PUBLIC HEALTH ASSESSMENT
 

EVALUATION OF POTENTIAL EXPOSURES TO CONTAMINATED OFF-SITE GROUNDWATER FROM THE OAK RIDGE RESERVATION (USDOE)
OAK RIDGE, ANDERSON COUNTY, TENNESSEE

III. EVALUATION OF ENVIRONMENTAL CONTAMINATION AND POTENTIAL EXPOSURE PATHWAYS

A release of a contaminant from a site does not always mean that the substance will have a negative impact on a member of the off-site community. For a substance to pose a potential health problem, exposure must first occur. Human exposure to a substance depends on whether a person comes in contact with the contaminant, for example by breathing, eating, drinking, or touching a substance containing it. If no one comes into contact with a contaminant, then no exposure occurs—and thus no health effects can occur. Even if the site is inaccessible to the public, contaminants can move through the environment to locations where people could come into contact with them.

ATSDR evaluates site conditions to determine if people could have been or could be exposed to site-related contaminants. When evaluating exposure pathways, ATSDR identifies whether exposure to contaminated media (soil, water, air, waste, or biota) has occurred, is occurring, or will occur through ingestion, dermal (skin) contact, or inhalation. ATSDR also identifies an exposure pathway as completed or potential, or eliminates the pathway from further evaluation. Completed exposure pathways exist if all elements of a human exposure are present. A release of a chemical or radioactive material into the environment does not always result in human exposure. For an exposure to occur, a completed exposure pathway must exist. A completed exposure pathway exists when all of the following five elements are present:

1. a source of contamination,
2. an environmental medium through which the contaminant is transported,
3. a point of human exposure,
4. a route of human exposure, and
5. an exposed population.

A potential exposure pathway exists when one or more of the elements are missing but available information indicates possible human exposure. An incomplete exposure pathway exists when one or more of the elements are missing and available information indicates that human exposure is unlikely to occur (ATSDR 2001). In addition, for each exposure pathway ATSDR scientists identify whether releases of contaminants and exposures are likely to have occurred in the past, are currently occurring, or could potentially occur in the future.

In preparing this PHA, ATSDR reviewed and evaluated environmental data provided to ATSDR scientists directly from the Department of Energy or in various reports prepared by the Environmental Protection Agency Region IV, the Tennessee Department of Environment and Conservation (TDEC) DOE Oversight Division, or their contractors. ATSDRs evaluation included the identification of inconsistencies and data gaps. The validity of analyses and conclusions drawn in this PHA are based on the reliability of the information referenced in reports related to the Oak Ridge Reservation (ORR). In our assessment, the quality of environmental data available in these documents is sufficient for public health decisions.

Site-related contaminants have not been detected beyond the ORR boundaries near either the ETTP or the ORNL.

This public health assessment is exclusively focused on human exposure to off-site groundwater. Exposure to other media is discussed in other health assessments of ORR performed by ATSDR. Since off-site groundwater contamination only occurs in the area immediately east of Y-12, in Union Valley, this is the only area where exposure scenarios are evaluated. ATSDR scientists have identified three possible exposure scenarios to the EEVOC plume (Table 9). The first exposure scenario involves withdrawal of groundwater for personal use from private groundwater wells. This exposure pathway was eliminated because there is no point of exposure, and there is no receptor population. No groundwater contaminant has been detected above CVs in residential wells, except one sample collected near ETTP in 1998 where boron was detected at a concentration slightly higher than the CV. As previously mentioned, the closest residential well to the EEVOC plume is approximately 2.25 miles away. There is no groundwater being withdrawn for personal use in Union Valley. Institutional controls implemented in accordance with the Interim ROD for Union Valley (DOE 1997) serve to help ensure that no one is drinking contaminated groundwater now or in the future. Residents near ORR who are consuming groundwater are not being exposed to contamination emanating from ORR.

The second exposure scenario evaluated was the possibility of someone coming in direct contact with groundwater at seeps or springs in Union Valley. Since the land overlying the known extent of the contaminant plume is zoned as "Industrial District 2", it is unlikely that individuals will come in contact with springs or seeps in this area. Also, most groundwater surfaces as diffuse discharge directly into Scarboro Creek. Indeed, groundwater constitutes the baseflow for Scarboro Creek in Union Valley (Figure 11). So, it is unlikely that individuals will come into direct contact with groundwater in seeps and springs before dilution with surface water occurs. Exposures to ORR related contaminants in surface waters are excluded in this PHA but are addressed in various other PHAs including: the White Oak Creek PHA, Y-12 Uranium PHA, and the Current and Future Chemical PHAs.

