detention pond design using masma

(i)

CONTENTS

PARTICULARS PAGES

MAIN DRAIN DESIGN CALCULATION 1 - 5

1 ) Design of Main Drain 'M1' 2

1.1) 21.2) Determine design flows for the darin 2

Location plan 3Pelan Butiran dan Titik Ketinggian 4

1.3) Data Main Drain 'M1' 5

DETENTION POND DESIGN CALCULATION 6 - 60

1) Calculate time of concentration1.1) Pre-development 7

Pelan Butiran dan Titik Ketinggian 81.2) Post-development 9

2) Compute Time-Area Diagram (TAD) for pre-development 10 - 11

3) Compute Time-Area Diagram (TAD) for post-development3.1) Computation of sub-catchment 12 - 133.2) Rearrange data in ascending order of t 143.3) Differentiating area with respect to time 153.4) Isochrone division, using 4 time intervals 15

4) Calculate Design Rainfall for Kuala Lumpur4.1) 10 ARI Design Rainfall 164.2) 50 ARI Design Rainfall 174.3) 100 ARI Design Rainfall 18

5) Computation of Temporal Pattern & Effective Rainfall (ER)5.1) Temporal Pattern & ER for 10 ARI pre-development 195.2) Temporal Pattern & ER for 50 ARI pre-development 205.3) Temporal Pattern & ER for 100 ARI pre-development 215.4) Temporal Pattern & ER for 10 ARI post-development 22 -235.5) Temporal Pattern & ER for 50 ARI post-development 24 - 255.6) Temporal Pattern & ER for 100 ARI post-development 26 - 27

6)6.1) Cal. Inflows Hydrograph for 10 ARI, 60 min Rainfall Duration 286.2) Cal. Inflows Hydrograph for 50 ARI, 60 min Rainfall Duration 296.3) Cal. Inflows Hydrograph for 100 ARI, 60 min Rainfall Duration 30

7) Compute the detention pond inflow hydrograph for tc post7.1 - 7.5) For 10 ARI 31 -337.6 - 7.10) For 50 ARI 34 - 367.11 – 7.15) For 100 ARI 37 - 39

8) Summary of pre & post-development flows hydrographs 40

9) Graphs of 50 ARI post-development inflow hydrographs for estimation of 41 - 42Detention pond size

Calculate tc for pre development

Compute the detention pond outflow limits for tc pre

(ii)

CONTENTS

PARTICULARS PAGES

10) Graphs of 100 ARI post-development inflow hydrographs for estimation of 43 - 44Detention pond size

11) Estimation of detention basin volume11.1) Based on 50 ARI post-developed inflows 4511.2) Based on 100 ARI post-developed inflows 4611.3) Conclusion 46

12) Compute Stage - Storage Relationship 47

13) Size the minor and major design storm primary outlet13.1) Estimate size of primary outlets 4813.2) Size the minor and major design storm primary outlet 4913.3) Trials selecting acceptable combinations of primary outlets 50

14) Compute stage-discharge relationship using orifice equation for primary outlet 51

15) Develop storage - outflow function 52

16) Inflow hydrograph routing for primary outlet16.1) Route the 10 ARI 30 min. post-developed inflow hydrograph through the 53

1st primary outlet

16.2) Route the 50 ARI 30 min. post-developed inflow hydrograph through the 542nd primary outlet

17) Compute stage-discharge relationship for secondary outlet (emergency spillway, ES) 55

18) Inflow hydrograph routing for secondary outlet (emergency spillway)18.1) Route the 100 ARI 30 min. post-developed inflow hydrograph through the 56

2nd primary outlet

19) Summary of detention pond design calculation 57

Plan and Section of Detention Pond 58 - 60

INTERNAL MAIN DRAIN DESIGN CALCULATION 61 - 71

1) Design of Internal Main Drain 'D1' 62 - 63




5) Design of Internal Main Drain 'D5' 70

Site Plan 71

REFERENCE 72

7

DESIGN OF DETENTION POND

PROJECT:

1) Calculate time of concentrations

1.1) Pre-development ( using Eq. 14.6 for natural catchment )

Equation 14.6, Vol. 5, natural catchment

A = 12.141 ha.L = 0.810 km L = length of flow path from catchment divide to outlety = 18.000 y = RL at upstream point ( refer contour plan attached )x = 12.800 x = RL at downstream point ( refer contour plan attached )

Average slope,S =S = 6.423 m/km S = slope of stream flow path

40 min. Use 60 min

Time interval = 5 min Table 13.4, Vol. 4No. of intervals = 8.0 Use 12 intervals

tc = 92.5 x L / (A1/10 x S1/5)

Conversion factor = 58.5 if area in km2

( y - x ) ÷ L

tc =

DESIGN OF DETENTION POND 3

1.2) Post-development

Equation 14.1, Vol. 5, urban catchment

12.192 m Length of roadn = 0.015 Manning's n from Table 14.2, Vol.5

Road camber slope = 1/40 1/40 ( JKR Srandard )Side table slope = 1/25 1/25

Average Slope, S = 13/400 S = slope of overland surface ( runoff from road )S = 3.25 %

2 min.

(Eq.14.5, Vol.5)

810 mV = 1 m/s

13 min.

16 min. Use 30 min

Time interval = 5 min Table 13.4, Vol. 4No. of intervals = 3.1 Use 6 iintervals

to = (107 x n x L1/3) / (S1/2)

Lo =

to =

td = Ld / V

Ld =

td =

tc = to + td

tc =


2) Compute Time-Area Diagram(TAD) for pre-development ( natural catchment )

Using 5 time intervals:

( 40/810 = 5/L )for t = 5 min

L = 101 mfor t = 10 min

L = 201 m

Draw isochrones on plan ( refer attached plan ) and planimeter areas:

Time( min )

0 - 5 A1 25,6725 - 10 A2 24,789

10 - 15 A3 24,44015 - 30 A4 24,20430 - 60 A5 22,305

Total 121,410

Time of flow is proportional to length

Area ( m2 )


3) Compute TAD for post-development ( urban catchment )

3.1) Computation of subcatchment and flow time

Refer plan attached for subcatchment

time of flow in drain up to subcatchment outlet

time of flow in drain from subcatchment outlet to detention pond

Sub Area t

Catchment ( m ) ( m ) ( m ) ( min ) ( min ) ( min ) ( min )

1 7,471 6.096 240.506 569.046 1.63 4.01 9.48 15.122 14,630 12.192 49.663 507.339 2.05 0.83 8.46 11.333 12,973 12.192 51.193 444.102 2.05 0.85 7.40 10.304 12,821 12.192 51.189 380.865 2.05 0.85 6.35 9.255 14,863 12.192 89.929 278.892 2.05 1.50 4.65 8.206 6,453 12.192 51.053 215.833 2.05 0.85 3.60 6.507 5,923 12.192 46.491 157.336 2.05 0.77 2.62 5.458 5,831 7.62 170.118 233.422 1.75 2.84 3.89 8.489 3,376 12.192 20.291 202.296 2.05 0.34 3.37 5.76

10 6,530 12.192 146.994 43.296 2.05 2.45 0.72 5.2211 606 3.048 157.018 0 1.29 2.62 0.00 3.9112 8,595 6.096 317.321 59.715 1.63 5.29 1.00 7.9113 3,907 6.096 112.667 170.904 1.63 1.88 2.85 6.3514 6,121 6.096 51.118 107.763 1.63 0.85 1.80 4.2715 5,879 6.096 95.865 0 1.63 1.60 0.00 3.22

115,979

to = (107 x n x L1/3) / (S1/2), for runoff from road surface

td =

td1 =

Lo Ld Ld1 to td td1

( m2 )


3.2) Rearrange data in ascending order of t

Sub t Area Cummulative

Catchment Area

( No. ) ( min )

0 0 01 15 3.22 5879.00 5,8792 11 3.91 606.00 6,4853 14 4.27 6121.00 12,6064 10 5.22 6530.00 19,1365 7 5.45 5923.00 25,0596 9 5.76 3376.00 28,4357 13 6.35 3907.00 32,3428 6 6.50 6453.00 38,7959 12 7.91 8595.00 47,390

10 5 8.20 14863.00 62,25311 8 8.48 5831.00 68,08412 4 9.25 12821.00 80,90513 3 10.30 12973.00 93,87814 2 11.33 14630.00 108,50815 1 15.12 7471.00 115,979

115,979

40

15.12

0.38

( to+td+td1 )

( m2 ) ( m2 )

tc =

Te =

Te/tc =


3.3) Differentiating area with respect to time

For (a) :

15.12 min

dA/dt = 7,671

3.4) Isochrone division, using 4 time intervals

Time( min )

