8 2.3. Stage 3 Refer to ESCP-TSF3-003-01 Stage 3 includes the construction of Collection Ponds S6 and S7 to the south of TSF3. The Collection Ponds are designed to capture runoff from the entire TSF3 footprint (34ha). Pond S6 will provide capacity of up to 40,000m3 Pond S7 will provide 80,000m3 of storage volume. SRP-TSF3-06 will be utilised during construction of the Collection Ponds (formerly constructed during Stage 1). This SRP is designed to capture and treat any runoff (overland flow and pumped flow). Perimeter bunds will be formed around the footprint of the Collection Ponds to direct any overland runoff to the SRP. During the construction of the Collection Ponds significant impoundment will be constructed (during the initial undercut as well as during the construction of the ponds) which aids the management of runoff and that can be periodically pumped to SRP-TSF3-06 for treatment prior to discharging to the Ruahorehore Stream. 2.4. Stage 4 Refer to ESC-TSF3-004-01 Stage 4 involves the continued construction of the TSF3, now using PAF material. All water is directed to the Collection Ponds. 2.5. Stage 5 Refer to ESC-TSF3-005-01 and ESCP-TSF3-005-02 Stage 5 involves the construction of the permanent diversion drain and haul road around TSF3. In total, the earthworks associated with the permanent uphill diversion and perimeter access road spans an average of 20m in width and will be approximately 2,950m in length, providing perimeter access around the TSF3. Clean run-on water from the hills above the TSF will be diverted around the facility to the Ruahorehore Stream. This diversion will be an extension to the existing Southern Uphill Diversion Drain which currently starts behind TSF1A and runs behind the East Stockpile. This drain is set at a level which allows for future potential raising to a crest of RL177. Accordingly, there will be a section of vegetation which will remain between the impoundment level (RL155) and the uphill drain cuts and fills. During construction of the permanent diversion drain large portions will be treated by typical ESC devices. Where this is not possible runoff will flow into the impoundment area of TSF3 and be captured by the Collection Ponds. A draft methodology which will be finalised prior to the commencement of earthwork is provided. The permanent uphill clean water diversion is proposed to be constructed in three sections, with the lower section (section 1) to be constructed first. SRP-TSF3-03 will be utilised to capture sediment laden runoff from the construction of section 1. Section 1 will extent to the East Gully Fill and catchment area of SRP-TSF3-05. This section will be constructed and progressively stabilised. A portion of the Section 2 permanent diversion drain will be able to be diverted to SRP-TSF3-05 for treatment. Where this is not possible silt fences or decanting earth bunds (DEBs) will be used to capture runoff. As works progress uphill more of the diversion drain will flow down to SRP-TSF3-05. The drain will be progressively stabilised.
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