hydraulic design - scan doc.docx

8/14/2019 Hydraulic Design - Scan Doc.docx

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3.4.2 Hydraulic Design

Once the peak flows were estimated, the drain conveyance capacities were determined through a

hydraulic design. Manning's formula and continuity equation was used for various trial sections to

obtain the optimum slope and the section of the drain. The dimensions were practically fixed to

suit the site conditions.

The formulas are given as follows:

Continuity equation: Q* = A.V Where A = Cross sectional area of flow m

Q'= Actual Discharge (cumecs) V

= Velocity of Flow (mis)

Manning's Equation: V

=

Where R = Hydraulic Mean Depth

(m) V= Flow velocity m/s S =

Channel slope

Where A= Cross sectional area of flow m

P = Wetted perimeter (m)

Culvert channel designs were performed by selecting trial sections assuming a free board of

0.5m and calculating the actual discharge Q' and comparing it with the peak flow Q obtained

in the hydrologic design. For a satisfactory performance of the culvert Q' > Q i.e. the drain

should have a capacity to carry a flow equal or more than the peak flow also the velocity of

the flow should preferably less than 2.0 m/sec.

3.4.3 Use of "Flow Master "and "Culvert Master" Software

For the opening size computation "Flow Master "and "Culvert Master" software were also

employed.

3.4.4 Specimen calculations

Manual calculation and software calculation for Culvrt at chainage 27+308 km are given below Culvrt at

chainage 27+308 km was located at U/S of tributary of Maha oya.

Existing Slope of the stream Highway crossing chainage at 27+308 km

n

R= A


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Total catchment

Length of the longest watercourse

Existing slope of the catchment

Corresponding velocity of catchment

(According to table 3.1)

Time of concentration

(Ponrajah's Formula)

Return period

Rainfall intensity

(By Ranathunga's formula)

= 50 Years

I = 7895 (T+49.4) --8BB1

= 127.54 mm/hr

Corresponding Run off coefficient = 0.40

(Reffering Ponrajah's table and "Applied Hydrology by Ven Te Chow")

Q=CIA/360

Q=8.13m3/s

Assuming 1m water depth according to site condition,

Using Maning's Formula Design section can be calculated.

Full suply depth (FSD) =1 m

Design discharge (Q) =8.13 m3/s

Design s!ope(S) such that velocity along

Cuvert less than 2.0m/sec =0.001

Manning's formla corresponding to concrete (n) =0.013

Q = 1R2/3S1/2A

= 1A5/3

S1/2

\ A2/3

n

v> Q = 1fBWxFSDf/3S1/2

1' (BW+2FSD)2/3n

Solving above equation, BW,= 4.31m


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Taking BW = 4.5m

Taking Free board as 0.5m, Design section = 4,5m x 1.5m

Qmax for design section = 8.57 m3/s

Qdesign =8.13m3/s

Hence design section is ok for maximum discharge for 50 years return period.

Specimen calculation for design section of culvert is same as Design section of Bridge,

BW Calculation for 27+308 Culvert Worksheet for Rectangular Channel

Project Description

Project File c:\haestad\academic\fmw\ckah cor.fm2

Worksheet 27+308

Flow Element Rectangular Channel

Method Manning's Formula

Solve For Channel Depth

input Data

Mannings Coefficient 0.01 3

Channel Slope 0.001 000 m/m

Bottom Width 4.31 m

Discharge 8.13 m /s

Results

Depth 1.00 m

Flow Area 4.31 m2

Wetted Perimeter 6.31 m

Top Width 4.31 m

Critical Depth 0.71 m

Critical Slope 0.002716 m/m

Velocity 1.89 ' m/s

Velocity Head 0.18 m

Specific Energy 1.18 m '*

Froude Number 0.60 ^ "


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Flow is subcritical.

4.0Drainage Opening Sizes for Culverts and Bridges and Recommended High Flood Level

4.1 Drainage Opening Sizes for Culverts and Bridges along the Expressway

Drainage opening sizes for culverts and bridges were decided using Rational Formula and Manning's Formula

assuming a critical water depth required to pass a 50 years flood. The required opening sizes are given in

Table 4.1 and the relevant hydrologic and hydraulic calculations are given in Annex (B.1) Table 4,1 -

Recommended Drainage Opening sizes for Culverts and Bridges along the Expressway

Culvert

no.

Culvert ID

(Chainage)

Design size Invert up

stream (m

MSL)

Invert down

stream (m

MSL)

Approxima

te Length

(m)

Remarks

79 25+245 10.00mx2.00m 24.00 23.97 41.3

80 25+367 1.50mx1.50m 25.02 24.95 34.9

81 25+565 6.25mx1.50m 25.11 25.07 35.8

82 25+947 6.50mx1.50m 27.62 27.57 43.9

83 26+180 2.00mx1.50m 28.10 28.05 45.2

84 26+550 3.00mx1.50m 34.60 34.55 48.085 27+308 4.50mx1.50m 35.20 35.13 68.2

86 27+481 1.50mx1.50m 35.00 34.95 50.0

87 27+948 4.00mx1.50m 32.58 32.54 39.8

88 28+400 I.75mx1.50m 33.12 33.05 60.7

89 28+500 1.75mx1.50m 33:50 33.43 61.5

90 28+885 2.25mx1.50m 36.50 36.44 36.9

91 29+520 4.25mx1.50m 37.04 36.97 69.1

92 30+036 2.50mx1.50m 38.12 38.05 41.2

93 30+330 2.50mx1.50m 44.09 44.01 47.0,

94 31+156 3.50mx1.50m 35.52 35.45 62.6

95 31+240 3.50mx1.50m 35.50 35.43 68.8

96 31+923 1.50mx1.50m 35.07 35.05 43.6

97 32+000 3. 25m x1. 50m 34.60 34.58 36.0

98 32+088 1.50mx1.50m 34.60 34.58 43.0

99 32+235 1.75mx1.50m 36.02 36.00 46.4

100 32+665 10.00mx2.00m 37.02 36.98 70.3

101 32+985 8.50mx2.00m 36.32 36.29 42.0

102 33+390 1.50mx1.50m 39.10 39.03 44.5

103 33+500 1.50mx1.50m 42.58 42.51 41.3

104 33+858 2.75mx1.50m 42.07 42.05 33.0


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105 33+936 6.75mx1.50m 41.13 41.11 37.1

106 34+913 3.50mx2.50m 48.69 48.63 54.2 Dual Purpose

107 35+358 4.25mx1.50m 36.03 35.99 46.7

108 35+410 4.50mx1.50m35.80 35.76 45.6

109 35+460 4.25mx1.50m 35.90 35.86 44.2

Culvert

no.

