Superfund Information Systems: Site Profile

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The Commodore Semiconductor Group site, which is located in Norristown, Montgomery County, Pennsylvania, was operated as a computer chip manufacturing facility from 1970 to 1993 by Commodore Business Machines. Waste solvents were stored in an underground concrete storage tank on site until 1975, when it was taken out of service. An unlined steel tank was installed next to the concrete one in 1975. Inspections conducted by the Pennsylvania Department of Environmental Protection (PADEP) indicated that both tanks leaked and contaminated groundwater. The majority of residences in the area are connected to a privately-owned public water supply, however, a small number of individuals still have operational private wells.

The site was proposed to the National Priorities List (NPL) in January 1987 and added to the NPL in October 1989.

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What Has Been Done to Clean Up the Site?

In 1981, Commodore excavated soils and pumped water from a contaminated well, then sprayed it onto surrounding fields. The volatile organic compounds (VOCs) dissipated into the air. Since 1984, air strippers have been in use to remove solvents from the groundwater. Air strippers have been installed on all affected public wells through agreements between Commodore and the local water authority. Also in 1984, household carbon units were installed at residences where VOC concentrations of at least 1 part per billion were detected in private wells. Other work performed at the site included: groundwater extraction and treatment, extension of the existing waterline to affected residences, and continued maintenance of household carbon units. On June 29, 1993, EPA issued a unilateral order to Commodore Business Machines, and Rockwell Automation, Inc (Rockwell) to carry out this work. Rockwell has complied with the order. Commodore Business Machines went bankrupt.

The waterline extension and laterals to the residences were completed in January 1997. Transfer of the ownership of the waterline extension to Audubon Water Company was completed in December 1997. The connection of the residences and the closing of the residential wells began in January 1998.

The groundwater extraction and treatment system (GWRTS) began treating groundwater in August 2000. The system functioned successfully to contain, and capture site-related VOCs. Analytical data indicates that contamination concentrations decreased significantly. However, residual levels of VOCs exist beneath the site property. The highest level of contamination associated with the Site exists in an upgradient shallow bedrock well. Under the Pennsylvania Department of Environmental Protection (PADEP) voluntary cleanup program, additional information is being collected to determine the contribution of contamination from upgradient sources.

In September 2003, Rockwell Automation completed additional work to enhance and speed up the groundwater treatment. This enhanced treatment included the installation of a full-scale vapor extraction system to remove chemical vapors from the soil and bedrock, chemical oxidation to treat residual contaminant levels in soil near and beneath the building, and air injection/sparge-vapor extraction (AI/S-VE) for the perched zone source area located beneath the southeastern, slab-on grade portion of the building. Rockwell continues to coordinate with EPA and PADEP and is currently operating the AI/S-VE system at the site to expedite cleanup.

A plume stability verification study began in December 2014 by turning off the GWRTS with the understanding that the GWRTS would be restarted if semi-annual groundwater monitoring yields results greater than a calculated threshold for each contaminant. The plume stability verification study continues to provide an opportunity to observe changes in the distribution of contaminants over the area when the groundwater recovery wells are off.

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What Is the Current Site Status?

EPA continues to oversee the cleanup activities at the Commodore Semiconductor Group site by the potentially responsible party (PRP), Rockwell Automation formerly known as Allen-Bradley, LLC. EPA continues to work closely with the PRP and the Pennsylvania Department of Environmental Protection to determine how the site can successfully achieve its cleanup goals, in light of contamination from other sources in the area.

EPA has conducted several five-year reviews of the site’s remedy. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by site decision documents. The most recent, 2020 Five-Year Review (PDF), found that the remedy is protective in the short-term as there is no current exposure to site-related contaminants. Long-term protectiveness of the remedy will be achieved by maintaining effective institutional controls and determining how the site can successfully achieve its cleanup goals, in light of contamination from other sources in the area. The next five-year review is scheduled for 2025.

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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 to minimize groundwater use, prevent possible future vapor intrusion and protect the integrity of the constructed remedy. Additional information about the institutional controls is available in 2020 Five-Year Review (PDF) (pages 7 and 8).

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Emergency Response and Removal

The cleanup also included removal actions, or short-term cleanups, to address immediate threats to human health and the environment. The site’s potentially responsible parties (PRPs) led removal actions in 1981 and 1984. These actions included excavating contaminated soil, pumping water from a contaminated well and spraying it onto surrounding fields, installing air strippers on all affected public wells, and installing household carbon filtration units.

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