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 12 of 44 Hazardous Substances Management Plan 5 HAZARDS IDENTIFIED AND RISK MANAGEMENT Risk Potential Cause Critical Controls Health Chemical Exposure Less than adequate competency to store, use and handle hazardous substances. Equipment failure - release or spillage. Incorrect use of PPE. Incorrect PPE. Less than adequate Ventilation and Extraction. Procedures no followed. Medically treated Injury Lost time Injury Permanent Disabling Injury Nervous system damage. WAI-250-PLN-003 Hazardous Substances PHMP & Hazardous Substances Risk Register. ChemAlert database & SDS chemical data. Product or Chemical Evaluation assessment. High risk chemical SOPs, Emergency Response. Inductions & Area Training with VoC. Pre-Start Inspections. Plant Automation. Ventilation & extraction systems. Inventory Checks & disposal management. Chemical storage, bunding, segregation. Spill Kits, Wash showers & eye wash stations. personal protective equipment Use of full-face Mask & Respirator filter. Sodium Cyanide - Delivery, Storage and Use Spillage contact with personnel Personal injury or health effects Cyanide storage area inside bunded shed. Bunded containment to prevent spill escaping to the workplace or environment. Cyanide facility and pipework away from acids, no possible way for acids and cyanide to interact Scrubber on solids mixing tank, automated control systems, interlock control systems to prevent tank overflows, overflow pipework to bund to catch any possible overflow, bund has sump pump rain fall re-directed away from cyanide storage bund to maintain bund storage volume. Fixed HCN monitoring, Materials construction, PPE Sodium Cyanide Solution (30%) - Storage and Use Spillage contact with personnel Personal injury or health effects Bunded area, splash guards around pipes, flange guards, pumps. Cyanide facility and pipework away from acids with no possibility of acids and cyanides interacting. Cyanide storage and mixing area pipework completely dedicated. Pipework isolated completely from water network. Automatic mixing, transfer dosing, automatic control systems, interlocked control systems to prevent tank overflows, bunded areas with sump pumps, rainfall directed away from cyanide storage bund to maintain bund storage volume, contingency ponds engineered and designed to hold cyanide spill. Fixed HCN monitoring, materials construction Poor lake water quality Acid run off from batters above the lake Breach of mining consents PLWQ model reviews Pit water monitoring programme

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