Complementarity or equivalence of natural and synthetic materials for the waterproofing of landfills?

Abstract

The French regulation concerning municipal waste storage defines materials to be used to insure watertightness of landfills. It also allows replacing these materials by others, providing these are shown to be equivalent and give the same security considering water resource pollution risks. Different waterproofing materials and mainly geomembranes and geosynthetic clay liners are presented together with their advantages and disadvantages when used at the bottom of landfills. Equivalency is then discussed, based on different research results. Two comparisons are made: the first between clay and geosynthetic clay liner, and the second between geomembrane and clayey barriers. It is shown that equivalency is not demonstrated yet. Indeed, it seems that at present, based on scientific evidences, materials composing barriers as defined by the regulation cannot be replaced by other materials.