intakes structures ......................................... .pptx

Collection &Conveyance of Water
Unit-II
BTCI05006/ MBCI05006

Collection & Conveyance of Water
Unit-II

Syllabus
• Collection and conveyance of water: Types of intake structure, design
of intake structure, estimation of fluid flows, engineering
requirements of conduits with respect to their performance, types of
conveyance system, hydraulic design of conveyance conduits, various
materials of pipes, appurtenances, and issues associated with
conveyance of water.
• Pumps for lifting of water: Types of pumps, selection of pumps,
design of pumping main for conveyance of water, economical
diameter of pumping main, pumping station

Introduction
•In any water supply project the first step is to select
the source of water from which water is drawn. The
device Installed for the purpose of drawing water
from the source of water are calledIntakes

Intake Structure
• Thebasic function of intake structure is to help in safely withdrawing
water from the source and then to discharge this water in to the
withdrawal conduit, through which it reaches the water treatment
plant.
• It is constructed at the entrance of the withdrawal conduit and thereby
protecting it from being damaged/clogged by ice,debris.
• Some times from reservoirs where gravity flow is possible, water is
directly transmitted to the treatment through intake structure.
• If gravity flow is not possible, water entering intake structure is lifted by
pumps and taken to the treatment plant.

Selecting Location Of Intake Structure
• Site should be near the treatment plant to reduce conveyance cost.
• Intake must be located in the purer zone of the source so that best quality
water is withdrawn from source to reduce the load on the treatment plant.
• Intake must never be located in the vicinity of waste water disposal point.
• Intake must never be located near the navigation channels so as to reduce
chances of pollution due to waste discharge from ships.
• The site should be such as to permit greater withdrawal of water, if
required in future.

• Intake must be located at a place from where it can draw water even
during the driest period of the year.
• The intake site should remain easily accessible during floods and
should not get flooded.
• In meandering rivers, the intakes should not be located on curves or
atleast on sharp curves.

Types of Intakes
According to type of source
• RiverIntake
• Canal Intake
• Reservoir Intake
• LakeIntake
According to position of Intake
• Submerged Intake
• Exposed Intake
According to presence of water in the tower
• Wet Intake
• Dry Intake
Intakes for Collecting Surface Water

According to position of Intake
• (a) Submerged Intake
• (b) Exposed Intake
• The submerged Intake structures are those which are constructed entirely
under water. They are less expensive to construct but are difficult to
maintain. Such intakes are commonly used to obtain water from lakes
• The Exposed intakes is in the form of well or tower constructed near the
bank of river or in some cases even away from the bank of river. They are
more common due to ease in operation andmaintenance

According to presence of Water in the tower
Wet Intake
Dry Intake
AWet intake is that type of the Intake tower in which the water level is
practically the same as the water level of the source of supply. Such
Intakes are also called as JackWell and is most commonlyUsed
In Dry Intake There is no water in the intake tower. Water enters
through entry port directly in to conveyance pipes. The dry Intake
tower is simply used for the operation of valves.

Simple LakeSubmergedIntakes
• It consists of a simple concrete block or a rock filled timber crib
supporting the starting end of the withdrawal pipe.
• The intake opening is generally covered by screen so as to prevent the
entry of debris, ice etc.. in to the withdrawal conduit.
• In lakes, where silt tends to settle down , the intake opening is generally
kept at about 2 to 2.5m above the lake bed level to avoid entry ofsilt.
• They are cheap &do not obstruct navigation
• They are widely used for small water supply projects drawing water from
streams or lakes having a little change in water level through outyear.
• Limitation is that they are not easily accessible for cleaning &repairing.

RockFilled Timber Crib-Submerged Intake

River Intake
A River Intake is located on the upstream side of the city to get
comparatively better quality of water. They are either located
sufficiently inside the river so that necessary demand of water
can be met in all the seasons of the year.
The intake tower permits the entry of water through several entry
ports located at various levels to cope with fluctuations in the water
levels during different seasons.
This are also called as penstocks. The penstocks are covered with
suitable design screens to prevent entry of floating impurities.

Intake Towers
• They are widely used on large water supply projects drawing water from rivers
or reservoirs having large change in water level.
• Gate controlled openings called Ports are provided at various levels in these
concrete towers to regulate the flow.
• If the entry ports are submerged at all levels, there is no problem of any
clogging or damage by ice or debris etc..
• There are two major types of intake towers:
(a) Wet intake towers
(b) Dry intake towers

Wet Intake Towers
• It consist of a concrete circular shell filled with water up to the reservoir
level and has a vertical inside shaft which is connected to the
withdrawal pipe.
• The withdrawal pipe may lie over the bed of the rivers or may be in the
form of tunnels below the river bed.
• Openings are made in to the outer concrete shell as well as, in to the
inside shaft.
• Gates are usually placed on the shaft, so as to control the flow of water in
to the shaft and the withdrawal conduit.
• The water coming out of the withdrawal pipe may be taken to pump
house for lift (if treatment plant is at high elevation) or may be directly
taken to treatment plant (at lower elevation).

Dry Intake Towers
• The water is directly drawn in to the withdrawal conduit through the
gated entry ports.
• Ithas no water inside the tower if its gates areclosed.
• When the entry ports are closed, a dry intake tower will be subjected to
additional buoyant forces.
• Hence it must be of heavier construction than wet intake tower.
• They are useful since water can be withdrawn from any selected level
of the reservoir by opening the port at that level.

Intake
• There are two types of intakes as under
• (i) Dry Intake Tower
• In dry intake tower the entry ports are directly connected with the
withdrawal conduit and water inside the tower when gates arein a
closed position. Dry Intake tower has a merit that the intake tower
being dry is made accessible for inspection and operation besides that
the water can be withdrawn from any level by opening the port at
that level.
• However, dry intake tower is massive in structure, than wet intake to
withstand additional buoyant forces to which it is subjected when the
port gates are closed.

Intake
Wet Intake Tower
• A wet intake tower has entry ports at various levels and the vertical
shaft is filled with water up to reservoir level. It differs from the dry
intake tower is that the water enters from the ports into the tower
and then into the withdrawal conduict through separate gated
openings. As such it consists of a circular shell made of concrete
filled with water up to reservoir level, housing another inside shaft
directly connected to the withdrawal conduit. It is less costly to
construct and is usually not subjected to flotation and certain other
stress may not be the consideration.

