Stormwater Treatment & Water Quality Management Plan_April2014

                                                                               Callaghan & Toth

4.       WATER QUALITY MANAGEMENT PLAN
4.1      Proposed On-Site Stormwater Treatment Process

The developed site was divided into MUSIC model sub-catchments as shown on Figure 4.1.
The proposed stormwater treatment train for the overall development site is illustrated on
Figure 3.1 and Figure 3.2 and are described below:
       a. One small Bioretention Basin (BioBasin 1)(already completed for Stage 1 i.e. Lots 1
           to 4),
       b. Two medium Bioretention Basins located in parkland treating runoff as follows:
              i. BioBasin 3 – Stages 2 and 5 i.e. Lots 5 to 16 and associated road reserve, and
             ii. BioBasin 2 – Stage 4 i.e. Lot 33 to 57.
       c. Three small Roadside Bio Basins (1a, 1b and 2) treating runoff from Lots 21 to 25
           and associated road reserve (part of Stage 3),
       d. Two Bioretention swales treating runoff from Lots 17,19,20,29 to 32 and associated
           road reserve (part of Stage 3),
       e. Three Raingardens for Lots 26, 27 & 28 (part of Stage 3), and
       f. A grassed buffer to treat sheet flow of road connecting Stage 3 to Blue Wren Place.

BioBasin 3 is located within the new Passive Parkland Area and discharges into the eastern
tributary. The three (3) raingardens will be located within the lots which they are treating and
also discharges into the eastern tributary
.
BioBasin 2 is located within the new Passive Parkland Area, the small roadside Bio Basins and
the swales are located along the new roadway off Blue Wren Court and these systems all
discharge into the western tributary.

The bio-retention component of these treatment systems will remove the nutrients, heavy
metals, and retard flow.

4.2      MUSIC Model
4.2.1 Source Nodes

Catchment areas of source nodes within the proposed development have been identified as
sub-catchments such as roofs, yard, road and verge. MUSIC allows for characteristics of these
source nodes to be amended to ensure that accurate pollution generation and hydraulic
characteristics for each sub-catchment are used to generate stormwater runoff within the
model. Table 4.1 below details the sub-catchments used in the MUSIC model, land use,
percent imperviousness and area of each sub-catchment. The MUSIC Modelling Guidelines for
South-East Queensland – Version 1 December 2010 have been used to set level of
imperviousness. The urban residential pollutant export parameters within the guidelines have
been used for each node.

The site has also been divided into three (3) main discharge points and modelled as such,
being
     Lots 1 to 16, and 26 to 28 discharging into creek flowing from east to west coming from
       Lake MacDonald Drive
     Lots 17 to 25 and 29 to 32 discharging into eastern side of creek flowing from south to
       north coming from Blue Wren Place
     Lots 33 to 57 discharging into western side of creek flowing from south to north from
       Blue Wren Place.


55 Lake MacDonald Drive – Stage 1 to 5                                                   pg. 12