Determlning and Mapplng DNAPL Saturation Values from Noninvasive GPR Measurements

With the possible application to fluid-flow modeling, saturation values of dense nonaqueous phase liquids(DNAPLs) may be determined and mapped through the use of measurements acquited by noninvasive groundpenetrating radar (GPR). In 1991, a controlled injection of perchloroethylene @CE), a common DNAPL, wasperformed by the University of Waterloo into an isolated, water-saturated, sandy aquifer at Canadian Forces BaseBorden. One of the geophysical techniques employed by the U. S. Geological Survey to monitor the location andmigration of the subsequent plume was 5OOMHz surface GPR acquited on a one meter grid spacing across thenine meter by nine meter cell over a period of 340 hours. This paper describes how full-waveform GPR modelingof these data for relative dielectric permittivity versus depth may be used to calculate and map spatial distributions ofDNAPL saturation over time using recursive solutions of the Bmggeman-Hark-Sen (BHS) mixing formula.