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The addition of woody debris to streams is a common restoration practice. Woody debris dams were added to four streams at Fort Benning Military Installation in 2003 to mitigate the impacts of military training activities on stream ecosystems. The short-term (3 y) and long-term (14 y) effects of these woody debris dams on ecosystem processes and community structure were evaluated. There were several changes to stream ecosystems after the woody debris additions including increased water residence times, primary production rates, ecosystem respiration rates, rates of nitrogen uptake, and retention of organic matter, as well as changes to macroinvertebrate communities. The woody debris dams were still in place 14 years later, and their long-term effects on the streams’ ecosystems are currently being evaluated.
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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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'''Related Article(s):'''
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'''Related Article(s)''':
  
  
'''CONTRIBUTOR(S):''' [[Dr. Natalie Griffiths]], [[Dr. Jack Feminella]], [[Dr. Brian Helms]], [[Sam Bickley]], and [[Dan Isenberg]]  
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'''CONTRIBUTOR(S):''' [[Dr. Samuel Beal]]
  
  
'''Key Resource(s)''':
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'''Key Resource(s)''':  
*[[media:2006-Mulholland-Riparian_Ecosystem_Mgmt_at_Miitary_Installations.pdf| Riparian Ecosystem Management at Military Installations: Determination of Impacts and Evaluation of Restoration and Enhancement Strategies]]<ref name= "Mulholland2007">Mulholland, P.J., Feminella, J.W., Lockaby, B.G. and Hollon, G.L., 2007. Riparian Ecosystem Management at Military Installations: Determination of Impacts and Evaluation of Restoration and Enhancement Strategies. Final Technical Report SI-1186. Pp.161. [[media:2006-Mulholland-Riparian_Ecosystem_Mgmt_at_Miitary_Installations.pdf|Report.pdf]]</ref>
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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>
*[https://doi.org/10.1899/0887-3593(2007)26(38:EOUDAI)2.0.CO;2 Effects of Upland Disturbance and Instream Restoration on Hydrodynamics and Ammonium Uptake in Headwater Streams]<ref name= "Roberts2007">Roberts, B.J., Mulholland, P.J. and Houser, J.N., 2007. Effects of upland disturbance and instream restoration on hydrodynamics and ammonium uptake in headwater streams. Journal of the North American Benthological Society, 26(1), pp.38-53. [https://doi.org/10.1899/0887-3593(2007)26(38:EOUDAI)2.0.CO;2 doi:10.1899/0887-3593(2007)26(38:EOUDAI)2.0.CO;2]</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>
*[https://doi.org/10.2307/1936830 Importance of Organic Debris Dams in the Structure and Function of Stream Ecosystems]<ref name= "Bilby1980">Bilby, R.E. and Likens, G.E., 1980. Importance of organic debris dams in the structure and function of stream ecosystems. Ecology, 61(5), pp.1107-1113. [https://doi.org/10.2307/1936830 doi: 10.2307/1936830]</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>
  
 
==Introduction==
 
==Introduction==
Headwater streams are important components of river networks. Headwaters are often the most pristine portion of a watershed; however, like most waterways, headwater streams are not impervious to degradation from anthropogenic and natural sources<ref>US Environmental Protection Agency (USEPA), 2006. Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams. EPA. Office of Research and Development, Office of Water, Washington DC 20460. EPA 841-B-06-002. [[media:2006-USEPA-Wadeable_Streams_Assessment.pdf| Report.pdf]]</ref>. Because of their close hydrologic connection to the surrounding terrestrial environment, headwater streams can be particularly influenced by land disturbances<ref>Allan, J.D., 2004. Landscapes and riverscapes: the influence of land use on stream ecosystems. Annu. Rev. Ecol. Evol. Syst., 35, pp.257-284. [https://doi.org/10.1146/annurev.ecolsys.35.120202.110122 doi: 10.1146/annurev.ecolsys.35.120202.110122]</ref><ref name= "Maloney2005">Maloney, K.O., Mulholland, P.J. and Feminella, J.W., 2005. Influence of catchment-scale military land use on stream physical and organic matter variables in small southeastern plains catchments (USA). Environmental Management, 35(5), pp.677-691. [http://dx.doi.org/10.1007/s00267-005-8651-5 doi: 10.1007/s00267-005-8651-5]</ref><ref>Walsh, C.J., Roy, A.H., Feminella, J.W., Cottingham, P.D., Groffman, P.M. and Morgan, R.P., 2005. The urban stream syndrome: current knowledge and the search for a cure. Journal of the North American Benthological Society, 24(3), pp.706-723. [https://doi.org/10.1899/04-028.1 doi: 10.1899/04-028.1]</ref> et al. 2005). Further, because of the hierarchical nature of river networks, disturbances in headwaters can influence downstream ecosystems<ref>Rabalais, N.N., Turner, R.E. and Wiseman Jr, W.J., 2002. Gulf of Mexico hypoxia, aka “The dead zone”. Annual Review of ecology and Systematics, 33(1), pp.235-263. [https://doi.org/10.1146/annurev.ecolsys.33.010802.150513 doi: 10.1146/annurev.ecolsys.33.010802.150513]</ref>. Minimizing human impacts on small streams is important for the protection of these ecosystems and their biodiversity and also because of the multiple ecosystem services provided by headwaters (e.g., water for drinking, bathing, recreation, consumption of fish, etc.).
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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)]]
  
