Distribution and fate of energetics on DoD test and training ranges : interim report 5

The DoD has a mandate of environmental stewardship as well as military readiness.Therefore, the concern that training with live munitions potentially generates undesirable residual constituents is of interest.The objective of this study is to develop techniques for assessing the potential for environmental contamination from energetic materials on testing and training ranges.The project defines the physical and chemical properties, concentrations, and distribution of residues in soils, and the potential for transport of these residues to groundwater.Surface soils associated with impact craters, targets areas, and firing points were characterized on 18 military installations in the United States and Canada.Residues from high-order, low-order, unconfined charge, and blow-in-place detonations were collected on witness plates, snow, and/or tarps for constituent analyses.Results of these analyses were used to characterize residue composition and spatial distribution in relationship to the types of training activities conducted.Results also contributed to development of surface soil sampling strategies for live-fire ranges.Transport parameters of contaminants of potential concern for which data are lacking were determined by leveraging this project with other funding sources.The characteristics of constituent residues on training ranges, both chemical composition and aerial distribution, vary with the type of range activity and the specific munitions fired.Residues tend to be localized in highly distributed point sources in the vicinity of targets and fixed firing positions.Characterizing these sites requires careful consideration of soil sampling strategies based on site activities and will typically include multi-increment composite sampling.Special care must be taken in laboratory subsampling since residues occur as solid particles of various sizes that are highly heterogeneously dispersed in the soil.For the types of ranges studied, e.g., heavy artillery and hand grenade ranges, RDX is a significant contaminant of concern.TNT, which is typically restricted to surface soil, poses less threat to groundwater than RDX.At firing points, propellant residues can be significant.High-order detonations, which constitute most of the explosions executed during training, generate undetectable to barely detectable, diffuse surface residuals; however, low-order detonations, the incidences of which are much lower than high-order detonations and which tend to be munitions-specific, are a potentially significant source of residues.Another issue with potential to generate significant residues is clearance of unexploded ordnance by blowing in place.Rendering safe does not always result in complete consumption of explosive charge.Therefore, care must be exercised to achieve complete detonations with secondary changes that do not contribute munitions constituents, especially RDX, to the soil.Results of fate and transport studies indicate that initial release of energetics from compositions, such as Composition B, into soils tends to be locally very high, approaching temperature-dependent aqueous phase saturation, even though the compositions dissolve more slowly than the solubilities of the individual components would suggest.Furthermore, soil adsorption from solution phase, which is governed to some extent by soil properties, will not significantly limit transport.Therefore, RDX is readily transportable to groundwater.TNT transforms readily to mono-amino products, the transport of which is limited by covalent bonding of these transformation products to soils components.Results of this study provide a technical basis for development of range-specific soil characterization approaches.Results also provide process descriptors for fate and transport of constituent residues and for assessing the exposure component of environmental risk assessments.The relationships emerging between various training activities and constituent residues provide a sound scientific basis for development of management practices for sustainment of training range activities while maintaining environmental stewardship.

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