Investigations of Layered Cover Systems Acting as Oxygen Barriers to Limit Acid Mine Drainage

In recent years, a number of closure plans for tailings impoundments having an acid mine drainage (AMD) problem have involved the construction of a cover with capillary barrier effects (CCBE). Under a relatively humid climate, this type of cover system functions primarily as an oxygen barrier, due to a fine-grained material layer that remains nearly saturated. The technique has been applied to a few sites in Quebec, Canada, which have been instrumented and monitored to follow cover behaviour. A comparison of reactive transport simulations with in-situ collected data confirms the efficiency of CCBEs in limiting acid mine drainage. This paper presents a few recent cases where covers have been constructed on reactive tailings, including data gathered at the Manitou and LTA sites. Sample results are shown and discussed.