Cissé, MK, Guittonny, M & Bussiere, B 2025, 'Characterisation of the Pinus banksiana root system to adjust the thickness of the coarse layer over a 
cover system used to control contaminated mine drainage in a boreal context ', in S Knutsson, AB Fourie & M Tibbett (eds), Mine Closure 2025: Proceedings of the 18th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-16, https://doi.org/10.36487/ACG_repo/2515_97
(https://papers.acg.uwa.edu.au/p/2515_97_Cisse/)
Abstract: To manage contaminated mine drainage, multilayered covers can be used to reclaim mine sites. Multilayered covers are composed of three to five layers of materials with contrasting hydrogeotechnical properties to limit water infiltration and/or oxygen migration into the tailings. To protect the core integrity of this cover system against climatic conditions, animals, and plant roots, a coarse layer (protection layer) is placed over the barrier layer between the mine waste and the outside environment. The roots of deep-rooted plants should be prevented from reaching the barrier layer below the protection layer; if root penetration occurs, it could alter the hydrogeotechnical properties of the barrier layer, causing performance loss. Furthermore, the design of the protection layer must anticipate long-term ecosystem changes that may influence cover performance. However, data representative of future ecosystems at reclaimed sites can be difficult to acquire by conventional methods. Studying a natural analogue of a multilayered cover can help to obtain these data. In this paper, the root systems of nine Pinus banksiana (77 to 119 years old) and four Picea mariana (76 to 94 years old) were studied in a well-drained sand (used as a protection layer analogue) on a gold mine site located in the boreal zone in Northern Quebec, Canada. Maximum rooting depth (MRD) and root colonisation along the soil profile were characterised by species. The MRD of Pinus banksiana was 100 cm and that of Picea mariana was 60 cm. Pinus banksiana and Picea mariana rooting occurrence and density, as well as Pinus banksiana root length density (RLD) distribution, were mostly concentrated (> 80%) in the top 30 cm of the sand. These data will be useful to adjust the thickness of the coarse layer to be placed above the barrier layer in a multilayered cover constructed to reclaim a tailings storage facility and facilitate the long-term performance of multilayered covers.

Keywords: multilayered covers’ performance, natural analogue, Pinus banksiana, Picea mariana, reclamation, root development