United States EPA-905-R97-002a
Environmental Protection Agency May 1997
WASTE MANAGEMENT
Risk Assessment for the Waste Technologies Industries (WTI)
Hazardous Waste Incineration Facility (East Liverpool, Ohio)
VOLUME I: Executive Summary
U.S. Environmental Protection Agency - Region 5
Waste, Pesticides and Toxics Division
77 West Jackson Blvd.
Chicago, IL 60604
Prepared with the assistance of:
AT. Kearney, Inc. (Prime Contractor; Chicago, IL);
with Subcontract support from:
ENVIRON Corp. (Arlington, VA),
Midwest Research Institute (Kansas City, MO)
and EARTH TECH, Inc. (Concord, MA)
under EPA Contract No. 68-W4-0006
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VOLUME I
EXECUTIVE SUMMARY
CONTENTS
Page
I. INTRODUCTION AND SUMMARY OF RESULTS 1-1
A. Overview 1-1
B. Introduction and Overview of Results 12
1. Human Health Risk Assessment 1-2
a) Introduction 1-2
b) Overview of Results 1-4
2. Screening Ecological Risk Assessment (SERA) 1-5
a) Introduction 1-5
b) Overview of Results 1-7
3. Accident Analysis 1-9
a) Introduction 1-9
b) Overview of Results 1-12
C. Structure of the Report 1-13
II. FACILITY BACKGROUND II-1
A. Facility Setting II-1
B. Facility Description II-2
III. FACILITY EMISSIONS III-l
A. Overview " III-l
B. Incinerator Stack Emissions III-l
C. Fugitive Emissions 1II-4
D. Uncertainties III-5
1. Uncertainties in Stack Emissions Characterization III-6
2. Uncertainties in Fugitive Emissions Characterization III-6
IV. ATMOSPHERIC DISPERSION AND DEPOSITION MODELING
OF EMISSIONS IV-1
A. Overview IV-1
B. Modeling Input Data IV-2
1. Source Data IV-2
2. ISC-COMPDEP Modeling IV-2
3. Non-Steady-State Modeling Using CALPUFF and fNPUFF IV-4
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CONTENTS
(continued)
Page
4. Wind Tunnel Simulations IV-5
5. Fugitive Emission Sources IV-5
C. Results IV-6
D. Uncertainties IV-6
1. Uncertainties Associated with Limitations of the
Technical Formulations IV-6
2. Uncertainties Associated with Data Limitations IV-7
V. HUMAN HEALTH RISK ASSESSMENT V-l
A. Overview V-l
B. Selection of Chemicals for Evaluation in the Risk Assessment V-2
1. Incinerator Stack Emissions . V-2
2. Fugitive Emissions V-3
C. Toxicity Assessment V-4
D. Exposure Assessment V-5
1. Identification of Population Subgroups and Exposure Pathways V-5
2. Fate and Transport Modeling V-7
3. Calculation of Dose V-7
E. Risk Characterization V-10
1. Incinerator Stack Emissions V-10
2. Fugitive Emissions V-ll
F. Uncertainties Associated with the HHRA V-l2
VI. SCREENING ECOLOGICAL RISK ASSESSMENT . VI-1
A. Overview VI-1
B. Selection of ECOCs VI-2
1. Incinerator Stack Emissions VI-2
2. Fugitive Emissions VI-3
C. Characterization of Exposure VI-4
D. Selection of Indicator Species Vl-6
E. Characterization of Effects VI-7
F. Risk Characterization VI-7
G. Uncertainties VI-9
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CONTENTS
(continued)
Page
VII. ACCIDENT ANALYSIS VII-1
A. Overview VII-1
B. History of Accidents Reported at U.S. Commercial
Incineration Facilities VII-2
C. Scenarios Considered in the Accident Analysis VI1-3
D. Chemicals of Potential Concern VII-3
E. Estimation of Emission Rates and Heat Effects VII-5
1. Chemical Emission Rates VII-5
2. Heat Effects VII-6
F. Dispersion Modeling for Accident Scenarios VII-6
G. Evaluation of Severity of Consequence and Probability of Occurrence VII-7
H. Uncertainties VII-11
VIII. ADDITIONAL ANALYSIS IN RESPONSE TO PEER REVIEW
RECOMMENDATIONS VIII-1
A. Overview VIII-1
B. Combustion Engineering VIII-3
1. Chemical Emissions from Accidental Fire VIII-3
2. Particle Size Distribution Data VIII-3
3. Emissions During Abnormal Operations VIII-3
4. Facility-Specific Sulfur Dioxide Removal Efficiencies VIII-4
C. Air Dispersion and Deposition Modeling VIII-4
1. Additional Calm/Stagnation Event Modeling - VIII-4
2. Re-evaluate Accident Scenarios Emissions During Calm Conditions VIII-5
D. Exposure Assessment VIII-5
1. Likelihood That Surrogate Selection Process
Biased the Calculated Risk VIII-5
2. Clarify How Chemical Concentration and Exposure
Factors Were Combined VIII-6
3. Exposure to Household Dust VIII-6
4. Expand Table on Key Fate and Transfer Assumptions VIII-6
E. Toxicology VIII-7
1. Route-to-Route Extrapolation of RfDs VIII-7
2. Additivity versus Synergy or Antagonism VIII-7
3. Include List of Noncancer Endpoints VIII-7
4. Exposure to Metals via Breast Milk Pathway VIII-8
5. Uncertainty Associated with Uncharacterized Emissions VIII-8
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CONTENTS
(continued)
F. Ecological Risk Assessment
1. Goals and Purpose
2. Permit Limit Scenario
3. Improve Text Clarity
4. Indicate Key Uncertainties that Influence Conclusions
G. Accident Analysis
1. Pressurized Release
2. Accident Severity and Consequence Information
3. Use of ERPG-2 Values
4. Fire Emissions Similar to Stack Emissions
5. CALPUFF Analysis of Calm/Stagnant Conditions
6. More Appropriate Model for Chemical Evaporation
7. Screening-Level Evaluation for Chemical Concentrations at the
East Elementary School
IX. REFERENCES
TABLES
Table III-l: Data on Polychlorinated Dioxin/Furan Stack Emissions at WTI
Facility Used in the WTI Risk Assessment
Table III-2: Estimated Average and High-end Stack Emission Rates for Dioxin
and Furan Congeners
Table III-3: Estimated Average and High-end Emission Rates for Products of
Incomplete Combustion (PICs) and Residues of Organic Compounds
Table III-4: Estimated Average Metal Emission Rates
Table III-5: Estimated Average Acid Gas and Paniculate Matter Emission Rates
Table III-6: Estimated Average Concentrations of Metals and Inorganic
Compounds in Fugitive Fly Ash Emissions
Table IV-1: Stack Parameters for the WTI Incinerator Stack
Table IV-2: Source Characteristics for Fugitive Emission Sources
Table IV-3: Summary of ISC-COMPDEP Modeling Results for the WTI Main
Incinerator Stack
Table IV-4: Summary of WTI Modeling Results with ISC-COMPDEP
Fugitive Emission Sources
Table V-l: Surrogate Chemicals Selected for the Indirect Risk Assessment of
Stack Emissions
Table V-2: Surrogate Chemicals Selected for the Assessment of Fugitive
Organic Vapor Emissions
Table V-3: Exposure Populations and Pathways Considered in the Risk
Assessment
Page
VIII-8
VIII-8
VIII-9
VIII-9
VIII-9
VIII-10
VIII-10
VIII-10
VIII-10
VIII-11
VIII-11
VIII-11
Vin-12
IX-1
III-8
III-9
III-10
HI-15
III-16
III-17
IV-8
IV-9
IV-10
IV-11
V-13
V-14
V-15
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CONTENTS
(continued)
Page
Table V-4: Estimated Area Average Cancer Risks and Hazard Indices Due to
Exposure from Direct and Indirect Pathways in Subarea El V-16
Table VI-1: Metals Evaluated in the SERA - Stack Emissions VI-10
Table VI-2: Organics Evaluated in the SERA - Stack Emissions VI-11
Table VI-3: Estimated Emission Rates for Metals and Total Cyanide in
Fugitive Fly Ash VI-12
Table VI-4: Estimated Emission Rates - Fugitive Organic Vapor Emissions VI-13
Table VII-1: Scenarios Selected for Quantitative Evaluation VII-13
Table VII-2. Severity of Consequence and Probability of Occurrence
Results for On-Site Scenarios VII-14
Table VII-3: Severity of Consequence and Probability of Occurrence Results
for Off-Site Scenarios VII-15
FIGURES
Figure II-1: Location of the WTI Facility II-5
Figure II-2: WTI Site Plan II-6
Figure III-1: Location of Stack, Fugitive Organic Vapor, and
Ash Emission Sources III-18
Figure VI- i: Diagrammatic Conceptual Site Model for the WTI SERA-Stack
Emissions VI-14
Figure VI-2: Diagrammatic Conceptual Site Model for the WTI SERA-Fugitive
Emissions VI-15
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I. INTRODUCTION AND SUMMARY OF RESULTS
A. Overview
In 1983, Waste Technologies Industries (WTI) received a permit from U.S. EPA Region 5
to construct and operate a hazardous waste incineration facility in East Liverpool, Ohio As
detailed in the permit application, the facility currently consists of a rotary kiln incinerator
with air pollution control equipment; waste transfer, handling and storage areas: an on-site
laboratory for waste testing; and associated administrative buildings. The facility began
limited commercial operations in April 1993, after completion of an initial incinerator trial
burn.
In 1992, U.S. EPA Region 5 performed a preliminary assessment of the potential human
health risks posed by inhalation exposure (i.e., direct exposure) to emissions from the
incinerator stack at the WTI facility (U.S. EPA 1992a). In 1993 and 1994, U.S. EPA's Office
of Research and Development (ORD) performed two screening-level analyses of the potential
human health risks posed by exposures to specific chemicals (polychlorinated dioxins and
furans) that may deposit from the air onto soil and vegetation, and accumulate in the food
chain (i.e., indirect exposures) (U.S. EPA 1993a; U.S. EPA 1994a). The results of the risk
assessments performed by Region 5 and ORD indicate that the potential risks through indirect
exposures are higher than those through direct inhalation. Limited site-specific data were
available in these preliminary assessments, which therefore relied on generic, non-site-specific
assumptions regarding both facility emissions and the potential for human exposure.
In May 1993, U.S. EPA initiated a comprehensive site-specific risk assessment for the
WTI facility. A Project Plan for the WTI Risk Assessment was developed by U.S. EPA
(1993d), and then subjected to external peer review by independent experts in the fields of
combustion technology, atmospheric dispersion modeling, exposure assessment, toxicology
and risk assessment (U.S. EPA 1993e).
Consistent with the Project Plan and Peer Review Panel comments on that plan, there are
three major components of the WTI Risk Assessment:
• Human Health Risk Assessment (HHRA). a detailed, site-specific, multipathway
evaluation that expands upon the screening-level analyses previously performed
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for the WTI facility. The goal of the HHRA is to develop an understanding of
the human health risks associated with exposures to routine emissions from the
WTI facility using refined risk assessment techniques, and provide a.basis for .
risk management decisions.
• Screening Ecological Risk Assessment (SERA), a screening-level analysis to
determine the potential significance of risks to ecological receptors (e.g.. plants.
fish, and wildlife) from exposure to routine emissions from the WTI facility.
The SERA for the WTI facility has been performed using conservative
assumptions and approaches to determine if a refined analysis is warranted.
• Accident Analysis, an evaluation of the consequences and probability of several
general classes of accidents that could potentially occur during operations of the
WTI facility. The Accident Analysis also evaluates the reduction in off-site
impacts that would be expected if mitigation measures succeed in shortening the
duration of accidental release events.
To the extent possible, the WTI Risk Assessment relies on site-specific data to reflect
more accurately emissions from the WTI facility, and local conditions in the vicinity of the
facility. For this purpose, on-site meteorological data were collected, substantial emissions
monitoring was conducted, and studies of the physical characteristics and populations in the
vicinity of East Liverpool were undertaken.
An overview of the approaches and results of the HHRA, SERA and Accident Analysis is
presented below. More complete descriptions are provided in subsequent chapters of this
Executive Summary.
B. Introduction and Overview of Results
1. Human Health Risk Assessment
a) Introduction
The regulatory framework for performing human health risk assessments has
been established through a series of guidance documents issued by U.S. EPA and
other regulatory agencies since the early 1980s. Key examples of guidance developed
by regulatory agencies to define the objectives and approaches for human health risk
assessment are listed below:
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• National Research Council (NRC). 1983. Risk Assessment in the Federal
Government: Managing the Process.
• U.S. EPA. 1986a. Guidelines for Carcinogen Risk Assessment.
U.S. EPA. 1986b. Guidelines for the Health Risk Assessment of Chemical
Mixtures.
• U.S. EPA. 1989. Risk Assessment Guidance for Superfund. Volume I
Human Health Evaluation Manual (Part A).
• U.S. EPA. 1994b. Estimating Exposure to Dioxin-like Compounds
(Review Draft)
• U.S. EPA. 1995a. Guidance for Risk Characterization.
Through these documents, guidelines for performing both qualitative and
quantitative human health risk assessments have been defined. U.S. EPA has also
released specific guidance for applying the general human health risk assessment
methodologies to incineration facilities, including the following:
• U.S. EPA. 1990a. Methodology for assessing health risks associated with
indirect exposure to combustor emissions, Interim Final.
• U.S. EPA. 1993b. Addendum to "Methodology for assessing health risks
associated with indirect exposure to combustor emissions" (Review
Draft).
• U.S. EPA. 1994c. Implementation guidance for conducting indirect
exposure analysis at RCRA combustion units (Draft).
U.S. EPA (1994c) guidance for hazardous waste combustion facilities regulated
under the Resource Conservation and Recovery Act (RCRA) specifies a two-step
approach for assessing human health risks. The first step is a screening-level risk
assessment performed to determine if a more detailed, site-specific evaluation of risk
is warranted. For the WTI facility, a preliminary assessment of human health risks
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through inhalation exposure was performed by U.S. EPA in 1992. Preliminary Risk
Assessment of Inhalation Exposures to Stack Emissions from the WTI Incinerator
(U.S. EPA 1992a). This was followed by two screening-level assessments of
multipathway exposures, one performed by ORD in 1993, Screening Level Anahsis o1
Impacts from WTI Facility (U.S. EPA 1993a). and another performed by ORD in
1994, Update of WTI Screening Level Analysis (U.S. EPA 1994a). The following
four scenarios were developed in the screening-level assessments: (1) a subsistence
farmer, (2) a "high-end" farmer1; (3) a resident; and (4) a school age child who is
expected to spend time playing in the yard at a local school. Pathways of exposure
were beef consumption for the farmer scenarios only; vegetable ingestion for the
resident and farmer scenarios; and soil ingestion, dermal contact and inhalation for all
scenarios.
In response to citizen concerns, the U.S. EPA initiated a detailed, site-specific.
multipathway risk assessment for the WTI facility, as soon as site-specific information
became available. The primary goal of the HHRA is to estimate risks associated with
typical and high-end exposure to routine atmospheric emissions from the WTI facility.
including risks posed by indirect exposures associated with contaminant uptake via the
food chain. Consistent with U.S. EPA guidelines on exposure assessment, estimates
of "central tendency" exposures are developed to reflect exposures that may be
experienced by typical members of the exposed population. In addition, individuals at
the upper end of the exposure distribution are identified, and a sensitivity analysis of
this "high-end" exposure group is conducted to assess the range of exposures in this
group.
b) Overview of Results
The primary conclusions of the HHRA are summarized below:
• For incinerator stack emissions, polychlorinated dioxins and furans
(PCDD/PCDF) are identified as the primary constituents of concern. The
consumption of meat and eggs from locally raised livestock, and the
consumption of milk and dairy products from locally raised cows are
identified as principal pathways of exposures to PCDD/PCDF. For these
pathways, the estimated average total cancer risk is 1 in 1 million (1 x 10h)
or less. Estimated average noncancer hazard index (HI) values are below
The subsistence farmer is assumed to derive his entire beef diet from cattle raised in the vicinity of the WTI
facility The "high-end" farmer is assumed to derive a portion of his beef diet from other sources
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1.0, indicating that noncancer health effects associated with stack emissions
would not be anticipated.
• For fugitive emissions, average cancer risks are estimated to be less than 2 in
1 million (2 x 10~6) for all fugitive emission sources. The estimated
noncancer HI values associated with exposure to fugitive emissions are
substantially below 1.0, indicating that noncancer health effects would not be
anticipated.
• Based on an evaluation of site-specific, incremental risk across the entire
population in the vicinity of the WTI facility, it is not anticipated that am
individual in this population would develop cancer as a result of exposure to
routine WTI emissions.
• Predicted off-site air concentrations of U.S. EPA-regulated "criteria
pollutants," such as sulfur dioxide, nitrogen oxides, hydrogen chloride,
paniculate matter, and lead are determined to be less than National Ambient
Air Quality Standards.
2. Screening Ecological Risk Assessment (SERA)
a) Introduction
A SERA has been performed to assess the potential for routine emissions from
the WTI facility to cause adverse effects to ecological receptors. For this purpose.
the major ecological receptors in the vicinitv of the WTI facility were identified,
likely exposure pathways were defined for stack and fugitive emissions, exposures to
selected ecological chemicals of concern (ECOCs) were estimated for representative
indicator species, and toxicological benchmarks (based on ecologically relevant
endpoints) were developed to evaluate the potential ecological effects of facility
emissions.
In many ways, ecological risk assessment is much more complex than human
health risk assessment. This stems largely from the need to evaluate multiple species
with widely differing exposures and toxicological sensitivities, and multiple effects at
levels of organization beyond the individual (i.e., the population and community)
Furthermore, chronic toxicological benchmarks are less well established for
ecological risk assessments than for human health risk assessments. As a result,
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compared to human health risk assessments, ecological risk assessments (especialh at
the screening level) generally rely on more qualitative methodologies, with a resulting
increase in uncertainty.
Regulatory guidance relating to specific methodologies for conducting ecological
risk assessments is limited, compared to the guidance available for human health risk
assessments. Key guidance documents used in the SERA, which define the objectives
and approaches of ecological risk assessment, include the following:
• U.S. EPA. 1992d. Framework for Ecological Risk Assessment.
• U.S. EPA. 1994e. Ecological Risk Assessment Guidance for RCRA
Corrective Action, Region 5. (Interim Draft)
Screening-level assessments represent the first phase in the ecological risk
assessment process. The need for, and focus of, additional phases of assessment are
determined by the results of the screening-level assessment. A SERA is the first
phase in the process described in Region 5 guidance (U.S. EPA 1994e). According
to the U.S. EPA's 1992 Framework for Ecological Risk Assessment (U.S. EPA
1992d), a screening ecological risk assessment "may be performed using readily
available data and conservative assumptions; depending upon the results, more data
then may be collected to support a more rigorous assessment." Because screening-
level analyses are generally performed using conservative assumptions and
approaches, the predicted risks are much more likely to be overestimated than
underestimated.
The SERA for the WTI facility is intended to complement the detailed HHRA.
Thus, consistent approaches and assumptions are used where appropriate in the SERA
and HHRA. For example, the atmospheric dispersion modeling performed for the
facility is common to both analyses. However, in contrast with the HHRA. which
focuses on central tendency exposures, the SERA relies on conservative (high-end)
estimates of emission rates and exposure parameters to produce reasonable upper-
bound estimates of risk. Examples of conservative approaches used in the SERA
include the following:
• To maximize hypothetical exposures, the ecological receptors considered in
the SERA are assumed to be present at the location of maximum impact of
facility emissions, with lifetime home ranges confined to the maximum
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impact point For example, for fugitive organic vapor emissions, exposures
are estimated at locations where airborne concentrations are estimated to be
the highest.
• Exposures are compared with toxicity data representing, where available, the
lowest chronic no-effect level data for ecologically relevant endpomts (e.g..
growth and reproduction).
• The SERA includes a "permit limit" scenario for stack emissions of metals
This upper-bound scenario is based on continuous emissions of stack metals
at the maximum hourly emission limits, as defined in the facility's existing
RCRA permit. A separate evaluation based on "expected" metal emission
rates is also performed.
The SERA conducted as part of the WTI Risk Assessment provides an initial
evaluation of potential risks to ecological receptors that may be directly exposed to.
or indirectly affected by, routine stack emissions and fugitive emissions. It screens
out those combinations of ECOCs, exposure pathways, and receptors where risks are
negligible, and it provides a focus for any additional evaluation that may be warranted
in a subsequent phase of assessment.
b) Overview of Results
The conclusions of the SERA are summarized below
• The area surrounding the WTI facility contains a wide variety of terrestrial.
wetland, and aquatic habitats and numerous plant, fish, and wildlife species.
• There are no recorded sightings of species listed as rare, threatened, or
endangered by Federal and State agencies within one kilometer of the
facility. The nearest known sightings of such species (two state-listed fish
species) occur approximately four kilometers southwest of the facility in the
Ohio River. Because of limited exposures, neither fish species (or any other
listed species) is likely to be adversely impacted by routine facility
emissions.
