FORMER BRANDYWINE DRMO YARD
SS-01 

BACKGROUND
The former Brandywine Defense Reutilization and Marketing Office (DRMO) Yard (SS-01) is an inactive facility administratively controlled by Andrews AFB. The 8-acre site is approximately eight miles south-southeast of Andrews AFB in the town of Brandywine, MD. While in operation from 1943-1987, the Brandywine DRMO yard was used for temporary storage of scrap materials and hazardous waste generated from various Department of Defense facilities in the region. 

The primary groundwater contaminant at the former DRMO site is trichloroethylene (TCE), a cleaning solvent. The plume has spread beyond the Air Force property into a residential neighborhood and commercial property. The primary soil contaminant is Polychlorinated Biphenyls (PCBs) and to a lesser extent metals and pesticides. 

In 1994, a remedial action took place to remove the PCB impacted surface soils within the DRMO Yard and in 1996 a groundwater pump and treat system was installed, which is still in operation today. The Environmental Protection Agency (EPA) placed this site on the National Priorities List (NPL) in 1999. While in the process of evaluating the extent of contamination, it was discovered that residents within a quarter-mile of the plume were using shallow groundwater wells for their drinking water source. To be on the safe side, the Air Force converted some homes to public water in 1991. The complex Remedial Investigation was finalized in June 2005. The Feasibility Study was then completed and a Proposed Plan was issued in June 2006, in which the preferred remedy identified was in-situ bioaugmentation and carbon substrate additions with groundwater gradient control. The Interim Record of Decision was authorized in Sept 2006 confirming the selected remedy. 

RISK DRIVERS
Solvents in groundwater extend onto adjacent private property. These include TCE, Tetrachloroethene (PCE), cis-1,2 Dichloroethene (DCE), and vinyl chloride in concentrations above regulatory standards. PCBs, semi-volatile organic compounds (SVOCs,) and metals also extent onto neighboring properties. PCBs were transported by surface water runoff and deposited in drainage swales and a forested wetland area. A response action is necessary to protect human health and the environment. 

PERFORMANCE-BASED APPROACH
The DRMO property has no current or future mission use to Andrews AFB, so efforts are being made to transition this property to future commercial use after the cleanup is complete. Two performance based contracts were awarded in 2006, one which addresses the solvent impacted groundwater, and the other to address the PCB impacted soils. 

For the PCB soil removal in 2007, industrial level clean-up goals will be used within the DRMO property and residential clean-up goals will be used for the railway and private properties. Efforts will be made to protect the trees and their roots within the forested wetland during the soil removal. After the contaminated soils are removed, the area of excavation will be restored to its natural state. 

For the groundwater remediation project starting in 2007, the objective is to prevent exposure to groundwater, vapor emanating from groundwater, and ultimately return it to drinking water standards. Institutional controls are in place to prevent groundwater use within a defined distance from the plume. A proprietary carbon based substrate similar to vegetable oil will be injected into the groundwater, along with a culture known as Dehalococcoides, which consumes the chlorinated solvents in the presence of this carbon substrate. In addition to this biologic degradation, a strategically positioned groundwater remediation system will be installed, managing hydraulic gradient and enhancing aquifer flushing, which will prevent further migration of the plume. 

CHALLENGES
The existing groundwater treatment system is not strategically positioned to prevent plume migration. The high TCE concentrations suggest the presence of droplets or pools of Dense Non-Aqueous Phase Liquid (DNAPL) on a clay layer. Remediation of this source zone presents a significant technical obstacle given the plume extends under multiple private parcels. Long term access to private properties is required, so community involvement is critical. Regulatory agencies have a high level of concern with groundwater contamination under multiple private property parcels. Operation and maintenance of the remediation system is expected to last for many years. Successful transformation of the DRMO property from its current condition to a parcel suitable for future use will require proper planning from the technical and real estate communities
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The proposed schedule for this site is: