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Emplacement of activated carbon (AC) into the subsurface is an emerging technology for ''in situ'' remediation. The technology has two components: activated carbon, which has high adsorption capacity for contaminants, and secondary chemical or biological amendments to stimulate ''in situ'' contaminant transformation. AC-based technology has been primarily applied at petroleum and chlorinated solvent contaminated sites where complex hydrogeology results in persistent plumes.  
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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)''':
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'''CONTRIBUTOR(S):'''  [[Dr. Samuel Beal]]
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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>
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==Introduction==
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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)]]
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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>.
  
'''Related Article(s):'''
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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>
  
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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).
  
'''CONTRIBUTOR(S):''' [[Dr. Dimin Fan]]
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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"/>.
  
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{| class="wikitable" style="float: right; text-align: center; margin-left: auto; margin-right: auto;"
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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.)
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! Military Range Type !! Analyte !! Range<br/>(mg/kg) !! Median<br/>(mg/kg) !! RSD<br/>(%)
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|-
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| colspan="5" style="text-align: left;" | '''Discrete Samples'''
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|-
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| Artillery FP || 2,4-DNT || <0.04 – 6.4 || 0.65 || 110
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|-
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| Antitank Rocket || HMX || 5.8 – 1,200 || 200 || 99
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|-
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| Bombing || TNT || 0.15 – 780 || 6.4 || 274
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|-
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| Mortar || RDX || <0.04 – 2,400 || 1.7 || 441
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|-
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| Artillery || RDX || <0.04 – 170 || <0.04 || 454
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|-
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| colspan="5" style="text-align: left;" | '''Incremental Samples*'''
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|-
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| Artillery FP || 2,4-DNT || 0.60 – 1.4 || 0.92 || 26
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|-
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| Bombing || TNT || 13 – 17 || 14 || 17
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|-
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| Artillery/Bombing || RDX || 3.9 – 9.4 || 4.8 || 38
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|-
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| Thermal Treatment || HMX || 3.96 – 4.26 || 4.16 || 4
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|-
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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.
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|}
  
'''Key Resource(s)''':
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==Incremental Sampling Approach==
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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]]
  
*[[media:2018-USEPA._Remedial_Technology_Fact_Sheet.pdf| Remedial Technology Fact Sheet - Activated Carbon-Based Technology for In Situ Remediation]]<ref name= "USEPA2018RT">U.S. Environmental Protection Agency (USEPA), 2018. Remedial Technology Fact Sheet - Activated Carbon-Based Technology for In Situ Remediation. EPA 542-f-18-001. [[media:2018-USEPA._Remedial_Technology_Fact_Sheet.pdf| Report.pdf]]</ref>.
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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.
*[https://clu-in.org/techfocus/default.focus/sec/Activated_Carbon-Based_Technology_for_In_Situ_Remediation/cat/Overview/ CLU-IN Technology Focus Area: Activated Carbon-Based Technology for In Situ Remediation]
 
  
==Introduction==
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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)]]
AC-based technology involves ''in situ'' emplacements of AC-based amendments in the subsurface to form an adsorptive/reactive zone for contaminant remediation<ref>Fan, D., Gilbert, E.J. and Fox, T., 2017. Current state of in situ subsurface remediation by activated carbon-based amendments. Journal of Environmental Management, 204, pp.793-803. [https://doi.org/10.1016/j.jenvman.2017.02.014 doi: 10.1016/j.jenvman.2017.02.014]</ref><ref name= "USEPA2018RT"/>.  As contaminated groundwater flows through this zone, the contaminants are retarded due to adsorption on to activated carbon. Sorption increases the residence time of contaminants within the reactive zone and therefore also increases contact with the reactive amendments, which has the potential to promote contaminant degradation.  
 
  
==Fundamental Processes==
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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.
  
