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PRELIMINARY PUBLIC HEALTH ASSESSMENT

DUBLIN WATER SUPPLY
DUBLIN, BUCKS COUNTY, PENNSYLVANIA



SUMMARY

The Dublin TCE Site (formerly the Dublin Water Supply Site) is a National Priorities List Update 10 site located at 120 Mill Street in Dublin Borough, Bucks County, Pennsylvania. The site consists of a 1-story brick building on approximately four and one-half acres of land surrounded on all sides by private property or a public street. Dublin, with an estimated population of about 1,800 people, is approximately 25 miles north of Philadelphia.

Water availability for Dublin is primarily groundwater through use of private and public wells, both shallow and deep. During a routine drinking water survey in 1986, the Bucks County Health Department discovered elevated levels of trichloroethylene (TCE) in tap water samples obtained in the Dublin Borough area. This finding led to additional investigation of the problem and a determination that the property located at 120 Mill Street was the most likely source of the Dublin TCE contamination. As a result of government health advisories and a Consent Agreement between the owner of the 120 Mill Street property and the U.S. Environmental Protection Agency (EPA), drinking water supplies that were known to be contaminated were treated and monitored in order to reduce exposure to the people using the water. In 1986, it was determined that the highest concentrations of TCE were associated with the 120 Mill Street property and that the contaminated groundwater plume was approximately 2,600 feet long and 1,600 feet wide. Several residential apartments, residences, and small businesses are within 0.25 miles of the site. In 1986, it was estimated that the TCE groundwater pollution affected about 500 residents. More residents have been affected as a result of contaminants moving into their drinking water supplies, and EPA has extended the area monitored to include those wells.

The site posed a public health hazard prior to treatment of water supplies. Currently, the site is an indeterminate health hazard because the moving groundwater plume is still under study. A Record of Decision (ROD) was issued on December 30, 1991, for the Dublin TCE Site, Alternate Water Supply Operable Unit. The ROD provides for treating a water supply well within the plume of contamination by an air stripping and vapor phase carbon adsorption system to supply treated water to the public water supply system, expanding the existing Dublin Borough public water distribution system to affected and potentially affected residences and businesses, monitoring of residential and commercial wells not addressed by the public water supply but which may be threatened, and operating and maintaining the selected remedy. The design of the waterline to carry public water to affected residences and businesses has been approved. Construction of the waterline is expected to begin in late winter or spring of 1994. A separate ROD will be issued to address Operable Unit Two, investigation and remediation of the groundwater, surface water, and soil at the site. That investigation is currently underway.

The Pennsylvania Department of Health (PADOH) conducted this preliminary health assessment based on the data obtained by EPA, the Department of Environmental Resources (DER), and PADOH's Southeastern Health District. Preliminary and Final Phase I Remedial Investigation (RI) and Preliminary and Final Phase II RI were not available at the time of this public health assessment. Upon receipt of the completed Final Phase I and II RI, PADOH will reevaluate conditions at the site.

Information from the Dublin TCE site, Bucks County, Pennsylvania, has been evaluated for appropriate follow-up with respect to health actions by the Agency for Toxic Substances and Disease Registry's (ATSDR) Health Activities Recommendation Panel (HARP). HARP determined that past exposure to contaminants at levels of public health concern has occurred and that current and future exposure to contaminants at levels of public health concern is possible. HARP determined that people known to have been exposed to TCE should be considered for inclusion on the National Exposure Registry--TCE Subregistry. Community and health care provider education are indicated. ATSDR will reevaluate this site for additional follow-up public health actions if new data become available that indicate a need to do so.

A public health action plan for the Dublin TCE site has been developed to ensure that actions are taken to help the community and protect the public health. The plan includes the following commitments:

In order to help the community better understand the implications of their exposure, PADOH, with the assistance of ATSDR, will provide community health education.

In order to help the health care providers in the Dublin community better understand the possible health implications of exposure to people in the area, PADOH, with the assistance of ATSDR, will provide information to area health care providers.

