main drain calculation
DESCRIPTION
main drain calculationTRANSCRIPT
![Page 1: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/1.jpg)
References : Urban Stormwater management manual
Table of Average Rainfall Intensity (mm/hr)
for Kuala Lumpur referred to table 13.A1
For Rainfall Duration > 30 minutes
referred to equation 13.2
Storm Duration , tc (mins)
ARI (year) 15 18 20 22 24 26 28 30 32 33 37 38 40 42 44 46 48 50 52 54 56 58 60
2 139.5 128.6 122.3 116.7 111.6 107.0 102.9 99.0 95.5 93.8 87.8 86.4 83.8 81.4 79.1 76.9 74.9 73.0 71.2 69.5 67.8 66.3 64.8
5 166.5 153.6 146.2 139.4 133.3 127.7 122.6 117.9 113.5 111.5 104.1 102.4 99.1 96.1 93.3 90.6 88.1 85.8 83.5 81.4 79.4 77.5 75.7
10 182.5 169.0 161.1 153.8 147.1 141.1 135.5 130.4 125.6 123.4 115.2 113.3 109.7 106.4 103.3 100.4 97.6 95.0 92.5 90.2 88.0 85.9 83.9
20 199.8 185.0 176.2 168.2 160.9 154.2 148.1 142.4 137.2 134.7 125.7 123.7 119.8 116.1 112.7 109.4 106.4 103.5 100.8 98.3 95.8 93.5 91.3
50 217.3 202.1 192.9 184.4 176.6 169.4 162.8 156.6 151.0 148.3 138.4 136.2 131.9 127.8 124.1 120.5 117.2 114.0 111.0 108.2 105.5 103.0 100.5
100 240.5 223.2 212.8 203.3 194.5 186.5 179.1 172.2 165.9 162.9 152.0 149.5 144.8 140.3 136.1 132.2 128.5 125.0 121.7 118.6 115.7 112.9 110.2
For Short Rainfall Duration < 30 minutes
referred to equation 13.3, 13.4 and table 13.3
value of 2
P24h= 100 (KUALA LUMPUR).
Storm Duration , tc (mins)
ARI (year) 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
2 212.5 201.5 193.7 187.8 183.3 179.6 171.3 164.4 158.5 153.5 149.1 143.6 138.7 134.4 130.5 127.0 123.0 119.4 116.0 113.0 110.2 107.6 105.2 103.0 101.0 99.0
5 288.1 266.9 251.8 240.5 231.7 224.6 213.0 203.3 195.1 188.1 182.0 174.8 168.4 162.7 157.7 153.1 148.1 143.5 139.3 135.5 132.0 128.7 125.7 122.9 120.3 117.9
10 315.3 292.7 276.5 264.4 255.0 247.4 234.7 224.1 215.2 207.5 200.9 192.9 185.9 179.7 174.2 169.2 163.6 158.6 154.0 149.8 145.9 142.3 139.0 135.9 133.0 130.4
20 352.4 325.8 306.9 292.7 281.6 272.8 258.5 246.6 236.6 228.0 220.5 211.7 203.9 197.0 190.8 185.3 179.2 173.6 168.5 163.9 159.6 155.6 152.0 148.6 145.4 142.4
50 385.3 356.6 336.1 320.8 308.8 299.3 283.7 270.7 259.8 250.3 242.2 232.5 224.0 216.5 209.7 203.6 196.9 190.8 185.2 180.1 175.4 171.1 167.1 163.4 159.9 156.6
100 432.3 398.8 374.9 356.9 342.9 331.8 314.2 299.6 287.2 276.6 267.4 256.7 247.2 238.7 231.2 224.4 217.0 210.2 204.0 198.3 193.1 188.3 183.8 179.7 175.8 172.2
![Page 2: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/2.jpg)
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : 00109 / Meseba YauTY
page Main Drain capacity Ogos 02
of main drain A1 REF.
