Original source · versioned page text
Apdx 4 - SWMP
ingeniir STORMWATER MANAGEMENT PLAN 221304-SMP-01 Proposed Duplex 23 Coral Tree Avenue Noosa Heads 4567 Lot 17 on RP90014 Ingeniir Pty Ltd MAY 22 Authored by: Daniel Kenna for and on behalf of Ingeniir Pty Ltd. Ingeniir Pty Ltd | 221304-SMP-01 ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187 Page 1 | 11
See the original
The page text is free to read. Viewing or downloading an original file needs an account.
Log in to see the originalFull text of the other 13 pages
Page 2
ingeniir
DOCUMENT INFORMATION
Document Reference Date Author Reviewed Review Date
221304-SMP-01 5/24/2022 Daniel Kenna Daniel Kenna 24/05/2022
© Ingeniir Pty Ltd (2022) All Rights Reserved. Copyright in the whole and every part of this document belongs
to Ingeniir Pty Ltd and may not be used, sold, transferred, copied or reproduced in whole or in part in any
manner or form or in or on any media to any person without the prior written consent of Ingeniir Pty Ltd.
DOCUMENT DETAILS & CERTIFICATION
Report Title Stormwater Management Plan
Document Reference 221304-SMP-01
Street Address 23 Coral Tree Avenue, Noosa Heads
Legal Description Lot 17 on RP90014
Prepared for Kumar Mahadevan
Revision 01
Date 19/05/2022
Prepared By Daniel Kenna
For and on behalf of Ingeniir Pty Ltd
Certified By Daniel Kenna
Qualifications RPEQ 15522
For and on behalf of Ingeniir Pty Ltd
Signed
Date 24/05/2022
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 2 | 11
Page 3
ingeniir
EXECUTIVE SUMMARY
Ingeniir Pty Ltd (Ingeniir) have been engaged by Kumar Mahadevan to produce this Stormwater Management
Plan (SMP) in support of the Material Change of Use application for the Proposed Duplex at 23 Coral Tree
Avenue Noosa Heads 4567, Lot 17 on RP90014.
This report is comprised of stormwater quantity and quality assessments. The quantity assessment is
undertaken to confirm a ‘non-worsening’ discharge of peak flow from the developed site. The quality
assessment is undertaken to determine the required stormwater treatment measures to be implemented on
site to comply with Local and State Authority requirements.
Stormwater Quantity Calculations consider storm events up to and including the 1% AEP storm event. The
purpose is to ensure that the existing infrastructure and/or downstream properties are not adversely
affected by the proposed development.
The stormwater quantity assessment determined that a negligible increase estimated runoff rates will occur
due to the proposed development and the site will maintain kerb discharges in accordance with IPWEAQ
standards.
Currently no quality stormwater management measures are in place for the existing subject site. As the
proposed development area is less than 2500m2; there are no required operable stormwater quality
objectives required by State and Local Stormwater Quality Objectives.
All relevant standards and guidelines are addressed in this Stormwater Management Plan including;
criteria from the Noosa Shire Council Planning Scheme Policy, Queensland Urban Stormwater Quality
Planning Guidelines (2010), Queensland Urban Drainage Manual (QUDM) and the Australian Rainfall and
Runoff Guidelines.
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 3 | 11
Page 4
ingeniir
1. INTRODUCTION
Ingeniir Pty Ltd (Ingeniir) have been engaged by Kumar Mahadevan to produce this Stormwater Management
Plan in relation to the Proposed Duplex Development at 23 Coral Tree Avenue Noosa Heads 4567, Lot 17 on
RP90014.
There are no current approvals over the existing site.
2. EXISTING SITE CONDITIONS
The site is legally described as Lot 17 on RP90014, with an allotment area of 607m2. The site is located within
the Noosa Shire Council local government area.
