Refernce Documents - RAL25 0001

                                          Table 5.2-1 Central Flow Path Catchment Characteristics
                                                                              Fraction Impervious
                                                        Catchment Area (ha)                                 C10
                                                                                       (fi)
                                                          Pre        Post       Pre         Post     Pre           Post
                                            C1           2.212      2.212       0.0         0.0      0.70         0.70
                                            C2           4.584      4.584       0.0         0.0      0.70         0.70
                                            C3           5.261      5.260       0.0        0.038     0.70         0.708
                                            C4           4.465      4.589       0.0        0.022     0.70         0.704
                                            C5           4.418      4.432       0.0        0.047     0.70         0.709
                                            C6           2.502      2.502       0.0        0.105     0.70         0.721
                                            C7           3.029      3.029       0.0        0.011     0.70         0.702
                                       Total (to site
                                        Boundary /       23.443    23.579       0.0      0.034       0.70         0.707
                                         Hoy Rd)


                   Rational method calculations were undertaken to quantify the impact the development will
                   have on the central flow path. Refer Table 5.2-2 for a comparison of pre vs post developed
                   discharge at the site boundary for the total contributing catchment. Refer Appendix F for
                   Rational Method Calculations


                                       Table 5.2-2 Central Flow Path Catchment Rational Method Calculations
                                                         AEP       Q Pre        Q Post      Variance
                                                                  (m3/s)        (m3/s)
                                                         63%       2.34          2.38        +1.6%
                                                         39%       3.12          3.17        +1.6%
                                                         18%       4.31          4.38        +1.6%
                                                         10%       5.20          5.28        +1.6%
                                                          5%       6.22          6.32        +1.6%
                                                          2%       7.86          7.99        +1.6%
                                                          1%       9.03          9.17        +1.6%


                   When considering the total catchment of the flow path to the Hoy Road crossing
                   (23.579ha), it is demonstrated that the peak flow will increase by 0.14m3/s or 1.6%. This
                   increase is negligible and will not result in an actionable nuisance. The following section of
                   this report will demonstrate the proposed works to the Hoy Road causeway will provide a
                   reduction in peak discharge for the majority of storm events due to the storage within the
                   overland flow path upstream of the road crossing being better utilised.



                                                                                                                          9
Document Set ID: 23448644
Version: 1, Version Date: 13/01/2025