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June 2025
Coordinates: Lat -19.9717°; Long -43.4803°
Guidance Note
Refer to our guidance note
Description and Lifecycle Design
The Grota I Filter Stack is a shared disposal facility for filtered tailings and waste rock, operated within the Córrego do Sítio (CDS) Complex, located in the municipality of Santa Bárbara, Minas Gerais, Brazil. The area is owned by AngloGold Ashanti (AGA), where gold is extracted, although the CDS Operations are currently under Care and Maintenance, therefore no deposition is currently taking place at the Grota I Filter Stack. The tailings generated from the filtration processes, as well as the waste rock resulting from overburden removal, will be directed to the structure once operations resume.
Phase 1 of the Grota I Filter Stack was designed with side slope faces at an angle of 1V:2.5H (21°), a maximum bench height of 10.0 meters, and berms with a width of 5.0 meters, resulting in a total maximum height of approximately 113.0 meters. Based on these geometric parameters, the final estimated storage capacity is approximately 6.2 million cubic meters of material (tailings and waste rock).
Grota I Filter Stack – General Information
| Facility Name | Grota I Filter Stack |
| Start of Operation | Co-disposal of waste rock and filtered tailings. |
| Maximum Licensed Stack Elevation | 965 m |
| Maximum Filled Elevation | 858,31 m |
| Current Height | 17 m |
| Licensed Volume | 6.200.000 m³ |
| Current Total Volume | 1.126.581,54 m³ |
| Licensed Area | 211.494 m² |
Consequence Classification
| GISTM Classification | Low |
Risk Assessment
AngloGold Ashanti’s comprehensive risk management system uses designs and controls to eliminate risks and where there are remaining risks, these are mitigated such that the residual risk is a As Low as Reasonably Practicable (ALARP).
Risk assessments are conducted by a multi-disciplinary team in collaboration with the Engineer of Record (EoR) for each facility in line with nationally or internationally accepted best practices. The risk assessment report provides a summary of the key details of the structure, including site investigations, geotechnical parameters, foundation conditions, embankment properties, drainage system details, spillway details, monitoring criteria, and the tailings disposal plan. It also details the risk-analyses methodology (using the qualitative bowtie method), potential failure modes along with their susceptibility and consequences, and the control and mitigation measures.
The risk analysis for the Grota I Filter Stack is currently in progress and due for completion in 2026.
Impact Assessment
The impact of a potential flow failure has been assessed considering the impact to human health and life, the environment, social and cultural impacts, as well as the infrastructure and economic impacts. These potential impacts have been used to inform the TSF Classification and the risk assessment consequence definition and the mitigation measures to be implemented.
Tailings flow if it occurred would be via natural topographic lows downstream of the facility, with limited flow volume being deposited. The tailings are geochemically consistent with the nearby orebodies from which they are derived and are non-acid forming. Environmental remediation would involve recovery of the sandy silt materials using earthmoving equipment.
Performance Reviews
AngloGold Ashanti has a comprehensive Tailings Review System which incorporates reviews from multiple levels and internal and external parties. All AngloGold Ashanti Filter Stacks are subject to the following reviews:
- Independent Tailings Review Board (ITRB) Review – Annually
- AngloGold Ashanti Corporate Review – Annually
- Monthly RTFE Assessment
| Reviews | Most Recent Review | Next Planned Review |
|---|---|---|
| ITRB | May 2025 | May 2026 |
AngloGold Ashanti has adopted the following ranking system for independent reviews:
Priority 1 – A stack safety issue considered immediately dangerous to life, health or the environment, or presents a significant risk of regulatory enforcement. Requires immediate action and to be completed as soon as practically possible but certainly within 2 months.
Priority 2 – If not corrected, a concern that could result in a stack safety issue leading to injury, health impact or discontinuity of operations. Requires immediate planning and completion by a date and specified by operations but as a minimum within 5-6 months
Priority 3 – Single occurrence of deficiency or non-conformance that alone would not be expected to result in stack safety issues, discontinuity of operations or regulatory intervention. Requires that measures be taken no later than a date that would prevent escalation, but no later than one year
Priority 4 – A recommendation based on good practice, improvement, or risk reduction. Recommendation towards best practices and mitigating risk associated.
No Priority 1 recommendations have been issued by the ITRB for the Grota I Filter Stack
Environmental and Social
Environment and Social monitoring programmes form part of AngloGold Ashanti’s Health, Safety, Environment (ISO14001) and Social Communities (HSEC) management systems, which act to fulfil the environmental social management system requirements under the GISTM. These environment and social monitoring programmes are comprehensively reviewed, and mitigation measures implemented as and where required. Further information on of our environment and social monitoring programmes, and performance results can be found in AngloGold Ashanti’s Sustainability Reports.