Main Drain A1 - Computation of Section Capacity
drainage reserve = 3.0 m 0.6 m PC Block Drain
alow freeboard = 0.3 m area,Ap = 0.2541 m
perimeter, Pp = 1.45 m
drain gradient , S =1/ 200
Bottom section n = 0.015 stone pitching
Side wall slope: 1/sw1= 0.50 drain
drain depth, D1 = 1.30 m
drain width, W = 1.2 m
Side slope width : Ws1 = 0.65 m
wetted Area, A1 = 2.66 m2
wetted perineter, P1 = 4.96 m
R1 = 0.54 m
drain cpacity, Q = 8.28 m3/s > required discharge,
velocity, V = 3.11 m/s < 4.0 m/s
2 yeasr storm top water lever, TWL2 = 0.84 m
5 yeasr storm top water lever, TWL5 = 1.00 m
100 years storm top water lever, TWL100 = 1.28 m
thus provide PC Block drain section with minimum
wall height = 1.5m
JURUTERA PERUNDING TEGAP SDN. BHD.
Designed :
Date :
Checked :
CALCULATION OUTPUT
drainage reserve
PC Block Drain
W
d
0.6
D
Sw1
1
0.3m FB
Ws1
![Page 3: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/3.jpg)
PROJECT : 00109 / Meseba YauTY
page Main Drain Capacity Ogos 02
of main drain A2REF.
Pudu Cut Drain
drainage reserve = 5.0 m area,Ap = 0.16 m
alow freeboard = 0.3 m perimeter, Pp = 1.17 m
drain gradient , S =1/ 300
n = 0.015 stone pitching
Bottom section drain
Side wall slope: 1/sw1= 0.5
drain depth, D1 = 1.20 m
drain width, W = 1.65 m
Side slope width : Ws1 = 0.60 m
wetted Area, A1 = 3.87 m2
wetted perineter, P1 = 5.34 m
R1 = 0.72 m
drain cpacity, Q = 12.01 m3/s > required discharge, drain section is
velocity, V = 3.10 m/s sufficient
2 yeasr storm top water lever, TWL2 = 0.39 m
5 yeasr storm top water lever, TWL5 = 0.58 m
100 years storm top water lever, TWL100 = 0.94 m
thus provide Pudu cut drain section with minimum
wall height = 1.5m
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : 00109 / Meseba YauTY
CALCULATION OUTPUT
Designed :
Date :
Checked :
Designed :
drainage reserve
pudu cut section W
d
1.05
D
Sw1
1
0.3m FB
Ws1
![Page 4: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/4.jpg)
page Main Drain Capacity Ogos 02
of main drain B1& B3REF.
Pudu Cut Drain
drainage reserve = 5.0 m area,Ap = 0.16 m
alow freeboard = 0.3 m perimeter, Pp = 1.17 m
drain gradient , S =1/ 500
n = 0.015 stone pitching
Bottom section drain
Side wall slope: 1/sw1= 0.5
drain depth, D1 = 1.70 m
drain width, W = 2.25 m
Side slope width : Ws1 = 0.85 m
wetted Area, A1 = 6.44 m2
wetted perineter, P1 = 7.06 m
R1 = 0.91 m
drain cpacity, Q = 18.06 m3/s > required discharge, drain section is
velocity, V = 2.80 m/s sufficient
2 yeasr storm top water lever, TWL2 = 0.53 m
5 yeasr storm top water lever, TWL5 = 0.70 m
100 years storm top water lever, TWL100 = 1.06 m
thus provide Pudu cut drain section with minimum
wall height = 2.0m
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : 00109 / Meseba YauTY
page Main Drain capacity Ogos 02
of main drain B2REF. CALCULATION OUTPUT
