This public health assessment (PHA) evaluates environmental exposures to contaminants released from the "TSCA Incinerator" at the U.S. Department of Energy (DOE) Oak Ridge Reservation (ORR) in Roane County, Tennessee. The incinerator's name comes from the Toxic Substances Control Act, or TSCA, one of the environmental regulations governing the incinerator's operations. DOE contractors operate the TSCA Incinerator at a facility currently known as East Tennessee Technology Park (ETTP), formerly known as the K-25 site and as the Oak Ridge Gaseous Diffusion Plant. The TSCA Incinerator destroys organic chemicals in waste material and reduces the volume of waste materials that contain low-level radioactive contamination. The TSCA Incinerator began routine operations in 1991, and continues to operate today.
The Agency for Toxic Substances and Disease Registry (ATSDR) prepared this PHA to evaluate environmental health issues related to the TSCA Incinerator. The scientific approaches used in this PHA are consistent with relevant policies and guidance documents that ATSDR and other agencies have developed specifically for assessing human health risks posed by incineration facilities. The PHA focuses almost entirely on direct inhalation exposures to airborne contaminants, which presents the most likely pathway by which residents might come into contact with site-related contaminants. A separate PHA will consider the possibility of the TSCA Incinerator's air emissions causing environmental contamination in other media, such as surface water, soils, and food items.
What are the objectives of this PHA? (1) To determine whether local residents, other than workers, have been harmed by contaminants released by the TSCA Incinerator; (2) to respond to specific community concerns about the TSCA Incinerator; and (3) to make recommendations to help ensure that residents will not be exposed to harmful levels of site-related contaminants in the future.
This PHA's conclusions are based largely on environmental sampling data, stack tests, and other records generated by multiple parties. Over the last 2 years, ATSDR obtained documents and insights from
ATSDR considered all information provided by these parties when preparing this PHA.
The TSCA Incinerator has been studied extensively and continuously since it began routine operations in 1991. Multiple parties have quantified what the TSCA Incinerator releases into the air, modeled how contaminants move through the air, and measured what levels of air contamination are found beyond the ETTP facility property line. To date, ATSDR has reviewed tens of thousands of environmental measurements taken over the entire time that the TSCA Incinerator has operated. This PHA's conclusions, therefore, are based on an extremely large volume of data, especially when compared with data available for other incineration facilities that ATSDR has evaluated over the years. The remainder of this section presents ATSDR's key findings on the TSCA Incinerator, starting with the main conclusion, followed by summary statements on other issues.
Main Conclusion
The TSCA Incinerator releases trace levels of contaminants into the environment, but in amounts far below levels associated with health effects. Continued operation of the TSCA Incinerator is not expected to cause harmful exposures because numerous safeguards, pollution controls, and strict permitting requirements are in place to prevent unsafe operating conditions from occurring.
The following paragraphs review ATSDR's key findings on several individual topics. As Figure 1 illustrates, these individual findings paint a consistent picture of the limited air quality impacts from the TSCA Incinerator, and they form the foundation for the main conclusion stated above.
With few exceptions, measured emission rates have been below health-protective limits established in the incinerator's environmental permits. In the isolated instances where higher emission rates were observed, ambient air monitoring data collected at the time show that air contamination at off-site locations was not affected. For many pollutants, the TSCA Incinerator's emissions account for an extremely small fraction of the total airborne emissions estimated for all of Roane County.
Figure 1. ATSDR's Main Conclusion and Supporting Lines of Evidence
Although the previous statements clearly support ATSDR's main conclusion for this site, it has become apparent to ATSDR that some community members have long-standing health concerns about the incinerator's ongoing operations, despite evidence suggesting that the site does not cause unhealthful exposures. To bridge this information gap, ATSDR recommends that TDEC annually issue fact sheets to brief residents on the incinerator's ongoing operations. These fact sheets should address inspection outcomes, regulatory compliance, agency oversight, and quantitative comparison of environmental sampling results collected by various parties.
When preparing this PHA, ATSDR identified regional air quality issues of potential health concern; namely, air quality across the Knoxville metropolitan area is occasionally poor when airborne levels of ozone and fine particles reach unhealthful levels. These air quality issues are regional in nature and result from industrial and motor vehicle emissions over a broad geographic area — emissions from the TSCA Incinerator appear to contribute little to these problems. When exposed to elevated levels of these pollutants, some people — particularly children, the elderly, and those with respiratory conditions — could experience lung irritation, difficulty breathing, and other health effects. On days with poor air quality, TDEC issues warnings that explain how people can reduce their exposure and how they can avoid adverse health effects. It is especially important for residents to heed these warnings and for adults to convey these warnings to their children, particularly asthmatic children.
The remainder of this PHA describes how ATSDR reached the conclusions and summary statements listed above. Those interested in only a brief summary of the main conclusions and recommendations should proceed to Sections VIII through X of this PHA. Those interested in a detailed account of ATSDR's scientific analyses are encouraged to read the entire report. Appendixes E and F of this PHA present a glossary and definitions of units of measurement used throughout this report.
Since 1942, the U.S. government and contractors have conducted various research and development activities at the Oak Ridge Reservation (ORR), located in Anderson and Roane Counties in Tennessee. These activities were primarily conducted at four separate facilities previously known as the Y-12 plant, the K-25 site, the S-50 site, and the X-10 site. For much of ORR's history, the research and development activities focused on designing and producing materials and components for nuclear weapons. In recent years, however, the ORR facilities' missions have changed considerably. While some ORR facilities continue to conduct nuclear research and production projects vital to national security, other ORR facilities devote considerable resources to environmental research and restoration.
The U.S. Department of Energy's (DOE's) environmental restoration activities address contamination that remains from past research, development, and production operations. A challenge faced by DOE has been how to handle "mixed wastes," or wastes that contain both chemical and radioactive contamination.
