Geosynthetic Clay Liners (GCLs) are high performance environmental liners comprised of a layer of low-permeability sodium bentonite combined with geosynthetic carriers, such as woven and/or nonwoven geotextiles, and in some cases polymer geomembranes. GCLs have been proven to provide better engineered performance and durability than several feet of compacted clay, with a total composite thickness of less than one quarter of an inch.