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Stream restoration is often performed to reduce the effects of stressors on the environment and return stream structure and function to pre-disturbance conditions. Often, restoration projects aim to improve water quality and in-stream habitat, manage riparian zones, stabilize stream banks, and allow fish to pass barriers. Stream restorations are commonly carried out across the United States, although very few studies have assessed and monitored the long-term effects of restoration; thus, the outcomes of stream restorations are generally not well documented. Of the many possible stream restoration approaches, one prominent approach in low-gradient, sandy-bottomed streams is the addition of coarse woody debris (CWD) to improve in-stream habitat. In an experimental study summarized here, debris dams were added to 4 streams at Fort Benning Military Installation, Georgia, to mitigate the impacts of military training activities. Results were compared to 4 control streams that were not restored. There were some short-term (< 3 y) changes to stream ecosystem structure and function, but thus far, minimal long-term (~14 y) effects on these streams have been evident.
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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]], [[Dan Isenberg]], [[Sam Bickley]], [[Dr. Brian Helms]], and [[Dr. Jack Feminella]]
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'''CONTRIBUTOR(S):''' [[Dr. Samuel Beal]]
  
'''Key Resource(s)''':
 
*[https://doi.org/10.1126/science.1109769 Synthesizing US River Restoration Efforts]<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>
 
*[[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>
 
*[https://doi.org/10.17226/1807 Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy]<ref name = "NRC1992">National Research Council, 1992. Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy. National Academies Press. [https://doi.org/10.17226/1807 doi: 10.17226/1807]</ref>
 
*[https://doi.org/10.1577/M06-169.1 Global Review of the Physical and Biological Effectiveness of Stream Habitat Rehabilitation Techniques]<ref name= "Roni2008">Roni, P., Hanson, K. and Beechie, T., 2008. Global review of the physical and biological effectiveness of stream habitat rehabilitation techniques. North American Journal of Fisheries Management, 28(3), pp.856-890. [https://doi.org/10.1577/M06-169.1 doi: 10.1577/M06-169.1]</ref>
 
  
==Stream Restoration: Definitions and Scope==
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'''Key Resource(s)''':  
Stream restoration is an overarching term used to describe the process of returning stream structure and function to pre-disturbance conditions<ref name = "NRC1992"/>. This definition of “restoration” differs from “reclamation” and “rehabilitation” in that the latter two terms describe altering a system to meet various human needs<ref name = "NRC1992"/>. Stream restorations often focus on improving the ecological condition within the stream itself, but it is important to recognize that streams are part of larger watersheds, with both upstream-downstream and lateral connections (i.e., to riparian zones and floodplains<ref name = "NRC1992"/>. Therefore, small-scale, in-stream restorations may have little impact if larger-scale impacts (e.g., land disturbances) are not addressed<ref name = "NRC1992"/><ref name= "Craig2008"/> Craig, L.S., Palmer, M.A., Richardson, D.C., Filoso, S., Bernhardt, E.S., Bledsoe, B.P., Doyle, M.W., Groffman, P.M., Hassett, B.A., Kaushal, S.S. and Mayer, P.M., 2008. Stream restoration strategies for reducing river nitrogen loads. Frontiers in Ecology and the Environment, 6(10), pp.529-538. [https://doi.org/10.1890/070080 doi: 10.1890/070080]</ref><ref name= "Roni2008"/><ref name= "Bernhardt2011>Bernhardt, E.S. and Palmer, M.A., 2011. River restoration: the fuzzy logic of repairing reaches to reverse catchment scale degradation. Ecological applications, 21(6), pp.1926-1931. [https://doi.org/10.1890/10-1574.1 doi: 10.1890/10-1574.1]</ref>. Instead, watershed-scale approaches focusing on improving land management practices within the watershed and also applying multiple, complementary stream and riparian restoration approaches have been recommended<ref name = "NRC1992"/><ref name = "Palmer2005">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><ref name= "Craig2008"><ref name= "Bernhardt2011/>).
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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>
  
