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PETITIONED HEALTH ASSESSMENT

OLD DOUGLAS COUNTY LANDFILL
(a/k/a: DOUGLAS COUNTY/CEDAR MOUNTAIN LANDFILL)
DOUGLASVILLE, DOUGLAS COUNTY, GEORGIA


DISCUSSION

A. Methods

The following sections contain an evaluation of the environmental data available for the Old Douglas County Landfill. In preparing this evaluation, ATSDR staff members have used established methodologies for determining how people may be exposed to potential contamination related to the landfill and what harmful effects, if any, may result from such exposure. ATSDR uses comparison values (CVs), which are screening tools used to evaluate environmental data that are relevant to the exposure pathways. Comparison values are concentrations of contaminants that are considered to be safe levels of exposure. Chemicals that are detected below CVs are not a health concern; chemicals that are detected above CVs require a more detailed evaluation of site specific exposure conditions. For a complete discussion of these (quality assurance considerations, human exposure pathway analyses, ATSDR's health comparison values, and the methods of selecting contaminants above comparison values), refer to Appendix B.

B. Extent of Contamination

Air

Ambient air sampling has not been conducted in the vicinity of the Old Douglas County Landfill. There are no records or complaints of strong odors coming from the landfill. Douglas County is not required to measure methane levels at this landfill, although, staff members conduct quarterly on-site methane monitoring to determine if methane is accumulating in the landfill. The method of methane monitoring used by landfill staff is consistent with EPD's recommended methods for subsurface soil gas monitoring [6]. Sampling locations are limited to four areas around the remote control airplane landing strip on the landfill. Based on these few sampling locations in only one area of the landfill, ATSDR cannot state whether methane is migrating off-site toward residential areas. ATSDR reviewed past and current measurements of methane. These measurements revealed that concentrations of methane at the sampling locations were detected 20 times below levels that would cause harm to persons on-site (detected levels were at 0-1%) [7]. Based on these readings, methane exposure is no threat to public health near the remote control airplane landing strip on the Old Douglas County Landfill.

Soil

Upon closure in 1989, the final clean soil cover depth added to the Old Douglas County landfill ranged between 2 to 6 feet [8]. Soil samples were collected at the landfill in 1994 to characterize the extent of contamination by analyzing for 17 organic and volatile organic compounds and 17 metals [9]. Off-site soil samples were also collected from two locations (one surface soil and one subsurface soil sample) in the mobile home park (Corn Crib Mobile Home Park) west of the landfill boundary. Manganese and lead were detected at the landfill above ATSDR's comparison values1. Manganese, lead, and iron were detected at the mobile home park above ATSDR's screening values and were evaluated in further detail . Potential exposure to manganese and lead is discussed further in Section C, Public Health Implications of Contaminants of Concern of this document.

Groundwater

Based on a topographic map of the Old Douglas County Landfill and known well depths in Douglas County, the depth of groundwater is estimated to be 30-60 feet below the land surface [3, 9]. The fractured bedrock depth in the vicinity of the landfill is approximately 25 feet; the landfill may fall within a groundwater recharge area [10]. There are no permanent groundwater monitoring wells located on or near the Old Douglas County Landfill. However, ATSDR reviewed groundwater data from two on-site temporary monitoring wells, one temporary off-site monitoring well, and six off-site private drinking water wells to determine if the landfill has had an impact on the groundwater. The nearest private well is located approximately 1,000 feet east of the landfill. The groundwater flow direction in the vicinity of the landfill is southeast toward Gothard's Creek [11]. No municipal drinking water wells were located in the vicinity of the landfill. Most residents in the vicinity of the Old Douglas County Landfill, including Corn Crib Mobile Home Park, receive drinking water from the Douglasville-Douglas County Water and Sewer Authority. This county municipality obtains its water from the Dog River and Bear Creek Reservoirs, which are more than fifteen miles from the landfill [9].

