Download pdf - main drain calculation

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

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


100 years storm top water lever, TWL100 = 1.28 m

thus provide PC Block drain section with minimum

wall height = 1.5m


Designed :

Date :

Checked :

CALCULATION OUTPUT

drainage reserve

PC Block Drain

W

d

0.6

D

Sw1

1

0.3m FB

Ws1


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


n = 0.015 stone pitching

Bottom section drain

Side wall slope: 1/sw1= 0.5






R1 = 0.72 m

drain cpacity, Q = 12.01 m3/s > required discharge, drain section is

velocity, V = 3.10 m/s sufficient




thus provide Pudu cut drain section with minimum

wall height = 1.5m



CALCULATION OUTPUT

Designed :

Date :

Checked :

Designed :

drainage reserve

pudu cut section W

d

1.05

D

Sw1

1

0.3m FB

Ws1

page Main Drain Capacity Ogos 02

of main drain B1& B3REF.

Pudu Cut Drain




n = 0.015 stone pitching

Bottom section drain







R1 = 0.91 m






thus provide Pudu cut drain section with minimum

wall height = 2.0m



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

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


Bottom section n = 0.015 stone pitching

Side wall slope: 1/sw1= 0.50 drain






R1 = 0.28 m

drain cpacity, Q = 1.63 m3/s > required discharge,

velocity, V = 2.00 m/s < 4.0 m/s




drainage reserve

PC Block Drain

W

d

0.6

D

Sw1

1

0.3m FB

Ws1

\\vboxsrv\conversion_tmp\scratch_3\[236585396.xls.ms_office.xls]box


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



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


3/s


3/s

Designed :

Date :

Checked :

CALCULATION OUTPUT





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


3/s


3/s


for paved surface (n=0.015)





drain length, Ld = 200 m






thus,





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


3/s


3/s

CALCULATION OUTPUT

Designed :

Date :

Checked :





of pre-development discharge computaion

REF.

1.0 Upstream Catchment Area

Upstream Catchment Area from catchment B = 22.1 ha

22.1 ha


for density grassed surface (n=0.060)





natural channel, Ld = 600 m






thus,





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


3/s


3/s


3/s

Designed :

Date :

Checked :

CALCULATION OUTPUT





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



3/s


3/s


3/s













thus,





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


3/s


3/s


3/s

CALCULATION OUTPUT

Designed :

Date :

Checked :



page Main Drain Catchment Computation Ogos 02


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


Discharge flow for 2 years storm upQ 2 = 0.81 m

3/s


3/s


3/s













thus,




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


Designed :

Date :

Checked :

CALCULATION OUTPUT





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


3/s


3/s


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


3/s


3/s


3/s

Total Discharge flow for 2 years storm Q 2,post = 4.76 m

3/s


3/s


3/s

OUTPUT

Designed :

Date :

Checked :

CALCULATION




of main drain B1 & B3REF.


Upstream Catchment Area i) Sri-seltra = 23 acre = 9.3 ha

(undevelope area)

Meseba ( developed area ) I) Meseba =27 acre 10.93 ha



3/s


3/s


3/s













thus,






C 100 = 0.86




3/s


3/s


3/s

Designed :

Checked :

CALCULATION

Date :

OUTPUT




of main drain B2REF.


Upstream Catchment Area i) Sri-seltra = 10 acre = 4.05 ha

(undevelope area)

Meseba ( developed area ) I) Meseba =3 acre 1.2 ha



3/s


3/s


3/s













thus,






C 100 = 0.86




3/s


3/s


3/s

OUTPUT

Designed :

Date :

Checked :

CALCULATION

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


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

WITH PUDU CUT DRAIN

HR-drain

Side wall : 1/sw = 0


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


n = 0.015


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

m




page Catchment Flow Compuation

of post-development discharge computaion - Catchment A

REF.

Box culvert Capacity computation


width, W = 2.10 m

Area, A = 3.15 m2


R = 0.62 m


n = 0.015


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



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 Catchment Flow Compuation

of post-development discharge computaion - Catchment B

REF.

Box culvert Capacity computation


width, W = 2.10 m

Area, A = 3.15 m2


R = 0.62 m


n = 0.015


velocity, V = 2.16 m/s < 4.0 m/s. OK




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

2.0 Main Drain A1 - Computation of Section Capacity

Pudu Cut Drain




n = 0.015 (for lined

Bottom section concrete drain)







R1 = 0.70 m

Upper Section


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





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

Pudu Cut Drain




n = 0.018 (for lined

Bottom section concrete drain)

Side wall slope: 1/sw1= 2






R1 = 0.76 m

Upper Section

Side wall slope: 1/sw1= 2


drain width, W2= 1.5 m


total wetted Area, A = 16.31 m2

total wetted perineter, P = 22.71 m

R = 0.72 m





2.0 Main Drain F - Computation of Section Capacity

Pudu cut drain


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


Side wall slope: 1/sw= 0.17 drain gradient , S =1/ 500

drain depth, D = 1.341 m n = 0.02 (for rubble wall)


Side slope width : Ws = 0.22 m

total wetted Area, A = 5.15 m2

wetted perineter, P = 6.45 m

R = 0.80 m



