Referenced Document - MCU30/0030 · MCU13/0030

                                                                                       ~
                                                                                  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 Plan No.
1303-01. The proposed treatment train for the development site is illustrated on Plan No. 1303-
02 and listed below:


1. The Bioretention Basin will treat the stormwater runoff from the access roads, car parks,
     verge and rainwater tank overflow. The treated runoff will then be directed to a vegetated
     area within the property. The bio-retention component will remove the nutrients, heavy

     metals, and retard flow.

     The Bioretention Basin will be unlined and also act as a Detention basin.


2.   Rainwater Tanks will be required to collect water from the new roofs. The tanks are to be
     underground and are to have potable top-up when 90% empty with an overflow pipe
     discharging to the bioretention basins. The tank capacity is to be adequate for the supply of
     washing machine cold water, toilets, and landscaping.


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, carparks, road and verge areas. MUSIC allows for the
characteristics of these source nodes to be amended to ensure that accurate pollution
generation and hydraulic characteristics 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 site has been related to a "Commercial" land use and pollutant export
parameters detailed in the Guidelines for this land use have been used for each node.


TABLE 4.1           MUSIC CATCHMENT AREAS (DEVELOPED)


               Catchment                      Land Use         Music Impervious         Area (ha)


          Habitable Roof Area                Commercial              100%                 0.3574

             (CatchmentA)

       Car Park to Bio-retention             Commercial               90%                 0.0387
             (Catchment B1)

       Car Park to Bio-retention             Commercial               90%                 0.0571
             (Catchment B2)

              TOTAL                                                                      O.4532ha




                                                                                                    11
1303, Kabara Hostel, Cooroy                 IWMP.doc                             January 2013