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• The maximum estimated exposure points for both stack and fugitive
emissions are within one kilometer of the facility.
• Under the expected emission scenario for metals from the incinerator stack.
low to negligible ecological risks are indicated.
• For routine emissions of organic compounds from the incinerator stack, low
to negligible ecological risks are indicated.
• For fugitive inorganic emissions from the ash handling facility, low to
negligible ecological risks are indicated.
• For fugitive organic vapor emissions, low to negligible ecological risks are
indicated except for formaldehyde. For formaldehyde, risks of relatively low
magnitude are indicated for wildlife in a small area immediately adjacent to
the tank farm, where inhalation exposures would be limited because of
habitat considerations and thus significant adverse effects to wildlife
populations and community structure are very unlikely.
• Under the "permit limit" scenario for metals in incinerator stack emissions,
risks of relatively high magnitude are indicated for six metals. Risks are
highest for thallium, selenium, barium, and nickel. However, as discussed
in Volume VI, Chapter I, this scenario is not necessarily representative of the
expected metal emissions (and resulting risks) from the facility stack.
Given the conservative assumptions used in the SERA, the likelihood of
significant risks to ecological receptors as a result of expected levels of routine
incinerator stack and fugitive emissions is predicted to be very low and further
assessment does not appear warranted. The conservative assumptions used in the
SERA and the uncertainty analysis provide a relatively high degree of confidence in
this low prediction of risk. If the WTI facility were to operate continuously at the
maximum hourly permit limits for metals, however, risks of relatively high magnitude
are predicted in the SERA. Although it is theoretically and legally possible for the
WTI incinerator to continuously emit met; Is at the permit limits, this is considered
unlikely based on the results of stack testing. For example, the "expected" emission
rate for thallium based on stack testing is over 10,000-fold lower than the permit limit
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(see Chapter VI). Quantifying the likelihood and possible extent of potential effects
under the permit limit scenario would require a more refined analysis. However.
because the scenario is not considered to be realistic and does not reflect emissions
expected during routine operations, it represents an absolute upper-bound condition
Therefore, if stack metal emissions do not reach the levels associated with this
scenario, it is highly probable that routine operations of the WTI facility would not
pose a significant risk to ecological receptors.
3. Accident Analysis
a) Introduction
An Accident Analysis has been performed to evaluate the likelihood and potential
off-site consequences of accidents that may occur during operations of the WTI
facility. Because it is not possible to identify and assess all accidents that could
hypothetically occur at the facility, a subset of accidents reflecting a range of severity
of consequence and probability of occurrence is evaluated. This subset has been
selected to address outcomes (e.g., spills, fires) that could be caused by different
initiating events. The results of this type of analysis typically provide information
that can be used to reduce the likelihood, extent and impact of possible accidents, as
suggested by the following key guidance documents:
• U.S. EPA, Federal Emergency Management Agency (FEMA). and I' S
Department of Transportation (U.S. DOT). 1987. Technical Guidance
for Hazards Analysis: Emergency Planning for Extremely Hazardous
Substances.
FEMA, U.S. EPA, and U.S. DOT. 1993. Handbook of Chemical
Hazard Analysis Procedures.
U.S. EPA. 1996. Accidental Release Prevention Requirements: Risk
Management Programs under Clean Air Act Section 112(r)(7); Final
Rule.
These documents outline a general approach for performing accident analyses at a
broad range of industrial facilities. The scope of accident analysis varies widely.
however, and the application of standard accident analysis methodologies to
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hazardous waste treatment facilities is relatively complex due to the variable
composition of the wastes handled. For example, while most industrial plants
typically handle a limited number of chemical reagents and products, a hazardous
waste treatment facility often receives chemical mixtures that can vary significantly
from day to day in terms of both composition and potential hazard.
In contrast with the HHRA and SERA, where measurements have been made to
establish the composition and magnitude of emissions under normal facility
conditions, there is insufficient operational history at WTI (or comparable facilities)
to accurately predict the nature of releases which may occur as a result of specific
accidents. Despite such uncertainties, the Accident Analysis provides useful
information regarding the possible effect of facility accidents, should they occur.
A primary goaJ of the Accident Analysis is to identify accident scenarios that
"have a reasonable likelihood of occurrence in the foreseeable future and/or which
may have significant consequences in the absence of an organized, rapid, and
effective response effort" (FEMA 1993). To accomplish this goal, key aspects of the
Accident Analysis include the following:
• Three general classes of on-site accidents (spill, fire, and mixing of
incompatible wastes) and two general classes of off-site accidents (spill and
fire) are evaluated. For each type of accident, two release quantities
("typical" and "conservative") are evaluated.
• Two waste compositions ("typical" and "conservative") are evaluated for
each accident event, to address uncertainties introduced by the variable
composition of the waste received by the facility.
Three sets of meteorological conditions ("typical," "conservative," and
"calm/inversion") are evaluated for each accident scenario, to determine the
effect of different conditions on predicted chemical concentrations.
• Severity of consequence is evaluated quantitatively through a comparison of
predicted chemical concentrations in air with acute toxicity criteria.
Probability of occurrence is evaluated semi-quantitatively through a
consideration of the likelihood that different types of accidents (e.g., spills)
will occur during facility operations.
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Given the objectives of the Accident Analysis, probability of occurrence has been
evaluated using the following guidelines presented by FEMA (1993):
Common Expected to occur one or more times each year on average
Likely Expected to occur at least once every 10 years on average.
Reasonably Predicted to occur between once every 10 years and once every
Likely 100 years on average.
Unlikely Predicted to occur between once every 100 years and once every 1.000
years-on average.
Very Predicted to occur less than once in 1,000 years.
Unlikely
FEMA (1993) also presents a four-tier system for classifying the consequences of
accident scenarios. The definitions provided by FEMA (1993) for categorizing
consequences are not directly applicable to the WTI Accident Analysis However, the
general system described in FEMA (1993) serves as the basis for the following
severity of consequence categories developed specifically for the WTI Accident
Analysis using U.S. EPA Level of Concern (LOG) values as acute toxicity criteria
Minor No exceedance of an LOG value in inhabited off-site areas; and
negligible potential for off-site fatalities or serious injuries due to
heat effects from a fire.
Moderate Exceedance of LOG values in inhabited off-site areas over distances
of 200 meters or less; injuries due to heat effects limited to a
distance of 200 meters into inhabited areas.
Major Exceedance of LOG values in inhabited off-site areas over distances
between 200 meters and 2,000 meters; injuries due to heat effects
limited to a distance of 2,000 meters into inhabited areas.
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Catastrophic Exceedance of LOG values in inhabited off-site areas over distances
greater than 2,000 meters: injuries due to heat effects extend to
distances greater than 2,000 meters into inhabited areas.
A similar system based on NIOSH Immediately Dangerous to Life or Health
(IDLH) values has also been developed:
Minor No exceedance of an Immediately IDLH value in inhabited off-site
areas; and negligible potential for off-site fatalities or serious
injuries due to heat effects from a fire.
Moderate .Exceedance of IDLH values in inhabited off-site areas over
distances of 100 meters or less; injuries due to heat effects limited to
a distance of 100 meters into inhabited areas.
Major Exceedance of IDLH values in inhabited off-site areas over
distances between 100 meters and 1,000 meters; injuries due to heat
effects limited to a distance of 1,000 meters into inhabited areas.
Catastrophic Exceedance of IDLH values in inhabited off-site areas over
distances greater than 1,000 meters; injuries due to heat effects
extend to distances greater than 1,000 meters into inhabited areas.
The overall significance of potential accidents at the WTI facility is characterized
by combining severity of consequence and probability of occurrence ratings.
b) Overview of Results
The results of the Accident Analysis are summarized below:
• For on-site accidents, only events with minor off-site consequences are
considered likely to occur at the WTI facility, and only events with minor or
potentially moderate off-site consequences are determined to be reasonably
likely to occur.
S'
• All on-site accident scenarios with potentially major off-site consequences are
determined to be unlikely to occur, and all on-site accidents with potentially
Volume I
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catastrophic off-site consequences are determined to be very unlikeh to
occur.
• For off-site accidents, events with minor consequences are determined to he.
at most, reasonably likely to occur.
• All off-site accident scenarios with potentially moderate or major
consequences are found to be unlikely or very unlikely to occur, and off-site
accidents classified as having potentially catastrophic consequences are
determined to be very unlikely to occur.
These results are consistent with the information presented in U.S. EPA's Report
on Emergency Incidents at Hazardous Waste Incinerators and Commercial Treatment,
Storage and Disposal Facilities (U.S. EPA 1995b). Using the data from U.S. EPA
(1995b) and the definitions presented in FEMA (1993), events having moderate.
major or catastrophic off-site consequences are classified as unlikely or very unlikely
to occur over a facility lifetime. Only events having minor off-site consequences are
classified as likely or reasonably likely to occur. This generally agrees with the
consequence/probability rankings developed for the WTI facility in the Accident
Analysis.
C. Structure of the Report
This report presents the approaches and results of the WTI Risk Assessment, and consists
of eight volumes, as follows.
• Volume I: Executive Summary
• Volume II: Introduction
• Volume III: Characterization of the Nature and Magnitude of Emissions
• Volume IV: Atmospheric Dispersion and Deposition Modeling
• Volume V: Human Health Risk Assessment: Evaluation of Potential Risks from
Multipathway Exposure to Emissions
• Volume VI: Screening Ecological Risk Assessment
• Volume VII: Accident Analysis: Selection and Assessment of Potential Release
Scenarios
• Volume VIII: Additional Analysis in Response to Peer Review Recommendations
Volume T 1-13
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The remainder of this Executive Summary presents additional details on the approaches
employed and results obtained in the WTI Risk Assessment. It is organized into chapters
corresponding to the individual volumes of the WTI Risk Assessment report.
Volume T T 14
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II. FACILITY BACKGROUND
A. Facility Setting
The WTI hazardous waste incineration facility is situated on 21.5 acres of land along the
Ohio River in East Liverpool, Columbiana County, Ohio. It is located directly across the
Ohio River from West Virginia and less than a 1 Vi miles west of the Pennsylvania-Ohio
border. The specific location of the WTI facility is shown in Figure II-1.
The WTI property is zoned for general industrial activity. It is bordered on the north by
Conrail railroad tracks, on the west by the Port Authority building, and on the south and east
by the Ohio River. The area immediately north of the railroad tracks and west of the Port
Authority building is zoned for medium-high density residential uses. This area is comprised
primarily of single-family homes, and includes an elementary school and a business college.
The Ohio River along the stretch adjacent to the WTI facility is approximately 1.200 to 1.500
feet wide, with residential areas along the West Virginia side of the river.
The population of East Liverpool is approximately 14,000, according to the 1990 census.
In addition to East Liverpool, the closest towns to the WTI facility are Chester, West Virginia
(approximately one mile southeast of the site); Wellsville, Ohio (approximately six miles west
of the site); and Midland, Pennsylvania (approximately five miles east of the site). The
nearest major city is Pittsburgh, which lies approximately 30 miles to the southeast of East
Liverpool.
The general area surrounding East Liverpool is largely rural, including beef, dairy, and
mixed agricultural farms. However, a number of small industrial facilities, including an
asphalt roofing plant and a china manufacturer, are also located within two miles of the WTI
facility. Industrial operations located within 10 miles of the WTI facility include specialty
steel operations, petroleum storage facilities, nuclear and coal fired power plants, and a large
refinery.
There are 4 state parks, 1 state forest, and 3 major wildlife management areas located
within approximately 20-kilometers (12.5 miles) of the WTI facility. This area also includes
numerous forests and wooded lots. In addition to the Ohio River, there are approximately 90
non-intermittent rivers and streams, and approximately 50 wetland areas greater than 10 acres
within 20-kilometers of the WTI facility. Due to the diversity of habitats in the general
Volume! II-1
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vicinity, there are diverse plant and animal communities composed of numerous plant.
mammal, bird, reptile, amphibian, fish, and other species. Some of the species within the
WTI assessment area are classified as rare or endangered by the Federal government or the
States of Ohio, Pennsylvania, or West Virginia.
The WTI facility is located within the Ohio River Valley, which creates complex
meteorological conditions. For example, there is strong channeling of wind at lower
elevations within the valley that is not present at higher elevations. Furthermore, some areas
in the vicinity of the facility are at elevations higher than the incinerator stack. These aspect
of the facility setting are addressed in the atmospheric dispersion modeling conducted tor this
assessment.
B. Facility Description .
The WTI hazardous waste incineration system is designed to thermally oxidize hazardous
waste regulated under Subtitle C of RCRA. The facility is expected to treat between 52,000
tons and 77,000 tons of liquid, solid, and semi-solid RCRA hazardous waste annually in a
single, rotary kiln incinerator. These hazardous wastes are required to be treated in
accordance with applicable regulations and the facility's operating permits, as issued by U.S.
EPA Region 5, the Ohio Environmental Protection Agency (OEPA) Divisions of Water, Air
Pollution Control, Solid and Hazardous Waste, and the Hazardous Waste Facility Approval
Board (HWFAB). The HWFAB, which was later renamed the Hazardous Waste Facility
Board (HWFB), is a state regulatory body which works in conjunction with the OEPA. WTI
has not been authorized to accept polychlorinated biphenyls (PCBs) in concentrations
exceeding 50 parts per million, dioxins, asbestos, radioactive wastes, or war gases
Support operations for the rotary kiln incinerator include a guard house, administrative
and maintenance buildings, a truck holding and sampling area, a drum processing facility, an
organic waste tank farm, and the incinerator feed building. There are also three different
waste water systems on-site: System A, which collects uncontaminated surface water; System
B, which collects storm water from inactive process areas; and System C, which collects water
from active process areas. WTI has a permit for a second rotary kiln incinerator and an
inorganic waste treatment plant, neither of which have been constructed. A site map is shown
in Figure II-2.
Wastes shipped to the WTI facility are pre-approved by the facility and registered on a
computerized waste tracking system. On arrival at the facility, wastes are sampled in
accordance with the facility waste analysis plan and directed to the appropriate process
treatment area, as follows:
Volnmo T TT
-------
Bulk solid wastes are sampled upon arrival at the facility. After approval, these
wastes are emptied into pits in a building immediately adjacent to the incinerator A
clam shell bucket then transfers the waste from the waste pits into a teed hopper for
the incinerator.
• Bulk liquid wastes are delivered to the facility in tanker trucks and sampled on
arrival. After approval, the tankers are moved to a diked, concrete area, where
wastes are pumped into an indoor tank farm.
• Drummed wastes are sent directly to the drum processing building, where at least one
out of every 10 drums of each waste stream is normally sampled. After approval, the
contents are generally pumped to pump-out tanks located to the south of the drum
processing building. Non-pumpable liquids, such as sludges, are usually extruded
from drums, mixed with pumpable waste, and then stored in tanks on the south side
of the drum processing building. Drums can also be fed directly to the incinerator
without being emptied.
All major waste handling, storage and treatment areas are concrete-lined and contain
collection sumps for the capture of spilled material. In addition, all major handling areas are
serviced by ventilation hoods that send collected vapors to the incinerator or to a carbon
adsorption bed system. There is also an extensive fire suppression system consisting of water
sprays and foams throughout the various waste handling and storage areas.
The WTI incinerator consists of a rotary kiln, waste feed mechanisms, a secondary
combustion chamber, a heat recovery boiler, air pollution control devices, a flue stack, solid
residue removal equipment, and computerized process control and instrumentation systems.
The rotary kiln is a refractory-lined cylindrical shell 15 feet in diameter and 43 feet in length
Hazardous wastes enter the rotary kiln and are oxidized at temperatures of approximately
1,800°F to 2,200°F. Gases produced during oxidation consist primarily of carbon dioxide
(CO2), nitrogen oxides (NOJ, and water, along with smaller quantities of organic compounds
(including products of incomplete combustion), metals, and acid gases (such as hydrogen
chloride and sulfur oxides). Non-combustible wastes generally melt at the high temperatures
in the kiln and form a residual viscous material known as slag. The gases from the kiln pass
to the secondary combustion chamber to provide for greater destruction of residual organic
compounds present in the gas stream.
The secondary combustion chamber is 61 feet high, 21 feet long, and 22 feet wide, and is
intended to enhance the destruction of organic compounds. Combustion gases exit the
Volume I II-3
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secondary combustion chamber at a temperature between approximately 1.350°F and 1.500°F.
and pass through a heat recovery boiler to generate steam for use at the WTI facility.
After cooling in the heat recovery boiler, the combustion gases pass to the air pollution
control system. The air pollution control system consists of a spray dryer, an enhanced carbon
injection system (ECIS), an electrostatic precipitator. a flue gas quench, and a tour-stage uet
scrubber system. The purpose of the air pollution control system is to reduce the
concentrations of organics, metals, acid gases, and paniculate matter in the combustion gas
stream. The resulting flue gas is discharged into the atmosphere from a 150-foot stack
Volume I II-4
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III. FACILITY EMISSIONS
A. Overview
Routine operations will result in emissions from several locations at the WTI facility.
including stack gases from the incinerator, organic vapors emitted during waste processing and
storage, and paniculate matter released during handling of ash produced by incineration. The
locations of potential stack; fugitive organic vapor and ash emission sources are shown on
Figure III-l. In addition to these emissions during routine operations, there is also the
potential for releases during both on-site and off-site accidents. An initial step of the WTI
Risk Assessment is the identification of process-specific emission sources, characterization of
the composition of emissions from these sources, and development of emission rates for the
substances of primary concern from each significant source.
Site-specific data and information are used in this study to the extent possible to
characterize both routine emissions during normal operation and releases during accidents.
For example, measurements from a series of trial burns and performance tests are used to
characterize incinerator stack emissions, and waste profile information based on projections
for the first year of WTI operations is used in calculating routine fugitive emissions and
accidental releases. The specific approaches used in characterizing routine emissions for this
assessment are summarized below. Emissions associated with potential accidents are discussed
in Chapter VII of this Executive Summary.
B. Incinerator Stack Emissions
In the risk assessment, substances of potential concern in the incinerator stack gases are
classified as follows:
• Polvchlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs). which are believed to
be a product of combustion of some types of hazardous wastes;
• Other organic chemicals, including products of incomplete combustion (PICs) other
than PCDDs/PCDFs, and residues of organic chemicals present in the feed that are
not completely combusted in the incinerator;
Volume I III-l
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• Metals, which may be present in the waste but can not be destroyed b\ combustion.
• Acid gases, such as nitrogen oxides (NOX). sulfur oxides (SOX). and hydrogen
chloride (HC1), which are formed during the combustion process, and
• Paniculate Matter, which may be entrained in the stack gas during waste combustion.
or formed as flue gases cool in the post-combustion zone of the incinerator.
Comprehensive stack testing, including the collection of several sets of data on
PCDD/PCDF emission rates, was performed at the WTI facility to provide site-specific
estimates of organic emissions. Two major stack emission measurement programs have been
completed at the WTI facility:
• Trial burns conducted in March 1993 and February 1994; and
• Incinerator performance tests conducted in August 1993, February 1994. April 1994.
August 1994 and December 1994.
The trial burns at the WTI facility relied on engineered waste feeds synthesized to
represent reasonable worst-case combustion or emission conditions. These trial burns were
required to:
• Demonstrate that the incineration system would meet permit requirements for organic
destruction and removal efficiency (DRE);
• Demonstrate that HC1, chlorine, and paniculate matter emissions would meet permit
requirements under worst-case operating conditions;
• Establish system removal efficiencies (SREs) for specific metals; and
• Determine the range of allowable operating conditions for the incineration system
The performance tests differ from the trial burns in that they were conducted during
normal operating conditions, burning wastes considered typical for the WTI facility. Thus.
performance tests are believed to be more representative of day-to-day operations, while trial
burns are meant to evaluate reasonable worst-case conditions.
Volume T TTT-2
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The WTI Risk Assessment relies on measurements from 26 PCDD/PCDF test runs
conducted between August 1993 and August 1994 (shown in Table III-l). and seven
comprehensive PIC test runs conducted in August 1994. PCDD/PCDF data collected at the
WTI facility prior to the installation of the enhanced carbon injection system (ECIS) in Jul\
1993 are not used in developing incinerator stack emission rates for the Risk Assessment
Furthermore, the PCDD/PCDF and PIC test runs conducted during the December 1994
performance tests were not available in time for developing emission rates for the WTI Risk
Assessment.
To supplement the site-specific measurements from the stack testing program, emissions
of chemicals not analyzed during the stack testing are estimated by developing a waste teed
chemical composition profile (from projections based on actual wastes received at the WTI
facility during the first nine-months of operation), and applying an incinerator DRE (based on
waste feed and incinerator stack testing at the WTI facility). Estimated emission rates for
PCDDs/PCDFs based on stack tests at WTI are shown on Table III-2; estimated emission rates
developed for PICs are shown on Table III-3.
