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PUBLIC HEALTH ASSESSMENT

WRIGHT-PATTERSON AIR FORCE BASE
FAIRBORN, GREENE COUNTY, OHIO


SUMMARY

Wright-Patterson Air Force Base (WPAFB) is an active military facility located between the cities of Dayton and Fairborn in Greene and Montgomery Counties of southwestern Ohio. WPAFB is composed of Wright Field, designated as Area B, and Patterson Field, designated as Areas A and C. Wright Field encompasses approximately 2,800 acres and includes three inactive runways, the Aeronautical Systems Center, the U.S. Air Force (USAF) Research Laboratory, the USAF Museum, and the USAF Institute of Technology. Patterson Field encompasses approximately 5,700 acres used for a range of activities from storage and warehousing to offices and classrooms. Active runways are located in Area C of Patterson Field. Hazardous substances were released to the environment during waste disposal, spills, fire training, and normal base operations. In October 1989, the U.S. Environmental Protection Agency (EPA) placed WPAFB on the National Priorities List based on the potential for hazardous substances in groundwater to contaminate drinking water supplies.

In preparing this public health assessment, ATSDR reviewed available data from WPAFB, EPA, the Ohio Environmental Protection Agency (OEPA), and the cities of Dayton and Fairborn. ATSDR also talked with community members about their health concerns. From a review of available data and discussions with community members, ATSDR identified releases from Operable Unit 1 (OU1) (Landfills 8 and 10), contamination of the drinking water supply, and contamination of recreational waters as the principal possible exposure pathways of concern. Based on a review of the available information, ATSDR concludes that WPAFB poses no apparent public health hazards.

ATSDR completed a detailed review of ambient air, surface soil, surface water, sediment, and private well sampling data at OU1. Sampling and analysis have not found contaminants at concentrations that are likely to pose a current public health hazard. In addition to these site media, a past ATSDR concern was methane gas emanating from the landfills. From 1985 though 1991, methane gas concentrations exceeding the lower explosive limit were detected in outdoor soil gas wells located within the landfills proper, areas adjacent to housing units on the eastern side of Landfill 10, and around the perimeter of Landfill 8 within the Woodland Hills housing complex. Although no methane was found in the housing units at that time, ATSDR determined in 1990 that this methane could pose an explosion hazard at several housing units. As a result, several units were evacuated and remediation activities were undertaken. The 1990 Health Consultation also discussed concerns about the potential for other contaminants beside methane to enter housing units. No data regarding potential indoor air contamination were available at the time of the health consultation. For this PHA, ATSDR reviewed results from 1991 ambient air and indoor air sampling and evaluated potential exposures to contaminants. The air contaminants posed no apparent public health hazard. To further decrease the possibility that methane gas leaks could occur and to decrease the potential for exposure to other contaminants, WPAFB installed landfill caps to prevent exposure to contaminated surface soil. The landfill caps include gas and leachate collection systems to prevent contaminant migration to ambient air, groundwater, surface water, and sediment. Wells surrounding the landfills are monitored to track contaminant migration and prevent future exposures. Homes with private wells were connected to municipal water supplies. Mitigation activities undertaken at WPAFB have reduced the potential for current and future explosive hazards. For these reasons, methane gas and possible low levels of contamination from OU1 in ambient air, surface soil, surface water, sediment, and private wells have not posed past public health hazards and do not present current or future public health hazards.

ATSDR evaluated drinking water sampling data from Fairborn supply wells, a Miami Conservancy District well, Dayton supply wells, and WPAFB supply wells. Contaminants were not present at concentrations that are likely to cause adverse health affects. Fairborn and the Miami Conservancy District closed their contaminated wells. The contaminated Fairborn well was used infrequently as an emergency supply well. The Miami Conservancy District only operated one well associated with a caretaker home that was occupied for only a portion of the year. The contaminated Dayton wells never contributed to the water supply system. Dayton and WPAFB installed water treatment systems on wells to remove contamination before water enters the distribution system. Fairborn, Dayton, and WPAFB regularly monitor wells to ensure the water's safety. The Miami Conservancy District no longer maintains any wells. WPAFB monitors groundwater throughout the base to track contaminant migration and ensure that these contaminants do not enter the drinking water supply. For these reasons, possible or actual contamination of public drinking water supplies has not posed past public health hazards and does not present current or future public health hazards.

ATSDR completed a detailed review of surface water and sediment sampling data from the Mad River and on-base water bodies (i.e., lakes and streams) and fish tissue sampling data from the Mad River and Hebble Creek. Site contaminants were not present at concentrations that are likely to adversely affect health. WPAFB has remediated soil-contaminated sites and monitors groundwater and surface water runoff to ensure that on-site contaminants are not migrating to water bodies. The Ohio Department of Health has issued a fish consumption advisory for the Mad River between Dayton and Urbana, Ohio, to reduce intake of contaminated fish tissue. This advisory indicates that people should eat no more than one 8-ounce meal of white sucker or common carp caught from the Mad River per week. This advisory is based on levels of PCBs found in fish tissue samples, however, no on-base sources of PCBs have been found during investigations at WPAFB. No fish tissue data were available for fish stocked in on-base lakes for recreational fishing. ATSDR believes, however, that residence time in these lakes, as indicated by the need for annual restocking, is insufficient for fish to bioaccumulate significant contaminant concentrations to present a public health hazard, particularly for the likely infrequent consumption. Fish tissue sampling from these on-base lakes would further support this conclusion. For these reasons, possible contamination of surface water, sediment, and fish in on-base water bodies and Hebble Creek has not posed past public health hazards and does not present current or future public health hazards. Additionally, although ATSDR agrees that the fishing advisory for Mad River is necessary, WPAFB does not appear to be contributing to contamination of fish in the river.


BACKGROUND

Site Description and History

Wright-Patterson Air Force Base (WPAFB) is an active military facility located between the cities of Dayton and Fairborn in Greene and Montgomery Counties of southwestern Ohio. The installation is composed of two airfields, Wright Field and Patterson Field, which are separated by State Route 444 and ConRail Corporation railroad tracks. Wright Field, also designated Area B, encompasses approximately 2,800 acres and includes three inactive runways, the Aeronautical Systems Center, the U.S. Air Force (USAF) Research Laboratory, the USAF Museum, and the USAF Institute of Technology. Wright Field is bounded by State Route 444 and Patterson Field to the north; commercial, residential, and agricultural land to the east and south; and the city of Dayton well fields and open land to the west. Patterson Field, composed of Areas A and C, encompasses approximately 5,700 acres used for a range of activities from storage and warehousing to offices and classrooms. Active runways are located in Area C of Patterson Field. Patterson Field is bounded by a mixture of industrial, commercial, agricultural, and open land to the north; residential neighborhoods and commercial properties to the east; state Route 444 and Wright Field to the south; and open land, residential neighborhoods, and the Mad River are to the west (see Figure 1) (OEM-WPAFB, 1998b).

In 1904, the Wright Brothers began experimental flying on Huffman Prairie, currently a portion of Area C within Patterson Field. A pilot training school was operated by the Wright Brothers at this site from 1910 to 1916. In 1917, training for pilots, mechanics, and armorers was provided at Wilbur Wright Field, also located in Area C. This was the beginning of a military presence at WPAFB. The Fairfield Air Depot, later renamed Patterson Field, was constructed adjacent to Wilbur Wright Field and began operation in 1918 as a general supply depot and aircraft engine repair center. In 1927, Wright Field was constructed in Area B. Wright Field served as the headquarters for the Army Air Corps Materiel Division, currently the Air Force Materiel Command, which was responsible for all research and development work for military aircrafts and components. During World War II, WPAFB underwent expansion with new construction of offices, hangers, runways, test facilities, and housing units. Employment peaked at this time with 50,000 personnel; declining to 25,000 after World War II (OEM-WPAFB, 1998b).

Currently, WPAFB supports over 1,560 on-base facilities, none of which conduct large-scale production or manufacturing operations. The largest facilities are associated with the Air Force Materiel Command, which has worldwide responsibility for all of the USAF's supply, depot maintenance, and repair functions, and the Aeronautical Systems Center, which conducts research and development and acquisition program management for all new Air Force aircraft and flight systems. Other main facilities operated at WPAFB include Wright Laboratories, the USAF Museum, the USAF Institute of Technology, the National Air Intelligence Center, and the USAF Medical Center (MARCOA Publishing, Inc., 1997; OEM-WPAFB, 1998a).

