Electrical Resistivity

Electrical resistivity testing is the answer to a wide range of subsurface problems and objectives, and is becoming a logical, reliable tool for everyday use in engineering applications.

The electrical resistivity survey is based on the principle that the earth material being tested acts as a resistor in a circuit. After inducing an electrical current into the ground, we measure the ability of that material to resist the current. Since various earth materials exhibit characteristic resistivity values, they can be distinguished using this method. Factors that affect the resistivity of earth materials include degree of saturation, porosity, pore-fluid content, temperature, salinity, and thicknesses of clay or sand layers. Applications of the electrical resistivity method include locating aquifers, saltwater intrusions, and other groundwater contamination problems. We can also characterize bedrock by locating weathered zones, fractures, and voids attributed to solution activity, or determine depth to bedrock, and thickness of clay or sand layers. Electrical resistivity can also aid in evaluating soils for corrosively or their potential grounding capabilities.