Pit lakes are one of the most visible legacies of open pit mining that result from permanent modifications to pre-mining topography, hydrology and hydrogeology. The extraction of the non-traditional hydrocarbon resource bitumen from Alberta’s Athabasca Oil Sands using truck-and-shovel techniques will result in the development of 35 pit lakes within the next 50 years. These will be large permanent basins with surface areas ranging from 0.2 to 35 km2 and depths ranging from 5 to 42 m. Only one lake, Syncrude’s Base Mine Lake, presently exists. Stakeholders and regulators are concerned that concentrations of constituents such as naphthenic acids, PAHs, ammonia and chloride in lake water will impair the environmental function and social utility of these lakes. However, numerical models have predicted that, within a decade or two of filling, these lakes will become relatively benign systems with the capacity to sustain aquatic ecosystems and to be fully integrated within the Athabasca watershed.
To improve our understanding of oil sands pit lake functions, a consortium of oil sands producers called Canada’s Oil Sands Innovation Alliance (COSIA) is considering developing a state-of-the-art research facility with three to four demonstration pit lakes, a dozen experimental ponds, and a smaller mesocosm and microcosm facility. The proposed demonstration pit lakes will be approximately 200 m in diameter and 20 m deep, will be constructed using oil sands waste materials and process waters representing proposed closure strategies, and will be monitored regularly for at least a decade. The DPL Project will include funding for external researchers (both Canadian and international) to conduct publishable research on specific knowledge gaps. On a global scale, this will be one of the first research initiatives from the petroleum-, metals-, coal-, uranium-, diamond-, or aggregate-mining sectors to physically test pit lake predictions on this scale in advance of lake formation.

This presentation will review the content and status of the COSIA Demonstration Pit Lakes Project, and will highlight potential research opportunities.