The majority of contamination identified at WPAFB resulted from the use of hazardous substances associated with (1) storage and use of fuels, (2) burning waste solvents and fuels during fire-fighting training exercises, (3) production of waste oil, solvents, and chemicals during research and development, and (4) waste oils and liquids resulting from aircraft maintenance. Sources and sites of contamination include landfills, earthfill disposal areas, fire-fighting training areas, spill sites, chemical burial sites, coal and chemical storage areas, and underground storage tanks (OEM-WPAFB, 1998b).

Remedial and Regulatory History

In 1981, the Department of Defense's Installation Restoration Program (IRP) commenced with a Phase I record review to identify potential problem areas at WPAFB. As a result, Phase II investigations were conducted at 33 sites. In February 1988, WPAFB entered into an Ohio Consent Order with Ohio Environmental Protection Agency (OEPA) to establish the framework for conducting preliminary assessments (PAs), site investigations (SIs), remedial investigations/feasibility studies (RI/FSs), remedial designs, and remedial actions. The U.S. Environmental Protection Agency (EPA) listed WPAFB on the National Priorities List (NPL) in October 1989 based on the potential for hazardous materials in groundwater to contaminate drinking water supplies. Similar to the consent order with OEPA, WPAFB entered into a Federal Facilities Agreement (FFA) with EPA in March 1991. The FFA established a framework and schedule for implementing and monitoring response actions at the base (OEM-WPAFB, 1997a and 1998b).

Under the IRP process, an RI/FS work plan was developed for 39 sites identified at WPAFB. Additional sites were added as they were identified during Phase II investigations. These sites were grouped into operable units (OUs) based on geographic location. Over time, additional sites were identified at WPAFB and grouped under existing OUs. Currently, there are 11 OUs focusing on potential contamination sources, one area of concern (AOC), and a Basewide Monitoring Program (BMP) addressing base-wide groundwater, surface water, and sediment concerns (OEM-WPAFB, 1998b). The sites are grouped (shown on Figures 2 and 3) as follows

OU1 -- Landfills 8 and 10
OU2 -- Burial Site 1; Coal and Chemical Storage Area; Long Term, Temporary, and Building 89 Coal Storage Piles; and Spill Sites 2, 3, and 10
OU3 --

Earthfill Disposal Zones 11 and 12; Fire Training Areas 2, 3, 4, and 5; Landfills 11, 12, and 14; and Spill Site 1

OU4 -- Landfills 3, 4, 6, and 7 and Central Heating Plant 2 at Building 271
OU5 -- Burial Site 4, Fire Training Area 1, Gravel Lakes Tank Site, and Landfill 5
OU6 -- Earthfill Disposal Zone 1 and Landfills 1 and 2
OU7 -- Landfill 9
OU8 -- Spill Sites 5, 6, 7, 9, and 11; underground storage tank (UST) at Building 71A; and Central Heating Plant 1 at Building 66
OU9 -- Burial Site 3, Central Heating Plant 5 at Building 770, Earthfill Disposal Zones 2 to 10, Deactivated Nuclear Reactor, and Radioactive Waste Burial Site
OU10 -- Central Heating Plants 3 at Building 170 and 4 at Building 1240, Landfill 13, Spill Sites 4 and 8, Tank Farm 49A, UST at Building 119, and East Ramp Removal Tank
OU11 -- Burial Site 2, Chemical Disposal Area, and UST at Building 4020
AOC -- Building 20079 Complex
BMP -- basewide groundwater

RIs and/or SIs have been completed for each OU. Records of Decisions (RODs) establishing required remedial actions, if any, have been signed for each OU, excluding the Building 20029 Complex, which is still under investigation, and basewide groundwater for which interim remedial actions have been undertaken. The USAF is in the process of implementing these remedial actions with the goal to have all remedies in place by the end of 1999 and to pursue partial delisting from the NPL for soil contamination sites, except OU1 (Landfills 8 and 10), by October 1999 (OEM-WPAFB, 1998d; Finke, 1999). A summary of investigations, remedial actions, and RODs completed are provided in Table 1.

ATSDR Involvement

In a 1990 Health Consultation and 1991 follow-up, the Agency for Toxic Substances and Disease Registry (ATSDR) investigated potential hazards of off-site migration of methane from Landfills 8 and 10 to the Woodland Hills housing area. Data from sampling conducted in 1985, summer and fall 1989, and winter 1990 were reviewed. Based on these data, ATSDR concluded that an imminent and substantial fire and explosion hazard existed in homes and structures in the immediate vicinity of Landfills 8 and 10. Data from soil gas monitoring wells served as the basis for this conclusion. Indoor air sampling did not detect methane. The 1990 Health Consultation also discussed concerns about the potential for other contaminants beside methane to enter housing units. No data regarding potential indoor air contamination were available at the time of the health consultation. ATSDR, therefore, recommended that the USAF conduct further indoor air, ambient air, and soil gas sampling. The USAF evacuated homes where ATSDR identified explosion hazards (ATSDR, 1990 and 1991) and proceeded to implement extensive remediation, including removal of some housing units, extraction of methane, and emplacement of venting and monitoring systems. Housing units were removed because the footprint of the landfill cap would have significantly encroached into their yards.

In preparation for completing a public health assessment (PHA), ATSDR conducted a site visit in spring 1998. ATSDR met with base personnel to explain ATSDR's mission and function and to describe the PHA process.

In September 1998, ATSDR conducted another site visit, during which ATSDR met with representatives of the USAF, attended an Environmental Advisory Board (EAB) meeting, and attended a community information session regarding Landfills 8 and 10. The community information session was designed to answer questions and hear concerns from residents about the proposal to remove the fences surrounding Landfills 8 and 10 and create a recreational area. Concerns and comments raised at these meetings are discussed in the Evaluation of Environmental Contamination, Exposure Pathways, and Public Health Implications section and the Community Health Concerns section of this report.

Demographics and Land Use

WPAFB is located in Greene and Montgomery Counties. The total populations of these counties are 136,731 and 573,809, respectively. Montgomery County contains the city of Dayton. The base is located west of and adjacent to the city of Fairborn, population 31,300.

At its peak during World War II, WPAFB employed 50,000 personnel. In 1997, approximately 24,600 personnel, 15,500 of which were civilians, were employed at WPAFB. Housing for military personnel and their families is provided at several locations within the base. Page Manor, located south of the runways in Area B, is the largest quarters with 1,463 family housing units. Facilities for 80 mobile homes are also provided in this area. The Brick Quarters, Green Acres, and Pine Estates are located within the northern portion of Area A and support 520 family housing units. Kitty Hawk Center, located northeast of Area A, provides housing within four dormitories for 592 personnel. No OUs or AOCs are located within these housing areas. Woodland Hills, located east of Area B, contains 350 family housing units. OU1 is located within the Woodland Hills housing area and OU9 is located immediately to the east. Base housing locations are shown on Figures 2 and 3. A total of approximately 7,100 residents, including 3,500 dependants under the age of 18, reside in on-base housing facilities (MARCOA Publishing, Inc., 1997; OEM-WPAFB, 1998d; Stoll, 1999).

Playgrounds are located within the housing areas. At present, these playgrounds are not located within the bounds of IRP sites or AOCs. Historically, there was a playground, including basketball and tennis courts, on Landfill 8 in the Woodland Hills housing area. Both Landfills 8 and 10 in the Woodland Hills housing area were used for recreational purposes until 1985. Concerns about public safety related to the landfills within the housing area are addressed in the Evaluation of Environmental Contamination and Potential Exposures Pathways section of this report. In addition, the city of Riverside maintains a community park at the Earthfill Disposal Zone 1, located in OU6 in the southwestern portion of Area B. Fill material was disposed here in the 1940s. Investigations at this area did not identify any contamination associated with the fill material (Engineering-Science, Inc., 1992; OEM-WPAFB, 1996).

There are five child care centers on base and plans are in place to open a new center and re-open an old center. One center is located by Building 1, in the northeastern portion of Area C. Three centers, one of which serves as a before and after program for school age children, are located in Kitty Hawk Center. The fifth center, located in the Page Manor housing area, serves as a community center for older children. None of the child care centers are located within an OU. Over 700 children under school age attend these on-base child care centers. In addition, residents may operate small, private day care centers within their homes. A permit must be filed with and approved by Base Housing. Base Housing strictly monitors the level of care and safety provided in homes (OEM-WPAFB, 1998d).

