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North Penn Area 1

Public Notice: September 1998

EPA Issues Explanation of Significant Differences for North Penn Area 1 Superfund Site

On September 24, 1998, the U.S. Environmental Protection Agency (EPA) issued an Explanation of Significant Differences (ESD) for the North Penn Area 1 Superfund Site in Souderton, Montgomery County, Pennsylvania. The Pennsylvania Department of Environmental Protection has concurred with this ESD, which is issued in accordance with Section 117 of the Comprehensive Environmental Response and Liability Act (CERCLA), as amended, 42 USC 9617(c), and 40 CFR 300.435(c)(2)(I). The ESD provides the public with an explanation of the change regarding the groundwater treatment plan described in the September 30, 1994, Record of Decision (ROD) for the site.

The soil excavation outlined in the 1994 ROD was completed on July 13, 1998. A total of 482 tons of soil were removed from the GKM and Gentle Cleaners properties.

EPA has determined that the interim cleanup plan selected for Operable Unit 2 (OU2) groundwater should be the final cleanup plan for contaminated groundwater. A ROD amendment is not required because the overall goal of the cleanup plan is the same. That goal is to eliminate the potential exposure risk from the contaminated soil, to eliminate the source of contamination migrating to the groundwater, and to prevent the spread of contaminated groundwater.

Explanation of Significant Differences

When the 1994 ROD was prepared, EPA selected an interim plan for contaminated groundwater because there was not enough information about the groundwater contamination beneath the site. The interim plan called for a pump- and-treat groundwater extraction system. Because there was a documented tetrachloroethylene (PCE) spill at the Gentle Cleaners property on the site in the early 1970s, there was a possibility that Dense Non-Aqueous Phase Liquids (DNAPLs) would be found in the subsurface water. If this proved to be the case, then a more sophisticated treatment system would have been necessary to clean the groundwater.

To determine the extent of the groundwater contamination, three monitoring wells were installed and sampled during the remedial design. The sampling data showed that the levels of contamination in the wells were low and that there was no evidence of the presence of DNAPLs. Based on these results, EPA determined that the system constructed as the interim cleanup measure should be sufficient to clean the contaminated groundwater. In addition, maximum contamination levels (MCLs) as established in the Safe Drinking Water Act will be used as the cleanup goal. Since MCLs are higher than background levels (levels of compounds found naturally in the soils), they are easier to achieve. And, because the source of the groundwater contamination the contaminated soils has been removed, the levels of PCE in the groundwater are not expected to increase.

EPA will monitor the levels of contamination in the groundwater by conducting periodic sampling using the monitoring program established in the ROD. This monitoring program requires sampling and analysis of the three monitoring wells constructed during the remedial design and the GKM and S-9 wells. EPA is required to conduct policy reviews every five-years until groundwater cleanup levels have been attained. The data collected during the monitoring program will be used to evaluate the performance of the extraction system.

For More Information

The ESD, as well as other site documents, are included in the Administrative Record located at the information repository for the North Penn Area 1 Superfund Site and are available for public review. To review this ESD, please visit one of these locations:

U.S. EPA Region III
1650 Arch Street
Philadelphia, PA 19103-2029
Monday Friday, 9:00 a.m. 4 p.m.
Please call in advance for an appointment, (215) 814-3157

Indian Valley Public Library
100 East Church Ave.
Telford, PA 18969
(215) 723-9109

If you have any questions regarding the site, please contact one of these EPA representatives:

David Polish (3HS43)
Community Involvement Coordinator
(215) 814-3327

Maria de los A. Garcia (3HS21)
Remedial Project Manager
(215) 814-3199

U.S. EPA Region III
1650 Arch Street
Philadelphia, PA 19103-2029

Region 3 | Mid-Atlantic Cleanup | Mid-Atlantic Superfund |EPA Home | EPA Superfund Homepage


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