Evaluation of Potential for Monitored Natural Attenuation of Perchlorate in Groundwater (Indian Head)

Solutions-IES conducted a demonstration of the potential for Monitored Natural Attenuation (MNA) to be used as a groundwater remedy for perchlorate at a site located on the Naval Surface Warfare Center near Indian Head, MD. The work was funded by the Environmental Security and Technology Certification Program (ESTCP Project ER-0428). The overall objectives of this project were to provide Department of Defense (DoD) managers with the tools needed to: (1) identify sites where MNA may be appropriate for management of perchlorate releases; and (2) demonstrate to regulatory agencies that perchlorate MNA can be effective for controlling adverse impacts to the environment. The project used a tiered approach described by Solutions-IES in a Protocol also prepared as part of this project. The Protocol, titled "Natural Attenuation of Perchlorate in Groundwater: Processes, Tools, and Monitoring Techniques" (ESTCP, 2008), guides the end user through the process of developing multiple lines of evidence to support perchlorate MNA. After a detailed site-selection process, the Indian Head project site was chosen for the demonstration. The Indian Head site consists of approximately 2 acres of grassy land bounded on the east and south by Mattawoman Creek, a large, tidally influenced tributary of the Potomac River. Two buildings are on the site: Building 1419 and a small drum storage building. Building 1419 was once used to clean out or "hog-out" solid propellant containing ammonium perchlorate from various devices, including rockets and ejection seat motors that had exceeded their useful life span. The hog-out process and former waste handling methods impacted the groundwater with elevated concentrations of perchlorate. The groundwater flow direction suggested that perchlorate-contaminated groundwater migrates approximately 460 ft until reaching Mattawoman Creek.