Plate 1: Site Locality (Site highlighted Green)
The site currently has an existing residential dwelling and driveway on site. The site elevation ranges from
21.7m in the rear (West) to 19.06m at the front (East) of the allotment. Currently the roof-water discharges to
the kerb and overland flow discharges across the eastern and northern boundaries.
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 4 | 11
Page 5
ingeniir
The site currently receives surface water runoff from the majority of 28 Banksia Street to the East.
The lawful point of discharge for the site is the Coral Tree Avenue Road Reserve.
3. DESIGN OBJECTIVES
The objective of this report is to demonstrate that the project can comply with the Noosa Shire Council’s
codes and policies in relation to stormwater management through the implementation of the following
objectives;
• Maintain stormwater quality in accordance with local and state policies
• Manage and Mitigate quantities of peak stormwater discharge
• Adopt Water Sensitive Urban Design (WSUD) principles throughout
• Stormwater Harvesting and re-use for landscaping and alternative uses
• Provide immunity and resilience from flooding
This report outlines the design requirements to achieve the above objectives in a site-specific context.
4. STORMWATER STRATEGY
The site is situated between Coral Tree Avenue on the East and Banksia Avenue on the West. There is
stormwater infrastructure in Coral Tree Avenue/Jan Street approximately 20m North of the site as shown in
Plate 2; however the existing infrastructure is deemed unsuitable for direct connection for the following
reasons.
• The existing sewer line exiting the Northern side of the site is at a level where the stormwater would
clash or require site connection at an acute angle further limited by the power pole and existing
NBN/Telstra pit behind it.
• The site discharge for piped flows (5%AEP) is 38L/s which is generally considered below the threshold
to require direct network connection and would be considered a typical discharge rate for a
residential allotment.
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 5 | 11
Page 6
ingeniir
Plate 2: Infrastructure North of Site (Site highlighted Green)
It is achievable to maintain acceptable flows to Coral Tree Avenue from the site in accordance with IPWEAQ
standard drawing RS-081. It is noted that RS-081 applies to roof-water connections which implies that a 5%
AEP is the design event for the 25L/s per discharge location as per note 4.
The developed site in a 1% AEP event is expected to discharge a maximum of 55L/s (a pre-development
increase of 2L/s), and 38L/s in a 5% AEP with 2 proposed discharge points and will therefore comply with the
requirements of RS-081 without the need for on-site mitigation. Refer Appendix 2 | Rational Method
Calculations for pre and post development rational method calculations for the site.
5. STORMWATER QUALITY
5.1 Construction Phase
The State Planning Policy (DILGP, 2017) Appendix 2 – Stormwater management design objectives
Table A: Construction phase – stormwater management design objectives outlines construction phase
requirements for stormwater quality.
The following manuals (as a minimum) should be read and implemented by any contractor proceeding with
the development construction;
• State Planning Policy Appendix 2 Table A – available here
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 6 | 11
Page 7
ingeniir
• IECA Principles of Construction Site ESC – available here
• Water by Design ESC Factsheet Suite – available here
Detailed Erosion and Sediment Control design and plans should be documented by a suitably experienced
professional in conjunction with any application, or prior to commencing with the Building Works associated
with the proposed development on site.
5.2 Operational Phase
The site has a lot area of 607 and as such does not trigger local or state requirements for operational
treatment objectives for stormwater quality.
With reference to Table 9.3.3.3 of the Dual Occupancy and Multiple Dwelling Code & Table 9.4.8.3 of the
Water Quality and Drainage Code, there is no requirements for on-site re-use of rainwater or other
alternative arrangements on site.
6. STORMWATER QUANTITY
The Bureau of Meteorology 2016 IFD service has been used for all analysis in this report.
A Rational Method estimation of the stormwater discharge has been used to estimate the pre-developed and
developed runoff performance of the site.
