RFI Response (rec. 4.09.25) S25-137 Stormwater Report_Optimized

2.2        Lawful Point of Discharge

Under existing site conditions, stormwater runoff is expected to discharge downslope as sheet flow toward the
southern boundary.
Stormwater drainage for the proposed development shall ensure no adverse impacts on upstream, downstream or
adjoining properties. Runoff from roof and hardstand areas for the proposed development is to be collected onsite
and discharged into an existing stormwater grate on Marcus Dunes Court. Runoff from ground surface areas below
the infiltration trench will continue to discharge downslope in line with existing conditions. Refer to Appendix C for
further information regarding the proposed stormwater works for the development.

2.3        Upstream Drainage Connection

The development site does not have any upslope properties that are unable to achieve a lawful point of discharge,
impacting the proposed development.

2.4        Flooding

The proposed development site is outside of flood and tide inundation extents indicated by NC disaster maps and is
considered to be flood free.

3          STORMWATER QUANTITY MANAGEMENT

A detailed stormwater quantity analysis of the existing site conditions has not been undertaken as the proposal is for
a residential development on a vacant residential lot within a small private community. No adverse impacts are
anticipated from the proposed development to the existing stormwater infrastructure within the community.

4          STORM WATER QUALITY MANAGEMENT

4.1        Operational Phase

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 C for the
stormwater management drawing.



 S25-137                                         Stormwater Management Report                              Page 2 of 6
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