Te =

115,979 ÷ 15.12 = m2/min

Area ( m2 )

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160

20000

40000

60000

80000

100000

120000

140000

05,879 6,485

12,606

19,13625,059

28,43532,342

38,795

47,390

62,25368,084

80,905

93,878

108,508

115,979

TAD GRAPH FOR POST-DEVELOPMENT

Time (min)

Cu

mm

ula

tive

Are

a (m

2)

0 - 5 A1 38,3565 - 10 A2 38,356

10 - 15 A3 38,35615 - 30 A4 912

Total 115,979


4) Calculate Design Rainfall for Kuala Lumpur

4.1) 10 ARI Design Rainfall

( Eq. 13.2, Vol. 4 )

a) Rainfall > 30 minutes

Table 13.A1, Vol. 4In ( I )

I(min) a b c d mm/hr mm

30 4.9696 0.6796 -0.2584 0.0147 4.8702 130.35 65.1860 4.9696 0.6796 -0.2584 0.0147 4.4293 83.88 83.88

120 4.9696 0.6796 -0.2584 0.0147 3.9137 50.08 100.16180 4.9696 0.6796 -0.2584 0.0147 3.5891 36.20 108.60

b) Rainfall < 30 minutes

( Eq. 13.3, Vol. 4 )

d(min) (Table 13.3) (mm) mm/hr

5 2.08 26.28 315.3310 1.28 41.24 247.4315 0.80 50.21 200.8620 0.47 56.39 169.1630 0.00 65.18 130.35

In ( RIt ) = a + b In( t ) + c ( In( t ) )2 + d ( In( t ) )3

tc Pd

Pd = P30 - FD( P60 - P30 )

FD Pd Id


4.2) 50 ARI Design Rainfall for Kuala Lumpur

( Eq. 13.2, Vol. 4 )




30 4.8047 0.9399 -0.3218 0.0197 5.0540 156.64 78.3260 4.8047 0.9399 -0.3218 0.0197 4.6106 100.54 100.54

120 4.8047 0.9399 -0.3218 0.0197 4.0905 59.77 119.53180 4.8047 0.9399 -0.3218 0.0197 3.7664 43.22 129.67


( Eq. 13.3, Vol. 4 )


5 2.08 32.10 385.2510 1.28 49.88 299.2815 0.80 60.55 242.1820 0.47 67.88 203.6330 0.00 78.32 156.64


tc Pd

Pd = P30 - FD( P60 - P30 )

FD Pd Id


4.3)100 ARI Design Rainfall for Kuala Lumpur

( Eq. 13.2, Vol. 4 )




30 5.0064 0.8709 -0.3070 0.0186 5.1489 172.24 86.1260 5.0064 0.8709 -0.3070 0.0186 4.7024 110.21 110.21

120 5.0064 0.8709 -0.3070 0.0186 4.1803 65.39 130.78180 5.0064 0.8709 -0.3070 0.0186 3.8548 47.22 141.66


( Eq. 13.3, Vol. 4 )


5 2.08 36.03 432.3110 1.28 55.29 331.7615 0.80 66.85 267.4220 0.47 74.80 224.4130 0.00 86.12 172.24


tc Pd

Pd = P30 - FD( P60 - P30 )

FD Pd Id


5) Computation of Temporal Pattern & Effective Rainfall ( ER )

No of Fraction of Rainfall in Each Time PeriodTime Table 13.B1, Vol. 4

Periods 1 2 3 4 5 6 7 8 9 10 11 12

10 2 0.570 0.430 - - - - - - - - - -15 3 0.320 0.500 0.180 - - - - - - - - -30 6 0.160 0.250 0.330 0.090 0.110 0.060 - - - - - -60 12 0.039 0.070 0.168 0.120 0.232 0.101 0.089 0.057 0.048 0.031 0.028 0.017

120 8 0.030 0.119 0.310 0.208 0.090 0.119 0.094 0.030 - - - -180 6 0.060 0.220 0.340 0.220 0.120 0.040 - - - - - -360 6 0.320 0.410 0.110 0.080 0.050 0.030 - - - - - -

5.1) Temporal Pattern & ER for 10 ARI pre-development

Initial loss = 10 mm ; proportional loss = 20 % of rainfall ( Table 14.4, Vol. 5 )

Storm Duration = 60 min Rainfall = 83.88 mmNo. of Time Interval = 12 Time Interval = 5 minutes ( Table 13.4, Vol. 4 )

Time Rainfall Initial Loss Pro. Loss ERInterval ( mm ) ( mm ) ( mm ) ( mm )

1 3.27 3.27 0.00 0.002 5.87 5.87 0.00 0.003 14.09 0.86 2.65 10.584 10.07 - 2.01 8.055 19.46 - 3.89 15.576 8.47 - 1.69 6.787 7.46 - 1.49 5.978 4.78 - 0.96 3.829 4.03 - 0.81 3.22

10 2.60 - 0.52 2.0811 2.35 - 0.47 1.8812 1.43 - 0.29 1.14

Total 83.88 10.00 14.78 59.10

Duration ( min )

a) For Storm Duration, td = 60 minutes




Storm Duration = 60 min Rainfall = 100.54 mmNo. of Time Interval = 12 Time Interval = 5 minutes ( Table 13.4, Vol. 4 )Time Rainfall Initial Loss Pro. Loss ER

Interval ( mm ) ( mm ) ( mm ) ( mm )

1 3.92 3.92 0.00 0.002 7.04 6.08 0.19 0.773 16.89 - 3.38 13.514 12.06 - 2.41 9.655 23.33 - 4.67 18.666 10.15 - 2.03 8.127 8.95 - 1.79 7.168 5.73 - 1.15 4.589 4.83 - 0.97 3.86

10 3.12 - 0.62 2.4911 2.82 - 0.56 2.2512 1.71 - 0.34 1.37

Total 100.54 10.00 18.11 72.43





Storm Duration = 60 min Rainfall = 110.21 mmNo. of Time Interval = 12 Time Interval = 5 minutes ( Table 13.4, Vol. 4 )

Time Rainfall Initial Loss Pro. Loss ERInterval ( mm ) ( mm ) ( mm ) ( mm )

1 4.30 3.92 0.08 0.302 7.71 6.08 0.33 1.313 18.51 - 3.70 14.814 13.22 - 2.64 10.585 25.57 - 5.11 20.456 11.13 - 2.23 8.907 9.81 - 1.96 7.858 6.28 - 1.26 5.039 5.29 - 1.06 4.23

10 3.42 - 0.68 2.7311 3.09 - 0.62 2.4712 1.87 - 0.37 1.50

Total 110.21 10.00 20.04 80.17



5.4) Temporal Pattern & ER for 10 ARI post-development

Initial loss = 1.5 mm ; loss rate = 0 mm/hr ( Table 14.4, Vol. 5 )

Storm Duration = 5 min Rainfall = 26.28No. of Time Interval = 1 Time Interval = 5 minutes ( Table 13.4, Vol. 4 )

Time Rainfall Initial Loss ERInterval ( mm ) ( mm ) ( mm )

1 26.28 1.50 24.78

Total 26.28 1.50 24.78

Storm Duration =10 min Rainfall = 41.24No. of Time Interval = 2 Time Interval = 5 minutes ( Table 13.4, Vol. 4 )


1 23.51 1.50 22.012 17.73 - 17.73

Total 41.24 1.50 39.74



1 16.07 1.50 14.572 25.11 - 25.113 9.04 - 9.04

Total 50.21 1.50 48.71


b) For Storm Duration, td = 10 minutes

c) For Storm Duration, td = 15 minutes



1 10.43 1.50 8.932 16.29 - 16.293 21.51 - 21.514 5.87 - 5.875 7.17 - 7.176 3.91 - 3.91

Total 65.18 1.50 63.68

d) For Storm Duration, td = 30 minutes






1 10.43 1.50 8.932 16.29 - 16.293 21.51 - 21.514 5.87 - 5.875 7.17 - 7.176 3.91 - 3.91

Total 65.18 1.50 63.68



1 3.27 1.50 1.772 5.87 - 5.873 14.09 - 14.094 10.07 - 10.075 19.46 - 19.466 8.47 - 8.477 7.46 - 7.468 4.78 - 4.789 4.03 - 4.03

10 2.60 - 2.6011 2.35 - 2.3512 1.43 - 1.43

Total 83.88 1.50 82.38


e) For Storm Duration, td = 60 minutes

Storm Duration = 120 min Rainfall = 100.16No. of Time Interval = 8 Time Interval = 15 minutes


1 3.00 1.50 1.502 11.92 − 11.923 31.05 − 31.054 20.83 − 20.835 9.01 − 9.016 11.92 − 11.927 9.42 − 9.428 3.00 − 3.00

