Responsible risk-informed tailings closure planning: a Klohn Crippen Berger perspective
This article explores Klohn Crippen Berger’s (KCB) perspectives and leadership in responsible tailings closure – examining industry-wide challenges, perspectives on ‘safe closure’ defined by the Global Industry Standard on Tailings Management (GISTM), and the unique opportunity for mining to rebuild trust and leave a lasting, positive reputation.
Industry challenges and evolving societal expectations
As global demand for minerals accelerates – driven by electrification, infrastructure expansion, and the energy transition – the mining industry faces mounting pressure to scale responsibly. The volume and complexity of Tailings Storage Facilities (TSFs) are expected to grow, and with that, the associated risks. Many operators continue to grapple with legacy sites, inconsistent definitions of leading practice, and limited consensus on what successful closure looks like in practice. Often, closure remains conceptual rather than operational, with few well-documented case studies to guide implementation. TSFs are under increasing scrutiny due to their potential environmental and social risks.
Companies are being called on to improve transparency and accuracy in forecasting long-term costs, particularly those related to tailings and water management for both operations and closure. These costs span capital and operational expenditures, including dam safety upgrades, erosion protection, complex cover systems, water treatment, long-term monitoring, and contingency planning.
These challenges underscore the importance of clear standards and frameworks to guide closure planning and execution.
GISTM’s ‘safe closure’
Numerous standards and guidelines exist to support safe dam design and responsible closure planning. These include the GISTM, the International Council on Mining and Metals (ICMM), Australian National Committee on Large Dams, the Canadian Dams Association, International Commission on Large Dams, the International Network for Acid Prevention, the Towards Sustainable Mining Initiative, and the emerging Consolidated Mining Standard Initiative.
KCB has played a key role in developing and refining these frameworks, which outline the ‘why’ and ‘what’ to do – but often leave interpretation around the ‘when’ and ‘how’ to implement them.
GISTM, in particular, was developed in response to catastrophic failures such as the Brumadinho disaster, which claimed 272 lives. It aims to raise the baseline of dam safety performance across the industry and introduces the concept of safe closure. According to GISTM, ‘safe closure’ is achieved when a tailings facility no longer poses material risks to people or the environment. A ‘safe closure’ status must be confirmed by an independent tailings review board or a senior independent technical reviewer(s) and signed off by the accountable executive. Under GISTM, material is something that deserves attention or can affect the decision being made (e.g. geotechnical, hydrotechnical, and geochemical potential failure modes). For the standard, the operator will decide what counts as important, based on local laws. This will be checked during any audit or independent review of how the standard is being followed.
To support the goal of ‘safe closure’ operators must demonstrate performance attributes across credible failure modes, including:
- Geotechnical: landforms must perform as designed and remain physically stable. This includes no potential for tailings flow beyond the facility, phreatic levels remaining within limits that would not result in increased instability, and without internal erosion occurring such that it could lead to material impacts.
- Hydrotechnical: effective flood routing, drainage, and erosion control are essential to ensure long-term containment and prevent tailings and tailings water release.
- Source–pathway–receptor: closure must address groundwater and surface water flow and quality, and other geochemical risks that could affect downstream receptors.
Meeting the minimum requirements for ‘safe closure’ under frameworks like the GISTM is an essential milestone, but it doesn’t automatically ensure responsible closure, dam declassification, or asset transfer. More holistic ‘responsible closure’ must go beyond meeting the standards – it should actively reduce long-term risks, avoid ongoing care obligations, and support beneficial post-mining land uses that align with the broader site closure vision and regional goals.
Rebuilding trust through closure performance
Closure design is inherently complex, requiring a balance of physical, geochemical, and social objectives – particularly for mine waste facilities like TSFs. While misalignment with operational design has historically stemmed from limited early stakeholder engagement and poor integration into business strategy, the more pressing challenge today is ensuring closure strategies evolve alongside changing mine plans. Because mine plans are dynamic, closure plans must be regularly updated to reflect new operational realities. When this doesn’t happen, it can lead to weak design progression, inaccurate cost estimates, and difficulty applying ‘as low as reasonably practicable’ principles, especially as stakeholder expectations and regulatory landscapes shift.
Even after achieving safe closure of a facility, ongoing surveillance, maintenance, and governance may be required to manage residual risks.
Whether referred to as safe closure, responsible closure, or life-of-asset completion, the focus remains on improving integration, transparency, and long-term planning. This includes building consensus around closure objectives, sharing lessons learned, and fostering collaboration across disciplines and jurisdictions.
KCB applies a forward-thinking, risk-informed approach to sustainable facility design and improved closure outcomes across diverse regions. In line with GISTM Requirement 5.6, we demonstrate closure feasibility early and work with our clients to incorporate progressive reclamation into their mine planning.
Our portfolio spans projects such as the Brenda Mine TSF, Greens Creek filtered tailings, upstream dam risk reduction in Brazil, legacy tailings work for ICMM members, and Papua New Guinea’s first above-ground TSF. In addition to delivering complex projects, we contribute to industry progress through guideline development and capacity-building initiatives like the Glencore Tailings Manager Academy, demonstrating our commitment to responsible closure through practical, measurable outcomes.
Advancing responsible tailings management
Tailings management has evolved significantly over the past several decades, driven by growing awareness of environmental risks and the need for long-term accountability.
In earlier decades, tailings were often discharged into waterways with minimal oversight. The 1960s marked a turning point, with the introduction of engineered containment systems and stronger regulatory frameworks. Technical professionals from firms like KCB played a foundational role in this shift, contributing to dam safety standards and design principles — including the 1972 Canadian guidelines for mine waste embankments — that continue to underpin modern practice.
Today, mining operations are adopting more sustainable and technically advanced approaches to tailings storage and closure. These include filtered and paste tailings, co-disposal strategies, and hydrocycloned sand placement. One of KCB’s founders pioneered the design of centreline cycloned sand dams with construction of the Brenda Dam in British Columbia, Canada – technology which is used globally for responsible dam construction.
As the industry moves forward, integrating closure into the asset lifecycle is essential. This means designing for long-term performance, not just liability, and embedding closure planning from the outset. Key considerations include:
- Vision and end land use: align closure goals with site and regional planning, regulatory obligations, and future beneficial land use.
- Risk, design maturity, and cost: ensure geotechnical and water risks are embedded in strategy and linked to long-term costs. Match closure planning with the appropriate level of design maturity.
- Foundations and materials understanding: develop a robust ground model and understand the behaviour of tailings, embankments, and rehabilitation materials.
- Design basis for closure: establish measurable success criteria and ensure the closure design is tested and endorsed, not just assumed.
- Life cycle planning: evaluate all viable closure alternatives and integrate adaptive strategies into the broader mine and processing plan.
- Learning and benchmarking: actively learn from other sites and industries to improve practice and build collective confidence.
Responsible closure is more than meeting standards — it’s an opportunity for the mining industry to rebuild trust, demonstrate long-term accountability, and leave a lasting positive reputation. This means designing for resilience, engaging stakeholders early, and embedding closure into the full asset life cycle.
At KCB, we promote and implement risk-informed, performance-based closure strategies that are technically robust, socially responsible, and future-focused — core to our company mission and purpose. By embedding these principles into practice, we aim to support the industry in achieving more sustainable outcomes and building confidence in long-term closure performance.