John H. Ballard

Overview of multimethod geophysical system development for enhanced near-surface target detection, discrimination, and characterization

Near-surface geophysical “targets” include unexploded ordnance (UXO), landmines, cavities (including tunnels and underground facilities), contaminant plumes, utilities (including underground storage tanks, pipelines, etc.), archaeological artifacts, graves, forensic evidence, structural foundation investigations for new and existing structures, and assessing the condition of engineered structures (e.g., bridges, dams, levees, roads, airfields, buildings). Application of near-surface geophysics to detect and characterize any of these “targets” is in the public interest, and many applications are clearly and directly related to public safety. While the detection of these targets in a geologic background can often be challenging, the discrimination of the desired target signatures or expressions from “false alarm” target signatures can be an even greater challenge. The discrimination challenge can be as simple as a “go/no-go” decision on the target, or the properties of the target may need to be further characterized after the decision. There is near unanimity among geophysicists (a rare thing) that multimethod, collocated complementary geophysical data enhance not only target detection but also the capability for discrimination and characterization. The U.S. Army Engineer Research and Development Center (ERDC) conducted a multiyear research and development effort that resulted in complementary, collocated simultaneous geophysical survey capabilities for near-surface targets.

Influences of U Sources and Forms on Its Bioaccumulation in Indian Mustard and Sunflower

Anthropogenic activities, such as ore mining and processing, nuclear power generation, and weapon tests, have generated uranium (U) contamination to soils and waters. The mobility and bioavailability of U are influenced by its sources, speciation, and plant species. Phytoremediation has emerged as an environmentally friendly, cost-effective green technology to remediate radioisotope- and metal-contaminated soils. The main objective of this study was to explore the feasibility using sunflower (Helianthus annuus) and Indian mustard (Brassica juncea) in cleaning up soils with UO2, UO3, and UO2(NO3)2. Uranium was found to be bioaccumulated in plant roots more than plant shoots. Uranium uptake by both plant species was significantly higher from the UO3- and uranyl-contaminated soils than from UO2-contaminated soils. UO3- and UO2(NO3)2-contaminated soils showed higher exchangeable, weak acid extractable, and labile U than the UO2-contaminated soils. After a growing season, three U forms decreased as redistribution/transformation of U resulted in U species with lower extractability. This study indicates the importance of U speciation in soil with regard to the potential use of sunflower and Indian mustard for phytoremediation of U-contaminated soils.

Development and characterization of small-scale washing systems for removal of depleted uranium oxides

Researchers from the Mississippi State University Institute for Clean Energy Technology (MSU-ICET) and the U.S. Army Engineer Research and Development Center (ERDC) have identified procedures and methodologies for identifying leaching solutions to assist in the removal of depleted uranium (DU) oxides from contaminated soils. They developed a benchscale leach system to optimize leaching procedures and methodologies. This study identified that a 2 molar (M) acetic-acid solution with a 15% (v/v) 0.3 M hydroxylamine hydrochloride solution could remove approximately 70% of the uranium in the soil sample. Pretreating the soil with 3 M hydrochloric acid improved leaching efficiency to approximately 90%. The MSU-ICET research team developed the preliminary design of a mobile leaching system based on the hydrochloric-acid pretreatment followed by 2 M acetic acid / 15% (v/v) 0.3 M hydroxylamine hydrochloride leaching method. The trailer heap leach system is designed to be used on-site, eliminating the need for additional transport of radioactive, contaminated soils. This will reduce the risk of radioactive exposure for personnel and will eliminate potentially serious transportation accidents. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR.

Portable Magnetic/Frequency Domain Electromagnetic Induction Sensor System Development

An unexploded ordnance (UXO) survey instrument that simultaneously collects total field magnetic data and frequency domain electromagnetic (FDEM) induction data was developed and tested for the detection and characterization of buried UXO. The system is comprised of an FDEM sensor operating at 9.8 kHz and a cesium vapor magnetometer. The system was initially tested in dynamic survey (detection) and static cued survey (characterization) modes at the Naval Research Laboratory Blossom Point UXO test facility in Maryland. During these tests, electromagnetic (EM) induced bias in the magnetic data was mitigated by physically offsetting the magnetometer from the EM transmitter coils. In the dynamic survey, the aggregate performance exceeded the detection rates for the individual component sensor technologies. The cued analysis tests showed that target features can be determined by using model-based analyses, and the location estimate errors provided by these analyses were consistently better than the dynamic survey results.