Total 100.16 1.50 98.66



1 6.52 1.50 5.022 23.89 − 23.893 36.92 − 36.924 23.89 − 23.895 13.03 − 13.036 4.34 − 4.34

Total 108.60 1.50 107.10

f) For Storm Duration, td = 120 minutes

g) For Storm Duration, td = 180 minutes






1 32.10 1.50 30.60

Total 32.10 1.50 30.60



1 28.43 1.50 26.932 21.45 - 21.45

Total 49.88 1.50 48.38



1 19.37 1.50 17.872 30.27 - 30.273 10.90 - 10.90

Total 60.55 1.50 59.05









1 12.53 1.50 11.032 19.58 - 19.583 25.85 - 25.854 7.05 - 7.055 8.62 - 8.626 4.70 - 4.70

Total 78.32 1.50 76.82



1 3.92 1.50 2.422 7.04 - 7.043 16.89 - 16.894 12.06 - 12.065 23.33 - 23.336 10.15 - 10.157 8.95 - 8.958 5.73 - 5.739 4.83 - 4.83

10 3.12 - 3.1211 2.82 - 2.8212 1.71 - 1.71

Total 100.54 1.50 99.04


e) For Storm Duration, td = 60 minutes



1 3.59 1.50 2.092 14.22 − 14.223 37.06 − 37.064 24.86 − 24.865 10.76 − 10.766 14.22 − 14.227 11.24 − 11.248 3.59 − 3.59

Total 119.53 1.50 118.03



1 7.78 1.50 6.282 28.53 − 28.533 44.09 − 44.094 28.53 − 28.535 15.56 − 15.56

f) For Storm Duration, td = 120 minutes

g) For Storm Duration, td = 180 minutes

6 5.19 − 5.19Total 129.67 1.50 128.17






1 36.03 1.50 34.53

Total 36.03 1.50 34.53



1 31.52 1.50 30.022 23.78 - 23.78

Total 55.29 1.50 53.79



1 21.39 1.50 19.892 33.43 - 33.433 12.03 - 12.03

Total 66.85 1.50 65.35





6.1 ) Cal. Inflow Hydrograph for 10 ARI, 60 min Rainfall Duration

25,672 24,789 24,440 24,204 22,305

( min ) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 0.00 0.0000 0.02 0.00 0.02 5 300 0.000

10 0.00 0.0000 0.03 0.02 0.00 0.05 5 300 0.00015 10.58 0.0106 271.74 0.03 0.02 0.00 271.79 5 300 0.90620 8.05 0.0081 206.71 262.39 0.03 0.02 0.00 469.15 5 300 1.56425 15.57 0.0156 399.65 199.60 258.70 0.03 0.02 857.99 5 300 2.86030 6.78 0.0068 173.98 385.90 196.79 256.20 0.02 1,012.90 5 300 3.37635 5.97 0.0060 153.31 168.00 380.47 194.89 236.10 1,132.77 5 300 3.77640 3.82 0.0038 98.19 148.04 165.63 376.79 179.60 968.26 5 300 3.22845 3.22 0.0032 82.69 94.81 145.95 164.03 347.23 834.72 5 300 2.78250 2.08 0.0021 53.40 79.84 93.48 144.55 151.17 522.43 5 300 1.74155 1.88 0.0019 48.23 51.56 78.72 92.57 133.20 404.29 5 300 1.34860 1.14 0.0011 29.28 46.57 50.84 77.96 85.31 289.96 5 300 0.96765 0.00 28.28 45.92 50.35 71.84 196.38 5 300 0.65570 0.00 27.88 45.48 46.40 119.75 5 300 0.39975 0.00 27.61 41.91 69.52 5 300 0.23280 0.00 25.44 25.44 5 300 0.08585 0.00 0.00 5 300 0.00090

Maximum Inflow = 3.776

6) Compute the detention pond outflow limits for tc pre

Time

Effective Rainfall ( mm

)

Effective Rainfall ( m

)

A1 ( m2 ) A2 ( m2 ) A3 ( m2 ) A4 ( m2 ) A5 ( m2 ) Total Depth

( m3 )

Time Interval ( min

)

Time

Inflow

Inflow Volume ( m3 ) ( m3/s )



25,672 24,789 24,440 24,204 22,305

( min ) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 0.00 0.0000 0.02 0.00 0.02 5 300 0.000

10 0.77 0.0008 19.67 0.02 0.00 19.69 5 300 0.06615 13.51 0.0135 346.90 19.00 0.02 0.00 365.91 5 300 1.22020 9.65 0.0097 247.78 334.97 18.73 0.02 0.00 601.50 5 300 2.00525 18.66 0.0187 479.05 239.26 330.25 18.55 0.02 1,067.13 5 300 3.55730 8.12 0.0081 208.55 462.57 235.89 327.06 17.09 1,251.17 5 300 4.17135 7.16 0.0072 183.77 201.38 456.06 233.61 301.40 1,376.22 5 300 4.58740 4.58 0.0046 117.70 177.45 198.54 451.66 215.29 1,160.63 5 300 3.86945 3.86 0.0039 99.11 113.65 174.95 196.63 416.22 1,000.56 5 300 3.33550 2.49 0.0025 64.01 95.70 112.05 173.26 181.20 626.23 5 300 2.08755 2.25 0.0023 57.82 61.81 94.36 110.97 159.67 484.62 5 300 1.61560 1.37 0.0014 35.10 55.83 60.94 93.45 102.26 347.58 5 300 1.15965 0.00 33.90 55.04 60.35 86.11 235.40 5 300 0.78570 0.00 33.42 54.51 55.62 143.54 5 300 0.47875 0.00 33.10 50.23 83.33 5 300 0.27880 0.00 30.50 30.50 5 300 0.10285 0.00 0.00 5 300 0.00090


Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow




25,672 24,789 24,440 24,204 22,305

( min ) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 0.30 0.0003 7.76 0.00 7.76 5 300 0.026

10 1.31 0.0013 33.57 7.50 0.00 41.06 5 300 0.13715 14.81 0.0148 380.25 32.41 7.39 0.00 420.05 5 300 1.40020 10.58 0.0106 271.60 367.17 31.96 7.32 0.00 678.05 5 300 2.26025 20.45 0.0205 525.10 262.26 362.00 31.65 6.75 1,187.76 5 300 3.95930 8.90 0.0089 228.60 507.04 258.57 358.50 29.17 1,381.88 5 300 4.60635 7.85 0.0078 201.44 220.74 499.90 256.07 330.38 1,508.53 5 300 5.02840 5.03 0.0050 129.01 194.51 217.63 495.08 235.98 1,272.21 5 300 4.24145 4.23 0.0042 108.64 124.57 191.77 215.53 456.23 1,096.75 5 300 3.65650 2.73 0.0027 70.16 104.91 122.82 189.92 198.62 686.43 5 300 2.28855 2.47 0.0025 63.37 67.75 103.43 121.64 175.02 531.21 5 300 1.77160 1.50 0.0015 38.48 61.19 66.80 102.43 112.09 380.99 5 300 1.27065 0.00 37.15 60.33 66.15 94.39 258.03 5 300 0.86070 0.00 36.63 59.75 60.96 157.34 5 300 0.52475 0.00 36.28 55.06 91.34 5 300 0.30480 0.00 33.43 33.43 5 300 0.11185 0.00 0.00 5 300 0.00090


6) Compute the detention pond outflow limits for tc pre

Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow




38,356 38,356 38,356 912

( min ) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 24.78 0.0248 950.35 0.00 950.35 5 300 3.168

10 0.00 950.35 0.00 950.35 5 300 3.16815 0.00 950.35 0.00 950.35 5 300 3.16820 0.00 22.60 22.60 5 300 0.07525 0.00 0.00 5 300 0.00030


7.2 ) Cal. Inflow Hydrograph for 10 ARI, 10 min Rainfamin Rainfall Duration

38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 22.01 0.0220 844.04 0.00 844.04 5 300 2.813

10 17.73 0.0177 680.14 844.04 0.00 1,524.18 5 300 5.08115 0.00 680.14 844.04 0.00 1,524.18 5 300 5.08120 0.00 680.14 20.07 700.20 5 300 2.33425 0.00 16.17 16.17 5 300 0.05430 0.00 0.00 5 300 0.00035


7 ) Compute the detention pond inflow hydrograph for tc post

Time


)


)

A1 ( m2 ) A2 ( m2 ) A3 ( m2 ) A4 ( m2 ) Total Depth

( m3 )

Time Interval ( min

)

Time

Inflow


Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow




38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 14.57 0.0146 558.79 0.00 558.79 5 300 1.863

