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PUBLIC HEALTH ASSESSMENT

USAF ROBINS AIR FORCE BASE (LANDFILL/SLUDGE LA)
(a/k/a USAF ROBINS AIR FORCE BASE)
WARNER ROBINS, HOUSTON COUNTY, GEORGIA


SUMMARY

Robins Air Force Base (AFB) covers 8,855 acres east of the city of Warner Robins in Houston County in middle Georgia. Included within the boundaries of the base is a 1,200-acre wetland. The base serves as a worldwide logistics management center for aircraft, missiles, and support systems and is a major repair center for aircraft and airborne electronic systems.

Operations that have contributed to contamination at the base include land filling, waste storage and disposal, chemical or fuel spills, airplane and equipment servicing and maintenance, electroplating, painting, and fire training activities. The primary contaminants of concern affecting the soil and groundwater are: fuels and petroleum products; volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) primarily solvents and their breakdown products; metals including arsenic, chromium, and lead; and radionuclides.

The ATSDR public health assessment process examines facilities for situations that present the potential for exposure to the public of chemical waste contaminants in the environment. Also examined are situations that could cause concern of the community that exposures are occurring. During the evaluation of the base, ATSDR found the following situations to warrant environmental evaluations:

  • potential exposure to contaminants in various media in the Landfill 03 area;
  • base-wide groundwater contamination;
  • contaminants in water, sediment and biota in Duck Lake; and
  • contaminants in water, sediment and biota in the Wetlands Area.

Because the contaminant levels found during sampling analyses were below levels that would reasonably be expected to result in adverse public health effects, these situations were determined to pose "No Apparent Public Health Hazard". These scenarios and the evaluation process used are described in detail in the following sections.


BACKGROUND

Site Description and History

Robins Air Force Base (RAFB)(1) covers 8,855 acres east of the city of Warner Robins in Houston County in middle Georgia (See Figure 1). Included within the boundaries of the base is a 1,200-acre wetland. The base serves as a worldwide logistics management center for aircraft, missiles, and support systems and is a major repair center for aircraft and airborne electronic systems. As a functioning military facility with extensive industrial operations, RAFB is subject to rigorous institutional controls, such as restricted access, fencing, and security personnel. For this reason, casual access to most areas of the base is limited, including areas where contamination may be present. This factor serves to greatly limit the potential for casual access by the community and by non-workers within the boundaries of RAFB.

In 1982, RAFB conducted a base-wide survey to identify and assess past practices for disposing of hazardous waste. Disposal areas were grouped into eight zones that were based primarily on location and type of disposal activity. In 1984 the facility was proposed for inclusion on the U.S. Environmental Protection Agency (EPA) National Priorities List (NPL) for hazardous waste sites. The listing was proposed primarily because of groundwater contamination and concern that people could be exposed to contaminants in this groundwater. RAFB was placed on the NPL in 1987 (1).

Operations that have contributed to contamination at RAFB include land filling, waste storage and disposal, chemical or fuel spills, airplane and equipment servicing and maintenance, electroplating, painting, and fire training activities. The primary contaminants of concern affecting the soil and groundwater are fuels and petroleum products; volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), primarily solvents and their breakdown products; metals including arsenic, chromium, and lead; and radionuclides (2). Currently 76 solid waste management units (SWMUs) are delineated within the base. The majority of these sites have relevant environmental sampling and analysis information available. Several recently discovered areas of concern (AOCs) are currently being investigated, with information collection underway or planned.

Two of the SWMUs comprise the NPL site, regulated under CERCLA: Landfill #4 and an adjacent sludge lagoon . The landfill, located in the approximate center of RAFB, covers 40-45 acres and is in a mixed hardwood swamp along the western border of the Ocmulgee River flood plain. The landfill operated from 1965 to 1978 and accepted general refuse, garbage, and industrial wastes. The 1.5 acre lagoon operated from about 1962 to 1978 and accepted wastes from two industrial waste treatment plants plus other waste chemicals. Both areas have undergone extensive remediation, appreciably decreasing the potential for the contamination to present a public health hazard. The balance of the hazardous waste areas are regulated and monitored under the Resources Conservation and Recovery Act (RCRA) (1). The waste areas are shown in Figure 2 and are summarized in Appendix B.

Demographics

RAFB is located adjacent to the city of Warner Robins (population about 40,000), in Houston County, Georgia (population about 89,000), and immediately adjacent to Bibb County (population about 150,000). Twiggs County (population about 10,000) is directly east of RAFB, across the Ocmulgee River . The base employs about 19,000 military and civilian personnel. Base housing consists of 1,399 family housing units and lodging for 1,169 single military personnel (3).

Land Use and Natural Resources

RAFB is bounded on the immediate west by the city of Warner Robins, on the north by a relatively undeveloped area that comprises the clear zone of the active runway. To the south of RAFB is a housing subdivision, Statham's Landing. To the east is the Ocmulgee River and its flood plain and wetlands.

Ground and surface water at RAFB generally drains from west to east into the Ocmulgee River flood plain. Aquifers at the site include the surficial fill, alluvial gravel, the Providence Formation Aquifer, Cusseta Clay Formation, and the Blufftown Aquifer. Present groundwater supply wells are located up gradient of contaminant sources.

