Defense installations contain millions of acres of land that need to be screened for explosives-related compound (ERC) contamination. Current methods such as EPA Method 8330 are expensive, time-consuming, and often unsatisfactory due to the heterogeneous spatial distribution and large areas of energetic compounds and sensitivity limits of traditional equipment. New sampling and analysis equipment is needed to more cost-effectively determine the extent of contamination.
The objective of this project was to develop innovative methods for the rapid screening of large areas containing energetic materials at low cost and with high confidence. Specific objectives included: (1) exploit existing amplifying fluorescent polymer (AFP) technology for the wide-area detection of energetic compounds and (2) develop standoff detection methods based on the AFP technology.
The AFP technology used in the Nomadics FIDO sensor for landmine detection can detect extremely small masses of TNT and related explosive compounds. In this project, direct vapor sampling with the FIDO detector was combined with a novel soil collection technique. Using a proprietary electrostatic precipitator, fine particulate matter is quickly collected from the soil surface. The FIDO sensor then analyzes these samples and determines contaminant levels. For standoff detection, small polymer beads are coated with AFP and a marker dye and distributed across the area to be assessed.
During tests conducted at Yuma Proving Ground, Arizona, areas with bulk TNT contamination were differentiated from areas contaminated at trace levels. Areas that were not contaminated with explosives gave little to no response. The relationship between soil energetic compound contamination and the concentrations of these compounds in the vapor phase, however, is complex. Factors such as heterogeneously distributed soil moisture and surface temperature are likely to make accurate determinations difficult. Although the method may not provide the same level of accuracy as laboratory analytical methods, it may provide order-of-magnitude estimates of contamination at a given site. Laboratory demonstration of the standoff detection method was successful, but numerous technical challenges prevented demonstrating it outdoors. Work is under way to develop new AFPs for detection of RDX and HMX.
This sampling method serves as an area reduction tool, enabling differentiation of uncontaminated areas from those that are impacted. The cost of analysis per sample is also much less than currently accepted laboratory methods. Finally, since samples are analyzed in the field, the turn-around time for results is minimized, enabling rapid decisions related to the level of contamination and follow-up field investigation and range management activities.