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. NCR Corp. manufactured cash registers from 1967 to 1975 and electronic equipment from 1975 to 1980. Waste disposal practices contaminated soil and groundwater with hazardous chemicals. NCR Corp. is conducting the cleanup. Operation and maintenance activities are ongoing.

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What Has Been Done to Clean Up the Site?

 

The NCR Corporation manufactured cash registers from 1967 to 1975 and electronic equipment from 1975 to 1980 on a portion of this 140-acre site..

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.

After manufacturing operations were discontinued, First Omni Bank, National Association of Maryland, purchased the operating portion of the property from NCR in 1981. In July 2003, First Omni Bank merged with Manufacturers and Traders Trust Company.

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.

This site was proposed to the National Priorities List in 1985 and formally added to the list in 1987. In 1988, NCR entered into a Consent Order with the State of Delaware which required interim remedial measures to address 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, emission controls for the air stripper, if necessary, 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 and Allfirst Financial Center to design, construct, operate, and maintain the remedy selected in the 1991 ROD. Construction of the remedy selected in the 1991 ROD for the Phase I Area was completed, in November 1995, and included an additional recovery well and a sub-surface infiltration gallery for treated groundwater.

The ROD was later modified with two 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.

The Delaware Department of Natural Resources and Environmental Controls in 1999, created a Groundwater Management Zone at the Site restricting the use of groundwater until the clean-up levels are achieved.

Since 2003, the responsible parties have voluntarily enhanced the groundwater remedy by piloting in-situ reductive dechlorination and abiotic treatment studies 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.

In March 2015, the potential for vapors from the groundwater plume to migrate into the M&T Bank building was evaluated. Site-related vapor concentration below the bank building were found not to be an issue that warranted a response.

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What Is the Current Site Status?

EPA has been overseeing the cleanup of groundwater contaminated with the solvent trichloroethylene (TCE) at the site.  Actions taken to address contaminated groundwater have included:

  1. groundwater extraction followed by treatment of the recovered groundwater with an onsite air stripper,
  2. air sparging/vapor extraction and
  3. in situ reductive dechlorination and abiotic degradation.

These actions have substantially reduced TCE concentrations in groundwater at the site. Sampling has found that downgradient domestic wells and Iron Branch Creek are not adversely impacted by the site.

Groundwater recovery and onsite treatment of recovered groundwater continues in the Phase I Area of the site at this time.

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 2020.

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Emergency Response and Removal

Cleanup has 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 Millsboro TCE Web Site

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