Richard provided a very interesting presentation on the work he is doing at the Diavik Diamond Mine in the Northwest Territories. The project aims to help better understand acid mine drainage in cold climates.
At the mine, three experimental piles of waste-rock have been created in order to determine the processes controlling sulphate oxidation and metal release in the low-sulphide rock piles. There is one large to-scale pile, and two smaller test piles.
Because of the location of the mine, it was found that the core of these rock piles becomes frozen (permafrost), so they have to predict the thickness of the active layer. In addition, the nature of the large grains makes these waste-rock piles very heterogenous.
Each of the test piles are heavily instrumented. Lysimeters with drains were constructed for the bases of each test pile, before the waste-rock was carefully piled on top. Each pile has effluent water collection systems, suction lysimeters, thermistors, TDR soil moisture probes, permeability balls, thermal conductivity ports, tensiometers, and gas sampling lines.
The instruments were distributed throughout the piles in three dimensions. Since the project started in 2006, measurements have been taken from every minute to every month. This provides a “rich and comprehensive data set” that is both spatially and temporally robust.
Two of the piles are instrumented with automated gas sampling systems that collect concentration measurements daily and pressure measurements every minute.
With all the data collected, they were able to capture annual freeze/thaw cycles in the piles. They were also able to develop a relationship between wind-induced pressure gradients and gas flow throughout the test piles.
This wind-induced gas transport had a significant influence on heat and water transport processes. They also found that there is a larger than expected active zone, due to the highly permeable rock and wind driven gas transport.
ABOUT THE SPEAKER – Richard Amos, PhD.
Research Assistant Professor
University of Waterloo
Richard Amos received his Ph.D. from the University of British Columbia in 2006 and previously graduated from the University of Toronto with a Bachelor’s degree in Geology and Chemistry. He currently holds the position of Research Assistant Professor in the Department of Earth and Environmental Sciences at the University of Waterloo. Dr. Amos’ research interests focus on the interaction of biogeochemical and physical processes on the fate of contaminants in groundwater and in the vadose zone. Specifically, the effects of dissolved and vapour phase gases on the rate and extent of bio/geochemical reactions and transport processes that control contaminant release, and/or degradation are investigated.