Attachment D amended SWMP

6.2.1.3 Model Selection, Assumption & Removal Effectiveness
In accordance with the Water by Design MUSIC Modelling Guidelines, split catchment methods were used for
the source Nodes utilizing modified % impervious area. Also, rainfall threshold, soil properties & pollutant
concentration input values were sourced from the guideline.
The MUSIC modelling inputs for the rainfall source nodes are shown below.
Table 9 - Music Source Parameters

                  Source Node Parameters – Sub Catchments                      Commercial

                                  Rainfall Threshold (mm/day)                      1

                                   Soil Storage Capacity (mm)                      18

                                 Initial Storage (% of Capacity)                   10

                                           Field Capacity                          80

                               Infiltration Capacity Coefficient - a              243
                  Rainfall -
                   Runoff
                                Infiltration Capacity Exponent - b                0.60

                                          Initial Depth (mm)                       50

                                       Daily Recharge Rate (%)                     0

                                       Daily Base flow Rate (%)                    31

                                  Daily Deep Seepage Rate (%)                      0


Base flow and Storm flow parameters for TSS, TP and TN for roofs, roads and ground levels were sourced from
Water by Design MUSIC Modelling Guidelines. Refer below for a summary of the parameters where used for
the model.
Table 10 – Commercial Source Node MUSIC Input Parameters

                               TSS log10 values           TP log10 values              TN log10 values
                Surface
 Flow Type
                 Type
                               Mean         St. dev.    Mean         St. dev.      Mean         St. dev.

                  Roof         N/A            N/A        N/A           N/A             N/A        N/A
  Baseflow
 parameters
                 Roads         0.780         0.390      -0.600         0.500       0.320         0.300

                Ground         0.780         0.390      -0.600         0.500       0.320         0.300

                  Roof         1.300         0.380      -0.890         0.340       0.370         0.340
 Stormflow
 parameters
                 Roads         2.430         0.380      -0.300         0.340       0.370         0.340

                Ground         2.160         0.380      -0.390         0.340       0.370         0.340




 BR210522_SBSMP_Rev5.docx                                                                                  Page 14 of 25