What is "mixed low-level radioactive and hazardous waste?" Waste management regulations define what materials should be considered "hazardous waste" and what materials should be considered "radioactive waste." Some wastes, however, meet the criteria set forth in both definitions. Such materials are considered "mixed low-level radioactive and hazardous waste," which is commonly referred to as mixed LLW. Depending on the source of the waste, mixed LLW can be liquid or solid. The TSCA Incinerator treats mixed LLW.
One way DOE and its contractors have addressed the challenge of mixed LLW is to design and operate an incinerator that treats and reduces the volume of waste materials. The incinerator is located at East Tennessee Technology Park (ETTP), formerly the K-25 site (see Figure 2). The incinerator is commonly known as the "TSCA Incinerator" because this operation is authorized under the Toxic Substances Control Act (TSCA) to treat wastes containing polychlorinated biphenyls (PCBs). The incinerator is also permitted under the Resource Conservation and Recovery Act (RCRA) to treat hazardous wastes. Construction of the incinerator was completed in 1989, and the incinerator began routinely treating wastes from ORR and other DOE facilities in 1991. The TSCA Incinerator continues to operate today.
This public health assessment (PHA) evaluates the public health implications of environmental releases from the TSCA Incinerator, including air emissions, solid wastes, and discharges to surface water. This PHA focuses almost entirely on environmental health concerns; that is, whether local residents living in communities near ETTP have contacted contamination at levels that might cause health problems. ATSDR is aware that some residents also have concerns about past and ongoing occupational exposures to contaminants at ORR. However, ATSDR's mandate does not include evaluating most occupational exposure scenarios. Those who are interested in learning more about occupational health issues for this site should refer to resources listed in Section V of this PHA.
This PHA presents the most extensive environmental health review to date of the TSCA Incinerator. ATSDR gathered and critically reviewed data and reports published by many parties, including environmental and health agencies, a local citizens' oversight committee, DOE and its contractors, and a group of independent experts chartered by the Governor of Tennessee. The PHA examines emissions monitoring data, environmental sampling data, and other observations that were collected over the entire history of the TSCA Incinerator's operations.
ATSDR's approach to evaluating the TSCA Incinerator started with collecting background information on topics such as operational history, community health concerns, environmental setting, and demographics. This section summarizes background information by presenting facts and observations about the TSCA Incinerator without any analyses or interpretations. Later sections in this report (Sections III through VII) describe how the background information fits into the overall environmental health analysis.
II.A. Site and Process Description
As Figure 2 shows, the TSCA Incinerator is located in the northeast corner of ETTP, which was formerly known as both the K-25 site and the Oak Ridge Gaseous Diffusion Plant. ETTP spans approximately 700 acres to which the public has no access, unless accompanied by an escort from the facility (see Section II.D). DOE constructed the TSCA Incinerator to help manage a growing volume of mixed LLW generated from various processes at ORR and at other DOE facilities. The purpose of the incinerator is to reduce the amount of waste that requires management, both by destroying hazardous organic chemicals in wastes and by reducing the volume of wastes containing radionuclides. The remainder of this section provides background information on incineration technology (see Section II.A.1) and describes the unit operations in the TSCA Incinerator (see Section II.A.2).
II.A.1. General Information on Incineration
Incinerators burn waste, thereby destroying some waste materials and reducing the volume of others. Although many different incineration technologies exist, nearly all incineration facilities share some common input and output streams, as Figure 3 depicts. The primary inputs at most incineration facilities are the wastes to be treated, along with air and additional fuel to support combustion. Incineration occurs within combustion chambers, which destroys most organic material in waste, but in the process generates two general types of output streams:
Figure 2. Location of the TSCA Incinerator
Figure 3. Generic Process Streams at Most Incineration Facilities
Those interested in more detailed information on incineration are referred to various documents published by government agencies on environmental health concerns related to thermal treatment technologies (e.g., ATSDR 2002; EPA 1998; NRC 2000).
"Thermal treatment technologies [including incinerators] are inherently neither safe nor unsafe; whether they are safe depends on how they are designed and operated" (ATSDR 2002). |
ATSDR is aware that many parties continue to debate whether incineration is a viable method of waste management. This PHA is not designed to enter this debate. Rather, its purpose is to evaluate the environmental health concerns specific to the TSCA Incinerator at ETTP. It is worth noting, however, that ATSDR has already conducted an extensive public health review of incineration and thermal treatment technologies (ATSDR 2002). That review found that the design and operation of an incinerator (see text box) must be considered when evaluating a particular site. Accordingly, this PHA not only reviews environmental sampling data collected near ETTP, but also considers specific information on how DOE designed and operates the TSCA Incinerator.
II.A.2. Process Description of the TSCA Incinerator
This section describes key elements of the engineering processes at the TSCA Incinerator, focusing on how the engineering design relates to potential air emissions and how waste material passes through the facility. This section provides an overview of the incinerator design, without necessarily identifying and commenting on the countless individual components (e.g., buildings, trailers, tanks, piping, connections) installed at the incinerator. Readers interested in a more detailed account of the engineering design should refer to DOE's permit application for the TSCA Incinerator, which includes highly detailed information about the incinerator design and operation (Radian 1997).
All equipment at the TSCA Incinerator can be classified into five general categories, as shown in Figure 4, on the following page. The following paragraphs describe the role each category of equipment plays and identify the main air emissions sources from the facility:
The composition of the wastes treated at the TSCA Incinerator can vary considerably throughout the year. Composition data comes largely from analytical data for the incoming wastes. For every year the TSCA Incinerator has operated, DOE has reported "rolling totals" that document the total amount of various chemical and radiological constituents in the waste (DOE 2003a). ATSDR thoroughly reviewed these records when preparing this PHA. As an example of the constituents, the 2003 "rolling totals" data include waste throughput estimates for approximately 200 organic chemicals, more than 25 metals, and more than 25 radionuclides. It should be noted that many of the constituents were tested for in the incoming waste, but never detected.
