Oil sands process water and tailings pond contaminant transport and fate : physical, chemical and biological processes

• Main Author: Lévesque, Céleste Marie
• Format: Text
• Language: English
• Published: University of British Columbia 2014
• Subjects: Fort McMurray; Mildred Lake
• Online Access: https://dx.doi.org/10.14288/1.0165952; https://doi.library.ubc.ca/10.14288/1.0165952

The Alberta Oil Sands development has been in operation since the 1960s, where innovations in technology in bitumen extraction have resulted in adaptive management of environmental sensitivities to Oil Sands Process-affected Water (OSPW) and tailings. This research assessed all the potential processes that OSPW constituents might undergo in the tailings impoundments in order to theorize on their ultimate fate. A conceptual tailing pond model was created, the first of its kind as there have been no attempts in the existing literature, and a tool for future management of these facilities. The development of a model is quite complex where the objectives are defined (e.g. OSPW constituents) and the various physical, chemical, biological, geochemical, hydrological and limnological processes involved. This research was conducted by one individual, while such integration and analysis would typically be tackled by a team of multidisciplinary experts. The scope of this research included the OSPW produced from oil sands open-pit mining, extraction and processing of bitumen. The crushing of ore and chemical additives affect water chemistry through the release of ions, salts, metals and organic compounds. Oil sands mines generate process affected water high in contaminants and the high degree of water recycling further concentrates these substances. The spatial and geological focus comprised the Athabasca ore deposit, with special attention on the Fort McMurray area and particular examination of the Mildred Lake Settling basin. A thorough literature review was conducted where the data and concepts from various scientific sources were utilized as a basis in the creation of a Tailings Pond Model, to conceptualize the physical, chemical and biological processes within a typical tailings settling basin. All further refinement and upgrading of the bitumen, processing of coke or other by-products were out of scope. Technological innovations in bitumen extraction and assisted tailings consolidation have resulted in more complex constituent compositions. The physical, chemical and biological processes occurring within a tailings pond are multifaceted making it difficult to model the ultimate fates of various substances. Chemical oxidation and bacterial decomposition have been shown to decrease toxicity of certain contaminants of greater concern.