Stormwater Management Plan

GOOD SHEPHERD LUTHERAN COLLEGE                                                             ODYSSEY CONSULTING GROUP
Lot 30 on SP170751                                                              Conceptual Stormwater Management Plan
115 Eumundi Noosa Road, Noosaville                                                                    Project No: K4277

         Comparison of Pre Development, Post Development and Mitigated Flow Rates for Catchment B
         Table 15:      Comparison of Pre Development, Post Development and Mitigated Flow Rates for Catchment B
           Average Recurrence Interval                                    2                10               100
                                                       3
           DRAINS Pre Development Flow Rate          m /s               0.104            0.169              0.277
           DRAINS Post Development Flow Rate           3
                                                     m /s               0.165            0.266              0.429
           Catchment A Q100
                                                       3
           DRAINS Mitigated Development Flow Rate    m /s               0.104            0.169              0.277




         Figure 3:      Mitigated Post Development Catchment Q100 Flow Rates

         Catchment A will be collected by a detention tank to mitigate flows to less than that of the pre
         development scenario and will discharge to a LPOD on Eumundi Noosa Road. With reference to Figure
         3 the detention arrangement can be seen to effectively mitigate the post development flows in all
         storm events for the proposed site.
                                                                                                        3
         The hydraulic analysis using the DRAINS model has determined that a minimum of 133 m of storage
         is required for runoff attenuation and is to be provided in the form of a detention tank located within
         the open space area. Refer to Odyssey Consulting Group, Stormwater Management Plan (Ref:
         K4277/P007/E) and Odyssey Consulting Group, Stormwater Detention and Bio retention Details (Ref:
         K4277/P010/D) included as Appendix F, for details of the tank arrangement, indicative location and
         preliminary stormwater layout. The final location onsite and construction levels will be determined at
         detailed design stage.

         A copy of the DRAINS model used in this report can be made available to Council upon request.



5.0 WATER QUALITY ASSESSMENT
5.1      Background
         The development of land has the potential to increase the pollutant loads within stormwater runoff
         and downstream watercourses.

         During the construction phase of the development disturbance to the vegetation on the site has the
         potential to significantly increase sediment loads entering downstream watercourses. The operational
         phase of the development will increase the density of residential land use potentially increasing the
         amount of sediments and nutrients washing from the site.




K4277-0002-D                                        14 February 2019                                        Page 9 of 16