PUBLIC HEALTH ASSESSMENT
FORT DIX (LANDFILL SITE)
WRIGHTSTOWN, BURLINGTON COUNTY, NEW JERSEY
In this section, ATSDR evaluates whether people were or are now exposed to contaminants originating from Fort Dix at levels that might pose a health hazard. A health hazard can only exist if all elements of an exposure pathway exist. These elements include a source of contamination, an environmental medium in which contaminants may be present, a point of human exposure, a route of human exposure (such as ingestion, inhalation, or skin contact), and a receptor population. Figure 4 illustrates the exposure evaluation process in more detail and Appendix A contains a glossary of environmental and health terms used in this document.
For each environmental medium under consideration (i.e., groundwater, soil, surface water, and sediment), ATSDR examines the types and concentrations of contaminants in the medium. ATSDR uses comparison values to screen contaminant concentrations in environmental media and to select contaminants for further evaluation. The comparison values include environmental media evaluation guides, reference dose media evaluation guides, cancer risk evaluation guides, and EPA's maximum contaminant levels (MCL). A description of the comparison values used in this public health assessment is provided in Appendix B.
Table 1 lists contaminants in each medium at Fort Dix that are present at levels greater than or equal to health-based comparison values. Contaminants at or below the comparison values are reasonably regarded as harmless. Because comparison values are designed to be many times lower than levels at which adverse health effects have been observed in experimental animal or human health studies, contaminants that exceed the comparison values would not necessarily be expected to produce adverse health effects.
This section evaluates potential exposure pathways at Fort Dix in more detail, considering data gathered and remedial activities conducted, to determine whether they represent, under site-related conditions, a threat to human health. Table 2 summarizes the potential exposure pathways discussed.
ATSDR made an initial site visit in May 1991 (ATSDR, 1991). During that visit, two potential exposure pathways were identified. The first pathway involves ingestion of contaminated groundwater. Populations potentially impacted by contaminated groundwater are off-post residents who use private drinking water wells that draw from the aquifer downgradient of Fort Dix. The second pathway involves dermal contact with and inhalation of radiologically contaminated soil. The population potentially impacted by radiologically contaminated soil is Fort Dix personnel conducting training in contaminated areas near the BOMARC site (ATSDR, 1991). No additional potential exposure pathways were identified during ATSDR's second site visit in April 1998.
The following discussion addresses the potential exposure pathway involving ingestion of contaminated groundwater. Although the BOMARC site is located on Fort Dix property, the contamination is the result of Air Force activity and the site is the Air Force's responsibility. The BOMARC site, therefore, will be addressed in an addendum.
After detailed review of available data, ATSDR concludes that contaminated water in the shallow aquifer beneath Fort Dix poses no public health hazard. This conclusion is based primarily on the fact that the groundwater is not used as a drinking water source in the vicinity of Fort Dix. Specifically:
- The Kirkwood-Cohansey Aquifer, the surficial aquifer under Fort Dix, has areas of contamination due to various activities performed at Fort Dix. Because this aquifer is not used as a public drinking water supply in the vicinity of Fort Dix, people are not exposed to this contamination.
- Fort Dix receives drinking water from surface water sources as well as groundwater sources. Groundwater that is used for drinking water at Fort Dix is drawn from aquifers deeper than the Kirkwood-Cohansey Aquifer. These water sources are not expected to be affected by contamination at Fort Dix.
- The majority of potable water used by surrounding communities is obtained from the deeper, uncontaminated aquifers.
- Only two nearby off-site private drinking water wells that draw from the Kirkwood-Cohansey Aquifer were identified during the remedial investigation. It does not appear, however, that contaminated groundwater at Fort Dix is or will be affecting these wells because they are not located downgradient from the contamination.
During environmental investigations at Fort Dix, groundwater samples were taken from the Kirkwood-Cohansey Aquifer. The groundwater in the aquifer was found to have areas that are contaminated with volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), and metals. The following sections discuss hydrogeology under Fort Dix, groundwater use, sources of drinking water, and groundwater quality, and provide further explanation as to why no public health hazards appear to exist.
There are five major aquifers in the Coastal Plain. Starting with the most shallow aquifer, they are: the Kirkwood-Cohansey Aquifer, the low 800-foot sand aquifer of the Kirkwood Formation, the Mt. Laurel-Wenonah Aquifer, the Englishtown Aquifer, and the Potomac-Raritan-Magothy Aquifer (Figure 2). These aquifers are separated by relatively impermeable units that vary in thickness and in their ability to function as confining layers, ranging from largely semi-confined to confined (ICF Kaiser, 1997). Due to the confining units separating the aquifers, water does not tend to move from one aquifer to another. The Vincetown Formation is included in the confining unit that separates the Kirkwood-Cohansey Aquifer from the deeper aquifers.
