ware pipes, with open joints, which are laid in the subsoil for
this purpose. This supply is supplemented by the yield
from five groups of Artesian wells. The water supplying
Stockholm is derived in part from a lake and in part from the
subsoil, almost exclusively from the latter during the winter
months. Interesting details of these and other works are
given by Palmberg and Newsholme in their Treatise on Public
Health and its Applications in different European Countries.
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CHAPTER XVIII
WELLS, AND THEIR CONSTRUCTION
The practice of obtaining water by means of wells sunk in
the subsoil is one which dates from the remotest antiquity,
and at the present time a very large proportion of the popula-
tion of the globe derives its supply of water from such sources.
In Great Britain it is estimated that over one-third of the
population is so supplied. Whilst in every other depart-
ment of engineering improvements have advanced with rapid
strides, especially in recent years, shallow wells continue to be
constructed in almost precisely the same way as they were
thousands of years ago. The well-sinker is the most conserva-
tive of men, and in most districts it is impossible to get a
well constructed so as to protect the water from pollution. To
the country well-sinker a well is merely a reservoir to contain
water, and whether this water enters from the bottom, side,
or top he considers a point unworthy of consideration, and
in fact he makes the well in such a manner that water can
freely enter it at all points. The result is, that as wells are,
for convenience, almost invariably sunk in close proximity to
inhabited houses, impurities from the soil, from defective
drains, cesspits, and cesspools readily gain access and foul the
purer water which enters at a greater depth. It is not
surprising therefore that the great majority of such wells
yield water which is always impure, and liable at any moment
to become specifically contaminated and produce an outbreak
of disease. The time-honoured custom of lining the well
x
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306 WATER SUPPLIES
with bricks, set dry, and resting upon a wooden curb, still
almost universally prevails. The brickwork may be carried
right up to the surface and the well left open, or it may be
covered with a lid, in which case it is frequently so left that
the water spilt upon withdrawing the bucket runs back into
the well, carrying with it filth from the surface of the ground
around, and during a heavy rainfall the surface water runs
directly into the well. Where the well is covered up, the
cover is generally near the surface, and may consist of old
railway sleepers or logs of wood admitting water freely.
Even if no sewage matters enter such wells, the wooden curb
and the rotting wooden covering yield putrid organic matter
to the water. Draw wells and dipping wells are also liable
to be contaminated by the dirty vessels let down into them,
by frogs, rats, and other animals getting in, and by dead
leaves and other matters blown by the wind. The animal
and the vegetable substances by their death and decay foul
the water. In wells otherwise carefully constructed it is
often found that impure water can gain access along the
track of the pipe leading from the pump to the well.
In a properly-constructed well no water should be able to
enter except from near the bottom, so that before reaching
the well it must have passed through a considerable thickness
of subsoil, becoming in its course thoroughly filtered and
purified. Various methods of accomplishing this difficult
task have been suggested ; but as there are other ways of
obtaining subsoil water, which are more simple and far more
satisfactory, we may reasonably hope that ere long the
ordinary form of shallow well will be abandoned. Before
describing these other methods, however, the best ways of
constructing wells may be briefly referred to. Where the
excavation is through solid rock, such as chalk, limestone, or
sandstone, the steining, or lining with a cylinder of brickwork
or of iron or other material will only be necessary to keep
out the water from the more pervious surface soil. If bricks
be employed they must be well bedded on the rock with
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WELLS, AND THEIR CONSTRUCTION 307
cement, and the whole of the brickwork lined inside with
hydraulic cement, and the lining continued some distance
below the last layer of bricks on to the exposed surface of
the rock, so as to render the junction as impervious as possible.
