RFI - updated flood investigation report

      A blockage factor of 20% has been applied as per the ARR blockage assessment completed
      in Appendix E.
      Table 4-2: Model Culvert Information
            ID                       Size                        Length   USIL (m AHD)   DSIL (m AHD)
            1            1 x 1800 x 900mm RCBC                    7.00        14.66          14.56
            2                  1 x 900mm RCP                      11.15       14.08          14.01
            3                  1 x 300mm RCP                      11.17       14.04          13.95
            4                  1 x 300mm RCP                      10.74       13.63          13.60
            5                  1 x 450mm RCP                      10.78       13.13          13.06
            6                  1 x 375mm RCP                      15.00       12.89          12.78
            7                  4 x 750mm RCP                      15.00       12.53          12.49
            8             1 x 300 x 450mm RCBC                    11.83       12.77          12.74
            9                  1 x 380mm RCP                      13.32       13.40          13.30
            10                 1 x 380mm RCP                      11.55       14.60          14.50
            11                10 x 750mm RCP                      11.2        13.95          13.80
            12           3 x 1200 x 900mm RCBC                    11.2        11.94          11.83
            13                1 x 1500mm RCP                      9.79        11.30          11.10
            14                 5 x 900mm RCP                      11.2        15.68          15.62
            15                 1 x 380mm RCP                      10.99       15.95           15.8
            16                10 x 750mm RCP                      11.2        14.05          13.95
            17                 5 x 2400 x 1500                    9.24         6.50           6.40
            18                 1 x 450mm RCP                       6.2         8.72           8.68
         Internal      9 x 1200mm x 600mm RCBC                    10.00       11.80          11.75
        Driveway               1 x 300mm RCP                        5         12.94          12.92



               Model Scenarios
      The Existing (E01) and Proposed (P01) scenarios are described below and depicted in
      Appendix D.

      4.2.1. Existing Scenario (E02)

      In representing the Existing Scenario, the model was setup to represent the overland flow
      characteristics that existed prior to the site being developed. A combination of LiDAR and
      detailed survey was used to represent the existing model terrain. The model was run for the
      63.2%, 39%, 10% and 1% AEP for durations ranging from 30min to 12hrs.

      3.2.3 Proposed Scenario (P03)

      The Proposed Scenario has utilised the Existing Scenario model to represent the proposed
      development. The following changes were made:
           •        Represent internal road at RL12.7m AHD (2d_zsh).
           •        Represent new 9 x 1200 x 600mm RCBC under internal road (1d_nwk).
           •        Represent filling of building envelopes of Lot 1 and 4 to achieve flood immunity
                    (2d_zsh).
           •        Represent minor regrading beside building envelope of Lot 1 (2d_zsh).
           •        Adjustments to roughness to account for new road (2d_mat).
      The model was run for the 63.2%, 39%, 10% and 1% AEP for durations ranging from 60min to
      24hrs.




21-0288-FS001-V3 | Flood Investigation | 60 Glenridge Drive, Cooroibah                                  | 11