United States
Environmental Protection
Agency
Region 5
77 West Jackson Boulevard
Chicago, IL 60604
EPA905-D95-002 /
Bvern6erf§95
External Review Draft
WASTE, PESTICIDES AND TOXICS DIVISION
Risk Assessment for the
Waste Technologies Industries (WTI)
Hazardous Waste Incinerator Facility
(East Liverpool, Ohio)
DRAFT
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REGION 5
Risk Assessment for the Waste Technologies Industries (WTI)
Hazardous Waste Incinerator Facility (East Liverpool, Ohio)
DRAFT DO NOT CITE OR QUOTE
Volume I:
EXECUTIVE SUMMARY
Prepared with the assistance of:
A.T. 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
NOTICE: THIS DOCUMENT IS A PRELIMINARY DRAFT.
It has not been formally released by the U.S. Environmental Protection Agency as
a final document, and should not be construed to represent Agency policy.
It is being circulated for comment on its technical content.
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VOLUME I
EXECUTIVE SUMMARY
CONTENTS
I. INTRODUCTION AND SUMMARY OF RESULTS 1-1
A. Overview 1-1
B. Introduction and Overview of Results 1-2
1. Human Health Risk Assessment 1-2
a) Introduction 1-2
b) Overview of Results 1-4
2. Screening Ecological Risk Assessment 1-5
a) Introduction 1-5
b) Overview of Results 1-7
3. Accident Analysis 1-8
a) Introduction 1-8
b) Overview of Results I-11
C. Structure of the Report 1-12
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 III-3
D. Uncertainties III-5
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 INPUFF IV-4
4. Wind Tunnel Simulations IV-5
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CONTENTS
(continued)
Page
5. Fugitive Emission Sources IV-5
C. Results IV-5
D. Uncertainties IV-6
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-3
D. Exposure Assessment V-5
1. Identification of Population Subgroups
and Exposure Pathways V-5
2. Fate and Transport Modeling V-6
3. Calculation of Dose V-7
E. Risk Characterization V-9
F. Uncertainties V-ll
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 VI-6
E. Characterization of Effects VI-6
F. Risk Characterization VI-7
G. Uncertainties VI-8
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 VII-2
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CONTENTS
(continued)
D. Chemicals of Potential Concern
E. Estimation of Emission Rates and Heat Effects
1. Chemical Emission Rates
2. Heat Effects
F. Dispersion Modeling for Accident Scenarios
G. Evaluation of Severity of Consequence and
Probability of Occurrence
H. Uncertainties
VIII. 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 Particulate 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 Emission
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
VH-3
VH-5
VII-5
VII-5
VII-6
VII-7
VII-9
VIII-1
III-7
III-8
III-9
III-14
111-15
111-16
IV-8
IV-9
IV-10
IV-11
V-13
V-14
V-15
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CONTENTS
(continued)
Table V-4: Estimated Area Average Cancer Risks and Hazard Indices
Due to Exposure from Direct and Indirect Pathways in
Subarea El
Table VI-1 Metals Evaluated in the SERA - Stack Emissions
Table VI-2: Organics to Be Evaluated in the SERA - Stack Emissions
Table VII-1: Scenarios Selected for Quantitative Evaluation
Table VII-2: Severity of Consequence and Probability of Occurrence
Results for On-Site Scenarios
Table VII-3: Severity of Consequence and Probability of Occurrence
Results for Off-Site Scenarios
V-16
VI-10
VI-11
VII-11
VII-12
VII-13
FIGURES
Figure II-1: Location of the WTI Facility
Figure II-2: WTI Site Plan
Figure III-l: Location of Stack, Fugitive Organic Vapor, and Ash
Emission Sources
Figure VI-1: Diagrammatic Conceptual Site Model for the WTI SERA-
Stack Emissions
Figure VI-2: Diagrammatic Conceptual Site Model for the SERA-
Fugitive Emissions
II-5
II-6
III-17
VI-12
VI-13
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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
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
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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, 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 likelihood of several
general classes of accidents that could potentially occur during operations of the
WTI facility. The Accident Analysis also evaluates the overall effectiveness of
existing mitigation measures in reducing off-site impacts.
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:
National Research Council (NRC). 1983. Risk Assessment in the Federal
Government: Managing the Process.
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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
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 ORE) in 1993, Screening Level Analysis
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of Impacts from WH Facility (U.S. EPA 1993a), and another performed by ORD in
1994, Update of W77 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 hi 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 10"6)
or less. For chemicals other than PCDD/PCDF, the highest predicted
cancer risks are for infant ingestion of mother's milk, which is estimated to
pose an average cancer risk of approximately 2 x 10"6, primarily through
exposure to benzo(a)pyrene. Estimated average noncancer hazard index
1 The subsistence fanner 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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(HI) values are below 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 cumulative risk across the entire population in the
vicinity of the WTI facility, it is not anticipated that any individual in this
population would develop cancer as a result of exposure to routine WTI
incinerator stack 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.
Based on the results of a quantitative uncertainty analysis, assuming a subsistence
farmer resides at the location of maximum impact, it is concluded that there is only a
very small probability that individual cancer risks associated with exposure to facility
emissions would exceed 1 in 10 thousand (1 x 10"*).
2. Screening Ecological Risk Assessment
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 vicinity 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 toxicity benchmarks (based on ecologically relevant endpoints)
were developed to evaluate the potential ecological effects of facility releases.
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
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effects at levels of organization beyond the individual (i.e., the population and
community). Furthermore, benchmarks for chronic toxicity are less well established
for performing ecological assessments than for human health assessments. As a
result, compared to human health assessments, ecological risk assessments
(especially on 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. 1992e. 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
1992e), 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 describes central tendency and high-end exposures, the SERA relies on
conservative estimates of emission rates and exposure parameters to produce
reasonable upper-bound estimates of risk. Examples of conservative approaches
used in the ecological assessment include the following:
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To maximize hypothetical exposures, the ecological receptors considered in
the assessment are assumed to be present at the location of maximum
impact of facility emissions, with lifetime home ranges confined to the
maximum impact point. For example, for fugitive emissions, exposures are
estimated at on-site 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 endpoints
(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 limits emissions, as defined in the facility's existing
RCRA permit. A separate evaluation based on "expected" metal emission
rates is also performed.
The SERA conducted in 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 includes a wide variety of habitats
and species. Species listed as rare, threatened, or endangered by Federal
and State agencies are not generally observed within five kilometers from
the facility.
The maximum estimated exposure points for both stack and fugitive
emissions are within one kilometer from the facility.
For routine emissions of organic compounds from the incinerator stack,
very low to negligible ecological risks are indicated.
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Under the expected emission scenario for metals from the incinerator stack,
very low to negligible ecological risks are indicated.
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, and nickel.
For fugitive vapor emissions, 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 facility, where inhalation exposures would be limited because of habitat
considerations and thus significant adverse effects to wildlife populations
and community structure are very unlikely.
For fugitive ash emissions, negligible ecological risks are indicated.
Given the conservative assumptions used in the SERA, the likelihood of
significant risks to ecological receptors as a result of expected incinerator stack and
fugitive emissions is predicted to be very low. If the WTI facility were to operate
continuously at the maximum hourly permit limits for metals, however, risks of
relatively high magnitude are predicted hi the SERA. Although it is theoretically
and legally possible for the WTI incinerator to continuously emit metals 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 (see Chapter VI). Quantifying the likelihood
and possible extent of potential effects under the permit limit scenario would require
a more refined analysis.