Solid wastes arrive at the TSCA Incinerator in enclosed containers, such that dusts or particles cannot blow from the waste material into the environment. Solid waste materials are repackaged into combustible containers, which are kept in storage areas before they are fed to the incinerator. The repackaging occurs over a ventilated table, further reducing the possibility of untreated wastes becoming airborne; exhaust air from repackaging areas passes through filters before being vented to the atmosphere. Examples of the types of solid wastes processed at the TSCA Incinerator include pallets, spent carbon, used wash rags, filters, trash, and spent personal protective equipment.
Liquid wastes are stored at the TSCA Incinerator primarily in tanks. While these tanks do have passive vents to the atmosphere, all vapors released from tanks first pass through carbon adsorption filters that capture volatile chemicals which might otherwise enter the air. The liquid wastes are piped directly into the incinerator, either to the rotary kiln or to the afterburner (see below for more information on these operations). With this design, evaporative losses and other fugitive emissions of untreated liquid wastes are expected to be minimal. The TSCA Incinerator is permitted to treat both aqueous waste (e.g., wastewater) and organic waste (e.g., oils, solvent mixtures, degreaser fluids).
First, all solid waste (along with some liquid waste) is fed into the primary combustion chamber, which is a rotary kiln. The kiln is cylindrical in shape, 6 feet in diameter, and 25 feet long. The inside temperature varies with the type of waste treated, but is generally at least 1,580 degrees Fahrenheit. Incineration of waste in the kiln generates gases which pass into the secondary combustion chamber (see next paragraph) for further treatment. Incombustible material in the waste leaves the rotary kiln in the form of ash. At the end of the kiln, the ash drops into a water pool and enters the residuals management part of the process, as described further below.
The secondary combustion chamber at the TSCA Incinerator is an afterburner, which serves two general purposes. First, some liquid waste is sprayed directly into the afterburner for purposes of treatment. Second, the afterburner destroys organic material in the gases generated in the rotary kiln. The temperature in the afterburner is typically at least 2,205 degrees Fahrenheit, and gases are exposed to this temperature for at least 4 seconds. With one exception, the treated air stream from the afterburner always passes directly into air pollution controls (see below). As the exception, a thermal relief vent (TRV) on the afterburner opens on infrequent occasions to avoid dangerous buildup of gases and to prevent situations that might harm the downstream air pollution controls. When the TRV opens, the waste feed to the incinerator is instantly cut off, and gases in the afterburner bypass air pollution controls and vent directly to the atmosphere. In the first 14 years that the TSCA Incinerator operated (1991 to 2004), the TRV opened 18 times. Sections III.B.2 and III.D.2 comment further on the significance of the TRV openings.
The fate of waste constituents within the incinerator varies. For instance, organic chemicals are very efficiently destroyed in the incinerator (see Section II.C for quantitative information on the destruction efficiency). Incineration of organic chemicals primarily generates a mixture of low molecular weight by-products (e.g., water, oxygen, carbon dioxide) that are relatively harmless from a health perspective. However, some potentially harmful by-products do form, such as inorganic acids, dioxins, and furans. Metals and radionuclides in the waste feed are not destroyed in the combustion chambers. Thus, the effluent from the combustion chambers contain a mixture of vapors products and particles that pass through a series of air pollution controls (see below) before being vented to the atmosphere.
As Figure 4 indicates, the main air emissions points from the TSCA Incinerator are (1) routine releases through the main process stack and (2) infrequent non-routine releases through the thermal relief vent. Section III of this PHA evaluates the public health implications of both types of releases. |
The gases generated in the TSCA Incinerator's afterburner pass through multiple air pollution control devices designed to remove contaminants (primarily particle-bound contaminants and acidic gases) from the effluent stream. The sequence of air pollution controls — a quench chamber, a Venturi scrubber, a packed bed scrubber, and two ionizing wet scrubbers — efficiently removes numerous contaminants, including very fine particles, that would otherwise escape to the air. The contaminants that are removed (e.g., metals, acids, radionuclides) are primarily captured in water that circulates through the air pollution controls. The next bullet item further discusses how the contaminants are handled in the wastewater streams. After passing through these multiple air pollution controls, the process gases are vented to the atmosphere through a 100-foot tall stack.
Specifically, the wet ash from the water pool at the end of the rotary kiln is transferred via conveyor belt to 55-gallon drums. (Keeping the ash wet minimizes the possibility of wind blowing contaminants into the atmosphere.) Ash samples from the drums are analyzed to determine whether the waste should be disposed of in a landfill or subjected to further treatment. When PCB-containing wastes are being burned, all ash found to contain more than 2 parts per million (ppm) PCBs must pass through the incinerator a second time for further treatment.
The liquid residuals from the air pollution control devices are collected in a sump, which generates both solid waste (sludge) and liquid waste (wastewater). Radionuclides, metals, and other low-solubility substances removed by the air pollution controls will largely collect in the incinerator's sludge. DOE handles this sludge, similar to the ash, according to applicable solid waste management regulations. The wastewater, on the other hand, is either recycled to the air pollution control devices or pumped to the Central Neutralization Facility (CNF) — the main wastewater treatment plant at ETTP. The treated water is discharged to the Clinch River. DOE's National Pollutant Discharge Elimination System (NPDES) permit requires frequent sampling of the treated water to demonstrate that the effluent will not harm human health or the environment. Refer to Section V of this PHA for ATSDR's evaluation of the environmental health issues associated with the incinerator's residuals.
Figure 4. Block Diagram of the TSCA Incinerator
The previous discussion highlights general design features of the TSCA Incinerator that are most relevant to environmental releases and to ATSDR's evaluations presented in this PHA. Generally speaking, the incinerator is designed to ensure that organic material in the wastes is efficiently destroyed, with no hazardous residuals generated.
