34 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 Ref Exclusion from zone Blast overpressure Max. offset distance Comment r 9.27 (2)(c)(i) Public traffic routes of high density, areas of high intensity land use, or any area where a person may be legally present inside the boundary of the place where the hazardous substance location is located 5 kPa 4.4 m ventilation shaft is securely fenced-off in a 10 m x 10 m compound such that in practice the public would not be within the 13 kPa overpressure radius. r 9.27 (2)(d) Vulnerable facilities defined in the HSW-HS regulations as: h) buildings of 4 storeys or more, of curtain wall construction with panels more than 1 500 mm square: i) buildings of 4 storeys or more with more than 50% of the wall area glazed: j) a hospital care institution, residential disability care institution, or rest home (as defined in section 58(4) of the Health and Disability Services (Safety) Act 2001), early childhood education and care centre (as defined in section 310 of the Education Act 1989), or school (as established under section 146 of the Education Act 1989): k) public buildings or structures of historic value: l) major transport and traffic terminals such as railway stations and airports handling more than 1 800 people in 24 hours: m) major public utilities whose service could be disrupted by a blast of 5 kPa: n) any similar facilities. 2 kPa 4.7 m There are no structures meeting the definition of vulnerable facilities located in the vicinity of the surface vents, nor is construction of any such structures anticipated in the Coromandel Forest Park in Wharekirauponga or at the OGNZL owned Willows Road site. This radius will extend 2.5 m from the perimeter fence in the maximum case. r 9.27 (4) A PCBU with management or control of a hazardous substance location that is used solely for securing and holding a class 1 substance must limit the quantities of any class 1 substance at the location to ensure that, in the event of an unintended initiation - the interior of any proximate building where a class 1 substance is manufactured would not be subject to a blast overpressure of more than 24 kPa. 24 kPa 1 m There are no Class 1 manufacturing operations either existing or proposed within the radius described at any of the surface connections. It is considered that the controlled zones are restricted to sufficiently minimise the risk to the public. Theoretically, the 2 kPa overpressure zone extend up to 2.5 m beyond the fence perimeter for the surface connections in the Coromandel Forest Park. However, given the conservative nature of the
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