The formulae used for the detailed hydraulic calculations are been taken as the deciding level for

calculating the plant

hydraulics.

Gravity flow in open channel

V=(1/n)*R^(2/3)*(Hf/L)^0.5
V= velocity in mps
n =Mannings n
R= Hydraulic radious in m
Hf= Head loss in m
L= Length in m
Flow through Pipe
v = 0.849*C*R^(0.63)*S^0.54
v = Velocity
C = Hazen-Williams coefficient = 100
R= Hydraulic radious in m
S = Slope of Hydraulic Gradient
Losses in pipe specials & fittings
Hf= K*V2/2g
K= Constant
For Entry K=0.5
For Exit K = 1.0
V= velocity through pipe in m/s
Losses through weir
Q = 0.5445*Ce*g^.5*b*h^1.5
Q = Discharge in Cum /Sec.
Ce = Coefficient of effective discharge = 0.864
b = Width of weir
h = Head loss over the weir
Losses in submerged openings and Sluice gates
h= ( v*k)2 / 2g
k = Constant = 0.62

Avg. flow 2025 20 MLD

20000 m3/d
833.33 m3/h
13.9 m3/min
0.2 m3/sec

Peak flow 2025 45 MLD

45000 m3/d
1875 m3/h
31.3 m3/min
0.5 m3/sec

Average flow 2040 30 MLD

30000 m3/d
1250 m3/h
20.8 m3/min
0.35 m3/sec

Peak flow 2040 68 MLD

68000 m3/d
2833 m3/h
47.2 m3/min
0.79 m3/sec

Top level of water in existing discharging Drain* 235.530 m

Peak flow 1 of 12
 *This level has been taken from DPR prepared by IRAM (Nov.'95)

Assumed Final IL of Final Effluent Channel 235.530 m

Top level of water at outlet of Final Effluent Channel
(IL + Depth of water in Final Effluent Channel) 236.330 m

1 Final Effluent channel

Width of drain 1.4 m
Length 240 m
N value 0.013
Assumed Depth of flow 0.8 m
Velocity (v) 0.70 m/sec
area 1.12 m2
Perimeter, P 3
a/p 0.37
Slope (by Mannings Formula), s 0.0003
Head loss (HL = S x L)
HL 0.075 m
TWL of Drain at start of Effluent Channel / ds of flume 236.405 m

2 Pipe from Parshall flume to discharge channel

Dia of pipe 0.7 m
velocity in pipe 1.4 m/sec
Length of pipe 10 m
a. Exit Loss from Parshall flume 0.093 m
b. Entry Loss at Effluent channel 0.047 m
Friction loss (Hazen william's equation), V=0.849*C*R^0.63*S^0.54
c. Friction loss HL 0.036 m
Total losses (a+ b+c) 0.176 m
TWL for outlet of Parshall Flume 236.581 m

Losses within Parshall Flume Unit

Width at u/s 1.500 m
Throat width of flume 0.300 m
Discharge 0.521 m3/sec

hc = cube root(Q x Q / B2/g)

hc = 0.678 m

Vc = 2.562 m/sec

hu3 - 1.0125293278
hu3-1.226 hu2 + 0.0109 = 0
Hu 1.219 m
check 0.314
HL 0.542
TWL for upstream of Parshall Flume 237.123 m

3 Loss in pipe from chlorine contact basin to Parshall Flume

Dia of pipe 0.7 m
velocity in pipe 1.4 m/sec
Length of pipe 10 m
a. Exit Loss from Chlorine contact tank 0.093 m
b. Entry Loss at Parshall Flume 0.047 m

Peak flow 2 of 12
 Friction loss (Hazen william's equation), V=0.849*C*R^0.63*S^0.54
c. Friction loss HL 0.036 m
Total losses (a+b+c) 0.176 m
TWL for outlet of Chlorine Contact Basin 237.299 m

4 Loss in Weir in outlet chamber of chlorine contact basin

Width of Weir 3.5 m
Head (h) 0.137 m
As per CPHEEO additional 0.050 m drop to be provided for weir
head loss calculation 0.05 m
TWL at outlet of Chlorine Contact Basin 237.485 m

5 Loss in Weir in inlet chamber of chlorine contact basin

Width of Weir 3.5 m
Head (h) 0.137 m
As per CPHEEO additional 0.050 m drop to be provided for weir
head loss calculation 0.05
TWL at inlet of Chlorine Contact Basin 237.672 m