There are no schools or elderly housing units within the boundaries of WPAFB. The USAF hospital is located in the eastern portion of Area A and beyond the boundaries of any OUs. The medical center is primarily an outpatient care center, with only 90 beds available for overnight patients (OEM-WPAFB, 1998d).

Quality Assurance and Quality Control

In preparing this PHA, ATSDR relied on the information provided in the referenced documents and from the referenced contacts. ATSDR assumes that adequate quality assurance and control measures were followed with chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn in this document are dependent on the availability and reliability of the referenced information.


EVALUATION OF ENVIRONMENTAL CONTAMINATION AND POTENTIAL EXPOSURE PATHWAYS

In this section, ATSDR evaluates potential exposure pathways in detail to determine whether contamination from WPAFB activities poses public health hazards to people having access to, or living near, the site. Figure 4 describes ATSDR's exposure evaluation process. As the figure indicates, ATSDR considers how people might come into contact with, or be exposed to, contaminated media. Specifically, ATSDR determines whether an exposure could occur through ingestion of or dermal (skin) contact with contaminated media, or inhalation of vapors and dust, and also considers the likely length (duration) and frequency of the exposure.

If exposure was or is possible, ATSDR then considers whether chemicals were or are present at concentrations that might be harmful to people. ATSDR does this by screening the concentrations of contaminants in environmental media (e.g., groundwater or soil) against health-based comparison values (CVs). CVs are chemical concentrations that health scientists have determined are not likely to cause adverse effects, even when assuming very conservative/safe exposure scenarios. Because CVs are not thresholds of toxicity, environmental levels that exceed CVs would not necessarily produce adverse health effects. If a chemical is found in the environment at levels exceeding its corresponding CV, ATSDR examines potential exposure variables and the contaminant's toxicology. ATSDR emphasizes that regardless of contaminant concentrations, a public health hazard exists only if people come in contact with, or are otherwise exposed to, harmful levels of contaminated media.

After an initial review of exposure pathways of concern at WPAFB, ATSDR identified the releases from OU1 (Landfills 8 and 10), groundwater contamination, and surface water/sediment and fish contamination as potential concerns that required further evaluation. Following the strategy outlined above, ATSDR examined whether human exposure to harmful levels of contaminants via these pathways existed in the past, exists now, or could potentially exist in the future. ATSDR summarizes its evaluation of potential exposure pathways in Table 2 and describes it in more detail in the discussion that follows. To acquaint readers with terminology and methods used in this report, ATSDR provided appendices describing information presented in this PHA. Appendix A provides a list of CVs. Appendix B describes the TCDD Equivalency Factor (TEF) methodology used to evaluate dioxins in the environment. Appendix C summarizes the methods and assumptions used to estimate exposures and support some of the report's conclusions. Appendix D provides a glossary of terms.

Concern: Exposure to Contaminated Media at OU1 (Landfills 8 and 10)

Could exposure to contaminants detected in ambient air, surface soil, surface water, sediment, groundwater, and private wells result in adverse human health effects for past, current, and future residents of the WPAFB Woodland Hills housing area and private homes along National, Zink, and Kauffman Roads?

Conclusions

After detailed review of the available data, ATSDR concluded that contaminants in ambient air, surface soil, surface water, sediment, groundwater, and private wells are not likely to pose a public health hazard. The following information supports ATSDR's conclusion.

  • Waste disposal in Landfills 8 and 10 resulted in contaminant releases to ambient air, surface soil, surface water, sediment, and groundwater. Ambient air sampling detected volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), and metals. Indoor air sampling in homes proximate to Landfills 8 and 10 detected VOCs. Surface soil, surface water, sediment, and groundwater sampling detected VOCs, SVOCs, polychlorinated biphenyls (PCBs), pesticides, and metals. Sampling also detected dioxins in surface water, sediment, and groundwater. Private well sampling detected VOCs, SVOCs, pesticides, and metals. Sampling dates and results are provided in detail below.
  • People living in the Woodland Hills housing area might have been exposed to contaminants in ambient air, surface soil, surface water, and sediment. Private wells along National, Zink, and Kauffman Roads were exposed to contaminants from Landfills 8 and 10 The extent of the exposure is evaluated below.
  • WPAFB has conducted remedial actions to prevent current and future exposures to contaminants originating at Landfills 8 and 10. Remedial actions included installing a landfill cap, a gas collection system, and a leachate collection system and connecting homes to municipal water supplies.
  • ATSDR evaluated past exposures based on conservative assumptions designed to overestimate the amount of contaminants to which people were exposed. The evaluation did not identify any exposures that are likely to result in adverse health effects.

Discussion

Natural Resources

OU1 is located in the southeastern portion of Area B. The subsurface consists of 80 to 120 feet of glacial till overlying bedrock. Groundwater at Landfill 8 flows easterly toward an unnamed tributary of Hebble Creek located between Landfills 8 and 10. Groundwater flows radially away from Landfill 10. In some areas, groundwater is under semi-confined to confined conditions. Leachate seeps, caused by groundwater reaching the surface of the landfills and entering surface water, are located at both Landfills 8 and 10. Several small, unnamed streams flow northerly between Landfills 8 and 10 and discharge to Hebble Creek. These streams historically received leachate runoff from the landfills. Flow within these streams is not sufficient to support a fish population viable for human consumption (Engineering-Science, Inc., 1992).

Land Use

OU1 is composed of Landfills 8 and 10, located in Area B of WPAFB. Landfill 8 was operated from 1947 until the early 1970s. Landfill 10 was operated from 1965 until 1970. Both were trench and cover landfills that accepted general base refuse and hazardous chemicals. The cover thickness varied from 3 to 12 feet in depth at Landfill 8 and from 1 to 3 feet at Landfill 10. Acid neutralization and fire training were also conducted at the landfills. Reportedly, disposal trenches were believed to be located within a housing area adjacent to Landfill 10. However, investigations did not identify any contamination associated with the alleged trench locations.

In March 1991, a passive temporary leachate collection system was installed along the northern and eastern slopes of Landfill 10 to control leachate seeps. In September 1994, remedial activities continued and included construction of an impermeable cap covered by a layer of soil and vegetation and installation of leachate and gas collection systems. Construction and installation was completed in October 1996. Prior to remediation, leachate would migrate from the landfills into a stream that flows between the two landfills. Since completion of remedial activities, untreated leachate collected from Landfills 8 and 10 is discharged to the Fairborn sanitary sewer system and treated in the Fairborn wastewater treatment plant (OEM-WPAFB, 1993 and 1998b).

The area surrounding OU1 supports a residential housing complex, Woodland Hills, used by military personnel and their families. Construction of the Woodland Hills housing units began in 1970 and residents began occupying homes in 1973 and 1974. The USAF closed the landfills prior to constructing Woodland Hills. From closure in the 1970s until 1985, when a fence was installed and access limited, there was a playground located within the footprint of Landfill 8 and both landfills were used as recreational areas by the nearby residents. The stream that flows between the two landfills was not included in the fenced area (Engineering-Science, Inc., 1992 and 1993; OEM-WPAFB, 1994 and 1998d).

Seven private homes are located along National Road approximately 300 feet west of Landfill 8. Five private homes are located along Zink and Kauffman Roads approximately 1,000 feet east of Landfill 10. These homes were built between 1944 and 1955 and remained separated from WPAFB by security fences. Until 1994, private wells served as the primary drinking water supply for these homes. In 1994, the USAF, as a precautionary measure, connected homes along National, Zink, and Kauffman Roads to the Fairborn municipal water supply because contamination was found in several wells during investigations of Landfills 8 and 10. Residents abandoned their private wells at this time, except for three homes which maintained the private wells for irrigation purposes (OEM-WPAFB, 1994; Finke, 1999).

