United States Solid Waste and EPA530-R-01-005
Environmental Protection Emergency Response March 2001
Agency (5305W) www.epa.gov/osw
&EPA Industrial Surface
Impoundments in the
United States
Printed on paper that contains 50 percent postconsumer fiber
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EPA530-R-01-005
March 2001
Industrial Surface Impoundments
in the
United States
Office of Solid Waste
U.S. Environmental Protection Agency
Washington, DC 20460
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DISCLAIMER
This document has been reviewed in accordance with U.S. Environmental Protection
Agency policy and approved for publication and distribution. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
ACKNOWLEDGMENTS
The authors greatly appreciate the concerted efforts of the many individuals who designed
and implemented this study, and of the many hundreds of survey respondents. This study was
conducted by EPA's Office of Solid Waste, with staff from the Economics, Methods and Risk
Analysis Division and Hazardous Waste Minimization and Management Division, and with
contract support from Industrial Economics, Inc., Research Triangle Institute, and Science
Applications International Corporation.
In memory of the late Oliver Fordham,
who performed the field sampling for this study.
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March 26, 2001 Table of Contents
Table of Contents
Executive Summary ES-1
Chapter 1 Study Background 1-1
1.0 Introduction 1-1
1.1 Previous Studies Defining and Characterizing Surface Impoundments 1-1
1.2 Legal Framework and Issues 1-2
1.2.1 Resource Conservation and Recovery Act - Background 1-2
1.2.2 Clean Water Act - Background 1-4
1.2.3 Clean Air Act - Background 1-5
1.2.4 Interaction of RCRA, CWA and CAA 1-6
1.2.5 Requirements To Conduct This Study 1-7
1.3 Study Purpose 1-8
1.4 Study Scope 1-9
1.4.1 Definition of Surface Impoundment 1-9
1.4.2 Other Scope Decisions 1-9
1.5 Overview of Methodology 1-11
1.5.1 Public Involvement in Study Design and Identification of Data Needs 1-11
1.5.2 Overall Framework of the Risk Assessment 1-12
1.5.3 Representativeness of Facilities in this Study 1-13
1.5.4 Peer Review of Study Components 1-15
1.6 Organization of this Report 1-17
1.7 References 1-18
Chapter 2 Industrial Surface Impoundments 2-1
2.1 Overview of Surface Impoundment Population 2-1
2.1.1 Population of Surface Impoundments 2-2
2.1.2 Location of Surface Impoundments 2-3
2.1.3 Breakdown of Surface Impoundments by Industry 2-4
2.1.4 Surface Impoundment Size and Appearance Characteristics 2-5
2.2 Chemicals and Management Practices at Surface Impoundments 2-6
2.2.1 Data Sources for Chemical Data 2-8
2.2.2 Chemicals Managed in Surface Impoundments 2-11
in
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March 26, 2001 Table of Contents
Table of Contents (continued)
2.2.3 Surface Impoundment Size and Wastewater Volume Characteristics 2-17
2.2.4 Management Practices at Surface Impoundments 2-19
2.3 Factors Related to Transport of Chemicals from Surface Impoundments 2-20
2.3.1 Factors Related to Transport of Chemicals in Air 2-20
2.3.2 Factors Related to Transport of Chemicals in Groundwater 2-22
2.4 Proximity of Humans to Surface Impoundments 2-27
2.4.1 Proximity of Humans to Surface Impoundments by Pathway 2-28
2.5 Regulatory, Exemption/Exclusion, and Operating Status of Surface Impoundments . 2-29
2.6 Conclusions 2-33
2.7 References 2-35
Chapter 3 Human and Ecological Risk Analysis 3-1
3.0 Summary of Chapter 3-1
3.1 Introduction and Overview 3-1
3.1.1 Overview of Methodology 3-1
3.1.2 Overview of Results 3-4
3.2 Direct Pathways (Inhalation and Groundwater Ingestion) 3-7
3.2.1 Methodology 3-7
3.2.2 Screening Results and Proportions of Facilities that May Pose Risks 3-13
3.2.3 Results for Groundwater Ingestion 3-13
3.2.4 Results for Direct Inhalation Pathway 3-19
3.3 Indirect Pathways: Groundwater to Surface Water 3-24
3.3.1 Methodology for Groundwater to Surface Water Pathway 3-25
3.3.2 Results for Indirect Pathway—Surface Water 3-28
3.3.3 Discussion of Uncertainties 3-32
3.4 Other Indirect Pathway 3-34
3.4.1 Methodology 3-34
3.4.2 Results 3-37
3.4.3 Discussion of Uncertainties 3-37
3.5 Ecological Risk Screening 3-40
3.5.1 Methodology 3-40
3.5.2 Results 3-42
IV
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March 26, 2001 Table of Contents
Table of Contents (continued)
3.5.3 Discussion of Uncertainties Associated with Screening Ecological Risk
Analysis 3-44
3.6 Summary and Conclusions 3-46
3.6.1 Summary of Major Risk Analysis Findings 3-47
3.6.2 Findings by Pathway Based on Risk Analysis 3-47
3.6.3 Findings Based on Risk Screening 3-48
3.6.4 Additional Findings of Interest 3.49
Chapter 4 Regulatory/Program Coverage and Gaps Analysis 4-1
4.0 Introduction and Background 4-1
4.1 Regulatory/Program Analysis Methodology 4-1
4.1.1 Approach for Conducting Regulatory/Program Coverage and Gaps
Analysis for Air Risks 4-2
4.1.2 Approach for Conducting Regulatory Program Coverage and Gaps Analysis
for Nonair Risks Found from Managing Nonhazardous Waste in Surface
Impoundments 4-3
4.2 Coverage and Potential Gaps in Existing Programs and Regulations Addressing
Air Risks 4-4
4.2.1 Existing RCRA Rules and Programs That Address Air Risks 4-5
4.2.2 Extent to Which Current RCRA Subtitle C Regulations Address Risks from
Wastes Newly Classified as Hazardous 4-10
4.2.3 Analysis of Coverage and Potential Gaps in CAA Requirements 4-13
4.3 Coverage and Potential Gaps in Existing Programs and Regulations Addressing
Nonair Risks 4-31
4.3.1 Groundwater Risks Found from Managing Nonhazardous Waste in Surface
Impoundments 4-31
4.3.2 Risks to Surface Water from Releases of Contaminated Groundwater to
Surface Water 4-39
4.3.3 Risks Associated with Other Indirect Pathways 4-41
4.3.4 Ecological Risks 4-43
4.4 Role of EPA's Multimedia Strategy for PBT Pollutants in Reducing Risks from
Surface Impoundments 4-43
Chapter 5 Summary and Conclusions 5-1
5.1 Scope of Surface Impoundment Study 5-1
5.2 SIS Requirements 5-1
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March 26, 2001 Table of Contents
Table of Contents (continued)
5.3 Survey and Risk Assessment Findings 5-1
5.3.1 Survey of Industrial Impoundments 5-1
5.3.2 Risk Assessment 5-2
5.4 Regulatory Analysis Findings 5-4
5.4.1 Air Pathway Regulatory Analysis 5-4
5.4.2 Groundwater and Surface Water Pathway Analysis 5-7
5.5 Surface Impoundments Study Conclusions 5-8
5.5.1 Our General Findings 5-8
5.5.2 Specific Findings to Satisfy Consent Decree Resulting from EDF v. Whitman 5-9
5.5.3 Specific Findings to Satisfy LDPFA—RCRA Section 3004 (g)(10) 5-9
5.5.4 Study Conclusion 5-9
Appendix A Study Design and Survey Data Collection and Processing A-l
Appendix B Database Tables B-l
Appendix C Risk Assessment Methodology and Results C-l
Appendix D Regulatory/Program Coverage and Gaps Analysis D-l
Appendix E Field Sampling and Analysis E-l
VI
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March 26, 2001 Table of Contents
List of Figures
1-1 Definition of surface impoundments used in this study 1-10
1-2 Study timeline 1-14
1-3 Selection of facilities for study 1-16
2-1 Distribution of 11,863 impoundments by year until began receiving waste 2-3
2-2 Regional distribution of surface impoundments 2-4
2-3 Surface impoundment located at a fruit processing facility 2-7
2-4 Surface impoundment at a petroleum refinery 2-7
2-5 Surface impoundment at a nylon manufacturing plant 2-8
2-6 Relationship between survey values and corresponding EPA measurements 2-10
2-7 Number of chemicals in wastewater and sludge managed in impoundments 2-12
2-8 Total wastewater quantity and number of impoundments by impoundment size .... 2-18
2-9 Depth to groundwater beneath impoundment by impoundment discharge status .... 2-23
2-10 Number of impoundments and wastewater volumes by liner status 2-24
3-1 Exposure pathways for active surface impoundments considered for human and
ecological receptors 3-3
3-2 Summary of sensitive ecosystem analysis 3-43
4-1 State programs or regulations for the protection of groundwater at nonhazardous
waste surface impoundments 4-37
4-2 Generalized approach for groundwater and surface water pathways
regulatory coverage and gaps analysis 4-6
4-3 State programs or regulations for the protection of groundwater at nonhazardous
waste surface impoundments 4-46
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March 26, 2001 Table of Contents
List of Tables
2-1 Overview of Facility, Impoundment, and Wastewater Quantity Estimates 2-3
2-2 Breakdown by 2-digit SIC Code of Surface Impoundments that Manage
Chemicals/pH of Concern and of Quantities of Wastewater Managed 2-5
2-3 Breakdown of Impoundment Surface Area 2-6
2-4 Constituents Confirmed with Field Sampling and Unreported Constituents 2-11
2-5 Breakdown of Chemical Categories for Wastewater and Sludge (at Different
Sampling Points) on Impoundment and Volume Basis 2-13
2-6 Comparison of 50th and 90th Percentile Influent Wastewater Concentrations with
Toxicity Characteristic (TC) Limits and Health-Based Screening Factors for
Selected Chemicals 2-15
2-7 Co-occurrence of Chemicals in Wastewater by Human Health Effect 2-16
2-8 Facility Breakdown of Treatment Process (Used by at Least One Impoundment) ... 2-19
2-9 VOC/Aeration Status for Impoundments 2-21
2-10 Number and Percentage of Impoundments by Liner Status 2-26
2-11 Monitoring Well/Detection of Releases by Discharger Type 2-27
2-12 Proximity of Surface Impoundments to People, Residences, Drinking Water Wells,
and Schools 2-28
2-13 Proximity of Residences to Impoundments Based on Presence of VOCs and
Aeration Status 2-29
2-14 Proximity of Nearest Wells to Impoundments Based on Linear Status 2-30
2-15 Regulatory, Exempt/Excluded, and Operating Status of Impoundments 2-32
2-16 Breakdown of Exempt/Excluded Wastewaters 2-32
3-1 Overview of Modeling-Level Results 3-5
3-2 Overview of Screening-Level Results 3-6
3-3 Facility-Level Overview of Human Health Results by Decharacterization Status .... 3-8
3-4 Facility-Level Overview of Human Health Results by Discharge Status 3-8
3-5 Overview of Tiered Risk Assessment Methodology for Direct Ingestion of
Groundwater 3-9
3-6 Overview of Tiered Risk Assessment Methodology for the Direct Inhalation of Air . 3-10
3-7 Summary of Screening Process and Risk Analysis Results for Direct Pathways:
Groundwater Ingestion and Air Inhalation 3-14
3-8 Summary of Chemicals and their Maximum of Hazard and Risk Exceedances
for Groundwater Pathway 3-15
3-9 Facility-Level Results for Groundwater Pathway by Decharacterizati on Status 3-16
3-10 Impoundment-Level Results for Groundwater Pathway by Liner Status 3-17
3-11 Maximum Hazard and Risk Exceedances for Air Pathway 3-20
3-12 Facility-Level Results for Air Pathway by Decharacterization Status 3-21
3-13 Impoundment-Level Results for Air Pathway by Aeration Status 3-22
3-14 Overview of Tiered Risk Assessment Methodology for Potential for Adverse
Effects on Surface Water Quality 3-26
3-15 Maximum Exceedances for Groundwater-to-Surf ace Water Pathway 3-29
Vlll
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March 26, 2001 Table of Contents
List of Tables (continued)
3-16 Facility-Level Results for Groundwater-to-Surf ace-Water Pathway by
Decharacterization Status 3-30
3-17 Impoundment-Level Results for Groundwater-to-Surface-Water Pathway by
Liner Status 3-31
3-18 Facility-Level Results for Groundwater-to-Surf ace-Water Pathway by Discharge
Status 3-31
3-19 Overview of Tiered Risk Assessment Methodology for Indirect Pathway
Assessment 3-35
3-20 Chemicals Selected for Inclusion in Indirect Exposure Pathway Ranking Analysis .. 3-36
3-21 Facility-Level Results for Indirect Pathways by Decharacterization Status 3-37
3-22 Facility-Level Results for Indirect Pathways by Discharge Status 3-38
3-23 Overview of Tiered Risk Assessment Methodology for Screening Ecological
Risk Assessment 3-41
3-24 Facility-Level Results for Ecological Risk by Decharacterization Status 3-44
3-25 Facility-Level Results for Ecological Risk by Discharge Status 3-44
4-1 Extent That Constituents Exceeding Risk Criteria for Air Pathways Are HAPs,
VOCs, or Covered by Draft Guide for Industrial Waste Management 4-19
4-2 Potential MACT and NESHAP Requirements Applicable to Surface
Impoundments 4-21
4-3 List of In-Scope 4-Digit SICs and Extent to Which They are Covered by MACT ... 4-21
4-4 Summary of 40 CFR Part 257 Criteria That Potentially Apply to Surface
Impoundments 4-34
4-5 Federal Regulatory or Program Coverage of Constituents with Predicted Risks
Exceeding Risk Criteria for Groundwater Pathway 4-35
4-6 Federal Regulatory or Program Coverage of Constituents with Predicted Risks
Exceeding the Risk Criteria for Groundwater to Surface Water Releases 4-40
4-7 List of Priority PBT Chemicals and Extent to Which They Showed Potential for
Risk 4-44
IX
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March 26, 2001 Executive Summary
Executive Summary
EPA's study, Industrial Surface Impoundments in the United States, originates from the
Land Disposal Program Flexibility Act (LDPFA), an amendment to the Resource Conservation
and Recovery Act (RCRA) enacted in 1996. The LDPFA exempts certain decharacterized wastes
from provisions of the RCRA land disposal restrictions. "Decharacterized" wastes are hazardous
wastes that have had their hazardous characteristics-that is, ignitability, corrosivity, reactivity, or
toxicity-removed through dilution or other treatment. The LDPFA exemption allows
decharacterized wastes to be either: (1) placed in surface impoundments that are part of
wastewater treatment systems whose ultimate discharge is regulated under the Clean Water Act
(CWA), or (2) disposed of in Class 1 nonhazardous injection wells regulated under the Safe
Drinking Water Act. Because of concerns regarding constituents that might remain in the wastes
after removal of the characteristic, Congress required, in the LDPFA, that the Environmental
Protection Agency (EPA) conduct a study "to characterize the risks to human health or the
environment associated with managing decharacterized wastes in CWA treatment systems" and
to "evaluate the extent to which risks are adequately addressed under existing State or Federal
programs and whether unaddressed risks could be better addressed under such laws or
programs."1
Additionally, in 1997 EPA agreed to an amendment to an existing consent decree,
Environmental Defense Fund vs. Whitman, D.C. Circuit, 89-0598 (EDF consent decree), to
include a requirement for a study of air risks from surface impoundments. The amended consent
decree required a study of air risks from several different kinds of waste management units and
an evaluation of gaps in regulatory controls for air risks posed by waste management practices.
The specific part of the air risk consent decree requirement pertaining to surface impoundments
in essence became a complementary study for the LDPFA study, since its time frame for
completion matched the LDPFA study and it imposed similar requirements on EPA-a risk
assessment and evaluation of regulatory coverage. Two of the major differences between the
consent decree requirements and the LDPFA study were the consent decree requirement's focus
on a single route of human exposure to pollutants-the air inhalation route-and the regulatory
status of the wastes required to be studied. While the LDPFA requires a study of nonhazardous
wastes that, at some point in time, exhibited a characteristic of hazardous waste, the consent
decree requires EPA to study nonhazardous wastes that have never been classified as hazardous
wastes. The consent decree also requires EPA to identify potential regulatory gaps in the current
RCRA hazardous waste characteristics and the Clean Air Act (CAA) programs.
This report summarizes EPA's study. It begins by describing the nature and variety of
industrial surface impoundments and the wastewaters they manage. In 1996, when EPA began
1 Congress, in the LDPFA, also required that EPA conduct a study of nonhazardous injection wells. The
results and findings of that study are reported in U.S. EPA, Office of Groundwater and Drinking Water, 2001, Class
I Underground Injection Control Program: Study of the Risks Associated with Class I Underground Injection Wells,
Washington, DC.
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March 26, 2001 Executive Summary
this study, there was limited information on industrial impoundment sizes, designs, and operating
characteristics, and there was limited information on the wastewaters managed in industrial
impoundments. This report, comprising an analysis of survey data, risk analysis, and regulatory
coverage findings, is the result of EPA efforts over the past 5 years to fill information gaps and
meet legislative and consent decree obligations. The report quantifies and describes the potential
risks to human health and the environment posed by chemical constituents present in the
wastewaters managed by industrial surface impoundments. It also identifies existing regulatory
controls and nonregulatory programs that can be used to address potential risks.
Overview of Survey and Risk Assessment Findings
Methodology
EPA estimates that, in the 1990s, there were approximately 18,000 industrial surface
impoundments in use throughout the United States. These surface impoundments were present at
about 7,500 facilities located primarily east of the Mississippi River and in Pacific Coast states.
Because of the scope of the universe, EPA conducted the study focusing on a sample of U.S.
facilities that use impoundments to manage industrial nonhazardous waste. Most of the facilities
selected for the study were chosen randomly to ensure that the sample facilities would be
representative of the facilities in the study population. EPA sent surveys to 221 facilities to
collect information on their impoundments and the wastes managed in them. EPA requested
information on the presence and quantities of 256 chemical constituents in the impoundments, as
well as on the impoundments' design and operation. EPA used these data to characterize the
potential risks that may be posed by managing the wastes in impoundments. The survey
responses on the presence and concentrations of specific chemical constituents were particularly
central to EPA's analysis. EPA also collected and analyzed wastewater and sludge from
impoundments at 12 facilities in the study and used that information to illuminate the
completeness and accuracy of the survey data. EPA also used data from a variety of other
sources such as facility permit files, U.S. Census data, and technical references.
