Geosynthetic Clay Liner (GCL) is a factory-manufactured hydraulic barrier comprising a layer of natural sodium bentonite encapsulated between two geotextiles, mechanically bonded by needle punching or stitching. Upon hydration, the bentonite swells to form a very low-permeability barrier, providing effective seepage control and containment. This type of GCL is widely used in landfill base and capping systems, ponds, lagoons, and environmental protection work, offering consistent performance, ease of installation, and reduced thickness compared to compacted clay liners.