Amended Stormwater Plan · MCU18/0019

SC7440 – Goodchap St, Noosa                                                                             13




Flows from minor storms up to and including the 10 year ARI are to be conveyed in the underground
drainage system. Major storm events exceeding the ARI10 year, up to and including the peak ARI 100 year
events will overtop the stormwater pits fronting the boundary and flow overland into Council’s road reserve.


A concept drainage layout plan has been included as Appendix A of this report.


4.4     Modelling Results
A node layout plan is included in Appendix C of this report and the resultant peak flow rates are displayed
in Table 4.3 & 4.4.


                              ARI     Design Storm (min)        Peak Flow (m3/s)
                               2               60                     0.170
                               5               60                     0.230
                              10               60                     0.262
                              20               60                     0.309
                              50               60                     0.350
                              100              60                     0.392
                            Table 4.3 – Pre-Development Peak Flow Rate Results


                              ARI     Design Storm (min)        Peak Flow (m3/s)
                               2              60                      0.104
                               5              60                      0.124
                              10              60                      0.133
                              20              60                      0.197
                              50              60                      0.254
                              100             60                      0.285
                      Table 4.4 – Post-Development (mitigated) Peak Flow Rate Results


As can be seen in Tables 4.3 & 4.4 the post-development peak flow rates to the existing drainage system
compare well to that of the existing pre-development site discharges. This is due to the large volumes of
on-site detention proposed to be included as part of the development.