6 Loss in pipe from Sequential Batch Reactor to chlorine contact basin

Dia of pipe 0.7 m
velocity in pipe 1.4 m/sec
Length of pipe 12 m
a. Exit Loss from SBR 0.093 m
b. Minor Loss (2 nos. 90 degree elbow) 0.056 m
c. Entry Loss at Chlorine Contact Basin 0.047 m
Friction loss (Hazen william's equation), V=0.849*C*R^0.63*S^0.54
d. Friction loss HL 0.043 m
Total losses (a+b+c+d) 0.239 m
TWL for outlet of SBR 237.911 m
Difference of Lvl b/w max and min water lvl in SBR 2.450 m
TWL at entry of SBR 240.361 m

7 Loss in pipe from flow splitting to Sequential Batch Reactor

Dia of pipe (2 nos. pipes for two SBR inlets) 0.5 m
velocity in pipe 1.3 m/sec
Length of pipe 14 m
a. Exit Loss from Flow Splitting 0.090 m
b. Entry Loss at SBR 0.045 m
Friction loss (Hazen william's equation), V=0.849*C*R^0.63*S^0.54
c. Friction loss HL 0.072 m
Total losses (a+b+c) 0.206 m
TWL for outlet of flow splitting 240.568 m

8 Loss in Weir at inlet of flow splitting

Width of Weir 1.5 m
Head (h) 0.316 m
As per CPHEEO additional 0.050 m drop to be provided for weir
head loss calculation 0.05
TWL in flow splitting 240.934 m

9 Loss by sluice gate before flow splitting

Size of sluice gate (1m x 1m) 1 sqm
Velocity (v) 0.79 m/sec
k 0.62
HL 0.012 M
TWL at sluice gate before flow splitting 240.946 m

Peak flow 3 of 12
 10 Loss in channel from Grit chamber to flow splitting
Width of drain 1m
Length 5m
N value 0.013
Assumed Depth of flow 1.2 m
Velocity (v) 0.66 m/sec
area 1.2 m2
Perimeter, P 3.4
a/p 0.35
Slope (by Mannings Formula), s 0.0003
Head loss (HL = S x L)
HL 0.001 m
TWL at downstream of grit chamber 240.947 m

11 Losses in rotating grit chamber 0.1 m

TWL at upstream of Grit chamber 241.047 m

12 Loss by sluice gate Before Grit Chamber

Size of sluice gate (1m x 1m) 1 sqm
Velocity (v) 0.79 m/sec
k 0.62
HL 0.012 M
TWL at sluice gate before Grit Chamber 241.059

13 Loss in channel from Screen to sluice gate of Grit chamber

Width of Screen channel 1m
Length 5m
N value 0.013
Assumed Depth of flow 1.2 m
Velocity (v) 0.66 m/sec
area 1.2 m2
Perimeter, P 3.4
a/p 0.35
Slope (by Mannings Formula), s 0.0003
Head loss (HL = S x L)
HL 0.001 m
TWL at downstream of Screen 241.061 m

14 Losses in screen
Peak Flow for 2040 ( for one channel) 34 MLD
34 MLD in One channel, Total flow = 68 MLD in two channels
0.39 m3/sec
Depth of flow in sewer at peak flow 1.2 m
velocity in sewer at peak design flow 1 m/sec
Drop of screen chamber floor with respect to sewer invert 0m
Assumed width of rectangular bars 10 mm
Clear spacing between bars 6 mm

i ) Design of Bar Racks

Assume Depth of flow in screen chamber 1.2 m
Velocity of flow through rack openings 1 m/s
Clear area of openings through the rack Q/V
0.39 sqm
Clear width of openings through rack 0.33 m
Providing clear spacings 6.00 mm
no of clear spacings 55.00

Peak flow 4 of 12
 Number of bars 54.00
Dia of each bar 10.00 mm each
Total width of the screen chamber 0.87 m
Say 1m
ii ) Actual depth of Flow in Screen chamber at peak flow
By Bernoulli's Theorem b/w sections 1 &2
Z1 + d1 + ( V1 * V1 / 2g) = Z2 + d2 + (V2 * V2 /2g) + hL

Taking floor of the screen chamber as datum (Z2=0) and assuming

Ke = 0.3 for coefficient of expansion.