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 likelihood of occurrence is evaluated. This subset has
been selected to address outcomes (e.g., spills, fires) that could be caused by
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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
U.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. 1995c. Accidental Release Prevention Requirements: Risk
Management Programs under Clean Air Act Section 112(r)(7); Proposed
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
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.
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.
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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.
In 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. This system has been used as the basis for developing the
following severity of consequence categories in the Accident Analysis:
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Minor No exceedance of an 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 areas over distances of
100 meters or less; injuries due to heat effects limited to a distance
of 1,000 meters into inhabited areas.
Major Exceedance of IDLH values in inhabited 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 hi 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 likelihood 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 moderate off-site consequences are determined to be reasonably likely to
occur.
All on-site accident scenarios with major off-site consequences are
determined to be unlikely to occur, and all on-site accidents with
catastrophic off-site consequences are determined to be very unlikely to
occur.
For off-site accidents, events with minor consequences are determined to
be, at most, reasonably likely to occur.
All off-site accident scenarios with moderate or major consequences are
found to be unlikely or very unlikely to occur, and off-site accidents
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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. Events having minor off-site
consequences are classified as 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 seven 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
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.
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H. 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 l/i 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 4 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 90 non-
intermittent rivers and streams and 50 wetland areas greater than 10 acres within 20-
kilometers of the WTI facility. Due to the diversity of habitats in the general vicinity, there
are numerous plant and animal communities composed of plant, mammal, bird, reptile,
amphibian, fish, and other species. Some of the species within the WTI study area are
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classified as rare or endangered by the U.S. EPA 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
aspects of the facility setting are addressed in the atmospheric dispersion modeling conducted
for 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:
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
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clam shell bucket then transfers the waste from the waste pits into a feed 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 that do not contain free
liquids are 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
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
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carbon injection system (ECIS), an electrostatic precipitator, a flue gas quench, and a four-
stage wet scrubber system. The purpose of the air pollution control system is to reduce the
concentrations of organics, metals, acid gases, and particulate matter in the combustion gas
stream. The resulting flue gas is discharged into the atmosphere from a 150-foot stack.
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F!\013999G\FIG2-I.DVG
HARRISON
0 20
Scale in Kilometers
40 0
12.4
Scale in Miles
24.8
Volume I
LOCATION OF THE WTI FACILITY
External Review Draft
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Figure 11-1
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»«.._jT /jS j
"I PROPOSED BUILDINGS
T EnsiiNC FACILITIES
CONCRETE PAVEMENT
BITUMINOUS *A»EM£NT
LEGEND
NEW SECUfllM rEKE
EUSUNC FENCE
PROPER I r LINE I CORNER
SIDE SLOPE
-------
m. 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:
Poly chlorinated 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;
Metals, which may be present in the waste but can not be destroyed by combustion;
Acid gases, such as nitrogen oxides (NOX), sulfur oxides (SOX), and hydrogen
chloride (HC1), which are formed during the combustion process; and
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Particulate 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 hi March 1993 and February 1994; and
Incinerator performance tests conducted hi 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.
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 hi August 1994. PCDD/PCDF data collected at the
WTI facility prior to the installation of the enhanced carbon injection system (ECIS) in July
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
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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 feed
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 IH-2; estimated emission
rates developed for PICs are shown on Table HI-3.
Emission rates are developed for 15 metals expected to be present hi 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
for 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, NOX, SOX, 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 hi the WTI facility permit
application and permit, an evaluation of the types of wastes handled by each of the facility
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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;
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 hi the vapor form, while
emissions from the fifth source, ash handling, are hi the form of particulate 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
organic vapor emission rates calculated for each source evaluated in the Risk Assessment are
as follows:
Valves and Flanges (Tank Farm Building): 2,126 Ibs./year
Carbon Adsorption Bed System: 224 Ibs./year
Waste Water Tank: 202 Ibs./year
Truck Wash Building: 10 Ibs./year
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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.
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.
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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 hi 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 hi 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:
Characterization of wastes handled at the facility - Fugitive vapor emissions are
highly dependent on the waste characteristics. Limited data, which might not be
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.
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TABLE m-1
