Geomembrane are plastic sheets used within soils as a waterproof barrier. Geomembranes do not always maintain close contact with the underlying material throughout their life. Problems may occur on the side slopes adjacent to open areas of water as a result of wind and wave action on any exposed portion of geomembrane. Wave action can tend to slightly lift the geomembrane and then slap it back down in a repetitive manner. If the geomembrane is directly in contact with the soil, this can cause loosening of the particles, which move down the slope underneath the geomembrane. Eventually, a cliff is formed at the water line together with a bulge below this level, which could excessively stress the geomembrane and the soil, preventing this form of erosion. In case of a localized tear or seam failure in the geomembrane, the geotextile helps to hold the soil in place, limiting propagation of failure. Although the primary role of the geotextile is often to separate the geomembrane from the soil, it may also act as a vent to release gas trapped or generated in the underlying soil, or reinforcement of, or support to, the geomembrane.
Heavy weight Nonwoven Geotextiles can cushion and protect geomembranes from damage by sharp objects, thereby minimizing the chances of leakage in the long-term. These fabrics enhance puncture, impact, and abrasion resistance, allowing landfill system construction and operation without fear of damaging critical lines. This function, although relatively simple, is a very large application area and one that is underrated due to the importance of protecting the vital fluid barrier. Nonwoven needle-punched geotextiles with mass per unit area greater than 10 oz/yd2 (350 g/m2) are commonly used.
