Soil, explosive contamination

USATHAMA) completed a trial burn of explosive, contaminated soil in a rotary kiln (Noland, 1984). Soil contaminated from red and pink water lagoons was successfully burned. A transportable rotary kiln yrstem was set up. The technology by Therm-All, Inc., had been used in industry for destruction of solid wastes. The normal screw feed system was not used, due to fear of a soil explosion during the extruded plug feed process. Therefore, the soil was placed in combustible buckets and individually fed by a ram into the incinerator. The feed rate was 300 to 400 Ib/hr and the operational temperature was 1200° to 1600°F in the kiln and 1600° to 2000°F in the secondary chamber. 

Noland, J. and W. Sisk. "Incineration of Explosives Contaminated Soils," In Management of Uncontrolled Hazardous Waste Sites Proceedings, Washington, D.C., 1984, pp. 203. 

Kitts CL, DP Cunningham, PJ Unkefer (1994) Isolation of three hexahydro-l,3,5-trinitro-l,3,5-triazine-degrading species of the family Enterobacteriaceae from nitramine explosive-contaminated soil. Appl Environ Microbiol 60 4608-4711. 

Jenkins, T. F. e.a., 1996, Assessment of Sampling Error Associated with Collection and Analysis of Soil Samples at Explosives-Contaminated Sites. U.S. Army Corps of Engineers, Cold Regions Research Engineering Laboratory, Special Report 96-15. 

T0112 Bioremediation of Explosives Contaminated Soil—General... 

One source estimated the cost of bioremediating explosives-contaminated soil to be 50 to 400 (1995 dollars) per cubic yard of soil treated. This estimate does not always include all indirect costs associated with treatment such as excavation, permits, and treatment of residuals. A U.S. Army study estimated that to treat less than 10,000 tons of contaminated soil, the cost would be 651 per ton for mechanically agitated composting, and 386 per ton for windrow composting (D17224H, p. 29). 

Treatment of explosives-contaminated soil using stage one of Waste Management, Inc. s, two-stage static soil process (TOSS) is approximately 110/yd. If stage two is necessary, the cost increases to 254/yd (D194676, pp. 36, 37). For more information on the TOSS process, please refer to the technology overview. 

Until very recently, explosives-contaminated soils have been remediated by incineration, a process whose high cost has stimulated the search for a more economical cleanup method (Roberts et al., 1993). Microbially mediated degradation of explosives is a promising technology. Many researchers have studied microbial consortia and various pure cultures for their ability to degrade TNT and other nitroaromatic compounds (for a review see Crawford, 1995), bringing about the development of bioremediation processes that can remove TNT and other explosives from contaminated soil and water (Funk etal., 1995 Williams a/., 1992). 

Craig, H. Sisk, W. (1994). The composting alternative to incineration of explosives contaminated soils. Tech Trends. EPA Publication 542-N-94-008. November 1994-... 

Spiker, J., Crawford, D. Crawford, R. (1992). Influence of 2,4,6-trinitrotoluene (TNT) concentration of the degradation of TNT in explosives-contaminated soils by the white-rot fungus Phanerochaete chrysosporium. Applied and Environmental Microbiology, 58, 3199-202. 

Williams, R. T. Marks, P. J. (1991). Optimization of Composting for Explosives Contaminated Soil. Final Report prepared for U.S. Army Toxic Hazardous Materials Agency. Report no. CETHA-TS-CR-91053. November 1991. 

D.F. Goerlitz L.M. Law, Gas Chromatographic Method for the Analysis of TNT and RDX Explosives Contaminating Water and Soil Core Material , US Department of Interior Geological Survey Open File Report 75-182 (May 1975) 44) Karl Trautzl, International... 

