Record of Decision System (RODS)
TANSITOR ELECTRONICS, INC.
|Site Name:||TANSITOR ELECTRONICS, INC.|
|City & State:||BENNINGTON VT 05404|
|NPL Status:||Deleted from the Final NPL|
|ROD Type:||Record of Decision|
|Contaminant:||VOCs, 1,1,1-trichloroethane (1,1,1-TCA), 1,1-dichloroethylene (1,1-DCE), trichloroethene, tetrachloroethylene, vinyl chloride|
Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.
The Tansitor Electronics, Inc. site consists of approximately 44 acres of land on West Road (Route 90) in Bennington, Vermont, and is 3 « miles west of Bennington Center. Most of the site is located to the north of Route 9 and the remainder is located to the south of Route 9. The portion of the site located to the south of Route 9 consists of wetlands, and there are also some wetlands on the northern portion of the property.
The site is located in a rural residential area. It is bounded to the north by privately owned woodland; to the east by Houran Road and a commercial property; to the south by wetlands; and to the west by agricultural/residential areas. Pleasant Valley School is located 1,200 feet east and upgradient of the site.
Transitor Electronics, Inc. currently manufactures electronic capacitors at the site. Approximately 100 workers are employed at the facility. Major site features include Transitor's operating manufacturing/office building, an Etch House, a man-made pond, parking areas, a Solid Waste Disposal Area, a Disposal Area, a Concrete Pad Area, and a Borrow Area.
Potable water supplies in the area, including the water supply on the site, are provided by private bedrock wells. Sanitary waste water from the Tansitor facility is disposed of into two on-site leachfields.
Surficial runoff from the site drains into the Fire Pond, an intermittent stream located on site, and the facility storm drain system, and ultimately into the wetland area south of Route 9. An unnamed east-west flowing perennial stream, located south of Route 9, enters the site from the west and flows through these wetlands into Browns Brook, a Class B surface water body located about « mile off site.
The site is located in an area zoned rural residential with a commercial corridor overlay along Route 9. As a manufacturing facility, Tansitor's industrial use of the site represents a grandfathered non-conforming use under the zoning laws. Because the site could be redeveloped and used for residential purposes under the zoning laws, the Environmental Protection Agency (EPA) considers the future land use of the site to be residential.
Since the 1950s, various owners have used the site as a manufacturing facility for electronic capacitors. EPA was notified that organic solvents and acids had been disposed of on site between 1956 and 1979. Over that period, an estimated equivalent of 117 drums of process waste were disposed in the Disposal Area. During the period of 1975-1979, the process waste disposed in the Disposal Area included 1,1,1-trichloroethane which is the predominant volatile organic compound (VOC) present in the groundwater. Tansitor has also reported that some waste detergents and dilute acid solutions may have been discharged into the two leach fields or directly into the intermittent stream north of its manufacturing building. Finally, Tansitor has reported that waste methanol had been burned periodically on the Concrete Pad.
Tests were performed on the site and Tansitor was requested to initiate removal activities and implement a soil sampling and analysis program in the disposal area. Following there actions, Tansitor was instructed to restrict access to the Fire Pond and disposal areas; define the areal and vertical extent of contaminated soil at the Disposal Area; remove the contaminated soil for proper disposal at a certified hazardous waste facility; design and implement an evaluation and monitoring program to determine the magnitude and extent of contamination resulting from the site; and determine potential remedial actions.
The Remedial Investigation (RI) at the site identified two significant plumes or zones of VOC contamination in shallow groundwater. The first plume originated from the Disposal Area and extends to the Fire Pond. The second plume originated from under the Concrete Pad Area, impacting an area approximately 60 feet by 240 feet.
The RI also identified the Eastern Leach Field, where vinyl chloride was detected in one well. Tansitor has made changes to the facility's interior drain system to eliminate further discharge of process waste to the leach field. Vinyl chloride was not detected in a sample collected after these changes were made.
All of the groundwater contaminants detected have been dissolved in the surrounding groundwater. However, the high levels of certain VOCs found suggest that these contaminants may exist as Dense Non-Aqueous Phase Liquids (DNAPLs) beneath the water table. Because current technologies cannot easily locate DNAPLs, their possible presence at the site is based on circumstantial evidence, and the amount of DNAPLs, if they exist, is not possible to determine. However, if residual pools of DNAPLs do exist, they will slowly dissolve and will continue to be a long term source of contamination into the surrounding groundwater.
One phase of sampling indicated elevated levels of lead, silver, and manganese in some of the monitoring wells. To evaluate the influence of turbidity on the measurements, low flow purging and sampling methodology was employed in the sampling in the next phase. That next phase of sampling results all showed a marked decrease in the concentrations of these metals.
This ROD sets forth the selected remedy for the Tansitor Electronics, Inc. site, which includes management of migration components to obtain a comprehensive remedy. This ROD does not include any source control component, because EPA's risk assessment concluded that the surface and subsurface soils did not present an unacceptable risk either under current conditions or under a potential future residential scenario.
The major components of the selected remedy include: institutional controls to prevent the use of contaminated groundwater and to inform future purchasers of property of the groundwater restrictions associated with the property; long-term monitoring of site groundwater on a regular basis to evaluate changes in site conditions over time; contingencies for future additional investigation or further action should the long-term monitoring reveal that contaminants have migrated beyond their current vertical or horizontal extent; and a five year review.
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