Emission rates are developed for 15 metals expected to be present in at least some waste
streams received by the WTI facility. Although most of the metals would be captured in the
incinerator slag and ash, a fraction of each metal is expected to escape the emission control
systems and be released to the atmosphere via the stack. The 15 metals for which emission
rates have been estimated are aluminum, antimony, arsenic, barium, beryllium, cadmium,
chromium, copper, lead, mercury, nickel, selenium, silver, thallium, and zinc. Emission rates
for these metals, shown on Table III-4, are estimated based on SRE data compiled from the
March 1993 trial burns, along with projected waste feed data for the WTI facility. Data on
SREs at the WTI facility are available for seven metals (antimony, arsenic, beryllium.
cadmium, chromium, lead, and mercury) tested in the March 1993 trial burn. SRE values tor
the remaining eight metals evaluated in the risk assessment are extrapolated from the trial burn
data for the seven metals, considering the results of thermodynamic modeling performed
specifically for the Risk Assessment.
Emission rates for HC1, NO,, SO,, and paniculate matter, shown on Table III-5, are
based on stack measurements at the WTI facility. For HC1, data from a total of 13 runs
collected during the March 1993 and February 1994 trial burns are used to estimate emission
rates for the WTI Risk Assessment. Emission rates for NOX and SOX are based on one
randomly selected month of continuous monitoring data, collected from February 23, 1995 to
March 21, 1995. Paniculate matter emission rates are based on 13 runs collected during the
March 1993 and February 1994 trial burns, and 22 runs from the performance tests.
-------
C. Fugitive Emissions
Atmospheric emissions may occur from a variety of sources other than the incinerator
stack during normal operations. These releases, which are collectively termed "fugitive"
emissions, may be generated during waste unloading, processing, and storage, and the
handling of incinerator ash. Through a review of information in the WTI facility permit
application and permit, an evaluation of the types of wastes handled by each of the facilitx
operations, and a facility site visit, the following fugitive emission sources were selected for
evaluation in the risk assessment:
• The Carbon Adsorption Bed (CAB) System, which receives organic vapors vented
from tanks in the organic waste tank farm operations in the container processing
building;
• Seals. Valves, and Flanges, associated with storage and process tanks inside the
organic waste tank farm building;
• The C system waste water holding tank, which collects potentially contaminated storm
water from active process areas within the facility;
• The on-site truck wash station, which is used to clean tank trucks; and
• Routine fugitive ash releases, from the bag filter used to control emissions during
loading of fly ash from the ESP into trucks.
Fugitive emissions from the first four sources listed above are in the vapor form, while
emissions from the fifth source, ash handling, are in the form of paniculate matter. Vapor
emissions are expected primarily from pumpable wastes, which typically have the highest
concentration of volatile chemicals. To identify constituents of primary concern in the vapor
emissions, a composite pumpable waste stream consisting of over 300 chemicals has been
developed based on estimated annual feed rates calculated using the WTI waste profile
information. The list of over 300 chemicals is truncated to include only those chemicals
received by the facility in the largest volumes, i.e., the approximately 100 chemicals that,
taken together, constitute 90% of the total pumpable waste. Vapor-phase fugitive emissions
are calculated using U.S. EPA models along with the physical/chemical properties of the waste
constituents, data and information from the WTI permit and permit application, and
information on facility design and operation. Based on these approaches, the total fugitive
Vnlumo I TTT 1
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organic vapor emission rates calculated for each source evaluated in the Risk Assessment are
as follows:
Valves and Manges (Tank Farm Building): 2,126 Ibs./year;
Carbon Adsorption Bed System: 224 Ibs./year:
Waste Water Tank: 202 Ibs./year; and
• Truck Wash Building: 10 Ibs./year.
Fugitive emission rates.for individual organic compounds in the waste feed are estimated
for a subset of organic constituents referred to as "surrogates" (see Chapters V and VI).
Emission rates for "surrogate" constituents in the fugitive vapor releases are developed based
on relative concentrations in the pumpable waste and physical/chemical properties.
Fugitive paniculate matter emissions from the ESP bag filter consist primarily of fly ash
produced during combustion of the hazardous waste. This fly ash contains potentially
hazardous metals, and generally has a very fine consistency. In the WTI Risk Assessment,
concentrations of metals and other hazardous chemicals are estimated based on testing of fly
ash samples collected from the ESP at the WTI facility. The samples were analyzed for 80
organic compounds, cyanide, and 9 metals. None of 80 organic compounds were detected in
any of the 12 fly ash samples tested, and thus organic chemicals are not identified as
substances of potential concern in fugitive ash emissions. Cyanide was detected in the fly ash
samples along with the following metals: arsenic, barium, cadmium, lead, nickel, selenium.
and silver.
Total paniculate matter emissions from the bag filter are calculated based on a total fly
ash generation rate of 5,300 tons per year, an empirically developed uncontrolled ash
emissions factor modified to account for the average moisture content of the fly ash, and the
expected control efficiency of the fabric filter. Emission rates for specific constituents in the
fugitive ash releases are based on concentrations detected in the fly ash samples, and are
shown in Table III-6.
D. Uncertainties
The estimation of emissions from the incinerator stack and from fugitive sources is an
important initial step in the Risk Assessment. Uncertainties associated with this step of the
assessment may affect the results of both the human health and ecological risk assessments
Volume I III-5
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The primary sources of uncertainty in estimating stack and fugitive emissions are described in
the following sections.
1. Uncertainties in Stack Emissions Characterization
The primary sources of uncertainty associated with the estimation of stack emissions
are summarized as follows:
• Variability of feed rates - The estimation of emission rates for metals and certain
organic chemical residues (for which stack testing was not conducted) is highly
dependent on the feed rate Limited data, which might not be fully representative
of long-term operations, are used to estimate feed rates.
• Use of predictive models - Thermodynamic modeling is conducted to provide
information on the behavior of metals in the incineration system. Several
simplifying assumptions are used in simulating metal behavior in the various
zones within the incinerator and air pollution control system. These assumptions
introduce unquantifiable uncertainties, but are believed to be appropriate given
the information available.
• Compounds not detected in stack sampling - Compounds that were analyzed for,
but were not detected, in the stack emissions are assumed to be present at one-
half the detection limit of the compound. Several of these chemicals significantly
influence the estimated risks.
• Uncharacterized stack emissions - Although stack sampling was conducted,
samples may contain compounds that are not conventional analytes and, as a
result, may not be characterized in the analysis. Levels of known constituents in
the emissions are prorated to account for this uncharacterized fraction.
introducing uncertainty into the risk assessment.
2. Uncertainties in Fugitive Emissions Characterization
The major sources of uncertainty associated with estimation of fugitive emissions
from routine storage and handling activities are summarized as follows:
Voliimp T TTT «;
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Characterization of wastes handled at the facility - Fugitive vapor emissions are
highly dependent on the waste characteristics. Limited data, which might not he
fully representative of long-term operations, are used to estimate emission rates
Modeling of tank farm emissions - The primary source of fugitive emissions is
predicted to occur from leaks in the flanges, seals, and valves in the waste
storage tank farm. Emissions from the tank farm are estimated based on
empirical emission factors that might not be fully representative of conditions at
the facility depending on operating practices at WTI.
Waste water tank emissions - Emissions from the waste water holding tank are
estimated using a predictive model. Conservative assumptions are applied in
characterizing the constituents that may be present in the waste water.
Volume I IH-7
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TABLE IH-1
Data on Polychlorinated Dioxin/Furan Stack Emissions at WTI Facility
Used in the WTI Risk Assessment-
August 1993
l-ebruar\ 1994
February 1994
April 1994
August 1994
Type of Testing
Performance Test
Performance Test
Trial Burn
Performance Test
Performance Test
Tests
Performed
Run 1
Run 2
Run 3
Run 4
Run 5
Run 1
Run 2
Run 3
Run 4
Run 5
Run 1
Run 2
Run 3
Run 4
Run 1
Run 2
Run 3
Run 4
Run 5
Run 1
Run 2
Run 3
Run 4
Run 5
Run 6
Run 7
Chlorine
Feed Rate
(Ih/hrt
2386
2573
2351
2387
1823
2530
2103
1790
1970
1500
2958
3304
3231
3109
2459
2234
2004
2109
1389
1049
411
414
390
1904
1017
399
Total
Concentration
6
7
39
6
6
8.8
3.2
4.8
5.0
4.9
6.2
4.9
3.7
3.6
4.5
4.8
3.4
2.5
3.5
1.7
0.7
1.2
1.0
1.4
1.5
1.9
TEQ
Concentration
(ng/dscm)c
0.10
0.12
0.27
0.11
0.11
0045
0.019
0.028
0.029
0.035
0.084
0.072
0.057
0.056
0.037
0.036
0035
0.032
0.033
0.017
0.010
0.016
0.017
0.018
0.021
0.021
TEQ
Emission Rate
Ig/s)
1 7E-09
2 1E-09
3 8E-09
2 1E-09
2.2E-09
1 2E-09
5 5E-10
7.8E-10
8.3E-10
9.6E-10
1.2E-09
1 OE-09
8.3E-10
8 5E-10
4 9E-10
4.6E-10
4.3E-10
4.5E-10
3.4E-10
2 6E-10
1.5E-10
2.3E-10
24E-10
2.4E-10
2 8E-10
3 OE-10
Notes
All emissions testing was performed with a kiln temperature in the range 2,150-2.200°F
1 Measurements were taken of all dioxin and furan congeners containing four to eight chlorine substituents with
chlorines in the 2-, 3-, 7-, and 8-positions. the reported value represents the sum of these congeners
The tetra- through octa-chlonnated dioxin and furan congeners are expressed on the basis of toxicity equivalents
(TEQs); the reported value is derived by multiplying the measured emissions of each congener by its toxic
equivalency factor (TEF) and then summing the results.
Volume T
ITT-8
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TABLE III-2
Estimated Average and High-end Stack Emission Rates
for Dioxin and Furan Congeners
Congener
Emission Rate (g/s)
Average
High-end
Dioxin Congeners
2,3,7,8-TetraCDD
1,2,3,7,8-PemaCDD
1,2. 3,4,7, 8-HexaCDD
1,2,3,6,7.8-HexaCDD
1,2,3,7, 8,9-HexaCDD
1,2,3,4,6,7,8-HeptaCDD
OctaCDD
l.OSx 10"
6.78x 10'"
8.95 x 10-"
1.66x 10-'°
1.09x 10-'°
1.24x 10''
6.15 x 10-"
:.i6x iO"
9 46 x 10
1.25x 10 IP
2.18x 10'°
1.55x 10-'°
1.69x 10-'
9.80 x 10"
Furan Congeners
2,3,7,8-TetraCDF
1,2,3,7,8-PentaCDF
2,3,4,7,8-PentaCDF
1,2,3,4,7,8-HexaCDF
1,2,3,6,7, 8-HexaCDF
2, 3,4,6,7, 8-HexaCDF
1,2,3,7,8,9-HexaCDF
1,2, 3,4,6,7, 8-HeptaCDF
1,2, 3,4,7, 8.9-HeptaCDF
OctaCDF
877 x 10-"
3 45 x 10 10
4.67 x 10''°
1.43x 10-'
1.33x 10-'
l.SOx 10"
2.93 x 10-'°
9 30 x 10'9
1.22x 10"
1.89x 10'8
1 15 x 10 l'
4 35 x 10'"
6.04x 10"'
1 85 x 10'9
1 71 x 10"
1.96x 10"
3.85x lO'10
1.30x 10*
l.SOx 10-'
3.62 x ID'8
Notes:
CDD - chlorodibenzo-p-dioxin
CDF - chlorodibenzofuran
Volume T
TTT-Q
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TABLE III-3
Estimated Average and High-end Emission Rates for Products of Incomplete
Combustion (PICs) and Residues of Organic Compounds
Substance
Acenaphthene
Acenaphthylene
Acetaldehyde
Acetone
Aceiophenone
Acrylonitrile
Anthracene
Benzene
Benzoic acid
Benzotrichlonde
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Bis(2-chloroeihoxy (methane
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromoform
Bromomethane
Bromodiphenylether, p-
Butanone, 2-
Buty Ibenzy Iphihalate
Carbon disulfide
Carbon tetrachlonde
Chlordane
Chloro-3-methylphenol, 4-
Chloroanilme, p-
Chlorobenzene
Chlorobenzilate
Emission Rate (g/s)
Average
6.69 x 106
6.69 x 10"
3 01 x 10-4
2.90 x l
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TABLE III-3 (continued)
Estimated Average and High-end Emission Rates for Products of Incomplete
Combustion (PICs) and Residues of Organic Compounds
Substance
Chloroethane
Chloroform
Chloromethane
Chloronaphthalene, beta-
Chlorophenol, 2-
Chlorodiphenyl ether, 4-
Chrysene
Cresol, m-
Cresol, o-
Cresol, p-
Crotonaldehyde
Cumene
2,4-D
4,4'-DDE
Dibenz(a,h)anthracene
Dibenzo(a,h)fluoranthene
Dibromochloromethane
Dichlorobenzene, 1,2-
Dichlorobenzene, 1,3-
Dichlorobenzene, 1,4-
Dichlorobenzidine, 3,3'-
Dichlorobiphenyl
Dichlorodifluoromethane
Dichloroethane, 1,1-
Dichloroethane, 1.2-
Dichloroethene, 1,1-
Dichloroeihene, trans- 1,2-
Dichlorophenol, 2,4-
Dichloropropane, i,2-
Dichloropropene, cis-1,3-
DichJoropropene, trans- 1,3-
Diethylphthalate
Emission Rate (g/s)
Average
4 90 x 10 J
2.66 x 10-4
2.45 x 10^
6.69 x ID'6
5.50 x 10'6
6.69 x lO"6
5.50 x 10-6
5.50 x 10"
5.50 x 10 6
5.50x 10-"
1.39x 10J
5.50 x 10 6
3.88 x 10 5
5.50 x 10'
5.50 x 10'6
5.50x 10-'
2 63 x 105
5.50x 10'6
5.50 x 10"
5.50 x 10 -"
3.33 x 105
4.68 x 10-"
2.45 x 10"1
1.25x 10 5
1.25x 10 5
1.25 x 10s
1.25 x 10s
5.50x 106
1.25x 10 5
1.25x 10'5
1.25x 10s
1.69x 10 5
High-end
980x 10-
4.07 x 10"1
4.90 x 10-"
6.69 x 106
l.lOx 10 5
6.69 x 106
l.lOx 10'
l.lOx 10'
l.lOx 10'
1 10 x 10'
1.39x 10 J
l.lOx 105
3.88 x 10 -<
l.lOx 10"
l.lOx 10'
l.lOx 10 5
2.63 x 10 s
l.lOx 10'
l.lOx 105
l.lOx 10'
3.33 x 105
8.22 x 10'8
4.90x 10"
2.50x 10 5
2.50x 10'
2.50x 10'
2 50 x 10'
1 lOx 10'
2.50x 10'
2 50 x 10'
'i.SOx 10'
3.60 x 10 '
Source
b
b
b
a
b
a
b
b
h
b
a
b
a
b
b
b
a
b
b
b
a
b
b
b
b
b
b
h
b
b
b
b
Volume I
HI-1
-------
TABLE III-3 (continued)
Estimated Average and High-end Emission Rates for Products of Incomplete
Combustion (PICs) and Residues of Organic Compounds
Substance
Dimethoxybenzidine, 3,3'-
Dimethylphenol, 2,4-
Dimethylphthalate
Di-n-butylphthalate
Di-n-octyl phthalate
Dimtrotoluene, 2,6-
Dimtro-2-methylphenol, 4,6- -
Dinitrophenol, 2,4-
Dinurotoluene, 2,4-
Dioxane, 1,4-
Ethyl methacrylate
Ethylbenzene
Ethylene dibromide
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluorene
Formaldehyde
Furfural
Heptachlor
Heptachlorobiphenyl
Hexachlorobenzene
Hexachlorobiphenyl
Hexachlorobutadiene
Hexachlorocyclohexane, gamma- (Lindane)
Hexachlorocyclopentadiene
Hexachloroeihane
Hexachlorophene
Hexanone, 2-
Indeno(1.2,3-Ld)pyrene
Isophorone
Maleic hydrazide
Emission Rate (g/s)
Average
1.15 x 10-4
5 50 x 10"
5 50 x 10"
1 57 x 10"
5.50x 10°
5.50x lO'"
5.50 x 106
5.50 x lO'6
5.50 x 10-6
4.94 x 10-"
2.45 x 10-"
4.98 x 10-"
1 15 x 10-'
3.05 x 105
1.46x 10-'°
5.50 x 10-6
6 69 x 10-*
6.07 x 104
5 50 x 10-6
5 50 x 10 7
\ 40 x 10 *
5 50 x lO-6
1 40 x 10"
1.01 xiO"1
5.48x10-'
5.50 x lO'6
5.50 x 10'6
3.20x 10 5
6 43 x 10 5
5 50 x 10"
6 69 x 10'6
1.15 x lO'4
High-end
1 15 x lO'4
1 10 \ 10s
1 10 \ 10"
: 04 \ io"
1 10 x 10"
l.lOx 10'
l.lOx 105
l.lOx 10s
l.lOx 10"
4.94 x 10-4
4.90x 10-4
7.53 x 10-
1.15x ID'4
3.05 x 10'
1.46x 10 10
l.lOx 10s
6.69 x 10°
6.07 x 10'4
1 lOx 10'
1.10 x 10'"
2 80 x 10 h
l.lOx 10'
2.80x 10 8
1.01 x 10 4
5.48 x 10's
l.lOx 10 5
l.lOx 10s
3.20x 10s
6.43 x 10s
1 lOx 10'
6 69 x 10°
1 15 x lO'4
Source
a
h
h
h
h
b
b
b
b
a
b
b
a
a
a
b
a
a
h
h
h
b
b
a
a
b
b
a
a
b
a
a
Vnliimp T
TIM:
-------
TABLE III-3 (continued)
Estimated Average and High-end Emission Rates for Products of Incomplete
Combustion (PICs) and Residues of Organic Compounds
Substance
Methoxychlor
Methvlene chloride
Methylnaphthalene, 2-
Methyl-tert-butyl ether
Methyl-2-Pentanone, 4-
Monochlorobiphenyl
Naphthalene
Nitroanilme, 2-
Nitroanilme, 3-
Nitroanilme, 4-
Nitrobenzene
Nitrophenol, 2-
Nitrophenol, 4-
N-Nitroso-di-n-butylamme
N-Nitroso-di-n-propylamine
N-Nitrosodiphenylamine
Nonachlorobiphenyl
Octachlorobiphenyl
Pentachlorobenzene
Pentachlorobiphenyl
Pentachloronitrobenzene
Pentachlorophenol
Phenanthrene
Phenol
Pyrene
Safrole
Styrene
Tetrachlorobiphenyl
Tetrachloroethane, 1,1,1,2-
Tetrachloroethane, 1,1,2,2-
Tetrachloroethene
Tetrachlorophenol, 2,3,4,6-
Emission Rate (g/s)
Average
5.50 x 10 7
3.96 x 10-"
4.18x 10 5
1.25x 10s
1.25x 10 5
1.67 x 10-'
5.50 x 10-6
6.69 x 10°
6.69 x 106
6.69 x 10-*
5.50 x lO'6
6.69 x lO'"
5.50 x lO'6
1.21 x 10^
6.69 x 1C'6
6.69 x 10'6
1 40 x lO'8
1.40x 10-'
4.76 x 105
1.40x 10 8
3.37 x 105
5.50 x lO'6
6.69 x 106
5 50 x 10*
5.50x 10"
1.15 x 10-4
2.25 x 105
1.40x 10'8
5.50 x 10-6
5.50 x ID'6
5 13 x 10-'
6.80 x 10-"
High-end
l.lOx 10-°
6.19x 10-4
4.18x 10s
2.50 x 10-?
2.50x 10'
2.99x 10"
1 10 x 10'
6.69x 10"
6.69 x 10"
6.69 x 10"
l.lOx 10"
6.69 x 10 6
l.lOx 10'
1.21 x 10"4
6.69 x 10"
6 69 x 10 °
2.80 x 10-'
2.80 x 10"'
4.76 x 10 5
2.80 x 10*
3.37 x 10 '
l.lOx 10'
6.69 x 10 6
1 10 x 10'
l.lOx 10'
1.15x 10-"
4.04 x 10 5
2.80 x 108
l.lOx 105
l.lOx 105
8 '02 x 10 '
6.80 x 106
Source
b
b
a
b
b
b
b
a
a
a
h
a
b
a
a
a
b
b
a
b
a
b
a
b
h
a
b
b
b
b
b
a
Volume I
HI-13
-------
TABLE IH-3 (continued)
Estimated Average and High-end Emission Rates for Products of Incomplete
Combustion (PICs) and Residues of Organic Compounds
Substance
Toluene
Tnchloro- 1 ,2.2-mtluoroethane. 1,1.2-
Tnchlorobenzene. 1.2,4-
Tnchlorobiphenyl
Tnchloroethane, 1,1,1-
Trichloroethane, 1,1,2-
Trichloroethene
Tnchlorofluoromethane
Trichlorophenol, 2,4,5-
Tnchlorophenol. 2 4.6-
Vinyl acetate
Vinyl chloride
Xylene, m-1
Xylene, o-
Xylene, p>
Emission Rate (g/s)
Average
6.13 x 10""
3.30x 10"
5.50 x 10°
3.02 x lO'8
1.25x 10 !
