Development Application part 7 of 10 Stormwater Management Report - MCU13/0092

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4.4 Catchment Annual Pollutant Loads


An assessment of stormwater quality was undertaken for the developed unmitigated site. The discharge
concentrations of key pollutants from the site were then compared to the wao’s. The pollutant concentrations were
obtained by running a MUSIC model with the model parameters sourced from Water by Design Music Modelling
Guidelines (Version 1.0 2010). MUSIC is the Model for Urban Stormwater Improvement Conceptualisation,
developed by the MUSIC Development Team of the CRC for Catchment Hydrology.

MUSIC has the ability to simulate quality of runoff from catchments ranging from a single house block up to many
square kilometres, and the effect of a wide range of treatment facilities on the quality of runoff downstream. By
simulating the performance of storm water quality improvement measures, MUSIC determines if proposed systems
can meet   specified water quality objectives.

Table 3 details the MUSIC parameters utilised in running the model.


                                     Table 3: MUSIC Model Parameter Summary


                        Meteorological Data                           40059 COOROY
                                                                1973-1983 6 minute BOM
                        Source Node                                    Commercial
                        Effective Impervious Area                         Varies
                        Effective Pervious Area                           Varies
                        Modelling Time Steps                             6 Minute
                        Drainage Link                                   No Routing
                        Pollutant Concentration                         Industrial
                        Soil Properties                                 Industrial
                        Treatment Devices                       Stormwater360 Enviopod
                                                            Stormwater360 Stormfilter System
                                                                      Rainwater Tank


MUSIC calculated the following annual pollutant loads for the 1 combined catchment:


                               Table 4: Annual Pollutant Loads and Concentrations


                       Pollutant                      Annual Load
            Total Suspended Solids                      998 kg/yr
            Total Phosphorus                            1.74 kg/yr
            Total Nitrogen                              8.11 kg/yr
            Total Gross Pollutants                      59.0 kg/yr




The above loads have been based on land use as a commercial site as designated in the the Water by Design
Pollutant Export Parameters for split catchment land use (log10 values) Table 3.8 P.16.




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