CWD bund – Topsoil stockpile 2ha 0.904 2% 0.92 550 CWD bunds – Magazine Storage Area 2ha 0.904 2% 0.92 550 Figure 3: Cross-section of a clean water diversion bund. Where a clean water diversion channel is required to be constructed then the following schematic is provided for a maximum clean water catchment of 6ha (WRS – Year 1 maximum catchment area). In this case the total flow depth would be 700mm (400mm plus 300mm freeboard). Figure 4: Design details of a clean water diversion channel for up to 6ha. 3.2. Dirty Water Diversions Dirty water diversions will direct sediment laden runoff to the sediment control measures. The dirty water diversions have been sized to provide diversion capacity up to the 5% Annual Exceedance Probability (AEP) storm event, plus a freeboard of 300mm. Calculations are provided in Table 4. Table 4: Dirty water diversion details assuming maximum dirty water catchment area. Dirty Water Diversions Area 5% AEP rainfall depth (mm) Catchment area (maximum) Peak flow (m3/s) Base width (m) Diversion slope (minimum) Channel capacity (m3/s) Design flow depth (including 300mm freeboard)
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