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Nitroaromatic and nitroamine compounds in munitions constituents are susceptible to rapid degradation under alkaline (i.e., basic, high pH) environmental conditions. Alkaline degradation of the secondary explosives TNT and RDX have been examined in laboratory-scale studies and field-scale demonstrations. Both topical and deeper soil-mixed applications of alkaline substances, such as hydrated lime and caustic soda, have successfully degraded munitions constituents in highly contaminated soils on training ranges and at formerly used defense sites (FUDS).
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The heterogeneous distribution of munitions constituents, released as particles from munitions firing and detonations on military training ranges, presents challenges for representative soil sample collection and for defensible decision making. Military range characterization studies and the development of the incremental sampling methodology (ISM) have enabled the development of recommended methods for soil sampling that produce representative and reproducible concentration data for munitions constituents. This article provides a broad overview of recommended soil sampling and processing practices for analysis of munitions constituents on military ranges.  
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<div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
  
<div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
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'''Related Article(s)''':  
  
'''Related Article(s):'''
 
*[[Munitions Constituents]]
 
*[[Munitions Constituents - Composting]]
 
  
 +
'''CONTRIBUTOR(S):'''  [[Dr. Samuel Beal]]
  
'''CONTRIBUTOR(S):''' [[Jared Johnson]]
 
  
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'''Key Resource(s)''':
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*[[media:Taylor-2011 ERDC-CRREL TR-11-15.pdf| Guidance for Soil Sampling of Energetics and Metals]]<ref name= "Taylor2011">Taylor, S., Jenkins, T.F., Bigl, S., Hewitt, A.D., Walsh, M.E. and Walsh, M.R., 2011. Guidance for Soil Sampling for Energetics and Metals (No. ERDC/CRREL-TR-11-15). [[media:Taylor-2011 ERDC-CRREL TR-11-15.pdf| Report.pdf]]</ref>
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*[[Media:Hewitt-2009 ERDC-CRREL TR-09-6.pdf| Report.pdf | Validation of Sampling Protocol and the Promulgation of Method Modifications for the Characterization of Energetic Residues on Military Testing and Training Ranges]]<ref name= "Hewitt2009">Hewitt, A.D., Jenkins, T.F., Walsh, M.E., Bigl, S.R. and Brochu, S., 2009. Validation of sampling protocol and the promulgation of method modifications for the characterization of energetic residues on military testing and training ranges (No. ERDC/CRREL-TR-09-6). Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) TR-09-6, Hanover, NH, USA. [[Media:Hewitt-2009 ERDC-CRREL TR-09-6.pdf | Report.pdf]]</ref>
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*[[media:Epa-2006-method-8330b.pdf| U.S. EPA SW-846 Method 8330B: Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC)]]<ref name= "USEPA2006M">U.S. Environmental Protection Agency (USEPA), 2006. Method 8330B (SW-846): Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC), Rev. 2. Washington, D.C. [[media:Epa-2006-method-8330b.pdf | Report.pdf]]</ref>
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*[[media:Epa-2007-method-8095.pdf | U.S. EPA SW-846 Method 8095: Explosives by Gas Chromatography.]]<ref name= "USEPA2007M">U.S. Environmental Protection Agency (US EPA), 2007. Method 8095 (SW-846): Explosives by Gas Chromatography. Washington, D.C. [[media:Epa-2007-method-8095.pdf| Report.pdf]]</ref>
  
'''Key Resource(s)''':
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==Introduction==
*[[media:2011_-_Johnson_-_Management_of_Munitions_Constituents_in_Soil.pdf | Management of Munitions Constituents in Soil Using Alkaline Hydrolysis: A Guide for Practitioners]]<ref name= "Johnson2011">Johnson, J.L., Felt, D.R., Martin, W.A., Britto, R., Nestler, C.C. and Larson, S.L., 2011. Management of munitions constituents in soil using alkaline hydrolysis: A guide for practitioners (No. ERDC/EL-TR-11-16). Vicksburg, MS: U.S. Army Engineer Research and Development Center.[[media:2011_-_Johnson_-_Management_of_Munitions_Constituents_in_Soil.pdf | Report.pdf]]</ref>
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[[File:Beal1w2 Fig1.png|thumb|200 px|left|Figure 1: Downrange distance of visible propellant plume on snow from the firing of different munitions. Note deposition behind firing line for the 84-mm rocket. Data from: Walsh et al.<ref>Walsh, M.R., Walsh, M.E., Ampleman, G., Thiboutot, S., Brochu, S. and Jenkins, T.F., 2012. Munitions propellants residue deposition rates on military training ranges. Propellants, Explosives, Pyrotechnics, 37(4), pp.393-406. [http://dx.doi.org/10.1002/prep.201100105 doi: 10.1002/prep.201100105]</ref><ref>Walsh, M.R., Walsh, M.E., Hewitt, A.D., Collins, C.M., Bigl, S.R., Gagnon, K., Ampleman, G., Thiboutot, S., Poulin, I. and Brochu, S., 2010. Characterization and Fate of Gun and Rocket Propellant Residues on Testing and Training Ranges: Interim Report 2. (ERDC/CRREL TR-10-13. Also: ESTCP Project ER-1481)  [[media:Walsh-2010 ERDC-CRREL TR-11-15 ESTCP ER-1481.pdf| Report]]</ref>]]
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[[File:Beal1w2 Fig2.png|thumb|left|200 px|Figure 2: A low-order detonation mortar round (top) with surrounding discrete soil samples produced concentrations spanning six orders of magnitude within a 10m by 10m area (bottom). (Photo and data: A.D. Hewitt)]]
  
