MCU14/0106 Appendix E - Engineering Report

Noosa Civic
Stormwater Management Plan




4                 Conclusion
A Stormwater Management Plan has been prepared to support the proposed expansion of Noosa Civic. The
key findings of the investigation are detailed below:
          Regional Flooding
           Council’s regional flood and storm tide mapping indicates that the proposed development will be
           above all regional flood events.
          Stormwater Quantity
           A detention basin (see Figure 5) is proposed to be operated in conjunction with flood storage within
           the car park area to mitigate the potential impact on peak flow rate resulting from development of the
           catchment. Based on the analysis, mitigation of developed peak flows to existing conditions will
           result in no adverse flooding impacts external to the site.
          Stormwater Quality
           It will be necessary to treat runoff from the site to satisfy the water quality objectives defined by the
           State Planning Policy (DSDIP, 2014) and Noosa Shire Council.
           Modelling of two approaches for the treatment of runoff was completed using the industry-standard
           MUSIC software.
           o            Bio-basin Treatment
                        For this scenario, runoff from the entire site was considered to be treated by a bio-retention
                        systems as shown on Figure 6.
           o            Water Re-use Tank and Bio-Basin Treatment
                        For this scenario, a 300 kL rainwater tank capturing runoff from roof surfaces for suitable re-
                        use purposes, with the remaining water to then be treated by bio-basins to the required
                        standards, was considered.
           Both treatment scenarios were found to satisfy the applicable water quality objectives. A decision
           will be made at detailed design in relation to the solution to be ultimately adopted.


Given the results obtained with respect to stormwater quality and quantity, it is considered that the site can
be developed from a stormwater management perspective without producing unacceptable impacts.




QIC Noosa Civic Pty Ltd                                    Version 1                                     November 2014
Appendix D - SMP.docx                                                                                         Page 11