Culvert ID

(Chainage)

Design size Invert up

stream (m

MSL)

Invert down

stream (m

MSL)

Approxima

te

Length(m)

Remarks

110 35+615 4.00mx1.50m 36.02 35.98 39.4

111 35+730 4.00mx1.50m 36.50 36.45 43.2

112 36+323 2.25mx1.50m 38.94 38.89 43.4

113 36+385 2.25mx1.5Qm 38.14 37.97 57.5

4 36+555 85m opening should be provided for Meerigama-Pasyala Rd and Railway Track

114 36+608 1 .50mx1 .50m 40.36 40.25 111.0

115 36+853 1 .50mx1 .50m 50.28 50.21 74.0

116 37+250 2.00mx1.50m 66.69 66.64 49.5

117 37+522 4.25mx1 .50m 58.65 58.59 57.6

118 37+893 9.00mx1.50m 48.45 48.37 88.6

119 38+001 9.00mx1.50m 48.45 48.39 62.7

120 38+400 2.00mx1.50m 58.94 58.89 46.5

121 38+676 3.25mx1.50m 59.51 59.46 57.2

122 38+943 3.00mx1.50m 64.30 64.26 39.7

123 39+195 3.75mx1.50m 53.46 53.39 72.4

124 40+065 i r-2.50mx1.50m 91.38 91.31 74.3125 40+630 3.50mx1.50m 76.70 76.66 35.6

126 40+815 3.50mx1.50m 57.98 57.92 59.2

127 40+900 1 .75mx1 .50m 54.90 54.82 70.9

128 41+070 2.00mx1.50m 57.75 57.71 44.8

129 41+445 13.50mx2.00m 51.28 51.26 51.4

130 41+565 20.00mx2.00m 48.86 48.83 68.6

131 41+930 3.75mx1.50m 66.16. 65.91 84.5

132 42+580 3.50mx1 .50m 103.84 103.78 54.2

133 42+925 3.00mx1.50m 91.76 91.71 51.9

134 43+545 9.00mx1.50m 56.52 56.47 67.8

135 43+840 3.25mx1 .50m 53.21 53.17 48.2 '

136 43+980 2.25mx1.50m 55.45 55.39 52.1

137 44+120 2.75mx1.50m 56.13 56.08 53.9

138 44+250 4.25mx1.50m 51.85 51.79 70.3

139 44+490 1 .50mx1 .50m 54.07 54.01 55.4

140 44+673 2.00mx1.50m 56.01 55.95 62.4

141 45+135 2.00mx1.50m 84.01 83.95 57.2

142 45+666 1 .50mx1 .50m 80.76 80.66 95.3

143 46+032 1.75mx1.50m 83.95 83.86 85.9

144 46+476 2.00mx1.50m 83.63 83.55 81.9


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145 46+892 1 .50mx1 .50m 67.70 67.45 82.7

146 47+451 9.00mx1.50m 56.82 56.75 62.0

147 47+557 7.00mx1.50m 56.61 56.55 69.7

148 47+928 4.50mx1 .50m 66.68 66.61 57.9

5 48+174 32.00mx4.50m 49.84 49.64 103.0

Note: Design sizes up to Culvert No.78 has submitted to RDA in CKAH chainage from 0+000 km to 25+000 km

4.2 Recommended High Flood Level along the Expressway

The recommended High Flood Level for design purposes of the expressway are given below

Table 4.2-Recommmended High Flood Levels of the Culverts across the Expressway

Culvert ID

(Chainage)

Size of Proposed

Structure

Existing Level

(m MSL)

Full Suplly Depth

(m)

Recommended

Flood Level (m

MSL)

25+245 10.00mx2.00m 24.00 1.50 25.50

25+367 1.50mx1.50m 25.02 1.00 26.02

25+565 6.25mx1.50m 25.11 1.00 26.11

25+947 6.50mx1.50m 27.62 1.00 28.62

26+180 2.00mx1.50m 28.10 1.00 29.10

26+550 3.00mx1.50m 34.60 1.00 35.60

27+308 4.50mx1.50m 35.20 1.00 36.20

27+481 1.50mx1.50m 35.00 1.00 36.00

27+948 4.00mx1.50m 32.58 1.00 33.58

28+400 1.75mx1.50m 33.12 1.00 34.12

28+500 1.75mx1.50m 33.50 1.00 34.5028+885 2.25mx1 .50m 36.50 1.00 37.50

29+520 4.25mx1.50m 37.04 1.00 38.04

30+036 2.50mx1.50m 38.12 1.00 39.12

30+330 2.50mx1.50m 44.09 1.00 45.09

31+156 3.50mx1.50m 35.52 1.00 36.52

31+240 3.50mx1.50mv 35.50 1.00 36.50

31+923 1.50mx1.50m 35.07 1.00 36.07

32+000 3.25mx1.50m 34.60 1.00 35.60

32+088 1.50mx1.50m 34.60 1.00 35.60

32+235 1.75mx1.50m 36.02 1.00 37.02

32+665 10.00mx2.00m 37.02 1.50 38.52

32+985 8.50mx2.00m 36.32 1.50 37.82

33+390 1.50mx1.50m 39.10 1.00 40.10

33+500 1.50mx1.50m 42.58 1.00 43.58

33+858 2.75mx1 .50m 42.07 1.00 43.07

33+936 6.75mx1.50m 41.13 1.00 42.13

34+913 3.50mx2.50m 48.69 1.00 49.69

35+358 4.25mx1.50m 36.03 1.00 37.03

35+410 4.50mx1.50m 35.80 1.00 36.80


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35+460 4.25mx1.50m 35.90 1.00 36.90

35+615 4.00mx1.50m 36.02 1.00 37.02

Culvert ID

(Chainage)

Size of Proposed

Structure

Existing Level

(m MSL)

Full Suplly

Depth (m)

Recommended

Flood Level (mMSL)

35+730 4.00mx1.50m 36.50 1.00 37.50

36+323 2.25mx1.50m 38.94 1.00 39.94

36+385 2.25mx1.50m 38.14 1.00 39.14

36+555 85m opening should be provided for Meerigama-Pasyala Rd and Railway Track

36+608 1.50mx1.50m 40.36 1.00 41.36

36+853 1.50mx1.50m 50.28 1.00 51.28

37+250 2.00mx1.50m 66.69 1.00 67.69

37+522 4.25mx1.50m 58.65 1.00 59.65

37+893 9.00mx1.50m 48.45 1.00 49.45

38+001 9.00mx1.50m 48.45 1.00 49.45

38+400 2.00mx1.50m 58.94 1.00 59.94

38+676 3.25mx1.50m 59.51 1.00 60.51

38+943 3.00mx1.50m 64.30 1.00 65.30

39+195 3.75mx1.50m 53.46 1.00 54.46

40+065 2.50mx1.50m 91.38 1.00 92.38

40+630 3.50mx1.50m 76.70 1.00 77.70

40+815 3.50mx1.50m 57.98 1.00 58.98

40+900 1.75mx1.50m 54.90 1.00 55.90

41+070 2.00mx1.50m 57.75 1.00 58.75

41 +445 13.50mx2.00m 51.28 1.50 52.7841+565 20.00mx2.00m 48.86 1.50 50.36

41+930 3.75mx1.50m "-66.16 1.00 67.16

42+580 3.50mx1.50m * 103.84 1.00 104.84

42+925 3.00mx1.50m 91.76 1.00 92.76

43+545 9.00mx1.50m 56.52 1.00 57.52

43+840 3.25mx1.50m 53.21 1.00 54.21

43+980 2.25mx1.50m 55.45 1.00 56.45

44+120 2.75mx1.50m 56.13 1.00 57.13

44+250 4.25mx1.50m 51.85 1.00 52.85

44+490 1.50mx1.50m 54.07 1.00 55.07

44+673 2.00mx1.50m 56.01 1.00 57.01

45+135 2.00mx1.50m 84.01 1.00 85.01

45+666 1.50mx1.50m 80.76 1.00 81.76

46+032 1.75mx1.50m 83.95 1.00 84.95

46+476 2.00mx1.50m 83.63 1.00 84.63

46+892 1.50mx1.50m 67.70 1.00 68.70

47+451 9.00mx1.50m 56.82 1.00 57.82

47+557 7.00mx1.50m 56.61 1.00 57.61

47+928 4.50mx1.50m 66.68 1.00 67.68


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48+174 32.00mx4.50m 49.84 3.50 53.34

4.3 Drainage Opening Sizes for Overpasses and Underpasses along the Expressway

Drainage Opening size for overpasses and underpasses were also determined using the methods used to

determine culvert openings. The required opening sizes are given in Table 4.3 and the relevant hydrologic and

hydraulic calculations are given in Annex (B.2)