In-stream restoration is an overarching term used to describe the process of improving the ecological condition of stream ecosystems<ref>Palmer, M.A., Bernhardt, E.S., Allan, J.D., Lake, P.S., Alexander, G., Brooks, S., Carr, J., Clayton, S., Dahm, C.N., Shah, J.F. and Galat, D.L., 2005. Standards for ecologically successful river restoration. Journal of applied ecology, 42(2), pp.208-217. [https://doi.org/10.1111/j.1365-2664.2005.01004.x doi: 10.1111/j.1365-2664.2005.01004.x]</ref>. Restoration is a common practice that is used around the globe, and billions of dollars are spent on stream restoration projects<ref name= "Bernhardt2005">Bernhardt, E.S., Palmer, M.A., Allan, J.D., Alexander, G., Barnas, K., Brooks, S., Carr, J., Clayton, S., Dahm, C., Follstad-Shah, J. and Galat, D., 2005. Synthesizing US river restoration efforts. Science. Vol. 308, Issue 5722, pp. 636-637. [https://doi.org/10.1126/science.1109769  doi: 10.1126/science.1109769]</ref>. However, few restoration projects have been monitored after installation, and fewer still have been monitored for long periods of time<ref name= "Bernhardt2005"/>. It has been even less common for stream restoration monitoring activities to evaluate both the structure (e.g., water quality, macroinvertebrates) and function (e.g., carbon and nutrient cycling) of streams<ref>Lake, P.S., Bond, N. and Reich, P., 2007. Linking ecological theory with stream restoration. Freshwater Biology, 52(4), pp.597-615. [https://doi.org/10.1111/j.1365-2427.2006.01709.x doi: 10.1111/j.1365-2427.2006.01709.x]</ref>.  
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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>.
  
One common restoration method is the addition of large wood (i.e., coarse woody debris or CWD) to stream channels. CWD additions are a low-cost restoration method<ref name= "Bernhardt2005"/>. In practice, nearby riparian trees are felled, cut, and placed into the channel of the stream. Wood additions can have several effects on the stream including altering the morphology and hydraulics of the stream, creating habitat for macroinvertebrates and fish, creating colonization surfaces for algae and microorganisms, and increasing the retention of sediment and organic matter, the latter of which is an important basal resource for many stream food webs<ref name= "Bilby1980"/><ref>Smock, L.A., Metzler, G.M. and Gladden, J.E., 1989. Role of debris dams in the structure and functioning of low‐gradient headwater streams. Ecology, 70(3), pp.764-775. [https://doi.org/10.2307/1940226 doi: 10.2307/1940226]</ref><ref>Bilby, R.E. and Ward, J.W., 1991. Characteristics and function of large woody debris in streams draining old-growth, clear-cut, and second-growth forests in southwestern Washington. Canadian Journal of Fisheries and Aquatic Sciences, 48(12), pp.2499-2508. [https://doi.org/10.1139/f91-291 doi: 10.1139/f91-291]</ref><ref name= "Roberts2007"/><ref>Roni, P., Beechie, T., Pess, G. and Hanson, K., 2014. Wood placement in river restoration: fact, fiction, and future direction. Canadian Journal of Fisheries and Aquatic Sciences, 72(3), pp.466-478. [https://doi.org/10.1139/cjfas-2014-0344 doi: 10.1139/cjfas-2014-0344]</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>
  
