MW-6
MW-4
N
A-1
Soil
MW-1
Boring 11
Soil Boring 9
A-2
MW-2
2.0
2.3
A-4
Soil
Soil Boring 8
1.8
Boring 6
1.4
T-1
T-2
1.4
1.8
A-3
1.6
1.5
Soil Boring 4
2.6
Soil Boring 5
Soil Boring 7
Soil Boring 10
Soil Boring 2
MW-7
MW-5
Treeline
Soil Boring 3
Area A-?
Area T-?
End of CRREL Survey Line
Monitoring Well//Boring
EM Anomalies:
0
50
100 ft
500 - mV
100 - 499 mV
0
10
20
30 m
50 - 99 mV
GPR Anomalies:
Anomalous Zone
Target and Depth (m)
Figure 13. EMI and GPR anomalies east of the CRREL baseline as compiled
from data recorded in June 1995. Interpreted depths to targets are in meters
below the existing ground surface. CRREL survey lines run from northwest
to southeast.
CONCLUSIONS
A-1 and A-2 both had raised surfaces, which indi-
cated that each was filled above the original
The 1994 investigations showed that the PRDA
ground surface.
contains four large areas within which geophysi-
GPR and EMI investigations in June 1995 show
cal methods clearly point to the presence of
that the 1994 excavations by OHM successfully
metallic objects and other buried debris. The vari-
removed all major metallic objects. The few scat-
ability in their intensity, depth, and location, and
tered, minor EMI anomalies that remained are
the clustering of these anomalies, suggested that
most likely attributable to the presence of small
both trenches (areas A-3 and A-4) and single or
near-surface metallic debris. The remaining, small
closely spaced excavations (areas A-2 and A-1)
GPR anomalies and suspicious zones not corre-
were used for burial. Anomalous horizons in
each area begin at a depth estimated at 1 to 1.5
lated with the EMI targets probably reflect the
m below the surface and extend to a depth of
complex geology. The fill material used subse-
over 4 m. A linear concentration of strong hyper-
quent to the 1994 excavations is easily delineated
bolic diffractions within area A-3 suggested a
with GPR because it contrasts markedly with the
trench of about 50 m in length containing
original ground surface.
stacked cylindrical objects. Excavation of the
Comparisons between the 1994 and 1995 GPR
A-3 area confirmed this interpretation. Prior to
records show that all major anomalies previously
13
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