Preliminary assessment of vegetated store-and-release cover using phosphate mine waste in a semi-arid climate

Authors: Zine, H; Elghali, A; Hakkou, R; Elgadi, S; Benzaazoua, M

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DOI https://doi.org/10.36487/ACG_repo/2515_87

Cite As:
Zine, H, Elghali, A, Hakkou, R, Elgadi, S & Benzaazoua, M 2025, 'Preliminary assessment of vegetated store-and-release cover using phosphate mine waste in a semi-arid climate', 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. 1-10, https://doi.org/10.36487/ACG_repo/2515_87

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Abstract:
Store-and-release (SR) cover systems, composed of fine- and coarse-grained materials, are commonly employed for mine tailings reclamation and are expected to maintain long-term performance for reclamation projects. This performance is primarily assessed through water balance components, particularly percolation control. Establishing native plant communities on these covers is crucial for sustaining their functionality over time. Vegetation influences SR cover performance by affecting water balance dynamics and modifying hydrogeological properties. However, its role is often overlooked in cover design and evaluation. This study aims to assess the influence of vegetation on water dynamics within an SR cover system through a column experiment. Three instrumented SR cover columns were monitored using sensors measuring volumetric water content. Cover performance was monitored to evaluate variations associated with the presence (or not) of vegetation over the cover. The SR system relies on rainfall storage during the wet season and water release via evapotranspiration during the dry season. It consists of a 100 cm compacted finegrained layer of phosphate mine waste (clay) designed to, for the first time in North Africa, mitigate acid mine drainage from sulphidic tailings at the abandoned Kettara mine site in Morocco’s semi-arid climate. Vegetation is hypothesised to impact cover hydrology by enhancing water infiltration and modifying water balance in the cover. These factors should be considered in hydrological modelling to design a sustainable SR cover that aligns with the long-term objectives of the mine closure plan for Kettara. Therefore, a multidisciplinary approach integrating both engineering and ecological principles is essential to ensure the effectiveness and longevity of SR cover systems in mine rehabilitation.

Keywords: mine reclamation, column test, store-and-release cover, tailings, Kettara mine

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