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 2C Drawn ZW Checked MP Drawing No. ESCP-TSF3-002-03 Sheet No. 7 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. Construction Methodology Modify clean water diversions to allow for further area of earthworks. During this stage of work the embankment crest will be constructed to an RL of 116.6. This will construct an embankment downstream height of 3.6m and an upstream height of 3.1m. The calculated storage volume to RL 116.6 is 19,120m3. This will contain approximately up to the 2year 12-hour rain event for a contributing catchment area for this stage of approximately 16.6ha (assuming no soakage). Below the footprint of the embankment toe, dirty water diversions will direct runoff from the embankment to SRP. Water impounded within the embankment will be pumped to the SRP for treatment. KEY Erosion and Sediment Control Clean Water Diversion Dirty Water Diversion Culvert Silt Fence Sediment Retention Pond Temporary clean water diversion directing upslope clean water catchment away from the area of earthworks. Embankment constructed across the valley floor. Undisturbed area – 3.34ha Earthworks within impoundment area – 5.25ha. Temporary clean water diversion. Geomembrane lined area – 8.0ha SRP-TSF3-07 Catchment area: 7.5ha Total volume: 2,250m3 Dead storage: 675m3 Live storage: 1,575m3 SRP to incorporate 2x manholes and outlet pipes and 5x T-bars.
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