annex 6 final

8/11/2019 Annex 6 Final

1/39

ANNEXURE

6

PROJECT LAYOUT AND HYDRAULIC

DESIGN CONSIDERATIONS


2/39

ANNEXURE

6-A

DESIGN OF SPILLWAY


3/39

Koto Hydropower Project Annexure 6-A

DESIGN OF SPILLWAYAT AXIS CKoto Hydropower Project (Computations after Flood 2010)

Design: Ref: Larry W. Mays, Page 17.1 Revised

SI FPS

Max. Flood Level MFL = 812.00 m 2664.17 ft

Crest Level (FRL) C.L. = 807.00 m 2647.77 ft ;considering P=C.L. - R.B.L.

River Bed Level R.B.L. = 802.00 m 2631.36 ft

Width of River Section at crest = 800.00 m 2624.80 ft

U/S face = 1 Hz. 3 Vert.

Maximum Head Hmax. = 5.00 m 16.41 ft ; MFL - RBL, Larry Mays, Page 17.50

Designed Head Ho = 4.00 m 13.12 ft Ho = 0.75 to 0.8 Hmax.

Total head at any time including velocity head He = 5.00 m 16.41 ft For design, He = Ho

P = 5.00 m 16.41 ft ;C.L - R.B.L

Discharge Coefficient

P / Ho = 1.25

Basic Discharge Coefficient Co = 3.91 ;Fig 17.1, Larry W. Mays

He / Ho = 1.25

Discharge Coefficient C = 1.003 ;Fig 17.2, Larry W. Mays

1 Discharge Coefficient Correction for u/s Sloping face Cinc. / Cver. = 1.000 ;Fig 17.3, Larry W. Mays

2 Discharge Coefficient Correction for d/s appron = 1.00 ;Fig 17.4, Larry W. Mays

1


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3 Discharge Coefficient Correction fortailwater submergence = 1.00 ;Fig 17.5, Larry W. Mays

SI FPS

Discharge Coefficient C = 2.16 3.922

Effective Length of Spillway

Le = L' - 2 (NKp + Ka) He Bays Width of each bay

Net Length L' = 180.00 m 590.58 ft 18 10

No.of Piers N = 17.00 ft

Width of each pier B' = 2.10 m 6.8901 ft

Kp = 0.01 ;Page 17.2, Larry W. Mays

Ka = 0.10 ;Page 17.2, Larry W. Mays

Effective Length Le = 177.30 m 581.72 ft

Discharge at Head

Discharge at Head Ho(Ogee with broad crested) Qo = 2907.72 m3/sec 102700.2 ft

3/sec ; C = 2.05

Discharge at Head He (Ogee with broad crested) Qe = 4063.66 m3/sec 143527.9 ft

3/sec ; (from Flow 3D)

Discharge at Head He (Pure Ogee) Qe = 4291.79 m3/sec 151585.3 ft

3/sec

10000 year return period Q = 6466.00 m3/sec 228378.1 ft

3/sec

Discharge Rating Curves

Crest Geometry

Total spillway crest length L = 215.70 m 707.71 ft

2


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Unit discharge at design head Ho q = 18.84 m3

/sec/m 203 ft2

/sec

Approach velocity Va = 2.09 m/sec 6.87 ft/sec

Aprroach velocity head ha = 0.2233 m 0.733 ft

ha / Ho = 0.056 0.056

Parameters for the crest geometry are determined from Fig 17.9, Page 17.9, Larry W. Mays

K = 0.510

n = 1.823 Upstream slope ( 1 H : 3 V )

Shape of nappe upstream of the origion Xc / Ho = 0.233

Yc / Ho = 0.082

R1 / Ho = 0.559

R2 / Ho = 0.181

Xc = 0.93 m 3.06 ft

Yc = 0.33 m 1.08 ft Yc 806.67

R1 = 2.24 m 7.34 ft

R2 = 0.72 m 2.38 ft

Shape of nappe downstream of the origion

Y / Ho = - K ( X / Ho )n

;Ref: Page 17.8, Fig 17.9, Larry W. Mays

or Y = - (K / Hon-1

) Xn SI FPS

Y = 0.1630 Xn 0.0613 X

n Equ 1

d (Y) / dx = 1.11 ; (V / H)

