Supporting Technical Assessments

REV DATE REVISION DETAILS APPROVED 0 17.06.22 Draft for review. Project WAIHI NORTH Title Erosion and Sediment Control Plan Tailings Storage Facility 3 – Stage 1 Drawn ZW Checked MP Drawing No. ESCP-TSF3-001-01 Sheet No. 1 NOTES 1. All erosion and sediment controls will be installed and maintained in accordance with the Waikato Regional Council Technical Report 2009/02 ‘Erosion and Sediment Control Guidelines for Soil Disturbing Activities’ (TR2009/02). 2. Completed areas to be stabilised in accordance with TR2009/02. 3. All erosion and sediment control measures will be inspected weekly by the site foreman. 4. Site monitoring will be undertaken before and immediately after rain as well as during heavy rainfall events. Any required maintenance or improvements to control measures will be undertaken immediately. SRP-TSF3-01 Catchment area: 5.5ha Total volume: 1,650m3 Dead storage: 495m3 Live storage: 1,155m3 SRP-TSF3-02 Catchment area: 12ha Total volume: 4,000m3 Dead storage: 1,200m3 Live storage: 2,800m3 SRP to incorporate 2x manholes and outlet pipes and eight T-bars. Stockpile 2 area – approximately 12ha Paleo undercut – refer to ESCP-TSF3-001-02 Stockpile 1 – 5.1ha KEY Erosion and Sediment Control Clean Water Diversion Dirty Water Diversion Culvert Silt Fence Sediment Retention Pond Refer to ESCP-TSF3-005-02 for construction of the final section of permanent uphill clean water diversion drain once SRP-TSF3-03 has been decommissioned. Temporary clean water diversion around SRP-TSF303 to match dimensions of permanent clean water diversion. Construction Methodology - Silt fences installed below the footprint of the SRPs. - Form temporary clean water diversion around SRP-TSF3-03. - SRPs constructed. - Perimeter bunding constructed around the stockpiles which will also act as a clean water diversion. The external ‘clean’ side of the permitter bunding will be stabilised. - Approximately 2ha of the Stockpile 2 area will naturally flow to the low point where SRP-TSF3-03 will be constructed. The rest of the area will be diverted to SRP-TSF3-02. While SRP-TSF3-03 has been designed for 12ha, it is not likely that the entire area will be ‘open’ and any one time. - Stockpiling commences. - Stockpiles will be progressively stabilised. - SRP-TSF3-03 will also be used during the construction of the permanent uphill clean water diversion drain (refer to ESCP-TSF3-005-01 and 02). SRP-TSF3-03 Catchment area: 2ha Total volume: 600m3 Dead storage:180m3 Live storage: 420m3 This SRP will be constructed to capture runoff during the setup phase of Stockpile 2 then will be used during the construction of the permanent uphill clean water diversion. Temporary dirty water diversions to delineate SRP-TSF3-03 catchment area.

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