Les Beard - Academia.edu (original) (raw)

Papers by Les Beard

9th EAGE/EEGS Meeting, 2003

Symposium on the Application of Geophysics to Engineering and Environmental Problems 1996, 1996

Data from two airborne geophysical surveys of the Department of Energy's Oak Ridge Reservation (O... more Data from two airborne geophysical surveys of the Department of Energy's Oak Ridge Reservation (ORR) were extremely valuable in deciding whether a 1000-acre (400 hectare) parcel of the ORR should be released to the City of Oak Ridge for industrial development. Our findings, based on electromagnetic and magnetic data, were incorporated in the federally mandated Environmental Assessment Statement (EAS), and in general supported claims that this land was never used as a hazardous waste disposal site. We estimated the amount of iron required to produce each anomaly using a simple dipole model. All anomalies with equivalent sources greater than approximately IO00 kg of iron were checked in the field, and the source of all but one identified as either a bridge, reinforced concrete debris, or a similarly benign object. Additionally, some smaller anomalies (equivalent sources of roughly 500 kg) have been checked: thus far, these also have innocuous sources. Airborne video proved invaluable in identifying logging equipment as the source of some of these anomalies. Geologic noise may account for some of the remaining anomalies. Naturally occurring accumulations of magnetic minerals in the soil on the ORR have been shown to produce anomalies which, at a sensor height of 30 m, are comparable to the anomaly produced by about 500 kg of iron. By comparison, the electronic noise of the magnetic gradiometer, 0.01-0.02 nT/m. is equivalent to only about 50-100 kg of iron at a 30 m sensor height. The electromagnetic data, combined with field mapping of karst structures, provided evidence of a northeast-southwest striking conduit spanning the parcel. The possible existence of a karst conduit led the EAS authors to conclude that this is a "sensitive hydrologic setting." We conclude that aerial geophysics is an extremely cost-effective, and efficient technique for screening large tracts of land for environmental characterization.

Symposium on the Application of Geophysics to Engineering and Environmental Problems 2003, 2003

Airborne magnetic surveys can cover hundreds of hectares with very close sensor spacing in a sing... more Airborne magnetic surveys can cover hundreds of hectares with very close sensor spacing in a single day. Over unexploded ordnance (UXO) contaminated areas this can translate to thousands of anomalies. Any tool that permits one to rapidly classify anomalies as probable non-UXO and probable UXO is useful. Several geophysical characteristics can be exploited to sort the anomalies, among them signal amplitudes, estimated source depth, and indicators of magnetic remanence. We have developed a grid-based technique that combines information from the total field residual anomaly, the analytic signal, and sensor height to estimate source depth and remanent magnetization. We can then use these and other indicators in statistical schemes to predict whether the source of an anomaly is or is not ordnance.

SEG Technical Program Expanded Abstracts 2006, 2006

SEG Technical Program Expanded Abstracts 1996, 1996

Symposium on the Application of Geophysics to Engineering and Environmental Problems 1995, 1995

In 1994, a high resolution helicopter geophysid survey was conducted over portions of the Oak Rid... more In 1994, a high resolution helicopter geophysid survey was conducted over portions of the Oak Ridge Reservation, Tennessee. The 1800 line kilometer survey included multi-frequency electromagnetic and magnetic sensors. The areas covered by the high resolution portion of the survey were selected on the basis of their importance to the environmental restoration effort and on data obtained from the reconnaissance phase of the airborne survey in which electromagnetic, magnetic, and radiometric data were collected over the entire Oak Ridge Reservation in 1992-93. The high resolution phase had lower sensor heights, more and higher EM frequencies, and tighter line spacings than did the reconnaissance survey. When flying over exceptionally clear areas, the high resolution bird came within a few meters of the ground surface. Unfortunately, even sparse trees and power or phone lines could prevent the bird from being towed safely at low altitudes, and over such areas it was more usual for it to be flown at about the same altitude as the bird in the reconnaissance survey, about 30m. Even so, the magnetometers used in the high resolution phase were 20m closer to the ground than in the reconnaissance phase because they were mounted on the tail of the bird rather than on the tow cable above the bird. The EM frequencies used in the high resolution survey ranged from 74ooHz to 67OOOHz. Only the horizontal coplanar loop configuration was used in the high resolution flyovers Flight line spacings in the high resolution flyover ranged from 46m over large treecovered areas to about 1Om in cleared waste burial grounds. A comparison with ground conductivity and magnetic data from the WAG 11 area shows that the ground survey provides much more derail than the high resolution aerial data, however the aerial survey of WAG 11 detected the major anomalous areas-buried processing equipment, buried drums, and an area of scattered debris. Better resolution could have been obtained had the area been clear enough for the sensor to drop below treetop level. Geologic structures and contacts appear to be as accurately mapped using a coil frequency of 7400Hz. Apparent resistivity maps at the highest frequency-66000Hz-do not correspond well with bedrock geology, but may be correlated with soil variations and the presence of buried metal. * The submitted manuscript has been authored by a contractor of the US. Government under contract No. DE-AC05-840R21400. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes.

