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 Tubewell design criteria for Northern...
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Title: Tubewell design criteria
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Permanent Link: http://ufdc.ufl.edu/UF00075690/00001
 Material Information
Title: Tubewell design criteria for northern zone, West Pakistan
Physical Description: 18 leaves : ill. ; 22 cm.
Language: English
Creator: Tipton and Kalmbach
Publisher: Tipton and Kalmbach, Inc. Engineers,
Tipton and Kalmbach, Inc. Engineers
Place of Publication: Lahore Pakistan
Publication Date: 1966
Copyright Date: 1966
 Subjects
Subject: Water resources development -- Pakistan   ( lcsh )
Water-pipes -- Design and construction   ( lcsh )
Genre: non-fiction   ( marcgt )
Spatial Coverage: Pakistan
 Notes
Statement of Responsibility: by Tipton and Kalmbach, Inc.
General Note: "March 12, 1966."
 Record Information
Bibliographic ID: UF00075690
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 82908304

Table of Contents
    Front Cover
        Front Cover
    Tubewell design criteria for Northern Zone, West Pakistan
        Page 1
        Page 2
        Page 3
        Page 4
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        Page 15
        Page 16
        Page 17
        Page 18
    Definition of symbols
        Page 19
    Figures
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
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Full Text

/o o/





------------------===~E== = t=====










TUBEWIVLL DESIGN C2ITS IIA



for



Northern Zone, West Pakistan










TIPTON AND KALDI~BACIH, INC.
ENGINiEi:;,

Lahore
";ST PAKISTAN





March 12, 1966










-----------------------------------_,__------------------------









TUBEWE.LL DESIGN CRITERIA


for

Northern Zone, West Pakistan



Many physical, technical and economic factors affect the

design of tubewells." Engineering considerations and construction

techniques restrict the rank.e of choice of components and physical

conditions affect performance. Still, within the restrictions

imposed by these factors, a wide range of design possibilities

exists. The best or optimum design is one which results in a

minimum total cost for the water pumped.

Screen dimensions, length and diameter, have the great-

est influence on optimum tubewell design, and of the two, length'

is the most important. Within certain minimum technical restric-

tions both dimensions are subject to wide variation depending on

several physical and economic factors. Characteristics of the

aquifer are the most important physical factor and the most

important economic factors are 1) life of the tubewell, 2) cost

of components and construction, 3) cost of power, 4) rate of

interest on investment, and 5) annual volume pumped or utilization.

In order for design criteria to be applicable, the

factors which are considered must be subject to evaluation or

estimation and the criteria must be in usable form. In this

report the most important design factors are discussed, certain

design parameters are chosen and an operational procedure is

derived for designing tubewells of optimum dimension during

construction.








- 2 -


Basic Considerations

Length and diameter of the screen are the most important

determinants of drawdown. Drawdown, in turn, has a major influence

on consumption of power. In the absence of other considerations,

minimum drawdown would result in minimum cost of water. But to

reduce drawdown, diameter of screen must be increased, or more

importantly, length of screen must increase. Both factors can be'

obtained only by increasing initial construction cost of the

tubewells. In order to determine optimum screen length a balance

between added construction cost and reduced power cost must be

achieved.

Regardless of changes in screen length and diameter,

many components of construction do not change or are of minor

influence. Only those components whose cost changes with screen

size need to be considered in determining optimum screen dimensions.

The construction components which Vary with screen length or dia-

meter are 1) depth of well, 2) amount of gravel shrouding, 3) length

of housing as influenced by drawdown, 4) length of blank as influen-

ced by amount of impervious layers in the aquifer and total well

depth, and 5) cost of screen.- In general, the total amount of these
2/
variable cost items can be stated as follows:-

C = P(D ) + P (L) + PD (B) + P gH ) + P,(G) (1)

It is convenient to express water volume and energy cost

on nn annual basis, so equation (1) must also be converted to this
1/ Borehole radius is considered constant (1 ft.) within the range
of screen radius examined.

2/ All symbols are defined at the end of the report








3 -

basis. The usual procedure is to make an interest charge on initial

cost and depreciate the initial cost over the life of tubewell.

