PUBLIC HEALTH ASSESSMENT
U.S. AIR FORCE PLANT NO. 4 (GENERAL
DYNAMICS)
FORT WORTH, TARRANT COUNTY, TEXAS
Air Force Plant 4 (AFP4) is a 602-acre government-owned contractor-operated aircraft manufacturing facility seven miles northwest of the city of Fort Worth in Tarrant County, Texas. The site is bounded by Lake Worth to the north and northwest, the city of White Settlement to the south and west, and Meandering Road Creek to the west. Naval Air Station (NAS) Fort Worth (formerly Carswell Air Force Base) is adjacent to AFP4 to the east.
AFP4 has been in continuous operation producing aircraft since 1942. Throughout the plant's early history (prior to 1973), waste materials (waste oils, fuels, solvents, paint residues, and spent process chemicals) were disposed of at on-site landfills or burned during fire training exercises. Primarily as a result of groundwater contamination, the site was placed on the National Priorities List (NPL) in August 1990. In September 1995, the U.S. Environmental Protection Agency (EPA) and the Texas Natural Resource Conservation Commission (TNRCC) approved the Remedial Investigation/Feasibility Study. A final Record of Decision (ROD) describing the selected remedial actions to be taken at the site was issued in July 1996.
The Texas Department of Health (TDH) and the Agency for Toxic Substances and Disease Registry (ATSDR) evaluated the environmental information available for the site and identified several exposure situations for evaluation. These exposure situations include possible contact with site contaminants in the foodchain, sediment, surface water, air, soil, and groundwater. A brief review of the evaluation organized by hazard category is presented below. Based on available data we have concluded that overall, the AFP4 NPL site poses no apparent public health threat. Because of insufficient data we identified one exposure situation as an indeterminate public health hazard. In the future, the conclusion category for the overall site could change if additional data indicate that the indeterminate public health hazard situation poses a threat to public health.
INDETERMINATE PUBLIC HEALTH HAZARD
ATSDR concluded that one exposure situation is a potential or indeterminate public health hazard. Additional information is required to adequately assess the magnitude of the health threat associated with this situation.
We concluded that the following exposure situations pose no apparent public health hazard. In these situations, people may come into contact with site contaminants; however, certain conditions exist that make it unlikely that exposure to contaminants would be of health concern.
ATSDR concluded that the following exposure situations pose no public health hazard either because people were not likely to come into contact with site contaminants or because institutional controls are sufficient to protect human health.
In addition to the environmental data, ATSDR evaluated available health outcome
data pertaining
to concerns raised by members of the community. In the past, community members raised
concerns about cancer and asthma. Because of the lack of a plausible exposure pathway, ATSDR
was not able to associate any of the health outcome data with site-related contaminants.
In accordance with the Interagency Agreement between the U.S. Air Force and the Agency for Toxic Substances and Disease Registry (ATSDR) and through a Cooperative Agreement between ATSDR and the Texas Department of Health (TDH), ATSDR and TDH have prepared this Public Health Assessment (PHA) for Air Force Plant 4 (AFP4), a federal facilities National Priorities List (NPL) site.
This PHA presents conclusions about whether exposures are occurring, whether a health threat is present, and whether adverse health effects are expected from that exposure. In some cases, it is possible to determine whether exposures occurred in the past. If it is found that a threat to public health exists, recommendations are made to stop or reduce the threat to public health.
In order to evaluate the threat to public health from contaminants at NPL sites, the PHA focuses on examining whether people have been exposed to (in contact with) the contaminants. Two of the most important tasks associated with the PHA are;
In the PHA we will examine:
To make the above determinations, each of the potential environmental media pathways will be examined. An environmental pathway can be described as the route the contamination follows from the source to where people may be in contact with it. The environmental media that this PHA will examine are:
Another important factor is the way that people might come into contact with the contaminant. By this we mean whether the chemical is:
Not all chemicals are a hazard for each of these methods of contact. For example, most metals are not harmful, particularly in very low amounts, if the only contact is by way of the skin. See the box on the following page for a portrayal of the exposure evaluation process we will use in this PHA.
In preparing this Public Health Assessment, ATSDR has relied on the information provided in the referenced documents. The Agency assumes that adequate quality assurance and quality control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and the conclusions drawn in this document are determined by the availability and reliability of the referenced information.
The majority of the environmental data were collected between February 1990 and May 1992
[1].
The EPA has approved quality assurance and quality control (QA/QC) criteria contained in the
referenced site investigation documents. The EPA also has overseen all aspects of the remedial
investigation to ensure that all QA/QC standards were met.
