TM 5-852-5/AFR 88-19, Volume 5
destroy intake structures. Some facilities remove the
such wells are high. The water must be protected
intake structure during those periods and rely on
from freezing and the permafrost must be main-
temporary storage. Development of intake galleries
tained in a frozen condition. This requires special
or wells in the stream bottom is successful for
well casings or grouting methods and unique opera-
avoiding ice problems, but it is difficult to locate the
tional methods. Subpermafrost water is generally
permanent channel in alluvial and braided streams.
deficient in dissolved oxygen and can also contain
The summer flows are higher in volume than the
high concentrations of dissolved iron and manga-
winter flows but they are poorer in quality,
nese salts. Hardness is also common. Dissovled
containing sediments and glacial silts which may be
organics can also create serious treatment problems
difficult to remove. For example, the Kenai River
due to interactions with the dissolved iron and the
near Soldotna, Alaska, has suspended sediment
color imparted to the water. The most reliable and
concentrations up to 151 milligrams per liter (mg/L)
economical ground water sources in the Arctic and
in the summer months. These sediments are
Subarctic are in the thawed zones adjacent to large
primarily glacial silts and are almost colloidal in size.
rivers and lakes. Most of the rivers are braided
b. Lakes. Deep lakes are a reliable, continuous
streams and have shifted their channels many times.
source of water. The quality of any liquid beneath
The former stream channels may still be underlain by
the ice in a shallow lake or pond is typically poor.
thawed material and represent a potential water
Impurities, such as most salts, are rejected from the
source depending on the type of soils involved.
freezing water, making the ice relatively pure but
3-5. Other water sources.
concentrating the impurities in the remaining liquid.
Snow, ice and direct catchment of rainfall are
A survey is required to identify lakes and ponds that
potential water sources that must be considered for
may freeze deeply enough to create this condition.
augmentation or emergency supplies and for small
Chapter 12 discusses the thermal aspects of such an
or temporary facilities. The natural quality of these
analysis.
sources is good but a stockpile of snow or ice can
c. Saline waters. Distillation or reverse osmosis
be easily contaminated. Large volumes of snow are
is used to treat saline or brackish waters; these
required to produce even small quantities of water
procedures are costly and energy intensive, so such
and the costs for harvesting and melting are high. It
sources will be avoided except as the last resort.
is estimated that 4 to 5 cubic feet of snow are
d. Augmentation. In the Arctic most of the
required for every 5 gallons of water produced, and
annual precipitation is in the form of snow.
to melt this volume of snow would require about a
Although total precipitation is low, advantage can
pint of diesel fuel for the snow melter. Brackish and
be taken of the windy conditions to induce snow
saline ponds have been improved in quality by
drifting at selected locations. Collection of the
pumping out the concentrated brines that remain
melting snow augments the summer water supply.
under the ice near the end of the winter and allow-
Snow fences were used to induce drifting in the
ing fresh spring runoff to recharge the pond. If
watershed of the Barrow, Alaska, water reservoir.
repeated several times the procedure allows the use
It was shown that at least 800 gallons of water was
of an initially unacceptable water source.
collected for every linear foot of 5-foot-high snow
fence that was installed, with the fences about 250
3-6. Structures.
feet apart.
Structures range from wells and their appurtenances
or simple temporary intakes on river ice to a
3-4. Ground water.
complex dam structure located on permafrost. The
Ground water can be a more reliable water source
complete structural design of any of these is beyond
than surface supplies. It is usually available on a
the scope of this manual (TM 5-852-4/AFM 88-19,
year-round basis and is more consistent in its
Chap. 4, discusses embankment construction on
temperature and mineral quality than surface
permafrost). It is the intent of this section to point
sources. Very shallow ground waters are unsuited
out those features that may require special attention
for potable water supplies without extensive treat-
in the cold regions.
ment and the yield is limited. Subpermafrost ground
a. River intakes. A permanent intake structure
water or permafrost zones thawed by large rivers
will usually be employed for large-scale permanent
and lakes are the most reliable sources. Sub-
military facilities in the Arctic. Structural damage
permafrost wells are technically feasible when the
from moving ice in the spring and in the fall is the
permafrost extends to a depth of a few hundred feet
major concern.
or less and they have been successfully used in cen-
(1) Temporary intakes. These are less expen-
tral Alaska. Costs for drilling and maintenance of
sive, and are removed from the river during spring
3-2
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