The brickwork should also be well puddled behind. Where
the rock is not freely porous water may accumulate in the
loose subsoil, and unless the greatest care be taken it will
enter the well. In the most modern wells cast-iron or
wrought-iron cylinders are employed for lining the upper
portion in order to keep out the surface water and land
springs. Similar cylinders are also employed to keep out
water from fissures which may be met with in excavating the
well. Where the subsoil is clay and impervious these pre-
cautions are of course not necessary. In ordinary wells, sunk
throughout in a porous subsoil, the lining should consist of
two separate rings of 4i-inch brickwork laid in cement and
lined with cement to a depth of 10 or 12 feet from the
surface. As this class of work is somewhat expensive, and
the cement is liable to fracture, either by the inward pressure
of the sides of the well or other causes, earthenware tubes are
now being made by the Leeds Fireclay Company for lining
purposes. These tubes have an internal diameter of 2 feet
6 inches, and cost 17s. 6d. each. The upper edge is bevelled
internally and the lower externally, so that the lower edge of
the upper tube fits like a wedge into the upper edge of the
tube below it, and there are no projecting surfaces outside to
retard the downward movements of the tubes. The ground
having been excavated as deep as can be done with safety, a
tube is dropped in and some well-puddled clay laid on the
bevelled edge and another tube lowered. If properly driven
the tubes fit well together. The tubes are lowered by aid of
ropes, blocks, and cross-bars. Having got in the tubes, a
collier can easily work inside and undermine the edge, when
the weight will cause them to descend. Clay is preferred
for the joints, because cement breaks when the tubes are being
lowered. Of course the joints can afterwards be " pointed "
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308 WATER SUPPLIES
inside with cement so as to make them more secure, and it is
advisable to try all the tubes, fitting and marking them before
using. Mr. Tudor, who has introduced these tubes, informs
me that he has put down in this way as many as twelve 3-feet
tubes in silty land. Other well-sinkers use a wooden curb or
crib of 3 \ feet in diameter. This is suspended and lowered
in the usual manner, and supports the tubes placed upon
it. The space between the ground and the tubes is filled in
with well-puddled clay. Or the well may be constructed in
the ordinary manner, dry steined with 4£-inch brickwork if
necessary, and the tubes then lowered and fitted and puddled
behind with clay. Dry-steined wells at present in existence
might with advantage be converted into tube wells in this
manner. The well itself having been so constructed as to
prevent the possibility of water entering anywhere except at
the bottom, it remains still to cover it in and protect the
top. The best plan is to project the dome of the well 6 or
12 inches above the surface of the ground and securely cover
with a properly-fitting iron cover. By this means easy access
is at any time gained for cleansing or examining purposes.
The pump should be fixed some little distance from the well,
and the drain carrying away the waste water should not go
near it. Every care should be taken to render water-tight
the aperture through which the pump pipe passes, and it .
should be bedded in clay or cement so as to prevent the
water or rats forming a track alongside the pipe through which
impurities can gain access to the water in the well. If the
sides of the well be covered up to a sufficient height above
the ground, the pump may be fixed inside, the handle and
spout only projecting outside. A hooded aperture at the top
can be left for ventilation.
Quite recently I have seen wells the upper portions of
which were constructed from the halves of old steam boilers,
the domed end of the boiler forming the top of the well and
a hole being drilled through the side for the pump pipe to
enter. To prevent the action of a soft water upon the iron,
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WELLS, AND THEIR CONSTRUCTION 309
it is desirable that the whole of the interior should be lined
with cement.
Koch, in his work on Water Filtration and Cholera, whilst
condemning strongly the ordinary shallow well, recognises
the fact that it is impossible to arrange that those already
existing should be abandoned. He therefore recommends
that the construction should be so altered as to remove all
danger of contamination from above. " To achieve this, one
should proceed by filling up the well to the highest water
point with gravel, and over the gravel with sand up to the
very top." Of course an iron pipe should traverse the sand
and gravel and be connected with the pump. A well so
constructed "gives the same protection against the infection
of water as is given by the sand filtration of the great
waterworks. In fact it really gives a greater protection,
since it is not exposed to the many disturbances in the
process of filtration already referred to, and is also not
affected by frost." So much attention is now being given
to perfecting as much as possible the water supply of the
great waterworks, that it is important not to lose sight
of the domestic water supply by pumps and wells. By
improving the wells in the manner explained above, "the
spread of cholera, 1 in so far as it is due to water, can be
restricted to a great extent. It is just in this respect that
a great deal can yet be done." This suggestion of Koch's is
one worthy of all consideration, since the change can be
effected at a minimum of expense, and the result leaves little
to be desired. It is important, however, to remember that
the superficial layer of sand should be at least 6 feet in thick-
ness. Where the subsoil water is reached at a less depth
than 6 feet, probably this method will not afford complete
protection in many cases. Dr. It. Kempster, in his researches
on "The influence of different kinds of soil on the cholera
and typhoid organisms," arrived at the following conclusions :