ATSDR Involvement

After entering into a Memorandum of Understanding with the Department of Defense (DOD), in 1991, ATSDR visited the 96 DOD installations then on the NPL and ranked them according to their potential public health hazards. ATSDR personnel visited RAFB in February 1991. On the initial visit, ATSDR reviewed the available site-specific information and visually inspected the contaminated sites and areas where hazardous substances had been released into the environment. The focus of the visit was to determine if people could come into contact with site contaminants at levels that pose health hazards, and whether actions to stop or prevent such exposures should be recommended. RAFB received a relatively low priority ranking to initiate a public health assessment in comparison with other DOD installations. The low ranking indicates that no immediate public health hazards were found. A second visit was made in April 1998 to obtain updated environmental information collected during remedial activities occurring since 1991. As a part of this effort, ATSDR met with representatives of the Air Force, U.S. Environmental Protection Agency (EPA) and state environmental regulators. ATSDR evaluated the current situations and the potential for ongoing exposure of the community to contaminants from RAFB. ATSDR coordinated the development of this public health assessment with the RAFB Restoration Advisory Board (RAB) in September 1998.


EVALUATION OF ENVIRONMENTAL CONTAMINATION, EXPOSURE PATHWAYS AND THE PUBLIC HEALTH IMPLICATIONS

Introduction

ATSDR's public health assessments are exposure or contact driven. Chemical contaminants disposed or released into the environment at RAFB have the potential to cause adverse health effects. However, a release does not always result in exposure. People are only exposed to a chemical if they actually come in contact with the chemical. Exposure may occur by breathing, eating, or drinking a substance containing the contaminant or by skin (dermal) contact with a substance containing the contaminant.

Exposure does not always result in adverse health effects. The type and severity of health effects that may occur in an individual from contact with a contaminant depend on the exposure concentration (how much), the frequency or duration of exposure (how long), the route or pathway of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of contaminants). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, life style, and health status of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. Together these factors and characteristics determine the health effects that may occur as a result of exposure to a contaminant.

In this section we evaluate the possible ways that people can be exposed to contamination ("pathways") at RAFB. We do this by examining the possible exposure situations to determine whether people in the community are exposed to (or in contact with) the contamination. We then look at whether that exposure may cause adverse health effects. ATSDR concluded that four exposure situations currently pose "No Apparent Public Health Hazard". Table 1 summarizes these situations.

Table 1. Public Health Situations Evaluated

POTENTIAL
PATHWAY
NAME
CONTAMINANT
POTENTIAL EXPOSURE PATHWAY ELEMENTS
TIME
COMMENTS
SOURCE
ENVIRONMENTAL
MEDIA
POINT OF
EXPOSURE
ROUTE OF
EXPOSURE
POTENTIALLY
EXPOSED
POPULATION
Landfill 03 Area primarily metals, some VOC and radionuclides landfill and disposal areas, fire training area soil, surface water, biota recreational area and lakes ingestion, dermal exposure recreational users past
present
future
Environmental sampling and analyses support that no exposures have occurred, are occurring or are likely to occur.
Base-wide Groundwater solvents and fuels numerous on and offsite domestic water domestic water use ingestion, inhalation, dermal domestic users, base personnel past
present
future
Contamination is not present in aquifer used for drinking water.
Duck Lake pesticides and PCBs spill and runoff sediment, surface water, fish recreational lake primarily dermal or consumption of fish recreational users past
present
future
Environmental sampling and analyses support that levels in past were not high enough to present a possible hazard. Remediation has eliminated potential exposure in present, future.
Wetlands primarily metals and pesticides landfill and runoff sediment, surface water, fish hunting or fishing primarily dermal exposure or consumption of fish recreational users past
present
future
Environmental sampling and analyses support that levels in the past were not high enough and are not high enough now to present a possible hazard. Remediation of adjacent waste areas will reduce potential for contamination in future.

Table 2 summarizes ATSDR's public health conclusions for the exposure situations identified at RAFB. Following sections contain detailed discussions of each situation. Additional information describing ATSDR's conclusion categories is provided in Appendix C.

Table 2. Summary of ATSDR's Public Health Conclusion for Robins AFB.

Conclusion Category Situation
No Apparent Public Health Hazard Landfill 03 Area
Groundwater
Duck Lake
Wetlands Area

Landfill #3 and Surrounding Area.

Site Description

This exposure scenario includes Landfill No. 3, Fire Prevention Training Area No. 2 (FPTA2), and the Laboratory Chemical Disposal Area (LCDA). This area collectively referred to as LF03, is depicted in Figure 3. It encompasses about six acres of open land. Contaminants at LF03,which include VOCs, SVOCs and metals, have been detected in soil and water and sediment (primarily in drainage ditches) and in the groundwater.

