Record of Decision System (RODS)
STANDARD CHLORINE OF DELAWARE, INC.
|Site Name:||STANDARD CHLORINE OF DELAWARE, INC.|
745 GOVERNOR LEA RD
|City & State:||NEW CASTLE DE 19720|
|NPL Status:||Currently on the Final NPL|
|ROD Type:||Record of Decision|
|Media:||groundwater, soil, sediments|
|Contaminant:||DNAPLs, monochlorobenze, chlorinated benzene compounds, organics|
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 Standard Chlorine of Delaware, Inc.(SCD or Standard Chlorine)site, approximately 40 acres in size, is located three miles northeast of Delaware City, Delaware. The SCD facility was constructed in 1965 on farmland. SCD operations were started in 1966 with the production of chlorinated benzene compounds including chlorobenzene, paradichlorobezene, orthodichlorobenzene, and lesser amounts of metadichlorobenzene and trichlorobenzene. Although operational production has varied over the years, these chemicals are still the primary products produced at the SCD facility.
In September 1981, a release of approximately 5,000 gallons of monochlorobezene (MCB) occurred at the SCD Site while workers were filling a railroad tank car. Some of the released chemical ran off in surface ditches toward a tributary to the Red Lion Creek. In response to this spill, under the direction of the Delaware Department of Natural Resources and Environmental Control (DNREC). SCD moved to prevent the discharge of MCB to the Red Lion Creek.
SCD's investigation revealed that the groundwater beneath the site was contaminated with other chlorinated benzene compounds, in addition to MCB. The primary source for the other chlorinated benzene was attributed to a leaking process drainage catch basin (CB#1), which was discovered and repaired in March 1976. SCD installed a groundwater recovery and treatment system in 1982. This system has been upgraded over time. The current configuration was implemented after a second major release from the facility which occurred in 1986. Monitoring of the groundwater recovery and treatment system is performed by SCD and has been documented in quarterly reports to DNREC.
The second major release occurred at the SCD facility on January 5, 1986 when approximately 400,000 gallons of paradichlorobenzene (DCB) and approximately 169,000 gallons of trichlorobenzene (TCB) were released at the site due to a total above ground tank failure. Some of the contaminants migrated from the mouth of the tributary upstream along the southern shoreline of Red Lion Creek.
The selected remedy consists of two components; an interim action for the groundwater and a final action for the soils and sediments. The interim action component will address containment of the groundwater; the final action will address treatment of the contaminated soils and sediments.
The interim action for the groundwater addresses containment of groundwater to minimize the continued release of contaminants. The interim action includes the following steps: construct a subsurface physical barrier such as a trench or slurry wall to contain groundwater and Dense Non-aqueous Phase Liquids (DNAPLs); install low-volume recovery wells to remove pools of DNAPLs which are identified during remedial design; repair and upgrade (if necessary) the existing groundwater pump-and-treat system; treat contaminated groundwater in the existing wastewater treatment plant along with treatment of all resulting air emissions; establish institutional controls to include deed restrictions and a Groundwater Management Zone (GWMZ); determine the extent of groundwater and DNAPL contamination; evaluate the technical practicability of remediating groundwater to health-based levels.
The preferred final action for soils and sediments is biological treatment. This innovative technology has the potential for substantial risk reduction at a much lower cost than thermal treatment. The major steps of biological treatment are as follows: conduct biological treatability/pilot-scale studies to determine the ability of biological treatment to reduce the concentration of contaminants in the soils and sediments to cleanup criteria; bioremediate the soils/sediments along the western drainage gully, the eastern drainage ditch, the soils adjacent to Catch Basin #1, those along the railroad tracks and along the unnamed tributary to Red Lion Creek, in addition to those soils in the waste piles and in the sedimentation basin using in situ (in place) or ex situ (excavated) treatment.
If, based on the results of the treatability studies or further testing during the remedial design phase, it is determined that bioremediation is not feasible for this Site, the preferred contingency remedy is Low Temperature Thermal Desorption (LTTD). The contingency remedy (LTTD) includes the following steps: excavate and treat the soils/sediments along the western drainage gully, the eastern drainage ditch, the soils adjacent to Catch Basin #1, those in the waste piles and in the sedimentation basin, as well as the soils along the unnamed tributary to Red Lion Creek; construct a low permeability asphalt cap along the railroad tracks and adjacent to Catch Basin #1; and restore the wetlands damaged by the remedial action.
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