H - Revised Integrated Water Management Plan by Cardno (inc MUSIC file) (13.09.19)

4 Modelling WSUD Tree Pits
4.1 Water Quality Modelling
   4.1.1 MUSIC by eWater
   MUSIC (the Model for Urban Stormwater Improvement Conceptualisation) is a modelling tool used to provide water
   quality analysis of proposed stormwater treatment systems. This model was initially developed by the Cooperative
   Research Centre for Catchment Hydrology (CRCCH) and is a standard industry model for this purpose. MUSIC is
   suitable for simulating catchment areas of up to 100 km2 and utilises a continuous simulation approach to model
   water quality.
   By simulating the performance of a range of stormwater treatment measures, MUSIC can be used to determine the
   ideal treatment solution and optimise the treatment size to achieve stormwater management objectives. The primary
   water quality constituents modelled in MUSIC include Total Suspended Solids (TSS), Total Phosphorus (TP) and Total
   Nitrogen (TN) and Gross Pollution (GP).


   4.1.2 Modelling Stratacell/Stratavault in MUSIC
   MUSIC can be used to model the storage benefits of an empty Strataflow Tank System and/or the water quality
   benefits of WSUD Strataflow tree pit with a soil media fill.
   A procedure has been developed to assist in sizing and specifying a tree pit or tank system to meet water quality or
   water quantity objectives, within MUSIC.
   The aim of the following procedure is to provide a quick guide of how to setup a MUSIC model and input appropriate
   parameters to ensure the model produces the most accurate and representative results.
   An overview of the modelling procedure is provided in the chart below.


 Step 1 - Model Set Up                                                                            Step 2 - Catchment Node
   • Set up the meterological template for the project site                                         • Edit the catchment parameters to specify the
   • Create a catchment node                                                                          catchment area and % imperviousness
   • Create a bioretention node to simulate a WSUD Strataflow tree pit, OR                          • Edit the pollution generation parameters within the
                                                                                                      catchment node to match the charcteristics and
   • Create a Tank Node to simulate a StrataflowTank Configuration, OR
                                                                                                      landuse of the modelled catchment. If the site specific
   • Create an Infiltration Node to simulate a leaky tank or                                          pollutant generation parameters are not available, leave
     infiltration system                                                                              the default values.
   • Identify Catchments
   • Initial modeling accordint to objectives
   • Water Quality/Detention/Infiltration Tree health
   • Services and constraings assessment
   • Assess site conditions


                                                                                                  Step 3 - Treatment Node
                                                                                                    • Edit the tree-pit (bioretention) node to specify its area,
 Step 4 - Run Model and Output Results                                                                ponding depth, filter depth, infiltration rate, etc... OR
   • Run the model                                                                                  • Edit the Tank node to specify it’s area, tank height,
   • Generate a model output to determine if the design meets                                         outlet size, etc... OR
     stormwater targets                                                                             • Edit the Infiltration node to specify it’s area, storage
                                                                                                      depth, infiltration rate, etc...




 Step 5 - Model Optimisation
   • Adjust the design/tree pit size until stormwater targets are met (or best possible outcome is achieved).




A more detailed step by step procedure is outlined in Appendix C.
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