Monitoring the Behaviour of the Multi-layer Cover at the Lorraine Mine Site
Symposium Rouyn-Noranda 2002
Michel Aubertin, Bruno Bussière, Johanne Cyr, René Fontaine,
Located in the Témiscamingue, the Lorraine Mine operated from 1964 to 1968, generating about 600 000 tonnes of tailings placed in a pond covering nearly 10 hectares. The tailings in the non-saturated zone remained exposed to the elements for over 30 years, allowing the activation of sulphide oxidation reactions and the generation of acidic leachate at the foot of the permeable embankments. In 1998, following a characterization study and the analysis of rehabilitation scenarios, the ministère des Ressources naturelles undertook rehabilitation of the site in order to limit the damage caused by acidic spills and to control the generation of acid mine drainage (AMD). The rehabilitation plan included various types of work including the construction of a cover with capillary barrier effects (CCBE) over the tailings pond. The main objective targeted by the placement of the CCBE at the Lorraine site was to hinder the migration of oxygen towards the reactive tailings in order to control the formation of AMD, by keeping a layer of material near saturation owing to the capillary effects generated by this type of cover. Following construction, the CCBE was monitored to evaluate its hydric behaviour and its performance in controlling AMD. This article presents and analyses the results of the three years of monitoring.