I'm interested in electrical resistivity, complex resistivity, electromagnetic induction, and ground penetrating radar (GPR) applications for subsurface characterization and monitoring. Specifically, as these pertain to our understanding of cold region subsurface processes and target detection. I am a research geophysicist at the U.S. Army Cold Regions Research
Discrete deep targets are a significant challenge for most surface-based geophysical techniques, ... more Discrete deep targets are a significant challenge for most surface-based geophysical techniques, even when considering high property contrasts. In general, surface-based geophysical methods lose lateral and vertical resolution with depth as a result of the limited acquisition geometry and increased signal attenuation. The former can be overcome through use of cross-borehole methods, but lateral localization is still needed for optimal borehole placement. As such, a relatively small, deep void located near the maximum depth of investigation (DOI) is very unlikely to be detected. Yet, secondary features associated with these voids can be exploited for enhanced detection performance. When voids are located below the groundwater table, a significant amount of dewatering and pumping is required to make them a functional passageway. This dewatering not only removes water from the void space but also the surrounding formation, resulting in a much larger, if more diffuse, secondary target: ...
Thin wires are a critical component of many types of improvised explosive devices. Short wires wi... more Thin wires are a critical component of many types of improvised explosive devices. Short wires with lengths on the order of 30 cm to a few meters are difficult to detect using electromagnetic induction metal detectors due to the induction currents having only a small cross-section of the wire to circulate on. Longer wires on the order of tens of meters up to a kilometer are often buried at depths which preclude induction detection. We demonstrate short wire detection and identification through acquiring the electromagnetic induction response at frequencies above the traditional EMI range. In addition, long wire detection and identification is shown through electric field coupling between excitation coils and the long wire itself. We present the relevant physics of detecting both types of wires and experimental and modeling results demonstrating the utility of this high-frequency EMI regime. We present a high-frequency electromagnetic induction instrument utilizing frequencies up to ...
A B S T R A C T A validation experiment, carried out in a scaled field setting, was attempted for... more A B S T R A C T A validation experiment, carried out in a scaled field setting, was attempted for the long electrode electrical resistivity tomography method in order to demonstrate the performance of the technique in imaging a simple buried target. The experiment was an approximately 1/17 scale mock-up of a region encompassing a buried nuclear waste tank on the Hanford site. The target of focus was constructed by manually forming a simulated plume within the vadose zone using a tank waste simulant. The long electrode results were compared to results from conventional point electrodes on the surface and buried within the survey domain. Using a pole-pole array, both point and long electrode imaging techniques identified the lateral extents of the pre-formed plume with reasonable fidelity but the long electrode method was handicapped in reconstructing vertical boundaries. The pole-dipole and dipole-dipole arrays were also tested with the long electrode method and were shown to have th...
High-frequency electromagnetic induction (HFEMI) extends the established EMI frequency range abov... more High-frequency electromagnetic induction (HFEMI) extends the established EMI frequency range above 100 kHz to perhaps 20 MHz. In this higher frequency range, less-conductive targets display heretofore unseen responses in their inphase and quadrature components. Improvised explosive device constituent parts, such as carbon rods, small pressure plates, conductivity voids, low metal content mines, and short wires respond to HFEMI but not to traditional EMI. Results from recent testing over mock-ups of less conductive IEDs or their components show distinctive HFEMI responses, suggesting that this new sensing realm could augment the detection and discrimination capability of established EMI technology. The electrical conductivity of soil may contribute, in effect, to the imaginary part of the permittivity of soil and may then, in turn, generate perceptible responses in traditional EMI. In HFEMI, both the real and complete imaginary parts of soil permittivity produce notable effects. Purs...