1.203 =
0.008
1.203 = 0.0 + d2 + 0.010 / d22 + 0.015 - 0.003 / d22
Equation for calculation of d2
d23 - 1.187 d22 + 0.007 = 0
Assumed value of d2 1.183
Check 0.00
V2 = 0.33 m/s
iii) Velocity through clear opening of Bar rack
V= 1.01 m/s
iv) Head Loss through Bar rack
h = 0.0728*(V2-V22), h= 0.066 m
Using Kirschmers Formula, h = β(W/b)^(4/3) x hv sinΦ
h= 0.227 m
V) Determine Depth and Velocity of Flow d/s of Bar rack
when Bar rack is clean
Z2+d2+V22/2g = Z3+d3+V32/2g+h
1 = 0.0 + d3 + 0.010/d32 + 0.065
Equation for calculation of d3
d33 - 1.122 d32 + 0.010 = 0
Assumed value of d3 1.11
Check 0.00
V3 = 0.35 m/s
vi) Head Loss through Bar rack at 50% clogging
h50%= 0.0728 ((Velocity through clogged rack) 2 - V22)
h50%= 0.419 - 0.014+0.406/d2'2
d2' + (V2')2/2g = d3+v22/2g+h50%
d2' + 0.010 / d2'2 = 1.11 + 0.008 + 0.406 / d2'2
Equation for calculation of d2'
d2'3 - 1.122 d2'2 - 0.396 = 0
Assumed value of d2' 1.340
Check 0.01
V2' = 0.29 m/s
h50%= 0.22 m
TWL at upstream of Screen 241.285 m

15 Loss in channel from sluice gate of influent sump (Elevated Inlet Chamber) to screen
Width of Screen Channel 1m
Length 5m
N value 0.013
Assumed Depth of flow 1.2 m
Velocity (v) 0.66 m/sec

Peak flow 5 of 12
 area 1.2 m2
Perimeter, P 3.4
a/p 0.35
Slope (by Mannings Formula), s 0.0003
Head loss (HL = S x L)
HL 0.001 m
TWL at downstream of influent sump sluice gate 241.287 m

16 Loss by influent sump sluice gate

Size of sluice gate (1m x 1M) 1 sqm
Velocity (v) 0.787 m/sec
k 0.62
HL 0.012 m
TWL in influent sump 241.299 m

TOTAL HEAD LOSS 5.769 M

Peak flow 6 of 12
 Hydraulic design (Avg. Flow)

The Hydraulic calculation for Average flow has been done to check the velocities at average flow. The
formulae used for the detailed hydraulic calculations are been taken as the deciding level for calculating the
plant hydraulics.
Gravity flow in open channel
V=(1/n)*R^(2/3)*(Hf/L)^0.5
V= velocity in mps
n =Mannings n
R= Hydraulic radious in m
Hf= Head loss in m
L= Length in m
Flow through Pipe
v = 0.849*C*R^(0.63)*S^0.54
v = Velocity
C = Hazen-Williams coefficient = 100
R= Hydraulic radious in m
S = Slope of Hydraulic Gradient
Losses in pipe specials & fittings
Hf= K*V2/2g
K= Constant
For Entry K=0.5
For Exit K = 1.0
V= velocity through pipe in m/s
Losses through weir
Q = 0.5445*Ce*g^.5*b*h^1.5
Q = Discharge in Cum /Sec.
Ce = Coefficient of effective discharge = 0.864
b = Width of weir
h = Head over the weir
Losses in submerged openings and Sluice gates
h= ( v*k)2 / 2g
k = Constant = 0.62

Avg. flow 2025 20 MLD

20000 m3/d
833.33 m3/h
13.9 m3/min
0.2 m3/sec

Peak flow 2025 45 MLD

45000 m3/d
1875 m3/h
31.3 m3/min
0.5 m3/sec

Average flow 2040 30 MLD

30000 m3/d
1250 m3/h
20.8 m3/min
0.35 m3/sec

Peak flow 2040 68 MLD

68000 m3/d
2833 m3/h

Avg flow 7 of 12
 47.2 m3/min
0.79 m3/sec

Top level of water in existing discharging Drain* 235.530 m

*This level has been taken from DPR prepared by IRAM
(Nov.'95)

Assumed Final IL of Final Effluent Channel 235.530 m

Top level of water at outlet of Final Effluent Channel
(IL + Depth of water in Final Effluent Channel) 236.030 m

