Amended Stormwater Managment Plan

SC5594 – Walter Hay Dr, Noosaville                                                            16




Flows from minor storms up to and including the 10 year ARI are to be conveyed in the underground
drainage system from the Bio-retention basin. Major storm events exceeding the ARI10 year, up to and
including the peak ARI 100 year events will overtop the Bio-retention basin weir 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)
1             90                     0.101
2             60                     0.150
5             60                     0.208
10            60                     0.247
20            60                     0.289
50            60                     0.335
100           60                     0.383
Table 4.3 – Pre-Development Peak Flow Rate Results

                                                   3
ARI           Design Storm (min)     Peak Flow (m /s)
1             60                     0.100
2             60                     0.129
5             60                     0.158
10            60                     0.179
20            90                     0.223
50            90                     0.304
100           90                     0.381
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.