Field and laboratory investigation of factors affecting GCL performance in the Antarctic environment

Performance indicators of geosynthetic clay liners (GCLs) exposed to the Antarctic environment were assessed using field and laboratory methods. Barrier properties of the GCLs were not impacted by the field conditions and exhumed hydraulic conductivities with respect to tap water ranged from 0.4 x 10-11 to 12 x 10-11 m/s, compared to 5 x 10-11 m/s (virgin) and from 2.1 x 10-11 to 8.8 x 10-11 m/s for a synthetic leachate, compared to 2.5 x 10-11 to 7.6 x 10-11 m/s for virgin specimens. The self-healing ability of bentonite remained intact despite environmental exposure as evidenced by X-ray radiographs. Using a test plot to evaluate GCL hydration with the major determinant of hydration was identified as proximity to meltwater flow. However, a finer subgrade (D60 = 5-7 mm) increased average and peak GCL moisture contents in areas not inundated with meltwater and resulted in less deformation than a coarse subgrade (D60 > 16 mm). Additionally, X-ray radiographs showed increased self-healing in monitoring specimens overlying fine subgrades. Environmental exposure (e.g., temperature cycling and dehydration/rehydration) did not affect the hydraulic conductivity of test plot specimens (1.1 x 10-11 to 8.5 x 10-11 m/s) compared to the virgin GCL (6.7 x 10-11 m/s) with respect to tap water, and minimal cation exchange had occurred.