A 10-year study of HDPE geomembrane longevity in contact with low pH solutions

The long-term performance of a high-density polyethylene geomembrane (GMB) immersed in acidic solutions is assessed over a 10-year accelerated ageing period. The immersion solutions had pH values of 0.5, 1.25, and 2.0, with chemistry likely encompassing that found after the leaching of copper, nickel, and uranium in heap leaching processes. With seven more years of data beyond previous studies on the same GMB, this work provides improved estimates of antioxidant depletion times at typical liner temperatures, as well as new data on the changes in physical and mechanical properties due to degradation over time. Despite the significant increase in acid concentration, degradation was shown to be independent of pH. Based on the most conservative estimates, the time to nominal failure of the GMB examined exceeds 210 years at 20 °C, and 35 years at 50 °C when immersed in the low pH solutions. In a composite liner configuration, the time to nominal failure was estimated to be over 120 years at 50 °C, over 390 years at 30 °C, and over 1400 years at 10 °C.