Attachment 3 - Stormwater Management Plan

                                           Figure 3.2 – DRAINS Post-development catchments


The results of the modelling against the range of design storms for the development under the existing and
proposed development conditions are shown in Table 3.1 Existing and proposed unmitigated site peak discharge
rates.
                              Table 3.1 Existing and proposed unmitigated site peak discharge rates

                                                                      Wyandra Street
                                                                                                      Qchange
                                           A.E.P               Qexisting    Qproposed    Qchange       (%)
                                                               (m³/s)       (m³/s)       (m³/s)
                                             1EY                0.024        0.027        0.003        13%
                                            50%                 0.029        0.029       0.000          0%
                                           0.2 EY               0.044        0.045       0.001          2%
                                            10%                 0.053        0.053       0.000          0%
                                             5%                 0.061        0.061       0.000          0%
                                             2%                 0.070        0.071       0.001          1%
                                             1%                 0.078        0.078       0.000          0%



The site has only resulting in minor increases to peak run-off for less than half of the modelled storm events. With the
increase being a maximum of 3L/s, the impact to downstream drainage conditions will be insignificant and unlikely
to result in damage or nuisance to downstream properties and infrastructure. Attenuation is therefore not required
for the proposed development.




Project number 20220116
File RECOR Preliminary Stormwater Management Report - 20220116.docx, 2022-09-27                                   Page 8 of 14
Revision 1


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