Groundwater in the shallow aquifers discharges where the water table intersects the surface of the ground, creating a surface water body or seep. General groundwater movement is toward lowland areas where water is discharged to Crosswick Creek, Rancocas Creek, and minor tributaries. As such, shallow groundwater flow directions are variable, often pointing toward the nearest stream (ICF Kaiser, 1997; KEMRON, 1997a).
No public drinking water supply wells are drawn from the Kirkwood-Cohansey Aquifer in the vicinity of Fort Dix (Camp Dresser, 1986). This aquifer, however, is used as a major drinking water source in the Toms River area of New Jersey, approximately 15 miles east of Fort Dix. The composite confining unit separating the Kirkwood-Cohansey Aquifer and the deeper Mt. Laurel-Wenonah Aquifer includes the Vincetown and Manasquan Formations, which may locally serve as sources of water. In central Ocean County, the Manasquan Formation is used as a water supply aquifer (ABB, 1997a).
The deeper aquifers are more productive than the Kirkwood-Cohansey Aquifer (Camp Dresser, 1986). The Mt. Laurel-Wenonah Aquifer is a major water supply aquifer. The Englishtown Aquifer lies beneath the Mt. Laurel-Wenonah Aquifer and is tapped for minor water supplies. Below the Englishtown Aquifer lies the Potomac-Raritan-Magothy Aquifer, which is the most important and productive aquifer in Burlington County (ICF Kaiser, 1997).
Drinking Water Sources
Potable water in the Fort Dix area is derived from surface water and groundwater sources. Potable surface water at Fort Dix is supplied from Greenwood Branch, which is a tributary of the North Branch of Rancocas Creek. Water is pumped through the water supply intake works at New Lisbon to the Fort Dix Water Filtration Plant, where it is treated and then released into the installation's water supply network. Due to its location relative to Fort Dix and the North Branch of Rancocas Creek, Greenwood Branch is not likely to be affected by groundwater quality in the surficial aquifer at Fort Dix (ICF Kaiser, 1997).
Besides Fort Dix, there is no known private or public potable use of surface water resources in the immediate vicinity of the installation, although farmlands may occasionally divert water for irrigation purposes. The surrounding communities primarily use groundwater from the deeper aquifers as a source of potable water (ICF Kaiser, 1997).
The surface water supply at Fort Dix is supplemented with groundwater from five drinking water wells located throughout the Cantonment Area (Figure 5, WW #1, 2, 4, 5, and 6). Well water is chlorinated and then pumped into the Fort Dix distribution network. Water from two of the five wells (WW #5 and 6) is also subject to iron and manganese removal (ICF Kaiser, 1997). These wells all draw from the deeper Raritan-Magothy Formation.
Numerous private wells and a few municipal wells are located in communities around Fort Dix. Detailed information on the exact location and the formations in which the wells are screened were only available for a few wells, however. These wells were identified using data from the Division of Water Resources of the New Jersey Department of Environmental Protection, the Burlington County Department of Health, and Pemberton Township (ICF Kaiser, 1997). Two private wells in the town of Browns Mills, wells 203 and 208, were identified as being screened in the Vincetown and Kirkwood Formations, respectively (Figure 5).
The Kirkwood-Cohansey Aquifer is used as a drinking water source in Toms River, Ocean County, New Jersey. Toms River lies approximately 15 miles east of Fort Dix. In a separate document, ATSDR has evaluated the potential impact of the Reich Farm Superfund site on the groundwater at Toms River; the reader is referred to the PHA for Reich Farms, Dover Township, New Jersey (ATSDR, 1989).
Groundwater Quality and Private Well Use
Data collected during the remedial investigation at Fort Dix do not indicate than any groundwater contamination has migrated off site. ATSDR evaluated sites that could potentially affect the nearby off-site private wells.
Wells 203 and 208 are located east of the Cantonment and Training Areas and south of the western end of the Range and Impact Area (Figure 5). The following Fort Dix sites are located in the vicinity of these wells: the Range Impact Area (FTDX-08), the Fort Dix Sanitary Landfill (FTDX-10), the Hazardous Waste Storage Area (FTDX-27), the PCB Transformer Storage Area (FTDX-29), and the PBAS Basin (FTDX-32). No groundwater data are available for the Range Impact Area, the PCB Transformer Storage Area, or the PBAS Basin site.
At the Hazardous Waste Storage Area (FTDX-27), no SVOCs or pesticides were detected in groundwater; no VOCs were detected above comparison values (Table 1). Lead was detected in groundwater between 1.52 and 2.6 parts per billion (ppb), which is slightly above EPA's MCL goal of 0 ppb but below EPA's action level for lead in drinking water of 15 ppb. Groundwater flow from this site was determined to be to the southeast. The Hazardous Waste Storage Area is located north of well 208 and northeast of well 203, therefore, groundwater from this site is not expected to affect either of these wells.
