Supporting Technical Assessments

4 | P a g e Class 1 Storage Location Assessment_Oceana Gold NZ Ltd Wharekirauponga Underground Mine Global Seismic Solutions Ltd (GSS) was engaged by OGNZL to investigate an appropriate location and develop a site design for the class 1 storage facilities at WUG. In addition to legislative requirements, the site design assessment included safety, environmental and operational considerations. While class 5 substances will also be utilised by WUG mining operations, these are stored separately to class 1 substances and are the subject of another separate report. 3. Regulatory Compliance Considerations The ‘Health and Safety at Work (Hazardous Substances) Regulations 2017’ is the primary regulatory document for hazardous substances in the workplace. It references classes 1-9 including ‘use, storage, transportation, manufacture and disposal’. The regulation is derived from the overarching ‘ Health and Safety at Work Act 2015’. The ‘ Health and Safety at Work (Hazardous Substances) Regulations 2017’ outlines the compliance requirements and regulations regarding controlled zones and obligations of a ‘Person Conducting a Business or Undertaking’ or PCBU (refer to Section 9.27’ ). A controlled zone means : ‘An area abutting a hazardous substance location that is regulated so that’, — (a) within the zone, the adverse effects of a hazardous substance are reduced or prevented; and (b) beyond the zone, members of the public are provided with reasonable protection from those adverse effects In respect of compliance with r 9.27 , each surface connection from underground mining operations (ventilation shaft/ escape way/ primary access route) must be taken into consideration as an area in which blast over pressure may potentially vent from the underground operations in the event of an unintended detonation. New Zealand Regulations do not provide for specific direction in calculating such occurrences , however, in referencing ‘ Annex M’ of ‘International Ammunition Technical Guideline (IATG 2.20) Quantity and Separation Distances, Hazard division QD matrix for HD 1.1, (underground storage) ‘Table M.1’, such controlled zones can be estimated. Additional regulatory guidance that has been referenced in the assessment including: • International Ammunition Technical Guideline (IATG 1.80), ‘Formulae for Ammunition Management (United Nations - Safer Guard) (2nd Edition 01.02.2015); • International Ammunition Technical Guideline (IATG 2.20), ‘Quantity and Separation Distances (United Nations - Safer Guard) (2nd Edition 01.02.2015); and, • AS 2187.1 – Explosives – Storage, Transport and Use, Part 1; Storage. The ‘ Health and Safety at Work (Hazardous Substances) Regulations 2017’ also stipulates additional requirements of a PCBU in relation to mitigating risk from storage of class 1 substances including emergency response and requirements for competent person(s) to be in charge of such substances. 4. Proposed WUG Magazine Layout and Positioning The proposed magazine layout will consist of seven individual magazine chambers within the facility. Six of the chambers will be used for varying commercial High Explosives (H.E) and the remaining chamber will be used for the storage of Initiating Explosives (I.E).

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