Data on Polychlorinated Dioxin/Furan Stack Emissions at WTI Facility
Used in the WTI Risk Assessment"
Date
August 1993
February 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
Run5
Run 1
Run 2
Run 3
Run 4
Run 1
Run 2
Run 3
Run 4
Run5
Run 1
Run 2
Run 3
Run 4
RunS
Run 6
Run 7
Chlorine
Feed Rate
(Ib/hr)
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
(ng/dscm)b
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
0.045
0.019
0.028
0.029
0.035
0.084
0.072
0.057
0.056
0.037
0.036
0.035
0.032
0.033
0.017
0.010
0.016
0.017
0.018
0.021
0.021
TEQ
Emission Rate
(g/sec)
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
l.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
2.4E-10
2.4E-10
2.8E-10
3.0E-10
Notes
a All emissions testing was performed with a kiln temperature in the range 2,150-2,200°F.
b 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.
c The tetra- through octa- chlorinated 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.
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TABLE m-2
Estimated Average and High-end Stack Emission Rates for
Dioxin and Furan Congeners
Congener
Emission Rate (g/sec)
Average
High-end
Dioxin Congeners
2,3,7,8-TetraCDD
1,2,3,7,8-PentaCDD
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
1.08 x 10'11
6.78 x lO'11
8.95 x lO'11
1.66 x lO'10
1.09x ID'10
1.24xlO'9
6.15 x ID'9
2.16x 10'11
9.46 x 10-11
1.25 x lO'10
2.18x 10-10
1.55 x lO'10
1.69x lO'9
9.80 x lO'9
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
8.77 x lO'11
3.45 x lO'10
4.67 x lO'10
1.43x ID'9
1.33 x lO'9
l.SOxlO'9
2.93 x ID'10
9.30 x lO'9
1.22x 10-9
1.89x 10'8
1.15 x 10-10
4.35 x 10'10
6.04 x lO'10
1.85 x 10-9
1.71 x lO'9
1.96x lO'9
3.85 x lO'10
1.30 x lO'8
l.SOx lO'9
3.62 x 10-8
Notes:
CDD - chlorodibenzo-p-dioxin
CDF - chlorodibenzofiiran
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TABLE m-3
Estimated Average and High-end Emission Rates for Products of Incomplete
Combustion (PICs) and Residues of Organic Compounds
Substance
Acenaphthene
Acenaphthylene
Acetaldehyde
Acetone
Acetophenone
Acrylonitrile
Anthracene
Benzene
Benzole acid
Benzotrichloride
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g ,h , i)pery lene
Benzo(k)fluoranthene
Bis(2-chloroethoxy)methane
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromoform
Bromomethane
Bromodiphenylether, p-
Butanone, 2-
Butylbenzylphthalate
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-3-methylphenol, 4-
Chloroaniline, p-
Chlorobenzene
Chlorobenzilate
Emission Rate (g/sec)
Average
6.69 x 10-*
6.69 x 10-*
3.01 x 10^
2.90 x 10'3
2.93 x 10*
2.02 x 10*
5.50 x 10-*
1.47 x 10'5
1.13 xlO's
3.20 x lO'5
5.50 x 10-6
5.50 x 10-*
5.50 x 10-*
5.50 x 10-*
5.50 x 10-6
6.69 x 10-*
1.33 x ID'5
6.69 x 10-*
3.72 x 10'5
1.03 x 10*
5.50 x 10-6
4.90 x 10*
6.69 x 106
5.14x 10'5
5.50 x 10-*
8.91 x 10-'
1.58 x 10*
5.50 x 10-7
6.69 x 10-*
6.69 x 10-*
5.50 x 10-*
3.68.x 10-5
High-end
6.69 x 10-6
6.69 x 10"*
3.01 x 10*
2.90 x 10'3
2.93 x 10*
2.02 x 10*
l.lOx ID'5
2.63 x ID'5
1.13 x 10-5
3.20 x ID'5
1.10 x 10s
l.lOx ID'5
l.lOx 10-5
1.10 x ID'5
l.lOx 10-5
6.69 x 10-*
1.33 x lO'5
6.69 x 10-*
5.23 x 10'5
1.53 x 10*
l.lOx 10'5
9.80 x 10-4
6.69 x 10-*
7.40 x lO'5
l.lOx lO'5
9.46 x 10'5
2.75 x 10^
l.lOx 10-*
6.69 x 10-*
6.69 x 10-*
l.lOx 10'5
3.68 x 10-5
Source
a
a
a
a
a
a
b
b
a
a
b
b
b
b
b
a
a
a
b
b
b
b
a
b
b
b
b
b
a
a
b
a
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TABLE ffl-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-
Dichloroethene, trans- 1,2-
Dichlorophenol, 2,4-
Dichloropropane, 1,2-
Dichloropropene, cis-1,3-
Dichloropropene, trans-1,3-
Diethylphthalate
Emission Rate (g/sec)
Average
4.90 x 10*
2.66 x 10*
2.45 x 10-4
6.69 x 10-*
5.50 x 10-*
6.69 x 10"*
5.50 x 10-6
5.50 x 10"*
5.50 x 10-6
5.50 x 10-*
1.39x 10*
5.50 x 10-*
3.88 x lO'5
5.50 x lO'7
5.50 x 10-*
5.50 x 10-6
2.63 x 10-5
5.50 x 10-*
5.50 x 10-*
5.50 x 10-*
3.33 x 10-'
4.68 x lO'8
2.45 x 10*
1.25x 10'5
1.25 x 10'3
1.25 x 10-5
1.25 x 10-5
5.50 x 10-*
1.25 x 10'5
1.25 x lO'5
1.25 x lO'5
1.69x lO'5
High-end
9.80 x 10*
4.07 x 10*
4.90 x 10*
6.69 x 10-*
l.lOx 10-5
6.69 x 10-*
l.lOx 10'5
l.lOx 10 5
l.lOx 10-5
l.lOx 10-5
1.39 x 10*
l.lOx 10'5
3.88 x lO'5
l.lOx 10-*
l.lOx 10-5
l.lOx 10-5
2.63 x 10-'
1.10 x 10-5
l.lOx 10-5
l.lOx 10-'
3.33 x 105
8.22 x 10-"
4.90 x 10*
2.50 x 10-5
2.50 x 10-5
2.50 x 10-5
2.50 x 10'5
l.lOx 10-5
2.50 x ID'5
2.50 x 10-'
2.50 x 10-5
3.60 x 10-5
Source
b
b
b
a
b
a
b
b
b
b
a
b
a
b
b
b
a
b
b
b
a
b
b
b
b
b
b
b
b
b
b
b
Volume I
III-10
External Review Draft
Do not cite or quote
-------
TABLE m-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
Dinitrotoluene, 2,6-
Dinitro-2-methylphenol, 4,6-
Dinitrophenol, 2,4-
Dinitrotoluene, 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
Hexachloroe thane
Hexachlorophene
Hexanone, 2-
Indeno(l ,2,3-cd)pyrene
Isophorone
Maleic hydrazide
Emission Rate (g/sec)
Average
i.is x 10"
5.50 x 10-*
5.50 x 10-*
1.57 x lO'5
5.50 x ID"*
5.50 x 10-*
5.50 x 10-6
5.50 x 10-6
5.50 x 10-6
4.94 x 10"
2.45 x 10"
4.98 x 10"
1.15x 10"
3.05 x lO'5
1.46x 10'10
5.50 x ID'6
6.69 x lO'6
6.07 x 10"
5.50 x 10"*
5.50 x lO'7
1.40x 10'8
5.50 x 10-'
1.40x 10-8
1.01 x 10"
5.48 x lO'5
5.50 x 10-*
5.50 x 10-*
3.20 x ID'5
6.43 x 10'5
5.50 x 10-*
6.69 x 10-*
1.15x lO"
High-end
1.15 x 10"
l.lOxlO'5 '
l.lOx lO'5
2.04 x lO'5
l.lOxlO5
l.lOx 10'5
1.10 x 10'5
l.lOx lO'5
l.lOx ID'5
4.94 x 10"
4.90 x 10"
7.53 x 10"
1.15x 10"
3.05 x 10'5
1.46 x 10-'°
l.lOx 10'5
6.69 x 10-'
6.07 x 10"
1.10 x 105
1.10 x 10-6
2.80 x 10-8
1.10 x 10 5
2.80 x lO'8
1.01 x 10"
5.48 x 10-5
l.lOx 10 5
1.10 x ID'5
3.20 x lO'5
6.43 x 10'5
l.lOx 10'5
6.69 x 10-*
1.15x10"
Source
a
b
b
b
b
b
b
b
b
a
b
b
a
a
a
b
a
a
b
b
b
b
b
a
a
b
b
a
a
b
a
a
Volume I
III-11
External Review Draft
Do not cite or quote
-------
TABLE III-3 (continued)
Estimated Average and High-end Emission Rates for Products of Incomplete
Combustion (PICs) and Residues of Organic Compounds
Substance
Methoxychlor
Methylene chloride
Methylnaphthalene* 2-
Methyl-tert-butyl ether
Methyl-2-Pentanone, 4-
Monochlorobiphenyl
Naphthalene
Nitroaniline, 2-
Nitroaniline, 3-
Nitroaniline, 4-
Nitrobenzene
Nitrophenol, 2-
Nitrophenol, 4-
N-Nitroso-di-n-butylamine
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/sec)
Average
5.50 x lO'7
3.96 x ID"4
4.18 x 10-5
1.25 x 10-'
1.25 x 10'5
1.67x 10-8
5.50 x 10-6
6.69 x 10-*
6.69 x 10-*
6.69 x 10-*
5.50 x 10-*
6.69 x 10"*
5.50 x 10-*
1.21 x 10-"
6.69 x 10-*
6.69 x 10"6
1.40x 10-"
1.40x 10-8
4.76 x 10-5
1.40x 10-8
3.37 x 10 5
5.50 x 10-6
6.69 x 10-6
5.50 x 10-*
5.50 x 10-*
1.15x 10-4
2.25 x lO'5
1.40 x lO'8
5.50 x 10-6
5.50 x 10-*
5.13 x lO'5
6.80 x 10-*
High-end
1.10x10"*
6.19x 10-"
4.18x 10-5
2.50 x 10-5
2.50 x 10'5
2.99 x 10-8
l.lOx 10'5
6.69 x 10-*
6.69 x 10'*
6.69 x 10-*
l.lOx 10-'
6.69 x 10'6
l.lOx 10-5
1.21 x 10-4
6.69 x 10-*
6.69 x ID'6
2.80 x 10-8
2.80 x ID'8
4.76 x lO'5
2.80 x 10-8
3.37 x 10-5
l.lOx 10'5
6.69 x 10-*
l.lOx 10-5
LlOxlO-5
1.15 x KT1
4.04 x 10'5
2.80 x 10-8
l.lOx 10-'
l.lOx 10-5
8.02 x 10'5
6.80 x 10-*
Source
b
b
a
b
b
b
b
a
a
a
b
a
b
a
a
a
b
b
a
b
a
b
a
b
b
a
b
b
b
b
b
a
Volume I
m-i2
External Review Draft
Do not cite or quote
-------
TABLE III-3 (continued)
Estimated Average and High-end Emission Rates for Products of Incomplete
Combustion (PICs) and Residues of Organic Compounds
Substance
Toluene