As an example, Roni et al. (2002)<ref name= "Roni2002">Roni, P., Beechie, T.J., Bilby, R.E., Leonetti, F.E., Pollock, M.M. and Pess, G.R., 2002. A review of stream restoration techniques and a hierarchical strategy for prioritizing restoration in Pacific Northwest watersheds. North American Journal of Fisheries Management, 22(1), pp.1-20. [https://doi.org/10.1577/1548-8675(2002)022<0001:AROSRT>2.0.CO;2 doi: 10.1577/1548-8675(2002)022<0001:AROSRT>2.0.CO;2]</ref> presented a hierarchical approach for restoration, with this approach specifically developed for improving fish habitat in forests and rangelands. They suggested that managers prioritize protecting intact (i.e., non-degraded) stream reaches that have high-quality habitat for fishes. Subsequent efforts should then focus on reconnecting high-quality habitats that have been disconnected hydrologically, followed by restoring ecosystem processes (e.g., restoring riparian processes by livestock exclusion), and lastly focusing on improving in-stream habitat through habitat augmentation practices (e.g., large wood or boulder additions).
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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)]]
  
==Stressors to stream ecosystems that motivate restoration==
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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>.
Headwater streams are important components of river networks and, like most waterways, they are also vulnerable 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>. Further, the hydrologic connectivity of river networks means that 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>. Thus, minimizing human impacts in headwater streams is important not only for protecting these ecosystems and their biodiversity but also because of the multiple services they provide to downstream ecosystems (e.g., water for drinking, bathing, recreation, consumption of fish, etc.).
 
  
A survey of stream restorations in the southeastern US revealed that environmental degradation, mitigation, and public safety were the main factors motivating stream restorations<ref name= "Sudduth2007">Sudduth, E.B., Meyer, J.L. and Bernhardt, E.S., 2007. Stream restoration practices in the southeastern United States. Restoration Ecology, 15(3), pp.573-583. [https://doi.org/10.1111/j.1526-100X.2007.00252.x doi: 10.1111/j.1526-100X.2007.00252.x]</ref>. Environmental stressors include changes in land use (e.g., forestland conversion) and hydrology (e.g., water withdrawals) in the surrounding watershed<ref>Stanford, J.A., Ward, J.V., Liss, W.J., Frissell, C.A., Williams, R.N., Lichatowich, J.A. and Coutant, C.C., 1996. A general protocol for restoration of regulated rivers. Regulated Rivers: Research & Management, 12(4‐5), pp.391-413. [https://doi.org/10.1002/(SICI)1099-1646(199607)12:4/5<391::AID-RRR436>3.0.CO;2-4 doi: 10.1002/(SICI)1099-1646(199607)12:4/5<391::AID-RRR436>3.0.CO;2-4]</ref><ref name= "Bernhardt2011/>. These factors, in turn, can reduce water quality, alter water quantity, degrade in-stream habitat and associated aquatic biodiversity, and alter availability and quality of food resources for biota (e.g., organic matter inputs<ref name = "NRC1992"/>). Therefore, the five most common goals of stream restoration projects are:
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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>
  
*improve water quality;
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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).
*manage riparian zones;
 
*improve in-stream habitat;
 