1.25x 10 5
1.86x 10 5
2.45 x 10-"
5.50 x 10'6
5.50 x 106
6.43 x 105
2.45 x 10-"
3.80 x 10-"
j.50 x 10-"
3.80 x 10-"
High-end
1 0? x 10 '
? 30 \ 10-
1 10 x 10*
5 80 x 10'"
2.50x 10'
2.50x 10'
3.09x 10-
4.90 x 10'4
l.lOx 10-
l.lOx 10s
6.43 x 105
4.90 x 10-"
5.64x 10-
l.lOx 10 5
5.64 x 10-
Source
h
j
h
h
b
b
b
b
b
b
a
b
b
b
b
Notes
a - Emission rate based on March 1993 and February 1994 trial burn results and waste profile information
In these cases, the average and high-end estimates are the same because the estimation method used in
this process results in a high-end estimate, which was conservatively assumed to applv to ihe average
case as well
b - Emission rate based on August 1994 PIC testing results.
c - The emission rate for the mixed isomer "m/p-xylene" estimated from the August 1994 PIC testing is
conservatively assumed to apply to both m-xylene and p-xylene.
Volume T
TTT-14
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TABLE III-4
Estimated Average Metal Emission Rates
Metal
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Measured SRE
(percent)
NA (99.99932')
99.986
99.977
NA (99 977h)
99 9907
99.987
99.99932
NA (99.977h)
99.99
Ol
NA (99.977h)
99.68
NA (99.977")
NA (99.977h)
NA (99 977")
Feed Rate
(Ib/hr)
140
0.24
1.3
5 3
0.0028
096
0.83
3.2
3.4
0011
0.17
1.2
0.52
1.7
4.2
Feed Rate
(g/s)
18
0.030
0.16
0.67
0.00035
0.12
0.10
0.41
0.44
0.0014
0.022
0.15
0.065
0.15
0.54
Emission Rate
(g/s)
2.4 x 10 "
4.2 x 10°
3 7 x 10'
1 5 x 10 J
3 ? x 10"
i 6 \ iir
7 1 x 10"
94 x 10'
4.3 x 10'
1 4 x 10 '
5 0 x 10"
4 7 x 10 J
1 5 x 10s
3 4 x 10'
1.2x 10-4
Notes.
System removal efficiency (SRE) determined from March 1993 trial burn (ENSR 1993)
NA - not applicable; SRE not determined in March 1993 trial burn (ENSR 1993).
a - Estimated based on chromium SRE.
b - Estimated based on arsenic SRE
c - Assumed to be zero although very low, non-zero SRE was measured prior to installation of the ECIS
Volume I
III-15
-------
TABLE III-5
Estimated Average Acid Gas and Particulate Matter Emission Rates
Substance
Average Emission Rate
(g/s)
Hydrogen Chloride (HC!)
0032
Nitrogen Oxides (NO,)
Sulfur Oxides (SO,)
0.091
Paniculate Matter
0.07
Notes.
Paniculate matter emission rate based on measurements at WTI during trial burns and performance test.
HC1 emission rate based on measurements from the trial burns.
SO, and NO, emission rates based on one month of continuous stack monitoring data collected in 1995
Yoliimp T
TIT-
-------
TABLE UI-6
Estimated Average Concentrations of Metals and Inorganic Compounds
in Fugitive Fly Ash Emissions
Metal/Inorganic
Compound
Arsenic
Barium
Cadmium
Lead
Nickel
Selenium
Silver
Total Cvanide
Frequency
of
Detection
i i:
9 12
11/12
11/12
9/12
5/12
6/12
2/12
Concentration
Range
(mg/kg)
< 0 5 - 27 '
< 1 -4 1
< 0 1 - 640
<05 - 130
<0 15 - 1.9
<0 1 - 1.0
<0 1 - 2 1
< 0 5 - 1 1
Average
Concentration
(mg/kg) ^
3 4
1 7
71 0
36 1
07
0.2
0 3
04
Emission Rate
lg/s)
1 3" \ 10'
6 75 \ Hi"
2 86 v 10'
1 45 x 10'
292 \ 10
8 23 \ 10'
1 04 \ 10 "
1 41 x 10
Note
< - Lower end of concentration range is the lowest detection limit from samples in which analyte was not
detected above detection limit
Volume I
111-17
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O
cr
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u
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to
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o
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3
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IV. ATMOSPHERIC DISPERSION AND
DEPOSITION MODELING OF EMISSIONS
A. Overview
Atmospheric dispersion and deposition modeling is used to estimate off-site ambient
concentrations and to support the calculation of concentrations in soil, vegetation, livestock.
surface water, and fish. These concentrations are a starting point for estimating exposures KM
both the human health and ecological risk assessments.
The location of the WTI facility presents several challenges for atmospheric dispersion
modeling:
• Due to complex topography in the vicinity of the WTI facility, site-specific
meteorological measurements indicate strong channeling of winds at lower elevations
within the Ohio River Valley that are not present above the valley.
• The dispersion and buoyant rise of plumes released from short stacks may be
significantly modified by the presence of buildings or other obstacles to the flow. A
particular phenomenon, building-induced downwash, may result in increased
concentrations in the near-field.
• The Ohio River Valley has a high incidence of stagnation and inversion conditions.
On-site measurements indicate that calm conditions prevail locally in the valley
approximately 20 to 25 percent of the time. These conditions may potentially limit
dispersion and transport of facility emissions, and may result in the accumulation of
pollutants in the immediate vicinity of the facility.
• Under moderate-to-high wind conditions, terrain-induced downwash (contaminants
being drawn downward near the ground surface as air flows over an abrupt drop in
terrain elevation) may result in increased concentrations in the vicinity of the WTI
facility.
Vnlnmo T TV-1
-------
These complexities are evaluated in this assessment through (1) the development and
application of a refined atmospheric dispersion/deposition model (ISC-COMPDEP);
(2) performance of sensitivity tests using the advanced non-steady state models (CALPUFF
and INPUFF), and (3) in the case of terrain downwash. a separate wind runnel simulation of
conditions in the vicinity of the WTI facility.
B. Modeling Input Data
1. Source Data
Site-specific source and emission parameters are necessary inputs for the dispersion
modeling application. These parameters include physical stack dimensions such as stack
height, stack diametet, exit gas velocity and exit temperature. Table IV-1 lists the main
parameters for the incinerator stack. Source characteristics for fugitive emissions are
included in Table IV-2.
Particle size information used in the assessment is derived from stack test
measurements made during the March 1993 trial burn (U.S. EPA 1993). Using these
data, different types of size distributions of paniculate matter are characterized as follows
• Mass weighted distribution assumes that the pollutant is bound throughout the
volume of the emitted particles, such as non-volatile metals, and;
Surface area distribution assumes that the pollutant is distributed on the surface of
the particles.
2. ISC-COMPDEP Modeling
Atmospheric dispersion and deposition of routine stack and fugitive emissions from
the WTI facility was modeled using the Industrial Source Complex - Complex Terrain
Deposition (ISC-COMPDEP) model. This model was developed by U.S. EPA to provide
a more refined analysis of atmospheric dispersion and deposition of emissions from
sources located in complex terrain, such as the area surrounding the WTI facility. The
ISC-COMPDEP model incorporates features of the Industrial Source Complex-Short Term
model for simple terrain applications, and the COMPLEX I screening model for complex
terrain.2 The U.S. EPA recommended procedures on intermediate terrain are also
Terrain is considered "simple" if it does not rise above the height of the stack and "complex" if it rises above
the height of the stack. Intermediate terrain is a subset of complex terrain consisting of areas between stack
top elevation and plume height after consideration of plume rise.
-------
implemented in ISC-COMPDEP These consist of modeling receptors between stack top
elevation and plume height with both the simple and complex terrain models, and using
the larger of the two concentration estimates as being most representative. The ISC-
COMPDEP model includes the Schulman-Scire building downwash algorithm for short-
stack emissions in addition to the Huber-Snyder scheme, to adequately address building
downwash situations.
Meteorological data used in the air quality modeling include the following:
Observations of wind and temperature made at three sites on or near the WT1
property. Data are available for the time period April 1992 through March 199?
from two 10-meter towers and one 30-meter tower;
• Wind, temperature, precipitation, and turbulence measurements made at three
heights on a 500-foot Beaver Valley Power Station Meteorological Tower
(BVPSMT). The BVPSMT is located near Shippingsport, Pennsylvania.
approximately eight miles east of the WTI site; and
• Standard meteorological observations of wind, temperature, cloud cover, ceiling
height, and precipitation made by the National Weather Service at the Greater
Pittsburgh International Airport. The Pittsburgh Airport is located approximately
30 miles southeast of East Liverpool.
To reflect the differences in flow within the valley and at higher elevations, the ISC-
COMPDEP model has been modified to allow vertical profiles of winds and temperatures.
derived from the BVPSMT and WTI on-site towers, to be used in determining
atmospheric stability, pollutant transport, and dispersion. Data from the Pittsburgh
Airport are used when data are not available from WTI or BVPSMT. The vertical
temperature gradient data from BVPSMT are incorporated into the model to provide an
improved representation of stability conditions at plume height during stable atmospheric
conditions.
Site-specific information is also used to define terrain elevations and land use/land
cover. Terrain elevations, and land use/land cover data were derived from data obtained
from the U.S. Geological Survey (USGS).
In addition to modeling the atmospheric dispersion of routine/acility emissions, the
ISC-COMPDEP model is also used to predict the extent of paniculate matter deposition
onto soil, vegetation, and surface water. Both dry deposition of particles (due to
Volume I IV-3
-------
gravitational settling, inertial impaction. and Brownian diffusion) and wet deposition ot
particles (due to scavenging by precipitation) are evaluated using the ISC-COMPDEP
model
The dry deposition flux depends on the pollutant concentration in air and the
"deposition velocity." The deposition velocity for panicles is influenced by several
parameters, including the characteristics of the ground surface (such as surface roughness
and ground cover type), atmospheric variables (such as stability and turbulence levels in
the atmosphere), and pollutant characteristics (such as the size, shape and density of the
particles). Information on particle size, an important factor in determining the dry
deposition rate, is derived from the March 1993 trial burn for use in the Risk Assessment
The wet deposition, or scavenging, rate is computed from a scavenging coefficient
and the precipitation rate. The scavenging coefficient depends on the characteristics of the
pollutant (such as solubility and reactivity for gases, size distribution for particles), and
the nature of the precipitation (such as rain or snow). National Weather Service
meteorological stations typically report hourly precipitation codes describing the type of
precipitation; which are used in the ISC-COMPDEP modeling, along with local
measurements of precipitation amounts collected at the BVPSMT.
3. Non-Steady-State Modeling Using CALPUFF and INPUFF
At the WTI facility, approximately 22 percent of a representative one-year period was
determined to be calm for modeling purposes (i.e., wind speeds less than 1.0 m/s). The
location of the WTI facility within a well-defined river valley is conducive to the
development of strong nocturnal temperature inversions and light winds. A possible
diurnal pattern involves the accumulation of pollutants in the stable layer during nighttime
hours with poor dispersion conditions, followed by the breakup of the inversion during the
following morning. This can result in stack emissions from the previous night to be
mixed rapidly to the ground (fumigation)
Because ISC-COMPDEP is a steady-state Gaussian plume model, it is not specifically
designed to handle non-steady-state phenomena, such as calm conditions and plume
fumigation in valley situations. Thus, a non-steady-state model (CALPUFF) is applied in
the Risk Assessment as a sensitivity analysis to simulate a typical calm wind and plume
fumigation event, and assess the impact of such conditions on short-term and long-term
concentrations.
The peak one-hour, 24-hour, and annual average concentrations' predicted by
CALPUFF are similar in magnitude to the values predicted by ISC-COMPDEP. This
suggests that the inclusion of calm wind dispersion and fumigation does not have a
Volume I IV-4
-------
significant effect on the peak predicted concentrations from the WTI incinerator stack.
Additional sensitivity analyses performed using an alternative non-steady-state model
(INPUFF) support the general conclusions of the CALPUFF modeling.
4. Wind Tunnel Simulations
A series of wind runnel simulations were performed at U.S. EPA's Fluid Modeling
Facility to evaluate the potential tor terrain-induced downwash at the sue and to
characterize resulting peak ground level concentrations (Snyder 1994). To provide a
context for the findings of this study relative to the air quality modeling program.
ISC-COMPDEP simulations are performed that parallel the configuration studied in the
wind tunnel.
In the wind tunnel study, a 1:480 scale model was constructed to represent a full-scale
region approximately one mile wide by three miles long. The wind tunnel simulations
examined the terrain configurations for three separate stack heights under moderate to
high wind conditions. The findings of the wind tunnel study confirm that terrain-induced
downwash is expected to occur near the WTI site. However, the concentrations estimated
by the ISC-COMPDEP model are sufficiently conservative, and the changes in peak
concentrations attributed to terrain downwash on the basis of the wind tunnel simulations
are relatively minor, such that modifications to the ISC-COMPDEP modeling performed
for the WTI facility are not necessary.
5. Fugitive Emission Sources
Dispersion modeling of fugitive vapor and particulate matter emissions was performed
using ISC-COMPDEP. Source characteristics for fugitive emissions include the type of
source (point or volume) location of source, release height, and for point sources only,
stack diameter, temperature and exit velocity. Of the five fugitive emission sources
evaluated in the WTI Risk Assessment, ash handling, the carbon adsorption bed, and the
organic waste tank farm are evaluated as point sources, while the waste water tank and.
truck wash are evaluated as volume sources.
Fugitive emissions from the organic waste tank farm, carbon bed adsorption system,
waste water tank, and truck wash are in the vapor phase. Emissions from ash handling
are in the form of paniculate matter. For the purposes of the atmospheric dispersion
modeling, the particle size distribution for fugitive emissions from ash handling are
assumed to be the same as for the incinerator stack, since the size distribution data for
paniculate matter from the ash handling system are not available.
Volume I TV-5
-------
C. Results
A total of 13 sets of simulations of the main incinerator stack are conducted with ihe ISC-
COMPDEP model, corresponding to three different pollutant distributions:
• Vapor phase emissions;
• Mass-weighted pollutant distribution on particles; and
• Surface area-weighted pollutant distribution on particles.
Wet and dry deposition effects are computed for the distributions involving paniculate
matter. The results of the ISC-COMPDEP model simulations are presented in Table IV-3
The maximum annual concentrations in air under all three distributions are predicted to occur
at the same receptor location; located approximately one kilometer to the east of the
incinerator stack. The meteorological conditions and the elevation of the receptor suggest that
this is due to plume impaction on elevated terrain. Maximum deposition flux occurs at a
receptor located approximately 100 m to the east of the stack. Based on the ISC-COMPDEP
modeling, wet deposition is the primary deposition mechanism at this point.
The results of the fugitive emission modeling are presented in Table IV-4. Given the low
release heights for the fugitive emission sources, maximum chemical concentrations in air due
to fugitive emissions are generally in the immediate vicinity of the source. One exception is
the carbon adsorption bed system, which has a stack release height of approximately 90 feet.
As a result, the highest chemical concentrations in air due to fugitive emissions from the
carbon adsorption bed stack are several hundred feet from the source.
D. Uncertainties
Uncertainty associated with modeling the atmospheric transport and deposition of facility
emissions arise from: (1) limitations in the ability of the technical algorithms to accurately
represent local conditions at the WTI facility, and (2) limitations in the amount and quality of
data available for the modeling.
1. Uncertainties Associated with Limitations of the Technical Formulations
The principal sources of uncertainty associated with the use of the air dispersion and
deposition models used in this assessment are summarized as follows:
• Wet deposition - The wet deposition algorithm overpredicts deposition in the near
field because of a conservative estimate of the wet scavenging rate.
TV
-------
Complex terrain - Although the ISC-COMPDEP model has been modified to
allow for characterization of wind flow in complex terrain, the modeling
approach still represents a simplified approximation of actual flow fields In
addition, the steady-state plume modeling approach used in ISC-COMPDEP doe*.
not allow for the plume trajectory to deviate from a straight line
• Calm winds and fumigation - The ISC-COMPDEP model does not account tor
calm conditions or fumigation associated with inversion break-up events.
Application of two non-steady-state models (CALPUFF and INPUFF) to address
this uncertainty is discussed in Volume IV.
• Dry deposition - Comparisons of dry deposition velocity observations with model
predictions generally show a significant amount of scatter (e.g., U.S. EPA 1993).
The prediction of deposition velocities is a strong function of meteorological
variables and the size distribution of the pollutant, both of which represent
sources of uncertainty. The initial split of pollutants between the vapor and
particle phases and the significance of transformations between vapor and particle
phases during plume transport are also areas of uncertainty.
2. Uncertainties Associated with Data Limitations
Sources of uncertainty associated with limitations in the data used in the air dispersion
and deposition modeling include the following:
• Meteorological data - Steady-state plume modeling results in a significant
simplification of meteorological conditions in the valley. Furthermore,
meteorological data collected at the site are supplemented by measurements at
Shippingsport and Pittsburgh. However, with the focus on long-term average
concentrations and deposition fluxes, the errors associated with use of simplified
meteorological approximations is likely to be somewhat mitigated.
Panicle size distribution - Deposition of paniculate matter from the atmosphere is
strongly dependent on particle size distribution. Limitations in testing equipment
did not allow for characterization of the size distribution for very small (less than
0.4 micron) panicles, thereby contributing some uncertainty to the deposition
modeling results.
Volume I IV-7
-------
TABLE IV-1
Stack Parameters for the WTI Incinerator Stack
Parameter
Stack height
Stack diameter
Exit velocin
Exit gas temperature
Stack base elevation
Value
45.7 m
1.83m
17 74 m/s
367. OK
212.1 m
(150 fn
(6 tt)
(58 2 n s)
(201 °Fi
(696 tti
Volume I
TV-8
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TABLE IV-2
Source Characteristics for Fugitive Emission Sources
Point Sources
Description
Ash Handling
Organic Wastetank Farm
Vemtfl
Vent #2
Vem #3
Vent 04
Carbon Adsorption Bed
X*
(m)
23.89
173.47
193.12
199.30
17965
61 02
y*
(m)
48.98
10845
11690
102.31
93.99
42.83
Stack
Height
(m)
6.706
18.9
18.9
18.9
18.9 '
28.04
Temperature
no
310
310.
310
310
310.
250
Exit Velociu
(m/sl
0 1
0 1
0 1
0.1
0.1
31.05
Diameter
(ml
0 1
0 1
0 1
0 1
0 1
0.762
Volume Sources
Description
Open Wastewater Tank
Truck Wash
X'
(m)
177.06
100.16
Y*
(m)
204.76
170.91
Height
(m)
5.3
3048
Initial
o,
2.35
1 77
Initial
o.
4.96
2 84
Note
* Coordinates are relative to the origin (0.0, 0 0) located at main incinerator stack. Coordinates are oriented
relative to true north.
Volume I
IV-9
-------
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TABLE IV-4
Summary of WTI Modeling Results with ISC-COMPDEP
Fugitive Emission Sources
Annual Simulation (April 1, 1992 to March 31. 1993)
All Results Are Based on Unit Emission Rate (1 g/s or 1 g/nr/s)
Run No.
8c
9c
lOc
Ik
12c
Notes.
Fugitive Emission Source
Carbon Bed Adsorption
System (one stack)
Ash Handling
(one stack)
Open Wastewater Tank
(volume source)
Organic Wastetank Farm
(four stacks)
Truck Wash
Pollutant Distribution
Vapor
Vapor
PM — Mass
PM — Surface Area
Vapor
Vapor
Vapor
Maximum Annual
Concentration
3.801'(0 8km. 200°
148.97' (0 1 km, 50°)
148.71 (0.1 km, 50°)
148.32(0.1 km. 50°)
298.68* (0.3 km, 40°
143.56" (0 1 km. 40°)
288 70" (0.2 km. 40°
Based on an emission rate of 1 g/s.
Based on an emission rate of 1 g/s per stack (four stacks in run).
Volume I
IV-]
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V. HUMAN HEALTH RISK ASSESSMENT
A. Overview
The HHRA consists of a detailed, site-specific, multipathway assessment to characterize
the potential human health risks associated with routine emissions from the WTI faciliu The
HHRA combines information on the nature and magnitude of routine emissions from the WTI
facility, the results of the air dispersion and deposition modeling, toxicity data for the
constituents of primary concern in the facility emissions, and site-specific data for the
surrounding region and population. The foundation for this Risk Assessment is consistent with
well established chemical risk assessment principles and procedures developed for the
regulation of environmental contaminants (NRC 1983, OSTP 1985, U.S. EPA 1986a,b).
Application of these guidelines and principles provides a consistent process for evaluating and
documenting potential human health risks associated with potential exposures to incinerator
stack and fugitive emissions. As described by the National Research Council (NRC 1983), the
risk assessment process consists of the following four components:
• Hazard identification, which involves identifying the chemical substances of concern.
and compiling, reviewing and evaluating data relevant to toxic properties of these
substances.
• Dose-response evaluation, which involves assessing the relationship between dose and
response for each chemical of potential concern.
• Exposure assessment, which involves the identification of potential exposure
pathways, the fate and transport of chemicals in the environment (including dispersion
modeling), and the estimation of the magnitude of chemical exposure for the potential
exposure pathways.