Designed :
Date :
Checked :
Date :
Checked :
CALCULATION OUTPUT
drainage reserve
pudu cut section W
d
1.05
D
Sw1
1
0.3m FB
Ws1
drainage reserve
pudu cut section W
d
1.05
D
Sw1
1
0.3m FB
Ws1
![Page 5: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/5.jpg)
Main Drain B2 - Computation of Section Capacity
drainage reserve = 3.0 m 0.6 m PC Block Drain
alow freeboard = 0.3 m area,Ap = 0.2541 m
perimeter, Pp = 1.45 m
drain gradient , S =1/ 200
Bottom section n = 0.015 stone pitching
Side wall slope: 1/sw1= 0.50 drain
drain depth, D1 = 0.40 m
drain width, W = 1.2 m
Side slope width : Ws1 = 0.20 m
wetted Area, A1 = 0.81 m2
wetted perineter, P1 = 2.94 m
R1 = 0.28 m
drain cpacity, Q = 1.63 m3/s > required discharge,
velocity, V = 2.00 m/s < 4.0 m/s
2 yeasr storm top water lever, TWL2 = 0.53 m
5 yeasr storm top water lever, TWL5 = 0.71 m
100 years storm top water lever, TWL100 = 1.00 m
drainage reserve
PC Block Drain
W
d
0.6
D
Sw1
1
0.3m FB
Ws1
![Page 6: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/6.jpg)
\\vboxsrv\conversion_tmp\scratch_3\[236585396.xls.ms_office.xls]box
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : Lot 1149 YauTY
page Catchment Flow Compuation Apr-06
of pre-development discharge computaion - Catchment A
REF.
1.0 Upstream Catchment Area
Upstream Catchment Area from catchment A = 14 ha
14 ha
1.1 Determine of time of concentration, tc
for density grassed surface (n=0.060)
average surface slopes =5%
Design overland flow distance = 200m
chart 14.1 to = 29 mins
average velocity in open drain , assumed v = 1 m/s
natural channel, Ld = 500 m
drain flow time, td = Ld / (v x 60) = 8 mins
thus, time of concentration, tc = to+ td = 37 mins
1.2 Determine rainfall intensity and Runoff Coefficient
Referred to Table of Average Rainfall Intensity (mm/hr) for short rainfall
duration for tc = 37 mins
thus,
rainfall intensity for 5 years storm5I 37 = 104.052 mm/hr
rainfall intensity for 10 years storm10I 37 = 115.178 mm/hr
rainfall intensity for 100 years storm100I 37 = 152.015 mm/hr
design chart Runoff Coefficient for Upstream catchment, C 5 = 0.35
14.4 between F C 10 = 0.42
between medium soil to sandy soil - forest C 100 = 0.51
1.3 Discharge flow computaion, Qpost , for pre-development
Q = (A1 x C1) x I
Discharge flow for 5 years storm Q 5,pre = 1.42 m
3/s
Discharge flow for 10 years storm Q 10,pre = 1.88 m
3/s
Discharge flow for 100 years storm Q 100,pre = 3.01 m
3/s
Designed :
Date :
Checked :
CALCULATION OUTPUT
![Page 7: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/7.jpg)
\\vboxsrv\conversion_tmp\scratch_3\[236585396.xls.ms_office.xls]box
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : Lot 1149 YauTY
page Catchment Flow Compuation Apr-06
of post-development discharge computaion - Catchment A
REF.
