A former Gold and copper ore processing site for over 50 years, Mine Principale was one of the largest in the Chibougamau area and covered a surface area of more than 300 hectares. With the main site operations ceasing in December 2004, the site is now home to three tailings yards with an estimated 19 Mt of tailings, an open pit, various industrial buildings and a polishing pond with an area of approximately 95 ha.
Several studies showed the site's tailings to be potentially acid generating (PGA) and leachable to metals (Cd, Co, Cu, Ni, Zn). According to Mining Industry Directive 019, the levels of Cd, Cu, Zn and petroleum hydrocarbons in the groundwater were above standard levels. Finally, sectors were found to be unstable at the surface pillar level and required security measures.
To ensure human safety and restore the site to an environmentally acceptable condition that would encourage future recreation, hunting and fishing, WSP was mandated by the Ministry of Energy and Natural Resources to provide engineering, project management and construction services for all restoration and remediation work on the Mine Principale mine site.