Trash Racks
• Trash rack is defined as a screen or grating provided at the entrance
of intake to prevent entry of debris. Trash racks usually consists of
trash sections 1.5 to 2 m wide and not too long for handling, made
up of mild steel flats on edge 5 to 15 cm. Coarse trash racks are
provided near the ports to prevent large drift, such as cakes of ice,
roots, trees and timber from being drawn into the intake.

Trash Racks
• In some part of the intake fine trash racks are provided to protect the
machine &machine parts through which water flows. In cold region,
trash racks is often clogged with fragile ice. Electrical heating for
small trash racks are provided to prevent ice formation on the racks.
• The floating debris accumulated, as are denied entry into the intake,
are removed with the help of power driven rack-rakes.

River Intake Structures
• They are generally constructed for withdrawing water from
almost all rivers.
• They can be classified in to two types
(1) Twin well type of intake structure
(2) Single well type of intake structure

Twin Well Type Intakes
• They are constructed on almost all types of rivers, where the river water hugs
the river bank.
• Atypical river intake structure consists of 3 components:
(a) An inlet well
(b) An inlet pipe (intake pipe)
(c) Ajack well
• Inlet well is usually circular in c/s, made of masonry or concrete.
• Inlet pipe connects inlet well with jack well. It has a min dia of 45cm, laid at
slope of 1 in 200. Flow velocity through it<1.2m/s
• Water entering jack well is lifted by pumps &fed into the rising main
• Jack well should be founded on hard strata having B.C> 450 kN/m2.

Single Well Type Intakes
• No inlet well &inlet pipe in this type of river intake.
• Opening or ports fitted with bar screens are provided in the jack
well itself.
• Thesediment entering will usually be less, since clearer water will
enter the off-take channel.
• The silt entering the jack well will partly settle down in the bottom
silt zone of jack well or may be lifted up with the pumped water
since pumps can easily lift sedimented water.
• Thejack well can be periodically cleaned manually, by stopping the
water entry in to the well.

Canal Intakes
• In case of a small town a nearby Irrigation Canal can be used as
the source of water. The Intake Well is generally located in the bank
of the Canal. Since water level is more or less constant there is no
need of providing inlets at different depth. It essentially consist of
concrete or masonry intake chamber or well.
• Since the flow area in the canal is obstructed by the construction
of Intake well, the flow velocity in the canal decreases. So the
canal should be lined on the Upstream & Downstream side of the
intake to prevent erosion of sides and bed of channel

Intakes For Sluice Ways Of Dams

Intakes for Reservoirs
• When the flow in the river is not guaranteed throughout the year,
a dam is constructed across the river to store the water in the
reservoir so formed.
• Reservoir Intakes essentially consists of an Intake tower
constructed on the slope of Dam at such a place where Intake can
draw water in sufficient quantity even in the driest period. Intake
pipes are fixed at different levels, so as to draw water near the surface
in all variations of water levels.

An intake structure constructed at the entrance of conduit and
thereby helping in protecting the conduit from being damaged
or clogged by ice , trash, debris, etc.., can vary from a simple
Concrete block supporting the end of the conduit pipe to huge
concrete towers housing intake gates, Screens, pumps, etc.. and
even sometimes, living quarters and shops for operating
personnel.

Lake Intake
• Lake Intake are mostly submerged intake. These Intakes are
constructed in the bed of lake below the low water level so as to draw
water even in dry season. It mainly consist of a pipe laid in the bed of
the lake. One end of the pipe which is in middle of the lake is fitted
with bell mouth opening covered with a mesh and protected timber
or concrete crib. The water enters in the pipe through the bell mouth
opening and flows under gravity to the bank where it is collected in a
sump well and then pumped to the treatment plant for necessary
treatment.

Advantages Intakes
• No Obstruction to navigation
• No danger of floating bodies
• No ice trouble

Intake
• The general requirement of an Intake Structure are:
Structural Stability
• The Intake structure is stable to resist water and wave thrust besides
wind pressure when reservoir is empty as also against the shock of
earthquakes.
Hydraulic efficiency
• There is smooth entry into the water conductor system to ensure
gradual transformation of static head to conduct velocity so as to
involve hydraulic losses.

Intake
Velocity Limitation
• The velocity through trash rack gates and ports is within economic and
safe limits.
Operational efficiency
• The intake and the equipments are such as to prevent/ minimize ice,
floating trash and coarse sediment entering the water conductor system
to ensure good operational efficiency.

Intake
• The main components of an irrigation intake structure are
(i) Trash rack and supporting structure
and rectangular circular
(ii) Bell mouth entrance with transition
opening, and
(iii) Gate slot closing devices with air vents.

Gate slot closing devices with air vents.

Intake
Function of Intakes
• Intake structure serve to permit withdrawal of water in the
reservoir over a predetermined range of reservoir levels to the outlet.
• The other functions served by an intake are to support necessary
auxiliary appurtenances such as trashrack, fish screens and
bypass devices, etc.,.

Intake
Run-of-River Intakes
• In a run-of-River plants, intake is apparent to power house and
draws water from the river without any appreciable storage
upstream of the diversion structure. Characteristics of river flows.,
the intake is designed to withstand high peaks and short duration flood
flows and high sediment loads. The bell mouth entrance is
essentially provided with trash racks.

Intake
Canal Intake
• It is also a variant of the run-of-river intake, that is provided
adjacent to the diversion weir/ barrages to admit water into the
canal. It is designed to function under low heads and the topography
and geology permits straight reach suitable for it. Sediment
excluder is an essential component of the intake. The crest of the
intake is generally raised to prevent entry of coarse fraction of bed
load into the canal.

Intake
Reservoir Type Intakes
• Intake tower classified as Submerged, dry and wet intakes fall in
this category.
(i) Submerged Intake
• An Intake Structure which remains entirely under water during
its operation is termed as submerged intake. It is provided where
the structure serves only as an entrance to the outlet conduct and
where ordinarily cleaning of the trash is not required. The conduct
intake may be inclined, vertical or horizontal in accordingly with
the intake requirements. . An Inclined Intake may be provided
with gates and operated on the upstream slopes of a low dam.