Based upon currently available data, there are no completed exposure pathways for ingestion or direct contact with off-site groundwater. Because of the shallow water table at ORR and the high interconnectivity of the groundwater with the surface water, contaminated groundwater transport is typically along short flow-paths to surface water. The EEVOC plume, east of the Y-12 complex, is the only confirmed off-site groundwater plume. This area is zoned for industrial purposes; therefore, there are no residential areas and, consequently, there are no private wells in use in this area. In fact, the only groundwater withdrawal occurring is from the dewatering operations of the quarry at lot Excess (613) near the eastern end of Union Valley. Contamination has never been detected in the quarry groundwater (DOE 1997). For these reasons, and because there is no point of exposure or receptor population for contaminated groundwater, ATSDR has determined that there are no completed exposure pathways for ingestion or direct contact with off-site groundwater.

Vapor Intrusion as a Potential Exposure Pathway

Vapor intrusion is the migration of volatile chemicals from subsurface soil or groundwater into overlying buildings (USEPA 2002c). Volatile organic compounds (VOCs) present in buried wastes in soil and/or in groundwater can emit vapors that may migrate through subsurface soils and into indoor air spaces of overlying buildings (NJDEP 2005). Often, the vapor concentrations in residences or occupied buildings are low and vapors may not be present at detectable levels, based on the specific conditions of the site. In extreme cases, the vapors may accumulate to levels that may pose safety hazards, acute and/or chronic health effects, or aesthetic issues (USEPA 2002c). As such, vapor intrusion has evolved as a potential exposure pathway of consideration in the investigation of contaminated sites.

Three off-site monitoring wells (GW-169, GW-170, and GW-232) near the Y-12 Complex and within the known extent of the EEVOC groundwater contaminant plume contained twelve contaminants with at least one sample above CVs. The contaminants included the following: aluminum, arsenic, boron, carbon tetrachloride, chloroform, chromium, fluoride, iron, lead, tetrachloroethylene, thallium, and trichloroethylene (Table 4). Of the above-mentioned contaminants detected, only carbon tetrachloride, chloroform, tetrachloroethylene, and trichloroethylene are VOCs. The following VOCs were either absent or detected at concentrations below the CVs in all subsequent samples: chloroform, tetrachloroethylene, and trichloroethylene. In addition, sampling of off-site residential wells near the Y-12 Complex, including the nearest residential well (RWS 67) approximately 2.25 miles east of the known extent of the EEVOC plume, found no contaminants above CVs.

In evaluating potential exposure to groundwater contaminants via vapor intrusion, ATSDR considered the ORR groundwater hydrology. Nearly all groundwater beneath the ORR migrates to surface water before leaving the ORR boundaries. Therefore, additional migration of groundwater contamination off site is unlikely, due to the widespread diffuse discharge of groundwater into the surface water bordering the site.

No residences exist over the EEVOC groundwater contaminant plume. In addition, areas in Union Valley overlying the known extent of the contaminant plume are zoned as "Industrial District 2." There is, however, a portion of an office building overlying the mapped extent of the EEVOC plume in Union Valley (Figure 13). This office building is on Scarboro Rd. just east of the Y-12 Complex. The building is currently used by DOE contractors. Because the apparent extent of the EEVOC plume is beneath this building, it is necessary to evaluate the possibility of vapor intrusion into the workspaces within this building.

The EEVOC groundwater contaminant plume contains carbon tetrachloride, a contaminant of sufficient volatility to be of concern for vapor intrusion. In order to estimate the transport of contaminant vapors from a subsurface source into indoor air spaces, the Johnson-Ettinger Model (JEM) was developed as a screening level model (available at http://www.epa.gov/oswer/riskassessment/airmodel/johnson_ettinger.htm ). Since the JEM is a screening tool, it is based on several conservative assumptions regarding contaminant distribution and occurrence, subsurface characteristics, transport mechanisms, and building construction (USEPA 2004).

Since most of the required JEM input data are not collected during a typical site characterization, conservative inputs were estimated or inferred from available data and other non-site specific sources of information. A groundwater screening model was utilized to estimate the carbon tetrachloride vapor concentration in the building that overlays the EEVOC groundwater contaminant plume.

Table 7 outlines the conservative default parameters and assumptions used in the JEM. The JEM was used to consider carbon tetrachloride vapor intrusion into the building that overlays the EEVOC plume through two soil types (silt and silt clay). Because it is unknown whether the building has a basement or slab-on-grade, the JEM was used to consider both possibilities.

