Amended Stormwater Plan

SC5551 - 28 Elkhorn Dr, Tewantin                                                                        9




3.3.2.2 Treatment Nodes
The following devices have been used in the treatment train to reduce these pollutant loads to achieve WQO’s
before discharging into the Elkhorn Drive drainage system.


    Bio-Retention Basin – An area of 70m2 designated Bio-retention to treat road, landscape, and roof
    catchments to achieve the WQO’s was modelled. An extended detention depth of 200mm with a filter
    media of 200mm/hr sandy loam hydraulic conductivity has been modelled. The location of this device
    is shown on the attached Appendix A.



3.3.3    Effectiveness in Pollution Reduction
The water quality development model was set up with the incorporation of the above devices to reduce
pollutant export to WQO levels. Table 3.5 indicates the predicted pollutant mean values of stormwater
discharged from the site as calculated by MUSIC:


                                   Pollutant                 Percentage Load Reduction

                        Total Suspended Solids (TSS)                  82.8%

                            Total Phosphorus (TP)                     62.4%

                              Total Nitrogen (TN)                     49.9%

                           Gross Pollutants (>5mm)                     100%

                                   Table 3.5 - Flow Based Pollutant Load Reduction



The MUSIC modelling results shown above indicate that the treatment train will adequately treat TSS, TP
and TN generated by stormwater runoff in accordance with the targets required under the water quality
objectives stated previously.