Residues from Live Fire Detonations of 155-mm Howitzer Rounds

Abstract : We quantified the explosives residues deposited by live fire of military munitions to estimate the load of unreacted energetics to soils. This value is needed to estimate potential explosives migration to groundwater. We sampled the impact and firing point residues of seven Composition B filled and seven TNT filled 155-mm howitzer projectiles (one of the five most commonly used rounds in the U.S. arsenal, and live fire residues had not been collected for them). The tests were conducted on an ice- and snow-covered range, which allowed us to sample the residues on an explosives-free surface and to visually demarcate the extent of the residue plume. We used a sampling protocol where 100 snow sample increments of 0.01 m2 were taken from the entire area of the demarcated plume and combined into one sample. Three replicate samples were taken from within each plume. Samples were also taken outside the visible plume to ensure that sample demarcation was correct. These live-fire detonations were extremely clean. For the Composition B (Comp B) rounds, the mass of RDX and TNT deposited ranged from below detection to 1 mg and 190 mug, respectively, for an individual round. Only 10(-7) to 10(-5) % of the high explosives in the original 6.9-kg Comp B round was recovered. For the TNT-filled rounds, no TNT or TNT breakdown products were recovered. Our findings are consistent with other research: live-fire, high-order detonations deposit very little explosive compounds and are not likely to be a threat to groundwater.