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Hazardous Waste Cleanup: INVISTA Seaford Plant in Seaford, Delaware

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The Seaford Facility is located south of Seaford, Delaware on DuPont Road (formally named Woodland Road). The 750 acre plant property is bordered by the Nanticoke River to the east and the Norfolk Southern Railroad to the north. Two branches of the Nanticoke River flow east along the facility's south and southwest property lines.

Cleanup Status

The investigation, remedy selection, and remedy implementation at this Facility are complete, and Institutional Controls have been put into place to prevent exposure to contamination remaining on-site. As the current owner of the real property, INVISTA S.A.R.L. is responsible for on-going monitoring and/or maintenance of the remedy consistent with the Record of Decision (ROD).

A revised Administrative Order on Consent for the facility was executed by DuPont and Delaware Department of Natural Resources and Environmental Control (DNREC) in September of 2014. On March 30, 2016, DuPont notified EPA of the transfer in title to INVISTA S.A.R.L, who will assume responsibility for ongoing monitoring and maintenance of the remedy per the ROD.

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Site Description

Interactive Map of INVISTA Seaford Plant, Seaford, Delaware


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The Seaford Facility is located south of Seaford, Delaware on DuPont Road (formally named Woodland Road). The 750 acre plant property is bordered by the Nanticoke River to the east and the Norfolk Southern Railroad to the north. Two branches of the Nanticoke River flow east along the facility's south and southwest property lines.

The facility was constructed in 1938 by DuPont for the production of textile fibers. It was owned and operated by DuPont until the sale of the operations and assets to INVISTA in 2004. DuPont retained ownership of the real property to conduct the Resource Conservation and Recovery Act (RCRA) corrective action activities at the facility.

INVISTA recently restructured the operations at the Seaford plant. The Seaford plant no longer produces the Bulk Continuous Filament (BCF) nylon and has idled the facilities associated with their Polymerization Operations. As a result of the restructuring efforts, hazardous waste generation is mainly from the facility's process lab and two maintenance shops. Waste is accumulated in the facility's Process Lab Less Than 90-day Accumulation Area and the C2 Warehouse Less Than 90-day Accumulation Area.

The Seaford plant receives hexamethylenediamine (HMD) by rail. The HMD is used in a remaining production process to manufacture a salt product that is then shipped to other plants.

Following an investigation and comment period that extended from April 16 to May 15, 2006, DNREC issued a final RCRA corrective action decision for this Facility on May 25, 2006.

The selected remedy at the Seaford Facility consists of the following items:

  • Solid Waste Management Unit (SWMU) 1: Sampling of well L-6D and monitored natural attenuation of carbon tetrachloride in conjunction with institutional controls. The institutional control is a groundwater management zone around the limits of the carbon tetrachloride plume. On July 20, 2010, the Solid and Hazardous Waste Management Section (SHWMB) concurred with DuPont's recommendation to discontinue sampling monitoring well L-6D for SWMU 1, as carbon tetrachloride has been reported below its maximum contaminant level (MCL) for the past three consecutive monitoring rounds.
  • SWMU 7/12/13: Sampling for arsenic in twelve existing wells and three surface water locations, and monitored natural attenuation of arsenic in conjunction with institutional controls. The institutional control is a groundwater management zone around the limits of the arsenic plume.
  • SWMU 13/17: Installation of a protective soil cover installed over exposed solid waste; completed October 30, 2006.

Installation of a protective soil cover over exposed solid waste proximate to SWMU 13/17 was completed October 30, 2006. On July 20, 2010 The SHWMB concurred with DuPont's recommendation to discontinue sampling monitoring well L-6D for SWMU 1, as carbon tetrachloride has been reported below its MCL for the past three consecutive monitoring rounds.

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Contaminants at this Facility

Wastes evaluated included fly ash, spent halogenated solvents, discarded commercial chemical products and wastes that exhibited corrosive and/or ignitable properties. Groundwater underlying localized areas of the facility contains low levels of metals and volatile organic compounds and previously exhibited low pH. The primary metal of concern in groundwater and sediment is arsenic. The source of increased concentrations of arsenic in groundwater was identified as coal ash generated by the facility power plant. A coal pile adjacent to the power plant was identified as the source of low groundwater pH. A formerly operating landfill was identified as the source of volatile organic compounds in the groundwater. These releases to groundwater were remediated by the implementation of various interim measures, corrective measures and final remedies.

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Institutional and Engineering Controls at this Facility

Institutional /Engineering Control Summary
Restrictions or Controls that Address: Yes No
Groundwater Use
X
 
Residential Use
X
 
Excavation
X
 
Vapor Intrusion
 
X
Capped Area(s)
X
 
Other Engineering Controls
 
X
Other Restrictions
 
X

    Two Institutional Controls were enacted from 2008 – 2009:

    1. A Memorandum of Agreement between the DNREC Division of Air and Waste and the DNREC Division of Water Resources was signed and put in place on April 3, 2008. The Agreement restricts water supply wells from being installed within the footprint of two groundwater management zones. One groundwater management zone (GMZ151) extends beyond the footprint of an onsite arsenic groundwater contaminant plume. The second groundwater management zone (GMZ152) extends beyond the footprint of an onsite carbon tetrachloride groundwater contaminant plume.
    1. An Environmental Covenant (EC) between DNREC and DuPont was filed with the Sussex County Assessment Division (Sussex County) on September 29, 2009. The EC prohibits withdrawal of groundwater from the Groundwater Management Zones (GMZs).  In addition, the EC enacts land use restrictions (non-residential) for designated areas and bans any activities which may interfere with the remedy. The EC covers Solid Waste Management Units (SWMU) : SWMU #1 is in GMZ152, while SWMUs #13 (large and small) that are in GMZ151. In adddition the EC covers SWMU #6, SWMU # 19 , and Golf Course Ash Refuse Area . Also SWMUs #13and #17 have a protective soil cover installed over exposed solid waste that was completed October 30, 2006.
    1. An amendment to the EC was file with the Sussex County on August 5, 2014. INVISTA S.A.R.L. is now responsible ongoing monitoring and maintenance of the remedy.

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    Land Reuse Information at this Facility

    The facility is under continued use.

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    Site Responsibility at this Facility

    RCRA Corrective Action activities at this facility are being conducted under the direction of the EPA Region 3 with assistance from DNREC.

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