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Record of Decision System (RODS)



City & State:  FALMOUTH  MA  02542
EPA ID:  MA2570024487
EPA Region:  01
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/ROD/R01-95/114
ROD Date:  09/29/1995
Operable Unit(s):  04
Media:  groundwater
Contaminant:  Trichloroethylene, 1,1,1-trichloroethane
Abstract:  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.

Otis Air National Guard, Massachusetts Military Reservation (MMR) occupies approximately 22,000 acres and consists of several operating command units. The Air Force managed the base until the end of 1973 when base management was transferred to the Air National Guard.

MMR has a year-round population of approximately 2,000 people, with an additional 800 nonresident employees. Year-round residents live in a housing area operated by the Coast Guard. Intermittent use of the area for Reserve and National Guard activities increases the MMR population by as many as several thousand people. Both year-round and seasonal residents live in the towns adjacent to MMR.

The area of contamination (AOC) addressed in this ROD occupies approximately 224 acres of land adjacent to the eastern boundary of the MMR. The Transmitter Station includes the main building, which houses the generator and offices, a 4,000 gallon aboveground fuel tank, and storage sheds.

Available documentation shows that activities conducted at the Transmitter Station that may have introduced hazardous substances to the AOC occurred from 1969 to 1975. Reportedly, these activities included the disposal of waste solvent (i.e., 30 gallons per year of trichloroethylene) on the ground and the reported burial of used electrical components, including capacitors and transformers, in a trench south of the Transmitter Building. Transformer oil, transformers, and capacitors may have contained polychlorinated biphenyls (PCBs). Drummed solvents were stored onsite, however, the storage area has since been removed of drums and covered by an addition to the Transmitter Building.

The original water supply well, located inside the Transmitter Building, was abandoned due to contamination of an undocumented nature. Some time before April 1986, a replacement well was installed approximately 80 feet north of the building. This replacement well is no longer used as a source of drinking water, reportedly because of an objectionable taste, however, it does supply water for all other uses at the building. Testing of the water indicated that low levels of 1,1,1-trichloroethane (TCA) and inorganics were present. However, due to the detection of contaminants in a water supply well within a regional groundwater recharge area, the AOC received a Hazard Assessment Rating Methodology score sufficient to qualify for it for further investigation.
Remedy:  No Action is necessary to address the contamination. However, groundwater monitoring will be performed at well WW-7 for a period of five years to provide information over time on the levels of volatile organic compounds detected in this well, and on the sporadic detection of inorganics in groundwater. These compounds were detected below state and federal Maximum Contaminant Levels for this site. Because the chemicals are at concentrations below those considered to present human health or ecological threats, no five year site reviews will be conducted.
Text:  View full-text ROD [ 65K ]
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