RATIONAL METHOD SITE DISCHARGE SUMMARY
Pre-Development Post-Development
AEP Duration Duration Performance
Q (m3/s) Q (m3/s)
(min) (min)
63.20% 0.013 5 0.014 5 7.7%
39.35% 0.018 5 0.019 5 5.6%
18.14% 0.025 5 0.026 5 4.0%
10% 0.03 5 0.031 5 3.3%
5% 0.036 5 0.038 5 5.6%
2% 0.046 5 0.048 5 4.3%
1% 0.053 5 0.055 5 3.8%
Table 1: Comparison of pre and post development site discharges to Coral Tree Avenue
As demonstrated in Table 1, the proposed development does not produce a material worsening of flows and
is discharging to a controlled discharge point being Coral Tree Avenue so is deemed unable to cause a
downstream nuisance as the peak increase in discharge is a maximum of only 2L/s. It is considered that the
redirection of existing flows exiting the Northern boundary of the site directly to Coral Tree Avenue is a
beneficial outcome.
The site is also noted as receiving some flows from 28 Banksia Avenue to the West. The proposed
development is designed to convey these flows around the proposed building by providing a cut-off drain
behind the Western retaining wall that directs flows to the driveway to discharge through to Coral Tree
Avenue in a sheet flow manner.
Currently there is no discernable drainage path for the flows from 28 Banksia Avenue, so the provision of a
drainage path for these flows is considered an improvement to the current scenario. Appendix 2 | Rational
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 7 | 11
Page 8
ingeniir
Method Calculations provides estimates of the current and developed flows for both the development site
(23 Coral Tree Avenue) and the neighbouring site (28 Banksia Avenue), although the flows rates presented
are considered conservative as the soils in this area are known to have infiltration rates of 125mm/hour or
better.
7. FLOODING
The site is in an elevated position locally and regionally and is not known to have any flood risk. A review of
the Noosa Shire Council’s Intramaps (accessed 19/05/2022) indicates that the site is not affected by any
known flood or storm tide studies. Refer Plate 3 for an excerpt of the Council mapping.
Plate 3: Noosa Shire Council Flood Hazard Area/Defined Flood Extent in the vicinity of the site (Site highlighted)
8. CONCLUSION
The proposed development has been analysed to provide design requirements to meet local and state
authority guidelines for stormwater quality and quantity outcomes.
The proposed development can achieve the required design outcomes of the IPWEAQ by limiting site
discharge to Coral Tree Avenue to less than 50L/s during a 5% AEP Event and effectively maintaining site
stormwater discharge rates for all events up to and including the 1% AEP.
If you wish to discuss this report and analysis further, please contact Daniel Kenna.
Yours sincerely,
Daniel Kenna
Beng CPEng MIEAust RPEQ 15522 NER 3133685 EC 66121
for and on behalf of Ingeniir Pty Ltd
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 8 | 11
Page 9
ingeniir
9. LIMITATIONS
This report has been written based on Ingeniir’s understanding of the required scope at the time of writing;
and is written for the purposes of Kumar Mahadevan and not to be used for any other purpose.
To the extent permitted by law, Ingeniir expressly disclaims and excludes liability for any loss, damage, cost or
expenses suffered by any third party relating to or resulting from the use of, or reliance on, any information
contained in this report. Ingeniir does not admit that any action, liability or claim exist or be available to any
third-party, and disclaims any liability resulting from the inaccuracy of third-party information supplied to
Ingeniir for use in this report.
