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Record of Decision System (RODS)



Address:  NEW ST 
City & State:  DOVER  DE  19904
County:  KENT
EPA ID:  DED980693550
EPA Region:  03
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/ROD/R03-94/186
ROD Date:  08/16/1994
Operable Unit(s):  01
Media:  groundwater, soil
Contaminant:  NAPLs, coal tar
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.

The 23-acre Dover Gas Light Company Site is a former coal gasification plant located in Kent County, Delaware. The site is currently an unpaved parking area that is used by the Delaware State Museum and other nearby businesses. The site lies directly over the Cheswold and Piney Point aquifers.

From 1859 to 1948, Dover Gas Light Company used the site for the production of gas through a process known as coal gasification. When the plant closed, all structures except the retort building were demolished. Much of the plant was removed, but sections of process equipment containing coal oil, coal tar, coke, and possibly acid, were buried on-site. Contamination was first discovered in 1984 when the State Development Office conducted studies in preparation for the construction of a Family Court building. Remains of the coal gasification plant were found buried and oily soil samples yielded significant contamination levels. As a result, the Department of Natural Resources and Environmental Control (DNREC) installed and sampled 16 monitoring wells. Shallow ground water at and to the southeast of the gas plant was found to be contaminated with several VOCs and PAHs. The Site was subsequently proposed for inclusion on the NPL in January 1987 and was finalized on the NPL in October 1989.

This ROD addresses the final remedial action for this site. The remedy will attain ground water ARARs or a waiver will be invoked in the future through the issuance of an Explanation of Significant Differences if attainment of ground water ARARs is determined by EPA to be technically impracticable. The results of the risk assessment showed that there are two major areas requiring remediation: 1) the soils at the location of the former coal gas plant and 2)the groundwater. This ROD addresses both areas.
From the results of the RI/FS, EPA considers the heavy deposits of coal tar and NAPLs to be principal threat waste. Generally, EPA expects to use treatment rather than containment to address principal threat waste.
Remedy:  The selected remedial action for this site includes hydraulic containment of an area containing nonaqueous phase liquids (NAPLs), removing any accessible and pumpable NAPLs, and natural attenuation of the portion of the plume containing only dissolved contaminants; if EPA determines that attainment of maximum contaminant levels (MCLs) or non-zero ma technically impracticable, EPA will invoke the "technical impracticability" ARAR waiver. All extracted ground water will be treated and discharged to the St. Jones River or POTW. Soils at the location of the former coal gas plant that do not meet site-specific clean-up criteria will be excavated and treated off-site using commercially available thermal destruction facilities. The remedial action includes institutional controls on well installation, an operations and maintenance plan, and ground water monitoring plan.
Text:  View full-text ROD [ 158K ]
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