The permeability of soils with organic fluids

Permeability measurements, using a consolidometer, were made for kaolinite, montmorillonite, and a clay-rich soil (the Lockport clay) with a variety of organic liquids and water as permeants. These data, along with selected values from the literature, were used to evaluate several theories that have been proposed as explanations for the general observation that permeabilities of clay soils with organic fluids as the permeants are higher than with water as the permeant. Of the several obvious differences in physical properties between water and organic liquids (e.g., dielectric constant, viscosity, dipole moment, specific gravity, and surface tension), only the dielectric constant provided a consistent correlation with the permeabilities used in this study. The permeabilities for the organic chemicals used in this study can be predicted using the measured permeability for the soil with water as the permeant and the dielectric constant of the organic by way of an exponential equation. For mixtures of acetone-water and methanol-water, the permeabilities did not vary linearly with the composition; the permeabilities remained close to values for pure water until approximately 70% (by volume) of the fluid was organic. Key words: permeability, organics, dielectric constant, soils.