Table 7: JEM Groundwater Screening Model Variables for Vapor Intrusion of Carbon Tetrachloride1 into the Building that Overlays the Off-Site EEVOC Groundwater Plume

JEM Variable	Silt Value	Silty Clay Value	Notes
Depth below grade to bottom of enclosed space floor	200 cm (B) 2 15 cm (S) 2	200 cm (B) 15 cm (S)	Default parameters were used to consider a building constructed with a basement or on a slab.
Depth below grade to water table	364 cm (B) 179 cm (S)	393 cm (B) 208 cm (S)	Regardless of the depth to water, the JEM requires a minimum depth to account for capillary fringe. The capillary fringe is 164 cm for buildings that overlay silt and 193 cm for buildings that overlay silty clay. The shallowest depth allowed by the model was utilized for both the basement and slab scenarios.
Soil type directly above the water table	Silt (B) Silt (S)	Silty Clay (B) Silty Clay (S)	JEM was utilized to consider vapor intrusion into an occupational building with either a basement or a slab, which overlays two types of soil (silt and silty clay). Both types of soil are found in the area of the building.
Average groundwater temperature	15ºC (B) 15ºC (S)	15ºC (B) 15ºC (S)	Average shallow groundwater temperature for Tennessee was calculated by taking the average of the shallow groundwater zones north (14ºC) and south (16ºC) of the state of Tennessee (Figure 8; USEPA 2004).
Vadose zone soil type	Silt (B) Silt (S)	Silty Clay (B) Silty Clay (S)	JEM was utilized to consider vapor intrusion into an occupational building with either a basement or a slab, which overlays two types of soil (silt and silty clay). Both types of soil are found in the area of the building.
Vadose zone soil dry bulk density	1.50 g/cm3 (B) 1.50 g/cm3 (S)	1.50 g/cm3 (B) 1.50 g/cm3 (S)	The universal default parameter which is consistent with USEPA (1996a and b) for subsurface soils.
Vadose zone soil total porosity	0.43 (B) 0.43 (S)	0.43 (B) 0.43 (S)	The universal default parameter which is consistent with USEPA (1996a and b) for subsurface soils.
Vadose zone soil water-filled porosity	0.05 cm3/cm3 (B) 0.05 cm3/cm3 (S)	0.11 cm3/cm3 (B) 0.11 cm3/cm3 (S)	Conservative default parameters for the vadose zone silt and silty clay water-filled porosity (Table 10; USEPA 2004).

¹The predominant VOC in the EEVOC groundwater contaminant plume is carbon tetrachloride. The maximum concentration (200 ppb) of carbon tetrachloride was detected (11/17/1994) above the CV from well GW-170, which is located within the known extent of the EEVOC.
²B = building with a basement; S= building built on a slab

Irrespective of the type of soil that underlies the building (silt or silty-clay), the carbon tetrachloride concentration was estimated to be slightly higher in a building with a basement, as opposed to a building with slab-on-grade construction (Table 8). To evaluate whether workers in this office building are being exposed to levels of VOCs that could potentially result in adverse health effects, ATSDR compared the JEM estimated carbon tetrachloride vapor concentrations to ATSDR's CVs, as well as to occupational exposure guidelines from the Occupational Health and Safety Administration (OSHA) and from the National Institute for Occupational Health and Safety (NIOSH) (Table 8).

Table 8: Estimated Vapor Concentration of Carbon Tetrachloride in the Office Building that Overlays the Off-Site EEVOC Groundwater Plume

Building	Silt	Silty Clay	ATSDR CREG1	ATSDR EMEG2	OSHA PEL3	NIOSH REL4
Basement	2.13 ppb	0.26 ppb	0.01 ppb	30 ppb	TWA = 10,000 ppb C = 25,000 ppb 200,000 ppb peak	ST = 2,000 ppb (60-minute)
Slab	1.80 ppb	0.22 ppb

C = ceiling
ppb = part per billion
ST = short-term exposure limit
TWA = time-weighted average

¹The cancer risk evaluation guide (CREG) is a highly conservative value that would be expected to cause no more than one excess cancer in a million persons exposed over time.
²The environmental media evaluation guide (EMEG) is a media-specific comparison value that is used to select contaminants of concern. Levels below the EMEG are not expected to cause adverse non-carcinogenic health effects.
³Occupational Safety and Health Administration (OSHA) permissible exposure levels (PELs) are regulatory limits on the amount or concentration of a substance in the air one may be exposed to over an 8-hour workday during a 40-hour workweek.