II.B. TSCA Incinerator Operational History
The TSCA Incinerator treats waste material consistently — but not continuously — throughout the year. DOE waste treatment records suggest that the incinerator typically operates up to 250 days per year. Downtime occurs due to various reasons, such as routine or non-routine maintenance.
ATSDR gathered three general types of information to characterize key features of the TSCA Incinerator's operational history:
Three important observations are evident from the table. First, unlike other emissions sources at ORR that ATSDR has evaluated to date, the TSCA Incinerator has only operated for the past 14 years. Therefore, as Section III explains, this PHA focuses only on potential exposures that have occurred since 1991. Second, the table indicates that DOE performed numerous emissions tests and trial burns before regulatory agencies would permit routine operations. This means that DOE had to characterize thoroughly the incinerator's performance before operations could commence. Third, the table notes that DOE performed several updates to its emissions tests and trial burns. Regulatory agencies required DOE to demonstrate, through these additional tests, that the incinerator continues to meet health-protective requirements specified in environmental permits. Taken together, these observations give some sense of the regulatory oversight of the incinerator's operations, an issue that Section II.C discusses further.
Table 1. Selected Milestones in the TSCA Incinerator's Operational History
Date |
Milestone |
|---|---|
1984 |
Construction of TSCA Incinerator begun |
May 1988 |
Final TSCA trial burn prior to permitting |
June 1989 |
Final RCRA trial burn prior to permitting |
June 1990 |
Final state emissions test prior to permitting |
April 1991 |
Start of routine waste treatment operations at the TSCA Incinerator |
June 1995 |
Updated state emissions test |
November 2000 |
Updated state emissions test |
May 2001 |
Updated RCRA/TSCA trial burn |
The amount of waste that the TSCA Incinerator treats is only a small fraction of the amount allowed under the facility's health-protective permits. |
Figure 5 shows how the annual amount of wastes treated at the TSCA Incinerator has varied from year to year. Waste treatment activity at the incinerator peaked in the mid-1990s and has decreased considerably since then. Not shown in Figure 5 is the fact that the TSCA Incinerator treats only a small fraction of the waste allowed in its environmental permits. Specifically, the current operating permits allow the TSCA Incinerator to treat no more than 1,836 pounds of liquid waste per hour and 964 pounds of solid waste per hour. Given these limits and assuming 10% downtime for routine maintenance, the TSCA Incinerator is currently permitted to treat approximately 10,000 tons of waste per year. Since 2000, however, the amount of waste treated at the TSCA Incinerator has been only 5% of the health-protective permitted limits.
Thus, in recent years, the TSCA incinerator has clearly been operating at levels much lower than the overall capacity expressed in terms of total liquid waste feed per hour or total solid waste feed per hour. However, it should be noted that there are many permit conditions for specific contaminants and parameters in the feed that could potentially cause the allowable waste feed rate to be lower than the maximum limits based on liquid and solid mass throughput.
As Table 2 shows, during the first 14 years of the TSCA Incinerator's operations, the TRV opened 18 times. The most frequent cause of the TRV openings was interruptions to the electrical power system. To minimize the likelihood of power losses shutting down operations, the incinerator is equipped with two separate feeders from the electric switchyard. But power outages have still caused 10 shutdowns (and TRV openings) over a 14-year period. The second most frequent cause was failures in the magnetic latch that keeps the TRV closed. After the last such failure (in July 1996), engineers at the facility designed and installed a new TRV closure mechanism that has addressed this problem (Iglar et al. 1998). The frequency of TRV openings has varied from year to year, with no TRV openings in some years and as many as five TRV openings in others.
To ensure that air releases during TRV openings do not reach unsafe levels, immediately after gases are vented to the air DOE collects air samples at two off-site locations. If waste feed and operating conditions at the time of the TRV opening are not bracketed by those observed during previous events, the samples are analyzed. Table 2 notes that air samples were analyzed for nine out of the 18 TRV openings that occurred between 1991 and 2004. Section III.D of this PHA reviews the results of samples collected during these episodic releases.
Figure 5. History of Waste Treatment Totals, by Calendar Year
Source of data: DOE 2003a.
Table 2. History of TRV Openings (1991–2004)
Date |
Cause |
Ambient Air Sample Analyzed? |
|---|---|---|
December 20, 1991 |
Electrical power interruption |
Yes |
May 5, 1993 |
Electrical power interruption |
Yes |
May 6, 1993 |
False radiation criticality alarm |
Yes |
February 25, 1995 |
Electrical power interruption |
Yes |
May 31, 1995 |
Electrical power interruption |
Yes |
June 18, 1995 |
Electrical power interruption |
Yes |
December 9, 1995 |
Loss of TRV magnet |
No |
December 22, 1995 |
Loss of programmable logic controller |
No |
January 28, 1996 |
Loss of TRV magnet |
Yes |
January 31, 1996 |
Loss of TRV magnet |
Yes |
April 30, 1996 |
Loss of programmable logic controller |
No |
July 7, 1996 |
Loss of TRV magnet |
Yes |
July 12, 1999 |
Electrical power interruption |
No |
December 29, 1999 |
Loss of programmable logic controller |
No |
June 29, 2002 |
Electrical power interruption |
No |
July 22, 2002 |
Electrical power interruption |
No |
February 27, 2004 |
Electrical power interruption |
No |
May 13, 2004 |
Electrical power interruption |
No |
Source of data: DOE 2003b.
The preceding discussion reviews key observations pertaining to the TSCA Incinerator's operational history. Still, as the next section of this PHA further describes, the facility's environmental permits largely dictate how DOE routinely operates the incinerator.