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 9 | 11
Page 10
ingeniir
Appendix 1 | BoM IFD Data
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 10 | 11
Page 11
Copyright Commonwealth of Australia 2016 Bureau of Meteorology (ABN 92 637 533 532)
All Design Rainfall Depth (mm)
Issued: 18-May-22
Location Label:
Requested coordinate:
Latitude -26.39523 Longitude 153.0877
Nearest gridLatitude
cell: 26.3875 (S) Longitude 153.0875 (E)
ExceedancesAnnual
per Year
Exceedance
(EY) Probability (AEP)
Duration Duration in min 12EY 6EY 4EY 3EY 2EY 63.20% 50% 0.5EY 20% 0.2EY 10% 5% 2% 1% 1 in 200 1 in 500 1 in 1000 1 in 2000
1 min 1 1.35 1.53 1.83 2.04 2.34 2.86 3.24 3.59 4.37 4.46 5.12 5.82 6.73 7.4 8.25 9.57 10.6 11.7
2 min 2 2.35 2.63 3.11 3.46 3.97 4.87 5.53 6.13 7.62 7.77 9.05 10.5 12.4 13.9 15.8 18.5 20.8 23.2
3 min 3 3.27 3.67 4.37 4.88 5.6 6.86 7.79 8.64 10.7 10.9 12.7 14.6 17.2 19.2 21.6 25.3 28.3 31.5
4 min 4 4.09 4.62 5.53 6.18 7.11 8.71 9.87 11 13.5 13.8 15.9 18.2 21.3 23.7 26.6 31 34.5 38.3
5 min 5 4.83 5.47 6.58 7.37 8.48 10.4 11.8 13.1 16 16.3 18.8 21.5 25 27.6 30.9 35.9 39.9 44.2
10 min 10 7.55 8.66 10.6 11.9 13.8 17 19.2 21.3 25.8 26.3 30.1 34.1 39.2 42.9 47.7 55.2 61.1 67.3
15 min 15 9.36 10.8 13.3 15 17.5 21.6 24.4 27.1 32.8 33.4 38.2 43.3 49.7 54.4 60.5 69.9 77.4 85.2
20 min 20 10.7 12.4 15.3 17.3 20.2 25.2 28.4 31.5 38.2 39 44.6 50.6 58.2 63.8 71 82.2 91.1 100
25 min 25 11.8 13.6 16.9 19.2 22.4 28.1 31.7 35.2 42.7 43.6 49.9 56.7 65.4 71.9 80.2 93 103 114
30 min 30 12.6 14.6 18.2 20.7 24.3 30.5 34.5 38.3 46.6 47.5 54.5 62.1 71.9 79.1 88.4 103 114 126
45 min 45 14.6 16.9 21.1 24.1 28.5 36.2 41 45.5 55.9 57 65.9 75.4 88 97.5 109 127 141 156
1 hour 60 16 18.6 23.3 26.7 31.6 40.6 46.1 51.1 63.3 64.5 74.9 86.2 101 113 126 147 163 181
1.5 hour 90 18.1 21.1 26.5 30.5 36.4 47.3 53.9 59.9 75 76.5 89.4 104 123 137 154 179 199 220
2 hour 120 19.7 23 29 33.5 40.2 52.6 60.2 66.9 84.5 86.1 101 118 140 158 177 205 228 252
3 hour 180 22.3 26 33 38.3 46.2 61.2 70.4 78.2 100 102 121 141 170 192 214 248 275 303
4.5 hour 270 25.3 29.6 37.7 43.9 53.4 71.5 82.6 91.7 119 121 144 170 205 233 258 298 330 363
6 hour 360 27.8 32.6 41.7 48.7 59.3 79.9 92.7 103 134 137 164 194 234 267 295 340 376 412
9 hour 540 31.9 37.6 48.2 56.5 69.1 93.8 109 121 160 163 196 233 283 322 356 410 451 495