LF03 is located between Luna Lake, a man-made water body, and Scout Lake, a natural water body. Luna Lake, located east of LF03, is about six acres in extent. It adjoins a family campground and a nature center. North of the landfill is an open area used for horse riding. Scout Lake, to the west, is about 20 acres in size. Both lakes are open for recreational activities, primarily boating and fishing. Although access by the general public is possible, use of lakes within the boundaries of RAFB is limited to Air Force personnel and families.

LF03 was used between 1964 and 1967, primarily to fill a wet and ponded area west of Luna Lake. The landfill was used for the disposal of about 65,000 cubic yards of general refuse. In 1967, the landfill was covered by a vegetated cap. During that year, Luna Lake was excavated, lined with a low permeability clay and filled with water from a well completed in the Providence aquifer. In the late 1940s, the site of Luna Lake was occupied by a retention pond, the purpose of which is not recorded in RAFB documents (4).

FPTA2 consisted of several open-burn sites to the west and northwest of the Luna Lake site. From the mid 1950s until the mid 1960s, these areas were used for fire prevention training, using various ignitable waste materials, including petroleum product, waste oil, paint residues, and solvents (4).

Aerial photographs taken from 1955 and 1958 show several hundred drums stored in and near the present horse training area. The contents and purpose of these drums is not documented in RAFB records (4).

The LCDA was used from 1962 to 1964 for the disposal of chemicals that had exceeded recommended shelf life. The precise location is unknown, but ground-penetrating radar surveys identified subsurface cells within LF03 that are believed to be the sites of these burials (4).

IRP site RW15 (low-level radioactive waste burial site)(Figure 4) is located to the north of LF03. The contaminants associated with this area are radium (RA) 226 and acetone. In 1954, a concrete vault was buried at this location. Its primary function was for disposal of radium paint and painting equipment used for application of radium to dials and gauges (5). Discarded dials and small electronic components were also found.


Exposure Evaluation - LF03

Recreational facilities popular with RAFB personnel are located in close proximity to former waste disposal areas. ATSDR concluded that, for the purpose providing information to the community of recreational users of these facilities, an evaluation of the potential for exposure would be useful.

The potential exposures for LF03 would be incidental via dermal exposure to, or ingestion of surface soil or sediment contamination in the area of LF03, or via dermal exposure to or inhalation or ingestion of water that might contain chemicals leached from the waste areas into the recreational water bodies. An additional possible route to be evaluated is consumption of fish from these lakes.

Exposure evaluation of surface water and sediment contamination

The exposures that might occur to any contaminants in Luna Lake would be infrequent and incidental during recreational activities. During investigations between 1987 and 1990, 16 surface water samples and 27 sediment samples were evaluated (4). According to the Corrective Action Plan for LF03 (4), five sediment and five surface water samples were collected from Luna Lake. Analysis of these samples did not detect VOCs or pesticides. Lead was detected in sediment samples (less than 7.4 mg/kg) and in two water samples, at slightly less than the Action Level (15 µg/l ) (4). The Action Level pertains to drinking water levels, and would be pertinent only for long-term exposure via drinking contaminated water.

The water level in Luna Lake is maintained by water pumped from a water supply well (WS-12) that is completed in the lower Providence aquifer. Analysis indicates that this aquifer is not contaminated (4). The water level in Luna Lake is maintained above the local water table, causing water in the lake to flow into the surficial aquifer, preventing any flow from this aquifer into the lake. This effectively prevents the migration of any contaminants from the surficial aquifer into the lake.

Based on a likely exposure to water and sediment in Luna Lake via only infrequent incidental dermal exposure or ingestion of water and sediments (or incidental inhalation of water), the contamination detections in Luna Lake do not represent levels that could result in public health hazard.

Scout Lake was not sampled. However, because the lake is located up gradient of the groundwater flow, any contamination to be unlikely to reach this lake via groundwater migration. Also, the surface water flow direction appears to be predominantly away from Scout Lake. At worst, the potential contamination via surface water run-off would be similar to that of Luna Lake and does not present a possible contaminant pathway. For these reasons, exposure to the water or sediment of Scout Lake does not represent a public health hazard.

Exposure evaluation of potential contamination of fish in Luna Lake.

Fish from Luna Lake have not been collected for analysis. Consumption of fish would most likely be in frequent and in small quantities, by visitors to the recreational area. Chemical analyses of samples collected from sediment and water of Luna Lake indicate that amounts of contamination available for uptake by fish in the lake would not likely be significant. For these reasons, it is not likely that fish in this lake could be exposed to sufficient contamination to present a public health risk to people catching and eating fish from Luna Lake.

Exposure evaluation of soil contamination in the area of LF03

A final possible pathway for exposure to contaminants from LF03 would be infrequent and incidental exposure via dermal contact or ingestion of surface soil or drainage ditch and seep sediments. This exposure might occur during activities at the recreational facilities around LF03.

Samples of surface soil and sediment from drainage ditches and surface seeps have been collected as a part of the remediation process ongoing in the LF03 vicinity. VOCs, SVOCs, pesticides and metals were detected in sediment samples. Petroleum hydrocarbons (up to 100,000 mg/kg inside the landfill boundary [and therefore under the capping material] , 5.5 to 12 mg/kg in samples collected outside the boundary) and metals (lead 1.1 - 8.5 mg/kg and chromium 9.3 - 9.4 mg/kg) were detected in soil samples (4). Given the likelihood of only infrequent and short-term exposure to this soil during recreational activities, incidental exposure is not likely to present a public health hazard.

