Supporting Technical Assessments

38 Tonkin & Taylor Ltd Hazardous Substances Technical Assessment – Waihi North Project - Waihi Processing Plant, Water Treatment Plant and Development Site Oceana Gold (New Zealand) Limited June 2022 Job No: 1015212.1000 vRev0 Substance Hazard Class Proposed maximum storage volume Delivery schedule Delivery volume Hydrochloric Acid (>25%) 6.1B, 8.1A, 8.2Bm, 8.3A, 9.1D, 9.3C 24,000 L Every two weeks 7,000 L Oxygen gas 5.1.2A 30,000 L Weekly 25,000 L Carbon Dioxide Not classified as hazardous 40,000 kg/L Weekly 5,250 kg/L LPG 2.1.1A 80,000 L 6 monthly 26,000 L Diesel 3.1D, 6.1E, 6.3B, 6.7B, 9.1B 200,000 L Sporadically for most tanks Twice weekly for the tank servicing the mine. 19,500 L Workshop Maintenance oils and greases* 6.1D, 6.1E, 6.3A, 6.4A, 6.5B, 6.9B, 9.1B, 9.1C 16,000 L Weekly 3,000 L Transformer oil 6.1E 8,640 L Transformer oil replacement anticipated to be rare occurrence. - Cyanide (Liquid 30%) 6.1B, 9.1C, 6.5B, 6.8B, 6.9A, 8.1A, 8.2B, 8.3A, 9.1A, 9.2A, 9.3A, 9.4A., 112,000 L Monthly 20,000 L Cyanide (solid) 6.1B, 6.1C, 6.3B, 6.4A, 6.5B, 6.8B, 6.9A, 8.1A, 9.1A, 9.2A, 9.3A, 9.4A. 77,180 kg Monthly 22,000 kg Ferric chloride 6.1D, 8.1A, 8.2C, 8.3A, 9.3C 30,000 L Monthly 8,000 L Hydrogen peroxide 5.1.1B, 6.1D, 8.2B, 8.3A, 6.9B, 9.1D, 9.3C 35,000 L 6 monthly 23,000 L Mercury 6.1B, 6.5B, 6.8A, 6.9A, 8.1A, 9.1A, 10 kg Not delivered, removed when required. 10 kg ANFO 1.1D, 6.1D, 6.3B, 6.4A, 6.7B, 9.1D, 6400 kg (NEQ) Weekly 2,000 kg (NEQ) Booster 1.1D, 6.1C, 6.9B, 9.1B,

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