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 to the DSB Task Force report and recent congressional interest, ESTCP designed a WAA pilot program that consists of demonstrations at multiple sites to validate the application of a number of recently developed and validated technologies as a comprehensive approach to WAA. These demonstrations of WAA technologies include deployment of high airborne sensors, helicopterborne magnetometry arrays and ground surveys.
This project demonstrated light detection and ranging (LiDAR) and orthophotography high airborne sensor technologies demonstrated at Pueblo Precision Bombing Range (PBR) #2 in Otero County, Colorado, and at Borrego Military Wash in southern California. LiDAR data are critical to the overall WAA process in the creation of an accurate high-resolution bare earth digital elevation model (DEM) for ortho-correction of all other remote-sensing datasets. LiDAR and orthophotography are both valuable for the identification and delineation of possible surface munitions-related features such as target circles and craters associated with munitions use at the site and for development of base mapping layers for site visualization, planning, and analysis.
The objectives of WAA include the rapid and efficient identification of areas of concentrated munitions use through the application of site characterization technologies. Information provided in historical records forms the basis for initial site assessments; field surveys employing a suite of technologies and processing techniques develops the knowledge of these sites and can provide information needed to support decisions at various stages of the munitions response process. Equally as important as defining areas of munitions contamination is the definition of areas with no indication of munitions contamination. The evidence derived from these data analyses assists in prioritizing remediation activities by providing a means for assessing the level of confidence in conclusions about munitions contamination at a site.
The LiDAR and orthophotography demonstrations were conducted to determine the utility of these datasets to identify munitions-related features, including target areas, craters, and range infrastructure features; to determine the accuracy of the datasets; and to acquire the datasets for site characterization and planning. For the Pueblo PBR #2 site, specific objectives included confirmation and delineation of the approximate boundaries of two documented bombing targets (Bombing Targets #3 and #4 [BT3 and BT4]) and a suspected 75-mm air-to-ground target area. At the Borrego Military Wash demonstration area, the specific objectives included confirmation and delineation of the two targets identified in the Archive Search Report (ASR) and determination of whether evidence exists of any previously unknown target areas.
Data collection for the Pueblo PBR #2 demonstration took place in two phases: Phase I in 2004, which covered 2,224 acres within the overall 7,500-acre WAA site, and Phase II in 2005, which covered the remaining 5,276 acres of the study area. For both Phases I and II data collections, the expected spatial accuracies were achieved for both the LiDAR and orthophotography datasets. Upon analysis of the processed datasets, targets, craters, and range infrastructure features were detected.
Data collection for the demonstration at the Borrego demonstration site took place in August of 2005. The expected spatial accuracies were compromised due to site restrictions on the emplacement of ground fiducials. Upon analysis of the processed datasets, targets and range infrastructure features were detected and the results compared to ground survey data collected by USACE for validation. Although the performance objectives were not all met for the demonstration, the use of LiDAR and orthophotography technologies did confirm the presence of features requiring further investigation and geolocated these features more accurately than had previously been documented. The demonstration showed that erosion and deposition can impact the persistence of detectable features over time; therefore, the potential effect of climactic conditions should be taken into account in assessing site suitability for LiDAR and orthophotography.
Overall, LiDAR and orthophotography technologies are efficient, cost-effective tools for WAA. As the first part of an integrated WAA investigation, the collection of thousands of acres of data per day and the analysis of LiDAR and orthophotography datasets yields results that can be used to characterize the extent of contaminated areas and delineate “clear” areas of large sites. The utilization of these technologies for WAA will result in a reduction in the overall costs of remediation by decreasing the number of acres requiring more extensive munitions response actions and focusing the extent of further investigations, ultimately yielding more efficient use of the DoD’s limited cleanup resources.
The primary benefit of these high-altitude technologies are the rapid characterization of large open areas. Cost analysis shows that, in general, costs per acre decrease with the increase in size of the project area. However, complex sites (e.g., densely vegetated or topographically steep and variable landscapes) requiring extended labor in data processing and analyses, or complicated data collection surveys (due to inclement weather, climatic conditions, logistical difficulties, etc.) can increase the per unit costs.