Radiologic evaluation of contamination at RW15

The buried vault was excavated in 1992, and was found to contain drums of liquid, ranging in capacity from five to fifty-five gallons. The vault and its contents were removed between June 1994 and September 1996 (5).

There are no water wells located in the vicinity of RW15. However, as a precaution, radiologic analyses were made of water sampled from three nearby monitoring wells (Figure 4). Table 1, in Appendix D, lists the maximum concentrations detected. Although the gross alpha detection exceeds MCLs, no drinking water supply wells exist in the vicinity to be at risk. Radiologic contamination does not present a public health hazard at RW15, via domestic use of this groundwater.

Soil samples were collected at RW15 in 1980. The primary concern was for incidental dermal contact and accidental ingestion by remediation workers during removal operations. An additional concern would be for similar short-term and infrequent exposures to recreational users of the area. Table 2, in Appendix D, depicts the results of analysis of four soil samples collected at RW15. Beta/gamma detector surveys of surface soils did not exceed 0.03 millirem (mr)/hr, also indicating that the levels of contamination were not likely to present a public health hazard (5). The potential infrequent and incidental contact with radioactive contaminants in soil at these levels does not present a public health hazard.

Groundwater Contamination Plumes

Extensive groundwater contamination has been documented in shallow aquifers (Surficial, Quaternary, upper and lower Providence) across RAFB. Figure 5 shows the location and extent of these plumes . Groundwater supply wells for the base are located west of the site and are up gradient to contamination. Two former base supply wells, located east and northeast of the NPL sites, were found to be contaminated with low levels of TCE (3 parts per billion [ppb]). These wells were removed from service, although the levels detected were below levels that would present a public health hazard (7). Figure 5 shows the location of the contaminant plumes located under RAFB. To assess the nature and extent of this groundwater contamination, base-wide sampling of groundwater is conducted annually and was last performed in 1998. In 1997, a total of 366 wells were sampled for analysis. The principal contaminants detected were chlorinated solvents (primarily TCE) and components of fuels (primarily benzene and chlorobenzene). With the exception of the limited groundwater contamination described in the area of LF03, the major sources of these plumes are located in the greater base industrial area (GBIA). The TCE originates from multiple industrial process sources in the GBIA. The fuel component plumes are believed to come from leaks and spills at fueling depots, fuel lines, tank farms and other fuel handling areas in the GBIA. The fuel component plumes are much more localized and not as areally extensive as the combined TCE plume (6).

A localized plume in the Surficial aquifer has been delineated in the northwestern portion of RAFB (Figure 6). The predominant contaminants in this plume are jet fuel components. One possible source of this plume may be a leaking pipeline located under the right-of-way for Highway 247. The GA EPD has investigated the vicinity of the plume and found no water supply wells located in the area that might be subjected to contamination (8). The US EPA, GA EPD and the Air Force are working with the owners of the pipeline to determine the cause of the leak and to make repairs. Remediation of the contamination is being initiated under GA EPD RCRA authority (9)

The potable water supply source for the base comprises of a series of wells completed in the Blufftown aquifer. This aquifer is separated from the contaminated shallow aquifers by the Cusseta unit, which serves as an aquitard, greatly limiting the potential for cross contamination from the shallow aquifers to deeper aquifer (6). Figure 7 depicts the relationship of the aquifers in the RAFB area. Potentiometric (hydrostatic pressure) measurements under the eastern portion of the base indicate that vertical movement between aquifers, if not restricted by the aquitard, would be from the lower to the upper aquifers. Conversely, under the western portion of the base, vertical movement would be downward, if not restricted by the aquitard. In this area, theoretically contaminants can migrate into the Blufftown Aquifer. Figure 8 shows the locations of RAFB water supply wells in relation to the overlying contaminant plumes. It should be emphasized that the detected contaminants were found in aquifers separated from the aquifer used for the base water supply.

The RAFB water supply system is regulated by the GA EPD under Safe Drinking Water Act (SDWA) authority delegated from the US EPA. Under this regulatory oversight, RAFB has monitored the base water supply wells since 1988 (10). Water from the wells is analyzed quarterly for a comprehensive suite of chemicals, including VOCs, such as TCE, and fuel components, such as benzene, that constitute the shallow aquifer contaminant plumes. Results of this sampling show that, since 1988, no contaminants have been found in these wells at levels that exceed SDWA regulatory limits. These limits are devised by the US EPA and GA EPD and are protective of human health. Additionally, drinking water analyses were compared to ATSDR comparison values. With chemicals for which ATSDR Comparison Values do not exist, EPA Region III risk-based concentrations (RBCs) were used. Table 3, Appendix D, indicates which chemicals exceeded ATSDR comparison values in the drinking water at Robins AFB. All detections above comparison values occurred on either May 16, 1988 or July 17, 1989. Two chemicals (bromodichloromethane and chlorodibromomethane) that were observed to exceed ATSDR comparison values may be by-products of the base's drinking water purification process and are not necessarily related to activities at Robins AFB. Detected concentrations only slightly exceed ATSDR cancer risk evaluation guidelines (CREG) and were detected only sporadically. No noncancer comparison values were exceeded. The very limited extent of potential exposure, therefore, makes it unlikely that detected concentrations would result in a public health hazard. ATSDR cannot draw definite conclusions regarding potential for contamination before 1988. However, because of the present location of water supply wells and the present extent of contaminant plumes, it is not likely that contamination that occurred in the past would have presented a potential public health hazard.

