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For internal circulation of BSNLonly
E4E4--E5 CIVIL E5 CIVIL
((TECHNICAL)TECHNICAL)
External & Internal Services External & Internal Services
(Water Supply)(Water Supply)
WELCOME
• This is a presentation for the E4-E5 Civil Technical
Module for the Topic: External & Internal Services –
Water Supply.
• Eligibility: Those who have got the Up-gradation to from
E4 to E5.
• This presentation is last updated on 21-4-2011.
• You can also visit the Digital library of BSNL to see this
topic.
For internal circulation of BSNLonly
For internal circulation of BSNLonly
AGENDA
Quality of Water
Demand requirements
Design of Water Distribution System
Internal Water Supply
QUALITY OF WATER
• Absolute pure water is never found in nature.
• Impurities in the form of salts, gases, bacteria algae
etc.
• Potable water to be supplied in the water supply
scheme.
• Potable water is safe to drink, pleasant to the taste.
• Contaminated water contains micro-organisms,
chemicals, industrial or other waters, or sewage.
For internal circulation of BSNLonly
STANDARDS OF WATER
Physical
• Temperature - 100 c to 15.60 c
• Colour - 10 to 20 (platinum cobalt scale)
• Turbidity - 5 to 10 ppm (Silica scale)
Chemical
• Total Solids - upto 500 p.p.m.
• Hardness - 75 p.p.m. to 115 p.p.m.
(hardness expressed as caco3 equivalent)
For internal circulation of BSNLonly
STANDARDS OF WATER
Chemical Contd.
• Chlorides - upto 250 p.p.m.
• Iron and Manganese - upto 0.3 p.p.m.
• ph Value - 6.5 to 8
• Sulphate - upto 250 p.p.m.
• Dissolved Oxygen - 5 to 6 p.p.m.
• B.O.D. - Nil
For internal circulation of BSNLonly
STANDARDS OF WATER
Biological
• B- coli - No B- coli in 100 ml.
• Most Probable Number - One Number in 100 ml.
(M.P.N)
• Periodical chemical, physical and bacteriological
tests of water samples shall be got it done through
approved laboratory.
• Remedial measures based on test results shall be
taken.
For internal circulation of BSNLonly
Treatment Process
Treatments used for removing impurities:
Impurity Process used for
removal
1. Floating matters as leaves, Screening
dead animals etc.
2. Suspended impurities Plain Sedimentation
as silt clay, Sand etc.
3. Fine suspended matter Sedimentation with
coagulation
For internal circulation of BSNLonly
Treatment Process
Impurity Process used for
removal
4. Micro-organism and Filtration
colloidal matters
5. Dissolved gases, tastes Aeration and
and odours chemical treatment
6. Softening Permutit method
7. Pathogenic bacteria Disinfections
For internal circulation of BSNLonly
Methods of Disinfection
The disinfection of water can be done by the following common
methods.
a) By the boiling of water.
b) By ultra-violet rays.
c) By the use of ozone.
d) By treatment with silver or electro-Katadyn process.
e) By the use of Iodine and Bromine.
f) By the use of excess lime.
g) By using potassium permanganate.
h) By the use of chlorine.
For internal circulation of BSNLonly
Methods of Disinfection
• Disinfection by excess lime though kills the bacteria but
pH value of the water is increased. Hence this method
is not use for water works.
• Use of KMNO4 can be used in open well or in ponds.
• The usual dose is 1-2 mg/litre with contact period of 4 to
6 hours. But efficiency to kill the bacteria is only 98%.
Hence not used in water works.
• The cheap and most effective method of disinfection is
by the use of chlorine.
For internal circulation of BSNLonly
Disinfection by Chlorine
• Chlorine is very useful to kill Micro-Organisms
present in the water. When Chlorine is dissolved in
water, it hydrolysis immediately as :
Cl2 + H2O ----- HOCL + H+ + Cl-
( Hyprocholorous Acid)
• Hypochlorous Acid further ionizes as
HOCL ----- H+ + OCL-
( Hyprocholorite Icons)
For internal circulation of BSNLonly
Disinfection by Chlorine
• Two prevailing species HOCL (Hypochlorous Acid)
and OCL- (Hypochloritic Ion) are called “Free
Available Chlorine” and are responsible for the
disinfection of water.
For internal circulation of BSNLonly
Forms of Chlorine
Chlorine is available in the following forms:
A. In the forms of Liquid Chlorine.
B. In the forms of gaseous Chlorine.
C. In the form of Chlorine dioxide.
D. In the form Chloramines.
E. In the form of
Bleaching Powder (Calcium Hypochloride).
For internal circulation of BSNLonly
Forms of Chlorine
• Form of Chlorine (A) to (D) in the previous slide,
require treatment plants and are used in big water
works.
• For small colonies we commonly use Bleaching
Powder as a source of Chlorine for disinfection and
it is cheap and best source of chlorine.