1.0 Meseba Development site Post Development Catchment Area
Upstream Catchment Area Forest = 28ac. 11.8 ha
Project Site ( developed area ) = 10 ac. 5.53 ha
1.1 Upstream Discharge, upQ
Discharge flow for 5 years storm Q 5,up = 1.19 m
3/s
Discharge flow for 10 years storm Q 10,up = 1.59 m
3/s
Discharge flow for 100 years storm Q 100,up = 2.54 m
3/s
1.1 Determine of time of concentration, tc
for paved surface (n=0.015)
average surface slopes =1%
Design overland flow distance = 200m
chart 14.1 to = 10 mins
average velocity in open drain , assumed v = 1 m/s
drain length, Ld = 200 m
drain flow time, td = Ld / (v x 60) = 3 mins
thus, time of concentration, tc = to+ td = 13 mins
1.2 Determine rainfall intensity and Runoff Coefficient
Referred to Table of Average Rainfall Intensity (mm/hr) for short rainfall
duration for tc = 15 mins
thus,
rainfall intensity for 5 years storm5I 13 = 195.10 mm/hr
rainfall intensity for 10 years storm10I 13 = 215.20 mm/hr
rainfall intensity for 100 years storm100I 13 = 287.20 mm/hr
design chart Runoff Coefficient for Upstream catchment, C 5 = 0.88
14.4 3 Semi-detached house on bare earth C 10 = 0.88
C 100 = 0.88
1.3 Discharge flow computaion, Qpre , for Post-development
Q = (A1 x C1) x I + upQ
Discharge flow for 5 years storm Q 5,post = 3.83 m
3/s
Discharge flow for 10 years storm Q 10,post = 4.49 m
3/s
Discharge flow for 100 years storm Q 100,post = 6.42 m
3/s
CALCULATION OUTPUT
Designed :
Date :
Checked :
![Page 8: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/8.jpg)
\\vboxsrv\conversion_tmp\scratch_3\[236585396.xls.ms_office.xls]box
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : Lot 1149 YauTY
page Catchment Flow Compuation Apr-06
of pre-development discharge computaion
REF.
1.0 Upstream Catchment Area
Upstream Catchment Area from catchment B = 22.1 ha
22.1 ha
1.1 Determine of time of concentration, tc
for density grassed surface (n=0.060)
average surface slopes =5%
Design overland flow distance = 200m
chart 14.1 to = 29 mins
average velocity in open drain , assumed v = 1 m/s
natural channel, Ld = 600 m
drain flow time, td = Ld / (v x 60) = 10 mins
thus, time of concentration, tc = to+ td = 39 mins
1.2 Determine rainfall intensity and Runoff Coefficient
Referred to Table of Average Rainfall Intensity (mm/hr) for short rainfall
duration for tc = 37 mins
thus,
rainfall intensity for 5 years storm5I 37 = 104.052 mm/hr
rainfall intensity for 10 years storm10I 37 = 115.178 mm/hr
rainfall intensity for 100 years storm100I 37 = 152.015 mm/hr
design chart Runoff Coefficient for Upstream catchment, C 5 = 0.35
14.4 between F C 10 = 0.42
between medium soil to sandy soil - forest C 100 = 0.51
1.3 Discharge flow computaion, Qpost , for pre-development
Q = (A1 x C1) x I
Discharge flow for 5 years storm Q 5,pre = 2.24 m
3/s
Discharge flow for 10 years storm Q 10,pre = 2.97 m
3/s
Discharge flow for 100 years storm Q 100,pre = 4.76 m
3/s
Designed :
Date :
Checked :
CALCULATION OUTPUT
![Page 9: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/9.jpg)
\\vboxsrv\conversion_tmp\scratch_3\[236585396.xls.ms_office.xls]box
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : Lot 1149 YauTY
page Catchment Flow Compuation Apr-06
of post-development discharge computaion - Catchment B
REF.
1.0 Meseba Development site Post Development Catchment Area
Upstream Catchment Area Forest = 28ac. 17.21 ha
Project Site ( developed area ) = 10 ac. 3.65 ha
1.1 Upstream Discharge, upQ
Discharge flow for 5 years storm Q 5,up = 1.74 m
3/s
Discharge flow for 10 years storm Q 10,up = 2.31 m
3/s
Discharge flow for 100 years storm Q 100,up = 3.71 m
3/s
1.1 Determine of time of concentration, tc
for paved surface (n=0.015)
average surface slopes =1%
Design overland flow distance = 200m
chart 14.1 to = 10 mins
average velocity in open drain , assumed v = 1 m/s
drain length, Ld = 200 m
drain flow time, td = Ld / (v x 60) = 3 mins
thus, time of concentration, tc = to+ td = 13 mins
1.2 Determine rainfall intensity and Runoff Coefficient
Referred to Table of Average Rainfall Intensity (mm/hr) for short rainfall
duration for tc = 15 mins
thus,
rainfall intensity for 5 years storm5I 13 = 195.10 mm/hr
rainfall intensity for 10 years storm10I 13 = 215.20 mm/hr
rainfall intensity for 100 years storm100I 13 = 287.20 mm/hr
design chart Runoff Coefficient for Upstream catchment, C 5 = 0.88
14.4 3 Semi-detached house on bare earth C 10 = 0.88
C 100 = 0.88
1.3 Discharge flow computaion, Qpre , for Post-development
Q = (A1 x C1) x I + upQ
Discharge flow for 5 years storm Q 5,post = 3.48 m
3/s
Discharge flow for 10 years storm Q 10,post = 4.23 m
3/s
Discharge flow for 100 years storm Q 100,post = 6.27 m
3/s
CALCULATION OUTPUT
Designed :
Date :
Checked :
![Page 10: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/10.jpg)
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : 00109 / Meseba YauTY
page Main Drain Catchment Computation Ogos 02
of main drain A1 REF.