Intake
Intake tower
• An Intake tower is used to draw water from the reservoir
in which there are huge fluctuations in water level or
quality water is to be drawn at the desirable depth or both. It
Consist of an elaborate exposed or tower like structure
rising above maximum reservoir level and closely located
to the dam body or the bank of the stream so as to be
approached by a connecting bridge of minimum span.

Intake
• The Intake tower consist of circular concrete structure
provided with openings or ports for water entry fitted
with trash racks to prevent the entry of debris and ice large
enough to injure the equipment and gates that control the
flow through intakes into the feeding conduct outlet.
• It has a merit that best quality of water available at
different depths at different seasons of the year can be
drawn through port openings at different elevations.

Design of Intake
• An Intake should be designed and constructed on the basis of following
points
• Sufficient factor of safety should be taken so that intake work can resist
external forces caused by heavy waves and currents, Impact of floating
and submerged bodies, ice pressure etc..
• Intake should have sufficient self weight, so that it may not float by the up
trust of water and washed away by thecurrent
• IfIntake work is constructed in navigation channels, it should be protected
against the impact of the moving ships by cluster of pile around
• The foundation of Intake should be taken sufficient deep so that they may
not be undermined and currentmay not overturn the structure.

Design of Intake
• To avoid the entrance of large and medium objects and fishes screens
should be provided on the Inlet, sides
• The Inlet should be of sufficient size and should allow required
quantity of water.
• The positions of Inlet should be such that they can admit water in all
seasons near the surface where quality of water is good.
• Number of Inlets should be more so that if any one is blocked, the
water can be drawn from others. The inlets should be completely
submerged so that air may not enter the suctionpipe.

Design procedure for Intakes
Canal Intake
• If Population is given and rate of water Supply is given the discharge
required by the city/town can be found
• Q=Population x RateofSupply
Design of Coarse Screen
• Generally the coarse screens are made of vertical bars of 15 to 20
mm dia and are spaced at 20 to 50 mm Centre toCentre
• Velocity through the screens is assumed to be around 0.15 m/sec

• Area of Screens= Discharge
Velocity through screens
Q=Ax V
Height of the screen is found assuming that the bottom of the screen is
kept 0.15 m above canal bed and also considering the minimum water
level in the canal.
After finding height, length of the screen opening can be found out.
Length of screen =Area
Height

• Number of bars required can be found after assuming the diameter
and spacing of the bars.
• Total length of screen will be length of opening +length occupied by
bars.
Design of bell mouth entry
• To find the area of bell mouth entry first assume the velocity through
bell mouth generally around 0.3 to 0.35 m/sec. After getting the area
find the dia of bell mouth

Design Procedure for Intakes
Design of Intake Conduit
• Assume the velocity of flow through conduit, generally 1.0 to 1.5
m/sec
• Find , A= Q
V
Then Using Hazen William formula, find the head loss and the slope
required, Charts can be used.

River Intake
• First Design the Intake Well. Dia is generally between 4 to 7.5 m.
Using discharge find the area and the diameter.
• If rectangular find length and width after finding the length and
width of the screen required.
• Design procedure for coarse screen and outlet conduct is almost
same as canal Intake.

Example
• Design a bell mouth canal intake for a city of 70,000
persons drawing water from a canal which runs only for 10
hrs. a day with a depth of 1.6 m. Also calculate the head loss
in the intake conduit if the treatment plant is 0.5 km away.
Assume average consumption per person= 160 l/d. Assume
the velocity through the screens and bell mouth to be 0.15
m/s and 0.3 m/s respectively.

Example
• Discharge required by the city
=70000 x 160 (Population x rate of supply)
=11,200,000
11.2 MLD(Million litre perday)
Since the canal only runs for 10 hrs. a day, this whole daily
flow is required to be drain in 10 hrs.

Example
Therefore the Intake load= 11.2 =1.12 ML/Hour
10
=1.12 x 10 6 m3 / hr....
10 3
1.12 x 10 3 m3 /sec
60 x 60
=0.311 m3 /sec

Example
Design of Coarse Screen
• Areaof Coarse Screen = Discharge
Velocity through the screen
Velocity through the screen =0.15 m/sec
Area of the coarse screen =0.311 = 2.075 m 2
0.15
Assume the minimum water level is 0.3 m below the normal water level. The
bottom of the screen is kept at 0.15 m above the bed level. Thetop of screen is kept
at minimum level
1.80 m
Therefore available height= 1.6 – 0.3- 0.15
=1.15 m
Minimum length of the screen= 2.075 =
1.15

Example
Assume the clear opening between vertical bars to be 30 mm each we have
= 60
• Number of opening =1.8
0.03
Therefore no of bars= 59
Assume the dia of bar as 20 mm
Length occupied by the bar of 20 mm =59 x0.02
=1.18 m
Therefore length of screen= 1.8 +1.18
=2.98
Say3 m
Hence provide coarse screen of length 3.0 m and height 1.15 in rectangular intake
well

Example
Design of Bell Mouth Entry
• Area of Bell mouth entry =Discharge
Velocity through the bell mouth
= 0.311
0.3
=1.037 m2
Diameter d of the bell mouth entry as
=∏ d 2 = 1.037
4

Example
• D={ 4 x 1.037} 1/2
∏
=1.15 m
If the dia of small holes in the screen is assumed to be 15 mm (10 to20mm).
Then area of each hole= ∏ x (0.015) 2
4
=1.767 x 10 -4
= Areaof bell mouth
Area of one hole
Therefore number of holes on the bell mouth
= 1.037
1.767 x 10 -4
=5868.2
Say 5869

Example
• Assume Velocity of flow in the conduit as 1.5 m/sec
• Area of conduit required = Discharge
Velocity
=0.311 =0.2073 m 2
1.5
Dia of pipe D will be
∏ D2 =0.2073
4
=0.514
Say0.55 m

Example
• Flow velocity through this 0.55 m dia conduit will be
=V=Q =0.311 =1.31 m /sec
A
x (0.55) 2
assume velocity of 1.5 m /sec
=∏
4

Example
• Head loss through n
the conduit up-to treatment plant is calculated by using
Hazen William’s eq
• V=0.85 CHR0.23 S0.54
• Where ,
• CH=Coefficient of thePipe
• =130 for Cast Iron Pipe
• R=Hydraulic mean depth
• =d/4 ( for pipe running full)
• =0.55 = 0.138 m
4
V=Velocity
S=Slope

