Executive summary OceanaGold (New Zealand) Limited (OGNZL) is seeking resource consent from the Hauraki District Council (HDC) and Waikato Regional Council (WRC) for the activities required to establish a new mining operation in the Wharekirauponga Valley. This new mine, referred to as the ‘Wharekirauponga Underground Mine’ (WUG), is part of the Waihi North Project (WNP) to extend the life of mining activities in Waihi. The WUG is located approximately 10 km north of the township of Waihi. The resource lies beneath the Coromandel Forest Park administered by the Department of Conservation (DOC) and within the Wharekirauponga Minerals Mining Permit (60541) area. This hazardous substances technical assessment has been prepared to evaluate the effect of hazardous substance storage and use associated with the establishment of the WUG and the mine access tunnel, which has a portal entrance on land owned by OGNZL on Willows Farm, Waihi. Hazardous substances will be both stored and used on the surface at Willows Road and underground within the tunnel and mine, which extends beneath the Coromandel Forest Park. The activity will include the storage and use of explosives, oxidising and toxic substances, workshop gases, fuels, maintenance oils and greases at the surface and within the underground mine. The storage and use of hazardous substances in New Zealand is governed primarily by the Health and Safety at Work (Hazardous Substance) Regulations 2017 which sets out control measures triggered by the volumes and types of hazardous substances proposed. Hazardous substance storage and use is further controlled by Resource Management Act 1991, exercised through Chapter 7.7. of the Hauraki District Plan (HDP). The proposed activity requires resource consent in accordance with the HDP Rule 7.7.10 as a non-complying activity for use of hazardous substances in the Conservation (Indigenous Forest) Zone at the WUG mine. This assessment has evaluated the hazards and risks in accordance with the Ministry for the Environment Guidance for Hazardous Facilities ME339 (2000), with supplementary guidance from the New South Wales Department of Planning’s Hazardous Industry Planning Advisory Paper series. The key risks identified for the Willows Road tunnel portal site and WUG mine include: Risk to people or property from fire or detonation at the explosives magazines, oxidiser storage area or diesel tanks; Risk to ecosystems from a spill of diesel during tank filling or equipment refuelling; and Risk to ecosystems from a spill of packaged goods during unloading to site. The risks to people, property and the environment from an unintended detonation at the proposed explosives storage locations is assessed as low and will be managed through site and equipment design (e.g. separation distances to offsite locations and other explosives stores, provision of fire protection systems and certification of the explosives storage magazines) and management controls (personnel access restrictions, security monitoring, staff training and handler certification, and emergency response plans). The surrounding areas at the surface at Willows Road and in the Coromandel Forest Park above the WUG are considered sensitive to the effects of an unintended detonation. However, taking into account the proposed controls and distance to sensitive land uses, the effects on offsite people and property from the proposed hazardous substances storage has been assessed as less than minor. Similarly, the impact of a detonation of the Class 1 explosives in the WUG has potential to impact people in the Coromandel Forest Park in the vicinity of the mine ventilation stacks. A quantitative assessment of the effect using dispersion modelling was undertaken in an Air Quality Assessment,
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