ATSDR's Division of Health Studies will review the information in this public health assessment and consider the request of the community for a health study. Considerations will include whether appropriate tests are available that will benefit the community and whether resources are available to conduct such tests.

PADOH will conduct a Site Review and Update, or other appropriate follow-up, in late 1994 or early 1995 when more data are available on the current status of drinking water quality in the area and on current conditions at the site. If data become available before that time that indicate exposures are occurring at levels of health concern, ATSDR will evaluate that information and determine what actions need to implemented to protect the public health.

Currently, the National Exposure Registry--TCE Subregistry is closed. ATSDR will consider including members of the exposed community on the TCE subregistry should a need for additional members arise.

BACKGROUND

A. SITE DESCRIPTION AND HISTORY

During a routine drinking water survey in 1986, the Bucks County Health Department (BCHD) discovered elevated levels of trichloroethylene (TCE) in tap water samples obtained from the Dublin Borough area, Bucks County, Pennsylvania (1-3). Sixty-one tap water samples were collected from June to September 1986, and the analyses of these samples provided data for three specific chemicals: 1,1,1-trichloroethane (1,1,1-TCA), tetrachloroethylene (PCE), and TCE. High levels of TCE were found in an industrial water supply, in residential water supplies, and in commercial water supplies (see Environmental Contamination and Other Hazards section). Private and public water wells are the primary drinking water source for people in Dublin. In 1986, both shallow and deep wells appeared to be contaminated with TCE. Elevated TCE levels (greater than 5 parts per billion (ppb)) were identified at approximately 170 homes, apartments, and businesses, thereby affecting an estimated 500 residents. Many of these individuals were residents of the Whistlewood Apartments, which has 144 units.

BCHD issued several health advisories concerning contaminated groundwater use. In 1986, the local health authorities implemented or recommended that drinking water supplies be treated by air strippers, charcoal treatment systems, water boiling, or not at all for some locations. The air stripper devices and the charcoal treatment units that have been installed treat the TCE-contaminated water so that people can use the water for any purpose. BCHD also recommended that carbon filters be used on water supplies with TCE levels above 5 ppb and that residents not bathe in water containing TCE at 500 ppb or more.

EPA Region III Emergency Response Section received the BCHD data for evaluation on September 3, 1986 (1). The EPA On-Scene Coordinator and his technical staff identified the current water usage status of all residential and public wells with elevated TCE levels. A meeting between EPA, the EPA Technical Assistance Team contractor, and BCHD was held on September 12, 1986, to obtain additional information in order to develop a coordinated approach by the respective agencies.

Following this meeting, a tour was conducted to make observations to locate the source of the TCE contamination. In October 1986, ATSDR developed a written health consultation on the "Dublin Water Supply Site" (3) in response to a request from EPA Region III to review analytical results for TCE in tap water samples obtained from the Dublin area. EPA had requested a health evaluation, specific recommendations, and action levels for drinking, cooking, and bathing.

In the 1986 health consultation, ATSDR stated the following six conclusions: (1) ATSDR believes that an imminent health threat exists, based upon the data provided, to that population being exposed to significant levels of TCE in the local groundwaters; (2) in order to provide lifetime protection from the toxic properties of TCE, waters used for all purposes (i.e., drinking, bathing, showering, and cooking) should contain less than 130 µg/L TCE; (3) in order to provide lifetime protection from the toxic properties of TCE, waters used only for drinking should contain less than 260 µg/L TCE; (4) in order to reduce the estimated excess lifetime cancer risk posed by using TCE-contaminated water for the long term, waters used for drinking, bathing, showering, and cooking should probably contain less than 5 µg/L TCE (this level corresponds to about a 1 x 10-6 excess lifetime cancer risk from drinking water only); (5) the full extent of contamination of TCE and other contaminants in the local groundwater resources has not been characterized; and (6) the length of time that local residents have been using contaminated water cannot be determined from the information provided (to ATSDR).

