An experimental investigation was conducted on the static liquefaction behaviour of very loose lightly cemented sands. Undrained and drained triaxial compression tests, one dimensional consolidation, high stress compression, and unconfined compression tests were performed on artificially prepared lightly cemented loose samples with cement-sand ratios of 2, 4 and 6%. Additional tests were also conducted on uncemented samples prepared at the same initial void ratio as the cemented samples. Besides the influence of degree of cementation, the effects of void ratio and confining pressure on the liquefaction potential of cemented sands were examined. The aim of this study is to make significant contribution to the understanding of static liquefaction failures in lightly cemented sands. It is shown that cementation could increase the initial stiffness and yield strength of cemented sands but its effect might decrease considerably after the peak strength because of destruction of the cementation bond. The response of cemented sands at lower cement contents was very similar to the response of loose sands and behaviour approached the response of medium to dense sands with increase in the degree of cementation. It is also shown that degree of cementation has a significant influence on liquefaction resistance. Even though the presence of small amounts of cementation did not prevent liquefaction failure, the liquefaction resistance of cemented sands generally increased for higher degrees of cementation. The consolidation, high stress compression and unconfined compression tests demonstrated the effect of cementation in increasing both the stiffness and strength of cemented sands. The unconfined compression strength increased approximately linearly with the increase in cement content. The rate of strength gain increased with an increase in the dry density of the compacted sample, indicating that the cementation was more for denser samples.

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on June 30, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Chemical and Materials Engineering, University of Alberta. Includes bibliographical references.

The velocity of diffusion of the bitumin from sections of 'Tar Sands' has been measured in a specially designed diffusion cell. The solvent used in this case was benzene. The diffusion constant was found to be D = 2.39 x 10⁻⁵/ ft²/hr. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Abstract Not Provided / Thesis / Bachelor of Science (BSc)

Syncrude Canada’s Base Mine Lake (BML), is the first oil sands pit lake and is being used to evaluate water-capped tailings technology for fluid fine tailings (FFT) management. To be successful, pit lakes must achieve the ecological role of a natural lake, requiring the development of oxygenated water cap capable of supporting macrofauna. Due to the reductive nature of the FFT stored at the bottom, oxygen-consuming constituents (OCC) such as methane, sulfide and ammonium can be mobilized into the water cap of oil sands pit lakes, posing a threat to the success of the reclamation. Results from BML are vital to inform successful pit lake design with a further 10+ pit lakes projected for collective waste reclamation required in the region, currently awaiting permitting. This field study established BML water cap depth dependent oxygen consumption rates (OCR), identified the key OCC driving those rates and modeled the roles of biogeochemical oxygen consumption and physical mixing in establishing water cap oxygen profiles during early stage development (< 5 years post commissioning). The balance between these two discrete processes underpins the likely viability of this management strategy for oil sands FFT. Results identify high OCR, in the range of highly productive eutrophic to hyper eutrophic lakes, in the vicinity of the FFT water interface, i.e. where concentrations of OCC are highest. Observed OCR rates decreased away from the FFT water interface, as concentrations of OCC decreased. The important OCC associated with high OCR were methane and ammonium. While the OCR values in the hypolimnion were extremely high, a minimally oxic FFT water interface persisted (<10 μM O2) contrasting the anoxic hypolimnetic waters typically observed in highly productive systems. Water cap oxygen mass balance modeling revealed physical mixing of oxygen into the hypolimnion from the metalimnetic region of the BML water cap currently slightly exceeds the oxygen being consumed through biogeochemical redox cycling, explaining the persistence of low levels of oxygen to the FFT water interface in the BML water cap (~ 10 m in depth). However, higher mobilization of OCC from the FFT as FFT consolidates, and/or higher rates of microbial biogeochemical cycling as microbial communities continue to establish and grow within BML, and/or decreased physical vertical transport of O2 into the hypolimnion, would all shift the oxygen balance towards greater consumption and thus would result in the migration of the oxic-anoxic boundary and OCC higher up into the water cap where they would directly impact the surface zone oxygen concentrations. Modeling results here identify that without the physical injection of oxygen into the hypolimnion, currently observed, OCR rates would generate anoxic conditions that would reach the middle of the metalimnion within this system within 24 hours. The development of an anoxic zone would facilitate greater generation of OCC directly within the water cap through anaerobic microbial biogeochemical cycling, the high levels of sulfate (~ 2 mM) observed within the BML water cap, which exceeds water cap oxygen concentrations by 3 orders of magnitude, indicate that generation of ΣH2S within this pit lake water cap would be a substantive risk to the development of a stable surface oxic zone that can support macro fauna. In addition, the emergence of nitrification, as one of the main oxygen-consuming reactions, was assessed experimentally to determine the potential effects on the oxygen depletion in BML water. Experimental results identified active nitrification with rates in the comparative range of marine to eutrophic estuary environments, with BML water collected from the metalimnion-hypolimnion interface, i.e. where the highest conversion of ammonia to nitrate was observed in field results. However, a comparison of oxygen consumption due to nitrification based on experimental, nitrification only results versus results from the field where nitrification as well as methanotrophy and other oxygen consuming processes are possible indicate oxygen consumption due to nitrification alone in the field is six times lower than the experimental oxygen consumption observed. These results highlight the competition for oxygen by multiple processes within BML, which suppress nitrification below levels observed under ideal experimental conditions. Characterization and modelling results of BML water cap oxygen concentrations carried out in this doctoral research reveal a new understanding of the important processes driving observed oxygen concentrations. These new insights delineate the potential effects of mobilized reduced constituents in the water cap from FFT and processes that may mitigate or exacerbate these impacts. Thus these results are of significant relevance to both the oil sands industry as well as other natural or anthropogenically impacted environments with high oxygen demand. / Thesis / Doctor of Philosophy (PhD)