In the first part of this report, EPA presents the survey findings, then the risk assessment
findings. The survey data provide information on the sizes and nature of the industrial
impoundment population, the impoundments' environmental settings, historical summaries of
liner failure and overtopping events, and the impoundments' designs and operating practices.
EPA conducted a risk assessment using the survey data and other sources of data. The risk
assessment consisted of a risk analysis in which EPA developed estimates of the chronic risks
that are potentially posed by three pathways (air, groundwater, and groundwater to surface water)
and a risk screening in which EPA considered the potential for other indirect pathway and
ecological hazards.
EPA conducted the risk analysis and risk screening in stages in order to screen the
thousands of possible data points, focus the analysis where most warranted, and, ultimately,
characterize the potential risks associated with industrial surface impoundments. In the first
stage, EPA applied precautionary exposure assumptions to screen out impoundments of no
concern and identify those that merited additional analysis. In subsequent stages, EPA used data
on actual exposure and used various fate and transport modeling tools to estimate potential risks.
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March 26, 2001 Executive Summary
EPA's risk screening of the other indirect pathways and ecological hazards was similar to the
initial stages of the risk analysis. Thus, the characterization of the other indirect pathway hazards
and ecological hazards developed in this study is less certain than the characterization of risks via
air, groundwater, and groundwater to surface water.
In the risk analysis, EPA used several chronic risk and hazard measures to evaluate
potential threats to human and ecological receptors from chemical constituents managed in
surface impoundments. EPA developed estimates of the excess individual lifetime cancer risk
posed to humans by exposure to carcinogenic chemicals. Chemicals with noncancer health
effects were evaluated using threshold measures of hazard. EPA developed hazard quotients
(HQs), which are the ratio of the dose of contaminant expected at an exposure point to an
appropriate safe reference dose. Other risk measures were also developed for the risk screening
to examine the threats associated with consumption of contaminated fish and with ecological
hazards. In determining what risks were of concern at each stage of the analysis, EPA generally
used a cancer risk of 1 or more in 100,000 and an HQ of 1 or more as the criteria for deciding
whether to retain an impoundment for the next stage of evaluation.
Characterization of Surface Impoundments
In the United States, industrial surface impoundments are an important and widely used
industrial materials management unit. Surface impoundments serve a variety of beneficial uses
in a number of industrial processes. Industrial facilities that produce wastewaters often use
surface impoundments to perform necessary wastewater treatment prior to discharge into surface
waters. In other cases, industrial facilities may need to control wastewater flows and use surface
impoundments for storing excess wastewater. In still other cases, industrial facilities may use
surface impoundments to manage their excess wastewaters through evaporation or seepage into
the ground.
EPA's best estimate is that two-thirds of the 18,000 industrial impoundments in the
United States, or about 11,900 impoundments located at 4,500 facilities, contain at least one of
the 256 chemical constituents that were of interest for this study or contain high (11 to 12.5) or
low (2 to 3) pH wastewater. Surface impoundments are used by many industrial sectors, such as
manufacturing, bulk petroleum storage, air and truck transportation, waste management, and
national security. The wastewaters managed in these surface impoundments are primarily from
manufacturing and washing processes and certain contaminated stormwaters. More than half of
the impoundments with chemical constituents or pH of interest are in the chemical, concrete,
paper, and petroleum industries.
Industrial impoundments vary greatly in size, from less than a quarter of a hectare (1/3 of
an acre) to several hundred hectares. The larger impoundments provide the bulk of the total
national industrial impoundment capacity. On a volume basis, the paper and allied products
sector manages roughly two-thirds of the total quantity of wastewater, more waste in
impoundments than all of the other industry categories combined.
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March 26, 2001 Executive Summary
Industrial impoundments frequently use management techniques that increase the
potential for chemical releases and frequently are found in environmental settings that increase
the potential for impacts to humans or ecosystems in the event of a chemical release. In this
study, EPA found that most industrial impoundments are located only a few meters above
groundwater and that, in most cases, shallow groundwater discharges to a nearby surface
waterbody. More than half of the impoundments do not have liner systems to prevent the release
of wastes to soil or groundwater. In addition, about 20 percent of impoundments are located
within 150 meters of a fishable waterbody, so migration through the subsurface to the nearby
surface water is possible. Finally, while aeration can have certain benefits, it also increases
volatilization and the potential for airborne contaminant migration. EPA found that about
45 percent of the total wastewater quantity managed in impoundments is aerated.
There is potential for people to be exposed to chemical constituents released from
industrial impoundments. EPA estimates that more than 20 million people live within
2 kilometers (or about 1.2 miles) of an industrial impoundment that was in operation during the
1990s, and about 10 percent of the impoundments have a domestic drinking water well located
within 150 meters of the impoundment's edge.
After evaluating impoundment settings and operations and confirming there was potential
for releases, EPA went a step further and conducted a risk assessment to examine the degree to
which the chemicals found in impoundments were likely to be released from impoundments and
ultimately expose people to harmful chemicals.
The results of the survey are presented in Chapter 2. Appendix A outlines the survey
methodology and quality assurance procedures. Appendix B presents more comprehensive and
detailed reporting of results. Appendix E discusses the field sampling effort.
Risk Analysis Findings
EPA is basing its conclusions on two sets of risk results. The first set of risk results are
those calculated using reported survey values for specified constituent concentrations present in
the impoundments. These risk results, therefore, reflect model results from reported
concentrations. The second set of risk results are those calculated either using imputed values,
where survey respondents reported constituents as being present but did not provide quantities, or
using detection limit levels when constituents were reported at less than a limit of detection.
Consequently, the second set of risk results are considerably more uncertain.
On a national scale across all pathways in the risk analysis, EPA found that only 5 percent
of the estimated 4,500 in-scope facilities and 2 percent of the estimated 11,900 impoundments
may pose risks to human health. However, EPA also found that 21 percent of facilities
nationally, corresponding to 24 percent of impoundments, have the potential for environmental
releases to occur from impoundments. While these releases do not appear to pose risk to human
health, they do indicate that selected contaminants in excess of health-based levels have the
potential to move beyond the surface impoundment confines and into the environment.
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March 26, 2001 Executive Summary
In the risk analysis, in addition to the national aggregated results, EPA developed risk
estimates for three pathways of potential exposure by which chemical constituents could move
from an impoundment, through the environment, and be available to be inhaled or ingested by
people nearby:
• Direct inhalation risks can occur if a constituent of concern evaporates from the
impoundment's water surface, is carried by air dispersion to nearby residences,
and then is inhaled by residents. EPA developed risk estimates for the closest
residences, based on locations reported in the surveys or identified through census
information, and generated national estimates.
About 92 percent of impoundments were found to pose no air inhalation risk of
concern. About 1 percent of impoundments are estimated to have a risk of
concern from the inhalation of airborne contaminants. In addition, an estimated
additional 3 percent of impoundments do not pose air inhalation risks to people
nearby, but do generate releases to the air that exceed health-based levels at a
distance of 25 meters from the impoundments. The remaining 4 percent of
impoundments could not be evaluated conclusively because of the use of detection
limits or inferred data due to incomplete reporting.
• Groundwater risks can occur if impoundments release a constituent of concern
through the bottom or sides of the impoundment and these chemicals enter
groundwater and move through the subsurface to a drinking water well. EPA
estimated risks that could occur due to consumption of water from the closest
drinking water wells reported in the surveys or identified through census
information, and then generated national estimates. Groundwater contaminant
migration depends on many factors, but migration can be slow. EPA's modeling
did not examine the speed of contaminant movement, so some of the reported
risks may occur in the future.
Groundwater risks also appear low; 67 percent of impoundments have no
evidence of risk. Less than 1 percent of impoundments are estimated to have the
potential for risk exceedances. In addition, 11 percent of impoundments have the
potential to generate contaminated groundwater plumes that may extend
150 meters or more beyond the unit boundary. The remaining 22 percent of
impoundments, while not estimated to cause a risk, could not be evaluated
conclusively for their potential to result in a release to the environment because of
incomplete reporting of concentration information.
• Groundwater to surface water risks can occur if constituents in an impoundment
migrate through groundwater, discharge into nearby surface water, and
contaminate fish and make drinking the surface water a concern. From the survey
data, EPA generated national risk estimates that identified situations where human
health ambient water quality criteria (HH-AWQC) might be exceeded in surface
waterbodies.
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March 26, 2001 Executive Summary
EPA estimates that less than 1 percent of impoundments contribute to
exceedances of HH-AWQC in nearby surface waters. EPA estimates 19 percent
of impoundments, while not causing exceedances of HH-AWQC once dilution
has occurred in the surface water, are estimated to generate releases that could
cause groundwater to exceed the HH-AWQC at the point of groundwater
discharge into the surface water.
Risk Screening Findings
EPA also screened for potential risks to human health through indirect pathways that
were not considered in the risk analysis and for potential risks to ecological receptors. The
objective of the screening was to determine the worst case potential for wastes of concern to
cause harm.
• Indirect pathway hazards can occur when humans ingest foods that have been
contaminated indirectly by surface impoundment releases. For example,
constituents can evaporate, move by dispersion through air, and then deposit on
nearby crops and contaminate food sources. EPA's methodology resulted in
estimates of potential indirect pathway hazards that were ranked categorically.
Approximately 6 percent of the facilities fell into the highest category, indicating
that this group of facilities has the greatest potential to result in an indirect risk of
concern. However, this analysis does not confirm that facilities in this group
actually have indirect risks of concern.
• Industrial wastes managed in surface impoundments may potentially cause
adverse effects on nonhuman organisms and natural systems. Many
impoundments are located near waterbodies and are freely accessible to wildlife.
For this study, EPA assessed the potential for impoundments to pose risks to
populations and communities of ecological receptors that live in and near surface
impoundments both during their operation and in the event that the impoundments
were closed with exposed wastes remaining in place. EPA estimates that
approximately 29 percent of facilities may have localized ecological impact
during their operation or after closure if ecological receptors inhabit the
impoundment area or the nearby areas affected by undiluted impoundment runoff.
The results of the risk analysis and risk screening are presented in Chapter 3 of this
report. Appendix C describes the methodology and more detailed findings.
Evaluation of Existing Federal and State Programs
Methodology
The LDPFA requires EPA to assess the various federal and state regulatory and
nonregulatory programs that address potential risks from surface impoundments and evaluate the
adequacy of such programs. In addition, the EDF consent decree requires us to determine the
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March 26, 2001 Executive Summary
need for a RCRA air characteristic to address potential air pathway risks from the studied surface
impoundments.
Our general approach for the regulatory coverage analysis included a detailed review of
applicable federal and state regulatory and nonregulatory programs. The regulatory coverage
analysis and identification of gaps in this coverage focused on the potential for risks as
determined by our human health and ecological risk screening analyses. The regulatory analysis
addresses each of the health pathways of concern and potential risks to ecological receptors. We
divided our analysis into two parts: (1) regulatory coverage of direct air inhalation risks, and
(2) regulatory coverage of all other "nonair" risks.
To evaluate regulatory coverage and potential gaps for direct air inhalation risks, we
reviewed two federal statutes: RCRA, that is, the hazardous and nonhazardous waste programs
under this act, and the CAA. The CAA analysis involved three interrelated elements: (1) a waste
management unit analysis to identify CAA provisions that can address surface impoundments;
(2) a constituent coverage analysis, which focused on the constituents of concern from the risk
assessment; and (3) an industry coverage analysis, which focused on the industry categories that
were within the scope of this study. We then evaluated possible regulatory coverage by state
programs. For potential nonair pathway risks posed by nonhazardous wastes in surface
impoundments, we (1) identified constituents of concern from the groundwater and groundwater
to surface water pathways, (2) identified federal regulations and programs that may address such
risks, and (3) assessed coverage by state programs.
Regulatory Analysis Findings
Overall, the study shows that regulatory and nonregulatory coverage of potential air risks
is extensive and that any gaps in coverage appear to be limited to specific industry sectors,
individual facilities that meet certain CAA exemptions, or specific air pollutants. The primary
regulatory program that addresses potential air risks from industrial surface impoundments is the
CAA National Emission Standards for Hazardous Air Pollutants program. Pursuant to section
112 of the CAA, all source categories that emit hazardous air pollutants and pose risks to human
health should be regulated when the maximum achievable control technology program is fully
implemented. There also are several other existing regulatory and nonregulatory programs that,
to varying degrees, address air releases from industrial surface impoundments. These programs
include the RCRA Corrective Action Program, the CAA Criteria Air Pollutant Program, state
regulations pursuant to State Implementation Plans, the Voluntary Industrial Waste Management
Guidance Program, and federal and state waste minimization programs.
For groundwater, the study shows that regulatory and nonregulatory coverage of potential
groundwater risks is extensive, but may still have some limited gaps. Potential groundwater risks
from industrial surface impoundments, including the groundwater to surface water pathway, are
addressed primarily through state regulatory and nonregulatory programs. Based on our available
information, most states have one or more programs that include provisions for controlling or
addressing groundwater releases from industrial nonhazardous waste surface impoundments.
The level of regulatory control or ability to address these releases, however, varies from state to
state. These state regulations may be implemented under either general solid and industrial waste
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management authority or under water program authority, for example, a state National Pollutant
Discharge Elimination System (NPDES) program. Additionally, there are RCRA, CWA, and
Safe Drinking Water Act (SOWA) programs that also, to varying degrees, address groundwater
releases or assess the susceptibility of drinking water sources to contamination. These programs,
for example, include the SDWA Source Water Assessment Program, SDWA Wellhead
Protection Programs, RCRA Corrective Action Program, the Voluntary Industrial Waste
Management Guidance Program, NPDES program, and federal or state waste minimization
programs.
The results of EPA's regulatory analysis are presented in Chapter 4 of this report. In
addition to identification of potential regulatory "gaps," EPA discusses the limitations of the
analysis and existing and future regulatory or nonregulatory tools that may be used to address
identified gaps.
Study Conclusions
Today's study satisfies both the requirements of the EOF consent decree and the LDPFA
with regard to evaluating the risks and regulatory programs for surface impoundments receiving
"decharacterized" wastewaters and never characteristic wastewaters. In both cases, EPA has
conducted an extensive analysis of the impoundment universe to understand the risks that may be
posed and the extent to which risks are addressed by current and emerging federal and state
programs.
In conducting the study pursuant to the EDF consent decree, EPA obtained the
information necessary to determine whether a rulemaking to promulgate a hazardous waste
characteristic should be initiated. Specifically, EPA examined the universe of impoundments
that manage nonhazardous wastewaters. In addition, EPA characterized the pollutants of
concern, likely releases, and pathways from these impoundments and assessed potential risks to
human health and environment. Little risk has been found, and any risk found is not widespread,
but may exist at a facility-specific level. Further, EPA examined the regulations that may apply
to impoundments under a variety of federal and state authorities and found that coverage is
extensive, but may not be complete in all cases. EPA identified a number of tools (for example,
CAA, RCRA, state programs) that can be used effectively to mitigate risks as alternatives to a
new hazardous waste characteristic.
In conducting the study pursuant to the LDPFA, EPA completed a study of
"decharacterized" wastewater that characterizes the risks to human health or the environment
associated with such management. The completed surface impoundment risk study will be
undergoing a formal peer review process by EPA's Science Advisory Board expected to begin in
early summer. In light of the planned peer review, any technical data in the report should be used
with appropriate caveats and cautions. Further, EPA examined existing federal and state
programs to evaluate the extent to which risks are adequately addressed under those programs
and looked at whether the risks could be better addressed under such laws or programs. EPA
concluded that there are some limited gaps in regulatory coverage, but did not find any serious
risks that are unaddressed by existing programs. The Agency has not yet determined whether any
specific regulatory actions are appropriate to mitigate the potential risks identified in the study.
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Chapter 1
Study Background
This chapter explains the legal framework and issues that form the Surface Impoundment
study's background, the previous studies of industrial surface impoundments, and the specific
purpose and scope of this study. A brief overview of the technical part of the study methodology
is included. Further explanations of the technical and program coverage methodologies are
found in Chapters 3 and 4.
1.0 Introduction
1.1 Previous Studies Defining and Characterizing Surface Impoundments
1.2 Legal Framework and Issues
1.3 Study Purpose
1.4 Study Scope
1.5 Overvi ew of Methodol ogy
1.6 Organization of this Report
1.0 Introduction
In the late 1970s to mid-1980s, the U.S. Environmental Protection Agency (EPA)
conducted research on industrial surface impoundments. Between 1990 and 1997, certain issues
arose concerning industrial impoundments, the nonhazardous (or formerly hazardous) wastes
managed in them, the potential risks posed by managing those wastes in impoundments, and how
existing regulations address potential risks. These issues were identified in the Land Disposal
Program Flexibility Act (LDPFA) legislation that amended the Resource Conservation and
Recovery Act (RCRA) and also in a consent decree (EDF v. Whitman). Both the legislation and
the consent decree required EPA to study the issues. To resolve these issues, EPA needed
specific information that was not available from previous research.
1.1 Previous Studies Defining and Characterizing Surface Impoundments
EPA performed a comprehensive census of agricultural, mining, industrial and municipal
surface impoundments in the late 1970s and early 1980s (U.S. EPA, 1983b). In this census, the
investigators located and categorized approximately 30,000 industrial surface impoundments
(Sis). The census included information on these impoundments' geographic distribution, sizes,
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March 26, 2001 Chapter 1
industry categories, functions, and potential for groundwater contamination. The data
identifying the facilities and their locations were not available to be used to help design this
study.
At the time this census was performed, the federal RCRA hazardous waste regulations
were just beginning to be implemented. These regulations included requirements for surface
impoundment design and operation; the original requirements for hazardous waste surface
impoundments were tightened in the mid-1980s. These requirements caused many facility
owners and operators to change their waste management practices for hazardous wastes and
manage more of their wastes in tanks rather than in surface impoundments.