Taking derrivative of Equ 1,

0.163 n X(n-1) = 1.11

3


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4

Location of the tangent point Xt = 4.97 m Xt = 16.30 ft

Yt = 3.03 m Yt = 9.93 ft

Yt = 803.97 m


7/39

ANNEXURE

6-B

DESIGN OF STILLING BASIN


8/39

Koto Hydropower Project Annexure-6B

1

DESIGN OF STILLING BASIN

Koto Hydropower Project (AT AXIS C) REVISED

RevisedRef: Larry W.Mays

Inputdata

Graphical / tabular values

Max. Discharge (Spillway) Q = 4063.66 cumecs 143527.9 cusec 6466 10000 year return period (cumecs)

Width of Spillway B = 215.70 m 707.7 ft ; including pier widths

Max. unit discharge q = 18.84 m2/sec 202.8 ft2/sec

Max. flood level M.F.L = 812.0 m 2664.2 ft

Crest Level of the Spillway C.L. = 807.0 m 2647.8 ft;above hz. Floor of stillingbasin

Slope of the spillway (1 V : z H ) z = 0.9

Head on Spillway Crest He = 5.00 m 16.4 ft

Basin floor level = 799 m 2621.5 ft

Design of Stilling Basin (Type) = IV (Modified) ; 2.5 < Froude No. < 4.5(Ref: Fig. 18.7, Page 18.15 of Larry W.Mays)

(Ref: Fig 9.41, epage 437, USBR)

Calculations

Z = m 2. ft

Total fall from reservior level to basinfloor 13 4 65

Conslting Fig 18.1 (Page 18.6 of Larry W. Mays) against Z and He

Va / Vt = 0. 79

Theoretical Velocity Vt = 14.36 m/sec 47.10 ft/sec

; Vt = ( 2g ( Z - Ho / 2 ))0.5

, Ref on Fig 18.1 (Page 18.6

W. Mays)


9/39

Koto Hydropower Project Annexure-6B

2

Actual Velocity Va = 13.93 m/sec 45.69 ft/sec

; Actual velocity = V1 = Velocity of flow entering into

the basin

D1 = 1.35 m 4.44 ft ; q /

=

V

Froude No. F1 3.82

Conjugate Depths RatioRef:

Paterka

TW = D2 = 6.67 m 21.88 ft

Velocity V2 = 0.26 m/sec 0.86 ft/sec

Froude No. F2 = 0. 30

Headloss in standing wave HL = 4.16 m 13.65 ft

Tail water Level = 806.27 m ; Basin floor Level + D2 x 1.05

Tail water Level (from HECRAS) = 806.3 m OK; from HECRASanalysis.

0.03

CHECK: TWL - TWLsb 3 - 5 = 14.49 Ref: Larry, W. Mays,Page 8.17

Water Acceleration Constant th = 1.48 secRef: Esha guides, Page147

Requirments of Penstocks = No Penstock Required

Discharge in Tunnel Q = 126cumecs

Tunnel diameter btwn reservoir and surgetank Dt = 7.0 m

Tunnel area btwn reservoir and surge tank At = 38.48 m2 (

D

2

)/4

Velocity in Tunnel Vt = 3.27 m/secTunnel length btwn reservoir and surgetank Lt = 1823 m

Min. net operating head on turbine H = 30.12 m

Min. head loss from reservoir to surge tankincluding tunnel velocity head H = 2.68 m ; as computed in "head losses - Koto" sheet

