RESISTIVITY/CONDUCTIVITY ANOMALIES AT THE NORMAN, OKLAHOMA LANDFILL SITE

A resistivity survey was carried out between the Months of April and June 2002 at a landfill site near Norman, Oklahoma. The essence was to determine the extent of migration of the leachate plume emanating from the landfill, and flowing downgradient toward the Canadian River. This plume has contaminated a part of the alluvial aquifer that underlies the landfill site. A total of five profiles, each covering a length of 135 m, were surveyed using a combination of Dipole-dipole, Wenner, and Wenner-Schlumberger electrode configurations on each profile. Three of the profiles were oriented in an E-W direction and placed 150 m from each other, covering a total distance of about 350 m downgradient from the landfill. The remaining two profiles ran N-S. As a control measure, electrical conductivity logging was performed on selected portions along each profile using the Geoprobe conductivity tool. The EC logs gave a good picture of the lithologic units that constitutes the aquifer. Two- dimensional modeling of the resistivity data was done using the RES2DINV software. The resistivity anomalies generated correlated well with the EC logs. Thus it was possible to delineate both the lateral and vertical extent of the leachate plume.