Frequently Asked Questions

GPR works by sending a tiny pulse of energy into a material and recording the strength and the time required for the return of any reflected signal. A series of pulses over a single area make up what is called a scan. Reflections are produced whenever the energy pulse enters into 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 which 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 back to the antenna, energy also keeps traveling through the material until it either dissipates (attenuates) or the GPR control unit has closed its time window. The rate of signal attenuation varies widely and is dependent on the properties of the material 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 levels of moisture can have a negative impact on our ability to provide accurate locate data.

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 vs the cost to repair them if they are hit (i.e. 50 cent pipe fitting vs locate cost).

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

Ground Penetrating Radar itself does not identify utilities. It is the operator and their interpretation of the data presented that can identify potential anomalies in the ground. Based on additional information about the site, we can draw conclusions as to what is underground.

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