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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. 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.

This site was proposed to the National Priorities List (NPL), a list of the most serious uncontrolled or abandoned hazardous waste sites, requiring long-term remedial action on January 22, 1987. The site was formally added to the list on October 4, 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 at least 1 part per billion of VOC was detected in private wells. Other work done at the site included, groundwater extraction and treatment, extension of the existing water line to affected residences, and continued maintenance of householde carbon units. On June 29, 1993, EPA issued a unilateral order to Commodore Business Machines, and Allen-Bradley Corporation to carry out this work. Only Allen-Bradley Corporation 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 from Allen Bradley Corporation 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.

Construction of the groundwater extraction and treatment system began in the Fall of 1999. In February 2000, pipelines and underground wiring were installed, pumps were installed at each of the extraction wells, and the groundwater treatment building was constructed. The treatment process equipment was installed in May 2000. Preliminary start-up and testing of the system began in August 2000.

In September 2003, Rockwell Automation completed additional work to enhance and speed up the groundwater treatment. This enhanced treatment (ET) included the installation of a full-scale vapor extraction system to remove chemical vapors from the soil and bedrock, and chemical oxidation to treat residual contaminant levels in soil near and beneath the building. Rockwell continues to coordinate with EPA and PADEP and intends to accelerate cleanup.

In January 2007, the Audubon Water Company stopped accepting treated water from the groundwater treatment system. Rockwell Automation currently sends treated water to the sanitary sewer system and therefore has changed the groundwater system's pumping rate to 10 gallons per minute. Semi-annual groundwater sampling shows that the treatment system is maintaining capture of the contamination. In light of recent groundwater data, Rockwell has been performing a plume stability analysis at the Site since December 2014.​

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What Is the Current Site Status?

EPA is overseeing current cleanup activities at the Commodore Semiconductor Group site by the Potentially Responsible Party (PRP), Rockwell Automation formerly known as Allen-Bradley, LLC.

The remedy for the site includes, among other things, a groundwater pump and treat system and the extension of an existing waterline to twelve residences along Rittenhouse and Audubon Roads. The waterline extension was turned over to the Audubon Water Company. Construction of a groundwater treatment system was completed in August 2000. The groundwater system currently pumps and treats approximately 10 gallons per minute of contaminated groundwater. Rockwell conducts groundwater sampling semi-annually to monitor the effectiveness of the groundwater treatment system.  In light of recent groundwater data, Rockwell has been performing a plume stability analysis at the Site since December 2014.

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 2015 Five-Year Review (PDF), found that the implemented remedy is protective in the short-term as there is no current exposure to Site-related contaminants of concern. Long-term protectiveness of the remedy will be achieved by continuing to pump and treat the groundwater, and maintaining effective institutional controls until cleanup standards are achieved. The next five-year review is scheduled for 2020.

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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 institutional controls is available in 2015 Five-Year Review (PDF) (pages 8, 9 and 26 ).

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Emergency Response and Removal

Cleanup has 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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