The document outlines the design specifications for a trapezoidal sarda type fall, including details for upstream (u/s) and downstream (d/s) wing walls, bed pitching, and cistern design. Key dimensions such as lengths, slopes, and crest levels are provided to ensure proper construction and functionality. Additional aspects discussed include the impervious floor, d/s side and bed protection, and the characteristics of various components of the system.

1. Trepezoidal Sarda type fall
Straight glacis fall
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2. u/s wing walls :
D/s wing walls :
D/s *bed pitching :
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4. Radius = 5 to 6 times H
= 5 x 0.83 to 6 x 0.83
= 4.15 to 4.98 m
Say R = 4.50 m
Provide u/s wing walls having
segmental portion with radius 4.5 m
and subtending an angle of 60°, at the
centre and starting from the u/s edge
of the crest wall.
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6. Length of d/s wing wall with
vertical face
= 6 H • HL
= 6-7 0.83 x 1.5
= 6.70 m
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8. Length of warped wing with a splay
of 1 in 3 = height * splay = 2.5 * 3
= 7.5 m
Total length of d/s wing wall = 6.70
+ 7.5 = 14.2 m.
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9. Length of d/s bed pitching
= 9 + 2Hl
= 9 + 2 x 1.5
= 12 m
Provide horizontal pitching up to
the end of masonry wing walls for a
length of 6.3 m and then sloping at 1
in 10 for length of 6 m.
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10. Wingwall
103.77
12 M
PITCHING
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14. FLUMED
FALL
UNFLUMED
FALL
METER
FALL
NONMETER
FALL
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15. 1. Crest design
2. Cistern design
3. Impervious floor
4. u/s wing walls
5. d/s wing walls
6. d/s side protection
7. Roughening devices
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20. Length of crest = width of bed (for
unflumed fall)
L = 35.0 m
For non-meter fall, narrow crest is
provided.
Discharge Q is given by :
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21. H = 0.85 m
R.L. of crest = u/s FSL – H
= 203.5 – 0.85
= 202.65 M
height of crest above u/s bed,
= R.L.of crest – U/S bed level
= 202.65 - 201.5 = 1.15
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22. Crest width for non meter fall
= (2/3) H
= (2/3) 0.85
= 0.57
The d/s glacis is provided in a slope of
2 : 1
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23. Compare it with d/s bed level
because as we know cistern is
always below d/s bed level.
Ef2 can be obtained from blench
curve from available q and Hl
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d/s bed level
u/s bed level
cistern level
0.25 ef2

26. d/s TEL = d/s FSL + Ha =202 + 0.02
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27. d/s bed RL is 200 m which is lower
than obtained cistern level.
So provide minimum depth of
cistern = 0.25 Ef2 = 0.25 (1.40) =
0.35 m.
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28. Length of cistern = 5 ef2 to 6 ef2
= 5(1.40) to 6 (1.40)
= 7.0 to 8.4 m
Provide length of cistern 8 .0 m
The cistern is joined to the d/s bed of
the channel with a slope of 5 : 1.
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d/s bed level
u/s bed level
cistern level
0. 35 m
8.0 m
5 in 1

30. Assuming 0.6 m additional cutoff
depth.
u/s cutoff depth = D1/3 + 0.6
D/S cutoff depth = D2/2 + 0.6
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d/s bed level
u/s bed level
cistern level
0. 35 m
8.0 m
5 in 1
0.2 m
Deflector
wall
1.6 m
1.40 m

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35. Provide total horizontal length of
impervious flow = 20.60 m
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d/s bed level = 200
u/s bed level
= 201.5
cistern level =
199.65
8.0 m
1.6 m
1.40 m
crest level =
202.65
0.5 IN 1
L = b
Lu = total length – d/s glacis – u/s glacis – crest width

37. Provide total horizontal length of
impervious flow = 20.60 m
crest width = 0.55 m
horizontal length of u/s glacis =
(202.65 - 201.5) x 0.5 = 0.58 m
horizontal length of d/s glacis =
(202.65 - 199.65) x 2 = 6.0 m
length of cistern = 8 m
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38. (a) u/s cutoff wall
d{ = 1.30 m
b = 20.60 m
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39. Assume a thickness of 0.4 m at the
end of u/s floor
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41. (b) d/s cutoff
d2 = 1.60 m
b = 20.6 m
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42. Assume thickness of 0.5 m at the
end of d/s floor.
Neglecting effect of mutual
interference.
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44. ib) At 3 m from the toe of glacis :
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45. (2) D/s wing walls :
Provide d/s wing walls upto the end of the
d/s floor and then join them to the return
walls.
Top level of wing wall = 202 + 0.5 = 202.5
m.
d/s Bed Protection :
No bed protection is required as a deflector
has been provided,
d/s Side Protection :
Length of side protection = 3D2 = 3 x 2= 6
m
Provide 20 cm thick brick side pitching
over 10 cm ballast for a length of
6 m at a slope of 1 : 1 beyond the d/s
impervious floor.
3/20/2014
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ASST. PROF. DIET
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