In 1985, EPA conducted a telephone screening survey (U.S. EPA, 1987) of facilities that
managed nonhazardous waste in onsite waste management units, including surface
impoundments. The definition of surface impoundment used in the telephone screening survey
was slightly different from the definition used in the 1983 census, and the telephone screening
survey study involved selected industry sectors rather than the broader range of industry sectors
covered in the 1983 census. The 1985 telephone screening survey results indicated that
approximately 15,000 surface impoundments were being used to manage nonhazardous waste.
During this study, EPA conducted a literature search to determine whether other
organizations had performed either national or regional studies of surface impoundments. There
was limited information in the public domain, and many of the published references on surface
impoundments that EPA found were journal articles describing topics relating to a single
impoundment or a single facility's impoundments. EPA found very few published risk
assessments of human or ecological effects posed by managing wastes in surface impoundments.
1.2 Legal Framework and Issues
7.2.7 Resource Conservation and Recovery Act - Background
RCRA establishes "a 'cradle-to-grave' regulatory structure overseeing the safe treatment,
storage, and disposal of hazardous waste."1 The first step in the cradle-to-grave process is
determining which wastes are hazardous. The statute delineates two types of hazardous wastes:
those wastes listed specifically by EPA as hazardous, and those that are hazardous because they
exhibit some objectively quantifiable property or characteristic (such as ignitability, corrosivity,
reactivity, or toxicity) identified by EPA. This study concerns the latter type: so-called
"characteristic" hazardous wastes.
In 1984, Congress amended RCRA to prohibit land disposal of hazardous wastes unless
hazardous constituents in the wastes are substantially destroyed, removed, or immobilized so that
threats to human health and to the environment posed by the wastes' land disposal are
minimized. Normally, this land disposal restrictions (LDR) requirement is satisfied by
pretreating hazardous wastes before they are land disposed. Implementing this requirement for
characteristic hazardous wastes, however, raises significant issues about the extent to which
1 United Technologies Corp. v. EPA, 821 F. 2d 714, 716 (D.C. Cir. 1987).
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pretreatment can be required. This is because, under RCRA regulations, characteristic wastes are
no longer identified as hazardous wastes once they no longer clearly exhibit a hazardous waste
characteristic. For example, a waste acid with pH less than 2 no longer exhibits the corrosivity
characteristic when its pH is greater than 2 and, thus, is no longer a hazardous waste (assuming
corrosivity is the only reason this waste was classified as hazardous).
The issue raised for purposes of the LDR program was whether EPA could require further
treatment of characteristic wastes even if they no longer exhibited a characteristic. Such
treatment could be needed to minimize threats posed by the wastes' land disposal (the overall
standard for assessing when land disposal is permissible) because characteristic hazardous wastes
may pose hazards for reasons in addition to the characteristic property they exhibit. For example,
characteristic hazardous wastes can contain problematic concentrations of hazardous
constituents. In its rule of June 1, 1990, EPA imposed further treatment of characteristic
hazardous wastes even when the wastes no longer exhibited a characteristic. Such treatment was
intended to minimize threats posed by land disposal.
Because the statute requires that hazardous constituents must be destroyed, removed, or
immobilized in order for threats to be minimized, this means, ordinarily, that hazardous
constituent levels cannot be reduced by means of dilution. EPA's LDR rules thus contain a
prohibition on dilution being used as a substitute for treatment that destroys, removes, or
immobilizes hazardous constituents. Applied to characteristic hazardous wastes, this means that
merely removing a characteristic property by dilution is inadequate treatment if the waste also
contains hazardous constituents (as most characteristic wastes do), since the hazardous
constituents would not be immobilized or destroyed, and, consequently, threats posed by land
disposal would not be minimized.
The most difficult issue presented by the question of dilution of characteristic wastes, and
the one that (eventually) occasioned this study, arises when wastewaters exhibit a characteristic,
become decharacterized as a result of dilution, and are then land disposed in waste management
units affected by either the Clean Water Act (CWA) or the Safe Drinking Water Act (SOWA).
The chief example is where a manufacturing plant's wastewaters, some of which exhibit a
characteristic, are commingled—resulting in decharacterization by dilution— and then treated in
a surface impoundment, a land disposal unit. The ultimate discharge of wastewaters from the
impoundment to navigable waters, or to publicly owned treatment works (POTW), is regulated
by the Clean Water Act.
Although in such a case the wastewater would be land disposed (i.e., placed in the
impoundment) without hazardous constituents in the characteristic wastes being destroyed,
removed, or immobilized (i.e., they would be merely diluted), EPA chose, in the June 1, 1990,
rulemaking, not to require treatment in advance of land disposal because of the likelihood of
substantial disruption of CWA treatment programs. Subsequently the D.C. Circuit Court agreed
with EPA only partially, holding that such dilution was permissible only to the extent treatment
in the impoundment removed the same amount of hazardous constituent before ultimate
discharge as would otherwise be required by the treatment standard. (Chemical Waste
Management, Inc. et al. v. EPA.)
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It is this aspect of the Court's opinion that Congress addressed in the 1996 Land Disposal
Program Flexibility Act (Public Law 104-119). Instead of immediately requiring the equivalent
treatment requirement adopted by the D.C. Circuit Court, Congress amended the statute to allow
most characteristic wastes to be decharacterized by any means (including dilution) and managed
in surface impoundments whose ultimate discharge is regulated under the Clean Water Act2 or
managed in underground injection wells regulated under the Safe Drinking Water Act. Congress
further required EPA to study risks to human health and to the environment posed by managing
decharacterized hazardous wastes in surface impoundments whose ultimate discharge is
regulated by the CWA or by managing decharacterized hazardous wastes in underground
injection wells regulated under the Safe Drinking Water Act. For risks found, EPA is required by
the LDPFA to evaluate the extent to which those risks are adequately addressed under existing
regulatory or nonregulatory programs. If risks are found that are not adequately addressed, then
EPA may "impose additional requirements" or rely on other state or federal programs to address
risks found (RCRA section 3004(g)(10)).
EPA's Office of Solid Waste (OSW) conducted this study on surface impoundments, and
EPA's Office of Groundwater and Drinking Water (OGWDW) separately conducted the study on
underground injection wells (U.S. EPA, 2001).
In 1997, as part of negotiations over the terms of a consent decree in U.S. District Court,3
EPA agreed to study human health risks from air inhalation posed by the nonhazardous wastes
managed in surface impoundments that were not part of the LDPFA study. These consent decree
nonhazardous wastes are called never characteristic wastes in the rest of this report. The
LDPFA study wastes are called decharacterized wastes in the rest of this report.
7.2.2 Clean Water Act - Background
The Clean Water Act establishes a program that controls the discharge of pollutants into
the waters of the United States. When facilities use water for some purpose and contaminate it
through use, or channelize precipitation that runs off into surface water, they generally direct the
flow
• Toward or into surface water
• Into a municipal wastewater collection system (where it is treated in a POTW)
• Into a topographic depression (low-lying area) where it either evaporates or
percolates into the ground.
RCRA sections 3004(g)(7) and (8). Decharacterized wastes for which EPA specified a method of
treatment remain prohibited from land disposal, as do reactive cyanide wastes (RCRA section 3004(g)(8)).
Environmental Defense Fund, Inc. vs. Christine Todd Whitman, Administrator, United States
Environmental Protection Agency, et al, Defendants, and American Petroleum Institute, et al, Intervenor-
Defendants, Civ. No. 89-0598, in the United States District Court for the District of Columbia.
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March 26, 2001 Chapter 1
The first way of handling the excess water is called direct discharge. At the point where
the excess water enters the surface water, a CWA National Pollutant Discharge Elimination
System (NPDES) permit, or an equivalent permit issued by an authorized state environmental
agency, specifies the amount of pollutants that may enter the surface water without degrading the
surface water quality.
The second way of handling excess water is called indirect discharge. The facility that
generates the excess water directs it into a publicly owned treatment works that includes both a
collection system and a treatment plant. In the POTW collection/treatment system, the excess
waters typically mix with the wastewaters from many other collection/treatment system users.
Once the wastewaters are treated, the discharge from the treatment system goes directly into
surface water, and that discharge is a direct discharge. The discharge from the treatment system
requires a Clean Water Act permit.
The third way of handling excess water, by directing or allowing it to flow into a low-
lying area, then recycling it back into facility processes or waiting for it to evaporate or drain
(infiltrate) into the ground, is called zero discharge because the excess water does not go into
surface water—at least not in a rapid or visually observable way. The term "zero discharge"
refers to the fact that there is no intended discharge into surface water or to a POTW.
For the direct dischargers, EPA or the authorized state environmental agency receives
permit applications and writes the permits. For indirect dischargers, pretreatment standard
regulations and/or a POTW collection/treatment system sets treatment levels for indirect
discharger users. Zero dischargers sometimes are regulated under the CWA and sometimes are
not. In general terms, an authorized state's environmental laws and their implementation
determine whether that state issues permits for zero dischargers. In many states, the authorized
state agency does not issue NPDES permits for zero dischargers.
1.2.3 Clean Air Act - Background
Section 112 of the Clean Air Act (CAA) requires EPA to regulate emissions of the most
potent air pollutants: those that are known or suspected to cause serious health problems such as
cancer or birth defects. The Clean Air Act refers to these pollutants as hazardous air pollutants
(HAPs).
When amending the CAA in 1990, Congress directed EPA to use a technology-based
approach to significantly reduce emissions of air toxics from major sources of air pollution,4
followed by a risk-based approach to address any remaining, or residual, risks. Under the
technology-based approach, EPA develops standards for controlling the emissions of air toxics
from each major source of HAPs. The standards are to result in the maximum reduction in
emissions of hazardous air pollutants achievable and cannot be any less stringent than the
average emission limitation achieved by the best performing 12 percent of existing sources
4 Major sources are defined as sources that emit 10 tons per year of any of the listed toxic air pollutants or
25 tons per year of a mixture of air toxics.
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within a source category for which EPA has emission information.5 Standards may be more
stringent than this base level of control (typically called a floor) after EPA considers cost, energy,
and nonair quality health and environmental impacts of potentially more stringent standards.
Standards thus typically reflect the performance of the maximum achievable control technology
(MACT). Eight years after each MACT standard is issued, EPA must assess the remaining
health risks from source categories. If necessary, EPA must implement additional standards that
address any significant remaining risk.
1.2.4 Interaction of RCRA. CWA. andCAA
The CWA and CAA were enacted to control and minimize water and air pollution,
respectively. These two laws caused facilities to collect and manage pollutants that previously
had been discharged into the nation's waterways and into its air. RCRA was enacted in
recognition of the need to manage these collected pollutants appropriately so that they would not
become waterborne or airborne again (RCRA section 1002(b)). This section discusses how these
three laws interact with respect to the particular issue of risks to human health and the
environment posed by managing nonhazardous wastes in surface impoundments.
A traditional focus of the RCRA hazardous waste program has been on risks posed by
collected wastes, such as air and water pollution control residues, and protecting groundwater
resources from contamination from those residues. The RCRA hazardous waste program
exempts from RCRA substantive and permitting requirements tank systems that are part of CWA
treatment systems. CWA NPDES permits issued by states, using state environmental statutes,
occasionally contain prohibitions on groundwater contamination. Because the CWA program's
traditional focus has been on protecting surface water rather than groundwater, however,
questions have arisen about whether wastes managed in CWA-regulated treatment systems, but
exempt from RCRA requirements, might contaminate groundwater. An example is one part of
the controversy that the LDPFA addressed: the potential for groundwater contamination from
decharacterized wastes managed in CWA treatment systems. In a CWA treatment system in
which wastewater flows first through a tank system and then into surface impoundments, the
wastewater treatment unit exemption from RCRA substantive and permitting requirements
would apply to the tank system part of the wastewater treatment system. Thus, characteristic
hazardous wastes could be introduced into the RCRA-exempt tank system part of the treatment
train, become diluted during treatment, and no longer exhibit the hazardous characteristic by the
time they reach a surface impoundment. This situation gave rise to the concern that hazardous
constituents present in the wastewater could still be present and available to contaminate
groundwater.
Historically, EPA's rules implementing the CWA have not addressed pollution from air
emissions emanating from wastewater collection and treatment systems. In some instances, the
RCRA hazardous waste program does address air emissions from wastewater collection and
treatment, and, in other instances, the CAA hazardous air pollutant (air toxics) program addresses
certain emissions from wastewater collection and treatment. However, there could be situations
5 For new sources, the standard is the level of emission reduction achieved by the best performing single
source within a source category.
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March 26, 2001 Chapter 1
in which wastewaters containing volatile HAPs are not regulated under either the RCRA
hazardous waste program or the CAA air toxics program. The consent decree sought to have
EPA investigate such situations and requires that EPA explicitly include certain facilities and
impoundments with a particular CAA section 112 status. EPA must assess whether these
facilities and impoundments, and the chemicals managed in them, pose risks by the direct air
inhalation pathway.
7.2.5 Requirements To Conduct This Study
1.2.5.1 LDPFA Requirements. Section 3004(g)(10) of the LDPFA requires the
Administrator of EPA to complete a study of wastes that: (1) no longer exhibits a hazardous
characteristic prior to management in any land-based solid waste management unit; and (2) is
treated in a treatment system that subsequently discharges to waters of the United States pursuant
to a permit issued under section 402 of the Federal Water Pollution Control Act, treated for the
purposes of the pretreatment requirements of section 307 of the Clean Water Act, or treated in a
zero discharge system that, prior to any permanent land disposal, engages in treatment that is
equivalent to treatment required under section 402 of the CWA for discharges to waters of the
United States.
Not later than 5 years after the date of enactment of the LDPFA (i.e., by March 26, 2001),
EPA must complete a study of these wastes to characterize the risks to human health or the
environment associated with such management. In conducting the study, EPA must evaluate the
extent to which risks are adequately addressed under existing state or federal programs and
whether unaddressed risks could be better addressed under such laws or programs. Upon receipt
of additional information or upon completion of such study and as necessary to protect human
health and the environment, EPA may impose additional requirements under existing federal
laws, including subsection 3004(m)(l) or rely on other state or federal programs or authorities to
address such risks.
1.2.5.2 EDF Consent Decree Requirements. Paragraph 11.1 of the consent decree
requires EPA to perform two studies on gaps in the hazardous waste characteristics. The studies
must also evaluate the resulting potential risks to human health posed by the inhalation of
gaseous and nongaseous air emissions from wastes managed in tanks, surface impoundments,
landfills, wastepiles, and land treatment units. For surface impoundments, the consent decree
specifically excludes those surface impoundments receiving decharacterized wastewaters that are
being studied under the LDPFA. With respect to the consent decree studies, at a minimum, EPA
is required to address releases from waste management units that: (1) are at facilities that are not
within source categories subject to the scope of the CAA NESHAP program, (2) are at facilities
that are not major sources under the CAA, and (3) are excluded under a specific NESHAP
MACT rule due to unit or chemical type. For the surface impoundments, EPA is required to
evaluate those impoundments receiving wastewaters that never exhibited a hazardous waste
characteristic.
The purpose of these studies is "to obtain such information as the Administrator may
require to determine whether a rulemaking to promulgate a hazardous waste characteristic that
addresses potential risk to human health through the direct inhalation pathway should be
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initiated." In May 1998, EPA released the first of the two required studies covering the waste
management units other than surface impoundments. (See Air Characteristic Study, U.S. EPA
1998, subsequently revised November 1999a.) The Consent Decree calls for completion and
public release of the surface impoundment study by March 26, 2001.
1.3 Study Purpose
This study's purpose is to fulfill, in a single place, the separate requirements posed by the
LDPFA and the consent decree, which are
"to characterize the risks to human health or the environment associated with
[managing decharacterized wastes in CWA treatment systems]" and to "evaluate
the extent to which risks are adequately addressed under existing State or Federal
programs and whether unaddressed risks could be better addressed under such
laws or programs." (RCRA section 3004(g)(10))
and
The Administrator shall...perform [a] stud[y] on gaps in the hazardous waste
characteristics and relevant Clean Air Act ("CAA") controls, and the resulting
potential risks to human health, posed by the inhalation of gaseous and non-
gaseous air emissions from wastes managed in...surface impoundments (excluding
those impoundments receiving decharacterized wastewaters that the Agency is
obliged to study pursuant to section 3004(g)(10) of RCRA, 42 U.S.C. S
6924(g)(10))....6
Both the statute and the consent decree require a risk assessment and then an evaluation
of existing mechanisms that address risks posed by this waste management practice. There are
differences between the statutory requirement and the consent decree requirement. EPA chose to
conduct a multimedia7 risk assessment, which satisfies the statutory requirement and goes beyond
what is required in the consent decree. EPA also performed an evaluation of existing programs,
both regulatory and nonregulatory, which satisfies the statutory requirement and goes beyond
what is required in the consent decree.
As a result, the study has two primary objectives: (1) to assess risks posed by the waste
management practices described in the statute and consent decree, and (2) to describe how
existing regulatory and nonregulatory programs address any risks that may be present.
Civ. No. 89-0958, Environmental Defense Fund, Inc. vs. Whitman et al. June 12, 1997.
7 In this context, "multimedia" refers to multiple environmental media— air, water, soil, and biota.
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1.4 Study Scope
1.4.1 Definition of Surface Impoundment
In the RCRA hazardous waste regulations, the definition of "surface impoundment" at 40
CFR260.10is
... a facility or part of a facility which is a natural topographic depression, man-
made excavation, or diked area formed primarily of earthen materials (although it
may be lined with man-made materials), which is designed to hold an
accumulation of liquid wastes or wastes containing free liquids, and which is not
an injection well. Examples of surface impoundments are holding, storage,
settling, and aeration pits, ponds, and lagoons.
Historically, there have been some difficulties in interpreting this definition related to
distinguishing between surface impoundments and tanks for purposes of interpreting whether the
hazardous waste regulations do or do not apply to a particular waste management unit. In a 1983
memorandum, EPA distinguished between tanks and impoundments (U.S. EPA, 1983a) by an
engineering test of a wastewater holding unit's structural integrity and interpreted the unit to be
either a tank (if it can withstand the forces applied during the engineering test) or a surface
impoundment (if it cannot withstand the applied forces).