==Principal of Operation==
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Munitions constituents are released on military testing and training ranges through several common mechanisms. Some are locally dispersed as solid particles from incomplete combustion during firing and detonation. Also, small residual particles containing propellant compounds (e.g., [[Wikipedia: Nitroglycerin | nitroglycerin [NG]]] and [[Wikipedia: 2,4-Dinitrotoluene | 2,4-dinitrotoluene [2,4-DNT]]]) are distributed in front of and surrounding target practice firing lines (Figure 1). At impact areas and demolition areas, high order detonations typically yield very small amounts (<1 to 10 mg/round) of residual high explosive compounds (e.g., [[Wikipedia: TNT | TNT ]], [[Wikipedia: RDX | RDX ]] and [[Wikipedia: HMX | HMX ]]) that are distributed up to and sometimes greater than) 24 m from the site of detonation<ref name= "Walsh2017">Walsh, M.R., Temple, T., Bigl, M.F., Tshabalala, S.F., Mai, N. and Ladyman, M., 2017. Investigation of Energetic Particle Distribution from High‐Order Detonations of Munitions. Propellants, Explosives, Pyrotechnics, 42(8), pp.932-941. [https://doi.org/10.1002/prep.201700089 doi: 10.1002/prep.201700089] [[media: Walsh-2017-High-Order-Detonation-Residues-Particle-Distribution-PEP.pdf| Report.pdf]]</ref>.
Alkaline hydrolysis reactions involve the aqueous interaction of added OH- ions with dissolved organic compounds. Degradation of nitroaromatics (i.e., TNT and DNT) is hypothesized to occur through formation of a Meisenheimer complex or TNT anion<ref>Saupe, A., Garvens, H.J. and Heinze, L., 1998. Alkaline hydrolysis of TNT and TNT in soil followed by thermal treatment of the hydrolysates. Chemosphere, 36(8), pp.1725-1744. [https://doi.org/10.1016/S0045-6535(97)10063-7 doi: 10.1016/S0045-6535(97)10063-7]</ref><ref>Salter-Blanc, A.J., Bylaska, E.J., Ritchie, J.J. and Tratnyek, P.G., 2013. Mechanisms and kinetics of alkaline hydrolysis of the energetic nitroaromatic compounds 2, 4, 6-trinitrotoluene (TNT) and 2, 4-dinitroanisole (DNAN). Environmental science & technology, 47(13), pp.6790-6798. [https://doi.org/10.1021/es304461t doi:10.1021/es304461t]</ref>. Initial denitration of nitroamines (i.e., RDX, HMX, and CL-20) by OH- is thought to cause molecular instability leading to ring cleavage, followed by spontaneous decomposition <ref>Jones, W.H., 1954. Mechanism of the Homogeneous Alkaline Decomposition of Cyclotrimethylenetrinitramine: Kinetics of Consecutive Second-and First-order Reactions. A Polarographic Analysis for Cyclotrimethylenetrinitramine1. Journal of the American Chemical Society, 76(3), pp.829-835. [https://doi.org/10.1021/ja01632a058 doi: 10.1021/ja01632a058]</ref><ref name= "Balakrishnan2003">Balakrishnan, V.K., Halasz, A. and Hawari, J., 2003. Alkaline hydrolysis of the cyclic nitramine explosives RDX, HMX, and CL-20: New insights into degradation pathways obtained by the observation of novel intermediates. Environmental Science & Technology, 37(9), pp.1838-1843. [https://doi.org/10.1021/es020959h doi: 10.1021/es020959h]</ref>. This degradation pathway is supported by observations of nitrite and formate production during the alkaline decomposition of nitramines<ref name= "Hwang2006">Hwang, S., Felt, D.R., Bouwer, E.J., Brooks, M.C., Larson, S.L. and Davis, J.L., 2006. Remediation of RDX-contaminated water using alkaline hydrolysis. Journal of Environmental Engineering, 132(2), pp.256-262. [https://doi.org/10.1061/(ASCE)0733-9372(2006)132:2(256) doi: 10.1061/(ASCE)0733-9372(2006)132:2(256)]</ref><ref name= ''Heilmann1996''>Heilmann, H.M., Wiesmann, U. and Stenstrom, M.K., 1996. Kinetics of the alkaline hydrolysis of high explosives RDX and HMX in aqueous solution and adsorbed to activated carbon. Environmental Science & Technology, 30(5), pp.1485-1492. [https://doi.org/10.1021/es9504101 doi: 10.1021/es9504101]</ref>.  
 
  
The terminal degradation products of alkaline hydrolysis are commonly formate, formaldehyde, nitrate, nitrite, and nitrous oxide. At pH greater than 11, TNT degrades readily to formate and nitrate, but at lower pH it tends to polymerize<ref>Felt, D.R., Nestler, C.C., Davis, J.L. and Larson, S.L., 2007. Potential for biodegradation of the alkaline hydrolysis end products of TNT and RDX (No. ERDC/EL-TR-07-25). Engineer Research and Development Center Vicksburg, MS. [[media:2001-Felt-_Potential_for_biodegradatio_of_the_alkaline_hydrolysis.pdf| Report.pdf]]</ref>.  
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Low-order detonations and duds are thought to be the primary source of munitions constituents on ranges<ref>Hewitt, A.D., Jenkins, T.F., Walsh, M.E., Walsh, M.R. and Taylor, S., 2005. RDX and TNT residues from live-fire and blow-in-place detonations. Chemosphere, 61(6), pp.888-894. [https://doi.org/10.1016/j.chemosphere.2005.04.058 doi: 10.1016/j.chemosphere.2005.04.058]</ref><ref>Walsh, M.R., Walsh, M.E., Poulin, I., Taylor, S. and Douglas, T.A., 2011. Energetic residues from the detonation of common US ordnance. International Journal of Energetic Materials and Chemical Propulsion, 10(2). [https://doi.org/10.1615/intjenergeticmaterialschemprop.2012004956 doi: 10.1615/IntJEnergeticMaterialsChemProp.2012004956] [[media:Walsh-2011-Energetic-Residues-Common-US-Ordnance.pdf| Report.pdf]]</ref>. Duds are initially intact but may become perforated or fragmented into micrometer to centimeter;o0i0k-sized particles by nearby detonations<ref>Walsh, M.R., Thiboutot, S., Walsh, M.E., Ampleman, G., Martel, R., Poulin, I. and Taylor, S., 2011. Characterization and fate of gun and rocket propellant residues on testing and training ranges (No. ERDC/CRREL-TR-11-13). Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) TR-11-13, Hanover, NH, USA. [[media:Epa-2006-method-8330b.pdf| Report.pdf]]</ref>. Low-order detonations can scatter micrometer to centimeter-sized particles up to 20 m from the site of detonation<ref name= "Taylor2004">Taylor, S., Hewitt, A., Lever, J., Hayes, C., Perovich, L., Thorne, P. and Daghlian, C., 2004. TNT particle size distributions from detonated 155-mm howitzer rounds. Chemosphere, 55(3), pp.357-367.[[media:Taylor-2004 TNT PSDs.pdf| Report.pdf]]</ref>
  
Propellant residues have been studied less than secondary explosives, but studies have shown the insoluble nitrocellulose matrix in some propellants to be rendered biodegradable under alkaline conditions<ref>Kenyon, W.O. and Gray, H.L., 1936. The Alkaline Decomposition of Cellulose Nitrate. I. Quantitative Studies1. Journal of The American Chemical Society, 58(8), pp.1422-1427. [https://doi.org/10.1021/ja01299a034 doi: 10.1021/ja01299a034]</ref><ref>Kim, B.J., Alleman, J.E. and Quivey, D.M., 1998. Alkaline hydrolysis/biodegradation of nitrocellulose fines (No. CERL-TR-98/65). Consstruction Engineering Researcg Lab (ARMY) Champaign, IL.[[media:1998-Kim-Alkline_Hydrolysis_Biodegradation_of_Nitrocellulose_Fines.pdf| Report.pdf]]</ref>. Ultimately, alkaline material is neutralized over time by the natural buffering capacity of soil.
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The particulate nature of munitions constituents in the environment presents a distinct challenge to representative soil sampling. Figure 2 shows an array of discrete soil samples collected around the site of a low-order detonation – resultant soil concentrations vary by orders of magnitude within centimeters of each other. The inadequacy of discrete sampling is apparent in characterization studies from actual ranges which show wide-ranging concentrations and poor precision (Table 1).
  