Head loss coefficient c = 0.25 ; H / Vt2


18/39

Koto Hydropower Project Annexure-6D

2

Min. surge tank area Ast =

474.8

5 m2

Ref: Larry, W. Mays,

Page 8.17Factor of safety FOS = 1.00

1 Surge tank area (with FOS of 1.5)Asurge =

474.8

5 m2

; 50% increase in area (Larry W. Mays page8.19)

2 Surge tank area Ast =980.2

8 m2 ; = 45 Dt

(10/3)/ Ho

Ref: Hydraulic Strs by P. Novak , ePage526

; with 1/n = 85 and FOS =1.5

Surge tank area (selected)

Asurg

e =

474.8

5 m2Diameter of tank area (selected) d = 24.59 m

Maximum Upsurge

r = 0.02 Ref: Hydraulic Strs by P. Novak , ePage 526

1 Max. upsurge Zmax. = 12.71 m

Head loss in tunnel Po = 1.84 m ; as computed in "head losses - Koto" sheet

K* .1= 0 4Z*max. = 0.91

2 Max. upsurge above operating levelZmax. = 11.10 m Ref: GTZ (Vol. Engineering Design), Page 112

Max. Z = Vt (At Lt / g As.c )0.5

- 0H

3

Max. upsurge bo = H / Q ( As g / (Lt /

At) )

0.5

= 0.211

Surge ratioZmax. /H = 8.75

Ref: Larry, W. Mays, Fig. 8.9, Page8.20

Maximum surge above operating level Zmax. = 23.45


19/39

ANNEXURE

6-E

TAILRACE CHANNEL DESIGN


20/39

Koto Hydropower Project Annexure-6E

TAILRACE CHANNEL DESIGN

Koto Hydropower Project

Selected

Tailrace having three channels

Unit No.

1

Unit No.

2

Unit No.

3

SingleTailrace

Designed Width of the Channel B = 7 m 7 m 7 m 15

Designed Depth of Channel D = 3.6 m 3.6 m 3.6 m 4

Side Slope z = 0(1 V : zH) 0

(1 V : zH) 0

(1 V : zH) 0

Topwidth T = 7 7 7 15

Manning's n n = 0.016 0.016 0.016 0.016

Length of cut and cover L = m m m

Longitudnal Slope S = 0.000333 m/m 0.000333 m/m 0.000333 m/m 0.000333

Calculations:

Velocity, V = 1/n R2/3

S1/2

Area A = 25.200 m2 25.200 m

2 25.200 m

2 60.000

Perimeter P = 14.200 m 14.200 m 14.200 m 23.000

Hydraulic Radius R = 1.775 m 1.775 m 1.775 m 2.609

Velocity V = 1.673 m/sec 1.673 m/sec 1.673 m/sec 2.163

Discharge Q = 42.16 m3/sec 42.16 m

3/sec 42.16 m

3/sec 129.78

1


21/39

ANNEXURE

6-F

TOTAL HEAD LOSSES FOR POWER


22/39

Koto Hydropower Project Annexure-6F

TOTAL HEAD LOSSES IN TUNNELSKOTO HYDROPOWER PROJECT

INPUT DATA

Power Tunnel Discharge Q = 4450.30 ft3/sec = 126 m3/sec

Headrace (Cut and Cover Conduit) Reach 1

No. of rectangular conduits N = = 3 No.

Conduit Discharge Q = 1483.43 ft3/sec = 42 m3/sec

Length L = 3608.91 ft = 1100 m

Width W = 14.76 ft = 4.5 m

Height H = 9.84 ft = 3 m

Longitudnal Slope S = 0.001

Not included in total headlosses i.e. d/s of sand trap

Mannings n n = 0.014

Headrace (Cut and Cover Conduit) Reach 2

No. of rectangular conduits N = = 3 No.

