The hydrologic behaviour of waste rock piles in the Canadian Arctic : snowmelt infiltration and the onset of long term freezing in test piles

• Main Author: Krentz, Andrew
• Format: Thesis
• Language: English
• Published: University of British Columbia 2014
• Subjects: Arctic; Diavik Diamond Mine; Rock Pile
• Online Access: http://hdl.handle.net/2429/50996

This thesis examines the hydrology of three experimental waste rock piles located in the Canadian Arctic at Diavik Diamond Mine (DDMI). Seven years of hydrology data is presented, including measurements of moisture contents, outflow volumes and soil tensions, along with an estimate of annual rainfall infiltration. The hydrology of each pile is influenced by freezing and thawing, and pore water flow is restricted to the time periods when the pile is thawed. The base of each pile contains drain pipes used to collect pore water from the piles, and these pipes are lined with internal heat traces. This research shows that the heat traces significantly influence the thermal behaviour and hydrology of the waste rock. A flooding event in the winter of 2012 interrupted power to the heat trace in two of the waste rock piles, and led to altered outflow volumes and patterns in 2013. A heat trace in the base of the third pile was intentionally turned off in 2011, and led to a significant decrease in the volume of outflow collected from the pile in 2012 and 2013. A bromide tracer was applied to the crest of one of the piles in 2007, and the recovery of the tracer is analysed until 2013. The results of this analysis are used to quantify the average residence time and flow velocity of pore water within the pile. The concentration of stable isotopes is analysed in outflow from the same pile, and is used to estimate the contribution of snowmelt to the total recharge received by the pile. The infiltration of snowmelt into another waste rock pile is estimated using the results of four snow surveys, a snowmelt ablation model, and an infiltration model suitable for use on frozen porous media. The research contained in this thesis provides information that will be incorporated into the final closure plan for DDMI, and will be used to help prevent the formation and release of low quality effluent from the full scale waste rock pile located at the mine site. Science, Faculty of Earth, Ocean and Atmospheric Sciences, Department of Graduate