*allow for fish passage and  
 
*stabilize stream banks<ref name= "Bernhardt2005"/>
 
  
==Restoration goals and assessment of efficacy: the importance of monitoring==
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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"/>.
Identification of a restoration project’s mission, goals, and objectives is necessary in order to evaluate the ecological success of that restoration<ref name = "NRC1992"/><ref name = "Palmer2005"/>. Central to this approach is the implementation of pre-restoration and post-restoration monitoring at appropriate spatial and temporal scales<ref name = "NRC1992"/><ref name = "Palmer2005"/>. Despite the large number of restorations that have taken place at a combined cost of >$1 billion per year in the United States<ref name= "Bernhardt2005"/>, effects of stream restorations are poorly documented because of extremely limited post-restoration monitoring<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= "Roni2008"/><ref name= "Bernhardt2011/>). It is estimated that only 10% of stream restorations are monitored or assessed after implementation<ref name= "Bernhardt2005"/>. In an analysis of 345 stream restoration studies<ref name= "Roni2008"/> found that conclusions on the effectiveness of restoration could not be drawn because of limited data on physical, chemical, and biological criteria collected primarily over short post-restoration time periods. For example, studies suggest that in-stream habitat modification can improve salmonid fish habitat and abundance, although the lack of statistically rigorous design, and high variability in responses with different in-stream restoration structures and different species make broad conclusions about efficacy difficult<ref name= "Roni2008"/>. It is not possible for many restoration studies to include monitoring in their projects due to funding limitations<ref name= "Sudduth2007"/>, but it is suggested those that can should adopt standard monitoring methods incorporating both stream structure and function responses, with measurements collected over long periods of time and across a wide range of environmental conditions (e.g., flood and drought years)<ref name = "Palmer2005"/><ref name= "Bernhardt2005"/><ref name = "Wohl2005>Wohl, E., Angermeier, P.L., Bledsoe, B., Kondolf, G.M., MacDonnell, L., Merritt, D.M., Palmer, M.A., Poff, N.L. and Tarboton, D., 2005. River restoration. Water Resources Research, 41(10). [https://doi.org/10.1029/2005WR003985 doi: 10.1029/2005WR003985]</ref><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>). Furthermore, measured environmental responses should be compared to multiple reference sites (minimally impacted systems of a similar stream order and in the same ecoregion as the restored site) in order to fully assess restoration efficacy<ref name = "Palmer2005"/>.
 
  
==Stream restoration techniques==
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{| class="wikitable" style="float: right; text-align: center; margin-left: auto; margin-right: auto;"
By their very nature, streams and rivers are dynamic ecosystems; thus, restoration efforts should focus on strategies designed to integrate dynamic physicochemical and biological processes<ref name = "NRC1992"/><ref name = "Palmer2005"/><ref name = "Thompson2005">Thompson, D.M., 2005. The history of the use and effectiveness of instream structures in the United States. Humans as Geologic Agents, 16, p.35. [https://doi.org/10.1130/2005.4016(04) doi: /10.1130/2005.4016(04)]</ref><ref name = "Wohl2005/><ref name= "Bernhardt2011/>). For example, restoration objectives focused on re-establishing a dynamic stream ecosystem may include restoring natural sediment dynamics and water flow, restoring natural riparian plant communities, and restoring natural channel configurations<ref name = "NRC1992"/>.  
+
|+ 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.)
 
+
|-
When selecting a target site for restoration, it is suggested that watershed assessments be conducted to determine appropriate locations. In practice, however, target sites are most often selected because land is available for restoration<ref name= "Sudduth2007"/>. It is important to note that if one restoration technique is conducted in multiple locations, the response of a system to restoration may not be the same because of site- and region-specific differences in geology, land use, climate, and biogeographic history<ref name = "Palmer2005"/><ref name = "Wohl2005/>. For example, an analysis of 24 restoration projects found that stream restorations were more successful in improving stream macroinvertebrate communities when the restorations were conducted closer to intact forests, which provided a source of invertebrates to recolonize restored sites<ref>Sundermann, A., Stoll, S. and Haase, P., 2011. River restoration success depends on the species pool of the immediate surroundings. Ecological Applications, 21(6), pp.1962-1971. [https://doi.org/10.1890/10-0607.1 doi: 10.1890/10-0607.1]</ref>.
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! Military Range Type !! Analyte !! Range<br/>(mg/kg) !! Median<br/>(mg/kg) !! RSD<br/>(%)
 
+
|-
{| class="wikitable" style="float:right; margin-left: 20px;"
+
| colspan="5" style="text-align: left;" | '''Discrete Samples'''
|+ Table 1. Categories of Stream Restoration (NRC 1992)
 
 
|-
 
|-
| Bank stabilization
+
| Artillery FP || 2,4-DNT || <0.04 – 6.4 || 0.65 || 110
 
