Waihi Underground Explosive Principal Hazard Management Plan Approved by: SSE/ General Manager Approval Date:11/05/2021 Next Review: 08/04/2022 OceanaGold Waihi Document ID: WAI-400-PLN-007 Page 16 of 27 The face and surrounding areas must be scaled from top down before any charging commences. No one is to work under unsupported ground. The charge basket is to be cleared of any materials associated with charging prior to starting scaling. The face must be charged top down. The electric detonator is not to be connected until as close as practical to the firing time. 6.3.3 Signs The appropriate signs must be hung during charging activities and include “Danger - Charging in Progress”, “Danger – Explosives” and “No Unauthorised Entry”. When charging is complete a “Danger – Charged Face” must be hung across the drive. No one can proceed past this sign without permission from the Shotfirer. For full details refer to the underground development charging procedure; see Appendix I for document details. 6.4 Firing 6.4.1 Initiating Blasts Any explosive can only be fired by the Charge-Up Operator with the approval of the Shift Supervisor. The Charge-Up Operator is responsible for correct and complete performance of site procedures, including but not limited to: • Clearing the heading prior to firing • Placement of appropriate signage • Correct hook up procedures • Requesting the Shift Supervisor to clear the tag board • Requesting permission to fire from the Shift Supervisor • Initiating the blast notification device • Initiating the blast, twitching the firing lines and restarting the ventilation fan (if appropriate) • Communicating all firing information to their Underground Shift Supervisor 6.4.2 Designated Firing Positions Generally, all firing will take place at the Designated Firing Point (DFP) at the tag board with the backup position being the portal firing point. However, if another location is to be used it must be approved by the Underground Mining Manager and be subject to a risk assessment. The new location must: • Be in a fresh air intake which will not be exposed to any fumes from the blast • Have appropriate ground support including mesh and/or shotcrete • Be at least 300 metres away or around two corners from the blast • Be at least 20 metres away from any vent doors, brattices or suspended vent fans • Be checked for intersections with diamond drill holes and have any such hole grouted if it has the potential to intersect the orebody or any development. • Where applicable, be in an area with good radio or telephone communication to the surface 6.4.3 Firing Cable Firing cable is to be maintained from the DFP to within 100 metres of the face. All joins in the firing cable must be done correctly to prevent short circuits. Firing cable should be tested regularly by the Charge-Up Operator and/or mine electricians as part of their firing procedures. Any defects must be reported immediately to the Shift Supervisors and rectified before firing can take place. All ends must be twitched and checked before commencing any work on a firing cable. To avoid electric currents being induced in any firing line and creating unplanned initiation they must never be installed parallel to and within 300mm of any power or communications cables. If a firing line needs to cross these services, it must do so at right angles. Insulation resistance testers should never be used on firing lines
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