===Adsorption===
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[[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>]]
Common organic contaminants are sorbed by AC mainly through [https://en.wikipedia.org/wiki/Van_der_Waals_force van der Waals forces]. Adsorption is reversible under typical subsurface conditions, so contaminants may be released if water chemistry changes or competing solutes are present<ref>To, P.C., Mariñas, B.J., Snoeyink, V.L. and Ng, W.J., 2008. Effect of strongly competing background compounds on the kinetics of trace organic contaminant desorption from activated carbon. Environmental Science & Technology, 42(7), pp.2606-2611. [https://doi.org/10.1021/es702609r doi: 10.1021/es702609r]</ref>.
 
  
The large adsorption capacity of AC is due to its highly porous internal structure and is influenced by many factors, including solution chemistry and presence of co-contaminants or dissolved organic matter (DOM) that compete for sorption sites.  Chemical and biological processes can also alter the AC, potentially reducing adsorption capacity. Regeneration of AC with persulfate can increase the polar functional groups that contain oxygen on the surface, reducing adsorption capacity<ref>Huling, S.G., Ko, S., Park, S. and Kan, E., 2011. Persulfate oxidation of MTBE-and chloroform-spent granular activated carbon. Journal of Hazardous Materials, 192(3), pp.1484-1490. [https://doi.org/10.1016/j.jhazmat.2011.06.070 doi: 10.1016/j.jhazmat.2011.06.070]</ref><ref>Hutson, A., Ko, S. and Huling, S.G., 2012. Persulfate oxidation regeneration of granular activated carbon: reversible impacts on sorption behavior. Chemosphere, 89(10), pp.1218-1223. [https://doi.org/10.1016/j.chemosphere.2012.07.040 doi: 10.1016/j.chemosphere.2012.07.040]</ref>.  Organic compounds released by microorganisms can compete for sorption sites, similar to DOM<ref>Aktaş, Ö., Schmidt, K.R., Mungenast, S., Stoll, C. and Tiehm, A., 2012. Effect of chloroethene concentrations and granular activated carbon on reductive dechlorination rates and growth of Dehalococcoides spp. Bioresource Technology, 103(1), pp.286-292. [https://doi.org/10.1016/j.biortech.2011.09.119 doi: 10.1016/j.biortech.2011.09.119]</ref><ref>Zhao, X., Hickey, R.F. and Voice, T.C., 1999. Long-term evaluation of adsorption capacity in a biological activated carbon fluidized bed reactor system. Water Research, 33(13), pp.2983-2991. [https://doi.org/10.1016/S0043-1354(99)00014-7 doi: 10.1016/S0043-1354(99)00014-7]</ref>. These factors are more likely to impact ''in situ'' treatment performance than that of above-ground engineered reactors due to the lack of process controls. For example, pre-treatment to remove metals and periodic backwash are both commonly used in ''ex situ'' treatment to improve the performance of activated carbon reactors, but are not practical for ''in situ'' applications.  
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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.
  
===Effects of Activated Carbon on Degradation===
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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>.
A variety of commercially available AC-based technologies have been developed in which AC is combined with [http://enviro.wiki/index.php?title=Zerovalent_Iron_(ZVI)_(Chemical_Reduction_-_ISCR) zero valent iron], [http://enviro.wiki/index.php?title=Chemical_Oxidation_(In_Situ_-_ISCO) chemical oxidants], or [http://enviro.wiki/index.php?title=Bioremediation_-_Anaerobic organic amendments] to stimulate contaminant degradation.
 
