6 | P a g e Class 1 Location Assessment Willows Road - Surface Magazine, WUG - Waihi North Project . ‘Figure 2 – Site layout’ 4.1. Operational and Product Storage Capacity Requirements Project consumption forecasts estimate that stored quantities of approximately 7,360 kg will be required. It is forecast that restocking of class 1 substances will be required on a weekly basis. During peak usage periods, a more frequent replenishment program may be required. The proposed storage would typically consist of up to approximately 10,000 detonators (I.E – 10 kg NEQ), and an aggregate quantity of up to ~7,350 kg NEQ of High Explosives (H.E). The stored H.E component would comprise varying commercial explosive substances based on operational requirements. Depending upon operational mining conditions, the mining process will utilise an ammonium nitratebased emulsion product (A.N.E) as the bulk explosive component. This would be stored on site as a ‘class 5 substance’ at a separate and approved location. This class 5 substance is sensitised during loading operations to become a class 1 explosive. This strategy would reduce the reliance on storing larger quantities of bulk commercial explosive products on site. A separate independent report has been prepared for class 5 storage. 4.2. Controlled Zone Considerations Part 9. r. 9.27 of the ‘ HSW (Hazardous Substances) Regulations 2017’ explain that the ‘PCBU is to control adverse effects of unintended initiation’. One method of achieving compliance with this section of the regulations is by way of managing the ‘controlled zones’. There are varying ‘overpressure’ (kPa)’ threshold criteria (Section ‘r 9.27’ ) applied to class 1 locations that relate to the different controlled zones. The overpressure thresholds are proportional to the stored NEQ. The potential effects on nearby infrastructure/ buildings/personnel in the event of an unintended detonation are considered when determining stored NEQ. In addition to managing controlled zones, evacuation zones may be an appropriate means of achieving compliance with regulatory requirements by limiting risk exposure to people (by way of 220 m NORTH Class 1 storage area compound Proposed site infrastructure Red line indicates boundary with neighbouring properties Proposed portal entrance
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