Supporting Technical Assessments

20 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 These procedures ensure that staff are trained to identify the hazards associated with each substance and implement measures to prevent spills or fires (depending on the nature of the hazard), minimising the chance of adverse effects at off site locations. This HSMP currently applies to OGNZL’s activities in Waihi, and will be updated to address any sitespecific hazards associated with the WUG and Willows Road site prior to commission. 4.4 Explosives hazard management 4.4.1 Explosives management plans and responsibilities ThePrincipal Hazard Management Plan (PHMP) for Surface Explosives and the PHMP for Underground Explosives set out the details of management of all aspects of storage, handling and use of explosives at the existing Waihi mining operation. Hazard management to minimise the risk of an unintended detonation is critical to worker safety on site, as well as for prevention of on-site property damage. Measures to manage the risk of a detonation incident will also minimise the potential for effects on off-site receptors. These PHMPs are attached as Appendix DandAppendix F respectively. The proposed magazines will be managed in accordance with the existing procedures for explosives management set out in these management plans. These plans will be updated to address the site-specific matters relevant to the proposed Class 1 storage areas associated with the WUG prior to each site’s commission. The key roles with responsibilities for control of hazards associated with the explosives storage and use on site include:  Magazine keeper – responsibilities include housekeeping and maintenance of the explosives storage site, signage and locking devices; upkeep of all documentation (licences, certifications and inventory records); and access to keys to magazine site.  Approved handlers – Certified for safe handling of explosive substances by a WorkSafe accredited external certifier; responsible for supervising all movements of explosives and equipment on site. 4.4.2 Security The proposed explosives storage locations will be securely fenced, and only certified personnel will be authorised to access the keys to the storage site. All sign-outs and returns of the keys are logged in a register and all keys are verified as returned by the magazine keeper at the end of each day. The storage area at the surface will also be equipped with a point-to-point laser system monitored continuously by site Security, which may only be deactivated by site Security for access by authorised personnel. A remote camera system may additionally be installed. A security camera will be installed to monitor the gate areas of the underground storage facilities. These cameras are proposed to be monitored by OGNZL security staff. These security measures will limit access from unauthorised personnel to reduce the likelihood of error, tampering or theft that could cause an incident. 4.4.3 Fire protection systems The proposed explosives magazines at the surface will be equipped with a heat sensing ‘dry riser’ sprinkler fire suppression system. In addition, two dry chemical powder fire extinguishers (Rating: 30B) are required by the HSW-HS regulations.

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