Table 4.3 - Recommended Drainage Opening sizes for Overpasses and Underpasses

Road ID Chainage Opening Size RemarksDivulapitiya-Naiwala Rd (RDA) 25+535 (LHS) 9.25mxl.50mDivulapitiya-Naiwala Rd (RDA) 25+535(RHS) l.OOmxl.SOm vMedagampitiya-Hanchapola Rd (PS) 26+394 (LHS) 2.50mxl.50mMedagampitiya-Hanchapola Rd (PS) 26+394(RHS) 4.25mxl.50m

Banduragoda-Weyangoda Rd (PS) 27+451 (LHS) 6.00mxl.50m Should be provided to suit site conditionsBanduragoda-Weyangoda Rd (PS) 27+451 (RHS) l.SOmxl.SOm Should be provided to suit site conditionsRoad (PS) 27+980 (LHS) l.OOmxl.SOmRoad (PS) 27+980(RHS) 1.75mxl.50mBanduragoda-Weyangoda Rd (PS) 28+720 (LHS) l.OOmxl.SOm

Banduragoda-Weyangoda Rd (PS) 28+720(RHS) l.OOmxl.SOm

Road (PS) 29+210 (LHS) l.OOmxl.SOm

Road (PS) 29+210(RHS) l.OOmxl.SOm

Keppetiwalana-Baduragoda Rd (PS) 29+707 (LHS) l.OOmxl.SOmKeppetiwalana-Baduragoda Rd (PS) 29+707(RHS) l.OOmxl.SOm

Gaspe Rd (RDA) 30+520 (LHS) l.OOmxl.SOmGaspe Rd (RDA) 30+520(RHS) 1.25mxl.50mRoad (PS) 31 +040 (LHS) l.OOmxl.SOmRoad (PS) 31+040(RHS1 l.OOmxl.SOmRoad (PS) 31 +395 (LHS) 1.25mxl.50m Should be provided to suit site conditionsRoad (PS) 31+395(RHS) 2.00mxl.50m Should be provided to suit site conditionsRoad (PS) 31+830 (LHS) 1.25mxl.50m

Road (PS) 31+830(RHS) 1.25mxl.SOmRoad (PS) 32+839 (LHS) 6.25mxl,50m Should be provided to suit site conditionsRoad (PS) 32+839(RHS) 13.00mxl.50m Should be provided to suit site conditionsRoad (PS) 33+490 (LHS) l.OOmxl.SOm Should be provided to suit site conditionsRoad (PS) 33+490(RHS) l.SOmxl.SOm Should be provided to suit site conditionsMeerigama-Wewaldeniya Rd (PS) 37+579 (LHS) l.OOmxl.SOm Should be provided to suit site conditions

Meerigama-Wewaldeniya Rd (PS) 37+579(RHS) l.OOmxl.SOm Should be provided to suit site conditionsMeerigama-Danovita Rd (PDA) 39+149 (LHS) l.OOmxl.SOm Should be provided to suit site conditionsMeerigama-Danovita Rd (PDA) 39+149(RHS) 1.25mxl,50m Should be provided to suit site conditionsKoshena-Soduruwatta Rd (PS) 40+510 (LHS) 2.25mxl.50mKoshena-Soduruwatta Rd (PS) 40+51 0(RHS) 1.75mxl.50m

Diversion Rd (PS) 40+885 (LHS) l.SOmxl.SOm Should be provided to suit site conditionsDiversion Rd (PS) 40+885(RHS) 7.50mxl.50m Should be provided to suit site conditionsRoad (PS) 41 +085 (LHS) l.OOmxl.SOm

Road (PS) 41+085(RHS) 1.75mxl.50m

Road (RDA) 41+620 (LHS) 2.00mxl.50m Should be provided to suit site conditionsRoad (RDA) 41+620(RHS) 2.00mxl.50m Should be provided to suit site conditions

Road (PS) 42+595 (LHS) l.OOmxl.SOm

Road (PS) 42+595(RHS) l.OOmxl.SOm


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Diversion Rd (PS) 43+616 (LHS) 2.00mxl.50m Should be provided to suit site conditionsDiversion Rd (PS) 43+616(RHS) 7.00mxl.50m Should be provided to suit site conditionsRoad (PS) 44+228 (LHS) l.OOmxl.SOm Should be provided to suit site conditionsRoad (PS) 44+228(RHS) l.OOmxl.SOm Should be provided to suit site conditions

Road ID Chainage Opening Size Remarks

Diversion Rd (RDA) 44+444 (LHS) l.OOmxl.SOm Should be provided to suit site conditions

Diversion Rd (RDA) 44+444(RHS) l.OOmxl.SOm Should be provided to suit site conditions

Diversion Rd Meerigama (RDA) 45+1 54 (LHS) l.OOmxl.SOm Should be provided to suit site conditions

Diversion Rd Meerigama (RDA) 45+1 54 (RHS) l.OOmxl.SOm Should be provided to suit site conditions

Road (RDA) 45+464 (LHS) l.OOmxl.SOm

Road (RDA) 45+464(RHS) l.OOmxl.SOm

Diversion Rd (PS) 45+802 (LHS) l.OOmxl.SOm Should be provided to suit site conditions

Diversion Rd (PS) 45+802(RHS) l.OOmxl.SOm Should be provided to suit site conditions

Road (PS) 46+488 (LHS) 4.75mxl.50m Should be provided to suit site conditions

Road (PS) 46+488(RHS) l.OOmxl.SOm Should be provided to suit site conditionsRoad (PS) 46+91 8 (LHS) l.OOmxl.SOm Should be provided to suit site conditions

Road (PS) 46+91 8(RHS) l.OOmxl.SOm Should be provided to suit site conditions

Diversion Rd (PS) 47+51 2 (LHS) l.OOmxl.SOm Should be provided to suit site conditions

Diversion Rd (PS) 47+512(RHS) l.OOmxl.SOm Should be provided to suit site conditions

Note : LHS and RHS are with reference to the direction of chainage increase


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5.0 Water Quality Monitoring Plan

5.1 Scope of the Study

The monitoring plan covers three phases of water quality situation in the project area. These are baseline

(existing condition), construction phase and operational phases. The scope of this study/report is limited to

surface water quality.

5.2 Background

Water pollution due to highway projects both during construction and operation are mostly a Non-Point

Sources (NPS) Pollution issue caused by contaminated runoff. Point source pollution can also occur during the

construction (Discharge of untreated effluent from Labor Camps, etc.) and in operation (Discharge from

restaurants in rest areas, etc). Tackling point source pollution is relatively easy through enforcement of

environmental protection regulations and provisions of environmenta! safeguards in the construction contracts.

Non Point Source pollution on the other hand is difficult to address through such measures but needs

qualitatively different approaches.

The water quality assessments of highway projects have two basic objectives as described below.

(a) Estimation of pollution loads or concentrations as a result of the said highway during construction and

operation and thereby develop suitable impact mitigation measures;

(b) Prepare an monitoring plan that will enable the authorities to determine whether the safeguards put in

place are effective and thereby to help to meet the water quality objectives

An important component of any water quality assessment of this nature is water quality monitoring. The

monitoring program shall establish the baseline conditions, water quality during construction and operation.

Water quality monitoring is an expensive exercise. Therefore one of the most important requirements of water

quality monitoring is to determine a sampling program that would provide the required information at an

acceptable cost. The sampling program shall cover the sampling locations, frequency (space-time framework

of sampling plan) and water quality parameters. The choice of parameters is normally based on ambient water

quality requirements. Cost is usually a factor that limits the type and number of parameters included in

monitoring plans. Testing should be based on accepted standard procedures. Also

sampling and testing should be carried out by experience technicians in accredited laboratories. This is

important if the data are to be accepted in a court of law.