12 hour 720 35.4 41.8 53.7 62.9 77.1 105 123 136 181 184 222 264 322 368 407 468 516 565
18 hour 1080 41.1 48.5 62.4 73.3 89.9 123 144 160 213 218 263 315 385 442 490 566 625 687
24 hour 1440 45.7 54 69.4 81.4 100 137 160 178 239 243 296 354 436 501 559 648 719 793
30 hour 1800 49.6 58.4 75.2 88.1 108 148 173 193 259 264 321 386 477 550 626 735 823 917
36 hour 2160 52.8 62.2 80 93.8 115 157 184 205 276 281 343 413 512 592 682 807 909 1020
48 hour 2880 58 68.3 87.7 103 126 172 202 224 302 308 377 456 568 661 768 917 1040 1180
72 hour 4320 65 76.6 98.3 115 141 192 225 250 338 345 424 515 647 757 880 1060 1210 1370
96 hour 5760 69.1 81.6 105 123 151 206 241 268 362 369 454 553 698 819 950 1140 1310 1490
120 hour 7200 71.4 84.8 110 129 159 216 253 281 379 386 475 579 732 859 995 1200 1370 1560
144 hour 8640 72.5 86.7 113 133 164 225 262 291 392 400 492 599 755 886 1030 1230 1410 1600
168 hour 10080 72.8 87.8 116 137 169 232 270 300 403 411 505 614 771 901 1050 1260 1440 1630
[OCR of page images]
O€9T
009T
O9sT
O6tT
OLET
O8TT
OzoT
LT6
€6L
£89
s9S
s6v
ey
€9€
€0€
7sz
0@z
T8T
9ST
9eT
vIt
OOT
7S8
elo
cu
Ese
STE
TEr
“LTT
0007 UIT = OOOT UIT
OvbT
OTT
OLET
OTET
Oter
OvoT
606
€78
6TL
S79
9TS
1st
OLE
O€€
slz@
82
66T
€9T
TvT
vit
€0T
TT6
vLl
TT9
66E
SVE
€87
807
90T
o9zT
O€cT
oozT
OvIT
O90T
L16
£08
SEL
89
99S
897
otv
Ove
862
8b
soz
6<T
LvT
Let
€0T
€6
ces
669
ess
SE
TE
€Sz
S8T
LS°6
00s UIT
OsOT 106
O€0T 988
S66 6S8
os6 6T8
088 “SL
89L 199
789 76S
979 oss
6SS TOS
067 chy
Lov 89€
9SE ee
S62 197
8Sz €€7
viz ?6T
LLT 8st
vst LET
9eT ett
60T oL6
vss Té6L
708 6TL
TL seo
s09 ves
Lly ocy
6 0E 9Le
997 LET
91% C6T
SST eT
Svs vl
00Z UT %T
TLL
SSZ
cel
869
Lv9
89S
ets
LLv
9€v
S8€
ee
€87
VEC
s0z
OLT
OvT
€?L
TOT
88
6TL
vs9
78s
Lev
C6E
sz
ET?
CLT
ver
€L9
%e
v19
66S
62S
€ss
STS
9sv
ely
98€
vSE
STE
v9
€€7
v6T
OLT
Tet
STT
vot
798
vse
Tre
“£g9s
90S
eer
Tve
STZ
78ST
OvT
SOT
78s
%S
SOS
én
slv
vsy
ver
LLE
eve
TE
962
€97
te
96T
v9T
vt
Tet
TOT
v68
ove
6s9
sus
66y
ovb
78E
TOE
SST
6ST
Ler
S06
ers
%OT
Tlv
oor
98€
69€
SvE
80€
182
v9
eve
8Tz
v8t
€9T
LET
Te
cot
T98
GOL
sv9
Zs
oly
oeb
6€
vee
€97
€9T
SET
60T
LLL
oD
€0v
76E
6LE
COE
BEE
OE
9L7
657
6€7z
€Tz
T8T
Oot
vET
6TT
Oot
Svs
SL
ee9
ess
990
Ley
T8E
S7E
8'Sz
oT
Set
LOT
eoL
Lev
AITO KOZ
OO0€
T6z
187
897
ose
vez
soz
€6T
8ZT
Oot
9ET
Tet
€0T
LT6
ese
699
66S
TTS
sSt
Ese
cSE
STE
Le
eT?
