Mapping the Norman, Oklahoma, Landfill Contaminant Plume Using Electrical Geophysics

By Robert J. Bisdorf and Jeffrey E. Lucius

ABSTRACT

The lateral extent of the electrically conductive portion of the contaminant plume emanating from the Norman Landfill was mapped using electrical geophysical measurements. EM induction and DC resistivity methods measured the apparent electrical resistivity of the subsurface. Both methods show an area of low resistivity indicating poor ground water quality in the alluvium, presumably due to leachate from the Norman Landfill. This area extends from the southwest side of the main landfill mound toward the Canadian River for no more than about 200 meters. Cross section and depth-slice maps made from the interpretation of the DC resistivity soundings and maps of measured resistivity from the EM measurements illustrate the lateral extent of the landfill contamination and show that the contaminate plume, which is about 9m thick, does not appear to extend into the bedrock. The EM induction method proved to be an easy and efficient procedure for rapidly determining the lateral extent of the leachate plume. The DC resistivity method, although more time consuming, provided better vertical resolution of the resistivity distribution.