The Tailings Compliance Priority Project identified opportunities for improvement in how the mining industry assesses the risks associated with tailings storage facility management and adopts appropriate controls for hazards. In particular, the mining industry must be aware that the risks to tailing storage facility management need to be considered throughout the life of a mining operation (design, construction, operation and decommissioning) to enable effective implementation of controls that will ensure operations are conducted in a safe and sustainable manner.

The NSW Resources Regulator does not prescribe how mine operators should conduct risk assessments specific to tailings storage facility management. However, guidance is provided below for how mine operators should approach risk assessments for events that affect both workers safety (WHS Act considerations) as well as environment, rehabilitation and mine closure matters (Mining Act considerations).

WHS (MPS) Act 2013 considerations:

The Guide - Preparing a principal hazard management plan provides information for how operators are required to consider risk to workers associated with tailings storage facility management. It is noted that tailings storage facility management is not listed as a ‘specified hazard’ in accordance with WHS (Mines and Petroleum Sites) regulation, however are considered as a component of the inundation and inrush hazards. Consideration of tailings storage facility management is required due to the reasonable potential to result in multiple deaths in a single incident or a series of recurring incidents.

The Notifying the regulator of a high risk activity (form contains guidance notes) provides notification requirements to the Regulator for operators undertaking listed high risk activities (HRA) in accordance with WHS (Mines and Petroleum Sites) Regulation.

Mining Act 1992 risk assessment considerations:

The ESG3 Mining operations plan (MOP) guide provides requirements for operators to consider specific risks relating to environmental issues (refer to Section 3.1 and 3.2 in this guide). Risk assessments are required to be undertaken in accordance with AZ/NZS ISO 31000:2018 Risk Management – Guidelines.

This Standard requires risk controls (or treatments) to be identified and justified, with risk treatment plans integrated into management plans and processes. As such, the implementation of risk controls for tailings storage facility management for closure is required to be clearly outlined in the MOP. The Regulator recommends that special consideration of tailings risk assessments and controls is undertaken in the MOP due to these mining domains having unique risks that may not apply to other areas of the mine.

A key consideration is that risks associated with tailings storage facility closures are required to be considered throughout the life of a mining operation (design, construction, operation and decommissioning) and not just be limited to the closure phase.

Guidance provided below may be useful for operators to consider the range of issues that the Regulator considers when determining the adequacy of controls implemented by mine operators to address risks associated with tailings storage facility closure.

Tailings storage facility closure risk assessment

As part of Tailings Compliance Priority Project, we conducted internal risk assessment workshops to improve the understanding of critical controls to address risks associated with events that affect the environment and mine closure matters (Mining Act considerations) associated with tailings storage facility management.

These assessments used the bowtie risk assessment method to display the links between the potential causes and consequences as well as the preventative and mitigative controls associated with the material unwanted events of 'release to the environment' and 'post-closure failure'. The assessment was then used to identify critical risk controls and assess their effectiveness as part of the targeted assessment programs.

Further information on the Regulator's risk assessment processes can be found at Regulating risks to rehabilitation.

The preventing controls that are critical to ensuring sustainable rehabilitation outcomes specific to tailings storage facility closure are identified by the blue text boxes in the abridged bowtie risk assessment diagrams below.

Click on image to expand

Click on image to expand

The Regulator takes into account several factors when assessing how mine operators identify, refine and implement controls to address risks for mine closure. For further information, refer to the Tailings management targeted assessment program in relation to the range of issues that are assessed by the Regulator as part of the tailings TAP for mine closure matters.