TEL
IT
98
ergo
6S'E
022
79¢
€s7
Tee
St
coz
v8T
€LT
Oot
vet
€?L
60T
Lee
978
vod
709
ees
Tov
Tv
SVE
LTE
vst
ve
C6T
STT
£86
642
ess
vee
AaS‘0 %OS
cEz 69T LET OTT 828 sel O800T ANOY BOT
St v9T €€T eI £98 sel 098 ANOY byT
9T@ 6ST 6¢T OTT ss vIL o0zZ ANY OZT
902 TST €eT SOT 9T8 169 092s ANY 96
76T Tet STT £86 99L $9 Ozer anoy @L
CLT 9eT €0T L£L8 €389 8S 0882 ANOY By
LST STT SEs 08 ecg 8cs Osta ANoY 9E
8vT 80T 188 asl v8s 960 o08T ANoY OE
LET Oot vts v69 vs “sb OvbT ANOY HZ
€?T 668 eel veg s8y TTY o8s0T ANOY 8T
SOT TLL 679 Les ST VSE o7zZ ANOY ZT
see T69 g9S c8b OLE 6TE ovs ANOY 6
662 €6s L380 Liv 9CE Ble O9€ anoy 9
STL ves 6ey LLe 967 est 0£7 Anoy S'7
719 coy ese €€ 9% ete O8T ANY €
ges cov Gee 62 €% Ler ozT ANY Z
ely v9E SOE s9z TTe T8T 06 Anoy S°T
90b OTE £97 fet 98T oT 09 Anoy T
T9E s87z Tee TIZ 69oT OT sv ull Si
SOE eve L0t 78ST OT 9?T 0€ ull O€
T8z aaa C6T 69T eT STT sz UI GZ
cst 707 elt est ver LOT oz ull OZ
91? SLT ST eer SOT 9E6 ST ull ST
dt SET 6TT 9°0T 99'°8 sol oT ulW OT
vot srs LEeL 8s9 Lvs €sy S UI S
1L8 TTL 8t9 ess wy 607 v ull 7
98'°9 9S sey Lev LOE LOE € ul €
L830 LOE ove ITE €97 SE7 z ul Z
987 vET v0? €8T est SET T ul T
%07°E9 Aqz AqE Aav Aaa Aa?T ulwuluoneing uoneing
(dav) Aujigeqoig aduepaaaxg jenuuy iaduepaaxy
(3) SZ80"eST @pnysu07 (s) szgE"9z
LL80'EST apny!Bu0] €7S6E'97-
apnyye7 us IsaseaN
apnyyje7 pajsanbay
jaqe] uol}e307
77-ACW-8T :panss|
(ww) yrdag jreyuey usisag |IV
(Z€S €€S LED 76 NAY) ABojosoajay| Jo neaing 9TOZ ele4Isny Jo YJeaMUoWWOD IYBLLAdOD
Page 12
ingeniir
Appendix 2 | Rational Method Calculations
Ingeniir Pty Ltd | 221304-SMP-01
ABN: 99 642 485 363 | PO Box 988 Maroochydore QLD 4558 | [email protected] | 0404157187
Page 11 | 11
Page 13
Rational Method Calculations
Project 221304
Address 23 Coral Tree Avenue By DK
Pre - Development Post - Development
Catchment Details Catchment Details
Area 0.0607 ha Area 0.0607 ha
fi 0.43 fi 0.62
C10 0.78632619 C10 0.82355848
I10 74.9 mm/hr I10 74.9 mm/hr
Standard Inlet Time Standard Inlet Time
Time 5 mins Time 5 mins
Overland Sheet Flow (Friend's Eqn) Overland Sheet Flow (Friend's Eqn)
Length m Length m
Slope % Slope %
Surface 'n' Surface 'n'
Time 0 mins Time 0 mins
Pipe Flow Travel Time Pipe Flow Travel Time
Flow Distance m Flow Distance m
Fall of Channel m Fall of Channel m
Time mins Time mins
Kerb Flow Kerb Flow
Length m Length m
Slope % Slope %
Time 0.0 mins Time 0.0 mins
Channel Flow (Figure 4.8 QUDM, or Channel Flow (Figure 4.8 QUDM, or
Manning's Equation) Manning's Equation)
Flow Distance m Flow Distance m
Fall of Channel m Fall of Channel m
