| The Waxman Smits model suggests a non-linear relationship between the bulk resistivity of formations containing clay minerals and the resistivity of the fluid in the pores. This model is applied to a site involving fine-grained soil deposits containing approximately 25% clay, and where shallow groundwater has been impacted by industrial activities. Quantitative estimates of pore water electrical conductivity from bulk electrical conductivity measurements in glacial till deposits can be made using a reasonable fit of data routinely collected during environmental site investigations. Data required to apply the Waxman Smits model includes: pore water electrical conductivity, cation exchange capacity, density and porosity of site soils, and interpreted electrical resistivity survey data. The most sensitive model parameters are: porosity, cation exchange capacity, cementation factor, and degree of saturation. Calibration and use of this model on sites with a history of subsurface disturbance or geologic heterogeneity is difficult. |
