RFI - stormwater report

2 Stormwater Quality
2.1 Design Objectives
This report identifies the stormwater quality management objectives for the operational
phase (post-construction phase) of the proposed development. Construction based
stormwater quality management objectives will need to be addressed as part of
operational works documentation.
The load based Water Quality Objectives (WQO’s) stipulated in the State Planning Policy
(DILGP, 2017) for the South East Queensland region will be adopted for the site. The
applicable water quality design objectives for the site are shown in Table 2-1 below.
Table 2-1: Site stormwater quality objectives (operational phase)

       Minimum reductions in mean annual loads from unmitigated development (%)
   Total Suspended       Total Phosphorous         Total Nitrogen    Gross pollutants
     Solids (TSS)               (TP)                    (TN)             >5 mm
          80                     60                      45                90

2.2 Stormwater Quality Treatment
2.2.1 Strategy
The objective of this report is to assess the stormwater quality measures required based
on the development layout prepared in order to support the development application.
The treatment train for the proposed development consists of runoff from the
development being discharged to bioretention basins prior to discharging from the site.

2.3 Modelling Approach
2.3.1 MUSIC Parameters
An assessment of stormwater runoff quality from the proposed development site has
been assessed using the Model for Urban Stormwater Improvement Conceptualisation
(MUSIC) – Version 6.30, released in 2017.

Climate data for the catchment was sourced from the MUSIC model database. The
rainfall and evaporation data template for this site has been based on data from Cooroy
from 1/1/1973- 31/12/1983 with six (6) minute rainfall duration. Table 2-2 and Table
2-3 outline the adopted source node parameters from MUSIC Modeling Guidelines
(Water By Design, 2010) that were used in the MUSIC model.




                                                                                        6