1.0 Meseba Development site
Upstream Catchment Area i) Forest Reserve= 20 acre = 8 ha
(undevelope area)
Meseba ( forest ) I) Meseba = 5.0 acre 2 ha
( developed area ) ii) meseba = 31 acre = 12.6 ha
1.1 Upstream Discharge, upQ
Discharge flow for 2 years storm upQ 2 = 0.81 m
3/s
Discharge flow for 5 years storm upQ 5 = 1.07 m
3/s
Discharge flow for 100 years storm upQ 100 = 1.72 m
3/s
1.1 Determine of time of concentration, tc
for paved surface (n=0.015)
average surface slopes =1%
Design overland flow distance = 200m
chart 14.1 to = 10 mins
average velocity in open drain , assumed v = 1 m/s
drain length, Ld = 450 m
drain flow time, td = Ld / (v x 60) = 8 mins
thus, time of concentration, tc = to+ td = 18 mins
1.2 Determine rainfall intensity and Runoff Coefficient
Referred to Table of Average Rainfall Intensity (mm/hr) for short rainfall
duration for tc = 18 mins
thus,
rainfall intensity for 2 years storm2I 18 = 134.40 mm/hr
rainfall intensity for 5 years storm5I 18 = 162.70 mm/hr
rainfall intensity for 100 years storm100I 18 = 238.70 mm/hr
design chart Runoff Coefficient for proposed site catchment, C 2 = 0.79
14.3 (4) Urban Residential Fully Built Up with Gardens C 5 = 0.84
C 100 = 0.86
JURUTERA PERUNDING TEGAP SDN. BHD.
Designed :
Date :
Checked :
CALCULATION OUTPUT
![Page 11: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/11.jpg)
PROJECT : 00109 / Meseba YauTY
page Main Drain Catchment Computation Ogos 02
of main drain A2 REF.
design chart Runoff Coefficient for proposed site catchment, C 2 = 0.6
14.4 (E) Close Crop C 5 = 0.63
C 100 = 0.66
Average Runoff coefficient for subcatchment , C2,avg = 0.76
C5,avg = 0.81
C100,avg = 0.83
1.3 Discharge flow computaion, Qpost, for Post-development
Q = (A1 x Cavg) x I + upQ
Discharge flow for 2 years storm Q 2,post = 4.16 m
3/s
Discharge flow for 5 years storm Q 5,post = 5.35 m
3/s
Discharge flow for 100 years storm Q 100,post = 8.06 m
3/s
1.4 Main drain A2 catchcment
Discharge From Main Drain A1 Q 2,post = 4.16 m
3/s
Q 5,post = 5.35 m3/s
Q 100,post = 8.06 m3/s
catchment from Main drain A2, ii) meseba = 5 acre = 2.02 ha
( developed area )
1.3 Discharge flow computaion, Qpost , for Post-development
Q = (A1 x C ) x I + upQ
Discharge flow for 2 years storm Q 2,post = 0.60 m
3/s
Discharge flow for 5 years storm Q 5,post = 0.77 m
3/s
Discharge flow for 100 years storm Q 100,post = 1.15 m
3/s
Total Discharge flow for 2 years storm Q 2,post = 4.76 m
3/s
Discharge flow for 5 years storm Q 5,post = 6.12 m
3/s
Discharge flow for 100 years storm Q 100,post = 9.21 m
3/s
OUTPUT
Designed :
Date :
Checked :
CALCULATION
![Page 12: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/12.jpg)
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : 00109 / Meseba YauTY
page Main Drain Catchment Computation Ogos 02
of main drain B1 & B3REF.
