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The Naval Air Warfare Center (NAWC) (formerly the Naval Air Development Center) is a 734-acre facility located approximately 28 miles northeast of Philadelphia, Pennsylvania. The Department of Defense closed NAWC in September 1996 under the Base Realignment and Closure program. Before closure of NAWC, the Navy conducted research, development, testing, and evaluation of Naval aircraft systems at the base. NAWC is now undergoing redevelopment with future uses including residential areas, parks and recreational facilities, and commercial businesses.

In 1979, chlorinated solvents were found in off-base and on-base water supply wells. This discovery prompted investigations of NAWC and surrounding industries. At NAWC, past spills and releases, hazardous waste management practices, waste disposal activities, and base operations were identified as potential sources of contamination. In October 1989, NAWC was listed on the National Priorities List. This action was based on the potential for contaminants to affect groundwater and surface water.

In preparing this public health assessment (PHA), ATSDR obtained data from NAWC, the U.S. Environmental Protection Agency (EPA), the Pennsylvania Department of Environmental Protection (PADEP), the U.S. Geological Survey, and local water suppliers. ATSDR also spoke with community members about their health concerns. Based on a review of available data and discussions with community members, ATSDR evaluated contaminants in groundwater, surface soil, surface water, and sediment for their potential to reach people (exposure) and cause health effects and assessed possible effects from exposure to lead and lead paint in on-base housing.

Past activities at NAWC released volatile organic compounds (VOCs) into groundwater underlying the base. This contamination affected NAWC wells and migrated beyond NAWC boundaries to affect municipal supply wells and private wells serving surrounding residences and businesses. ATSDR evaluated past exposures based on conservative assumptions that overestimate potential exposures. ATSDR evaluation concluded that contaminant levels were too low to cause adverse public health effects. The Navy and municipal water authorities closed impacted wells as soon as contamination was identified. One municipal well was re-opened with a treatment system in place. The municipal water authorities regularly sample water supply wells to ensure the safety of the water supply. Upon discovering VOCs in private wells in 1993, the Navy immediately began providing bottled water to homes with contaminants detected above EPA's maximum contaminant levels (MCLs). These homes were then provided with treatment systems and connected to municipal water supplies in 1995. To prevent current and future exposures, the Navy installed a water treatment system to remove groundwater contamination underlying NAWC and conducts regular monitoring to ensure that groundwater in surrounding neighborhoods is not compromised further. Residential well owners who remain concerned about contamination in groundwater can consider connecting their homes to tested municipal drinking water supplies, sampling their own private wells or, in areas of known contamination, installing and maintaining treatment systems. Based on past exposures, conservatively estimated exposure doses, and actions conducted or planned to prevent additional exposures, ATSDR concludes that past, current, and future exposures to contaminants through use of groundwater as a drinking water supply are too low to cause illness or other adverse health effects. Possible health effects resulting from exposures to contaminants found in one public water supply prior to 1979, however, were indeterminate because information about contaminants and concentrations leading to well closures are unknown.

Soil contamination from past activities at NAWC, such as waste disposal, fire-fighting training, and spills, was detected at nine sites during base investigations. Surface soil contaminants included polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dioxins, and metals. Of these nine sites, eight are located in industrial, research, or airfield portions of the base where access was restricted by perimeter fences, warning signs, and, while NAWC was active, gate guards and security patrols. Exposures in restricted areas of the base were limited to on-base employees. On-base employees working in these areas are expected to have worn long pants, work gloves, and work boots to reduce exposures. The Navy has completed remedial actions at these sites to prevent current and potential future exposure. One area of contaminated soil is located within an on-base housing complex (Shenandoah Woods). After the Site 5 landfill was closed, two buildings in Shenandoah Woods were partially built on the landfill. Investigations at Site 5 found contaminants in a small number of surface soil samples. Therefore, on-base residents may have contacted surface soil contaminants during outdoor activities. Because levels of contaminants were low, contaminants were found in isolated areas, and exposure was most likely intermittent, ATSDR's evaluation did not identify any past or current exposures at Shenandoah Woods that might result in adverse health effects. Based on potential exposures and conservatively estimated exposure doses, ATSDR concludes that past, current, and future contact with surface soil is not expected to cause illness or other adverse health effects.