|-
 
|-
| Channel modification
+
| Antitank Rocket || HMX || 5.8 – 1,200 || 200 || 99
 
|-
 
|-
| Fish reintroduction
+
| Bombing || TNT || 0.15 – 780 || 6.4 || 274
 
|-
 
|-
| Flow augmentation
+
| Mortar || RDX || <0.04 – 2,400 || 1.7 || 441
 
|-
 
|-
| Organic matter addition
+
| Artillery || RDX || <0.04 – 170 || <0.04 || 454
 
|-
 
|-
| Revegetation of banks and riparian zones
+
| colspan="5" style="text-align: left;" | '''Incremental Samples*'''
 
|-
 
|-
| Land use regulation
+
| Artillery FP || 2,4-DNT || 0.60 – 1.4 || 0.92 || 26
 
|-
 
|-
| Soil stabilization
+
| Bombing || TNT || 13 – 17 || 14 || 17
 
|-
 
|-
| Water quality improvements
+
| Artillery/Bombing || RDX || 3.9 – 9.4 || 4.8 || 38
 +
|-
 +
| Thermal Treatment || HMX || 3.96 – 4.26 || 4.16 || 4
 
|-
 
|-
| Water temperature alteration
+
| colspan="5" style="text-align: left; background-color: white;" | * For incremental samples, 30-100 increments and 3-10 replicate samples were collected.
 
|}
 
|}
  
There are many types of stream restoration techniques that have been applied, and the type of restoration(s) can depend on the size and extent of the stressor, predominant land use in the watershed, position of the stream within the watershed, and the goals and objectives of the stakeholders<ref name = "NRC1992"/><ref name= "Bernhardt2005"/><ref name = "Palmer2005"/>. Stream restoration goals and techniques are too numerous to discuss succinctly here (see Table 1). As one example, the five most common restoration techniques to improve habitat for salmonid fishes include habitat reconnection, road improvement, riparian management, in-stream habitat improvement, and nutrient enrichment<ref name= "Roni2002"/>.  
+
==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<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: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]]
  
One common restoration technique is the addition of coarse woody debris (CWD) to stream channels. CWD additions are a low-cost method to improve in-stream habitat<ref name= "Bernhardt2005"/>. In practice, nearby riparian trees are felled, cut, and staked in place within the stream channel. CWD additions can exert several positive effects on stream ecosystems including altering morphology and hydraulics of stream channels, creating habitat for benthic macroinvertebrates and fish, providing colonization surfaces for algae and other microorganisms, and increasing retention of sediment and organic matter, the latter of which is an important basal resource for many stream organisms<ref>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><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">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><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>. Therefore, CWD additions have been used to improve in-stream habitat for aquatic organisms, primarily fish<ref name= "Roni2002"/>, and also, have been identified as a strategy to improve in-stream nitrogen retention<ref name= "Roberts2007"/><ref name= "Craig2008"/>. However, a lack of comprehensive monitoring data has limited the ability to thoroughly evaluate the efficacy of this technique<ref name = "Thompson2005"/>. For example, Roni et al. (2002)<ref name= "Roni2002"/> found that 41% of in-stream habitat improvement studies in the Pacific Northwest increased juvenile salmonid abundance; however, only about 20% of these studies quantified responses for >5 y, and responses varied across the restoration techniques examined<ref name= "Roni2002"/>.  
+
DUs can vary in shape (Figure 4), size, number of increments, and number of replicates according to a project’s data quality objectives.
  
==Case study: Assessment of in-stream restoration on DoD land at Fort Benning Military Installation==
+
[[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)]]
At Fort Benning Military Installation (FBMI), military training activities (i.e., dismounted infantry tactics, tracked vehicle maneuvers) on sandy upland soils have led to erosion and high sedimentation rates in streams<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"/>. Specifically, streams at FBMI with higher watershed disturbance (defined as the % of the watershed with bare ground on slopes >5%) were found to have impaired water quality and reduced ecosystem function<ref name= "Houser2005"><ref>Mulholland, P.J., Houser, J.N. and Maloney, K.O., 2005. Stream diurnal dissolved oxygen profiles as indicators of in-stream metabolism and disturbance effects: Fort Benning as a case study. Ecological Indicators, 5(3), pp.243-252. [https://doi.org/10.1016/j.ecolind.2005.03.004 doi: 10.1016/j.ecolind.2005.03.004]</ref><ref name= "Roberts2007"/>. Therefore, an experimental restoration pilot project (i.e., CWD additions) was implemented in 2003 at FBMI to reduce the effects of military activities on stream ecosystem processes.
 
