Walmsley, A, Mundodi, L, Sederkenny, A, Anderson, N, Missen, J & Yellishetty, M 2022, 'From spoil to soil: utilising waste materials to create soils for mine rehabilitation', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: Proceedings of the 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1237-1248, https://doi.org/10.36487/ACG_repo/2215_92
(https://papers.acg.uwa.edu.au/p/2215_92_Walmsley/)
Abstract: The Latrobe Valley in Victoria, southeast Australia, is home to three large open-cast brown coal mines. Due to the nature of the mining operations, there is a lack of topsoil to cover the whole area that is to be progressively rehabilitated. This has led to the development of technosols, employing the ideas of the circular economy by using waste products from three industries located in the Latrobe Valley: mining and energy production (overburden, subsoil, topsoil, waste brown coal and fly ash from the powerplant), paper milling and recycling (effluent sewage recovery and recycling waste) and municipal green waste collection (compost). These waste products have been mixed at different ratios and tested in laboratory, greenhouse and field conditions to establish the best type of technosol that is safe for the environment and can turn into a productive soil in the long-term. If proven suitable, this new concept will not only aid in rehabilitation of large post-mining areas but also help in waste reduction. In a greenhouse study, we tested plant germination and growth in seven different mixtures. Although grass germination was highest in natural topsoil, both grass and clover biomass and leaf length were generally higher in technosols than in topsoil. Also, the plant tissue nutrient levels were similar or higher in technosols than in topsoil. Four out of seven technosols were then transferred into a field trial. Preliminary results from the trial have shown that plant biomass in three out of four technosols is greater than in natural topsoil. Further monitoring of soil properties is being undertaken to assess long-term performance of these soils.

Keywords: technosol, mine rehabilitation, waste utilisation, plant growth