Tetryl may be released to the air, water, and soil when old stores of the explosive ate destroyed by exploding or burning. However, tetryl has not been measured in air during any of these activities. Tetryl that was manufactured or stored at military installations, like Army ammunition plants, may still be present in the soil and water at or around these sites. Tetryl is not likely to evaporate into air from water or soil surfaces. However, tetryl may be present in air associated with dust from these sites. Tetryl appears to break-down rapidly in some soils. Picric acid, is one of the break down products of tetryl in soil. Tetryl probably does not easily travel from soil to groundwater. Erosion of soil from contaminated sites may release tetryl to nearby surface water. Once it is in the water, tetryl may dissolve or associate with small particles of suspended solids, sediments, or organic debris. Some of these particles will settle to the bottom. Tetryl breaks down rapidly in sunlit rivers and lakes but much more slowly in groundwater. It is not known whether tetryl will build up in fish, plants, or land animals. See Chapters 4 and 5 for more information on tetryl in the environment. 

Table 7.2 shows how frequently various nitroaromaticss and nitramines occur at explosives-contaminated sites with which die U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) and the Missouri River Division (MRD) have been involved. TNT is the most common contaminant, occurring in approximately 80% of the soil samples found to be contaminated with explosives. Trinitrobenzene (TNB), which is a photochemical decomposition product of TNT, was found in between 40 and 50% of these soils. Dinitrobenzene (DNB), 2,4-dinitrotoluene (2,4-DNT), and 2,6-DNT, which are impurities in production-grade TNT, were found in less than 40% of the soils. Figure 7.2 shows the chemical structures of common explosive contaminants. 

Table 7.2 Nitroaromatics and Nitramines Detected by CRREL and MRD in Explosives-Contaminated Soils from Army Sites...

The most immediate and profound risk from explosives is that of potential reactivity. Explosives exist in soils and sediments as small crystals to large chunks. Applying the correct initiating source to one of these crystals will cause a detonation. The amount of damage caused is in direct proportion to the size of the crystal. The presence or absence of water has minimal effect on the reactivity of the soil. A two test protocol has been developed and tested to determine the relationship between explosives contaminated soil content and reactivity. The Zero Gap test and the Deflagration to Detonation Transition (DDT) indicate that soils with 12% or less total explosives concentration will not propagate a detonation or explode when heated under confinement. 

U.S. EPA Region 10, the Oregon Department of Environmental Quality (DEQ), and U.S. Army Environmental Center (AEC) have used these results for determining the characteristic hazardous waste status of explosives contaminated soil as a reactive waste under RCRA. The basis for the RCRA characteristic hazardous waste status is the assumed explosive reactivity of the soils if subjected to a strong initiating force or if heated under confinement (40 CFR 261.23). These results apply to explosives such as TNT, HMX, DNT, TNB, and DNB, and do not apply to initiating compounds, such as lead azide, lead styphenate, or mercury fulminate. 

A baseline risk assessment is conducted to assess the potential human health and environmental impacts associated with soil contamination. The primary exposure pathways evaluated for explosives contaminated surface soils are dust inhalation, soil ingestion, and dermal absorption. Reasonable Maximum Exposure (RME) concentrations are based on the 95% upper confidence interval (UCI) on the arithmetic mean of soil sampling data. The land use scenarios quantitatively evaluated may include industrial and residential use, utilizing EPA standard default exposure parameters. 

Five types of biological treatment systems have been evaluated for explosives contaminated soils, including (1) composting, (2) anaerobic bioslurry, (3) aerobic bioslurry, (4) white rot fungus treatment, and (5) land farming. 

In 1988, the Army began a series of demonstration studies at the Louisiana Army Ammunition Plant to determine the effectiveness of composting explosives-contaminated soils. In the initial study, static-pile composting required 153 days to remediate soils contaminated with just 3% explosive waste by volume. 

Chemical and toxicological testing showed that nonaerated windrow composting can rapidly reduce extractable explosives, extractable mutagenic activity, and leachable toxicity of explosives-contaminated sediments. It is at least as efficient as the best static pile or mechanically stirred composting methods, based on results of other studies conducted at the same site, and thus is an excellent candidate for remediation of explosives-contaminated soils and sediments. 

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