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Record of Decision System (RODS)



Address:  RTE 113 
City & State:  DOVER  DE  19901
County:  KENT
EPA ID:  DE8570024010
EPA Region:  03
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/ROD/R03-95/207
ROD Date:  09/26/1995
Operable Unit(s):  11
Media:  groundwater
Contaminant:  Trichloroethene (TCE), perchloroethene (PCE), and 1,2-dichloroethen
Abstract:  Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.

Dover Air Force Base (DAFB) is located in Kent County, Delaware, three and a half miles southeast of the city of Dover and is located on the St. Jones River. DAFB comprises approximately 4,000 acres of land, including annexes, easements, and leased property. The surrounding property is mainly cropland and wetlands.

DAFB began operation in December 1941. Since then, various military services have operated out of DAFB. The present host organization is the 436th Airlift Wing. Its mission is to provide global airlift capability, including transport of cargo, troops, equipment, and relief supplies.

The portion of DAFB addressed in this Record of Decision (ROD) is located within Area 6 of the West Management Unit. The Area 6 region of investigation extends approximately 8,400 feet from its northern-most point near the hardstand and Building 723 to its southern-most point near the St. Jones River. The area north of U.S. Highway 113 contains the industrialized portion of the Area 6 region of investigation. The location addressed in this ROD falls within this industrialized portion of Area 6.

Area 6 is defined by the association of chlorinated solvents in groundwater forming a plume in the Columbia Aquifer. Several separate potential sources were identified in the Area 6 remedial investigation (RI) that may have contributed to the chlorinated solvent contamination.

The Area 6 RI identified four regions where shallow groundwater contained combined concentrations of the chlorinated solvents trichloroethene (TCE), perchloroethene (PCE), and 1,2-dichloroethene (DCE). These regions were inferred to be in the vicinity of the source areas for the chlorinated solvent plumes that are present in Area 6. The source area addressed in this ROD is the Paint Washout Area located along the eastern portion of the open storage yard. The maximum concentration of total chlorinated volatile organic compounds (VOCs) in Target Area 1 groundwater was found in the shallow portion of the Columbia aquifer. Comparing the concentrations of chlorinated VOCs in the shallow and deep portions of the Columbia Aquifer, it is apparent that the constituents migrated downward through the Columbia Aquifer where most of the plume expansion occurred.
Remedy:  The selected interim remedy consists of in situ bioremediation of groundwater utilizing intrinsic bioremediation. Intrinsic bioremediation is one of the bioremediation technologies being applied to the Target Areas to promote the development of alternate and innovative treatment technologies. Performance of the interim remedy and compliance with applicable or relevant and appropriate requirements will be evaluated in the Final Basewide ROD.
Text:  View full-text ROD [ 41K ]
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