stormwater mgJ00300R1V1_25_Kauri_St_Cooroy_Complete · MCU18/0165

25 Kauri St Cooroy




Image 4-1 – Total Existing Site Design Runoff Hydrographs




4.2      Un-Mitigated Developed Case
The development has been incorporated into the WBNM modelling by updating the fraction
impervious values to reflect the proposed developed layout as shown in Appendix B. All
proposed roof and road areas have been assigned a fraction impervious of 100% impervious and
the remaining site ground level has been assigned a fraction impervious of 30% to account for
pathways etc. The resulting overall fraction impervious for the developed site is 73% and this
has been assigned to the developed case WBNM model.

The adopted ensemble hydrograph for each AEP event is shown on Image 4-2. Peak flows and
the associated critical storm duration are also labelled. These hydrographs represent the design
storm runoff from the full un-mitigated developed site.




J00300R1V1                                                                                   6