• Risk characterization, which involves calculating numerical estimates of risks for each
substance through each route of exposure using the dose-response information and the
exposure estimates.
Volume T V-1
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In applying this four-step process, U.S. EPA guidance is relied upon in conjunction uuh
site-specific information to the extent possible. The general approach used in the HHRA
provides estimates of:
• Individual risks based on "central tendency" exposure within defined "subareas"
surrounding the facility, expressed both as averages across the subarea and at the
location of maximum chemical concentrations within each subarea.
• Risks to potentially more highly exposed or susceptible subgroups, such as young
children, within the general population.
• Risks associated with specific activities that may result in elevated exposures, such as
subsistence fishing.
• Individual risks based on "high-end" exposure to subgroups of the population that are
believed to be potentially more highly exposed. This accounts for potential
variabilities in exposure within an exposed subgroup.
• Cumulative risks to the population in the vicinity of the WTI incinerator, as a result
of stack emissions.
This approach allows for the estimation of risk to specific segments of the population,
taking into account site-specific activity patterns, the number of individuals in each subgroup,
and actual locations of individuals within these subgroups.
B. Selection of Chemicals for Evaluation in the Risk Assessment
1. Incinerator Stack Emissions
Approximately 200 chemicals are identified as potentially present in stack emissions.
Only a few of these compounds, however, have been measured in incinerator stack
emissions during performance tests and trial burns at the WTI facility. The human health
risks associated with direct inhalation exposure to each identified compound are
quantitatively evaluated in the HHRA. However, to focus the assessment of risks via
indirect pathways of exposure, a subset of the organic compounds Believed to contribute
most significantly to risk (referred to as "surrogate" chemicals) are selected for
-------
quantitative evaluation. Surrogate organic chemicals are selected based on the following
factors:
• Emission rate, as reflected by data collected during trial burns and performance
tests at the WTI facility and from the waste profiles:
• Toxicitv. considering both carcinogenic and noncarcinogenic effects, and
• Bioaccumulation potential, a measure of the extent to which a chemical is likeh
to accumulate in meat, milk, fish, and other components of the food chain and
thus contribute to risks through indirect pathways of exposure.
On this basis, a total of 32 organic compounds, shown in Table V-l, are selected as
surrogate chemicals for evaluating indirect exposures to incinerator stack emissions. Each
of the metals identified in stack emissions from the WTI facility is included in the
evaluation of indirect exposures.
2. Fugitive Emissions
For the assessment of routine fugitive vapor emissions, over 300 organic compounds
are identified in pumpable wastes received by the WTI facility. To focus this assessment.
surrogate chemicals are selected based on the following factors:
• Quantity. based on the total annual volume of a constituent received in the
pumpable feeds at the WTI facility;
• Toxicitv. considering both carcinogenic and noncarcinogenic effects; and
• Volatility, as a measure of the rate at which a chemical will volatilize from a
pumpable waste into the atmosphere.
On this basis, a total of 11 organic chemicals, shown on Table V-2, are identified as
surrogates for the quantitative evaluation of fugitive vapor emissions. For fugitive ash
emissions, cyanide and all seven metals detected in incinerator fly ash are selected for
evaluation.
Volume I V-3
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C. Toxicity Assessment
The toxicity assessment of the HHRA includes the first two steps of the general risk
assessment process: hazard identification and dose-response assessment. Consistent with U.S.
EPA guidance, potential carcinogenic and noncarcinogenic effects are evaluated separately.
Substances classified by U.S. EPA as potentially carcinogenic are assumed to pose a finite
cancer risk at all exposure levels. In evaluating potential cancer risks, therefore, a "no-
threshold" assumption is applied for all potential carcinogens.
The cancer slope factor (SF) (which is an upper-bound estimate of the likelihood that a
carcinogenic response will occur per unit intake of a chemical over a 70-year lifetime
exposure) is used as a measure of the potency of a chemical carcinogen. An SF value for a
chemical is derived by applying a mathematical model to extrapolate from the relatively high
doses administered to experimental animals (or, more rarely, experienced by people, typically
in the workplace) to the lower exposure levels expected for human contact in the environment
A number of models exist to extrapolate from high dose conditions to low dose conditions; the
approach used by U.S. EPA to develop SF values is the linearized multistage model, which is
generally believed to be conservative, i.e., is likely to overpredict the true potency of a
chemical.
In contrast to the approach used to evaluate carcinogenic effects, when considering
noncancer effects U.S. EPA generally assumes that a minimum threshold level of exposure
must be reached before the effect will occur. The estimated level of daily human exposure
below which it is unlikely that adverse effects will result is known as the reference dose (RfD).
In evaluating inhalation exposures, U.S. EPA has also developed reference concentration
(RfC) values to examine the noncarcinogenic effects of certain chemicals. RfD and RfC
values are typically derived from experimental animal studies, and incorporate uncertainty
factors to extrapolate from the high dose exposures in the animal experiments to the low doses
likely to be received by humans from environmental sources. These uncertainties include a
factor to account for individuals who are likely to be more susceptible than the general
population to the chemical.
The primary sources of SF, RfD, and RfC values used in the HHRA are, (1) the
Integrated Risk Information System (IRIS), an online data base maintained by U.S. EPA that
provides internally peer reviewed toxicity data for many commonly detected substances, and
(2) U.S. EPA's (1994f) Health Effects Assessment Summary Tables (HEAST), which include
information from the literature compiled for use in the Superfund program. For a few
chemicals, toxicity criteria were developed in consu'tation with U.S. EPA. For example, for
polychlorinated dioxins and furans (PCDD/PCDF), SF values were developed based on a
toxicity equivalency factor (TEF) approach (U.S. EPA 1994b), whereby the SF values for
Volume I V-4
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individual forms of PCDD/PCDF were established relative to 2,3.7.8-tetrachlorodibenzo-p-
dioxin (2,3.7,8-TCDD), which is believed to be the most toxic form of PCDD/PCDF. A TEF
approach (U.S. EPA 1993f) is also used to estimate SF values for several polycychc aromatic
hydrocarbons (PAHs), relative to benzo(a)pyrene For lead, a biokinetic modeling approach
developed by U.S. EPA (1990c) is utilized in the HHRA to relate lead exposures to blood lead
levels and the potential for adverse health effects.
D. Exposure Assessment
1. Identification of Population Subgroups and Exposure Pathways
The exposure assessment step of the Risk Assessment involves the identification of
potentially exposed populations, and the measurement or estimation of the magnitude of
exposure to individuals in the population. Within the exposed population, the magnitude
of exposure is expected to vary by individual due to differences in individual
characteristics and activity patterns, among other factors. Therefore, a distribution of
exposures across the population is expected to exist. Since direct measurement of this
exposure distribution can not be readily performed, subgroups within the population are
identified that are expected to have similar exposure because of similarities in activity and
behavior patterns. Based on the identified activity and behavior patterns in the vicinity ot
the WTI facility, the following subgroups are considered in the HHRA.
• Adult non-farming residents;
• Child non-farming residents;
• Adult farmers whose diet consists partially of homegrown food products; and
• Children of farmers whose diet consists partially of homegrown food products.
In addition to these subgroups, which are expected to comprise a significant portion
of the local population, exposure to three additional potentially exposed subgroups of the
population is estimated. Individuals in these subgroups may experience elevated
exposures to facility emissions due to specific behavior patterns:
• Children 7-12 years old who attend school in the area;
• Adult farmers whose entire diet is mainly homegrown (referred to as subsistence
farmers); and
• Children of subsistence farmers.
Volume I V-5
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The subgroups identified above are the primary focus of the HHRA. Additional
groups who may be highly exposed because of particular activity patterns are also
included in the HHRA to assess the potential risks associated with specific activities:
• Adults and children with home gardens;
• Breast-feeding infants;
Subsistence fishermen individuals who fish primarily for recreational purposes.
but obtain a significant portion of their diet from fish in local bodies of water.
and
• Deer hunters who hunt and consume deer from the area.
For incinerator emissions, exposure to individuals living and working in the vicinity
of the WTI facility is evaluated for both inhalation and indirect, multipathway routes of
exposure. The primary pathways of exposure considered in the HHRA for incinerator
stack emissions are:
• Inhalation of air;
• Ingestion of and dermal contact with soil;
• Consumption of meat, dairy products, and eggs from locally raised livestock;
• Consumption of locally grown vegetables; and
• Ingestion of and dermal contact with surface water during swimming.
To focus the WTI Risk Assessment, a study area within a 12-kilometer radius of the
facility is defined based on the highest risk pathway for the general population, and
divided into 12 subareas. Each subarea is designated by E, N, S, or W to reflect direction
from the stack, and 1, 2. or 3 to show relative distance from the stack.
The assessment of exposures to fugitive vapor emissions is limited to inhalation.
because of the volatile nature of the majority of the fugitive emissions, and the expected
localized impact. Thus, risks due to fugitive vapor emissions are evaluated for adult non-
farming residents, child non-farming residents, and children who attend school in the area.
Exposure to fugitive ash emissions is evaluated for inhalation, soil ingestion, soil dermal
contact, and vegetable consumption pathways. The populations and exposure pathways
considered in the HHRA are summarized in Table V-3.
Volume I
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2. Fate and Transport Modeling
As previously discussed in Chapter IV. the ISC-COMPDEP model is used in the
HHRA to evaluate atmospheric dispersion and deposition of both incinerator stack and
fugitive emissions. The results of the ISC-COMPDEP modeling are used to estimate
chemical concentrations in air associated with the routine emissions from the WT1 facilit).
and can be used directly to assess inhalation exposures. In addition, the results of the
dispersion and deposition modeling are used as the starting point for evaluating exposures
through indirect pathways. Indirect exposure occurs as a result of the wet and dr\
deposition of paniculate matter and vapor onto soil and vegetation, and subsequent
migration of these chemicals into other media. For example, stack constituents that are
deposited onto the soil can be incorporated into vegetation, which can then be ingested by
livestock. Vapor uptake into vegetation is another mechanism of chemical entry into the
food chain. Consequently, human exposure to site-related contaminants may occur
through ingestion of vegetables or livestock grown or raised locally.
In order to assess multipathway exposures, an estimate of chemical concentrations in
soil, vegetables, animal products (e.g., meat, eggs, milk, game), surface water, fish and
mothers' milk is needed. To predict chemical concentrations in these media, fate and
transport models based on U.S. EPA guidance (U.S. EPA 1990a, 1993b. 1994b) are
applied. Values used as input parameters in the fate and transport models are developed
based on site-specific data wherever possible; where such site-specific data are not
available, U.S. EPA-recommended default parameters are used.
3. Calculation of Dose
Human exposure to substances emitted during routine operations of the WTI facility
may occur as a result of inhalation, ingestion, or dermal contact. To estimate the
magnitude of the dose received through each of these routes of exposure, the
environmental media concentrations developed using the fate and transport models are
combined with exposure factors reflecting behavior and activity patterns. U.S. EPA
guidance recommends that such exposure estimates be presented using several descriptors
(U.S. EPA 1992c; 1995a). For example, the guidelines call for estimating the "high-end"
exposure, which is an estimate of the exposure of individuals in the upper end of the
population exposure distribution. Conceptually, U.S. EPA guidance defines high-end
exposure as within the upper 10% of the exposure distribution, but not higher than the
expected highest value in the true distribution of the population. The guidance also
recommends the development of "central tendency" exposure estimates to reflect exposure
Volume I V-7
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experienced by "typical" individuals in the exposed population (i.e., those approximate!)
at the median of the exposure distribution).
Various types of data are necessary to develop information on the exposure
distribution of the population. In the HHRA. the exposure distribution for the overall
population is estimated based on subgroups consisting of individuals expected to share the
same exposure characteristics. These subgroups can be characterized using site-specific
information concerning:
• The location of the exposure subgroups with respect to the WTI facility;
• Typical activity patterns for each subgroup; and
• The number of individuals that comprise each subgroup.
In order to fully develop an exposure distribution for a subgroup, detailed information
must be available regarding the activity and behavioral patterns of individuals in the
subgroup. Such information includes the percent of time spent performing different
activities at specific locations, estimates of dietary intake, sources of meat, milk, and
produce within the area, and the age and sex of individuals within the population. For
example, it is important to understand what fraction of food consumed locally is derived
from local sources rather than imported from remote locations.
In general, site-specific information and U.S. EPA guidance (U.S. EPA 1989, 1990b,
1992c) are relied upon in the HHRA to estimate the exposure factors. Typical exposures
for each subgroup are estimated by combining exposure factors believed to reflect typical
activity and behavior patterns with media concentrations developed using the fate and
transport models. The high end of the population exposure distribution includes highly
exposed subgroups within areas predicted to be more significantly impacted by facility
emissions Examples of the site-specific data compiled and used in the HHRA include the
following-
• To evaluate exposures from consuming locally grown fruits and vegetables, data
are compiled from an informal home gardening survey conducted in June 1993 by
the East Liverpool Board of Health. The data from the home gardening survey
provide a general indication of gardening practices in the East Liverpool area,
and are used to estimate the fraction of homes in the area surrounding the WTI
facility that have gardens, and the fraction of the residents' fruit and vegetable
diets that are homegrown.
-------
Potential exposures through mgestion of fish are estimated based on data derived
from a recreational fishing study performed as part of a joint Ohio/West Virginia
Department of Natural Resources Recreational Fishing Study (ODNR 1994a) and
an electro-fishing survey conducted by the Ohio River Valley Sanitation
Commission (ORSANCO). The data compiled by these studies provide an
indication of the amount of fishing that occurs in the vicinity of the WTI facilit)
and the average weight of fish.
To estimate exposures through consumption of locally produced milk and meat.
information regarding local farming practices was obtained from interviews with
local agricultural extension agents. The primary source of information on beef
farming statistics is agricultural data compiled by the Agricultural Statistics
Service associated with the Departments of Agriculture in Ohio, Pennsylvania
and West Virginia (ODA 1994; PDA 1994; WVDA 1994). Livestock data
include such parameters as the total number of cattle/calves in the state, the
number of calves born annually, and information on slaughter and marketing of
beef cattle and calves. A limited amount of data are also available from a 1992
survey of beef cattle and dairy farms performed for the Beaver Valley Nuclear
Power Station, located in Shippingsport, Pennsylvania. The general locations of
dairy farms in the area surrounding the WTI facility were obtained from the
Agricultural Marketing Service of USDA.
Exposure to hunters from consuming game derived locally is estimated using
information on deer hunting in the area surrounding the WTI facility provided by
the Departments of Natural Resources in Ohio, Pennsylvania, and West Virginia
(ODNR 1994b, PDNR 1994; WVDNR 1994).
To estimate overall population risks posed in the area, population data for the
three county area surrounding the WTI facility (Columbiana. Ohio. Beaver,
Pennsylvania; Hancock, West Virginia) are compiled from a summary of 1990
census data (CACI 1992). The county farming populations are estimated based
on the number of farms (USDC 1993a,b,c) and the typical household size (CACI
1992) in each county.
Volume I V 9
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E. Risk Characterization
The final step of the HHRA is risk characterization. In the risk characterization step.
chemical toxicity values are combined with the dose estimates for each of the exposure
pathways to evaluate both carcinogenic risks, and the potential for noncarcinogenic health
effects. The conclusions of the risk characterization in the HHRA are summarized below
1. Incinerator Stack Emissions
• PCDD/PCDF are identified as the primary constituents of concern in assessing
the potential risks to human health associated with WTI stack emissions.
• Exposures through the consumption of meat and eggs, dairy products, and
mothers' milk are determined to be the principal pathways of exposure to
constituents in the WTI stack emissions.
• The highest cancer risks are estimated in the nearest subarea to the east of the
facility, Subarea El. As shown in Table V-4, average cancer risks in Subarea El
for the identified subgroups range from 0.2 in 1,000,000 (2 x 10'7, for the adult
resident) to 1 in 1.000,000 (1 x 10'6, for the subsistence fanner adult and child).
Exposure to PCDD/PCDF accounts for most of the estimated risk. A sensitivity
analysis of the variability in exposure within the more highly exposed subgroup.
the subsistence farmer, was also conducted. This analysis identified food
ingestion rates and exposure duration as the most sensitive parameters in
estimating exposure for the subsistence farmer. The variability in exposure for
the subsistence farmer subgroup in Subarea El was assessed by recalculating
risks using values near the high end of the range for both food ingestion rates and
exposure duration. These changes result in high end cancer risks for the
subsistence farmer which are 7 in 1,000,000 (7 x 10"6), or approximately 7-fold
above the estimated average risk.
• In addition to the risks estimated for the subgroups listed in Table V-4, risks
were assessed for specific activities that may not be routinely performed by all of
the subgroups evaluated. These activities included consumption of homegrown
fruits and vegetables, subsistence fishing, consumption of venison derived
locally, and breast feeding. Breast feeding was estimated to account for the
highest potential incremental increase in risk. The estimated average cancer risk
Volume! V-10
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for breast-feeding infants of the subsistence farmer in Subarea El is
approximately 2 in 1,000.000 (2 x 10'0). PCDD/PCDF and benzo[a]pyrene
account for most of the estimated risk.
The highest noncancer Hazard Index (HI) values are also estimated in Subarea
El. As shown in Table V-4. estimated average HI values are below 1.0 for all
population subgroups. This indicates that noncancer health effects associated
with stack emissions are not anticipated.
For average exposures, the highest total (direct plus indirect pathway) noncancer
HI value is estimated to be for the child of the subsistence farmer, located in
Subarea El. This value is 0.07. The greatest contribution to this HI is from
direct inhalation, for which the estimated HI value is 0.05.
2. Fugitive Emissions
The average cancer risks from inhalation of fugitive organic vapor emissions are
estimated to be in the range of 0.5 in 1.000,000 (5 x 10'7) to 2 in 1.000.000
(2 x lO'6).
Average inhalation cancer risks associated with fugitive ash emission are
estimated to be below 0.05 in 1,000,000 (5 x 10'8). Indirect cancer risks
associated with exposure to fugitive ash emissions are significantly below 0.01 in
1,000,000(1 x 10-8).
The estimated average noncancer HI values associated with exposure to fugitive
organic vapors range from between 0.01 and 0.07. Since these values are
significantly below 1.0, noncancer health effects are not anticipated.
Average noncancer HI values associated with fugitive ash emissions are estimated
to be at least 1,000-fold less than 1.0, indicating that noncancer health effects are
not anticipated.
Volume I V-ll
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F. Uncertainties Associated with the HHRA
The primary sources of uncertainty associated with the HHRA are summarized as follows
• Toxicitv data - The assessment of the toxicity of several of the chemicals considered
in the HHRA is based on experimental animal data, which introduces uncertami> due
to differences in absorption, metabolism, excretion and toxic response between
humans and the animal species tested. However, U.S. EPA applies uncertainty
factors in extrapolating the animal data to humans that are designed to incorporate a
significant safety margin to ensure that the toxicity factors are adequately protective
of sensitive individuals in the population.
• Fate and transport models - The fate and transport models used to predict
environmental concentrations of substances emitted from the facility represent a
simplification of the processes that determine actual environmental concentrations.
Furthermore, input parameter values used in the models are often based on algorithms
derived from empirical correlations for a limited number of chemicals that may not be
directly applicable to all chemicals considered in the assessment.
• Estimation of exposure - Because site-specific data do not exist for many exposure
parameters, standard default values are often applied that may not accurately represent
the behavior patterns or actual locations of individuals living in the vicinity of the
WTI facility.
• Additivity of risks - In the HHRA, cancer risks and hazard quotients are summed for
all chemicals evaluated, as well as across all exposure pathways considered.
Uncertainty is introduced because the mechanism of toxicity and weight-of-evidence
are not considered in this process. In addition, additivity may not apply to
noncarcinogens that do not affect the same target organ. Finally, mechanisms
governing antagonistic or synergistic responses are not well understood, so that the
cumulative risk from multiple chemical exposures is not well defined.