1.0 Meseba Development site
Upstream Catchment Area i) Sri-seltra = 23 acre = 9.3 ha
(undevelope area)
Meseba ( developed area ) I) Meseba =27 acre 10.93 ha
1.1 Upstream Discharge, upQ
Discharge flow for 2 years storm upQ 2 = 0.94 m
3/s
Discharge flow for 5 years storm upQ 5 = 1.25 m
3/s
Discharge flow for 100 years storm upQ 100 = 2.00 m
3/s
1.1 Determine of time of concentration, tc
for paved surface (n=0.015)
average surface slopes =1%
Design overland flow distance = 200m
chart 14.1 to = 10 mins
average velocity in open drain , assumed v = 1 m/s
drain length, Ld = 200 m
drain flow time, td = Ld / (v x 60) = 3 mins
thus, time of concentration, tc = to+ td = 13 mins
1.2 Determine rainfall intensity and Runoff Coefficient
Referred to Table of Average Rainfall Intensity (mm/hr) for short rainfall
duration for tc = 13 mins
thus,
rainfall intensity for 2 years storm2I 13 = 158.50 mm/hr
rainfall intensity for 5 years storm5I 13 = 195.10 mm/hr
rainfall intensity for 100 years storm100I 13 = 287.20 mm/hr
design chart Runoff Coefficient for proposed site catchment, C 2 = 0.82
14.3 (4) Urban Residential Fully Built Up with Gardens C 5 = 0.85
C 100 = 0.86
1.3 Discharge flow computaion, Qpost, for Post-development
Q = (A1 x Cavg) x I + upQ
Discharge flow for 2 years storm Q 2,post = 4.89 m
3/s
Discharge flow for 5 years storm Q 5,post = 6.28 m
3/s
Discharge flow for 100 years storm Q 100,post = 9.50 m
3/s
Designed :
Checked :
CALCULATION
Date :
OUTPUT
![Page 13: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/13.jpg)
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : 00109 / Meseba YauTY
page Main Drain Catchment Computation Ogos 02
of main drain B2REF.
1.0 Meseba Development site
Upstream Catchment Area i) Sri-seltra = 10 acre = 4.05 ha
(undevelope area)
Meseba ( developed area ) I) Meseba =3 acre 1.2 ha
1.1 Upstream Discharge, upQ
Discharge flow for 2 years storm upQ 2 = 0.41 m
3/s
Discharge flow for 5 years storm upQ 5 = 0.54 m
3/s
Discharge flow for 100 years storm upQ 100 = 0.87 m
3/s
1.1 Determine of time of concentration, tc
for paved surface (n=0.015)
average surface slopes =1%
Design overland flow distance = 200m
chart 14.1 to = 10 mins
average velocity in open drain , assumed v = 1 m/s
drain length, Ld = 100 m
drain flow time, td = Ld / (v x 60) = 2 mins
thus, time of concentration, tc = to+ td = 12 mins
1.2 Determine rainfall intensity and Runoff Coefficient
Referred to Table of Average Rainfall Intensity (mm/hr) for short rainfall
duration for tc = 12 mins
thus,
rainfall intensity for 2 years storm2I 12 = 164.40 mm/hr
rainfall intensity for 5 years storm5I 12 = 203.30 mm/hr
rainfall intensity for 100 years storm100I 12 = 299.60 mm/hr
design chart Runoff Coefficient for proposed site catchment, C 2 = 0.82
14.3 (4) Urban Residential Fully Built Up with Gardens C 5 = 0.85
C 100 = 0.86
1.3 Discharge flow computaion, Qpost, for Post-development
Q = (A1 x Cavg) x I + upQ
Discharge flow for 2 years storm Q 2,post = 0.86 m
3/s
Discharge flow for 5 years storm Q 5,post = 1.12 m
3/s
Discharge flow for 100 years storm Q 100,post = 1.73 m
3/s
OUTPUT
Designed :
Date :
Checked :
CALCULATION
![Page 14: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/14.jpg)
U-drain
Side wall : 1/sw = 0
depth, D = 1.2 m without FB
width, W = 0.6 m
Side width : Ws = 0 m
Area, A = 0.72 m2
perineter, P = 3 m
R = 0.24 m
drain gradient , S =1/ 200
n = 0.015
discharge, Q = 1.310792 m3/s > required. OK.
