Appendix I - Stormwater Management Plan

       4         Stormwater Quantity Management

       4.1       Stormwater Quantity Management Assessment

                 The stormwater quantity management assessment demonstrates that overland flow
                 within the network is reduced as a result of this development and is therefore not
                 expected to adversely impact on the stormwater network. Further details are outlined
                 in the following sections.


       4.2       Q100 Flood Assessment

                 Review of Noosa Shire Council’s storm tide information map for area 10-D34 (which
                 includes this site) confirms that the site is not subject to storm tide inundation.
                 Additionally, the river flood information map 10-D34 map confirms that the site is not
                 subject to river inundation.
                 Refer to Council maps attached in Appendix C.


       4.3       Lawful Point of Discharge

                 The existing stormwater overland flow from the site currently sheet flows across the
                 subject property and discharges towards the northeast and northwest sections of the
                 site onto Gateway Drive.
                 The proposed development will maintain a lawful point of discharge to Gateway Drive.


       4.4       10 Year ARI – Contributing Catchment Flows

                 The total site area (0.1266 ha) accounts for less than 5% of the total catchment area
                 associated with the overall stormwater network system (2.66 ha) and as such,
                 assessment of stormwater quantity has been undertaken on the assumption that the
                 additional flows resulting from the development will be negligible. Furthermore, it is
                 assumed that the recently constructed stormwater network along Gateway Drive, east
                 of the development site has been designed with sufficient capacity to allow for
                 development of the site. Therefore, this assessment will utilise the Rational Method
                 for comparative purposes to identify flows associated with the pre and post
                 development scenarios for the 10 year and 100 year ARI rain events.
                 Analysis of the minor event recognises the requirements pertaining to pipe capacity
                 for commercial development in accordance with QUDM is for a 10 year ARI. PCdrain
                 was utilised to model the internal stormwater network to ensure the requirements of
                 QUDM are achieved. Results of the analysis confirm that the proposed internal
                 stormwater network is sufficient to accommodate 10 year ARI flows. Results are
                 presented in Appendix E.



Mogpropmanagement Pty Ltd                         Page 9                                   205-002-002R
Stormwater Management Plan
Noosaville Site