24 Bases with reported TCE water contamination
(Source: Agency for Toxic Substances and Disease Registry)

Naval Air Development Center

Warminster Township, PA

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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.
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).


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