Continuous Treatment of Low Levels of TNT and RDX in Range Soils Using Surface Liming

摘要

Significant quantities of residual energetics are deposited on surface soils at live-fire ranges. Most of these residues come from bulk composition left over following low-order detonations. Of particular concern is RDX, which is environmentally persistent and mobile, and can therefore lead to groundwater pollution. Base hydrolysis can be used to rapidly decompose TNT and RDX in aqueous solutions. Hydrolysis of TNT produces soluble and insoluble polymers, while hydrolysis of RDX releases simple inorganic ions. It is reasonable to expect that similar chemical reactions could be used to decontaminate explosives residues in situ on contaminated range soils. This project investigated surface application of agricultural lime to hydrolyze residual energetic materials (including TNT RDX, HMX, and 2,4-DNT) that had been deposited on shallow soils at a hand grenade training range. Laboratory experiments conducted using soil samples from the range indicated that lime could be used to destroy all of the TNT and most of the RDX. Results of the laboratory experiments were used to guide field trials at the range. Unfortunately, the heterogeneous distributions of residual TNT and RDX were so great that statistically significant results could not be demonstrated using samples collected from shallow surface soil. Lime applications are continuing at this site. Samples from below the depth of active soil deposition and mixing (cratering) should be collected in the future using remote-controlled equipment. Such samples should reveal whether the lime treatment reduces the downward migration of energetics residuals from the surface.