• TWA concentrations for OSHA PELs must not be exceeded during any 8-hour work shift of a 40-hour workweek.
• OSHA ceiling concentrations (C) must not be exceeded during any part of the workday; if instantaneous monitoring is not feasible, the ceiling must be assessed as a 15-minute TWA exposure.
• There is also a 200,000 ppb peak, which means that a 5-minute exposure above the ceiling value, but never above the maximum peak, is allowed in any 4 hours during an 8-hour workday.

⁴The National Institute of Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) indicates a time-weighted average (TWA) concentration for up to a 10-hour workday during a 40-hour workweek. Specifically, the short-term exposure limit (ST) is a 15-minute TWA exposure that should not be exceeded at any time during a workday.

It is important to note that this evaluation was conservative for the following reasons:

• The maximum carbon tetrachloride concentration (200 ppb), rather than an average, from an off-site groundwater monitoring well in the EEVOC plume was used in the calculations. Further, carbon tetrachloride was only detected in 45 of 244 samples, and only 26 of these detections were higher than 7 ppb.
• Default parameters and assumption variables were entered into the model, due to the lack of information regarding the building characteristics and specific depth of the EEVOC groundwater plume in this area. In general, using the default parameters for input variables will result in higher indoor air concentrations (USEPA 2004).
• ATSDR assumed that the EEVOC plume exists in the shallow, transient groundwater zone (between 1 and 7 feet below ground; USGS 1989). The depth below grade to water table variable was the smallest depth one could assume, given the inherent capillary fringe requirement.

In all instances, the estimated vapor concentrations of carbon tetrachloride in the office building are much less than ATSDR's environmental media evaluation guide (EMEG) and the OSHA and NIOSH regulatory limits. Even though the estimated vapor concentrations are above the cancer risk evaluation guide (CREG), ATSDR does not expect vapor intrusion to be a concern for the people who work in the building that overlays the EEVOC plume, especially given the conservative nature of the evaluation. The CREG is a highly conservative CV that is based on exposure in a residential setting 24 hours/day, every day of the year. Occupational (i.e., 8 hours/day, 40 hours/week) exposure would be much lower.

Based on currently available data and the results of the JEM, ATSDR concludes that groundwater does not pose a public health hazard via a vapor intrusion exposure pathway. Although the EEVOC groundwater contaminant plume emanating from the Y-12 complex has migrated off site, no residences overlay the plume. The nearest residence is approximately 2.25 miles east of the known extent of the EEVOC plume. One office building partially overlies the plume; however, conservative modeling indicates that estimated VOC concentrations are well below the EMEG and several orders of magnitude below the regulatory limits for occupational exposure.

Table 9: Exposure Pathways

Pathway	1. Source of Contamination	2. Fate and Transport	3. Point of Exposure	4. Route of Exposure	5. Receptor Population	Time Frame	Conclusion for Pathway
	Five Components of a Completed Exposure Pathway
Contacting GW from Private wells in Union Valley	EEVOC Plume from the Y-12 Complex	Plume is migrating east along strike in the Maynardville Limestone Formation. It extends off-site into Union Valley.	None. There are no residences deriving drinking water from private wells in this area.			Past, Present, Future	Incomplete
Contacting groundwater from seeps and springs in Union Valley	EEVOC Plume from the Y-12 Complex	EEVOC plume has migrated off-site and discharges at various seeps and springs throughout Union Valley	Potential use of, or contact with, spring water from Union Valley.	Ingestion, dermal contact, inhalation	None likely. Seeps and springs feed Scarboro creek so isolated contact with groundwater from seeps and springs before dilution in surface water is unlikely.	Past, Present, Future	Incomplete
Inhaling VOCs via vapor intrusion into buildings in Union Valley	EEVOC Plume from the Y-12 Complex	EEVOC plume has migrated off-site under	Working in the office building immediately east of Y-12.	Inhalation	Individuals working in the building	Past, present, future	Potentially Complete

IV. PUBLIC HEALTH IMPLICATIONS

ATSDR scientists have determined that there are no completed exposure pathways for ingestion or direct contact with off-site groundwater at ORR. The only confirmed contamination to have migrated off-site was from EEVOC contaminated groundwater plume originating in the Y-12 Complex. There has been no site-related groundwater contamination detected off-site either at the ETTP (former K-25 and S-10), or the ORNL (former X-10) facilities. This is likely due to the widespread diffuse discharge of groundwater into the surface water bordering the site. Groundwater is a known contributor to surface water contamination throughout the ORR. However, this PHA only addresses human exposure to off-site groundwater.

