Water repellency requirements for geomembranes

Geomembranes are used extensively as moisture barriers for the containment of water and the control of moisture movements in soils. As such, it is essential to establish their relevant property requirements, in particular, those dealing with water repellency. Two water repellency properties govern the selection of a suitable geomembrane - wetting pressure and permeance. Wetting pressure governs the mode of moisture flow through the geomembrane (liquid or vapor) while permeance governs the rate of moisture flow (vapor). These water repellency requirements are examined and design equations presented which allow for controlled migration of vapor through the geomembrane. The practical implications governing the water repellency requirements for geomembranes are also discussed.