5.3 Assessment of Project Area


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5.3.1 Field Assessment

Water quality sampling plan needs identification of sampling locations. For this purpose a reconnaissance field

visit was undertaken on 7th

December and 14th

December 2010 to identify the water-bodies located in the said

stretch of the proposed expressway. This is basically a census of surface water-bodies that the proposed

expressway cut across from Baduragoda to Abepussa Interchange. Table 5.1 provides the list of water-

bodies (streams, canals, water pools/ponds and rivers) found in this stretch. The surface water-bodies

identified are mainly the irrigation canals also functioning as part of the storm water drainage systems. Table

5.1 depicts the usage of the water bodies observed during the field study [See the Notes at the bottom of

Table 5.1]. Figure 5.1 Map shows locations and The GPS coordinates of the Location IDs defined in Table

5.1 are provided in Table 5.2.

Shallow wells are a common feature along the expressway trace. At several places wells were found next to

streams/-canals with water overflowing from the mouth. These are public wells mainly used for bathing and

washing. Wells located in home gardens are mainly for household consumption including drinking.

Table 5.1-Surface Water-Bodies Located between Baduragoda - Ambepussa

Location ID* Description Usage

WQ1 Kuda Oya - major streamWashing/Bathing/ Storm water Drainage/

(Note- Not withdrawn for water supply in

the immediate downstream)

WQ2 Small irrigation ditch cutting across DudlySenanayake Road Irrigation

WQ3Small irrigation canal/ditch by the edge of the paddy filed cuttingaccress Devala Road

Irrigation

WQ4 Small stream which feeds a small pond used for bathing Bathing

WQ5 Two small irrigation ditches Irrigation

WQ6 Small irrigation canal Irrigation

WQ7Irrigation canal with substantial flow going along the edge of the paddy

field and parallel to the toe of the narrow lane

Irrigation (Note: Other uses may be

possible in the downstream)WQ8 Sizable irrigation canal flowing through paddy filed (Village

Kebellawita)

Irrigation (Note: Other uses may be

possible in the downstream)WQ9 Wide irrigation canal with substantial flow Irrigation (Note: Other uses may be

possible in the downstream)

Location ID* Description Usage

WQ10 Small irrigation ditch Irrigation


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WQ11Wide channel through paddy lands (in the vicinity of Rilagala); there

was substantial flow

Irrigation/ bathing/washing

WQ12 Small irrigation stream through paddy fields Irrigation

WQ13 Very small irrigation channel; very low flow; Latha Mawatha Irrigation

WQ14 Large stream; substantial flow Irrigation/Bathing /Washing

WQ15Set of small irrigation ditches

Irrigation

WQ16 Very small natural stream flowing through home gardens Drainage

WQ17Sizable stream also serving as a important irrigation drainage canal;

Stream cut across B1 7 road; there are other small irrigation ditches

Irrigation/ Drainage/ Bathing/ Washing

WQ18By the side of main road B17. Drainage channel; railway line is parallel

to the road about 50 feet away

Drainage

WQ19 Small irrigation ditch by the side of the paddy filed fields Irrigation

WQ20Small stream crossing the railway line and going through uncultivated

paddy area

Drainage

WQ21 Two minor irrigation ditches Irrigation

WQ22 Set of small irrigation canals crossing and going parallel to B26 road.These canals combine and convert to a sizable canal with significant

flow

Irrigation/ (Note: Other uses may be

possible in the downstream)

WQ23Two small irrigation canals flowing along the two edges of the paddy

area; substantial flow

Irrigation

WQ24Two small irrigation canals flowing Tajong the two edges of the paddy

area; ^ ,

Irrigation

WQ25Tank situated outside the road boundary but the spill channel of the

tank is cut across by the proposed highway

Bathi ng/Wash ing/I rrigation

WQ26Wide irrigation channel going through a large paddy filed. Two other

small irrigation ditches are flowing at the two edges of the

paddy area

Irrigation/ Drainage (Note: Other uses may

be possible in the downstream)

WQ27 Small irrigation channel flowing at the edge of the paddy land Irrigation

WQ28 Two small irrigation ditches Irrigation

WQ29 Very small irrigation ditch Irrigation

WQ30 About 3 feet wide irrigation ditch running at the edge of the paddy filed

and highland

Irrigation/drainage

WQ31 Small irrigation ditch Irrigation

WQ32 Small irrigation ditch going at the edge of the paddy fields Irrigation

WQ33Sizable irrigation canal partly lined and going through paddy lands Irrigation/washing

Note 1: The descriptions under the "Usage" column are based on observations made during the

reconnaissance filed visit. It is recommended that further investigations were made on ambient uses of

major water-bodies and record the uses with more details for at least 1-2 kilometers downstream.

Note 2: Identifications (ID) numbers of water bodies are given consecutively from the point first visited to the

point last visited. First visited point is defined as WQ1.


13/36

Note 3: Flow conditions of the streams, canals etc reflects the situation at the day of the inspection (wet

weather with significant rainfall in the previous days).

Note 4: Irrigation canals also acts as drainage canals in many cases


14/36

Table 5.2- Water Quality Locations

Location Longitude Latitude

WQ1 80 12.451 7 14.669

WQ2 80 12.246 7 14.496

WQ3 8011.840 7 14.296WQ4 8011.674 7 14.247

WQ5 8011.428 7 14.466

WQ6 8011.348 7 14.720

WQ7 8011.191 7 14.779

WQ8 8011.094 7 14.879

WQ9 8010.819 7 14.860

WQ10 80 09.806 7 14.382

WQ11 80 09.885 7 14.292

WQ12 80 09.942 7 14.462

WQ13 80 09.049 7 14.099

WQ14 80 08.541 7 14.063

WQ15 80 08.305 713.995

WQ16 80 07.993 714.129

WQ17 80 07.266 7 14.009

WQ18 8007.117 7 14.007

WQ19 80 07.224 7 14.029

WQ20 80 06.842 7 14.590

WQ21 80 06.569 7 14.484

WQ22 80 05.798 7 14.294

WQ23 8005.517 7 14.226

WQ24 80 05.298 7 14.024

WQ25 80 04.873 713.775

WQ26 80 04.490 713.953

WQ27 80 02.344 7 12.369

WQ28 80 02.756 7 12.628

WQ29 80 02.838 7 12.733

WQ30 80 03.078 712.810

WQ31 80 03.351 7 12.975

WQ32 80.03.746 7 13.303

WQ33 80 3.753 713.569


15/36

5.3.2 Climatic Conditions

Table 5.3 gives the average annual rainfall for calendar year at Abepussa and Henarathgoda

(Gampaha).

Table 5.3 - Average Annual Rainfall in Millimeters

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

Abepuss ' 50.4 78.1 165.8 271.6 248.2 200.2 126.3 120.7 209.7 399.8 314.5 122.4 2307.7

Henarathgoda 63.8 79.0 141.4 241.0 382.1 231.3 138.3 145.2 250.1 346.1 298.9 159.5 2476.7

It is assumed the rainfall quantities and pattern for Abepussa and Henarathgoda (Gampaha) gauging stationsrepresent the situation for the project area. The key observations of rainfall pattern are:

a. January and February are the driest months and the sizable rainfall is commencing at

end of March. March and April represent the first inter-monsoon period, b. May records significant

rainfall and May to September is the South-West Monsoon

period. Flooding is common in this month, c. October and November together records the heaviest

rainfall period and these two

months represent the second inter-monsoon period. Flooding is common in this period, d. December

to February represent the North-East Monsoon Period.

5.4 Ambient Water Quality Requirements

The best yardstick for evaluating freshwater quality in this case is the ambient water quality requirements for

satisfying various water uses. Table 5.4 reports the water quality criteria for freshwater systems for different

categories of water uses (Central Environmental Authority, 2003). Accordingly there are seven categories of

water uses falling into three classes as given below. Table 5.4 provides the acceptable concentration levels

for some selected parameters for different ambient uses of water. Full details of acceptable parameter levels,

including for heavy metals are available in the CEA publications.


