OPW16/0021- Operational Works Application 2 of 4

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2.3.3 Catchment!Areas!
During! detailed! design! phases! and! as! a! result! of! the! FLOTH! hydraulic! design! (see!
Appendix! 1)! the! developed! areas! of! the! site! will! all! be! directed! to! a! single! outlet.!!
This!is!a!significant!change!to!the!previous!SWMP!(AquaIntel,!2014).!!!
For!the!purposes!of!water!quality!modelling!the!development!site!has!been!split!into!
catchments! that! report! to! the! various! water! quality! treatment! devices.! Each!
catchment! is! then! divided! into! roofed,! paved,! road! and! grassed! areas.! ! Significant!
areas!of!the!site!remain!undeveloped!and!have!been!included!in!the!MUSIC!model!as!
forested,! however,! results! are! reported! upstream! of! these! areas.! Table! 3! outlines!
the!catchment!areas!represented!within!the!MUSIC!model.!The!stormwater!quality!
catchments!are!provided!in!Figure!5.!External!catchments!have!not!been!modelled,!
as!they!do!not!contribute!to!the!water!quality!improvement!devices.!
Table!3:!Catchment!Areas!
                            Drive!       Roof!         Deck!    Grassed!      Forest!
                                                                              Total!
      Catchment!
                            (ha)!        (ha)!         (ha)!      (ha)!        (ha)#!
                                                                              (ha)!
External!                     !      !         !          !                   0.286!
                                                                             0.286!
D1c!                       !         !         !          !                   0.155!
                                                                             0.155!
D1a_Driveway!           0.026!       !         !          !          !       0.026!
OPW_Green_Roof!            !      0.067!       !          !          !       0.067!
OPW_Lower_A!               !         !         !       0.024!        !       0.024!
OPW_Lower_B!               !         !     0.02736! 0.02964!         !       0.057!
OPW_Roof!                  !      0.022!       !          !          !       0.022!
D2b!                       !         !         !          !       0.221!     0.221!
C3!                        !         !         !          !       0.317!     0.317!
!                          !         !         !          !       0.286!     0.286!
#!Forest!sources!nodes!for!the!undeveloped!portion!of!the!site!have!been!included!in!
the!MUSIC!model!however!results!are!reported!at!the!outlet!of!the!developed!areas.!!

2.3.4 MUSIC!Model!Layout!
As! the! management! of! urban! stormwater! needs! to! take! a! holistic! approach,! a!
number! of! management! measures! need! to! be! implemented! in! series! to! form! a!
treatment!train.!The!correct!utilisation!of!various!devices!within!the!treatment!train!
is! imperative! to! target! the! desired! pollutants,! from! the! gross! solids! to! the! fine!
particles.!!Figure! 4!shows!the!MUSIC!model!layout!for!the!development!(Mitigated!
Scenario).!
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