Resume/ Abstract
Cover systems are used to mitigate environmental issues associated with the storage of mine wastes such as acid mine drainage (AMD). AMD occurs when sulfide minerals contained in mine wastes are in contact with atmospheric oxygen and water. Cover systems are designed to control water and oxygen migration down to the wastes they cover, thanks to targeted hydrogeotechnical properties of their materials put in place at construction. However, cover systems are very likely colonized by vegetation with time. Plants can affect cover effectiveness by directly changing water and oxygen distribution in cover materials through water pumping and cellular respiration, and indirectly by modifying the materials’ physical, chemical, and biological properties. Thus, to maintain long-term effectiveness, cover systems must be considered as developing structures with evolving hydrogeotechnical properties influenced by different factors including root effects . Root development and effects are expected to vary in cover systems, due to material types (e.g. grain size, natural vs recycled vs synthetic), cover configuration, and hydrology (level of water table and degree of saturation), but root studies in covers are scarce. In this conference, some quantitative examples of root effects on the degrees of saturation, saturated hydraulic conductivities, water retention curves and oxygen consumption in diverse materials of cover systems designed as oxygen or water barriers will be presented. A better understanding of root and cover system interactions will allow to better predict their long-term performance to control AMD.