In this study, EPA considered using this definition, but was concerned that the difficulties
in distinguishing between tanks and impoundments would pose problems with the screening
survey, which was intended to identify a sample of facilities with impoundments. EPA reviewed
the definitions used in the 1983 census and the 1985 telephone screening survey and chose to use
a modified version of the definition in the 1983 census. The definition OSW finally used in its
surveys for this study (U.S. EPA, 1999b, 1999c) used both text and graphics and is shown in
Figure 1-1)
1.4.2 Other Scope Decisions
EPA faced several decisions on scoping the study on matters that were not specified in
the legislation. EPA received and considered public comments on many of the scope decisions.
(EPA's strategy for involving the public in the study design and implementation is described in
Section 1.5.) These specific decisions are described as follows.
Economic Sectors To Include in the Study. EPA chose to focus the study on those
sectors most likely to generate characteristic hazardous waste and, thus, to potentially have
decharacterized waste that might be managed in impoundments. The sectors included were the
manufacturing industries (including food processing; textiles; paper and allied products; stone,
clay and glass; chemicals and allied products; petroleum and allied products; and primary
metals), bulk chemical and petroleum storage, sewerage and refuse systems, scrap and waste
materials, airport terminals, truck transportation terminals, and national security. EPA generally
excluded the economic sectors that had already been studied in considerable detail under the
various statutory RCRA exclusions for large-volume wastes (the so-called "Bevill exclusions"
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A surface impoundment is a natural topographic depression, artificial excavation, or dike arrangement
for storing, treating, or disposing of wastewater (i.e., liquid or semi-solid waste with less than 5%
solids by weight). A surface impoundment may be constructed above the ground, below the ground,
or partly above the ground and partly below the ground. A surface impoundment's length or width is
greater than its depth (for example, it is not an injection well). Here are some examples (side view):
above the ground naturally occurring or excavated below ground/
dike arrangement artificially excavated diked above ground
below the ground
Figure 1-1. Definition of surface impoundments used in this study.
found at RCRA section 3001(b)(3)). However, some facilities whose wastes are excluded under
these statutory exclusions inadvertently were included in the study population because it was not
possible to separate them from facilities in the economic sectors of interest.
Time Frame in Which Impoundments Operate. Because impoundments sometimes
operate for many decades, EPA needed to define practical boundaries for the operating period
time frames this study would review. EPA did not believe that facility owners would have
information readily available concerning old impoundments that had closed many years ago.
EPA decided that, since the original LDPFA issue came about due to the so-called "third third"
1990 land disposal restrictions, it was appropriate to focus attention on only those impoundments
that were potentially affected by those regulations (promulgated on June 1, 1990). Thus, EPA
limited the study's scope to impoundments that had received waste on or after June 1, 1990.
Geographic Range. In RCRA, the term "state" refers to the 50 states, the District of
Columbia, Puerto Rico, the Virgin Islands, Guam, American Samoa, and the Commonwealth of
the Northern Mariana Islands. The study's geographic range includes all of these areas.
Whether To Include both Wastewater and Sludge. For this study, EPA defined
wastewater as "liquid or semi-solid waste with less than 5% solids by weight" and sludge as "any
solid, semi-solid, or liquid waste containing 5 weight percent or more solids, that is generated in
the course of treating or managing wastewater." Initially, EPA proposed including sludge and
sludge management practices in the study's scope. However, the issue of sludge management
after removal from the impoundment (or sludge management in impoundments, where the
impoundment is the final disposal unit for the sludge) was not part of the original LDPFA issue.
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In addition, the complexity of the ongoing nature of sludge management (with such diverse
practices as dewatering, land application, landfilling, and beneficial reuse) would have
complicated the data collection. Thus, EPA decided to limit the study to wastewater and sludge
present in an impoundment and not to study risks posed by sludges after they are intentionally
removed from an impoundment.
Chemical Constituents of Concern. The legal issues that prompted the study revolved
around hazardous constituents in these wastes remaining after the characteristic property is
removed (in the case of the LDPFA) and around a list of 105 specific constituents that the
consent decree required EPA to study. EPA combined the list of 105 specific constituents with a
list of constituents that had been identified previously as being of concern in the LDR program
(certain so-called "universal treatment standards" constituents), or more broadly in the RCRA
hazardous waste program (additional constituents that were being considered under the
Hazardous Waste Identification Rule [HWIR] proposal in early 1997). The combined list
consisted of 256 chemicals (or, in some cases, classes of chemicals) that were the subject of the
study.
1.5 Overview of Methodology
7.5.7 Public Involvement in Study Design and Identification of Data Needs
Soon after the Land Disposal Program Flexibility Act was enacted, EPA placed a notice
in the Federal Register about the legislation's requirement to conduct the study, requested public
comments on the "data collection, quality assurance/quality control of data, development of risk
assessment methods, establishment of a peer-review structure for the study, and assessment of
current State/Federal/Tribal regulations or programs that address risks"8 and invited stakeholders
to submit ideas for the study design. The general nature of the comments submitted was that
EPA would need to collect detailed, site-specific information from a representative sample of
facilities to be able to assess potential risks accurately. EPA chose to design the study using
many of the public comments received. EPA also sought a consultation from a committee of
EPA's Science Advisory Board (SAB) to gain expert scientific input on the design of the risk
assessment portion of the study.
Based on the public comments and expert scientific input, EPA identified three broad
categories of data needs:
• Data on chemical constituents' health effects and physical/chemical properties
• Information on federal and state regulatory and nonregulatory programs
• Data on sources and wastes including
Environmental settings in which impoundments are found
Vol. 61, Federal Register, pp. 38684-38687, July 25, 1996.
-------
March 26, 2001 Chapter 1
Impoundment design features
Impoundment operating and closure practices
Wastes managed in impoundments (quantity of the waste matrix and its
chemical composition—presence, identification and quantities of chemical
constituents)
Presence, location, and activities of people and nonhuman organisms.
The data in the first category are available in the scientific literature. For the information in the
second category, EPA used various public data sources. For the data in the third category,
although some data were readily available in public data sources, EPA had no way to judge their
representativeness. Thus, a major challenge EPA faced in performing the study was how to
identify facilities that used surface impoundments meeting the criteria spelled out in the
legislation and consent decree in order to select a representative sample of facilities with
impoundments and how to collect from them the data in the third category.
7.5.2 Overall Framework of Risk Assessment
The basic framework for the risk assessment portion of the study can be summarized in
five steps:
1. Characterize the target population of facilities and impoundments and draw a
probability sample
2. Develop the risk assessment framework
3. Conduct a pilot study
4. Collect and process data for the risk assessment
5. Perform the risk assessment.
The first step consisted of targeting impoundments that were likely to manage the kinds
of wastes the legislation and consent decree required to be studied and that were likely to manage
the hazardous constituents that were at issue in both the legislation and the consent decree.
Because impoundments are sometimes used to manage stormwater that is merely precipitation
runoff and potentially contains very few, if any, of these constituents, EPA was not interested in
including impoundments holding stormwater only. However, many facilities use impoundments
to hold stormwater and some process wastewater, and some facilities use impoundments to hold
cooling water (which could be combined with stormwater, process wastewater, or both). The
wide variety of situations led EPA to decide on a list of wastewater attributes to use as criteria for
screening out impoundments that were unlikely to have constituents of concern. The criteria
were included in a "screening" survey that was used to target the study's focus on impoundments
most likely to be of interest.
1-12
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March 26, 2001 Chapter 1
The second step was to develop the risk assessment framework. During the study period,
both computing technology and risk assessment "state of the science" developed rapidly, and
EPA continually revised its approach for conducting the risk assessment to take advantage of
these developments. Using guidance from EPA's Science Advisory Board and technical
expertise in risk assessment, EPA developed a series of data analysis protocols to apply to the
information identified as necessary for the risk assessment.
The third step was to conduct a pilot study to test the data collection, data processing, and
risk assessment framework on a limited number of facilities. EPA used the results from the data
collection test to improve the survey used to collect the detailed data necessary for the risk
assessment. EPA also gauged the level of effort, both for the pilot study facilities to complete the
survey and for EPA to process and analyze the data, and made adjustments in the study's scope
and the risk assessment framework to improve the data collection and analysis efficiency.
The fourth step, collecting and processing the data, took the largest amount of time. For
situations such as this study, the Paperwork Reduction Act requires federal agencies to publish
draft surveys and accept public comments in two separate Federal Register notices before
receiving Office of Management and Budget (OMB) approval for sending out surveys. EPA
designed the data collection as a two-stage sample: the first stage was necessary to identify
facilities with impoundments meeting the study criteria, and the second stage was necessary to
collect the detailed information needed for the risk assessment. EPA used the screener survey for
the first stage and a long survey for the detailed information in the second stage. At the end of
the second stage, EPA also performed "field sampling" of wastewater and sludge samples taken
from impoundments at some of the study facilities. The total elapsed time for conducting the
pilot and completing the data collection part of the second stage survey was 3 years (see
Figure 1-2 for study timeline showing key milestones).
The fifth step, performing the risk assessment, was altered from the pilot study approach
due to the advances in computing technology, the availability of environmental fate and transport
models, and the need to perform further screening to remove from consideration those facilities,
impoundments, and constituents that present very little or no risk. EPA prepared a technical plan
for conducting the risk assessment and obtained input from independent peer reviewers before
embarking on the task of analyzing the survey and field sampling data. In performing the risk
assessment, EPA encountered certain situations not anticipated, so the final risk assessment
approach differed somewhat from the approach outlined in the technical plan. The approach
used is described in Chapter 3 and in Appendix C.
7.5.3 Representativeness of Facilities in This Study
Section 2 of the LDPFA described the three types of CWA facilities: direct, zero, and
indirect dischargers. Facilities that are one of these three types of dischargers and use surface
impoundments are the population the LDPFA directed EPA to study. At the beginning of this
study, EPA did not have a list of facilities in the United States with impoundments meeting the
criteria described in the statute or the consent decree. For direct dischargers, EPA had a
database, called the Permit Compliance System (PCS), that had some facility name and address
information, but did not identify very many facilities that used impoundments. For zero
1-13
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March 26, 2001
Chapter 1
Date
March 1996
July 1996
September 1996
October 1996 to April 1997
April 30/May 1, 1997
July 1997
February 1998
April to June 1998
July 1998
August 1998
December 1998
February to September 1999
November 1999 to July 2000
February to March 2000
May to August 2000
May 2000 to January 2001
September 2000 to March 2001
February to March 2001
Activity
Land Disposal Program Flexibility Act (LDPFA) enacted
Federal Register notice requesting comment on study
methodology
Preliminary consultation on methodology with Science Advisory
Board
Prepare methodology for Science Advisory Board peer review
Science Advisory Board peer review of proposed methodology
Begin pilot study
Draw random sample of facilities to receive screener surveys
First Paperwork Reduction Act Federal Register notice
Revise surveys based on public comments
Complete pilot study report; Second Paperwork Reduction Act
Federal Register notice; Submit Information Collection Request
to Office of Management and Budget (OMB)
Science Advisory Board peer review report on proposed
methodology
OMB approves Information Collection Request
Send out screener surveys, process data from returned surveys;
draw random sample of facilities to receive long survey
Long survey data collection
Peer review of technical plan for risk assessment
EPA "field sampling"
Human health and ecological risk assessment
Review of existing regulatory requirements and nonregulatory
programs
Final Agency review
Figure 1-2. Study timeline.
1-14
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March 26, 2001 Chapter 1
dischargers and indirect dischargers, there was no corresponding database that listed facility
names and addresses.
After extensive research, EPA concluded that the three subpopulations (direct, zero, and
indirect dischargers) presented different challenges for conducting the study. EPA was able to
use PCS as the data source to locate direct dischargers with impoundments. EPA constructed an
essentially complete list of the direct dischargers and drew a stratified random sample from that
list. For the direct dischargers, EPA believes that the sample is a representative one. EPA
constructed a new national list of zero dischargers from data supplied by state environmental
agencies and certain other sources. This list reflects the known zero discharger subpopulation,
but may not accurately reflect the entire national zero discharger subpopulation. However, it is
the most complete national list of zero dischargers that was possible to construct under this
study's constraints. Thus, EPA believes the sample of zero dischargers is representative of the
facilities on the list but may not be representative of all zero dischargers in the study population.
For the indirect dischargers, EPA concluded that, of the many thousands of indirect dischargers
across the country, it was likely that, at most, several hundred used impoundments. As a result,
EPA concluded that it was infeasible to locate a representative sample of this small
subpopulation. Instead, EPA chose to identify a nonrepresentative sample of the indirect
dischargers, selected to represent the known range of industries, and simply compare the results
for this group with the results for the direct and zero dischargers.
Figure 1-3 illustrates the steps taken to identify a representative sample of direct and
known zero dischargers and to identify the sample of indirect dischargers for this study.
In the rest of this report, EPA presents the survey data and risk assessment results for the
direct and zero dischargers. Although EPA included some indirect dischargers in the study and
performed the same risk assessment steps for those indirect dischargers, none were found to pose
risks at levels of concern. For simplicity, the indirect dischargers are omitted from the
descriptions in the rest of the report (although the data on their impoundments and wastes are
included in the appendixes and other supporting materials).
1.5.4 Peer Review of Study Components
EPA has a policy that requires peer review of major scientific and technically based work
products (U.S. EPA, 1994). One group that performs peer reviews of selected EPA work
products is the Science Advisory Board. EPA requested a SAB peer review of the proposed
study methodology. SAB agreed to review the proposed methodology, and convened a special
subcommittee of its Environmental Engineering Committee to perform the peer review. EPA
presented the proposed study design to the subcommittee in April 1997. The Science Advisory
Board's report for this peer review is available at http://www.epa.gov/sab/eec9809.pdf
(U.S. EPA, 1998).
EPA made use of many of the SAB recommendations during the study's implementation.
One topic on which EPA requested advice was the question of obtaining peer review at different
points in the study's implementation. SAB's advice on this topic was that EPA should consider,
plan for, and seek "...the peer review for minimum disciplinary acceptability of the
1-15
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March 26, 2001
Chapter 1
Direct Dischargers
Compiled Permit
Compliance System
data on 43,050 facilities
Selected stratified
random sample of
2,000 facilities; 138
were ineligible
Zero Dischargers
Compiled available state and
Toxics Release Inventory data
on 5,807 facilities
Selected stratified
random sample of 250
facilities; 74 were
ineligible
Indirect Dischargers
Compiled available
information on 35
facilities
Selected all 35
facilities
Identified 2,073 potentially eligible facilites to receive screener survey. Tracing efforts yielded
mailing addresses and contact information for 2,017 facilities:
1,185 direct dischargers
67 zero dischargers
35 indirect dischargers
Received screener survery responses from 1,774 of 2,017 facilities. Of these, 432 were from facilities
reporting use of in-scope impoundments:
365 direct dischargers
40 zero dischargers +
27 indirect dischargers
Selected
purposive
sample of
6 direct
dischargers
to pretest
long survey
Selected stratified
random sample of
40 zero dischargers
Selected purposive
sample of 14
indirect
dischargers
Distributed risk assessment survery to 221 facilities. Of these, 1 was a duplicate, 4 were
nonrespondents, and 21 were false positive screener survey responses. End result was 195 facilities
entering the risk assessment part of the study
Figure 1-3. Selection of facilities for study.
1-16
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March 26, 2001 Chapter 1
information...the validity of the technical interpretation, and...the relevance of the technical data
and interpretation to a policy decision..." while suggesting that there should be flexibility in
exactly which parties perform these three functions (U.S. EPA, 1998). EPA chose to follow this
advice using already existing mechanisms in place for obtaining public input and to seek formal
peer review by independent scientific experts at two points: a review of the technical plan for the
risk assessment prior to implementing it, and a review of the final risk characterization results.
The review of the technical plan for the risk assessment is described in more detail in
Appendix C. An SAB peer review of the risk characterization results will occur after completion
of the study.
1.6 Organization of This Report
The rest of this report describes the methodology, results, and conclusions of the risk
portion of the study and the corresponding analysis of regulatory and nonregulatory program
coverage of potential risks found. The risk portion of the study is described in Chapters 2 and 3,
the existing program coverage portion of the study is described in Chapter 4, and the risk
conclusions and the program coverage conclusions are summarized in Chapter 5.
Chapter 2 explains the long survey data that were used to develop the bulk of the study's
conclusions about potential risks. It also includes a discussion of the field sampling results and
how they illustrate the strengths and weaknesses of the long survey data on waste
characterization. The survey data are a critical component of the overall risk portion of the study
because they provide the context for the formal risk assessment results.
Chapter 3 presents the two parts of the formal risk assessment: the risk analysis, which
yielded numerical estimates of risks potentially posed via three human health "pathways," and a
risk screening, which did not yield numerical estimates of risks. The risk analysis consists of
• Estimates of potential risks to actual current, or likely future, receptors
• An assessment of environmental releases that are occurring and would cause
potential risks if people or ecological receptors were present at certain locations.
Chapter 4 presents the evaluation of the extent to which existing regulatory and non-
regulatory programs address the potential risks found and described in Chapter 3. For human
health risks from the direct air inhalation pathway, EPA identified provisions in both RCRA and
CAA programs that address surface impoundments, the extent to which any of the 256
constituents are specifically addressed by such programs, and the extent to which the industry
categories covered by the SI Study are addressed by the programs. For "non-air risks," EPA
identified federal and state regulations and programs that may address such risks and identified
the constituents of concern and assessed their coverage by these regulations and programs.
Chapter 5 summarizes the important findings from the survey data, summarizes the
results from the risk assessment, and summarizes the overall assessment of how well the existing
programs address the potential risks found.
1-17
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March 26, 2001 Chapter 1
Appendix A explains the statistical study design, the survey implementation, and data
processing steps.
Appendix B provides a detailed profile of the study population. The particular attributes
of impoundments, and the wastes managed in them, which can contribute to their probability of
causing environmental releases and/or human or ecological risks are described in considerable
detail. These data are important for understanding the context of the risk assessment results and
conclusions.
Appendix C provides a detailed description of the risk assessment methodology and more
details about the risk assessment results.
