Supporting Technical Assessments

Approved by: Process Manager Approval Date: 16/12/2021 Next Review: 16/122023 OceanaGold Waihi Document ID: WAI-250-PLN-003 Page 17 of 44 Hazardous Substances Management Plan Stored hazardous substances must be adequately segregated based on: • Quantity of materials stored • Physical state of the chemicals (solid, liquid or gas) • Degree of incompatibility (report available from ChemAlert) • Manufacturer’s instructions; and • Known behaviour of the materials. All bunded compounds will be maintained to ensure; • Bunding in compliance with AS1940 – 2009 • Secondary containment capacity of at least 110% of the largest container • Chemical resistant to the substance stored • Valves, pumps and meters associated with transfer are operable as required • Equipment is adequately protected and contained • Any potential jetting from any storage vessel or fitting is captured within the bunded area; and • Incompatible chemicals are physically segregated and do not come into contact with each other 7.7 Signage Signage will be maintained at all entrances to site as per the HSNO requirements to ensure that people (including emergency services) entering site understand the hazards posed by the substances and take the appropriate precautions. Entrance, area and storage tank signage is to identify the substance present, the class and action to be taken in an emergency. Additional signage for tanks (LPG, liquid oxygen, hydrochloric acid, diesel and sodium hydroxide) require signage to include: proper shipping name, UN number, relevant HAZCHEM code, other applicable warnings (eg degree of the hazard, if combustible, highly toxic, highly corrosive, no smoking, no ignition sources etc). 7.8 Storage Tanks and Piping Storage tanks and piping must be certified and approved for the conditions of use and be made of suitable material to be impervious to the chemical stored in them. They are to be stored above ground and routinely inspected and maintained. The only exemption (LPG Line under roadway) requires specific integrity testing. Piping and flow lines shall be colour coded and marked to indicate the content and direction of flow. Fluids will be labelled in accordance to ASNI/ASME A13.1. Gases will be labelled in accordance to AS/NZS 5807. 7.9 Automated Plant Control Systems Automated plant control systems will be in place where possible to safeguard personnel and property. Hazardous substance bulk storage will be fitted with level instruments where possible which feedback to a central PLC SCADA system. The SCADA is continuously monitoring and displays the information to operations on a human machine interface (HMI). Where possible control interlock’s will be in place to prevent any

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