Electrical resistivity survey Electromagnetic conductivity

Ground Penetrating Radar (GPR), Electromagnetic Conductivity (EM), Electrical Resistivity Surveys, or Seismic Surveys. 

Inducing an electromagnetic field eliminates the need for an electrode array and, therefore, the electromagnetic field method is a more rapid tool for surveying. The elimination of electrodes to measure electrical properties of subsurface materials also enables electromagnetic surveys to be conducted in many areas where resistivity surveys cannot be considered (i.e. pavement areas, very dry sandy soils, frozen ground, railroad tracks, etc.). Electromagnetic conductivity surveys may also be used to produce rapid continuous profiles up to depths of 15 meters. 

Electrical resistivity measurements were also taken at 28 locations selected across the site to verify the data collected by electromagnetic methods. The data obtained was in agreement with the results of the electromagnetic conductivity survey. 

Electromagnetic (EM) Conductivity Measures the electrical conductivity of materials in microohms over a range of depths determined by the spacing and orientation of the transmitter and receiver coils, and the nature of the earth materials. Delineates areas of soil and groundwater contamination and the depth to bedrock or buried objects. Surveys to depths of SO to 100 ft are possible. Power lines, underground cables, transformers and other electrical sources severely distort the measurements. Low resistivities of surficial materials makes interpretation difficult. The top layers act as a shunt to the introduction of energy info lower layers. Capabilities for defining the variation of resistivity with depth are limited. In cases where the desired result is to map a contaminated plume in a sand layer beneath a surficial clayey soil in an area of cultural interference, or where chemicals have been spilled on the surface, or where clay soils are present it is probably not worth the effort to conduct the survey. 

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