10 25.11 0.0251 963.00 558.79 0.00 1,521.79 5 300 5.07315 9.04 0.0090 346.68 963.00 558.79 0.00 1,868.47 5 300 6.22820 0.00 346.68 963.00 13.29 1,322.97 5 300 4.41025 0.00 346.68 22.90 369.58 5 300 1.23230 0.00 8.24 8.24 5 300 0.02735 0.00 0.00 5 300 0.00040



38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 8.93 0.0089 342.44 0.00 342.44 5 300 1.141

10 16.29 0.0163 624.96 342.44 0.00 967.40 5 300 3.22515 21.51 0.0215 824.95 624.96 342.44 0.00 1,792.34 5 300 5.97420 5.87 0.0059 224.99 824.95 624.96 8.14 1,683.03 5 300 5.61025 7.17 0.0072 274.98 224.99 824.95 14.86 1,339.77 5 300 4.46630 3.91 0.0039 149.99 274.98 224.99 19.62 669.57 5 300 2.23235 0.00 149.99 274.98 5.35 430.32 5 300 1.43440 0.00 149.99 6.54 156.53 5 300 0.52245 0.00 3.57 3.57 5 300 0.01250 0.00 0.00 5 300 0.000



Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow


Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow




38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 1.77 0.0018 67.93 0.00 67.93 5 300 0.226

10 5.87 0.0059 225.20 67.93 0.00 293.13 5 300 0.97715 14.09 0.0141 540.48 225.20 67.93 0.00 833.61 5 300 2.77920 10.07 0.0101 386.05 540.48 225.20 1.62 1,153.34 5 300 3.84425 19.46 0.0195 746.37 386.05 540.48 5.35 1,678.26 5 300 5.59430 8.47 0.0085 324.93 746.37 386.05 12.85 1,470.21 5 300 4.90135 7.46 0.0075 286.32 324.93 746.37 9.18 1,366.80 5 300 4.55640 4.78 0.0048 183.38 286.32 324.93 17.75 812.38 5 300 2.70845 4.03 0.0040 154.42 183.38 286.32 7.73 631.85 5 300 2.10650 2.60 0.0026 99.73 154.42 183.38 6.81 444.34 5 300 1.48155 2.35 0.0023 90.08 99.73 154.42 4.36 348.59 5 300 1.16260 1.43 0.0014 54.69 90.08 99.73 3.67 248.17 5 300 0.82765 0.00 54.69 90.08 2.37 147.14 5 300 0.49070 0.00 54.69 2.14 56.83 5 300 0.18975 0.00 1.30 1.30 5 300 0.00480 0.00 0.00 5 300 0.000



Time


)


)


( m3 )

Time Interval ( min

)

Time Inflow




38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 30.60 0.0306 1173.85 0.00 1,173.85 5 300 3.913

10 0.00 1173.85 0.00 1,173.85 5 300 3.91315 0.00 1173.85 0.00 1,173.85 5 300 3.91320 0.00 27.91 27.91 5 300 0.09325 0.00 0.00 5 300 0.000



38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 26.93 0.0269 1032.98 0.00 1,032.98 5 300 3.443

10 21.45 0.0214 822.67 1032.98 0.00 1,855.65 5 300 6.18515 0.00 822.67 1032.98 0.00 1,855.65 5 300 6.18520 0.00 822.67 24.56 847.23 5 300 2.82425 0.00 19.56 19.56 5 300 0.06530 0.00 0.00 5 300 0.000



Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow


Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow




38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 17.87 0.0179 685.59 0.00 685.59 5 300 2.285

10 30.27 0.0303 1161.13 685.59 0.00 1,846.72 5 300 6.15615 10.90 0.0109 418.01 1161.13 685.59 0.00 2,264.73 5 300 7.54920 0.00 418.01 1161.13 16.30 1,595.44 5 300 5.31825 0.00 418.01 27.61 445.62 5 300 1.48530 0.00 9.94 9.94 5 300 0.03335 0.00 0.00 5 300 0.00040



38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 11.03 0.0110 423.12 0.00 423.12 5 300 1.410

10 19.58 0.0196 751.01 423.12 0.00 1,174.13 5 300 3.91415 25.85 0.0258 991.34 751.01 423.12 0.00 2,165.47 5 300 7.21820 7.05 0.0070 270.37 991.34 751.01 10.06 2,022.78 5 300 6.74325 8.62 0.0086 330.45 270.37 991.34 17.86 1,610.01 5 300 5.36730 4.70 0.0047 180.24 330.45 270.37 23.57 804.63 5 300 2.68235 0.00 180.24 330.45 6.43 517.12 5 300 1.72440 0.00 180.24 7.86 188.10 5 300 0.62745 0.00 4.29 4.29 5 300 0.01450 0.00 0.00 5 300 0.000



Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow


Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow




38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 2.42 0.0024 92.86 0.00 92.86 5 300 0.310

10 7.04 0.0070 269.94 92.86 0.00 362.80 5 300 1.20915 16.89 0.0169 647.86 269.94 92.86 0.00 1,010.66 5 300 3.36920 12.06 0.0121 462.76 647.86 269.94 2.21 1,382.77 5 300 4.60925 23.33 0.0233 894.66 462.76 647.86 6.42 2,011.70 5 300 6.70630 10.15 0.0102 389.49 894.66 462.76 15.40 1,762.31 5 300 5.87435 8.95 0.0089 343.21 389.49 894.66 11.00 1,638.36 5 300 5.46140 5.73 0.0057 219.81 343.21 389.49 21.27 973.78 5 300 3.24645 4.83 0.0048 185.10 219.81 343.21 9.26 757.38 5 300 2.52550 3.12 0.0031 119.55 185.10 219.81 8.16 532.62 5 300 1.77555 2.82 0.0028 107.98 119.55 185.10 5.23 417.85 5 300 1.39360 1.71 0.0017 65.56 107.98 119.55 4.40 297.48 5 300 0.99265 0.00 65.56 107.98 2.84 176.38 5 300 0.58870 0.00 65.56 2.57 68.12 5 300 0.22775 0.00 1.56 1.56 5 300 0.00580 0.00 0.00 5 300 0.0008590



Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow




38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 34.53 0.0345 1324.26 0.00 1,324.26 5 300 4.414

10 0.00 1324.26 0.00 1,324.26 5 300 4.41415 0.00 1324.26 0.00 1,324.26 5 300 4.41420 0.00 31.49 31.49 5 300 0.10525 0.00 0.00 5 300 0.000



38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 30.02 0.0300 1151.33 0.00 1,151.33 5 300 3.838

10 23.78 0.0238 911.95 1151.33 0.00 2,063.29 5 300 6.87815 0.00 911.95 1151.33 0.00 2,063.29 5 300 6.87820 0.00 911.95 27.38 939.33 5 300 3.13125 0.00 21.68 21.68 5 300 0.07230 0.00 0.00 5 300 0.000



Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow


Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow




38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 19.89 0.0199 763.02 0.00 763.02 5 300 2.543

10 33.43 0.0334 1282.12 763.02 0.00 2,045.14 5 300 6.81715 12.03 0.0120 461.56 1282.12 763.02 0.00 2,506.70 5 300 8.35620 0.00 461.56 1282.12 18.14 1,761.82 5 300 5.87325 0.00 461.56 30.49 492.05 5 300 1.64030 0.00 10.97 10.97 5 300 0.03735 0.00 0.00 5 300 0.000



38,356 38,356 38,356 912

( min) ( sec )

0 0.00 0.0000 0.00 0.00 0 0 0.0005 12.28 0.0123 470.99 0.00 470.99 5 300 1.570

10 21.53 0.0215 825.81 470.99 0.00 1,296.80 5 300 4.32315 28.42 0.0284 1090.08 825.81 470.99 0.00 2,386.88 5 300 7.95620 7.75 0.0078 297.29 1090.08 825.81 11.20 2,224.38 5 300 7.41525 9.47 0.0095 363.36 297.29 1090.08 19.64 1,770.36 5 300 5.90130 5.17 0.0052 198.20 363.36 297.29 25.92 884.77 5 300 2.94935 0.00 198.20 363.36 7.07 568.62 5 300 1.89540 0.00 198.20 8.64 206.84 5 300 0.68945 0.00 4.71 4.71 5 300 0.01650 0.00 0.00 5 300 0.000



Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow


Time


)


)


( m3 )

Time Interval ( min

)

Time

Inflow



8 ) Summary of Pre and Post-Development Flow Hydrographs

Pre-Development Post-DevelopmentARI ( years )

10 50 100 10 50 100Storm Duration ( minutes )