Example
• Therefore,
• 1.5 =0.85 x 130 x (0.138 ) 0.63 S0.64
• S0.54 = 150
0.85 x 130 x (0.138)0.63
=0.047
S=(0.047) 1 /0.54
=3.51 x 10 -3
Or 1 in 284.73
S=HL= HeadLoss
L Length of Pipe
Length of pipe is equal to the distance of Intake from treatment plants 0.5 km =
500 m
HL=3.51 x 10 -3 x500
=1.755 m

Example
• Design a bell mouth canal Intake for a City of 1,00,000 persons
drawing water from a canal which runs for 10 hrs.. a day with a
depth of 2 m. Also calculate the head loss in the intake conduit if the
treatment works are 1 km away. Draw a neat sketch of canal Intake.
Assume average consumption per person= 150 l/day. Assume the
velocity through the screens and bell mouth to be less than 15 cm/sec
and 35 cm/sec

Example
Discharge through Intake
Daily Discharge= 150 x 1,00,000= 15,000,000 l/day
• Since the canal runs only for 10 hrs. perday.
• Intake Load/hr =15,000,000 =15,000,00 lit/hr
10
= 0.4166 m3 /sec
=15,00 m3 /hr....
Q= 1500
60 x 60

Example
Area of Coarse Screen Ifront of Intake
• Area of Screen= 0.4166= 2.777 m 2
0.15
Letthe area occupied by solid bars by 30 %of the total area
Therefore the actual area= 3.96 m 2
Let us assume minimum water level at 0.3 m below normal water level. Also let us keep
bottom of the screen at 0.15 m above canal bed and top of screen at the minimumwater
level.
Available height of screen= 2- 0.3-0.15 =1.55 m
Required length of screen= 3.96 =2.55 m
1.55
Hence provide a length of 2.6 m
Hence provide a screen of 1.55 x 2.6 m

Example
Design of Bell Mouth Entry
• Area of Bell mouth Ab= 0.4166 =1.301 m 2
0.32
Dia db= { 1.301 x 4}1/2 = 1.65 m
3.14
Hence provide a bell mouth of 1.7 m dia

Example
• Let us assume a velocity of 1.5 m/sec in the conduit
• Dia of conduit D ={0.4166 x 4 } 1/2 =0.35 m
1.5 x 3.14
However, provide 0.5 m dia, conduit, so that actual velocity of flow is
V = 0.4166 x 4 = 2.12 m/sec
3.14 x (0.5) 2

Example
Forhead loss through theconduit
• V=0.849 CR0.63 S0.54
• C= 130
• R=D/4 =0.5 /4 =0.125
• Hence Slope Sof the energy line,
• 2.12 =0.849 (130) (0.125) 0.63 S0.54
• S=7.533 x 10 -3
• S=HL/L
• HL=Sx L=7.53m

Conveyance of Water
• Water is drawn from the sources by Intakes. After it’s drawing the
next problem is to carry it to the treatment plant which is located
usually within city limits. Therefore after collection, the water is
conveyed to the city by mean of conduits. If the source is at higher
elevation than the treatment plant, the water can flow under
gravitational force.
• Forthe conveyance of water at such places we can use open channel,
aqueduct or pipe line, Mostly it has been seen that the water level in
the source is at lower elevation than the treatment plant, In such case
water can be conveyed by means of closed pipes under pressure

Conveyance of Water
• If the source of supply is underground water, usually there is
no problem as, these sources are mostly in the underground
of the city itself. The water is drawn from the underground
sources by means of tube-wells and pumped to the over-
head reservoirs, from where it is distributed to the town
under gravitational force. Hence at such places there is no
problem of conveyance of water from sources to the
treatment works.

Conveyance of Water
•In case of sources of water supply is river or reservoir
and the town is situated at higher level, the water will
have to be pumped and conveyed through pressure
pipes. If the source is available at higher level than
the town, it is better to construct the treatment plant
near the source and supply the water to the town
under gravitational forces only,

Conveyance of Water
Open Channels
• These ae occasionally used to convey the water from the source to the
treatment plant. These can be easily and cheaply constructed by
cutting in high grounds and banking in lowgrounds.
• Thechannels should be lined properly to prevent the seepage and
contamination of water. As water flows only due to gravitational
forces, a uniform longitudinal slope is given. The hydraulic gradient
line in channels should not exceed the permissible limit otherwise
scouring will start at the bed and water will become dirty. In channel
flow there is always loss of water by seepage and evaporation,

Conveyance of Water
Aqueducts
• Aqueducts is the name given to the closed conduit constructed with
masonry and used for conveying water from source to the treatment
plant or point of distribution. Aqueduct may be constructed with
bricks, stones or reinforced cement concrete. In olden days
rectangular aqueduct were used, but now a days horse-shoe or
circular section are used. These aqueduct are mostly constructed with
cement concrete Theaverage velocity should be 1 m/sec

Conveyance of Water
Tunnels
• This is also a gravity conduit, in which water flows under
gravitational forces. But sometimes water flows under pressure and
in such cases these are called pressure tunnels. Grade tunnels are
mostly constructed in horse-shoe cross-section, but pressure tunnel
have circular cross-section. In pressure tunnels the depth of water is
generally such that the weight of overlying material will be sufficient
to check the bursting pressure. Tunnels should be water tight and
there should be no loss of water.

Conveyance of Water
Flumes
• These are open Channels supported above the ground over
trestles etc.. Flumes are usually used for conveying water
across valleys and minor low lying areas or over drains and
other obstruction coming in the way. Flumes may be
constructed with R.C.C, wood or metal. The common section
are rectangular and circular.

Conveyance of Water
Pipes
• These are circular conduits, in which water flows under pressure.
Now a days pressure pipes are mostly used at every places and they
have eliminated the use of channels, aqueducts and tunnels to a large
extent. These are made of various materials like cast Iron, wrought
Iron, steel, cement Concrete, asbestos, cement, timber, etc.. In the
town pips are also used for distribution system. In distribution system
pipes of various diameter, having many connections and branches
are used. Water pipe lines follow the profile of the ground water and
the location which is most economical, causing less pressure in pipes
is chosen.