Channels and streams draining surface water runoff from sites with soil contamination are located near the northwest, north, and south boundaries of NAWC. Investigations of these streams as they leave the base detected VOCs, PAHs, and metals in surface water and PAHs, PCBs, aldrin (a pesticide), and metals in sediment. These streams flow off-base into residential neighborhoods where adults and children may use the streams and adjacent areas for recreational activities such as walking, playing, or wading. Streams leaving the base are intermittent and surface water is present only part of the year; therefore, boating, swimming, and fishing are unlikely in the immediate vicinity of the drainage features. The Navy has completed remedial actions at sites with soil contaminants to prevent additional contaminant movement to the streams. The Navy conducts regular stream monitoring to track and prevent off-site movement of elevated contaminant concentrations. ATSDR's assessment did not identify any past, current, or future exposures that might result in adverse health effects. Based on potential exposures, conservatively estimated exposure doses, and planned monitoring activities, ATSDR concludes that exposures during recreational use of the streams are below levels that cause illness or other adverse health effects.

Lead and lead paint exposures present a unique health concern for unborn and preschool children. Because lead paint was commonly used in homes in the past and can be a source of lead exposures, ATSDR assessed possible effects from exposure to lead and lead paint in on-base housing. Sampling found no lead paint or dust in homes in the Shenandoah Woods housing complex. Lead in paint, dust, and/or soil was found in eight homes located in the officer housing area, Quarters A, and Quarters B. To prevent current and future exposures, the Navy completed removal and abatement actions at these homes. Lead paint was either removed or encapsulated, lead paint chips found at the foundation of residences were removed, and areas where lead concentrations in soil exceeded standards were remediated. Based on ATSDR's detailed evaluation of possible adverse health effects from past, current, and future exposures to lead in on-base housing, ATSDR concluded that past exposure to lead was not expected to result in adverse health effects in all homes except one. In Quarters A, lead exposures could have resulted in increased blood lead levels, however, possible adverse health effects are indeterminate because it is unknown if children and pregnant women lived in this home when lead was accessible.


Site Description

The Naval Air Warfare Center (NAWC), formerly the Naval Air Development Center, is located in Bucks County, Pennsylvania, approximately 28 miles northeast of Philadelphia. The majority of NAWC is in Warminster Township with smaller portions located in Northampton Township and Ivyland Borough (Figure 1). This 734-acre facility includes various buildings, paved roads, a runway and ramp area, mowed fields, and a small wooded area. NAWC is bordered by residential areas to the south and north, by industrial developments to the west and northwest, and by a golf course and open area to the east (Halliburton NUS 1992).

Operational History

Before World War II, the land where NAWC is located was used for farming. In 1941, this land was purchased by Brewster Aeronautical Corporation to manufacture military aircraft. The Navy assumed control of the plant in 1944 and installed the Naval Air Modification Unit to add modifications to military aircraft produced at other locations. After World War II, the main function of NAWC became research, development, testing, and evaluation of Naval aircraft systems. Anti-submarine warfare systems and software development also took place at the site. In 1992, the name of the facility changed from the Naval Air Development Center to the Naval Air Warfare Center, Aircraft Division, Warminster (EA Engineering 1995).

NAWC was closed in September 1996 following the Base Realignment and Closure (BRAC) program managed by the Department of Defense. With realignment, many of the activities conducted at NAWC were relocated to the Naval Air Warfare Center, Aircraft Division, Patuxent River, Maryland (Department of the Navy 1997b). Currently, NAWC is undergoing redevelopment. The Navy has maintained a small staff of personnel at NAWC to oversee the base redevelopment. Several facilities are occupied by businesses under interim base reuse plans. Two military housing areas are also occupied by military personnel and their families.

As a research center for Naval aircraft and anti-submarine warfare systems, and their associated software, NAWC generated a variety of industrial wastes. Wastes containing hazardous substances, such as paints, solvents, sludges Exiting ATSDR Website, and waste oils were generated during aircraft maintenance, pest control and pesticide application, fire-fighting training, machine shop operations, spray painting, and research and testing activities (Halliburton NUS 1992). Between 1940 and 1980, these wastes were disposed of in lagoons Exiting ATSDR Website, pits, trenches, and landfills on base property. Until 1988, waste fuel was burned in the fire training area (Brown & Root 1996c).

Remedial and Regulatory History

In 1979, the U.S. Environmental Protection Agency (EPA) began investigating NAWC. At that time, testing by the Navy indicated that the groundwater at NAWC was contaminated with volatile organic compounds (VOCs) including methylene chloride, toluene, trichloroethylene (TCE), 1,2-dichloroethene, chloroform, tetrachloroethylene (PCE), and 1,1,1-trichloroethane, as well as various heavy metals (beryllium, copper, lead, nickel, and zinc). In 1980, the Navy began further investigations of on-base groundwater contamination and potential sources (Halliburton NUS 1992).

In 1985, a Preliminary Assessment and Site Investigation was completed by EPA to determine if NAWC was a source of on-base and/or off-base groundwater contamination. Nine potential areas where contaminants may have been stored, released, or disposed at NAWC were evaluated. In addition to sources at NAWC, EPA identified an industrial area north of NAWC and two industrial sites south of NAWC as other possible sources of the chlorinated solvents found in groundwater during previous investigations (NUS Corporation 1985).

In 1986, the Pennsylvania Department of Environmental Protection (PADEP) inspected Sites 1 through 9 and recommended remedial action for Site 8, the fire-fighting training area. The recommended remedial action for Site 8 included excavating and disposing of contaminated soils and lining the excavated area to protect groundwater and surface water. In 1988, NAWC personnel indicated that the berms, residue, and soil were removed and deposited proximate to the fire-fighting training area. The area was regraded. Site 8 investigations encompassed the fire-fighting training area and surrounding areas (Halliburton NUS 1992; Brown & Root 1996c).

NAWC was placed on the National Priorities List (NPL) in October 1989 based on the potential for contaminants detected at NAWC to impact groundwater and surface water. An Interagency Agreement, which formalized and scheduled remedial investigations and activities for the site, was reached between EPA and the Navy in 1990 (Halliburton NUS 1992).

The Navy is conducting a long-term, phased approach to environmental cleanup at NAWC. The Phase I Remedial Investigation (RI) began in late 1989 and was completed in April 1991. The Phase I RI involved mapping VOCs (soil gas sampling, electromagnetic surveys, and soil borings), installing new monitoring wells, and sampling groundwater, surface water, and soil to confirm site contamination and characterize the extent of contamination throughout NAWC. (Halliburton NUS 1992).

The Phase II RI, which began in late 1991 and was completed in 1993, further investigated the type and extent of contamination, in addition to identifying possible remedial activities. Phase II investigations focused on groundwater impacts from waste areas. In addition to the site-wide Phase II RI, site-specific RIs were completed. In place of a RI, the Navy completed an Off-Base Well Inventory and Sample Analysis Report to address off-base groundwater contamination. In addition to identifying on-base sources of contamination, the Navy also identified off-base sources of groundwater contamination during the course of their investigations (Halliburton NUS 1992, 1993b).

The Phase III RI, which focused on soil, sediment, and surface water, was conducted from January 1995 through November 1996 to identify sites where further action was warranted and to help determine what these further actions should be. The Phase III RI included investigations of Areas A, B, and C, as designated during the Phase II RI. Area D was not included because no soil contamination was identified in this area during the Phase II RI. The Navy conducted additional investigations in 1999 to supplement the Phase III RI (Brown & Root 1996c; Department of the Navy 2000e).

