Wormeester, E & Vause, A 2025, 'Retrospectively applying the Global Industry Standard on Tailings Management to 
legacy tailings facilities to achieve safe closure', 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_10
(https://papers.acg.uwa.edu.au/p/2515_10_Vause/)
Abstract: The Global Industry Standard on Tailings Management (GISTM) highlights the critical need to develop closure plans at the very beginning of a project. This means that tailings storage facilities (TSFs) should be planned and designed with both closure and post-closure phases in mind. However, many TSFs that were established, operated and decommissioned before the advent of modern standards and regulations often lack such plans, or the existing plans may be insufficient. These legacy sites can pose significant environmental and safety threats to their surroundings. To meet the requirements of GISTM, this paper proposes a systematic approach using reverse engineering to achieve the safe closure of legacy TSFs. The process begins with a gap analysis to evaluate the adequacy of the existing knowledge base and closure plans. The knowledge base is essential for assessing the facility’s performance, identifying risks, and selecting appropriate closure measures. The success of this analysis depends on the expertise of the review team, which must possess strong geochemical, geotechnical, geohydrological, hydrotechnical, environmental and socio-economic skills. If significant gaps are found in the knowledge base, actions must be taken to close the gaps and the environmental, geotechnical, and hydrotechnical performance of the facility must be re-evaluated and risks reassessed. The design basis for closure is then established, and closure options are explored and evaluated through a multi-criteria alternatives analysis that considers environmental, social, and safety aspects, aiming to reduce material risks to ‘as low as reasonably possible’ (ALARP). Ultimately, this leads to the selection and development of a suitable closure design, followed by construction and monitoring to achieve a safe and stable landform.

Keywords: tailings, GISTM, TSF, closure, legacy site, reverse engineering