==Assessment of In-Stream Restoration Practices at Fort Benning Military Installation==
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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).
Fort Benning Military Installation (FBMI) is located in central-west Georgia, USA, in the Southeastern Plains Level-III ecoregion<ref>Omernik, James M. "Ecoregions of the conterminous United States." Annals of the Association of American geographers77, no. 1 (1987): 118-125. [https://doi.org/10.1111/j.1467-8306.1987.tb00149.x doi: 10.1111/j.1467-8306.1987.tb00149.x]</ref>. FBMI was established in 1918, and military training activities have been ongoing since that time. It is likely that due to the lack of agricultural or urban land use within the boundaries of FBMI, several threatened species, endangered species, and species of special concern persist<ref name= "Dale2002">Dale, V.H., Beyeler, S.C. and Jackson, B., 2002. Understory vegetation indicators of anthropogenic disturbance in longleaf pine forests at Fort Benning, Georgia, USA. Ecological indicators, 1(3), pp.155-170. [https://doi.org/10.1016/S1470-160X(01)00014-0 doi: 10.1016/S1470-160X(01)00014-0]</ref>. An important objective at FBMI is maintaining environmental sustainability while meeting military training objectives ([http://www.benning.army.mil/Garrison/sustainability/ Sustainability])<ref name= "Dale2002"/>.  
 
  
Military training activities (i.e., dismounted infantry tactics, tracked vehicle maneuvers) on sandy upland soils can lead to erosion and high sedimentation rates in streams at FBMI<ref>Lockaby, B.G., Governo, R., Schilling, E., Cavalcanti, G. and Hartsfield, C., 2005. Effects of sedimentation on soil nutrient dynamics in riparian forests. Journal of Environmental Quality, 34(1), pp.390-396. [https://doi.org/10.2134/jeq2005.0390 doi:10.2134/jeq2005.0390]</ref><ref name= "Maloney2005"/><ref name= "Houser2005">Houser, J.N., Mulholland, P.J. and Maloney, K.O., 2005. Catchment disturbance and stream metabolism: patterns in ecosystem respiration and gross primary production along a gradient of upland soil and vegetation disturbance. Journal of the North American Benthological Society, 24(3), pp.538-552. [https://doi.org/10.1899/04-034.1 doi: 10.1899/04-034.1]</ref><ref>Houser, J.N., Mulholland, P.J. and Maloney, K.O., 2006. Upland disturbance affects headwater stream nutrients and suspended sediments during baseflow and stormflow. Journal of Environmental Quality, 35(1), pp.352-365. [https://doi.org/10.2134/jeq2005.0102 doi:10.2134/jeq2005.0102]</ref><ref name= "Mulholland2007"/>. Therefore, an experimental stream restoration pilot project was implemented in 2003 at FBMI to determine whether CWD additions would reduce the effects of military activities on stream ecosystem processes.  
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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"/>.
  
Two SERDP projects have focused on evaluating the effects of those CWD additions on the streams’ ecosystem structure and function. The first project compared stream ecosystem processes before (2001-2003) and for three years after (2003-2006) the addition of CWD dams to streams at FBMI. The second project is measuring the same ecosystem processes 14 years after the CWD additions (2017-2018) to determine whether there have been any long-term benefits.
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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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|-
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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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|}
  
==CWD Additions at FBMI==
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==Incremental Sampling Approach==
[[File:Griffiths1w2 Fig1.png|thumb|left|Figure 1. CWD Additions Shortly After Installation in a Stream]]
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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.
[[File:Griffiths1w2 Fig2.png|thumb|left|Figure 2. Burial of CWD Dams in a Restored Stream (Photo taken in March 2006)]]
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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]]
[[File:Griffiths1w2 Fig3.png|thumb|right|Figure 3. Location of the Study Streams at Fort Benning Military Installation Used in the 14-year Reassessment of CWD Addition Efficacy]]
 