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ATSDR Exposure Evaluation Process |
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WHAT are the contaminants at Air Force Plant 4? WHICH environmental media are
contaminated? and HOW much contamination is present in each? HOW do contaminants travel to where people can come into contact with them? HOW could people be exposed to the
contaminants? ARE people exposed to site contaminants? or WERE they exposed to site contaminants in the past? If exposure is occurring, or occurred in the past, |
A. SITE DESCRIPTION AND HISTORY
AFP4 is a government-owned contractor-operated aircraft manufacturing facility seven miles northwest of the city of Fort Worth in Tarrant County, Texas (Figure 1). The 602-acre site is bounded by Lake Worth to the north and northwest, the community of White Settlement to the south and west, and Meandering Road Creek to the west. Meandering Road Creek discharges into Lake Worth. Except for areas adjacent to Meandering Road Creek and Lake Worth, the land surrounding AFP4 is flat. Elevations at the site range from 590 feet above mean sea level (msl) along Lake Worth to approximately 670 feet above msl at the southwest corner of the site [1]. Neither a 100- nor a 500-year flood event would directly affect the site [2]. Carswell Air Force Base (part of which is now named Naval Air Station [NAS] Fort Worth and the remainder of which belongs to the Air Force Base Conversion Agency [AFBCA]) is adjacent to AFP4 to the east and is a source of groundwater contamination independent of AFP4.
AFP4 has been in continuous operation producing aircraft since 1942. Over the years the plant has produced B-36, B-58, F-111, and F-16 aircraft. General Dynamics (GD) operated the facility from 1953 until 1993 when Lockheed Martin took over the operation. Currently, Lockheed Martin is engaged in the production of the F-16 Fighting Falcon and other advanced tactical fighters. In the past, a Nuclear Aerospace Research Facility (NARF) involved in the experimental development of nuclear aircraft was located at AFP4. In 1974, this facility was demolished and the debris was removed and disposed of off site.
It has been estimated that in the past, AFP4 generated 5,500 to 6,000 tons of waste oils, fuels, solvents, paint residues, and spent process chemicals per year [1]. Throughout the plant's early history, these wastes were disposed of at on-site landfills or burned during fire training exercises. Since 1973, these wastes have been disposed of at permitted off-site facilities. The AFP4 NPL site includes four landfills, five fire training areas, three chrome pits, a chemical pit, three fuel saturation areas, and a wastewater collection system and basin (Figure 2).
Contamination on AFP4 was first reported in 1982, when a citizen noted an odd discharge in an outfall from Landfill No.1. A French drain was installed to prevent the migration of contaminated groundwater toward Meandering Road Creek. The Air Force initiated the Installation Restoration Program (IRP) at AFP4 to identify and evaluate potential areas of contamination. A total of 31 hazardous spills and waste disposal areas were identified. Seven of the 31 areas were determined to require no further action [1]. The 24 remaining areas included industrial processing areas, fuel storage areas, landfills, known chemical and fuel spill areas, chemical disposal pits, fire training areas, an interim remedial action location, and the Assembly Building/Parts Plant. In 1984, AFP4 was proposed to be listed on the NPL and was placed on the NPL in August 1990. In October 1990, the U.S. Air Force and the U.S. Department of Energy (DOE) contracted with Rust Geotech to begin a Preliminary Assessment/Site Inspection (PA/SI) and a Remedial Investigation/Feasibility Study (RI/FS) for the site. The RI/FS, which characterized the extent of the contamination at the site, was approved by the U.S. Environmental Protection Agency (EPA) and the Texas Natural Resource Conservation Commission (TNRCC) in September 1995. A final Record of Decision (ROD) describing the selected remedial actions to be taken at the site was issued in July 1996. The ROD addresses the final response actions planned for the six areas identified in the baseline risk assessment that have the potential for excess risk. These six areas are Landfill No. 3, Landfill No. 4, Meandering Road Creek, Paluxy Aquifer and Upper Sand Groundwater, East Parking Lot Groundwater plume, and Building 181 [2].
ATSDR's initial involvement with AFP4 began in 1988, when a preliminary health assessment was prepared. Based on the information available at that time, ATSDR concluded that "this site is of potential health concern because of the potential risk to human health resulting from possible exposure to hazardous substances that may result in adverse health effects." ATSDR recommended a characterization of the potential for off-site migration of contaminants.
In 1991, ATSDR initiated and completed a health
consultation for AFP4 [3]. This health
consultation focused on two specific public health concerns which were identified during a site
visit: 1) unrestricted access to a creek and landfill where significant surface water contamination
had been documented, and 2) groundwater contamination observed in the middle Paluxy aquifer
near two White Settlement municipal wells. In that health consultation, ATSDR recommended
that "access should be restricted to Landfill No. 3, seeps in the area, and the portion of
Meandering Road Creek which borders Landfill No. 3." ATSDR also requested to be kept
advised of the results from the sampling of White Settlement municipal wells #2 and #12.