Groundwater at the Fort Dix Sanitary Landfill (FTDX-10) is contaminated with VOCs, SVOCs, and metals at levels above comparison values (Table 1). In 1986, trichloroethylene (TCE) was detected at up to 11 ppb in a monitoring well that draws from the Vincetown Formation. This concentration is above ATSDR's cancer risk evaluation guide of 3 ppb and the MCL of 5 ppb. Because no other VOCs were detected in the monitoring well, however, the source of the TCE is suspect (Camp Dresser, 1987). Groundwater flow patterns appear to be in a south-southeast direction at the toe of the landfill and southwesterly toward the swamp to the west of the landfill (Camp Dresser, 1986). Wells 203 and 208 are located to the east-northeast of the landfill; therefore, no groundwater contamination from the Fort Dix Sanitary Landfill is expected to affect these wells. Furthermore, contaminated groundwater does not flow south of the groundwater divide that exists south of the landfill. Therefore, potential off-site wells that draw from the surficial aquifer southwest of the landfill are not expected to be affected by the Fort Dix Sanitary Landfill (Camp Dresser, 1986).
Although areas of the surficial aquifer underlying Fort Dix are contaminated with VOCs, SVOCs, and metals, the aquifer is not used as a public drinking water supply in the vicinity of Fort Dix. Furthermore, it does not appear that contamination from Fort Dix has migrated off site. The two private wells that were identified as drawing from the Kirkwood-Cohansey aquifer do not appear to be affected and are not expected to be affected by contamination from Fort Dix. Because no exposure pathway exists, ATSDR concludes that no public health hazards exist from groundwater at Fort Dix.
A community relations plan (CRP) at Fort Dix was developed during the IRP program to establish communication and information exchange between Fort Dix and the civilian work force, the Army, various federal, state, county, and community agencies, and the public (ICF Kaiser, 1994). As part of the CRP, 22 community interviews with business leaders, community leaders, citizens living in the vicinity of Fort Dix, and family members living on post were conducted in 1988. The main concern identified was the possibility that past waste disposal practices may have affected the quality of groundwater in the vicinity of Fort Dix. Other public health concerns included soil contamination, surface water contamination, air pollution, and the BOMARC site.
During ATSDR's 1991 site visit, local health authorities expressed concern about the solid waste incinerator's (Resource Recovery Facility, formerly Municipal Incinerator, Site FTDX-03) consistent failure to meet metals emissions standards and about groundwater contamination from a solvent disposal pit known as MAG-1 (Site FTDX-07). Also in 1991, the Pinelands Commission, a regional planning and preservation agency, expressed concerns about groundwater contamination at the Fort Dix Sanitary Landfill (Site FTDX-10; ATSDR, 1991). As part of the site visit process, ATSDR contacted members of the Restoration Advisory Board (RAB) during the 1998 site visit. No additional community concerns were presented by RAB members. During the review of BRAC documents during this public health assessment, ATSDR identified a potential health concern regarding UXO on Fort Dix.
ATSDR evaluated soil, sediment, surface water, and groundwater data at all IRP sites at Fort Dix. The results of these analyses are presented in Table 1. No additional potential pathways of exposure were identified during this evaluation. Analysis of a potential human exposure pathway via groundwater at Fort Dix is presented in the Evaluation of Environmental Contamination and Potential Exposure Pathways section. As mentioned above, the BOMARC site will be evaluated in a separate document. The following discussions involve the solid waste incinerator (Site FTDX-03) and UXO at Fort Dix.
After detailed review of available data, ATSDR concludes that air emissions from the solid waste incinerator (Site FTDX-03) at Fort Dix pose no apparent public health hazards. This conclusion is based on the following:
- Because the incinerator was closed in June 1998, and there are no plans to reopen it, there is no current or future potential for exposure to air emissions from the facility.
- No past ambient air monitoring data exist in the vicinity of the incinerator. Based on an air dispersion model that used the highest detected levels of mercury emitted from the incinerator, ambient air levels are below ATSDR's comparison value.
The solid waste incinerator (Site FTDX-03) received solid waste from Fort Dix and McGuire Air Force Base and operated from 1985 until June 5, 1998. The facility was operated by a contractor for the Army. The facility was reportedly out of compliance with air permit restrictions, particularly with respect to mercury. The incinerator was shut down on June 5, 1998, when the Army began disposing of solid waste at the Burlington County Landfill. The Army has no plans to re-open the incinerator. Because the incinerator is no longer in operation, it poses no current or future public health hazards.