Trichloro- 1 ,2 ,2-trifluoroethane , 1,1,2-
Triehlorobenzene , 1,2,4-
Trichlorobiphenyl
Trichloroethane, 1,1,1-
Trichloroethane, 1,1,2-
Trichloroethene
Trichlorofluoromethane
Trichlorophenol, 2,4,5-
Trichlorophenol, 2,4,6-
Vinyl acetate
Vinyl chloride
Xylene, m-°
Xylene, o-
Xylene, p-c
Emission Rate (g/sec)
Average
6.13 x 10-*
3.30 x 10^
5.50 x 10-*
3.02 x 10-8
1.25 x 10'5
1.25 x 10-5
1.86x 10-5
2.45 x 10*
5.50 x 10"*
5.50 x 10-*
6.43 x 10'5
2.45 x 10^
3.80 x 10*
5.50 x 10-*
3.80 x 10^
High-end
1.03 x lO'3
3.30 x 10*
l.lOx 10*
5.80 x 10-"
2.50 x 10-5
2.50 x 10 5
3.09 x 10 5
4.90 x 10*
l.lOx 10 5
l.lOx lO'5
6.43 x 105
4.90 x 10-4
5.64 x 10*
l.lOx 10s
5.64 x 10*
Source
b
a
b
b
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 apply to the 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 I
ni-13
External Review Draft
Do not cite or quote
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TABLE ra-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 (99.977b)
99.9907
99.987
99.99932
NA (99.977b)
99.99
Oc
NA (99.977b)
99.68
NA (99.977b)
NA (99.977b)
NA (99.977b)
Feed Rate
(lb/hr)
140
0.24
1.3
5:3
0.0028
0.96
0.83
3.2
3.4
0.011
0.17
1.2
0.52
1.7
4.2
Feed Rate
(g/sec)
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/sec)
2.4 x 10-*
4.2 x 10-6
3.7 x 10-5
1.5 x 10^
3.3 x 10-8
1.6 x 10-5
7.1 x ID'7
9.4 x lO'5
4.3 x 10'5
1.4x 10'3
5.0 x 10-6
4.7 x 10"4
1.5 x 10-5
3.4 x 10-5
1.2x 104
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
m-14
External Review Draft
Do not cite or quote
-------
TABLE m-5
Estimated Average Acid Gas and Particulate Matter
Emission Rates
Substance
Hydrogen Chloride (HC1)
Nitrogen Oxides (NOJ
Sulfur Oxides (SOX)
Particulate Matter
Average Emission Rate
(g/sec)
0.032
2.4
0.091
0.07
Notes:
Particulate matter emission rate based on measurements at WTI during
trial burns and performance test.
HC1 emission rate based on measurements from the trial burns.
SOX and NO, emission rates based on one month of continuous stack
monitoring data collected in 1995.
Volume I
m-15
External Review Draft
Do not cite or quote
-------
TABLE m-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 Cyanide
Frequency
of
Detection
1/12
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
<0.5 - 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
0.7
0.2
0.3
0.4
Emission Rate
(g/sec)
1.37 x 10-6
6.75 x 1C'7
2.86 x 10-5
1.45 x ID'5
2.92 x 10-7
8.23 x 10-8
1.04 x ID'7
1.41 x 10-7
Notes:
< - Lower end of concentration range is the lowest detection limit from samples in which analyte was
not detected above detection limit.
Volume I
ra-16
External Review Draft
Do not cite or quote
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o\acad\013999GM3999GBl
^\
V"S<\ \
, Wast* Water
/ Treatment
Bldg.
V--\ Bld«-_V
^ V"' s»ack
Wast* Water
Tanks
Truck Unloading
Station
Organic Waste
Tank Farm
Existing
Maintenance
Bldg.
FUGITIVE EMISSION SOURCES;
1 Tank farm
2 Wastewater tank
3 Truck wash
4 Carbon adsorption bed
5 Ash loading
NOTE: Not to scale
Based on VonRoll DrawlngI c-01 -1-00001
LOCATION OF STACK, FUGITIVE ORGANIC VAPOR, AND ASH EMISSION SOURCES
Figure
III 1
-------
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 hi soil, vegetation, livestock,
surface water, and fish. These concentrations are a starting point for estimating exposures
for 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 tune. These conditions may potentially limit
dispersion and transport of facility emissions, and may result in the accumulation of
pollutants hi 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.
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 tunnel simulation of
conditions in the vicinity of the WTI facility.
Volume 1 External Review Draft
IV-1 Do not cite or quote
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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 diameter, 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 hi 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.1 The U.S. EPA recommended procedures on intermediate terrain are
also 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.
1 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.
Volume 1 External Review Draft
IV-2 Do not cite or quote
-------
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 WTI
property. Data are available for the time period April 1992 through March
1993 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 facility 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
gravitational settling, inertial impaction, and Brownian diffusion) and wet deposition of
particles (due to scavenging by precipitation) are evaluated using the ISC-COMPDEP
model.
Volume 1 External Review Draft
IV-3 Do not cite or quote
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The dry deposition flux depends on the pollutant concentration in air and the
"deposition velocity." The deposition velocity for particles 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 hi 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
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.
Volume 1 External Review Draft
IV-4 Do not cite or quote
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4. Wind Tunnel Simulations
A series of wind tunnel simulations were performed at U.S. EPA's Fluid Modeling
Facility to evaluate the potential for terrain-induced downwash at the site 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 paniculate 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 particulate 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.
C. Results
A total of 13 sets of simulations of the main incinerator stack are conducted with the
ISC-COMPDEP model, corresponding to three different pollutant distributions:
Vapor phase emissions;
Volume 1 External Review Draft
IV-5 Do not cite or quote
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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.
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 hi ISC-COMPDEP
does not allow for the plume trajectory to deviate from a straight line.
Volume 1 External Review Draft
IV-6 Do not cite or quote
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Calm winds and fumigation - The ISC-COMPDEP model does not account for
calm conditions or fumigation associated with inversion break-up events.
Application of a non-steady-state model (CALPUFF) 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.
Particle 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) particles, thereby contributing some uncertainty to
the deposition modeling results.
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TABLE IV-1
Stack Parameters for the WTI Incinerator Stack
Parameter
Stack height
Stack diameter
Exit velocity
Exit gas temperature
Stack base elevation
Value
45.7m
1.83m
17.74 m/s
367.0 K
212.1 m
(150 ft)
(6ft)
(58.2 ft/s)
(201 °F)
(696 ft)
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Table IV-2
Source Characteristics for Fugitive Emission Sources
Point Sources
Description
Ash Handling
Organic Wastetank Farm
Vent#l
Vent #2
Vent #3
Vent #4
Carbon Adsorption Bed
A*
(m)
23.89
173.47
193.12
199.30
179.65
61.02
Y
(m)
48.98
108.45
116.90
102.31
93.99
42.83
Stack
Height
(m)
6.706
18.9
18.9
18.9
18.9
28.04
Temperature
(deg. K)
310.