" White crystal sand, yellow sand, and garden earth have no
1 And of typhoid fever and other diseases disseminated by water.
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3 io WATER SUPPLIES
marked favourable or injurious action on the life of the
organisms. The length of life of the organisms in the soil
depends chiefly on the amount of moisture present. Peat, on
the contrary, is very deadly to both the comma and typhoid
bacillus. The soil acts as a good filter, holding back most of
the organisms, but it is possible for these organisms to be
carried through 2£ feet of porous soil by a current of water."
Where the ground water-level, therefore, is within 5 or less
feet from the surface, the side of the well should be rendered
impervious to a depth of 10 or 12 feet, or, better still, the
water should be obtained by aid of an Abyssinian tube well,
next to be described, driven to at least this depth.
In a great many instances subsoil water can be obtained
without the trouble and expense of well-digging, merely by
driving iron tubes through the ground until the subsoil water
is reached, and fixing a pump to the upper end of the tube.
Such tube wells were first used systematically during the
Abyssinian campaign, hence they are now popularly known
as "Abyssinian" tube wells. They are most suitable for
gravel, coarse sand, chalk, and similar porous water-bearing
strata, and for depths not exceeding 40 to 50 feet, though
under exceptional circumstances tubes have been driven
successfully to a depth of 150 feet. Naturally they cannot
be driven through hard rock, neither are they suitable for
obtaining water from marl, fine sand, or clay formations,
since the apertures in the perforated terminal tube are liable
to become blocked by the fine particles of which such strata
are composed. A pointed perforated tube is driven into the
ground by aid of a "monkey." (The tubes vary from 1^ to
4 inches in diameter, according to the amount of water which
it is desired to raise.) When this tube has been well driven,
a second tube is screwed on to the first and the driving
resumed. By lowering a plummet down the tubes from time
to time, it can be ascertained whether water has been reached
or whether sand or earth is filling up the end of the perforated
tube. When water is reached a pump can be attached and
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WELLS, AND THEIR CONSTRUCTION 311
a sample drawn for examination, and
the quantity available ascertained.
If either the quantity or quality be
unsatisfactory, the tubes can be
driven deeper or they can be with-
drawn and redriven in another spot.
A well of this character is shown in
Fig. 20. Very often, where the
supply from an ordinary sunk well
is limited, it can be increased by
driving one or more of the "Abys-
sinian " tubes from the bottom of the
well. Special pointed and perforated
tubes are employed where the soil is
ferruginous or likely to corrode the
metal of the ordinary tube. Tubes
designed to prevent plugging with
sand are useful under certain circum-
stances, as when the water-bearing
strata contains together with the
sand a fair proportion of grit. In
fine sandy soils, however, it is
better to withdraw the tubes, ram
down a lot of fine gravel, and redrive.
In the "Abyssinian" tube well
the water is drawn directly from the
water-bearing stratum, there being
no reservoir. At first the water
invariably contains fine sand or
chalk, according to the nature of the
subsoil, but after a time a clear water
is yielded. This is probably due to
the removal of all the fine particles
and debris from around the terminal
tube and the formation of a natural
cavity in which the water accurnu-
Fio. 20.-Abys8inlan Tube Well.
