Water Diffusion Through Geomembranes Under Hydraulic Pressure

A theoretical analysis of fluid transport mechanisms through geomembranes is presented. Diffusion and permeation tests that use a volumetric and radioactive tracer method to measure the amount of water flow through geomembrane specimens give an understanding of the mechanism of water transport through the following different types of geomembranes: high density polyethylene (HDPE), polyvinyl chloride (PVC), and bituminous geomembranes. The use of the hydraulic permeation test and hydraulic conductivity (as defined by Darcy's law) to characterize geomembrane permeability are discussed. It appears that the transport of water through the tested geomembranes is mainly a function of the hydrophobic behavior of the geomembranes but not of the pressure gradient. Therefore, hydraulic conductivity as defined by Darcy's law is unable to describe water transport through geomembranes.