Estimating Energetic Residue Loading on Military Artillery Ranges: Large Decision Units

Abstract : Sampling experiments were conducted at three artillery/mortar impact ranges at Fort Hood, Texas; 29 Palms, California; and Fort Carson, Colorado, and at a mortar firing point at Fort Carson. The objective of these investigations was to assess the use of multi-increment sampling as a means of estimating the concentrations and mass loading of energetic compounds in surface soils for decision units ranging in size from 100 to 10,000 m2. In some cases, chunks of pure explosives were observed on the surface within the areas being sampled. These chunks were presumably present due to the partial (low-order) detonation of some type of munition during past training exercises, or from blowing in place of unexploded ordnance. Characterization was conducted using 49- to 100-increment surface samples that were collected using a systematic sampling design where individual increments were collected at equally spaced distances across the area. This was accomplished by dividing the area of concern into 49 to 100 equally sized sub-areas and collecting an increment from each sub-area to build the sample. The mass of multi-increment samples collected generally ranged from 1 to 2 kilograms. Replicate samples were collected to assess the reproducibility, i.e., sampling error. Average concentration estimates for the studied areas were used to estimate the mass loading for the energetic substances that were detected. The energetic compounds detected were generally RDX, HMX, and TNT for impact areas where the residue deposition appeared to be mostly from Composition-B-filled rounds. Sometimes the environmental transformation products of TNT, namely 2ADNT, 4ADNT, and TNB, were also detected. For the firing point area, only NG and 2,4DNT were detected. Overall, this sampling strategy was adequate to characterize a decision unit as large as 10,000 m2 at a heavily used firing point. Compositional and