  
AC has also been shown to increase the longevity of abiotic dechlorination mediated by ZVI when ZVI is impregnated within the AC pore matrix<ref>Choi, H., Al-Abed, S.R. and Agarwal, S., 2009. Effects of aging and oxidation of palladized iron embedded in activated carbon on the dechlorination of 2-chlorobiphenyl. Environmental Science & Technology, 43(11), pp.4137-4142. [https://doi.org/10.1021/es803535b doi: 10.1021/es803535b]</ref><ref>Tseng, H.H., Su, J.G. and Liang, C., 2011. Synthesis of granular activated carbon/zero valent iron composites for simultaneous adsorption/dechlorination of trichloroethylene. Journal of Hazardous Materials, 192(2), pp.500-506. [https://doi.org/10.1016/j.jhazmat.2011.05.047 doi: 10.1016/j.jhazmat.2011.05.047]</ref>. This has been attributed to AC protecting ZVI from other side reactions that can consume Fe(0), such as reduction of water. The enhanced longevity of abiotic dechlorination has also been observed in one pilot test in which Carbo-Iron® &reg; was injected into a contaminated aquifer<ref>Mackenzie, K., Bleyl, S., Kopinke, F.D., Doose, H. and Bruns, J., 2016. Carbo-Iron as improvement of the nanoiron technology: From laboratory design to the field test. Science of the Total Environment, 563, pp.641-648. [https://doi.org/10.1016/j.scitotenv.2015.07.107 doi: 10.1016/j.scitotenv.2015.07.107]</ref><ref>Vogel, M., Nijenhuis, I., Lloyd, J., Boothman, C., Pöritz, M. and Mackenzie, K., 2018. Combined chemical and microbiological degradation of tetrachloroethene during the application of Carbo-Iron at a contaminated field site. Science of The Total Environment, 628, pp.1027-1036. [https://doi.org/10.1016/j.scitotenv.2018.01.310 doi: 10.1016/j.scitotenv.2018.01.310]</ref>.  
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==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.
  
AC addition has the potential to both enhance and inhibit biotransformation reactions. In ''ex situ'' water treatment applications, the large surface area of AC can promote microbial attachment and biofilm formation, enhancing some biodegradation processes<ref>Simpson, D.R., 2008. Biofilm processes in biologically active carbon water purification. Water Research, 42(12), pp.2839-2848. [https://doi.org/10.1016/j.watres.2008.02.025 doi: 0.1016/j.watres.2008.02.025]</ref><ref>Bushnaf, K.M., Mangse, G., Meynet, P., Davenport, R.J., Cirpka, O.A. and Werner, D., 2017. Mechanisms of distinct activated carbon and biochar amendment effects on petroleum vapour biofiltration in soil. Environmental Science: Processes & Impacts, 19(10), pp.1260-1269. [https://doi.org/10.1039/c7em00309a  doi: 10.1039/C7EM00309A]</ref>). Recently, AC-supported biofilms were shown to enhance the extent of dechlorination of polychlorinated biphenyls (PCBs) in sediment<ref>Kjellerup, B.V., Naff, C., Edwards, S.J., Ghosh, U., Baker, J.E. and Sowers, K.R., 2014. Effects of activated carbon on reductive dechlorination of PCBs by organohalide respiring bacteria indigenous to sediments. Water Research, 52, pp.1-10. [https://doi.org/10.1016/j.watres.2013.12.030 doi: 10.1016/j.watres.2013.12.030 ]</ref>, and of RDX in granular activated carbon (Bio-GAC) reactors<ref>Millerick, K., Drew, S.R. and Finneran, K.T., 2013. Electron shuttle-mediated biotransformation of hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine adsorbed to granular activated carbon. Environmental science & technology, 47(15), pp.8743-8750. [https://doi.org/10.1021/es401641s doi: 10.1021/es401641s]</ref>.  Adsorption to AC also has the potential to decrease contaminant availability for degradation because (''i'') micropores, the major sorption sites, are located deep in the AC pore matrix, which are physically separated from reactive amendments, and (''ii'') most degradation reactions require contaminants in the dissolved phase. If degradation processes cause aqueous phase concentration to decline, contaminants can desorb from the AC allowing further degradation.
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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.
  
AC addition could potentially enhance some biotransformation processes by facilitating direct interspecies electron transfer (DIET)<ref>Lovley, D.R., 2017. Syntrophy goes electric: direct interspecies electron transfer. Annual Review of Microbiology, 71, pp.643-664. [https://doi.org/10.1146/annurev-micro-030117-020420 doi: 10.1146/annurev-micro-030117-020420]</ref>. AC addition to anaerobic digesters has been shown to increase methane production.  Electrons produced during fermentation processes or hydrogen oxidation can be transferred through the AC to methanogens co-located on the activated carbon<ref>Liu, F., Rotaru, A.E., Shrestha, P.M., Malvankar, N.S., Nevin, K.P. and Lovley, D.R., 2012. Promoting direct interspecies electron transfer with activated carbon. Energy & Environmental Science, 5(10), pp.8982-8989. [https://doi.org/10.1039/c2ee22459c  doi: 10.1039/c2ee22459c ]</ref><ref>Yang, Y., Zhang, Y., Li, Z., Zhao, Z., Quan, X. and Zhao, Z., 2017. Adding granular activated carbon into anaerobic sludge digestion to promote methane production and sludge decomposition.  Journal of Cleaner Production, 149, pp.1101-1108. [https://doi.org/10.1016/j.jclepro.2017.02.156 doi:10.1016/j.jclepro.2017.02.156]</ref>).  However, the impact of AC addition on DIET in the subsurface has not been studied.
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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).
  
