TM 5-852-5/AFR 88-19, Volume 5
condensation and a vent blocked with ice will result
other arctic and subarctic structures and are covered
in an vacuum in the tank as water is withdrawn and
in TM 5-852-4/AFM 88-19, Chap. 4. Foundation
possibly cause the tank to collapse. Overflow piping
design for tanks is complicated by the very high
will either be inside the tank or protected with insu-
loads imposed by the stored water and the need to
lation and heat tracing if placed on the exterior.
keep the water in the unfrozen state. The unfrozen
Since ice can damage float type water level indica-
water is a heat source that can have an adverse
tors, the pressure transducer type is recommended.
effect on the underlying permafrost and must be
Temperature monitoring at various levels for control
considered during design for a tank on grade.
and for alarms will be included in the design.
5-5. Earth reservoirs.
b. Thermal considerations. Whenever practical,
tanks must be buried or covered with soil to reduce
Water impoundments for domestic and industrial
the effect of low air temperature. Elevated tanks
water supply and for hydropower have been suc-
must be avoided unless they are absolutely neces-
cessfully constructed in the Arctic and Subarctic.
sary for the water distribution system since they
The most likely configuration for military facilities
expose the greatest surface area to the worst cli-
is an earthen embankment to either increase the
matic conditions. All exposed tank surfaces and ris-
storage capacity of an existing lake or stream or to
ers for elevated tanks must be insulated. The eco-
impound water in a natural drainage swale. Con-
nomical thickness of insulation can be determined by
struction of these embankments must be in accor-
the calculation procedures in chapter 12, paragraph
dance with TM 5-852-4/AFM 88-19, Chap. 4. A
12-9i. Thermal calculations are also necessary to
liner is necessary within the embankment or to seal
size the heating systems used to replace heat losses
the entire reservoir, when permeable soils are
or to heat the water for distribution. The unit
present or used for construction. Successfully used
capacity of a heat exchanger or boiler must be equal
liner materials include Hypalon synthetic rubber,
to the maximum rate of heat loss.
chlorinated polyethylene (CPE) and elasticized poly-
olefin. (See EPA 600/8-79-027 for further detail on
5-4. Tank foundations.
linings.)
Foundation considerations are similar to those for
5-4
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