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Design of Water Supply

Networks

CIVL 5995 Project I

A!a" Sana

Depart!ent of Ci#il an" Arcitectural$ngineering

Sultan %a&oos 'ni#ersity( )!an

1

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Design of water "istri&utionsyste!

A municipal water distribution system is used to deliverwater to the consumer.

Water is withdrawn from along the pipes in a pipe networksystem, for computational purposes all demands on the

system are assumed to occur at the junction nodes. Pressure is the main concern in a water distribution system.

At no time should the water pressure in the system be solow that contaminated groundwater could enter the systemat points of leakage.

The total water demand at each node is estimated fromresidential, industrial and commercial water demands atthat node. The re !ow is added to account for emergencywater demand.

"

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Co!ponents of a water"istri&ution syste!

#

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*unctional Co!ponents of aWater 'tility

$

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Large "ia!eterwater !ains

%

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Pressure +e"ucing an" CeckVal#e

&

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A ,ypical Pu!ping StationSce!atic

'

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Pu!p ouse

(

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Centrifugalpu!ps

)

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Typical elevatedwater tanks

1*

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+eser#oir-pu!p-tank syste!

11

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Pu!p cur#es

1"

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,ypes of#al#es

1#

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,ypical layout of water supplysyste!

1$

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'sing &ooster pu!ps

1%

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)peration of a water supplysyste!

1&

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Syste! ea" cur#e

1'

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Pu!p operating point

1(

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)perating points ./a01 an"/in12

1)

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)perating points for #ariouspu!ps

"*

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)peration points for #ariouspipes

"1

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,ypical pipe network

""

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"#

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"$

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"%

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"&

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"'

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"(

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")

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Water +emandTotal water demand at a node is eual to the average water demand

per capita multiplied by the population served by that node.

The population may be estimated by any of the available models ofpopulation growth. These models use the previously availablepopulation data for future projections.-or eample, according to Arithmetic model/

P(t)is the population at time tand P*is the reference population.ktPtP += 0)(

#*

Public Authority for Electricity and Water, Sultanate of Oman

+esign 0uidelines and tandardsfor Water upply ystems

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Water De!an"

imilarly a higher order polynomial

function can be obtained as follows/ ++++=

32

0)( ctbtatPtP

$0a!ple32ou are in the process ofdesigning a water3supply system for a

town, and the design life of yoursystem is to end in the year "*"*. Thepopulation in the town has been

measured every 1* years since 1)"*and is given below. 4stimate thepopulation in the town using graphicaletension and arithmetic growthro ection.

#1

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Population projection2ear Populatio

n1)"* 1"%,***1)#* 1%*,***1)$* 1%*,***1)%* 1(%,***

1)&* 1(%,***1)'* "1*,***1)(* "(*,***1))* #"*,***

From the graph, if the line is extended to year

22, !e get, the population as" ##,

$y regression on the data for %&' to %&&, !e get the follo!ing expression"

ttP 550060000)( +=!here, t is the time in years starting from year %&2( So, for year 22, t) %,

and !e get the population" #&,

#"

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+emand pattern

##

-i d d

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-ire demand*nsurance Ser+ices Office, *nc( *SO, %&-. formula"

iiii PXOCNFF )( +=

!here, /FFi is needed fire flo! at location i, 0iis the construction factor based on

si1e and type of construction of the building, Oiis the occupancy factor reflectingthe inds of material stored in the building +alue range from ('3 to %(23., and

45P.iis the sum of the exposure factor and communication factor that reflects the

proximity and exposure of other buildings +alue range from %( to %('3.(

ii AFC 220min)/L( =

Aiis the effecti+e floor area in s6uare meters, typically e6ual to the area of thelargest floor in the building plus 37 of the area of all other floors, F is a

coefficient based on the class of construction( 8he maximum +alue of 0i and

typical F +alues are gi+en belo!"

Class ofConstruction

Description * /a01C

i.L4!in2

1 -rame 1.% #*,***" 5oisted masonry 1.* #*,***# 6oncombustible *.( "#,***$ 7asonry,

noncombustible*.( "#,***

% 7odied re resistive *.& "#,*** #$

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-ire demandCo!&usti&ility

class$0a!ples )i

831 6oncombustible teel or concrete products

storage

*.'%

83" 9imitedcombustible

Apartments, mosues,o:ces

*.(%

83# 8ombustible +epartment stores,supermarkets

1.*

83$ -ree3burning Auditoriums, warehouses 1.1%83% ;apid burning Paint shops, upholstering

shops1."%

A+erage +alue of 45P.i is %(#( 8he /FF should be rounded to the nearest%9:min if less than & 9:min and to the nearest 29:min if greater than

&9:min(;euired re !ow ;euired re !ow +uration

?)*** "

11***31#*** #1%***31'*** $

1)***3"1*** %

"#***3"&*** &

"&***3#**** '

#****3#$*** (

#$***3#(*** )

#(***3$%*** 1* #%

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Operating criteria for !ater supply systemsPrimary functions of a !ater;supply system

%( nder normal conditions ) 2# to #% Pa

?uring fire or emergency ) @%# Pa

Maximum pressure not strict. " 3Pa(

Storage facilities%( 27 to 237 of the maximum daily demand +olume

2( Fire demand=( Emergency storage minimum storage e6ual to a+erage daily system demand.

#(