Superfund Information Systems: Site Profile

Superfund Site:

NCR CORP. (MILLSBORO PLANT)
MILLSBORO, DE

Cleanup Activities

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Background

The 140-acre NCR Corp. (Millsboro Plant) site is located in Millsboro in Sussex County, Delaware. National Cash Register (NCR) Corp. manufactured mechanical cash registers from 1967 to 1975 and electronic cash registers from 1975 to 1980. Trichloroethylene (TCE), used for degreasing operations, was stored in a tank outside the manufacturing building. Also, waste from the plating operation was discharged to on-site lagoons. The chromium-bearing sludge that accumulated in the lagoons was later disposed in a pit on the property.

These waste disposal practices contaminated soil and groundwater with hazardous chemicals. This site was proposed to the National Priorities List in 1985 and formally added to the list in 1987.

NCR Corp. is conducting the cleanup as a responsible party. Cleanup activities are ongoing.

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What Has Been Done to Clean Up the Site?

After manufacturing operations were discontinued, First Omni Bank, National Association of Maryland (currently M&T Bank), purchased the operating portion of the property from NCR in 1981.

In 1981, NCR excavated chromium-bearing sludge from a bentonite-lined pit. Toxic materials were drained and removed from two concrete-lined storage lagoons and 28 groundwater monitoring wells were installed.

In 1988, NCR entered into a Consent Order with the State of Delaware which required interim remedial measures to address trichloroethylene (TCE)-contaminated groundwater in the Phase I Area of the site. These measures included installation and operation of a groundwater recovery well and onsite treatment of the recovered groundwater with an air stripper.

EPA issued a Record of Decision (ROD) in 1991, selecting a remedy which included additional groundwater recovery wells in the Phase I Area and emission controls for the air stripper, if necessary. The ROD also required a groundwater investigation in the Phase II Area and groundwater recovery wells in the Phase II Area, if necessary.

In March 1992, EPA issued a Unilateral Administrative Order requiring NCR to design, construct, operate, and maintain the remedy selected in the 1991 ROD. Construction of the remedy for the Phase I Area was completed in November 1995. The construction included additional recovery wells and a sub-surface infiltration gallery for treated groundwater.

The ROD was later modified with three Explanations of Significant Differences (ESDs). The first ESD selected air sparging/soil vapor extraction (AS/SVE) as the remedy for groundwater in the Phase II Area of the site. Construction for the Phase II Area remedy was completed in September 1996. The AS/SVE system in the Phase II Area operated until 2001 and substantially reduced contaminant levels in groundwater.

The second ESD selected AS/SVE to enhance restoration of contaminated groundwater in the Phase I Area.  An AS/SVE system subsequently operated in the Phase I Area from 1999 to 2007, further reducing contaminant levels in groundwater in the subject area.

In 1999, the Delaware Department of Natural Resources and Environmental Control (DNREC) created a Groundwater Management Zone at the site restricting the use of groundwater until the clean-up levels are achieved.

In July 2003, First Omni Bank merged with Manufacturers and Traders Trust Company (M&T Bank).

Since 2003, the responsible parties have voluntarily enhanced the groundwater remedy by piloting technologies known as in-situ reductive dechlorination and abiotic treatment to further reduce concentrations of groundwater contaminants at the site.

In March 2015, site groundwater was analyzed for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). These chemicals have been associated with chrome plating and electronics manufacturing. No unacceptable risks were identified.

Also in March 2015, the potential for vapors from the groundwater plume to migrate into the M&T Bank building was evaluated. Site-related vapor concentrations below the bank building were found to not pose a risk to human health. Therefore, no response action was necessary.

Sampling has found that downgradient domestic wells and Iron Branch Creek are not adversely impacted by the site.

A third ESD was signed in 2016. This ESD added in-situ reductive dechlorination and abiotic treatment to the remedy.

In May 2017, NCR requested that they be allowed to discontinue operation of the remaining groundwater recovery well. This request was made due to the extended age and over capacity of the system, which resulted in numerous shutdowns for maintenance. EPA approved the request in July 2017.

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What Is the Current Site Status?

EPA has conducted several five-year reviews of the Site’s remedy. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by Site decision documents. The most recent, 2015 Five-Year Review (PDF), concluded that the remedy continues to be protective of human health and the environment. The next five-year review is scheduled for June 2020.

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Emergency Response and Removal

The cleanup also included removal actions, or short-term cleanups, to address immediate threats to human health and the environment. Actions in 1981 removed chromium-bearing sludge from a bentonite-lined pit and toxic materials from two concrete-lined storage lagoons. In 1988, an interim remedial measure included installation and operation of a groundwater recovery well and on-site treatment in the Phase I Area of the site.

On-Scene Coordinator's NCR Corp. (Millsboro Plant) Web Site

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