3.3. Sediment Retention Ponds Multiple Sediment Retention Ponds (SRPs) are proposed to be constructed to capture sediment laden water during the earthworks associated with the NRS site establishment. The size of the SRPs has generally been sized based on a 3% storage volume capacity, where practical. Where space is limited, and the contributing slope length is less than 200m and steepness less than 10% the SRP has been designed to provide a minimum storage volume based on 2% of the contributing catchment area. An additional volume of 10% will be provided in the forebay of each SRP. These devices have been sized in accordance with TR2009/02. Final design details will be provided as part of the updated SSESCP for the NRS. A draft design for SRP-NRS-01 proposed to capture runoff from the northern stockpile has been provided in Appendix A. 3.4. Decanting Earth Bunds Decanting earth bunds (DEBs) are not proposed as part of this SSESCP. 3.5. Chemical Treatment The Chemical Treatment Management Plan (CTMP) provided as Appendix A of the Erosion and Sediment Control Assessment Report provides the methodology for determining the effectiveness and dose rates for chemical treatment to enhance the sediment retention efficiency of sediment retention ponds, decanting earth bunds and other water impoundment devices that will be used throughout the project. Appendix A of the CTMP details the provides the chemical analysis and test report which confirms the efficacy of chemical treatment of typical sites' soils, based on the testing methodology described in the CTMP. 3.6. Silt Fences and Super Silt Fences Silt fences or Super Silt Fences may be used to capture runoff from small areas that cannot actively drain to a SRP. Silt fences will be installed below the footprint of all SRPs to capture any runoff during the construction phase of these devices. Once the device is constructed then the silt fence will need to be returned up either side of the emergency spillway. 3.7. Stabilisation Progressive stabilisation will be undertaken throughout the earthwork operations. Both temporary and permanent stabilisation measures will be employed on site. Common stabilisation measures include spreading of aggregate, grassing (with a full cover of grass), applying mulch and the use of geotextiles. Once the catchment area for a particular ESC device is stabilised in accordance with TR2009/02, or the runoff directed to a different water management system (i.e. the Water Treatment Plant) then the ESC monitoring and maintenance will cease and the ESC device could be decommissioned. 3.8. Dust Management Dust will be managed in accordance with the Air Quality Management Plan. 3.9. Dewatering and Pumping Dewatering (pumping) will be required during the Project. A Dewatering Management Plan is proposed to
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