Under provisions of the SDWA, quarterly sampling and analysis will ensure that contaminants do not occur undetected in base water supplies. The SDWA also requires that if contamination is found, the water supply will not be used as a drinking water source, and before use resumes, treatment facilities will be in place to treat any contamination that might occur, reducing it to levels that are not a health threat, if not removing it completely. Therefore, groundwater contamination at RAFB does not present a future public health hazard via the base public water supply.

Local groundwater flow is east, toward the Ocmulgee River. Groundwater contamination under RAFB is fairly extensive, particularly in the case of TCE contamination. However, at present, the plumes are confined within base boundaries and are not accessible to potential offsite user exposure. To address the possibility of offsite exposure, the GA EPD conducted a well survey in 1994 for the area east of RAFB (10). This survey found that there were no private domestic wells located between the base and the river.

Because this area is located within the floodplain and consists predominantly of wetlands, it is not likely that future development will occur. Therefore private water wells will not likely be constructed down-gradient of the present location of the plumes. Furthermore, remediation plans call for the treatment of the plumes to reduce or eliminate existing contamination, decreasing the possibility of offsite migration (11).

For these reasons, consumption of contaminated groundwater does not present a public health hazard, and it is not likely to present a public health hazard in the future. Although no information exists for base supplies before 1986, it is not likely that the aquifer used for base water supplies was contaminated, and is not likely to have presented a past public health hazard.

Contamination in Duck Lake

Site Description

Duck Lake is a 14-acre artificial lake located in the central portion of RAFB (See Figure 9). The lake was created by damming an existing stream. It receives runoff from an extensive area within RAFB, including a base golf course, base industrial areas, and base residential areas, as well as areas off base within the city of Warner Robins. The primary environmental concern regarding the lake was a DDT spill that occurred in 1979 (12). The spill occurred at the RAFB entomology shop, located approximately 3000 feet from Duck Lake. A 55-gallon drum of DDT was spilled into a gravel-lined area. DDT reached Duck Lake via surface water runoff, after traveling approximately one mile in a drainage ditch (depicted in Figure 9). A Resource Conservation and Recovery Act (RCRA) Facility Investigation and associated studies were conducted to supplement the previous Installation Restoration Program study. These investigations indicated that the sediment in Duck Lake was contaminated with pesticides (including DDT) and polychlorinated biphenyls (PCBs). The contamination of Duck Lake can be attributed to both the DDT spill and widespread use of other pesticides within the Duck Lake watershed. The source of PCBs is unknown, but because PCBs were detected in only one soil sample there does not appear to be a continuing source of PCB contamination.

In 1992, the entomology shop building was removed, along with contaminated soil. The area was subsequently capped with a clay layer and partially repaved. Fishing and other recreational activities took place at Duck Lake, but access to the lake was restricted and fishing was prohibited in 1994 (12). Swimming is also prohibited at Duck Lake, but the report does not indicate how long this has been the case.

Remedial Activities

The stated remedial action objective for the Duck Lake project was to reduce health risks posed by contaminants to humans and the environment. This could be accomplished by preventing further contamination of the sediment and by preventing exposure of aquatic life in Duck Lake to contaminated sediments. The corrective measures for Duck Lake consisted of dewatering the lake, excavating sediments which contained contaminants at concentrations above sediment removal criteria established in the Corrective Action Plan for Duck Lake, transporting and disposing of sediments, and constructing erosion controls in the lake tributaries (12, 13).

To reduce the amount of sediment and contaminants that are transported to the lake via storm water runoff, work efforts in the upgradient streams constructed sedimentation basins and stabilized banks/slopes. Two main basins now serve as hydraulic retention facilities that allow sediments an opportunity to settle out before reaching the lakes.

Sediment excavation in Duck Lake was accomplished from September 1997 to December 1998. The excavating program included the following steps:

- A recommended depth of sediment was removed based on previous sediment sampling results.
- A confirmation topographic survey was performed to evaluate that the correct depth of sediment was excavated from each portion of the lake.
- Approximately 31,000 dry tons of sediment was shipped offsite for proper disposal.

After the lake sediments met the project sediment removal criteria, the lake was allowed to refill and has since been restocked with various species of fish.

The post remediation monitoring program consists of monitoring the contaminant concentration and volume of sediment accumulating in the sedimentation basins. The results of this monitoring will be used to determine when the sediment should be removed from the sedimentation basins to protect the ecosystem in Duck Lake." (13).

