U:\2021\BM210482_IBo_Waihi_North_Project\Documents\WNP_Freshwater_Report_May_2022\FINAL_Freshwater_Report_FOR DELIVERY_June 2022\FINAL DELIVERED 17 JUNE 2022\WAI-985-000-REP-LC-0007_Rev0_Freshwater_20220621_FINAL.docx 17.3 Tailings Storage Management Project Activities 17.3.1 Outline and Footprint The total footprint of works required for TSF3 is 95 ha. This area includes the stockpile areas, the new embankment and impoundment areas, collection ponds, the uphill diversion drain and area between the impoundment and the uphill diversion drain. Approximately 8.2 ha (plan area) of the designated Significant Natural Area 166 is included in the overall extent of works. The area between the impoundment and uphill diversion drain does not need to be cleared of vegetation, however, the works for cutting in of the uphill diversion drain is a tight working space and is likely to require cut to fill downslope along the alignment through the SNA. The alignment suggests a conceptual cut and fill extent in the SNA. It is estimated that at least 2.7 ha (plan area) of vegetation will be able to remain between the RL155 impoundment and extent of fill for the extension of the Southern Uphill Diversion Drain. The effects of loss of terrestrial vegetation are reported by Bioresearches (2021). 17.3.2 Erosion and Sediment Control Erosion and sediment control measures will be established before undertaking preparatory works. This will include appropriate silt control to avoid discharge of excessive suspended solids to the Ruahorehore Stream. Similar techniques as utilised for the construction of the other TSFs will be used, including: • Installation of silt fences on steep slopes where possible. • Construction of temporary clean and dirty water diversion drains. • Construction of earth detention bunds. • Construction of sediment collection ponds. • Use of flocculants as required. Details of erosion and sediment control are laid out in OGNZL (2021). 17.3.3 Preparatory Works Preparatory works will include: • Clearing site of fences and farm services. • Relocating power ready for reestablishment. • Establishing a haul road down East Stockpile to the TSF3 site. • Sheeting of access roads. • Progressive mulching and burning (if required) of vegetation. • Progressive topsoil and vegetation stripping and stockpiling. • Cutting of additional farm drains as required to drain the surficial soils. • Construction of the extended Southern Uphill Diversion Drain behind TSF3 site. • Ruahorehore Stream realignment.
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