Subsequently, White Settlement municipal well #2 was taken out of service by the city of White
Settlement.
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VOLUNTARY ACTIONS TAKEN BY THE AIR FORCE IN
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| In response to ATSDR's health consultation, the Air Force has voluntarily installed, and is currently operating, a vacuum-enhanced extraction system at Landfill No. 3 to reduce contamination in the Terrace Alluvial groundwater that may discharge to Meandering Road Creek. This extraction system consists of 42 extraction wells spaced 20 feet apart and a trench 150 feet long with four extraction points. The wells and the trench are along the western edge of Landfill No. 3. The trench was installed where the depth to the bedrock (i.e., the Walnut Formation) is shallow, approximately 4 feet. The vacuum-enhanced extraction system was chosen for this site because of the low permeability of the aquifer in this area [2]. The Air Force also has installed a fence across Meandering Road Creek (near Landfill No. 3) as a precautionary measure to reduce the potential for exposure to site contaminants. |
C. DEMOGRAPHICS, LAND USE AND NATURAL RESOURCE USE
We looked at the demographics, land use and natural resource use in the area to help identify and characterize potentially exposed populations.
Demographics
Several small communities, including White Settlement, Westworth Village, and River Oaks are close to AFP4. White Settlement, population 15,472 [4], lies to the south and west. Based on the 1990 U.S. census data and an area-proportional spatial analysis technique, we estimated the total population within one half-mile and one-mile of the site boundaries. Within one half-mile of the site boundaries we estimated the total population to be 6,303 people (Figure 3). Approximately 90 percent were white, four percent were black, and six percent were of other races. Eight percent were of Hispanic origin (Hispanic origin may be of any race), 12 percent of the total population were age six and younger, and eight percent were age 65 and older. Approximately 25 percent of the population were females of child-bearing age (15 to 44 years).
We estimated there to be 13,158 people within one mile of the site boundaries (Figure 4). Approximately 91 percent were white, four percent were black, and five percent were of other races. Six percent were of Hispanic origin, 11 percent of the total population were age six and younger, and 10 percent were age 65 and older. Approximately 24 percent of the population were females of child-bearing age (15 to 44 years). There were a total of 5,161 housing units within one mile of the site boundaries for an average of 2.55 persons per household.
AFP4 employs approximately 11,500 people. In 1989, the year of peak employment, there were approximately 31,500 people employed at the plant. The former Carswell Air Force Base occupies approximately 2,800 acres. When the base was fully active, it employed approximately 1,200 military personnel and 300 civilians.
According to 1990 census data for the census tract closest to the site, the median value of owner occupied homes was $48,200 and the median rent was $342 per month. Both of these figures are relatively low and are indicative of a population in a lower socioeconomic bracket [5]. These figures were not available for the one mile boundary around the site.
Land Use and Natural Resource Use
The AFP4 NPL site is in western Tarrant County, Texas. The site and the surrounding areas to the south and east are urbanized. Approximately 70 percent of the AFP4 surface area is covered by buildings, concrete, or asphalt. The remaining 30 percent of the surface area is primarily grass-covered soils. The area to the west-northwest of AFP4 is primarily residential.
This public health assessment focuses on three surface water bodies which are affected by AFP4: Lake Worth, Meandering Road Creek, and Farmers Branch Creek. Lake Worth, which borders AFP4 on the north and northwest, is a reservoir constructed in 1914 by the city of Fort Worth as a municipal water supply. The West Fork of the Trinity River flows southeastward from Lake Worth. In addition to serving as a municipal water supply, the reservoir is used for fishing boating, and water skiing by local residents. Lake Worth is a source of drinking water for the City of Fort Worth.
Meandering Road Creek borders AFP4 to the west and flows north to Lake Worth. Farmers Branch Creek originates in White Settlement and flows south of AFP4 in an easterly direction to the West Fork of the Trinity River. Meandering Road Creek and Farmers Branch Creek are intermittent creeks which receive the majority of their flow from surface water runoff discharged into the creeks via storm drains and culverts. Both creeks also receive some of their flow from groundwater. Because of their proximity to AFP4 both creeks receive surface water runoff from AFP4; however, due to the intermittent nature of the creeks fishing and wading in the creeks by local residents is not likely. Access to portions of Meandering Road Creek are restricted by fencing. Access to portions of Farmers Branch Creek which cross the NAS is restricted by base security.
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