Surface Water and Sediment at Duck Lake

Several studies (RFI Addendum [14], Final Background Study Report, Duck Lake Corrective Action Plan [13], and Final Design Study Report, Duck Lake Corrective Action Plan [15]) have investigated the contamination of sediments in Duck Lake. Analysis of contaminant concentrations found in the surface water and sediments at Duck Lake are summarized in Table 3 of Appendix D.

The surface water entering the lake comes primarily from areas (both on- and off-base) west and northwest of the lake. In 1987, surface water samples were collected from Duck Lake and also from the drainage feature between the DDT spill site and Duck Lake. Organopesticides, such as DDT, were not detected in any of these surface water samples. An initial RFI report indicated that the absence of pesticides in the surface water might be a function of the low solubilities of pesticides and the flushing effect caused by continual recharge and discharge of the lake. Five additional surface water samples collected during the RFI addendum process by LAW Environmental (14) showed only trace levels of lindane (gamma-BHC). No other pesticides or PCBs were detected in any of the samples. ATSDR evaluation of data in the Duck Lake Corrective Action Plan (15) indicated that surface water ingestion or dermal contact are not considered to present human health risks because no contaminants are present in the surface waters of Duck Lake at concentrations above the practical quantitation limits (the detection limit that accounts for sample dilution, matrix interference, sample preservation, and analysis).

Some contaminants in sediment exceeded ATSDR comparison values, but by less than one order of magnitude, at most. The levels detected are not sufficient to pose public health hazards via incidental (short-term and infrequent) dermal exposure. The majority of the samples were taken in the middle of the lake, but a conservative assumption is that a person wading in the lake may have come in contact with the concentrations shown in Table 3 of Appendix D. During wading or swimming, the route of exposure to lake sediment would likely be limited to the skin on the bottom of feet, which makes absorption less likely. The sporadic nature and short duration of exposures that are likely to have occurred in the past as such that these exposures would likely have resulted in no apparent public health hazard in the past. Remediation activities have reduced or eliminated contaminants in the lake, further insuring that harmful exposures are not likely to occur, therefore, present and future exposures present no apparent public health hazard.

Fish Tissue Contamination

Because all fish were removed from the lake in June 1996 and lake sediments are being removed, present and future exposures are not likely to occur. Past exposures may have occurred. Analysis of fish tissue samples was conducted in 1996. The maximum and average concentrations of metals and pesticides detected in fish tissue at Duck Lake are summarized in Table 4, in Appendix D. Also summarized in Table 4 of Appendix D are Food and Drug Administration (FDA) Action/Guidance Levels and EPA Region III RBCs. In some instances, a large difference (several orders of magnitude) exists between the two standards, so noncancer doses (for both adult and child) and cancer risk values (adult only) were calculated for infrequent fish consumption (i.e., 0.0065 kg/daily or about one 8-ounce fish meal per month) from Duck Lake. The results of these calculations are included in Table 4 and are compared with ATSDR minimum risk levels (MRLs) and EPA reference doses (RfDs, [for those substances for which no ATSDR MRLs exist]). Noncancer dose and cancer risk calculations were not conducted if the maximum concentration detected in fish tissue from Duck Lake was below EPA Region III's RBCs, because these standards are conservative. These evaluations show that the quantities of contaminants present in fish from Duck Lake, in the past, are not likely to be at levels that would present public health hazards from consuming these fish, particularly for people doing so on an infrequent or irregular basis. Because people are not likely to be subsisting on fish from this lake, it is unlikely that past consumption of fish containing the maximum detected concentration would have resulted in any public health hazard. Remediation activities have reduced or eliminated contaminants in the lake, further insuring that harmful exposures are not likely to occur, therefore, present and future exposures present no apparent public health hazard.


Contamination in the "Wetlands Area"

Site Description

The area referred to as the "Wetlands Area" is 400 acres in extent. The site, designated OU2, is adjacent to the RAFB Landfill 4 with the sludge lagoon constructed in the northern portion of the landfill. See Figure 10 for location of this area. The 45-acre Landfill 4 was active from 1965 to 1978, for the disposal of general refuse and industrial waste. The sludge lagoon was active from 1962 until 1978. It was used for the disposal of industrial wastewater treatment sludge and other liquid waste (16). The Wetlands Area formerly received contamination via runoff from the landfill and sludge lagoon, and to a lesser degree via effluent discharged from the RAFB wastewater treatment plant. Highest concentrations of sediment contamination occur in the drainage ditch immediately adjacent to the landfill and sludge lagoon.

During remediation activities at RAFB, runoff from Landfill 4 has been redirected away from the wetlands area. Effluent from the wastewater treatment facility has been redirected into the Ocmulgee River (16). As a result, the likelihood of future contamination has substantially decreased. In addition, because of the isolated location and the restrictions on public access (including fencing), contact with contaminated media would be infrequent. Exposure scenarios for this area would be from incidental dermal exposure or ingestion/inhalation of surface water or soil, or from consumption of fish caught in the wetlands. The principal contaminants detected were metals, with some solvents, pesticides and PAHs (16). Whatever contact might occur would be incidental (or accidental) and infrequent. The levels of contaminants detected were below levels that would present public health hazards for the incidental contact that would be likely. The type of contact likely and the levels present indicate that exposure to sediment or surface water contamination does not present a public health hazard from incidental, infrequent contact via dermal contact or ingestion/inhalation.

