Low-disturbance decharacterisation of a legacy bauxite tailings facility in the Brazilian Amazon: integrated drainage, revegetation and monitoring

Authors: Marques da Silva, N; Carvalho Mollica, M Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2615_98

Cite As:
Marques da Silva, N & Carvalho Mollica, M 2026, 'Low-disturbance decharacterisation of a legacy bauxite tailings facility in the Brazilian Amazon: integrated drainage, revegetation and monitoring', in AB Fourie, G Boggs, J Heyes & M Tibbett (eds), Mine Closure 2026: Proceedings of the 19th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-14, https://doi.org/10.36487/ACG_repo/2615_98



Abstract:
The SP-2/3 bauxite tailings storage facility is part of a 1,405 ha tailings disposal system on a plateau in the Brazilian Amazon, planned for progressive, integrated closure of its structure to restore land function and reintegrate the plateau landform. Constructed in 1988 for deposition of thickened tailings, SP-2/3 operated until 2000 when it became inactive and then the natural recovery process began, during a period of limited Brazilian requirements for dam decharacterisation. After approximately 20 years of rehabilitation and ecological re-establishment, it was necessary to develop a closure strategy aligned with Brazilian dam decharacterisation requirements (including ANM Resolution No. 95) and with international best practices, such as the Global Industry Standard on Tailings Management (GISTM), while preserving established vegetation and minimising disturbance to the tailings surface. This paper presents a low-disturbance closure approach based on integrated engineering and environmental analysis to reinstate surface drainage, eliminate persistent ponding and support long-term revegetation, while reducing residual geotechnical and environmental risks. Works comprised localised openings through major internal topographic barriers to restore hydraulic connectivity, spillways to provide compliant overflow capacity, and localised fills in internal depressions previously prone to ponding to route stormwater to designed drainage pathways. Revegetation protocols were adapted to site conditions using selective topsoil placement, enrichment techniques and treatments for areas formerly affected by waterlogging. Two years of post-construction monitoring confirmed the efficiency of the drainage system, the proper performance of spillways during rainfall events, the stability of reshaped surface, and the continued improvement in vegetation cover. Pre- and post-intervention comparisons demonstrate significant progress in vegetation recovery at SP-2/3 while retaining most pre-existing vegetation. Revegetation included the planting of 19,914 individuals across 18 native tree species. The outcomes demonstrate that integrating terrain morphology, infiltration and water accumulation processes, and environmental criteria from project inception can enable low-disturbance decharacterisation of legacy tailings facilities in environmentally sensitive settings.

Keywords: mine closure, decharacterisation, bauxite tailings, low‑disturbance closure, surface drainage, revegetation, post‑closure monitoring, Brazilian Amazon

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