310.
310.
310.
310.
250.
Exit Velocity
(m/s)
0.1
0.1
0.1
0.1
0.1
31.05
Diameter
(m)
0.1
0.1
0.1
0.1
0.1
0.762
Volume Sources
Description
Open Wastewater Tank
Truck Wash
Jf
(m)
177.06
100.16
r
(m)
204.76
170.91
Height
(m)
5.3
3.048
Initial
CT>
2.35
1.77
Initial
CT,
4.96
2.84
Coordinates are relative to the origin (0.0, 0.0) located at main incinerator stack. Coordinates
are oriented relative to true north.
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Table IV-3
Summary of ISC-COMPDEP Modeling Results for the WTI Main Incinerator Stack
Annual Simulation (April 1, 1992 to March 31, 1993)
All Results Are Based on Unit Emission Rate (1 g/s)
Run No.
la
Ib
Ic
2a
2b
2c
3a
3b
4a
4b
5a
5b
5c
Model
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
ISC-COMPDEP
Run Description
Base Case
Base Case
Base Case
GEP Ht. Stack
GEP Ht. Stack
GEP Ht. Stack
9-yr High
Precipitation
9-yr Low
Precipitation
Turbulence-based
Sigmas
Pollutant
Distribution
Mass
Surface Area
Vapor
Mass
Surface Area
Vapor
Mass
Surface Area
Mass
Surface Area
Mass
Surface Area
Vapor
Maximum
Concentration
(Hg/m3)
.9128 (1 km, 100°)
.9111 (1 km, 100°)
.9144 (1 km, 100°)
.8077 (1 km, 100°)
.8057(1 km, 100°)
.8098 (1 km, 100°)
.9126(1 km, 100°)
.9108 (1 km, 100°)
.9131 (1 km, 100°)
.9115(1 km, 100°)
.9207 (1 km, 100°)
.9190 (1 km, 100°)
.9223 (1 km, 100°)
Maximum
Deposition Flux
(g/mVyr)
.2213 (0.1 km, 80°)
.3052(0.1 km, 80°)
~
.1655(0.1 km, 80°)
.2254(0.1 km, 80°)
~
.2653 (0.1 km, 80°)
.3653(0.1 km, 80°)
.1505(0.1 km, 80°)
.2080(0.1 km, 80°)
.1733 (0.1 km, 100°)
.2394(0.1 km, 90°)
"
Receptor
Average
Concentration
(Hg/m3)
.1018
.1013
.1024
.0830
.0826
.0836
.1017
.1012
.1019
.1014
.1018
.1014
.1024
Receptor
Average
Deposition Flux
(g/m2/yr)
.0123
.0168
--
.0121
.0164
--
.0145
.0196
.0087
.0120
.0121
.0164
~~
Total (Wet and
Dry) Average
Deposition
Velocity (cm/s)
.38
.53
~
.46
.63
-
.45
.62
.27
.38
.38
.51
~
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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/m2/s)
Run No.
8c
9c
lOc
lie
12c
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
(ug/m3)
3.801" (0.8 km, 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°)
143.56b(0.1 km, 40°)
288.70' (0.2 km, 40°)
a Based on an emission rate of 1 g/s.
b Based on an emission rate of 1 g/s per stack (four stacks in run)
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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 facility.
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.
In applying this four-step process, U.S. EPA guidance is relied upon in conjunction with
site-specific information to the extent possible. The general approach used in the HHRA
provides estimates of:
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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 hi 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;
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Toxicitv. considering both carcinogenic and noncarcinogenic effects; and
Bioaccumulation potential, a measure of the extent to which a chemical is likely
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 hi incinerator fly ash are selected for
evaluation.
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.
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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 hi 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 consultation with U.S. EPA. For example, for
poly chlorinated 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
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 19930 is also used to estimate SF values for several polycyclic
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.
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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 hi 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 of 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.
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;
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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;
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.
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 WTI
facility, 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
dry deposition of particulate matter and vapor onto soil and vegetation, and subsequent
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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 hi 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 experienced by "typical" individuals in the exposed population (i.e., those
approximately 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.
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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 hi 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 hi 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 ingestion 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 facility 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
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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.
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:
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.
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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 1Q-6, for the subsistence farmer adult and
child). Exposure to PCDD/PCDF accounts for most of the estimated risk.
In order to assess the variability in exposure to the subsistence farmer, high-end
exposures are estimated for this subgroup. The high-end exposure for the
subsistence farmer is estimated to be approximately 7 hi 1,000,000 (7 x 10'6).
Of the subgroups for which specific activity patterns were evaluated (including
adults and children with home gardens, breast-feeding infants, subsistence
fishermen, and deer hunters), breast-feeding infants of subsistence farmers
account for the highest risks. The estimated average cancer risk for this
subgroup in Subarea El is approximately 2 in 1,000,000 (2 x 10"6).
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.
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 10-6).
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)
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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.
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 uncertainty
due to differences hi 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 hi this process. In addition, additivity may not apply to
noncarcinogens that do not affect the same target organ. Finally, mechanisms
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governing antagonistic or synergistic responses are not well understood, so that the
cumulative risk from multiple chemical exposures is not well defined.
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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
Carbon tetrachloride
Di(n)octyl phthalate
Heptachlor
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclopentadiene
Hexachlorophene
Dioxin Congeners (7)
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
Benzo(b)fluoranthene
Benzo(a)pyrene
Dibenz(a,h)anthracene
Indeno(l ,2,3-cd)pyrene
Furan
2,3,7,8-TCDF
1,2,3,7,8-PeCDF
2,3,4,7,8-PeCDF
1,2,3,4,7,8-HxCDF
1,2,3,6,7,8-HxCDF
Heptachlorobiphenyl
Hexachlorobiphenyl
Tetrachlorobiphenyl
Congeners (10)
1,2,3,7,8,9-
2,3,4,6,7,8-
1,2,3,4,6,7,8
1,2,3,4,7,8,9
OCD
HxCDF
HxCDF
-HpCDF
-HpCDF
F
Metals (13)
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium (hexavalent)
Lead
Mercury2
Nickel
Selenium
Silver
Thallium
Zinc
Notes:
a - Includes methylmercury in aquatic environments
CDD - chlorodibenzo-p-dioxin
CDF - chlorodibenzofuran
Working Draft No. 2
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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
Pyridine
Working Draft No. 2
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TABLE V-3
Exposure Populations and Pathways Considered in the Risk Assessment
Exposure
Pathway
Air Inhalation
Soil Ingestion
Dermal Contact with Soil
Locally Raised Meat
Milk and Milk Products from Locally
Raised Cows
Homegrown Vegetables
Surface Water Ingestion
Dermal Contact with Surface Water
Exposure Population
Resident
Adult
X
X
X
X
X
NAd
X
X
Child"
X
X
X
X
X
NAd
X
X
School
Child"
X
X
X
X
X
NAd
X
X
Farmer
Adult
X
X
X
X
X
X
X
X
Child-
same as CR
same as CR
same as CR
X
X
X
same as CR
same as CR
Subsistence Farmer
Adult
same as AF
same as AF
same as AF
X
X
X
same as AF
same as AF
Child-
same as CR
same as CR
same as CR
X
X
X
same as CR
same as CR
Specific Activities Evaluated
Consumption of Homegrown Fruits and Vegetables (Adult and Child Residents and School-age Children)
Consumption of Locally Caught Fish by Subsistence Fishermen
Consumption of Mothers' Milk by Breast-feeding Infants0
Consumption of Meat from Locally Hunted Deer
Notes: a - assumed to be in 1 to 6 year-old age range.
