Halby Chemical Co.

Overview

The Halby Chemical Co. site covers 9 acres in the Port of Wilmington industrial area in New Castle, Delaware. A chemical manufacturing plant operated there from 1948 to 1980, discharging wastewater into an unlined lagoon. That wastewater flowed through a tidal marsh, the Lobdell Canal, and into the Christina River. The site was added to the National Priorities List (NPL) in June 1986. Today, six businesses employing 69 people operate on the property, and the site has achieved sitewide ready for anticipated reuse status.

Contamination spread across soil, groundwater, sediment, and surface water. EPA identified 27 contaminants of concern. These include carbon disulfide, mercury, cyanide, tetrachloroethene, arsenic, cadmium, chromium, cobalt, manganese, nickel, and other metals in groundwater, as well as polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene in surface soil. Arsenic also appears in sediment.

Cleanup is organized into two operable units. Operable Unit 1 covers surface soil at the operating facility and uses an engineered cap, excavation, solidification and stabilization of material, off-site disposal, and institutional controls. Operable Unit 2 addresses groundwater and surface water through off-gas treatment, wetlands replacement, revegetation, capping, drainage controls, monitoring, and institutional controls. Active cleanup began in 1995 with removal of buildings, tanks, and contaminated containers. By 1998, chemical oxidation had treated 11,000 cubic yards of carbon disulfide-contaminated soil. All construction was completed by April 2002. Groundwater and surface water operation and maintenance activities began in January 2020 and remain ongoing.

The 2022 Five-Year Review found the remedy protective of human health and the environment in the short term, with no unacceptable exposure pathways currently present. For long-term protection, continued monitoring of stormwater pond sediments and groundwater is required. Institutional controls restrict groundwater well installation, soil disturbance, and residential or incompatible land uses. The next five-year review is scheduled between September and November 2027.

Community members can review the 2024 Community Involvement Plan, which outlines how residents can participate in the cleanup process. Site documents are available at the Wilmington Institute Library in Wilmington, Delaware, or at the U.S. EPA Region 3 office in Philadelphia, Pennsylvania, by appointment. Residents with questions can contact EPA's Community Involvement Coordinator or Remedial Project Manager directly using the contact information below.