Using heat as a potential groundwater Tracer through Stratigraphically Complex Media at the Victor Diamond Mine Site

Abstract

The Victor Diamond Mine site near Attawapiskat, Ontario will begin mine development in the fall of 2007. The area around the site is characterized by two to three meters thick patterned peatland, which in turn is underlain by sand and silt, variable marine clay, and a large limestone bedrock aquifer. Bioherms, which are large, fractured limestone rocks that extend upward from the bedrock, to the surface in some cases, are complicating features to consider in the mine development planning. There is concern thatdewatering the aquifer for open pit mining may lead to disruptions in the surface peatlands due to draining through the bioherms. Dewatering the aquifer could impact the hydrological and ecological balance of the peatland, but the magnitude of the effect depends on the characteristics of the connections between the peatland and the underlying materials, which are currently unknown. A five year research program has commenced at the site to gain insight to the material behaviour and to study changes at the site asdevelopment progresses. This project will analyze the potential to use heat as a tracer for groundwater movement, and to integrate the findings into the long­term monitoring plan. Heat tracing may be used to test hypotheses for water movement at the site, and to detect areas of particular concern during dewatering. It is expected that collecting ormation about the site in this way and implementing monitoring plans will prevent, or at least anticipate, significant changes in the peatland ecosystem.