Fifteen years has been accepted as the life of tubewells under

conditions in the Punjab. The West Pakistan Water and Power

Development Authority pays 4% percent interest on the loans granted

for tubewell construction. Combining power charges with deprecia-

tion and interest charges on half the initial investment (average

investment over the life of the tubewell), the average variable

cost for a given volume of water can be expressed as:

C = 0.09 C + C a CA + C (2)
v I E IA E

where CE = PE (), PE is the rate for electricity and E is annual

consumption in K','H,

Total pumping head

Power consumption is a function of total pumping head,

Ht, which is the sum of ultimate depth to static water level, Wt;

tubewell drawdown, s; height of discharge pipe above surface level;

friction head loss of column pipe and discharge pipe, h ; and

discharge velocity head, h That is

H = W + s + h + h + 5 = H + WV + 5 (3)

Ultimate depth to static water level is specified by considerations

not directly related to optimum screen length and will be prescri-

bed for purposes of optimiz.ation. Average height of discharge pipe

is approximately 5 feet above the surface level. The variable

components of head, or dynamic head, IHd, are therefore drawdown,

friction head and velocity head,








4 -

Tubewell drawdown can be divided into three parts in

general tubewell design:

s = 1 + s2 + s3 (4)

1. s1 is the part of drawdown due to aquifer loss which is

a function of tubewell discharge, screen length, screen radius,

radius of borehole and aquifer permeability. Theoretically, sI is

also a function of area recharge intensity, anisotropic condition

of the aquifer, degree of penetration, time of pumping, aquifer

boundary conditions, interference of well field and so on. Tasting

data show that the most suitable formula for computing aquifer loss

in the Punjab area, is to consider the well as partially penetrating

an aquifer of semi-infinite depth with essentially radial flow with-

in the influence radius of (TT/2)L at the end of the well-testing
s
period. That is

Q 2 7r L5s 0.20 )
s1 n7nK i, s.r.+ (5)
1 47r K LLs 2 r

Since the term 0.20 is usually negligible, the relation

can be simplified to:

= /./5 Q. /157Ls (6)
Tr K L5 ~

2. sa is the part of drawdown due to gravel pack loss

It is a function of tubewell discharge, screen length, screen

radius, borehole radius and gravel pack permeability.


s2 (7)


3. s3 is the part of drawdown or head loss which is

caused by the flow passing through the screen slot and the







-5-

accummulative flow along the well screen axis,

,53 U2 Q
(c h c'- >-i )//


where C' = 11.31 C A /As, and C is the coefficient of contraction
c p c
and A /As is the ratio of slot opening to screen surface. With

properly designed screen slot, size, shape and distribution, if

L /2 rs > 15 the equation above can be simplified as follows:


172r4C (8)

The column pipe and discharge pipe friction lose is

computed by the following equation:


Zf ^ z y (9)
hf =J2r 2T rU4


and the velocity head is


h = (10)


Therefore the dynamic head can be computed by



n. -H^-LL ]r + qZ
7 L-- 07 (11)


For average Punjab aquifer conditions and general tubewell

design practices, the following values are recommended for use in

computing total dynamic head:

Aquifer permeability for water, K=1.5x10-3 ft/sec(excluding clay layers)
-1
Gravel pack permeability for water, K = 100 K = 1.5 x 10 ft/sec
g
Bore hole radius, r = 1.0 ft
*w







- 6 -


Pipe friction factor, f = 0.015

Acceleration of gravity, g = 32.2 ft/sec2

By substituting these values into equation (11), the

following equation can be derived:


S 2.44x / L.s 4.87 xo' 2.44 y/ 7
d L Ls zS Ls
-3
.7/ X/O -2 c z
+/47 IX//O XjJ/xto5 L (12)


Following are workable equations for design purposes for

the case of depth to static water level nt 20 feet:

A. Screen radius, r = 3 in = 0.250 ft


d = 2.44 4 93 X0'7 q 4 (13)

B. Screen radius, r = 4 in = 0.333 ft


Ifd -Z. '44/oz-17 93" !--'^ "jQ ro30x,-'IQz (14)


C. Screen radius, r = 5 in = 0.417 ft


id s 4.87 X/o OX Q2 (15)
id =2.44 Ls + -- / + .o -]Qz (/S)


The theories, assumptions, analyses of testing data, and

other engineering and practical considerations upon which these

equations are based are beyond the scope of this report.

Cost components

Under usual contract sporifications, the cost of drilling

is variable with depth. Present contracts specify Rs 32 per foot for





7 -

the first 300 feet of drilling, Di. Rs 36 per foot for drilling between

300 and 400 feet, D2w; Rs 45 per foot for drilling over 400 feet in

depth, D3w. The rate continues to increase with deeper drilling but

depths beyond 500 feet are seldom applicable for conditions found in

the Punjab and will be ignored in this report. Using the designations

above, total depth of well can be specified as:

D = Dw + D2w+ D3w (16)

Alternately, depth of well is also the sum of screen length, length

of housing pipe below the surface and length of blank pipe:

D = L + Hg + B 3 (17)
w S
Length of housing pipe must exceed depth to static water table plus

drawdown and can be specified as follows for usual conditions

Hg = Wt + s + 8 (18)

This allows 5 feet of housing pipe below drawdown water level and a

3 foot extension above ground level for the pedestal.