16/36

Categories of Water Uses

Nature conservation

Drinking with simple treatment

Bathing and recreation

Fish and aquatic life

Drinking with conventional treatment

Irrigation and agriculture

Minimum quality (other uses)

As water uses for water-bodies are identified (Table 5.1), it is possible to determine the

important water quality parameters and minimum water quality requirements for each water-

body using the published data. Although not required in this case other additional parameters

can be added to evaluate the long-term impacts such as eutrophication.

Table 5.4 - Ambient Water Quality Requirement for Water Use Categories

Water Use

Category

PH Con. Turb DO COD P F SAR SO4 Cl

High]

1

2 6.0 8.5 5 *6 15 0.7 1.5 250 200

3 6.0 9.0 5 20 0.7

4 6,0 8.5 3 15 0.4

5 6,0 9.0 4 30 0.7 1.5 250 200

6 6.0 8.5 700 3 0.7 6-15

Note 1: Con-Conductivity (ds/m); Turb -Turbidity (NTU); pH, SAR -Numerical values; others -

ppm Note 2: Requirements for nature conservation to be determined on case by case basis

Note 3; Refer to CEA publications for concentration limits for other parameters including heavy metals

ass

ass I

ass II

ass II

ass II

ass II

ass II

ass III


17/36

5.5 Sampling Plan

5.5.1 Construction Phase

5.5.1.1 Nature of Construction Phase

Among the contributory factors for deterioration of water quality during road construction are:

(a) soil loss causing high sediment loads in runoff which also cause sedimentation in streams

and rivers, soil/sediment can also carry other pollutants to the water column; (b) biological

pollution due to damaged drainage

Pipes, septic tanks, uncontrolled discharge of wastewater generated in labour camps, etc;

and (c) spills of chemicals. During construction increased turbidity, color, suspended solids

are difficult to avoid water quality problems. Chemical pollution commonly includes petroleum

products.

The magnitude of impacts of these pollutants on water-bodies is dissimilar and depends on

ambient uses. In the project area there are no ecologically sensitive water-bodies requiring

application of conservation measures. As such in this case the water-bodies which are used

for water supply, bathing, and recreation are the most critical in terms of water quality. The

main water-body in this section is the Kuda Oya. Although water supply intakes are notpresent in Kuda Oya in the immediate downstrearn. from the point of intersection with the

proposed expressway, it is possible for such intakes in this water-body considering its size.

Most of the other water-bodies identified in Table 5.1 are irrigation/drainage canals. Thus

water quality standards applicable to these water-bodies are significantly less.

The other characteristic of the construction phase is that the wide spread nature of activities,

so that water quality deterioration is reflected across the area under construction. However,

problem could be more acute in certain areas where activities such as bridge construction are

taking place. Similarly high biological pollution could be possible down streams of labour

camps, if located close to waterways. [Note: Special areas such as borrow sites and mining

sites are not included in this study].

5.5.1.2 Special Issues (Bentonite Loss)

Bentonite clays are heavily used in Southern Expressway Project for pile driving work. While


18/36

bulk of the betonite is recovered and reused small percentage is always get to the environment

and washed away to natural water courses during rains. Therefore the impact of bentonite on

water quality is of special interest.

Bentonite is basically clay consisting mostly of montmorillonite. It has large water absorbing

capacity thus can convert to viscous liquid which is used in drilling and pilling work in

construction engineering. Bentonite is normally refered by dominant cation such as Calcium,

Sodium, Aluminum, or Potassium. Calcium bentonite has ion exchange characteristics. It can

exchange its Calcium Ion to other irons. Thus theoretically a water quality change takes

place. However, this is absolutely negligible in terms of quantities of runoff water. The other

issue is not so much of water quality but settling of bentonite slurry in small irrigation canals,

waterways and even on access roads. It is heavy and when mixed with water acts as a jelly.

Thus it can settle on the drainage paths within short distance. This is unlikely to cause an

impact unless large quantities are lost inadvertently cause drainage paths to be blocked or

roads surfaces to become slippery when wet.

5.5.1.3 Water Quality Parameters proposed for Monitoring

V '

Water-bodies listed in Table 5.1 can be divided into two broad categories based on their

ambient uses as:

A. Water-bodies used for bathing and recreation (water intakes were not observed in the

immediate project area)

B. Water-bodies serving as irrigation/drainage canals

The water quality parameters for monitoring are determined based on pollutants that are likely

to gain entry during construction and affecting the ambient uses. The proposed parameters

are given in Table 5.5.

5.5.1.4 Sampling Locations

To an extent water-bodies in Table 5.1 divided into two environmental settings.

(a) WQ 1- WQ 14 - somewhat hilly terrain

(b) WQ 15 - WQ 33 - relatively flat terrain

In similar environmental settings water quality impacts of construction are likely to be felt


19/36

similarly in the downstream of the road trace. Section from WQ 15- WQ 33 (See the Map given

in Figure 5.1) is more or less similar to the last segment of the first 25 kilometers, which was

covered in the previous study. Also a water-body of significant importance was not found in

this section. [Note: One irrigation tank is located at WQ 25. However, this is located upstream

of the proposed expressway and not expected to be affected by the proposed project

significantly].

On the other hand WQ 1 to WQ 14 represents somewhat hilly area and not part of flood plains. It

is assumed that water quality effects of the project are similar in this section. Therefore two

use-wise important water-bodies are proposed in this section for monitoring. The two water-

bodies are WQ 1 (Kuda Oya) and WQ 11 (Irrigation Canal in Rilagala Area). Monitoring at

upstream location is also proposed for these two water-bodies. The reason for inclusion of

upstream location in the monitoring plan is that it provides water quality data undisturbed by

the construction activities. Thus they will be useful for assessing the construction impacts.

[Note: Upstream water quality can be affected during flooding. This situation is not covered in

general water quality assessment].

Table 5.5 - Water Quality Sampling Locations for Construction Phase

Type of Water- Water-body Sampling Locations Parametersbody ID

A W1 300m upstream of centerline of the trace COD

BOD

600m downstream of centerline of theTSS

trace Turbidity

Color

pH

Colour

Oil andA W11 200m upstream of centerline of the trace Grease

Nitrate -N

trace Phosphate

5.5.1.5 Frequency of Monitoring


20/36

Worst water quality situations in the water-bodies identified in Table 5.1 can occur at times

when (a) significant runoff is generated when -the streams/canals/rivers are in low flow

conditions during seasonal dry period or due to irrigation controls, (b) significant runoff

generated after a long dry spell. As these conditions occur in an ad hoc manner, is not

possible to fix an exact time for monitoring where the intention is to ascertain the worst

water quality situation. Thus it is useful that timing of sampling to be determined by those

responsible based on their judgment. However by considering the climatic data reported in

Section 5.3.2 it is proposed to include minimum of five samples per year on following basis.

(i) One sample at each sampling location in January or February immediately after a

sizable storm event.

(ii) One sample at each sampling location in April after a sizable storm event

(iii) One sample at each sampling location in May

(iv) One sample at each sampling location in August after a sizable storm event

(v) One sample at each sampling location in October or November

5.5.2 Operational Phase

5.5.2.1 Nature of Operational Phase

Operational phase water quality pollution is primarily NPS pollution. In this phase long-term

impacts are also an important consideration as heavy metals and other chemicals including

petroleum based products are also a concern in this phase. Nevertheless significant long-term

effects, such as due to bio-accumulation are not expected in here. This is because substantial

rains during May and then in October-November period has high potential for flushing out

pollutants with less opportunity for long-term accumulation. As the water-bodies of concern are

flowing water-bodies chances of such accumulation is reduced further.

