DEFENSE GENERAL SUPPLY CENTER (DLA)
CHESTERFIELD COUNTY, VA
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The 640-acre Defense Supply Center (DLA) site is an active federal facility in Chesterfield County, Virginia, about eight miles south of Richmond. A Defense Logistics Agency supply center has operated on site since 1941. Past operations on site include aviation equipment manufacturing and repair, firefighter training, and the use and storage of hazardous materials. Chemical operations have included storing and shipping flammable, toxic, corrosive and oxidizing chemicals as well as pesticides. In the 1960s and early 1970s, the Defense General Supply Center disposed of some waste material in a shallow ravine called the Area 50 Landfill. These activities contaminated soil, sediment and groundwater with hazardous chemicals. Under the federal facility agreement for the site, cleanup has been divided into several different parts, called operable units (OUs), to best address different areas of contamination. Remedies for many of the OUs are in place. Remedy selection for remaining OUs is underway.
What Has Been Done to Clean Up the Site?
Remedial actions completed to date include land use controls; soil and asphalt covers for contaminated areas; monitored natural attenuation of groundwater contaminants; enhanced bioremediation of contaminated groundwater; groundwater monitoring; vegetative covers; and excavation and off-site disposal of contaminated soil. Remedy construction began in 1993 and is ongoing.
The Site consists of approximately 640 acres that have been used as a Defense Logistics Agency supply center since 1941. Past operations conducted on-site include aviation equipment manufacturing and repair, firefighter training, and the use and storage of hazardous materials. Current industrial operations include refurbishing helmets and steel compressed gas cylinders using dry (ball blasting) processes and tent fabrication and repair. Chemical operations at the Site have included storing and shipping flammable, toxic, corrosive, and oxidizer chemicals as well as pesticides. In the 1960s and early 1970s, DSCR disposed of some of their waste material in a shallow ravine called the Area 50 Landfill. In the 1980s, groundwater contaminated primarily with volatile organic compounds (VOCs) was detected downgradient of the landfill, and the Site was placed on the National Priorities List of hazardous waste sites.
Under the Federal Facility Agreement for this Site, the cleanup has been divided into separate parts, called operable units (OUs). There are a total of 13 OUs at DSCR; nine are source (soil) areas, three are groundwater OUs and there is one groundwater interim action OU. Remedies for eight of the nine soil OUs have been completed; OU 13 is the remaining soil OU to be addressed. While a remedy is in place for groundwater OU 8, this remedy changed to a more active treatment as documents in the September 2011 Explanation of Significant Differences (ESD).
- The Open Storage Area (OU 1) was historically used for storage and recoupment activities. An interim Record of Decision (ROD) was signed in 1992; a revised Human Health Baseline Risk Assessment (HHBRA) and an Explanation of Significant Differences (ESD) was issued in 2007. The remedy consists of Land Use Controls (LUCs) and annual inspections.
- Area 50 Landfill (OU 2) was formerly used to dispose of chemicals and construction debris. The ROD was signed in 2008 and the remedy consisted of a soil cover and LUCs. The RACR was finalized in June 2010.
- The soil within the National Guard Area (OU 3) was impacted by vehicle maintenance and degreasing activities. The remedy, documented in the 1995 ROD, consisted of an asphalt cover and LUCs.
- The soil at OU 4, the Former Fire Training Area, was found to need no further action (NFA) and the ROD was signed in 1999.
- The Acid Neutralization Pit area (OU 5) consists of two former concrete settling tanks, used for the neutralization of acidic wastewater from metal cleaning and painting operations. The ROD was signed in 1992 and identified the use of a soil vapor extraction (SVE) system to reduce remaining VOC concentrations to below the soil remediation objective. However, upon further investigation using a pilot study, a full-scale SVE system was decided to be unnecessary and an ESD was signed in 1995. The ESD recommended no further action be required. The pits have been covered with concrete and LUCs are in place to limit future land use.
- OU 6 consists of the groundwater contamination plume underneath OUs 1, 2 and 3. Contaminants of Potential Concern (COPCs) primarily include chlorinated VOCs. Bioremediation treatability studies have been performed in four source areas.
- OU 7 consists of the groundwater contamination plume beneath OUs 4 and 13. Similar to OU 6, the COPCs include chlorinated VOCs and bioremediation treatability studies have been performed at three source areas.
- The groundwater underneath OU 5 is being addressed as OU 8, which is a chlorinated VOC plume. The ROD was signed in 2007 and the remedy consists of monitored natural attenuation (MNA), with an in-situ bioremediation contingency. An ESD to document a shift to the contingency remedy was finalized in September 2011. Biannual (March and September) groundwater monitoring in accordance with the ROD and remedial design are ongoing.
- OU 9 includes the interim remedy for OU 6, which was finalized through an interim action ROD in 1993. The action consisted of a groundwater extraction and air-stripping system to reduce mass and limit further transport of impacted groundwater off-site. A rebound test of the treatment system revealed the operation of the system was not necessary and an amendment to the interim ROD authorizing the decommissioning of the system was signed in 2008. The final remedial action for the OU 9 groundwater plume will be addressed through the action taken at OU 6.
- The former Building 68 area (OU 10) was historically used as a pesticide storage building. The remedy documented in the 2007 ROD includes a vegetative cover and LUCs.
- The Transitory Shelter 202 area (OU 11) was formerly a storage area. The remedy, as finalized through the 2007 ROD, also consists of a vegetative cover and LUCs.
- The former Building 112 area (OU 12) was historically used for pesticide storage and mixing operations. The ROD was signed in 2005 and the remedy included an asphalt cover, LUCs and groundwater monitoring for arsenic for five years.
- The PAH area (OU 13) consists of a fuel oil spill area. The contaminants of concern include arsenic, dioxins and PAHs.
What Is the Current Site Status?
The site is being addressed through federal actions.
EPA is overseeing the ongoing cleanup efforts at the Site. Record of Decisions (RODs) have been issued for OUs 1, 2, 3, 4, 5, 8, 10, 11 and 12. Remedial actions were implemented at OUs 1, 3, and 5. An ESD was issued for OU 5, which called for no further action at the Site. A final ROD with an interim remedy and subsequent ESD was issued for OU 9 (Interim remedial action for OU 6 groundwater was implemented as OU 9). A removal action was completed at OU 4. The OU 12 remedial action construction was completed in September 2006. Remedial actions for OUs 8, 10 and 11 are ongoing.
EPA has conducted several Five-Year Rreviews of the site’s remedy. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by site decision documents. The most recent review conducted August 2013, concluded that completed remedial actions at the site are in accordance with the remedies selected by EPA and that the remedies continue to be protective of human health and the environment. For OUs for which final remedies are not yet complete, the review concluded that the remedies will be protective of human health and the environment upon completion. The next Five-Year Review is scheduled for September 2018.