Grant: Research Tools and Instruments - Category 1 (<$150,000)

Geomembranes are thin plastic liners (1.5- to 2-mm-thick high-density-polyethylene sheets) that are frequently used as part of barrier systems for waste containment facilities (landfills, heap leach pads) in order to minimize the movement of potentially hazardous contaminants into the surrounding environment. Although widely used, there is presently very little data concerning the long-term performance of geomembranes under likely field conditions. To address this concern, the applicants are conducting a program of research into the effects of ageing on the performance of geomembrane liners. The research involves accelerating the ageing process in the laboratory using elevated temperatures and then monitoring the changes in geomembrane properties with time. In this work the depletion of the protective antioxidants (added to the plastic to provide better long-term durability) will be monitored using specialized Differential Scanning Calorimetry (DSC) testing. Knowing how long it takes for the antioxidants to deplete provides essential information on how long the plastic liner may last. Building on a dozen years of preparatory work, the novel and unique aspects of this research are the examination of: through thickness variations in antioxidant concentration, extreme pH leachates and realistic field exposure on the oxidative degradation of polyethylene geomembranes. The proposed work is anticipated to: (a) provide essential data towards answering the question of how long the plastic liners will last; and (b) improve the long-term physical performance of the plastic liners; both ultimately resulting in waste containment facilities that provide greater long-term environmental protection. 10 HQP (PhD: 3 current and 2 starting May 2011, one MSc, 2 Postdoctoral Fellows and 2 Technologists) will receive advanced training regarding the long-term behaviour of environmental liners using this equipment.