Supporting Technical Assessments

44 Tonkin & Taylor Ltd Hazardous Substances Technical Assessment – Waihi North Project - Waihi Processing Plant, Water Treatment Plant and Development Site Oceana Gold (New Zealand) Limited June 2022 Job No: 1015212.1000 vRev0 Vulnerable facility definition (HSW-HS 2017) Rural zone 4. public buildings or structures of historic value: None existing. 5. major transport and traffic terminals such as railway stations and airports handling more than 1 800 people in 24 hours: Not permitted. 6. major public utilities whose service could be disrupted by a blast of 5 kPa: None existing. 7. any similar facilities. None existing. The overpressure radii do not overlap any of the hazardous substance storage associated with the Processing Plant, WTP or any of the existing or proposed explosives stores in Waihi. At this distance, there are unlikely to be any cumulative impacts on these activities from an unintended detonation at the Development Site. 7 Risk assessment for hazardous substances 7.1 Introduction The following sub-sections set out a risk assessment of the proposed storage and handling of hazardous substances at OGNZL’s sites for the proposed storage volumes. The risk assessment involves consideration of:  Identification of potential hazards, failure modes and exposure pathways;  The sensitivity of the surrounding environment;  The separation distances from neighbouring activities and the number of people potentially at risk from the facility;  Cumulative risks of hazardous facilities in the area; and  Transport of hazardous substances on and off the site to ensure safe access and appropriate routes for delivery vehicles on site to minimise risk of spillage. 7.2 Assessment method In the absence of New Zealand specific guidance, the New South Wales Department of Planning (NSW DoPI) Multi-Level Risk Assessment19 approach was considered in development of the methodology for this assessment. The Multi-Level Risk Assessment approach is summarised inFigure 7.1. There are three levels of assessment, which are:  Level 1 – Qualitative Analysis, primarily based on the hazard identification techniques and qualitative risk assessment of consequences;  Level 2 – Partially Quantitative Analysis, using hazard identification and the focused quantification of key potential offsite risks; and  Level 3 – Quantitative Risk Analysis (QRA) based on the full detailed quantification of risks, consistent with Hazardous Industry Planning Advisory paper No.6 – Guidelines for Hazard Analysis. 19 Assessment Guideline Multi-Level Risk Assessment, New South Wales Department of Planning, 2011

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