Y-12

The exposure investigation of this document addressed three possible exposure scenarios for contacting contaminated groundwater emanating from the Y-12 complex, two were eliminated because there are no points of exposure (i.e., contaminants have not been detected above CVs in private wells and there is no ready access to springs and seeps) and there is no receptor population. Exposure to the contaminated groundwater is unlikely to occur because there are no private wells and no residences near the EEVOC plume in Union Valley. The third possible exposure pathway – vapor intrusion into an office building overlying the EEVOC plume – has been conservatively modeled with results indicating estimated VOC concentrations well below occupational regulatory guidelines. ATSDR scientists have determined that there are no public health implications associated with contaminants from the Y-12 Complex.

ETTP and ORNL

A discussion of how the groundwater of the ORR typically flows has been presented in this document in the Site Geology/Hydrogeology section. There, it is illustrated that groundwater movement beneath streams and rivers in this area is limited at best. While it is true that water does occur beneath the stream beds, most is actually taken up into the stream flow (gaining stream system) through diffuse discharge from the groundwater. Some groundwater can be retained in the alluvium beneath and adjacent to the stream beds in the hyporheic zone, but core samples near the UEFPC indicate that there is a glei horizon beneath the stream bed which limits downward groundwater migration (USGS1989). Cracks and fissures in the karst rock formations underlying ORR significantly decrease with depth, thereby further limiting migration of contaminants to shallow plumes intercepted by surface water either by seeps and springs, which are common throughout the ORR, or as baseflow for creeks and streams. Also, site-related contaminants have not been detected beyond the ORR boundaries near either ETTP or ORNL in seeps/springs, monitoring wells or residential wells. For these reasons, ATSDR scientists have determined that there are no public health implications related to exposure to contaminated groundwater from either ETTP or ORNL.

V. HEALTH OUTCOME DATA EVALUATION

Health outcome data are measures of disease occurrence in a population. Common sources of health outcome data are existing databases (cancer registries, birth defects registries, death certificates) that measure morbidity (disease) or mortality (death). Health outcome data can provide information on the general health status of a community—where, when, and what types of disease occurs and to whom it occurs. Public health officials use health outcome data to look for unusual patterns or trends in disease occurrence by comparing disease occurrences in different populations over periods of years. These health outcome data evaluations are descriptive epidemiologic analyses. They are exploratory as they may provide additional information about human health effects and they are useful to help identify the need for public health intervention activities (for example, community health education). However, health outcome data cannot—and are not meant to—establish cause and effect between environmental exposures to hazardous materials and adverse health effects in a community.

ATSDR scientists generally consider health outcome data to evaluate the possible health effects in a population known to have been exposed to enough environmental contamination to experience health effects. In this pubic health assessment on off-site groundwater at ORR, ATSDR scientists determined that people were not and are not using private groundwater wells and were not exposed to ORR related contaminants from groundwater exposure. For these reasons, health outcome data will not be evaluated in this public health assessment.

VI. COMMUNITY HEALTH CONCERNS

Responding to community health concerns is an essential part of ATSDR's overall mission and commitment to public health. ATSDR actively gathers comments and other information from the people who live or work near the ORR. ATSDR is particularly interested in hearing from residents of the area, civic leaders, health professionals, and community groups.

To improve the documentation and organization of community health concerns at the ORR, ATSDR developed a Community Health Concerns Database that is specifically designed to compile and track community health concerns related to the site. The database allows ATSDR to record, track, and respond appropriately to all community concerns, and also to document ATSDR's responses to these concerns. From 2001 to 2003, ATSDR compiled more than 2,500 community health concerns obtained from the ATSDR/ORRHES community health concerns comment sheets, written correspondence, phone calls, newspapers, comments made at public meetings (ORRHES and work group meetings), and surveys conducted by other agencies and organizations. These concerns were organized in a consistent and uniform format and imported into the database.

The community health concerns addressed in this public health assessment are those concerns in the ATSDR Community Health Concerns Database that are directly related to issues associated with groundwater contamination on-site and movement of the contaminant plume off-site. Table 10 contains the actual comments and ATSDR's responses.

