Hazardous Waste Cleanup: SGS-Thomson Microelectronics in Montgomeryville, Pennsylvania
On this page:
- Cleanup Status
- Site Description
- Contaminants at this Facility
- Institutional/Engineer Controls
- Land Reuse
- Site Responsibility
Cleanup Status
EPA issued a “Yes” determination for the Facility’s Current Human Health Exposures Under Control Environmental Indicator (EI) in October 2022. In September 2023, EPA determined Migration of Contaminated Groundwater Environmental Indicator under Control.
Cleanup Background
During closure of former solvent storage tanks in 1990, volatile organic compounds (VOCs) were discovered in the site soils and groundwater in the general vicinity of the tanks. Contaminated soils were excavated in 1994 and a groundwater monitoring program was initiated. The facility received a release of liability for soils from Pennsylvania Department of Environmental Protection (PADEP) in January 1997 since the analytical data indicated that the Statewide Health Standards (SHSs) had been met. The facility received a release of liability for groundwater from PADEP in February 1997 by virtue of attainment of the site specific standards. Trichloroethylene (TCE) and vinyl chloride remained above PADEP’s medium specific concentrations for groundwater but a downward trend in concentrations was apparent and no registered potable wells were located in the vicinity of the facility. The facility and the surrounding area receive their potable water from the North Wales Water Authority.
While it had appeared that concentrations of contaminants were naturally biodegrading over time based on groundwater samples collected from the mid-1990s through 2006, EPA decided to take another look at groundwater quality beneath the facility in 2019. When it was learned that the existing wells had been properly abandoned and were no longer sampleable, EPA installed 3 pairs of nested wells with each of the nested wells installed as a multiple well borehole containing both a shallow and deeper screened interval. The new wells were sampled in September 2019 and March 2020. Analytical results indicate that the shallow water bearing unit continues to contain elevated concentrations of chlorinated VOCs.
Concurrent with the 2019/2020 groundwater sampling events, EPA also collected three paired sub-slab soil gas/indoor air samples within the facility building to determine if the vapor intrusion pathway was complete. While VOC concentrations in the sub-slab soil gas samples were great enough to suggest the potential for a vapor intrusion problem, the indoor air samples demonstrated the concrete slab provided an effective barrier from those contaminants. No contaminants in indoor air were detected above EPA’s risked based regional screening levels (RSLs) for indoor air.
A Daycare is located approximately 500 feet northwest (upgradient) of SGS. Due to its proximity, in December 2010 and July 2011, EPA’s Superfund program collected sub-slab, indoor air and ambient air samples at the Daycare to determine if the remaining groundwater contamination at SGS was migrating and contributing to potential vapor intrusion inside the Daycare. No constituents of vapor intrusion concern attributable to SGS were detected in any of the samples collected during either round of sampling. Superfund concluded that the vapor intrusion pathway is likely not a completed pathway at the Daycare.
Site Description
Interactive map of SGS-Thomson Microelectronics, Darby, PA
View larger mapThe facility was owned and operated by Advanced Power Technology RF and Microsemi RF between 1993 and 2007. Silicon-based semiconductors in the product area of transistors were historically manufactured at this location by the companies. Hazardous wastes have not been generated and the property has not housed a RCRA treatment, storage or disposal (TSD) type facility since prior to Microsemi RF vacating the facility in 2007. K & B Wireless Communication owned the facility property from 2007 through March 2020 and used the building as a mobile phone showroom and warehouse and had various tenants over the years in the rear (western) portion of the building. The owner of the facility property since March 2020 is 140 Commerce Drive, LLC, which leases out portions of the building to tenants. The Tustin Group, a provider of HVAC, Energy, Water, Fire and Life Safety and Security Services for business owners and property managers, currently leases space in the building.
Contaminants at this Facility
Groundwater in the shallow water bearing unit beneath the facility continues to contain chlorinated VOCs (primarily TCE and vinyl chloride) above EPA’s maximum contaminant levels (MCLs). These contaminants do not appear to be impacting the indoor air quality of the on-site building or any neighboring buildings.
Institutional and Engineering Controls at this Facility
A deed restriction that prohibits groundwater use at the Facility was required as part of the release of liability granted by PADEP. EPA will determine whether any additional controls will be required.
Land Reuse Information at this Facility
The Facility property is currently being reused for commercial/light industrial purposes.
Site Responsibility at this Facility
Resource Conservation and Recovery Act (RCRA) Corrective Action activities at this facility have been conducted under the direction of EPA Region 3 with assistance from PADEP.