07/1841 - Response to Information Request [As Published] · 132007.1841

STORMWATER QUALITY MANAGEMENT PLAN 5

 

the bottom layer will carry flow to the outlet of the bio-retention areas. The

location of these bio-retention areas is shown in appendix B.

- Rainwater Tanks — These tanks will be positioned the proposed carparks. Runoff
will be collected from the roof of the development at a rate of 151/m? of roof. This
results in a total volume of rainwater storage of approximately 113kL. Water

collected will be used for irrigation or other external uses

2.3 — Rainfall Data

Rainfall data for the site was chosen to give the best representation of actual conditions
to be expected. The meteorological data selected in the MUSIC program was the
Cooroy 30/11/1980 — 31/05/1990 data provided by the Bureau of Meteorology, using
a 6 minute time step. This period of data was used as requested by Noosa Shire

Council.

2.4 — Assessment of Results

The specified water quality objectives have been met on the subject site for total
suspended solid (TSS), total phosphorus (TP), and total nitrogen (TN) concentrations
through the use of a gross pollutant trap, rainwater tanks, and bio-retention areas.

Appendix B contains the following MUSIC output:

« Flow based sub-sample daily mean cumulative frequency graphs,

« Treatment train effectiveness for the system,

« Node Layout

Table 2.3 below indicates the predicted export pollutant concentrations calculated by

MUSIC;

Table 2.3: Predicted Post-Development Treated Water Quality

 

 

 

 

 

 

 

 

 

 

Indicator % Reduction Predicted Value
Tota! Suspended Solids (TSS) 98.6 0.201 mg/L
Total Phosphorus (TP) 78.5 0.0105 mg/L
Total Nitrogen (TN) 50.0 0.129 mg/L
BARLOW GREGG VDM M3048

DECEMBER 2007