Hydraulic Properties Of Aggregated Oil Sand Material From The Athabasca Deposit
Of crucial importance to the reclamation of oil sands mining-affected areas, is creation of a soil medium capable of supporting a target ecosystem. A considerable portion of these landscapes contain coarse-textured soils, which have poor water retention. Furthermore, many soils naturally contain oil sand, and little is known of its effects on the surrounding soils. The key objectives of this thesis were to assess the soil water repellency (WR) and infiltration rates of aggregated oil sand material (AOSM) and surrounding soils from the Athabasca region, to understand their potential to modify the soil water dynamics of reclamation ecosystems. To evaluate the efficacy of discreet and composite salvaging techniques, the effects of salvage depth on the hydraulic properties of AOSM were also examined. A correlation exists between AOSM salvage depth and extent of weathering, where near-surface deposits contain fewer petroleum hydrocarbons (PHC)s than at depth. This relationship confirms onion-skin weathering, where exposure to weathering and degradation is greater in the near-surface of the profile and on the surface of individual aggregates. The WR of AOSM was significantly greater than the surrounding soils, indicating potential for reduced absorption and conductivity. This was confirmed by an infiltration study, which showed AOSM have significantly lower infiltration rates than the surrounding soils. Therefore, AOSM may slow the flow of water through the profile, increasing water storage and providing additional plant-available water, potentially modifying the soil water regime and enabling the establishment of relatively productive ecosites. As salvage depth of AOSM increased (weathering decreased), PHC content and WR increased while infiltration rate decreased. Similarly, PHC content and WR increased with depth into individual AOSM. These results suggest interstitial PHCs are responsible for the enhanced WR and reduced infiltration rates. Therefore, as AOSM continues to weather and its PHCs are degraded and/or removed, its hydraulic properties will likely become more similar to that of the surrounding soils. The results of this study imply the benefits of discreet salvaging, where deep deposits containing relatively high levels of PHCs remain at depth after reclamation, avoiding the excessive drying and expression of WR often experienced in the near-surface.
soil reclamation, oil sand weathering, soil hydrocarbons, aggregated oil sand material, water repellency, water storage, infiltration, miniaturized infiltrometer, tarball, Athabasca oil sand
Master of Science (M.Sc.)