Contamination of military training grounds during training activities with legacy and newly developed munitions and potential off-site transport is a concern from both an environmental and military readiness standpoint. To quantify the potential for high explosives (HE) contamination and the subsequent risk for off-site migration, the different pathways that contribute to the transport and fate of energetics in the environment need to be identified and their relative contributions characterized. While the deposition, photo-transformation, and transport through soils of energetic compounds is being studied, there are knowledge gaps regarding their transport in surface water, particularly overland flow. Therefore, one objective of this project is to examine the surface transport of munitions formulations in solution and as particles, including examination of all processes that could influence their fate, such as sorption, photo-transformation, biotransformation, biodegradation, dissolution, and sediment transport. A second objective is to combine this new information with prior studies to create a complete picture of munitions fate that can then be used to determine natural attenuation, risk of contamination, and the need for any remedial measures.

To achieve these goals, a systematic set of research activities will be utilized, including organization and integration of existing knowledge, laboratory studies that close knowledge gaps exposed by the data analysis (specifically the transport of explosives as particles, dissolved in overland flow, and adsorbed to suspended and immobile sediment), and development of an integrated model and computational environment that would predict the fate of HEs for a particular location. The approach includes:

• laboratory batch and flume studies to characterize the interaction of dissolved munitions constituents with soil and suspended sediment in overland flow;
• laboratory flume studies that determine the effect of flow and particle characteristics on the transport of HE particulates, using model plastic and munitions particles;
• flume studies that examine surface amendments that decrease overland flow and erosion and therefore potentially minimize overland transport of energetics;
• synthesis of existing and newly obtained knowledge to formulate the relevant mechanisms and develop a conceptual framework for munitions transport and fate on military ranges;
• quantification of the contribution of each transport pathway for different runoff and infiltration scenarios under a range of conditions representative of different training sites;
• development of an integrated model that uses existing hydrologic and transport modules that would allow users to estimate potential for munitions contamination using their site parameters; and
• testing the performance of the model at a contaminated field site.

This work will synthesize the wealth of existing and new information about the fate of energetic compounds into a comprehensive conceptual framework that will allow determination of the relevant transport and attenuation mechanisms for a particular site. This capability will improve the accuracy of risk assessments for characterizing the potential of surface water and groundwater contamination. It will also enhance decision-making regarding mitigation measures required to minimize off-site contamination by energetic compounds. Ultimately, the outcomes and products of this project will improve the capability of the Department of Defense for cost-effective management of munitions testing and training ranges. (Anticipated Project Completion - 2023)