II.C. Remedial and Regulatory History
DOE could not begin waste treatment operations at the TSCA Incinerator until environmental regulatory agencies, primarily EPA and TDEC, issued the necessary permits. The permitting process for such a facility is quite extensive, as is demonstrated by the fact that more than 2 years passed between the time the TSCA Incinerator was constructed and when permitted operations began. Operations at the TSCA Incinerator must comply with multiple federal regulations (e.g., the Clean Water Act, the Clean Air Act, TSCA, and the Resource Conservation and Recovery Act, or RCRA) and supplemental regulations issued by the state of Tennessee. Further, many activities for operations involving radioactivity must meet standards established by DOE. Although the many permits governing the incinerator's operations address different issues, the environmental permits share one common feature: they are intended to prevent situations in which releases from the TSCA Incinerator can harm human health or the environment.
The remainder of this section reviews notable features of the environmental permits that pertain to environmental releases from the TSCA Incinerator:
What is the waste destruction and removal efficiency (DRE)? The overwhelming majority of waste material fed to an incinerator is not released to the air. Rather, organic chemicals are destroyed in the combustion chambers; metals and radionuclides are largely removed from process streams by air pollution controls and eventually accumulate in solid residuals, whether the ash at the end of the rotary kiln or the sludge from the water used in the air pollution controls.
The destruction and removal efficiency refers to the percent of waste material that is either destroyed or otherwise removed from the waste feed. For most hazardous waste incinerators, DREs for organic compounds are greater than 99.99% and well over 90% for many metals and radionuclides. The DRE for a given chemical is calculated using the following equation:
DRE = (Feed Rate – Emission Rate) / (Feed Rate)
The feed rate is the measured amount of chemical in the wastes fed to the incinerator and the emission rate is the measured amount of chemical in the stack exhaust.
Recognizing that operating parameters are closely linked to incinerator performance, environmental regulatory agencies require thermal treatment facilities to determine, typically through trial burns, the ranges of operating parameters needed to achieve the required destruction removal efficiencies (DREs). For the TSCA Incinerator, DOE had to demonstrate that the incineration process could achieve DREs greater than 99.9999% for PCBs and greater than 99.99% for other organic chemicals expected to be found in hazardous waste. To date, DOE has conducted multiple trial burns at the TSCA Incinerator, all of which have challenged the incinerator to destroy wastes under unfavorable conditions, such as lower combustion temperatures and higher feed rates.
The trial burns conducted at the TSCA Incinerator served two critical purposes. First, they proved that the incinerator could meet the numerous and extensive requirements set forth in environmental regulations, such as minimum DREs and maximum emission rates for certain pollutants. (Appendix A presents detailed summaries of the trial burns conducted at the TSCA Incinerator.) Second, they provided information that regulators could use to establish limits on critical operating parameters. Table 3, for instance, lists several critical operating parameters that DOE must continuously monitor to ensure that the TSCA Incinerator operates in a manner consistent with conditions observed during the trial burns. Whenever operating parameters deviate from the limits shown in Table 3, an automatic waste feed cutoff occurs: the waste feed automatically shuts down, wastes remaining within the incinerator are fully treated, and no further waste is treated until the operating parameters return to acceptable values. Through this continuous monitoring and automatic waste feed cutoff process, regulators help ensure that the TSCA Incinerator only operates in a manner that has been shown to achieve the required waste-destruction efficiencies.
Table 3. Limits Established in Permits for Selected Operating Parameters
Parameter |
Permit Limit |
Rationale |
Monitoring Status |
|---|---|---|---|
Outlet temperature of rotary kiln |
> 1,580 °F |
Lower temperatures could lead to more products of incomplete combustion and failure to meet required waste destruction efficiencies for organic wastes. |
DOE must monitor all of the parameters listed in this table continuously. Outputs from the monitors are fed directly to the control room. Values found outside of permitted limits will trigger automatic waste feed cutoffs. DOE must frequently test and calibrate the sensors that measure the listed parameters. |
Outlet temperature of afterburner |
> 2,205 °F |
||
Gas residence time in the afterburner |
> 2 seconds |
The afterburner will not destroy organic compounds that move through the system too rapidly. |
|
Stack exit velocity |
< 21.4 feet/second |
||
TRV opening |
Must be closed |
Operating with the TRV open would release exhaust gases to the air without first sending them through air pollution controls. |
|
Concentrations of carbon monoxide in the stack exhaust |
<100 ppm (1-hour rolling average) |
Higher carbon monoxide levels are an indicator of incomplete combustion or organic material. |
|
Solid waste feed rate to kiln |
<1,008 lb/hour |
The trial burns demonstrated that the incinerator can efficiently destroy wastes at these feed rates. Destruction efficiencies at higher feed rates have not been verified. |
|
Organic liquid waste feed rate to kiln |
<812 lb/hour |
||
Aqueous liquid waste feed rate to kiln |
<478 lb/hour |
||
Organic liquid waste feed rate to afterburner |
<710 lb/hour |
||
Water recycle flow through venturi scrubber |
<121 gallons/minute |
Values outside these ranges would indicate that the air pollution controls might not be treating the exhaust streams efficiently. |
|
Effluent pH in the packed bed scrubber |
<6.1 (with 30-minute delay) |
Notes:
Source of data: Radian 1997.
The temperature and residence time requirements only apply to TSCA conditions (i.e., incinerating wastes containing PCBs). The RCRA requirements for these parameters are less stringent.
The table lists only a subset of the operating parameters specified in the various environmental permits.
Overall, the purpose of the previous discussion is to emphasize that the TSCA Incinerator is a closely regulated air emissions source. Due to the extensive environmental regulations and permitting requirements, DOE invested considerable effort to obtain its original permits and, to comply with those permits, closely monitors the incinerator's performance.
