Abstract

Bernard Swarbrick¹ Vincent Boulanger-Martel²

¹: Cornerstone EHS Management Systems Inc. Toronto, Ontario, Canada

² : Université du Québec en Abitibi-Témiscamingue, Research Institute on Mines and the Environment, Rouyn-Noranda, Québec, Canada

ABSTRACT

Surface water management is an important challenge facing the mining industry. During operations, a significant amount of water must be managed and treated to ensure the stability of mining infrastructures and protect the environment. The accumulation of snow on the surface of tailings storage facilities (TSFs) during winter represent an important (and typically the largest) component of the annual water inventory. Over the winter months, the water inventory is collected as snow, resulting in the collection of water over 3-4 months. This water inventory generally needs to be released during the spring runoff over very intense and compressed timelines (generally 1-2 weeks). As a result, spring snowmelt is associated with peak flows that place high demands on TSFs, surface water management and mine water treatment infrastructures. Certain conditions such as a large snowpack combined with a warm and rainy spring could be critical to the performance and integrity of such mining infrastructures. Moreover, the spring runoff period, in many cases presents one of the greatest risks to tailings dams, flumes and treatment capacity. Thus, it becomes essential for mining operators to be able to better control water flows and reduce the geotechnical and environmental risks associated with snowmelt. The risk level to mines has substantially increased because of climate change, where initial design criteria for existing operations are being challenged. Therefore, gaining control on spring water flows is particularly relevant in the context of climate change where it is difficult to accurately predict the evolution of climatic conditions.

As such, CORNERSTONE EHS Management Systems Inc. in collaboration with the Research Institute on Mines and the Environment at UQAT have developed strategies which slow the snow melt significantly, spreading the spring runoff over 4- 6 weeks (and possibly longer). This has the potential of significantly reducing peak flows, providing much more control over the water management during this high-risk period. This can further improve water treatment and reducing noncompliance with regulatory requirements during these periods. Field test work was conducted to assess the effectiveness of strategically constructed snow management piles at controlling snowmelt on TSFs. In situ characterization work were performed to assess the evolution of density and thermal conductivity of groomed snow as a function of depth in the pile and time. Then, the volumes of the snow management piles were monitored throughout snowmelt using remote sensing tools. Details on the construction methods and challenges associated with snow grooming are also provided and discussed. Results demonstrate that engineered snow management piles are an effective tool to manage the winter water inventory, control snowmelt and reduce extreme meltwater flow rates. Further test work is ongoing to optimize the design, construction, and performance of this new water management tool.