Appendix D provides a detailed description of the "existing program" analysis
methodology and more details about the coverage found.
Appendix E provides an overall summary of the field sampling waste characterization
data and the detailed information underlying the Chapter 2 description of how the field sampling
data illustrate the strengths and weaknesses of the long survey waste characterization data.
1.7 References
U.S. EPA (Environmental Protection Agency). 1983a. OSWERDirective # 9483.1983(01):
Memorandum from Bruce Weddle to Thomas Devine: Determination of Tanks vs. Surface
Impoundments. Washington, DC.
U.S. EPA (Environmental Protection Agency). 1983b. Surface Impoundment Assessment
National Report. Washington, DC.
U.S. EPA (Environmental Protection Agency). 1987. Draft Final Report: Screening Survey of
Industrial Subtitle D Establishments. Washington, DC.
U.S. EPA (Environmental Protection Agency). 1994. Memorandum from Carol M. Browner to
Assistant Administrators et al.: Peer Review Program. Washington, DC.
U.S. EPA (Environmental Protection Agency). 1998. An SAB Report: Review of the Surface
Impoundments Study (SIS) Plan. Washington, DC.
U.S. EPA (Environmental Protection Agency). 1999a. A Guide for Industrial Waste
Management. EPA530-R-99-001. Washington, DC: U.S. Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1999b. Revised Risk Assessment for the Air
Characteristic Study Volume I Overview. EPA 530-R-99-019a. Washington, DC:
U.S. Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1999c. EPA Supplemental Environmental
Projects Policy, Questions and Answers for the Practitioner. Office of Enforcement and
Compliance Assurance, Washington, DC.
1-18
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March 26, 2001 Chapter 1
U.S. EPA (Environmental Protection Agency). 2001. Class I Underground Injection Control
Program: Study of the Risks Associated with Class I Underground Injection Wells.
Office of Groundwater and Drinking Water, Washington, DC.
1-19
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March 26, 2001 Chapter 2
Chapter 2
Characterization of Industrial Surface Impoundments
This chapter presents the survey findings of EPA's 5-year study of the population of
surface impoundments that manage industrial nonhazardous wastewaters. This presentation
accompanies the risk assessment results discussed in Chapter 3 and the regulatory gap findings
addressed in Chapter 4. Main findings are discussed under the following sections:
2.1 Overview of Surface Impoundment Population
2.2 Chemicals and Management Practices at Surface Impoundments
2.3 Factors Related to Transport of Chemicals from Surface Impoundments
2.4 Proximity of Humans to Surface Impoundments
2.5 Regulatory, Exemption/Exclusion, and Operating Status of Surface
Impoundments
2.6 Conclusions
For background information on EPA's study, including the sampling methodology and survey
instrument, see Chapter 1 and Appendix A. A more detailed presentation of the data from the
survey is provided in Appendix B of this report.
2.1 Overview of Surface Impoundment Population
This section provides an overview of surface impoundment population characteristics,
such as impoundment age, location, industrial classification, and size.1 The data presented here
portray a snapshot in time and, therefore, cannot account for changes in given industrial sectors
that have already taken place since the survey or may take place at some point in the future.
1 Throughout this chapter, rounded figures on the number of facilities, number of impoundments, and total
wastewater volume are presented in the text. Estimates of these variables shown in tables and figures are left
unrounded. Due to differing patterns of missing data, the weight adjustments for missing data lead to slightly
different estimates presented for the same variable in some tables/figures. See Appendix B for the standard errors
associated with these estimates.
-------
March 26, 2001 Chapter 2
2.1.1 Population of Surface Impoundments
EPA estimates that there are approximately 18,000 industrial nonhazardous surface
impoundments2 located at 7,500 facilities that received waste between June 1990 and June 2000
and met the other criteria for being in this study. Of these nonhazardous industrial
impoundments, approximately 11,900 manage wastewaters that contain one or more chemicals of
concern and/or have either high or low pH (see Table 2-1). These impoundments are located at
an estimated 4,500 facilities and account for roughly 650 million metric tons (t) of wastewater
quantity managed. Although only 15 percent of these facilities manage any decharacterized
wastes, the volumes of decharacterized wastewater managed make up 70 percent of the entire
wastewater quantity. This study presents results for these 11,900 impoundments that contain
wastewaters with chemicals/pH of concern.3
Management of wastewaters in impoundments can include storage, treatment, and, in
some cases, disposal. Approximately two-thirds of all facilities have more than one
impoundment onsite and roughly 5 percent have more than 10 impoundments onsite that manage
wastewaters. Usually, storage and treatment functions are performed before the wastewater is
discharged to a surface waterbody under a National Pollutant Discharge Elimination System
(NPDES) permit; facilities employing this approach are often referred to as "direct dischargers."
As shown in Table 2-1, there are 3,940 facilities and 10,990 surface impoundments that manage
approximately 618,000,000 metric tons of wastewater through direct discharge.4
Impoundments used for disposal of wastewater are referred to as "zero discharge"
impoundments. The practice of wastewater disposal in impoundments is less common than
storage and treatment of wastewater in impoundments. Disposal is usually achieved by allowing
the wastewater to evaporate or to percolate into the ground and does not include discharge to a
surface waterbody. EPA estimates that there are 510 zero discharge facilities, or 880
impoundments, that manage approximately 27,000,000 metric tons.
In the economic sectors that are the subject of this study, surface impoundments are used
for the management of wastewater, stormwater, and cooling water. As shown in Figure 2-1, the
majority of impoundments were constructed within the past 30 years. Furthermore, 40 percent of
impoundments came on line in the 1970s, probably in response to environmental programs
promulgated early in that decade requiring greater treatment of industrial wastewaters. The
impoundments that were in operation before 1970, approximately one-quarter of the population,
were likely employed in some aspect of water supply management associated with the industrial
processes at these facilities.
Actual estimates of the number of industrial nonhazardous waste impoundments vary from 16,700 (based
on the long survey) to 18,400 (based on the screener survey). See Appendix A for a detailed discussion of these
estimates.
3 In comparison, in the United States today, there are just under 50 facilities with roughly 200 surface
impoundments that are used to manage hazardous waste. These hazardous waste surface impoundment figures are
based on data extracted from EPA's RCRAInfo in January 2001.
4 Number for facilities, impoundments, and quantities of wastewater managed are rounded in this chapter.
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March 26, 2001
Chapter 2
Table 2-1. Overview of Facility, Impoundment, and Wastewater Quantity Estimates
Characteristic
Estimated number of facilities
Estimated number of impoundments
Total quantity of wastewaters managed
(metric tons)3
Direct
Dischargers
3,944
10,987
627,218,336
Zero
Dischargers
512
876
27,250,309
Total
Population
4,457
11,863
654,468,645
The estimate of the wastewater quantity for the total population differs from the estimates shown in Tables 2-2
and 2-15. This is due to missing data associated with this variable. Refer to Appendix A on missing data and
Appendix B for the standard error associated with this variable.
5,000
T? 4,500
-I—-
g> 4,000
(U
I' 3'500
| 3,000
§ 2,500
o
E" 2,000
M—
% 1,500
§ 1,000
500
0
(4,226)
(1,213)
(1,446)
(0)
(114)
(409)
(2,382)
(2,073)
Before 1900 1940-1949 1960-1969 1980-1989
1900-1939 1950-1959 1970-1979 1990-2000
Year Impoundments Began Receiving Waste
Figure 2-1. Distribution of 11,863 impoundments by year unit began receiving
waste.
2.7.2 Location of Surface Impoundments
Generally, surface impoundments are located in areas with fairly significant precipitation
levels and availability of water. Figure 2-2 shows the breakdown of the 11,900 impoundments
from the survey by EPA Region across the United States. The greatest proportion of
impoundments are located in Gulf Coast states and along the East Coast. EPA's Region 3 has
the greatest density of impoundments per 100 square miles; EPA Region 4 has the highest
number of impoundments. Zero discharge facilities are generally distributed across the regions
evenly, with the exception of EPA Regions 1 and 8, which have none.
2-3
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March 26, 2001
Chapter 2
Region 2
312
601
Hawaii
D
Region 2
312
Puerto Rico
Virgin Islands
Legend
Surface impoundments
per 1 00 square miles
| I 0 1 -0.2
[ I 0.3-0.4
| I 0 5-0.7
• 1.6
EPA Regions are labeled
with estimated number of
surface impoundments.
The national total across all
Regions is estimated to
be lljS62 impoundments,
Figure 2-2. Regional distribution of surface impoundments.
2.7.3 Breakdown of Surface Impoundments by Industry
Surface impoundments have been and continue to be used widely in the management of
industrial wastewaters. For this study, EPA chose a scope of economic activities that generally
matched the "industrial" categories of the December 1983 Surface Impoundment Assessment
National Report, focusing on the manufacturing sector, along with certain other economic sectors
that were likely to have surface impoundments with wastes containing chemical constituents.
The nonmanufacturing sectors included were trucking, motor freight terminal maintenance,
airports, the waste management and sanitary services sector, industrial supplies, chemical and
allied product bulk storage, petroleum bulk stations, national security, and miscellaneous
services. (See Chapter 1 and Appendix A for a discussion of the industry coverage in the sample
selection for the study.)
According to the survey data, approximately two-thirds of the total wastewater quantity
managed in the 11,900 impoundments is managed at paper and allied product sector facilities
(see Table 2-2). This industrial sector, however, represents only 6 percent of the population of
facilities and just over 10 percent of all impoundments. Furthermore, an analysis at the 4-digit
2-4
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March 26, 2001
Chapter 2
Table 2-2. Breakdown by 2-Digit SIC Code of Surface Impoundments that Manage
Chemicals/pH of Concern and of Quantities of Wastewater Managed
SIC Code Descriptor
Chemical and Allied Products (SIC 28)
Stone, Clay, Glass, Concrete Products (SIC 32)
Wholesale Trade-Nondurable Goods (SIC 51)
Primary Metals Industry (SIC 33)
Food and Kindred Products (SIC 20)
Petroleum and Coal Products (SIC 29)
Paper and Allied Products (SIC 26)
All Other SIC Codes
Percent of
4,457
Facilities
19
15
12
10
8
7
6
23
Percent of
11,863
Impoundments
23
13
10
8
8
11
12
15
Percent of
653,314,426 a
Metric Tons
Wastewater
9
1
4
7
5
6
66
2
SIC = Standard Industrial Classification.
a The estimate of the wastewater quantity for the total population differs from the estimates shown in Tables 2-1
and 2-15. This is due to missing data associated with this variable. Refer to Appendix A on missing data and
Appendix B for the standard error associated with this variable.
Standard Industrial Classification (SIC) code level reveals that roughly 40 percent of the total
wastewater quantity falls in the pulp mills industry (SIC 2611), a sub sector of the paper and
allied products industry.
Examining the data in Table 2-2 regarding the overall industrial coverage, the top four
sectors account for 56 percent of the population of facilities; these sectors are chemical and allied
products; stone, clay, glass, concrete products; wholesale trade-nondurable goods; and primary
metals. These sectors manage only 20 percent of the total wastewater volume. The breakdown
of industries differs at the impoundment level. The chemical and allied product sector and the
stone, clay, glass, concrete products sector represent an estimated 36 percent of the population of
impoundments. However, the next highest sectors in impoundment representation are the
petroleum and coal product sector and the paper and allied products sector, with a total of
23 percent of the impoundments in the population.
2.1.4 Surface Impoundment Size and Appearance Characteristics
Impoundments vary considerably in surface area and depth. A size breakdown of
impoundment surface area for the impoundment population is shown in Table 2-3. The depth of
the impoundment can fluctuate, especially with larger units. These factors determine the overall
volume of wastewater managed in any given impoundment. The relationship of impoundment
surface area and wastewater volume is discussed in Section 2.2.3.
2-5
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March 26, 2001 Chapter 2
Table 2-3. Breakdown of Impoundment Surface Area
Size Range
(hectares)
0 to 1/4 hectares
1/4 to 1 hectares
1 to 5 hectares
5 to 10 hectares
10 to 5 00 hectares
Impoundment Surface Area
(Percent of 11,863 Total)
6,013 (51%)
2,953 (25%)
1,989 (17%)
456 (4%)
452 (4%)
As shown in Table 2-3, 51 percent of all impoundments have a surface area of 1/4 hectare
or less. The medium size range of impoundments, from 1/4 to 5 hectares, constitutes 42 percent
of the total population. The upper 8 percent of impoundments range from 5 to 500 hectares in
size. The direct and zero discharge populations each have roughly the same size breakdown as
that shown in Table 2-3 for the total population of impoundments.
Figures 2-3 through 2-5 show three pictures of impoundments taken during EPA's field
sampling (see Appendix E for details on field sampling). Surface impoundments range from
engineered structures that have the appearance of being man-made to marsh-like areas that an
observer might not realize were used for wastewater management. Some have vegetation
growing in the impoundments; many have vegetation growing along the edges. For
impoundments with "liner" systems (one or more layers of material placed on the sides and
bottom to prevent the wastewater from seeping into the ground), the aboveground part of the
liner may be visible. Frequently, equipment such as pumps, flow control devices, and aeration
equipment is present. There can be vehicle access roads constructed on top of the berms that
form the sides. The color of the wastewater can be many different hues, and the wastewater can
have a floating layer of oil or grease, a frothy appearance from foam, and/or a distinct odor.
Impoundments can be located immediately adjacent to agricultural or residential areas or in areas
of heavy industrial concentration.
2.2 Chemicals and Management Practices at Surface Impoundments
Surface impoundments provide a relatively low-maintenance/low-cost method of
effectively managing nonhazardous wastewater, and thus serve a useful purpose in protecting
waterbodies from receiving highly contaminated industrial wastes. However, impoundments can
have an impact on the environment: chemicals can volatilize from the wastewater surface,
contamination of the groundwater can occur if wastewater leaches from the impoundment, and
nearby surface waterbodies can become polluted. Additionally, impoundments can experience
overtopping releases through significant precipitation events or berm failure.
2-6
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March 26, 2001
Chapter 2
Figure 2-3. Surface impoundment located at a fruit processing facility.
Figure 2-4. Surface impoundment at a petroleum refinery.
2-7
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March 26, 2001
Chapter 2
Figure 2-5. Surface impoundment at a nylon manufacturing plant.
This section describes the sources for the chemical data used in this study, discusses the
chemicals that can be present in wastewater and sludge in impoundments, identifies
impoundment size and wastewater volume characteristics of the population of impoundments,
and examines the management practices employed at surface impoundments.
2.2.7 Data Sources for Chemical Data
In this study, EPA is using two sources of data to identify the chemicals present in the
impoundments and to quantify the amounts of those chemicals that are present: survey data and
field sampling data.
2.2.1.1 Survey Data. In the SI survey, EPA requested that respondents identify the
chemicals of concern present in their impoundments and, if known, state the average quantity of
each chemical present
• In the preceding 3-year period, or
• In any 3-year period since 1990, if no data were available for the most recent
3-year period.
2-8
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March 26, 2001 Chapter 2
EPA encouraged respondents to conduct analytical tests to produce their answers, but allowed
respondents to report estimates based on their knowledge of their wastes and processes. If data
were unavailable, the survey respondents were not required to provide information. However,
many survey respondents conducted sampling in order to respond to the survey.
Based on the survey data, methanol, fluoride, acetone, manganese, zinc, barium, and
nickel are present in the greatest quantity in wastewater. See Section 2.2.2 for a more detailed
discussion of frequently occurring chemicals.
2.2.1.2 Field Sampling Data. Of the major industry categories represented in the survey
sample, EPA selected 12 facilities and, based on the survey responses and general knowledge of
each industry, identified chemicals likely to be present in those facilities' impoundments. EPA
then visited the facilities to obtain wastewater and sludge samples, analyzed those samples, and
used the field sampling data for comparison with the survey data.6 For more information on the
field sampling, see Appendix E of this report. EPA performed the field sampling to accomplish
two primary objectives. The risk assessment relies on the survey data regarding the presence and
quantities of constituents. If the survey data on constituent quantities do not reflect the actual
quantities of constituents in an impoundment (that is, are inaccurate), then the risk assessment
results based on those data will be inaccurate as well. Similarly, if survey respondents did not
report all the constituents present in an impoundment, then the survey data on the presence of
constituents will be incomplete and the risk assessment results will likewise be incomplete. The
field sampling effort provided an independent check, or verification, of the survey data on
constituent presence and quantities. Thus, the field sampling objectives were
• To evaluate the degree to which the concentrations of constituents reported in the
survey agree with the concentrations measured in the field
• To evaluate the degree to which the field sampling results revealed omissions in
the reported survey data on presence and quantities of constituents.
For those constituents reported in the survey data and for which the field sampling
confirmed their presence at the particular facilities and impoundments, the reported survey data
values of chemical quantity agree, in most instances, within an order of magnitude of the
corresponding field sampling quantity (see Figure 2-6). Furthermore, in almost all instances, the
reported survey values agree within 2 orders of magnitude of the corresponding field sampling
values. This finding indicates that, where chemical constituents were reported by survey
respondents, EPA's field sampling did not find evidence of underreporting.
One limitation of this comparison is the fact that the survey requested average values over
a 3-year period, while the field sampling data were obtained on a 1- or 2-day visit. Another
limitation is that, because the facilities selected for field sampling were not chosen randomly, the
results cannot be statistically extrapolated. However, EPA believes that the comparisons provide
useful insights into the overall quality of the survey data and into certain critical areas of
uncertainty in the risk assessment.
6 For more information on the field sampling, see Appendix E of this report.
-------
March 26, 2001
Chapter 2
Survey values lOOtirrES EPAsarrple analysis result
Survey values 10tirres EPAsarrple analysis result
EPAsarrple analysis result 10tirres survey value
EPAsarrple analysis result 100 tirres survey value
EPA sample analysis result 1000 tirres survey value
Ratios in Rank Order (all data pairs except pH)
Figure 2-6. Relationship between survey values and corresponding EPA measurements.
As an indication of whether constituents might tend to be present that were not reported
in the survey, EPA compared the number of constituents reported by each of the 12 field
sampling facilities with the number of constituents found in the field sampling. Table 2-4
presents the results of this comparison.
