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 19 of 27 7.1.2 Charging If ANFO is being used an IT and charge cage is utilised. The charge cage has certified kettles, is equipped with lo-stat ANFO hoses and has an earthing strap. A mobile charging unit (Charmec) fitted with a Hypercharge unit will be used if charging with emulsion. A smaller portable Hypercharge unit that attaches to an IT may also be used for charging with emulsion. All units are equipped with a fixed fire suppression system. 7.1.3 Firing A Stinger or Beethoven is used to initiate all blasts on the main firing line. If the blast initiation system is electronic, an independent firing line system is used, and only appropriate blast initiation equipment will be used. 7.2 Maintenance 7.2.1 Special Precautions Prior to any explosives equipment undergoing maintenance the following considerations need to be considered: • Remove all explosives and wash down machine before servicing • Charge Vehicle Possession Handover form completed. • Use hot work permits where relevant and earthing during welding • No welding to be done on the charge cage • No one is permitted to work directly on the pump of the Hypercharge Drive system. If a problem with the pump occurs, notify the Production Engineer who will arrange for Orica to service it. Refer to the hot work procedure for more information on precautions taken when servicing the Charmec; see Appendix I for document details. 7.2.2 Inspection and Testing The following inspections and tests are carried out as part of a weekly service: • The condition and structural integrity of the charge cage is inspected • The resistance of the earthing strap on the ANFO charge cage is tested and recorded • The relief pressure on the safety valves on the kettles is tested in conjunction with testing of the regulators • Any information on faults or repairs noted on the daily pre-start checklist should be tended to as well (if not fixed previously) 7.2.3 Preventative Maintenance All equipment used underground is subject to a preventative maintenance program. All equipment is brought to the surface workshop on a routine basis so appropriate checks, inspections and tests can be carried out. In addition to this, ANFO kettles will be pressure tested annually by a registered organisation.
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