60 5 10 15 30 60 5 10 15 30 60 5 10 15 30 60Flow ( cumecs )

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 05 0.000 0.000 0.026 3.168 2.813 1.863 1.141 0.226 3.913 3.443 2.285 1.410 0.310 4.414 3.838 2.543 1.570 0.358

10 0.000 0.066 0.137 3.168 5.081 5.073 3.225 0.977 3.913 6.185 6.156 3.914 1.209 4.414 6.878 6.817 4.323 1.34415 0.906 1.220 1.400 3.168 5.081 6.228 5.974 2.779 3.913 6.185 7.549 7.218 3.369 4.414 6.878 8.356 7.956 3.71120 1.564 2.005 2.260 0.075 2.334 4.410 5.610 3.844 0.093 2.824 5.318 6.743 4.609 0.105 3.131 5.873 7.415 5.05325 2.860 3.557 3.959 0 0.054 1.232 4.466 5.594 0 0.065 1.485 5.367 6.706 0 0.072 1.640 5.901 7.35030 3.376 4.171 4.606 0 0.027 2.232 4.901 0 0.033 2.682 5.874 0 0.037 2.949 6.43935 3.776 4.587 5.028 0 1.434 4.556 0 1.724 5.461 0 1.895 5.98640 3.228 3.869 4.241 0.522 2.708 0.627 3.246 0.689 3.55845 2.782 3.335 3.656 0.012 2.106 0.014 2.525 0.016 2.76750 1.741 2.087 2.288 0 1.481 0 1.775 0 1.94655 1.348 1.615 1.771 1.162 1.393 1.52760 0.967 1.159 1.270 0.827 0.992 1.08765 0.655 0.785 0.860 0.490 0.588 0.64470 0.399 0.478 0.524 0.189 0.227 0.24975 0.232 0.278 0.304 0.004 0.005 0.00680 0.085 0.102 0.111 0 0 085 0 0 090

15 MINS.

Time ( min )

CRITICAL STORM DURATION FOR POST-DEVELOPMENT, Q50 =

CHECK : Rational Method Hydrograph

C = 0.8 ( assumed average )

247.43 mm/hr

299.28 mm/hr

331.76 mm/hrA = 1.152 ha.

0.633

0.662

0.849

Qy = ( C x yIt x A ) ÷ 360

10I10 = (tc = 10)50I10 = (tc = 10)

100I10 = (tc = 10)

Q10 = m3/s

Q50 = m3/s

Q100 = m3/s


Volume = 5,611

Volume = 6,848

9) Graphs of 50 ARI Post-Development Inflow Hydrographs for estimation of detention pond size

m3

m3

0 5 10 15 20 250.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0

3.443

6.185 6.185

2.824

0.065

10 Min. 50 ARI Hydrograph

Time (min)

0 5 10 15 20 25 300.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0

2.285

6.156

7.549

5.318

1.485

0.033

15 MIn. 50 ARI Hydrograph

Time (min)

Infl

ow

(m

3/s

)In

flo

w (

m3

/s)


Volume = 8,910

Volume = 11,487


m3

m3

0 5 10 15 20 25 30 35 40 450.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0

1.410

3.914

7.2186.743

5.367

2.682

1.724

0.6270.014


0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 750.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 0.310

1.209

3.369

4.609

6.706

5.8745.461

3.2462.525

1.7751.393

0.9920.588

0.2270.005


Time (min)

Time (min)

Infl

ow

(m

3/s

)In

flo

w (

m3

/s)


Volume = 6,239

Volume = 7,580


m3

m3

0 5 10 15 20 250.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0

3.838

6.878 6.878

3.131

0.072

10 Min. 100 ARI Hydrograph

Time (min)

0 5 10 15 20 25 300.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0

2.543

6.817

8.356

5.873

1.640

0.037


Time (min)

Infl

ow

(m

3/s

)In

flo

w (

m3

/s)


Volume = 9,814

Volume = 12,608


m3

m3

0 5 10 15 20 25 30 35 40 450.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0

1.570

4.323

7.9567.415

5.901

2.949

1.895

0.6890.016


0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 750.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

00.358

1.344

3.711

5.053

7.350

6.4395.986

3.558

2.767

1.9461.527

1.0870.644

0.2490.006


Time (min)

Time (min)

Infl

ow

(m

3/s

)In

flo

w (

m3

/s)


11 ) Estimation of detention basin volume

11.1 ) Based on 50 ARI post-developed inflows

ParameterStorn Duration ( minutes )

10 15 30 60

5,611 6,848 8,910 11,487

6.185 7.549 7.218 6.706

4.587 4.587 4.587 4.587

( minutes ) 30 35 50 80

( minutes ) 15 15 15 25

0.351 0.451 0.368 0.336

1,968 3,087 3,282 3,864

Eq 20.13, Vol.7where,

estimated storage volume

inflow hydrograph runoff volume

inflow hydrograph peak flow rate

allowable peak outflow rate

time base of the inflow hydrograph

time to peak of the inflow hydrograph

Maximum pond depth within the basin should not exceed 3.0 m under normal operating conditions(See Section 20.5.2, Vol.7)

Vi ( m3 )

Qi ( m3/s )

Qo ( m3/s )

ti

tp

Vs/Vi

Preliminary Vs ( m3 )

Vs/Vi = 1.291x ( 1 - Qo/Qi )0.753x ( ti/tp )-0.411

Vs =

Vi =

Qi =

Qo =

ti =

tp =

From the above table, the basin volume is estimated for 3,864 m3 at time 60 minutes.


11 ) Estimation of detention basin volume

11.2 ) Based on 100 ARI post-developed inflows

ParameterStorn Duration ( minutes )

10 15 30 60

6,239 7,580 9,814 12,608

6.878 8.356 7.956 7.350

4.587 4.587 4.587 4.587

( minutes ) 30 35 50 80

( minutes ) 15 15 15 25

0.425 0.501 0.412 0.383

2,649 3,795 4,047 4,834

Eq 20.13, Vol.7where,

estimated storage volume

inflow hydrograph runoff volume

inflow hydrograph peak flow rate

allowable peak outflow rate

time base of the inflow hydrograph

time to peak of the inflow hydrograph

Maximum pond depth within the basin should not exceed 3.0 m under normal operating conditions(See Section 20.5.2, Vol.7)

The overall detention pond dimensions refer plan attached.

Depth = 2.000 mSide Slope = 4 (H) : 1 (V)

Volume = 4,963

Area = 3,406

Total Area = 5,064- area of the pond with 6.0 m width for maintenance around the pond

12) CONCLUSION

Pond area to be provided is

Pond area with 6.0 m width for maintenance around the pond to be provided is

Pond area required is

Vi ( m3 )

Qi ( m3/s )

Qo ( m3/s )

ti

tp

Vs/Vi

Preliminary Vs ( m3 )

Vs/Vi = 1.291x ( 1 - Qo/Qi )0.753x ( ti/tp )-0.411

Vs =

Vi =

Qi =

Qo =

ti =

tp =

From the above table, the basin volume is estimated for 4,834 m3 at time 60 minutes.

m3 > 4,834 m3 … O.K for 100 ARI post-development inflows.

m2 ( 0.842 acres ) - area of the the pond

m2 ( 1.25 acres )

= 3,406 m2 ( 0.842 acres )

= 5,064 m2 ( 1.25 acres )

= 5,099 m2 ( 1.26 acres )

11 ) Compute Stage - Storage Relationship

11.1 ) Preliminary Total Basin Stage-Storage Relationship

Stage, RL Depth, d Δd SS 2xSSxΔd Length Breadth Area Length Breadth Area Total Area

( m ) ( m ) ( m ) ( m/m ) ( m ) L1 ( m ) B1 ( m ) L2 ( m ) B2 ( m )