Unplanned releases of radioactive and hazardous wastes have occurred at the 241-SX Tank Farm on t... more Unplanned releases of radioactive and hazardous wastes have occurred at the 241-SX Tank Farm on the U.S. Department of Energy Hanford Site in southeast Washington State. Interim and long-term mitigation efforts are currently under evaluation for 241-SX Tank Farm. Two contiguous interim surface barriers have been designed for deployment at 241-SX Tank Farm to reduce future moisture infiltration; however, construction of the surface barriers has been deferred to allow testing of alternative technologies for soil moisture reduction and possibly contaminant source term reduction. Previous tests performed by other organizations at the Hanford Site have demonstrated that: vadose zone desiccation using large diameter (greater than 4 inch) boreholes is feasible; under certain circumstances, mobile contaminants may be removed in addition to water vapor; and small diameter (approximately 2 inch) boreholes (such as those placed by the direct push hydraulic hammer) can be used to perform vapor ...
ABSTRACT The increased use of biofuels (e.g. ethanol) as an alternative to, and additive in, petr... more ABSTRACT The increased use of biofuels (e.g. ethanol) as an alternative to, and additive in, petroleum-based fuels likely will result in the same types of accidental releases and exposure currently associated with the transport and storage of petroleum products. Within the last decade a large number of studies have focused on the geophysical detection and monitoring of petroleum-based fuel releases, and subsequent biodegradation and remediation activity. Ethanol has unique properties; it is miscible in water, preferentially biodegraded, and manifests cosolvency when released in the presence of existing contamination. New tools are needed to rapidly identify and delineate a potential release to the subsurface. This study examines the feasibility of using ground penetrating radar (GPR) as a tool to image the migration of an ethanol release within an Ottawa sand matrix. A tank scale model of a closed hydrologic system was prepared. An automated gantry measurement apparatus allowed for both zero offset, and coincident reflection measurements with a multi-channel 800 MHz GPR system on multiple horizontal planes. Measurements were acquired in the vadose and saturated zones to image the injection and migration of the ethanol release. Preliminary results suggest a measureable contrast within the time series GPR data at the location of the injected ethanol release and subsequent migration.
The recent 3D electrical resistivity characterization at 241-U Tank Farm represents the first ful... more The recent 3D electrical resistivity characterization at 241-U Tank Farm represents the first full-farm true 3D environmental resistivity deployment in the world. Technological and manufacturing developments by the vendor resulted in a data acquisition system that far surpasses the ability of the previous off-the-shelf systems. The new data acquisition system allows for 180 channels, which enables the full-farm 3D acquisition without the inaccuracies associated with combining multiple datasets. This ultimately leads to a more accurate model of the subsurface and a better understanding of moisture and contaminant distribution within the vadose zone. Additionally, advancements in electrical noise filters and increased output power resulted in better quality data than previously acquired at the site, reducing the amount of poor quality data by more than half. Ultimately, the new, improved system increased the speed of data acquisition and quality of the final results. The system allowe...
The Signal Physics Representation in Uncertain and Complex Environments (SPRUCE) work unit, part ... more The Signal Physics Representation in Uncertain and Complex Environments (SPRUCE) work unit, part of the U.S. Army Engineer Research and Development Center (ERDC) Army Terrestrial-Environmental Modeling and Intelligence System (ARTEMIS) work package, focused on the creation of a suite of three-dimensional (3D) signal and sensor performance modeling capabilities that realistically capture propagation physics in urban, mountainous, forested, and other complex terrain environments. This report describes many of the developed technical capabilities. Particular highlights are (1) creation of a Java environmental data abstraction layer for 3D representation of the atmosphere and inhomogeneous terrain that ingests data from many common weather forecast models and terrain data formats, (2) extensions to the Environmental Awareness for Sensor and Emitter Employment (EASEE) software to enable 3D signal propagation modeling, (3) modeling of transmitter and receiver directivity functions in 3D i...
Operations associated with nuclear weapons development resulted in subsurface heavy metal and rad... more Operations associated with nuclear weapons development resulted in subsurface heavy metal and radionuclide contamination at many sites within the former US nuclear weapons development complex. Of these, the Hanford Site, which housed research and plutonium production facilities, faces some of the most complex and challenging subsurface remediation problems. In this chapter, we briefly discuss the Hanford Site operations and waste management practices that resulted in vadose zone and groundwater radionuclide contamination. We then present several examples of how near-surface geophysical methods are being used to inform site operators of the properties and processes governing contaminant distribution and behavior.
