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Cold Regions Research and Engineering Laboratory UXO Detection at Jefferson Proving Ground
Using Ground-Penetrating Radar
Steven A. Arcone, Kevin ONeill, Allan J. Delaney,
April 2000
and Paul V. Sellmann
Approved for public release; distribution is unlimited.
Cold Regions Research
and Engineering Laboratory
ERDC/CRREL TR-00-5
ERDC/CRREL TR-00-5
US Army Corps
of Engineers
�
Engineer Research and
Development Center Abstract: Ground-penetrating radar (GPR) was used
to detect UXO and nonordnance on the 40-acre site (lot
54) of Jefferson Proving Ground, Indiana. The UXO are
buried about 1 m deep in a clayey silt for which the soil
water content ranged from moist near the surface to
near saturation at about 1 m. A 16-bit radar was used to
profile along previously established lines and transects
over emplaced artificial targets. Data were recorded at
4864 traces/s with minimal towing speeds during both
dry and rainy weather. Target responses at both 300
(time range of 50 ns) and 600 MHz (30 ns) ranged from
discrete diffractions to short reflection segments. Soil
loss greatly attenuated diffraction hyperbolas. Theoret-
ical analyses of these hyperbolas give an average soil
dielectric constant of 10 at both 300 and 600 MHz. The
phase polarity of many of the reflected and diffracted
wavelets indicate targets with wave impedances higher
than that of the soil. It is therefore assumed that these
targets are metallic and the responses of some, whose
locations correlate with the position of UXO on burial
maps, are shown in detail. Theoretical modeling of wave-
let propagation for this soil confirms the high rate of at-
tenuation (4766 dB/m round-trip), the maintenance of
waveform, a shift in wavelet local frequency, and re-
sponse to a typical UXO. It is concluded that GPR is
effective for finding targets in this type of soil to no more
than 2-m depth. It is recommended that future surveys
utilize high trace acquisition rates to capture the full tar-
get responses, and a prowed, heavy dielectric antenna
sled to improve antenna-to-ground coupling and to de-
flect surface obstacles such as vegetation. Broadband,
three-dimensional numerical modeling of scattering from
UXO-shaped targets in soil, with diverse orientations of
antenna and target relative to one another, suggests
that target length and diameter may be inferred from
resonance patterns in backscattered signals. The sim-
ulations also reveal some ways in which oblique target/
antenna orientations along a transect may affect
frequency-dependent response patterns, providing clues
as to target shape as well as positional ambiguities.
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COVER: Commercial antenna transducer units that
produced the 300- (left) and 600-MHz wavelets. The
plastic tubs improved ground contact. Technical Report
ERDC/CRREL TR-00-5
Prepared for
ARMY ENVIRONMENTAL CENTER AND OFFICE OF THE CHIEF OF ENGINEERS
Approved for public release; distribution is unlimited.
UXO Detection at Jefferson Proving Ground
Using Ground-Penetrating Radar
Steven A. Arcone, Kevin ONeill, Allan J. Delaney,
April 2000
and Paul V. Sellmann
US Army Corps
of Engineers
�
Cold Regions Research &
Engineering Laboratory PREFACE
This report was prepared by Dr. Steven A. Arcone, Research Geophysicist, Snow and
Ice Division; Dr. Kevin ONeill, Research Civil Engineer, Applied Research Division; Allan
J. Delaney, Physical Sciences Technician, Snow and Ice Division; and Paul V. Sellman,
Geologist, Civil Engineering Research Division, Research and Engineering Directorate,
U.S. Army Cold Regions Research and Engineering Laboratory (CRREL), Engineer Re-
search and Development Center (ERDC), Hanover, New Hampshire.
This work was jointly sponsored by the U.S. Army Environmental Center (AEC), Aber-
deen Proving Ground, Maryland, under MIPR Number 3767, 15 April 1997, George
Robitaille, Program Manager, and by the ERDC Environmental Quality Technology (EQT)
Program, Work Unit Innovative Geophysical Technologies for Enhanced Buried UXO Dis-
crimination (AF25, 6.2), Dr. John Cullinane, Program Manager.
The authors thank Dr. Dwain Butler, Dr. Janet Simms, and Jose Llopis of Geotechnical
Laboratory, ERDC, Vicksburg, Mississippi, for supplying necessary technical information
and for helping to coordinate field activities, and thank the Thayer School of Engineering
Numerical Methods Laboratory, particularly Dr. S.A. Haider, for providing technical assis-
tance.
This publication reflects the personal views of the authors and does not suggest or reflect
the policy, practices, programs, or doctrine of the U.S. Army or Government of the United
States. The contents of this report are not to be used for advertising or promotional pur-
poses. Citation of brand names does not constitute an official endorsement or approval of
the use of such commercial products.
ii CONTENTS
Preface .............................................................................................................................
ii
Introduction .....................................................................................................................
1
Site description ................................................................................................................
1
Soils .................................................................................................................................
2
Dielectric theory ..............................................................................................................
3
Equipment and methods ..................................................................................................
3
Radar system ...........................................................................................................
3
Field profiling ..........................................................................................................
4
Post-processing and display of data ........................................................................
5
Profile interpretation ................................................................................................
5
Results and discussion .....................................................................................................
5
Control studies .........................................................................................................
5
Grid survey: 300 MHz .............................................................................................
8
Grid survey: 600 MHz ............................................................................................. 12
Distribution of � ..................................................................................................... 12
Theoretical discussion ..................................................................................................... 13
Modeling .......................................................................................................................... 15
Incident field and polarization parameters ...................................................................... 22
Modeling results .............................................................................................................. 23
Conclusions and recommendations ................................................................................. 28
Literature cited ................................................................................................................. 30
Abstract ............................................................................................................................ 32
ILLUSTRATIONS
Figure
1. Location of the 40-acre site at Jefferson Proving Ground .......................................
2
2. Typical form of a radiated GPR wavelet .................................................................
4
3. Distributions at the 40-acre site with radar profile transe