12.45 0.00 0.00 4 0.00 41.10 31.90 1311.09 41.10 31.90 1311.09 2,622.1812.35 0.10 0.10 4 0.80 41.90 32.70 1370.13 41.90 32.70 1370.13 2,740.2612.25 0.20 0.10 4 0.80 42.70 33.50 1430.45 42.70 33.50 1430.45 2,860.9012.15 0.30 0.10 4 0.80 43.50 34.30 1492.05 43.50 34.30 1492.05 2,984.1012.05 0.40 0.10 4 0.80 44.30 35.10 1554.93 44.30 35.10 1554.93 3,109.8611.95 0.50 0.10 4 0.80 45.10 35.90 1619.09 45.10 35.90 1619.09 3,238.1811.85 0.60 0.10 4 0.80 45.90 36.70 1684.53 45.90 36.70 1684.53 3,369.0611.75 0.70 0.10 4 0.80 46.70 37.50 1751.25 46.70 37.50 1751.25 3,502.5011.65 0.80 0.10 4 0.80 47.50 38.30 1819.25 47.50 38.30 1819.25 3,638.5011.55 0.90 0.10 4 0.80 48.30 39.10 1888.53 48.30 39.10 1888.53 3,777.0611.45 1.00 0.10 4 0.80 49.10 39.90 1959.09 49.10 39.90 1959.09 3,918.1811.35 1.10 0.10 4 0.80 49.90 40.70 2030.93 49.90 40.70 2030.93 4,061.8611.25 1.20 0.10 4 0.80 50.70 41.50 2104.05 50.70 41.50 2104.05 4,208.1011.15 1.30 0.10 4 0.80 51.50 42.30 2178.45 51.50 42.30 2178.45 4,356.9011.05 1.40 0.10 4 0.80 52.30 43.10 2254.13 52.30 43.10 2254.13 4,508.2610.95 1.50 0.10 4 0.80 53.10 43.90 2331.09 53.10 43.90 2331.09 4,662.1810.85 1.60 0.10 4 0.80 53.90 44.70 2409.33 53.90 44.70 2409.33 4,818.6610.75 1.70 0.10 4 0.80 54.70 45.50 2488.85 54.70 45.50 2488.85 4,977.7010.65 1.80 0.10 4 0.80 55.50 46.30 2569.65 55.50 46.30 2569.65 5,139.3010.55 1.90 0.10 4 0.80 56.30 47.10 2651.73 56.30 47.10 2651.73 5,303.4610.45 2.00 0.10 4 0.80 57.10 47.90 2735.09 57.10 47.90 2735.09 5,470.18

A1 ( m2 ) A2 ( m2 ) A ( m2 )

Average Storage Total Storage

0.00 0.00 0.002,681.22 268.12 268.122,800.58 280.06 548.182,922.50 292.25 840.433,046.98 304.70 1,145.133,174.02 317.40 1,462.533,303.62 330.36 1,792.893,435.78 343.58 2,136.473,570.50 357.05 2,493.523,707.78 370.78 2,864.303,847.62 384.76 3,249.063,990.02 399.00 3,648.064,134.98 413.50 4,061.564,282.50 428.25 4,489.814,432.58 443.26 4,933.074,585.22 458.52 5,391.594,740.42 474.04 5,865.634,898.18 489.82 6,355.455,058.50 505.85 6,861.305,221.38 522.14 7,383.445,386.82 538.68 7,922.12

Area( m2 ) ( m3 ) S ( m3 )


12 ) Compute Stage - Storage Relationship

12.1 ) Designed Basin Stage-Storage Relationship

Stage, RL Depth, d SS Length Breadth Area Length Breadth Area Total Area Average Storage Total Storage

( m ) ( m ) ( m ) ( m/m ) ( m ) L1 ( m ) B1 ( m ) L2 ( m ) B2 ( m )

10.45 0.00 0.00 0 0.00 47.80 25.10 1,199.78 20.80 21.30 443.04 1,642.82 0.00 0.00 0.0010.55 0.10 0.10 4 0.80 48.60 25.90 1,258.74 21.60 21.30 460.08 1,718.82 1,680.82 168.08 168.0810.65 0.20 0.10 4 0.80 49.40 26.70 1,318.98 22.40 21.30 477.12 1,796.10 1,757.46 175.75 343.8310.75 0.30 0.10 4 0.80 50.20 27.50 1,380.50 23.20 21.30 494.16 1,874.66 1,835.38 183.54 527.3710.85 0.40 0.10 4 0.80 51.00 28.30 1,443.30 24.00 21.30 511.20 1,954.50 1,914.58 191.46 718.8210.95 0.50 0.10 4 0.80 51.80 29.10 1,507.38 24.80 21.30 528.24 2,035.62 1,995.06 199.51 918.3311.05 0.60 0.10 4 0.80 52.60 29.90 1,572.74 25.60 21.30 545.28 2,118.02 2,076.82 207.68 1,126.0111.15 0.70 0.10 4 0.80 53.40 30.70 1,639.38 26.40 21.30 562.32 2,201.70 2,159.86 215.99 1,342.0011.25 0.80 0.10 4 0.80 54.20 31.50 1,707.30 27.20 21.30 579.36 2,286.66 2,244.18 224.42 1,566.4211.35 0.90 0.10 4 0.80 55.00 32.30 1,776.50 28.00 21.30 596.40 2,372.90 2,329.78 232.98 1,799.3911.45 1.00 0.10 4 0.80 55.80 33.10 1,846.98 28.80 21.30 613.44 2,460.42 2,416.66 241.67 2,041.0611.55 1.10 0.10 4 0.80 56.60 33.90 1,918.74 29.60 21.30 630.48 2,549.22 2,504.82 250.48 2,291.5411.65 1.20 0.10 4 0.80 57.40 34.70 1,991.78 30.40 21.30 647.52 2,639.30 2,594.26 259.43 2,550.9711.75 1.30 0.10 4 0.80 58.20 35.50 2,066.10 31.20 21.30 664.56 2,730.66 2,684.98 268.50 2,819.4711.85 1.40 0.10 4 0.80 59.00 36.30 2,141.70 32.00 21.30 681.60 2,823.30 2,776.98 277.70 3,097.1611.95 1.50 0.10 4 0.80 59.80 37.10 2,218.58 32.80 21.30 698.64 2,917.22 2,870.26 287.03 3,384.1912.05 1.60 0.10 4 0.80 60.60 37.90 2,296.74 33.60 21.30 715.68 3,012.42 2,964.82 296.48 3,680.6712.15 1.70 0.10 4 0.80 61.40 38.70 2,376.18 34.40 21.30 732.72 3,108.90 3,060.66 306.07 3,986.7412.25 1.80 0.10 4 0.80 62.20 39.50 2,456.90 35.20 21.30 749.76 3,206.66 3,157.78 315.78 4,302.5212.35 1.90 0.10 4 0.80 63.00 40.30 2,538.90 36.00 21.30 766.80 3,305.70 3,256.18 325.62 4,628.1312.45 2.00 0.10 4 0.80 63.80 41.10 2,622.18 36.80 21.30 783.84 3,406.02 3,355.86 335.59 4,963.72

Δd 2xSSxΔd

A1 ( m2 ) A2 ( m2 ) A ( m2 ) Area( m2 ) ( m3 ) S ( m3 )

48


13 ) Size the minor and major design storm primary outlet

13.1 ) Estimate size of primary outlets

From pre-development inflow hydrograph,

3.776

From pre-development inflow hydrograph,

4.587

Q = Eq 20.2, Volume 7, Chap.20

where,

Q =C = discharge coefficient ( 0.40 - 0.62)

effective head on the orifice measured from centre of opening, m

0.375 m

2.245

1.691 m

Trials Ø ( mm ) Nos.2nd Primary, Top RowIst Primary, Bottom Row 600 2 0.565

Total 2 0.565

Maximum basin outflow for Q10 = m3/s

Maximum basin outflow for Q50= m3/s

C.Ao.√ (2.g.Ho)

orifice discharge, m3/s

Ao = orifice x-sectional area, m2 ( πDo2/4 )

Do = orifice Ø, m

Ho =

Ho =

Ao = Q10 ÷ {C. (2.g.Ho)0.5}

Ao = 3.776 ÷ {0.62 x (2 x 9.81 x 0.375)0.5}

Ao = m2

Do =

Area( m2 )

49


13.2 ) Size the minor and major design storm primary outlet

12.45 Crest-Level of Spillway

Freeboard, 300 mm

10.45 Bed Level of Detention Pond / Soffit Level of 1st Primary Outlet

2 Nos. 750 mm Pipe

11.90 : Q10

12.13 12.23 : Q50

12.38 : Q100

1800mm


13.3 ) Trials for selecting acceptable combinations of primary outlets

( MAX. POND DEPTH NOT GREATER THAN 3 m. UNDER MAX. DESIGN STORM ARI -20.5.2, VOL. 7 )

Tria

ls

Pipe CombinationsPipe Size & Soffit 10 ARI 50 ARI Total 100 ARI

Area Storage Level Outflow Stage Stage Diff. Outflow Stage Stage Diff. Height RL

110.45 10.45

2 No. 750 mm 0.884 4,963.72 10.45 2.921 3.776 11.90 1.45 3.233 4.587 12.23 1.78 3.23 12.38

210.45 10.45

2 Nos 600mm 0.565 0.00 10.45 3.776 4.587

3

4

5

6

7

8

9

10

11

12

Q10 Limit Q50 Limit


13.3 ) Trials for selecting acceptable combinations of primary outlets

( MAX. POND DEPTH NOT GREATER THAN 3 m. UNDER MAX. DESIGN STORM ARI -20.5.2, VOL. 7 )