ATSDR also made the following 10 recommendations in the 1986 report: (1) immediately protect public health by preventing any further use of potable water containing TCE concentrations equal to or greater than 260 µg/L; (2) protect the public health by preventing any long-term use of potable water containing TCE concentrations equal to or greater than 130 µg/L (this value corresponds to an excess lifetime cancer risk of 1 x 10-4); (3) determine and monitor all local private and public wells that could be potentially affected by the site or the groundwater contamination plume; (4) determine the extent of contamination due to TCE and possibly other contaminants in the local groundwater resources; (5) to ensure continued protection of public health and adequate removal of volatile organic chemicals, verify that short-term treatment devices have been properly installed and maintained; (6) to determine present environmental levels of exposure and the efficiency of the treatment devices to satisfactorily remove contaminants, monitor all treated waters used for drinking and other purposes until a long-term solution is achieved; (7) to ensure protection of public health, monitor the "supplied waters," and tap waters of affected water supplies where residents use contaminated groundwaters for uses other than drinking or where residents still use groundwaters for consumption without approved treatment; (8) to assist in determining the significance of chronic exposure from showering with local TCE-contaminated water, collect air samples of bathroom air during showers and possibly other environmental samples in those residences that have elevated TCE levels (i.e., greater than 130 µg/L) in their well water; (9) develop and implement a long-term plan to protect all affected water supplies containing TCE concentrations equal to or greater than 5 µg/L; and (10) consider implementing actions in accordance with the recommended time frames discussed in the attached tables (see Appendix A - Table III in ATSDR report) for the specified TCE levels (these recommended time frames are to protect the public from chronic toxicity and from an excess lifetime cancer risk, no matter how the water is used).

On October 20, 1986, a meeting was held at the BCHD Offices in Doylestown. Attendees at the meeting included representatives of BCHD, DER, EPA Region III CERCLA Removal Enforcement Section, and attorneys representing the owner of the property located at 120 Mill Street. The purpose of the meeting was to present the most recent groundwater sampling data from residents' wells in Dublin Borough and to determine what action may be needed to address the source of TCE contamination in the Borough's water supply. In a November 6, 1986, follow-up letter, EPA identified the property as the most likely source of the Dublin TCE contamination and identified the owner as the potentially responsible party (PRP). Over the past four decades, the site has been owned by several entities (i.e., corporation and individuals). EPA further pointed out that the present lack of oversight of TCE levels in residents' water supplies represented an imminent threat to their health. DER also notified the owner in a November 12, 1986, letter (5) that a BCHD investigation of numerous wells during the summer of 1986 indicated that the site well yielded the highest TCE level (10,000 ppb). The investigation also showed that partial drums of degreasing solvents containing TCE were stored on the property and that, based on interviews with personnel currently employed at the site, the previous occupiers used degreasing solvents.

In June 1987, a Consent Agreement and Order (6a) was signed by EPA and the owner of the property located at 120 Mill Street in Dublin Borough, which was then referred to in the Consent Order as the "Dublin TCE Site" or "the site." According to the Consent Agreement, the owner agreed to take action to assure that all residents and commercial employees exposed to TCE levels greater than 5 ppb have an adequate treatment system in place, to provide periodic monitoring of all present treatment systems to assure that they are functioning properly, and to conduct periodic groundwater monitoring of wells for all residents at risk in accordance with the work plan, attached as Exhibit I in the Consent Agreement. In the work plan, EPA established four categories, or tiers, to guide appropriate action for each well. Each tier addresses a TCE concentration range and appropriate corrective action and follow-up monitoring. The EPA work plan (see Appendix B) includes a description of the tier approach as well as the steps to be taken to implement the various phases of the work plan. The EPA tier approach is a modified version of the ATSDR approach described in Appendix A. The owner began to implement the work plan shortly after the signing of the consent order in June 1987.

