Voyer, E & Arsenault, J 2026, 'Rehabilitation of historical mine features: from mitigation toward true risk elimination', in AB Fourie, G Boggs, J Heyes & M Tibbett (eds), Mine Closure 2026: Proceedings of the 19th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-15, https://doi.org/10.36487/ACG_repo/2615_32
(https://papers.acg.uwa.edu.au/p/2615_32_Voyer/)
Abstract: The Abitibi–Northern Ontario region is one of the most historically significant mining areas in Canada, with more than a century of continuous mineral exploration, underground development, and large-scale mining production. Hundreds of historical mine workings are the legacy of extensive exploration and mining operations, including shafts, raises, portals, drifts, adits and stopes, often connected in complex underground networks. 
Over time, these mine features have become part of the regional landscape. Closure and rehabilitation work can be critical, as unmanaged legacy mine hazards may continue to deteriorate and present significant hazards that can affect ground integrity and community safety.
Initial mitigation approaches often focus on containing risks rather than managing the underlying sources of hazards. Advantages to proceeding towards comprehensive, integrated, long-term interventions that aim at eliminating hazards rather than mitigating them include enabling future access to communities, reducing long-term costs and improving the likelihood of relinquishment. Eliminating hazards may require several investigations and design steps, as it is often more complex and costly than short- or medium-term securing measures and therefore requires strong justification before being implemented.
However, historical mining activities were often poorly documented, lack reliable records, and deterioration over time makes it necessary to verify subsurface conditions. Rehabilitation designs of legacy mine hazards start with desktop assessment using sometimes limited historical records to identify potential risks. Field investigations using various survey techniques, along with technical assessments that meet regulatory standards, enable initial assumptions to be refined to design tailored rehabilitation options.
This article presents case studies of completed and ongoing rehabilitation projects in the Abitibi–Northern Ontario region. It outlines both industry and technical perspectives on the challenges posed by limited historical information, considerations guiding the selection of investigation methods and the field constraints encountered during investigation and rehabilitation processes. It demonstrates that effective rehabilitation aimed at eliminating hazards relies on an adaptive, risk-based approach that evolves as new information emerges, ensuring hazards are accurately characterised and properly addressed.