The environmental setting for a site largely determines how close residents can come to sources of contamination and how contaminants move through the environment. Accordingly, when evaluating environmental health issues for the TSCA Incinerator, ATSDR considered the following observations:
The prevailing wind patterns in the Oak Ridge area tend to be along the valley floor directions. To illustrate this, Figure 6 summarizes hourly wind speed and wind direction measurements in a format known as a wind rose. The wind rose displays the statistical distribution of wind speeds and wind directions recently observed at a meteorological station located at ETTP. As Figure 6 depicts, the prevailing wind patterns near the TSCA Incinerator are from the general southwest direction (i.e., west-southwest, southwest, south-southwest) toward the northeast and, to a lesser extent, from the general northeast direction toward the southwest. These directions correspond to up-valley and down-valley flows — directions consistent with local terrain features. Despite the dominance of winds along the valley axis, Figure 6 indicates that winds occasionally blow in other directions. As Section III.D further discusses, when reviewing the ambient air monitoring data and ambient air sampling data for this site, ATSDR focused on exposures that might occur to residents located in the prevailing wind directions, with the understanding that residents who do not live in the prevailing wind directions would experience lower exposures.
The previous discussion is intended to identify aspects of the environmental setting that are most relevant to releases from the TSCA Incinerator. Those interested in further information on the environmental setting are referred to other resources (e.g., DOE 1991–2002).
Figure 6. Typical Wind Rose for the ETTP Area
Notes:
This wind rose was generated from meteorological data collected in 1999 at a weather station at ETTP. Wind measurements were made at 10 meters above ground surface. Wind roses for other years display nearly identical prevailing wind patterns.
Bars in the figure indicate the direction from which wind was blowing. The shading and thickness of the bars indicate the wind speeds observed for each wind direction. Specifically, the circular grid lines represent the percent of time that the wind blows in a particular direction, and the wind direction for a given bar is from the end of the bar towards the center of the wind rose.
II.E. Local Emissions Sources and Regional Air Quality
Although this PHA focuses on environmental health concerns specific to the TSCA Incinerator, ATSDR identified some general air quality issues for the Knoxville metropolitan area that need to be reviewed to better appreciate the significance of the incinerator's releases. The remainder of this section provides perspective on these related issues, which include other air emissions sources near ETTP (Section II.E.1) and regional air quality concerns (Section II.E.2).
II.E.1. Other Air Emissions Sources
When evaluating the air exposure pathway, ATSDR typically considers not only emissions from the source of concern (in this case, the TSCA Incinerator) but also emissions from other sources in the area. ATSDR takes this approach because community members ultimately are exposed to air contaminants released from all local sources, not just contaminants released from a single source. Accordingly, this section presents information ATSDR gathered on two types of emissions sources near ETTP.
According to the most recent data available to ATSDR when preparing this PHA, for calendar year 2001 six industrial facilities located within 10 miles of the TSCA Incinerator submitted air emissions data to TRI. Table 4 summarizes the air emissions data that the facilities reported, and Figure 7 shows the locations of these facilities. Two observations can be made from the table: first, the TSCA Incinerator is somewhat isolated from large industrial air emissions sources, as the closest facility that disclosed any air emissions to TRI is 4 miles from ETTP. Second, the TSCA Incinerator accounts for an extremely small fraction (<0.02%) of the total toxic chemicals reported to TRI by other industrial facilities located within 10 miles. Readers should refer to Section V.B of this PHA for further insight on the inferences that should be drawn from the TRI data.
ATSDR is aware that community members have expressed concerns about other air emissions sources more than 10 miles from the TSCA Incinerator. For instance, community members have asked about the significance of TVA's Bull Run Steam Plant, which is located northeast of ORR, about 13 miles from the TSCA Incinerator. In Section V.B of this PHA, ATSDR provides some context on that facility's emissions.
Table 4. Air Toxics Emissions Data from EPA's 2001 Toxic Release Inventory (TRI) for Industrial Facilities within Approximately 10 Miles of ETTP
Facility Name |
Approximate Distance from ETTP (See Figure 7) |
Total Air Emissions of Toxic Contaminants Disclosed to TRI in Reporting Year 2001 |
|---|---|---|
U.S. DOE East Tennessee Technology Park |
0 miles |
Hydrochloric acid = 25 lbs. |
Lead = 58 lbs. |
||
U.S. DOE Oak Ridge Natl. Lab. |
4 miles |
Lead = 1 lbs. |
Diversified Scientific Services, Inc. (DSSI) |
5 miles |
Acetonitrile = 14 lbs. |
Methylene chloride = 11 lbs. |
||
Methanol = 22 lbs. |
||
n-Hexane = 15 lbs. |
||
Toluene = 20 lbs. |
||
Xylenes = 21 lbs. |
||
U.S. TVA Kingston Fossil Plant |
8 miles |
1,2,4-Trimethylbenzene = 500 lbs. |
Arsenic compounds = 1,505 lbs. |
||
Barium compounds = 1,250 lbs. |
||
Chromium compounds = 755 lbs. |
||
Cobalt compounds = 255 lbs. |
||
Copper compounds = 755 lbs. |
||
Hydrochloric acid = 4,000,005 lbs. |
||
Hydrogen fluoride = 510,005 lbs. |
||
Lead compounds = 242 lbs. |
||
Manganese compounds = 1,000 lbs. |
||
Mercury compounds = 450 lbs. |
||
n-Hexane = 500 lbs. |
||
Nickel compounds = 255 lbs. |
||
Polycyclic aromatic cmpds. = 27 lbs. |
||
Selenium compounds = 7,705 lbs. |
||
Sulfuric acid = 1,400,005 lbs. |
||
Vanadium compounds = 755 lbs. |
||
Zinc compounds = 255 lbs. |
||
U.S. DOE Oak Ridge Y-12 National Security Complex |
8 miles |
Freon 113 = 16,530 lbs. |
Hydrochloric acid = 102,332 lbs. |
||
Lead compounds = 4 lbs. |
||
Mercury compounds = 2 lbs. |
||
Methanol = 21,417 lbs. |
||
Nitric acid = 2,601 lbs. |
||
Sulfuric acid = 44,221 lbs |
||
Boeing Oak Ridge Co. |
10 miles |
Nitric acid = 143 lbs. |
Notes:
Source of data: EPA 2004a.