Private Wells

The Georgia Department of Natural Resources (DNR) identified six private wells within a half mile that are currently being used for potable water. These six private wells were sampled by DNR to characterize and determine the potential impact from the landfill. A seventh private well owner located approximately two miles down gradient of the groundwater flow path and the landfill independently tested the groundwater to determine the quality of potable water. The private wells were tested for 16 metals and 92 volatile organic compounds. There were no contaminants detected in private wells at levels of health concern [12][13]. ATSDR concludes that the seven private wells sampled are safe for potable use.

Temporary Monitoring Wells
The two temporary monitoring wells, which are not used as potable water sources, are not required to be routinely monitored for chemicals. The results in this report are from a groundwater analysis performed in 1994. There were several metals detected in the temporary monitoring wells at the landfill and off-site, just beyond the landfill property line, above ATSDR's comparison values (Appendix C, Table 3). It appears that groundwater contamination has occurred at the landfill and has migrated off-site. Human consumption of this contaminated groundwater is not occurring presently, however, it appears possible that future use of groundwater near the landfill may occur. Douglas County has had a rapid increase in urban development as it is considered one of the metropolitan counties of Atlanta, Georgia. Based on the evidence of groundwater contamination, there is also the potential that landfill related contaminants could migrate toward private drinking water wells in the future. An annual groundwater monitoring program at the perimeter of the landfill would indicate such migration in advance. If site-related contaminants enter any drinking water wells, appropriate actions should be taken to prevent or eliminate human exposure to those contaminants. There is no current human exposure associated with groundwater contamination; therefore, ATSDR concludes there is no threat to public health related to the groundwater contamination.

Surface Water and Sediment

The lowest part of the landfill is Gothard's Creek which intersects the landfill property. There are also four settling ponds, an open trench, and two intermittent creeks on-site. As a result, precipitation runoff drains downslope into Gothard's Creek, the four settling ponds and the open trench. The Georgia Environmental Protection Division noted leachate from the landfill entering Gothard's Creek during a 1993 site visit [14]. Due to this observation, it is suspected that contamination from the landfill has migrated off-site via Gothard's Creek. ATSDR reviewed surface water and sediment sampling data from Gothard's Creek and the settling ponds. There were no surface water contaminants detected above ATSDR's comparison values in Gothard's Creek, its tributaries, the settling ponds, or the trench. The surface water in the vicinity of the Old Douglas County Landfill is not of public health concern.

Sediment levels of three metals (lead, manganese, and iron) were detected in the settling ponds on-site and in Gothard's Creek both on- and off-site above ATSDR's comparison (or screening values)2. In the environment, metals attach to soil particles, settle out of surface water, and accumulate in sediments. A discussion of possible exposure to these metals is in Section C, Public Health Implications of Contaminants of Concern.

C. Public Health Implications of Contaminants of Concern (COCs)

ATSDR reviewed available data for all environmental media (groundwater, surface water, soil, sediment, and methane levels) sampled in the vicinity of Old Douglas County Landfill. At the completion of the data review and analysis, ATSDR selected the following chemicals as contaminants of concern (COCs): lead, manganese, and iron. Additional environmental and toxicological evaluations were required for each of these chemicals.

Lead, manganese, and iron were selected as contaminants of concern because concentrations of these chemicals exceeded ATSDR's comparison values or a comparison value has not been developed. Two potential routes of exposure to these contaminants were identified. The first route is direct contact with the contaminated soil and sediment with exposure occurring as a result of dermal contact or incidental ingestion of soil and sediment. The second is an indirect route of exposure via consumption of fish from Gothard's Creek that may accumulate contaminants that are in the sediments. A discussion of potential exposure to these chemicals as a result of human activities at the landfill is in the following paragraphs.

Potential Soil and Sediment Exposure

Lead
Low levels of lead were detected in soil and sediment samples collected on- and off-site. The maximum concentration of lead detected at the Cedar Mountain Landfill was 54 parts per million (ppm) in the sediments of a settling pond in the northeast section of the landfill. The concentration of lead detected in sediments ranged from 3.7-54 ppm. The surface soil concentration of lead in the mobile home park ranged from 5.2 - 20 ppm. A maximum allowable level of 250 ppm lead is recommended in areas without grass cover that are frequently used as play areas by children [15]. In addition, based on the frequency of contact with the contaminated areas, it is unlikely that children would frequently play in the settling ponds and come in contact with the sediments (the likely point of maximum contamination). The landfill also has a grass cover that deters direct contact with the surface soil at the landfill. Adverse health effects are not expected as a result of direct exposure to lead in the soil and sediments at Old Douglas County Landfill.

