Performance of three GCLs used for covering gold mine tailings for 4 years under field and laboratory exposure conditions

ABSTRACT: The performance of geosynthetic clay liners (GCLs) above arsenic-rich gold mine tailings was investigated by the construction of a test cover comprised of three GCL products placed above the tailings at an abandoned gold mine in Nova Scotia, Canada. In parallel research, the performance of the three commercially available GCLs was assessed based on a series of laboratory column experiments. Of the three needle-punched GCLs tested, one has untreated Wyoming bentonite and a woven carrier geotextile; the second has a polymer-enhanced Wyoming bentonite and a scrim-reinforced nonwoven carrier geotextile, and the third has a polymer-enhanced Wyoming bentonite and woven carrier geotextile coated by a thin polypropylene geofilm. After 4 years of exposure in the field and laboratory, the bentonite structure of all exhumed GCLs appeared to be well hydrated with no visible cracks provided that the cover soil thickness was ≥ 0.7 m. The GCL with untreated bentonite exhibited the highest reduction in the exch...