==Aqueous Kinetics==
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In comparison to discrete sampling, incremental sampling tends to yield reproducible concentrations (low relative standard deviation [RSD]) that statistically better represent an area of interest<ref name= "Hewitt2009"/>.
Degradation rates by alkaline hydrolysis for major secondary explosive compounds in aqueous systems have been measured under a range of pHs and temperatures (Table 1). Reported half-lives of TNT ranged from about 2-6 hours at pH 12 to up to six days at pH 11 in stirred aqueous reactors<ref name= ''Emmrich1999''>Emmrich, M., 1999. Kinetics of the alkaline hydrolysis of 2, 4, 6-trinitrotoluene in aqueous solution and highly contaminated soils. Environmental Science & Technology, 33(21), pp.3802-3805. [https://doi.org/10.1021/es9903227  doi: 10.1021/es9903227]</ref><ref name= "Hwang2005">Hwang, S., Ruff, T.J., Bouwer, E.J., Larson, S.L. and Davis, J.L., 2005. Applicability of alkaline hydrolysis for remediation of TNT-contaminated water. Water research, 39(18), pp.4503-4511. [https://doi.org/10.1016/j.watres.2005.09.008 doi: 10.1016/j.watres.2005.09.008]</ref>. Hydrolysis of RDX is reported to also occur with half-lives on the order of hours, with a strong dependence on temperature<ref name= ''Heilmann1996''/><ref name= "Hwang2006"/>. HMX reacted more slowly with a reaction rate two orders of magnitude slower than that observed for RDX<ref name= ''Heilmann1996''/>. Alkaline hydrolysis of the caged nitroamine CL-20 had an observed half-life of roughly one hour in pH 10 solution and on the order of minutes at higher pH<ref name= "Balakrishnan2003"/>.  
 
  
{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none; text-align: center;"
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{| class="wikitable" style="float: right; text-align: center; margin-left: auto; margin-right: auto;"
|+ <div style="text-align: center;"> Table 1. Observed Batch Kinetics for the Alkaline Destruction of Secondary Explosive Compounds in Aqueous Systems</div>
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|+ Table 1. Soil Sample Concentrations and Precision from Military Ranges Using Discrete and Incremental Sampling. (Data from Taylor et al. <ref name= "Taylor2011"/> and references therein.)
 
|-
 
|-
! Compound
+
! Military Range Type !! Analyte !! Range<br/>(mg/kg) !! Median<br/>(mg/kg) !! RSD<br/>(%)
! pH
 
! Temp<br />(&deg;C)
 
! Pseudo 1<sup>st</sup> Order<br />Decay Constant<br />(min<sup>-1</sup>)(10<sup>-3</sup>)
 
! Observed<br />Half-Life<br />(min)
 
! Reference
 
 
|-
 
|-
! rowspan="6" | TNT
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| colspan="5" style="text-align: left;" | '''Discrete Samples'''
| 10 || 20 ||0.0 || n/a || Emmrich, 1999<ref name= ''Emmrich1999''/>
 
 
|-
 
|-
| 11 || 20 || 0.43 || 1,600 || Emmrich, 1999<ref name= ''Emmrich1999''/>
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| Artillery FP || 2,4-DNT || <0.04 – 6.4 || 0.65 || 110
 
|-
 
|-
| 12 || 20 || 6.1 || 115 || Emmrich, 1999<ref name= ''Emmrich1999''/>
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| Antitank Rocket || HMX || 5.8 – 1,200 || 200 || 99
 
|-
 
|-
| 11 || 25 || 0.15 || 4,621 || Hwang, et al., 2005<ref name= "Hwang2005"/>
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| Bombing || TNT || 0.15 – 780 || 6.4 || 274
 
|-
 
|-
| 11.5 || 25 || 0.34 || 2,039 || Hwang, et al., 2005<ref name= "Hwang2005"/>
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| Mortar || RDX || <0.04 – 2,400 || 1.7 || 441
 
|-
 
|-
| 11.9 || 25 || 1.1 || 630 || Hwang, et al., 2005<ref name= "Hwang2005"/>
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| Artillery || RDX || <0.04 – 170 || <0.04 || 454
 
|-
 
|-
! rowspan="14" | RDX
+
| colspan="5" style="text-align: left;" | '''Incremental Samples*'''
| 11.18 || 50 || 9.3 || 75 || Heilmann, et al., 1996<ref name= ''Heilmann1996''/>
 
 
|-
 
|-
| 11.32 || 50 || 13 || 53 || Heilmann, et al., 1996<ref name= ''Heilmann1996''/>
+
| Artillery FP || 2,4-DNT || 0.60 – 1.4 || 0.92 || 26
 
|-
 
|-
| 12 || 50 || 58.2 || 12 || Heilmann, et al., 1996<ref name= ''Heilmann1996''/>
+
| Bombing || TNT || 13 – 17 || 14 || 17
 
|-
 
|-
| 12.3 || 50 || 127.2 || 5.5 || Heilmann, et al., 1996<ref name= ''Heilmann1996''/>
+
| Artillery/Bombing || RDX || 3.9 – 9.4 || 4.8 || 38
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|-
 +
| Thermal Treatment || HMX || 3.96 – 4.26 || 4.16 || 4
 
|-
 
|-
| 11 || 25 || 0.8 || 866 || Hwang, et al., 2006<ref name= "Hwang2006"/>
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| colspan="5" style="text-align: left; background-color: white;" | * For incremental samples, 30-100 increments and 3-10 replicate samples were collected.
|-
+
|}
| 11.5 || 25 || 1.7 || 408 || Hwang, et al., 2006<ref name= "Hwang2006"/>
+
 
|-
+
==Incremental Sampling Approach==
| 12 || 25 || 2.3 || 301 || Hwang, et al., 2006<ref name= "Hwang2006"/>
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ISM is a requisite for representative and reproducible sampling of training ranges, but it is an involved process that is detailed thoroughly elsewhere<ref name= "Hewitt2009"/><ref name= "Taylor2011"/><ref name= "USEPA2006M"/>. In short, ISM involves the collection of many (30 to >100) increments in a systematic pattern within a decision unit (DU). The DU may cover an area where releases are thought to have occurred or may represent an area relevant to ecological receptors (e.g., sensitive species). Figure 3 shows the ISM sampling pattern in a simplified (5x5 square) DU. Increments are collected at a random starting point with systematic distances between increments. Replicate samples can be collected by starting at a different random starting point, often at a different corner of the DU. Practically, this grid pattern can often be followed with flagging or lathe marking DU boundaries and/or sampling lanes and with individual pacing keeping systematic distances between increments. As an example, an artillery firing point might include a 100x100 m DU with 81 increments.
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[[File:Beal1w2 Fig3.png|thumb|200 px|left|Figure 3. Example ISM sampling pattern on a square decision unit. Replicates are collected in a systematic pattern from a random starting point at a corner of the DU. Typically more than the 25 increments shown are collected]]
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 +
DUs can vary in shape (Figure 4), size, number of increments, and number of replicates according to a project’s data quality objectives.
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 +
[[File:Beal1w2 Fig4.png|thumb|right|250 px|Figure 4: Incremental sampling of a circular DU on snow shows sampling lanes with a two-person team in process of collecting the second replicate in a perpendicular path to the first replicate. (Photo: Matthew Bigl)]]
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==Sampling Tools==
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In many cases, energetic compounds are expected to reside within the soil surface. Figure 5 shows soil depth profiles on some studied impact areas and firing points. Overall, the energetic compound concentrations below 5-cm soil depth are negligible relative to overlying soil concentrations. For conventional munitions, this is to be expected as the energetic particles are relatively insoluble, and any dissolved compounds readily adsorb to most soils<ref>Pennington, J.C., Jenkins, T.F., Ampleman, G., Thiboutot, S., Brannon, J.M., Hewitt, A.D., Lewis, J., Brochu, S., 2006. Distribution and fate of energetics on DoD test and training ranges: Final Report. ERDC TR-06-13, Vicksburg, MS, USA. Also: SERDP/ESTCP Project ER-1155. [[media:Pennington-2006_ERDC-TR-06-13_ESTCP-ER-1155-FR.pdf| Report.pdf]]</ref>. Physical disturbance, as on hand grenade ranges, may require deeper sampling either with a soil profile or a corer/auger.
 +
 
