Erosion and Sediment Control Assessment Report Rev. 0 This is an uncontrolled copy if photocopied or printed from the Intranet. Copyright © 2016, SouthernSkies Environmental Ltd. All rights reserved. Page 19 of 30 manual decant pulley system, which will enable the decants to be raised during pumping activities to these structures. During pumping the decants will only be lowered once an acceptable standard of discharge quality, assessed as not less than 100mm visual clarity, has been achieved. The pumping rates and volumes to SRPs will be controlled so that the total pump volume can be fully captured within the retention structure. 6.3.8. Dust Control Dust will be managed onsite in accordance with the Air Quality Management Plan14. 6.3.9. Streamworks NRS The NRS will require various streamworks. The upper catchment streams above the footprint of the site will be diverted into a new permanent diversion channel that will be formed around the site and discharge into the lower reaches of the main tributary just upstream of its confluence with the Ohinemuri River. That diversion will be constructed in stages, and fully stabilised prior to flows being diverted into each stage. This will require relatively significant earthworks including cuts through ridges, which will be diverted back to sediment retention ponds until stabilised. Temporary culverts will be installed to carry tributary flows across the works required to form the diversion and haul routes. These will be installed partially off-line, with the existing channel being used to carry flows until the pipe is installed, and flows are directed into it. Subject to detailed design and contractor input, pumping may also be used in conjunction with the diversion channel. On completion of the permanent diversion channel, those pipes will be plugged and sacrificed, and the earthworks across the site undertaken. TSF3 As for the NRS, a permanent diversion channel will be installed to pick up all upper catchment flows and direct those to the Ruahorehore Stream downstream of the new stormwater ponds. Temporary clean water diversions will be used to divert upstream drainage around the initial works areas. The permanent diversion channel will be installed using the same staged, offline methodology as that of the NRS. Once the diversion is operational, the various minor stream channels and drainage channels within the TSF3 site will be managed within the footprint of the general earthworks. Other minor channel works will be required that will also adopt the off-line methodology. Services Trench The works required along the Services Trench from the Willows Road site to the Processing Plant will require two crossings of Ohinemuri River. It is proposed that the utilities will be installed by separate pipe bridges. No works within streams are proposed. 7. EROSION AND SEDIMENT CONTROL IMPLEMENTATION 7.1. Site Specific Erosion and Sediment Control Plans The SSESCPs will address the following information for each specific work area, which may be a site (e.g. NRS or TSF3) or a stage of a site. The SSESCPs will include: 14 Draft Air Quality Management Plan; June 2022, prepared by OGNZL
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