Appendix R: Overview of Acid Rock Drainage Operational and Post-Closure Water Management Strategies at Resolution Copper Mining for the Protection of Groundwater and Surface Water

Resolution will implement best practice, proactive acid rock drainage (ARD) management strategies. The goal of these strategies will be to minimize ARD risks during operation and ensure that ARD is avoided after closure. All potentially impacted water will be contained on site during operation and will be put to beneficial use, thereby reducing the need to import makeup water. The ultimate goal of the management strategies is to avoid the creation of any post-closure ARD-related water management liabilities. No potentially acid generating (PAG) development rock, ore and concentrate will be present on site at closure. All PAG rock within the block cave will be deeply buried and ultimately flooded, permanently isolating it from oxygen and controlling ARD in perpetuity. Similarly the PAG portion of the tailings will be encapsulated within a much larger mass of benign tailings, effectively controlling oxygen ingress and ARD generation in perpetuity.