 +
[[File:Beal1w2 Fig5.png|thumb|left|200 px|Figure 5. Depth profiles of high explosive compounds at impact areas (bottom) and of propellant compounds at firing points (top). Data from: Hewitt et al. <ref>Hewitt, A.D., Jenkins, T.F., Ramsey, C.A., Bjella, K.L., Ranney, T.A. and Perron, N.M., 2005. Estimating energetic residue loading on military artillery ranges: Large decision units (No. ERDC/CRREL-TR-05-7). [[media:Hewitt-2005 ERDC-CRREL TR-05-7.pdf| Report.pdf]]</ref> and Jenkins et al. <ref>Jenkins, T.F., Ampleman, G., Thiboutot, S., Bigl, S.R., Taylor, S., Walsh, M.R., Faucher, D., Mantel, R., Poulin, I., Dontsova, K.M. and Walsh, M.E., 2008. Characterization and fate of gun and rocket propellant residues on testing and training ranges (No. ERDC-TR-08-1). [[media:Jenkins-2008 ERDC TR-08-1.pdf| Report.pdf]]</ref>]]
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 +
Soil sampling with the Cold Regions Research and Engineering Laboratory (CRREL) Multi-Increment Sampling Tool (CMIST) or similar device is an easy way to collect ISM samples rapidly and reproducibly. This tool has an adjustable diameter size corer and adjustable depth to collect surface soil plugs (Figure 6). The CMIST can be used at almost a walking pace (Figure 7) using a two-person sampling team, with one person operating the CMIST and the other carrying the sample container and recording the number of increments collected. The CMIST with a small diameter tip works best in soils with low cohesion, otherwise conventional scoops may be used. Maintaining consistent soil increment dimensions is critical.
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The sampling tool should be cleaned between replicates and between DUs to minimize potential for cross-contamination<ref>Walsh, M.R., 2009. User’s manual for the CRREL Multi-Increment Sampling Tool. Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) SR-09-1, Hanover, NH, USA.  [[media:Walsh-2009 ERDC-CRREL SR-09-1.pdf | Report.pdf]]</ref>.
 +
 
 +
==Sample Processing==
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While only 10 g of soil is typically used for chemical analysis, incremental sampling generates a sample weighing on the order of 1 kg. Splitting of a sample, either in the field or laboratory, seems like an easy way to reduce sample mass; however this approach has been found to produce high uncertainty for explosives and propellants, with a median RSD of 43.1%<ref name= "Hewitt2009"/>. Even greater error is associated with removing a discrete sub-sample from an unground sample. Appendix A in [https://www.epa.gov/sites/production/files/2015-07/documents/epa-8330b.pdf U.S. EPA Method 8330B]<ref name= "USEPA2006M"/> provides details on recommended ISM sample processing procedures.
 +
 
 +
Incremental soil samples are typically air dried over the course of a few days. Oven drying thermally degrades some energetic compounds and should be avoided<ref>Cragin, J.H., Leggett, D.C., Foley, B.T., and Schumacher, P.W., 1985. TNT, RDX and HMX explosives in soils and sediments: Analysis techniques and drying losses. (CRREL Report 85-15) Hanover, NH, USA. [[media:Cragin-1985 CRREL 85-15.pdf| Report.pdf]]</ref>. Once dry, the samples are sieved with a 2-mm screen, with only the less than 2-mm fraction processed further. This size fraction represents the USDA definition of soil. Aggregate soil particles should be broken up and vegetation shredded to pass through the sieve. Samples from impact or demolition areas may contain explosive particles from low order detonations that are greater than 2 mm and should be identified, given appropriate caution, and potentially weighed.
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 +
The <2-mm soil fraction is typically still ≥1 kg and impractical to extract in full for analysis. However, subsampling at this stage is not possible due to compositional heterogeneity, with the energetic compounds generally present as <0.5 mm particles<ref name= "Walsh2017"/><ref name= "Taylor2004"/>. Particle size reduction is required to achieve a representative and precise measure of the sample concentration. Grinding in a puck mill to a soil particle size <75 µm has been found to be required for representative/reproducible sub-sampling (Figure 8). For samples thought to contain propellant particles, a prolonged milling time is required to break down these polymerized particles and achieve acceptable precision (Figure 9). Due to the multi-use nature of some ranges, a 5-minute puck milling period can be used for all soils. Cooling periods between 1-minute milling intervals are recommended to avoid thermal degradation. Similar to field sampling, sub-sampling is done incrementally by spreading the sample out to a thin layer and collecting systematic random increments of consistent volume to a total mass for extraction of 10 g (Figure 10).
 +
 
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig6.png|thumb|200 px|Figure 6: CMIST soil sampling tool (top) and with ejected increment core using a large diameter tip (bottom).]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig7.png|thumb|200 px|Figure 7: Two person sampling team using CMIST, bag-lined bucket, and increment counter. (Photos: Matthew Bigl)]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig8.png|thumb|200 px|Figure 8: Effect of machine grinding on RDX and TNT concentration and precision in soil from a hand grenade range. Data from Walsh et al.<ref>Walsh, M.E., Ramsey, C.A. and Jenkins, T.F., 2002. The effect of particle size reduction by grinding on subsampling variance for explosives residues in soil. Chemosphere, 49(10), pp.1267-1273. [https://doi.org/10.1016/S0045-6535(02)00528-3 doi: 10.1016/S0045-6535(02)00528-3]</ref> ]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig9.png|thumb|200 px|Figure 9: Effect of puck milling time on 2,4-DNT concentration and precision in soil from a firing point. Data from Walsh et al.<ref>Walsh, M.E., Ramsey, C.A., Collins, C.M., Hewitt, A.D., Walsh, M.R., Bjella, K.L., Lambert, D.J. and Perron, N.M., 2005. Collection methods and laboratory processing of samples from Donnelly Training Area Firing Points, Alaska, 2003 (No. ERDC/CRREL-TR-05-6). [[media:Walsh-2005 ERDC-CRREL TR-05-6.pdf| Report.pdf]]</ref>.]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig10.png|thumb|200 px|center|Figure 10: Incremental sub-sampling of a milled soil sample spread out on aluminum foil.]]</li>
 +
 
 +
==Analysis==
 +
Soil sub-samples are extracted and analyzed following [[Media: epa-2006-method-8330b.pdf | EPA Method 8330B]]<ref name= "USEPA2006M"/> and [[Media:epa-2007-method-8095.pdf | Method 8095]]<ref name= "USEPA2007M"/> using [[Wikipedia: High-performance liquid chromatography | High Performance Liquid Chromatography (HPLC)]] and [[Wikipedia: Gas chromatography | Gas Chromatography (GC)]], respectively. Common estimated reporting limits for these analysis methods are listed in Table 2.
 +
 