Tria

ls

Pipe CombinationsPipe Size & Soffit 10 ARI 50 ARI Total 100 ARI

Area Storage Level Outflow Stage Stage Diff. Outflow Stage Stage Diff. Height RL

110.45 10.45

2 No. 750 mm 0.884 4,963.72 10.45 2.921 3.776 11.90 1.45 3.233 4.587 12.23 1.78 3.23 12.38

2

3

4

5

6

7

8

9

10

11

12

Q10 Limit Q50 Limit


14 ) Compute stage - discharge relationship using oriffice equation for primary outlets

Stage, RL 1st Primary Nos. Ø ( mm )

Q1

2nd Primary Nos. Ø ( mm )

Q2

Total Discharge( m ) Bottom, Q1 2 750 Top, Q2 - - Q ( Q1+Q2 )

10.45 0.00 2.427 0.000 0.000 0.00010.55 0.10 2.427 0.316 0.767 0.76710.65 0.20 2.427 0.447 1.085 1.08510.75 0.30 2.427 0.548 1.329 1.32910.85 0.40 2.427 0.632 1.535 1.53510.95 0.50 2.427 0.707 1.716 1.71611.05 0.60 2.427 0.775 1.880 1.88011.15 0.70 2.427 0.837 2.030 2.03011.25 0.80 2.427 0.894 2.170 2.17011.35 0.90 2.427 0.949 2.302 2.30211.45 1.00 2.427 1.000 2.427 2.42711.55 1.10 2.427 1.049 2.545 2.54511.65 1.20 2.427 1.095 2.658 2.65811.75 1.30 2.427 1.140 2.767 2.76711.85 1.40 2.427 1.183 2.871 2.87111.95 1.50 2.427 1.225 2.972 2.97212.05 1.60 2.427 1.265 3.069 3.06912.15 1.70 2.427 1.304 3.164 3.164

Ho C.Ao. (2.g)0.5 Ho0.5 Ho C.Ao.(2.g)0.5 Ho

0.5 ( m3/s )

Q = Eq 19.6, Vol 7

where,

Q =

difference in water levels of pond and outlet drain

effective head ( m )S = pipe longitudinal slope ( m/m )L = pipe length ( m )

sum of loss factors for the pipe system

Eq 19.7, Vol 7where,

trash screen loss factor

entrance loss factor

friction loss factor

bend loss factor

outlet loss factor

Outlet pipe slope = 3% %Pipe length = 8.6 m

Ap x √ { 2g x Ho )

Ho = H /KL = ( K t + K e + K f + K o ) x V2/2g

pipe capacity ( m3/s )

A p = cross-sectional area of pipe ( m2 ) H =

Ho =

K L=

KL = K t + K e + K f + K b + K o

K t =

K e =

K f =

K b =

K o =


A g =

For the trash rack,

0.75

0.55


orifice discharge coefficient = 0.62

1.60

K t = 1.45 − 0.45 { A n / A g } − { A n / A g }2

A n = net open area between the screen bars ( m2 )

gross area of the screen and supports ( m2 )

A n / A g =

K t =

K e = 1/Cd2 − 1

Cd =

K e =

▼4.10H

Ho

Hydraulic Grade Line

8.6 m

5 m

▼3.90

▼4.80

f x L/D Eq 19.10, Vol 7where,

f = Darcy-Weisbach friction loss coefficientD = pipe diameter ( m )

f = Eq 19.11, Vol 7where,

n = Manning's n = 0.011

0.50

( per pipe )

L H Q V

( m ) ( m/s )

#REF! 0.55 1.60 0.50 8.60 #REF! #REF! 1.10 #REF! #REF! #REF!

For 4 pipes, Q = #REF!

CONCLUSION : 1) Loss only minus 2.3 %2) Loss in terms of pipe length is only about minus 2.7 % for up to 20 m

K f =

125 x n2/D1/3

K f = 125 x 0.0112 x L/ D4/3

K o =

A p K t K e K o K f K L Ho

( m2 ) ( = H/KL ) ( m3/s )

52


15 ) Develop storage - outflow function

Stage, RL Depth Discharge Discharge Storage

( m ) H ( m ) ( min ) ( sec )

10.45 0.00 0.000 0.000 0.00 5 300 0.000 0.00010.55 0.10 0.767 0.767 168.08 5 300 1.888 1.88810.65 0.20 1.085 1.085 175.75 5 300 2.257 2.25710.75 0.30 1.329 1.329 183.54 5 300 2.553 2.55310.85 0.40 1.535 1.535 191.46 5 300 2.811 2.81110.95 0.50 1.716 1.716 199.51 5 300 3.046 3.04611.05 0.60 1.880 1.880 207.68 5 300 3.264 3.26411.15 0.70 2.030 2.030 215.99 5 300 3.470 3.47011.25 0.80 2.170 2.170 224.42 5 300 3.666 3.66611.35 0.90 2.302 2.302 232.98 5 300 3.855 3.85511.45 1.00 2.427 2.427 241.67 5 300 4.038 4.03811.55 1.10 2.545 2.545 250.48 5 300 4.215 4.21511.65 1.20 2.658 2.658 259.43 5 300 4.388 4.38811.75 1.30 2.767 2.767 268.50 5 300 4.557 4.55711.85 1.40 2.871 2.871 277.70 5 300 4.722 4.72211.95 1.50 2.972 2.972 287.03 5 300 4.885 4.88512.05 1.60 3.069 3.069 296.48 5 300 5.046 5.04612.15 1.70 3.164 3.164 306.07 5 300 5.204 5.204

Δt (2S/Δt)+Q1 (2S/Δt)+Q

Q1 ( m3/s ) Q ( m3/s ) S (m3 ) ( m3/s ) ( m3/s )

14.1 ) Graphs

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

Storage - Outflow Relationship

Ou

tflo

w(

m3/

s )

2S/Δt + Q, m3/s

10.4

5

10.5

5

10.6

5

10.7

5

10.8

5

10.9

5

11.0

5

11.1

5

11.2

5

11.3

5

11.4

5

11.5

5

11.6

5

11.7

5

11.8

5

11.9

5

12.0

5

12.1

5

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500


16 ) Inflow Hydrograph Routing for Primary Outlets

16.1) Route the 10 ARI 30 min. post-developed inflow hydrograph through the 1st primary outlet

Time, t Inflow, I Outflow Water Level Stage, RL Depth Discharge,Q Storage,S (2S /Δt)+Q

( mins ) ( m ) ( m ) ( m )

0 0 0 0 0 10.45 10.45 0.00 0.000 0.00 0.0005 1.141 1.141 0.214 1.141 0.464 10.51 10.55 0.10 0.767 168.08 1.888

10 3.225 4.366 2.010 4.580 1.285 10.73 10.65 0.20 1.085 343.83 3.37715 5.974 9.199 7.109 11.209 2.050 11.16 10.75 0.30 1.329 527.37 4.84520 5.610 11.585 13.496 18.693 2.598 11.60 10.85 0.40 1.535 718.82 6.32725 4.466 10.076 17.825 23.572 2.874 11.85 10.95 0.50 1.716 918.33 7.83830 2.232 6.698 18.680 24.523 2.921 11.90 11.05 0.60 1.880 1,126.01 9.38635 1.434 3.666 16.729 22.346 2.808 11.79 11.15 0.70 2.030 1,342.00 10.97740 0.522 1.956 13.490 18.686 2.598 11.60 11.25 0.80 2.170 1,566.42 12.61345 0.012 0.534 9.462 14.023 2.281 11.33 11.35 0.90 2.302 1,799.39 14.29850 0.000 0.012 5.698 9.474 1.888 11.06 11.45 1.00 2.427 2,041.06 16.03455 0.000 2.803 5.698 1.447 10.81 11.55 1.10 2.545 2,291.54 17.82260 0.878 2.803 0.963 10.61 11.65 1.20 2.658 2,550.97 19.66565 0.164 0.878 0.357 10.50 11.75 1.30 2.767 2,819.47 21.56370 0.031 0.164 0.067 10.46 11.85 1.40 2.871 3,097.16 23.51975 0.006 0.031 0.012 10.45 11.95 1.50 2.972 3,384.19 25.53380 0.001 0.006 0.002 10.45 12.05 1.60 3.069 3,680.67 27.60785 0.000 0.001 0.000 12.15 1.70 3.164 3,986.74 29.742