Length of blank pipe varies with the number and thickness

of impervious layers in the aquifer. In the Punjab the length of

blank usually vari.-s between zero and 50 percent of the length of

screen and averages about 15 percent. For most calculations, length

of blank will be considered 15 percent of screen length:

B = 0.15 L (19)

Equation (17) can be restated using equations (18) and (19) as:

D = 1.15 L + Wt + s + 5 (20)
w s t

It will also be convenient to restate equation (16) as:






- 8 -


(21)
D = 1.15 L + + + + 5 D. D(
iw s t j j w

Present contract unit prices for non-drilling components

are Rs 60 per foot for 6 inch fiberdla:,. screen, Rs 75 per foot for

8 inch fiberglass screen and Rs 85 per foot for 10 inch fiberglass

screen, P ; Rs 44, Rs 58 and Rs 70 for 6, 8 and 10 inch blank pipe,
S
P1 ; Rs 55 per foot for housing pipe, PIg ; and Rs 11 per foot for

gravel shrouding, PG. From equation (19) the cost of blank pipe

can be stated as PB(0.15L ) or for 8 inch blank pipe, Rs 8.70 L .

Using this and the other stated prices, equation (1) becomes

C = 32 Dl + 36 D 2+45D +(8.70+75) L +11D +55(W +s+8) (22)
I 1w 2w 3w 8 w t

for 8 inch screen. On an annual basis, equation (22) becomes


C = 2.8D w+3.24D w+4.05Dw +7.53L +.99D +4.95(W +s+8) (23)
IA 1w 2w 3w s w t

Power consumption

Daily energy consumption is specified by:

2.03 QHt (24)
d --.
e

Usinp 60 percent combined wire to water efficiency, e,- the annual

electrical cost is:

CE = 1,235 UQHt(P ) = 86.45 U4Hf (25)

where U is average annual utilization and PE, the price of elec.tri-

city is Rs 0.07/KWH .

Optimizing procedure

The Ranual cost of a volume of water specified by U and

Q is C the sum of .equations (23) and (25). For 8 inch screen it
eeeeeeeeeeeeeeeeeeeeeeeee-r~----rr------------------ --
1/ Performance test data for 225 SCARP I test wells show combined
efficiency to be 5,.6 + 2.0 percent. As efficiency is expected
to increase, a value of 60 percent is appropriate, Although
efficiency varies through the life of the tubewell it will be
considered for design purposes that the effect of this
variation is offset by a decline i.n the water table,







- 9 -


can be written


C = 3.87 Dw + 4.23 D2 + 5.04 Dw + 7.53 L + (4.95+86.45 UQ) s
v 1w 2w 3w s

+4.95(Wt+8)+86.45 UQ (Wt+hf+h +5) (26)

This equation is a continuous, concave function of L for any Di but

discontinuous over its full range. The minimum value of C with
v

respect to screen length can be found by differentiating in segments

because within anysegment two Di are constant. Furthernmor4, the

last two terms in equation (26) are-not functions of screen length

and also drop out. For D ', 300 feet, equation (26) becomes .
W"

C 3.87(1.15 L +W is+5)+7.53 L + (4 98 +* 86,45 UQ', .

+ 4.95(W +8)+86.45 VU (W +H1 +h +5)

.and

a. = 11. 9 8 + (8.82z 8:..-5 UQ)
acs


or
- .s s :




9 9=7 896.4 (6.8.2 S.4 7 -0Q44
45 L .(27)

For = 4 cusecs and U = 60 percent, equation (27), when set eliual

to zero reduces to

L2 17,617 log L 4i128 (28)
S S -

which can be solved by successive approximitien.

.. The form of C and its components and the solution for

(18) are shown graphically in Figure 1.

Influence of various factors

Length..of blank pipe: The general case for equation (19)

can be written B = b L where b is the factor indicating blank pipe
S






10'

;as a percent of screen length. Using the general case for: length

of blank pipe andcombining equation ('3) -and (25) with D 3 300;


C (10.62+9.Q9b) L.+(8.82+86.45 ,U() s +8,82(Wt)
V .s* ,.* t 1. */ ; *


86.45 UQ (IV +h +h +5)+58.95
t rv


(29)


for 8 inch screen. And


9Cv (/aBz O ( ^B. d52) s (30)

Thus the blank pipe factor, affects the constant term in equation.. (27).

