16-001014-01A (Swmp)

                           Table 3-8:    Central Basin Stage Storage Discharge Relationship
                          Accumulated
      Stage (m AHD)                          Discharge (m3/s)     Basin Control/ Structure
                          Storage (m3)
     99.6                      0                   0.00           Primary Front & Side Orifices
     99.7                     237                  0.06
     99.8                     485                  0.17
     99.9                     744                  0.33
     100.0                   1,013                 0.53
     100.1                   1,293                 0.77
     100.2                   1,583                 0.87
     100.3                   1,884                 0.96
     100.4                   2,196                 1.04           Primary Outlet Pit Weir Level (RL100.45mAHD)
     100.5                   2,517                 1.21
     100.6                   2,885                 1.66
     100.7                   3,265                 2.01
     100.8                   3,658                 2.06
     100.9                   4,069                 2.12           Major Overflow Weir (Major & Extreme Events)
     101.0                   4,489                 2.98
     101.1                   4,919                 4.60
     101.2                   5,359                 6.77
     101.3                   5,808                 9.43           Minimum Top of Embankment (RL 101.3m AHD)

3.2.6     DEVELOPED MITIGATED PEAKS FLOW RESULTS

Modelling was undertaken for the all recurrence interval storm events up to and including the 1% AEP storm event with
storm durations ranging from 30 to 120 minutes (these were considered the critical durations). A comparison between
peak flows for the existing and developed mitigated scenarios has been provided at each discharge location in Table 3-9
below.

                           Table 3-9:   Developed Mitigated Scenario Peak Flow Comparison
                                         Existing Peak       Developed Peak         Percentage
                        AEP             Discharge (m3/s)     Discharge (m3/s)       Difference
                                                      Discharge Location A (North)
                        63%                   0.17                0.16                  -5%
                        39%                   0.26                0.23                  -8%
                        18%                   0.36                0.34                  -4%
                        10%                   0.43                0.41                  -4%
                        5%                    0.55                0.46                 -17%
                        2%                    0.66                0.59                 -12%
                        1%                    0.77                0.77                  0%
                        AEP                          Discharge Location B (Central)
                        63%                   1.14                1.13                  -1%
                        39%                   1.71                1.54                 -10%
                        18%                   2.54                2.35                  -7%
                        10%                   3.02                2.76                  -9%
                        5%                    3.69                3.60                  -2%
                        2%                    4.28                4.13                  -4%
                        1%                    4.95                4.65                  -6%

As indicated in the results, peak flows have been reduced below existing levels at both discharge locations. Therefore,
the results demonstrate that the proposed detention basins are adequate to reduce peak flows to ensure no adverse
impact due to the development.


16-001014-01 | STORMWATER MANAGEMENT PLAN (SWMP)                COOROY RETIREMENT COMMUNITY, TRADING POST
| PALM LAKE RESORTS                                                                         ROAD, COOROY                  | 12