Protecting the environment from contamination
Training with live munitions can potentially contaminate training-range soils. The explosives and propellants used in fired munitions contain compounds, such as TNT, DNT, RDX, and NG, that can be toxic to humans and to the environment. Live-fire training with weapon systems will result in verying amounts of propellant residue, dependingon the system. While high-order detonations leave almost no residue, ineffective detonations can scatter more than half of their explosive fill onto the soil surface in the form of millimeter- to centimeter-sized explosive particles. ERDC’s Cold Regions Research and Engineering Laboratory (CRREL) and Envirostat, Inc. has developed the Multi-Increment Sampling (MIS) technique to more accurately determine the levels of hazardous compounds in range soils.
Multi-increment samples are more representative
The traditional environmental sampling method of taking a few discrete soil samples is not effective when testing ranges because discrete samples do not reflect the varied distribution and composition of explosive and propellant residues in the soil. Samples using the MIS method result in a more representative concentration values for the energetic compounds in the area.
Adapted from methods used in the mining industry, MIS results in a single sample made up of soil taken from evenly distributed locations throughout the area sampled. Individual soil increments of the same geometry and mass are combined and processed to form one sample that represents the mean concentration of energetic compounds occurring throughout the area sampled.
Discrete sampling, which is commonly used on ranges, is less accurate in estimating mean concentration because of the large variation among the samples. In studies taking both discrete and MIS samples from the same site, the discrete samples varied by orders of magnitude whereas the MIS samples varied by less than 30 percent. Quality assurance procedures have also been developed for MIS, which allow the estimation of samplingerror to be calculated. If applied correctly, MIS is the most cost-effective, reproducible and defensible sampling collection methodology that can be implemented.
The effectiveness of MIS depends on collecting the soil increments from the entire area of interest. Fifty (50) or more increments should be collected per sample. Ideally, the increments should be evenly distributed within the area (i.e., be the same distance from each other), be taken from the same depth in the soil, and have a similar size and mass. CRREL developed a sampling tool for the collection of multi-increment samples.
MIS can be used to estimate the concentration of all analytes in most media but was originallly developed to address heterogeneously distributed particle contaninants. Before sampling, it is important to determine data quality objectives and to frame the overall goals of the project. These objectives determine how many increments are required per sample and how many MIS samples are needed to provide the information required to achieve the goals.
ERDC-CRREL has used multi-increment samples to map the distribution and concentration of high explosives in soils at a variety of military ranges, including anti-tank rocket ranges, artillery ranges, and bombing ranges.
MIS is effective in characterizing both active and closed military-range soils. Information of compound concentrations can be used to (1) modify or change the location on active ranges of live-fire training so as to minimize the threat to groundwater or (2) determine if the land on closed ranges can be reused for other purposes or returned to civilian control.
Multi-increment samples have also been used to quantify how much residue is deposited by high- and low- order detonations of single projectiles detonated on snow — a clean collection surface. This information is needed to estimate the mass (load) of energetics being deposited on training ranges and as input to models that predict the likelihood that energetics will be dissolved and transported to groundwater.
ERDC Points of Contact
Questions about Multi-Increment Sampling?
Contact: Marianne E. Walsh, Michael Walsh, Susan Taylor