The effect on optimum screnenength as b varies from zero to 100

percent is shown in Figure 2,

The larger the amount of impervious layers in the aquifel

the more costly the tubewell is to construct because depth must be

increased accordingly. As more blank pipe is required, initial

construction cost becomes relatively more important in determining

optimum screen length than cost of power consumption. As a result,

optimum screen length decreases when the amount of blank pipe

increases

Price of screen: Again combining equation (23) and (25),

C can be written
V
C = (5.22+.09P )L +(8.82+86.45UQ)s+8.82(Wt)
V a t
+86.45 U'l(l +h +h +5)+58.95 (31)
t fV
for 8 inch screen and D1 .300 feet, Thus, like the proportion of

blank pipe, screen price affects the *constant term in. equation (27).

An increase in screen price, as would be expected, decreases optimum ,:

screen length (Figure 3).






S. .. . .., ,'." .iti. ..







-11-

Static Water Level: From inspection of equations (26) 4o

(28) it is obvious that static water level, Wt has no direct

influence on optimum screen length. However static water level

does affect total depth of well which affects the location of the

discontinuities in equation (26). Because of this Wt has a snall

effect on optimum screen length but calculations 3how the effect

to be no mo,-e than 5 feet for the usual rano:e of W't, and there-

fore, ne 'liibleo

Annual Utilization: Higher annual utilization allows

initial construction cost to be distributed over a larger volume

of water, reducing the relative importance of this component of

annual variable cost. The effect is an increase in optimum screen

length if greater utilization is anticipated (Figure 4). It .is

evident from inspection of equation (27) that proposed utilization

is a significant determinant of optimum screen length

Cost of Power: Variation in cost of power has a marked

influence on optimum screen length figure e 5). The relatively high

price of electricity in West Pakistan puts a premium on low total

head causing greater optimum screen lengths than expected in areas

of lower power cost9

Rate of interest and tubelell life: These factors

influence optimum screen length because they affect annual charges

on initial construction cost, CI, in equation (2). The constant

(0.09) in equation (2) is comprised of (i/2+1/L) where i is rate of

interest .znfl L is tubewoll life in years. Thus, a decrease in i

or an increase in L reduce the initial construction component(CIA)








12 -

of the cost of water. If annual charges on initial construction cost

are smaller, the use of greater screen length-to reduce power cost

is justified even though it increases initial cost. The effect from

varying interest rate is shown in Figure 6 and the effect from vary-

ing estimated life is shown in Figure 7.

Di.cuqsion and Conclusions

The values of many variables affecting screen dimension

including prices of components, cost of power and rate of interest

on initial investment are known for any given time and location.

Tubewell life is estimated on the basis of type of components used

and conditions prevailing in the area and must be resolved before

hand. For a given project area, therefore, these factors are given.

Aquifer permeability varies from site to site and in

large projects it is usually not possible to determine specific

vliluir for each site. However an appropriate design value for a

project area can be selected. Blank pipe also varies from tubewell

to tubewell but its length is determined at each location during

drilling.

Within a project area, variables such as tubewell

capacity and anticipated utilization vary from site to site. In

order for an optimization process to be useful all combinations

of these factors neeil to be considered seprately,

Although radius of screen is an important variable in

tubewell design, sufficient parameters, are available to predetermine

this dimension for tubewells of different capacities prior to








1.*








13 -

installation. Length of screen, the most important consideration

in tubewell design, should and can be determined individually at

e:ch site at time of drilling.

Selection of Design Value for Aquifer permeability: Refer-

ing to equations (5) and (11), the most critical single factor

affecting optimum screen length is the inherent property of the

aquifer, permeability. Aquifer permeability varies from place to

place :-nd is extremely difficulty to predict accurately regardless

how colaplete have been the investigation and testing programs.

Figure 8 shows the influence of aquifer permeability on

cost per acre foot of water. Three heavy dots represent optimum

design for each permeability value. The curves radiating from

these points show the effect on water cost when actual permeabil.4y

conditions differ from the assumed value. When an incorrect per-

mehbility valuc is assumed, the cost of water is higher than when

the correct value is used. However, as can be seen in Figure 8,

the magnitude of deviation from optiimum varies with the choice of

assumed 'permeability. Thus, even though actual permeability at

each site is unknown, a value for use in desii'n can be selected

which results in minimum cost of water over a broad area if

distribution of permeability for the area is known

i'ortun;t:ely the variation of aquifer permeability in

the water yielding formations of the Punjab is rather small from

the geological point of view (Figure 9). Nevertheless, such a

variation, as well as practical considerations, defy the possibi-

lity of site by site estimation and establishing a precise per-

meability for design of every tubewelle






-14 .

