WATER & WASTEWATER
ENGINEERING
Water Supply Engineering
Lecture No. 3
Surface Water Collection Works
Water Supply System
• Components
1. Collection Works
2. Purification Works
3. Distribution Works
River
LLP
Mixing
Flocculation
Sedimentation
Filtration
Disinfection
HLP
Intake
Water
Treatment
Plant
(WTP)
Pipe Network
Collection Works
• 1. Intake Structure The basic function of the
intake structure is to help in safely withdrawing
water from the source and then to discharge this
water into the withdrawal conduit (normally
called intake conduit), through which it flows up
to water treatment plant(WTP).
• 2. Sump In which water is collected to be
pumped to water treatment plant.
• 3. Pump Through which water is pumped to
water treatment plant.
Collection Works
• Intakes consist of the opening, strainer and
the conduit conveying the water , usually by
gravity, to a well sump.
• From the well the water is pumped to the
treatment plant
Intake Types
Factors affecting choice of intake type:
1. Water width
2. Water depth
3. Navigation
4. Fluctuation in water level
Intake Types
1- shore intake
2- pipe intake
3- Tower intake
4- submerged intake
Factors Governing Location of Intake
1. At a straight part of the canal to avoid silting
and scouring zones.
2. Upstream any source of pollution.
3. Fix a prohibited area 150 m upstream and 50
m downstream the intake location.
4. Away from the surface to avoid floating
materials and away from the bottom to avoid
fine materials.
Design of Shore Intake
• Design capacity:
pop. × qav. × 1.4 × 1.1
Qd =
1000 × working hrs of LLP × 60 × 60
Design of intake conduit:
Qd = A × V × no
Assume V = 1 m/sec.
Then,
Qd = (ΠD2/4) × 1 × no
No. of intake conduits < 2
Get D, V actual
Design of Shore Intake
• Design of sump:
Qd = V / T
Assume T = 5 - 15 min.
V = Qd × T
Get V
V=L×B×d
Assume d = 1 . 0 - 3 . 0 m
L=n×S
n: no. of pumps S = 2 - 3 m
Get B
B<2m
Design of Shore Intake
Design of Pump House:
Dimensions
• L1 = L + 2 m
• B1 = L1 / 2
Pumps
• HP = γ × Qd × Hm
75 × η
• Hm = Hd + Hs
γ = 1 Q= Lit
γ = 1 Q= m3/sec
Qd= 1.4 Qavg
Design of Shore Intake
• Hd is the height from mixing tank W.L to the
axis of the pump
• Hs is the height from the axis of the pump to
the W.L of the sump
Hm ≈ 3m at least
Design of Shore Intake
• Σ losses = Screen losses + Hfriction + inlet & outlet
losses
• Screen losses = 0.1 m
• Hfriction = 4 × f × L × Vact2
( Intake conduit)
2 × g × Dcom
• Inlet & outlet losses = 1.5 × Vact2
2×g
L= (30-70) cm