Nature and Extent of Contamination

Since 1985, the USAF has conducted numerous soil gas sampling events at Landfills 8 and 10. The first sampling event was conducted in 1985 with additional soil gas sampling in summer and fall 1989 and winter 1991. Results from these sampling events were reviewed for the 1990 Health Consultation and 1991 follow-up as discussed in the "ATSDR Involvement" section of this PHA. Between July and December 1991, five rounds of ambient (outdoor) air and one round of indoor air sampling were conducted. A total of 40 ambient air samples and 12 indoor air samples were collected and validated under EPA guidelines, a process that reviews the accuracy and usability of data. Ambient air samples, collected from nine locations around Landfills 8 and 10, were analyzed for VOCs, SVOCs, metals, and particulate matter. Ambient air sampling detected the following contaminants above CVs: acetone, benzene, methylene chloride, 1,1,2-trichloroethane, trichloroethylene (TCE), arsenic, beryllium, and chromium. Tetrachloroethylene (PCE) was detected in the upwind sample during one sampling round. Indoor air samples were collected from nine Woodland Hills housing units located adjacent to Landfills 8 and 10. These samples were analyzed for VOCs, which were not detected above CVs (Engineering-Science, Inc., 1993). Results of ambient air sampling at Landfills 8 and 10 are presented in Table 3.

In fall 1991, nine surface soil samples (from 4 to 12 inch below ground surface [bgs]) were collected at Landfill 8 and seven samples were collected at Landfill 10. These samples were analyzed for VOCs, SVOCs, pesticides/herbicides, PCBs, metals, dioxins and dibenzofurans, radiological parameters, and total petroleum hydrocarbons. ATSDR evaluated sampling results and found that arsenic, beryllium, and iron were detected above CVs in samples from both landfills. The PCB Aroclor-1254 and gamma-chlordane were detected above CVs in samples from Landfill 10 only (see Table 4). The maximum detected concentrations presented in Table 4 are above the levels determined to be naturally occurring in soil. Based on surface and subsurface soil sample results, it was determined that soil contamination was limited to within the landfill boundaries. In addition, the elevated concentrations of metals appeared to be located within localized areas rather than spread throughout the landfills (Engineering Science, Inc., 1993).

Surface water and sediment from leachate seeps and streams receiving surface water runoff from the landfills were sampled three times: spring 1991, fall 1991, and winter 1992. Surface water and sediment samples were analyzed for VOCs, SVOCs, pesticides/herbicides, PCBs, metals, dioxins and dibenzofurans, radiological parameters, and total petroleum hydrocarbons. At Landfill 8, benzene, vinyl chloride, bis(2-ethylhexyl)phthalate, aldrin, metals, and dioxins were detected in leachate and/or surface water samples at concentrations above CVs. Dioxins are a class of over 200 similar chemicals, but are reported and evaluated as a single concentration that is derived considering variations in toxicity among the different dioxin chemicals, referred to as the toxicity equivalents (TEQ). The method for deriving the TEQ is described in detail in Appendix B. Polyaromatic hydrocarbons (PAHs) (a class of SVOCs) and metals were detected above CVs in sediment samples from leachate seeps and/or the stream adjacent to Landfill 8. At Landfill 10, VOCs, SVOCs and PAHs, pesticides, metals, and dioxins were detected in leachate and/or surface water at concentrations above CVs. In sediment samples from the leachate seeps and the stream adjacent to Landfill 10, PAHs and metals were detected above CVs (Engineering Science, Inc., 1993). The maximum detected concentrations of contaminants detected above CVs are provided in Table 5.

National Road homes are located west of Landfill 8 and Zink and Kauffman Road homes are located east of Landfill 10. Private wells at six homes along National Road and four homes along Zink and Kauffman Roads were sampled on three occasions: spring 1991, fall 1991, and winter 1992. These wells were analyzed for VOCs, SVOCs, pesticides/herbicides, PCBs, metals, dioxins and dibenzofurans, radiological parameters, and total petroleum hydrocarbons. Bromodichloromethane, chloroform, dibromochloromethane, bis(2-ethylhexyl)phthalate, arsenic, and manganese were detected above CVs in private wells along National Road. The VOCs (chloroform, bromodichloromethane, and dibromochloromethane) were detected in well WP-LF08-PW04 only in the winter 1992 sampling round. When this well was re-sampled in April 1992, no contaminants above CVs were detected. Arsenic, manganese, and heptachlor were detected above CVs in private wells along Zink and Kauffman Roads. Heptachlor was also only detected in one well during a single sampling round (Engineering Science, Inc., 1993).The maximum detected concentrations of contaminants detected above CVs are provided in Table 6.

Evaluation of Potential Public Health Hazards

    Past Exposures

Sampling detected contamination in ambient air, surface soil, surface water, sediment, groundwater, and private drinking water wells. Woodland Hills residents may have been exposed to contaminants in ambient air. Residents that used the former landfills as recreation areas may have been exposed to contaminants in surface soil, surface water, and sediment. Residents along National, Zink, and Kauffman Roads were exposed to groundwater contaminants in their drinking water supply wells.

ATSDR Exposure Dose Estimates

To evaluate whether health hazards were associated with exposure to contaminated media, ATSDR estimated the potential doses for on- and off-site residents (adults and children). To estimate doses, ATSDR used very conservative assumptions to overestimate the levels of actual exposure. These assumptions, ATSDR's methods, and the estimated doses are further described in Appendix C. Although low levels of contamination were detected in samples collected at Landfills 8 and 10, in no case were levels found to be high enough to present a reasonable likelihood for harmful exposures to have occurred. ATSDR concluded that past exposures pose no apparent public health hazards for on- and off-site residents. This conclusion is based on ATSDR's exposure evaluation and the following information:

  • CVs are used as screening values. Detection of chemicals above CVs does not, of itself, necessarily imply that harmful exposure occurred.
  • Landfills 8 and 10 were operated as trench and cover landfills, as such, waste was covered with a layer of soil soon after disposal. The cover thickness varied from 3 to 12 feet in depth at Landfill 8 and from 1 to 3 feet at Landfill 10. This cover would have minimized direct contact with wastes disposed of in the landfills. In addition, sampling results from 1991 are considered representative of past conditions because the landfill covers were installed after waste disposal and remained unchanged until remedial actions were completed in 1994.
  • Sampling detected contaminants above CVs in only a small portion of the total samples collected for each media. For example, four of the six contaminants detected in private wells adjacent to the landfills (chloroform, bromodichloromethane, dibromochloromethane, and heptachlor) were detected in only one well during only one of the three sampling rounds. Actual exposure to the maximum detected contaminant concentrations did not occur over the entire exposure period or across the entire site.
  • ATSDR used extremely conservative assumptions about how often and how long a resident is exposed to a chemical. Ambient air exposures were assumed to occur 24-hours a day, every day, over the entire exposure period. Actual exposures were likely less frequent and over a shorter duration than assumed by ATSDR.
  • No surface water and sediment CVs are available, therefore contaminant concentrations detected in these media were compared to drinking water and surface soil CVs, respectively. Calculations of drinking water and soil CVs assume that exposure occurs daily and occurs for extended periods of time (i.e., years). However, surface water is not used as a drinking water source, and exposure to sediment in these water bodies is not likely to occur daily for extended periods of time (i.e., years). Therefore, the contaminants were evaluated for potential exposure through incidental ingestion of surface water and sediment. For incidental exposure, the levels detected do not present a public health hazard.
  • The streams do not support a fish population viable as a food source. Consumption of fish from these water bodies is not an exposure pathway.
  • Contaminants above CVs were detected in private wells along National Road. However, groundwater flow along National Road is generally toward the north and east and toward Landfill 8 (Engineering Science, Inc., 1993). Therefore, it is unlikely that Landfill 8 is the source of contamination in private wells along National Road. Regardless of the source, however, ATSDR evaluated exposure, using conservative assumptions for exposure frequency and duration, and found that contaminants were not present at concentrations likely to result in adverse health effects.

    Current and Potential Future Exposures

Current and future exposures to contaminants detected in site media are not expected to occur because remedial actions have isolated or removed contaminants and any remaining contamination is no longer accessible to the public. Therefore, ATSDR concluded that current and future site use is unlikely to result in adverse health effects. The following remedial actions prevent exposures and support ATSDR's conclusion:

  • The USAF installed a landfill cover, a gas collection system, and leachate collection system to prevent migration of contaminants from the landfills to surrounding areas. The landfill cap consists of an impermeable geomembrane to prevent precipitation infiltration and a 2 foot soil cover to prevent exposure to surface soil contaminants. The gas and leachate collection systems capture and treat gases and leachate produced in the landfills to prevent migration of contaminants to ambient air and adjacent streams.
  • The landfills are surrounded by a fence to prevent access. The USAF is exploring the possibility of removing fences and using the landfills for passive recreation, such as walking trails. The USAF will not remove the fences until they can ensure that public health will be protected.
  • WPAFB continues to monitor groundwater in OU1 to track contaminant migration and ensure that people are not exposed to contamination, either through water supplies or groundwater discharge to surface water bodies.
  • WPAFB connected homes with private wells along National, Zink, and Kauffman Roads to the Fairborn municipal water supply. These residents abandoned their private wells, except three of the homes where the wells are maintained for irrigation. This limited use, however, is unlikely to result in adverse health effects.

