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Record of Decision System (RODS)



Address:  600 TERMINAL AVE 
City & State:  NEW CASTLE  DE  19720
EPA ID:  DED980830954
EPA Region:  03
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/541/R-98/014
ROD Date:  03/31/1998
Operable Unit(s):  02
Media:  Groundwater, Sediment, Soil, Surface Water
Contaminant:  Inorganics, Metals, VOC
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 Halby Chemical site is located in a highly industrialized area near the Port of Wilmington, Delaware. This 10-acre site features include three office buildings/warehouses and a lagoon with associated wetlands. Surrounding land parcels include steel and asphalt plants, a residential parcel, and the Potts Property State Superfund site. Approximately half of the site lies in the 100 year floodplain.

The Halby Chemical plant was constructed in the late 1940s. Specialty chemicals, primarily sulfur compounds, were processed in the chemical manufacturing plant from 1948 to 1980. From 1948 to 1964, production wastewater and cooling water were disposed of by discharge into the unlined on-site lagoon. The lagoon drained into the adjacent tidal marsh through culvert(s) beneath the railroad tracks. The tidal marsh drained to the Christina River through the Lobdell Canal. The chemical production facility operating as Halby Chemical closed in 1977 and the property was sold to Brandywine Chemical Company (BCC).

In 1984, the Environmental Protection Agency (EPA) conducted an inspection of the Halby Chemical site. In April 1986, EPA issued Special Notice Letters to the identified Potentially Responsible Parties (PRPs) inviting them to perform a Remedial Investigation and Feasibility Study (RI/FS). The PRPs declined to conduct the RI/FS.
In June 1991, EPA completed a Fund-lead RI/FS for a portion of the site and issued a Record of Decision (ROD) for the first operable unit (OU1). In August 1991, EPA issued Special Notice Letters to the identified PRPs inviting them to design and implement the remedy selected in the OU1 ROD. Under an April 9, 1992 Consent Decree Witco Corporation (Witco) agreed to perform the remedial design and remedial action for the OU1 ROD, requiring remedial actions in the former process plant area. On February 3, 1995, EPA completed a Removal Site Assessment focusing on the portions of the former chemical production facility and tankfarm which were not being utilized by BCC and were not properly decontaminated or maintained. On February 22, 1995 EPA issued an Action Memorandum documenting removal assessment findings and immediate actions planned to abate the immediate and significant threat posed by the presence of various hazardous substances located in numerous tanks, process lines, reaction vessels, sumps and drains, drums, pressurized cylinders and other containers. On March 6, 1995, a notice was sent informing Witco of potential liability related to necessary removal response actions.

Between February and July 1995, EPA completed the removal activities identified in the Action Memorandum to mitigate the immediate threat posed by improperly stored chemicals in the former process plant area. During completion of final removal activities planned in the February 1995 Action Memorandum, EPA identified an area of high carbon disulfide contamination extending from the point that waste water had been discharged from the chemical production facility to the lagoon. On July 6, 1995, a second Action Memorandum was issued documenting EPA's determination that the carbon disulfide may pose an imminent and substantial endangerment to human health or the environment and outlining actions to be taken to minimize the threat. On June 30, 1995, Notice of Potential Liability was sent re-confirming Witco's potential liability and formally notifying Witco of additional removal activities to be taken at the site. On July 20, 1995, EPA issued a Unilateral Administrative Order for Removal Action to Witco. Pursuant to the Removal Order, Witco successfully implemented mitigative measures. The investigation performed by Witco confirmed a large mass of carbon disulfide located within an area of less than two acres. In July 1997, EPA completed the RI/FS for OU2. A ROD for OU2 was issued in March 1998.
Remedy:  The Soil alternative consists of the following components:

Cover the areas of the site where soil exceeds 38 mg/kg arsenic with a paved cap;
Excavate soil on the adjacent residential property that exceeds 14 mg/kg arsenic and combine with the contaminated soil under the cap;
Backfill the residential property with clean soil, cover with six inches of topsoil and re-establish vegetation;
Monitor gas in the area of the carbon disulfide treatment zone; install a gas collection system, if necessary;
Install a system to control both surface water and soil erosion;
Implement deed restrictions and conduct long-term monitoring to ensure the integrity of the cap;

The lagoon and marsh alternative consists of the following components:

Drain the lagoon and marsh, excavate the I-495 drainage ditch sediments, and place the sediments in the lagoon/marsh area;
Backfill and level the lagoon and marsh with clean soil;
Cap the lagoon area with a paved surface; cover the marsh area with topsoil and establish vegetation;
Utilize a mobile water treatment plant to treat water taken from the lagoon and marsh, if necessary;
Create a new wetlands area at an off-site location, equivalent in function and value to the approximately seven acres of the on-site lagoon and marsh areas to be eliminated;
Implement deed restrictions and conduct long-term monitoring and maintenance activities.

The groundwater alternative consists of the following components:

Implement deed restrictions consistent with Delaware Department of Natural Resources and Environmental Controls (DNREC's) groundwater management zone to provide additional continued assurance that public or domestic water supply wells are not permitted to draw water from aquifers affected by the site;
and conduct groundwater monitoring to track site-related contamination.

The cumulative estimated cost of implementing Selected Remedy is:
Capital Cost: $8,225,000
Annual O&M Cost: $84,100
Total Present Worth Cost $9,740,000
Text:  View full-text ROD [ 192K ]
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