The U.S. Army Corps of Engineers (USACE), Baltimore District is studying ways to improve the property formerly used by the Department of Defense in the 1950s, previously known as the Manassas Air Force Communications Facility (MAFCF). The area is now the southern portion of the Prince William County Public Schools property located in Independent Hill, VA. USACE is initiating a remedial design (RD) for remedial action (RA) to cleanup groundwater contamination associated with past military activity (see Site History below).

In August 2013, USACE completed a risk assessment to determine if remaining contaminants from past government use posed any hazards. The assessment showed there are no risks from site contaminants to students and staff in the northern part of the site where the Independence Nontraditional School is located (presentation slide 11).

However, elevated concentrations of contaminants (presentation slide 12) were detected in groundwater in the southern portion of the site. It is important to clarify this groundwater is not used for drinking water and there is no direct pathway between the public and the contaminated groundwater. This groundwater contamination could affect construction workers under very specific circumstances. A worker would have to spend four hours a day, 125 days a year, for a year working in a very confined trench to potentially experience any health risks.

USACE conducted a supplemental site characterization from 2015 to 2018 to help outline the best course of action to clean up the remaining groundwater contamination in the southern part of the site. Using the results from this investigation, USACE developed remedial alternatives to remediate the groundwater at MAFCF (presentation slide 14).

USACE, in coordination with the Virginia Department of Environmental Quality, will treat the contaminated groundwater to reduce future risks. This is to be done through a combination of in situ chemical oxidation (ISCO) and in situ enhanced bioremediation (ISEB) to address the contamination in the groundwater. This is to be completed by injecting materials into the groundwater that will treat the contamination. Within nested/flush mounted groundwater wells onsite, ISCO would be used to treat the source areas by injecting chemical oxidants into the bulk of the contamination. ISEB would subsequently be used to treat groundwater contamination further away from the source area by injecting natural materials to promote environmental conditions necessary for biodegradation of contaminants.

The former MAFCF was used as an aircraft control and warning station in the Air Defense Command Radar Network from 1952 to 1959. The site is located on State Route 619 at its intersection with State Route 646 in Prince William County, Virginia, approximately 11 miles southwest of Manassas (presentation slide 2).

The Department of Defense (DoD) declared the installation excess to the needs of the Air Force in 1964. The Air Force transferred approximately 4 acres to the Department of the Army in 1966. In 1968, the government deeded approximately 45 acres in fee-owned land and 32 buildings to the Prince William County School Board.

In 1986, the Virginia Department of Waste Management performed an assessment of the former drinking water production wells where petroleum and chlorinated solvents were detected in sample results. This assessment showed that trichloroethylene (TCE) and perchloroethylene (PCE) had been found in the groundwater. As a result, the Prince William County School Board abandoned the water system and tied into the county water system.

In 1987, USACE conducted a confirmation study of the groundwater and determined that the 45 acres fee-owned portion of this parcel was formerly owned and used by the DoD. This made it eligible for the Defense Environmental Restoration Program, Formerly Used Defense Site Program.

Once USACE established the property as a Formerly Used Defense Site, the project team started conducting a series of studies to determine if contamination associated with former DoD use is present above the Virginia Department of Environmental Quality standards.