Concern: Exposure to Groundwater Contamination

Could exposure to TCE, PCE, and other contaminants in groundwater result in adverse human health effects for residents of neighboring communities or for former residents, employees, or visitors of WPAFB?

Conclusions

After detailed review of the available data, ATSDR concluded that contaminants in groundwater are unlikely to pose a public health hazard. The following information supports ATSDR's conclusion.

  • Past activities at WPAFB resulted in groundwater contamination underlying the base. Sampling detected VOCs, SVOCs, pesticides, metals, and dioxins in groundwater at different locations throughout the base. VOCs and chromium were detected in WPAFB, Fairborn, and Dayton water supply wells. Vinyl chloride was detected in the single caretaker well operated by the Miami Conservancy District. Sampling dates and results are provided in detail below.
  • WPAFB residents and workers were exposed to low levels of VOCs in drinking water in the past. Prior to 1970, Fairborn residents were exposed to chromium contamination in an emergency water supply well. Users of the Miami Conservancy District caretaker well were exposed to low levels of vinyl chloride. Dayton has never used their VOC-contaminated wells to supply drinking water. The extent of exposure is evaluated below.
  • Fairborn and the Miami Conservancy District closed their contaminated wells. WPAFB, Fairborn, and Dayton regularly monitor drinking water supplies under OEPA guidance. A treatment system is in place at OU5 (Landfill 5), the source of a TCE plume migrating off base. WPAFB regularly monitors groundwater throughout the base to track contaminant migration.
  • ATSDR conducted an exposure evaluation based on conservative assumptions designed to overestimate the amount of contaminants to which people were exposed. The evaluation did not identify any exposures that might result in adverse health effects, based on current epidemiology, toxicology and medial information.

Discussion

Hydrogeology

Groundwater underlying WPAFB is present in two aquifers: the Mad River Buried Valley Aquifer and the deeper bedrock aquifer. The unconsolidated Mad River Buried Valley Aquifer consists of alluvium, till, and glacial sand and gravel. The alluvium, which is only present in portions of WPAFB, can range from 40 to 60 feet deep. A 2 to 7 foot thick layer of dense, unsorted till composed of clay, silt, gravel, and sand separate the alluvium and glacial deposits. However, in many areas this till layer may be absent and the alluvium directly overlies the glacial deposits. These glacial deposits range from 50 to 250 feet thick; the thickest portions are located in Area C and the western boundary of Area B. The narrowest or shallowest glacial deposits are located in the eastern upland portion of Area B, where bedrock outcroppings are located. The groundwater table in the unconsolidated deposits is generally 5 to 15 feet bgs. During wet weather, the groundwater table may be found at the surface in low-lying areas. The alluvium and till layers may be locally productive and provide domestic water supplies. The underlying glacial deposits were designated a sole-source aquifer in 1988 and serve as a drinking water supply to WPAFB, Fairborn, and Dayton. The bedrock aquifer is composed of limestone and shale and is located near the surface in Area B and up to 250 feet bgs in Areas A and C. Groundwater is present in fractures and joints in the bedrock, however, bedrock is only a minor source of drinking water (OEM-WPAFB, 1998b and 1998c; USGS, 1996).

The aquifer system underlying WPAFB may be considered unconfined, allowing vertical migration of groundwater; however, localized till layers may influence flow within a given area. Significant sources of recharge for the aquifers underlying WPAFB are infiltration of precipitation and surface water and groundwater flow into the area. Groundwater flow in Areas A and C is toward the Huffman Dam to the southwest. Adjacent to the Mad River along the northwestern base boundary, localized flow is toward the river. Within the eastern portion of Area B, groundwater flows north-northeast toward Huffman Dam. Groundwater flow is to the west-northwest toward the Mad River in the western portion of Area B. There are some localized variations caused by subsurface geology and by pumping of wells (OEM-WPAFB, 1998b; USGS, 1996).

Groundwater Use

WPAFB pumps drinking water from 15 water supply wells, which comprise three water supply systems. Five wells (Wells A, B, C, E, and F) are located in Area A within OU5. These wells serve as a backup to the water supply wells serving Area B. These wells are currently inactive due to high exceedences of EPA's secondary Maximum Contaminant Levels (MCLs) for iron and manganese. Four wells (Wells 1, 2, 4, and 5), none of which are located within the boundaries of an OU, are located in and supply water to Area B. The supply system serving Areas A and C is composed of six wells (Wells 1, 2, 3, 7, 8, and 9) located along Skeel Avenue in Area C. Water within each system is blended prior to distribution. Combined, these systems serve a total population of 7,100 on-base residents and 24,600 on-base workers. Water supply well locations are shown on Figures 2 and 3 (MARCOA Publishing, Inc., 1997; OEM-WPAFB, 1998b; Rogers, 1999).

Fairborn supplies water to approximately 32,000 people from 10 wells located in three well fields: Mad River, North, and Central Park. The Mad River well field, developed in 1974, is located adjacent to the Mad River and north and upgradient of WPAFB. This well field contains five wells and serves as the city's primary drinking water supply. The North well field, located adjacent to OU2 and upgradient of groundwater flow from WPAFB, contains four wells and serves as an emergency water supply. The North well field is only used in times of drought and twice a year during hydrant flushing. One well within the North well field was closed in November 1970 due to chromium contamination. Fairborn monitors other active emergency wells in this area to ensure that contamination is not entering the water supply system. The Central Park well field consists of one well located in Central Park, upgradient of WPAFB. This well is maintained on stand-by status for emergency use only. Each of these well fields draw from the sole-source water-bearing aquifer underlying the region (Hawkins, 1999).

Private wells located in Fairborn and downgradient of WPAFB were present along National, Zink, and Kauffman Roads. The residences were connected to the municipal water supply in 1994 as described in the previous section. Private wells located in the city of Riverside are present downgradient of Landfill 2, located in OU6 in the western portion of Area B. No groundwater contaminants have been detected migrating from Landfill 2 to downgradient locations (OEM-WPAFB, 1998b and 1998c; Hopkins, 1999; Luken, 1999).

The Miami Conservancy District is located southwest of OU5 adjacent to the Huffman Dam. A single well serving a caretaker house was used as a drinking water supply for several months every year. This well was abandoned when investigations detected vinyl chloride; re-sampling of the well did not detect any contamination (IT Corporation, 1995).

Dayton provides drinking water to a population of approximately 400,000 with multiple well fields pumping from two aquifers; an unnamed aquifer northwest of WPAFB and the Mad River Buried Valley Aquifer. The unnamed aquifer is located beyond WPAFB's boundaries. Based on its location several miles northwest and cross gradient of WPAFB and the groundwater hydrology, this aquifer is not likely to be impacted by activities at WPAFB (City of Dayton, 1998)

Dayton maintains two well fields using the Mad River Buried Valley Aquifer. The Rohrer's Island well field is located along the Mad River and downgradient of WPAFB. This well field was developed as the first municipal water supply for Dayton in the late 1800s and provides the majority of the water supply. Since initial development, wells have been continuously added, closed, or replaced as needed. The Huffman Dam well field is located along Huffman Dam between WPAFB and the Rohrer's Island well field. This well field is relatively new and has not yet been used to supply drinking water (City of Dayton, 1998; Shoemaker, 1999).

The Dayton water supply is blended prior to distribution so that no single supply well provides 100 percent of a household's or business's water supply. Within the city of Dayton, no private wells were identified downgradient of WPAFB (City of Dayton, 1998)

Nature and Extent of Groundwater Contamination

Dayton designated a wellhead protection zone for the Mad River Buried Valley Aquifer, partially within the boundary of WPAFB. WPAFB activities have released contamination to this aquifer. In the process of investigating site contamination, the USAF installed and sampled hundreds of monitoring wells located within OUs and around the perimeter of the base. Sampling detected VOCs, SVOCs, pesticides, metals, and dioxins. Based on these sampling results, the USAF implemented remedial action and monitoring programs to insure that the water supply is protected from further contamination.