As a result of investigations, the Navy divided NAWC into ten operable units (OUs). OU1, OU6, OU7, OU9, and OU10 address soil, groundwater, and surface water and sediment contamination associated with Sites 1, 2, 3, and the Impoundment Areas (referred to as Area A) and Sites 5, 6, and 7 (Area B). OU2 addresses potential off-site groundwater contamination. OU3 and OU5 address soil, groundwater, and surface water and sediment contamination associated with Sites 4, 8, the Maintenance Area, and the Tile Field (Area C). OU4 and OU8 address soil and groundwater contamination associated with Area D, located in the western portion of NAWC (Figure 2). Records of Decision (RODs) selecting remedial actions, if necessary, have been signed for each of these OUs, except OU2 which was addressed through a time critical remedial action (i.e. providing water treatment systems or municipal connections to homes with private wells) (Department of the Navy 2000e).

Appendix A, Table A-1 describes each OU, including individual sites, and summarizes previous investigations and remedial actions completed or planned. This table also describes off-base water supplies, including Warminster Municipal Water Authority (WMWA) Well 26 and private wells in the Ivyland/Kirk Road neighborhood, that have been impacted by NAWC contamination. The Agency for Toxic Substances and Disease Registry (ATSDR) used information from previous investigations and remedial actions to evaluate the potential for public exposure to contaminants and the potential for adverse health effects resulting from exposures. A conclusion regarding potential public health hazards for each area of contamination found at NAWC is also presented in Appendix A, Table A-1. During the RI investigations, the Navy evaluated several municipal and private water supplies that were later found to be affected by sources other than NAWC. Appendix A, Table A-2 describes these water supplies and Navy investigations, as well as information regarding potential public health hazards.

ATSDR Involvement

ATSDR released a preliminary public health assessment (PHA) on January 17, 1989. ATSDR concluded that NAWC may be a potential public health concern because of the possibility of human contact with contaminants at the site (ATSDR 1992).

On July 29, 1991, ATSDR conducted an initial site scoping visit to evaluate site conditions. ATSDR recommended that the Navy conduct additional investigations to characterize site contamination (ATSDR 1992). ATSDR conducted another site visit from December 2 through 4, 1997. During these visits, ATSDR met with base environmental personnel, PADEP, the Bucks County Health Department, and community members, and performed a site walk over to identify potential pathways for human exposures to contamination.

As part of ongoing efforts to address concerns about groundwater contamination in the vicinity of NAWC, the Pennsylvania Department of Health (PADOH), in cooperation with ATSDR, has completed health consultations for several sites proximate to NAWC that have also been identified as sources of groundwater contamination. Most recently, PADOH completed health consultations for the Fischer & Porter manufacturing plant to the southwest and the Derewal Property to the south of NAWC. At the Fischer & Porter manufacturing plant, PADOH evaluated past exposure to TCE and PCE in groundwater and concluded that no adverse health effects would be expected. Exposure is no longer occurring. At the Derewal Property, PADOH evaluated past and current exposures to low levels of chloroform in private wells and concluded that continued use of private wells should not harm the health of the users (ATSDR 1999a; PADOH 1999).

Land Use and Demographics

Surrounding Community

Prior to World War II, the land where NAWC is located was used for farming. Since World War II, the area has experienced continuous population growth and is now primarily residential with few rural areas remaining. Some commercial and industrial developments are located to the west and northwest of the base. Housing developments, residential neighborhoods, and a golf course surround NAWC along the northern, eastern, and southern base boundaries. The closest off-base home is less than 50 feet from the NAWC boundary (Halliburton NUS 1992).