Peak outlow for 10 year ARI post-developed = 2.921 @ RL = 11.90

10 year ARI pre-developed outflow limit = 3.776 OK

Ij + Ij+1 (2Sj /Δt)-Qj (2Sj+1 /Δt)+Qj+1

( m3/s ) ( m3/s ) ( m3/s ) ( m3/s ) ( m3/s ) ( m3/s ) ( m3 ) ( m3/s )

m3/s

m3/s


16 ) Inflow Hydrograph Routing for Primary Outlets

16.2 ) Route the 50 ARI 30 min. post-developed inflow hydrograph through the 2nd primary outlet

Time, t Inflow, I Outflow Stage, RL Stage, RL Depth Discharge,Q Storage,S (2S /Δt)+Q

( mins ) ( m ) ( m ) ( m )

0 0.000 0.000 0.000 0.000 0.000 10.45 10.45 0.00 0.000 0.00 0.0005 1.410 1.410 0.264 1.410 0.573 10.52 10.55 0.10 0.767 168.08 1.888

10 3.914 5.324 2.724 5.588 1.432 10.80 10.65 0.20 1.085 343.83 3.37715 7.218 11.132 9.321 13.856 2.267 11.32 10.75 0.30 1.329 527.37 4.84520 6.743 13.961 17.565 23.282 2.858 11.84 10.85 0.40 1.535 718.82 6.32725 5.367 12.109 23.353 29.674 3.161 12.15 10.95 0.50 1.716 918.33 7.83830 2.682 8.049 24.935 31.401 3.233 12.23 11.05 0.60 1.880 1,126.01 9.38635 1.724 4.406 23.049 29.341 3.146 12.13 11.15 0.70 2.030 1,342.00 10.97740 0.627 2.351 19.469 25.400 2.965 11.94 11.25 0.80 2.170 1,566.42 12.61345 0.014 0.641 14.743 20.111 2.684 11.67 11.35 0.90 2.302 1,799.39 14.29850 0.000 0.014 10.088 14.758 2.335 11.38 11.45 1.00 2.427 2,041.06 16.03455 0.000 6.196 10.088 1.946 11.09 11.55 1.10 2.545 2,291.54 17.82260 3.163 6.196 1.516 10.84 11.65 1.20 2.658 2,550.97 19.66565 1.084 3.163 1.039 10.64 11.75 1.30 2.767 2,819.47 21.56370 0.203 1.084 0.441 10.51 11.85 1.40 2.871 3,097.16 23.51975 0.038 0.203 0.082 10.46 11.95 1.50 2.972 3,384.19 25.53380 0.007 0.038 0.015 10.45 12.05 1.60 3.069 3,680.67 27.607

0.001 0.007 0.003 10.45 12.15 1.70 3.164 3,986.74 29.742

Peak outflow for 50 year ARI post-developed = 3.233 @ RL = 12.23




m3/s

m3/s

55


17 ) Compute Stage - Discharge Relationship for Secondary Outlet ( Emergency Spillway, ES )

Adopt a freeboard height of 300 mm for weir

Stage, RL Q Combined Eq. 20.6, Volume 7

( m ) B H Discharge

( m ) ( m ) ( m )

10.45 0.000 0.00010.55 0.767 0.76710.65 1.085 1.08510.75 1.329 1.32910.85 1.535 1.53510.95 1.716 1.71611.05 1.880 1.88011.15 2.030 2.03011.25 2.170 2.17011.35 2.302 2.30211.45 2.427 2.42711.55 2.545 2.54511.65 2.658 2.65811.75 2.767 2.76711.85 2.871 2.87111.95 2.972 2.97212.05 3.069 3.06912.15 1.8 0.00 0.000 1.48 0.000 3.164 3.16412.25 1.8 0.10 0.032 1.48 0.084 3.256 3.34012.35 1.8 0.20 0.089 1.48 0.238 3.345 3.58312.45 1.8 0.30 0.164 1.48 0.438 3.432 3.869

Broad-Crested Weir, Q = CBCWBH1.5

H1.5 CBCW QES ( m3/s )

( m3/s ) ( m3/s )


18 ) Inflow Hydrograph Routing for Secondary Outlet ( Emergency Spillway )

Route the 100 ARI 30 min. post-developed inflow hydrograph through the 2nd primary outlet

Time, t Inflow, I Outflow Stage, RL Stage, RL Depth Discharge,Q Storage,S (2S /Δt)+Q

( mins ) ( m ) ( m ) ( m )

0 0.000 0.000 0.000 0.000 0.000 10.45 10.45 0.00 0.000 0.00 0.0005 1.570 1.570 0.294 1.570 0.638 10.53 10.55 0.10 0.767 168.08 1.888

10 4.323 5.893 3.156 6.186 1.515 10.84 10.65 0.20 1.085 343.83 3.37715 7.956 12.279 10.668 15.435 2.384 11.42 10.75 0.30 1.329 527.37 4.84520 7.415 15.371 20.047 26.039 2.996 11.97 10.85 0.40 1.535 718.82 6.32725 5.901 13.316 26.414 33.363 3.475 12.31 10.95 0.50 1.716 918.33 7.83830 2.949 8.850 27.910 35.264 3.677 12.38 11.05 0.60 1.880 1,126.01 9.38635 1.895 4.845 25.928 32.755 3.414 12.28 11.15 0.70 2.030 1,342.00 10.97740 0.689 2.585 22.294 28.513 3.109 12.09 11.25 0.80 2.170 1,566.42 12.61345 0.016 0.705 17.313 22.999 2.843 11.82 11.35 0.90 2.302 1,799.39 14.29850 0.000 0.016 12.304 17.328 2.512 11.52 11.45 1.00 2.427 2,041.06 16.03455 0.000 8.016 12.304 2.144 11.23 11.55 1.10 2.545 2,291.54 17.82260 4.547 8.016 1.735 10.96 11.65 1.20 2.658 2,550.97 19.66565 1.988 4.547 1.280 10.73 11.75 1.30 2.767 2,819.47 21.56370 0.410 1.988 0.789 10.56 11.85 1.40 2.871 3,097.16 23.51975 0.077 0.410 0.167 10.47 11.95 1.50 2.972 3,384.19 25.53380 0.014 0.077 0.031 10.45 12.05 1.60 3.069 3,680.67 27.60785 0.003 0.014 0.006 10.45 12.15 1.70 3.164 3,986.74 29.74290 0.003 0.003 0.000 12.25 1.80 3.340 4,302.52 32.02395 12.35 1.90 3.583 4,628.13 34.437

100 12.45 2.00 3.869 4,963.72 36.961105

Peak outflow for 100 year ARI post-developed = 3.677 @ RL = 12.38




m3/s

m3/s

72REFERENCE

Volume 4, 5, 7 & 101. Urban Stormwater Management Manual For Malaysia (MASMA 2000), JPS Malaysia,


20 ) SUMMARY OF DETENTION POND DESIGN CALCULATION

unitCATCHMENT DETAIL

Catchment Area, A = 12.141 ha.

PRE-DEVELOPMENT

Eq.14.6, Vol.5Length of flow path from catchment, L = 0.810 km

Slope, S = 6.423 m/km

40 min.

60 min.

83.88 mm/hr

100.54 mm/hr

3.776

4.587

POST DEVELOPMENT

Eq.14.1, Vol.5

12.192 mn = 0.015

Slope, S = 3.25 %

2.05 min

Eq.14.5, Vol 5

809.55 mVelocity of flow, V = 1.00 m/s

13.49 min

16 min

30 min.

156.64 mm/hr

172.24 mm/hr

7.549

8.3557

SIZING OF DETENTION POND

3,864

4,834Pond depth, y = 2.000 m

Side Slopes, S = 4(H) : 1(V)

Bottom area of the pond, A1 = 1,643

Top area of the pond, A2 = 3,406

5,064

Pond's area to be provided = 5,064Pond's area to be provided in acres = 1.25 acres

Pond area required = 1.26 acresType of primary outlet pipe and size 750mm dia. R.C. Pipe

No. of outlet 2

tc = 92.5 x L / (A1/10 x S 1/5)

Time of Concentration, tc =

Use Time of Concentration, tc =

Rainfall Intensity for 10 ARI, 50I60 =


Maximum inflow for 10 ARI, Q10 = m3/s


to = (107 x n x L1/3) / (S1/2)

Length of Road, Lo =

to =

td = Ld / V

Length of drain, Ld =

Duration of drain flow, td =

tc = to + td

Time of concentration, tc =

Use Time of Concentration, tc =





Estimated Storage Volume for 50 ARI, Vs = m3

Estimated Storage Volume for 100 ARI, Vs = m3

m2

m2

Pond area with 6.0 m width for maintenance around the pond area to be provided = m2

m2

detention pond design using masma

Documents

normal operating

selecting

ij ij1

effective

temporal pattern

internal main

loss er interval

inflow hydrograph