Symposium on the Application of Geophysics to Engineering and Environmental Problems 2002, 2002

On the basis of a successful prototype test, we have begun development of a new airborne electrom... more On the basis of a successful prototype test, we have begun development of a new airborne electromagnetic system for detection of unexploded ordnance. The design is based on an investigation of design parameters and a series of noise measurements. The noise tests were designed to determine optimal locations for transmitters and receivers and to characterize the relative noise contributions of the helicopter with and without its engine running, as well as to distinguish between noise that is helicopter-generated and that which is induced in the helicopter by the electromagnetic transmitter. Data were acquired with the second-generation prototype in December 2001, and completion of a production system is anticipated approximately one year later.

Symposium on the Application of Geophysics to Engineering and Environmental Problems 2010, 2010

In the fall of 2008, a low-altitude airborne geophysical survey was carried out at a military ins... more In the fall of 2008, a low-altitude airborne geophysical survey was carried out at a military installation in Australia, the primary goal of which was detection and mapping of infrastructure, buried wastes, and other buried and surface metallic objects within a 1738 hectare area. The primary survey system was the Battelle VG-16 vertical magnetic gradient system. Because the base is active, the time frame for conducting the survey was limited to a few weeks. The short time frame and the added expense of an additional system were factors against adding on an electromagnetic survey. However, the Australian Department of Defence suggested that there might be non-ferrous targets of significance that the magnetic system would not detect. Moreover, the base was located some tens of kilometers from a field of extinct volcanoes, presenting the possibility of magnetic geology in the form of mafic igneous units. Therefore, it was determined that an airborne transient electromagnetic system should be included in the project. The added electromagnetic system proved valuable, but not in the way that was expected. Concentrations of strong anomalies appeared in the magnetic data, the sources of which could be either buried debris or geological. The TEM-8 system was flown over some of the more dense concentrations of magnetic anomalies. In some of these areas the TEM data showed very few anomalies, indicating that either the VG-16 anomalies are associated with magnetic rock types, or that the metallic sources detected by the VG-16 system are too deeply buried to be detected with the TEM-8 system. A few carefully located excavations indicated that the sources of the magnetic anomaly concentrations without associated electromagnetic anomalies were localized concentrations of very magnetic iron-bearing rock.

Symposium on the Application of Geophysics to Engineering and Environmental Problems 2007, 2007

Site S-12 is one of several World War II era bombing targets found on the Pueblos of Laguna and I... more Site S-12 is one of several World War II era bombing targets found on the Pueblos of Laguna and Isleta in New Mexico. Magnetometry results from a low-altitude helicopter magnetometry survey at S-12 were inconclusive as to the extent and density of the ordnance debris field because underlying basalt flows created such a strong background signal. Subsequently, a team from Battelle and GDD Inc. carried out ground geophysical surveys to test the effectiveness of a geophysical instrument called Beep Mat. Beep Mat is mounted in a rugged sled and is designed to be towed over the ground or through snow. Originally developed for Canadian mineral prospecting, it has the ability to distinguish between conductive and non-conductive materials and between magnetic and non-magnetic materials. It is therefore a potentially useful instrument for UXO detection and discrimination. At Site S-12, a 100m x 50m grid was established in an area thought to be on the periphery of the bombing target. Geophysical data using EM-61, and Beep Mat were collected over the grid at one meter line spacing. Both the EM-61 and the Beep Mat data produced similar maps showing locations of scrap and UXO, but Beep Mat anomaly peaks were randomly offset about 2m from EM-61 anomaly peaks.

Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XV, 2010

Symposium on the Application of Geophysics to Engineering and Environmental Problems 2008, 2008

SEG Technical Program Expanded Abstracts 2007, 2007

Two new airborne vertical magnetic gradient arrays, which mount directly to a helicopter for oper... more Two new airborne vertical magnetic gradient arrays, which mount directly to a helicopter for operation at 1.5-5m altitude, have recently been tested at an unexploded ordnance (UXO) test site in Ohio. These arrays consist of 16 and 22 cesium vapor magnetometers respectively, configured as 8 and 11 vertical magnetic gradiometers. Results from the test demonstrate significant improvements in performance over previous total field systems.

SEG Technical Program Expanded Abstracts 2008, 2008

In January 2008, low-altitude (~1-3 meters above ground level) airborne geophysical surveys were ... more In January 2008, low-altitude (~1-3 meters above ground level) airborne geophysical surveys were carried out at the Marine Corps Air Ground Combat Center (MCAGCC), near Twentynine Palms, California. The primary goal of the surveys was to assess the viability of airborne magnetic or electromagnetic geophysical surveys at MCAGCC for detection and mapping of unexploded munitions. Due to high magnetic content in the rocks and soils at MCAGCC magnetic methods had been shown in the past to have limited usefulness. The background magnetic conditions made this site a good candidate for the use of a new 8channel Time-domain Electromagnetic system (TEM8) developed by Battelle. The first phase of the project was an assessment of the efficacy of TEM8 and vertical magnetic gradient (VG-22) technologies, based on results from surveys of two 8 hectare areas and a 2 hectare geophysical prove out (GPO) area. This demonstration showed that both VG-22 and TEM8 were useful at this site, but the combination of the two datasets is more effective than either dataset used singularly for target prioritization.

Stochastic Environmental Research and Risk Assessment, 2008

Page 1. ORIGINAL PAPER Multiscale structure of UXO site characterization: spatial estimation and ... more Page 1. ORIGINAL PAPER Multiscale structure of UXO site characterization: spatial estimation and uncertainty quantification G. Ostrouchov Æ WE Doll Æ LP Beard Æ MD Morris Æ DA Wolf Published online: 31 January 2008 Ó Springer-Verlag 2008 ...

Journal of Environmental & Engineering Geophysics, 2006

ABSTRACT

GEOPHYSICS, 2004

Field trials of a low‐flying time‐domain helicopter electromagnetic system designed for detection... more Field trials of a low‐flying time‐domain helicopter electromagnetic system designed for detection of unexploded ordnance have yielded positive and encouraging results. The system is able to detect ordnance as small as 60‐mm rounds at 1‐m sensor height. We examined several transmitter and receiver configurations. Small loop receivers gave superior signal‐to‐noise ratios in comparison to larger receiver loops at low heights. Base frequencies of 90 Hz and 270 Hz were less affected than other base frequencies by noise produced by proximity to the helicopter and by vibration of the support structure. For small ordnance, a two‐lobed, antisymmetric transmitter loop geometry produced a modest signal‐to‐noise enhancement compared with a large single rectangular loop, presumably because the antisymmetric transmitter produces smaller eddy currents in the helicopter body, thereby reducing this source of noise. In most cases, differencing of vertically offset receivers did not substantially impr...

GEOPHYSICS, 1998

Where the magnetic permeability of rock or soil exceeds that of free space, the effect on airborn... more Where the magnetic permeability of rock or soil exceeds that of free space, the effect on airborne electromagnetic systems is to produce a frequency‐independent shift in the in‐phase response of the system while altering the quadrature response only slightly. The magnitude of the in‐phase shift increases as (1) the relative magnetic permeability is increased, (2) the amount of magnetic material is increased, and (3) the airborne sensor gets nearer the earth’s surface. Over resistive, magnetic ground, the shift may be evinced by negative in‐phase measurements at low frequencies; but over more conductive ground, the same shift may go unnoticed because of the large positive in‐phase response. If the airborne sensor is flown at low levels, the magnitude of the shift may be large enough to affect automatic inversion routines that do not take this shift into account, producing inaccurate estimated resistivities, usually overestimates. However, layered‐earth inversion algorithms that incor...