NCR Corp. operated a 140-acre manufacturing facility in Millsboro, Delaware from 1967 to 1980, producing cash registers and using trichloroethylene, or TCE, as a degreasing chemical. Waste from plating operations went into on-site concrete lagoons, and sludge was buried in a pit on the property. Those practices contaminated both soil and groundwater with TCE, chromium, and related breakdown chemicals. EPA added the site to the Superfund National Priorities List in 1987.
Eleven contaminants have been identified in groundwater at the site. These include TCE and its breakdown products such as vinyl chloride, cis-1,2-dichloroethene, and trans-1,2-dichloroethene, as well as tetrachloroethene, chloroform, and chromium. EPA selected a cleanup plan in 1991 targeting this groundwater contamination. Work has included extraction wells, air stripping, carbon adsorption, and later additions of air sparging and soil vapor extraction. More recently, in-ground bioremediation and chemical oxidation and reduction were added to the remedy. A groundwater pump and treat system has run since 1988, and physical construction of the remedy was completed in September 1996.
M&T Bank is the responsible party and has voluntarily supported additional cleanup testing. Investigations found no harmful levels of TCE or related contaminants in domestic supply wells or in Iron Branch Creek. A 2015 evaluation found no unacceptable health risks from vapor migration into the M&T Bank building on the property. Delaware's Department of Natural Resources and Environmental Control established a groundwater management zone that blocks new water supply wells in the contaminated area. Zoning restrictions also prevent residential use of the property.
A five-year review was completed in June 2025. It found that cleanup remains protective of human health and the environment in the short term. EPA expects to achieve long-term protectiveness by the next review in 2030. Upcoming work includes evaluating the groundwater treatment system, testing a sub-slab depressurization system for vapor intrusion, sampling surface water and sediment in Iron Branch, and testing groundwater for 1,4-dioxane and per- and polyfluoroalkyl substances, known as PFAS. An explanation of significant differences is estimated for the November 2027 to January 2028 timeframe. The site has not yet been deleted from the National Priorities List.
Community members can engage through EPA's Community Involvement Program. Two EPA staff members handle questions about the site. Miranda Cento is the Community Involvement Coordinator, and Kate Lasseter is the Remedial Project Manager. Site documents are available online and at two physical locations: the Town Office Building at 322 Wilson Highway in Millsboro, Delaware, and EPA Region III in Philadelphia, Pennsylvania, both by appointment.