  
CWD additions were installed in 4 headwater streams within Ft. Benning’s boundaries as part of a previously funded SERDP project (SI-1186)<ref name= "Mulholland2007"/>. Riparian trees (blackgum [''Nyssa sylvatica''] or white oak [''Quercus alba'']) were used for the CWD additions. The trees were felled on-site in August 2003 and cut to the desired length. The trees were left on land to dry for 2-3 months prior to installation in the stream. In October 2003, the cut trees (~10-20 cm diameter, 1-2 m in length) were added in a “Z” design along a 100-150 m section within each stream. Three cut tree sections were used to make the “Z” design, and 10-15 of these “Z”-shaped woody debris dams were installed along each stream length (~10 m apart). The CWD dams were anchored using rebar stakes driven into the streambed. The “Z” design was used to increase the retention of organic matter and slow water flow to maintain a stable streambed. The CWD additions approximately doubled the amount of CWD in the restored streams. The CWD additions themselves increased the coverage of CWD in the streams by 3.1 to 5.2%, resulting in a total CWD coverage (naturally occurring + added CWD) of 6.9 to 12.1%<ref name= "Mulholland2007"/>.  
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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.
  
One issue encountered several months after the CWD additions was excessive sedimentation that led to the burial of much of the added CWD in 2 of the 4 restored streams. Sedimentation and burial was likely exacerbated by high precipitation and stream flow in the post-restoration period, as the summer precipitation amounts in 2003, 2004 and 2005 were among the highest on record at that time<ref name= "Mulholland2007"/>. Because of the issue of CWD burial, the original CWD additions were augmented with additional wood in 2004, and the CWD coverage in these two streams was thereby tripled<ref name= "Mulholland2007"/>. Burial of CWD dams was assessed in 2005, and ranged from 30 to 75% in the restored streams.
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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)]]
  
==Assessment of Restoration Efficacy==
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==Sampling Tools==
The 2007 SERDP project used a before-after control-intervention (BACI) approach<ref name= "StewartO1986">Stewart-Oaten, A., Murdoch, W.W. and Parker, K.R., 1986. Environmental impact assessment:" Pseudoreplication" in time?. Ecology, 67(4), pp.929-940. [https://doi.org/10.2307/1939815 doi: 10.2307/1939815]</ref> to assess the effects of CWD addition on stream ecosystem structure and function. From July 2001 through October 2003, pre-restoration measurements were made at 8 stream sites on a monthly and seasonal basis. In October 2003, CWD dams were installed at 4 of the 8 stream sites, leaving 4 stream sites to serve as unrestored controls. From October 2003 through November 2006, post-restoration measurements were made at all 8 stream sites on a monthly and seasonal basis, enabling pre- and post-restoration periods to be compared using the BACI method<ref name= "StewartO1986"/>.  
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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.
  
Beginning in May 2017, 14 years after the CWD additions, monthly and seasonal measurements resumed at 7 of the 8 stream sites (one unrestored site was not included in the reassessment because it was disturbed) to assess the long-term efficacy of CWD additions as a stream restoration technique. A subset of the 2007 study’s ecosystem structure and function measurements was collected from May 2017 through November 2018.
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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>]]
[[File:Griffiths1w2 Fig4.png|thumb|right|Figure 4. Nutrient Addition at one of the Study Streams]]
 
[[File:Griffiths1w2 Fig5.png|thumb|right|Figure 5. Collection of Macroinvertebrates in One of the Study Streams]]
 
  
==Initial Effects of Restoration (2001-2006)==
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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.
This section describes the main findings from a study that evaluated the initial effects of CWD additions on stream ecosystem structure and function including effects on water quality, nutrient uptake, stream metabolism, benthic particulate organic matter, and macroinvertebrates as these responses were measured for three years immediately after restoration. For a more complete description of these and other findings, please see Mulholland et al. 2007<ref name= "Mulholland2007"/>.
 
  
Water quality grab samples were collected approximately monthly (8x/year) and were analyzed for total and inorganic suspended sediments, dissolved organic carbon, ammonium, nitrate, and soluble reactive phosphorus concentrations. Field measurements of temperature, specific conductance and pH were collected during each site visit. In general, there were no changes to these water quality parameters in restored streams in the 2004-2006 post-restoration period<ref name= "Mulholland2007"/>.
+
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>.
  
