Windle, D, Weaver, T & Kovacsy, D 2026, 'Contaminated site assessment strategies to address mine closure planning challenges', 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. 1-12, https://doi.org/10.36487/ACG_repo/2615_84
(https://papers.acg.uwa.edu.au/p/2615_84_Windle/)
Abstract: Strategies for contaminated site assessment and remediation have been developed to address mine closure planning challenges, based on direct experience at multiple Australian mines. 
The typical approach to contaminated site assessment at mines references a contaminated sites register and focuses on small or operational areas (such as workshops, refuelling, landfills, airports and historical spills). Challenges arise when applying contaminated site guidance – the National Environment Protection (Assessment of Site Contamination) Measure (ASC NEPM) and the Per- and Poly-fluoroalkyl Substances National Environmental Management Plan (PFAS NEMP) – to mines, for example due to their typically large size (potentially unachievable sampling densities) and remote nature (including limited formal waste disposal locations). Mineralised conditions and Traditional Owner land use also present challenges applying standard assessment criteria that do not account for elevated background concentrations (mineralisation) or sitespecific exposure pathways. While contaminated site assessment and remediation is typically a closure cost provision, it is often based on limited information, undertaken later in closure planning, and costs are frequently underestimated. 
Strategies to address these mine-specific challenges that reflect Australia’s ASC NEPM/PFAS NEMP framework and local regulations include undertaking aspects of contaminated site assessment well before closure, e.g. risk assessment that includes Traditional Owner land uses. Leveraging existing and new data through dashboards and visualisations helps to improve decision-making and stakeholder communications and assists with deriving background concentrations to inform site-specific, risk-based criteria. Development of mine-wide conceptual site models (CSMs), remedial objectives and strategies assists in prioritising assessment of spatial or contaminant-based domains that consider historical activities, current conditions or potential future land uses. Finally, assessing individual PFAS (per- and poly-fluoroalkyl substances) sources while considering mine-scale processes that may distribute PFAS more widely is key. 
These strategies support closure through improved and more complete remediation planning, allowing areas to be cleared or remediated before closure, and potentially identifying practices to change or implement that may reduce future contamination. These approaches better inform liabilities and costs associated with managing contaminated sites, facilitating more timely and cost-effective mine closure.
Strategies for contaminated site assessment and remediation have been developed to address mine closure planning challenges, based on direct experience at multiple Australian mines. Key challenges that are common to many mine sites relate to assessment of multiple sources at sites that are large and typified by long and complex histories. Further challenges arise due to typically mineralisation conditions, including for risk assessment and remediation, and particularly due to the remote nature of many mine sites, which limits remediation options. Strategies to address these challenges involve early assessment, engagement and consideration of contaminated land in operations and closure planning. The value of consolidating and leveraging existing data to support decision-making and stakeholder communication cannot be underestimated. While different strategies and combinations of strategies will apply at individual mine sites, a robust mine-wide CSM and perspective should be developed and updated through the entire contaminated site assessment and remediation process for every mine. Benefits in adopting these strategies include time and cost improvements for site assessment and remediation during operations, rehabilitation and closure.