5.5.2.2 Water Quality Parameters proposed for Monitoring

Detailed list of pollutants entering the runoff from roads/highways under operation are provided

by the USEPA (1997). These mainly include: (a) particulate matter, (b) N and P from fertilizer

and pesticides, if maintenance of turf is part of the operation, (c) verity of heavy metals from

ware and tare of tires, combustion products, etc (d) oil and petroleum products due to spilling

(e) pathogens from animal excreta and rest areas. It is not practical and economical for the

water quality monitoring program to include all th,e individual pollutants. Thus the following set


21/36

of waterc.

quality parameters are proposed for water quality monitoring during operations, which can give

the picture of general water quality status.

Turbidity

pH

COD

TSS

Kjeldahl-N

Phosphate-P

Copper

Zin


22/36

5.5.2.3 Sampling Locations

Category B water-bodies (Section 5.5.1.2) are less important during operation phase as water is

not in direct contact with humans. Therefore only Category A water-bodies are proposed for the

monitoring program in this phase. Water-body proposed for the sampling program during operationis WQ1. Sampling location is defined in Table 5.6 below.

Table 5.6 -Water Quality Sampling Locations for Operational

300m upstream of centerline of the trace

600m downstream of centerline of the trace

5.5.2.4 Frequency of Monitoring

During the operational phase "first flush" in general results highest pollution concentrations in the runoff.

First flush means rainfall caused runoff after a dry period. Such events under low flow conditions usually

result relatively high pollution concentrations. On the other hand pollution concentration becomes less

prominent during heavy rain period due to dilution by increased flow. Accordingly following monitoring

schedule is proposed for operational phase, (i) One sample at each sampling location in January or

February immediately after a sizable storm event.

(ii) One sample at each sampling location in April after a sizable storm event (iii) One sample

at each sampling location in August after a sizable storm event (iv) One sample at each

sampling location in October or November

5.6 Baseline Conditions

Baseline water quality reflects the situation before the construction of the expressway. Baseline studyincludes two water-bodies selected for monitoring program under construction phase. The two water-bodies

are WQ1 and WQ11 {Table 5.1). Table 5.7 provides the details of the baseline water quality plan.

Table 5.7 - Water Quality Sampling Locations for Baseline Study

Type of

Water-body

Water-body ID Sampling Locations Parameters

A W1 600m downstream of centerline of the trace COD BOD

Water-body

ID

Sampling Locations

W1


23/36

A W11 600m downstream of centerline of the trace TSS

Turbidity

Color

pH

Colour

,,. Oil and Grease

Nitrate -N

Phosphate

;-*. Copper

. " Zinc

The water quality measurements during baseline study shall reflect the same flow or hydrologic conditions

under which the sampling was carried out during construction and operational phases. Thus sampling

frequency (time frame) for baselines study is set as follows, (i) One sample at each sampling location in

January or February immediately after a sizable storm event.

(ii) One sample at each sampling location in April after a sizable storm event (iii) One sample

at each sampling location in the month of May (iv) One sample at each sampling location in

August after a sizable storm event (v) One sample at each sampling location in October or

November

One set of data is unlikely to provide us the general water quality picture for baseline conditions. For this

purpose at least few years of data would be required. However, in reality water quality data of such length

and coverage are often not available. It is recommended to commence the baseline water quality data

collection as early as possible to collect a reasonably long data set to develop sufficiently accurate picture of

water quality before the project. In absence of such possibility it is necessary to use other historical water

quality data to generate the information required.


24/36


25/36

6.0 Recommendations

1. The drainage openings for small streams, Irrigation canals have been designed considering once in

fifty year flood situation.i.e. fifty year return period. In the design future development of area which

will increase the impervious area and the runoff volume has been considered. However with thepast experience climate changes and the percentage of land converting to developments have

been taken in to account.

2. Since the proposed highway trace passes through the low-lying areas and hilly areas it is

recommended to construct the cross drainage structures to minimize the effect of backwater

created by rising flood levels. The minimum sizes of Culverts across the proposed alignment are

included in table 4.1. Also it should be ensured that there will not be any settlements of culverts to

avoid adverse environmental impacts due to stagnation of water.

3. It is observed that the present uncertainty related to climate change which links to flood damage.

Therefore It is suggested to minimize the filling which causes adverse environment effect by

introducing Viaduct sections wherever necessary. Also natural water paths should not be disturbed

and should be improved.

4. If any changes are suggested using viaduct sections in your design sofit levels of those and location

of piers should be brought to the notice of SLLRDC for rechecking.

5. The outlet of all the proposed culvert/bridge crossings should be dredged and connected to the

nearby streams. The inlets of the same should be cleared about 500m upstream. These drainage

connections should be established before filling of embankment.

6. All drainage structures have been provided for cross drainage only. If additional structures are

needed for irrigation purposes they should be additionally provided.

7. It is desirable to discuss the locations of the proposed drainage crossings with Irrigation

Department, and Department of Agrarian Development Services and farmers' organizations. If anychanges are suggested those should be brought to the notice of SILRDC for rechecking.


26/36

8. The toe drains and other drainage canals in the vicinity of the road along the expressway should be

established as proposed in the Table 4.3.

9. Prior approval for the proposed bridges across the Kuda oya should be obtained from Department of

Irrigation.

10. Canal banks which already collapsed should be protected using gabions at least 200m both sides

(U/S and D/S) of the Canals where proposed culverts are located.

11. Canals should be dredged and kept to a desirable bed width. Necessary other maintenance should

be carried out through the responsible institution simultaneously at least 500m both sides (U/S and

D/S) of the Canais where proposed culverts are located.

12. The distance proposed for downstream measurement of water quality is for the purpose of providing

adequate mixing of pollutants with the stream flow. Also Upstream measurement is aimed at

obtaining the undisturbed picture during measurements.

13. The water quality monitoring plan to be implemented in three phases such as baseline (before the

project and existing .status), construction phase and operational phase.

14. Proper sample preservation methods are required. Therefore Sampling and testing should be carried

out by recognized institution.

15. Analytical methods use for water quality monitoring should be the standard methods accepted in Sri

Lanka.


27/36

Bibliography

(i) Design of Irrigation head works for Small Catchments,2ndEdition (Revised) ,AJ.P.Ponrajah,lrrigation Department Colombo, May 1984

(ii) Technical paper of towards more efficient hydraulic and hydrological Design of Cross drainagesstructures using new developed Intensity Duration Frequency Equations by D.G.L. RanatungaFormer Head Hydrology Division Irrigation Department.

(iii) Applied hydrology, International Edition, 1988 by Ven Te Chow.

(iv) Hydrological Study for Colombo-Kandy Alternate Highway Chainage from 0+000 km to25+000 km

(v) Ambient Water Quality Guidelines, Central Environmental Authority, 2003

(vi) Controlling Nonpoint Source Runoff Pollution from Roads, Highways and Bridges.

Washington, D.C.: Office of Water, U.S. Environmental Protection Agency, 1995.

(vii) Environmental Impact Assessment Report; Colombo-Kandy Alternate Highway Project;2003.

(viii) Sources and Mitigation of Highway Runoff Pollutants; Federal Highway Administration;Washington, D.C., 1984.

(ix) Statistical Methods for Environmental Pollution Monitoring; R.O, Gilbert; 1987.


