H - Revised Integrated Water Management Plan by Cardno (inc MUSIC file) (13.09.19)

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



Table 7-2       Existing Flood Level (mAHD)

                                                     Existing Flood Level (mAHD)
    Location           39% AEP           20% AEP              10% AEP        5% AEP                2% AEP           1% AEP
        P1               8.89                 8.93              8.98               9                 9.05             9.07
        P2                8.2                  8.2              8.22           8.25                  8.27             8.28
        P3               10.12                10.13             10.14          10.14                10.15            10.15
        P4               8.25                 8.26              8.27           8.27                  8.28             8.28
        P5               7.07                 7.06              7.09               7.1               7.1              7.11
        P6                6.9                 6.89              6.92           6.93                  6.93             6.93
        P7               6.73                 6.73              6.74           6.75                  6.74             6.76
        P8               5.92                 5.97              6.08           6.08                  6.08             6.08
        P9               6.31                 6.31              6.38           6.43                  6.43             6.46
        P10              5.56                 5.62               5.7               5.7               5.7              5.7
        P11               4.5                 4.54              4.59           4.59                  4.58             4.6
        P12              4.32                 4.33              4.44           4.48                  4.45             4.48


7.4.3         Post- Development Scenario
For the post development scenario, the development footprint has been set at a nominal level to form a
complete blockage of any flowpaths that cross the area in the existing case. A service road is proposed to be
located around the north-east and northern edge of the development area. The level of this road will be set in
detailed design phases of this project. This service road will function as an overland flowpath in the larger
events that exceed the capacity of the proposed 750 mm RCP. Flows from catchments to the North and North
West of the site area will be conveyed around the development via the service road flow path. Minor
catchments to the west of the site have been included in the quantity analysis as it is assumed that these flows
will be captured by the site drainage.
For the post development scenario, an upgrade to the existing under sized 1200 mm x 300 mm RCBC at the
site access from 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 700 mm RCBC, reducing the flows currently being
diverted onto Hofmann Drive. (Figure 7-3, C26)
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 (Figure 7-3, C27, C28 C29). This extension of the existing 750 mm RCP is only intended to convey
flows in events up to the 39% AEP. The complete drainage networks for the existing and developed cases are
shown in Appendix C.
Flows from larger AEP events will follow the existing flow path through the northern portion of the site. The
service road describe above will assist in this conveyance around the north-east corner of the proposed
development. (Figure 7-4)
The proposed pipe network and overland flowpaths will need to be considered for easements/future land
encumbrances as per Council requirements.




V190428 | 10 September 2019 | Commercial in Confidence                                                                        26