Time mins Time mins
Adopted Time of Adopted Time of
Concentration
5 mins Concentration
5 mins
Pre-Development Peak Discharges Post-Development Peak Discharges
Design Storm Frequency
Area (ha) Cy Iy (mm/h) Qy (m3/s) (AEP) Factor (Fy)
Area (ha) Cy Iy (mm/h) Qy (m3/s)
0.0607 0.62906096 125 0.013 63.20% 0.80 0.0607 0.65884679 125 0.014
0.0607 0.66837727 157 0.018 39.35% 0.85 0.0607 0.70002471 157 0.019
0.0607 0.74700988 196 0.025 18.14% 0.95 0.0607 0.78238056 196 0.026
0.0607 0.78632619 226 0.03 10% 1.00 0.0607 0.82355848 226 0.031
0.0607 0.8256425 258 0.036 5% 1.05 0.0607 0.86473641 258 0.038
0.0607 0.90427512 300 0.046 2% 1.15 0.0607 0.94709226 300 0.048
0.0607 0.94359143 331 0.053 1% 1.20 0.0607 0.98827018 331 0.055
Discharge Comparison
AEP 63.20% 39.35% 18.14% 10% 5% 2% 1%
Difference 0.001 0.001 0.001 0.001 0.002 0.002 0.002
Percentage 7.7% 5.6% 4.0% 3.3% 5.6% 4.3% 3.8%
Page 14
Rational Method Calculations
Project 221304
Address 28 Banksia Avenue By DK
Pre - Development Post - Development
Catchment Details Catchment Details
Area 0.0647 ha Area 0.0647 ha
fi 0.00 fi 0.75
C10 0.7 C10 0.85
I10 74.9 mm/hr I10 74.9 mm/hr
Standard Inlet Time Standard Inlet Time
Time 5 mins Time 5 mins
Overland Sheet Flow (Friend's Eqn) Overland Sheet Flow (Friend's Eqn)
Length m Length m
Slope % Slope %
Surface 'n' Surface 'n'
Time 0 mins Time 0 mins
Pipe Flow Travel Time Pipe Flow Travel Time
Flow Distance m Flow Distance m
Fall of Channel m Fall of Channel m
Time mins Time mins
Kerb Flow Kerb Flow
Length m Length m
Slope % Slope %
Time 0.0 mins Time 0.0 mins
Channel Flow (Figure 4.8 QUDM, or Channel Flow (Figure 4.8 QUDM, or
Manning's Equation) Manning's Equation)
Flow Distance m Flow Distance m
Fall of Channel m Fall of Channel m
Time mins Time mins
Adopted Time of Adopted Time of
Concentration
5 mins Concentration
5 mins
Pre-Development Peak Discharges Post-Development Peak Discharges
Design Storm Frequency
Area (ha) Cy Iy (mm/h) Qy (m3/s) (AEP) Factor (Fy)
Area (ha) Cy Iy (mm/h) Qy (m3/s)
0.0647 0.56 125 0.013 63.20% 0.80 0.0647 0.68 125 0.015
0.0647 0.595 157 0.017 39.35% 0.85 0.0647 0.7225 157 0.02
0.0647 0.665 196 0.023 18.14% 0.95 0.0647 0.8075 196 0.028
0.0647 0.7 226 0.028 10% 1.00 0.0647 0.85 226 0.034
0.0647 0.735 258 0.034 5% 1.05 0.0647 0.8925 258 0.041
0.0647 0.805 300 0.043 2% 1.15 0.0647 0.9775 300 0.053
0.0647 0.84 331 0.05 1% 1.20 0.0647 1 331 0.06
Discharge Comparison
AEP 63.20% 39.35% 18.14% 10% 5% 2% 1%
Difference 0.002 0.003 0.005 0.006 0.007 0.01 0.01
Percentage 15.4% 17.6% 21.7% 21.4% 20.6% 23.3% 20.0%