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Attachment C - Stormwater Management Plan - 30-32 Doonella Street_SMP-revA_full (00016826)
Attached to the e-mail MCU15/0053 Plans & Applicant's Response to Information Request.
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3.4 Mitigated!Scenario!
When!comparing!the!peak!flows!in!the!existing!and!developed!scenario,!increases!in!
the!peak!discharge!occur!at!the!catchment!outlet.!!As!a!result!a!detention!system!will!
be! required! to! be! implemented! in! order! to! demonstrate! non"worsening! from! the!
site.!!!
All! modeling! parameters! remain! consistent! between! the! developed! and! mitigated!
scenarios,! with! the! addition! of! a! detention! tank! at! the! site! outlet.! ! The! storage!
details!included!within!the!model!are!provided!in!Table!13.!
Table!13:!!Storage!and!Outlet!Details!of!Underground!Detention!System!
Storage!
Storage!Height!! Outlet!Configuration! Peak!100yr!WSL!!
Volume!!
20m3! 1.0m! 300mm!pipe! RL1.0m!
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A! comparison! of! the! peak! flows! between! the! existing,! developed! and! mitigated!
scenarios! are! presented! below! in! Table! 14.! ! It! can! be! seen! that! non"worsening! of!
peak!flows!are!achieved!at!each!outlet!to!the!site.!!
Table!14:!!Comparison!of!Existing,!Developed!and!Mitigated!WBNM!Outlet!Peak!Flows!
Existing!Peak! Developed!Peak! Mitigated!Peak! Change!in!Peak!
! Flow!(m3/s)! Flow!(m3/s)! Flow!(m3/s)! Flow!(m3/s)!
1!year! 0.08! 0.08! 0.07! "0.003!
2!year! 0.10! 0.10! 0.09! "0.004!
5!year! 0.12! 0.13! 0.12! "0.007!
10!year! 0.14! 0.14! 0.13! "0.008!
20!year! 0.16! 0.16! 0.14! "0.011!
50!year! 0.16! 0.18! 0.16! "0.002!
100!year! 0.18! 0.19! 0.18! "0.004!
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WBNM!outputs!are!provided!in!Appendix!2!of!this!report.!
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