Munitions and explosives of concern (MEC) contamination is a high priority problem for the Department of Defense (DoD). Recent DoD estimates of MEC contamination across approximately 1,400 DoD sites indicate that 10 million acres are suspected of containing MEC. Because many sites are large in size (greater than 10,000 acres), the investigation and remediation of these sites could cost billions of dollars. However, on many of these sites only a small percentage of the site may in fact contain MEC contamination. Therefore, determining applicable technologies to define the contaminated areas requiring further investigation and munitions response actions could provide significant cost savings. Therefore, the Defense Science Board (DSB) has recommended further investigation and use of wide area assessment (WAA) technologies to address the potential these technologies offer in terms of determining the actual extent of MEC contamination on DoD sites. In response, ESTCP designed a WAA pilot program that consisted of demonstrations at multiple sites to validate the application of a number of technologies as a comprehensive approach to WAA.
The objective of this project was to demonstrate Light Detection and Ranging (LiDAR), orthophotography, synthetic aperture radar (SAR) and hyperspectral imaging (HSI) to determine the spatial distribution of uncontaminated areas versus concentrated contamination and to plan ground remediation efforts accordingly as part of the ESTCP WAA pilot program.
WAA technology demonstrations for this project were conducted at Pueblo Precision Bombing Range #2, Colorado and Borrego Military Wash, California (LiDAR and orthophotography only). LiDAR and orthophotography were successful in detecting craters, aiming circles, and other large munitions-related features constructed from earthen berms. Overall, target features were best-defined in the LiDAR data compared to the orthophotography data. SAR showed the capability of detecting relatively large metallic items on the surface of the ground and unshielded by foliage but with a high false alarm rate. Detection was less reliable on items with volumes of less than a few liters. HSI proved unable to detect metallic fragments on the ground and was less successful at detecting munitions-related features than had been hoped. It did prove successful in reducing SAR false alarms due to vegetation.
The primary benefit of WAA technology is in rapid characterization of large open areas. LiDAR and orthophotography provide a valuable layer of evidence that can both support and add to initial knowledge about a site.
SAR is most applicable to sites with fairly large munitions or munitions scrap on the ground surface. SAR readily detects vertical vegetation, such as trees and bushes, which results in a large number of false alarms. In addition, SAR needs to be used in conjunction with a suite of WAA sensors for target and clutter discrimination to reduce the false alarm rate.
HSI requires significant post-processing of the raw data to produce useful outputs. In addition, the large number of spectral bands recorded results in extremely large data sets, and this can limit the spatial resolution that is practical.