Table 2-4 suggests that the reported survey data on the presence of chemical constituents
may be incomplete. At each of the 12 facilities visited for sampling, EPA found unreported
constituents above a limit of detection. The number of unreported constituents found at a facility
ranged from 3 to 30.
Based on the agreement between the concentrations reported in the survey and those
measured during EPA's field study, EPA has concluded that there is no reason to question the
concentration data provided in the facility survey. However, based on the discrepancies observed
as to the presence of some constituents in the impoundments sampled, there is evidence to
suggest that facility operators do not necessarily have comprehensive knowledge of all the
individual constituents contained in their impoundments.
2-10
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March 26, 2001
Chapter 2
Table 2-4. Constituents Confirmed with Field Sampling and Unreported Constituents
Facility
SIC Code
2037
2621
2611
2821
2819
2911
2911
3087
3273
3313
3353
3674
SIC Description
Fruit processing
Paper mill
Pulp mill
Nylon manufacturing
Inorganic chemicals
Petroleum refinery # 1
Petroleum refinery #2
Rubber mixing
Ready mix concrete
Electrometallurgical products
Aluminum manufacturing
Semiconductors
No. Of
Constituents
Reported in
Survey"
0
15
11
8
6
55
11
10
0
17
7
4
No. Of Same
Constituents
Detected in
Corresponding
EPA Sample
0
8
10
6
4
17
11
5
0
15
7
4
No. Of
Additional
Constituents
Detected by
EPA and Not
Reported
by Facility
11
18
30
18
13
7
13
3
10
13
11
9
SIC = Standard Industrial Classification.
a Includes concentration values reported as "<", and constituents reported as "present but quantity unknown.'
There are a variety of possible reasons for these discrepancies. For example, EPA used
high-quality analytical procedures enabling the quantification of constituents that are present at
low levels. In addition, impoundment operators may only be required to monitor for a limited
number of indicator chemicals and, as a consequence, may only track and therefore report one
chemical among a larger class of chemical constituents.
Where chemical data are discussed in the remainder of this chapter, data from the survey
database are used. For a more complete discussion of the field sampling data, please see
Appendix E of this report.
2.2.2 Chemicals Managed in Surface Impoundments
As stated in Section 2.1.1, the impoundments addressed in this study are those that
manage wastewaters that contain chemicals or pH of concern. Of the 11,900 impoundments that
meet this criterion, just over 90 percent had chemicals of concern and roughly 10 percent had pH
2-11
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March 26, 2001
Chapter 2
of concern. According to the survey data, approximately half of all facilities (15 percent of
wastewater quantity managed) employ impoundments to manage five or fewer chemicals.
Figure 2-7 shows the distribution of chemicals present on a per impoundment basis for
wastewater influent, wastewater in impoundment, and sludge. The industry sectors that employ
impoundments to manage more than 20 chemicals are chemical and allied products, paper and
allied products, petroleum and coal products, and primary metals. A more detailed examination
of the chemicals found in impoundments across SIC codes is provided in Appendix B.
A breakdown of chemicals present, by chemical category, for wastewaters and sludges is
shown in Table 2-5. This table displays chemical presence based on "influent," "in
impoundment," and "effluent" sampling points. The figures in this table represent the number of
impoundments that contain chemicals from the given chemical category (shown under "# Imps"),
and the percentage of the total volume of wastewater that contains chemicals from the given
chemical category (shown under "% Vol").
As shown in Table 2-5, metals are the most prevalent chemical category found in
wastewaters across the population of impoundments, present in 9,970 impoundments at influent
and 7,760 impoundments at effluent sampling points. Furthermore, approximately 85 percent of
9,000
8,000
« 7,000
03
E 6,000
T3
o 5,000
4,000
3,000
2,000
1,000
0
Wastewater influent
Wastewater in impoundment
Sludge
0-5
>25
6-10 11-15 16-20 21-25
Number of Target Chemicals per Impoundment
Note: For a detailed examination of the number of chemicals found in impoundments by SIC code, see
Appendix B.
Figure 2-7. Number of chemicals in wastewater and sludge managed in
impoundments.
2-12
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March 26, 2001
Chapter 2
Table 2-5. Breakdown of Chemical Categories for Wastewater and Sludge (at Different
Sampling Points) on Impoundment and Volume Basis
Chemical Categories
VOCs
SVOCs
Metals
Dioxin-like compounds
Mercury
Any chemicals
Wastewater
Influent
#
Imps
5,866
3,824
9,966
291
2,483
10,745
%
Vol
76
75
84
24
27
96
In
Impoundment
#
Imps
5,412
3,786
9,982
218
2,479
10,766
%
Vol
76
75
83
21
30
97
Effluent
#
Imps
4,815
3,508
7,762
346
2,235
8,187
%
Vol
72
69
85
22
31
92
Sludge
Influent
#
Imps
1,690
863
3,925
247
1,061
4,101
%
Vol
4
7
42
10
0.9
45
In
Impoundmen
t
#
Imps
2,006
1,261
5,551
861
1,745
5,759
%
Vol
21
24
98
35
66
100
Effluent
#
Imps
1,311
605
3,078
412
826
3,230
%
Vol
14
3
88
41
6
89
# Imps = number of impoundments.
% Vol = percent of total volume.
SVOCs = Semivolatile organic compounds.
VOCs = Volatile organic compounds.
wastewater volumes contain metals. Dioxin-like compounds are the least common category of
chemicals found in wastewaters across the population of impoundments, present in 290
impoundments at influent and 350 impoundments at effluent sampling points. However, just
over 20 percent (between 21 and 24 percent) of wastewater volume contains dioxin-like
compounds.
Metals are also the most common chemicals present in sludges across the population of
impoundments, showing up in 3,930 impoundments at influent and 3,080 impoundments at
effluent sampling points. A comparatively higher number of impoundments contain metals in
sludge at the "in impoundment" sampling point, approximately 5,500 impoundments. Dioxin-
like compounds are the least common category of chemicals in sludge managed in
impoundments, present at between 250 impoundments at influent and 410 impoundments at
effluent sampling points. There is also a comparatively higher number of units, 860
impoundments, with dioxin-like compounds at the "in impoundment" sampling point.
The most common constituents (by volume) in each chemical category are
• VOCs: methanol, acetone, methyl ethyl ketone, and acetaldehyde
• SVOCs: ethylene glycol, phenol, cresols, and aniline
• Metals: manganese, zinc, barium, and nickel.
2-13
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March 26, 2001 Chapter 2
In addition, two inorganic chemicals, sulfides and fluoride, are commonly present in wastewater
volumes. These data are provided in Appendix B, along with presence and volume estimates for
all SIS chemicals.
The pH criteria (pH between 2 and 3 or pH between 11 and 12.5) was not a significant
issue at the impoundments addressed in this report. Approximately 3 percent of impoundments
were in the acidic range, almost all of which managed never characteristic wastewaters. Roughly
8 percent of impoundments were in the basic range, the vast majority of which never managed
characteristic wastes.
Table 2-6 presents data on the wastewater influent concentrations for 11 toxicity
characteristic (TC) constituents that are managed in impoundments (see 40 CFR 261.124,
Table 1). These 11 constituents are among the most frequently occurring across the population
of impoundments, with all but cresol being in the top 25 chemicals; cresol is ranked 35th by
presence. Appendix B, Table B-19a shows a complete breakdown of chemicals by presence and
by wastewater quantity.
As the data show, arsenic, benzene, and cadmium have 50th percentile concentrations for
never characteristic, decharacterized, or all impoundments that are above a screening factor
health benchmark for cancer or noncancer effects. For the 90th percentile concentrations,
selenium is added to that list. Barium, chloroform, chromium, mercury, and methyl ethyl ketone
have 90th percentile concentrations that are within an order of magnitude of a human health
screening factor. Benzene is the lone chemical to have 90th percentile wastewater influent
concentrations for never characteristic and for all impoundments above the TC level. Arsenic,
barium, benzene, cadmium, chloroform, chromium, lead, and selenium show concentrations that
are above the TC level at a few impoundments (see Appendix B for histograms of the full
concentration distributions for these TC chemicals). The never characteristic and
decharacterized concentration breakdowns do not reveal any clear trends regarding chemical
concentration.
In Table 2-7, EPA presents data on the facility-level co-occurrence of chemicals in
wastewater by human health effect. Facility-level co-occurrence is defined as two or more
chemicals with a common target health effect occurring within or across impoundments at a
single facility. These figures on co-occurrence of chemicals with a common target health effect
do not account for the potential variance of the effects that may result within the same target
health effect category, nor does this evaluation consider chemical concentration with regard to
co-occurrence. However, EPA did consider chemical concentration and co-occurrence in the risk
analysis. Specifically, EPA's risk analysis examined the risks caused by exposure to multiple
contaminants from the same impoundment and facility and found only a single instance where
co-occurrence led to a risk of concern. (See Appendix C, Section C.I, which provides
information on the assessment of cumulative risks.) The evaluation of chemical co-occurrence
was specifically called for as a part of the consent decree (EDF v. Whitman).
As the data show, the top five target health effect categories for facilities with two or
more chemical co-occurrences in wastewater are kidney, liver, neurological, cancer, and
hematological. The target health effect categories that have facilities with co-occurrences of
2-14
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March 26, 2001
Chapter 2
Table 2-6. Comparison of 50th and 90th Percentile Influent Wastewater
Concentrations with Toxicity Characteristic (TC) Limits and Health-Based
Screening Factors for Selected Chemicals
Chemical
Arsenic
(7440-38-2)
Barium
(7440-39-3)
Benzene
(71-43-2)
Cadmium
(7440-43-9)
Chloroform
(67-66-3)
Chromium
(7440-47-3)
Cresol
(1319-77-3)
Lead
(7439-92-1)
Mercury
(7439-97-6)
Methyl Ethyl
Ketone (MEK)
(78-93-3)
Selenium
(7782-49-2)
Screening
Factor3
(mg/L)
Care.
6.6E-04
NA
1.8E-02
NA
1.6E-01
NA
NA
NA
NA
NA
NA
Noncarc.
6.9E-03
1.6E+00
NA
1.2E-02
2.3E-01
6.9E-02
1.2E+00
NA
6.9E-03
1.4E+01
1.2E-01
TC
Limit b
(mg/L)
5.0
100.0
0.5
1.0
6.0
5.0
200.0
5.0
0.2
200.0
1.0
Influent Wastewater Concentrations (mg/L)
50th Percentile
Never
Charac-
eristic
9.0E-03
1.3E-01
8.0E-01
1.8E-02
4.0E-03
6.0E-03
NA
2.0E-02
6.0E-05
O.OE+00
2.0E-03
Decharac-
terized
6.9E-03
l.OE-01
1.6E-02
3.1E-03
1.9E-02
6.4E-03
4.1E-02
5.7E-03
5.9E-04
7.4E-01
8.0E-03
All
Impound-
ments
9.0E-03
1.3E-01
2.1E-02
3.1E-03
4.0E-03
6.4E-03
3.1E-02
l.OE-02
3.0E-04
6.1E-01
5.3E-03
90th Percentile
Never
Charac-
teristic
1.3E-02
3.2E-01
1.1E+00
7.9E+00
1.1E-02
2.5E-02
NA
2.0E-02
6.0E-04
2.5E-02
1.4E-01
Decharac-
terized
2.1E-02
4.5E-01
9.0E-02
7.0E-03
1.1E-01
2.7E-02
1.1E-01
2.0E-02
7.5E-03
5.9E+00
4.8E-02
All
Impound-
ents
2.1E-02
3.5E-01
8.0E-01
1.5E-01
3.0E-02
2.7E-02
1.1E-01
2.0E-02
3.8E-03
5.9E+00
1.4E-01
NA = Not available.
a Human health screening factors for carcinogens (care.) and noncarcinogens (noncarc.) in drinking
water. See Appendix C, Attachment C-3.
b Source: RCRA §261.24, Table 1 - Maximum Concentration of Contaminants for the Toxicity
Characteristic
between 11 and 20 chemicals in wastewater within/across impoundments are liver, cancer,
kidney, and neurological; liver has the most facilities within this range, at 221. Additional
evaluation of the co-occurrence of chemicals in wastewaters and in sludge is shown in
Appendix B.
2-15
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March 26, 2001
Chapter 2
Table 2-7. Co-occurrence of Chemicals in Wastewater by Human Health Effect
Target Health
Effect3
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Estimated Number of Facilities with Co-occurrences15 in
Wastewater
Number of Chemicals Co-occurring Within/
Across Impoundments0
2-3
621
0
0
984
0
0
0
635
13
0
0
0
1,246
1,099
0
972
766
0
0
873
13
123
832
0
238
0
4-6
328
0
0
193
0
0
0
11
0
0
0
0
76
799
0
339
64
0
0
696
0
0
131
0
0
0
7-10
390
0
0
13
0
0
0
0
0
0
0
0
11
111
0
212
0
0
0
73
0
0
0
0
0
0
11-20
30
0
0
0
0
0
0
0
0
0
0
0
0
11
0
221
0
0
0
10
0
0
0
0
0
0
All Facilities
with Two or
More
Co-ocurrences
1,369
0
0
1,191
0
0
0
646
13
0
0
0
1,334
2,020
0
1,743
830
0
0
1,653
13
123
962
0
238
0
(continued)
2-16
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March 26, 2001
Chapter 2
Table 2-7. (continued)
Estimated Number of Facilities with Co-occurrences'5 in
Wastewater
Target Health
Effect3
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/
Across Impoundments0
2-3
0
0
6
4-6
0
0
0
7-10
0
0
0
11-20
0
0
0
All Facilities
with Two or
More
Co-ocurrences
0
0
6
a For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based.
Cancer or leukemia for carcinogenic chemicals. See Appendix C for discussion of health
benchmarks.
b A facility-level co-occurrence is defined as when two or more chemicals with a common target
health effect occur within or across impoundments at a single facility.
0 Lists of the co-occurring chemicals at each facility in the sample are provided in Appendix B.
2.2.3 Surface Impoundment Size and Wastewater Volume Characteristics
Impoundment size is an important variable in the assessment of wastewater volumes and
the potential for environmental releases. As shown in Figure 2-8, approximately 75 percent of
the total wastewater quantity for all impoundments exists at roughly 10 percent of the
impoundments; these impoundments have surface areas that range from 5 to 500 hectares.
Alternatively, approximately half of all impoundments have surface areas under 1/4 hectare;
these 6,000 impoundments have a combined total of roughly 1 percent of the wastewater quantity
managed in all impoundments.
For a given impoundment surface area, the wastewater quantity in that impoundment will,
of course, vary based on depth of the impoundment as well as the potential for partial
impoundment dryness on a seasonal basis. Above each bar in the top histogram in Figure 2-8 is
the range of wastewater quantities in impoundments in the given size class. A clear example of
variance in wastewater quantities is seen for the 1/4- to 1-hectare size range. The wastewater
quantity for this group of impoundments varies from roughly 4 metric tons to over 1 million
metric tons.
The lower histogram in Figure 2-8 displays the number of impoundments broken out by
direct or zero discharge status above each bar. While zero discharge impoundments are present
at just over 10 percent of all facilities and make up approximately 7 percent of all impoundments,
they represent under 5 percent of the total wastewater quantity. Just over 400 zero discharge
impoundments (almost half of the 876 total zero dischargers) are under 1/4 hectare, while just 7
percent of the zero discharge impoundments are over 5 hectares in size.
2-17
-------
March 26, 2001
Chapter 2
_ 500
B 450
o
B 400
E
| 350
1 300
| 250
ro
a 200
- 0
(76-13,259,557)
64%
(606-757,061)
20%
(13,155-1,135,592)
(4-1,659,100)
(0.4-13,627) 5%
1%
10%
%
(A
0-1/4 1/4-1 1-5 5-10 10-486
Size of Impoundment (hectares)
percent of total wastewater managed
B) = range of lowest (A) to highest (B) wastewater quantity (metric tons) per impoundment
7,000
6,000
S 5,000
c
o 4,000
I"
o 3,000
i_
0)
| 2,000
1,000
(5,611/4
51%
fl
-
-
T7\
Q Direct Discharge Impoundments
|| Zero Discharge Impoundments
(2,711/242)
25%
n (1,821/1 69)
n
(435/20) (410/42)
4% 4%
I I I
0-1/4
10-486
1/4-1 1-5 5-10
Size of Impoundment (hectares)
% = percent of the total number of impoundments
(A/B) = number of direct discharge impoundments (A)/number of zero discharge
impoundments (B)
Figure 2-8. Total wastewater quantity and number of impoundments by
impoundment size.
2-18
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March 26, 2001
Chapter 2
Table 2-8. Facility Breakdown of Treatment Process
(Used by at Least One Impoundment)
Treatment Process
Facility Status
Direct dischargers
(3,944 facilities)
Zero dischargers
(5 12 facilities)
All facilities
(4,457 facilities)
Aeration
Number of
Impoundments
920
160
1,081
%
23
31
24
Sedimentation
Number
of
Impoundments
1,780
217
1,997
%
45
42
45
Other
Number
of
Impoundments
1,745
92
1,837
%
44
18
41
No Treatment
Number
of
Impoundments
2,091
232
2,323
%
53
45
52
% = percent of discharge category.
Several treatment processes may be used at the same facility. Therefore, the sum of the percentages for "all
facilities" does not total 100%.
Impoundment size is an important factor in assessing the potential for human exposure to
chemicals managed at these facilities. For the air pathway, volatilization potential can increase at
larger impoundments due to the increase in surface area exposed to the atmosphere at these
impoundments. Alternatively, greater impoundment size can allow for greater dilution of
chemicals and thus lower concentrations and reduced emissions (see Section 2.3.1). Similarly,
for the groundwater pathway, larger impoundments are less likely to be lined than are smaller
impoundments. Additionally, chemical releases to groundwater may be more difficult to detect
at larger impoundments due to the greater demand for monitoring well coverage. However, the
greater dilution of chemicals that often occurs in larger impoundments is again a mitigating
factor, reducing the potential that releases from the unit will be at high concentrations (see
Section 2.3.2).