Volume T V-1
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TABLE V-l
Surrogate Chemicals Selected for the
Indirect Risk Assessment of Stack Emissions
PICs and Residual Organic Compounds (15)
Bis(2-ethylhexyl)phthalate Benzo(b)fluoranthene Heptachlorobiphenyl
Carbon tetrachlonde Benzo(a)pyrene Hexachlorobiphenyl
Di(n)octyl phthalate Dibenz(a.h)anthracene Tetrachlorobiphenyl
Heptachlor Indeno(1.2 ?-cd)pyrene
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclopemadiene
Hexachlorophene
Dioxin Congeners (7)
Furan Congeners (10)
2,3.7,8-TCDD
1,2.3,7,8-PeCDD
1,2,3,4.7.8-HxCDD
1,2,3,6,7,8-HxCDD
1,2,3.7,8,9-HxCDD
1,2,3.4.6,7.8-HpCDD
OCDD
2,3,7,8-TCDF 1.2.3.7,8.9-HxCDF
1,2,3,7,8-PeCDF 2,3,4,6,7.8-HxCDF
2,3,4,7,8-PeCDF 1,2,3,4.6,7.8-HpCDF
1.2,3.4,7,8-HxCDF 1,2,3,4,7.8,9-HpCDF
1.2,3,6,7,8-HxCDF OCDF
Metals (13)
Antimony Chromium (hexavalent) Silver
Arsenic Lead Thallium
Barium Mercury1 Zinc
Beryllium Nickel
Cadmium Selenium
Notes
* - Includes methylmercury in aquatic environments
CDD - cnlorodibenzo-p-dioxin
CDF - chlorodibenzofuran
Volume I V-i:
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TABLE V-2
Surrogate Chemicals Selected for the Assessment of
Fugitive Organic Vapor Emissions
Acetone Dichlorodifluoromethane
Acrylonitrile 1,1-Dichloroethene
Carbon Disulfide Formaldehyde
Carbon Tetrachloride Hydrazine
Dibromomethane 2-Nitropropane
Pyndine
Volume I V-14
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TABLE Y-4
Estimated Area Average Cancer Risks and Hazard Indices
Due to Exposure from Direct and Indirect Pathways in Subarea El
Population Subgroup
Resident Adult
Resident Child
Farmer Adult
Farmer Child
School-Age Child
Subsistence Farmer Aduh
Subsistence Farmer Child
Cancer Risks
2 x 107
4 x ID'7
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6 x ID'7
3 x 10-7
1 x 10-6
1 x 10-6
Hazard Indices
1 x 10:
5 x 10-2
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3 x 102
2 x ID'2
7 x ID'2
Volume I
V-16
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VI. SCREENING ECOLOGICAL RISK ASSESSMENT
A. Overview
The Risk Assessment for the WTI facility includes a Screening Ecological Risk
Assessment (SERA) to provide an initial evaluation of potential risks to ecological receptors
that may be directly exposed to, or indirectly affected by, stack and fugitive emissions trom
the WTI facility. The assessment is consistent with the general approach outlined by U.S.
EPA (1992d), and its screening-level nature is consistent with U.S. EPA Region 5 draft
Ecological Risk Assessment Guidance for RCRA Corrective Action (U.S. EPA 1994e), which
describes a tiered approach to evaluating risks to ecological receptors. U.S. EPA (1992d)
states that an ecological risk assessment at the screening level "may be performed using readily
available data and conservative assumptions; depending upon the results, more data then may
be collected to support a more rigorous assessment." The primary goals of the SERA are as
follows
• To identify and eliminate from further consideration those Ecological Chemicals of
Concern (ECOCs), exposure pathway, and ecological receptor combinations for
which potential risks are negligible;
• Where potentially significant risks are identified, provide direction regarding further
evaluations in the ecological risk assessment process; and
• Evaluate the presence of federal- and state-listed rare, threatened, and endangered •
species in the vicinity of the facility and the likelihood that they would be exposed to
facility-related ECOCs.
Ecological risk assessment involves the same general methodologies as human health risk
assessment. As in a human health risk assessment, the ecological risk assessment integrates
exposure and toxicity. the two fundamental factors in assessing potential risks. However.
there are also key differences. Unlike a human health risk assessment, an ecological
assessment must often consider risks to a diverse community comprising multiple species
Volume I VII
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Different types of plants and animals (including mammals, birds, reptiles, amphibians, and
fish) with different habitats, exposures and toxicological susceptibilities, must be evaluated
both individually and collectively, resulting in a greater overall degree of complexity than in a
human health risk assessment. Further, ecotoxicological data are not available for a number of
species and chemical constituents. Ecological risk assessments are therefore usualh qualitative
or semi-quantitative, especially at the screening level.
In evaluating receptors and exposure pathways, the SERA considers habitats and biota in
the vicinity of the WTI facility having the greatest potential for exposure to incinerator stack
and fugitive emissions. The assessment area for the SERA is defined as the area within a 20-
kilometer radial distance of the WTI facility, encompassing a 1,260 square kilometer (km2)
area. The typical biota present in the assessment area are identified and representative species
or species groups are selecied as indicator species for use in the SERA. Because of
differences in goals and approaches, the SERA assessment area, which is intended to include
habitats and species of greatest exposure potential, is not the same as the "study" area in the
HHRA.
Conservative assumptions, designed to overestimate rather than underestimate potential
exposures and risks, are used to select ECOCs, exposure pathways, and indicator species, and
to determine whether potentially significant ecological risks may occur from routine facility
emissions. Any potentially significant risks identified in the SERA could be evaluated further
in subsequent phases of the risk assessment process.
B. Selection of ECOCs
1. Incinerator Stack Emissions
There is currently no single established approach for ranking or selecting surrogate
chemicals for ecological risk assessments. Various approaches have been described and
compared in the literature and discussed at professional work shops (U.S. EPA 1980,
1994d; Davis et al. 1994; SETAC 1995). In general, these approaches consider chemical
release or contaminant levels, inherent toxicity, bioaccumulation potential, and, to a lesser
extent, persistence as ranking criteria to select surrogate chemicals for risk evaluation In
developing a list of ECOCs for the SERA, the focus is on organic chemicals and metals
Two other categories of chemical emissions, acid gases and particulate matter, are
excluded as ECOCs because they are judged to pose a much lower potential risk than
organic chemicals and metals to ecological receptors. All 15 metals for which emission
estimates are developed are selected as ECOCs. These metals are shown in Table VI-1.
However, as in the HHRA, a subset of surrogate organic chemicals of primary concern
Volume I VI 2
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are selected as ECOCs, due to the large number of organic constituents potentially present
in WTI incinerator stack emissions. The screening of organic chemicals to select ECOCs
is conducted in three parts:
Evaluation based on major exposure type;
Evaluation based on chemical group; and
Evaluation based on professional judgement.
The exposure and chemical group analyses utilize a scoring algorithm consisting of
the following factors: .
• Emission rate, based on high-end emission rate estimates, as discussed in Chapter
III;
• Toxicity. based on available toxicological data for terrestrial animals and/or
aquatic organisms, depending on the exposure type and/or chemical group
evaluated; and
• Bioaccumulation potential, as represented by the octanol/water partition
coefficient (Kow).
After selecting organic chemicals based on the scoring algorithm, additional chemicals
are added as ECOCs based on professional judgement. Chemical persistence is
considered in this step. For example, polychlorinated biphenyls (PCBs), which are not
selected as an ECOC based on the scoring algorithm but which are known to persist and
to bioaccumulate in the food chain, are included in the risk analysis.
Based on this evaluation, 22 organic compounds (or groups of compounds such as
PCBs) are selected as ECOCs for evaluating WTI incinerator stack emissions in the
SERA. These chemicals are shown in Table VI-2.
2. Fugitive Emissions
In selecting ECOCs for fugitive organic vapor emissions, different (but functionally
equivalent) scoring algorithms than the ones developed for incinerator stack emissions are
used. Since the constituents present in fugitive organic vapor emissions are anticipated to
Volume I VI-3
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be primarily volatile chemicals with relatively low bioaccumulation potential, organic
ECOCs are selected based on the following criteria.
• Quantity released, taking into account the volume of the chemical present in the
pumpable waste feeds, and the vapor pressure of the constituent;
• Water solubility, calculated from log Kow values: and
• Toxicity to terrestrial animals (via inhalation) and/or aquatic organisms (via
surface water exposures).
The scoring algorithm js supplemented with consideration of persistence and
bioaccumulation. Based on this process, eight chemicals are selected as fugitive organic vapor
ECOCs. These compounds are acetone, acetonitrile, acrylonitrile, chloroform.
dimethylamine, dimethylhydrazine, formaldehyde, and hydrazine.
As in the HHRA, metals detected in at least one fly ash sample are selected as ECOCs for
evaluating fugitive inorganic emissions from the ash handling facility. Thus, seven metals
(arsenic, barium, cadmium, lead, nickel, selenium, silver) and total cyanide are evaluated in
the SERA for this emission source.
C. Characterization of Exposure
A total of five scenarios are considered in evaluating exposures to incinerator stack and
fugitive emissions in the SERA. Three exposure scenarios are evaluated for incinerator stack
emissions and two exposure scenarios are evaluated for fugitive emissions.
Two exposure scenarios are evaluated for metal ECOCs in incinerator stack emissions.
The first scenario involves an evaluation based on expected annual average metal emission
rates, assuming the facility operates at full capacity. This scenario, termed the stack expected
metal scenario, uses the same emission rates as those used in the HHRA. The second scenario
for stack metal ECOCs involves an assumption that the incinerator is operating continuously at
its projected maximum permitted metal emissions limits. This is termed the stack projected
permit limit metal scenario. The metal permit limits are based on maximum hourly, rather
than annual average, emissions and thus this scenario represents an "upper-limit" for metal
emissions from the incinerator stack. A comparison of the metal emission rates included in
these two exposure scenarios is presented in Table VI-1. ''
A single exposure scenario based on high-end emission rates (i.e., 95% upper confidence
limit values) is evaluated for organic ECOC stack emissions. In contrast, the HHRA relied
Volume I VI-4
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primarily on average emission rate estimates for organics, with the high-end rates applied in
the HHRA in a sensitivity analysis. The added conservatism of using high-end emission rates
in the SERA is consistent with its being a screening-level assessment. The stack emission
rates used in the SERA for organic constituents are presented in Table VI-2
Two exposure scenarios are used to evaluate fugitive emissions The fugitive morgana
scenario evaluates emissions of inorganic (metals and total cyanide) constituents from the ash
handling facility while the fugitive organic scenario evaluates emissions of volatile organic
constituents from four potential sources within the facility boundary. Potential ecological
exposures are evaluated at the point of maximum air concentration for each of the five fugitive
sources (four vapor and one ash). The emission rates used in the SERA for the fugitive
inorganic and fugitive organic scenarios are presented in Tables VI-3 and VI-4, respectively
For the fugitive inorganic exposure scenario, predicted maximum concentrations of the
ECOCs in air. surface soil, surface water, and sediment are used in the SERA as exposure
point concentrations. These environmental media concentrations are evaluated at the projected
locations of maximum air concentrations, at the potential locations of maximum deposition
onto soil and vegetation, and at representative water bodies within 10 kilometers of the
facility. The fate and transport models used in the HHRA are also applied in predicting
chemical concentrations in the SERA. Tissue concentrations in representative food items are
modeled to evaluate potential food chain effects in upper trophic level wildlife receptors for a
subset of the ECOCs.
Exposure concentrations for fugitive organic vapor emissions are assessed only for the air.
surface water, and sediment pathways, given the volatile, water soluble, and non-
bioaccumulative nature of the constituents in these fugitive releases. As a conservative
measure, maximum concentrations for a particular ECOC are summed for all fugitive sources,
as well as for contributions from incinerator stack emissions. This provides a conservative
estimate of exposure because the modeled locations of maximum concentrations are not the
same for all fugitive sources and for the incinerator stack.
Exposure routes and pathways for the ecological receptors to chemicals in the different
environmental media are shown in Figures VI-1 and VI-2 for incinerator stack and fugitive
emissions, respectively. As indicated in the two figures, terrestrial animals may be exposed to
chemicals through the following exposure routes: (1) direct inhalation of vapor-phase
chemicals, or of chemicals adsorbed to paniculate matter; (2) direct ingestion of soil and
sediment; and (3) consumption of vegetation and/or animal tissues containing chemicals which
have entered the food chain.
Terrestrial and emergent wetland plants may be exposed to airborne chemicals via
absorption of vapor phase chemicals through leaf surfaces or absorption of chemicals deposited
Volume I VI-5
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by air or water onto leaf surfaces. In addition, plants may be exposed through their root
surfaces during water and nutrient uptake to chemicals deposited onto soil and sediment.
Aquatic animals may be exposed by direct contact with chemicals in water and sediments, or
by dietary consumption through the food chain.
D. Selection of Indicator Species
Because of the complexity of the ecosystem surrounding the WTI facility, it is not possible
to assess potential adverse effects to all ecological receptors within the assessment area
Therefore, "indicator" species are selected to evaluate potential risks to the broader ecological
community. The objective of the indicator species selection process is to identify species
which: (1) are known to occur, or are likely to occur, within the assessment area; (2)
represent a reasonable range of potentially exposed taxonomic groups or life history traits in
the habitats present; and (3) have sufficient toxicological information available on which to
base an evaluation. On this basis, and considering the potential exposure routes and pathways
shown in Figures VI-1 and VI-2, the following indicator species or species groups are selected
for evaluation in the SERA:
• Terrestrial plants;
• Soil fauna (primarily earthworms);
• Meadow vole;
• Northern short-tailed shrew;
• American robin;
• Red fox.
• Mink;
• Red-tailed hawk;
• Belted kingfisher; and
• Aquatic biota (plants, invertebrates, and fish).
No recent occurrences of rare, threatened, or endangered species are known within a
1-kilometer radius of the WTI facility. The closest recent occurrences of rare, threatened, or
endangered species (two state-listed fish species) occur approximately four kilometers
southwest of the facility in the Ohio River.
Volume I Vl-fi
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E. Characterization of Effects
In assessing potential adverse effects to indicator species, chronic lexicological benchmark
values were derived from the literature for each terrestrial and semi-aquatic indicator species
No-Observed-Adverse-Effect-Levels (NOAELs) based on growth and reproductive endpomts
were obtained, when available. Growth and reproduction are emphasized as lexicological
endpoints because they are the most relevant, ecologically, to maintaining viable populations.
and because they are generally the most studied chronic endpoints for ecological receptors
Where chronic NOAEL values are not available, estimates are derived from chronic Lov%est-
Observed-Ad verse-Effect-Levels (LOAELs), or acute thresholds, using appropriate uncertainty
factors.
For aquatic biota, U.S. EPA Ambient Water Quality Criteria (AWQC) for the protection
of aquatic life are used to evaluate potential adverse effects in surface water. Comparable
Ohio, West Virginia, and.Pennsylvania water quality criteria are used to supplement the U.S.
EPA AWQC values. Benchmark values for aquatic biota exposed to chemicals in sediments
are based on published criteria and guideline values, or derived from data in the literature
F. Risk Characterization
In the SERA, risk is characterized by calculating a hazard quotient. The hazard quotient
is calculated by dividing the estimated exposure concentration or dose by the appropriate
toxicological benchmark value. Hazard quotients exceeding one indicate the potential for risk
(the magnitude indicating the relative magnitude of the risk) and hazard quotients of one or
less indicate that risks are low to negligible. In the SERA, the lowest available toxicological
benchmark values (based on NOAELs) are used along with upper-bound exposure estimates to
calculate hazard quotient values; this is intended to ensure that potential risks are not
underestimated.
The conclusions of the risk characterization phase of the SERA are summarized as
follows:
For metal emissions from the incinerator stack under the stack expected metal
scenario, low to negligible ecological risks are indicated.
• For organic emissions from the incinerator stack, low to negligible ecological risks
are indicated.
i •
For metals in fugitive inorganic emissions from the ash handling facility, low to
negligible ecological risks are indicated.
Volume I VI-7
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• For fugitive organic vapor emissions, except for formaldehyde, low to negligible
ecological risks are indicated. For formaldehyde, risks of relatively low magnitude
are indicated for wildlife from inhalation exposure.
• For metal emissions from the incinerator stack under the stack projected permit limit
metal scenario, risks of relatively high magnitude are indicated for terrestrial plants
and animals from exposure to six metal ECOCs (barium, mercury, nickel, selenium.
silver, and thallium). The largest exceedances of toxicological benchmark values
occur for thallium, selenium, barium, and nickel. A relatively low magnitude risk is
indicated for aquatic biota for one metal (silver).
In summary, the SERA indicates low to negligible ecological risks for routine emissions
of organic chemicals (except formaldehyde in fugitive emissions) and for expected emissions
of metals from the stack and the ash handling facility. Formaldehyde exposure levels
exceeding inhalation benchmarks are limited to habitats in or immediately adjacent to the
facility. It is expected that wildlife exposures will be limited at these locations (due to habitat
considerations) and that adverse effects to wildlife populations and community structure would
be unlikely.
The results of the stack projected permit limit metal scenario indicate that the magnitude
of the predicted risks is relatively high for both plant and animal terrestrial indicator species at
the projected points of maximum air concentrations and total stack deposition. A key issue
relating to the stack projected permit limit metal scenario is the degree of realism in the
emission rate estimates based on the maximum permitted hourly emission levels. For this
scenario, it was assumed that the incinerator emits metals continuously (on an annual basis) at
the maximum hourly permitted levels. Although this level of emission is considered very
unlikely, it is theoretically and legally possible. Furthermore, for several metals, including
those for which hazard quotient values were calculated to exceed one, removal efficiencies
were assumed to be zero.
If the metal emission rates assumed in the projected permit limit scenario were to be
reached over an extended period, the magnitude of the predicted risks (even considering the
conservative nature of the assessment) suggests that adverse effects to terrestrial plant and
animal species are likely. Given the areal extent over which some of these predicted risks
extend, adverse effects are possible to some wildlife populations and possibly to the terrestrial
plant community. Quantifying the degree of likelihood and the extent of these potential effects
for the indicator species, metals, and exposure pathways for which risk is predicted would
require additional evaluation at the PERA or DERA level. The implications of such high
Volume I VT-8
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metal exposures for rare, threatened, and endangered species that may inhabit the assessment
area would have to be determined from a biological assessment (not a PERA or DERA).
However, this scenario does not reflect emissions expected during routine operations The
results of the SERA indicate that routine operations at the WTI facility would not present a
significant risk to ecological receptors and that additional analyses (PERA or DERA) are not
warranted.
G. Uncertainties
There are various sources of uncertainty in the SERA; they are basically of two types.
There are uncertainties inherent in screening-level ecological risk assessment, and there are
others related to the particular estimation parameters and assumptions used in this SERA to
establish exposure concentrations (or doses) and toxicological benchmarks. With regard to the
first type of uncertainty, the SERA is consistent with the state-of-the-science methodology for
screening-level assessments, which is designed to be a conservative or protective approach
given the constraints of the science and of the available information. Decisions are made in
the problem formulation step regarding how to select ECOCs, exposure pathways, receptors.
and a risk characterization methodology for this assessment.
The second type of uncertainty involves the values chosen from among the available site-
specific data, assessment guidelines, and scientific literature as input parameters in deriving
estimates of emission rates, dispersion factors, deposition rates, contact rates, uptake rates,
ecotoxicological endpoints, and uncertainty factors. Values are chosen in an attempt to
generally model upper-bound exposures and lower-bound toxicological benchmarks such that
risks are not underestimated
The SERA meets the objective of separating those ECOCs, exposure pathways, and
receptors that clearly do not pose a significant contribution to overall risk, but without
underestimating risks for receptors that might be more highly exposed or susceptible. It is
very likely that risks are overestimated in some cases because of the conservative assumptions
Volume I VI-9
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TABLE VI-1
Metals Evaluated in the SERA - Stack Emissions
Chemical
Aluminum
Antimom
Arsemc
Barium
Beryllium
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
"Permit Limit"
Emission Rate
(g/s)
...
1 6 x 10'4
1 1 x !(T
5 5 x 10'
3.6x 10"
1.9 x 10"
1.5 x HT1
—
1.2x 10°
8.8 x 10'2
2.2 x 10'
4 4x10°
3.3x 10°
5.5x 10-'
—
"Expected" Emission
Rate
(g/s)
24 \ l(l~
4 2\ 10'
? 7 \ 10"
1 5 \ 1(1-
3 3 x 10 f
1.6x 10'
7.1 x 10"
94x 10 5
4.3 x 10'
1 4 x 10 '
5.0 x 10"
4.7x 10J
1.5 x W
3 4 x 10s
1 2 x 104
Volume T
VT-in
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TABLE VI-2
Organics Evaluated in the SERA-
Stack Emissions
Chemical
Acetone
Acrylonitnle
Anthracene
Benzo(a)pyrene
Bis(2-ethylhexyl)phthalate
Chloroform
Crotonaldehyde
2,4-D
4,4'-DDE
Di-n-ocryl phthalate
1,4-Dioxane
Dioxin/furan
Formaldehyde
Heptachlor
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclopentadiene
Hexachlorophene
Pemachlorobenzene
Pentachlorophenol
Total PCBs
Vinyl chloride
High-End Emission Rate
(g/s)
2.90 x 10 "'
2.02 x 1CT
l.lOx 10'
1 10 x 10'
5.23 x 10'
4.07 x 104
1 39 x 10"
3.88 x 10'
1.10 x 10-"
1 10 x 10s
4.94 x 10'4
1.26x 10"
6 07 x 10-
l.lOx 10-6
1.10 x 10s
1.01 x 10-
l.lOx 10 5
3 20 x 10s
4 76 x 10 5
1 10 x 10'
3 38 x 10^
4 90 x 10"
Volume I
VI-11
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TABLE VI-3
Estimated Emission Rates for Metals and Total Cyanide in Fugitive Fly Ash
Chemical
Arsenic
Barium
Cadmium
Lead
Nickel
Selenium
Silver
Total Cvanide
High-End Emission Rate
(g/s)
3 31 x 10"
9 11 \ 10"
6.63 x 10'
2.17 x 10'
4.22 x 10 7
1.48x 10'7
2.34 x 107
2.61 x lO'7
Volume T
VI
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TABLE VI-4
Estimated Emission Rates - Fugitive Organic Vapor Emissions
Chemical
Acetone
Acetonitnle
Acrylonitnle
Chloroform
Dimethylamine
Dimethylhydrazine
Formaldehyde
Hydrazine
Emission Rate (g/s)
Carbon
Absorption
Bed
1.18x 10'3
3.19 x 10'5
2.71 x 10'5
7.94 x 10'5
3.00 x 10-4
2.28 x lO'5
6.74 x 10-4
1.72x 10-6
Tank
Farm
1.12 x 10 2
3.03 x 10-4
2.57 x 10-4
7.52 x 10-4
2.84 x 10-3
2.16x IQ-4
6.39 x 10-3
1.63 x 10-5
Open Waste
Water Tank
1.06x 10 3
2.88 x 10"'
2 44 x 10-s
7.15x 10'-
2.70 x 10-4
2.05 x 105
6.07 x 10-4
1.55x 10-6
Truck
Wash
5.19 x 10"'
1.41 x 1(T
1 19 x 10°
3.50 x 10"
1.32 x 10'
1.01 x 10(1
2.98 x 10"
7.58 x lO'8
Volume I
VI-13
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VII. ACCIDENT ANALYSIS
A. Overview
The WTI Risk Assessment includes an analysis of potential human health effects
associated with accidents that might occur during operation of the WTI facility. The approach
for conducting this analysis has been developed based on guidance published by U.S. EPA
(e.g., U.S. EPA 1987; 1996) and other agencies such as the U.S. Federal Emergency
Management Agency (FEMA 1993). The primary objective of the Accident Analysis is to
assess the potential for human health effects associated with general types or classes of
accidents that could occur at the WTI facility. The results of this type of analysis typically
provide information that can be used to reduce the likelihood, extent and impact of possible
accidents.
