Attachment D amended SWMP

Bio-Retention System
The following table summarises the individual parameters used in the MUSIC model for the proposed
conventional bio-retention system.
Table 13 - Bio-Retention Details

                              Properties                              Basin 1

                              Extended Detention Depth (m)              0.30

                              Minimum Surface Area (m²)                  68

                              Minimum Filter Area (m²)                   68

                              Saturated Hydraulic                       200
                              Conductivity (mm/hr)

                              Minimum Filter Depth (m)                   0.4

                              Maximum TN Content (mg/kg)                400

                              Maximum Orthophosphate                     30
                              Content (mg/kg)

The proposed surface area has been calculated on equal surface area method to ensure most accurate filter
area. The final surface area will be larger than the area outlined above however was reduced during the
modelling to ensure the stormwater quality requirements are met.

6.2.1.7 Treatment Train Effectiveness
The table summarises the effectiveness of the proposed treatment trains modelled in MUSIC.
Table 14 - Treatment Train Effectiveness Result

                                                                          Achieved
                                              Inflows    Outflows                          Targeted
                Source Pollutants                                      Treatment Train
                                               (kg/yr)    (kg/yr)                          Reduction
                                                                          Reduction

         Total Suspended Solids (kg/yr)         1350        269                80.1%             80%

         Total Phosphorus (kg/yr)                2.6       0.679               73.8%             60%

         Total Nitrogen (kg/yr)                 13.7        6.11               55.4%             45%

         Gross Pollutants (kg/yr)               120         4.75               96%               90%



Results show that the proposed treatment train achieves the required water quality objectives.




 BR210522_SBSMP_Rev5.docx                                                                              Page 16 of 25