The Principale Mine site, located on Merrill Island in Lac aux Dorés, near Chibougamau, is marked by more than 50 years of gold and copper mining. Operations in two distinct sectors, Campbell and Merrill, have left a complex legacy of tailings, waste rock and contaminated areas. The site, which has been abandoned for several years, presents considerable environmental challenges, including the presence of tailings generating acid mine drainage (AMD), soil and water contamination, and structures and infrastructure left in place, such as demolished buildings and tanks that may have contained hydrocarbons. Faced with this situation, the Ministère des Ressources naturelles et de la Faune (MRNF) initiated a restoration program to return the site to an environmentally acceptable state and secure it for future use, while minimizing costs and guaranteeing the longevity of the facilities.

As part of this project, Artelia was commissioned to carry out a complete environmental characterization study of the site and draw up a suitable remediation plan. Our team coordinated the work and acquired the data needed to assess the extent of contamination and determine the best remediation approaches. The work included geotechnical and hydrogeological surveys, laboratory testing and analysis of various remediation techniques. The mandate also involved defining priorities, such as securing old infrastructures, rehabilitating tailings sites and reducing risks associated with wind erosion and contaminant transport. In collaboration with the MRNF and other stakeholders, Artelia proposed a remediation scenario that meets technical, environmental and economic requirements, while also satisfying the expectations of local communities and environmental authorities. To ensure this social acceptability, we presented our solutions at consultation sessions with the citizens of the municipality of Chibougamau, as well as the Cree community of Oujé Bougoumou. This restoration plan will ensure personal safety, the restoration of local ecosystems, and sustainable future use of the site.