velocity, V = 1.484237 m/s < 3.0 m/s. OK WITH PUDU CUT DRAIN
top water lever TWL = 1.8 m 100 year storm A= 0.163142
top water lever TWL = 0.96 m 5 year storm P= 1.174
TOTAL
A= 0.883142
P= 3.124
R= 0.282696
D
W
![Page 15: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/15.jpg)
WITH PUDU CUT DRAIN
![Page 16: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/16.jpg)
HR-drain
Side wall : 1/sw = 0
depth, D = 0.75 m without FB
width, W = 1 m
Side width : Ws = 0 m
Area, A = 1.032743 m2 0.75
perimeter, P = 2.842478 m
R = 0.363325 m
drain gradient , S =1/ 200
n = 0.015
discharge, Q = 2.478847 m3/s > required. OK.
velocity, V = 2.400254 m/s < 3.0 m/s. OK WITH H/R DRAIN
H/R drain dia. = 0.6
top water lever TWL = 1.8 m 100 year storm A= 0.282743
top water lever TWL = 0.96 m 5 year storm P= 0.942478
D
W
![Page 17: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/17.jpg)
m
![Page 18: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/18.jpg)
\\vboxsrv\conversion_tmp\scratch_3\[236585396.xls.ms_office.xls]box
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : Lot 1149 YauTY
page Catchment Flow Compuation
of post-development discharge computaion - Catchment A
REF.
Box culvert Capacity computation
depth, D = 1.50 m without FB
width, W = 2.10 m
Area, A = 3.15 m2
perimeter, P = 5.10 m
R = 0.62 m
drain gradient , S =1/ 500
n = 0.015
discharge, Q = 6.81 m3/s > required. OK.
velocity, V = 2.16 m/s < 4.0 m/s. OK
top water lever TWL = 1.43 m 100 years storm Q100,post = 6.42 m3/s
top water lever TWL = 1.09 m 10 years storm Q10,post = 4.49 m3/s
top water lever TWL = 0.97 m 5 years storm Q5,post = 3.83 m3/s
Thus, Proposed 2.1 x 1.8 m PC Box Culvert
(include 0.3 free board)
OUTPUT
Designed :
Date :
Checked :
CALCULATION
Apr-06
W
D
0.3 FB
Box Culvert
TWL
![Page 19: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/19.jpg)
\\vboxsrv\conversion_tmp\scratch_3\[236585396.xls.ms_office.xls]box
JURUTERA PERUNDING TEGAP SDN. BHD.
PROJECT : Lot 1149 YauTY
page Catchment Flow Compuation
of post-development discharge computaion - Catchment B
REF.
Box culvert Capacity computation
depth, D = 1.50 m without FB
width, W = 2.10 m
Area, A = 3.15 m2
perimeter, P = 5.10 m
R = 0.62 m
drain gradient , S =1/ 500
n = 0.015
discharge, Q = 6.81 m3/s > required. OK.
