Appendix D- SWMP

 29 September 2023




4.5.3 Stormwater Quality Management Strategy

In order to satisfy the requirements of the State Planning Policy July 2017 for the adequate
treatment of stormwater runoff, natural treatment solutions have been provided to remove
hydrocarbons, suspended solids and nutrients prior to being discharged from site.

5.3.3.1 Potential Pollutants Generated
The pollutants that could be potentially generated as a result of the development use are as
follows:

    •     Litter
    •     Sediment
    •     Nutrients (Nitrogen and Phosphorous)
    •     Hydrocarbons (oils and grease)
    •     Surfactants
    •     Pathogens/Faecal Coliforms (bacteria and viruses)

The MUSIC computer modelling program developed by the Co-operative Research Centre for
Catchment Hydrology was used to predict the performance of the proposed stormwater treatment
train.

At this stage the pollutants modelled in MUSIC are Total Suspended Solids (TSS), Total
Phosphorous (TP) and Total Nitrogen (TN).

5.3.3.2 Rainfall
The rainfall data used in the model was based on the Bureau of Meteorology data from rainfall
station 40059 Cooroy Composite. The model was run for a 10-year period from 1 January 1973 to
31 December 1983. The modelling time step was 6 minutes.

5.3.3.3 Rainfall Runoff Properties
In accordance with the recommendations of Water By Design’s MUSIC Modelling Guidelines for
South East Queensland rainfall runoff properties for commercial areas have been used.

These are listed in Table 1 below.




 Excellence with Economy in Engineering                                                          10
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