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Annex (B.1): Hydrological and Hydraulic Calculation for Drainage Opening Sizes

Culvert ID

(Chainage)

Total

Catch m

ent Area

(ha)

Length of

Longest

water

path (m)

Runoff

Coeffici

ent

Time of

Concent

ration

Tc(min)

Rainfall

Intensity

(mm/hr)

SOyr

Discharge

(m3/sec)

SOyr

slope Water

Depth

(m)

Proposed Size of

Structure

25+245 284.37 2080 0.40 90.82 97.89 30.93 0.0006 1.50 10.00mx2.00m

25+367 20.22 1101 0.40 55.14 127.07 2.85 0.0020 1.00 1.50mx1.50m

25+565 90.05 1255 0.40 60.75 121.30 12.14 0.0010 1.00 6.25mx1.50m

25+947 100.86 1348 0.40 64.14 118.08 13.23 0.0010 1.00 6.50mx1.50m

26+180 20.08 873 0.40 46.82 136.77 3.05 0.0010 1.00 2.00mx1.50m

26+550 25.18 738 0.40 41.90 143.30 4.01 0.0010 1.00 3.00mx1.50m

27+308 57.39 1089 0.40 54.70 127.54 8.13 0.0010 1.00 4.50mxl50m

27+481 8.39 449 0.40 31.37 159.78 1.49 0.0010 1.00 1.50mx1.50m

27+948 46.67 966 0.40 50.21 132.63 6.88 0.0010 1.00 4.00mx1.50m

28+400 ! 35.09 654 0.40 38.84 147.71 5.76 0.0010 1.00 1.75mx1.50m

28+500 J 1.75mx1.50m

28+885 26.36 718 0.40 41.17 144.32 4.23 0.0015 1.00 2.25mx1.50m29+520 53.06 925 0.40 48.72 134.42 7.92 0.0010 1.00 4.25mx1.50m

30+036 26.64 780 0.40 43.43 141.20 4.18 0.0015 1.00 2.50mx1.50m

30+330 34.72 1069 0.40 53.97 128.34 4.95 0.0015 1.00 2.50mxl50m

31+156 -i 82.94 936 0.40 49.12 133.94 12.34 0.0010 1.00 3.50mx1.50m

31+240 J 3.50mx1.50m

31+923 -, 60.75 625 0.40 37.78 149.30 10.08 0.0004 1.00 1.50mxl50m

32+000 I 3.25mx1.50m

32+088 | 1.50mx1.50m

32+235 J 1.75mx1.50m

32+665 297.15 2751 0.40 115.28 84.87 28.02 0.0005 1.50 10.00mx2.00m

32+985 223.45 2423 0.40 103.33 90.74 22.53 0.0005 1.50 8.50mx2.00m33+390 i 36.02 802 0.40 44.24 140.12 5.61 0.0015 1.00 1.50mx 1.50m

33+500 J 1.50mx1.50m

33+858 1 , 84.15 979 0.40 50.69 132.07 12.35 0.0005 1.00 2.75mx1.50m

33+936 6.75mx1.50m

34+913 14.09 435 0.40 30.86 160.69 2.52 0.0010 1.00 3.50mx2.50m

35+358 -i 202.54 1884 0.40 83.68 102.55 23.08 0.0007 1.00 4.25mx1.50m

35+410 4.50mx1.50m

35+460 J 4.25mx1.50m

35+615 ~\ 134.31 2044 0.40 89.51 98.72 14.73 0.0010 1.00 4.00mx1.50m

35+730 J 4.00mx1.50m

36+323 -\ 53.10 1010 0.40 51.82 130.76 7.71 0.0010 1.00 2.25mx1.50m36+385 J 2.25mx1.50m

36+555 85m opening should be provided for Merigama-Pasyala Rd and Railway Track 85m Opening

36+608 4.54 849 0.40 45.95 137.89 0.70 0.0010 1.00 1.50mx1.50m

36+853 9.43 441 0.40 31.08 160.30 1.68 0.0010 1.00 1.50mx1.50m

37+250 15.12 565 0.40 35.60 152.70 2.57 0.0010 1.00 2.00mx1.50m


29/36

Culvert ID

(Chainage)

Total

Catchm

ent Area

(ha)

Length of

Longest

water

path (m)

Runoff

Coeffici

ent

Time of

Concentr

ation

Tc(min)

Rainfall

Intensity

(mm/hr)

50yr

Discharge

(m3/sec)

SOyr

slope Water

Depth

(m)

Proposed Size of

Structure

37+522 56.11 1122 0.40 55.90 126.25 7.87 0.0010 1.00 4.25mx1 .50m

37+893 -i 456.45 3977 0.40 159.98 68.57 34.78 0.0008 1.00 9.00mx1.50m

38+001 J 9.00mx1.50m

38+400 16.58 469 0.40 32.10 158.51 2.92 0.0010 1.00 2.00mx1.50m

38+676 45.02 1662 0.40 75.59 108.42 5.42 0.0010 1.00 3.25mx1.50m

38+943 38.00 1347 0.40 64.10 118.11 4.99 0.0010 1.00 3.00mx1.50m

39+195 48.55 1128 0.40 56.12 126.02 6.80 0.0010 1.00 3.75mx1.50m

40+065 24.41 802 0.40 44.24 140.12 3.80 0.0010 1.00 2.50mx1.50m

40+630 52.94 1707 0.40 77.23 107.18 6.30 0.0010 1.00 3.50mx1.50m

40+815 45.74 1410 0.40 66.40 116.03 5.90 0.0010 1.00 3.50mx1 .50m

40+900 13.83 712 0.40 40.96 144.63 2.22 0.0010 1.00 1.75mx1.50m

41+070 15.07 575 0.40 35.96 152.13 2.55 0.0010 1.00 2.00mx1.50m

41+445 \ 1456.46 5049 0.40 199.06 58.90 95.32 0.0004 1.50 13.50mx2.00m

41+565 20.00mx2.00m

41+930 44.91 964 0.40 50.14 132.72 6.62 0.0010 1.00 3.75mx1.50m

42+580 40.83 976 0.40 50.58 132.20 6.00 0.0010 1.00 3.50mx1.50m

42+925 34.31 1064 0.40 53.79 128.54 4.90 0.0010 1.00 3.00mx1.50m

43+545 1 193.10 1539 0.40 71.10 112.00 24.03 0.0008 1.00 9.00mx1.50m

43+840 ^ 3.25mx1.50m

43+980 26.35 1472 0.40 68.66 ,114.06 3.34 0.0010 1.00 2.25mx1 .50m

44+120 31.66 1332 0.40 63.56 118.62 4.17 0.0010 1.00 2.75mx1 .50m

44+250 57.71 1366 0.40 64.80 117.48 7.53 0.0009 1.00 4.25mx1.50m

44+490 10.44 475 0.40 32.32 158.14 1.83 0.0010 1.00 1.50mx1.50m

44+673 14.18 416 0.40 30.16 161.93 2.55 0.0010 1.00 2.00mx1.50m

45+135 17.40 501 0.40 33.26 156.53 3.03 0.0010 -1.00 2.00mx1 .50m

45+666 9.19 473 0.40 32.24 158.26 1.62 0.0010 1.00 1.50mx1.50m

46+032 12.31 528 0.40 34.25 154.89 2.12 0.0010 1.00 1.75mx1.50m

46+476 16.63 469 0.40 32.10 158.51 2.93 0.0010 1.00 2.00mx1.50m

46+892 10.30 450 0.40 31.40 159.72 1.83 0.0010 1.00 1.50mx1.50m

47+451 1 267.06 1630 0.40 74.42 109.33 32.44 0.0009 1.00 9. 00m x 1.50m

47+557 -* 7.00mx1.50m

47+928 62.61 1255 0.40 60.75 121.30 8.44 0.0010 1.00 4.50mx1.50m

48+174 5057.04 13399 0.40 503.44 32.92 184.95 0.0040 3.50 32.00mx4.50m


30/36

Annex (B.2): Hydrological and Hydraulic Calculation for Drainage Opening Sizes for

