Stormwater Management Report

The Rainfall Runof Parameters for the source catchment nodes have been taken from Table 3.7 of Water By Design’s
– MUSIC Modelling Guidelines, Version 1.0 (2010) and are shown in Table 2 below.

                                           Table 2 – Rainfall Runoff Parameters

                               Rainfall threshold (mm/day)                          1
                                                Pervious Area Properties
                               Soil storage capacity (mm)                           18
                               Initial storage (% of capacity)                      10
                               Field capacity (mm)                                  80
                               Infiltration capacity coefficient – a                243
                               Infiltration capacity exponent - b                   0.6
                                                Groundwater Properties
                               Initial depth (mm)                                   50
                               Daily recharge rate (%)                              0
                               Daily baseflow (%)                                   31
                               Daily deep seepage rate (%)                          0


The pollutant load concentrations for the source catchment has been taken from Water By Design’s – MUSIC
Modelling Guidelines, Version 1.0 (2010) using the concentrations recommended for industrial areas.

 The model was run for an average rainfall recorded at Caloundra Rainfall Station 40040, between the years 2000-
2010 and using a 6 minute time step. The mean annual rainfall for Caloundra area is 1543mm.




8.2 MUSIC Model Results


The proposed treatment train modelled with MUSIC, includes the following water quality treatment measures:

A bio-retention basin will be constructed within landscaped areas to the south-east corner of the site adjacent the
                                                                            2                                2
existing bushland. The bio-retention basin is to have a total area of 74.7m and a filter media area of 39m and is to
accept runoff for all roofs, hardstand and majority of landscaped areas prior to discharging into the existing drainage
infrastructure. The basin has been modelled with an extended detention depth of 200mm, a hydraulic conductivity of
200mm/hr and a filter media depth of 400mm.

The results are shown in Table 3 below:

                                          Table 3 - Treatment Train Effectiveness




These results indicate that the water quality objectives have been achieved based on the proposed treatment train for
all pollutants in the stormwater discharge.


HR DESIGN                                         Reference No: 18-0165A                                    Page 8 of 14