NE
Distance (m)
SW
0
12
24
36
1994 Fill
Old Fill?
1
2
Numerous Targets
Trench with
Define a Lawyer?
Metallic Targets?
3
Rocks or Non-
metallic Targets?
4
EM > 50 mV
5
0
20
40
60
80
b. Recorded along the axis of a
suspected trench in area T-1.
Figure 12 (cont'd). 400-MHz GPR profile and interpretative depth sections.
concrete, etc.). Alternatively, the nonmetallic
lies exceed 50 mV is shown in the schematic, and
GPR anomalies may result from the complex
GPR diffractions within this zone are thought to
geology, in which case the metallic refuse is
originate from metal objects.
indeed confined to narrow trenches.
Nearly all of the 400-MHz GPR profile data
The areal extent of significant GPR anomalies
recorded in area T-1 show evidence of a second,
is presented in Figure 13. Also plotted on this
deeper subsurface horizon. In many instances
figure are estimated depths to specific targets as
this reflection can be followed to intercept with
determined from the high-amplitude hyperbolic
the base of the 1994 fill section. This horizon
diffractions on the GPR profiles. These targets
may represent a former ground surface that was
represent significant items, particularly the ones
excavated for burial of refuse and then sub-
that lie within the limits of the strong EMI
sequently filled (labeled on Fig. 12 as "old fill").
anomalies. All targets are interpreted to be less
The EMI anomalies typically fall within the
than 2.6 m deep.
areal limits of the deeper, older horizon. This
Some additional isolated EMI anomalies exist
suggests that refuse was buried in wide, tapered
at the site, most of which are minor (less than 100
depressions that might allow easy access. Non-
mV) and probably result from small pieces of
metallic GPR anomalies adjacent to the promi-
metal near the surface. At the time of this writing,
nent induction (metallic) anomalies might rep-
none of the anomalous areas east of the baseline
resent miscellaneous fill material with little
have been excavated.
metallic content (crates, building materials,
12
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