Figure 2: Example of a flood gate proposed to be installed on the outlet pipe of SRP-NRS-04. 2.2. Stage 2 Refer to ESCP-NRS-002-01, ESCP-NRS-002-02, and ESCP-NRS-002-03. Stage 2 largely involves the construction of the permanent uphill clean water (stream) diversion, perimeter access road and NRS diversion channel. A cross section of the proposed structure is provided in Figure 3. In total the uphill diversions and perimeter access road spans 22m in width and will be approximately 1.2km in length, providing perimeter access around the NRS. 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 two sections, with the upper section to be constructed first. Two SRPs will be constructed to service this section of work (SRP-NRS-06 and SRP-NRS-07). Perimeter bunds, both clean water and dirty water, will be constructed upslope and downslope of the works area. Initially, a temporary stream diversion pipe will need to be placed within the base of the gully to allow any clean water to continue downstream via the existing stream channel. Once the temporary pipe has been installed SRP-NRS-07 can be built on top of it to service the earthworks required to fill the gully and construct the permanent uphill clean water diversion. The pipe size can be confirmed through detailed design and a stabilised bund can be constructed immediately downslope of the pipe inlet to significantly increase the headwater depth if the capacity of a pipe was exceeded. The earthworks associated with the magazine storage facility could also be completed during this stage of works which would allow runoff from this area to flow to SRP-NRS-07. Staging details will be confirmed as part of the Final ESCPs.
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