This procedure, which uses Audio Frequency Domain Magnetics (AFDM), begins by charging the groundwater site with a low voltage, low amperage, high frequency electrical current. As the current moves through the groundwater, it emits a magnetic field whose size, shape, magnitude and direction are characteristic of the surrounding aqueous system (Biot-Savart Law). This field is then read at the surface by a specially tuned receiver. The data thus generated can be used to create both two-dimensional maps and three-dimensional models which indicate the attributes of the subsurface water network, including potential flow paths.
The images created by this process highlight those locations where the electrical current has concentrated. Because electricity concentrates in areas of highest conductivity, it is reasonable to infer that either these highlighted locations contain relatively large quantities of water or relatively high level of Total Dissolved Solids (TDS). Since TDS levels often correspond to the prevalence of certain contaminants, this feature of the AFDM investigation enhances its suitability for the characterization of contaminated groundwater sites and the identification of pollution plumes.
This technology has recently been deployed in a variety of settings, from ecologically sensitive environments in northern
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