 +
{| class="wikitable" style="float: center; text-align: center; margin-left: auto; margin-right: auto;"
 +
|+ Table 2. Typical Method Reporting Limits for Energetic Compounds in Soil. (Data from Hewitt et al.<ref>Hewitt, A., Bigl, S., Walsh, M., Brochu, S., Bjella, K. and Lambert, D., 2007. Processing of training range soils for the analysis of energetic compounds (No. ERDC/CRREL-TR-07-15). Hanover, NH, USA. [[media:Hewitt-2007 ERDC-CRREL TR-07-15.pdf| Report.pdf]]</ref>)
 
|-
 
|-
| 12.2 || 25 || 7.9 || 88 || Hwang, et al., 2006<ref name= "Hwang2006"/>
+
! rowspan="2" | Compound
 +
! colspan="2" | Soil Reporting Limit (mg/kg)
 
|-
 
|-
| 12.6 || 25 || 22.3 || 31 || Hwang, et al., 2006<ref name= "Hwang2006"/>
+
! HPLC (8330)
 +
! GC (8095)
 
|-
 
|-
| 13 || 25 || 27.7 || 25 || Hwang, et al., 2006<ref name= "Hwang2006"/>
+
| HMX || 0.04 || 0.01
 
|-
 
|-
| 12 || 25 || 2.7 || 260 || Gent, et al., 2010<ref name= '' Gent2010''>Gent, D.B., Johnson, J.L., Felt, D.R., O'Connor, G., Holland, E., May, S. and Larson, S.L., 2010. Laboratory demonstration of abiotic technologies for removal of RDX from a process waste stream (No. ERDC/EL-TR-10-8). Engineer Research and Development Center Vicksburg MS Environmental Lab. [[media:2010-Gent-laboratory_Demostration_of_abiotic_tech_for_removal_of_RDX.pdf| Report.pdf]]</ref>
+
| RDX || 0.04 || 0.006
 
|-
 
|-
| 12.5 || 25 || 8.3 || 83 || Gent, et al., 2010<ref name= '' Gent2010''/>
+
| [[Wikipedia: 1,3,5-Trinitrobenzene | TNB]] || 0.04 || 0.003
 
|-
 
|-
| 13 || 25 || 26.8 || 26 || Gent, et al., 2010<ref name= '' Gent2010''/>
+
| TNT || 0.04 || 0.002
 
|-
 
|-
| 13.3 || 25 || 52.3 || 13 || Gent, et al., 2010<ref name= '' Gent2010''/>
+
| [[Wikipedia: 2,6-Dinitrotoluene | 2,6-DNT]] || 0.08 || 0.002
 
|-
 
|-
! rowspan="3" | HMX
+
| 2,4-DNT || 0.04 || 0.002
| 10.34 || 50 || 0.09 || 7,788 || Heilmann, et al., 1996<ref name= ''Heilmann1996''/>
 
 
|-
 
|-
| 11.32 || 50 || 0.99 || 700 || Heilmann, et al., 1996<ref name= ''Heilmann1996''/>
+
| 2-ADNT || 0.08 || 0.002
 
|-
 
|-
| 12.36 || 50 || 1.1 || 641 || Heilmann, et al., 1996<ref name= ''Heilmann1996''/>
+
| 4-ADNT || 0.08 || 0.002
 
|-
 
|-
! rowspan="4" | CL-20
+
| NG || 0.1 || 0.01
| 10 || 25 || 8 || 87 || Santiago, et al., 2007<ref name= "Santigo2007">Santiago, L., Felt, D.R. and Davis, J.L., 2007. Chemical Remediation of an Ordnance-Related Compound: The Alkaline Hydrolysis of CL-20. Environmental Quality Technology Program (No. ERDC/EL-TR-07-18). Engineer Research and Development Center, Vicksburg, MS Environmental Lab. [[media:2007-Santiago-chemical_remediation_of_an_ordnance_related_compound.pdf| Report.pdf]]</ref>
 
 
|-
 
|-
| 11 || 25 || 50.3 || 14 || Santiago, et al., 2007<ref name= "Santigo2007"/>
+
| [[Wikipedia: Dinitrobenzene | DNB ]] || 0.04 || 0.002
 
|-
 
|-
| 11.5 || 25 || 147.7 || 4.7 || Santiago, et al., 2007<ref name= "Santigo2007"/>
+
| [[Wikipedia: Tetryl | Tetryl ]]  || 0.04 || 0.01
 
|-
 
|-
| 12 || 25 || 858 || 0.8 || Santiago, et al., 2007<ref name= "Santigo2007"/>
+
| [[Wikipedia: Pentaerythritol tetranitrate | PETN ]] || 0.2 || 0.016
 
|}
 
|}
 
==Performance in Soil Systems==
 
[[File:Johnson1w2 Fig1.png|thumb|right|Figure 1: RDX concentrations in leachate by rain event for meso-scale lysimeters containing hand grenade range soils as reported by Larson et al. (2007)<ref name= "Larson2007"/>]]
 
 
Alkaline material is neutralized over time by the natural buffering capacity of the soil. Protons (H<sup>+</sup>) exchanged from low pH soils and metal cations interact with hydroxide (OH<sup>-</sup>) ions to mitigate the alkaline degradation of munitions constituents. Furthermore, hydrogen ions associated with various functional groups in humic matter may also dissociate under elevated pH conditions and likewise inhibit alkaline hydrolysis of the explosive contaminants. Soil chemistry therefore plays an important role in energetics remediation through alkaline hydrolysis.
 
 
Soil microcosm studies with 5% w/w calcium hydroxide and 50% w/w water observed half-lives for TNT, RDX, and HMX on the order of a day to a week, with degradation rates following the sequence of TNT > RDX > HMX, similar to the aqueous studies. Soil slurries using 2,4-DNT and the single amino substituted TNT degradation products (4A-2,6-DNT and 2A-4,6-DNT) also exhibited day to week-long half-lives at pH 11 and 12<ref name= ''Emmrich1999''/><ref>Emmrich, M., 2001. Kinetics of the alkaline hydrolysis of important nitroaromatic co-contaminants of 2, 4, 6-trinitrotoluene in highly contaminated soils. Environmental Science & Technology, 35(5), pp.874-877. [https://doi.org/10.1021/es0014990 doi: 10.1021/es0014990 doi: 10.1021/es0014990 ]</ref>.
 
 
A meso-scale soil treatability study was conducted using soils collected from two different hand grenade ranges<ref name= "Larson2007">Larson, S.L., Davis, J.L., Martin, W.A., Felt, D.R., Nestler, C.C., Brandon, D.L., Fabian, G. and O'Connor, G., 2007. Grenade Range Management Using Lime for Metals Immobilization and Explosives Transformation Treatability Study (No. ERDC/EL-TR-07-5). Vicksburg, MS: U.S. Army Engineer Research and Development Center. [[media:2007-Larson-grenade_Range_Management_Using_Lime_for_Metals_Immobilization.pdf| Report.pdf]]</ref>. These soils were treated with a well-mixed application of hydrated lime, and migration of RDX was monitored by analyzing porewater concentrations in installed lysimeters over time (Figure 1). Overall, the reduction in RDX leaving the mesocosms as both leachate and runoff was greater than 90% with application of hydrated lime. The study authors also observed that alkaline amendments were able to fix metals contamination in place on hand grenade range soils.
 
