TM 5-852-5/AFR 88-19, Volume 5
b. Infiltration galleries. Infiltration galleries re-
c. Wells. The basic procedures for water well
move the structure from risk of ice damage and
design are discussed in TM 5-813-1/AFM 88-10,
thereby offer advantages over direct intakes. Figure
Vol.1. The special concern for subpermafrost wells
3-4 illustrates several configurations of infiltration
is not to allow thawing of the permafrost during
galleries that have been used successfully in the cold
drilling and during operation of the well. The former
regions. The gallery is placed in thawed material in
may require either compressed air or non-toxic
the stream bed or adjacent to it. The yield will
drilling muds or fluids with rotary drilling
depend on the type of soil present. Importation of
procedures. Avoidance of permafrost thawing dur-
coarse-textured material will be necessary for
ing well operation may require multiple casings so
gallery construction in fine-textured silty and clayey
that cold air can circulate in the annular spaces.
soils. Both electrical and steam lines have been used
Concurrent with protection of the permafrost is the
in galleries to prevent freezing. Steam lines are
necessity of maintaining the water in an unfrozen
usually placed on the upper surface of the intake
state and this will require heat addition for an
laterals and on a second level about 1.5 feet above
intermittently used system. Figure 3-5 illustrates a
that. The heating elements or steam lines are not
typical cold regions well with a submersible pump in
normally operated continuously but are used only in
non-permafrost conditions but designed for frost
emergencies to restore a frozen or partially frozen
and heave protection in the surface soils. Bentonite,
system. Springs can also be developed with these
mixtures of oil, wax and sand, and various plastic
same techniques.
coatings have been used on these casings to prevent
3-5
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