SUSTAINABILITY

Operational status of dams and residue storage facilities

We acknowledge the severe adverse impact poor Residue Storage Facility (RSF) (previously referred to as Tailings Storage Facilities (TSF)) management can have on human lives, the natural environment and our business. To this end, Letšeng has reviewed all applicable international standards, codes and guidelines related to responsible RSF management and aligned our Residue Management System (RMS) to the Conformance Protocols on the Requirements of the Global Industry Standard on Tailings Management (GISTM) published by the International Council on Mining and Metals (ICMM). The RMS is a comprehensive framework that integrates people, resources, processes and practices related to RSF management to help the business achieve its performance objectives, manage risk and ensure safe, responsible management of its RSFs. The RMS is aligned and integrated with other relevant site-level systems, such as the site-wide environmental and social management system and systems related to water management.

Letšeng has two RSFs and one freshwater dam on site:

1. The Patising RSF, which is currently in use for the deposition of coarse and fine tailings from the treatment plants.
2. The Old RSF, has reached capacity and is no longer used for any tailings deposition. Plans for concurrent rehabilitation are currently being considered.
3. The Mothusi Dam, which is the mine’s freshwater supply source.

Letšeng’s RSFs and freshwater dam were constructed using the centre line and downstream tipping method, being a safer method of construction than the “upstream” construction methods used in most recent dam failures reported in the mining industry. The RSFs and freshwater dam are managed in accordance with the adopted industry best practices and governance structures. No areas of concern have been noted at the established governance forums and the operational parameters are in line with the set targets. The condition of the RSFs and all risk mitigation measures are continuously monitored and well managed. The appointed engineer of record (EoR) and Independent Tailings Review Board (ITRB) have conducted their periodic and annual inspections of the respective facilities and have not noted any issues or concerns related to the stability and management of these facilities. There were no incidents of compromised dam or RSF integrity in 2023 or prior thereto.

We recognise that ensuring the integrity of our RSFs and freshwater storage facilities is non-negotiable and integral in exercising our responsibility to safeguard our workforce, communities and environment to ensure business continuity. We remain focused and proactive in managing our RSFs according to adopted international best practice. Retaining structures and embankments undergo stringent safety monitoring in the form of inspections and audits, which are conducted both internally and externally at regular intervals throughout the year. Stringent inspections and monitoring on a daily, weekly and monthly basis include surveying various factors such as the densities of fines deposits, water levels, beach lengths and freeboard. Annual structural stability analysis is also conducted at our RSFs and an early-warning system, together with community training and awareness programmes, are used to ensure the emergency readiness of communities that could be affected in the unlikely event of a failure. The nearest village is located 20km downstream from the mine. The findings and recommendations stemming from these investigations and audits are reported quarterly to the Boards and Sustainability subcommittees at both operational and Group level.

An external consultant was appointed to investigate the founding conditions of the RSFs, construct stratigraphic models for each of those, and conduct a stability analysis followed by a review and update of the previous dam breach analysis that was conducted in 2020. From the study results it was concluded that the stability of the RSFs at current height complies with the minimum safety requirements. Based on the in-depth stability assessment conducted on the RSFs at final height, the overall stability exceeds requirements and liquefaction risk is considered low (and largely inconsequential if it were to occur). The most credible mode of failure associated with a far-reaching zone of influence is thus linked only to the escape of impounded water.

Governance framework

Our approach

It is our responsibility to guard our workforce, communities and the environment in which we operate against any potential risks posed by our operations. RSFs, while an integral part of mining, present a significant potential hazard if not responsibly managed and continuously monitored. Focused risk management is therefore crucial at every stage of the lifecycle of our RSFs.

In response to recent tragedies, the ICMM’s GISTM was established to achieve the ultimate goal of zero harm to people and the environment. The GISTM requires operators to take responsibility and prioritise the safety of RSFs through all phases of their lifecycles, including closure and post-closure. It also requires the disclosure of relevant information to support public accountability. Gem Diamonds has committed to and adopted the GISTM standards.

We recognise that ensuring the integrity of our RSFs and freshwater storage facilities is non-negotiable and integral in exercising our responsibility to safeguard our workforce, communities and environment to ensure business continuity. We take a focused and proactive approach to managing our RSFs according to appropriate international best practice. Retaining structures and embankments undergo stringent safety monitoring in the form of inspections and audits, which are conducted both internally and externally at regular intervals throughout the year. Stringent inspections and monitoring on a daily, weekly and monthly basis include surveying various factors such as the densities of fines deposits, water levels, beach lengths and freeboard. Annual structural stability analysis is also conducted at our RSFs and an early-warning system, together with community training and awareness programmes, are used to ensure the emergency readiness of communities that could be affected in the unlikely event of a failure. The nearest village is located 20km downstream from the mine.

The findings and recommendations stemming from these investigations and audits are reported quarterly to the Boards and Sustainability subcommittees at both operational and Group level.

The Global Industry Standard on Tailings Management

The GISTM is directed at operators and applies to RSFs, both existing and to-be-built. It makes it clear that extreme consequences to people and the environment from catastrophic RSF failures are unacceptable. To this end, operators must have zero tolerance for human fatalities and strive for zero harm to people and the environment, which is directly aligned to our safety culture. The GISTM provides the specified measures to prevent failure of RSFs and to implement best practices in planning, design, construction, operation, maintenance, monitoring, closure and post-closure activities.

Our dam and RSF management, monitoring and assurance strategy