SUPERSEDED NEGOTIATED - OPW25 0042 - REFERENCE DOCUMENT (As Published)

             2.1.1       Modelling Parameters
        A hydrologic analysis of the Site and contributing catchments has been undertaken to determine the pre and post-development peak
        discharges. Key hydrologic model details are provided in Table 2.2.

        TABLE 2.2: KEY MODELLING PARAMETERS - HYDROLOGY

            Parameter                            Details                                       Basis / Comments

            Software                             WBNM                                          -

            Approach                             ARR 2019 Methodology                          -

            Pervious Initial and Continuing
                                                 31mm / 3.4mm/hr
            Losses
                                                                                               ARR Data Hub
                                                                                               Lat: -26.394
            Temporal Patterns                    East Coast North (ECNorth)
                                                                                               Long: 153.085
            Pre-Burst                            Median

                                                                                               BOM Rainfall IFD Data System
            IFD                                  -                                             Lat: -26.394
                                                                                               Long: 153.085


             2.1.2       Summary of Peak Flows
        TABLE 2.3: PEAK DISCHARGE

                                                                    1% AEP                                    1% (2100) AEP

            Model Outlet                                            1.91                                      2.32




        2.2             Local Flood Model
        Flood modelling of the local catchment has been carried out using TUFLOW software developed by BMT WBM. TUFLOW is a computational
        engine that provides one-dimensional (1D) and two-dimensional (2D) solutions for the free surface flow equations to simulate flood and
        tidal wave propagation. The Heavily Parallelised Compute (HPC) computational method has been applied using 2023-10-AE version of
        TUFLOW. Modelling assumptions and outcomes are described below.


             2.2.1       Model Setup
        A local flood model has been setup to represent the Proposed scenario for the site and are described below:

        •     Proposed Scenario (004) – The Proposed Scenario has been prepared to represent the proposed development (including changes to
              hydrology, earthworks and associated infrastructure) to assess any potential changes that may result within the drainage path from the
              development works.

        The TUFLOW hydraulic model been assessed for 1% AEP and 1% AEP Climate Change storm events. The assessment has considered a range
        of storm durations (15 min to 120 min) to ensure that the critical storm is defined. Critical duration was under 15 minutes for all events. A
        summary of the model setup is detailed below with TUFLOW model setup presented below in Figure 2.2.

        Sensitivity Assessment – Three sensitivity assessments were completed for the following arrangements and run for the 1% (2100) AEP event:




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                   23806878                                                                                                                         6
Version: 0, Version Date: 01/01/1900