Appendix B - Biome Consulting Response

The pollutant export and runoff parameters adopted for each sub catchment were as prescribed
within Table 3.8 and Table 3.7 of the Water by Design MUSIC v6 Modelling Guidelines (2010) for an
urban residential catchment. Table 3 summarises the bioretention node parameters.

                                              Table 3 Bioretention Parameters
                                   Parameter                                                           Bioretention D3
                                                   2
                               Surface area (m )                                                              75
                         Extended detention depth (m)                                                         0.2
                                               2
                                Filter area (m )                                                              75
                       Unlined filter media perimeter (m)                                                     0.01
                    Saturated hydraulic conductivity (mm/hr)                                                  200
                                Filter depth (m)                                                              0.4
                       TN content of filter media (mg/kg)                                                     400*
                   Proportion of organic material in filter (%)                                               <5
                Orthophosphate content of filter media (mg/kg)                                                30*
                               Is the base lined?                                                             Yes
                       Effectiveness of plant TN removal                                                  Effective
                            Overflow weir width (m)                                                    Surface Area/10
                            Exfiltration rate (mm/hr)                                                         0.00
                              Underdrain present?                                                             Yes
                    Submerged zone with carbon present?                                                       No
                  Confirmation that K and C* remain default?                                                  Yes

         Sediment Forebay Required (>2.5 ha contributing catchment)                                           Yes
*As per Healthy Land and Water Recommendations for MUSICv6 modelling

Modelling Results
Results of the MUSIC v6 modelling for the treatment train effectiveness are summarised in Table 4,
and show that the 80%, 60%, 45% and 90% reduction targets for TSS, TP, TN and gross pollutants
respectively were achieved for the rainfall data set simulated. A screen capture of the modelling
results is included as Figure 2.

                                          Table 4 Treatment Train Effectiveness

                              Inflows                   Outflows           Reduction               Reduction             Water Quality
    Pollutant
                               (kg/yr)                   (kg/yr)            (kg/yr)               Achieved (%)           Objective (%)

        TSS                    1,110                      166                   944                    85.1                  80.0
        TP                      2.29                      0.52                  1.77                   77.3                  60.0
        TN                      13.9                      6.33                  7.57                   54.5                  45.0
        GP                      157                         0                   157                    100                   90.0
NOTE: All simulations have been run with pollutant export estimation set to “stochastic generation”.




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