BUCKS COUNTY, PENNSYLVANIA
PADOH reviewed private well water data provided by EPA (1993-1996, Table 1) and determined no contamination is present in off-site wells at levels of public health concern. A 1996 sample from well RW-01 contained tetrachloroethene at 7 µg/L, which, because of groundwater flow directions (Figure 6), is probably not site related. No contamination was found in RW-01 before 1996, and the source of that contamination is not clear. Migration of site contaminants to nearby wells is unlikely because of natural geological conditions. The proposed groundwater remediation plan that EPA is now implementing should also prevent any likelihood of site-related contaminants reaching off-site residential wells in the future. An interception trench was completed on October 8, 1997, and the recovery wells are now undergoing testing. Once on line, the recovery wells and collection system will provide good site perimeter coverage so that contaminated groundwater does not leave the site (5).
Two water wells are on site. One serves the on-site residence (RW-10), and one serves the
Keystone Excavation building (RW-46). Before EPA put a carbon filter unit at the on-site
residence on October 15, 1997, the home apparently did not have a filter system (6). The
residents reported they used bottled water for drinking and used well water for bathing and
cooking prior to the carbon filter unit installation (6). EPA feels the extensive removal action has
helped decrease trichloroethene levels in the home well from 1,100 µg/L found in 1993 to 41
µg/L found in 1996 (7). The Keystone well is apparently upgradient of the former waste disposal
areas and has never contained any contaminants
The residents at the on-site residence were exposed to trichloroethene present in their well water. The residents stated they did not drink the water, but they did use the water for other household purposes, such as bathing and cooking. The residents did not report any adverse health effects that they associated with use of the well water when it contained up to 1,100 µg/L trichloroethene. Ingestion of that amount would not likely result in adverse health effects; however, inhalation of that amount of trichloroethene in a poorly ventilated environment could cause headache, fatigue, drowsiness, and possibly decreased depth perception and motor skills (8). If someone became sensitive to trichloroethene, that person could develop a skin rash from touching water containing that level (8).
PADOH believes that consumption of trichloroethene in water at 41 µg/L poses no adverse, noncancer public health hazard to people; however, because ingestion of 41 µg/L slightly exceeds the intermediate minimum risk level (MRL) for a 10 kilogram child drinking 1 liter of water a day, ATSDR and PADOH feel that children should not be exposed to that level if possible. The MRL represents a conservative dose estimate we use as a screening tool and does not represent a dose that would necessarily cause adverse health effects (8). Oral exposure at 41 µg/L presents no apparent increased cancer risk following a lifetime (70 years) of oral exposure. PADOH also feels that the people who live in the house should not experience adverse health effects through their dermal and inhalation exposures to trichloroethene at 41 µg/L (8). Installation of the carbon filtration unit stopped the exposure, and maintenance of the unit will prevent future exposures.