Stormwater Management Report

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

As the site is not within Unitywater’s service area, it is expected that roofwater runoff from the existing
dwelling would be directed to rainwater storage tanks for reuse. The ground level farmland areas
generally fall to respective gullies as sheet flow and then discharge off site.

It is proposed to maintain existing conditions as part of the development proposal. Roofed areas of the
development shall all be directed to rainwater storage tanks for use on site with overflow being allowed
to discharge to ground level. 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, unimproved properties unable to gravity drain to a
lawful point of discharge.

2. 4       Flood ing

The proposed development site is not impacted by NC flood overlay mapping for any flood sources.

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 rural residential development on an existing 43.2Ha lot. It is not
expected that the resultant impervious area fraction would significantly exceed 10%.

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 proposal is for a rural residential development nor would the proposal result in an
impervious area fraction in excess of 25%. 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 will be implemented on site collecting runoff from all roofed areas for
            reuse on site.

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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