ECM_22343539_v1_Stormwater Management Report

                 2. 2       Law fu l P oint of D is ch ar ge

                 Roofwater runoff from the existing dwelling is assumed to discharge to ground level and discharge to
                 the east with ground level runoff as sheet flow.
                 The proposed lawful point of discharge for the roofwater from the proposed development shall be The
                 Esplanade kerb and channel via the construction of a new kerb outlet. Runoff from the upper impervious
                 ground level areas shall be directed to a soakage trench with the remaining lower pervious areas
                 continuing to discharge to the east as sheet flow. Roofwater runoff from the proposed development
                 shall be collected on site and directed to the new outlet via the construction of new on site drainage.
                 Refer to Appendix B for further information regarding the proposed stormwater works for the
                 development.

                 2. 3       Ups tr e am D r ain ag e C onne ct ion

                 The development site does not have any upslope properties unable to gravity drain to a lawful point of
                 discharge.

                 2. 4       Flood ing

                 The proposed development site is not impacted by any NC flood mapping and is therefore considered
                 to be flood free.

                 3      STO R M WAT E R Q UA N TIT Y M AN AG E ME NT


                 A detailed stormwater quantity analysis of the existing and developed site conditions has not been
                 undertaken as the proposal is for a residential dwelling on an existing residential lot with final impervious
                 area fraction being generally in line with lump C10 values for low density residential lots.

                 4      W AT ER Q U AL IT Y M A NAG E M EN T


                 4. 1       O pe r at io na l Ph a se

                 The development is not required to meet the Queensland Government’s State Planning Policy (July
                 2017) as the site does not exceed the 2,500m2 minimum site area. However stormwater quality
                 management must still be undertaken via the application of best management practices (BMPs) to
                 ensure no adverse impacts to the downstream environment.

                 Pollutants typically generated during the operational phase of the development include:

                        •    Litter/gross pollutants;

                        •    Sediment;

                        •    Nutrients (N & P);

                        •    Hydrocarbons (oils and grease); and

                        •    Heavy metals.

                 Stormwater quality best management practices may be implemented for the development as follows:

                        •    First flush diversion system for roof water diverting the roof water for irrigation purposes

                        •    Rainwater storage tanks may be used to collect rainwater for landscape irrigation.
                 Best management practices have been deemed sufficient for the site area and land use. Refer to
                 Appendix B for the stormwater management drawing.



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Document Set ID: 22343539
Version: 1, Version Date: 16/03/2023