Refernce Documents - RAL25 0001

                        Table 5.2.2-3 XP Storm Model Results – Critical Peak Discharge Comparison – Link 31
                                       AEP   Peak Pre Developed        Peak Post Developed         Difference
                                             Discharge (m3/sec)         Discharge (m3/sec)          (m3/sec)
                                       63%           1.4                       2.1                     0.64
                                       39%           2.8                       2.9                     0.08
                                       18%           4.2                       3.9                    -0.25
                                       10%           5.3                       4.6                    -0.75
                                        5%           6.4                       5.4                    -0.99
                                        2%           7.5                       6.6                    -0.90
                                        1%           8.8                       8.0                    -0.81


                     Refer to modelling results shown in Table 5.2.2-3, post development peak discharge will
                     be similar to pre development peak rates resulting in no adverse impacts on the
                     downstream property. Only the critical peak flow in the 63% & 39% AEP event is exceeded.


                        Table 5.2.2-4 Difference Comparison of Pre vs Post Mitigated Development – Link 31
                                                              AEP – Difference in Discharge m3/s
                          Duration         1%           2%         5%         10%          18%       39%        63%
                           10min          0.73         0.29       0.21        0.19         0.17      0.14       0.11
                           15min          1.98         1.85       0.58        0.20         0.17      0.14       0.11
                           20min          0.20         1.58       1.97        0.83         0.22      0.13       0.11
                           25min         -1.65        -0.32       1.64        1.69         0.61      0.14       0.11
                           30min         -1.57        -1.36       0.50        1.92         1.25      0.14       0.11
                           45min         -0.82        -0.97      -0.94        0.22         1.41      0.75       0.06
                            1hr          -0.63        -0.90      -0.55       -0.37         0.40      1.39       0.24
                           1_5hr         -0.75        -0.85      -0.88       -0.58        -0.28      1.08       0.85
                            2hr          -0.89        -1.01      -1.03       -0.75        -0.11      0.31       1.01
                            3hr          -0.89        -0.99      -0.51       -0.32        -0.24      0.08       0.64
                           4_5hr         -0.85        -0.78      -0.48       -0.36        -0.40      0.07       0.60
                            6hr          -0.29        -0.25      -0.54       -0.50        -0.12      0.11       0.60
                                 Decrease Pre vs Post
                                 Increase Pre vs Post


                     Table 5.2.2-4 shows the difference in discharge between the pre developed and post
                     development results for all storms and durations modelled. As previously illustrated, the
                     critical peak discharge and the majority of flows across all ensembles storms and
                     durations modelled will not result in an actionable nuisance.




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