Ground Penetrating Radar Explained
Ground-penetrating radar (GPR) is a geophysical locating method frequently used by SoftDig® that utilizes radiofrequency waves to produce images of the subsurface, allowing us to pinpoint the location of underground utilities, UST’s and a multitude of other phenomenon. This nondestructive method uses radiofrequencies within the microwave band, which detect reflected signals after they come into contact with subsurface structures or changes in soil composition.
What You May Use GPR For
SoftDig’s GPR applications are set in a variety of media, including rock, soil, pavements and structures. SoftDig® utilizes single frequency GPR units to detect simple utility lines up to depths of about 10 ft., multi frequency 3D units for congested areas, UST Investigations and geological studies and lastly, high frequency units that specialize in concrete slab inspections and structural elements in concrete floor and wall slabs up to a maximum thickness of 20 inches.
Understanding Exactly How GPR Works
SoftDig’s array of GPR units emits radio waves from a transmitter, from the low end of 250 MHz (for deep inspections) to 1.6 GHz (for shallow concrete slab inspections into the ground. Once these waves encounter a buried object or a boundary between materials having different dielectric constants, it may be reflected or refracted or scattered back to the surface. A receiving antenna on the unit can then record the variations in the return signal. The principals involved are similar to seismology, except that electromagnetic energy is used instead of acoustic energy, and energy may be reflected at boundaries where subsurface electrical properties change rather than subsurface mechanical properties as is the case with seismic energy.
GPR does not work in all conditions, and can provide false readings especially in areas with high salt content in the soil, such as coastal areas, and tightly packed clay soils and rocks can prevent locating of utilities with GPR.
Why You Should Use SoftDig® for Your GPR Services
Having performed thousands of GPR investigations, SoftDig® continues to exceed industry standards for accuracy, integrity and professionalism. We’ve applied our expertise in GPR technologies across a broad spectrum of industries, working on high-profile projects delivering detailed results on every project, large and small.
Services and GPR Applications
- Utility locating and mapping (metallic and non-metallic)
- Underground storage tank (UST) delineation
- Septic system (tanks and leach field), well, cistern and pipe locating
- Concrete thickness verification and rebar mapping (location, size, and spacing)
- Structural deficiency identification (sub-base settlement, voids, rebar wear and corrosion)
- Ahead of coring mark-out of construction elements and embedment
- Archeological feature delineation (foundations, roadbeds, privies, wells)
- Cemetery grave mapping
- Geologic feature detection (bedrock, karst, sinkhole and void formations)
- Environmental concerns (landfill boundaries, overburden thickness, historic fill, drum piles)
- Verification of paving material thickness
- Pipeline leak locating