Figure 9 shows the distribution of aquifer permeability in.;:

Chaj Doab based on samples from installed tubewells, The mean value,

is (1.65 + 0.06) x 10-fps at the 95 percent probability level.

Considering this distribution and the effect on water cost shown

in Figure 8, a permeability value of K = 1.5 10 -fps has been chosen

for tubewell design purposes for this area.- There is evidence that

a.similar distribution occurs over the Punjab as a whole. If so, a

design permeability value of 1.5 x 10-3fps can be used over Ihe

entire region. However, if adequate test data are available to

determine permeability distributions for specific project or scheme

areas, savings can result from estimating individual design per-

meability values for each area.

Screen radius: Given an optimum design value for -'

permeability, the cost of components and other considerations,

optimum screen radius can be chosen. The primary choice criterion
17 T eoretl celermination o? an optimum design value For pesa
lity from known water cost and permeability frequency relations
can be demonstrated. Let
C =#1(Kd, K,. Qd

F =b2 (K)

where C is unit water cost, K is design permeability, K is
permeability at the site, Qd as design discharge, and F is the
frequency function of permeability in a project area. The
weighted average unit water cost is


Ave. 2 (K dk

where K and K2 are the upper and lower limits of aquifer
permeability.

The optimum design value for permeability (Kd opt) can.be
obtained by solving



From examination of Figures 8 and 9, it is obvious that
the optimum design value for permeability for this area is
near, but smaller than, the mean K value .





.5 + . .-''

is.cost of water including consideration of both initial construction ... ,

cost and power cost.

Figure 10 shows the cost of water from a 2 cusec tubewell

with three screen radii, screen length being optimum in each case:.

Over all ranges of utilization, the cost of water from a 6 inch

screen (3 inch radius) exceeds the cost from 8 or 10 inch screen

There is no significant difference in cost between the latter. On the

basis of water cost, it appears that a 6 inch screen can be eliminated.

but thore is no means to choose between 8 and 10 inch screen. From

Figure 11, showing initial construction cost, the slight advantage

of the 8 inch screen is apparent. If capital for project construction

is scarce (perhaps more scarce than the 4% percent rate of interest

indicates) then this factor should be considered as the criterion in

choosing between screen of 4 and 5 inch radius. Alternately, if

power is relatively more scarce than capital (though the Rs 0.07/KWII

is quite high) the choice would have to be 5 inch radius (Figure 12).

For a 3 cusec tubewell the cost of water criterion alone

favors 10 inch screen though by only a small margin (Figure 13). The

initial construction cost and power cost criteria produce the same

conflicting; choices as for the 2 cusec tubewell.

The choice of screen radius for 4 and 5 cusec tubewells is

more cle.ir cut based only on the cost of water criterion. In those

two cases the savings in water cost definitely favor the larger

screen (Figures 14 and 15).

One further consideration can aid in choosing between 8

and 10 inch screen for the smaller capacity tubewells. Cost of

shipment of the screen is based on yardage rather than weight.

Eight inch screen can be inserted in 10 inch screen for shipment,








16

making an important savings in overall cost. In the absence oi

another definite choice indicator, this consideration favors the

use of 8 inch screen for the smaller capacity tubewells.

Optimum screen radius, therefore, is taken to be 4 inch

for 2 and 3 cusee tubewells and 5 inch for 4 and 5 cusec tubewells.

Tubewell capacity: Occasionally situations arise when a

choice can be made between tubewells of different capacities, e.g.

two tubewells of 2 cusecs capacity could be installed or one 4

cusec tubewell serving two closely situated watercourses could be

substituted. The cost of water criterion favors larger tubewells

in such situations (Figure 16). This results primarily from the

greater construction cost associated with two tubewells versus one

tubewell. However, if limited power generating capacity is an

overriding consideration, the larger number of small tubewells

would be chosen (Figure 17),

Screen Length: As shown previously, length of screen is

a function of a large nunb-r of variables. It has been shown that

screen length varies with such factors as tubewell life, rate of

interest, cost of screen, cost of power, length of blank pipe and

annual utilization. In the past it has been a practice to consider

screen length primarily as a function of tubewell capacity, ie.

