Appendix D- Stormwater Management Plan · MCU23/0078

2.3     TOPOGRAPHY AND CATCHMENT CHARACTERISTICS

        The topography and catchment characteristics for the development site, broken down between both Sites A and B, are
        discussed below:


2.3.1   Site A – Western Lot


            −    The high point of the existing site is RL 9.47m AHD located on the eastern side of the site;

            −    The development falls from the high point at an approximate grade of 2.5% to a low point of RL 3.88m AHD in
                 the south-western corner;

            −    During both minor and major storm events, runoff from the site discharges as overland flow over the western
                 boundary of the development site and onto the environmental zone and natural drainage channel, and is
                 ultimately conveyed through culverts below Hofmann Drive to Eenie Creek and Lake Weyba;

            −    As the roadways surrounding the site have been built assuming a fully developed catchment, there is no external
                 catchment.

2.3.2   Site B – Eastern Lot


            −    The high point of the existing site is RL 10.63m AHD located on eastern side of the site;

            −    The development falls from the high point at an approximate grade of 1% to a low point of RL 9.2m AHD in the
                 south-west corner;

            −    During both minor and major storm events, runoff from the site discharges as overland flow over the western
                 boundary of the development site and onto the private access roadway, and is ultimately conveyed to the
                 stormwater drainage system along the access roadway to Eenie Creek and Lake Weyba;

            −    Site B is split into two sub-catchments, with a high-point located midway along the private access road frontage,
                 with flows directed either towards the north-west onto the private access road and around Site A to the
                 environmental zone and natural drainage channel, or towards the south-west onto the private access roads; and

            −    As the roadways surrounding the site have been built assuming a fully developed catchment, there is no external
                 catchment.

        See the survey plan in Appendix C for more information.


2.4     EXISTING FLOODING CONDITIONS

        From Noosa Shire Council Plan Interactive Mapping, it has been obtained for the site and states the following:

            −    No flood levels or flags for building development purposes exist for the development site.

            −    The interactive mapping system within Noosa Shire Council Plan confirms that the development site is not
                 affected by Eenie Creek or overland flow flooding.

            −    It is expected that the site is at a low risk of flood inundation.




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