Length L = 314.96 ft = 96 m

Width W = 15.75 ft = 4.8 m

Height H = 10.50 ft = 3.2 m

1


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2

Longitudnal Slope S = 0.001


Power Tunnel

Length of Tunnel L = 6076.10 ft = 1852 m

Dia of TunnelD =

22.97 ft=

7 m

Hydraulic Radius r = 5.74 ft = 1.75 m

Velocity in Tunnel v = 10.73 ft/sec = 3.27 m/sec


Penstock

Length of Penstock L = 295.27 ft = 90 m

Dia of Penstock D 19.69 ft = 6.00 m


Velocity in Tunnel v = 13.35 ft/sec = 4.07 m/sec

g = 32.19 ft/sec2 = 9.81 m/sec2

Trashrack and Transition

Area of the trachrack = x m ( w x H)

Velocity through the net trashrack areaVn = 5.151 ft/sec = 1.57 m/sec


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3

Net area through the rack bars (an),Gross area of the racks and bars (ag)

Ratio of an/ag = 0.50

Radius of the bend No. 1Rb = 196.86 ft = 60.0 m

Angle of the bend No. 1 = = 55.0 degree

Radius of the bend No. 2Rb = 0 ft = 0.0 m

Angle of the bend No. 2 = = 0.0 degree

HEAD LOSSES CALCULATIONS

Total Head Losses =

Hf+ K trash+ He+ Kb + Kc +

K

exp + Kg

(Ref: Design of Small Dams, USBR, Page 469)

Reported losses

Trashrack Losses = 0.404 ft = 0.12 m 0.20

Entrance Losses = 0.074 ft = 0.02 m 0.10

Bend Losses = 0.193 ft = 0.06 m 0.10

Friction Losses

Cut and Cover Conduit = 0.302 ft = 0.09 m 0.20


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4

Power Tunnel = 6.030 ft = 1.84 m 1.90

Penstock = 3.609 ft = 1.10 m 1.10; 3.5m in penstock inseries.

Transition Losses = 0.098 ft = 0.03 m 0.10

Gate and valve Losses = 0.19 ft = 0.06 m 0.10

Total Head Losses = 10.229 f t = 3.32 m 3.80 m


26/39

ANNEXURE

6-G

DESIGN OF OUTLETS


27/39

Koto Hydropower Project Annexure-6G

DESIGN OF OUTLET WORKS

Koto Hydropower Project

Revised

Bottom Outlets:

Designed Width of the outlet B = 1.5 m

Designed Depth of the outlet D = 1.5 m

Max. Flood Level = 811.3 m

Invert Level of outlet = 802.5 mCentre point level of the outlet = 803.25 m

C = 0.79 mSlightly roundedentrance

Discharge per outlet Q = 22.3 cumecs

Velocity V = 9.9 m/sec

No. of outlets (undersluices) = 16.0

Total discharge through undersluices = 357.4 cumecs

Undersluices:

Designed Width of the outlet B = 1.0 m

Designed Depth of the outlet D = 1.0 m

Max. Flood Level = 811.3 m

Invert Level of outlet = 802.5 mCentre point level of the outlet = 803 m

C = 0.79 mSlightly roundedentrance

Discharge per outlet Q = 10.1 cumecs

Velocity V = 10.1 m/sec

No. of outlets (undersluices) = 4.0

Total discharge through undersluices = 40.3 cumecs

1


28/39

ANNEXURE

6-H

DESIGN OF DIVERSION ARRANGEMENTS


29/39

Koto Hydropower Project Annexure-6H

1

DESIGN OF DIVERSION ARRANGMENTS

Koto Hydropower Project (AT AXIS C) REVISED

Diversion Arrangements

Duration of project (Dry seasons) = 2

(Flood season) = 1

10year return period = 947 cumecs 33447.9 cusecs

Stage 1 (In first year) "right side of the river" will be made dry with construction of Coffer dam.