L = AQ. This practice provides an easy means for determining

screen length in the field and, when A is properly chosen, results

in tube;wlls of relatively high economic efficiency. However,

because many other factors affect screen length the initial cost of

some tubewells thus designedl is higher than necessary and in other

cases a greater pumpini7 head than necessary is produced. Figure







17-

18 shows the relationship between screen length per cusec of tubewell

discharge and utilization. Also shown for comparison are screen

lengths resulting from the practice of considering screen length

only as a function of tubewell discharge. The difference in the

magnitude and shape of the curves is an indication of the error

which can occur by an overly simplified method of screen length

selection.

Summary

Length of screen is the most important controllable

factor in tubowell design. After values for the fixed factors have

been established and capacity and utilization factors for a specific

tubewell have been determined, optimum screen length can be calculated

by a simple process on site at time of drilling.

Figure 19 is designed to be used in conjunction with the

weil log to determine optimum screen length and concomittant lengths

of housing and blank pipe as well as total depth of well. Based on

equations and values of parameters developed previously, graphs such

as Figure 19 can be constructed for various combinations of water

tahle and utilization factor anticipated. As drilling proceeds,

the inspector would lo- length of blank pipe required as shown by

the dashed line. When the log intercepts the curve in the upper

right hand quadrant corresponding to the capacity of woll being

drilled, approximate well depth would have been reached. A horizon-

tal line drawn to the left from the point of intersection to the

appropriate curve in the upper left quadrant specifies optimum

lergth of screen and a vertical line from this point to the appropriate

curve in the lower left quadrant specifies proper length of housing




*' ; ., .. . ( .8 ,, ,'., -:,


pipe. Rounded values of blank pipe, screen ani, housing: wiou-ld be'

entered in the lor,'r right corner and thtkir sum would giv? actual

well depth.

Thus, embodied in Figure 19 are all the components of

tubowell design which can be measured and specified at time of

tubewell con-truction. The use of this figure provides a simple

process by which tubewells of optimum dimensions can be constructed

throughout a project area. Becau e of the ease of incorporating

this process, it can be substituted for other methods of tubwwell

design which result in non-optimum dimensions for many wells in a

project.





Definition of Symbols


D Length of blank pipe (feet)
b A factor indicating blank pipe as a percent of screen length
C, Annual cost of electricity (rupees)

CI Initial Tubewell construction cost in rupees (including
only those items which vary with screen dimensions)
CIA Annual cost of tubewe.ll construction (rupees)
C Annual variable cost of water (rupees)
JS -iffPect 0f a 4taurr C70ei
D. Amount of drilling at various depths (feet). When D) -300'
i = 1; 5 0') < ) ) 400', i= 2; 400' < D 500' i = 3.
w w
D Depth of well (feet)
w
f Pipe friction factor
G, Depth of gravel shroudin,; (feet)
g Acceleration of gravity (feet per second per second)

IId Total dynamic head (feet)
II Length of pump housing pipe (feet)
Ht Total pumping head (feet)
hf Friction loss in column pipe and discharge pipe (feet)
h Discharge velocity head (feet)
V
K Aquifer permeability for water (feet per second)
Kg Gravel pack permeability (fert per second)
L equivalent length of column pipe and discharge pipe (feet)
L Length of screen (feet)

Pb Unit price of blank pipe (rupees per foot)
1' Unit cost of drilling (rupees per foot)
PG Unit price of gravel shrouding (rupees per foot)
PtG Unit price of pump housing (rupees per foot)
' Unit price of screen (rupees per foot)
Q Tubewell discharge in cubic feet per second (cusecs)
rs Radius of screen (feet)
r Borehole radius (feet)
w
s Total tubewell drawdown (feet.)
U Annual utilization expressed as percent

Vt Ultimate depth to static water level (feet)












COST PER ACRE FOOT OF WAT Vs


IOO
i00


I
200


300


4
400


S TUBtWELL CPAL\PLTY = 4 cUSt$CS
5CREE(N RAN1US = 4 N .
EPTHR TO STATIC, WATtR. LEAVE L= 20 FT .
LIFE OF TUBtWELL = 15 Y'EAV5
-UTILtZATION FPLTO. 60 %o
N-TEREST RATE = -43 'o


10













5


I co


Fsn

too 200 300 AOO
- I I I i IN .., 1I I -
TUBEWELL SCREENN LENGTH ,r.


FIGURE. I


__ _ __ __


.t _.I.' C-
rUsCrwF~:~.sCa~E~N LLNGTH.


5 rUiiM - TOT L Co ST




~-:



:-

:: 2: : - i




*.


..v
i.


~;~ : r
'i t.