In 1992, the Bucks County Planning Commission estimated the population size for communities surrounding NAWC as (Halliburton NUS 1994a):

Warminster Township - 33,081
Northampton Township - 35,453
Upper Southampton Township - 16,046
Ivyland Borough - 488

ATSDR identified five residential neighborhoods located proximate to NAWC. The Ivyland/Kirk Road neighborhood (also referred to as Area 1, North) is located north of the base and encompasses portions of Warminster and Ivyland. There are approximately 1,300 residents in this neighborhood. The Speedway neighborhood (Area 1, South) is located west of the base within Warminster and houses approximately 500 residents. The Casey Village (Area 2, East) and Flying Heels (Area 2, West) neighborhoods are located south of the base within portions of Warminster and Upper Southampton. Casey Village has approximately 750 residents and Flying Heels has approximately 1,650 residents. The Stonybrook Homes area is located along the southwestern NAWC boundary in Warminster and has approximately 4,300 residents (1990 Census of Population and Housing 1991). Each of these neighborhoods is shown on Figure 2. Demographic information is provided in Figure 3 and Table 1.


NAWC is currently an inactive base undergoing redevelopment under the BRAC program. Future land uses at each site are discussed in Appendix A, Table A-1. Until September 1999, access was limited by perimeter fences, gate guards, and roving patrols. Currently, Navy personnel overseeing the base redevelopment conduct daily inspections and work with the local police departments to prevent unauthorized use of the base (Ames 1999, 2000).

Approximately 1,850 civilians and 1,000 military personnel were employed at NAWC in 1994 (Halliburton NUS 1992). At peak operation, NAWC employed 2,800 civilians, 200 military personnel, and up to 300 daily contractors (Ames 1999). Approximately 500 people now work at the site either in caretaker positions or at new jobs created through interim base reuse (Ames 1998, 2000).

Approximately 800 to 1,000 military personnel and their families stationed at nearby Willow Grove Naval Air Station currently live in two on-base housing areas at NAWC (Ames 1998). Willow Grove Naval Air Station is a joint Navy and Air Force base that provides administrative and logistical support to reserve units. This facility is located several miles west of NAWC (Figure 1). Officer housing is located in the northwestern portion of NAWC near the intersection of Jacksonville and Kirk Roads. As many as six families may reside in this area. No potential areas of contamination have been identified in the Officer housing area. Enlisted housing, referred to as the Shenandoah Woods housing complex, is located in the southern portion of NAWC. Between 450 and 550 military personnel and their families reside in this housing complex. Site 5, a former landfill, is located near two multifamily housing units within the Shenandoah Woods housing complex.

Quarters A and B are located in the northern portion of NAWC within Area C and in the southern portion of NAWC west of Area B, respectively. These quarters are former farm houses that provided housing for the commanding officer and the second-in-command at NAWC. These homes are currently vacant. No areas of surface contamination have been identified near Quarters A or B; however, groundwater contamination associated with Area C underlies Quarters A (Halliburton NUS 1992; Ames 1999).

Quality Assurance and Quality Control

In preparing this PHA, ATSDR reviewed and evaluated information provided in the referenced documents. Documents prepared for the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Resource Conservation and Recovery Act (RCRA) programs must meet specific standards for adequate quality assurance and control measures for chain-of-custody procedures, laboratory procedures, and data reporting. The environmental data presented in this PHA are from site characterization, remedial investigation, and groundwater monitoring reports prepared by EPA, the U.S. Geological Survey (USGS), and the Navy under CERCLA and RCRA.

Several of these documents, however, are undergoing review by the Restoration Advisory Board (RAB), a group of community members and regulators that provides input to the Navy through the various steps of the environmental remediation process. RAB members, the Navy, and EPA have not reached a consensus about contamination sources. Specifically, there is concern about the conclusion that sources located beyond base boundaries are responsible for groundwater contamination found in municipal wells and neighborhoods adjacent to NAWC. ATSDR discusses groundwater contamination resulting from both Navy and off-base sources to address this concern.

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