2.2.4 Management Practices at Surface Impoundments
Management practices at impoundments can be broadly classified as aeration,
sedimentation, and other (including flocculation, coagulation, precipitation, filtration,
biotreatment, denitrification, disinfection, ion exchange, adsorption, and chemical oxidation).
Table 2-8 shows a breakdown of management methods at facilities by discharge type.
Approximately one-quarter of all facilities performed aeration in at least one impoundment, with
a slightly greater percentage of zero dischargers than direct dischargers conducting aeration.
Roughly 45 percent of all facilities have sedimentation occurring in an impoundment, while
approximately 40 percent of facilities employed some other treatment method. At half of all
facilities, no treatment was conducted. See Appendix B, Table B-10, for a detailed list of all
treatment types used in the survey.
2-19
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March 26, 2001 Chapter 2
Many facilities manage wastewaters in multiple impoundments, allowing different
methods of treatment to be conducted in different impoundments that are linked in the process
(e.g., aeration, biotreatment, and sedimentation). EPA did not assess the occurrence of staged
treatment at these facilities. This issue is discussed briefly with regard to transport of chemicals
in the atmosphere in Section 2.3.1.
2.3 Factors Related to Transport of Chemicals from Surface Impoundments
This section presents data on factors associated with the transport of chemicals in
wastewater from source to receptor via environmental media: air, groundwater, and surface
water. The presence of volatile organic compounds (VOCs), the use of aeration, and the size of
the impoundment are discussed for the air pathway. The depth to groundwater and presence of
liners are discussed for the groundwater pathway. The surface water pathway is treated as a
special case of groundwater transport. Therefore, the hydrogeological connectivity of
groundwater to surface water is discussed in this section; the possibility of surface water
contamination from occurrence of overtopping events is also briefly discussed.
2.3.1 Factors Related to Transport of Chemicals in Air
The uncontrolled release of VOCs from wastewaters is an area of concern. There are
many factors that affect the volatilization of a chemical from the water surface of an
impoundment and its subsequent transport in the atmosphere. These factors include the
properties of the chemical (e.g., its chemical-specific tendency to partition between water and
air), the temperature of the air above the impoundment and the wastewater in the impoundment,
the local meteorological conditions including wind speed and atmospheric stability class, and the
characteristics of the impoundment such as its surface area and aeration level.7 Additionally, the
mass of VOC present in the wastewater has an important influence on the overall emissions from
a given unit. The data on VOCs in wastewater, impoundment size, and aeration are discussed
below as they relate to potential air contamination.
Approximately 50 percent of impoundments manage wastewaters that contain VOCs (see
Table 2-9). However, roughly 75 percent of wastewaters by volume contain VOCs.
Additionally, 55 percent of direct dischargers have VOCs present in wastewaters, compared to an
estimated 20 percent of zero dischargers. As discussed in Section 2.2.2, the most common VOCs
(by volume) present in wastewaters are methanol, acetone, methyl ethyl ketone, and
acetaldehyde.
Impoundment size is an important factor influencing the atmospheric contaminant
concentration at a receptor point. EPA therefore examined the presence of VOCs by
impoundment size in a separate analysis. Approximately 70 percent of the very large
impoundments (those in the 5- to 500-hectare category) contain VOCs, while 50 percent of the
small impoundments (under 1 hectare) contain VOCs.
7 Surface impoundments are generally designed as open-air units. Relatively few are known to have a
cover or be under a roofed structure.
2^20
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March 26, 2001
Chapter 2
Table 2-9. VOC/Aeration Status for Impoundments
VOCs/Aeration
Treatment
No VOCs / aeration
VOCs / aeration
VOCs / no aeration
No VOCs / no aeration
All impoundments'1
Number of
Impoundments
804
939
5,350
4,770
11,863
Wastewater
Quantity
(metric tons)
44,276,182
306,608,296
253,540,050
154,075,362
758,499,891
Percent of Total
Wastewater
Quantity
6
40
33
20
100
The total wastewater quantity shown here for all impoundments does not equal the total
wastewater quantity shown in Table 2-1. This is due to the missing data associated with this
variable. Please refer to Appendix A for a discussion of how missing data were handled, and
Appendix B for information on the standard error associated with the wastewater quantity
estimate.
Aeration is a fairly common management practice for these impoundments and is
performed for various reasons to improve the efficiency of wastewater treatment. As discussed
in Section 2.2.4, aeration is performed at approximately 25 percent of all facilities. Using the
figures shown in Table 2-9, EPA estimates that approximately 45 percent of the total wastewater
volume is aerated. However, according to the same table, of the 1,743 impoundments where
aeration is conducted, 804, or almost half, show no presence of VOCs in wastewater. This is
understandable given that aeration may be employed for reasons other than treatment of volatiles,
such as for mixing coagulants in the wastewater or promoting aerobic biodegradation (Metcalf
and Eddy, 1991).
Of those impoundments conducting aeration, approximately 50 percent are under
1 hectare in size. However, almost 40 percent of impoundments in the 5- to 500-hectare size
range are employing aeration practices. These very large impoundments are likely aerated only
in particular areas of the impoundment.
As discussed in Section 2.2.4, facilities may employ more than one impoundment in the
process of managing industrial wastewaters. Approximately two-thirds of all facilities have more
than one impoundment onsite; roughly 5 percent have more than 10 impoundments onsite. In
such cases, a facility may have one aerated impoundment in conjunction with an impoundment
for sedimentation purposes or some other purpose. Information on the sequencing of
impoundments in multistage treatment processes at these facilities was not analyzed in this
report. However, any time wastewater containing VOCs experiences turbulence (as when it is
pumped from one unit to another), flows through a channel from one unit to another, or at any
discharge points in the process, releases to the atmosphere are likely (Metcalf and Eddy, 1991).
Therefore, the roughly 5,300 impoundments that contain volatiles but are not performing aeration
may still produce air emissions.
2-21
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March 26, 2001 Chapter 2
2.3.2 Factors Related to Transport of Chemicals in Groundwater
Moderate release of chemicals to the subsurface is a design feature of many zero
discharge impoundments, which make up just under 10 percent of the population of
impoundments addressed in this study. However, releases of chemicals at high enough
concentrations can, over time, result in contamination of drinking water supplies or of fishable
waterbodies, and thus potential risk to humans. Many factors influence the release and migration
of chemicals in groundwater. This section examines depth to groundwater and presence of an
impoundment liner for the population of impoundments addressed in this report. In addition,
EPA also addresses the discharge of groundwater to surface water, overtopping events, and the
data on monitoring wells used to detect releases to groundwater.
2.3.2.1 Depth to Groundwater. The distribution of the depths to groundwater relative to
the bottom of the impoundment is shown in Figure 2-9. Approximately 75 percent of
impoundments are located in areas where groundwater depth is within 4 meters of the bottom of
the impoundment, and almost 90 percent of impoundment bottoms are within 8 meters of
groundwater. There are no notable differences in depth to groundwater for the direct and zero
discharge subpopulations.
Given that over 90 percent of impoundments in the population are direct dischargers and
are located near surface waterbodies, it is not surprising to find that the impoundments are
located over relatively shallow groundwater. In fact, as Figure 2-9 shows, almost 20 percent of
impoundments have impoundment bottoms that are below the groundwater surface. Given their
proximity to surface water, many of these groundwater levels are likely to fluctuate seasonally or
with significant precipitation events.
Although the presence of generally shallow groundwater conditions is significant in terms
of the potential for groundwater transport of chemical from impoundments, not all shallow
groundwater is potable; thus, it is less significant in terms of risk to humans. Approximately
one-third of these groundwaters are not potable according to the survey respondents reporting
potability status.
2.3.2.2 Presence of Liner. Use of liners is an important method of preventing releases
from impoundments to the subsurface. The survey defined the term "liner" as
a continuous layer of natural or man-made materials, emplaced beneath and/or on
the sides of a surface impoundment, that restricts the downward and/or lateral
release of waste, waste constituents, or leachate from the surface impoundment.
The liner does not include naturally occurring materials (such as a naturally
occurring clay layer) that, although effective in controlling the release of leachate
from the surface impoundment, were not emplaced intentionally for that purpose.
EPA collected data on the presence of liners at impoundments, as well as the age and type
of liner and whether liner failure had occurred. Figure 2-10 displays information on liner usage
by impoundment, impoundment size, and wastewater volume. EPA estimates that approximately
5,000 impoundments, or approximately 40 percent of the population, are lined. However, just
2-22
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March 26, 2001
Chapter 2
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March 26, 2001
Chapter 2
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Lined Impoundments
132,759,481
43%/57%
31,120,581
46%/54%
[; 1
415,452,370
21%/79%
65,577,583
30%/70%
0-1/4 1/4-1 1-5 5-10
Size of Impoundments (hectares)
10-486
Total wastewater quantity (from lined and unlined impoundments) is presented
above each bar
(A%/B%) = percent of wastewater managed in lined impoundments (A)/percent
managed in unlined impoundments (B)
Size of Impoundment
(hectares)
Number of
Impoundments
Number of Lined
Impoundments
Number of Unlined
Impoundments
Depth to Groundwater
(m): median (lowest,
highest)
0-1/4
6,013
2,043
3,970
1.1 (-3.8, 64)
1/4-1
2,953
1,878
1,075
1.2 (-6.1, 44)
1-5 I 5-10
1,989 I 456
796 99
1,193 356
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10486
452
139
314
1.2 (-4.6, 41)
All
Impoundments
11,863
4,955
6,908
1.5 (-8. 2, 122)
Figure 2-10. Number of impoundments and wastewater volumes by liner
status.
2-24
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March 26, 2001 Chapter 2
under 25 percent of wastewater volumes are managed in lined units. This difference in the
percentage of lined impoundments and the percentage of wastewater quantities managed in lined
impoundments is attributable to the fact that larger units are lined less frequently. Just over 40
percent of impoundments under 1 hectare are lined, and 25 percent of those over 5 hectares are
lined. One-third of those impoundments with liners were from the chemical and allied products
industry sector.
There are a number of possible reasons why liners are used more frequently at smaller
units. Obviously, it is more economical and practical to line a smaller unit than to line a larger
unit. Additionally, many of the larger impoundments are likely older and were built to provide
access to large water supplies that were critical to the manufacturing process at these facilities.
They were, therefore, probably constructed in areas that would effectively contain water naturally
rather than built to rely on more modern liner technologies.
As engineered structures, liners are susceptible to design and operating flaws and to
routine wear and tear that can eventually reduce their ability to restrict flow. However, liner
failure can occur in just one layer of the liner at impoundments with multiliner systems or occur
in a place in the liner that is above the water surface, which would not necessarily result in a
release to groundwater. In addition, liner failure can occur in the freeboard area or next to
conveyances, making detection and repair relatively simple. EPA estimates that approximately
12 percent of the impoundments with liners experienced liner failure. Roughly 10 percent of all
wastewater volumes are managed in impoundments that have had a liner failure.
The effectiveness of a liner system depends in part on the type of liner installed. The data
on liner types are shown in Table 2-10. Almost 80 percent of the lined units have clay, flexible
membrane, or composite (flexible membrane and clay) liners. Forty-four percent of the units
lined have flexible membrane or composite liners, which are generally more effective than
alternative liner types. Asphalt was the least common liner type, employed at less than 1 percent
of lined impoundments.
2.3.2.3 Groundwater Discharge to Surface Water. Transport of chemicals from surface
impoundments to fishable waterbodies can occur through discharge of groundwater to surface
water. In cases where there is a direct hydrogeological connection between groundwater and
surface water, contaminant transport in groundwater can impact fishable waterbodies.
Survey data suggest that roughly 80 percent of all impoundments are above groundwater
systems that discharge to surface water. In addition, approximately 95 percent of impoundments
with a surface area over 5 hectares are above groundwater that discharges to surface water.
These larger impoundments constitute only 10 percent of the total impoundment population. In
addition, the size of these larger impoundments may allow for greater dilution of chemicals than
in smaller impoundments. However, given that only 40 percent of all impoundments are lined,
and that these larger impoundments are less likely to be lined than the smaller ones, they may
present a greater potential, at the impoundment level, for contamination of adjacent fishable
waterbodies.
2-25
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March 26, 2001
Chapter 2
Table 2-10. Number and Percentage of Impoundments by Liner Status
Liner Status
Compacted clay
Flexible membrane (FML)
Composite (FML and clay)
Concrete
Asphalt
Other
Unlined3
Total
Number of
Impoundments
1,680
1,584
536
629
55
363
7,017
11,863
Percentage of
Impoundments
14
13
5
5
<1
3
59
100
This estimate differs from the estimate of outlined impoundments shown in
Table 2-12. This is due to missing data associated with this variable. Refer to
Appendix A on missing data and Appendix B for the standard error associated
with this variable.
2.3.2.4 Overtopping Events. Overtopping of impoundments can result in contamination
of adjacent surface waterbodies through overland transport of wastewaters. EPA estimates that
one-quarter of all facilities had an overtopping event, which occurs where there is significant
precipitation, or dike or berm failure. An estimated 20 percent of the population of
impoundments have fishable waterbodies within 150 meters of the impoundment. And
approximately 20 percent of impoundments with fishable waterbodies within 150 meters
experienced an overtopping event. EPA did not analyze data on the magnitude of these
overtopping events due to concerns with their reliability. Therefore, the potential for impacts to
nearby aquatic systems from overtopping is unknown.
2.3.2.5 Monitoring Wells. Monitoring wells are installed to detect releases of chemicals
from impoundments to groundwater. One-third of the population of impoundments and roughly
the same percentage of facilities reported the presence of a monitoring well intended to detect
releases. Of these impoundments, 5 percent (189 units) detected a release of chemicals to
groundwater, as shown in Table 2-11.
Almost 50 percent of the impoundments with monitoring wells are solid waste
management units (SWMUs) at RCRA treatment, storage, and disposal (TSD) facilities (see
Section 2.5 for information on SWMUs). However, only one-third of the total population of
impoundments are SWMUs at RCRA TSDs. This increased attention to potential releases,
evidenced by the greater use of monitoring wells at these SWMUs, is not surprising given the
RCRA corrective action program's oversight at these facilities.
2-26
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March 26, 2001
Chapter 2
Table 2-11. Monitoring Well/Detection of Releases by Discharger Type
Discharger Type
Direct dischargers
Zero dischargers
All impoundments
Monitoring Well Present
Detected
Release
189
0
189
Did Not
Detect
Release
3,257
411
3,668
Total
Number
3,446
411
3,856
%
31
47
33
No Monitoring
Well to Detect
Release
Number
7,541
465
8,007
%
69
53
67
All Impoundments
Number
10,987
876
11,863
%
100
100
100
2.4 Proximity of Humans to Surface Impoundments
In this section, EPA examines the potential for human exposure to the chemicals
managed in impoundments. First, the general proximity of humans and human activities to
surface impoundments is addressed. Then, EPA focuses on the proximity of humans to potential
exposure points for air, groundwater, and surface water.
The industrial facilities that employ surface impoundments to manage nonhazardous
wastewater are located throughout the United States in a wide array of settings. Some facilities
are located in rural areas adjacent to agricultural land use, while other facilities are in heavily
populated residential areas or are part of a concentration of industrial activity (see Figures 2-3
and 2-4).
Within this diversity of settings, the potential for human exposure to chemicals managed
in these impoundments does exist. EPA estimates that roughly 20 million people (approximately
10 million residences) are located within 2 kilometers of an impoundment (see Table 2-12). Of
this population, roughly 50,000 people live within 150 meters of an impoundment. Additionally,
an estimated 540 schools are located within 500 meters of an impoundment.
Another indicator of potential exposure is the human activity that occurs near these
facilities. EPA's data suggest that farming occurs within 2 km of an impoundment at
approximately 40 percent of all facilities. Roughly half of all facilities have fishing within 2 km
of an impoundment, and two-thirds of all facilities identified swimming as occurring within 2 km
of an impoundment. Hunting is estimated to occur within 2 km of an impoundment at
approximately one in five facilities. Each of these activities represents a means by which an
exposure pathway could be completed (e.g., indirect exposure through ingestion of produce
grown at farms with significant air deposition of chemicals from an adjacent impoundment).
This overview of humans and human activities near surface impoundments suggests that
exposure is possible, given the potential for release of contaminants to air, groundwater, or
surface water. Section 2.3 of this report discusses several factors related to the possibility of
such environmental transport of chemicals from wastewater. In this section, these transport
2-27
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March 26, 2001
Chapter 2
Table 2-12. Proximity of Surface Impoundments to People, Residences,
Drinking Water Wells, and Schools
Distance from
Impoundment
(m)
0- 150m
151 -500m
501 -1,000m
1,001 -2,000m
People Living
within a
Given Distance
51,579
663,380
3,284,378
14,414,175
Residences
within a
Given Distance
21,227
285,411
1,341,834
5,898,810
Drinking Water
Wells within a
Given Distance
888
13,728
56,146
204,984
Schools within
a Given
Distance
0
541
2,390
8,990
GW= Groundwater.
factors are linked with the human proximity data to provide a closer look at the potential for
exposure.
2.4.1 Proximity of Humans to Surface Impoundments by Pathway
EPA has generally observed a significant decline in the concentration of airborne
chemicals in a plume as the distance from the source increases. Therefore, in assessing potential
exposure to chemicals through the air pathway, EPA examined the proximity of humans within a
150-meter radius of surface impoundments that manage VOCs. EPA estimates that just under
10 percent of all impoundments manage VOCs and have residences within a 150-meter radius
(see Table 2-13). Roughly half of these impoundments manage VOCs through aeration.
As discussed in Section 2.3.2 of this chapter, movement of a contaminant plume in
groundwater is influenced by a host of factors. These factors must be assessed at the facility
level for an accurate determination of the potential for human exposure through groundwater.
For the purposes of this chapter, EPA examined the proximity of wells and of fishable
waterbodies to impoundments in order to provide an overall picture of the potential for human
exposure through groundwater. Approximately 10 percent of all facilities (or 6 percent of all
impoundments) are estimated to have a drinking water well within 150 m of an impoundment
(see Table 2-14). Fifteen percent of those impoundments (approximately 100) are lined
impoundments. At a 2,000-meter radius from the impoundment, the proportion of
impoundments with wells jumps to 50 percent (approximately 6,000 out of 11,900), 45 percent
(approximately 2,700) of which are lined units.