Discrete deep targets are a significant challenge for most surface-based geophysical techniques, ... more Discrete deep targets are a significant challenge for most surface-based geophysical techniques, even when considering high property contrasts. In general, surface-based geophysical methods lose lateral and vertical resolution with depth as a result of the limited acquisition geometry and increased signal attenuation. The former can be overcome through use of cross-borehole methods, but lateral localization is still needed for optimal borehole placement. As such, a relatively small, deep void located near the maximum depth of investigation (DOI) is very unlikely to be detected. Yet, secondary features associated with these voids can be exploited for enhanced detection performance. When voids are located below the groundwater table, a significant amount of dewatering and pumping is required to make them a functional passageway. This dewatering not only removes water from the void space but also the surrounding formation, resulting in a much larger, if more diffuse, secondary target: ...
Thin wires are a critical component of many types of improvised explosive devices. Short wires wi... more Thin wires are a critical component of many types of improvised explosive devices. Short wires with lengths on the order of 30 cm to a few meters are difficult to detect using electromagnetic induction metal detectors due to the induction currents having only a small cross-section of the wire to circulate on. Longer wires on the order of tens of meters up to a kilometer are often buried at depths which preclude induction detection. We demonstrate short wire detection and identification through acquiring the electromagnetic induction response at frequencies above the traditional EMI range. In addition, long wire detection and identification is shown through electric field coupling between excitation coils and the long wire itself. We present the relevant physics of detecting both types of wires and experimental and modeling results demonstrating the utility of this high-frequency EMI regime. We present a high-frequency electromagnetic induction instrument utilizing frequencies up to ...
A B S T R A C T A validation experiment, carried out in a scaled field setting, was attempted for... more A B S T R A C T A validation experiment, carried out in a scaled field setting, was attempted for the long electrode electrical resistivity tomography method in order to demonstrate the performance of the technique in imaging a simple buried target. The experiment was an approximately 1/17 scale mock-up of a region encompassing a buried nuclear waste tank on the Hanford site. The target of focus was constructed by manually forming a simulated plume within the vadose zone using a tank waste simulant. The long electrode results were compared to results from conventional point electrodes on the surface and buried within the survey domain. Using a pole-pole array, both point and long electrode imaging techniques identified the lateral extents of the pre-formed plume with reasonable fidelity but the long electrode method was handicapped in reconstructing vertical boundaries. The pole-dipole and dipole-dipole arrays were also tested with the long electrode method and were shown to have th...
High-frequency electromagnetic induction (HFEMI) extends the established EMI frequency range abov... more High-frequency electromagnetic induction (HFEMI) extends the established EMI frequency range above 100 kHz to perhaps 20 MHz. In this higher frequency range, less-conductive targets display heretofore unseen responses in their inphase and quadrature components. Improvised explosive device constituent parts, such as carbon rods, small pressure plates, conductivity voids, low metal content mines, and short wires respond to HFEMI but not to traditional EMI. Results from recent testing over mock-ups of less conductive IEDs or their components show distinctive HFEMI responses, suggesting that this new sensing realm could augment the detection and discrimination capability of established EMI technology. The electrical conductivity of soil may contribute, in effect, to the imaginary part of the permittivity of soil and may then, in turn, generate perceptible responses in traditional EMI. In HFEMI, both the real and complete imaginary parts of soil permittivity produce notable effects. Purs...
Unplanned releases of radioactive and hazardous wastes have occurred at the 241-SX Tank Farm on t... more Unplanned releases of radioactive and hazardous wastes have occurred at the 241-SX Tank Farm on the U.S. Department of Energy Hanford Site in southeast Washington State. Interim and long-term mitigation efforts are currently under evaluation for 241-SX Tank Farm. Two contiguous interim surface barriers have been designed for deployment at 241-SX Tank Farm to reduce future moisture infiltration; however, construction of the surface barriers has been deferred to allow testing of alternative technologies for soil moisture reduction and possibly contaminant source term reduction. Previous tests performed by other organizations at the Hanford Site have demonstrated that: vadose zone desiccation using large diameter (greater than 4 inch) boreholes is feasible; under certain circumstances, mobile contaminants may be removed in addition to water vapor; and small diameter (approximately 2 inch) boreholes (such as those placed by the direct push hydraulic hammer) can be used to perform vapor ...