 
==Field-Scale Performance Examples==
 
===Hand Grenade Range===
 
[[File:Johnson1w2 Fig2.png|thumb|Figure 2: Mean pore water RDX concentrations by hand grenade bay and lysimeter with maximum and  minimum concentration profiles (avg, n ranges from 7 to 10; modified from Larson et al., 2007)<ref name= "Larson2007"/>.]]
 
Alkaline hydrolysis was successfully employed at a hand grenade range that experiences ~55,000 hand grenade detonations each year<ref name= "Larson2007"/><ref>Martin, W.A., Felt, D.R., Nestler, C.C., Fabian, G., O’Connor, G. and Larson, S.L., 2012. Hydrated Lime for Metal Immobilization and Explosives Transformation: Field Demonstration. Journal of Hazardous, Toxic, and Radioactive Waste, 17(3), pp.237-244. [https://doi.org/10.1061/(ASCE)HZ.2153-5515.0000176 doi: 10.1061/(ASCE)HZ.2153-5515.0000176]</ref>. During this demonstration, initial soil samples were collected from individual grenade bays and lysimeters were installed to a depth of 5 feet below ground surface. Lime was applied in December, 2005, April, 2006, and January, 2007, with nine discrete sampling events occurring between December, 2005, and March, 2007. Lysimeter concentrations are shown in Figure 2 for one treated grenade bay and another untreated control bay. Based on the average pore water concentration in the treated and untreated bays over the demonstration period, there was a 77% reduction in RDX concentration in pore water from the treated bay. There is a statistically significant difference between the explosives concentration in the pore water from the untreated vs. the limed bays (P < 0.001).
 
 
A project has been funded beginning in FY19 to re-examine liming practices at this hand grenade range and produce a report on the long term efficacy of this management technique for an active training range.
 
 
===Ammunition Plant===
 
''Ex-situ'' alkaline hydrolysis was used at an ammunition plant to remediate surface soil (0 to 20 feet below ground surface) that had high concentrations of DNT and TNT<ref name= "Johnson2011"/>. Laboratory experiments on this soil demonstrated that target nitroaromatic compounds could be reduced to less than 10 mg/kg within a week. The only final product of note was nitrite, which could be destroyed via a denitrification process if necessary. Over a two-year period, approximately 150,000 tons of impacted soils were treated and approximately 148,000 lbs of nitroaromatic compounds destroyed, with an average contaminant mass reduction of 96 percent. Subsequent ''in-situ'' treatment was used to remediate over 15,000 additional tons of soil.
 
 
[[File:Johnson1w2 Fig3.png|thumb|right|Figure 3: Soil mixing during ex situ alkaline treatment of soils  at an ammunition plant.]]
 
The basic ''ex-situ'' treatment process involved the excavation of contaminated soil to a lined basin onsite. A typical excavation is shown in Figure 3. Caustic reagents in pellet form were added at a one to two percent weight by weight basis (depending on the starting concentrations, starting pH, and the buffering capacity) along with small quantities of metal catalyst, if needed. The soil was treated in 300 cubic yard batches, with amended chemicals thoroughly mixed into the soil using conventional equipment.  Water was added as needed to increase the moisture content to near saturation. Mixing was repeated two to three times a week and samples were collected for moisture content and pH, which are critical field monitoring and effectiveness parameters. 
 
 
After one week, soil sampling was performed per site specific sampling protocol and analyzed for contaminants of concern, daughter products, and breakdown products.  If needed for soil with higher concentrations of explosives, caustic reagent was supplemented to maintain the pH at the 13.0 unit level.  Soil continued to be treated until TNT and DNT concentrations were below cleanup levels (57 mg/kg for TNT and 25.4 mg/kg for total DNTs).  Metals were also analyzed periodically and TCLP tests were performed per site treatment goals.  When needed on a small percentage of batches, denitrification of soil was performed to lower the nitrite end-product using citric acid as the pH reducer and carbon substrate. After complete treatment, the soil was transported back to the excavation.  ''In-situ'' treatment is performed in a similar way to ''ex-situ'' treatment using conventional equipment and prescribed quantities of chemical reagents.
 
 
Some general heuristic guidelines are summarized in Figure 4. An active firing range requires treatment technologies that have minimal soil disturbance, requiring topical application of hydrated lime for most range applications. Therefore the fate of hydroxide (OH-) ions during transport through the soil is an important aspect of this proposed remediation technology. Studies performed by the agricultural and oil industries provide evidence of the transport limitations of hydroxide ions in soils, particularly in those soils with significant clay content <ref>Breit, V.S., Mayer, E.H. and Carmichael, J.D., 1979, January. An easily applied black oil model of caustic waterflooding. In SPE California Regional Meeting. Society of Petroleum Engineers. [https://doi.org/10.2118/7999-MS doi: 10.2118/7999-MS]</ref><ref>DeZabala, E.F., Vislocky, J.M., Rubin, E. and Radke, C.J., 1982. A chemical theory for linear alkaline flooding. Society of Petroleum Engineers Journal, 22(02), pp.245-258. [https://doi.org/10.2118/8997-PA [https://doi.org/10.2118/8997-PA doi: 10.2118/8997-PA]</ref><ref>Somerton, W. H., and C. J. Radke. 1980. Roles of clays in the enhanced recovery of petroleum. Proceedings of the first joint SPE/DOE symposium on enhance oil recovery. Society of Petroleum Engineers</ref><ref>Smith, C.J., Peoples, M.B., Keerthisinghe, G., James, T.R., Garden, D.L. and Tuomi, S.S., 1994. Effect of surface applications of lime, gypsum and phosphogypsum on the alleviating of surface and subsurface acidity in a soil under pasture. Soil Research, 32(5), pp.995-1008. [https://doi.org/10.1071/SR9940995 doi: 10.1071/SR9940995]</ref>.
 
 
[[File:Johnson1w2 Fig4.png|thumb|center|400 px|Figure 4: General heuristics for determining application of alkaline amendments for the management of munitions constituents in soil.]]
 
  
 
==References==
 
==References==
<references />
+
<references/>
 
 
  
 
==See Also==
 
==See Also==
 +
*[https://itrcweb.org/ Interstate Technology and Regulatory Council]
 +
*[http://www.hawaiidoh.org/tgm.aspx Hawaii Department of Health]
 +
*[http://envirostat.org/ Envirostat]

Latest revision as of 18:58, 29 April 2020

The heterogeneous distribution of munitions constituents, released as particles from munitions firing and detonations on military training ranges, presents challenges for representative soil sample collection and for defensible decision making. Military range characterization studies and the development of the incremental sampling methodology (ISM) have enabled the development of recommended methods for soil sampling that produce representative and reproducible concentration data for munitions constituents. This article provides a broad overview of recommended soil sampling and processing practices for analysis of munitions constituents on military ranges.