1 Final Effluent channel

Width of drain 1.4 m
Length 240 m
N value 0.013
Assumed Depth of flow 0.5 m
Velocity (v) 0.5 m/sec
area 0.7 m2
Perimeter, P 2.4
a/p 0.29
Slope (by Mannings Formula), s 0.0002
Head loss (HL = S x L)
HL 0.052 m
TWL of Drain at start of Effluent Channel / ds of flume 236.082 m

2 Pipe from Parshall flume to discharge channel

Dia of pipe 0.7 m
velocity in pipe 0.6 m/sec
Length of pipe 10 m
a. Exit Loss from Parshall flume 0.018 m
b. Entry Loss at Effluent channel 0.009 m
Friction loss (Hazen william's equation), V=0.849*C*R^0.63*S^0.54
c. Friction loss HL 0.008 m
Total losses (a+ b+c) 0.036 m
TWL for outlet of Parshall Flume 236.118 m

Losses within Parshall Flume Unit

Widht at u/s 1.500 m
Throat width of flume 0.300 m
Discharge 0.231 m3/sec

hc = cube root(Q x Q / B2/g)

hc = 0.397 m

Vc = 1.945 m/sec
h -0.59 hu + 0.0012 = 0
u
3 2

Hu 0.587 m
check 0.000
HL 0.190
TWL for upstream of Parshall Flume 236.307 m

Avg flow 8 of 12
 3 Loss in pipe from chlorine contact basin to Parshall Flume
Dia of pipe 0.7 m
velocity in pipe 0.6 m/sec
Length of pipe 10 m
a. Exit Loss from Chlorine contact tank 0.018 m
b. Entry Loss at Parshall Flume 0.009 m
Friction loss (Hazen william's equation), V=0.849*C*R^0.63*S^0.54
c. Friction loss HL 0.008 m
Total losses (a+b+c) 0.036 m
TWL for outlet of Chlorine Contact Basin 236.343 m

4 Loss in Weir in outlet chamber of chlorine contact basin

Width of Weir 3.5 m
Head (h) 0.080 m
As per CPHEEO additional 0.050 m drop to be provided for
weir head loss calculation 0.05 m
TWL at outlet of Chlorine Contact Basin 236.473 m

5 Loss in Weir in inlet chamber of chlorine contact basin

Width of Weir 3.5 m
Head (h) 0.080 m
As per CPHEEO additional 0.050 m drop to be provided for
weir head loss calculation 0.05
TWL at inlet of Chlorine Contact Basin 236.602 m

6 Loss in pipe from Sequential Batch Reactor to chlorine contact basin

Dia of pipe 0.7 m
velocity in pipe 0.6 m/sec
Length of pipe 12 m
a. Exit Loss from SBR 0.018 m
b. Minor Loss (2 nos. 90 degree elbow) 0.011 m
c. Entry Loss at Chlorine Contact Basin 0.009 m
Friction loss (Hazen william's equation), V=0.849*C*R^0.63*S^0.54
d. Friction loss HL 0.010 m
Total losses (a+b+c+d) 0.048 m
TWL for outlet of SBR 236.651 m

TWL at entry of SBR (same as Peak Flow TWL) 240.361 m

7 Loss in pipe from flow splitting to Sequential Batch Reactor

Dia of pipe (2 nos. pipes for two SBR inlets) 0.5 m
velocity in pipe 0.6 m/sec
Length of pipe 14 m
a. Exit Loss from Flow Splitting 0.018 m
b. Entry Loss at SBR 0.009 m
Friction loss (Hazen william's equation), V=0.849*C*R^0.63*S^0.54
c. Friction loss HL 0.016 m
Total losses (a+b+c) 0.043 m
TWL for outlet of flow splitting 240.404 m

8 Loss in Weir at inlet of flow splitting

Width of Weir 1.5 m
Head (h) 0.183 m

Avg flow 9 of 12
 As per CPHEEO additional 0.050 m drop to be provided for
weir head loss calculation 0.05
TWL in flow splitting 240.637 m

9 Loss by sluice gate at flow splitting

Size of sluice gate (1m x 1M) 1 sqm
Velocity (v) 0.35 m/sec
k 0.62
HL 0.002 M
TWL at sluice gate before flow splitting 240.640 m

10 Loss in channel from Grit chamber to flow splitting

Width of drain 1m
Length 5m
N value 0.013
Assumed Depth of flow 0.8 m
Velocity (v) 0.43 m/sec
area 0.8 m2
Perimeter, P 2.6
a/p 0.31
Slope (by Mannings Formula), s 0.0002
Head loss (HL = S x L)
HL 0.0008 m
TWL at downstream of grit chamber 240.641 m

