On-Site Analysis for High Concentrations of Explosives in Soil
Extraction Kinetics and Dilution Procedures
THOMAS F. JENKINS, PATRICIA W. SCHUMACHER, JANE G. MASON
AND PHILIP G. THORNE
INTRODUCTION
Background
For the greater part of this century, the U.S. Army has manufactured explosives and munitions
and demilitarized munitions at Army facilities throughout the United States. Disposal of wastes
generated in these manufacturing operations has contaminated some Army lands with residues of
explosives. For example, the Army utilized unlined evaporation/percolation lagoons for disposal
of wastewaters from manufacturing, demilitarization, and load, assemble, and pack operations.
After many years of operation, explosives tended to accumulate at the soil surface of these lagoons,
sometimes at concentrations in the percent range. Whether sampling for site characterization or
conducting remediation activities, these areas of very high explosives concentration are a major
concern relative to the potential for detonation.
Several years ago, the U.S. Army Toxic and Hazardous Materials Agency (now the U.S. Army
Environmental Center) sponsored a study to document the reactivity (propagation of a detonation)
hazard associated with high concentrations of secondary explosives in soil (Kristoff et al. 1987). A
series of tests was conducted to define the reactivity of explosives-contaminated soils to flame and
shock as a function of explosives composition. The results of this work indicated that soils contain-
ing concentrations of TNT (2,4,6-trinitrotoluene) and RDX (1,3,5-hexahydro-1,3,5-trinitrotriazine)
below 15% were not reactive to shock stimuli, and soil concentrations below 12% could not be
detonated by flame initiation. To provide a margin of safety, the U.S. Army Environmental Center
has established a level of 10% as the concentration of secondary explosives in soil at which a deton-
ation would not propagate. Any concentration above 10% would be considered an explosive opera-
tion and would require the approval of the Department of Defense Explosive Safety Board. Because
of the cost and specialized nature of these reactivity tests, it was recommended that compositional
analysis be used to identify potentially reactive soils (those above the 10% criteria). Because of the
explosive hazard involved, a simple, rapid method for on-site analysis is useful in order to allow
decisions to be made expeditiously or to screen samples prior to shipment to off-site laboratories.
Three approaches have been developed for rapid on-site analysis: colorimetric methods, immuno-
assays, and ion mobility spectrometry (Table 1). All of these methods rely on an initial step involv-
ing rapid extraction of the soil with an organic solvent. Acetone or methanol have been the solvents
of choice because of the large solubility of these compounds in these polar solvents, and their com-
patibility with on-site methods of determination. However, the applicability of these solvents to
extraction of soil samples with very high concentrations of nitroaromatics and nitramines has not
been evaluated.
Previous Page