Fish Tissue Data from Wetlands Area (Zone 1)

EA Engineering (1995) conducted a study examining the partitioning of chemicals between selected fish tissues (fillet and carcass). EA Engineering analyzed 25 fin fish (largemouth bass, redbreast sunfish, and bluegill) for the presence of 4,4-DDT, 4,4-DDD, 4,4-DDE, dieldrin, heptachlor epoxide, and mercury. 4,4-DDT was detected in only one carcass sample and not in any fillet samples. Study results are shown in Table 5. From a health perspective, the fillet concentrations are of greater interest than the whole carcass concentrations because most people will be assumed to eat the fillet and not the carcass or parts of the carcass.

Contaminant levels measured in the fillets were below FDA Action/Guidance Levels and by that standard would not be considered public health hazards. As an additional conservative measure, ATSDR compared measured fish fillet concentrations with EPA Region III's risk-based concentrations (RBCs). The maximum detected fillet concentrations for mercury, 4,4-DDD, 4,4-DDE, dieldrin, and heptachlor epoxide were higher than for RBCs. It is important to understand that the RBC levels are "screening" values based on very conservative assumptions. First, RBCs are based on the assumption that people might eat fish one or two times a week (0.054 kilograms/day) over the course of 30 years. Second, to be fully protective, screening values are usually set at levels much lower than those known to result in adverse health effects. Therefore, just because a screening value is exceeded does not mean adverse effects would be expected.

ATSDR looked more closely at site-specific conditions to better understand the health implications of available fish data. In doing so, ATSDR concluded that detected contamination levels in fish tissue do not pose public health hazards largely because people are not likely catching and eating fish from this relatively inaccessible area on a regular and frequent basis. The area is remote, overgrown and "swampy", to the extent that regular, frequent usage is not observed. Even in the unlikely event that people were eating about one 8-ounce fish meal per month (or 0.0065 grams/day averaged over a year), estimated exposure doses are lower than those expected to result in adverse health effects, even when assuming exposure to the maximum detected contaminant levels in the fillet (see Table 5a).

ATSDR concludes that infrequent consumption of fish from this area does not present a public health hazard.


QUALITY ASSURANCE AND QUALITY CONTROL

In preparing this Public Health Assessment, ATSDR relied on 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.

Most of the environmental data presented in this public health assessment are from the Remedial Investigation (RI) information. Generally, the methodology used in the RI activity is appropriate for characterizing contamination at RAFB. Additional information collection is planned during completion of RI activities. If this information suggests previously undetected concerns about potential public health hazards, ATSDR will conduct a re-evaluation of that information. Conclusions or recommended actions of this PHA will be modified if appropriate and necessary.


COMMUNITY HEALTH CONCERNS

ATSDR investigated public health concerns through meetings, correspondence, telephone conversations and technical information from RAFB, US EPA, and state agencies. Community public health concerns have been identified regarding the effects of environmental contamination at RAFB. For the most part, the nature of these concerns could be categorized as an interest in understanding the nature of the contamination and the potential for public health effects, rather than concern that specific illnesses had occurred or been caused by environmental contamination. Evaluations of the situations are presented in the body of this document.

During the public comment period for the public health assessment, concern was raised by a member of the local community, regarding the groundwater contamination documented to exist under portions of RAFB. The concern was that this groundwater contamination might be found in locations were members of the public could be exposed. In answer to this concern, ATSDR reiterates the evaluation described above. That is, that although groundwater contamination exists, it is not found in locations where the public might be exposed. Under the oversight of the US EPA and the Georgia EPD, RAFB has thoroughly evaluated the nature and extent of groundwater contamination, finding it to be limited to portions of the aquifers under the base. There are no public or private wells located where contamination might affect them. Additionally, under the oversight of the US EPA and the Georgia EPD, a comprehensive remediation program is underway to monitor and treat water contamination, further decreasing the likelihood that an exposure will occur.


HEALTH OUTCOME DATA

We did not evaluate health outcome databases because people were not exposed to site contaminants at levels that would result in public health hazards.


CHILD HEALTH ISSUES

ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than are adults from certain hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed because they play outdoors and may bring food into contaminated areas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors closer to the ground. Children are also smaller, resulting in higher per body weight doses of chemical exposure. 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.

ATSDR considered the likelihood for children who live on-base, or in the vicinity of RAFB, to be exposed to base contaminants at levels of health concern. ATSDR did not identify any past, present, or future situations in which children were or would be likely to encounter chemical contaminants at RAFB, other than incidental exposure. Although children live on the base, contamination is located in restricted or not-accessed areas and in unused groundwater aquifers.


PREPARERS OF REPORT

Jeffrey A. Kellam
Environmental Health Scientist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

Carl Blair
Regional Representative
ATSDR Region IV


PUBLIC HEALTH ACTION PLAN

Conclusions

1. Low levels of contamination have been detected at RAFB in soil, surface water and sediment in the vicinity of Landfill 3 and associated waste areas. However, these levels and the type of past, present or future exposures that would be likely do not present potential public health hazards.

