Grant: Collaborative Research and Development Grants

Ensuring the long-term chemical stability of reactive materials in mine waste storage facilities is one of the main issues in mine site reclamation, and engineered covers are commonly used to address this problem. The goal of such covers is to limit the pollution of water draining from the wastes, usually by controlling oxygen migration and/or water infiltration downward into the reactive wastes. The effectiveness of a cover relies on the ability to control important components of the water balance (WB) in the cover materials, including infiltration, evapotranspiration, and variation in water storage. The presence of vegetation on covers can reduce their water content through root pumping and transpiration. Plants can also change the hydrogeological properties of the cover materials through creation of biopores by roots and organic matter enrichment. These changes can impact infiltration rates and water storage in the cover. The main objective of this interdisciplinary project is to better calibrate and model the impact of vegetation on the WB of mine reclamation covers to ensure their long-term performance. Three experiments will be performed on site at three different mines, at the intermediate scale (10 × 10 m cells) and site-wide scale. Vegetated layers will be added to the designs of reclamation covers in two contexts: low-sulfur waste rocks or tailings, and acid-generating tailings reclaimed with a monolayer made of desulfurized tailings and combined with an elevated water table. The proposed research will help to better quantify the positive and negative effects of vegetated layers on the performances of engineered covers. Two PhD students, one MSc student, and one post-doctoral researcher will be trained and will contribute to fulfilling industry demands for skilled labor in the development of sustainable mine site reclamation practices.