Air emissions for ETTP should include amounts of chemicals released from the TSCA Incinerator that are subject to the TRI reporting requirements. The 2001 TRI data for ETTP include forms for PCBs and hexachlorobenzene. However, both forms reported zero air emissions and are therefore not included in the table above.
Data are presented for calendar year 2001. These were the most recent TRI data available when this PHA was first drafted.
The TRI regulations require facilities in certain industries to disclose the amounts of specific toxic chemicals that are released to the environment or managed as waste. However, the regulations do not require that all facilities report, and they do not apply to all toxic chemicals. As a result, this table should not be viewed as a comprehensive inventory of industrial air emissions for the Oak Ridge area. Further, the data in this table likely do not represent all toxic air emissions for the facilities listed. TRI data are self-reported; the accuracy of the release data and the geographic coordinates for individual facilities is not known.
Notes:
Source of data: EPA 2004.
Only facilities that reported air releases to TRI were considered for this figure.
The TRI regulations require facilities in certain industries to disclose the amount of specific toxic chemicals they release to the environment or manage as waste. Still, the regulations do not require that all facilities report, and do not address all contaminants; this is presumably why this figure does not identify every industrial facility in the Oak Ridge area. Therefore, this figure does not present a comprehensive account of industrial air emissions sources near ETTP. TRI data are self-reported; the accuracy of the release data and the geographic coordinates for individual facilities is not known.
Overall, the previous discussion reveals that the TSCA Incinerator not only is a relatively isolated source of air emissions, but also appears to account for a small fraction of the total air emissions throughout Roane County and the Oak Ridge area. Consequently, the levels of air pollution measured in the area generally cannot be assumed to result entirely from the TSCA Incinerator. Nevertheless, this PHA thoroughly evaluates the public health implications of all emissions and ambient air sampling data collected for this site, including contaminants (e.g., radionuclides) not typically reported in TRI, NEI, and other emission inventories.
II.E.2. General Air Quality in the Knoxville Metropolitan Area
For more than 20 years, EPA and state environmental agencies have evaluated general air quality concerns by measuring ambient air concentrations of six common air pollutants, also known as criteria pollutants. The criteria pollutants are
Many different air emissions sources contribute to the airborne levels of these pollutants. For every criteria pollutant EPA has established a health-based National Ambient Air Quality Standard (NAAQS). In cases where air quality does not meet an NAAQS, states are required to develop and implement plans to bring air pollution levels into attainment with the health-based standards. The following paragraphs review the general air quality in the Knoxville metropolitan area:1
Table 5. EPA's 1999 National Emissions Inventory (NEI) Data for Roane County
Source Category |
Emissions Data for Selected Pollutants |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Carbon Monoxide |
Nitrogen Oxides |
PM10 |
Sulfur Dioxide |
VOCs |
||||||
Tons per Year |
% of Total |
Tons per Year |
% of Total |
Tons per Year |
% of Total |
Tons per Year |
% of Total |
Tons per Year |
% of Total |
|
ETTP (includes TSCA Incinerator) |
5 |
<0.1% |
30 |
0.1% |
5 |
<0.1% |
1 |
<0.1% |
7 |
0.2% |
Other major industrial sources |
1,357 |
5.1% |
26,782 |
86.8% |
5,529 |
73.0% |
110,795 |
99.6% |
267 |
6.1% |
Mobile sources |
23,879 |
88.9% |
3,898 |
12.6% |
156 |
2.1% |
221 |
0.2% |
2,350 |
53.6% |
All other sources |
1,611 |
6.0% |
153 |
0.5% |
1,883 |
24.9% |
169 |
0.2% |
1,764 |
40.1% |
Totals for Roane County |
26,852 |
100% |
30,863 |
100% |
7,573 |
100% |
111,186 |
100% |
4,388 |
100% |
Notes:
Source of data: EPA 2004b.
EPA updates its NEI data every 3 years. Results for 1999 are shown, as that is the most recent year for which final NEI data are available.
Air emissions for ETTP should include releases from the TSCA Incinerator.
The PM10 emissions data shown here include the sum of filterable and condensable particulate matter smaller than 10 microns.
"Other major industrial sources" is the sum of releases EPA has reported for the "major" air emissions sources in Roane County. A "major" source emits a threshold amount (or more) of at least one criteria pollutant; thus, this category includes the largest industrial emissions sources in the county. These include Oak Ridge National Laboratory, U.S. TVA Kingston Fossil Plant, Clinch River Corporation, Horsehead Resource Development Company, and Fortafil Fibers, Inc.
"Mobile sources" include a wide range of on-road and off-road mobile sources that burn gasoline, diesel fuel, and other types of fuels. These emissions sources include automobiles, trucks, and various commercial, industrial, recreational, and agricultural vehicles.
"All other sources" include industrial sources that are not categorized as major sources, residential emissions sources (e.g., fireplaces, wood-burning stoves, trash burning), and miscellaneous other sources (e.g., wind-blown dust, forest fires, structural fires).
What is ozone? Ozone forms in air when emissions from numerous sources, including motor vehicles and industry, mix together and react with sunlight. Ozone levels are typically highest during the afternoon hours of the summer months, when the influence of direct sunlight is greatest. When airborne ozone levels are high enough, people may experience respiratory health problems. |
The ozone air quality issue in the Knoxville metropolitan area is not unique. In fact, nearly every major metropolitan area along the East Coast has unhealthy ozone levels occasionally during the summer months. Moreover, more than 150 million residents nationwide live in ozone non-attainment areas. It is also important to note that the ozone problems in the Knoxville area are complex and result from industrial and motor vehicle emissions over a broad geographic region. Sources that release nitrogen oxides and VOCs (both known as ozone precursors) contribute significantly to ozone formation. As Table 5 shows, the TSCA Incinerator releases relatively small amounts of these precursors, especially when compared to other sources in Roane County and beyond. In short, the Knoxville area's ozone air quality issue is regional in nature and is largely unrelated to air emissions from the TSCA Incinerator. Consequently, this PHA addresses ozone issues in response to community concerns about general air quality (see Section V), and not as a site-specific issue.
