Stormwater Management Plan · MCU15/0122

                                                                                          15099 - SBSMP/2
                                                                                                    Page 10




                   Table 5.4 - XP-RAFTS Source Node Parameters – Pre-Development Site
                                                             Pre-Development Site
                                                                 Existing Node
                            Parameter
                                                     Sub Catchment 1      Sub Catchment 2
                                                        (Pervious)          (Impervious)
                          Initial Loss (mm)                  0                    0
                      Continuous Loss (mm/hr)               2.5                   0
                        Catchment Area (ha)               0.2927               0.1398
                       Impervious Percentage                0%                  100%
                            Vectored Slope                 4.4%                 8.0%
                             Manning's "n"                 0.050                0.015
                           IFD Coefficients             Noosaville            Noosaville
                         Storage Coefficient                N/A                  N/A


Table 5.5 summaries the pre-development peak flows calculated by XP-RAFTS for a range of
design storms. As a check to ensure the peak flows calculated from XP-RAFTS are reasonable,
peak flows utilising the Rational Method were calculated and have also been listed in Table 5.5
(refer Appendix F for detailed Rational Method calculations).

         Table 5.5 – Pre-Development Peak Discharge (XP-RAFTS and Rational Method)

                                        XP-RAFTS                           RATIONAL METHOD
             ARI
                                 Existing Peak Discharge                  Existing Peak Discharge
           (years)
                                          (m3/s)                                   (m3/s)
                                           0.150
              2                                                                   0.100
                                     (2yr 25min storm)
                                           0.199
              5                                                                   0.138
                                     (5yr 25min storm)
                                           0.222
              10                                                                  0.161
                                     (10yr 25min storm)
                                           0.255
              20                                                                  0.192
                                     (20yr 25min storm)
                                           0.271
              50                                                                  0.243
                                     (50yr 25min storm)
                                           0.301
             100                                                                  0.279
                                     (50yr 25min storm)


For pre-development peak flow rate hydrographs from XP-RAFTS refer to Appendix D.




Site Based Stormwater Management Plan
Proposed Medical Development at Cnr Val Crescent & Goodchap Street, Noosaville