AC can be produced from a variety of different materials with different activation methods, pretreatments, and impregnations. These differences result in differing physical and chemical properties which can impact degradation processes. In recent laboratory studies, complete biological reductive dechlorination was inhibited in the presence of two different kinds of AC<ref>McGee, Kameryn and K.T. Finneran, In situ activated carbon for TCE remediation, ASM Microbe General Meeting, June 2018, to be presented in Atlanta, GA</ref>. These results are in contrast with the laboratory and field data reported for a commercial AC product, which have shown positive effects of AC on biological reductive dechlorination<ref>Valentine, M. Accelerate biodegradation of chlorinated contaminants facilitated using an in-situ liquid activated carbon: A pilot study and full-scale application in South Carolina. RemTEC 2017, Denver, CO. </ref>. The mechanisms that cause such a contrast are currently unknown, highlighting the need for further research.  
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<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>
  
==State of Practice==
+
==Analysis==
The first AC-based product for ''in situ'' groundwater remediation was developed in 2004. Since then, five more AC-based products have been developed (Table 1). Interests from practitioners and regulators have grown with increasing availability of commercial products. Together, these products have been applied at sites across North America and Europe. The largest proportion of applications have been at small retail gas station sites, focusing on treatment of petroleum constituents, primarily benzene, toluene, ethylbenzene and xylenes (BTEX).  However, the technology has been increasingly applied at large federal sites, such as Superfund sites, where chlorinated solvents are the major contaminants of concern<ref name= "USEPA2018RT"/>.  
+
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="text-align: center; margin-left: auto; margin-right: auto;"
+
{| class="wikitable" style="float: center; text-align: center; margin-left: auto; margin-right: auto;"
|+ Table 1. Properties of seven AC-based products that have been used for ''in situ'' applications
+
|+ 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>)
 +
|-
 +
! rowspan="2" | Compound
 +
! colspan="2" | Soil Reporting Limit (mg/kg)
 +
|-
 +
! HPLC (8330)
 +
! GC (8095)
 
|-
 
|-
! Product
+
| HMX || 0.04 || 0.01
! Property
 
! Target Contaminants
 
! Degradation Pathway
 
 
|-
 
|-
| BOS-100&reg; || Granular AC impregnated with ZVI || Chlorinated solvents || Abiotic reductive dechlorination
+
| RDX || 0.04 || 0.006
 
|-
 
|-
| BOS-200&reg; || Powder AC mixed with nutrients, electron acceptors, and facultative bacteria || Petroleum hydrocarbons || Aerobic and anaerobic biodegradation
+
| [[Wikipedia: 1,3,5-Trinitrobenzene | TNB]] || 0.04 || 0.003
 
|-
 
|-
| CAT-100&reg; || BOS-100&reg; plus reductive dechlorination bacterial strains || Chlorinated solvents || Abiotic and biotic reductive dechlorination
+
| TNT || 0.04 || 0.002
 
|-
 
|-
| COGAC&reg; || Powder AC mixed with calcium peroxide and sodium persulfate || Chlorinated solvents or petroleum hydrocarbons || Chemical oxidation, aerobic and anaerobic biodegradation
+
| [[Wikipedia: 2,6-Dinitrotoluene | 2,6-DNT]] || 0.08 || 0.002
 
