Stormwater Management Plan · MCU18/0019

SC7440 – Goodchap St, Noosa                                                                                     8




3.3.3   Pollutant Export Modelling
The Model for Urban Stormwater Improvement Conceptualisation (MUSIC) has been utilised to calculate
pollutant loads from the proposed development and to predict performance characteristics of the proposed
treatment train. Modelling parameters used were adopted from the Water by Design “Music Modelling
Guidelines for South-East Queensland”, and the updated MUSIC Version 5 recommended parameters for
Bio-retention basin nodes. MUSIC modelling setup and results are attached within Appendix B.


Under the proposed conditions, the site was ‘split’ into three land use catchment nodes; the roofed area,
driveways and ground level uses. The pollutant export parameters utilised were based on the Urban
Residential pollutant loads, refer Tables 3.4 & 3.5. The pollutants have been generated stochastically in the
modelling scenario.


                      Parameter                                                      Value
               Rainfall threshold (mm)                                                1
             Soil storage capacity (mm)                                              500
              Initial storage (% capacity)                                            10
                 Field capacity (mm)                                                 200
         Infiltration capacity coefficient (a)                                       211
          Infiltration capacity exponent (b)                                          5.0
                  Initial depth (mm)                                                  50
               Daily recharge rate (%)                                                28
               Daily baseflow rate (%)                                                27
             Daily deep seepage rate (%)                                              0
                       Table 3.4 – Rainfall-runoff Parameters Adopted (Urban Residential)



                                             TSS Log                 TP Log                         TN Log
 Flow Type      Surface Type
                                     Mean        Std Dev.    Mean        Std Dev.            Mean       Std Dev.
                      Roof             N/A         N/A        N/A             N/A            N/A             N/A
  Baseflow
                  Driveways            1.00        0.34      -0.97            0.31           0.20            0.20
Parameters
                 Ground Level          1.00        0.34      -0.97            0.31           0.20            0.20
                      Roof             1.30        0.39      -0.89            0.31           0.26            0.23
 Stormflow
                  Driveways            2.43        0.39      -0.30            0.31           0.26            0.23
Parameters
                 Ground Level          2.18        0.39      -0.47            0.31           0.26            0.23
                        Table 3.5 – Pollutant Export Values Adopted (Urban Residential)