The Accident Analysis evaluates the potential impact distance for specific accident events
based on acute health effects associated with short-term (i.e., less than 24-hour) exposures. Of
primary interest in the Accident Analysis is the potential for health effects associated with
events that could have significant short-term off-site consequences, but which generally do not
have a high probability of occurring. In addition to these conservative scenarios, more typical
events with a greater likelihood of occurrence but lower potential consequences are also
examined. For both conservative and typical accident scenarios, a range of meteorological
conditions (including atmospheric inversions) are ewluated, and the effect of emergency
response measures is assessed.
Both on-site and off-site accidents are included in the Accident Analysis. For the on-site
accident scenarios, the off-site distance over which human health effects might be anticipated
is estimated; for the off-site accident scenarios, the distance over which health effects may
occur along local access routes to the facility is identified. In determining the distance over
which effects may occur, inhalation is evaluated as the primary route of short-term exposure
for the off-site community. While direct dermal exposure may also be of concern in some
accident scenarios, exposures through inhalation could occur over a larger area, and would be
more likely to result in adverse health effects.
Given that the focus of the Accident Analysis is the adequacy of existing design and
operation features in protecting the off-site community, risks to on-site workers are not
Volume I VII-1
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evaluated. Furthermore, ecological assessments typically focus on risks to ecological
communities rather than risks to individual receptors. Since most plausible accident scenarios
would affect relatively small areas, and are therefore unlikely to affect entire ecological
communities, potential ecological risks associated with facility accidents are not considered
Many different types of events, or combinations of events, could lead to the general
classes of accidents evaluated in the Accident Analysis. Thus, a rigorous evaluation of the
causes of specific accident scenarios is not performed. Instead, probabilities for occurrence of
the various classes of accident events considered are estimated using the semi-quantitative
methods presented in Technical Guidance for Hazards Analysis by U.S. EPA (1987). and the
Handbook of Chemical Hazard Analysis Procedures by FEMA (1993). This approach is
consistent with U.S. EPA's proposed rule for Accidental Release Prevention Requirements
(U.S. EPA 1995c).
B. History of Accidents Reported at U.S. Commercial Incineration Facilities
The U.S. EPA (1995b) has compiled a review of reported emergency incidents at
hazardous waste incinerators and commercial treatment, storage, and disposal facilities
regulated under RCRA. Descriptions are provided for incidents reported to have occurred
between 1977 and May 1995 at 11 commercial hazardous waste incinerators, 10 non-
commercial incinerators, and 23 other commercial treatment, storage, and disposal facilities.
The information included in U.S EPA (1995b) was compiled by contacting combustion
experts and permit writers in each of the 10 U.S. EPA regional offices, as well as individuals
within state regulatory agencies.
A total of 50 emergency incidents, as defined by U.S. EPA, were reported at the
hazardous waste incinerators identified in the study. In the report, an emergency incident is
defined as "a hazardous waste spill, unauthorized release, fire, or explosion." For the 26
commercial hazardous waste incineration facilities identified as having operated in the U.S.
some time during the period from 1981 to the present. 24 emergency incidents at 11 facilities
were reported, with 10 of these incidents involving a release of hazardous waste.
Based on the 10 reported emergency incidents involving hazardous waste over a total of
approximately 250-300 years of operation for the 26 commercial incinerators, approximately
one emergency incident involving a hazardous waste release has been reported for every 25 to
30 years of operation. None of the 10 reported incidents involving releases of hazardous
waste resulted in a fatality or serious injury in off-site communities, although on-site worker
injuries and fatalities have occurred.
Volume T VTT-
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C. Scenarios Considered in the Accident Analysis
Based upon a review of reported accidents at commercial hazardous waste incineration
facilities, available guidance, a review of the design and operation of the WTI facihtx. and a
site visit, the following general scenarios are selected for quantitative evaluation in the
Accident Analysis:
On-site spill;
• On-site fire.
On-site mixing of incompatible wastes;
Off-site tanker truck spill; and
• Off-site tanker truck spill with fire.
The criteria used in selecting these general scenarios are: (1) severity of consequence.
i.e., the potential for the scenario to result in significant off-site consequences; and (2)
probability of occurrence, i.e., the potential for the scenario to occur during the expected
operating life of the facility (30 years), based on available data.
For each of the five general scenarios selected for evaluation, both a "conservative" event
and a "typical" event is developed. These events are shown in Table VII-1. For the on-site
spill scenario, the typical event involves a 100-gallon spill due to a tanker truck accident,
resulting in volatile emissions. The conservative on-site spill event involves a 5,000-gallon
spill. The typical on-site fire scenario involves the combustion of 200 gallons of waste, while
the conservative on-site fire scenario involves a 20.000-gallon spill and fire. For on-site
mixing of incompatible wastes, the typical event involves generation of toxic gases in the event
of 200 gallons of incompatible waste being mixed. The conservative on-site mixing of
incompatible wastes scenario involves a total of 10.000 gallons of incompatible wastes being
mixed, and generating toxic gases.
The typical off-site spill event involves a 100-gallon spill along a local access road, while
the conservative off-site spill involves a 5,000-gallon spill along the local access road. The
off-site typical and conservative fire scenarios involve combustion of 100 gallons and 5.000
gallons of waste, respectively, along the local access road.
D. Chemicals of Potential Concern
Chemicals of potential concern in the Accident Analysis are identified from a review of
information from the following sources:
Volume 1 VII-3
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• Projected waste composition during the first year of operation, based on waste
profiles from WIT.
• Acutely hazardous wastes as defined under Subpart D of 40 CFR 260. Hazardous
Waste Management Systems;
• Chemicals regulated under Section 112(R) of the Clean Air Act (CAA) as toxic or
flammable substances that could be involved in an accidental release; and
• Chemicals listed as Extremely Hazardous Substances (EHSs) under Section 302 of the
Emergency Planning and Community Right-to-Know Act (EPCRA).
From a list of over 300 chemicals derived from these sources, specific indicator chemicals
are selected for each of the accident scenarios. The criteria used to select chemicals for
evaluation are the following:
• Acute toxicity. as represented by Immediately Dangerous to Life or Health (IDLH)
values established by the National Institute for Occupational Safety and Health
(NIOSH) or Level of Concern (LOG) values established by U.S. EPA;
• Volatility, as represented by the vapor pressure of the chemical; and
• Concentration, as estimated based on data reported in waste profiles supplied by WT1
For the on-site and off-site spill scenarios, two chemicals have been selected for
evaluation: formaldehyde and acetone Formaldehyde is selected as the "worst case"
chemical for evaluating spills based primarily on its high acute toxicity and high vapor
pressure. Acetone is selected as a "typical" chemical for evaluating spills primarily because it
is projected to be received in high quantities at the WTI facility. Both formaldehyde and
acetone wastes are evaluated for conservative and typical on-site and off-site spills.
For the on-site and off-site fire scenarios, combustion of a chlorinated waste generating
phosgene and hydrogen chloride (HC1) is selected in the Accident Analysis. Phosgene and
HC1 are selected based on high acute toxicity, and the likelihood that they could be produced
t *
during combustion of chlorinated wastes In both tne conservative and typical on-site and off-
site fire scenarios, it is assumed that a hypothetical waste containing 15% tetrachloroethene
and 85% toluene would be combusted. Fire scenarios which consider emissions of
Voli
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uncombusted waste constituents have also been evaluated, and are discussed in Volume VIII
(Response to Peer Review Workshop Comments).
For the on-site mixing of incompatible waste scenarios, HC1 is evaluated as the chemical
of primary concern in the event of mixing of incompatible wastes containing chlorine
(Bretherick 1985: Sax and Lewis 1989). According to ASTM (1986), HC1 formation can
occur when chlorinated hydrocarbons are mixed with mineral acids or strong oxidizing agents
In both the typical and conservative scenarios involving on-site mixing of incompatible waste.
it was assumed that a waste containing tetrachloroethene is mixed with a 70% nitric acid
solution, generating HC1 emissions.
E. Estimation of Emission Rates and Heat Effects
1. Chemical Emission Rates
Emission rates and durations are developed for the specific constituents based on
facility-specific parameters (such as tank volumes and dike sizes) and short-term
atmospheric release modeling techniques. These models account for the physical/chemical
properties of the substances and the presence of passive mitigation devices (e.g.. concrete
dikes and berms). Waste consisting of a mixture of chemicals is modeled for all events in
the Accident Analysis. Physical or chemical properties for these mixtures are estimated
from the properties of the pure chemicals, weighted by the mass fraction of each chemical
constituent
In estimating emissions for each of the on-site accident events, two scenarios are
evaluated:
• No active or automatic mitigation devices (e.g., nitrogen blankets or sprinkler
systems) are assumed. However, passive mitigation (dikes and berms) is
assumed to be effective
• Active or automatic mitigation devices are assumed to control emissions. The
effect of mitigation is evaluated in the uncertainty analysis through two separate
cases, with assumed response times of 10 minutes and 1 hour, respectively.
For the off-site accident events, only passive mitigation is considered.
Volume I VII-5
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2. Heat Effects
For the on-site and off-site fire scenarios, the Automated Resource for Chemical
Hazardous Incident Evaluation (ARCHIE) model developed by FEMA is used to assess
the heat effects of fires. For fires and explosions. ARCHIE can be used to estimate the
size of a pool of burning substances, the height of the expected resulting flame, and the
radius from the center of the burning pool within which individuals could potential!) be
fatally burned, or experience second degree burns or severe pain. ARCHIE modeling is
performed to examine the heat impacts resulting from a fire ignited both immediate!) attei
a spill, and after a pool achieves its maximum size.
In addition to heat effects, the fire hazards associated with a possible fireball incident
are also estimated using the ARCHIE model. A fireball could be formed if a sealed.
inadequately vented container of flammable liquid or liquified compressed gas is exposed
to an external fire or other source of heat sufficient to cause explosion or violent rupture
of the container (FEMA 1993). For the scenarios evaluated in the Accident Analysis, it is
considered highly unlikely that the above conditions would occur and that a fireball would
form.
F. Dispersion Modeling for Accident Scenarios
Two different models are used to evaluate atmospheric dispersion of releases that could
occur during potential on-site and off-site accidents from operation of the WTI facility:
• For vapor releases from accidents involving a spill or mixing of incompatible wastes.
the SLAB model is used SLAB is a model released by The Lawrence Livermore
National Laboratory, and has been identified by the U.S. EPA for use in modeling
hazardous/toxic air pollutant releases (U.S. EPA 1993c). This model simulates both
neutral and denser than air releases, and allows for continuous, finite duration, and
instantaneous releases.
• For releases associated with fire scenarios, the ISC-COMPDEP model is applied.
Unlike SLAB, ISC-COMPDEP has buoyant plume rise algorithms that allow the
gradual or transitional rise of plumes to be evaluated. In modeling buoyant plumes
associated with fire scenarios, the ability to treat terrain effects is critical.
For the accident scenarios modeled using SLAB, off-site chemical concentrations in air
are evaluated for three meteorological conditions:
Volume I VII-6
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• Typical Meteorological Conditions. Typical meteorological conditions at the WTI
facility are determined to be neutral atmosphere with average wmdspeed (3.2 m/s)
• Conservative Meteorological Conditions. To determine the appropriate conservative
meteorological conditions for any given accident scenario. 54 combinations of
atmospheric stability and windspeed are examined to determine the highest chemical
concentration in air at each off-site location. These 54 combinations of atmospheric
stability and windspeed are those selected relevant to noncalm meteorological
conditions at the WTI site. In general, the conservative meteorological condition
reflects a stable atmosphere with low windspeed, e.g.. a windspeed of 1 5 m/s. and
stability Category F
• Calm/Inversion Meteorological Conditions. Calm/inversion meteorological
conditions are considered the most stable condition that could occur at the WTI site.
and thus result in the highest off-site concentrations in air in the event of an accidental
release. Under the hypothetical calm/inversion condition, emissions are assumed to
accumulate in air immediately above the source for one hour during calm conditions.
and then are carried off-site under low wind speeds. This approach is consistent with
the approach used to evaluate calm/inversion conditions for routine incinerator stack
emissions.
For each of these meteorological conditions, a 30-minute average concentration is
calculated using SLAB, to allow for a direct comparison of predicted concentrations to
applicable criteria.
For the fire scenarios modeled using ISC-COMPDEP, typical and conservative
meteorological conditions are evaluated As with the SLAB model. 30-minute average
concentrations were calculated from the ISC-COMPDEP model results. The ISC-COMPDEP
model is not appropriate for use when calculating atmospheric dispersion under calm/inversion
conditions because the Gaussian equation assumption used in ISC-COMPDEP is invalid. An
evaluation of fire scenarios under calm/inversion conditions has thus been performed using the
CALPUFF model, and is discussed in Volume VIII (response to Peer Review Workshop
Comments).
G. Evaluation of Severity of Consequence and ^robability of Occurrence
The results of the Accident Analysis for each accident scenario are characterized in terms
of both severity of consequence and probability of occurrence. The severity of consequence
Volume I VII-7
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for each scenario is ranked as minor, moderate, major, or catastrophic, based on the distance
over which predicted concentrations in potentially inhabited areas could exceed either the U.S
EPA LOG values or the NIOSH IDLH values.
FEMA (1993) presents a four-tier system for classifying the consequences of accident
scenarios. This general system has been adapted and used as the basis for the following
severity of consequence categories developed specifically for use in the WT1 Accident
Analysis using LOG values as acute toxicity criteria:
Minor
No exceedance of an LOG value in inhabited off-site areas; and
negligible potential for off-site fatalities or serious injuries due to heat
effects from a fire.
Moderate Exceedance of LOG values in inhabited off-site areas over distances of
200 meters or less; injuries due to heat effects limited to a distance of
200 meters into inhabited areas.
Major
Exceedance of LOG values in inhabited off-site areas over distances
between 200 meters and 2,000 meters; injuries due to heat effects limited
to a distance of 2,000 meters into inhabited areas.
Catastrophic
Exceedance of LOG values in inhabited off-site areas over distances
greater than 2,000 meters; injuries due to heat effects extend to distances
greater than 2,000 meters into inhabited areas.
A similar system based on IDLH values has also been developed:
Minor
No exceedance of an IDLH value in inhabited off-site areas; and
negligible potential for cff-site fatalities or serious injuries due to heat
effects from a fire.
Moderate Exceedance of IDLH values in inhabited off-site areas over distances of
100 meters or less; injuries due to heat effects limited to a distance of
100 meters into inhabited areas.
Yolump T
VTT-8
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Major Exceedance of IDLH values in inhabited off-site areas over distances
between 100 meters and 1.000 meters; injuries due to heat effects limited
to a distance of 1,000 meters into inhabited areas.
Catastrophic Exceedance of IDLH values in inhabited off-site areas over distances
greater than 1,000 meters; injuries due to heat effects extend to distances
greater than 1,000 meters into inhabited areas.
In the Accident Analysis, the probability of occurrence is estimated based on the reported
frequency of general classes of accident events, using data summarized in U.S. EPA (19955).
along with the likelihood of the waste being received by WTI, and the meteorological
conditions at the time of the accident. For off-site accidents, these data are supplemented with
information compiled by the U.S. Department of Transportation and the Ohio Department ot
Public Safety. FEMA (1993) presents the following guidelines for evaluating accident
probability:
Common Expected to occur one or more times each year on average.
Likely Expected to occur at least once every 10 years on average.
Reasonably Predicted to occur between once every 10 years and once every
Likely 100 years on average.
Unlikely Predicted to occur between once every 100 years and once every 1,000 years
on average.
Very Predicted to occur less than once in 1,000 years.
Unlikely
The probability of occurrence is ranked according to these categories based on the
estimated probability of the accident event, the estimated probability of the meteorological
conditions, and an estimated waste composition based on the WTI waste profile information.
The probability of occurrence rankings developed in the Accident Analysis correspond to
broad classes of accidents, rather than individual events.
Volume I VII-9
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Severity of consequence and probability of occurrence rankings from the on-site scenarios
are summarized in Table VII-2. As shown in Table VII-2. the evaluation of consequences
using the above criteria for the on-site events results in the following:
• Only events with minor off-site consequences are considered likely to occur at the
WTI facility;
• Only events with minor or moderate off-site consequences are considered reasonabh
likely to occur;
• Events with potentially major off-site consequences are considered unlikely to occur;
and
• Events with potentially catastrophic consequences are considered very unlikely to
occur.
The severity of consequence and probability of occurrence rankings for off-site accident
scenarios are shown in Table VII-3. Using the same criteria for the off-site accident scenarios
results in the following:
• Events with minor consequences are considered to be, at most, reasonably likely to
occur;
• Events with potentially moderate or major consequences are considered to be unlikely
or very unlikely to occur; and
• Events classified as having potentially catastrophic consequences are considered to be
very unlikely to occur.
In general, the consequence probability rankings summarized in Tables VII-2 and VII-3
are consistent with the information presented in U.S. EPA's Report on Emergency Incidents a!
Hazardous Waste Incinerators and Commercial Treatment, Storage, and Disposal Facilities
(1995b). Using the compilation of accident events in U.S. EPA (1995b), and applying the
ranking scheme suggested in FEMA (1993). the probability of an accident-at a hazardous
waste incinerator with moderate, major, or catastrophic off-site consequences would be
classified as unlikely or very unlikely to occur over a facility lifetime. Only events having
Volume I VII-10
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minor off-site consequences would be classified as likely or reasonably likely to occur. This
generally agrees with the consequence probability rankings for the scenarios developed
specifically for the WTI facility in the Accident Analysis.
In response to Peer Review Panel comments, a screening-level evaluation of hypothetical
concentrations at the East Elementary School, which lies approximately 300 meters north of
the WTI facility, has also been performed. The results of the screening-level evaluation
indicate that, for most accident event scenarios, estimated worst-case concentrations at the
distance to the school are below LOG values. Those accident scenarios for which LOG values
might be exceeded at the distance to the school are expected to be very unlikely to occur
during the life of the facility.
H. Uncertainties
As described in Section VII (Uncertainties) of Volume VII, there are uncertainties
associated with various aspects of the Accident Analysis, including the toxicity evaluation, the
exposure assessment, and the ranking of both consequence and probability of occurrence.
Uncertainties associated with the evaluation of chemical toxicities include limited toxicological
data, the need to extrapolate from animals to humans, and a lack of knowledge regarding
potential interactions among various chemicals.
The sources and magnitude of the uncertainties associated with exposure assessment may
vary greatly from one risk assessment to another. These uncertainties are largely determined
by the chemicals, populations, pathways, data and models used in the assessment Scenarios
in the Accident Analysis are selected for quantitative evaluation to provide a range of credible
accident events More extreme events, with potentially greater off-site consequences, but
significantly lower probabilities of occurrence, are also theoretically possible, but would not
affect the overall conclusions of the Accident Analysis. Incomplete information on waste
composition and limited information available for predicting emissions resulting from fires or
the mixing of incompatible wastes also contribute to uncertainty. This uncertainty is addressed
by selecting indicator chemicals believed to overestimate, rather than underestimate, potential
risk.
Parameters used in the Accident Analysis that are subject to uncertainty include those used
to estimate emission rat~s (e.g., spill pool size and temperature) and chemical concentrations
in the media and locations of interest (e.g., wind speed and other meteorological conditions).
Additionally, uncertainty is inherent in the models used to predict chemical emissions and
subsequent atmospheric dispersion. Conservative assumptions are generally made in applying
these models to avoid underestimating potential off-site consequences.