NA - Not applicable b - assumed to be in 7 to 12 year-old age range.
X - Unique exposure assumptions are required c - assumed to be less than 1 year old.
CR - Child resident d - Consumption of homegrown fruits and vegetables is evaluated separately for
AF - Adult farmer residents with home gardens.
Volume I
V-15
Working Draft No. 2
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TABLE V-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 Adult
Subsistence Farmer Child
Cancer Risks
2 x lO'7
4 x lO'7
6 x lO'7
6 x 10-7
3 x lO'7
1 x 10-*
1 x 10-«
Hazard Indices
1 x lO'2
5 x 10'2
1 x 102
6 x lO'2
3 x lO'2
2 x 10'2
7 x 10'2
Volume I
V-16
Working Draft No. 2
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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 from
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, Region 5 (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 concern those Ecological Chemicals of
Concern (ECOCs), exposure pathways, and ecological receptors that do clearly not
represent a significant contribution to overall risks;
Where potentially significant risks are identified, provide direction regarding further
evaluations hi 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 the human health risk assessment, an ecological
assessment must often consider risks to a diverse community comprising multiple species.
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 many
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species and chemical constituents. Ecological assessments are usually qualitative or
semiquantitative, 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 a 20-kilometer radial distance
encompassing a 1,260 square kilometer (km2) area surrounding the WTI facility. The typical
biota present hi the assessment area are identified and representative species or species
groups are selected 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 facility
emissions. Any potentially significant risks identified hi 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
paniculate 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 hi Table VI-1. However, as in the HHRA, a subset of surrogate organic
chemicals of primary concern 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 hi three parts:
Evaluation based on major types of exposure;
Evaluation based on chemical group; and
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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;
Toxicitv. based on available toxicological data for terrestrial animals and/or
aquatic organisms, depending on the exposure type and/or chemical group
evaluated.
Bioaccumulation potential, as represented by the octanol/water partition
coefficient (K^); and
After selecting organic chemicals based on the scoring algorithm, additional chemicals
are added as ECOCs based on professional judgement. Chemical persistence is
considered hi 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 for 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 organic ECOCs for fugitive vapor emissions, different scoring
algorithms than the ones developed for incinerator stack emissions are used. Since the
constituents present in fugitive vapor emissions are anticipated to 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 K^ values; and
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Toxicitv to terrestrial animals (via inhalation) and/or aquatic organisms (via
surface water exposures).
The scoring system is supplemented with consideration for types of chemicals,
persistence, and bioaccumulation. Based on this process, eight chemicals are selected as
organic fugitive 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 ash emissions. Thus, seven metals (arsenic, barium, cadmium, lead,
nickel, selenium, silver) and cyanide are evaluated in the SERA for this emission source.
C. Characterization of Exposure
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.
For organic ECOC incinerator emissions, a scenario based on high-end emission
rates (i.e., 95% upper confidence limit values) is evaluated. In contrast, the HHRA
relied 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 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.
For metal ECOCs in incinerator stack emissions, two separate scenarios are
evaluated:
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 "expected" scenario, uses the same emission rates as those
used in the HHRA.
The second scenario for metal ECOCs involves an assumption that the
incinerator is operating continuously at its current maximum permitted metal
emissions limits. This is termed the "permit limit" scenario. The existing
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 "permit limit" and "expected"
scenario metal emission rates is presented in Table VI-1.
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For fugitive emissions of fly ash metals and cyanide (fugitive inorganic scenario)
and organic vapors (fugitive organic scenario), potential ecological exposures at the
point of maximum air concentration for each of the five fugitive sources (four vapor
one ash) are evaluated.
For each of the incinerator stack scenarios, predicted maximum concentrations of the ECOCs
in air, surface soil, surface water, and sediment are used hi the SERA as exposure point
concentrations. These environmental media concentrations are evaluated at the projected
locations of maximum air concentrations (on-site or off-site), 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 for the SERA. Tissue concentrations hi representative
food items are modeled to evaluate potential food chain effects hi wildlife.
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
concentrations for fly ash emissions are evaluated for all media/pathways in the same manner
as stack emissions. Exposures are estimated at the projected location of maximum air
concentrations and in the potential location of maximum metal deposition.
Exposure pathways for the ecological receptors to chemicals in the different
environmental media are shown hi 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 any of four major exposure routes:
Direct inhalation of vapor-phase chemicals, or of chemicals adsorbed to paniculate
matter;
Direct ingestion of soil and sediment;
Dermal contact with soil and sediment; and
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 by air or
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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 taxonomic groups or life history traits hi 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 shown in Figures
VI-1 and VI-2, the following indicator species or species groups are selected for evaluation
hi 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.
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 are outside the 5-kilometer radius, except for two fish species recorded
outside the 1 kilometer radius, and within the 5-kilometer radius.
E. Characterization of Effects
In assessing potential adverse effects to indicator species, chronic toxicological
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
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reproduction endpoints were obtained, if available. Growth and reproduction are emphasized
as toxicological endpoints because they are the most relevant, ecologically, to maintaining
viable populations, and because they are generally the best studied chronic exposure
endpoints for ecological receptors. Where chronic NOAEL values are not available,
estimates are derived from chronic Lowest-Observed-Adverse-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
Federal AWQC values. Benchmark values for aquatic biota exposed to chemicals in
sediments were 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 potentially moderate
to high magnitude risks (the magnitude of the hazard quotient 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 toxicity 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 organic emissions from the incinerator stack, low to negligible ecological risks
are indicated.
For metal emissions from the incinerator stack under the "expected" emission
scenario, low to negligible ecological risks are indicated.
For metal emissions from the incinerator stack under the "permit limit" emission
scenario, risks of moderate to high magnitude are indicated for terrestrial plants and
animals (including wildlife). The largest exceedances of toxicological benchmark
values are calculated for thallium, selenium, and nickel. Lower magnitude risks are
indicated for aquatic biota for one metal (silver).
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For fugitive organic vapor emissions, except for formaldehyde, low to negligible
ecological risks are indicated. For formaldehyde, cumulative hazard quotients
exceed one (HQ 2.3) for wildlife from inhalation exposure.
Low to negligible ecological risks are indicated for metals in fugitive ash emissions.
In summary, the SERA indicates low to negligible ecological risks for routine emissions
of organic chemicals (except formaldehyde in fugitive emissions) and for expected emission
of metals. The formaldehyde exposure levels 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 "permit limit" scenario for incinerator stack metal emissions suggests
that valued resources could be adversely impacted if the incinerator emits metals continuously
at the allowable maximum hourly level. Although this is considered unlikely, it is
theoretically and legally possible. Quantifying the likelihood and the possible extent of these
potential effects for the indicator species for which hazard quotients exceed one, as well as a
more in-depth assessment of the potential risks to rare, threatened, and endangered species,
would require evaluation at the Preliminary Ecological Risk Assessment (PERA) or Detailed
Ecological Risk Assessment (DERA) level.