River bed level = 802.00 m 2631.36 ft

Top elevation of the Coffer dam = 805.00 m 2641.21 ft

Free board for Coffer dam = 0.50 m 1.64 ft

Water depth in diversion channel = 2.50 m 8.20 ft

Length of diversion channel = 65.00 m 213.27 ft

Velocity in diversion channel = 5.83 m/sec 19.12 ft/sec

Stage 2 (In 2nd year) "left side of the river" will be made dry with construction of Coffer dam.Top elevation of the Coffer dam = 809.00 m 2654.33 ft

Free board for Coffer dam = 0.50 m 1.64 ft

Top of concrete dam completed in stage 1 = 807.00 m 2647.77 ft

Water depth in diversion channel above dam = 1.50 m 4.92 ft

No. of undersluices completed in stage 1 = 5 No.

Discharge passing from all undersluices = 41.03 cumecs 1449.26 cusecs

Discharge to be passed above dam (overtop) = 905.97 cumecs 31998.6 cusecs

Length of diversion channel = 80.00 m 262.48 ftVelocity in diversion channel = 7.55 m/sec 24.77 ft/sec


30/39

ANNEXURE

6-I

CONCRETE BOX CHANNEL

FULL SUPPLY LEVELS (F.S.L)

AND

BED LEVELS (B.L)

Koto Hydropower Project Annexure-6I


31/39

KOTO HYDROPOWER PROJECTChannel Full Supply Levels (F.S.L) and Bed Levels

(B.L)

Distance F.S.L B.L

(m) (m) (m)

0 804.50 801.50

50 804.40 801.40

100 804.30 801.30

150 804.20 801.20

200 804.10 801.10

250 804.00 801.00

300 803.90 800.90

350 803.80 800.80

400 803.70 800.70

450 803.60 800.60

500 803.50 800.50

550 803.40 800.40

600 803.30 800.30

650 803.20 800.20

700 803.10 800.10

750 803.00 800.00

800 802.90 799.90

850 802.80 799.80

900 802.70 799.70

Koto Hydropower Project Annexure-6I


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1350 801.80 798.80

1400 801.70 798.70

1450 801.60 798.60

1500 801.50 798.50

1550 801.40 798.40

1600 801.30 798.30

1650 801.20 798.20

1700 801.10 798.10

1750 801.00 798.00

1800 800.90 797.90

1850 800.80 797.80

1900 800.70 797.70

1950 800.60 797.60

2000 800.50 797.50

2050 800.40 797.40

2100 800.30 797.30

2150 800.20 797.20

2200 800.10 797.10

2250 800.00 797.00

2300 799.90 796.90

2350 799.80 796.80

2400 799.70 796.70

2450 799.60 796.60

2500 799.50 796.50


33/39

ANNEXURE

6-J

DESIGN OF SAND TRAP


34/39

Koto Hydropower Project Annexure-6J

1

HYDRAULIC CALCULATION FOR SANDTRAP

KOTO HYDROPOWER PROJECT

Q (m3/s) = 126 m3/s

Chambers 6 Nos.

Q/Chamber = 21.00 m3/s

d (mm) = 0.20 mm

K(Strickler) = 71.43 n = 0.014

Gs 2.65

Assume

Coefficient a = 44

Max. flow velocity in sand trap, V (m/s) = 0.20 m/s cm/sec

Calculations:

Width (B) = 9.20 30.18 ft Assume

Depth (H) = 11.41 37.44 ft

= H0.5

Vs' [m/s] = 0.0257 settling velocity in standing water

Alphas = 0.0391 0.132/SQRT(H)

Vs [m/s] = 0.0179 settling velocity in flowing water Vs'-V

Ls = 127.30 417.66 ft HV/VsSelected Length(m) = 127.3 417.66 ft

Time Taken by the particle to pass the basin = 636.5 sec

Time Taken by the particle to settle down = 636.5 sec

Checks

Ls = 8*B = 73.60 m

H/B 1.24 O.K.H > 1.25B (H should be greater than ORequal to 1.25B)

Vcr (Shileds)= 0.737 m/s From Manning formula

Vcr (Camp)= 0.200 m/s O.K.