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 18, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Chemical Engineering, Department of Chemical & Materials Engineering, University of Alberta. Includes bibliographical references.

Thesis (Ph.D.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Feb. 19, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geotechnical Engineering, [Department of] Civil and Environmental Engineering, University of Alberta. Includes bibliographical references.

Several oil sands tailings from Suncor Energy Inc. were analysed with respect to the mobility and solubility of the petroleum hydrocarbon (PHC) contaminants. At sites where oil sands tailings materials have been disposed of and are covered with a growing medium, the PHCs from the tailings may slowly migrate into the reclamation cover, increasing their availability to the plants in the cover system, which could be detrimental to the development and establishment of the plant cover system. This study characterized the PHC content of the tailings and quantified the desorption and diffusion coefficients for F2 and F3 fraction PHCs. All tailings materials collected from Suncor were characterized for initial PHC content. Desorption coefficients were experimentally determined using batch tests for 9 tailings materials (MFT, LG MFT, PT MFT, Tailings Sand, P4 UB Surface, P4 UB Auger, 2:1 CT, 4:1 CT and 6:1 CT). The experimental results from the batch tests were fitted to a Langmuir hyperbolic isotherm model. Diffusion coefficients were determined by fitting the experimental results from a radial diffusion 1-dimensional experiment to a Finite Difference Model. Diffusion coefficients for F2 and F3 Fraction PHCs were developed for 7 tailings materials (MFT, LG MFT, PT MFT, Tailings Sand, 2:1 CT, 4:1 CT and 6:1 CT). The diffusion coefficients (D*) and the Langmuir desorption constants ( and ) developed from these experiments are included in Table A.1. The desorption coefficients resulting from this study are similar to those reported for the desorption of asphaltene, which is one of the components in oil sands tailings. The Langmuir isotherm model was found to be the best fit for the experimental desorption data; the Langmuir isotherm model is commonly used in sorption isotherms of organic chemicals. The results of the radial diffusion experiments agree with diffusion rates found by other researchers in similar porous media. More research may be needed to verify both of these preliminary results for the desorptive and diffusive transport of F2 and F3 PHC fractions in tailings. Tailings composition will continue to change as new technologies for fines settling and bitumen extraction are developed. The diffusion of PHCs from these new materials will need to be examined as it is probable that these changes will affect the transport and mobility of the contaminants.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Sept. 1, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Chemical Engineering, Department of Chemical and Materials Engineering, University of Alberta." Includes bibliographical references.

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on June 29, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Chemical & Material Engineering, University of Alberta. Includes bibliographical references.