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 as a result of 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 hi deriving
estimates of emission rates, dispersion factors, deposition rates, contact rates, uptake rates,
ecotoxicological endpoints, and uncertainty factors. Values are chosen hi an attempt to
generally model upper-bound exposures and lower-bound toxicological benchmarks such that
risks are not underestimated.
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The SERA meets the objective of separating those ECOCs, exposure pathways, and
receptors that clearly do not significantly contribute 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.
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TABLE VI-1
Metals Evaluated in the SERA - Stack Emissions
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
"Permit Limit"
Emission Rate
(g/sec)
1.6x 10"
1.1 x 10-4
5.5 x 101
3.6 x 10-6
1.9 x 10"
1.5 x 10"
1.2x lO'3
8.8 x lO'2
2.2 x 101
4.4 x 10°
3.3 x 10°
5.5 x 10'1
"Expected" Emission
Rate
(g/sec).
2.4 x 10"
4.2 x 10-6
3.7 x lO'5
1.5 x 10"
3.3 x 10-8
1.6 x lO'5
7.1 x ID'7
9.4 x lO'5
4.3 x ID'5
1.4 x 10'3
5.0 x 10"6
4.7 x 10"
1.5 x 1C'5
3.4 x 10-5
1.2 x 10"4
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VI-10
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TABLE VI-2
Organics to be Evaluated in the SERA-
Stack Emissions
Chemical
Acetone
Acrylonitrile
Anthracene
Benzo(a)pyrene
Bis(2-ethylhexyl)phthalate
Chloroform
Crotonaldehyde
2,4-D
4,4'-DDE
Di(n)octyl phthalate
1 ,4-Dioxane
Formaldehyde
Heptachlor
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclopentadiene
Hexachlorophene
Pentachlorobenzene
Pentachlorophenol
Total PCBs
Total dioxins/furans (TEQ)
Vinyl chloride
High End
Emission Rate
(g/sec)
2.90 x IO-3
2.02 x 10"
l.lOxlO'5
l.lOx lO'5
5.23 x IO-5
4.07 x 10* ,
1.39x 10*
3.88 x IO-5
l.lOx ID"6
l.lOx 10'5
4.94 x 10"
6.07 x 10"
l.lOxlO-6
l.lOx 10'5
1.01 x 10"
l.lOx 10s
3.20 x ID'5
4.76 x 10'5
1.10 x 10s
3.38 x 1C'7
1.26xlO-9
4.90 x 10"
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OUANTUM105MB:PROJECTS'01-4000A-CONCEPTUAL MODEL-STACK EMISS2
SOURCES
EXPOSURE PATHWAYS
FYPfi^tlPP
poUT£s
Foliar uptake-
Root
absorption
Contact/_
ingestion
ingestion
Contact-
Contact
Contact
Contact
RECEPTORS
Birds
Mammals
Plants
-^Herbivores
Earthworms Wnsectivores
Birds
Mammals
Carnivores
I
^ Aquatic
T^ Plants
Aquatic
" ^
invertebrates ^s^
Zooplankton Fish
Piscivores
Fish
I ^ Aquatic
*"^" Plants "
Fish
Benthic
invertebrates
Fish
.
Piscivores
DIAGRAMMATIC CONCEPTUAL SITE MODEL FOR THE WTI SERA - STACK EMISSIONS
Volume
Figure
VM
-------
QUANTUM105MB:PROJECTS:01-4000A:CONCEPTUAL MODEL-FUGITIVE EMIS2
SOURCES
Organic fugitive ECOCs
summed across
four:
Fugitive ash ECOCs
Air
EXPOSURE PATHWAYS
"^ Dispersion
Ground-
^- level
air
Surface
water
Sediment
RECEPTORS
f
Inhalation
Birds
Mammals
Foliar uptake
Contact
^ Contact
Inhalation
Foliar uptake -
Root
absorption
Contact/_
ingest ion
^
Aquatic biota
Aquatic biota
Birds
Mammals
Plants
>> Plants
-^Herbivores
Carnivores
| ingestion |
Birds
Mammals
' ^ I ^ Aquatic
T^ Contact T^ plants ~
I Aquatic
Earthworms ^Hnsectivores
Fish
invertebrates^.^
Zooplankton
Fish
Piscivores
n-
Piscivores
DIAGRAMMATIC CONCEPTUAL SITE MODEL FOR THE WTI SERA - FUGITIVE EMISSIONS
Volume 1
Figure
Vj.2
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VH. 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; 1995c) 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, 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 inversions) are evaluated, 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
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.
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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. Information on incidents occurring between 1977 and May 1995
was reported for 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 tune 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.
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 facility, and a
site visit, the following general scenarios are selected for quantitative evaluation in the
Accident Analysis:
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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 significant off-site consequences; and (2) probability of occurrence, i.e., the
potential 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 hi 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:
Projected waste composition during the first year of operation, based on waste
profiles from WTI;
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).
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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 toxicitv. as represented by Immediately Dangerous to Life or Health (IDLH)
values established by the National Institute for Occupational Safety and Health
(NIOSH);
Volatility, as represented by the vapor pressure of the chemical; and
Concentration, as estimated based on data reported in waste profiles supplied by
WTI.
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 (HCI) is selected in the Accident Analysis. Phosgene and
HCI are selected based on high acute toxicity, and the likelihood that they could be produced
during combustion of chlorinated wastes. In both the 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.
For the on-site mixing of incompatible waste scenarios, HCI 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), HCI 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 HCI emissions.
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£. 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.
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 potentially 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 immediately
after 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
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rupture of the container (FEMA 1993). For the scenarios considered in the Accident
Analysis, there is a very low likelihood 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 ah- 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:
Typical Meteorological Conditions. Typical meteorology at the WTI facility is
determined to be neutral atmosphere with average windspeed (3.2 m/sec).
Conservative Meteorological Conditions. To determine the appropriate conservative
meteorology 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/sec,
and stability Category F.
Calm/Inversion Meteorological Conditions. Calm/inversion meteorology is
considered the most stable condition that could occur at the WTI site, and thus
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results in the highest off-site concentrations in ah- in the event of an accidental
release. This hypothetical meteorology assumes emissions accumulate in air
immediately above the source for one hour during calm conditions and stable
meteorology, and then are carried off-site under low wind speeds. This approach is
consistent with the approach used to evaluate calm/inversion condition 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. The ISC-COMPDEP model is not appropriate for
use when calculating atmospheric dispersion under calm/inversion conditions because the
Gaussian equation assumption used hi ISC-COMPDEP is invalid. As with the SLAB model,
30-minute average concentrations were calculated from the ISC-COMPDEP model results.
G. Evaluation of Severity of Consequence and Probability 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 for each scenario is ranked as minor, moderate, major, or catastrophic, based
on the distance over which predicted concentrations hi potentially inhabited areas could
exceed the NIOSH IDLH values.
FEMA (1993) presents a four-tier system for classifying the consequences of accident
scenarios. This system has been used as the basis for developing the following severity of
consequence categories in the Accident Analysis:
Minor No exceedance of an 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 areas over distances of
100 meters or less; injuries due to heat effects limited to a distance
of 1,000 meters into inhabited areas.
Major Exceedance of IDLH values hi inhabited 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.
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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
(1995b), 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 of 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 in these terms based on the probability of the
accident event, the probability of the meteorological conditions, and an estimated waste
composition based on the WTI waste profile information. The probability of occurrence
rankings developed hi the Accident Analysis correspond to broad classes of accidents, rather
than individual events.