|-
 
|-
| PlumeStop&reg; || Colloidal AC suspension with a proprietary organic stabilizer, co-applied with hydrogen or oxygen release compounds, and/or corresponding bacterial strains || Chlorinated solvents or petroleum hydrocarbons || Biotic reductive dechlorination of chlorinated solvents or aerobic biodegradation of petroleum hydrocarbons
+
| 2,4-DNT || 0.04 || 0.002
 
|-
 
|-
| Carbo-Iron&reg; || Colloidal AC impregnated with ZVI || Chlorinated solvents || Abiotic reductive dechlorination
+
| 2-ADNT || 0.08 || 0.002
 
|-
 
|-
| EHC-Plus&reg; || 35% (wt) microscale ZVI, 50% controlled-release organic carbon, 15% powder AC || Chlorinated solvents || Abiotic and biotic reductive dechlorination
+
| 4-ADNT || 0.08 || 0.002
 +
|-
 +
| NG || 0.1 || 0.01
 +
|-
 +
| [[Wikipedia: Dinitrobenzene | DNB ]] || 0.04 || 0.002
 +
|-
 +
| [[Wikipedia: Tetryl | Tetryl ]]  || 0.04 || 0.01
 +
|-
 +
| [[Wikipedia: Pentaerythritol tetranitrate | PETN ]] || 0.2 || 0.016
 
|}
 
|}
 
==Treatment Scenario==
 
AC-based technology has been primarily applied for management of persistent plumes resulting from the slow release of contaminants from low permeability zones (see [http://enviro.wiki/index.php?title=Dispersion_and_Diffusion Dispersion and Diffusion]).  The combination of ''in situ'' adsorption and degradation is thought to be more cost-effective than pump & treat (P&T) and sustain longer treatment effectiveness than degradation alone. Several field applications have demonstrated long-term effectiveness of AC-based technology<ref>Guilfoil, D., 2017. Karst bedrock remediation of PCE in Kentucky. 33rd Annual International Conference on Soils, Sediments, Water, and Energy. Amherst, MA</ref>. However, questions remain about whether adsorption or degradation is the primary process responsible for contaminant removal.
 
 
This technology has also been used to limit contaminant migration from groundwater to surface water, where high groundwater velocity limited the effectiveness of soluble amendments<ref>Krouse, C.; Fitzgerald, S.; Noland, S.; Thacker, N., 2016. Angled injection to mitigate PCE intrusion into a stream at a Federal superfund site in the Piedmont Region of North Carolina, 10th International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Palm Springs, CA.</ref>. 
 
 
==Implementation==
 
Implementation of ''in situ'' AC-based technologies follows similar design principles and engineering approaches as any other injection-based remediation technology. Subsurface hydrogeology and contaminant distribution, both vertically and horizontally, must be well understood and delineated.  Colloidal AC products can be injected under low pressure and transported through high permeability zones to reduce mass flux.  GAC and PAC-based products must be injected under pressure and are not expected to transport substantial distances.  The design loading rate of GAC and PAC-based products is typically determined by total mass of a contaminant in both high and low permeability zones.  The design loading rate of colloidal AC-based products is based on the dissolved contaminant mass flux.
 
 
Performance monitoring for ''in situ'' AC-based remedial technology requires multiple lines of evidence to confirm that contaminants are removed not only by adsorption but also by degradation. Reduction in concentration of parent compounds alone cannot differentiate degradation from adsorption.  If [http://enviro.wiki/index.php?title=Biodegradation_-_Reductive_Processes reductive dechlorination] is thought to be an important degradation process, treatment performance should be evaluated by monitoring for complete dechlorination products (e.g., ethene/ethane) and molecular indicators (e.g., ''Dehalococcoides'' population or presence of vinyl chloride reductase (''vcrA'')). For [http://enviro.wiki/index.php?title=Biodegradation_-_Hydrocarbons petroleum hydrocarbons], consumption of electron acceptors (e.g., nitrate or sulfate) or production of volatile fatty acids (VFAs) may serve as general indicators for biological degradation. [http://enviro.wiki/index.php?title=Molecular_Biological_Tools_-_MBTs Molecular diagnostic tools] may provide more definitive evidence by targeting specific functional genes necessary for biodegradation. 
 
  
 
==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