Refernce Documents - RAL25 0001

                     5.2.1 Stormwater Modelling


                     An XP Rafts Model has been prepared to simulate the pre and post-developed drainage
                     scenario for the central flow path in order to quantify stormwater flows from this flow
                     path, the developed site and the impact of the proposed Hoy Road crossing works. The
                     following methodologies and parameters were adopted in the model


                          •    Site Specific Rainfall Intensities - Bureau of Meteorology’s 2016 IFDs.
                          •    Storm Durations Modelled – 10min to 360min
                          •    AEP Modelled – 63%, 39%, 18%, 10%, 5%, 2% and 1%
                          •    ARR Initial (35mm) and Continuing (3.0mm) Losses applied for Pervious Area.
                          •    Impervious area Initial (2mm) and Continuing (0mm).
                          •    Results reported are the maximum of the means.


                     The attached XP-Storm Model (Appendix E) catchment nodes have been calibrated to the
                     1% AEP discharge results calculated using the Rational Method (RM) for the Pre and Post
                     development scenarios. This approach to calibration and modelling provides a good fit
                     between the model and hand calculations. Refer to for results of the Rational Method
                     (RM) and XP Storm (XP) discharge.


                     Refer to Table 5.2-3 & Table 5.2-4 for results of the Rational Method (RM) and XP Storm
                     (XP) discharge for each catchment node. Refer Appendix F for RM calculations.




                                                                                                             10
Document Set ID: 23448644
Version: 1, Version Date: 13/01/2025