No ambient air monitoring data, past or present, are available in the proximity of the incinerator. As a result, past exposures to incinerator emissions are not known and can only be estimated. In order to evaluate potential past exposure to air emissions from the incinerator, ATSDR reviewed stack emission testing results at seven points in time that quantified the amounts of mercury released from the incinerator. The data for these tests were collected in November/December 1988, April 1995, April 1997, June 1997, September 1997, December 1997, and March 1998 (Army, 1999; NJDEP, 1999). These stack tests were performed for compliance purposes for the New Jersey Department of Environmental Protection.
A conservative air dispersion model was used to estimate worst-case ambient air concentrations that might have resulted from the measured levels of mercury emissions. The model parameters included the stack height, stack diameter, stack exit velocity, stack temperature, and the maximum measured mercury emission levels.
The model predicted that the ground level mercury concentrations would be highest one quarter mile (approximately 300 meters) from the incinerator stack. A federal corrections institution lies approximately one quarter mile to the east of the incinerator. An elementary school is located more than one quarter mile to the west and all other residential neighborhoods are more than one half mile from the incinerator.
Based on the results of the stack emission data from each of the seven time periods specified above, the maximum predicted concentration was 0.03 micrograms per cubic meter (µg/m3). This concentration is below ATSDR's comparison value for mercury in ambient air of 0.2 µg/m3 (the chronic environmental media evaluation guide, or EMEG) and, therefore, does not pose a public health hazard.
Although the seven stack testing periods considered in this analysis suggest that ambient air concentrations of mercury were not above ATSDR's comparison value, even considering the highest mercury emission levels detected, ATSDR notes that these studies measured emission levels at a number of points in time. These emission data may or may not be characteristic of releases over the entire operating history of the incinerator. Actual mercury levels may have been lower or higher than those measured during these tests reported.
Based on the results of an air dispersion model using conservative assumptions to predict potential mercury exposure and limited available emission data, ATSDR concludes that no apparent public health hazards exist from exposure to mercury emissions from the solid waste incinerator at Fort Dix.
After review of available material, ATSDR has drawn the following conclusions:
- In one incident, children who live at Fort Dix were reported to have discovered live ammunition.
- The Army should work to ensure that all areas where UXO may be found by residents of Fort Dix, especially children, are thoroughly searched and UXO removed. In areas where UXO may potentially exist but excavation is not possible, physical barriers, such as fences, should be installed.
During the BRAC UXO survey, it was reported that children found two explosive-filled hand grenades (Ogden, 1997). The children lived in the Garden Terrace housing area, but the location at which the grenades were found is unknown. It was speculated that the grenades were found in the wooded area south of the Cantonment Area. Later documentation indicates that the grenades were not, in fact, explosive filled. Please refer to comment 5 in Appendix C. In a separate incident, three drill mortars (no explosive charge) were found during excavation for a new gas line in the Holly Crest housing area (Ogden, 1997).
Military operations have occurred at Fort Dix since 1917. These activities have left UXO or spent ammunition in several areas. These items may have become buried in more recent years. Because children live at Fort Dix, the Army should ensure either that UXO is located and retrieved or that areas where removal is prohibited are made inaccessible. ATSDR recommends that any areas where UXO could be discovered by children, particularly in areas near or in residential areas, be remediated or fenced off and posted for no trespassing.
ATSDR recognizes that infants and children may be more sensitive to environmental exposure than adults in communities faced with contamination of their water, soil, air, or food. This sensitivity is a result of the following factors: (1) children are more likely to be exposed to certain media (e.g., soil or surface water) because they play outdoors; (2) children are shorter than adults, which means that they can breathe dust, soil, and vapors close to the ground; and (3) children are smaller, therefore childhood exposure results in higher doses of chemicals per body weight. Children can sustain permanent damage if these factors lead to toxic exposure during critical growth stages. ATSDR is committed to evaluating their special interest at sites such as Fort Dix, as part of ATSDR's Child Health Initiative.
ATSDR evaluated the likelihood that children living at Fort Dix may have been or may be exposed to contaminants at levels of health concern. ATSDR did not identify any situations in which children are likely to be or have been exposed to contaminants at levels that would be associated with adverse health effects. ATSDR based this conclusion on several factors after reviewing the available data, including:
- Because the Kirkwood-Cohansey Aquifer is not used as a public drinking water supply in the vicinity of Fort Dix, no exposures are expected to exist. No drinking water wells located on site are screened in this aquifer. Groundwater contamination does not appear to have migrated off site. Two nearby off-site wells that draw from the Kirkwood-Cohansey Aquifer were identified during the remedial investigation, but it appears that they are not and will not be affected by contaminated groundwater at Fort Dix.
- Based on an air dispersion model, past exposure to mercury levels from the incinerator do not appear to pose a public health hazard.
- Sites where UXO may be found are generally part of the Training and Range and Impact Areas and are, therefore, not accessible to children. However, the Army should ensure that any accessible areas with UXO should either be remediated or made inaccessible.