OPW16/0021- Operational Works Application 2 of 4

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Executive!Summary!
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AquaIntel! has! been! commissioned! by! TOD! Consulting! Engineers! on! behalf! of! Universal!
Property! Company! Establishment! to! prepare! a! Stormwater! Management! Plan! (SWMP)! to!
support! the! Operational! Works! Approval! for! the! residential! development! at! 71! Seaview!
Terrace,! Sunshine! Beach! (Lot! 1! RP197117).! ! This! document! supersedes! the! stormwater!
management! plan! prepared! by! AquaIntel! (2014)! in! support! of! the! Material! Change! of! Use!
application.!
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The!site!is!currently!undeveloped!and!well!vegetated.!!The!site!is!located!adjacent!to!Noosa!
national!Park.!There!is!a!small!external!catchment!draining!through!the!site!from!the!west.!!
The! site! grades! from! the! west! to! the! east! and! currently! runoff! from! the! site! collects! in! a!
drainage!line!near!the!eastern!boundary!of!the!site!and!discharges!to!the!beach.!!!
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It!is!proposed!that!the!residence!be!constructed!with!a!living!‘green’!roof!consisting!of!up!to!
200!mm!of!soil!media!sustaining!planted!material!covering!the!shell!like!structure.!!The!roof!
will!drain!via!an!under!drainage!network!and!a!series!of!intercept!drains!to!the!edges!of!the!
roof.!!
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Internal! hydraulic! design,! estimation! of! reuse! and! sizing! of! reuse! infrastructure! has! been!
completed!by!FLOTH.!The!scope!of!this!investigation!is!to!provide!stormwater!treatment!and!
control! measures! to! meet! development! conditions! for! the! site! and! based! on! the! hydraulic!
design! by! FLOTH.! ! This! investigation! does! not! include! hydraulic! modelling! of! the! internal!
pipework!and!drainage!system!proposed!by!FLOTH!and!only!comprises!hydrologic!modelling!
from!the!outlet!of!the!proposed!stormwater!reuse!tanks!to!the!site!outlets!for!the!purpose!of!
determining! estimates! of! peak! flows! form! the! site.! ! Components! of! the! FLOTH! design! that!
will!act!as!water!quality!improvement!devices!such!as!a!GPT!and!the!stormwater!reuse!tanks!
have!been!included!in!water!quality!modelling!as!per!the!specified!design.!
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Environmental! best! management! practices! are! proposed! for! treatment! of! stormwater!
generated!by!the!site.!Stormwater!will!be!treated!using!a!number!of!treatment!devices!prior!
to!discharge!to!the!receiving!environment.!The!stormwater!treatment!train!for!the!site!will!
include!collection!of!runoff!from!roofed!and!paved!areas!to!a!GPT!and!stormwater!harvesting!
system! then! through! a! bioretention! garden! prior! to! discharge! into! the! existing! forested!
areas.!!
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Non[worsening!of!peak!flows!from!the!site!has!been!demonstrated!through!the!incorporation!
of!a!stormwater!reuse!tank!(designed!by!others)!and!detention!basin,!which!incorporates!the!
bioretention! basin.! ! Runoff! from! the! external! catchment! to! the! west! of! the! site! will! be!
managed!by!diverting!the!existing!drainage!paths!along!the!western!boundary!and!allowing!
flow!to!continue!through!the!area!of!the!site!which!will!not!be!developed.!!Overflows!from!
the! stormwater! reuse! tank! will! be! directed! into! a! detention! basin! and! then! onto! natural!
ground! below! the! proposed! development! so! that! one! point! of! discharge! is! maintained.!!
Development!conditions!are!addressed!by!providing!a!piped!outlet!form!the!basin!to!below!
RL26!and!a!spreader!at!this!location!to!minimize!the!risk!associated!with!flow!concentration!
from!the!outlet.!
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This!Stormwater!Management!Plan!demonstrates!that!effective!treatment!of!stormwater!at!
the!proposed!development!can!be!achieved!through!the!application!and!appropriate!design!



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