Table 10: Community Health Concerns from the Oak Ridge Reservation Community Health Concerns Database and ATSDR Responses

#	Comment	ATSDR Response
1	Is the groundwater helping to contribute to kidney cancer? -and, Past exposures to arsenic from groundwater may have resulted in high levels of arsenic in my body.	Since ATSDR scientists have concluded that there is no exposure to contaminated groundwater from ORR (see the Evaluation of Environmental Contamination and Potential Exposure Pathways section of this document), it is unlikely that any incidence of kidney cancer or elevated levels of arsenic in the body of citizens in the surrounding area is attributable to consumption of groundwater.
2	Groundwater flows from the Y-12 plant to Scarboro.	The East End Volatile Organic Compound (EEVOC) plume flows east-northeast along strike, paralleling the underlying geology. Current DOE plume mapping indicates that the EEVOC is entirely in the Maynardville Limestone (part of the Conasauga Group – See Figure B-1), an aquifer formation with relatively high hydraulic conductivity. The Scarboro community is located on the Rome formation that consists of low-conductivity shales and siltstones. It is unlikely that water will migrate from areas with higher hydraulic conductivity to those with less.
3	What effect do the solid waste storage areas have on groundwater?	Solid waste storage areas (SWSA) are discussed in the Melton Valley Watershed section of this document.
4	Concern that communities that share a limestone slab with a burial ground or dumping ground might have contaminated groundwater.	A thorough investigation of the underlying geology of the ORR and surrounding areas, as well as the contaminated groundwater from ORR, with respect to the communities nearby is the focus of this public health assessment. We hope that the specific information we have presented in this PHA about each of the facilities at ORR has answered this general question about public contact with contaminated groundwater. For specific information regarding the geology and hydrology of the ORR, please refer to Appendix B.

VII. CONCLUSIONS

It is important for the reader to understand that ATSDR scientists acknowledge the fact that karst systems are notoriously difficult to fully characterize with respect to groundwater flow direction and rate. We have based our conclusions on currently available data concerning groundwater flow and specific contaminant fate and transport from well monitoring data. There are large solution cavities beneath ORR and the surrounding area which are often interconnected and have high flow rates. Some have been encountered in various well drilling activities or by casual observation, and some have yet to be discovered. Our conclusions are based upon well supported information of groundwater flow and contaminant transport. While much is unknown or fully understood about karst systems in general, it is our intention to assess the currently available data, and to arrive at a conclusion of whether the community has had (or is currently having) an exposure to contaminants in off-site groundwater.

Another point of consideration is that of the possibility of the over-pumping of groundwater wells creating a negative hydraulic gradient which could draw contaminants against the normal flow of groundwater. It is true that heavy well pumping can create a negative hydraulic gradient and cause groundwater to flow toward the well in all directions. Also, the theoretical potential exists for contaminated water to be drawn from surface water sources. However, based on available data, we do not believe this is occurring in residential wells or monitoring wells surrounding the reservation.

This public health assessment addresses off-site (community) exposures to contaminated substances released to the groundwater from the Oak Ridge Reservation. Having thoroughly evaluated past public health activities and available current environmental information, ATSDR has reached the following conclusions:

• Although extensive groundwater contamination exists throughout the ORR, ATSDR scientists have concluded that there is No Public Health Hazard from exposure to contaminated groundwater emanating from ORR. This conclusion category is used for sites that, because of the absence of exposure, do not pose a public health hazard. Sufficient evidence exists that no human exposures to contaminated groundwater have occurred, no exposures are currently occurring, and exposures are not likely to occur in the future (ATSDR 2005). The EEVOC plume emanating from the Y-12 complex is the only confirmed off-site groundwater plume. Table 9 illustrates the three exposure scenarios that were considered for this public health assessment: 1) contacting groundwater from private wells in Union Valley, 2) contacting groundwater from seeps and springs in Union Valley, and 3) vapor intrusion in to the off-site office building east of Y-12. Based on the fact that groundwater has short flow paths to surface water in this area and that there are no private wells pumping groundwater in this area, ATSDR scientists concluded that there were no completed exposure pathways for ingestion or direct contact with off-site groundwater. Also, extremely conservative modeling indicates that estimated VOC concentrations in the office building are much less than ATSDR's EMEG and the OSHA and NIOSH regulatory limits. Even though the estimated vapor concentrations are above the extremely conservative CREG, ATSDR does not expect vapor intrusion to be a concern for the people who work in the building that overlays the EEVOC plume.
  
