Evaluation of the Performances of a Monolayer Cover with an Elevated Water Table Used for the Reclamation of the Abandoned Aldermac Mine Site (Québec, Canada)

Abstract

Until 2008, the Aldermac mine was considered one of the most problematic abandoned mines sites in Québec due to the high production of acid mine drainage caused by mine tailings spread over a large area. The site was reclaimed between 2008 and 2009 to reduce the ecological footprint and to minimize any further tailings oxidation (production of acid mine drainage). For this purpose, a monolayer cover with an elevated water table was used as an oxygen barrier on the north zone of the site. To assess the performance of the monolayer with an elevated water table cover, a network of observation wells was set up to monitor the water table level and collect groundwater samples for the analysis of physical and chemical parameters. Results of water table level measurements show that the cover successfully maintains the tailings within the water table at all times, thus preventing further tailings oxidation. Hydrogeochemical results, interpreted with principal component analysis, show that the quality of water is improving, thus indicating that reclamation is helping to reduce groundwater contamination at the site.