Presented as a key topic at the latest ACG tailings seminar, SRK’s Justin Walls discussed the complexities of Tailings Storage Facility (TSF) closure design processes, shedding light on the critical considerations needed to meet long-term closure goals. Addressing uncertainties, stakeholder expectations, and environmental challenges, the presentation highlighted the multidisciplinary efforts needed to secure safe, sustainable, and resource-efficient solutions for TSF closure.
Navigating Tailings Storage Facility Closure: Accounting for Long-Term Uncertainties
Mining plays a pivotal role in global development, but its legacy often extends beyond the lifecycle of operational mines. TSFs, which host mining waste material, must be transitioned into physically stable, environmentally compatible, and socioeconomically viable landscapes to meet evolving regulatory, community, and ecological demands.
TSF Closure Guidelines and Hierarchies
TSF closure efforts are guided by internationally recognised frameworks such as the Global Industry Standard on Tailings Management (GISTM), ANCOLD criteria, and the ICMM Integrated Mine Closure Good Practice Guide. These guidelines emphasise the importance of creating a post-closure condition that is safe, physically stable, non-polluting, erosion-resistant, and self-sustaining. Closure designs must meet long-term stabilisation objectives by balancing physical, chemical, ecological, and social conditions while remaining economically viable and minimising ongoing maintenance requirements.
Adhering to established hierarchies that prioritise safety, environmental risk limitation, and socioeconomic transition provides a foundation for functional closure plans. These hierarchies also allow flexibility to adapt to site-specific challenges, ensuring that closure designs remain robust and effective.
Factoring in Uncertain Variables
Closure planning is often fraught with uncertainties. Factors such as climate change, geotechnical behaviour of materials, consolidation rates within the tailings body, final TSF geometry, erosion potential, and groundwater seepage require comprehensive study. Stakeholder expectations and evolving regulatory conditions further add layers of complexity. For instance, determining an appropriate storm event to plan for in the face of climate variability and changing legislative requirements necessitates resilient engineering designs that incorporate layers of redundancy.
Combining robust risk assessments with adaptive strategies is essential to anticipate shifts in environmental conditions. Long-term performance depends on closure designs that maintain flexibility to address unexpected field conditions and newly developed data.
Re-defining the TSF Form
The geometry of TSFs plays a significant role in closure outcomes and future land uses. Design considerations for outer slopes and top basin areas must align with surface water management plans and infiltration design. For example, determining whether concave, constant, or stepped slopes are best suited for erosion resistance is a critical decision. Similarly, the top basin geometry must be evaluated for its water-retaining or water-shedding properties. These considerations incorporate geotechnical parameters, appropriate capping materials, and vegetation selection to ensure stability and resilience against erosion forces.
Stakeholder Engagement and Socioeconomic Sustainability
Successful TSF closure planning requires alignment with stakeholder and community objectives. Early collaboration with regulators and local communities is essential to agree on relinquishment criteria. Post-closure objectives may extend beyond traditional land uses, encompassing biodiversity projects, renewable power generation, biofuel cultivation, or other sustainable land practices.
Such initiatives strengthen socio-environmental transitions, ensuring that post-closure landscapes retain value and purpose, contributing positively to local communities and ecosystems.
Tools to Support Closure Design
Modern tools and technologies enhance the efficiency and precision of TSF closure planning. Modelling approaches such as rain-on-grid simulations, groundwater and stability analyses, and landform evolution assessments provide critical insights. Additionally, rendered designs and Augmented or Virtual Reality technologies offer immersive visualisations of proposed closure plans, aiding stakeholder communication and validation.
Integrating rain-on-grid modelling with surface water closure plans has proven effective in optimising runoff and reducing erosion, consolidating long-term safety post-closure.
Innovating Toward Sustainability
TSFs present an opportunity not merely to rehabilitate but to innovate. For sites with challenging closure parameters, forward-thinking designs – such as geomembranes, adaptive water management systems, or climate-conscious vegetation strategies – can unlock pathways to self-sustaining ecosystems.
The long-term success of TSF closures relies on mining professionals dedicating extensive expertise to addressing uncertainties. Balancing risk, cost-effectiveness, regulatory compliance, and ecological transitions is essential to orchestrate a future where closed TSFs contribute positively to their surrounding landscapes.