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312
WATER SUPPLIES
lates. In suitable localities these tube wells answer
admirably, and not only are cheaper to sink, but yield a safer
supply of water than a sunk well. One man, usually, can
drive the smallest -sized tubes, but three or four men are
required for the largest tubes. In very light soil a 30-feet
well may be driven in less than one day ; in a firmer soil three
days may be required. Whatever the depth of the tube well
an ordinary pump will raise the water, provided the water
level in the tube is within 25 feet of the surface. If the
water stand at a lower level, a deep well pump must be pro-
vided.
The capacity of these tube wells varies with the depth,
yield of spring, and power of pump applied.
The following are the estimates of two of the best-known
firms of well-sinkers.
Size of Well.
Yield in Gallons per Hour.
Authority.
ljin.
150 to 600
Le Grand and Sutcliff
2 „
300 to 1200
3 „
600 to 2400
4 „
1200 to 4400
u»
150 to 900
C. Isler and Co.
2 „
300 to 1500
SI
3 „
450 to 3000
11 If
Messrs. Le Grand and Sutcliff have kindly furnished me
with the following table (see page 313), giving the depth of
well, size of tube, yield of water per hour of a series of typical
wells driven by them, which bear out the above statements.
Not only are these tube wells preferable to sunk wells on
account of the greater freedom from risk of contamination,
but they are much less expensive. The probable cost of a
well can easily be calculated from the following estimates
(see page 314).
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WELLS, AND THEIR CONSTRUCTION
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3H
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Twelve-Feet Tube
with Hire of Plant
and Man to Superin-
tend Driving.
Add for each
additional
Foot.
Pump, Column, and
Foundation.
lj-inch tube
2
3 „
4
£2 4
3 10
7 10
9 15
3s.
4s. 6d.
10s.
13s.
£2 10 to £3 10
£3 10 to £4^10
>» »»
To the above must be added the man's time in travelling,
railway fares, carriage of materials, etc. A well driven recently
in one of my districts to a depth of 17 feet, a 2-inch tube
being used, cost £8:12:4, the items being as under.
17-feet 2-inch tube well . . . . £2 14 6
4 -inch column, pump, and foundation
Hire of man and plant
Man's time travelling
Railway fare and carriage
3 8
1 10
7
12
Total . £8 12 4
The wages of the agricultural labourer who assisted in
driving the tube is not included, but would not exceed 5s.
These prices may be compared with the following schedule
of prices taken from Sir It. Rawlinson's Suggestions as to the
Preparations of Plans for Drainage and Water Supply (Local
Government Board, 1878).
Schedule of prices for sinking wells in Clay, lined with
9-inch brickwork in Portland Cement. Wooden curves,
cylinders, and pumping extra.
4 feet diameter to depth of 200 feet, 50s. per foot run.
5 „ „ 200 ,, 65s.
200
200
85s.
105s.
Rough estimate of well-sinking, through Clay, Chalk, and
Gravel, entirely exclusive of brickwork or fittings.
Diameter of Well.
Depth.
Price per Foot of Depth.
Total Cost.
4 feet
5 „
50 feet
50 „
3s.
4s. 6d.
£7 10
11 5
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WELLS, AND THEIR CONSTRUCTION 315
Where hard rock has to be pierced or where the water-
bearing stratum lies at a considerable depth below the ground
surface, the well must either be excavated or bored. The
cost of sinking as compared with boring is so excessive that
nearly all deep wells are now bored Not only is the cost
much less, but as the bore -hole is lined with metal tubes
(which should be of wrought iron, lap -welded and steel-
socketed), surface springs are excluded, and the possibility of
contamination reduced to a minimum. Various methods are
employed and many different kinds of tools, according to the
nature of the strata to be penetrated, and the depth and
the manner of the borings, which vary from 3 to 12 inches
in diameter ; but in soft rock, like chalk, this diameter may
be greatly exceeded. In the majority of cases the borings
are made from the bottom of a dug well, the object usually
being twofold : (a) to form a storage reservoir for the water ;
and (b) to provide a receptacle for the pumps. It is, how-
ever, found that in many cases the dug well can, with advant-
age, be dispensed with. It is only really necessary where the
spring is weak and the demand for water intermittent. Such
dug wells, unless very carefully constructed, also increase
greatly the liability to contamination by surface water.