Volume I VH-11
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Sensitivity analyses are used to demonstrate the effect of active mitigation measures and
the effect of failures of passive mitigation measures on the severity of consequence. It is
predicted that active mitigation is effective in reducing short-term consequences only if it
occurs relatively quickly, i.e., within 10 minutes of the accident event. As expected, failure
of passive mitigation (e.g., failure of dikes at the same time an accident occurs) would increase
the potential for off-site consequences.
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VIII. ADDITIONAL ANALYSIS IN RESPONSE TO
PEER REVIEW RECOMMENDATIONS
A. Overview
Volume VIII of the risk assessment was prepared to address comments received from the
scientific peer review conducted on the draft of the comprehensive risk assessment for the
WTI facility. That peer review, the second of two peer reviews concerning the WT1 risk
assessment, began in the winter of 1995. It included a face-to face meeting of the peer panel
in Washington, D.C., on January 11, 1996, and concluded with the publication of the report
entitled Report on the U. S. EPA Technical Workshop on WTI Incinerator Risk Assessment
Issues on May 2, 1996 (subsequently referred to in this document as the "Report").
The second peer review continued a process begun in 1993, when the U.S. EPA's Risk
Assessment Forum held a workshop to review the original project plan for the WTI risk
assessment. In that first peer review workshop, 13 peer reviewers were distributed into work
groups to discuss four major aspects of the project plan: combustion engineering,
meteorological conditions/air dispersion, exposure assessment, and toxicology. The workshop
was attended by more than 100 observers. Workshop participants recommended that the U.S.
EPA expand the scope of the planned assessment to include more facility performance data,
use additional computer models, include a screening ecological risk assessment, and provide
an analysis of accident scenarios
For the second peer review, the U.S EPA Risk Assessment Forum added a fifth work
group specializing in the area of ecological assessment, and expanded the scope of the air
dispersion work group to include accident analysis. The number of reviewers was increased
from 13 to 19, with many of the original 13 reviewers participating in the second peer review
In this second peer review, the U.S. EPA sought comments on the technical accuracy,
completeness, and scientific soundness of the WTI facility risk assessment.
The 1-day workshop on January 11. 1996, provided a forum for the expert peer review
panel to discuss the elements of the draft WTI risk assessment. Unfortunately, inclement
weather prevented many members of the community surrounding WTI from traveling to and
participating in the review process.
Volume T VIII-
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The reviewers were in general agreement on the overall quality of the assessment and
contributed useful suggestions for refinements to the final document. According to the May 2
Report:
"Overall, comments on the draft WTI risk assessment were favorable Indeed.
throughout the workshop, as the expert peer reviewers discussed the assessment as a
whole and specific parts of it, workshop participants repeatedly prefaced suggestions
for improvements with praise for the overall thoroughness, quality, and integrity of
the assessment. Noting that they had been quite critical of the draft project plan for
the assessment, the peer reviewers stated that by contrast they were very impressed
with the thoroughness, organization, and clarity of the draft assessment - and with the
seriousness and faithfulness with which EPA had followed the comments and
recommendations of the project plan peer reviewers. Their most substantive
comments pertained to three topics (accident scenarios, cumulative risk, ecological
risk) that were not covered in the initial project plan for the assessment and thus had
not benefited from previous review. The peer reviewers described most of their
other comments as questions of clarification or as other minor issues not likely to
affect the overall results of the assessment. "
In the May 1 Report, each of the five work groups summarized its comments in an
individual chapter or section. Each chapter summarized its findings with both "Near-Term
Recommendations" specifically addressing the WTI risk assessment, and "Long-Term
Recommendations" for consideration in future risk assessments conducted by the Agency.
Each chapter also contained a more detailed narrative providing the background for each of the
recommendations .
A new volume, Volume VIII, was created to provide additional analysis and respond to
each of the Near-Term Recommendations of the peer panel in each of the subject-specific
Chapters. Where it was appropriate to make changes in the risk assessment itself, those
changes are referenced in Volume VIII.
Because the peer review panel's long-term recommendations generally addressed future
risk assessments, Volume VIII generally does not respond to those suggestions. However,
wherever the EPA risk assessment staff believed that either a long-term recommendation or a
specific element of a background narrative could benefit from an Agency response,
Volume VIII does provide such response.
What follows in this Chapter are the highlights of the comments from each peer review
work group, and how the EPA has addressed each comment.
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B. Combustion Engineering
1. Chemical Emissions from Accidental Fire
Comment: The peer reviewers suggested that the EPA change the chemical release
model for the accidental fire scenario to include the same chemicals and relative
emission rate estimation procedures used for stack emissions based on overall
destruction efficiencies ("DEs") of 90 to 99.99 percent.
Response: This has now been done. Two additional approaches were investigated
based on the suggested approach, representing "worst case" waste and "typical"
waste. The detailed results are presented in Volume VIII. In brief, the results of the
more conservative 90% DE analysis for the two assumed waste mixtures were that the
acute toxicities associated with the predicted ambient air concentrations of the
hazardous constituents would not increase the size of the total area found to be above
the IDLH/LOC level when compared with the original analysis (which only evaluated
phosgene and hydrochloric acid predicted to be formed in the fire). We have noted
the results of this additional analysis in the final risk assessment.
2. Particle Size Distribution Data
Comment: The peer panel suggested that the EPA obtain actual particle size
distribution data for stack emissions in order to improve the risk assessment's
estimates of gas-particle partitioning of PCDD/F and metals and other PICs. The
peer reviewers stated that if it could be demonstrated that the currently used
assumptions are the most conservative, the requirements for additional stack sampling
could be omitted.
Response: The EPA evaluated this comment, and demonstrates in Volume VIII that
the chosen method is the most conservative approach.
3. Emissions During Abnormal Operations
Comment: The peer panel suggested adjusting the estimate of 11001131 PIC emission
rates to reflect emissions during abnormal operations (i.e., based on the percentage of
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operating time during which emission violations or automatic waste feed cutoffs
occur)
Response: The EPA has done this, basing the analysis on continuously recorded
stack emissions of total hydrocarbons. The results are presented in Chapter II of
Volume VIII, and are referenced in Volume V.
4. Facility-Specific Sulfur Dioxide Removal Efficiencies
Comment: The peer panel suggested that EPA obtain actual facility-specific sulfur
dioxide (SO2) removal efficiency data over a wide concentration range so that the
SO2 surrogate will better model the behavior of selenium.
Response: We obtained and analyzed that information, but were not able to make
any useful conclusions for the risk assessment. Based on our analysis of this
previously unavailable data, we concluded that we have limited confidence in the use
of the SO2 capture efficiency, as measured by the CEM system, to estimate the
selenium capture efficiency. We therefore recommend that selenium capture
efficiency be measured directly at the facility. This capture efficiency should
specifically be studied at a low feed concentration which is determined to realistically
represent expected feed concentrations.
C. Air Dispersion and Deposition Modeling
1. Additional Calm/Stagnation Event Modeling
Comment: The peer reviewers stated that the CALPUFF analysis was limited to
"simple terrain" and a greatly simplified meteorological data set due to data
limitations. The reviewers recommended performing the CALPUFF analysis using a
realistic four-dimensional wind field over a reasonable period of time to assess
concentrations under adverse dispersion conditions such as a calm/stagnation event.
These results should then be compared with ISC-COMPDEP to better understand the
impact of calm/stagnation conditions on predicted concentrations.
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Response: The Agency analyzed this issue and determined that rerunning
CALPUFF, as suggested by the peer reviewers, would not change the results of the
risk assessment A detailed analysis is presented in Volume VIII.
2. Re-evaluate Accident Scenarios Emissions During Calm Conditions
Comment: The peer panel stated that the extended dispersion modeling performed
for the accident scenario should be re-examined in light of the CALPUFF
calm/stagnation analysis. Accident scenario concentrations should be recomputed
based on the occurrence of an accident during the meteorological event to assess
whether ambient concentrations during such an event are significantly exacerbated
Response: The Agency addressed this comment by running the CALPUFF model for
the calm/inversion meteorological condition for both fire scenarios. The results and
findings of this analysis are described in Volume VIII of the risk assessment.
D. Exposure Assessment
1. Likelihood That Surrogate Selection Process Biased the Calculated Risk
Comment: The peer panel recommended that EPA consider the likelihood that a
chemical with a significant potential contribution to risk was omitted via the surrogate
selection process for evaluating chemicals for indirect risk. The panel asked for a
simple qualitative reality check.
Response: The Agency performed a quantitative analysis to compare results of the
surrogate chemical selection process with the cancer risks and Hazard Index (HI)
values predicted for the subsistence farmer in the area of highest impact. (Only
organic chemicals enter into this analysis since all metals were selected for entry into
the risk estimates.) The objective was to determine how well the surrogate ranking of
the chemicals correlates with their contribution to total organic risk. For carcinogens,
this analysis indicated that more than 90 percent of the total risk associated with the
29 organic chemicals selected as surrogate chemicals was associated with the 16
chemicals with the highest surrogate selection scores. The incremental addition to the
total risk of the surrogate chemicals was insignificant for the chemicals with the
lowest surrogate selection scores. It was therefore concluded that it is unlikely that
Volume I VIII-5
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chemicals screened out in the surrogate selection process would contribute
significantly to total cancer risk. Similar findings were observed in an analysis of the
surrogate chemicals with noncancer effects. A description of the analysis conducted
and the results has been included in Chapter VIII of the revised HHRA (Volume V)
2. Clarify How Chemical Concentration and Exposure Factors Were Combined
Comment: It was suggested that the EPA add a table or figure that summarizes how
chemical concentrations and exposure factors were combined to develop central
tendency and high-end estimates of exposure and risk.
Response: The text in Volume V has now been modified to clarify the process of
combining exposure factors, and a new table (Table VIII-2) was added to the HHRA
that summarizes the two "risk descriptors "--area average and maximum-and the two
subgroups evaluated in the high-end sensitivity analysis.
3. Exposure to Household Dust
Comment: The peer panel suggested that the EPA include a qualitative discussion
about the contribution of household dust to exposure.
Response: Text was added to the soil ingestion section of Volume V Appendix V-8
that indicates that the soil ingestion rates used are based on estimates of ingestion of
outdoor soil and indoor dust (per U.S. EPA guidance). The added text also indicates
that it is assumed for the purposes of the HHRA that concentrations in outdoor soil
and indoor dust are equal. This assumption was also added to the Key Assumption
table in Appendix V-8 of Volume V.
4. Expand Table on Key Fate and Transfer Assumptions
Comment: The peer reviewers suggested that EPA expand Volume V Table Vl-2 on
key assumptions for fate and transport models to include more components about
processes of biotransfer, diffusion, and deposition.
Response: The Key Assumptions table that was prepared for Volume V Appendix V-
7 (Fate and Transport Model Equations and Parameter Values) is now used in place
Volume I VIII-6
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of the table previously presented in Volume V Chapter VI. This "new" table
provider more detail concerning fate and transport modeling assumptions. A footnote
was added to the table to indicate that Key Assumptions concerning diffusion and
dispersion are summarized in Volume IV.
E. Toxicology
1. Route-to-Route Extrapolation of RfDs
Comment: The peer review panel suggested including a discussion of the uncertain!}
associated with employing route-to-route extrapolation of RfDs.
Response: Route-to-route extrapolation for chemicals with noncancer health effects is
discussed briefly in Chapter III, Section D.2. This discussion was expanded and
developed into a new section in this part of the HHRA.
2. Additivity versus Synergy or Antagonism
Comment: The peer reviewers asked that EPA provide additional discussion and
rationale for the assumption of additivity versus assumption of synergy or antagonism
for the toxicology of complex mixtures.
Response: New text and additional references have been added to Volume V which
support the use of additivity as presently the best model to employ after considering
the available data and the low doses that are expected from WTI emissions.
3. Include List of Noncancer Endpoints
Comment: The peer review panel suggested that EPA include a list of noncancer
endpoints for chemicals addressed in the risk assessment.
Response: A table summarizing the target organs for noncancer effects associated
with the surrogate organic chemicals and metals evaluated in the HHRA has been
added to Volume V, Chapter VIII.
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4. Exposure to Metals via Breast Milk Pathway
Comment: The peer reviewers suggested clarifying why the risk assessment does not
address exposure to metals (especially methyl mercury) by the breast milk pathway
Response: An analysis was conducted to compare relative concentrations of
contaminants in cows' milk to provide an indication of the potential partitioning of
metals into human breast milk. The relative concentrations of 2,3,7,8-TCDD,
benzol ajpyrene, arsenic, beryllium, and mercury were compared. Based on
partitioning of contaminants into cows' milk, as estimated in the HHRA. the
partitioning of metals, such as arsenic, beryllium, and mercury, was found to be more
than 1.000 times lower than the partitioning of organic compounds, such as 2.3.7.8-
tetrachlorodibenzo-p-dioxin and benzo[a]pyrene. Further discussion is provided in
Volume VIII.
5. Uncertainty Associated with Uncharacterized Emissions
Comment: The peer reviewers suggested that the risks of uncharacterized emissions
be further evaluated.
Response: A discussion of uncharacterized emissions has been added to Volume V,
Chapter VIII.
F. Ecological Risk Assessment
1. Goals and Purpose
Comment: The peer review panel stated that the principal problem with the SERA
was that its goals and purpose were not clear. Consequently, the implications of the
results of the assessment and the appropriateness of possible recommendations were
found to be unclear.
Response: The text describing the purpose and scope of the SERA has been revised
and expanded in Volume VI. This includes a new section on "Goals and Objectives
of the SERA" which clearly states the goals of the document along with the primary
Volume I VIII-8
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and secondary objectives. Numerous sections within Volume VI have been revised to
clearly restate these goals and objectives.
2. Permit Limit Scenario
Comment: The peer review panel was concerned that the "permit limit scenario"
does not appear in the human health risk assessment.
Response: In order to assist the permitting authorities in evaluating maximum permn
limits, a separate analysis has been performed, similar to that performed in the
SERA, to evaluate the potential human health risks from metals emitted at the current
maximum permit limit. This is included in Volume VIII as Attachment VII-1.
3. Improve Text Clarity
Comment: The peer reviewers suggested that EPA edit the SERA to make it more
succinct and more accessible to stakeholders.
Response: The entire SERA text has been revised to improve clarity, including
appropriate cross references to other Volumes of this WTI Risk Assessment and
redundant text has been removed.
4. Indicate Key Uncertainties that Influence Conclusions
Comment: The peer review panel suggested clarifying in the uncertainty analysis
which uncertainties are most important to the conclusions.
Response: Chapter VIII of Volume VI, Uncertainty Analysis, underwent significant
revision and provides a discussion of key uncertainties expected to influence
ecological risk. The sections on uncertainty of Chapters IV through VII were also
revised, along with Tables IV-11, V-33, VI-8, and VII-58, to clarify the importance
to risk conclusions
Volume I VIII-9
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G. Accident Analysis
1. Pressurized Release
Comment: The peer reviewers were concerned that the accidental analysis did not
address all potentially important accident scenarios. For example, pressurized jet
releases from the incinerator containment was suggested as a scenario that could
result in aerosol formation due to mixing of chemicals or heating by fire.
Response: In response to the peer panel's concern, the EPA has re-evaluated the
possibility of such a pressurized jet scenario for inclusion in the accident analysis.
Our analysis of the potential for such a scenario is presented in Volume VIII.
2. Accident Severity and Consequence Information
Comment: The peer reviewers stated that the accident analysis did not adequately
communicate the expected value of accident impacts.
Response: Numerical ranges associated with the terms have now been incorporated
into a table as part of the results.
3. Use of ERPG-2 Values
Comment: The IDLH values used in the accident analysis are designed to provide
short-term protection to healthy workers and do not account for the greater variation
in sensitivity likely to exist in a non-occupational population that includes children.
The peer reviewers recommended that some other measure of accident health impacts
be considered. It was noted that the American Industrial Hygiene Association's
Emergency Response Planning Guidelines (ERPG) levels would probably have been
more appropriate than IDLH values for characterizing the severity of accident
consequences.
Response: The Accident Analysis was modified to respond to this concern. In the
Accident Analysis, ERPG-2 values are compared to both LOC and IDLH values for
the chemicals selected for each accident events. Furthermore, a comparison between
ERPG-2 values and LOC values for chemicals selected for evaluation in the Accident
Volume I VTTT-10
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Analysis is presented in Attachment IV-1 to Volume VIII titled "Evaluation of the
Use of ERPG-2 Values vs. LOG values in the Accident Analysis for the WTI
Facility." IDLH values are still retained as a screening method to select the
chemicals of concern that should be entered into the quantitative analysis of accident
scenarios, because the IDLH value is the acute health benchmark available for the
largest number of substances in WTI's waste profile list (>300 chemicals).
4. Fire Emissions Similar to Stack Emissions
Comment: The panel recommended that the chemical release model for accidental
fires should be changed to include the same chemicals and relative emission rate
estimation procedures used for stack emissions.
Response: The analysis now includes such a fire scenario evaluation of a "worst-
case" and a more typical waste based on total volume received and toxicity as
determined from waste profiles received during the first year of operation. The
chemical emission rates have been determined for DRE values of 90 and 99%. For
information on this analysis, see the response to Comment #1 in the Combustion
Engineering section of Volume VIII.
5. CALPUFF Analysis of Calm/Stagnant Conditions
Comment: The peer reviewers stated that the dispersion modeling performed for the
accident scenarios should be re-examined in light of the reviewers' recommendation
that calm/stagnant conditions be reanalyzed with a more appropriate data set in the
CALPUFF model.
Response: This has been done, with the results presented in Chapter III of
Volume VIII.
6. More Appropriate Model for Chemical Evaporation
Comment: The peer reviewers were concerned that the model used to estimate the
rate of chemical evaporation from spills was not appropriate for calm conditions.
Volume T ViTT-11
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Response: The conservative on-site and off-site spills have been re-evaluated in light
of the Rife and Gauss models recommended by the peer review panel. The results of
the reevaluation are presented in Volume VIII.
7. Screening-Level Evaluation for Chemical Concentrations at the East Elementary
School
Comment: The peer reviewers recommended that the Accident Analysis be modified
to include an evaluation of potential chemical concentrations at the East Elementary
School in the event of an accidental release.
Response: The Accidental Analysis has been expanded to include a screening-level
evaluation at the location of East Elementary School.
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IX. REFERENCES
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based on binary chemical reactions. D-34 Proposal P. 168. March.
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CACI Marketing, Inc. (CACI). 1992. The sourcebook of county demographics: Census
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Technologies
ENSR Consulting and Engineering (ENSR). 1993. Final trial burn report for the rotar\ kiln
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Ohio Department of Natural Resources (ODNR) 1994b. Telephone conversation between
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practices in Ohio. November.
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Ohio River Valley Water Sanitation Commission (ORSANCO). 1988. 1987and 1988
ORSANCO composite fish tissue data. Cincinnati, Ohio.
Ohio River Valley Water Sanitation Commission (ORSANCO). 1990. Sample analyses
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Ohio River Valley Water Sanitation Commission (ORSANCO). 1993. Results of 1992 fish
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Voliimr 1 TX -">
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Technical guidance for hazards analysis: Emergency planning for extremely hazardous
substances OSWER-88-0001 (NTIS PB93-206910). December.
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U.S. Environmental Protection Agency (U.S. EPA). 1990b. Exposure factors handbook.
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Final Draft ECAO-CIN-757. Cincinnati, Ohio.
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of inhalation exposures to stack emissions from the WTI Incinerator. January.
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Source Complex (ISC2) Dispersion Models. Volume I. EPA/450/4-92/008a.
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impacts from WTI facility, attached to memorandum from W. Farland, Director. Office of
Health and Environmental Assessment to B. Grant, Attorney, Office of General Counsel.
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Research and Development February 8
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assessing health risks associated with indirect exposure to combustor emissions."
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U.S. Environmental Protection Agency (U.S. EPA). 1993c. Guidance on the application of
refined dispersion models for hazardous/toxic air releases. Office of Air Quality Planning
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U.S. Environmental Protection Agency (U.S. EPA). 1993d. WTI Phase II Risk Assessment
Project Plan, EPA ID number OHD980613541. Region V, Chicago. Illinois U.S. EPA
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Workshop on WTI Incinerator Risk Issues. EPA/630/R-94/001 December
U.S. Environmental Protection Agency (U.S. EPA). 1993f. Provisional guidance for
quantitative risk assessment of poly cyclic aromatic hydrocarbons. Office of Research and
Development. Washington, D.C. EPA/600/R-93/089. July.
U.S. Environmental Protection Agency (U.S. EPA). 1994a. Memorandum from W. Farland.
Director, Office of Health and Environmental Assessment to WTI Workgroup entitled:
Update of WTI screening level analysis. October 26.
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like compounds. Review Draft. Office of Research and Development, Washington. D.C.
EPA/600/6-88/005Cc.
U.S. Environmental Protection Agency (U.S. EPA). 1994c. Implementation guidance for
conducting indirect exposure analysis at RCRA combustion units. Memorandum from
M. Shapiro, Director, Office of Solid Waste. Revised April 22.
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West Virginia Agricultural Statistics Service (WVDA). 1994. 7993 Annual Bulletin No. 24.
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