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Record of Decision System (RODS)



EPA ID:  PAD093730174
EPA Region:  03
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/ROD/R03-92/155
ROD Date:  09/29/1992
Operable Unit(s):  01
Media:  Groundwater
Contaminant:  VOCs
Abstract:  SITE HISTORY/DESCRIPTION: The 14-acre Commodore Semiconductor Group (CSG) site is a manufacturing facility in Norristown, Montgomery County, Pennsylvania. Land use in the area is residential, commercial, and industrial with a wetland area located within 1 mile from the site. The site overlies a Class IIA aquifer that is used as a source of drinking water. From 1969 to present, the owners, including CGS, used the site to manufacture semiconductor chips. A concrete underground storage tank was installed adjacent to the southeast side of the building to store a waste solution known to contain TCE and other solvents generated from the manufacturing process. The concrete tank was reported to have leaked in 1974. As a result, an unlined steel tank was installed next to the concrete tank. Use of the concrete tank was discontinued. In 1978, a local watersupplier detected TCE in two of its wells adjacent to the site. The state identified the CSG site as a possible TCE contaminant source. Subsequently, in 1979, the underground storage tanks were excavated and replaced with a waste solvent collection system. In 1981, CSG also eliminated use of TCE in their manufacturing process. From 1981 to 1984, to address the TCE contamination, CSG pumped and spray irrigated water from a public supply well, purchased and installed an air stripper for treating contaminated ground water, implemented a residential sampling program, and installed carbon filter systems at affected residences. In 1984, further state and EPA investigations confirmed contaminants onsite in ground water and drinking water. This ROD addresses the contamination of onsite ground water and drinking water. The primary contaminants of concern affecting the ground water are VOCs, including PCE and TCE. PERFORMANCE STANDARDS OR GOALS: Ground water clean-up goals are based on background levels as established by SDWA MCLs or health-based levels, whichever are more stringent. Chemical-specific ground water goals include 1,2-DCB 75 ug/l; 1,2DCA 810 ug/l; PCE 5 ug/l; TCA 200 ug/l; TCE 5 ug/l; and vinyl chloride 2 ug/l. INSTITUTIONAL CONTROLS: Ground water use restrictions on installing new wells shall be implemented in areas where MCLs are exceeded.
Remedy:  SELECTED REMEDIAL ACTION: The selected remedial action for this site includes extending the public water supply lines and connecting affected residences located in areas south of the CSG facility; abandoning contaminated wells; continued maintenance of existing residential carbon units, with disposal or recycling of the spent carbon filters as determined during the remedial design phase; installing additional ground water extraction wells, air strippers, and vapor phase carbon units, to treat the contaminated ground water onsite with discharge to a public water system or reuse by the CSG facility, with overflow discharge offsite to a POTW; sampling ground water and treated water; and implementing institutionalcontrols, including ground water well restrictions. The estimated present worth cost for this remedial action is $5,573,700, which includes an annual O&M cost of $446,500 for years 0-2, and $404,300 for years 3-30.
Text:  View full-text ROD [ 1.80M ]
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