Conveyance of Water
• The cost of pipe line depends on the internal pressure to
bear and the length of pipe line. Therefore as far as possible
the hydraulic line is kept closer to the pipe line. In the valley
or low points a scour valve is provided to drain the line and
removing accumulated suspended matter. Similarly at high
points air relief valves are provided to remove the
accumulated air. To prevent the bursting of pipes due to
water hammer, surge tanks or stand pipes are provided at
the end of pipes.

Conveyance of Water
The selection of material for the pipes is done on the
following points
• Carrying Capacity of the pipes
• Durability and life of the pipe
• Type of water to be conveyed and its corrosive effect on the pipe
material.
• Availability of funds
• Maintenance cost, repair etc..
• Thepipe material which will give the smallest annual cost or capital
cost will be selected, because it will be mostly economical.

Conveyance of Water
Following types of pipes are commonly Used
• CastIron Pipes
• Wrought Iron pipes
• Steel Pipes
• Concrete Pipes
• Cement lined CastIron Pipes
• Plastic or PVCpipes
• Asbestos cement pipes
• Copper and lead pipes
• Wooden pipes
• Vitrified Clay pipes

Conveyance of Water
• Out of the types mentioned, plastic or PVC and Asbestos
cement pipes, wooden pipes are not generally used for
conveyance of water. They are used in house drainage or
water connection within individual house.

CastIron Pipes
• Cast – Iron Pipes are mostly used in water supply schemes. They have
higher resistant to corrosion, therefore have long life about 100
years.
• Cast Iron pipes are manufactured in lengths of 2.5 m to 5.5 m. The
fittings of these pipes are also manufactured in sand molds having
core boxes. These fittings are also weighed, coated with coal tar and
finally tested. Cast-Iron pipes are joined together by means of Bell
and Spigot, Threaded or flanged Joints

Conveyance of Water
Advantages of CI Pipes
• Ease in jointing the pipes
• Can withstand high Internal pressure
• Have a very long design life. (100 years)
• They are less prone to corrosion.

Conveyance of Water
Dis-advantages of CI Pipes
• They are heavy and difficult to transport
• Length of pipe available as less (2.5 to 5.5m) so more joints are
required for laying the pipes so chances of leakage also Increases.
• They are brittle so they break or crack easily.

Conveyance of Water
Wrought Iron Pipes
• Wrought Iron Pipes are manufactured by rolling the flat plates of the
metal to the proper diameter and welding the edges. If compared
with cast Iron, these are more lighter, can be easily cut, threaded and
worked, give neat appearance if used in the interior works. But it is
more costly and less durable than cast iron pipes. These pipes should
be used only inside the buildings, where they can be protected from
corrosion. Wrought Iron pipes are joined together by couplings or
screwed and socketed joints. To Increase the life of these pipes
sometimes these are galvanized with zinc.

Conveyance of Water
Steel pipes
• The Construction of these pipes is similar to wrought iron
pipes, it is occasionally used from main lines and at such
places where pressure are high and pipe dia is more. Steel
pipes are more stronger, have very light weight and can
withstand high pressure than cast iron pipes. They are also
cheap, easy to construct and can be easily transported.

Conveyance of Water
• The disadvantages of these pipes is that they cannot withstand
external load, if partial vacuum is created by emptying pipe rapidly,
the pipe may be collapsed or distorted. These pipes are much affected
by corrosion and are costly to maintain The life of these pipes is 25 to
50 years, which is much shorter as compared to cast Iron Pipes Steel
pipes are not used in distribution system, owing to the difficulty in
making connections.
• The joints in steel pipes may be made of welding or riveting,
longitudinal lap joints are made In riveted steel pipes up to 120 cm
dia

Conveyance of Water
Concrete Pipes
• These pipes may be precast or Cast-in-situ plain concrete
pipe may be used at such places where water does not flow
under pressure, these pipes are jointed with Bel &Spigot
Joints. Plain Concrete pipes are up to 60 cm dia only, above
it these are reinforced.

Conveyance of Water
Advantages of R.C.C Pipes
• Their life is more about 75 years
• They can be easily constructed in the factories or at site
• They have least coefficient of thermal expansion than other types of
pipes . Hence they do not require expansion joints
• Due to their heavy weight, when laid under water, they are not
affected by buoyancy, even when they are empty.
• They are not affected by atmospheric action or ordinary soil under
normal condition.

Conveyance of Water
Disadvantages of R.C.C Pipes
• They are affected by acids, alkalis and salty waters
• Their repairs are very difficult.
• Due to their heavy weight, their transportation and laying cost is
more.
• It is difficult to make connections in them
• Porosity may cause them to leak.

Pipe Joints
• For the facilities in handling, transporting, and placing in position,
pipes are manufactured in small lengths of 2 to 6 meters. These small
pieces of pipes are then joined together after placing in position to
make one continuous length of pipe.
• The design of these joints mainly depends on the material of the pipe,
internal water pressure and the condition of the support
• The bell and spigot joints, using lead as filling material is mostly used
for cast Iron pipes. For Steel pipes welded, riveted, flanged or screwed
joints my be used.

Various types of Joints which are mostly used, are
as follows
• Spigot and Socket Joints or Bell &Spigot Joints
• Expansion Joints
• Flanged Joints
• Mechanical Joints
• Flexible Joints
• Screwed Joints
• Collar Joints
• A.C.PipeJoints

Spigot and Socket Joints
•This types of joints is mostly used for cast iron pipes
For the construction of this joint the spigot or normal
end of one pipe is slipped in socket or bell mouth end
of the other pipe until contact is made at the base of
the base of the bell.

• After this hemp or yarn is wrapped around the spigot end of
the pipe and is tightly filled in the joint by means of yarning
iron up to 5 cm depth. The hemp is tightly packed to
maintain regular annular space and for preventing jointed
material from falling inside the pipe. After packing of hemp
&gasket or joint runner is clamped against the outer edge of
the bell.

• Sometimes wet clay is used to make tight contact between
the runner and the pipe so that hot lead may not run out of
the joint spaces. The molten lead is then poured into V-
shaped opening left in the top by the clamp joint runner.
The space between the hemp yarn and the clamp runner is
removed, the lead which shrink while cooling, is again
tightened by means of chalking tool and hammer. Now a
days in order to reduce the cost of lead certain patented
compounds of sulphur and other materials and other
materials are filled in these joints.

