The Boarhead Farms Site consists of approximately 124 acres of land currently owned by Boarhead Corporation and is located in Bridgeton Township, Bucks County, Pennsylvania, southwest of the intersection of Lonely Cottage Road and Birch Road. The Site is on the National Priorities List and performance of a long-term remedial response action, or Remedy, to address contaminated groundwater is on-going. The focus of this removal action is a single-family residence located on the Site where high concentrations of trichloroethene (TCE) vapors are present. The residence is located over a cut-stone, loosely mortared foundation that is believed to have been constructed in the late 18th or 19th century, and may be the remnants of a root cellar. A spring enters the basement in the western corner and is connected to a sump located in the southern corner through a trench drain. A second sump located in the north corner does not appear to be connected to the spring. Pumps in both sumps prevent groundwater accumulation in the basement. Staining on the basement walls indicates that water may seasonally rise as high as approximately 2 feet above the floor if not regularly pumped out. The basement is separated from the upper floors by floor doors and is not currently used as a living space.
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In a 2007 statutory review of the Remedy, EPA identified the need to evaluate the residence to determine if vapor intrusion – the volatilization of organic compounds from groundwater and migration into overlying structures – was occurring. Samples collected in December 2008 indicated that TCE was present in air on the first floor at a concentration of 200 micrograms per cubic meter (µg/m³) and in air in the basement at 1,200 µg/m³. A water sample collected from standing water in the basement contained TCE at a concentration of 2,000 micrograms per liter (μg/L). Based on these results, EPA issued a Special Bulletin on May 28, 2009 and initiated an emergency removal action to reduce the high concentrations of TCE in indoor air to less than 10 μg/m³. Engineering measures taken in the residence included the installation of portable air filtration units, cleaning sediment out of the sumps and trench, installation of a pump in one sump and replacement of a pump in the other sump, connection of the combined sump discharge to the groundwater treatment system, placement of non-air tight rubber matting over the sumps and trench, and installation of an exhaust system in the basement. As of September 2014, indoor air results were reduced to less than 10 μg/m³ and the removal action was completed.
Upon an Agency-wide revision of the risks presented by TCE, the non-cancer reference concentration (RfC) was reduced to 2 μg/m³ and a risk management benchmark for early response actions at the same value was established. As a result, conducted sampling in March 2016 to evaluate the current conditions and effectiveness of the engineering upgrades. The results indicated that TCE was present in indoor air above the risk management benchmark of 2 μg/m³ (up to 3.6 μg/m³), and the concentrations in basement air and the open-air groundwater sumps (79 μg/m³ and 2,200 μg/L, respectively) indicated that a substantial threat to human health existed. Subsequently, the EPA RPM initiated a removal site evaluation under 40 CFR § 300.410 to determine whether additional removal response actions were necessary and warranted.
On June 1, 2018, EPA signed an action memorandum to address the release and threat of release of hazardous substances to indoor air within the on-site residence.
On August 28, 2018, EPA and its ERRS contractor, Environmental Restoration, mobilized to the site to begin the removal action. Construction activities were completed on September 20, 2018. On October 2 and 3, 2018, Tetra Tech, a contractor to EPA's Environmental Response Team, collected indoor and ambient air samples to evaluate the performance of the upgraded system. Analytical results received in late October indicated that all TCE concentrations in indoor air were below the 2 µg/m³ goal identified in the Action Memorandum. No further construction activities are planned at this time. Post-removal site controls will be addressed through EPA's remedial program.