Mixing and temporal variation in the groundwater flow system at the Con Mine, Yellowknife, Northwest Territories, Canada: An analogue for a radioactive waste repository.

• Main Author: Douglas, Malcolm Charles.
• Other Authors: Clark, Ian D.
• Format: Others
• Published: University of Ottawa (Canada) 2009
• Subjects: Geology.
• Online Access: http://hdl.handle.net/10393/9802; http://dx.doi.org/10.20381/ruor-7975

The spatial and temporal variations in geochemistry and isotopes of groundwaters at the Con Mine in Yellowknife, N.W.T., Canada, have provided insights to the impact of mining on the local hydrogeological environment. The study explores the use of mine hydrology in an analogous setting to assess the impact of a radioactive waste repository on groundwater flow, and surface to depth pathways in the Canadian Shield. The 50 years of mining activity at the Con mine fit the time frame envisaged for the construction and operation of a repository. Inflow at eighteen boreholes and three faults was periodically monitored from 1994 to 1996. Groundwater discharge in the mine is a mixture of fresh water to brine, with maximum TDS of 290 g/L, at depths of 701 m to 1,615 m below surface. Three end-members are identified: (1) Shield brine typical of deep crystalline environments, (2) early Holocene precipitation and glacial melt water, and (3) recently recharged meteoric water. A body of glacial water emplaced at the time of deglaciation, has remained stable under the low hydraulic gradients in deep groundwater flow in the low-relief setting of the shield terrain, until disturbed by the steep surface to depth gradients imposed by mining activities. (Abstract shortened by UMI.)