An assessment conducted in 1988 by an EPA contractor (7) of source contamination noted that TCE, 1,1,1-TCA, and PCE escaped from the property and entered the environment through improper industrial practices. The assessment noted that chemicals were used as solvents at the property as early as mid-1959. During the period 1950-1971, it was noted that solvents were used in a degreasing machine and were dumped in small quantities on the macadam behind the building near a storm sewer inlet; waste solvent was kept in 55-gallon drums behind the main building; and TCE and other solvents may have entered the on-site septic system, which was in use until approximately 1966. Representatives from Weston also conducted a site visit on January 21, 1988, to collect samples from old waste drums stored at the site, to collect soil samples, and to conduct other tests. One of the findings was that the containers of waste solvents left by Athlone contained significant concentrations of 1,1,1-TCA, TCE, and PCE.

The site was proposed for listing by EPA on the National Priorities List (NPL/Update 10) in October 1989 and finalized on the NPL in August 1990.

In August 1990, ATSDR developed a second health consultation on the "Dublin Water Supply Site" (11) in response to a request from EPA Region III to review March 1990 water quality data that are associated with the Dublin TCE site to determine if those levels of TCE groundwater contamination continue to represent a public health concern. EPA also requested that ATSDR evaluate a revised work plan for area residential and commercial wells affected by the TCE-contaminated groundwater plume to assure that proposed changes are protective of public health. In the 1990 health consultation, ATSDR indicated that the proposed changes outlined in the revised work plan and reviewed by ATSDR would, in general, be protective of public health.

ATSDR pointed out, however, that the use of carbon filtration systems as a long-term solution to the health concerns posed by high levels of TCE in water supplies may not be the safest approach. Other carbon filtration systems can support the growth of potentially harmful bacteria, which can find their way into the household water supplies. Improper operation and maintenance can result in contaminant breakthrough and carbon channeling, which can result in contamination of the water supply.

Another concern posed in the health consultation is whether or not the point-of-use filtration systems installed in TIER II level residences (see Appendix B for definition of Tier II) will effectively eliminate concerns about inhalation of TCE that would volatilize from non-filtered water taps. Also, ingestion of contaminated water from non-filtered water taps in residences and businesses may also be a concern. In October 1990, a telephone conference was held with representatives of EPA, PADOH, and ATSDR (6b) regarding the conclusions and recommendations made by ATSDR. In 1991, EPA issued an amendment to the 1987 Consent Agreement. The amendment provided for full house treatment systems for residences only. Businesses still receive tap systems or bottled water if they have TCE levels greater than 5 ppb in their well water. Additionally, EPA has extended the area monitored to include other private wells that are now showing low levels of contamination in order to ensure all affected wells are identified and receive the proper treatment system if indicated.

A Record of Decision (ROD) was issued on December 30, 1991, for the Dublin TCE Site, Alternate Water Supply Operable Unit. The ROD provides for a permanent measure to supply people with contaminated wells with clean water. The ROD describes the treatment of a water supply well within the plume of contamination by an air stripping and vapor phase carbon adsorption system to supply treated water to the public water supply system, expansion of the existing Dublin Borough public water distribution system to affected and potentially affected residences and businesses, monitoring of residential and commercial wells not addressed by the public water supply but may be threatened, and operation and maintenance of the selected remedy. The design of the waterline to distribute public water to affected residences and businesses has been approved. Construction is expected to begin in late winter or early spring 1994. A separate ROD will be issued to address Operable Unit Two, investigation and remediation of the groundwater, surface water, and soil at the site. That investigation is currently underway.

B. SITE VISIT

The Dublin TCE Site was visited on January 26, 1990, by personnel from PADOH, ATSDR, EPA, Dublin Borough, and representatives of other interested groups. The site visit consisted of a tour of the property at 120 Mill Street ("Dublin TCE Site"), the Borough Headquarters to discuss past, current, and future plans by EPA and others, and a general tour of the Borough to view areas which may have been impacted by the groundwater TCE contamination. The site visit concluded with a tour of the Whistlewood Apartment complex. The group viewed the property area which was described as the most likely source of the Dublin TCE contamination and inspected the water treatment facility (air stripper) being used at Whistlewood Apartments to remove TCE from the tenants' water supply.

