13. Appendix I - Integrated Water Mangement Plan

                                                                                                     Integrated Water Management Plan
                                                                                             Noosa Marketplace : 2-20 HOFMANN DRIVE



Table 6-1       Existing Flood Level (mAHD)

                                                   Existing Flood Level (mAHD)
    Location            39% AEP            20% AEP             10% AEP              5% AEP                2% AEP        1% AEP
        P1                 8.95                8.96               8.99                9.03                 9.08           9.10
        P2                 8.38                8.38               8.39                8.41                 8.43           8.44
        P3                 9.85                9.85               9.85                9.86                 9.87           9.87
        P4                 8.35                8.35               8.35                8.37                 8.39           8.39
        P5                 N/A                 N/A                 N/A                 N/A                 N/A            N/A
        P6                 6.80                6.84               6.85                6.86                 6.88           6.89
        P7                 4.53                4.57               4.59                4.60                 4.64           4.68
        P8                 4.46                4.50               4.51                4.52                 4.55           4.57
        P9                 6.64                6.67               6.67                6.68                 6.69           6.71
        P10                8.79                8.80               8.80                8.82                 8.84           8.85
*N/A meaning that the point of interest is out of the flood waters or located on a development building

6.4.3         Post- Development Scenario
For the current modelling, the development footprint has been set at a nominal level of RL 10.0 mAHD to form
a complete blockage of the flowpath. A service road is proposed to be located around the northern edge of
the development area. The level of this road will be set in detailed design phases of this project, along with
further refinement of the design.
For the post development scenario, an upgrade to the existing 1200 mm x 300 mm RCBC underneath Hofmann
Drive is required due to the increased flows along the eastern boundary of the site. It is proposed to upgrade
this culvert to a 2400 mm x 600 mm RCBC. Within the developed scenario, the existing bank of 4 x 2400 mm
x 800 mm RCBCs at the discharge point was tentatively modelled with an additional barrel. This was done to
ensure that peak flows leaving the site would discharge into the environmental reserve effectively. The
requirement for the additional barrel will be confirmed by more detailed modelling to be undertaken for the final
design.
A 750 mm RCP is proposed to connect to the existing 750 mm RCP entering the site off Commerce Court.
This pipe conveys flows around the development footprint and discharges upstream of the 2400 mm x 600 mm
RCBC under the access road connecting to the roundabout on Hofmann Road.
The peak 1% AEP flood level at the north-west corner of the site (P1) is approximately RL 9.3 mAHD, dropping
to 8.8 mAHD at (P4). The flow path around the north-eastern corner of the development area has a crest at
8.5 mAHD at the north eastern corner of the site and thereby acts as the hydraulic control for flood waters.
The floodplain to the north of the development detains floodwaters and drains via a field inlet connected to the
750 mm RCP through the site via a 450 mm RCP. This drainage feature allows the area to the north to drain
after a flood event. The modelled post-development flood levels are shown in Table 6-2.
Table 6-2       Developed Flood Level (mAHD)
                                                  Developed Flood Level (mAHD)
    Location            39% AEP            20% AEP             10% AEP              5% AEP                2% AEP        1% AEP
        P1                 8.81                8.96               9.07                9.14                 9.27           9.33
        P2                 8.48                8.60               8.63                8.68                 8.76           8.8
        P3                 9.85                9.85               9.85                9.86                 9.87           9.87
        P4                 8.48                8.60               8.63                8.68                 8.76           8.80
        P5                 N/A                 N/A                 N/A                 N/A                 N/A            N/A
        P6                 6.79                6.80               6.82                6.84                 6.86           6.87
        P7                 4.50                4.53               4.53                4.55                 4.56           4.56
        P8                 4.44                4.46               4.46                4.47                 4.48           4.49
        P9                 6.64                6.65               6.66                6.67                 6.69           6.69
        P10                N/A                 N/A                 N/A                 N/A                 N/A            N/A
*N/A meaning that the point of interest is out of the flood waters or located on a development building


V190428 | 15 May 2019 | Commercial in Confidence                                                                                  22