pond will be built with a maximum catchment area of 1.2ha. This SRP will be designed and constructed in accordance with TR2009/02. Refer to Appendix B for the SRP design details. Earthwork’s activities will commence with construction of the access to the Gladstone Portal. The final design and earthworks staging details are yet to be confirmed. These details will be confirmed as part of the final SSESCP. Until such time that the runoff is contained within the GOP runoff could either be directed to the existing contingency pond within the Processing Plant and water directed to the Water Treatment Plant (TBC based on capacity) or by additional ESC measures, such as a separate SRP. As a separate earthwork’s operation, during Year 1 earthworks associated with the construction of MUG and WUG portals (location shown on Figure 1) will be undertaken to the north of GOP. All water runoff from this area will be either be directed to the existing Water Treatment Plant or separate ESC measures will be installed. The details will be provided as part of the final SSESCP. As part of the Water Treatment Plant upgrade a new discharge pipe will be laid from the Water Treatment Plant and the existing discharge pipe will also be relocated. The proposed alignments are shown on the drawing titled Waihi North Water Treatment Plan Outfall Discharge Upgrade – Civil Set Layout View, drawing number 2210983-203-SK1; prepared by BECA. Both pipes are 250mm diameter and extend from the Water Treatment Plant ponds to the Ohinumuri River outfalls. The discharge locations are shown on the BECA drawings. A brief construction methodology for the pipe installation is as follows: - The pipes will be installed as a typical open trenching operation, generally utilising a cut and cover methodology. The methodology involves the excavation of the trench in no more than 100m sections, laying pipe and backfilling the trench within the same day. Any exposed area will be covered with hay mulch. - An approximately 1300mm deep by 600mmwide trench will be excavated with spoil stockpiled on the high side of the trench for later reuse as backfill. - Pipes will be laid within the excavated trench. - If any water impounds within the trench, it will be pumped to a sediment control device for treatment prior to discharging. - Stockpiled spoil will be used to backfill the trench. Any excess spoil will be placed on a truck and transported back to site for disposal. - The disturbed and exposed area will be covered with hay mulch. Reinstatement at ground level will match existing. Outlet structures are proposed to be installed within the Ohinemuri River. 2.2. Year 2 Refer to ESCP-GP-001-02 Year 2 involves much of the same in terms of the ESCs. No additional ESC measures are proposed. 2.3. Year 3 to Year 6 Refer to ESCP-WR-001-03 Once the GOP has been excavated to inversion and once all water runoff is contained within the pit, SRP-GP-
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