MCU10/2083 Information Request Response 37 Gibson Rd Noosaville

                                                                                                                                        URBAN




3.5   RAINFALL INTENSITIES

The rainfall intensities for the Pre and Post Development Scenarios were determined from the IFD chart for the
Noosa Region calculated from AR&R, 1987.


                                                     Table 4 - Rainfall Intensities

        Time of Concentration   1 year ARI         2 year ARI        5 year ARI          10 year ARI       20 year ARI    50 year ARI      100 year ARI
                  (mins)         (mm/hr)           (mm/hr)            (mm/hr)              (mm/hr)          (mm/hr)        (mm/hr)          (mm/hr)



                  5.33           126.20            159.47             196.90               217.61           246.74         285.14           314.27

                  5.42           125.46            158.55             195.78               216.39           245.36         283.56           312.53



3.6   FLOWS (UNMITIGATED)

The flow calculated for the Pre and Post Development Scenarios for a range of storm events is tabulated below.

                                                    Table 5 - Flows (Unmitigated)

      Scenario
                                                   Q1                Q2               QS             Q10           0.20          QSO            Q100
                                               (m'/s)           (m'/s)             (m'/s)          (m'/s)         (m%s)         (m'/s)          (m'/s)
       Pre Development                         0.095            0.128             0.177            0.205          0.243        0.306            0.337

       Post Development                        0.094            0.128             0.176            0.204          0.242        0.304            0.335




3.7   COMPARISON OF FLOWS

There is no net increase in flow due to the proposed development as tabulated below.

                                                   Table 6 - Comparison of Flows

                                              Q1                Q2               QS               Q10           Q20           QSO
       Scenario                                                                                                                           Q10o (m'/s)
                                             W/o             W/o                (m /s)           (m /s)        (m /s)        (m'/s)


       Pre Development                       0.095         0.128               0.177 1 0.205                   0.243        0.306           0.337

       Post Development                      0.094         0.128               0.176          0.204            0.242        0.304           0.335

       To Be Detained                        -0.001        0.000               -0.001         -0.001          -0.001        -0.002          -0.002


A rational method analysis of pre and post development scenarios concludes that no net increase in peak
stormwater flows will occur as a result of the proposed development. On site detention storage will not be
required to ensure no net increase in post development discharge to the street drainage network within Gibson
Road and Skipper Place.




 SITE BASED STORMWATER MANAGEMENT PLAN - Revision E                       ' G bson Road, Noon.                                                            7