ABSTRACT The increased use of biofuels (e.g. ethanol) as an alternative to, and additive in, petr... more ABSTRACT The increased use of biofuels (e.g. ethanol) as an alternative to, and additive in, petroleum-based fuels likely will result in the same types of accidental releases and exposure currently associated with the transport and storage of petroleum products. Within the last decade a large number of studies have focused on the geophysical detection and monitoring of petroleum-based fuel releases, and subsequent biodegradation and remediation activity. Ethanol has unique properties; it is miscible in water, preferentially biodegraded, and manifests cosolvency when released in the presence of existing contamination. New tools are needed to rapidly identify and delineate a potential release to the subsurface. This study examines the feasibility of using ground penetrating radar (GPR) as a tool to image the migration of an ethanol release within an Ottawa sand matrix. A tank scale model of a closed hydrologic system was prepared. An automated gantry measurement apparatus allowed for both zero offset, and coincident reflection measurements with a multi-channel 800 MHz GPR system on multiple horizontal planes. Measurements were acquired in the vadose and saturated zones to image the injection and migration of the ethanol release. Preliminary results suggest a measureable contrast within the time series GPR data at the location of the injected ethanol release and subsequent migration.
The recent 3D electrical resistivity characterization at 241-U Tank Farm represents the first ful... more The recent 3D electrical resistivity characterization at 241-U Tank Farm represents the first full-farm true 3D environmental resistivity deployment in the world. Technological and manufacturing developments by the vendor resulted in a data acquisition system that far surpasses the ability of the previous off-the-shelf systems. The new data acquisition system allows for 180 channels, which enables the full-farm 3D acquisition without the inaccuracies associated with combining multiple datasets. This ultimately leads to a more accurate model of the subsurface and a better understanding of moisture and contaminant distribution within the vadose zone. Additionally, advancements in electrical noise filters and increased output power resulted in better quality data than previously acquired at the site, reducing the amount of poor quality data by more than half. Ultimately, the new, improved system increased the speed of data acquisition and quality of the final results. The system allowe...
The Signal Physics Representation in Uncertain and Complex Environments (SPRUCE) work unit, part ... more The Signal Physics Representation in Uncertain and Complex Environments (SPRUCE) work unit, part of the U.S. Army Engineer Research and Development Center (ERDC) Army Terrestrial-Environmental Modeling and Intelligence System (ARTEMIS) work package, focused on the creation of a suite of three-dimensional (3D) signal and sensor performance modeling capabilities that realistically capture propagation physics in urban, mountainous, forested, and other complex terrain environments. This report describes many of the developed technical capabilities. Particular highlights are (1) creation of a Java environmental data abstraction layer for 3D representation of the atmosphere and inhomogeneous terrain that ingests data from many common weather forecast models and terrain data formats, (2) extensions to the Environmental Awareness for Sensor and Emitter Employment (EASEE) software to enable 3D signal propagation modeling, (3) modeling of transmitter and receiver directivity functions in 3D i...
Operations associated with nuclear weapons development resulted in subsurface heavy metal and rad... more Operations associated with nuclear weapons development resulted in subsurface heavy metal and radionuclide contamination at many sites within the former US nuclear weapons development complex. Of these, the Hanford Site, which housed research and plutonium production facilities, faces some of the most complex and challenging subsurface remediation problems. In this chapter, we briefly discuss the Hanford Site operations and waste management practices that resulted in vadose zone and groundwater radionuclide contamination. We then present several examples of how near-surface geophysical methods are being used to inform site operators of the properties and processes governing contaminant distribution and behavior.
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Papers by Danney Glaser