areas that may be some of the geo-
logically oldest surficial materials on
Birch Hill
Fort Wainwright. The top and bottom
surfaces of the permafrost also have
highly irregular relief and can sub-
Road
Tank Farm
Railroad
stantially influence ground water
movement (Fig. 2).
0
200
400 m
Ground water flow within the can-
tonment area of Fort Wainwright (Fig.
ad
Ro
ill
1) is necessarily complex. This com-
H
ch
Truck Fill
plexity reflects not only the presence
r
Bi
Quarry
Stand
or absence of permafrost but also the
structure and stratigraphy of the sur-
face sediments, the thickness of un-
frozen materials above the permafrost,
N
the total thickness and depth to the
bottom of permafrost, and the imme-
diate sources of ground water. These
sources include the ChenaTanana
d
oa
River system and more local aquifers
R
r
ve
such as Birch Hill (Pw 1958, Will-
Ri
School
Che n
Test Grid
a
iams 1970, Shannon and Wilson, Inc.
R
1992, Lawson et al. 1993).
Tr
ai
Two types of ground water systems
Shannon Park
no
rG
Subdivision
ate R ad
exist: a laterally discontinuous, near-
o
surface system above the permafrost
ROLF
(suprapermafrost), and a deeper one
beneath the permafrost (subperma-
Figure 1. OU-3 sites north of the Chena River, including the Tank
frost) (Lawson et al. 1993). The supra-
Farm, Truck Fill Stand, Canol Road pipeline and Test Grid.
permafrost and subpermafrost aqui-
fers are linked where the frozen
swales or former stream channels, roads, buried
ground is perforated by isolated thaw zones (sur-
pipelines, building excavations and other areas
rounded by permafrost, but unfrozen to bedrock),
cleared of vegetation (Lawson et al. 1993). The
and in more extensive unfrozen zones, typically
bottom surface of the permafrost commonly
within former stream channel or swale deposits.
ranges from 10 to over 50 m deep, with a mini-
Isolated thaw zones (taliks) may be areas where
mum thickness of a few meters adjacent to thawed
the subpermafrost aquifer discharges or recharges,
areas, and maximum thicknesses over 80 m in
exhibiting either upward or downward vertical
Figure 2. Stacked, three-
dimensional representa-
tions of upper and lower
surfaces of permafrost in
the Canol Road "Test
Grid." Permafrost is ab-
sent in those areas of the
figure where the upper
surface appears to be at a
lower elevation than the
bottom surface.
2
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