?
?
Tank
Farm
?
N
?
?
?
?
?
?
?
?
?
?
?
?
?
b. Presence or absence of unfrozen
materials below the permafrost.
Aquifers are usually present
within the unfrozen materials. In
the first unfrozen classification, the
following applies--sediments
thawed to bedrock; water bearing;
bedrock presumed thawed. In the
second classification, the following
applies--sediments thawed be-
tween permafrost and bedrock;
100 m
subpermafrost aquifer present. In
the third classification, the follow-
ing applies--water not encoun-
Unfrozen
tered during drilling through
weathered bedrock surface; locally
d
Permafrost Present to
sporadic and discontinuous thaw
an Unspecified Depth
zones may be present at the sedi-
Permafrost Generally Extends
ment/bedrock interface, especially
Through Sediments into Bedrock
Tr
ainor Gate Rd
near thaw zones and adjacent to
at an Unspecified Depth
subpermafrost aquifer.
Figure 10 (cont'd).
Thus, there are large areas where sediments are
Because of its lateral extent, this area forms a nearly
perennially frozen an unknown depth into the
impenetrable barrier to deeper ground water mi-
underlying bedrock (Fig. 10b). Such areas later-
gration from the east and south of the Truck Fill
ally confine unfrozen and deeply thawed areas
Stand, where there is a subpermafrost aquifer in
from one another, thereby affecting ground water
unfrozen materials beneath the permafrost.
flow. In other locations, permafrost thickness is
The data on bedrock depth indicate the exist-
less than the depth to bedrock; underlying sedi-
ence of a buried valley trending northeast to south-
ments are unfrozen, as is the bedrock beneath
west across the site in an area of discontinuous
them, and they generally contain ground water.
permafrost (Fig. 13). Because much of the Truck
A particularly extensive area where bedrock is
Fill Stand area is characterized by unfrozen sedi-
relatively shallow and sediments are frozen into it
ments beneath permafrost, the bedrock valley ap-
lies south and east of the Tank Farm (Fig. 10b).
pears to provide a connection for ground water in
11
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