11 Losses in rotating grit chamber 0.1 m

TWL at upstream of Grit chamber 240.741 m

12 Loss by sluice gate Before Grit Chamber

Size of sluice gate (1m x 1m) 1 sqm
Velocity (v) 0.35 m/sec
k 0.62
HL 0.002 M
TWL at sluice gate before Grit Chamber 240.743

13 Loss in channel from Screen to sluice gate of Grit chamber

Width of Screen channel 1m
Length 5m
N value 0.013
Assumed Depth of flow 0.8 m
Velocity (v) 0.43 m/sec
area 0.8 m2
Perimeter, P 2.6
a/p 0.31
Slope (by Mannings Formula), s 0.0002
Head loss (HL = S x L)
HL 0.0008 m
TWL at downstream of Screen 240.744 m

14 Losses in screen
Avg Flow for 2040 ( for one channel) 15 MLD
15 MLD in One channel, Total flow = 30 MLD in two channels
0.17 m3/sec

Avg flow 10 of 12
 Depth of flow in sewer at Avg flow 0.8 m
velocity in sewer at Avg design flow 1 m/sec
Drop of screen chamber floor with respect to sewer invert 0m
Assumed width of rectangular bars 10 mm
Clear spacing between bars 6 mm

i ) Design of Bar Racks

Assume Depth of flow in screen chamber 0.8 m
Velocity of flow through rack openings 1 m/s
Clear area of openings through the rack Q/V
0.17 sqm
Clear width of openings through rack 0.22 m
Providing clear spacings 6.00 mm
no of clear spacings 36.17
Number of bars 35.17
Dia of each bar 10 mm each
Total width of the screen chamber 0.57 m
Say 1m
ii ) Actual depth of Flow in Screen chamber at Avg flow
By Bernoulli's Theorem b/w sections 1 &2
Z1 + d1 + ( V1 * V1 / 2g) = Z2 + d2 + (V2 * V2 /2g) + hL

Taking floor of the screen chamber as datum (Z2=0) and

assuming Ke = 0.3 for coefficient of expansion.

0.803 = 0.0 + d2 + 0.001 / d22 + 0.015 - 0.0003 / d22

Equation for calculation of d2
d23 - 0.787 d22 + 0.001 = 0
Assumed value of d2 0.786
Check 0.00
V2 = 0.22 m/s
iii) Velocity through clear opening of Bar rack
V= 1.02 m/s
iv) Head Loss through Bar rack
h = 0.0728*(V2-V22), h= 0.072 m
Using Kirschmers Formula, h = β(W/b)^(4/3) x hv sinΦ
h= 0.228 m
V) Determine Depth and Velocity of Flow d/s of Bar rack
when Bar rack is clean
Z2+d2+V22/2g = Z3+d3+V32/2g+h
1 = 0.0 + d3 + 0.001/d32 + 0.073
Equation for calculation of d3
d33 - 0.714 d32 + 0.001 = 0
Assumed value of d3 0.71
Check 0.00
V3 = 0.24 m/s
vi) Head Loss through Bar rack at 50% clogging
h50%= 0.0728 ((Velocity through clogged rack)2 - V22)
h50%= 0.186 - 0.002+0.185/d2'2
d2' + (V2')2/2g = d3+v22/2g+h50%
d2' + 0.001 / d2'2 = 0.712 + 0.002 + 0.185 / d2'2

Avg flow 11 of 12
 Equation for calculation of d2'
d2'3 - 0.714 d2'2 - 0.184 = 0
Assumed value of d2' 0.93
Check 0.00
V2' = 0.19 m/s
h50%= 0.21 m
TWL at upstream of Screen 240.958 m

15 Loss in channel from sluice gate of influent sump to screen

Width of Screen Channel 1m
Length 5m
N value 0.013
Assumed Depth of flow 0.8 m
Velocity (v) 0.43 m/sec
area 0.8 m2
Perimeter, P 2.6
a/p 0.31
Slope (by Mannings Formula), s 0.0002
Head loss (HL = S x L)
HL 0.0008 m
TWL at downstream of influent sump sluice gate 240.958 m

16 Loss by influent sump sluice gate

Size of sluice gate (1m x 1M) 1 sqm
Velocity (v) 0.347 m/sec
k 0.62
HL 0.002 m
TWL in influent sump 240.961 m

TOTAL HEAD LOSS 5.431 M

Avg flow 12 of 12