Stormwater Management Report

2.2        Lawful Point of Discharge

Roofwater runoff from the existing dwelling appears to discharge via a stormwater outlet adjacent to the
southwestern corner of the shared accessway and continue downslope as sheet flow into existing stormwater
infrastructure.
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 on site
and discharged via new stormwater outlets on the western edge of the shared driveway. Runoff will continue
downslope in line with existing conditions and ultimately into stormwater infrastructure on The Esplanade. Refer to
Appendix B 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 and developed site conditions has not been undertaken as the
proposal is for a residential development on an existing residential lot without substantial change in site impervious
fraction as a result of the development.

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.




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