Seasonal, short-term ammonium releases were conducted to assess the effect of CWD additions on ammonium uptake metrics, which measure the rate at which nutrients (ammonium) cycle in streams<ref>Tank, J.L., Bernot, M.J. and Rosi-Marshall, E.J., 2007. Nitrogen limitation and uptake. In Methods in Stream Ecology (pp. 213-238). ISBN 13: 978-0-12-332908-0, ISBN 10: 0-12-332908-6</ref>. The ammonium uptake rate increased in restored streams immediately (within 1 month) after restoration<ref name= "Roberts2007"/>. There are several reasons as to why the CWD additions may have led to an increase in ammonium uptake rate. First, it is likely that the CWD additions increased the size of the transient storage zone (defined as hyporheic zones and areas of slow moving water) which allowed for increased removal of nutrients via biotic or abiotic mechanisms<ref name= "Roberts2007"/>. Second, the CWD may have acted as a stable substrate to allow algae and microbial biofilms to colonize, and these organisms subsequently took up the added nutrients<ref name= "Roberts2007"/>. Lastly, the CWD may have increased retention of organic matter, leading to increased demand for nutrients by biofilms that colonize that organic matter.
+
==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%<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.
  
Whole-stream ecosystem metabolism is a measure of gross primary production (GPP) and ecosystem respiration (ER), and represents how organic carbon is produced and consumed by organisms within the stream<ref>Tank, J.L., Rosi-Marshall, E.J., Griffiths, N.A., Entrekin, S.A. and Stephen, M.L., 2010. A review of allochthonous organic matter dynamics and metabolism in streams. Journal of the North American Benthological Society, 29(1), pp.118-146. [https://doi.org/10.1899/08-170.1 doi: 10.1899/08-170.1]</ref>. Whole-stream metabolism was measured seasonally in each stream in the pre- and post-restoration periods using the one-station diel oxygen change method<ref name= "Houser2005"/><ref>Bott, T. L. 2006. Primary productivity and community respiration. Methods in Stream Ecology, 2nd ed., pp.263-290. Elsevier, New York </ref>. GPP rates did not change in the first year after CWD additions. However, GPP rates increased in 3 of the 4 restored streams from autumn 2004 through spring 2005, likely due to increased algal growth on CWD. This was corroborated by increased algal biomass (chlorophyll a concentration) in the restored streams in winter 2004<ref name= "Mulholland2007"/>. After the initial increase in GPP in restored streams, GPP rates decreased and were not different than in the pre-restoration period<ref name= "Mulholland2007"/>. ER rates increased in restored streams for the first 2 years after CWD additions (2004-2005) likely due to the increases in transient storage zone size, increased area for microbial colonization, and increased organic matter retention. By 2006, ER rates in restored streams decreased to pre-restoration levels likely due to burial of the CWD<ref name= "Mulholland2007"/>.
+
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.
  
Benthic particulate organic matter (BPOM) is organic matter (e.g., leaves, wood) that is retained on the surface of the stream bed (i.e., by debris dams) or within the near surface sediments. In sandy-bottom streams, BPOM acts as an important source of nutrition for the primary consumers (e.g., stream macroinvertebrates)<ref>Cummins, K.W., and M.J. Klug. 1979. Feeding ecology of stream invertebrates. Annual Review of Ecology and Systematics 10:147-172 [https://doi.org/10.1146/annurev.es.10.110179.001051 doi: 10.1146/annurev.es.10.110179.001051 ]</ref>. There was no clear effect of CWD additions on BPOM in restored vs. unrestored streams; however, BPOM increased within the CWD additions suggesting that these debris dams increased the retention of organic matter<ref name= "Mulholland2007"/>.  
+
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).
 
