EFFECTIVENESS OF ELECTRICAL RESISTIVITY IN DELINEATING LEACHATE PLUME AT THE FORMER SHELBY COUNTY LANDFILL IN MEMPHIS, TENNESSEE
Identification of ground-water contamination is commonly achieved by chemical analysis of water sampled from monitoring wells; however, the distribution of monitoring wells does not always satisfactorily reflect the extent of ground-water contamination. This pilot study gauged the effectiveness of an electrical resistivity survey to identify the extent of contamination in a shallow aquifer beneath a landfill. Seven resistivity lines were completed north of the landfill using a SuperSting© R8/IP with an array of 28 electrodes at 10 meter spacing. Historical geochemical data and geologic logs were used to constrain resistivity data collected and produce a two-dimension cross-section of the subsurface. Preliminary results of the resistivity survey indicate impacted ground water in the shallow aquifer immediately north of the landfill, which is consistent with elevated specific conductance values and poor water quality observed in monitoring wells in the same vicinity during the July 2011 ground-water sampling event. Application of a full-scale resistivity survey may also improve the definition of the window orientation and lithology.