NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: physical sciences, mining impacts, hydrology, mineralogy, biogeochemistry, waste rock

Objective(s): To investigate the processes related to water quality and quantity (collected at different scales) draining from country rock stockpiles that are located in areas of continuous permafrost.

Project Description: This research study is designed to investigate the processes related to water quality and quantity (collected at different scales) draining from country rock stockpiles that are located in areas of continuous permafrost. The quality of water draining from a country rock stockpile is determined by the combined effects of oxygen transport in the air phase, biogeochemical processes that control mineral weathering rates, the release of heat and dissolved constituents due to sulfide mineral oxidation, and hydrologic processes that control unsaturated water flow. The transport of dissolved constituents is further affected by the precipitation and subsequent dissolution of secondary minerals. Three instrumented country rock stockpiles were constructed from 2004 to early 2007. All three test piles were constructed on an impermeable high-density polyethylene (HDPE) liner that ensures all water that infiltrates the piles and reports to the bottom is collected. In addition, 12 lysimeters (water collection boxes) were constructed on the liner to collect spatially discrete water samples. All water from the base and from the lysimeters is directed to heated instrumentation shacks where the water discharges through a series of flow-through cells. The flow-through cells have probes to measure pH and electrical conductivity, as well as a cell to collect water samples. Water is then direct to tipping bucket rain guages to measure flow. Water samples for geochemical analysis are collected approximately every second day during peak water flows and less frequently when flows decline. Several parameters are measured in the field, and additional analyses are conducted on samples shipped to the University of Waterloo. The study is undertaken entirely as a graduate research program of the Universities of Waterloo, British Columbia and Alberta. Students and staff working on the project are all affiliated with the universities (students, researchers, technicians, professors, and support staff). Seasonal Diavik staff from the north may be able to learn about the project through exposure to the site and research team members, and possibly, in assisting with some research activities. Test Piles Researchers attend the annual Geoscience Forum in Yellowknife, prepare annual progress reports, and prepare papers and conference presentations. Environmental Monitoring Advisory Board (EMAB) site visits include a brief discussion of test piles. The fieldwork for this study will be conducted from January 1, 2012 to December 31, 2012.