Expansion Joints
• This joint is used at such places where pipes expand or contract due
to change in atmospheric temperature and thus checks the setting of
thermal stresses in the pipes. In this joints the socket end is flanged
with cast iron follower ring, which can freely slide on the spigot end
or plane end of other pipes. An elastic rubber gasket is tightly pressed
between the annular spaces of socket by means of bolts. In the
beginning while fixing the follower ring some space is left between
the socket base and the spigot end for the free movement of the pipes
under variation of temperature. In this way when the pipe expands
the socket end moves forward and when the pipe contracts, it moves
backward in the space provided for it. The elastic rubber gasket in
every position keeps the joint water tight.

Flanged Joint
• This joint is mostly used for temporary pipe lines, because the pipe
line can be dismantled and again assembled at other places.
• The pipe in this case has flanges on its both ends, cast, welded or
screwed with the pipe. The two ends of the pipes which are to be
jointed together are brought in perfect level near one another and
after placing of washer or gasket of rubber, canvas, copper or lead
between the two ends of flanges is very necessary for securing a
perfect water-tight joints. These joint cannot be used at places where
it has to bear vibration of pipes etc..

Flexible Joints
• Sometimes this joint is also called Bell &Socket or Universal Joint. This
joint is used at such places where settlement is likely to occur after
the lying of the pipes. This joint can also be used for laying of pipes
on curves, because at the joint the pipes can be laid at angle. This is a
special type of joint. The socket end is cast in a spherical shape. The
spigot end is plain but has a bead at the other end. Forthe assembling
of this joints, the spigot end of one pipe is kept in the spherical end of
the other pipe.

Flexible Joints
• After this the retaining ring is slipped which is stretched
over the bead. Then a rubber gasket is moved which touches
the retainer high. after it split cast iron gland ring is placed,
the outer surface of which has the same shape as inner
surface of socket end. Over this finally cast iron follower
ring is moved and is fixed to the socket end by meansof
bolts. It is very clear that if one pipe is given any deflection
the ball shaped portion will move inside the socket, and the
joint will remain waterproof in all the position.

Mechanical Joints
• This type of joints are used for jointing cast Iron, Steel or wrought
Iron pipes, when both the ends of the pipes are plain or spigot. There
are two types of mechanical joints.
• Dressers- Couplings
• It essentially consists of one middle ring, two follower rings and two
rubber gaskets. The two follower rings are connected to-gather by
bolts and when they are tightened, they pass both the gaskets tightly
below the ends of the middle ring. These joints are very strong and
rigid and can withstand vibrations and shocks up to certain limit.
These joints are mostly suitable for carrying water lines over bridges,
where it has to bear vibrations.

Mechanical Joints
Victaulic Joint
• In this type of joints a gasket or leak-proof ring is slipped over both
the ends of the pipes. This gasket is pressed from both the sides by
mean of half iron couplings by bolts. The ends of pipes are kept
sufficient apart to allow for free expansion, contraction and
deflection. This joints can bear shocks, vibrations etc.. and used for
cast-iron, steel or wrought iron pipe lines in exposed places.

Screwed Joints
• The joint is mostly used for connecting small diameter cast iron,
wrought iron and galvanized pipe. The end of the pipes have threads
outside, while socket or couplings has threads on the inner side. The
same socket is screwed on both the ends of the pipes to join them. For
making water tight joints zinc paint or hemp yarn should be placed
in the threads of the pipes, before screwing socket over it.

Collar Joint
• This type of joint is mostly used for joining big diameter concrete and
asbestos cement pipes. The ends of the two pipes are brought in one
level before each other. Then rubber gasket between steel rings or
jute rope socked in cement is kept in the grove and the collar is
placed at the joint so that it should have same lap on both the pipes.
Now 1:1 cement mortar is filled in the space between the pipes and
the collar.

Jointfor A.C. Pipes
• Forjointing small diameter A.C.Pipes the two ends of pipes are butted
against each other, then two rubber rings will be slipped over the
pipes and the couplings will be pushed over the rubber rings. The
rubber rings make the joint water-proof.

Laying of Water Supply Pipes
• Pipes are generally laid below the ground level, but sometimes when
they pass in open areas, they may be laid over the ground. The pipes
are laid in the following way.
• First of all the detailed map of all roads, streets lanes etc., is prepared.
On this map the proposed pipe line with all sizes and length will be
marked. The position of existing pipe line, curb lines, sewer lines etc..
will also be marked on it. In addition to this position of valves and
other pipe specials, stand posts etc.. will also be marked, so that at the
time of laying there should be no difficulty in this connection.

• After the general planning, the center line of the pipe line will be
transferred on the ground from the detail plan. The center line will
be marked by means of stalkes driven at 30 m interval on straight
lines. On curves the stalkes will be driven at 7 to 15 m spacing. If the
road or streets have curbs, the distance of center of pipe line fro curb
will be marked.

• When the center line has marked on the ground the excavation for
the trenches will be started. The width of the trench will be 30 cm to
45 cm more than the external diameter of the pipe. At every joint the
depth of excavation will be 15 to 20 cm more for one meter length
for easy joining of the pipes. The pipe lines should be laid more than
90 cm below the ground so that pipe may not break due to impact of
heavy traffic moving over the ground

• Afterthe excavation of trenches the pipes are lowered in it. The pipe
laying should start from lower level and proceed towards higher
level with socket end towards higher side. The jointing of pipes
should be done along with the laying of pipes.
• After laying the pipe in position, they are tested for water leakage and
pressure.
• When the pipe line is tested, the back filings of the excavated
material will be done.
• The soil which was excavated is filled in the trenches all around the
pipes and should be well rammed. All the surplus soil will be
disposed off and the site should be cleaned.

Hydrostatic Test
• After laying the new pipe line, jointing & back filling, it is subjected
to the following tests:
• Pressure Tests at a pressure of at least double of maximum working
pressure, pipe joints shall be absolutely water tight.
• Leakage Test (to be conducted after the satisfactory completion of the
pressure test) at a pressure as specified by the authority for a
duration of two hours.
• In this way error in workman ship will be found immediately and
can be rectified. Usually the length to be tested is kept up to 500 m.

