MCU14/0106 & OPW15/0001 Appendix E - Stormwater Management Plan

Noosa Civic
Stormwater Management Plan




5                Conclusion
A Stormwater Management Plan has been prepared to support the Noosa Civic expansion. The key findings
of the investigation are detailed below.
         Regional Flooding
           The Regional flood and storm tide mapping indicates that the proposed development will be above
           the regional flood events.
         Stormwater Quantity
           The proposed development is predicted to increase the peak stormwater discharges from the site.
           Mitigation measures as shown in Figure 3 include:
             - Utilising storage in the car parks to a maximum depth of 300mm. For the purposes of the
               development application assessment, the levels were based on the preliminary engineering
               levels.
             - Reducing the capacity of the culverts under Hofmann Road to 4/1200x300 and raising the invert
               level from 3.05mAHD to 3.35mAHD whilst maintaining a 225 RCP at the original invert level for
               low flows; and
             - Utilizing the fauna passage as a discharge point for events above a 5 year ARI.
           Based on the analysis, the mitigation strategy is predicted to reduce the peak flows to existing
           conditions therefore causing no adverse flooding 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, 2013) and Noosa Shire Council. The proposed mitigation measures
           were found to satisfy the applicable water quality objectives.
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 Final                                        11 May 2015
J13041R2_Final SWMP.docx                        Commercial in Confidence                                     Page 15