By Behrooz Ghahreman-Nejad, Allan Watson, Keith Seddon – Senior Principal Engineers
Tailings management guidelines around the world, including Australia, have undergone review and change over recent years mainly in the aftermath of major tailings dam failures (particularly Mt Polley, Fundao and Feijao). Amid these changes, the International Council on Mining and Metals (ICMM), representing 27 mining and metals companies, initiated the development of a universal standard on tailings management. The Global Industry Standard on Tailings Management (GSTM) was formally launched on 5 August 2020.
ATC Williams has been at the forefront of tailings management practice in Australia and internationally for over 30 years. Our emphasis is always on the safe storage of tailings, while contributing to the diversity of tailings management approaches through an understanding of tailings material behaviour and innovation of storage technologies.
At ATC Williams, we welcome a heightened focus on standards for tailings management. Therefore, we address these two questions:
- How is the GSTM best applied in the current environment, and
- How does the industry avoid the notion that this standard is more than just “Death by a Thousand Codes”?
Existing Tailings Management Guidelines
Prominent guidelines and standards for tailings management comprise those from ANCOLD (Australian National Committee on Large Dams), ICOLD (International Committee on Large Dams), and CDA (Canadian Dam Safety Association). In an Australian context, most state authorities apply specific requirements through codes of practice or regulations. Mining companies commonly adopt minimum practice standards reflecting their corporate commitment to the community and environmental values, and for risk mitigation purposes.
ANCOLD (and sometimes CDA) and individual state guidelines are commonly adopted in Australia for design and management of tailings storage facilities.
An outline of the GSTM
The Global Industry Standard on Tailings Management was developed with a single goal: striving for Zero harm to people and the environment. Above all, the universal objective of the GSTM is to prevent catastrophic failure and enhance the safety of mine tailings facilities. Most notably, it embodies transparency, accountability and safeguarding the rights of project-affected people.
The "High Level” standard is developed around six topic areas:
- Affected Communities
- Integrated Knowledge Base
- Design, Construction, Operation and Monitoring of the Tailings Facility
- Management and Governance
- Emergency Response and Long-Term Recovery
- Public Disclosure and Access to Information
It is important to note that the GSTM is directed at Operators of tailings storage facilities, whilst providing a robust framework for tailings management.
- To the Owner and Operator
If you are an Owner or Operator, two critical elements of the GSTM that are relevant in your situation are Governance and Emergency Preparedness. Key roles are highlighted, and responsibilities outlined. You will be encouraged to consider the inclusion of Accountable Executives, Engineers of Record and Responsible Tailings Facility Engineer in your team, along with independent review provisions. This enhances your operating culture as related to tailings management, ensuring that the demands of the system are understood and responsiveness and adaptability to emerging issues, incidents or emergencies are readily available.
- To the Designer
The designer will see that the main difference between the GSTM and other commonly used guidelines is the recommended adoption of the extreme design criteria (i.e. consequence category) as the default setting for the design of new and upgrades to existing tailings storage facilities (TSFs). A quick reference from Topic 4 is reproduced below:
A. Develop preliminary designs for the tailings facility with external loading design criteria consistent with both the consequence of failure classification selected based on current conditions and higher Consequence Classifications (including ‘Extreme’).
B. Informed by the range of requirements defined by the preliminary designs, either:
- Implement the design for the ‘Extreme’ Consequence Classification external loading criteria; or
- Implement the design for the current Consequence Classification criteria, or a higher one, and demonstrate that the feasibility, at a proof of concept level, to upgrade to the design for the ‘Extreme’ classification criteria is maintained throughout the tailings facility lifecycle.
Also, under Clause 4.7
Existing tailings facilities shall conform with the Requirements under Principle 4, except for those aspects where the Engineer of Record (EOR), with review by the ITRB or a senior independent technical reviewer, determines that the upgrade of an existing tailings facility is not viable or cannot be retroactively applied. In this case, the Accountable Executive shall approve and document the implementation of measures to reduce both the probability and the consequences of a tailings facility failure in order to reduce the risk to a level as low as reasonably practicable (ALARP). The basis and timing for addressing the upgrade of existing tailings facilities shall be risk-informed and carried out as soon as reasonably practicable.
It is important for the Owner and Operator to note that implementation of an “Extreme” failure consequence category requires design for potentially significantly higher design loads (i.e. earthquakes with a 10,000 year return period). These criteria are expected to have significant cost implications and, in some cases, may result in existing TSFs becoming unviable as the upgrade (even at a proof of concept level) may not be feasible.
Exploring the merits
It is understood (AusIMM Webinar on GSTM)(1) that the ICMM is committed to GSTM implementation through its member companies over five years, comprising:
- one year of review and reclassification of consequence category for existing TSFs
- upgrades to existing high priority TSFs over two years
- upgrading the remaining TSFs over an additional two years
While we contemplate whether the GSTM is a Major Improvement or “Death by a Thousand Codes”, we must also emphasise its three merits:
- A “global” relevance which allows the industry internationally to work on common ground
- Emphasis on operating culture, which amongst other things, encourages partnering between operators and designers
- It “raises the bar” in terms of design standards, with the universal introduction of an extreme consequence category as a default classification.
Our focus, as a community, should be aimed at reducing the probability of tailings dam failures. This reduction is dependent on several elements, including the adequacy of investigation, design, construction, and operation of tailings storage facilities, which may not be achieved only by the introduction of higher governance levels.
(1) AusIMM Webinar on The Global Industry Standard on Tailings Management, 4 September 2020.
For queries regarding the implementation of the GSTM, please contact our tailings professionals in the Melbourne, Perth, and Brisbane offices or Behrooz Ghahreman-Nejad on +61 423 151 019 or email@example.com
Behrooz Ghahreman-Nejad is Chief Technical Officer and Senior Principal Engineer, having more than 27 years' experience with significant emphasis on the geotechnical and water management aspects of tailings and water retaining dams.
Keith Seddon is Senior Principal Engineer with over 40 years’ experience in all aspects of mine tailings disposal, including conventional, thickened and paste tailings schemes.
Allan Watson is CEO and Senior Principal Engineer, having over 30 years’ experience in a wide range of projects primarily servicing the mining and waste management industries.