velocity, V = 2.16 m/s < 4.0 m/s. OK
top water lever TWL = 1.41 m 100 years storm Q100,post = 6.27 m3/s
top water lever TWL = 1.04 m 10 years storm Q10,post = 4.23 m3/s
top water lever TWL = 0.9 m 5 years storm Q5,post = 3.48 m3/s
Thus, Proposed 2.1 x 1.8 m PC Box Culvert
(include 0.3 free board)
Checked :
CALCULATION OUTPUT
Apr-06
Designed :
Date :
W
D
0.3 FB
Box Culvert
TWL
W
D
0.3 FB
Box Culvert
TWL
![Page 20: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/20.jpg)
2.0 Main Drain A1 - Computation of Section Capacity
Pudu Cut Drain
drainage reserve = 20.0 m area,Ap = 0.16 m
alow freeboard = 0.3 m perimeter, Pp = 1.17 m
drain gradient , S =1/ 1500
n = 0.015 (for lined
Bottom section concrete drain)
Side wall slope: 1/sw1= 2.00
drain depth, D1 = 1.45 m
drain width, W = 5.5 m
Side slope width : Ws1 = 2.90 m
wetted Area, A1 = 12.36 m2
wetted perineter, P1 = 17.59 m
R1 = 0.70 m
Upper Section
Side wall slope: 1/sw1= 2.00
drain depth, D2 = 0 m
drain width, W2= 1.8 m
Side slope width : Ws2 = NIL m
total wetted Area, A = NIL m2
total wetted perineter, P = NIL m
R = NIL m
drain cpacity, Q = 16.82 m3/s > required discharge, drain section is
velocity, V = 1.36 m/s sufficient
5 yeasr storm top water lever, TWL5 = 1.16 m
100 years storm top water lever, TWL100 = 1.4 m
drainage reserve
pudu cut section W
d
1.05
D
Sw1
1
freeboard
Ws1
1
D1
W2 Ws2
D2 Sw2
drainage reserve
dD
freeboard
1 D2 Sw2
![Page 21: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/21.jpg)
Pudu Cut Drain
drainage reserve = 20.0 m area,Ap = 0.16 m
alow freeboard = 0.3 m perimeter, Pp = 1.17 m
drain gradient , S =1/ 1500
n = 0.018 (for lined
Bottom section concrete drain)
Side wall slope: 1/sw1= 2
drain depth, D1 = 1.35 m
drain width, W = 8.0 m
Side slope width : Ws1 = 2.70 m
wetted Area, A1 = 14.61 m2
wetted perineter, P1 = 19.25 m
R1 = 0.76 m
Upper Section
Side wall slope: 1/sw1= 2
drain depth, D2 = 0.10294394 m
drain width, W2= 1.5 m
Side slope width : Ws2 = 0.21 m
total wetted Area, A = 16.31 m2
total wetted perineter, P = 22.71 m
R = 0.72 m
drain cpacity, Q = 18.77 m3/s > required discharge, drain section is
velocity, V = 1.15 m/s sufficient
5 yeasr storm top water lever, TWL5 = 1.17 m
100 years storm top water lever, TWL100 = 1.61 m
2.0 Main Drain F - Computation of Section Capacity
Pudu cut drain
drainage reserve = 6.0 m area,Ap = 0.16 m
pudu cut section W
1.05
D
Sw1
1
Ws1
D1
W2 Ws2
Sw2
Ws
pudu cut section
W
ddrainage reserve
1.05
D
Sw
1
freeboard
![Page 22: main drain calculation](https://reader034.vdocuments.us/reader034/viewer/2022042517/577cc7931a28aba711a15eba/html5/thumbnails/22.jpg)
alow freeboard = 0.3 m perimeter, Pp = 1.17 m
Side wall slope: 1/sw= 0.17 drain gradient , S =1/ 500
drain depth, D = 1.341 m n = 0.02 (for rubble wall)
drain width, W = 3.5 m
Side slope width : Ws = 0.22 m
total wetted Area, A = 5.15 m2
wetted perineter, P = 6.45 m
R = 0.80 m
drain cpacity, Q = 9.92 m3/s > required discharge, drain section is
velocity, V = 1.93 m/s sufficient
5 years storm top water lever, TWL5 = 1.12 m
100 years storm top water lever, TWL100 = 1.57 m