Evaluating the use of stable isotopes of water to characterize oil sands mine waste

T. Baer, S.L. Barbour

In the proceedings of: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Isotope Tracing II

ABSTRACT: There is a need to track and characterize water movement through oil sands closure landforms to understand the hydrological behaviour of these landforms over time. Even after reclamation is complete, these closure landforms will evolve hydraulically and geochemically over decades to hundreds of years. Methods will be required to track the water movement into and out of these landforms over time. Stable isotopes of water have been used by numerous researchers to track recharge rates through natural soil profiles. In the case of oil sands mine closure landforms, these techniques may also be able to take advantage of distinct isotopic signatures that exist as a result of the genesis of the closure landform (e.g. overburden shale or hydraulically placed sand tailings). This study was focused on developing an initial catalogue of the stable isotope of water signatures of oil sands mine site waters in an effort to identify and characterize mine site waters based on isotope composition. This study was undertaken at in the Athabasca Oil Sands Region in Northern Alberta, CA. The mine site contains a range of landforms including process water and fine tailings containment facilities, tailings sand structures and shale overburden dumps. Water samples collected across the site included the following: tailings/process affected water, meteoric water (snow and rain), surface water (from natural and site drainage) and groundwater samples. Soil samples from drilling and sampling operations were also used to characterize formation waters. The local meteoric water line for the mine site established by Hilderman (2011) was expanded and further refined. The results of the study highlight the distinct stable water isotope signature that is associated with hydraulically placed tailings (sand or fine tailings), overburden shale dumps, recycle water and meteoric water. The paper also illustrates examples in which mixing of waters from various landforms are characterized by the isotope analysis.

RÉSUMÉ: Il est nécessaire de tracer ogie de ces terrains vont évoluer sur des dizaines voire des enir les taux de recharge dans des profils de sols naturels. Dans le cas des terrains miniers réclamés des sables bitumineux, une signature isotopique distincte en t amener une précision supplémentaire à cette technique. la mine de Syncrude à Mildred Lake des rejets miniers, les installations de confinement des résidus miniers fins, les structures de résidus miniers sableux et des dépôts de shale de confinement. el et artificiel du site), opérations de forage et d'échantillonnage ont été également employés pour caractériser les eaux. La ligne locale des eaux météoriques pour le site minier, établi par Hilderman (2011), a été étendue et mieux définie. shales de confinement possèdent del'analyse isotopique.

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