OPW16/0021- Operational Works Application 2 of 4

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(to!be!treated!and!used!for!household!use)!or!to!a!large!Stormwater!Tank!via!a!GPT!
and!reused!within!the!site.!!This!reuse!of!water!from!the!site!is!a!significant!change!
from! the! proposal! presented! in! the! superseded! SWMP! (AquaIntel,! 2014).! ! As! such!
the!MUSIC!model!has!been!amended.!!
In!order!to!quantify!load!reductions!a!base!case!(unmitigated)!assuming!the!building!
has!the!green!roof!areas!is!compared!to!mitigated!scenarios!including!the!inclusion!
of!reuse!estimates!and!treatment!devices.!!
2.3.2 MUSIC!Setup!
An! assessment! of! stormwater! runoff! quality! from! the! proposed! development! site!
has! been! conducted! using! the! Cooperative! Research! Centre! for! Catchment!
Hydrology’s! (CRCCH)! Model! for! Urban! Stormwater! Improvement! Conceptualisation!
(MUSIC).! MUSIC! is! a! decision! support! tool,! used! to! plan! and! design! appropriate!
urban! stormwater! management! systems! at! the! conceptual! level.! ! MUSIC! Version!
6.1.0,!released!in!2015,!was!used!in!this!assessment.!
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!1/1/1973Z!31/12/1983!with!six!(6)!minute!rainfall!duration.!
The!“MUSIC!Modelling!Guidelines”!(Water!By!Design,!2010)!was!used!as!the!basis!for!
constructing! the! MUSIC! model.! ! The! default! parameters! of! the! MUSIC! model! were!
used!in!representing!the!treatment!nodes!(where!applicable).!!
Source! node! parameters! for! urban! residential! (roof,! road! and! ground! level)! and!
forest!from!the!“MUSIC!Modelling!Guidelines”!(Water!By!Design,!2010)!were!used!in!
the!MUSIC!model.!
The! following! scenario! was! modelled! in! order! to! assess! the! performance! of! the!
proposed!development!and!treatment!devices:!

    1. Green! Roof! –! the! inclusion! of! the! roofed! areas! as! forest! source! nodes,! no!
       reuse!and!no!additional!treatment;!and!
    2. Mitigated! –! the! inclusion! of! the! green! roof! and! additional! water! quality!
       treatment! devices,! namely! a! bioretention! garden,! gross! pollutant! trap! and!
       storm!water!tank.!

The!fraction!impervious!value!applied!for!each!of!the!source!nodes!in!the!scenarios!
outlined!above!are!detailed!in!Table!2.!
Table!2:!Impervious!Percentage!

         Source!Node!                               Green!Roof!      Mitigated!
         Driveway!                                    100%!             100%!
         Deck!areas!(excluding!pool!
                                                      100%!             100%!
         surface)!
         Roof!                                         0%!               0%!
         Garden/lawn!                                  0%!               0%!




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