Depending on the site conditions, high moisture levels can hurt our ability to provide accurate location data.

While some of the GPR energy pulse is reflected to the antenna, energy travels through the material until it either dissipates (attenuates) or the GPR control unit has closed its time window. The signal attenuation rate varies widely and depends on the material's properties through which the pulse passes.

The duration of a GPR scan depends on various factors, such as the area's size, the structure's complexity, and the desired level of detail. However, GPR scans are generally quick and efficient, with smaller areas often taking just a fraction of the time to complete compared to X-rays. Our experienced team utilizes advanced GPR technology to ensure timely and accurate scanning, helping you proceed with your project without unnecessary delays.

Absolutely! GPR is highly versatile and can provide depth information for new concrete installations and existing structures. Whether you need to locate rebar or post tension cables in freshly poured concrete or assess the depth of objects within an established structure, GPR can deliver reliable depth measurements. This versatility makes GPR an invaluable tool for various construction projects, regardless of the concrete stage.

Irrigation main lines often have wires and can be easily located by wires. However, irrigation lateral lines require more in-depth locating. Typically, it is not cost-effective to locate them compared to the cost to repair them if they are hit (e.g., 50-cent pipe fitting vs. locate cost).

Many people wonder whether it is safe to use GPR equipment. The answer is yes. Ground-penetrating radar may sound dangerous, but it is actually a safe technique. The radar only emits about one percent of the power that the average cell phone emits.

Ground-penetrating radar does not identify utilities. The operator and their interpretation of the data presented can identify potential anomalies in the ground. Based on additional information about the site, we can draw conclusions about what is underground.

Members of our trained team can identify the type of utility by tracing it using Utility Locate Equipment other than GPR. They can also identify features such as control boxes, valves, and meters. However, if the locators cannot directly connect to the specific utility, they may not be able to identify it conclusively.

GPR is generally used to scan subsurface anomalies. First, our team can determine what is normal in a specific area, and then our team can determine what is not normal. Abnormal areas are referred to as anomalies. Depending on the scope of the job, these anomalies could be anything from unknown graves to tunnels. They may also be environmental hazards such as buried tanks or explosives.

WOOD Inspection Services is dedicated to subsurface locating for private utility projects and concrete scanning. We pride ourselves on being focused on the customer and providing as much information as we can to our clients. With decades of experience on various job sites and applications (empty voids and sinkholes to concrete structures), we use our skills and the latest technology to reveal the underground. We will be honest about what services you need, even if that means we don’t provide them.

Yes, Wood Inspection Services is available for weekend and emergency on-site inspections at an extra cost. The fees vary based on the service required. Contact us with any questions about work outside our regular working hours.

GPR equipment transmits and receives electromagnetic energy. That is why it is a good idea to turn off cell phones, pagers and two-way radios should not be used around a GPR. Electromagnetic radiation can interfere with the ground penetration radar signal. If one has to use these devices, then they should be kept at least 10 feet away from the GPR equipment.