Supporting Technical Assessments

11 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 The proposed underground Class 1 explosives storage facility is proposed to be situated 317 m below the surface to service the underground mining operation. The existing surface sites will continue to operate as secure intermediary stores for explosives prior to transfer to the underground facility. These activities are considered to be existing and due to the separation, there are no cumulative effects between the existing storage and proposed storage. Figure 3.3: Indicative locations of existing and proposed OGNZL’s Class 1 storage activities Source: Aerial imagery from Esri World Imagery Map The relocated LPG tanks will be approximately 750 m from the proposed new Class 1 explosives store. Cumulative effects are not anticipated at this range. 3.5 Hazardous substances 3.5.1 Overview The substances associated with the Processing Plant, WTP and Development Site at Waihi are assigned hazardous classifications under the Hazardous Substances and New Organisms Act 1996 (HSNO). A new hazard classification system came into force in New Zealand on 30 April 2021 to align with the Globally Harmonised System. Both the former classifications from the safety data sheet and the equivalent new classification have been presented for each substance. The former classifications are used throughout this report for brevity, as they are still commonly used and understood in New Zealand. 3.5.2 Processing Plant, WTP and relocated Development Site operations The volumes, classifications and location of hazardous substances associated with the Processing Plant, WTP and the relocated activities at the western portion of the Development Site are set out in Table 3.2 below. Class 1 explosives proposed for the new store on the Development Site are detailed in Section 3.5.3. 2.2 km 1.2 km 2.9 km

RkJQdWJsaXNoZXIy MjE2NDg3