A 2011 update for the single-layer desulphurised tailings cover completed in 1999 at Detour Gold

Authors: Cash, AE; Urrutia, P; Wilson, GW; Robertson, J; Turgeon, MH Download Paper

DOI https://doi.org/10.36487/ACG_rep/1208_15_Cash

Cite As:
Cash, AE, Urrutia, P, Wilson, GW, Robertson, J & Turgeon, MH 2012, 'A 2011 update for the single-layer desulphurised tailings cover completed in 1999 at Detour Gold', in AB Fourie & M Tibbett (eds), Mine Closure 2012: Proceedings of the Seventh International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 149-162, https://doi.org/10.36487/ACG_rep/1208_15_Cash



Abstract:
A desulphurised tailings cover was installed to reduce oxygen diffusion into underlying sulphidic tailings at the Detour Lake Mine in Ontario, Canada between 1998 and 1999. This paper reviews the outcomes of the original characterisation of the desulphurised cover in 2000 and evaluates performance of the cover following an investigation completed 11 years after installation. A holistic view of the tailings system is discussed including water quality testing, fish populations within the tailings management area, and geochemical analyses of the desulphurised cover. An initial site investigation and numerical modelling were completed by Sjoberg-Dobchuk et al. (2003) to instrument the cover and monitor the water content profile, as well as to collect tailings samples for geotechnical and geochemical characterisation. Numerical simulations concluded that the tailings cover would not maintain greater than 85% saturation within the region of the beach. However, oxygen flux rates through the desulphurised cover to the underlying tailings were still found to be reduced to 2 mole/m2/yr or less due the consumption oxygen by the residual sulphide content within the cover profile. This study indicated the cover was effective in preventing ARD. A follow-up study was conducted in August 2011 to assess the performance of the cover system prior to flooding by new tailings. A site investigation was conducted at the original instrumentation locations to collect samples for geochemical analyses. The laboratory results and visual observations indicated the cover is performing well, without maintaining >85% saturation. Water quality sampling of the tailings pond water generally met or exceeded the Ontario Provincial Water Quality Objectives and the tailings pond supported a substantial population of four fish species. The study provided further confirmation that the profile of the desulphurised tailings cover profile has not become acidic and the cover performance has met the initial design expectations.

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