Attachment D - Stormwater Report · MCU18/0013

                           Figure 3 - Ensemble Statistics Utility Results; 100 year ARI

      Table 3 below compares the peak flow rates and total runoff volume for the existing and developed model.
     Table 3 - XP Storm Results

                                  Median           Peak Flow Rate (L/s)              Total Volume (m3)
       ARI     Duration (min)     Storm
                                  Pattern        Existing         Developed        Existing     Developed

                      5             N/A              37             18 (-19)         7.15       3.09 (-4.06)

                     10              5               35                35           13.73       9.95 (-3.79)
        10
                     25              5               29              25 (-4)        24.67      21.94 (-2.73)

                     60              2               26              27 (+1)        39.06      37.10(-1.96)

                      5             N/A              60              58 (-2)        14.08       9.23 (-4.85)

                     10              8               48              49 (+1)        21.05      17.80 (-3.25)
       100
                     25             10               42                42           39.32      35.45 (-3.87)

                     60              6               35                35           62.53      60.06 (-2.47)

      As shown in Table 3, the peak flow rate of stormwater runoff and the total runoff volume off site has not
      increased as a result of the development. The 1L/s increase for the 10 year 1 hour design storm and 100
      year 10 minute design storm are considered negligible and within the tolerance of the modelling software.
      The proposed infiltration/detention tank is therefore considered to be adequate. Results for the 5 minute
      duration for the 100 year ARI are outlined in Figure 4 & 5 below.




                                      24 Arakoon Street, Sunshine Beach QLD 4567
Job No – S18-003                         STORMWATER MANAGEMENT REPORT                                            5