IGO SUSTAINABILITY REPORT 2020

Mineral residue management Nova Operation IGO’s mineral waste material includes tailings and waste rock, the two largest mining-related waste streams produced at our operations. Management and storage of waste rock and the processed mineral tailings is a critical issue for our industry. It represents a social, safety and environmental challenge that we are determined to meet. The effective management of the storage of tailings requires rigorous design practices, comprehensive monitoring and management programs, independent auditing and strict corporate governance oversight. IGO manages one operating Tailings Storage Facility (TSF) at the Nova Operation, which is fully lined and has been engineered for the life of the mine. Mineral waste management at IGO-operated assets are subject to our Group Environmental Standard 3 – Mineral Waste Management which applies to the management of waste rock and tailings. This standard requires the development of a tailings management plan, which includes a risk assessment completed in accordance with IGO’s Common Management System Standard 3 – Risk Management. As part of our ongoing tailings management process, IGO maintain an annual audit schedule to ensure that our practices at IGO-operated facilities conform to our Group standards and are being operated in accordance with the mine’s operating strategy, safety conditions, prescribed premises conditions, and mining tenement conditions. We use independent external reviews to provide us with the confidence that our facilities are conforming to regulations. During the FY20 annual audit schedule, IGO commissioned SRK Consulting to review the ongoing operational, management and monitoring aspects of the Nova Operation TSF in line with IGO management standards and regulatory licence conditions. In previous financial years, SRK Consulting completed a dam breach assessment at Nova to examine various worse-case credible case dam breach scenarios and define the likely area of impact given a dam breach and the catastrophic release of tailings. This study validated the original dam breach assessment completed as part of the Operation's pre-feasibility study. Finally, we have undertaken a high-impact function audit, completed by Klohn Crippen Berger, in which no issues were identified with respect to integrity of the dam. The location of the TSF at the Nova Operation is remote from local communities and public infrastructure. The studies and audits conducted to date provides us with an acceptable level of assurance that impacts from a dam failure will be contained within IGO’s mining lease boundaries. Risk management systems are in place for operational facilities to mitigate potential impacts on employees and contractors in the event of a dam failure. This includes maintaining current emergency response plans in accordance with our Common Management System Standard 13 — Emergency Preparedness and Business Continuity Planning. EVALUATION OF TSF MONITORING TECHNOLOGIES In the aftermath of the recent spate of tailings storage facility (TSF) failures, there has been a significant increase in activity relating to their monitoring. To play our part and drive future management improvements, IGO collaborated with Amira Global in sponsoring a project to evaluate TSF monitoring technologies. A focus of this project is to provide an independent evaluation of a range of monitoring technologies, and their suitability, for the application of providing advance warning of potential instabilities of TSFs. This will be achieved through an integrated program of laboratory and field testing as well as physical and numerical modelling of selected sites. Managing the storage of mineral tailings is a critical issue for our industry, and we are proud to play our part. The Nova Operation deposited 1,293,793 tonnes of dry tailings in FY20. There were no significant incidents associated with the Nova TSF during the financial year. Likewise, there were no uncontrolled releases from the facility, nor any associated material fauna losses. IGO supports the need for the public disclosure of TSF management practices, and actively participates in external requests for information. We continue to support the investor led Church of England Pensions Board Mining and Tailings Safety Initiative and have provided a response to its request for disclosure of TSF management information, which is available on our website. Waste rock generated from our operations is stored and managed in accordance with statutory guidelines and IGO standards. In FY20, the Nova Operation generated 187,153 tonnes of waste rock, a 57 per cent decrease on FY19, representing improved management practices and the deliberate use of waste rock as backfill underground. Additional tailings and waste rock data can be found in the performance data on page 97. Tropicana Operation At the Tropicana Operation, waste rock and tailings are the main waste streams generated. In addition to the gold bearing ore, waste rock is extracted from the various pits during the mining process. Some of this material is classified as potentially acid-forming due to its high sulphur content which, if left unmanaged and exposed to the elements, could potentially generate acid and/or metalliferous drainage (AMD). A waste rock management strategy is employed to mitigate possible downstream impacts to biota and groundwater. The encapsulation of potentially acid- forming waste with benign material is the principal method to prevent AMD generation. During FY20, the Tropicana Operation produced 81.7Mt of waste rock. Tailings produced from the processing plant are pumped into the purpose- built, single-cell TSF. The main environmental consideration in managing water in the TSF is to minimise the presence of weak acid dissociable (WAD) cyanide in the tailings liquor. WAD cyanide is toxic to fauna. Given water bodies are very attractive to avifauna in arid environments, the presence of WAD cyanide in the water contained in a tailings dam presents both a lure and a threat to the bird life. In response, water recovered from the surface of the TSF is reused within the processing circuit, contributing to high salt content and hypersaline classification. Hypersalinity is used as a wildlife protection mechanism, preventing them from drinking the water and coming into direct contact with WAD cyanide tailings. Within this context, it should be noted that there have been no material numbers of fauna fatalities at the Tropicana TSF. In FY20, the Tropicana Operation deposited 9.58Mt of dry tailings into its storage facility. Additional Tropicana environmental data is located within the performance data on page 100. Nova Operation Tailings Storage Facility 56 — IGO SUSTAINABILITY REPORT 2020 IGO SUSTAINABILITY REPORT 2020— 57 RESPONSIBLE OPERATIONS