28 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 State Hazard Class Proposed maximum storage volume Storage location description Secondary containment minimum requirement (HSW-HS regulation ref) LPG Gas 2.1.1A 80,000 L Two pressure vessels (40,000 L each), moving to the western portion of the Development Site central to OGNZL landholding Secondary containment not required for gases Diesel Liquid 3.1D, 6.1E, 6.3B, 6.7B, 9.1B 200,000 L Various units: Selfbunded isotainers (40,000 L) or portable tanks (<6,000 L) Containment for at least 110% capacity of the largest container (r17.100) or integral containment1: Integral containment (double skin) provided for each tank. Workshop Maintenance oils and greases* Liquid 6.1D, 6.1E, 6.3A, 6.4A, 6.5B, 6.9B, 9.1B, 9.1C 8,000 L at each workshop Various units (tank, IBC or 205 L drum) located at each workshop Containment for at least 25% TPP or 110% of the largest container whichever is greater (r13.33): 2,000 L Transformer oil Liquid 6.1E 8,740 L Two 3,500 L capacity transformers and one 1,740 L transformer Containment for at least 110% of the largest container (r13.33): 9,610 L Note that the transformer design provides 150% containment: 13,110 L Cyanide (Liquid 30%) Liquid 6.1B, 6.1C, 6.5B, 6.8B, 6.9A, 8.1A, 8.2B, 8.3A, 9.1A, 9.2A, 9.3A, 9.4A. 112,000 L Tank within the Processing Plant. Located on the eastern side of the reagent storage. Containment for at least 110% capacity of the largest container (r17.100) or integral containment1: 123,200 L Cyanide (solid) 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 Boxed storage within the Processing Plant. Located on the eastern side of the reagent storage. Secondary containment not necessary for solid substance Ferric chloride Liquid 6.1D, 8.1A, 8.2C, 8.3A, 9.3C 30,000 L Two tanks (20,000 L and 10,000 L) in the WTP Containment for at least 110% capacity of the largest container (r17.100) or integral containment1: 112,200 L
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