SWMP change reps

5.3.4    Pollutant Modelling
The impact of the stormwater quality management strategy of runoff discharged from the site has been
assessed using the Pollutant Export Model, Model for Urban Stormwater Improvement
Conceptualisation (MUSIC).

For our model the proposed treatment train has been modelled: -

         1.     Roof water from buildings containing units 301-304, 401-404 will be collected by a 7kL
                rainwater re-use tank with an overflow to an onsite Bio retention basin, namely Bio-
                Retention Bed A (BR-A) located in the north-eastern corner of the site. The rainwater
                tank will be re-used for area landscaping irrigation only, to all common areas.
         2.     Roof water from buildings containing units 701-704 and the front portion of 601-602 will
                be collected by a 7kL rainwater re-use tank with overflow to the onsite Bio retention
                basin, namely Bio-Retention Bed B (BR-B) located in the South-eastern corner of the
                site. The rainwater tank will be re-used for landscaping irrigation only, to all common
                areas.
         3.     Surface runoff from hardstand and landscaping areas will be collected by numerous catch
                pits and pipes. The internal drainage network will then discharge into the onsite bio
                retention basins for treatment.

The Music Model was set up in accordance with the Water By Design Music Modelling Guidelines for
South East Queensland. Design parameters are listed below:

BR-A

         •      Surface Area                           =     85m2
         •      Filter Media Area                      =     50m2
         •      Filter Depth                           =     0.4m
         •      Extended Detention                     =     0.2m
         •      Hydraulic Conductivity                 =     180mm/ Hr
         •      TN content of Filter Media             =     500mg/ kg
         •      Orthophosphate content of Filter Media       =       5mg/ kg

BR-B

         •      Surface Area                           =     30m2
         •      Filter Media Area                      =     25m2
         •      Filter Depth                           =     0.4m
         •      Extended Detention                     =     0.2m


SCG Consulting Engineers                     Page 13                           SCG Ref: 33132(SWMP).RevC