Supporting Technical Assessments

31 Tonkin & Taylor Ltd Hazardous Substances Technical Assessment – Waihi North Project - Storage and use of hazardous substances at Willows Road site and the Wharekirauponga Underground Mine Oceana Gold (New Zealand) Limited June 2022 Job No: 1015212.1000 vRev0 Figure 5.1: Overpressure zones offset distances Source: GSS (October 2021) As identified onFigure 5.1, the 2 kPa blast overpressure radius crosses the site boundary at the northeast (Zone A) and southwest (Zone B) of the proposed stores. The underlying land zone for the neighbouring property to the southwest is Rural and to the north is Conservation (Indigenous Forest) Zone. There are no dwellings in the overlapping area, however there is a farm shed approximately 500 m south of the magazines’ location. People present in these areas could experience up to 5 kPa overpressure in a worst-case scenario in Zone B at the closest point to OGNZL’s boundary west of the surface magazine compound. The properties that are overlapped by the 2 – 5 kPa blast overpressure zone have been evaluated to determine whether the underlying zoning in the HDP permits the construction of vulnerable facilities in Table 5.2 below. Quantitative analysis of the consequence of exposure to this level of overpressure is provided in Section 7.3.2.1. The purpose of the requirement to exclude these activities from the 2kPa overpressure radius in the HSW-HS is to protect vulnerable facilities from effects in an explosion scenario. Therefore, compliance with these requirements ensures that impacts on sensitive activities are minimised. Table 5.2: Assessment of potential for establishment of Vulnerable Facilities at off-site properties in the 2 kPa blast overpressure zone Vulnerable facility definition (HSW-HS 2017) Conservation (Indigenous Forest) zone Rural zone Buildings of 4 storeys or more, of curtain wall construction with panels more than 1,500 mm square: Not permitted – height restriction of 6 m (permitted) and 8 m (RD) Not permitted - Only dwellings and buildings accessory to farming permitted.

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