sources or percolated waters adjacent
(1) Steep slopes.
The flow of
to a turbid surface water.
Well
water from a spring located on a steep
points are issued in 2-inch diameter,
slope of loose earth can be collected
54-inch lengths.
A drive cap is
by constructing deep, narrow ditches
placed over the thread and the well
leading from the spring to the point
point is driven into the ground with a
of collection, or by constructing
sledge.
Successive sections of pipe,
pipeline tunnels from the spring to
each 5 feet long, are added and driven
the collecting point.
Large diameter
until the screen is well within the
pipe is desirable for this purpose.
water bearing media.
Several well
The water from the tunnels can be
points may be connected in parallel to
trapped by constructing a dam at the
supply sufficient water to the raw
point of collection.
water pump. In developing drive point
sources, it must be remembered that
(2) Digging.
Digging is a more
the pumps issued with field equipment
positive and more economical method of
only have about 15 feet of practical
developing a spring than blasting.
suction lift. Pumping water from well
The use of explosives in developing
points deeper than a maximum of 20
the yield from springs should proceed
feet is mechanically impractical.
with great caution because blasting in
unconsolidated rocks may shift the
4.
SPRINGS
sand or gravel in such a way as to
divert the spring to a different
a. Development.
Springs yielding
point.
20 gallons per minute or more of water
5.
SEA WATER SOURCES
can be used as a source of field water
supply if properly developed.
A
common method of development is to
a. Characteristics.
Sea water, as
enlarge the outlet of the spring and
a source, is vastly different in its
reduce loss of water by damming it and
characteristics, as well as in the
conducting it to storage.
methods of purification, from other
To reduce possible pollution, springs
surface water sources.
The chemical
should be cleared of all debris,
characteristics of sea water are such
undergrowth, top soil, loose rocks,
that normal coagulation and filtration
and sand.
are
ineffective
as
treatment
processes.
The
only
economical
b. Collection.
Water which flows
process yet devised to successfully
from rocks under the force of gravity
desalt
and
soften
sea
water
is
and collects in depressions can be
distillation.
Distillation equipment
collected in boxes or basins of wood,
is not normally found in engineer
tile, or concrete. The collecting box
units, but may be requisitioned from
should be large enough to impound most
engineer depots on a need basis.
of the flow, and should be placed
Relatively high cost and low quantity
below the ground level so that only
of distillate production are further
the top is slightly above the surface.
limiting factors.
Therefore, sea
The box should be covered tightly to
water should be used only when surface
prevent
and
lessen
or ground sources are unavailable or
The inlet should be
inadequate to meet demands.
designed to exclude surface drainage
and prevent pollution.
This requires
b. Development.
In
developing
fencing off the area and providing
sea water sources, consideration must
proper drainage.
Figure 8 shows a
be given to such factors as surf
spring inlet which has been protected
action,
salt
water
corrosion,
in this manner.
The screen on the
suspended
sand
and
silt
in
the
overflow pipe prevents the entrance of
water, living organisms, surface oil
insects and small animals.
along
beaches,
and
the
rise
and
3-7
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