  
Both the short-term and long-term effects of CWD addition on stream ecosystem structure and function were evaluated in multiple highly disturbed streams at FBMI. The first project compared stream ecosystem processes before (2001-2003) and after (2003-2006) addition of CWD dams to stream channels. The second project examined responses 14 years after CWD additions (2017-2019) to determine whether there were any long-term benefits of CWD additions on in-stream stream structure and function.
+
==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<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.
  
===CWD additions at FBMI===
+
[[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>]]
CWD additions were installed in four headwater streams within Ft. Benning’s boundaries as part of a previously funded SERDP project<ref name= "Mulholland2007"/>. Riparian trees (blackgum [''Nyssa sylvatica''] or white oak [''Quercus alba'']) were used for the CWD additions. Trees were felled on-site in August 2003, cut to the desired length, and then left on land to dry for 2-3 months prior to installation in the stream. In October 2003, cut trees (~10-20 cm in diameter, 1-2 m in length) were added in a “Z” configuration along a 100-150 m section within each stream (Figure 1). Three cut tree sections were used to make the “Z” design, with 10 to 15 of these “Z”-shaped woody debris dams installed along each stream length (~10 m apart), anchored in place using rebar stakes driven into the stream bed. The “Z” configuration was used to increase retention of organic matter and slow water flow to promote a stable stream bed. CWD additions approximately doubled the amount of in-stream CWD in restored streams<ref name= "Mulholland2007"/>.
 
  
One issue that was encountered several months after the CWD additions was that excessive sedimentation from storm events led to the burial of much of the added CWD in two of the four restored streams (Figure 2). Sedimentation and burial were 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, and stream flow was 5-8 times higher in the post-restoration period than the pre-restoration period<ref name= "Mulholland2007"/>. Because of the CWD burial, the original CWD additions were augmented with a second addition of wood in 2004, such that the CWD coverage in these two streams was then triple the pre-restoration amount<ref name= "Mulholland2007"/>. Burial of CWD dams was assessed in 2005 and 30% to 75% of the debris dams were buried in the restored streams.
+
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<ref>Walsh, M.R., 2009. User’s manual for the CRREL Multi-Increment Sampling Tool. Engineer Research and Development Center / Cold Regions Research and Engineering Lab (ERDC/CRREL) SR-09-1, Hanover, NH, USA.  [[media:Walsh-2009 ERDC-CRREL SR-09-1.pdf | Report.pdf]]</ref>.
 +
 
 +
==Sample Processing==
 +
While only 10 g of soil is typically used for chemical analysis, incremental sampling generates a sample weighing on the order of 1 kg. Splitting of a sample, either in the field or laboratory, seems like an easy way to reduce sample mass; however this approach has been found to produce high uncertainty for explosives and propellants, with a median RSD of 43.1%<ref name= "Hewitt2009"/>. Even greater error is associated with removing a discrete sub-sample from an unground sample. Appendix A in [https://www.epa.gov/sites/production/files/2015-07/documents/epa-8330b.pdf U.S. EPA Method 8330B]<ref name= "USEPA2006M"/> provides details on recommended ISM sample processing procedures.
 +
 
 +
Incremental soil samples are typically air dried over the course of a few days. Oven drying thermally degrades some energetic compounds and should be avoided<ref>Cragin, J.H., Leggett, D.C., Foley, B.T., and Schumacher, P.W., 1985. TNT, RDX and HMX explosives in soils and sediments: Analysis techniques and drying losses. (CRREL Report 85-15) Hanover, NH, USA. [[media:Cragin-1985 CRREL 85-15.pdf| Report.pdf]]</ref>. Once dry, the samples are sieved with a 2-mm screen, with only the less than 2-mm fraction processed further. This size fraction represents the USDA definition of soil. Aggregate soil particles should be broken up and vegetation shredded to pass through the sieve. Samples from impact or demolition areas may contain explosive particles from low order detonations that are greater than 2 mm and should be identified, given appropriate caution, and potentially weighed.
 +
 