Related Article(s):


CONTRIBUTOR(S): Dr. Samuel Beal


Key Resource(s):

Introduction

Figure 1: Downrange distance of visible propellant plume on snow from the firing of different munitions. Note deposition behind firing line for the 84-mm rocket. Data from: Walsh et al.[5][6]
Figure 2: A low-order detonation mortar round (top) with surrounding discrete soil samples produced concentrations spanning six orders of magnitude within a 10m by 10m area (bottom). (Photo and data: A.D. Hewitt)

Munitions constituents are released on military testing and training ranges through several common mechanisms. Some are locally dispersed as solid particles from incomplete combustion during firing and detonation. Also, small residual particles containing propellant compounds (e.g., nitroglycerin [NG] and 2,4-dinitrotoluene [2,4-DNT]) are distributed in front of and surrounding target practice firing lines (Figure 1). At impact areas and demolition areas, high order detonations typically yield very small amounts (<1 to 10 mg/round) of residual high explosive compounds (e.g., TNT , RDX and HMX ) that are distributed up to and sometimes greater than) 24 m from the site of detonation[7].

Low-order detonations and duds are thought to be the primary source of munitions constituents on ranges[8][9]. Duds are initially intact but may become perforated or fragmented into micrometer to centimeter;o0i0k-sized particles by nearby detonations[10]. Low-order detonations can scatter micrometer to centimeter-sized particles up to 20 m from the site of detonation[11]

The particulate nature of munitions constituents in the environment presents a distinct challenge to representative soil sampling. Figure 2 shows an array of discrete soil samples collected around the site of a low-order detonation – resultant soil concentrations vary by orders of magnitude within centimeters of each other. The inadequacy of discrete sampling is apparent in characterization studies from actual ranges which show wide-ranging concentrations and poor precision (Table 1).

In comparison to discrete sampling, incremental sampling tends to yield reproducible concentrations (low relative standard deviation [RSD]) that statistically better represent an area of interest[2].

Table 1. Soil Sample Concentrations and Precision from Military Ranges Using Discrete and Incremental Sampling. (Data from Taylor et al. [1] and references therein.)
Military Range Type Analyte Range
(mg/kg)
Median
(mg/kg)
RSD
(%)
Discrete Samples
Artillery FP 2,4-DNT <0.04 – 6.4 0.65 110
Antitank Rocket HMX 5.8 – 1,200 200 99
Bombing TNT 0.15 – 780 6.4 274
Mortar RDX <0.04 – 2,400 1.7 441
Artillery RDX <0.04 – 170 <0.04 454
Incremental Samples*
Artillery FP 2,4-DNT 0.60 – 1.4 0.92 26
Bombing TNT 13 – 17 14 17
Artillery/Bombing RDX 3.9 – 9.4 4.8 38
Thermal Treatment HMX 3.96 – 4.26 4.16 4
* For incremental samples, 30-100 increments and 3-10 replicate samples were collected.

Incremental Sampling Approach

ISM is a requisite for representative and reproducible sampling of training ranges, but it is an involved process that is detailed thoroughly elsewhere[2][1][3]. In short, ISM involves the collection of many (30 to >100) increments in a systematic pattern within a decision unit (DU). The DU may cover an area where releases are thought to have occurred or may represent an area relevant to ecological receptors (e.g., sensitive species). Figure 3 shows the ISM sampling pattern in a simplified (5x5 square) DU. Increments are collected at a random starting point with systematic distances between increments. Replicate samples can be collected by starting at a different random starting point, often at a different corner of the DU. Practically, this grid pattern can often be followed with flagging or lathe marking DU boundaries and/or sampling lanes and with individual pacing keeping systematic distances between increments. As an example, an artillery firing point might include a 100x100 m DU with 81 increments.

Figure 3. Example ISM sampling pattern on a square decision unit. Replicates are collected in a systematic pattern from a random starting point at a corner of the DU. Typically more than the 25 increments shown are collected

DUs can vary in shape (Figure 4), size, number of increments, and number of replicates according to a project’s data quality objectives.

Figure 4: Incremental sampling of a circular DU on snow shows sampling lanes with a two-person team in process of collecting the second replicate in a perpendicular path to the first replicate. (Photo: Matthew Bigl)

Sampling Tools

In many cases, energetic compounds are expected to reside within the soil surface. Figure 5 shows soil depth profiles on some studied impact areas and firing points. Overall, the energetic compound concentrations below 5-cm soil depth are negligible relative to overlying soil concentrations. For conventional munitions, this is to be expected as the energetic particles are relatively insoluble, and any dissolved compounds readily adsorb to most soils[12]. Physical disturbance, as on hand grenade ranges, may require deeper sampling either with a soil profile or a corer/auger.

Figure 5. Depth profiles of high explosive compounds at impact areas (bottom) and of propellant compounds at firing points (top). Data from: Hewitt et al. [13] and Jenkins et al. [14]

Soil sampling with the Cold Regions Research and Engineering Laboratory (CRREL) Multi-Increment Sampling Tool (CMIST) or similar device is an easy way to collect ISM samples rapidly and reproducibly. This tool has an adjustable diameter size corer and adjustable depth to collect surface soil plugs (Figure 6). The CMIST can be used at almost a walking pace (Figure 7) using a two-person sampling team, with one person operating the CMIST and the other carrying the sample container and recording the number of increments collected. The CMIST with a small diameter tip works best in soils with low cohesion, otherwise conventional scoops may be used. Maintaining consistent soil increment dimensions is critical.

The sampling tool should be cleaned between replicates and between DUs to minimize potential for cross-contamination[15].

Sample Processing

While only 10 g of soil is typically used for chemical analysis, incremental sampling generates a sample weighing on the order of 1 kg. Splitting of a sample, either in the field or laboratory, seems like an easy way to reduce sample mass; however this approach has been found to produce high uncertainty for explosives and propellants, with a median RSD of 43.1%[2]. Even greater error is associated with removing a discrete sub-sample from an unground sample. Appendix A in U.S. EPA Method 8330B[3] provides details on recommended ISM sample processing procedures.

Incremental soil samples are typically air dried over the course of a few days. Oven drying thermally degrades some energetic compounds and should be avoided[16]. Once dry, the samples are sieved with a 2-mm screen, with only the less than 2-mm fraction processed further. This size fraction represents the USDA definition of soil. Aggregate soil particles should be broken up and vegetation shredded to pass through the sieve. Samples from impact or demolition areas may contain explosive particles from low order detonations that are greater than 2 mm and should be identified, given appropriate caution, and potentially weighed.

The <2-mm soil fraction is typically still ≥1 kg and impractical to extract in full for analysis. However, subsampling at this stage is not possible due to compositional heterogeneity, with the energetic compounds generally present as <0.5 mm particles[7][11]. Particle size reduction is required to achieve a representative and precise measure of the sample concentration. Grinding in a puck mill to a soil particle size <75 µm has been found to be required for representative/reproducible sub-sampling (Figure 8). For samples thought to contain propellant particles, a prolonged milling time is required to break down these polymerized particles and achieve acceptable precision (Figure 9). Due to the multi-use nature of some ranges, a 5-minute puck milling period can be used for all soils. Cooling periods between 1-minute milling intervals are recommended to avoid thermal degradation. Similar to field sampling, sub-sampling is done incrementally by spreading the sample out to a thin layer and collecting systematic random increments of consistent volume to a total mass for extraction of 10 g (Figure 10).