As early as 1985, the USAF was sampling drinking water supply wells and water from the distribution system under USAF regulations to maintain compliance with the Safe Drinking Water Act and Ohio rules and regulations. Between 1985 and 1988, bromodichloromethane, chloroform, dibromochloromethane, bromoform, PCE, TCE, carbon tetrachloride, vinyl chloride, and 1,1-dichloroethene were detected above ATSDR's CVs. In the late 1980s, the USAF installed treatment systems on each well due to some VOCs, such at TCE and PCE, exceeding the MCLs. Samples collected in 1991 detected the following contaminants above CVs in the water supply prior to treatment: carbon tetrachloride, bromodichloromethane, dibromochloromethane, PCE, and TCE. Currently, samples are collected after treatment and before water enters the distribution system and are analyzed for VOCs, SVOCs, metals, and water quality parameters. Sampling of the treated water in 1998 detected chloroform, bromodichloromethane, and dibromochloromethane at concentrations above CVs, but below EPA's MCLs (OEM-WPAFB, 1998d; Rogers, 1999). It should be noted that these chemicals are common by-products resulting from disinfection of drinking water by chlorination processes. Table 7 presents the maximum detected concentrations and corresponding CVs for contaminants detected above CVs.

In November 1970, when sampling likely began, Fairborn closed one well located upgradient of WPAFB and within the North well field due to chromium contamination. The chromium concentration that resulted in the well closing is unavailable. Fairborn conducts quarterly monitoring under OEPA guidance. No other wells have been closed due to contamination (Hawkins, 1999).

A single well in the Miami Conservancy District served a caretaker residence during the summer months. Sampling of this well detected vinyl chloride above its CV during one sampling round. Resampling has not detected contamination above CVs. This well has been closed and is no longer used (IT Corporation, 1995).

Investigations of OU5 identified a TCE plume migrating from WPAFB toward the two Dayton well fields located along the Mad River. Monitoring for VOCs at Rohrer's Island well field commenced in spring 1988. At this first sampling event, TCE was detected in one well (PW58) above the CV and EPA's MCL. Well PW58 was installed in 1988 and had never contributed to the water supply system when sampling detected TCE. In general, concentrations of TCE have been decreasing in this well over time. No other VOCs were detected above CVs during regular monitoring. In 1989, an air stripper was installed at PW58 to prevent contamination from entering the water supply distribution system (City of Dayton, 1998; Shoemaker, 1999).

The Huffman Dam well field was constructed along the Mad River immediately downgradient of OU5. Because sampling detected a TCE plume migrating from WPAFB toward the Huffman Dam well field, Dayton sampled wells PW65 and PW71 within this well field prior to pumping water. PW65 sampling has been conducted regularly since December 1992. PCE, TCE, 1,2-dichloroethane (1,2-DCA), and vinyl chloride were found above CVs in samples from this well. PW71 sampling began in December 1993 and has found PCE, TCE, and 1,2-DCA at concentrations above CVs. PW65 and PW71 are currently used for pumping and treating contaminated groundwater to remove VOC contamination. The Huffman Dam well field has never contributed to the Dayton water supply. If this well field is used as an active water supply, water will be treated prior to distribution regardless of detected contaminant concentration (City of Dayton, 1998).

Exposure Evaluation of Potential Public Health Hazards

    WPAFB Water Supply System

WPAFB residents and workers were exposed to VOC-contaminated drinking water in the past. The initial date of contamination remains unknown. VOC concentrations above CVs and MCLs were detected when the supply wells were tested in compliance with the Safe Drinking Water Act and OEPA regulations in 1985.

    ATSDR Exposure Dose Estimates

To evaluate whether health hazards are associated with exposure to VOC-contaminated drinking water at WPAFB, ATSDR estimated the potential doses for on-site workers and on-site residents (adults and children). To estimate doses, ATSDR used very conservative assumptions believed to greatly overestimate the levels of actual exposure. These assumptions, ATSDR's methods, and the estimated doses are further described in Appendix C. ATSDR concludes that past, current, and potential future exposures to VOC-contaminated groundwater in the water supply system are not likely to pose public health hazards. This conclusion is based on ATSDR's exposure evaluation and the following information:

  • CVs are used as screening values. Detection of chemicals above CVs does not, of itself, necessarily imply that harmful exposure occurred.
  • Sampling detected contaminants above CVs in only a small portion of the water supply samples (less than 25%). However, calculations of CVs assume that people were exposed to the maximum detected contaminant concentration over the entire exposure period, which is unlikely to occur.
  • ATSDR used extremely conservative assumptions about how often and how long a worker or resident is exposed to a chemical. Residents were assumed to drink water from the WPAFB system every day over the entire exposure period. Actual exposures are expected to be less frequent and over a shorter duration than assumed by ATSDR.
  • WPAFB blends water from each well within the supply system prior to distribution. Because of this practice, contaminant concentrations at the point of exposure, such as at the tap or a water fountain, will be less than the maximum detected concentration detected at an individual well.
  • To prevent current and future exposures, WPAFB regularly monitors the water supply system under OEPA guidance, installed treatment systems at all water supply wells to remove contaminants, and regularly monitors groundwater throughout the base to track contaminant migration.

    Off-Base Water Supplies

Sampling detected chromium in one Fairborn emergency supply well, vinyl chloride in a Miami Conservancy District well, and VOCs in two Dayton well fields. People using these water supply systems may have been or could be exposed to contamination. ATSDR evaluated potential exposures and concluded that past, current, and potential future use of these water supplies are not likely to pose public health hazards. This conclusion is based on the following information.

  • Any chromium exposure is expected to have been infrequent and of short duration. The chromium-contaminated well within Fairborn was used only as an emergency supply during drought or the twice annual hydrant flushing events. Prior to distribution, water from this well was blended with water from other supply wells, reducing the actual chromium concentration distributed to homes. The contaminated well is currently inactive and Fairborn regularly tests other wells to insure that the supply system is free of contamination.
  • The Miami Conservancy District well was closed after sampling detected vinyl chloride. This well served a caretaker home that was only occupied in the summer. Vinyl chloride exposure to occupants of the caretaker residence is expected to have been infrequent and of short duration. Although, re-sampling did not detect contamination above CVs, this well was abandoned and no longer serves as a drinking water supply.
  • Prior to being connected to the supply system, sampling detected VOCs in several Dayton water supply wells. Dayton installed treatment systems on these wells and several of the wells remain inactive and unconnected to the municipal system. Contaminated wells in the Dayton supply system never contributed to the drinking water supply, therefore, this pathway is incomplete. Dayton regularly tests other wells to ensure that the supply system is free of contamination.

Concern: Potential Impacts to the Mad River and On-Base Lakes

Could contaminants detected at WPAFB migrate to recreational water bodies, including the Mad River and on-base lakes, and result in adverse human health effects from recreational activities such as swimming, boating, and fishing?

Conclusions

After detailed review of surface water, sediment, and fish tissue data, ATSDR concluded that contaminants in on- and off-base surface water bodies are not likely to pose public health hazards, based on current epidemiological, toxicological and medical information. The following information supports ATSDR's conclusion.

  • Past activities at WPAFB resulted in low levels of surface water and sediment contamination in water bodies at or near WPAFB. Sampling detected SVOCs, pesticides, and metals in surface water, and SVOCs, pesticides, metals, and dioxins in sediment. Fish tissue samples from the Mad River and Hebble Creek detected low levels of PCBs, lead, and zinc. Sampling data and results are provided in detail below.
  • Recreational users of on- and off-base water bodies were potentially exposed to low levels of contaminants in surface water, sediment, and fish tissue. The extent of exposure is evaluated below.
  • Currently, the Ohio Department of Health (ODH) has a fish advisory for the Mad River based on PCB concentrations detected in fish tissue. The affected area extends from Urbana, a town 50 miles upstream of WPAFB, to Dayton, downstream of WPAFB. The advisory recommends limited consumption of fish caught in the Mad River. In addition, no on-base sources of PCBs have been identified during investigations at WPAFB.
  • The USAF conducts regular sampling of storm water outlets that drain to the Mad River and on-base surface water bodies. In addition, WPAFB has remediated soil contamination and has treatment and monitoring systems in place for groundwater contamination. These measures reduce the likelihood that additional contamination from WPAFB is entering the Mad River and its tributaries.
  • ATSDR conducted an exposure evaluation based on conservative assumptions designed to overestimate the amount of contaminants to which people were exposed. Because the levels of contamination found were low, the evaluation did not identify any exposures that might result in adverse health effects.

