Uses for Dam Liners and Geomembranes

Geomembrane – any membrane that is impermeable or very low permeable synthetic membrane liner or barrier. Used with soils, rocks or other geotechnical material in order stop the migration of fluids (or gases in some cases) from the containment area. The geomembrane is used either as a containment barrier, a lining or as capping to minimise evaporation. Dam Liners and pond liners are two very common examples, however liners have much wider uses in commercial and mining industries such as landfill sites (both as a liner and as a cap), evaporation ponds, rain water harvesting etc.

Geomembranes are typically made from flat polymer sheets, usually EPDM, PVC, Polyethylene (high and low) or Polypropylene. These are the most common materials however are other compounds and mixes are sometimes utilised.

In the case of dam liners, the use is a last resort for farm dams where other methods of sealing the dam have either failed or are not practical. Dams are typically built on clay based soil and then sealed with a clay like bentonite, sodium or gypsum. However whenever soil conditions are not ideal or where ground movement can occur, it is often necessary to consider a dam liner.

Farm dams, which only ever collected water for livestock and irrigation are about the only types of dams that typically don’t use a liner. All other uses require a geomembrane liner and is considered mandatory, especially for mining and commercial applications, In fact anywhere where leeching of chemicals or untreated water into the environment is unacceptable.

Geomembranes are not only used underneath but can be used over the top as a cap. Capping can prevent both rain and other elements from entering the storage area. This is used extensively in landfill applications and material selection will depend on the base liner or the cap which are under different loads and different weather conditions.