  • Figure 6: CMIST soil sampling tool (top) and with ejected increment core using a large diameter tip (bottom).
  • Figure 7: Two person sampling team using CMIST, bag-lined bucket, and increment counter. (Photos: Matthew Bigl)
  • Figure 8: Effect of machine grinding on RDX and TNT concentration and precision in soil from a hand grenade range. Data from Walsh et al.[17]
  • Figure 9: Effect of puck milling time on 2,4-DNT concentration and precision in soil from a firing point. Data from Walsh et al.[18].
  • Figure 10: Incremental sub-sampling of a milled soil sample spread out on aluminum foil.
  • Analysis

    Soil sub-samples are extracted and analyzed following EPA Method 8330B[3] and Method 8095[4] using High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC), respectively. Common estimated reporting limits for these analysis methods are listed in Table 2.

    Table 2. Typical Method Reporting Limits for Energetic Compounds in Soil. (Data from Hewitt et al.[19])
    Compound Soil Reporting Limit (mg/kg)
    HPLC (8330) GC (8095)
    HMX 0.04 0.01
    RDX 0.04 0.006
    TNB 0.04 0.003
    TNT 0.04 0.002
    2,6-DNT 0.08 0.002
    2,4-DNT 0.04 0.002
    2-ADNT 0.08 0.002
    4-ADNT 0.08 0.002
    NG 0.1 0.01
    DNB 0.04 0.002
    Tetryl 0.04 0.01
    PETN 0.2 0.016

    References

    1. ^ 1.0 1.1 1.2 Taylor, S., Jenkins, T.F., Bigl, S., Hewitt, A.D., Walsh, M.E. and Walsh, M.R., 2011. Guidance for Soil Sampling for Energetics and Metals (No. ERDC/CRREL-TR-11-15). Report.pdf
    2. ^ 2.0 2.1 2.2 2.3 Hewitt, A.D., Jenkins, T.F., Walsh, M.E., Bigl, S.R. and Brochu, S., 2009. Validation of sampling protocol and the promulgation of method modifications for the characterization of energetic residues on military testing and training ranges (No. ERDC/CRREL-TR-09-6). Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) TR-09-6, Hanover, NH, USA. Report.pdf
    3. ^ 3.0 3.1 3.2 3.3 U.S. Environmental Protection Agency (USEPA), 2006. Method 8330B (SW-846): Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC), Rev. 2. Washington, D.C. Report.pdf
    4. ^ 4.0 4.1 U.S. Environmental Protection Agency (US EPA), 2007. Method 8095 (SW-846): Explosives by Gas Chromatography. Washington, D.C. Report.pdf
    5. ^ Walsh, M.R., Walsh, M.E., Ampleman, G., Thiboutot, S., Brochu, S. and Jenkins, T.F., 2012. Munitions propellants residue deposition rates on military training ranges. Propellants, Explosives, Pyrotechnics, 37(4), pp.393-406. doi: 10.1002/prep.201100105
    6. ^ Walsh, M.R., Walsh, M.E., Hewitt, A.D., Collins, C.M., Bigl, S.R., Gagnon, K., Ampleman, G., Thiboutot, S., Poulin, I. and Brochu, S., 2010. Characterization and Fate of Gun and Rocket Propellant Residues on Testing and Training Ranges: Interim Report 2. (ERDC/CRREL TR-10-13. Also: ESTCP Project ER-1481) Report
    7. ^ 7.0 7.1 Walsh, M.R., Temple, T., Bigl, M.F., Tshabalala, S.F., Mai, N. and Ladyman, M., 2017. Investigation of Energetic Particle Distribution from High‐Order Detonations of Munitions. Propellants, Explosives, Pyrotechnics, 42(8), pp.932-941. doi: 10.1002/prep.201700089 Report.pdf
    8. ^ Hewitt, A.D., Jenkins, T.F., Walsh, M.E., Walsh, M.R. and Taylor, S., 2005. RDX and TNT residues from live-fire and blow-in-place detonations. Chemosphere, 61(6), pp.888-894. doi: 10.1016/j.chemosphere.2005.04.058
    9. ^ Walsh, M.R., Walsh, M.E., Poulin, I., Taylor, S. and Douglas, T.A., 2011. Energetic residues from the detonation of common US ordnance. International Journal of Energetic Materials and Chemical Propulsion, 10(2). doi: 10.1615/IntJEnergeticMaterialsChemProp.2012004956 Report.pdf
    10. ^ Walsh, M.R., Thiboutot, S., Walsh, M.E., Ampleman, G., Martel, R., Poulin, I. and Taylor, S., 2011. Characterization and fate of gun and rocket propellant residues on testing and training ranges (No. ERDC/CRREL-TR-11-13). Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) TR-11-13, Hanover, NH, USA. Report.pdf
    11. ^ 11.0 11.1 Taylor, S., Hewitt, A., Lever, J., Hayes, C., Perovich, L., Thorne, P. and Daghlian, C., 2004. TNT particle size distributions from detonated 155-mm howitzer rounds. Chemosphere, 55(3), pp.357-367. Report.pdf
    12. ^ Pennington, J.C., Jenkins, T.F., Ampleman, G., Thiboutot, S., Brannon, J.M., Hewitt, A.D., Lewis, J., Brochu, S., 2006. Distribution and fate of energetics on DoD test and training ranges: Final Report. ERDC TR-06-13, Vicksburg, MS, USA. Also: SERDP/ESTCP Project ER-1155. Report.pdf
    13. ^ Hewitt, A.D., Jenkins, T.F., Ramsey, C.A., Bjella, K.L., Ranney, T.A. and Perron, N.M., 2005. Estimating energetic residue loading on military artillery ranges: Large decision units (No. ERDC/CRREL-TR-05-7). Report.pdf
    14. ^ Jenkins, T.F., Ampleman, G., Thiboutot, S., Bigl, S.R., Taylor, S., Walsh, M.R., Faucher, D., Mantel, R., Poulin, I., Dontsova, K.M. and Walsh, M.E., 2008. Characterization and fate of gun and rocket propellant residues on testing and training ranges (No. ERDC-TR-08-1). Report.pdf
    15. ^ Walsh, M.R., 2009. User’s manual for the CRREL Multi-Increment Sampling Tool. Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) SR-09-1, Hanover, NH, USA. Report.pdf
    16. ^ Cragin, J.H., Leggett, D.C., Foley, B.T., and Schumacher, P.W., 1985. TNT, RDX and HMX explosives in soils and sediments: Analysis techniques and drying losses. (CRREL Report 85-15) Hanover, NH, USA. Report.pdf
    17. ^ Walsh, M.E., Ramsey, C.A. and Jenkins, T.F., 2002. The effect of particle size reduction by grinding on subsampling variance for explosives residues in soil. Chemosphere, 49(10), pp.1267-1273. doi: 10.1016/S0045-6535(02)00528-3
    18. ^ Walsh, M.E., Ramsey, C.A., Collins, C.M., Hewitt, A.D., Walsh, M.R., Bjella, K.L., Lambert, D.J. and Perron, N.M., 2005. Collection methods and laboratory processing of samples from Donnelly Training Area Firing Points, Alaska, 2003 (No. ERDC/CRREL-TR-05-6). Report.pdf
    19. ^ Hewitt, A., Bigl, S., Walsh, M., Brochu, S., Bjella, K. and Lambert, D., 2007. Processing of training range soils for the analysis of energetic compounds (No. ERDC/CRREL-TR-07-15). Hanover, NH, USA. Report.pdf

    See Also