Discussion

Hydrology

The Mad River flows southerly along the northwestern boundary of Areas A and C. The Huffman Dam, located along the Mad River immediately south of OU5 in Area C, controls river flow to prevent downstream flooding. Several tributaries to the Mad River flow through WPAFB before discharging into the river. Hebble Creek flows southwesterly through Areas A and C and converges with the Mad River proximate to Huffman Dam. Trout Creek flows southwesterly through Area C and converges with the Mad River north of Huffman Dam. Lily Creek flows westerly through Area B and converges with the Mad River south of the Huffman Dam and Rohrer's Island well field. These water bodies are shown on Figures 2 and 3. Portions of WPAFB are located within the Mad River floodplain.

Surface water from WPAFB drains either directly to the Mad River and its tributaries (Lily Creek, Hebble Creek, Trout Creek, and several unnamed streams) or into catch basins and storm drains. The catch basins and storm drains are located throughout WPAFB and discharge in the Mad River or its tributaries. Oil-water separators are located in some areas of the base, but generally storm water runoff is not treated before discharge to the river and streams. Storm water is sampled at outfall points as required under a National Pollution Discharge Elimination System (NPDES) permit issued in 1980. Only concentrations of iron and total suspended solids have ever exceeded the permit limits. WPAFB is currently in the process of renewing this permit with the OEPA (OEM-WPAFB, 1998b and 1998d; True, 1999).

Four lakes are located within the boundaries of WPAFB: Bass Lake, Gravel Lake, East Twin Lake, and West Twin Lake. Bass Lake is located in the northern portion of Area C south of OU11. Bass Lake discharges to the Mad River via an unnamed stream. Gravel, East Twin, and West Twin Lakes are located in Area C in OU5. These three lakes, which are more properly classified as ponds because of their shallow depth, were created from gravel quarrying activities. Gravel, East Twin, and West Twin Lakes do not discharge to the Mad River. A water treatment system is in place at OU5 to remove VOCs from contaminated groundwater and discharges to the Twin Lakes under a NPDES permit. If the water level in the Twin Lakes is high or the discharge pipes need cleaning, the treatment system discharges directly to the Mad River under this NPDES permit. Discharge is monitored to ensure the that contamination is not entering these water bodies (IT Corporation, 1995; OEM-WPAFB, 1998c).

Recreational Use

The Mad River is located beyond the boundaries of WPAFB and public access to the river is not restricted. People use the Mad River for recreational purposes such as fishing, swimming, wading, and boating. Access to Hebble, Trout, and Lily Creeks is restricted by security fences that surround WPAFB. Based on their relatively isolated locations, these creeks are unlikely to be frequented by base employees or residents, however, they may serve as occasional recreation areas (OEM-WPAFB, 1998b; USGS, 1996). One unnamed tributary to Hebble Creek passes through the Woodland Hills housing area and has received contaminants in runoff and leachate from Landfills 8 and 10. Concerns associated with recreational use of this stream by base residents were discussed previously in this report.

Bass, Gravel, East Twin, and West Twin Lakes are open to military members, active and retired, and WPAFB employees for recreational purposes, but are not available for general public access as they are located within the security fences of WPAFB. Each of the four lakes is maintained as recreational areas. Maintenance activities at each of these lakes includes annually stocking with fish. Activities that may be conducted at the lakes include fishing and boating; swimming and wading are prohibited (OEM-WPAFB, 1998d; Finke, 1999).

Nature and Extent of Contamination

During investigations of WPAFB, surface water and sediment samples were collected from the Mad River, on-base streams, and the on-base lakes. Surface water and sediment samples were analyzed for VOCs, SVOCs, PCBs, pesticides, and metals. In addition, OEPA collected fish tissue samples from the Mad River and analyzed these samples for SVOCs, PCBs, pesticides, metals, and dioxins. Because surface water and sediment CVs are not available, analysis results for these media are compared to the drinking water and surface soil CVs, respectively. In surface water, bis(2-ethylhexyl)phthalate, pentachlorophenol, alpha-BHC, and metals were detected above CVs. Sediment sampling and analysis detected PAHs, pesticides, metals, and dioxins above CVs. The method used to evaluate dioxins is described in Appendix B. Analysis of fish tissue samples from the Mad River and Hebble Creek detected PCBs above CVs. No fish tissue samples were collected from on-base water bodies; however, no on-base sources of PCBs exist (IT Corporation, 1995; OEPA, 1994; USGS, 1996). Sampling results for contaminants detected above CVs in surface water, sediment, and fish tissue are presented in Table 8.

Evaluation of Potential Public Health Hazards

Recreational users of on- and off-base surface water bodies may have been exposed to SVOCs, pesticides, metals, and dioxins in surface water and sediment, and PCBs and metals in fish.

    ATSDR Exposure Dose Estimates

To evaluate whether health hazards are associated with exposure to contaminants in surface water bodies used for recreational purposes, ATSDR estimated the potential doses for recreational users (adults and children). To estimate doses, ATSDR used very conservative assumptions believed to overestimate the levels of actual exposure. These assumptions, ATSDR's methods, and the estimated doses are further described in Appendix C. Even using conservative exposure assumptions, ATSDR concludes that past, current, and potential future exposures to contaminants in surface water, sediment, and fish tissue are not likely to pose public health hazards. This conclusion is based on ATSDR's exposure evaluation and the following information:

  • CVs are used as screening values. Detection of chemicals above CVs does not, of itself, necessarily imply that harmful exposure occurred.
  • Sampling only detected contaminants above CVs in only a small portion of the total samples collected for each media. However, calculations of CVs assume that people were exposed to the maximum detected contaminant concentration over the entire exposure period.
  • ATSDR CVs use extremely conservative assumptions about how often and how long a recreational user is exposed to a chemical. Actual exposures are expected to be less frequent and over a shorter duration than assumed by ATSDR.
  • No surface water and sediment CVs are available, therefore, contaminant concentrations detected in these media were compared to drinking water and surface soil CVs, respectively. Calculations of the drinking water and soil CVs assume that exposure occurs daily. The streams may be used for recreational purposes, however, exposure is expected to occur significantly less frequently than assumed by the CVs. Moreover, none of the surface water bodies are used as a source of drinking water.
  • Currently, ODH has a fish advisory for the Mad River based on PCB concentrations detected in fish tissue, however, no on-base sources of PCBs have been found during investigations at WPAFB. This advisory indicates that people should eat no more than one 8-ounce meal of white sucker or common carp caught from within the stretch of the Mad River from Urbana, a town 50 miles upstream of WPAFB, to Dayton, downstream of WPAFB. The advisory is expected to reduce the amount of fish people consume from this stretch of the river. This limitation is expected to protect local anglers from exposure to contaminants that may accumulate in fish in the Mad River, regardless of source.
  • To limit and prevent future exposures, the USAF regularly monitors groundwater and samples storm water outlets that drain to the Mad River and on-base surface water bodies. In addition, the USAF has remediated soil contamination throughout the base and operates a groundwater treatment system at OU5. These measures reduce the potential that WPAFB is an ongoing source of contamination in recreational water bodies and limit exposure by providing a "warning" should future contamination occur. Over time, contaminant concentration are expected to decline and, in turn, potential doses and exposures are expected to decline.

COMMUNITY HEALTH CONCERNS

ATSDR identified the following community health concerns through meetings, contact with officials, and review of site documents, including RODs and the Community Relations Plan prepared by the USAF in August 1997:

  • Is there a relationship between several childhood cancers in the Beavercreek neighborhood and activities at WPAFB? (This issue was raised by the Ohio Cancer Registry.)

The Beavercreek neighborhood is located southeast of the base. This is a fairly rural neighborhood where many on-base employees, both civilian and military, reside. Groundwater underlying WPAFB flows to the northwest, toward the Mad River and away from the Beavercreek neighborhood. Surface water runoff and streams at WPAFB also flow toward the Mad River and away from the Beavercreek neighborhoods. Therefore, groundwater and surface water are not expected to transport contamination from WPAFB to Beavercreek. The prevailing wind direction is to the northeast, however, shifting winds may on occasion transport airborne contamination from WPAFB to the Beavercreek neighborhood. WPAFB serves mostly as a research facility and not as a manufacturing facility. The primary sources of airborne contaminants are the heating plants. Air emissions are monitored under permits and the primary emission concern is sulfides which lead to acid rain and are not associated with cancer. ATSDR did not identify an association between contamination within WPAFB and the Beavercreek neighborhood.

