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Siguiri TSF, Guinea
At 10 April 2024
Coordinates: Lat 11.518565°, Long -9.409338°
Guidance Note
Refer to our guidance note.
Description and Lifecycle Design
The Siguiri Gold Mine is located approximately 29km southeast of Siguiri Town in Guinea, West Africa.
The TSF is in a natural basin, closed by an earth fill starter embankment, six kilometres to the south of the plant. The initial design life was seven years up to 2011 but this has been extended after the wall raising method was changed. The wall has been raised in an upstream method using the underflow fraction of cycloned tailings. Currently the walls are raised in a combination of upstream and downstream methods that has been enabled by vacuum cycloning.
The construction of a storm water attenuation dam enabled storm water to be drawn off the TSF instead of being attenuated on the TSF. A further extension had been proposed requiring the installation of toe and elevated drains at the TSF walls.
AngloGold Ashanti has an internal corporate tailings management team and has appointed an internal Responsible Tailings Facility Engineer (RTFE) an external Engineer of Record (EoR) and an Independent Tailings Review Board (ITRB) at this facility to oversee and govern the operations, maintenance and surveillance (OMS) of the facility.
Siguiri TSF General Information
| Facility Name | Siguiri TSF |
| Period of Operation | 2005 – present |
| TSF Classification | SANS 10286 – High GISTM – Very High |
| Construction Method | 2005 – 2007 Downstream laterite impoundment 2007 – 2011 Upstream cyclone underflow impoundment 2011 – Present: Main wall: downstream cyclone underflow Saddles: combination of up- and down-stream cyclone underflow |
| Deposition Method | Single cell, rotational sub-aerial spigot deposition and rotational cyclone deposition. |
| Target Annual Production Rate | 12 Mtpa |
| Current Tailings Volume / Tonnage | 202 Mt |
| Designed / Licensed Volume / Tonnage | 238 Mt |
| Estimated End-of-life | 2035 Design to increase the TSF capacity is in progress |
| Current Crest Elevation | 435.3 mamsl at the Main Wall |
| Final designed/licensed crest elevation | Design to increase the TSF capacity is in progress |
| Current Maximum Embankment Height | ~54m |
| Outer Wall Profile | 1V:3H |
Consequence Classification
| TSF Classification | Very High |
Risk Assessment
AngloGold Ashanti’s comprehensive risk management plan aims to implement designs and controls in a way that risks are eliminated risks and where any risks remain, these are mitigated so that the residual risk is a As Low As Reasonably Practicable (ALARP).
Risks are considered in the design stages with mitigation measures incorporated into the design features and operational procedures. Risks are also identified and mitigated through numerous layers of reviews and inspections with follow up actions and recommendations developed to mitigate identified risks. The Siguiri potential failure modes assessment has been completed with the failure modes and effects assessment planned for 2024. The assessment will be conducted with a multi-disciplinary team and in collaboration with the Engineer of Record (EoR) in line with accepted best practices.
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 also the risk assessment consequence definition and the mitigation measures to be implemented.
Modelling of a potential failure indicates that the areas northeast and south of the Siguiri TSF could be affected and could impact human settlements, farming, and water resources. These impacts will be confirmed by the detailed assessments and EPRP development.
Performance Reviews
AngloGold Ashanti has a comprehensive Tailings Review System which incorporates reviews from multiple levels and internal and external parties. All AngloGold Ashanti TSFs are subject to the following reviews:
- EoR Inspections – typically quarterly and Annual Performance Reviews
- Review – Annually
- AngloGold Ashanti Corporate Review – Annually
- Independent 3rd Party Regulatory Review – Annually
- Dam Safety Review (DSR) – Typically every five years
| Reviews | Most Recent Review | Next Planned Review |
|---|---|---|
| EoR | Dec 2023 | Q1 2024 |
| ITRB | May 2023 | June 2024 |
| DSR | N/A | 2026 |
AngloGold Ashanti has adopted the following ranking system for independent reviews: Priority 1 actions are classified as a material finding.
Priority 1 – A dam safety issue considered immediately dangerous to life, health or the environment, or at significant risk of regulatory enforcement.
Priority 2 – If not corrected, a concern that could result in a dam safety issue leading to injury, health impact or discontinuity of operations.
Priority 3 – Single occurrence of deficiency or non-conformance that alone would not be expected to result in dam safety issues, discontinuity of operations or regulatory intervention.
Priority 4 – A recommendation based on good practice, improvement, or risk reduction.
Summary of Material Findings and Mitigation Measures:
| Reference | Material Finding | Mitigation Measures to Meet ALARP |
|---|---|---|
| 2022 Stability Report | Low safety factors at the saddle walls 1-4. | Deposition from the Saddle 1/2/3 was stopped in November 2022 and buttressing was started in February 2023 with completion expected in 2024. |
| 2023 ITRB Report |
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 fulfill 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 TSFs and ground water conditions around all our TSFs are regularly monitored. Where groundwater impact plumes exist, their migration is modelled and managed, as necessary to avoid interaction(s) with potential receptors.
No material findings were made in relation to the Siguiri TSF in 2023.
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
The mine has developed an emergency management plan which identifies potential events and incidents, defines those personnel responsible for implementation of the response, and describes procedures for notification, communication, and escalation of the emergency response.
The emergency preparedness and response planning specific to modelled potential failure scenarios of the Siguiri TSF is under way and we are targeting end 2025 to have these formally developed.
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 Siguiri TSF and its appurtenant structures.
Guidance Note
This document provides the information required under Requirement 15.1.B of the GISTM.
This document should be read in conjunction with the information relating to AngloGold Ashanti’s tailings management practices that is available on the AngloGold Ashanti website, as well as the risk factors and other disclosures in AngloGold Ashanti’s annual report on Form 20-F for the year ended 31 December 2023 to be filed with the United States Securities and Exchange Commission (SEC) (the “Form 20-F”).
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, all-in 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.
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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 of this document 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.