Grant: Collaborative Research and Development Grants

Planting vegetation is a potential method to dewater saturated tailings structures and increase soil strength through a root bed that acts as a natural reinforcing geotextile. Conventional planting and broadcast seeding by professional crews cannot be accomplished at large scale on very soft deposits because of the safety risk to personnel. This study aims to determine viable plant establishment approaches for the unique conditions presented by soft tailings deposits. Approaches will include different forms of seeding and planting of nursery stock seedlings. Robotic methods to deploy and fertilize plants on soft tailings will also be demonstrated for planting, fertilizing (Spring and Winter). Hydroseeding and hydraulic transport will also be assessed. The species of interest include: slender wheatgrass (Agropyron trachycaulum), sandbar willow (Salix exigua) and water sedge (Carex aquatilis). Together, these species represent a range of moisture tolerance and growth habits. Through all trials, detailed plant and geotechnical data will be collected in order to quantify the effect of plant-mediated dewatering. A techno-econometric evaluation will be done to assess the cost of scale-up, the most appropriate timing for planting and subsequent lifts of material to ensure effective dewatering and strengthening, and the degree of automation necessary for commercial implementation. A highly interdisciplinary group of university and polytechnic students and staff will comprise the team. Three graduate students, one post-doctoral fellow, four university undergraduates will be trained in the present project, with two college diploma researchers be trained with support from three research technicians and research associates in complementary efforts in a closely related project at a polytechnique. The expected outcome is a protocol for using vegetation as a method for dewatering and strengthening of challenging wet soils prior to reclamation for a final landscape.