Civil Engineering Departmental Seminar - THE IMPORTANCE OF UNDERSTANDING SPATIAL VARIATION OF GEOLOGICAL PROFILES IN OIL SANDS TAILINGS DAM DESIGN

THE IMPORTANCE OF UNDERSTANDING SPATIAL VARIATION OF GEOLOGICAL PROFILES IN OIL SANDS TAILINGS DAM DESIGN

Design of the External Tailings Area (ETA) for Imperial’s Kearl Mine was based, in part, on seepage analyses that used generalized geologic information combined with discrete boreholes, soil samples and piezometric information. The scale and locations of the available information could not practically describe or account for the geologic variability at the site, which led to discrepancies between the measured seepage rates and the rates predicted in design. This resulted in the installation of “fit for purpose” seepage control measures at locations along the toe of the dam soon after the start of reservoir filling. A series of field investigations and seepage back-analyses were undertaken to better understand the seepage mechanism. The effort focused mainly on how to match the measured and predicted seepage rates and incorporation of important features not initially taken into account. This case study presents a practical approach to evaluate the seepage mechanism, which includes a series of transient seepage back-analyses, establishing relationships for piezometric responses in time and space, and a study on geological borehole locations. The proposed approach substantiated through this case study can be applied to other similar projects