  
• Groundwater and surface water are highly interconnected throughout the ORR. Groundwater flow in this area (ORR) is influenced largely on the extent of fractures in the bedrock which create preferential flow paths. In the regional aquifers of East Tennessee, including those underlying the ORR, fractures in bedrock are typically limited to the upper extents of the bedrock formations and significantly decrease with depth (MMES 1986, USGS 1986b, USGS 1988, USGS 1989, SAIC 2004). The numerous springs and seeps in the area support the notion of a very active shallow groundwater system in the ORR. Also, groundwater will flow along bedding planes and along strike, especially in areas where carbonate units have well-developed conduit systems (ORNL 1982, USGS 1997). Therefore, groundwater constitutes much of the baseflow of many streams and tributaries in the area, including East Fork Poplar Creek (USGS 1989, SAIC 2004). It is unlikely that contaminated groundwater at the ORR will flow beneath, and continue to flow away from, streams and rivers that surround the site. Indeed, the incised meander (see Appendix A) of the Clinch River in bedrock represents a major topographic feature that prevents groundwater from passing beneath the river (ORNL 1982).

VIII. RECOMMENDATIONS

Having evaluated past public health activities and the available environmental information, ATSDR recommends that the community be informed that ATSDR has evaluated off-site groundwater contamination from the Oak Ridge Reservation and has concluded that there is no public health hazard associated with past and current releases.

In this PHA, ATSDR scientists used every data source available to compile a database of off-site groundwater sampling results, albeit from monitoring wells, residential wells, or from seeps and springs nearby. While CERCLA requires groundwater monitoring, residential well sampling is not regularly conducted by either the State of Tennessee or by DOE. Therefore, we recommend that a regular periodic residential well-sampling program be initiated in order to assure that these wells remain free of ORR site-related contaminants.

ATSDR also recommends that institutional controls set forth in the Interim Record of Decision for Union Valley (Jacobs EM Team 1997a) remain in place to prevent exposure to contaminated groundwater. These controls should remain in place until all off-site contamination in Union Valley is reduced to below levels of health concern.

IX. PUBLIC HEALTH ACTION PLAN

The public health action plan for the Oak Ridge Reservation (ORR) contains a description of actions taken at the site and those to be taken at the site following the completion of this public health assessment. The purpose of the public health action plan is to ensure that this public health assessment not only identifies potential and ongoing public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to harmful substances in the environment. The following public health actions at the ORR are completed, ongoing, or planned:

Completed Actions

• In 1991, the Tennessee Department of Health (TDOH) began a two-phase research project to determine whether environmental releases from ORR harmed people who lived nearby. Phase I focused on assessing the feasibility of doing historical dose reconstruction and identifying contaminants that were most likely to have effects on public health. Phase II efforts included full dose reconstruction analyses of iodine 131, mercury, polychlorinated biphenyls (PCBs), and radionuclides, as well as a more detailed health effects screening analysis for releases of uranium and other toxic substances (a summary can be found in the Oak Ridge Dose Reconstruction Project Summary Report, Volume 7). Phase II was completed in January 2000. All of the final reports from Phase I and Phase II of the Oak Ridge Environmental Dose Reconstruction Project are accessible from the DOE public use database called Comprehensive Epidemiologic Data Resource (CEDR). This database contains information pertinent to health-related studies performed at Oak Ridge Reservation and other DOE sites. The URL for the Phase I and Phase II Dose Reconstruction Project is – http://cedr.lbl.gov/DR/dror.html
  
  
• In 1992, the U.S. Department of Energy (DOE) conducted a Background Soil Characterization Project in the area around Oak Ridge (DOE 1993).
  
  
• In 1993, ATSDR evaluated public health issues related to past and present releases into the creek from the Y-12 Complex in a health consultation, Y-12 Weapons Plant Chemical Releases Into East Fork Poplar Creek (ATSDR 1993).
  
  
• In 1996, ATSDR evaluated the current public health issues related to the past and present releases into the Lower Watts Bar Reservoir from the ORR in a Health Consultation on the Lower Watts Bar Reservoir (ATSDR 1996).
  
  
• In 1998, the Environmental Sciences Institute at Florida Agricultural and Mechanical University (FAMU), along with its contractual partners at the Environmental Radioactivity Measurement Facility at Florida State University, and the Bureau of Laboratories of the Florida Department of Environmental Protections, as well as DOE subcontractors in the Neutron Activation Analysis Group at Oak Ridge National Laboratory and the Jacobs Engineering Environmental Management Team, sampled soil, sediment, and surface water from Scarboro to address community concerns about environmental monitoring in the neighborhood (FAMU 1998).
  
  
• In 2001, the U.S. Environmental Protection Agency (EPA) collected samples of soil, sediment, and surface water from the Scarboro community to address community concerns and verify the results of the 1998 sampling conducted by FAMU (EPA 2003).
  