2. Groundwater contamination exists within RAFB. However public water supplies, as well as base water supplies come from aquifers that are not contaminated and are not likely to have been contaminated in the past. Quarterly monitoring of public and base water supplies is adequate to prevent harmful exposure to contaminants in the future.

3. Contamination has been documented in Duck Lake water, sediment and biota. However, the levels are low enough and the likely exposure infrequent enough that this contamination is not likely to have resulted in public health hazards in the past. Remediation of the lake will further reduce contaminant levels so that present and future exposures are unlikely and no public health hazards are likely.

4. "Wetlands Area" sediments and water have been contaminated, most likely by leachate from Landfill 4. The levels detected are low. The types of infrequent exposures that are likely to have occurred to the low levels of contaminants in water and sediment, as well as any that might have occurred by eating fish from that area, are not likely to have resulted in public health hazards in the past. Remediation and institutional control to access make it unlikely that future exposures will present public health hazards.

5. Several AOCs remain to be investigated. Generally, these areas are not located where public access is likely and the likelihood of substantial exposures is small.

Actions Taken or Planned

Monitoring by the Air Force has delineated the nature and extent of contamination at RAFB. Remediation activities, as determined in cooperation with the US EPA and the Georgia EPD are further reducing the likelihood of present and future exposures.

Regular monitoring is conducted on public and base drinking water supplies, as required by the US EPA and the Georgia EPD, under the Safe Drinking Water Act. This monitoring will ensure that water quality remains acceptable.

Actions Recommended

The principal action ATSDR recommends is continued monitoring of groundwater for SDWA compliance.

Verifying mitigation of the contamination in Duck Lake and the Wetlands Area is recommended in the event that usage of these areas changes in a manner that could result in increased exposure to remaining contaminants. (An example of such a change might be the development of subsistence fishing.)

ATSDR will maintain contact with the RAFB restoration program and regulators during the remediation process. If future situations occur that present potential public health concerns, ATSDR will provide the appropriate evaluations.


REFERENCES

  1. U.S. EPA, Region 4, 1997, National Priority List (NPL) Site Narrative at Listing, Robins Air Force Base, "http://www.epa.gov/superfund/oerr/pics/sf@epa.gif".

  2. Georgia EPD, 1996, Evaluation of Robins Air Force Base's Status under the RCRIS Corrective Action Environmental Indicator Event Codes (CA725 and CA 750), EPA ID Number GA1570024330, September 25, 1996.

  3. U.S. Air Force, 1998, Robins Air Force Base Homepage, Robins AFB.af.mil.

  4. Warner Robins ALC/EMQ, 1998, Draft Final Corrective Action Plan for Landfill No. 3 (IRP SITE Nos. LF03, FT06, WP13) Robins AFB, Georgia, Project No. UHHZ94-7010, March 1998.

  5. Warner Robins ALC/EMQ, 1997, Management Action Plan, Installation Restoration Program, September, 1997.

  6. Warner Robins ALC/EMQ, 1997, Final Basewide Groundwater Sampling, Spring 1997, Volume 1, Robins AFB, Georgia, Project No. UHH97-7003, September 1997.

  7. ATSDR, 1991, Robins AFB Site Scoping Visit Summary Report.

  8. ATSDR, 1998, Record of Communication, Georgia Environmental Protection Division, Mr. Eddie Williams, May 15, 1998.

  9. Georgia EPD, 1994, Trip Report, Robins Air Force Base, January 6, 1994.

  10. Georgia EPD, 1998, SDWA Program database, Robins AFB sampling information 1988-1998.

  11. Warner Robins ALC/EMQ, 1995, Draft Baseline Report, V. 1, Remedial Design Support, Zone 1, Operable Unit 2, Robins Air Force Base, G. September 29, 1995.

  12. Warner Robins ALC/EMQ, 1997, Final Corrective Action Plan for Duck Lake, Delivery Order no. 5011, WRALC, Contract no. F09650-94-D-0035, February 1997.

  13. Rust Engineering, 1996, Technical Memorandum Duck Lake Fish Eradication. Prepared for Environmental Management Directorate, Robins Air Force Base, August 1996.

  14. LAW Engineering, 1995, Draft Final RCRA Facility Investigation Technical Report Addendum for Zone 2B, Site OT29 Duck Lake.

  15. Rust Engineering, 1997, Final Corrective Action Plan for Duck Lake. Prepared for Environmental Management Directorate, Robins Air Force Base, February 1997.

  16. Warner Robins ALC/EMQ, 1998, Baseline Risk Assessment Work Plan for Operable Unit 2 Wetlands Delivery Order 5010, WRALC, Contract No. F09650-94-D-0035, May 1998.

  17. EA Engineering, Science, and Technology. 1995. Partitioning of Chemicals Between Selected Fish Tissues Collected at Warner Robins Air Force Base. Prepared for Armstrong Laboratories, August 1995.

1. Abbreviations and acronyms are listed in Appendix A



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