Mid-Atlantic Superfund

EPA Region 3 (Mid-Atlantic)

Delaware
New Castle County
Wilmington

EPA ID# DED980830954

1st Congressional District

Last Update: September 2009

Other Names

None

Current Site Status

The U.S. Environmental Protection Agency has overseen the cleanup of the Halby Chemical site where treatment of 11,000 cubic yards of carbon disulfide contaminated soils was completed in January 1998. In March 1998, a Record of Decision (ROD) was issued outlining plans for the entire cleanup, including capping arsenic-contaminated soil; filling chemically degraded wetlands; creating new wetlands at an off-site location to compensate for those to be lost; and institutional controls to prevent any installation of drinking water wells in the vicinity of the site. EPA entered into a Consent Decree with the potentially responsible parties during the Spring of 1999. The settling parties began carrying out the cleanup during June 2001. The cleanup was completed in 2002. Monitoring at the Site will ensure the protectiveness of the remedy. EPA issued the second Five Year Review Report for the Site in September 2007.

Site Description

The Halby Chemical Site is located within an industrialized section of Wilmington's port area. At least five small businesses are currently located on the property. The nine-acre Site includes a former chemical production area located on the southernmost three acres of the Site, where chemicals were manufactured from 1948 to 1980. Upon cessation of chemical production operations, the owner simply boarded up the two buildings housing processing equipment, with unwanted chemicals remaining in-place. A laboratory was abandoned on the second floor of the office building/warehouse. During operations, wastewater from the production of sulfur-based compounds at the plant was discharged into an unlined lagoon. Chemical effluent then flowed through an adjacent tidal marsh leading to the Lobdell Canal, through the Lobdell Canal, and into the Christina River ½ mile east of the Site. This discharge practice resulted in significant residual contamination of lagoon and marsh sediments (primarily with ammonia, zinc and arsenic). Some contaminants from the effluent, specifically carbon disulfide and thiocyanate, seeped directly into the underlying ground water. Subsurface soil beneath the former effluent outfall was so highly contaminated with carbon disulfide that routine sampling caused the ignition of vapors. On-Site soil contains elevated concentrations of inorganic chemicals including arsenic. Eden Park, a residential community, is located about 1/4 mile west of the Site; approximately 2,500 people live within a mile. Residents receive potable water from the Artesian Water Company, which draws water from clean and unthreatened supply wells located several miles from the Site.

Site Responsibility

The cleanup of this site is the responsibility of federal and state governments and parties potentially responsible for site contamination.

NPL Listing History

This site was proposed to the National Priorities List of the most serious uncontrolled or abandoned hazardous waste sites requiring long term remedial action on September 18, 1985. The site was formally added to the list June 10, 1986, making it eligible for federal cleanup funds.

Threats and Contaminants

The groundwater is contaminated with carbon disulfide and metals, including arsenic and manganese. The lagoon and marsh sediments contain high levels of ammonia, arsenic, cadmium, copper and zinc. The surface water contains elevated levels of ammonia and heavy metals, including arsenic and lead. Elevated levels of arsenic were detected in the surface soil, and elevated levels of carbon disulfide in subsurface soil. The carbon disulfide-contaminated soil was treated with an innovative in-situ oxidation process, and no longer presents a threat.

Contaminant descriptions and risk factors are available from the Agency for Toxic Substances and Disease Registry, an arm of the CDC.

Cleanup Progress

Construction Complete. Construction at the Site was completed in 2002. All contaminated soils and sediments have had protective covers placed on them, and a monitoring program is being implemented to ensure the long-term stability of those covers. The Preliminary Close-Out Report for the Site was signed on April 22, 2002. In July 1995, EPA completed a removal action at the Site. The buildings and above-ground storage tanks within the former process area were dismantled and disposed of off-site, leaving a chemical-empty warehouse within the fence. EPA addressed the contents of an estimated 600 small containers and 13 pressurized cylinders found in the abandoned laboratory area. An estimated 200 drums and 50 tanks were found in the warehouse area, chemical processing area, and tank farm, and approximately 1,000 small containers were found haphazardly mixed with shallow soil near the sump. Chemicals in these containers and vessels, such as carbon disulfide, thorium nitrate, mercury, ammonium thiocyanate, sulfide, cyanide and tetrachloroethene, were transported off-site for safe disposal. In accordance with a Unilateral Administrative Order issued in July 1995, Witco Corporation, a former owner/operator, erected a security fence and successfully treated the carbon disulfide-contaminated soils with an in-situ chemical oxidation process. A crane-mounted 6-feet-diameter single auger was used to mix sodium percarbonate with contaminated soils to convert the carbon disulfide to relatively inert carbon dioxide and sulfate salts. Treatment of 11,000 cubic yards of carbon disulfide-contaminated soils was completed in January 1998. In March 1998, a Record of Decision (ROD) was issued. The final cleanup plan includes: capping arsenic-contaminated soil; filling chemically degraded wetlands; creating new wetlands at an off-Site location to compensate for those to be lost; and institutional controls to prevent the installation of drinking water wells in the vicinity of the Site. EPA entered into a Consent Decree with the potentially responsible parties during the Spring of 1999. Construction of the final remedy began June 2001 and was completed in 2002. Monitoring at the Site will ensure the protectiveness of the remedy. EPA issued the second Five Year Review Report for the Site in September 2007.

Contacts

Site Contacts

Administrative Record Locations