Geosynthetic clay liners: An effective and efficient solution Waste rock and overburden stacked at a mine site. The high-density polyethylene The GCL is comprised of two geotextiles that are needlepunched together, encapsulating a layer of sodium bentonite clay between them. (HDPE) geomembrane liner must be capable of withstanding the excessive weight of ore, the continuous application of corrosive chemicals, and harsh weather conditions over the long term. The HDPE liner thickness is typically between 60 and 80 mils (1.5 and 2 mm). The liner must have no gaps, holes or areas of potential failure. Since a heap leach pad is a process component, like all process components at a mine site, the pad cannot be put into use until the Nevada Division of Environmental Protection-Bureau of Mining Regulation and Reclamation has reviewed and approved a detailed " as-built " report prepared by a Nevada licensed and registered professional 30 Geosynthetics | April May 2023 engineer showing that the pond was constructed properly and has been tested to ensure that it will not leak to the environment during and after active operations. Challenge The customer's heap leach pad required 1 foot (30 cm) of low permeability clay soil beneath the geomembrane. Due to sourcing problems, the mine owner could not acquire enough clay-historically used at the site-of suitable reliability to use for the compacted layer/prepared surface under the HDPE geomembrane liner. The on-site quantity and rate of production would not allow completion of the heap leach pad on time.