  
• In 2004, the Agency for Toxic Substances and Disease Registry (ATSDR) released the final ORR Public Health Assessment for Y-12 Uranium Releases.

Ongoing Actions

• ATSDR will continue to evaluate contaminants and pathways of concern to the community surrounding the reservation. In addition to this evaluation of groundwater, ATSDR is evaluating uranium from the Y-12 Complex, uranium and fluorides from the K-25 facility, iodine 131, mercury, White Oak Creek releases in the 1950s, PCBs, and the TSCA incinerator.
  
  
• In 1999, the Oak Ridge Reservation Health Effects Subcommittee (ORRHES) was created under the guidelines and rules of the Federal Advisory Committee Act to provide a forum for communication and collaboration between citizens and the agencies that are evaluating public health issues and conducting public health activities at the ORR. The ORRHES serves as a citizen advisory group to CDC and ATSDR and provides recommendations on matters related to public health activities and research at the reservation. It also provides an opportunity for citizens to collaborate with agency staff members, to learn more about the public health assessment process and other public health activities, and to help prioritize public health issues and community concerns to be evaluated by ATSDR.
  
  
• DOE has developed a Groundwater Strategy document (USDOE 2004) that lays out a plan for making future decisions on groundwater remediation on the ORR on a watershed scale. Previously, groundwater contamination had been dealt with on a site-by-site basis. The goal is to evaluate various groundwater remediation technologies for that areas within the same water transport system (watershed) and have similar contamination problems and land uses in an effort to increase cost-effectiveness.

X. PREPARERS OF REPORT

Trent D. LeCoultre, MSEH, REHS
Environmental Health Scientist
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

Jack Hanley, M.P.H.
Environmental Health Scientist
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

XI. REFERENCES

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ATSDR. 1996a. Health consultation for U.S. DOE Oak Ridge Reservation: Lower Watts Bar Reservoir Operable Unit. Oak Ridge, Anderson County, Tennessee. Atlanta, Georgia: U.S. Department of Health and Human Services. February 1996.

ATSDR. 1996b. Health consultation for U.S. DOE Oak Ridge Reservation: proposed mercury clean-up level for the East Fork Poplar Creek floodplain soil, Oak Ridge, Anderson County, Tennessee. Atlanta: U.S. Department of Health and Human Services.

ATSDR, National Center for Environmental Health, National Institute for Occupational Safety and Health, Tennessee Department of Health, Tennessee Department of Environment and Conservation, U.S. Department of Energy. 2000. Compendium of public health activities at the U.S. Department of Energy. November 2000. Available from URL: http://www.atsdr.cdc.gov/HAC/oakridge/phact/c_toc.html.

ATSDR. 2004. Public Health Assessment, Y-12 Uranium Releases, Oak Ridge Reservation. Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services, Atlanta, GA, January 30, 2004.

ATSDR. 2005. Public Health Assessment Guidance Manual (Update). U.S. Department Of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, Atlanta, GA. Available from URL: http://www.atsdr.cdc.gov/HAC/PHAManual/index.html

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Benfield R. 2002. ORRHES meeting minutes. TDEC groundwater geologist presentation. October 22, 2002. Available from URL: http://www.atsdr.cdc.gov/HAC/oakridge/meet/orr/m10_02.pdf.

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ChemRisk. 1993b. Oak Ridge health studies, phase I report. Volume II—part A—dose reconstruction feasibility study. Tasks 1 & 2: A summary of historical activities on the Oak Ridge Reservation with emphasis on information concerning off-site emissions of hazardous materials. Oak Ridge Health Agreement Steering Panel and Tennessee Department of Health. September 1993. Available from URL: http://cedr.lbl.gov/DR/OAKPDF/historicalops.pdf

ChemRisk. 1993c. Oak Ridge health studies, phase I report. Volume II—part B—dose reconstruction feasibility study. Tasks 3 & 4: Identification of important environmental pathways for materials released from Oak Ridge Reservation. Oak Ridge Health Agreement Steering Panel and Tennessee Department of Health. September 1993. Available from URL: http://cedr.lbl.gov/DR/OAKPDF/importexposure.pdf

ChemRisk. 1993d. Oak Ridge health studies, phase 1 report. Volume II—part C—dose reconstruction feasibility study. Task 5: A summary of information concerning historical locations and activities of populations potentially affected by releases from the Oak Ridge Reservation. Tennessee Department of Health and the Oak Ridge Health Agreement Steering Panel. September 1993. Available from URL: http://cedr.lbl.gov/DR/OAKPDF/historicalocations.pdf

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