( Vcr (shields) >

V )

davd


35/39


B 9.20 mCheck

b 4.10 m b = (B-w) / 2

h 4.10 m

w 1.00 m

Slope of sedimentation tank 3.00 %

Depth at the end with assumed slope 15.23 m

Mean area 122.57 m2 B

Mean velocity 0.1713

Critical velocity 0.7368Check

Check mean vel < critical vel O.K.

U/s Transition

In order to achieve a uniform approach of water over the whole chamber

width, the transition section is to be designed according to following H X-SECTIONformula.

B = B1+2 (L1* tan alpha)

Width of headrace channel B1 16.20 m

Angle of inclination of transition in deg 30

0.524 h

Tan Alpha 0.578Thickness of inner walls 0.6 m b

Thickness of outer walls 0.6 m

Total width of sedimentation tank 59.40 m w

Width of sedimentation tank B 58.20 m

without outer walls

Transition length L1 36.35 m

L/3 42.43 m

2


36/39


Check L1 < L/3 O.K. 65.23

D/s Transition

In order to achieve a uniform approach of water over the tunnel

dia, the d/s transition section is to be designed according to following

formula.

B = B1+2 (L1* tan alpha)

Width of Tunnel (Dia of Tunnel) B' 18.40

Angle of inclination of transition in deg 300.524

Tan Alpha 0.578

Width of sedimentation tank B 58.20 m

without outer walls

Transition length L1 34.45 m

L/3 42.43 m

Check L1 < L/3 O.K. 67.43

Total Length of Sand Trap 198.11 m ; including transitions

Dimensions of flushing trap ;under sand trap

Min. width w 1.00 m

Height h 4.10 m

Dimensions of flushing channel (F.C) Rectangular

Note : The flushing channel is so designed that at a time flushing of 3 chambers will be done simultaneously.

From left side, one chamber will be flushed from Ist and 2nd, 2nd chamber will be flushed from 3rd and 4th and 3rdchamber will be flushed from 5th and 6th chamber.

F.C in front of Ist and 2nd chambers

Minimum operating level (MOL) 780.97 m

Invert level of channel 776.87 m

Width w 1.00 m dimensions of individual 6 gates

Height h 0.50 m

Area A 0.50 m

2

3


37/39


4

As outlet, Velocity at intake V 7.13 m/sec Coeff. C 0.82

Discharge Q 3.56 m3

/sec ;(square cornered entrance)

F.C in front of 3rd and 4th chambers

Discharge of 2 no. F.Cs Q 7.13 m3/sec

Width w 2.00 m

Height h 0.50 m

Area A 1.00 m2

As outlet, Velocity at intake V 7.13 m/sec ;pressurized conduit flow

F.C in front of 5th and 6th chambers

Discharge of 2 no. F.Cs Q 10.69 m3/sec

Width w 3.00 m

Height h 0.50 m

Area A 1.50 m2

As outlet, Velocity at intake V 7.13 m/sec ;pressurized conduit flow

Spill Section

Width B 70 m

Height H 0.41 m

Discharge coefficient C 1.7 ; broad crested

Discharge Q 31.24 m3/sec

Rectangular Area of Flow for each chamber 140.14 m2

For trapezoidal chamber

No. of chambers 6 Nos.

Selected internal base width 8.50 m

Top internal width of chamber 9.90

Maximum Height of chamber 15.23

Area of chamber 140.14

Height of collecting chamber 3.75


38/39

ANNEXURE

6-K

BACK WATER SURFACE PROFILE


39/39

800

802

804

806

808

810

812

814

816

818

0 200 400 600 800 1000 1200 1400

E

levation(m)

Distance upstream of Weir (m)

Koto Hydropower ProjectWATER SURFACE PROFILE (W.S.P) FOR 1000 YEARS FLOOD (Q1000) AT WEIR AXIS C

R.B.L Unifrom Flow F.R.L Back Water Surface Profile

Length of W.S.P for Q1000 = 879 m

River Bed Level

Weir Crest Level

W.S.P for Q1000 with 5m High Weir

W.S.P for Q1000 with Natural Conditions

annex 6 final

Documents