The severity of consequence and probability of occurrence results from the on-site
scenarios are summarized hi Table VII-2. As shown hi Table VII-2, the evaluation of
consequences using the above criteria for the on-site events results in the following:
Events considered likely to occur produce only off-site consequences considered
minor:
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Events considered reasonably likely to occur produce off-site consequences
considered minor or moderate:
Events with potentially major off-site consequences are considered unlikely to occur;
and
Events with potentially catastrophic off-site 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;
x
Off-site accidents 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
at 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 consequences would be classified as
unlikely or very unlikely over a facility lifetime. The probability of an event having minor
consequences would be classified as likely or reasonably likely. This generally agrees with
the consequence probability rankings for the scenarios developed specifically for the WTI
facility in the Accident Analysis.
H. Uncertainties
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
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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.
In the Accident Analysis, NIOSH IDLH values are used to evaluate the downwind distance
over which adverse human health effects might be anticipated in the event of an accident.
To determine the effect of using a more stringent measure of potential health effects, a
sensitivity analysis is conducted using U.S. EPA Level of Concern (LOG) values, which are
lower than the IDLH values. In addition, the effect of shorter concentration averaging times
in making comparisons to IDLH values is examined in a sensitivity analysis.. As expected,
exceedances of LOG values extend to greater distances than exceedances of IDLH values, in
some cases by up to three or four-fold. Averaging time is predicted to have less effect on
the results of the analysis.
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 media, chemicals, populations, pathways, data and models used hi 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 rates (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 hi 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.
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 very quickly, i.e., within 10 minutes of the accident event. As expected, failure of
passive mitigation (e.g., failure of dikes at the same tune an accident occurs) would increase
the potential for off-site consequences.
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TABLE VIM
Scenarios Selected for Quantitative Evaluation
Scenario
On-Site Spill
On-Site Fire
On-Site Mixing of Incompatible
Wastes
Off-Site Spill
Off-Site Fire
Description
Conservative Event
5,000-gallon spill due to a tanker truck
accident, resulting in volatile emissions
20,000-gallon spill in the Organic Waste
Tank Farm ignites, generating toxic products
of combustion
Accidental pumping of 5,000 gallons of
wastes from a tanker truck to a storage vessel
containing 5,000 gallons of an incompatible
waste, generating toxic gases
5,000-gallon spill along local access road,
resulting in volatile emissions
5,000-gallon spill ignites, generating toxic
products of combustion
Typical Event
100-gallon spill due to tanker truck
accident, resulting in volatile emissions
200-gallon spill ignites, generating toxic
products of combustion
200-gallons of incompatible wastes are
mixed, generating toxic gases
100-gallon spill along local access road,
resulting in volatile emissions
100-gallon spill ignites, generating toxic
products of combustion
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TABLE VII-2
Severity of Consequence and Probability of Occurrence Results for On-Site Scenarios
Scenario
t
On-Site Spill
5,000-gallon spill
Formaldehyde Waste
Acetone Waste
100-gaIlon spill
Formaldehyde Waste
Acetone Waste
On-Site Fire
20,000-gallons of waste
200 gallons of waste
Mixing of Incompatible Wastes
10,000 gallons
200 gallons
Meteorological Conditions
Typical | Conservative
Severity of
Consequence
Major
Minor
Moderate
Minor
Minor'
Minor2
Major
Minor
Probability of II Severity of
Occurrence Consequence
Unlikely
Reasonably Likely
Reasonably Likely
Likely
Unlikely
Reasonably Likely
Unlikely
Reasonably Likely
Catastrophic
Minor
Major
Minor
Minor1
Minor2
Catastrophic
Major
Probability of
Occurrence
Very Unlikely
Unlikely
Unlikely
Reasonably Likely
Very Unlikely
Unlikely
Very Unlikely
Unlikely
Calm/Inversion
Severity of
Consequence
Catastrophic
Minor
Major
Minor
NE3
NE
Catastrophic
Major
Probability of
Occurrence
Very Unlikely
Unlikely
Unlikely
Reasonably Likely
Very Unlikely
Unlikely
Very Unlikely
Unlikely
Notes:
1 On the bases of potential HC1 and phosgene emissions and heat effects, the conservative fire is judged to have minor consequences. If a fireball were to form, the
consequences would be classified as major, but the probability of occurrence is very unlikely.
2 On the bases of potential HC1 and phosgene emissions, heat effects and assumed fireball formation, the typical fire is judged to have minor consequences.
3 NE: Not Evaluated.
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TABLE VII-3
Severity of Consequence and Probability of Occurrence Results for Off-Site Scenarios
Scenario
Off-Site Spill
5,000-gallon spill
Formaldehyde
Acetone
100-gallon spill
Formaldehyde
Acetone
Off-Site Fire
5,000 gallons of waste
100 gallons of waste
Meteorological Conditions
Typical
Severity of
Consequence
Major
Minor
Major
Minor
Moderate1
Moderate2
Probability of
Occurrence
Very Unlikely
Unlikely
Unlikely
Reasonably Likely
Very Unlikely
Unlikely
Conservative
Severity of
Consequence
Catastrophic
Moderate
Catastrophic
Minor
Major1
Moderate2
Probability of
Occurrence
Very Unlikely
Very Unlikely
Very Unlikely
Unlikely
Very Unlikely
Very Unlikely
Calm/Inversion
Severity of
Consequence
Catastrophic
Moderate
Catastrophic
Minor
NE3
NE
Probability of
Occurrence
Very Unlikely
Very Unlikely
Very Unlikely
Unlikely
Very Unlikely
Very Unlikely
Notes:
1 On the bases of potential HC1 and phosgene emissions, the conservative fire is judged to have minor consequences under typical meteorology and potentially major
consequences under conservative meteorology. Given the potential heat effects of the fire, the event would be judged to have moderate consequences. If a fireball were
to form, the consequences would be classified as major, but the probability of occurrence is very unlikely.
2 On the bases of potential HC1 and phosgene emissions and heat effects the typical fire is judged to have moderate consequences.
3 NE: Not Evaluated
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M. Shapiro, Director, Office of Solid Waste. Revised April 22.
U.S. Environmental Protection Agency (U.S. EPA). 1994d. Chemical hazard evaluation for
management strategies: A method for ranking and scoring chemicals by potential human
health and environmental impacts. EPA/600/R-94/177.
U.S. Environmental Protection Agency (U.S. EPA). 1994e. Ecological risk assessment
guidance for RCRA corrective action, Region 5. Interim Draft.
U.S. Environmental Protection Agency (U.S. EPA). 1995a. Guidance for risk
characterization. Science Policy Council. February.
U.S. Environmental Protection Agency (U.S. EPA). 1995b. Report on emergency incidents
at hazardous waste incinerators and commercial treatment, storage, and disposal
facilities (TSDFs). Draft. May.
U.S. Environmental Protection Agency (U.S. EPA). 1995c. Accidental release prevention
requirements: Risk management programs under Clean Air Act Section 112(r)(7);
Proposed rule. 40 CFR Part 268. March 13.
West Virginia Agricultural Statistics Service (WVDA). 1994. 7993 Annual Bulletin No. 24.
West Virginia Department of Natural Resources (WVDNR). 1994. Letter from W. Kordek,
Technical Support Unit, to A. Johnston, ENVIRON, regarding deer hunting in West
Virginia. January 11.
Volume 1 External Review Draft
VIII-4 Do Not Cite or Quote
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