For internal circulation of BSNLonly
Dosage of Chlorine
• In normal waters that are pre treated with settling
and filtration, a chlorine of about 0.2 to 1 ppm
(Particle Per Million) may be required to obtain the
desired results.
• The bleaching powder normally contains chlorine
which vary 25-30%.
• Bleaching powder should be stored in air tight
container.
For internal circulation of BSNLonly
Demand Requirement
• The daily requirement of the buildings is calculated on the
basis of the population (p) and per capita rate of supply (q).
• For residential buildings, population may be taken as five
members per family.
• For residential buildings, per capita rate may be taken as
200 lit/head/day.
• For non-residential buildings, the daily consumption (q)
given table ‘B’.
• Population of buildings, (p) may be taken from table ‘A’.
• Total demand (Q) = p x q
For internal circulation of BSNLonly
Demand Requirement
Table A
• The assessment of the population in occupancies
based on plinth area clause 6.2.1. part IX Plumbing
services – section I. Water supply and clause 7,5 or
part IV fire protection as given in * National Building
code of India 1970 *
i) Staff Quarters & residence:- Assume a family of
5 person per quarter or an area of 12.5m2/person
whichever is more.
For internal circulation of BSNLonly
Demand Requirement and General Principles
Table A
ii) Technical buildings such as 10.00m2/person
• Telephone Exchange Buildings,
• Telecom Factories
• And workshop.
iii) Post offices and Administrative 10.00m2/person
• Buildings
For internal circulation of BSNLonly
Demand Requirement
Table B
i) Staff Quarters 200 Litres/ head/ day
(Para 5.1.N.B.C. 1983)
ii) Technical buildings: 45 litres/ head/ day
• Tel. Exch. Buildings ( Para 3.2 IS-1172-1971)
• Telecom factories
iii) Post offices and 45 litres/ head/ day
Administrative Buildings (Para 3.2 IS-1172/ 1971)
For internal circulation of BSNLonly
Layout of Distribution System
Dead End System
• Pipes are to be laid as per layout of the roads.
• This system requires less number of valves and also
shorter pipe lengths, therefore it is cheap and simple.
• But since water can be reached to any place by only one
route, any damage and subsequent repair to the pipe
result in shutting downs the supply of a large area
ahead.
• In this system water remains stagnant resulting
contamination of water.
For internal circulation of BSNLonly
Layout of Distribution System
For internal circulation of BSNLonly
Layout of Distribution System
Grid Iron System
• Where the roads arranged in grid iron pattern the
pipe lines are laid similarly.
• Water reaches different places through more than
one route. Hence frictional losses are less, and the
sizes of the pipe get reduced.
• However the system requires more length of pipes
and number of sluice valves.
For internal circulation of BSNLonly
Layout of Distribution System
Grid Iron System Contd…
• If repairs are to be carried out to any pipe, only a
small portion in the vicinity gets effected, since
water can be supplied ahead by some other route.
• There is no stagnation of water. Hence no problem
of contamination.
For internal circulation of BSNLonly
Layout of Distribution System
For internal circulation of BSNLonly
Layout of Distribution System
The Ring Main System
• The capacity of grid iron can be enhanced and the
pressures can be improved by running a looped
feeder around the high demand section and
arranging grid over it.
For internal circulation of BSNLonly
Layout of Distribution System
For internal circulation of BSNLonly
Design of Water Distribution System
• Till date no direct methods are available for design
of distribution pipes.
• While doing the design, diameter of pipes are
assumed. Terminal pressure are calculated, after
allowing the losses of head, when full peak flow
discharge is flowing.
For internal circulation of BSNLonly
Design of Water Distribution System
The Hazen – william’s formula is widely used for
determining the velocity through pipes.
V = 0.85 CH.R0.63 S0.54
V = Velocity m/Sec.
S = Slope of the Energy Line.
R = Hydraulic Mean Depth
R = A/P = Cross section area/
Perimeter
CH = Coefficient of Hydraulic Capacity.
For internal circulation of BSNLonly
Design of Pipe Network
• To reduce the tedious calculations of calculating the
Head Losses in pipes, the Hazen – William’s
Nomogram is used. Hazen – William’s chart for
various materials of pipe are available in Public
Health Engineering departments of the state Govt.
For internal circulation of BSNLonly
Hazen-William’s Nomogram
For internal circulation of BSNLonly
Internal Water Supply
General Guidelines for Planning of Internal Water
Supply System:-
• Water for drinking purpose should not be taken from
Distribution Pipe (from OHT) but it should be taken
directly from Service Pipe (to OHT) or separate pipe
should be provided to kitchen.
• Distribution pipe should be designed to avoid any
Air Lock. Vent should be provided at the highest
point.
For internal circulation of BSNLonly
Internal Water Supply
General Guidelines for Planning of Internal Water
Supply System Contd…:-
• It is always preferable to provide unions at number
of places so as to enable for easiness in repairs.
• No reveres loop should be provided in the internal
water supply otherwise water supply will be blocked
by Air Lock.
For internal circulation of BSNLonly
For internal circulation of BSNLonly