There is potential for ground water seepage from Filter Stacks and ground water conditions around all our Filter Stacks are regularly monitored. Where groundwater impact plumes exist, their migration is modelled and managed, as necessary to avoid interactions with potential receptors.
An easily accessible and effective grievance mechanism has been implemented so that any formal complaints can be submitted by stakeholders and resolved.
Emergency Response and Preparedness
Emergency preparedness and response planning (EPRP) to address the potential for failure of the Grota I Filter Stack is not required by Brazilian regulations since the facility is a stack. While an EPRP has not been prepared, AngloGold Ashanti has conducted pre-emptive emergency response activities in response to stability concerns related to Grota I Filter Stack and a comprehensive EPRP in line with the Dam Breach Analysis is being developed for this facility.
Financial Capacity
AngloGold Ashanti confirms it has adequate financial capacity to cover the agreed share of estimated costs of planned closure, early closure, reclamation, and post-closure monitoring and maintenance of the Grota I Filter Stack and its appurtenant structures.
Guidance Note
Certain statements contained in this document, other than statements of historical fact, including, without limitation, those concerning the economic outlook for the gold mining industry, expectations regarding gold prices, production, total cash costs, all-in sustaining costs, cost savings and other operating results, return on equity, productivity improvements, growth prospects and outlook of AngloGold Ashanti’s operations, individually or in the aggregate, including the achievement of project milestones, commencement and completion of commercial operations of certain of AngloGold Ashanti’s exploration and production projects and the completion of acquisitions, dispositions or joint venture transactions, AngloGold Ashanti’s liquidity and capital resources and capital expenditures, the consequences of the COVID-19 pandemic and the outcome and consequences of any potential or pending litigation or regulatory proceedings or environmental, health and safety issues, are forward-looking statements regarding AngloGold Ashanti’s financial reports, operations, economic performance and financial condition.
These forward-looking statements or forecasts are not based on historical facts, but rather reflect our current beliefs and expectations concerning future events and generally may be identified by the use of forward-looking words, phrases and expressions such as “believe”, “expect”, “aim”, “anticipate”, “intend”, “foresee”, “forecast”, “predict”, “project”, “estimate”, “likely”, “may”, “might”, “could”, “should”, “would”, “seek”, “plan”, “scheduled”, “possible”, “continue”, “potential”, “outlook”, “target” or other similar words, phrases, and expressions; provided that the absence thereof does not mean that a statement is not forward-looking. Similarly, statements that describe our objectives, plans or goals are or may be forward-looking statements.
These forward-looking statements or forecasts involve known and unknown risks, uncertainties and other factors that may cause AngloGold Ashanti’s actual results, performance, actions or achievements to differ materially from the anticipated results, performance, actions or achievements expressed or implied in these forward-looking statements. Although AngloGold Ashanti believes that the expectations reflected in such forward-looking statements and forecasts are reasonable, no assurance can be given that such expectations will prove to have been correct.
Accordingly, results, performance, actions or achievements could differ materially from those set out in the forward-looking statements as a result of, among other factors, changes in economic, social, political and market conditions, including related to inflation or international conflicts, the success of business and operating initiatives, changes in the regulatory environment and other government actions, including environmental approvals, fluctuations in gold prices and exchange rates, the outcome of pending or future litigation proceedings, any supply chain disruptions, any public health crises, pandemics or epidemics (including the COVID-19 pandemic), the failure to maintain effective internal control over financial reporting or effective disclosure controls and procedures, the inability to remediate one or more material weaknesses, or the discovery of additional material weaknesses, in the Company’s internal control over financial reporting, and other business and operational risks and challenges and other factors, including mining accidents.
For a discussion of such risk factors, refer to AngloGold Ashanti’s annual report on Form 20-F for the financial year ended 31 December 2024 filed with the United States Securities and Exchange Commission (SEC). These factors are not necessarily all of the important factors that could cause AngloGold Ashanti’s actual results, performance, actions or achievements to differ materially from those expressed in any forward-looking statements. Other unknown or unpredictable factors could also have material adverse effects on AngloGold Ashanti’s future results, performance, actions or achievements. Consequently, readers are cautioned not to place undue reliance on forward-looking statements.
AngloGold Ashanti undertakes no obligation to update publicly or release any revisions to these forward-looking statements to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events, except to the extent required by applicable law. All subsequent written or oral forward-looking statements attributable to AngloGold Ashanti or any person acting on its behalf are qualified by the cautionary statements herein.