British Columbia Mine Reclamation Symposium

Mine rock stockpile reclamation trial, Detour Lake Mine : Design, construction, and lessons learned Cash, A. E.; Mendoza, C. A.; Straker, J.; Raizman, V.; Lyle, K.; McKenna, G.

Abstract

Designs for reclamation cover systems on waste rock stockpiles must consider the specific objectives of the cover systems and the unique features of individual mine sites. Configurations and characteristics of waste material, characteristics and availability of reclamation material, suitability of vegetation, and climate are some of the considerations. These factors require geotechnical, hydrological, and ecological design decisions be made to achieve site-specific and overall closure objectives; however, in early stages of mine development the characteristics and configurations of the reclamation design which will lead to the better reclamation outcomes are unknown. Guidance for beneficial strategies for landform design and progressive reclamation are being developed at Detour Lake Mine by designing, establishing, monitoring, and evaluating a large-scale (10 ha) Test Cover Trial on waste rock stockpiles during the early stages of mining. The design included 13 cover trial treatments with varying characteristics to consider geotechnical aspects (i.e., constructability, stability, erodibility), ecological aspects (i.e., plant and root development, habitat development), and hydrological aspects (i.e., partitioning water between evapotranspiration, surface runoff, net percolation). The available cover materials were silt rich with variable amounts of peat. To accommodate the unique and challenging properties of these materials, design variables for the Test Cover Trial included ranges in waste rock slope angles, in reclamation cover thickness, composition, and surface grading, and in revegetation treatments. Design modifications were required during construction to accommodate operational challenges and site conditions. Modifications were necessary to decrease cover density, to account for minimal to variable peat content, and to compensate for reduced planting densities, while still maintaining the design intent. Insights into operational-scale construction methods and techniques gained throughout the construction process are being applied to ongoing progressive reclamation at the mine. Results of ongoing monitoring are described in a companion paper by Harrington et al.

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