Mine waste cover system design – considerations for cold regions

Authors: Dobchuk, B; Nahir, M; O’Kane, MA; Ayres, B Download Paper

DOI https://doi.org/10.36487/ACG_rep/1208_37_Dobchuk

Cite As:
Dobchuk, B, Nahir, M, O’Kane, MA & Ayres, B 2012, 'Mine waste cover system design – considerations for cold regions', in AB Fourie & M Tibbett (eds), Mine Closure 2012: Proceedings of the Seventh International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 417-431, https://doi.org/10.36487/ACG_rep/1208_37_Dobchuk



Abstract:
The contaminated sites program of Aboriginal Affairs and Northern Development Canada (AANDC) is responsible for closure of contaminated sites on Crown land throughout the Canadian north. A significant percentage of the closure liabilities faced by AANDC are associated with abandoned mines. Of these mine-related liabilities, many involve the need to construct earthen cover systems over potentially reactive tailings and waste rock in cold regions. AANDC will be implementing cover systems at sites in the very near future and therefore require that critical questions in regards to cold regions cover systems be addressed: i) what are the key processes that will affect performance of different types of cover systems within a cold regions context; ii) how should the design process incorporate these issues; and iii) what are the risks to long-term performance as a result of these cold regions phenomena. This paper outlines the technical guidance approach for cover systems in cold regions that has been developed by AANDC with the assistance of a Technical Advisory Group (TAG). Extreme climatic conditions in cold regions result in the ground surface reacting in ways not experienced in warmer regions of the world. These terrain features are caused by frost action processes. Frost action refers to soil behaviours that are the result of freezing and thawing of water within the soil matrix. Key points from the guidance document are presented. Cover system design philosophy as it relates to cold regions is discussed including utilising attributes of cold regions in design. Designing for sustainability highlights the importance of final landform design and key failure mechanisms for covers in cold regions: thermokarst, solifluction, and glaciation of surface water management systems. An emphasis is placed on robust landform design as well as the importance of risk assessment to evaluate final cover design. A generic case study is presented to provide an example of a cold regions cover design and the results of a risk assessment.

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