Superfund Information Systems: Site Profile

Superfund Site:

A.I.W. FRANK/MID-COUNTY MUSTANG
EXTON, PA

Cleanup Activities

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Background

The Site is located on 16 acres which were originally surrounded by farmland, but are undergoing rapid development, including a mix of residential, commercial and light industrial areas.  From 1962 to 1981, 15 of the 16 acres were used to produce Styrofoam cups and plates. In 1981, Continental Refrigerator Corp. bought the property and manufactured refrigerators, freezers and warming cabinets for the institutional food industry. One acre of the site was leased by Mid-County Mustang since the 1940s, for auto repairs and body shops. Solvents used for engine cleaning were routinely dumped into floor drains until the 1980s when the drains were sealed. From the floor drains, the solvents proceeded onto a drain field and contaminated soil and groundwater, primarily with trichloroethylene (TCE), a major component of solvents and degreasers. More than 900 people live within one mile of the site, and Valley Creek, a recreational area, is located within a half mile.

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What Has Been Done to Clean Up the Site?

  • In 1985, the owners of Mid-County Mustang cemented the floor drains, excavated contaminated soil in the drain field, and shipped the soil off site for proper disposal.
     
  •  EPA placed the site on the Superfund program’s National Priorities List (NPL) in 1989.
     
  • In 1991, a fire destroyed one of the buildings while EPA was studying the site, so EPA demolished the damaged building to safely complete its study and feasibility report, which was done by June 1995.
     
  • Three types of contamination were found: 1) TCE and other solvents in groundwater: 2) TCE and other solvents in soil: 3) abandoned debris in drums, drainage ditches, sumps and underground tanks.
     
  • EPA selected the final cleanup option for the site in a 1995 Record of Decision (ROD), which included construction of a municipal water line; extraction and treatment of contaminated groundwater; and removal and disposal of contaminated soil and debris.
     
  • The EPA connected residential homes to a new public water supply line in 2000 and, at the same time, dug extraction wells to pump and treat the groundwater.  Groundwater pump and treat began in 2000, 24 hours a day, seven days a week.
     
  • In 2011, a vapor intrusion study was done to see if contaminated vapors from the contaminated groundwater were seeping into one of the homes located above the contaminated groundwater plume.  The results indicated that vapor intrusion is not occurring.
     
  • As of January 2012, the groundwater treatment system operation and maintenance, along with required routine groundwater sampling, became the responsibility of the Pennsylvania Department of Environmental Protection (PADEP). EPA performed these tasks for the first 10 years.
     
  • Prior to turning over operation and maintenance to the PADEP, EPA contractors completed pilot studies of in-situ chemical oxidation injections and biological remediation injections in existing and new monitoring wells. The pilot injections used the oxidizing chemicals and naturally occurring bacteria and nutrients to break down contaminants to levels below clean-up standards.
     
  • The results of the pilot studies, which were completed in August of 2011, were evaluated in a Focused Feasibility Study (FFS) that was completed in Spring 2015.
     
  • The FFS results and the data collected were used to propose a remedy modification to the 1995 ROD.  EPA prepared a Proposed Plan for public comment, prior to issuing the ROD Amendment in 2017.
     
  • In June 2017, EPA signed an Amendment to the 1995 Record of Decision to include an additional contaminant of concern to the cleanup – 1,4 dioxane. The Amendment also replaces the extraction and treatment via air stripping of groundwater with in situ chemical oxidation (ISCO) and in situ bioremediation (ISBR).
     
  • EPA is currently in the process of revising its cleanup plans (known as the remedial design) based on the ROD amendment. The final remedial design is expected to be complete in mid-2018.

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What Is the Current Site Status?

  • Operation and maintenance, as well as monitoring, are ongoing.
     
  • EPA is finalizing its remedial design for the in-situ chemical oxidation and in-situ bioremediation of groundwater.
     
  • Every five years, EPA conducts a review of the cleanup to evaluate if it remains protective of human health and the environment. The last five year review was completed in March 2016 (PDF) (65 pp, 4.72 MB, About PDF) and found the remedies to be functioning as designed; however modification of the remedy and further assessment and monitoring is required.

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Activity and Use Limitations

At this site, activity and use limitations that EPA calls institutional controls are in place. Institutional controls play an important role in site remedies because they reduce exposure to contamination by limiting land or resource use. They also guide human behavior. For instance, zoning restrictions prevent land uses – such as residential uses – that are not consistent with the level of cleanup.

For more background, see Institutional Controls.

Institutional controls are in place that currently prevent new residential wells from being installed in contaminant plume.

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Enforcement Information

Enforcement Documents Consent Decree - January 2012 (PDF) (33 pp, 1.27 MB, About PDF)

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