During the process of boring a number of springs may be
tapped, and the quality of the water yielded by each can be
ascertained by analysis. If it be ultimately found that one
of the upper springs yields the most suitable water, the tubes
can be withdrawn and the hole plugged at such a depth that
only water from that particular spring is supplied. In the
older wells the tubes lining the bore are usually not con-
tinuous, and water from divers sources has free access to
the wells. In the more modern borings larger tubes are
used for convenience in boring, and a smaller tube with tight
joints is then inserted, reaching from the surface to the bottom
of the well. The outer tubes may be afterwards withdrawn
or the space between the two filled in with cement. With
such a continuous tube the pump can be so attached that
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316 WATER SUPPLIES
the water is drawn directly from the bottom of the well.
The conditions which influence the yield of water from
bored wells are so lucidly expressed by Mr. R. Sutcliff,
in a paper read before the Brewers' Congress in 1886,
that no apology is required for reproducing them here.
" The continuous tube," says Mr. Sutcliff, " has an important
bearing on the yield from the spring; the weight of the
atmosphere being removed by the pump from the surface of
the water in the tube well. This, as regards the velocity of
the flow of the spring, is equivalent to drawing the water
from some 34 or 35 feet lower than is possible when the
weight of atmosphere presses on the surface of the water.
The increase in supply under these conditions is equal to
about 40 per cent, which acts as an important compensation
for absence of storage. It may be interesting to give an
example of this. A dug well, 25 feet deep and of 5 feet
diameter, will hold 3050 gallons of water. Suppose that
such a well is supplied by a spring which, when the head of
25 feet is removed from it, will flow at the rate of 950 gallons
per hour. As the maximum flow is only obtainable after the
storage is completely exhausted, the average yield must be
taken until that exhaustion occurs. Let the pumps be started
to draw 1500 gallons per hour, the quantity obtained by
storage will be exhausted in two hours. But as in that time
the spring would have been yielding an average flow of, say,
700 gallons per hour, the well would not be emptied until
the pumps had been going about four hours. When that time
had expired, the spring would be yielding its maximum of
950 gallons per hour, and the speed of the pumps would have to
be slackened proportionately. Under these conditions, a total
of 11,500 gallons would be drawn from the well in ten hours.
" Let a tube well be placed under exactly similar circum-
stances as regards supply and water level. The pumps draw-
ing from a tube well could get 950 gallons per hour plus 40
per cent; that is to say, 1330 gallons per hour. Therefore,
the tube well would in ten hours yield 13,300 gallons — a gain,
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WELLS, AND THEIR CONSTRUCTION 317
in that time, in spite of absence of storage, of 1800 gallons ;
and the pumping from the tube well could be continued uni-
formly at the same speed for an indefinite period, so long as
the spring maintained its flow.
" When the normal level of the spring is not sufficiently
near the surface, or the flow is not rapid enough to enable
an ordinary lift pump to draw the water, the tube well must
be made of such size as will enable a deep well pump to be
placed in it, as far below the surface of the water as may be
necessary to obtain the required supply. A deep well pump
can be placed 150 or even 200 feet below the surface; but
when it becomes necessary to place it at that depth below
the water level, the supply required is one that is very great
compared with the spring that yields it. Because, although
all springs increase until the base of them is reached, that
augmentation is a constantly decreasing one. The reason for
this decrease is obvious. The water flows through channels
of fixed area. When the head of water is removed, the
pressure is increased proportionately with the depth that the
water is lowered; but the friction of passing through the
channels also increases. So that to double the supply that
flows at 150 feet below the head of the spring, it would be
necessary to place the pump 600 feet under the water. These
facts are of the highest importance in deciding whether a
given spring can meet the requirement of the consumer.
Let it be supposed that two borings are made, and that
springs are tapped by these borings, which both overflow the
surface of the ground at the rate of 10 gallons per minute.