ABSTRACT
The selection of a geomembrane product depends on its application in the waste containment facility, whether as a primary or secondary base liner, or as a liner in the final cover. Factors to consider when selecting a geomembrane for these applications are listed in Table 13.1. In addition to adequate material strength, flexibility and puncture resistance (i.e., to minimize the development of small holes and tears), it is also important for all applications that the geomembranes have sufficient durability. Durability requirements depend on the exposure conditions. Resistance to stress cracking, a brittle failure mechanism manifest by semi-crystalline polymers as discussed in Section 13.2.2, is an important durability issue for all applications. Oxidation will lead to breakdown of the polymer and eventually failure of the geomembrane. Thus, oxidative resistance is very important for all liner applications, including secondary liners which have the potential to be exposed to both atmospheric oxygen in the secondary leachate collection system and leachate, and which require a long service life. Chemical
resistance in contact with leachate (see Section 13.3) is very important for primary liners, and UV resistance may be very important for cover geomembranes.
