NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: contaminants, water quality, arsenic, groundwater, carbon dioxide, tailings disposal

Objective(s): To determine the magnitude and rate of release of arsenic and other toxic elements from the Giant Mine tailings to groundwater; to evaluate remediation alternatives for tailings management, including the effects of proposed engineered covers; and to apply novel characterization techniques to understand the mechanisms controlling arsenic release.

Project Description: The goals of this research are: 1) to determine the magnitude and rate of release of arsenic and other toxic elements from the Giant Mine tailings to groundwater; 2 to evaluate remediation alternatives for tailings management, including the effects of proposed engineered covers; and, 3) to apply novel characterization techniques to understand the mechanisms controlling arsenic release. The research team will install a network of piezometers within tailings impoundments at Giant Mine for the collection of groundwater samples. Key geochemical parameters, such as acidity and concentrations of dissolved chemical species, including arsenic and sulfate, will be measured. Groundwater physical parameters, including water level measurements and hydraulic conductivity will be used to calculate groundwater fluxes within and from the tailings impoundment. Pore-gas concentrations of oxygen and carbon dioxide will be measured with depth within the tailings impoundment as indicators of sulfide mineral oxidation and carbon mineral dissolution. Tailings mineralogy and microbial-community composition will be characterized in the laboratory at the University of Waterloo and other collaborating institutions. Large-scale column experiments will be conducted in the laboratory to estimate long-term rates of acid generation, acid neutralization, and the release and attenuation of trace elements in uncovered and covered tailings. Geochemical and reactive transport modelling will be integrated with field measurements to provide quantitative estimates of the long-term release of contaminants from the wastes under current conditions and following implementation of the alternative remediation strategies. Results of this research project will be used to inform closure-strategy design to reduce the environmental impacts associated with the long-term management of arsenic-bearing tailings at Giant Mine. The research team is open to dissemination of research results and discussions of the research results with members of the local communities. The research team will provide Indigenous and Northern Affairs Canada with annual progress reports, which will include detailed research progress updates and data summaries. In addition, the results of this research will be described in academic theses, conference presentations, conference proceedings papers, and refereed journal articles. The research team will interact directly with personnel involved in site remediation at Giant Mine. Research results will be disseminated to the public via community-engagement activities; graduate students and other research personnel are willing to provide presentations to local school groups and to other members of the community through knowledge-mobilization workshops. The fieldwork for this study will be conducted from May 1, 2019 to October 31, 2019.