There was no visual evidence of any contamination at the site and the site has unrestricted access. An apartment complex and numerous houses and businesses are located in areas over the groundwater plume, and there is a local apple orchard within close proximity of the site.

In discussions which took place throughout the site visit, it became clear that TCE exposure has been reduced for residents whose water has been tested and for whom a problem had been identified. There is, however, a continuing potential public health threat for residents whose water supplies are currently contaminated due to TCE contamination (and are unaware of the problem) or whose water supplies are currently safe but in danger of becoming contaminated because of movement of the contaminated groundwater plume.

On January 13, 1994, Mark Lavin and William Schmeer of PADOH visited the Dublin TCE site to assess current conditions. The site is currently used by two organizations, Thompson Racing and Laboratory Testing, Inc. The site is unrestricted, except for the buildings. The closest residence is about 100 yards northeast of the site. The orchard to the northwest appears to be well maintained and is likely productive during growing season. A large, black canister at the rear of Building 1 contains stored water from a pump test.

The PADOH team also visited the Whistlewood Apartment complex, which is north of the site. The team observed and photographed the existing air stripping tower that treats the well water for the 144-unit complex. The team also contacted the Dublin Borough secretary to ask if any people using private wells have connected their residences to the Borough's uncontaminated water system because of private well contamination. She indicated that no such connections have been made and that none will be made until PADER and EPA project approvals are finalized.

C. DEMOGRAPHICS, LAND USE, AND NATURAL RESOURCE USE

Dublin Borough is located in northern Bucks County approximately 25 miles north of Philadelphia, Pennsylvania. The Borough is bordered by Bedminster Township to the east and Hilltown Township to the west. There are presently an estimated 1,800 people living in the Borough of Dublin. The potable water supply for the Dublin community is primarily groundwater through private and public wells, both shallow and deep.

The "Dublin TCE Site" consists of a one story brick building on approximately four and one-half acres of land, which is surrounded on all sides by private property or a public street (see maps in Appendix C), and the extent of the contaminated groundwater plume. The property has been occupied by a succession of industrial operations for over 40 years.

There is an apple orchard about 100 yards north of the site.

D. Health Outcome Data

Using state health data bases, special studies, or other relevant health outcome data bases, it may be possible to compare health outcome in areas around hazardous waste sites in Pennsylvania with the state as a whole. This section introduces these data bases and discusses their limitations. An evaluation of the usefulness of these health data as they relate to the Dublin TCE site is presented in the Public Health Implications section.

PADOH has maintained resident death records since 1903. However, the Pennsylvania Cancer Registry has collected cancer data for all areas of Pennsylvania only since 1984. Field representatives interact with local hospitals to audit the accuracy of all Pennsylvania Cancer Registry Report Form information. However, the mobility of the patients, the variance in compliance rates among hospitals, and the newness of the program create difficulty in collecting meaningful data of geographic areas smaller than the county level. The most recent report, published in September 1991, is entitled Cancer Incidence and Mortality in Pennsylvania, 1988. The report only presents data applicable at the county level (smallest geographic area). PADOH is unaware of the existence of any special studies or other relevant health outcome data bases associated with this site.

COMMUNITY HEALTH CONCERNS

In our discussion with the Dublin Borough officials, we learned that the residents of Dublin are concerned about the potential for their water supplies to become contaminated due to migration of TCE in the groundwater and any health impacts that may result from exposure to the contamination. These concerns are evaluated in the Public Health Implications section of this document.

This document was released for public comment on March 1, 1991. Comments received during, and after, the public comment release are addressed in the Attachment of this public health assessment.


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