Synthetic Mining Solutions for Laboratory Testing of Geosynthetic Clay Liners

Geosynthetic clay liners (GCLs) are increasingly used in engineering and environmental applications that include nonstandard solution chemistry. Long-term exposure of geosynthetics to nonstandard solutions in containment facilities, such as heap leach pads, municipal and hazardous solid waste containment, and so on, may cause degradation of bentonite and polymeric components and alter the hydraulic and mechanical properties of GCLs. Leachate collected from full-scale containment facilities has commonly been used in previous studies for field-focused GCL-related experiments. However, due to problems associated with using actual leachates, representative synthetic solutions often are used. A step-by-step procedure for the design, preparation, and verification of representative synthetic mining solutions for laboratory testing on GCLs is described in this study. Recipes for creating three synthetic mining solutions to simulate gold, copper, and bauxite process solutions are presented. The procedure for solution development and prepared solutions were verified via comparison of measured to calculated metals concentrations, which yield concentration differences less than 8% for all three synthetic process solutions.