Macroinvertebrates are a diverse group of organisms, and several macroinvertebrate metrics are used to assess the health of stream ecosystems<ref>Barbour, M.T., Gerritsen, J., Snyder, B.D. and Stribling, J.B., 1999. Rapid bioassessment protocols for use in streams and wadeable rivers: periphyton, benthic macroinvertebrates and fish (Vol. 339). Washington, DC: US Environmental Protection Agency, Office of Water. EPA 841-B-99-02. [[media:1999-Barbour-Rapid_bioassessment_protocols_for_use_in_streams_and_wadeable_rivers.pdf| Report.pdf]]</ref><ref>Maloney, K.O. and Feminella, J.W., 2006. Evaluation of single-and multi-metric benthic macroinvertebrate indicators of catchment disturbance over time at the Fort Benning Military Installation, Georgia, USA. Ecological Indicators, 6(3), pp.469-484. [https://doi.org/10.1016/j.ecolind.2005.06.003 doi: 10.1016/j.ecolind.2005.06.003]</ref>. Macroinvertebrate assemblage responses to CWD additions were variable, with the effects varying by season and by invertebrate metric (e.g., diversity, Ephemeroptera, Plecoptera, Trichoptera [EPT] taxa). EPT density, which is often used as an indicator of stream health, increased in restored streams post-restoration, but only in winter<ref name= "Mulholland2007"/>. The percentage of taxa classified as clingers (which attach to surfaces in the stream) also increased in restored streams in the post-restoration period compared to unrestored streams, but only in spring<ref name= "Mulholland2007"/>. Clingers require stable substrata and the CWD dams may have provided this stable habitat. The percentage of taxa classified as shredders (which consume organic matter) increased in restored streams in the post-restoration period, but only immediately after the CWD additions (winter 2004). There was no difference in percentage of shredders between restored and unrestored streams when all post-restoration years (2004-2006) were examined. The initial increase in shredders may have reflected increased retention of organic matter by the CWD dams; however, the diminishing effect of the CWD additions over time may have reflected high stream flow and burial of CWD dams. Further, total macroinvertebrate density decreased over time likely reflecting the periods of high stream flow in the post-restoration period. There were no clear effects of restoration on total macroinvertebrate density.
 
  
[[File:Griffiths1w2 Fig6.png|thumb|right|Figure 6. CWD Dams Immediately After Restoration (from Mulholland et al. 2007<ref name= "Mulholland2007"/>)]]
+
<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>
[[File:Griffiths1w2 Fig7.png|thumb|right|Figure 7. CWD Dams 14 Years After Restoration (Photo taken by Sam Bickley)]]
+
<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>
  
==Long-Term Effects of Restoration (2017-2018)==
+
==Analysis==
From May 2017 through November 2018, post-restoration measurements of stream ecosystem structure and function were made approximately 14 years after the CWD additions in 7 streams (3 unrestored, 4 restored) on a monthly and seasonal basis. This study design enabled the long-term assessment of CWD dam additions as a restoration tool. Water chemistry was measured at each stream monthly, and ammonium uptake rates, whole-stream metabolism estimates, BPOM content, and macroinvertebrates were measured at each stream on a seasonal basis.
+
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.
  
Analyses of the long-term responses of stream ecosystems to CWD additions are currently ongoing. The most immediate finding is that the CWD dams are still in place 14 years after their initial installation. Other findings will be posted as they become available.
+
{| 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>)
 +
|-
 +
! rowspan="2" | Compound
 +
! colspan="2" | Soil Reporting Limit (mg/kg)
 +
|-
 +
! HPLC (8330)
 +
! GC (8095)
 +
|-
 +
| HMX || 0.04 || 0.01
 +
|-
 +
| RDX || 0.04 || 0.006
 +
|-
 +
| [[Wikipedia: 1,3,5-Trinitrobenzene | TNB]] || 0.04 || 0.003
 +
|-
 +
| TNT || 0.04 || 0.002
 +
|-
 +
| [[Wikipedia: 2,6-Dinitrotoluene | 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
 +
|-
 +
| [[Wikipedia: Dinitrobenzene | DNB ]] || 0.04 || 0.002
 +
|-
 +
| [[Wikipedia: Tetryl | Tetryl ]]  || 0.04 || 0.01
 +
|-
 +
| [[Wikipedia: Pentaerythritol tetranitrate | PETN ]] || 0.2 || 0.016
 +
|}
  
 
==References==
 
==References==
 
+
<references/>
<references />
 
  
 
==See Also==
 
==See Also==
*[https://www.benning.army.mil/Garrison/sustainability/ Sustainability]
+
*[https://itrcweb.org/ Interstate Technology and Regulatory Council]
*[https://www.serdp-estcp.org/Program-Areas/Resource-Conservation-and-Resiliency/Natural-Resources/Watershed-Processes-and-Management/RC-1186 Riparian Ecosystem Management at Military Installations: Determination of Impacts and Restoration and Enhancement Strategies]
+
*[http://www.hawaiidoh.org/tgm.aspx Hawaii Department of Health]
*[https://www.serdp-estcp.org/Program-Areas/Resource-Conservation-and-Resiliency/Infrastructure-Resiliency/Land-Use-and-Carbon-Management/RC-2704 Evaluating the Long-Term Ecological Responses to Riparian Ecosystem Restoration at the Fort Benning, Georgia Military Installation]
+
*[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
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    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
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    See Also