  • Has site contamination impacted the fish in water bodies other than the Mad River (Bass Lake, Gravel Lake, and the Twin Lakes), and what is the impact on East Twin and West Twin Lakes from receiving treated water from the OU5 water treatment system? (This issue was raised by a member of the EAB.)

    The USAF collected surface water and sediment samples from Bass, Gravel, East Twin, and West Twin Lakes during site investigations. ATSDR did not identify any contaminants in surface water or sediment in these lakes that are present at concentrations likely to result in adverse health effects. However, the USAF did not collect fish samples from these lakes. The USAF must restock Bass, Gravel, East Twin, and West Twin Lakes with fish annually because fishing at the lakes reduces the fish population. ATSDR believes that fish are unlikely to bioaccumulate significant concentrations of contaminants because they are caught within a year after stocking. Fish tissue sampling results would strengthen this conclusion.

    East Twin and West Twin Lakes receive treated water from the OU5 water treatment system on a regular basis. Only when the water level is high, or the system needs cleaning, is treated water discharged directly to the Mad River. OEPA regulates discharge to the East Twin and West Twin Lakes and the Mad River with a NPDES permit. This permit requires regular sampling to monitor contaminant concentrations. ATSDR reviewed the March 1998 sampling data and no contaminants were detected above CVs or MCLs.

  • Could levels of the pesticide chlordane in soil near the foundation of housing units in Page Manor pose a potential health threat? (This issue was raised by WPAFB personnel based on historical application of chlordane to control termites in base housing units.)

    WPAFB conducted sample analyses for soils collected in the base housing areas because of a concern that chlordane levels might be in excess of what could be considered safe for residential areas. Chlordane is present in soil adjacent to housing foundations as a result of application as a termiticide. Chlordane use was a common and accepted widespread practice throughout the country until use was discontinued in 1988. Sample analysis found chlordane in foundation soil at WPAFB as a result of normal and accepted application procedures. There is no evidence that the chemical was misapplied. Detected concentrations are consistent with those expected from normal application of residences treated before 1988. Although the amounts found are in excess of CVs, they do not pose a public health hazard for the type of exposure expected, as discussed below.

    ATSDR evaluated exposure to children through incidental ingestion of contaminated soil. The amounts present, ranging up to 310 parts per million (ppm), were detected adjacent to housing unit foundations. In a recent sample analysis conducted by WPAFB, chlordane concentrations decreased greatly in samples collected further than 1.5 feet from the foundations of the homes (OEM-WPAFB, 1999). Detected chlordane levels are not expected to be found uniformly throughout the yards, and likely only occur as relatively isolated "hot spots" found near the foundations. A potential public health hazard might become a possibility only if soil from these specific "hot spots" is consumed by a child repeatedly and consistently for a number of days (for example, every day for two weeks). Because the "hot spots" do not uniformly occur across the yards of the housing area, this type of exposure is unlikely. In addition, the exposure would occur only if the surface of the "hot spot" consisted of bare dirt. Any ground cover, such as grass, shrubbery, mulch, or paving will eliminate the likelihood of exposure. Considering the factors described above, it is not likely that exposure to levels of chlordane detected would present a potential public health hazard.

  • Could contaminants from Landfills 8 and 10 contribute to increased cancer rates for families that lived in the Woodland Hills housing area when the landfills were used for recreational purposes? (This issue was raised by a former resident of the Woodland Hills housing area.)

    As part of the evaluation of contaminated media at OU1, discussed earlier, ATSDR compared detected contaminant concentrations against CVs. Concentrations above CVs do not necessarily indicate that there will be adverse health effects unless very specific types of exposure occur. For those contaminants detected above CVs, ATSDR conducted an exposure evaluation that considers chemical toxicity and how frequently and for how long a person is exposed.

    At OU1, ATSDR evaluated exposures for Woodland Hills residents (adults and children) that contacted contaminants in ambient air, surface soil, surface water, and sediment. In this evaluation, ATSDR used conservative assumptions that overestimate the length of exposure and how much of a contaminant a person actually contacts. For example, ATSDR assumed that military personnel resided in Woodland Hills for a period of 5 years, whereas, military personnel actually resided in on-base housing for only 3 years. ATSDR also assumed that residents would contact contaminants in the landfill during recreational use, which was assumed to occur 5 days a week for 26 weeks each year. Such frequent use was unlikely to occur based on inclement weather and the regional Mid-west climate; boots, long pants, jackets, and gloves worn during colder months are expected to limit contact with contaminants. ATSDR did not identify any contaminants at concentrations that would likely increase a resident's probability of developing cancer from the types of incidental contact that would be likely to occur. Appendix C provides details regarding methods and assumptions used by ATSDR in conducting this evaluation.

  • Could contaminants from Landfills 8 and 10 contribute to the occurrence of multiple sclerosis for families that lived in the Woodland Hills housing area when the landfills were used for recreational purposes? (This issue was raised by a former resident of the Woodland Hills housing area.)

    Medical research to date has not linked multiple sclerosis to exposure to hazardous chemicals in the environment. And, as stated above, in the evaluation of contaminants associated with Landfills 8 and 10 ATSDR did not identify any contaminants at concentrations that would likely increase the occurrence of illnesses in general. It is unlikely that incidence of multiple sclerosis would be effected by any of the contaminants detected in sampling analyses at these landfills.


ATSDR CHILD HEALTH INITIATIVE

ATSDR recognizes that infants and children may be more sensitive to exposures than adults in communities with contamination in water, soil, air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed because they play outdoors and they often bring food into contaminated areas. Children are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in higher doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care. Because children depend completely on adults for risk identification and management decisions, ATSDR is committed to evaluating their special interests at sites such as WPAFB, as part of the ATSDR Child Health Initiative.

Like other people living or working at or in the vicinity of WPAFB, children may contact contamination in site media. Near OU1 (Landfills 8 and 10), children residing in the Woodland Hills housing complex may contact contaminants in ambient air, surface soil, surface water, and sediment. Private wells, contaminated with VOCs and metals, served off-base homes adjacent to OU1. Children residing on-base throughout WPAFB were exposed to VOCs in drinking water from the water supply system. Children, either at WPAFB or in surrounding neighborhoods, may have been exposed to contaminants in surface water, sediment, or fish from the Mad River and on-base recreational lakes.

To evaluate whether children may experience adverse health effects from exposure to site contaminants, ATSDR estimated the potential doses for children either living on or near WPAFB and children using on- and off-base surface water bodies for recreation. To estimate doses, ATSDR used very conservative assumptions believed to overestimate the levels of actual exposure. These assumptions, ATSDR's methods, and the estimated doses are further described in Appendix C. ATSDR concludes that exposure to site contamination does not pose unique health hazards for children. This conclusion is based on ATSDR's exposure evaluation and the following information:

  • CVs are used as screening values. Detection of chemicals above CVs does not, of itself, necessarily imply that harmful exposure occurred.
  • Sampling detected contaminants above CVs in only a small portion of the total samples collected for each media. However, in evaluating potential health hazards, ATSDR assumed that children were exposed to the maximum detected contaminant concentration over the entire exposure period, which is unlikely to occur.
  • ATSDR used extremely conservative assumptions about how often and how long children are exposed to a chemical. Actual exposures are expected to be less frequent and over a shorter duration than assumed by ATSDR.
  • An evaluation of estimated exposure doses to ATSDR's minimal risk levels (MRLs) and the toxicology literature did not identify childhood doses that are likely to result in adverse health effects.
  • WPAFB, surrounding cities, and regulatory agencies are aware of the contamination issues stemming from activities at WPAFB. The USAF has taken measures and conducted remedial activities to prevent future contaminant releases to the environment. WPAFB also monitors existing contamination in groundwater to ensure the safety of the water supply and prevent future exposures. Surrounding cities also monitor their water supplies. Regulatory agencies monitor fish safety in the Mad River and oversee activities at WPAFB to ensure the proper actions are taken to address existing contamination and prevent future contamination.

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