Geological and Geophysical Investigations of the
Hydrogeology of Fort Wainwright, Alaska
Part I: Canol Road Area
DANIEL E. LAWSON, JEFFREY C. STRASSER, JODIE D. STRASSER,
STEVEN A. ARCONE, ALLAN J. DELANEY AND CHRISTOPHER WILLIAMS
In this report, we summarize the initial results
INTRODUCTION
of ongoing hydrogeological investigations of the
ground water and permafrost conditions in the
Within interior Alaska, and, in particular, the
northwestern corner of the cantonment of Fort
cantonment area of Fort Wainwright, the perma-
Wainwright. Our work has included developing
nently frozen and unfrozen materials that contain
Ground-Penetrating Radar (GPR) to define the
ground water aquifers are complexly and dis-
spatial and vertical extent of permafrost. Our in-
continuously distributed. Ground water may oc-
vestigations are part of continuing site character-
cur above, below and adjacent to those materials,
ization for remedial investigations and treatabil-
as well as in thawed zones that are within, or
ity studies of contaminant problems on Fort
penetrate through, the permafrost. The perma-
Wainwright (Fig. 1). This facility was placed on
frost controls the movement of ground water be-
the Comprehensive Environmental Response,
cause of its impermeability.
Compensation, and Liability Act (CERCLA) Na-
The fate of contaminants in ground water is
tional Priorities List (NPL) in August 1990. The
thereby linked to both the distribution of perma-
Canol Road area contains two sites within one of
frost and the movement of the ground water with-
the five Operable Units (OU-3) established for
in the adjacent unfrozen sediments. Prior to the
investigation and remediation under the Federal
work discussed in this report, permafrost and
Facilities Agreement (FFA) of 1992, which sets
aquifer distributions across Fort Wainwright were
guidelines for Fort Wainwright on contaminant
incompletely described and known only in gen-
remediation under CERCLA.
eral terms. Therefore, the complex hydrogeological
conditions led to considerable problems for those
trying to locate suspected contaminants, to iden-
General background
The three-dimensional distribution of perma-
tify source areas, to define transport paths, and to
nently frozen ground exerts considerable control
evaluate the fate of contaminant plumes, includ-
on ground water flow in regions of discontinuous
ing their migration off-site. Physical hydrogeo-
permafrost. Transitions from unfrozen to frozen
logical models of ground water flow in this perma-
conditions may be abrupt and without surface
frost terrain are therefore essential to remediating
expression. Further complicating our attempts to
define this distribution are several factors: the
Permafrost may be present or absent because of
current environment, past climatic conditions, ter-
a number of factors, including human and natural
rain characteristics, vegetation cover, historic use
disturbances to the terrain and vegetation, and its
and surface disturbances (Hopkins et al. 1955,
distribution may therefore be chaotic. Identifying
Williams 1970).
areas of permafrost and, conversely, unfrozen aqui-
Permafrost exists at various depths through-
fers within permafrost areas is therefore extremely
out the Fairbanks and Fort Wainwright area. The
difficult. Standard techniques such as drilling or
top of the permafrost ranges from 0.5 to over 15
terrain analyses cannot readily locate frozen or
m deep, with the thickest thawed zones beneath
unfrozen zones except in the most obvious of cases.
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