What is particulate matter (PM)? PM is airborne particles and droplets of varying sizes and chemical composition. Many different industrial, mobile, natural, agricultural, and other sources release PM directly to the air or release pollutants that form PM while in the air. Environmental regulations have addressed total suspended particulates (TSP), particulate matter smaller than 10 microns (PM10), and particulate matter smaller than 2.5 microns (PM2.5). Section III.D comments further on the different size fractions of PM. |
Like the area's ozone problems, the PM2.5 issues in the Knoxville metropolitan area are not unique. According to EPA's most recent estimates, approximately 99 million U.S. residents — mostly in urban areas in the Midwest, northeast, and along the Appalachian Mountains — live in PM2.5 "non-attainment areas." In many cases, the PM2.5 problems cannot be attributed to a single source; PM2.5 forms in the air from many precursors that originate from multiple combustion and industrial sources over broad areas. That said, however, emission inventory data (e.g., Table 5) have shown that the TSCA Incinerator emits insignificant amounts of PM2.5 precursors, particularly when compared to other emissions sources in the Knoxville metropolitan area. Therefore, this PHA addresses the elevated PM2.5 levels in the Knoxville metropolitan area as a regional air quality issue (see Section V), not one resulting from the TSCA Incinerator's emissions.
Airborne levels of ozone and PM2.5 are sometimes unhealthy in the Knoxville metropolitan area. The air quality problems for both pollutants are regional issues—not directly the result of air emissions from the TSCA Incinerator. Section V of this PHA discusses the public health implications of living in areas where airborne ozone and PM2.5 levels are occasionally elevated.
ATSDR examines demographic data to determine the number of people who are potentially exposed to environmental contaminants and to consider the presence of sensitive populations, such as children (age 6 years and younger), women of childbearing age (between ages 15 and 44 years), and the elderly (age 65 years and older). This section considers general population trends for residents nearest to the TSCA Incinerator and also identifies the residential areas closest to the site.
In addition to the aforementioned residential neighborhoods, where prolonged or chronic exposures to site contaminants are feasible, ATSDR also considered short-term exposures residents might experience when they are closer to the TSCA Incinerator. The nearest publicly accessible area is Blair Road, which at its closest point passes about ¼ mile from the base of the TSCA Incinerator stack. Residents are not expected to spend extended periods of time outdoors on the parts of Blair Road nearest to the TSCA Incinerator, though such activity is not prohibited.
Later sections of this PHA refer to the demographic data. Specifically, Section IV evaluates public health implications of chronic exposure for residential populations, and Section V presents health-related information specific to children and the elderly, which are known to be sensitive to exposures to certain air pollutants.
II.G. Summary of Public Health Activities Pertaining to the TSCA Incinerator
For more than 12 years, ATSDR has been evaluating environmental health issues related to other facilities at ORR. The text box at the end of this section describes how residents can get more information on ATSDR's past and ongoing environmental health activities for those other facilities. A timeline for the main public health activities specific to the TSCA Incinerator follows:
Figure 8. Demographics within 3 Miles of the TSCA Incinerator
Where can one obtain more information on ATSDR's activities at Oak Ridge?
In addition to completing this PHA, ATSDR and other agencies have evaluated numerous other environmental health issues related to ORR facilities. Community members can find more information on ATSDR's past activities by:
Visiting one of the records repositories. Copies of ATSDR's publications for ORR, along with publications from other agencies, can be viewed in records repositories at the DOE Information Center, the Harriman Public Library, the Kinsgton Public Library, the Oak Ridge Public Library, the Roane State Community College, and the Rockwood Public Library.
Visiting the ORRHES or ATSDR Web sites. These Web sites have links to past publications, schedules of future events, and related informational materials. The ORRHES site is http://www.atsdr.cdc.gov/HAC/oakridge and the ATSDR site is http://www.atsdr.cdc.gov. The most comprehensive summary of past activities is available online at http://www.atsdr.cdc.gov/HAC/oakridge/phact/c_toc.html.
Contacting ATSDR directly. Residents can contact representatives from ATSDR directly by dialing the agency's toll-free number, 1-888-42ATSDR (or 1-888-422-8737).
II.H. Quality Assurance and Quality Control
To prepare this PHA, ATSDR reviewed and evaluated information provided in the documents listed in the References (see Section XII). The environmental data presented in this PHA are from reports produced by many parties, including DOE, EPA, TDEC, and TVA. The limitations of these data have been identified in the associated reports, and, where appropriate, they are restated in this document. After reviewing the studies conducted to date, ATSDR determined that the quality of environmental data available in the site-related documents for the TSCA Incinerator is adequate to support public health decisions. ATSDR has made specific recommendations to improve, or better characterize, the quality of certain environmental sampling efforts. Refer to Appendix C for ATSDR's specific conclusions regarding the quality of the ambient air monitoring and ambient air sampling studies.
ATSDR also used an extensive review process for quality control purposes. Earlier drafts of this PHA and draft findings were presented to numerous parties, including ATSDR scientists with extensive experience in incineration and radiation exposure assessment, DOE, EPA, TDEC, ORRHES, and the PHAWG. ATSDR hopes that this extensive review process has helped ensure that all information and scientific analyses presented in this PHA are scientifically sound and technically accurate.
Next Section Table of Contents
