Grant: Collaborative Research and Development Grants

The environmental issues associated with mineral exploitation are mostly associated with the chemical instability of weathering mineral assemblages when they are exposed to air and water flows. Different tailing ponds and waste rock piles management and reclamation strategies have been developed and applied to prevent the generation of acid mine drainage, by limiting the water flow and the penetration of the oxygen. The construction of cover layers on the top of tailings ponds and waste rock piles is one of the most promising reclamation strategies since it is easy to implement and relatively inexpensive. However, these cover layers are subject to erosion, freeze and thaw effects, vegetation action, extreme weather events and climate changes. It is therefore important to evaluate and to monitor their performance over time. The monitoring is currently carried out with traditional hydrogeological instruments, such as water content and suction probes, piezometers and lysimeters; which is not very suitable for the monitoring of large areas (up to several hundred hectares). Indeed, the measurements have a limited volume of investigation (a few cubic decimeters around the probes). We propose to develop and apply an electrical imaging system to evaluate the performance of cover layers in the context of mining site reclamation in Canada. Automatized measurements will be used to reconstruct the water content distribution continuously for a full year. The proposed large-scale electrical imaging also aims to identify the best cover layer geometry over the entire tailings pond and for waste rock piles for future design.