48 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 entrance, or stored underground in a services bay. Gasser does not have an environmental hazard but will likewise be stored in a bunded storage shed. The greatest risk that has been identified which could result in an off-site environmental effect is an accidental release of diesel during delivery by truck to the services bay at the surface or the underground refuelling units, refuelling of the generator or fire pumps at the SFA or during the refilling of the mechanical equipment. All refuelling activities will be undertaken by trained staff prepared to carry out emergency response measures in the event of a small spill. The diesel refuelling facilities are designed with interlocks to prevent overfilling of the tank or equipment. The refuelling of equipment will be undertaken by trained staff, with access to spill kits for spill response. The areas where diesel and oils are stored and where refuelling takes place are bunded to prevent storm-water ingress and the pads drain to treatment prior to discharge to the environment. All storage of hazardous substances will also be undertaken in compliance with the HSW-HS requirements which include requirements on separation between materials, secondary containment and certification. All hazardous substances will be transferred to their storage locations within appropriate timeframes of their arrival on site. Provided the controls and mitigations are in place as outlined above, the effects on the environment are expected to be less than minor. 8.2.3 Cumulative effects The substances proposed to be stored at the surface with potential for off-site effects are Class 1 explosives at the magazine compound and the Class 5 oxidising substances at the SFA at Willows Rd, the greatest risks being accidental detonation or ignition. The surface infrastructure area is located beyond the 2 kPa overpressure radius of the magazine compound, and is not expected to be impacted by an unintended detonation at this distance. There are no other stores at proximity to the proposed site storing explosive or oxidising substances. Similarly, the underground Class 1 explosives and Class 5 oxidisers are separated by more than 100 m at the shortest distance to minimise the cumulative impacts of an event at either store. The remote locations underground beneath the Coromandel Forest Park provides significant separation to any other hazardous facilities in the area. Each hazardous substance store is managed in accordance with the controls described in Section 4 and the chance of simultaneous failures and cumulative effects is low. Other chemicals that will be stored on-site with potential for off-site effects are diesel, gasser, oils and greases. The greatest risks being a spill during substance unloading to site or refilling of the equipment. Refuelling of drilling equipment at any of the previously established drill sites and water pump locations in the Coromandel Forest Park is the only comparable activity in the vicinity. Each drill site is managed in accordance with the controls described in Section 4 and the chance of simultaneous failures and cumulative effects is negligible. 8.2.4 Transport Any transport of hazardous substances will be in accordance with the Land Transport Rule: Dangerous Goods 2005 and, when on site, all transport of explosives is carried out under the supervision of a Certified Handler. These measures are considered sufficient to ensure that the environmental effects arising from the transport of hazardous substances will be less than minor.
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