Pumps for Lifting Water
• The function of the pump is to lift the water or any fluid at higher elevation or
higher pressure. In water works pumps are required under the following
circumstances.
• Atthe source of water to lift the water from rivers, streams, wells etc.. and to
pump it to the treatment works.
• Atthe treatment plant to lift the water at various units so that it may flow in
them due to the gravitational force only during the treatment of the water.
• Forthe back washing of filters and increasing theirefficiency.
• Forpumping chemical solution at treatmentplants.
• Forfilling the elevated distribution reservoirs or overheadtanks
• Toincrease the pressure in the pipe lines by boosting up thepressure.
• Forpumping the treated water directly in the water mains for itsdistribution.

Classification of pumps
• (i) Classification based on principles of operation
• Displacement pump
• Centrifugal pumps
• Air –lift pumps
• Impulse pumps
• (ii) Classification based on type of power required
• Electrical driven pumps
• Gasoline engine pumps
• Steam engine pumps
• Diesel engine pumps

Classification of pumps
• (iii) Classification based on the type of services
• Low lift pumps
• High lift pumps
• Deep-well pumps
• Booster pumps
• Standby pumps

Theselection of a particular type of pumps
depend upon the following factors
• Capacity of pumps
• Number of pump units required
• Suction conditions
• Lift (total head)
• Discharge condition, and variation in the load
• Floor space requirement
• Flexibility of operation
• Starting &priming characteristics
• Initial cost and running costs

Displacement Pumps
• In these types of pumps vacuum is created mechanically by
the movable part of the pumps. In the vacuum first the
water is drawn inside the pumps, which on the return of
mechanical part of the pump is displaced and forced out of
the chamber trough the valve and pipe. The back flow of the
water is prevented by means of suitable valves.

Displacement Pumps
• The following are the two main type of displacement pumps
(i) Reciprocating Pumps
(ii) Rotary Pumps

Displacement Pumps
Reciprocating Pump
• Reciprocating pumps may be of the following types
• Simple hand-operated reciprocating pump
• Power operated deep well reciprocating pump
• Single-acting reciprocating pump
• Double-acting reciprocating pump

Displacement Pumps
Rotary Pump
(a) Rotary pumps with gear
(b) Rotary pumps with cams
• The revolving blades fit closely in the casing and push the water by
their displacement. The blades revolve in a downward direction at
the Centre and the water is carried upward around the side of the
casing. In this way the water is pushed through the discharge pipe
and partial vacuum is created on the suction side. The intensity of
vacuum mainly depends on the tightness of the parts.

Displacement Pumps
Advantages of Rotary Pumps
• They do not require any priming as they are self-primed.
• Theefficiency of these pumps is high at low to moderate heads up-to
discharge of 2000 l/m
• These pumps have no valves, are easy in construction and
maintenance as compared with reciprocating pumps.
• These pumps give steady and constant flow
• These pumps are deployed for the individual building water supply
and for fire protection.

Displacement Pumps
Disadvantages of Rotary Pumps
• The initial cost of these pump is high
• Their maintenance cost is high due to abrasion of their cams and
gears.
• They cannot pump water containing suspended impurities as the
wear and abrasion caused by the impurities will destroy the seal
between the cans and the casing.

Centrifugal Pumps
• These pumps work on the principle of centrifugal force,
therefore, they are called centrifugal pumps. The water
which enters inside the pump is revolved at high speed by
means of impeller and is thrown to the periphery by the
centrifugal force.

Centrifugal Pumps
Advantages and Disadvantages of Centrifugal Pumps
• The centrifugal pumps have the following advantages
• Due to compact design, they require very small space.
• They can be fixed to high-speed driving mechanism
• They have rotary motion due to which there is low or no noise
• They are not damaged due to high pressure

Centrifugal Pumps
Disadvantages of centrifugal pumps
• They require priming
• The rate of flow of water cannot be regulated.
• Any air leak on the suction side will affect the efficiency of the pump.
• They have high efficiency only for low head and discharge.
• The pump will run back, if it is stopped with the discharge valve
open.

Design of Pumps
• Design of pumps means to find out the capacity of the pump
required to deliver specific quantity of water against specific head.
• Sodesign of pumps can be divided into twoparts
• Tofind the total head against which the pump has to operate.
• The total power requirement or the capacity of the pump or the size
of the pump required and also deciding the number of pumps
required as well as stand by.

Total Head Or LiftAgainst Which ThePump Has
To Work
• The total head or total lift against which the pump has to work
includes suction lift (or Head), discharge or delivery lift (or Head)
and total loss of head due to friction, entrance, exit, fitting etc. in
suction and rising main.
• If Hs=Suction lift orHead
• Hd=Delivery or dischargehead
• Hl=Total loss of head then,
• Thetotal head against which the pump has to work is given by:
• H=Hs+Hd+Hl

To Work
• Suction lift : It is the difference between the lowest water and the
pump
• Discharge lift or delivery Head:It is the difference between the point
of discharge or delivery and the pump.
• Generally only the friction losses is considered for the design as
minor losses are very small if the length of the pipe is greater

To Work

To Work
• Friction loss can be found out by Darcy Weisbachequation
• Darcy Weisbach Eqn = Hf=4 fl v2 = f’l v2
2 g d 2g d
Where ,
l=length of pipe
d=dia of pipe
v=velocity of flow
f=coefficient of friction
f’=friction factor Value of friction factor varies between (0.02 to0.075)

Power required by the pump or capacity of
pump
• The horse power (H.P.) of the pump can be determined by calculating the
work done by the pump in raising the water up to the height H.
• Let the pump raise W kg of water to height Hmeter.
• Then the work done by the pump= W xH (m.kg)
• =ϒ Q H (m. kg/sec)
• Where, ϒ =Unit Weight of water
• Q=Discharge to be pumped in m3 /sec
• H=Total head in meter
• Water Horse Power (WHP) = ϒ Q H
75

Power required by the pump or capacity of
pump
• Brake Horse Power (B.H.P)=W.H.P
Ƞ
= ϒ Q H
75 Ƞ

Number of Pumps, size and stand by units
• Pumping units at water works are generally not operated at full
capacity for all times. Since the efficiency of pumping unit varies
with the load, it is a usual practice to design a pumping station that
some of the pump units can be operated at full capacity, at all the
time. Hence two, three, or four pumps are installed. The sizes of these
pumps can be fixed by considering the demand, available storage.
• Thus, there will always exist some stand by capacity to take care of
the repairs, breakdowns, etc. Generally 100 %stand-by by capacity
to take care against average demand and 33.33 to 50 % standby
capacity against the peak demand is considered sufficient and may
therefore be provided at the pumping station.