Manganese
EPA Region III develops tables of risk-based acceptable concentrations; the one for manganese is 1800 ppm for residential soils. Manganese was detected below this concentration at all locations except the settling pond sediments in the northeast section of the landfill. The maximum concentration of manganese detected at this location was 4,800 ppm or 4.8 mg/gram of sediment. Manganese, like a number of other metals (iron, copper, zinc), is an essential element of the diet. The Food and Nutrition Board of the National Research Council has set an Estimated Safe and Adequate Daily Dietary Intake (ESADDI) of 2 to 5 milligrams (mg) for manganese. ATSDR has an interim guidance of 0.07 milligrams per kilogram per day (mg/kg/day) that is based on the upper limit of the ESADDI [16]. It is unlikely that a person would come in contact with the contaminated sediment frequently. It is also unlikely that exposure to manganese in the soil or sediment at the landfill would significantly increase the normal dietary intake of manganese. Adverse health effects are not expected as a result of exposure to manganese at this site.

Iron
The maximum concentration of iron detected at the Cedar Mountain Landfill was 85,000 ppm in the sediments of a settling pond in the northeast section of the landfill. Iron was also detected in subsurface soil at the mobile home park at a concentration of 43,000 ppm. ATSDR estimated an exposure dose using an unlikely situation of a child ingesting the maximum concentration of iron in sediment (85,000 ppm) on a daily basis. According to this scenario, the levels consumed by a child were five times less than the Recommended Dietary Allowance (RDA), which is a guideline of proper nutrition and diet [17]. Also, it is unlikely that a child would consume sediment and soil from the landfill on a daily basis. Adverse health effects are not expected as a result of exposure to iron at this site.

Based on the detailed review of possible exposure situations to these three metals in sediments and soil, ATSDR considers the sediment in the settling ponds at Old Douglas County Landfill and Gothard's Creek are not of public health concern at the present time. However, ATSDR does recommend that measures should be taken to ensure that daily contact with the contaminated sediment is prevented. Currently, soil exposure is not a public health concern, both on- and off-site.

Fish Consumption

The concentration of manganese, iron, and lead detected in the sediments in the settling ponds and Gothard's Creek are not at levels of health concern. It is unlikely that these metals would accumulate significantly in fish tissue due to both the small amounts present and the bioavailability (or accumulation rates) of the specific metals involved. In addition, based on the small size of Gothard's Creek near and on the landfill, it is unlikely that people consume fish from these areas on a routine basis.

D. ATSDR Child Health Initiative

As part of ATSDR's Child Health Initiative, a section is included in all ATSDR health based documents to address potential exposures of children to contaminants. Children are at greater risk than adults from certain kinds of exposure to hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed for several reasons; children play outside more often than adults, increasing the likelihood that they will come into contact with chemicals in the environment. Since they are shorter than adults, they breathe more 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 damage if toxic exposures occur during certain growth stages.

Many children live in the mobile home park adjacent to the landfill and have access to it. Therefore, ATSDR closely reviewed this potential exposure to children while evaluating this site. ATSDR also used the Environmental Media Evaluation Guidelines (EMEG) for children, who are considered the most sensitive segment of the population. ATSDR did not identify any chemical contaminants at levels of health concern to children.

E. Physical Hazards

The Old Douglas County Landfill is an inactive landfill that is accessible to trespassers. The potential for accidents involving trespassers on-site is evident from the off-road vehicle trails, children's treehouses, and deer hunting stands. Methane has been monitored near the landing strip for remote controlled airplanes. However, no other methane gas measurements have been taken to determine if methane is migrating off-site at levels that might be explosive.



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