Examining controls on mass loading to an oil sands end pit lake

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Mining of oil sand deposits in northern Alberta, Canada involves large open pit operations and generation of fluid fine tailings. End pit lakes have become an important technology for integrating these tailings into mine closure landscapes. This technology involves storage of fluid fine tailings under a continuous water cover within a mined-out pit. The success of end pit lakes as a mine closure strategy depends upon: (1) immobilization of organic and inorganic constituents; (2) establishment of sustainable biological communities; and (3) isolation of submerged tailings from the overlying water column. Thirty end pit lakes are currently included in closure plans for oil sands mining operations in the Athabasca oil sands region. This research will focus on Base Mine Lake, the first full-scale oil sands end pit lake, which was established in January 2013 by Syncrude Canada Ltd. The overall goal of this research is to better understand relationships between biogeochemical mass-transfer processes and physical mass-transport processes within end pit lakes. This goal will be achieved through completion of four key research objectives focused on: (i) constraining controls on the production, consumption, and transport of biogenic gases; (ii) examining relationships between biogeochemical processes and tailings consolidation; (iii) assessing energy transport mechanisms through low solids content fine tailings; and (iv) evaluating controls on physical transport using conservative tracers. These data will be integrated through development of conceptual and numerical models of tailings consolidation and corresponding biogeochemical and physical processes. This research will improve understanding of the biogeochemical evolution of end pit lakes and, therefore, inform ongoing development of closure plans for oil sands mines.