Overpass and Underpass

Culvert ID

(Chainage)

lotai

Catchme

nt Areaha

i_engin

of

Longest

water

Runoff

Coeffici

ent

i ime or

Concentr

ationTc min

Kainran

Intensity

(mm/hr)50 r

uiscnarg

e

(m3/sec)50 r

slope

SWater

Depth

(m)

Proposed Size

of Structure

25+535 (LHS) 161.92 1838 0.40 82.00 103.71 18.66 0.001 1.00 9.25mxl.50m

25+535(RHS) 2.16 202 0.40 22.36 177.47 0.43 0.001 1.00 l.OOmxl.SOm

26+394 (LHS) 25.18 830 0.40 45.26 138.78 3.88 0.001 1.00 2.50mxl.50m

26+394(RHS) 54.20 1063 0.40 53.75 128.58 7.74 0.001 1.00 4.25mxl.50m

27+451 (LHS) 87.68 1215 0.40 59.29 122.75 11.96 0.001 1.00 6.00mxl.50m

27+451 (RHS) 11.87 893 0.40 47.55 135.86 1.79 0.001 1.00 l.SOmxl.SOm

27+980 (LHS) 5.40 347 0.40 27.65 166.61 1.00 0.001 1.00 l.OOmxl.SOm

27+980(RHS) 15.67 821 0.40 44.93 139.21 2.42 0.001 1.00 1.75mxl.50m

28+720 (LHS) 1m minimum openings should be provided . l.OOmxl.SOm

28+720(RHS)l.OOmxl.SOm

29+210 (LHS) l.OOmxl.SOm

29+21 0(RHS) l.OOmxl.SOm

29+707 (LHS) 0.58 94 0.40 18.43 186.59 0.12 0.001 1.00 l.OOmxl.SOm

29+707(RHS) 5.11 515 0.40 33.77 155.67 0.88 0.001 1.00 l.OOmxl.SOm

30+520 (LHS) 4.15 355 0.40 27.94 166.06 0.77 0.001 1.00 l.OOmxl.SOm

30+520(RHS) 8.89 728 0.40 41.54 143.81 1.42 0.001 1.00 1.25mxl.50m

31 +040 (LHS) 1.83 180 0.40 21.56 179.25 0.36 0.001 1.00 l.OOmxl.SOm

31+040(RHS) 6.48 762 0.40 42.78 142.09 1.02 0.0010 1.00 l.OOmxl.SOm

31 +395 (LHS) 9.06 539 0.40 34.65 154.23 1.55 0.001 1.00 1.25mxl.50m

31+395(RHS) 18.83 776 0.40 43.29 141.40 2.96 0.001 1.00 2.00mxl.50m

31+830 (LHS) 9.08 663 0.40 39.17 147.22 1.49 0.001 1.00 1.25mxl.50m

31+830(RHS) 10.10 1712 0.40 77.41 107.04 1.20 0.001 1.00 1.25mxl.50m

32+839 (LHS) 127.08 2627 0.40 110.76 86.99 12.28 0.001 1.00 6.25mxl.50m

32+839(RHS) 255.40 2571 0.40 108.72 87.99 24.97 0.001 1.00 13.00mxl.50m

33+490 (LHS) 1.93 204 0.40 22.44 177.31 0.38 0.001 1.00 l.OOmxl.SOm

33+490(RHS) 10.63 697 0.40 40.41 145.42 1.72 0.001 1.00 l.SOmxl.SOm

37+579 (LHS) 4.62 359 0.40 28.09 165.78 0.85 0.001 1.00 l.OOmxl.SOm

37+579(RHS) 1.11 155 0.40 20.65 181.32 0.22 0.001 1.00 l.OOmxl.SOm

39+1 49 (LHS) 6.89 627 0.40 37.86 149.19 1.14 0.001 1.00 l.OOmxl.SOm

39+149(RHS) 7.99 412 0.40 30.02 162.19 1.44 0.001 1.00 1.25mxl.50m

40+510 (LHS) 20.74 732 0.40 41.68 143.61 3.31 0.001 1.00 2.25mxl.50m

40+51 0(RHS) 11.71 443 0.40 31.15 160,17 2.08 0.001 1.00 1.75mxl.50m

40+885 (LHS) 9.25 425 0.40 30.49 161.34 1.66 0.001 1.00 l.SOmxl.SOm

40+885(RHS) 119.09 1586 0.40 72.82 110.60 14.64 0.001 1.00 7.50mxl.50m

41+085 (LHS) 0.56 95 0.40 18.46 186.50 0.12 0.001 1.00 l.OOmxl.SOm

41+085(RHS) 14.56 778.00 0.40 43.36 141.30 2.29 0.001 1.00 1.75mx1.50m

41+620 (LHS) 19.31 761 0.40 42.74 142.14 3.05 0.001 1.00 2.00mxl.50m

41+620(RHS) 18.02 946 0.40 49.49 133.50 2.67 0.001 1.00 2.00mxl.50m


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Culvert ID

(Chainage)lotalCatchme

nt Area

ha

Length

of

Longest

water

Runoff

Coeffici

ent

i ime or

Concentr

ation

Tc min

Kamtall

Intensity(mm/hr)

50 r

Uischarg

e

(m3/sec)

50 r

slope

SWaterDepth(m)

Proposed Size

of Structure

42+595 (LHS) 5.59 458 0.40 31.70 159.21 0.99 0.001 1.00 l.OOmxl.SOm

42+595(RHS) 2.37 211 0-40 22.69 176.75 0.47 0.001 1.00 l.OOmxl.SOm

43+616 (LHS) 17.06 686 0.40 40.01 145.99 2.77 0.001 1.00 2.00mxl.50m

43+61 6(RHS) 85.09 928 0.40 48.83 134.29 12.70 0.0009 1.00 7.00mxl.50m

44+228 (LHS) 4.99 374 0.40 28.63 164.75 0.91 0.001 1.00 l.OOmxl.SOm

44+228(RHS) 6.31 392 0.40 29.29 163.53 1.15 0.001 1.00 l.OOmxl.SOm

44+444 (LHS) 4.36 457 0.40 31.66 159.27 0.77 0.001 1.00 l.OOmxl.SOm

44+444(RHS) 1.29 171 0.40 21.23 179.99 0.26 0.001 1.00 l.OOmxl.SOm

45+1 54 (LHS) 0.38 113 0.40 19.12 184.91 0.08 0.001 1.00 l.OOmxl.SOm

45+154 (RHS) 6.10 1295 0.40 62.21 119.89 0.81 0.001 1.00 l.OOmxl.SOm

45+464 (LHS) 1 m minimum openings should be provided . l.OOmxl.SOm45+464(RHS) l.OOmxl.SOm

45+802 (LHS) l.OOmxl.SOm45+802(RHS) l.OOmxl.SOm

46+488 (LHS) 56.71 751 0.40 42.38 142.64 8.99 0.001 1.00 4.75mxl.50m

46+488(RHS) 2.14 370 0.40 28.49 165.02 0.39 0.001 1.00 l.OOmxl.SOm

46+91 8 (LHS) 1.09 185 0.40 21.74 178.84 0.22 0.001 1.00 l.OOmxl.SOm

46+91 8(RHS) 5.87 442 0.40 31.11 160.23 1.05 0.001 1.00 l.OOmxl.SOm

47+51 2 (LHS) 5.79 380 0.40 28.85 164.34 1.06 0.001 1.00 l.OOmxl.SOm

47+51 2(RHS) 2.71 273 0.40 24.95 171.97 0.52 0.001 1.00 l.OOmxl.SOm

Following details are enclosed into Annex (C);

1). Details of culverts "'

2). Maps showing catchment areas

3). Colombo Kandy alternate Expressway plan and longitudinal maps

4). Longitudinal sections and Cross sections at Chainage 33+368 km, 37+8.79 km 38+001 km and

48+174 km


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