TRACKING WATER MOVEMENT IN CLOSURE LANDFORMS IN OIL SANDS MINES – EXTENDING TEMPORAL AND SPATIAL MONITORING SCALES

The first oil sands mines in Northern Alberta will also be moving towards final closure within the next few decades. These mines are actively reconstructing final closure landscapes of overburden and mine waste and reclaiming these landforms as mining progresses. This reclamation is occurring at unprecedented scales over extremely challenging parent materials including saline/sodic overburden, sand and fine tailings, as well as refining by-products such as coke. Historically, the primary research questions surrounding reclamation were focused on the ability of reclamation covers to provide sufficient water for reestablishment of upland forests. More recently, the primary research questions are now focused on the release of water through surface and groundwater pathways to engineered closure wetlands and final release off site. This is of particular significance since the mines are designed as zero water release facilities throughout their operation life span of close to 50 years.

A collaborative, multi-disciplinary, research program into the design and performance of reconstructed soil profiles on lands disturbed by oil sands mining has been ongoing at the University of Saskatchewan since the late 1990s. This presentation will highlight key findings from the historical research on long-term reclamation cover performance including the relatively long time frames that are required to demonstrate the trajectory and maturation of these reclamation cover profiles; decades (10s of years) for physical changes and water dynamics and longer (50-100 years) for chemical weathering and the re-establishment of upland forests. More recent research efforts focused on developing new tools for tracking water balance and water migration within closure landforms over large spatial and temporal scales will also be discussed. These methods include the use of air-permeability testing, Geological Weighing Lysimeters(GWL), Distributed Temperature Sensing (DTS) using fibre optics, mapping the stable isotopic composition of site wide waters, deep profiling of the stable isotopes of water, and vegetation monitoring.