DUBLIN TCE SITE
DUBLIN BOROUGH, BUCKS COUNTY, PENNSYLVANIA
The Pennsylvania Department of Health (PADOH) prepared this Health Consultation (HC) to update the status of the Dublin TCE Site in Dublin Borough, Bucks County, Pennsylvania to determine whether the site poses a public health hazard to community residents. A 1997 Site Review and Update published by the Agency for Toxic Substances and Disease Registry (ATSDR) and PADOH concluded that in the past, the site posed a health hazard because of exposures to volatile organic compounds (VOCs) in groundwater. Those exposures ended in 1991 after all contaminated wells received filters to reduce or eliminate contaminants. Since 1991, the U.S. Environmental Protection Agency (EPA) contractor has defined the extent of the groundwater plume and provided all affected residences and businesses with connections to a safe, approved public water supply system.
The Dublin TCE site no longer poses a public health threat to the community. The EPA is currently writing a Record of Decision (ROD) for Operable Unit 2 (OU 2) which will address containment of the plume using a pump and treat process. However, the drought emergency in Bucks County and elsewhere in the state has made regulatory officials reluctant to pump and treat large volumes of groundwater for fear of depleting precious groundwater reserves and drying up public water supply wells. The ATSDR and PADOH will review the ROD for OU 2 when it is presented for public comment.
The Dublin TCE Site (the site) is in Dublin Borough, Bucks County, Pennsylvania (Figures 1 and 2). In addition to the plume, the site includes a 1-story brick building housing an automotive storage and performance shop, situated on 4 ½ acres of land . In 1986, during a routine water supply inspection, the Bucks County Health Department discovered VOCs in a downgradient water supply well. A wider investigation revealed a contaminant plume about ½ mile long and 1/4 mile wide, and confirmed the site as the source . Figure 2 shows in plan view the approximate 5 parts per billion (ppb) concentration contour line (isocon), which delineates the extent of EPA's maximum contaminant level (MCL) for TCE allowed in public water supplies. The isocon is interpolated from monitoring well and water supply well data collected during approximately 10 years of environmental sampling. To reduce exposures, some private well owners began installing treatment systems on their wells almost immediately after contaminant discovery. On June 29, 1987, the site owner signed a Consent Order and Agreement (COA) with EPA to provide all affected wells with carbon filter units . On August 30, 1990, the EPA placed the site on the National Priorities List and, on December 30, 1991, signed a ROD for Operable Unit One (OU1). Also, by the end of 1991, installation of the temporary filter units was completed, and exposures to contaminated groundwater ended. . OU1 provides permanent safe drinking water from an approved public supply for all homes and businesses whose groundwater has been or could become contaminated by the site .
In March 1994 PADOH and ATSDR published a Preliminary Public Health Assessment (PPHA) for the site. In September 1997 they published a Site Review and Update[3,1]. Those documents provide additional details concerning site history, site visits, and regulatory action by EPA.
The EPA Remedial Project Manager (RPM) is writing the ROD for OU 2 which is expected to address hydraulic containment of the plume and eliminate future potential exposures. Dublin Borough and water authority officials have expressed concern to EPA that pumping the plume now (with a drought emergency in effect) could lower the water table to a level that would interfere with the yield from public water supply wells. Therefore, ATSDR and PADOH will wait until that ROD is finished before commenting on it. In any event, no current exposure through contaminated groundwater threatens area citizens.
On February 7, 2002, J.E. Godfrey of PADOH visited the site and surrounding area. The site was similar to its condition in 1997, except that much of the area behind the plant that was formerly orchard  had been replaced by single family homes (Figure 2). The on-site building is used to store antique race cars. Because groundwater is the only contaminated environmental medium, residents in the new homes are not at risk from exposure to TCE through air or soileven though some homes are constructed directly over a portion of the plume (see Discussion section below). All new homes are supplied with water from the borough's public water supply.
As previously stated , all affected businesses and homes have been connected to the Dublin Borough water supply. Therefore, no completed exposure pathways connect contaminated groundwater to drinking or bathing activities. During preparation of this health consultation, PADOH and ATSDR inquired whether the EPA evaluated potential exposure risks from indoor air in homes (with basements) that were built over the contaminant plume. A plume concentration contour map in the PPHA indicates that the new construction was over the part of the plume (cross-gradient from the plume axes) containing less than 10 ppb TCE [3,4]. Later sampling from (newer) monitoring wells constructed in 1994 confirmed that fact , and water level measurements in those same wells indicated a water table depth of about 30 feet. EPA evaluated the groundwater-to-air exposure medium using the Farmer model  and, considering all environmental data and the results of the model, determined that houses built over the plume posed no hazard to residents living in them.
ATSDR and PADOH recognize that when encountering contaminated soil, air, or water, infants and children can be more sensitive than adults. Children are smaller than adults, resulting in higher doses of chemical per unit of body weight. They are shorter, and therefore closer to the ground, where they can breathe more dust and heavy vapors. Also, the developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Therefore, ATSDR and PADOH have evaluated children's special interests at the Dublin TCE site, and have determined that no completed exposure pathways exist that could pose special risks for children.
The Dublin TCE Site poses no public health hazard to Borough residents and visitors. All previously affected homes and businesses, and all newly built homes, are connected to the public water supply serving the town. EPA is in the process of writing a ROD for OU 2 which is expected to address plume containment and eliminate future potential exposures.
No recommendations to protect public health are needed at this time.
ATSDR and PADOH will review the ROD for OU2 when it is presented for public comment.
1. Agency for Toxic Substances and Disease Registry. 1997. Site review and update, Dublin TCE Site, Bucks County, Pennsylvania. Atlanta: U.S. Department of Health and Human Services.
2. United States Environmental Protection Agency. 1991. Record of Decision, Dublin TCE Site. Philadelphia, PA.
3. Agency for Toxic Substances and Disease Registry. 1994. Preliminary public health assessment, Dublin Water Supply, Dublin, Bucks County, Pennsylvania. Atlanta: U.S. Department of Health and Human Services.
4. United States Environmental Protection Agency. 1996. Draft remedial Investigation/feasibility study report, Dublin NPL Site, Dublin, Pennsylvania. Philadelphia, PA.
5. United States Environmental Protection Agency. 1998. Memo dated October 6 from P.I. Flores-Brown to Dawn Ioven. Philadelphia, PA.
J. E. Godfrey, P.G.
Pennsylvania Department of Health
This Dublin TCE Lead Site Health Consultation has been prepared by the Pennsylvania Department of Health under cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was initiated.
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this health consultation and concurs with its findings.
Richard E. Gillig
Chief, SPS, SSAB, DHAC, ATSDR