''-
?'i "i

";; :': r
"
: d


5lANK P!P As EC4~C~r EQW5 CREET L~N~iVH Y. OPTriii4Uh~ Lthc~H sFi
3' '3 3


-j


I')

I,w
LI.
03




ul


4








II
z



3jfl


vu174zkf0i'$ r-CArfr 3-60

f- .S -ELP4 4 irN

TO _iTA11I C. 'WTtz EML: 2 OF-t


OprrmUM 5CRE.EN LE.NC-H -Pr.


3 4 3 3 .
4;r. 3 ~ i


-i


<913

70



~i.


S3- 0I
300. * .


~ -~- -~- -~ m


''
1

i

I
r -
a
:::
-~; -;~.h--'

i
L\
'


1 -~




i

'"

`i
..' :p
2:


333L


S C.P e N


33


.i.
'2


I

,- I..- r


+r
:
r
r
-:

,X
' ~

~
: -


"
i
i .



\jI

;I: ~u




z







: i
: .~
.-





i

;r









c



1.:
1 :

~ ;..
-



...



r



i 1-- :


PIGURE 'Zi





S


PRICE. OF SCAECN Vs. OPTIMUM SCREEN LE1I'TH

50 loo 150 200 250 300


UTILZAOto t r-c-TOR GO
1LojUS oF Sc 14 w .
M4 TO ST-TIC. watlc. .EEV= 2OFt.


~80

Iso
z 70-




LL) 170:) 701
LA)





60 6






r 5050.
50 10. 0o.








OMMTIUM SCREEN LENMT~H.

FI.C4URE
4. 4




47 *0


TILlZ4 TOR Viw.1 OPTIMUM


300


80 -


70






GO


/














or
U,





a!


OPTIMUM: C' E.E LENGTH, FT.


mUoRE. 4.


o 100 "


4
I


/
/

/


i!


1.










3-
0->


DEPTI TO STATIC WATER LEYTL= 20~.,


SCLE RDlU5 = 40


40-


- ` 1 -- ---~--~---'--


5CrZ55N iLNLT~::


de

















POWER COST Vs. OPTIMUM SCREEN LLECGTH

- too. --- T
oo00 200



; "


0.11


17/



U/ U/

b/


/


/ RADIUS OF SCREEN 4 N4
SOTEP TO STl I c-A WkErLt.EL 20 FT.
UTIUZATIOoN FACTOR = 0%


200


OPTIMUM SCRLED LESJCTH, F-.


FIkURE. 5.


0.11


-0. 09


-0.07


/

/
/

I-,/


/


'-I

u


/


-o.os


/


0.09 J


0.07-






0.05-















RATE OF INTEREST YV. OPTIMUM SCREEN LEJN4G


50 100 150 200 250 300





-20 DEPT o -IQ SAI.IC WAs. LevrL- =2O v. 20 -

SRMDU5 OF SCREEN = 4 .
\ UTILIZATION FACTOR f%
5 \ \






0

0\ to
















50 too 200 250 300
15 I \ 15



\ +3 *











S\ \ \




90 rO0 MSO 200 2.5 300
.,I1 I I _1__ 1 ____t ,_I _


OPTIMUM SCREEN LENGTH, Fr.

FIGURE 6.


"*

u"

..
r- c;
~ir


:







NV.



















LIFE OF TUSEWELL Vs. OPTIMUM SCRS.Er .LENG I i
-~ r rr













20& .woo
2so2















I,
I. I












h-40 -. I I


; ; i.: i/



:h. ~/1
/


U


soL .. 200



O..Pu.Ai .SCREE.N IENGTHi, FT.




M CAGL. kE


f
24





























RWW~j OF SCREWi .

EPIH *TO S~IIC. "MTE Wjv 20-v,.


250. s oba




I -








*' .


LU







Lo










LL
0
lu


O.




*.*
:- * : ;
' .i.*: i' ^ '-. fl '1'- ':



























^* "/ : ^ i. .*:: -p


c


r





',
'














: ;
'. -i
r3


4 :- ~





-i


~I;~ ,d










i .i



.:.i?
z
, ; rl. -- .P '?~
r

; r,
"; - -: ~ " : --.:
; ":
: j
b

a
I



i I


"~1

:;
.r
-


;.





1, z.


-




~~


~








3-


'

,-~ I
i
i,-
J


~-:

"
~
~. -



-~~- St.si;


* :'


.



~


~ - .-





'
i .


-;.


r C;


I .
:;

61.


_--I-


i.

,
,


'' ~-
.-if








I i. I' 2I I
n 1.0 2.0 2.5


TUMWALL, CAPACITY =4 CUSCES .
52.tEN A'US A 1N.
D\ PTH TO STATIC 'WTEi. LEV EL 2o0r.
TnlLZ.ATMoN VTorv 60.