Design of Rising Main
• Rising main is the pipe through which the pumped water is sent
further to the next unit for treatment purpose. Water flows in this
pipe under high pressure and flow is turbulent. Here the friction loss
in the pipe is more due to high velocity. Pressure pipes are designed
such that overall cost of the project should be lowest possible both
from maintenance and constructional point of view.

Economic diameter of rising main
• For pumping a particular fixed discharge of water, there are two options
• Itcan be pumped through bigger diameter pipe at low velocity
• Through lesser diameter pipe at high velocity
• If the dia of the pipe is increased, it will lead to higher cost of the pipe line on the other
hand if the pipe diameter is reduced the velocity would increase which will lead to
higher frictional head loss and will require more Horse Power for pumping,thereby
increasing the cost of pumping, also cost of fitting will increase.
• For obtaining the optimum efficiency, it is necessary to design the diameter of the
pumping main which will be overall most economical in initial cost as well as
maintenance cost for pumping the required quantity of water. The diameter which
provide such optimum condition is known as “economic diameter” of the pipe.

• An empirical formula given by lee is commonly used for determining
the dia of the pumping or rising main
• D=0.97 to 1.22√Q
• Where,
• D=Economic dia of pipe in meters
• Q=Discharge to be pumped in cumecs

Head loss in rising main
• The loss of head in the rising main can be found byusing
• (i) Darcy Weisbach eq
• (ii) Hazen William’s equation
• Darcy Weisbach Eqn= Hf=4 f l v2 =
2 gd
f’l v2
2g d
Where ,
l=length of pipe
d=dia ofpipe
v=velocity of flow
f=coefficient of friction
f’=friction factor Value of friction factor varies between (0.02 to0.075)

Hazen Williams Equation
• V=0.85 CHR0.63 S0.54
• Where,
• V=velocity of flow
• S=Slope of H.G.L
• =Hl = HeadLoss
L Length of Pipe
R=Hydraulic mean Radius of the pipe = A
P
Ifpipe is running full then
R=∏/4 d2 =d/4
∏ d
CH=Hazen William’s coefficient which depends on age, quality and material ofpipe.

Examples
• Find out the head loss due to friction in a rising main from the
following data:
• Length of the rising main= 600 m
• Diameter of pipe= 0.2 m
• Discharge required to be pumped =1200 l/min
• Friction factors= 0.025

Examples
• Velocity of flow = Q
A
Q= 1200 l/min
= 1200 x 10-3 m3 /sec
60
=0.02 m3 /sec
V=0.02
∏ (0.2) 2 =0.637 m/sec
4

Examples
• Hf= f’lv2
2gd
=0.025 x 600 x (0.637)2
2 x 9.81 x0,2
=1.551 m

Examples
• A city with 1.5 lakh population I to be supplied water at 100 lpcd
from a river 1 km away. The difference in water level of sump and
reservoir is 30 m. if the demand has to be supplied in 8 hr., determine
the size of the main and B.H.Pof the pumps required.
• Take f- 0.0075, velocity in the pipe as 2.0 m/sec and efficiency of
pump as 75 %

Examples
• Population of a city= 1,50,000
• Rate of water supply= 100 lpcd
• Therefore the average demand of the town= 1,50,000 x 100
• =15 x 10 6 l/day
• Maximum daily demand= 1.5 x avg demand
• =1.5 x 15 x 106
• =22.5 x 10 6 l/day
• =22.5 MLD

Examples
• Asthe full demand is to be supplied through pumps in 8 hrs
• Discharge required= 22.5 x 10 6 l/ hours
• 8
• = 22.5 x 10 6 x 10 -3= 0.781 m3 /sec
8 x 3600

Examples
• The maximum velocity in the pipe is given as 2.0m/sec
• Therefore Cross sectional area of the pipe required
• A=Q = 0.781 = 0.39 m 2
• v
• If d is the dia of the pipe then
• ∏ d 2 =0.39
4
D= 0.704m
=0.75 m
Total lift is given as 30 m

Examples
• Friction loss hf can be found by using Darcy Weisbash eq n
• Hf=4 f l v2
2 g d
=4 x 0.0075 x 1000x (2.0 )2
2 x 9.81 x 0.75
=8.155 m

Examples
• Thus the total lift against which the pump has to work or lift water
• =30 +1.155
• =38.155m
• BHP ofthe pump= ϒ Q H
75 Ƞ
1 hp(I) =745.699872 W =0.745699872 kW
=1000 x 0.781 x 38.155
75 x 0.75
=526.75 =530HP
1 W in ... ... is equal to ...
• 1 kg·m
2
/
3
s

Example
• From a clear water reservoir 3 m deep and maximum water level at
RL35 m water is to be pumped to an elevated reservoir at RL80 m at
the constant rate of 9 lakh litres per hour. The distance is 2000 m.
Find the economic diameter of the rising main and the water horse
power of the pump. Neglect minor losses and take f=0.01

Example
• The Discharge Q= 9 lakh per hour
• = 9,00,000 =0.25 m3 /sec
1000x 60 x 60
Economic diameter of rising main can be found by
D=1.22 √Q
=1.22 √0.25
=0.61 m

Example
• Maximum Suction Head =3 m ( depth ofreservoir)
• Maximum delivery head =(80- 35)= 45 m
• (Difference between maximum water level and height of elevated
reservoir)
• Suction +Delivery= 3 +45 =48 m

Example
• Friction Head loss can be found by
• Hf=4 flv 2
2 g D
V=Q = 0.25 = 0.855 m/ sec
A ∏ (0.61) 2
4
Hf=4 x 0.01 x 2000x (0.855) 2
2 x 9.81 x0.61
Hf=4.886 m
The total Head =48 +4.886m
H=52.886 m

Example
• Water horse power of Pump= ϒ Q H
75
=1000 x 0.25 x52.866
75
=176.22 HP

References
Water Supply Engineering :ByProfS.K.Garg
Khanna Publishers
Internet Websites

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