Evaluation of Vapor Intrusion in Complex Geologic Setting
- Article by Kevin Kilmartin et al.
- July 1, 2015
- Technology News and Trends, July 2015
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In this article, Tetra Tech’s Kevin Kilmartin and U.S. Environmental Protection Agency’s (EPA) Mitch Cron and Roy Schrock discuss the vapor intrusion mitigation approach implemented at the Crossley Farm Superfund site in Berks County, Pennsylvania. The site is located within a highly faulted and fractured crystalline bedrock setting. Tetra Tech has provided remedial investigation and feasibility study, remedial design, and remedial action services for multiple site media since 1994 as an EPA contractor.
Improper disposal of trichloroethene (TCE) on a local hilltop created a contaminated groundwater plume extending 2.5 miles downgradient along the adjacent valley. Subslab vapor and indoor air sampling of residences indicated vapor intrusion was creating unacceptable human health risks. Since homes in the area range from relatively new to more than 200 years old, varied construction techniques prevented application of a standard design for the mitigation systems. The EPA has installed systems at 19 of the affected homes, and the Pennsylvania Department of Environmental Protection will run the systems until the site risks are reduced to regulatory-acceptable levels.