Investigating the biogeochemical evolution of mature fine tailings associated with end pit lakes in the Alberta oil sands

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Processing oil sands for the extraction of bitumen produces large volumes of mine waste products (e.g. water, silt/clays, residual bitumen, metals and residual solvents). The current waste practice is gravity settling and subsequent storage in large basins. The denser settled product (mature fine tailings MFT) is then transferred into pits. At the facility in the Fort McMurray region, an ongoing sustainable strategy is creating a containment region by combining the mined-out pits, (e.g. West In Pit) into a series of endpit lakes. The current storage practice can affect the surrounding environment via several different mechanisms. For example, a number of processes can occur within bulk MFT that will affect both the volume and quality of the water cap in the final base mine lakes. These include both biological and chemical alterations of dissolved constituent levels driven by reduction-oxidation (REDOX) mediated reactions, and general consolidation of the tailings layer over time. The proposed research program will investigate the biogeochemistry and development of REDOX gradients of MFT at Syncrude and Suncor oil sand lease operations in Fort McMurray, Alberta. This information will be used to facilitate and support sediment oxygen demand (SOD) environmental models currently being developed for end pit lake design and implementation. The research program will involve scientists from Syncrude Canada Ltd, Suncor Energy, and the Cumulative Environmental Management Association (CEMA) providing funding for one postdoctoral fellow, two Ph.D., one MSc. and three undergraduate students. All HQP in this program will gain multidisciplinary experience encompassing aspects of oil sands mining and processing, end pit lake remediation, geochemistry, and electrochemistry, molecular microbial identification (using novel T-RFLP analysis and qPCR) to investigate the long term behaviour of freshly processed and stored MFT in end pit lake reclamation.