 +
The <2-mm soil fraction is typically still ≥1 kg and impractical to extract in full for analysis. However, subsampling at this stage is not possible due to compositional heterogeneity, with the energetic compounds generally present as <0.5 mm particles<ref name= "Walsh2017"/><ref name= "Taylor2004"/>. Particle size reduction is required to achieve a representative and precise measure of the sample concentration. Grinding in a puck mill to a soil particle size <75 µm has been found to be required for representative/reproducible sub-sampling (Figure 8). For samples thought to contain propellant particles, a prolonged milling time is required to break down these polymerized particles and achieve acceptable precision (Figure 9). Due to the multi-use nature of some ranges, a 5-minute puck milling period can be used for all soils. Cooling periods between 1-minute milling intervals are recommended to avoid thermal degradation. Similar to field sampling, sub-sampling is done incrementally by spreading the sample out to a thin layer and collecting systematic random increments of consistent volume to a total mass for extraction of 10 g (Figure 10).
 +
 
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig6.png|thumb|200 px|Figure 6: CMIST soil sampling tool (top) and with ejected increment core using a large diameter tip (bottom).]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig7.png|thumb|200 px|Figure 7: Two person sampling team using CMIST, bag-lined bucket, and increment counter. (Photos: Matthew Bigl)]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig8.png|thumb|200 px|Figure 8: Effect of machine grinding on RDX and TNT concentration and precision in soil from a hand grenade range. Data from Walsh et al.<ref>Walsh, M.E., Ramsey, C.A. and Jenkins, T.F., 2002. The effect of particle size reduction by grinding on subsampling variance for explosives residues in soil. Chemosphere, 49(10), pp.1267-1273. [https://doi.org/10.1016/S0045-6535(02)00528-3 doi: 10.1016/S0045-6535(02)00528-3]</ref> ]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig9.png|thumb|200 px|Figure 9: Effect of puck milling time on 2,4-DNT concentration and precision in soil from a firing point. Data from Walsh et al.<ref>Walsh, M.E., Ramsey, C.A., Collins, C.M., Hewitt, A.D., Walsh, M.R., Bjella, K.L., Lambert, D.J. and Perron, N.M., 2005. Collection methods and laboratory processing of samples from Donnelly Training Area Firing Points, Alaska, 2003 (No. ERDC/CRREL-TR-05-6). [[media:Walsh-2005 ERDC-CRREL TR-05-6.pdf| Report.pdf]]</ref>.]]</li>
 +
<li style="display: inline-block;">[[File:Beal1w2 Fig10.png|thumb|200 px|center|Figure 10: Incremental sub-sampling of a milled soil sample spread out on aluminum foil.]]</li>
 +
 
 +
==Analysis==
 +
Soil sub-samples are extracted and analyzed following [[Media: epa-2006-method-8330b.pdf | EPA Method 8330B]]<ref name= "USEPA2006M"/> and [[Media:epa-2007-method-8095.pdf | Method 8095]]<ref name= "USEPA2007M"/> using [[Wikipedia: High-performance liquid chromatography | High Performance Liquid Chromatography (HPLC)]] and [[Wikipedia: Gas chromatography | Gas Chromatography (GC)]], respectively. Common estimated reporting limits for these analysis methods are listed in Table 2.
 +
 
 +
{| class="wikitable" style="float: center; text-align: center; margin-left: auto; margin-right: auto;"
 +
|+ Table 2. Typical Method Reporting Limits for Energetic Compounds in Soil. (Data from Hewitt et al.<ref>Hewitt, A., Bigl, S., Walsh, M., Brochu, S., Bjella, K. and Lambert, D., 2007. Processing of training range soils for the analysis of energetic compounds (No. ERDC/CRREL-TR-07-15). Hanover, NH, USA. [[media:Hewitt-2007 ERDC-CRREL TR-07-15.pdf| Report.pdf]]</ref>)
 +
|-
 +
! 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://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