3Pon'Um DEmIq W/mt. CoeUixrLT
ASuaJ1ss AWJ'FeR PBMEASiLrFY
ppljrMUM dAt L"JW&Gthe DESlGNLD
ON THE 54IS 'O A ,iQre PERMM.,ILTy "
- .= 9"74 BSI' O .6..'"a L


ON T.. As AAut5o 1E:,U-TY
K J.50 tolI FT/E. . -


----OPTIMUM 6tCAEeI LQT14 DESrtIGND On
TE SAas ov AQUIVEIR 9U 1ssLWBY
K .--2 .o. m Fi.irsec. O
I I


2.0
t .


2$


AQUIFER. PtRME8BluTY, IO FTr/sc.

FTc4UE 8


FIGURE 3


v
at



LL
0







t-



8
ll)
;

Qt


10.


i ~b,
r
F.





COST OF WATER Vs RPADIS OF SCR.Et


A e 0 d


TU BWELL CAPK'TY 2
DEPTH TO 5TATIC WATER LEVEL


40 60 80
I I


UTILIZATION


FACTOR, PERCENT.


FIGURE 10


CUSEC5 I _
20 FT.




t0O


.* **


I)






~


L14


TU&eVEAu. CAPACITY

A... DEPTL ~ UAEL


CU LSEC~r.

-= Z F'r.


UTILiZATION FACrD PE.CCEPt I


MFGURE A4



A.-* A


I
,tgo


40
I


-*


_


C T R-.





*NITAL CIOH$TVRUCTON CO$ VJ-i RADi&)S. OVF 5CIIUJ~


I ~


-'
2

ir


j
;:
~ 1 :..


-1 ..~. .


-.C
[. :,. ,''
-
r


s0
I


, .


,

i.
;











POWER COST Vs R.ADIUS OF SCREEN


TuBEw utL CAPAcATY = 2 CU5ECS
DEPTH TO STATIC WATER LEVEL = 20 FT.


UTILIZATION FACTOR PE cE.NT


FIGURE 12.


-575














-5.25






5.00






-475


Si









5.2S -_






5.00






4.-75.


I- -i


:, ...

i;













COST OF WATER Vs RADIUS OF SCREEN


06 60 SO



10 to





9 9










DEPTH TO STATIC WATER LLVEL 20 Ft.
in -87 7-
0








FIGURE 13












COST OF WATER Vs RAtDIUS OF SCR tEE


UTIL\2ATION FACTOR PERCLi


FIURE 14


__ I

.%;


'
'










COST OF" WATER Vs. QADIUS OF SCRaiX


40 60 b


TUSEWYALL CAPACITY= S CusECS,
S DEPTH TO STATIC WATER LEVEL 20 Ft.
-14 I : 14


SI UTILIZATI ACTO PE
UTILIZATION -FACTOR. P-.CENT .


GU CE 15 .













COST OF WATER Vs TUBEWELL CAPACITY
(OPTIMUM SCREEN DIMENSION)

40 60










uo -9
0 s




1' "
06






U 7


UTILIZATION FACTOR, PERCENT


FIGURE 16











POWER COST Vs TUBOWELL CAPACITY
(OPTIMUM SCREEN DIMEN51ONS)


-5.5


- so


4.5


EPTH TO STAC WATER LEVEL 20



DEPTH "TO STATIC WATER LEVEL = ZO Fr.


4.0-


40 GO 80
U II I A ,
UTILIZATION FACTOR PERCENT.


FIGURE 17


5.0_


-A.4


r 1














-SCR.EN LEN.CTH PER CUSEC Vs. TUBEWEUL CA.Pb~\TY


40 60


LI/Q = 50 ; Q 34,5 CUSECS


/., ..


/

BASED ON SIMPLIFIED
METHOD


Ls/Q= 40; Q=2 CUSECS


Z /.
/7,f-


NOTE'. DEPTH TO STATIC. vATER LEVEL= 2.0 FT.
SCRCLEN RADIUS Fo. 2&3 CUSEC TUBEWELL= IN.
SCR-.EEN RADIUS FDo 4 & 5 CUSEC TUBIEELL= 5 IN


i 35 8 O

OPTIMUM DESViDN



S A 60

UTI LtZATION -ACTOR PERCENT.


FIGURE: 16.


50






45






40































Uj


/

c,


Qf
C/ s- ___




to0 t5o 200 250
DEPTH OF WELL, r-





UTILIZA1TION FACTOI=60%,
TO STATIC WJVTEP. LEVEL 20PT-


300 35)


4- cs.


F!CUEL 19


4~

p,
0'








*r


j




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