Approved Plans - MCU18-0097 · MCU18/0097

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




                          Figure 3:      Mitigated Post Development Catchment Q100 Flow Rates (25 minute Storm)

                          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 Walter Hay Drive. 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.

                          The hydraulic analysis using the DRAINS model has determined that a minimum of 100 m3 of storage
                          is required for runoff attenuation and is to be provided in the form of a detention tank located within
                          the proposed car park area. Refer to Odyssey Consulting Group, Stormwater Management Plan (Ref:
                          K4277/P007/G) and Odyssey Consulting Group, Stormwater Detention and Bio Retention Details (Ref:
                          K4277/P010/E) 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.

                          The following sections describe the predicted increase in pollutant loads generated by the proposed
                          development and treatment devices to mitigate the potential increases. In accordance with industry
                          guidelines suspended solids, nitrogen and phosphorus will be targeted for reduction during the
                          operational phase of the development.

                 5.2      Water Quality Objectives
                          To protect the water quality of the downstream watercourses the following water quality objective
                          has been applied to stormwater runoff from the site in accordance with State Planning Policy. The
                          following load reduction targets must be achieved when assessing the post-developed sites treatment
                          train (comparison of unmitigated developed case versus developed mitigated case):



                 K4277-0002-E                                         18 June 2019                                          Page 9 of 14
Document Set ID: 20894174
Version: 1, Version Date: 03/07/2019