EPA considered the potential for surface water contamination through groundwater at a
150-meter radius also. As discussed in Section 2.3.2, just over 80 percent of all impoundments
are located above groundwater systems that discharge to a fishable waterbody. Furthermore,
approximately 20 percent of all impoundments have a fishable waterbody within a 150-meter
radius.
2-28
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March 26, 2001
Chapter 2
Table 2-13. Proximity of Residences to Impoundments Based on Presence of VOCs
and Aeration Status
Proximity of Nearest Residences to
Surface Impoundments
(m)
VOC/Aeration Status of Impoundments3
0-
150
151-
1,000
1,001-
2,000
No Residences
within 2,000
Total
No VOCs in wastewater
Number of impoundments
Percent of total wastewater quantity
3,439
14%
2,173
8%
236
3%
101
<1%
5,947
25%
VOCs present in wastewater/no aeration
Number of impoundments
Percent of total wastewater quantity
458
8
4,123
24%
338
1%
44
<1%
4,963
33%
VOCs present in wastewater/aeration
Number of impoundments
Percent of total wastewater quantity
406
8%
433
29%
96
3%
18
2%
953
41%
Total
Number of impoundments
Percent of total wastewater quantity
4,303
30%
6,729
60%
670
8%
162
2%
11,863
100%
The estimates of the number of impoundments and the percent of total wastewater quantity shown in this
table do not agree with those shown in Table 2-9. This is due to the missing data associated with these
variables. Please refer to Appendix A for a discussion of how missing data were handled, and Appendix B
for information on the standard error associated with these variables.
EPA believes that the data discussed above on the proximity of humans to impoundments
with respect to the air, groundwater, and surface water pathways suggest that the potential exists
for human exposure to chemicals from these impoundments. The risk assessment work
discussed in Chapter 3 of this report evaluates this potential for human exposure.
2.5 Regulatory, Exemption/Exclusion, and Operating Status of Surface Impoundments
The 4,500 facilities examined in this study operate within an overall regulatory context.
This context may include permits requiring regular onsite activities, such as periodic sampling of
wastewater or routine contacts with regulators, or operational conditions calling for occasional
adjustments to treatment processes or monitoring of various aspects of facility operations and
monthly flow rates. At any given facility, this regulatory context is made up of federal, state, or
local regulations. For example, survey data show that approximately 80 percent of all
impoundments are under some level of regulatory oversight, either by virtue of a state or local
permit or as an SWMU at a RCRA TSD. Similarly, this regulatory context may include
exemptions or exclusions from such regulations. Survey data show that roughly 15 percent of
2-29
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March 26, 2001
Chapter 2
Table 2-14. Proximity of Nearest Wells to Impoundments Based on Liner Status
Liner Status of Impoundments
Proximity of Nearest Wells to Surface Impoundments
(m)
0-150
151-500
501-2,000
No Well
within
2,000
Total
Lined impoundments—no liner failures
Number of impoundments
Percent of total wastewater quantity
54
2%
541
5%
1,661
8%
1,809
4%
4,065
18%
Lined impoundments—with liner failures
Number of impoundments
Percent of total wastewater quantity
40
<1%
95
<1%
311
5%
38
<1%
484
6%
Unlined impoundments3
Number of impoundments
Percent of total wastewater quantity
569
6%
546
25%
2,173
28%
4,026
17%
7,314
75%
Total
Number of impoundments
Percent of total wastewater quantity
663
8%
1,182
30%
4,145
41%
5,873
21%
11,863
100%
The estimates of the number of unlined impoundments shown in this table do not agree with the number shown
in Table 2-10. This is due to the missing data associated with these variables. Refer to Appendix A for a
discussion of how missing data were handled, and Appendix B for information on the standard error associated
with this variable.
impoundments are used to manage wastewaters that are excluded or exempt from RCRA
regulations.
EPA collected data on the state, local, and federal regulations that apply at these facilities.
Additionally, any exemptions or exclusions that apply at the facility were identified. The survey
also requested information on the operating status of the impoundments at the facility. This
section presents the main findings from these data.
EPA first examined the data on whether impoundments had a state or local permit for any
wastewater or sludge management, groundwater protection activities, and/or air emissions
associated with the particular impoundment. As shown in Table 2-15, there are an estimated
3,600 facilities, or 80 percent of all facilities, with at least one impoundment that is under a state
or local permit. These 3,600 facilities represent over 95 percent of the wastewater quantities
managed in impoundments and are almost entirely NPDES permits for direct discharge to a
surface waterbody. Of the facilities that identified permits, 25 percent were chemical and allied
product facilities and roughly 15 percent were stone, clay, glass, and concrete product facilities.
2-30
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March 26, 2001 Chapter 2
The paper and allied product sector and the wholesale trade-nondurable goods sector each
accounted for just under 15 percent of these facilities.
Some impoundments examined in this study are solid waste management units at a
RCRA TSD facility and are, therefore, subject to federal requirements for remediation of
environmental contamination at the facility (40 CFR 264.101). Approximately one-quarter of all
facilities (one-third of all impoundments) are RCRA TSD facilities with SWMUs onsite that
have been through a RCRA Facility Assessment (RFA), as shown in Table 2-15.8 Of those
impoundments in this group, two-thirds are chemical and allied product impoundments and one-
quarter are petroleum and coal product impoundments.
EPA gathered information on the management of exempt/excluded wastewaters in
impoundments. As shown in Table 2-15, approximately 15 percent (1,700 impoundments) of the
population manage some exempted or excluded wastewaters. Of those impoundments in this
group, roughly 35 percent are paper and allied product impoundments, 35 percent are chemical
and allied product impoundments, and 20 percent are petroleum and coal product impoundments.
These wastewaters are identified as being exempt or excluded from RCRA Subtitle C regulation
under a number of possible exemption/exclusion categories. This volume, approximately
98,800,000 metric tons, represents 15 percent of the total wastewater quantity managed in
impoundments. As shown in Table 2-16, the exclusions and exemptions cited include those for
point source discharges (40 CFR 261.4(a)(2)), mixtures of solid waste and characteristic-only
hazardous waste (40 CFR 261.3(a)(2)(iii)), Bevill wastes (40 CFR 261.4(b)(7) and
3001(b)(3)(A)(ii)), coal and fossil fuel combustion wastes (40 CFR261.4(b)(4) and
3001(b)(3)(A)(i)), and mixtures of solid waste and hazardous waste discharging to Clean Water
Act systems (40 CFR 261.3(a)(2)(iv)). For more details on these exclusions and exemptions,
please see Appendix A, which contains the survey appendix with the definitions that were
provided to survey respondents. Also see Appendix B, which provides a more detailed
breakdown of the exempt/excluded wastewaters.
EPA collected data on the operating status of the impoundments in the study. Most
impoundments were built more than 20 years ago (see Figure 2-1). Nearly 40 percent of the
impoundments operating in the 1990s were constructed in the 1970s and were presumably built
in response to environmental programs seeking improved wastewater treatment. The
impoundments that were in operation before 1970, approximately one-quarter of the population,
were likely employed in some aspect of water supply management associated with the industrial
processes at these facilities.
Eventually, impoundments stopped being used for waste management and were closed,
with varying degrees of waste removal. As shown in Table 2-15, EPA estimates that, during the
1990s, 16 percent of the industrial impoundments permanently stopped receiving waste. This
closure rate is in sharp contrast to the previous decade when a significant percentage of
During an RFA, an overseeing agency typically compiles existing information on environmental
conditions at a given facility and, as necessary, gathers additional facility-specific information on solid waste
management units and other areas of concern, releases, potential releases, release pathways, and receptors.
Information gathered during an RFA usually forms the basis for initiating full-scale site characterization.
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March 26, 2001
Chapter 2
Table 2-15. Regulatory, Exempt/Excluded, and Operating Status of Impoundments
Percent of impoundments
(out of 11,863)
Percent of facilities with at least
one unit in category
(out of 4,457)
Percent of total wastewater
quantity managed at
impoundments
(out of 653,796,340 metric tons)a
(1)
SWMU
RCRA
Assessment
33
25
14
(2)
Manage
Excluded/
Exempt
Wastewater
15
14
15
(3)
Ceased
Receiving
Waste since
June 1, 1990
16
22
4
(4)
Are under
State/Local
Regulations
86
81
97
(5)
Meet All
(1-4)
0.9
0
0 5
(6)
Meet
None
(1-4)
5
7
2
The estimate of the wastewater quantity for the total population differs from the estimates shown in Tables 2-1
and 2-2. This is due to missing data associated with this variable. Refer to Appendix A on missing data and
Appendix B for the standard error associated with this variable.
Table 2-16. Breakdown of Exempt/Excluded Wastewaters
Exemption/Exclusion Category
Estimated Volume
(and Percentage)
of Wastewater
Other (not on specific list of exclusions/exemptions)
Mixtures of solid waste and characteristic hazardous waste listed solely
because it exhibits a characteristic
Point source discharges
Bevill wastes
Coal and fossil fuel combustion wastes
Mixtures of solid waste and hazardous waste discharging to CWA system
Lab wastes mixed with solid waste
De minimis quantities of commercial chemical products mixed with
solid waste
Heat exchanger bundle cleaning sludge from petroleum refining
industry and solvent waste mixtures
Domestic sewage and mixtures of domestic sewage
Reclaimed pulping liquor
Wastes excluded from definition of solid waste
Total Volume of Exempt/Excluded Wastewaters
40,444,366
16,731,865
13,366,523
12,537,291
7,836,906
(41%)
(17%)
(14%)
(13%)
(8%)
1,852,033
1,175,821
105,767
1,606,185
2,016,833
1,000,407
98,768,548
(2%)
(1%)
(0.1%)
(2%)
(2%)
(1%)
(100%)
2-32
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March 26, 2001 Chapter 2
hazardous waste impoundments were closed and replaced with tanks. One-quarter of the
impoundments that ceased receiving wastes are from the wholesale trade-nondurable goods
industry sector. Roughly 35 percent of these impoundments were between 15 and 20 years old
and 20 percent were between 35 and 55 years old. These impoundments were predominantly
smaller units and account for under 5 percent of the total wastewater quantity.
The data examined above provide a picture of the regulatory and operating status of the
population of facilities addressed in this study. As Table 2-15 shows, only 7 percent of the
population of facilities fall under none of the regulatory/operating status categories.
Furthermore, based on analyses not shown in the table, almost half of the impoundments in the
overall population either ceased receiving waste during the 1990s or are at a RCRA TSD facility
and are therefore subject to facility-wide corrective action remedial requirements to address
potential releases. In addition, approximately 80 percent of all impoundments are under some
level of regulatory oversight, either by virtue of a state or local permit or as an SWMU at a
RCRA TSD. These facts, to some degree, mitigate the concerns stated in Section 2.4 concerning
the potential for human exposure to chemicals from impoundments. Chapter 4 of this report,
which investigates the potential gaps that exist in the regulation of surface impoundments, covers
these issues in much greater detail.
2.6 Conclusions
Surface impoundments continue to be a prominent feature in the industrial landscape. The
overall picture of the U.S. industrial surface impoundment population shows approximately
18,000 impoundments operating in the 1990s; an estimated 11,900 contain at least one or more
of the chemical constituents of concern for this study or have high or low pH. The geographic
distribution of these impoundments reflects areas with generally higher precipitation levels; that
is, they tend to be located in the areas east of the Mississippi River, mainly in Gulf Coast states
and along the East Coast. Fewer appear to be located in the more arid states west of the
Mississippi. Approximately 90 percent of impoundments are direct dischargers and 10 percent
are zero dischargers.
These impoundments serve a variety of beneficial uses. Many facilities employ
impoundments to perform necessary wastewater treatment prior to discharge into surface waters.
In other cases, industrial facilities may need to control wastewater flows and use impoundments
for storing excess wastewater. In still other cases, facilities use impoundments to manage excess
wastewaters through evaporation or seepage into the subsurface.
Industrial impoundments vary greatly in size and physical characteristics. Just under 50
percent of impoundments are 1/4 hectare or smaller in size, and, almost 10 percent of the
population of impoundments are over 5 hectares in size. These larger impoundments form the
bulk of the total national industrial impoundment capacity. Approximately 75 percent of the total
wastewater quantity managed exists at only 10 percent of the impoundments. Additionally,
about one-third of the facilities that fall into the study population have only one nonhazardous
impoundment onsite. Just under 5 percent of facilities have over 10 impoundments for
nonhazardous industrial waste management.
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March 26, 2001 Chapter 2
The paper and allied products sector accounts for two-thirds of the entire volume of
wastewater managed in these impoundments, although representing only 6 percent of the
facilities in the population. Over 50 percent of the facilities in the population fall into four
industrial sectors: chemical and allied products; stone, clay, glass, and concrete products;
wholesale trade-nondurable goods; and primary metals industry. Almost one in four
impoundments is located at a chemical and allied products facility.
Although only 15 percent of all facilities manage any decharacterized wastes, the
impoundments with decharacterized wastes account for 70 percent of the total industrial
wastewater quantity. Approximately 85 percent of impoundments have metals present in the
wastewater, and roughly half have volatile organic chemicals present. Approximately half of all
facilities use impoundments to manage between one and five chemicals of concern.
Most impoundments were built more than 20 years ago. Nearly 40 percent of the
impoundments operating in the 1990s were constructed in the 1970s; presumably in response to
environmental programs seeking improved wastewater treatment. Approximately 25 percent of
impoundments were in operation before 1970, suggesting that water supply was a critical
component of their process.
Impoundments, consistent with their intended purpose, are frequently found in vulnerable
environmental settings or use management techniques that increase the potential for chemical
releases to the environment. For example, although aeration can have certain benefits, it also
increases the potential for airborne contaminant migration. Furthermore, most impoundments
are located above shallow groundwater that is located within a few meters of the impoundment
bottom, and more than half of the impoundments do not have a liner system to retain the wastes
inside the impoundment. Four-fifths of industrial impoundments are located above groundwater
that discharges to a fishable waterbody, and approximately one out of five impoundments is
within 150 meters of a fishable waterbody. Approximately 20 percent of impoundments with
fishable waterbodies within 150 meters had overtopping events.
Regarding the potential for human exposure to constituents of concern, EPA estimates
that roughly 20 million people live within 2 kilometers of an industrial impoundment that
operated during the 1990s. Approximately one-tenth of the facilities have drinking water wells
within 150 meters of at least one of their impoundments. Further, approximately 75 percent of
all wastewaters contain volatile organic chemical constituents, which to varying degrees will
escape from the impoundments as air emissions (depending on physical properties of the specific
constituent and on meteorological conditions). Roughly one-third of impoundments have
residences within 150 meters of the impoundment.
Eventually, impoundments cease receiving waste and are closed with varying degrees of
waste removal. During the 1990s, EPA estimates that about 15 percent of the industrial
impoundments permanently stopped receiving waste. This is in sharp contrast to the previous
decade when the majority of hazardous waste impoundments were converted to tanks.
Furthermore, EPA estimates that more than three-quarters of industrial impoundments are
located at a RCRA permitted interim status facility and, as a result, are within RCRA jurisdiction
2-34
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March 26, 2001 Chapter 2
for corrective action as solid waste management units or operate under a state or local permit
such as a wastewater discharge permit.
The figures presented above on the chemicals managed in impoundments, the potential
for transport of chemicals in environmental media, and the proximity of residences to
impoundments provide an overall picture of the surface impoundment universe. Impoundments
are used to manage a host of chemicals of concern. The conditions that exist at these units allow
for the possibility of chemical transport from wastewaters. These conditions include the
presence of VOCs in aerated impoundments and the absence of liners at units that are located
above relatively shallow groundwater. In many cases, there are residences near these units,
allowing for the potential of residents' exposure to chemicals. Given these facts, EPA performed
an assessment of the risks posed by the population of impoundments. The results of this risk
assessment are presented in Chapter 3.
2.7 Reference
Metcalf and Eddy, Inc. 1991. Wastewater Engineering Treatment, Disposal, and Reuse. Third
Edition. Revised by G. Tchobanoglous and F. L. Burton. McGraw-Hill, Inc.
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March 26, 2001 Chapter 3
Chapter 3
Human and Ecological Risk Analysis
3.0 Summary of Chapter
The purpose of this chapter is to describe the methodology and provide the results for the
screening and assessment of potential risks to human and ecological receptors that may be
attributable to surface impoundments managing industrial wastewaters. The methodology and
results are summarized for each major pathway assessed, as outlined below. Additional detail on
this analysis is provided in Appendix C.
3.1 Introduction and Overview
3.2 Direct Pathways: Inhalation and Groundwater Ingestion
3.3 Indirect Pathways: Groundwater to Surface Water
3.4 Other Indirect Pathways
3.5 Ecological Risk Screening
3.6 Conclusions
3.1 Introduction and Overview
EPA has conducted the risk analysis for surface impoundments in several stages, with the
basic objectives of screening all the reported surface impoundments and chemicals, ranking those
that warrant additional analysis, and developing risk estimates for chemicals and surface
impoundments that may be of higher concern due to concentrations and environmental settings.
Throughout this process, the findings reported in the November 1999 survey have been used to
identify factors that may contribute to environmental releases or potential chronic risks posed by
surface impoundments.
3.1.1 Overview of Methodology
3.1.1.1 Tiered Approach to Risk Assessment Methodology. This analysis has been
conducted according to the technical plan submitted for peer review in February 2000, with
several additional refinements to the risk screening, ranking, and modeling steps. In general, EPA
used a sequential approach to rank facilities to progress through each step of the analysis:
1. Preliminary Screen: Conduct direct exposure pathway screenings of all the
survey facilities using health-based and ecological screening factors based on
precautionary exposure assumptions.
2. Release Assessment: Conduct screening-level modeling for direct pathways
using health-based screening factors.
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March 26, 2001 Chapter 3
3. Risk Modeling: Conduct site-based modeling to further refine the initial risk
estimates according to the environmental setting described in the survey data.
In essence, the methodology was designed to progress from a very precautionary
exposure/risk analysis for all facilities to a more realistic, site-based assessment that takes full
advantage of survey and site-specific information on facilities in the final stages of analysis. For
each major exposure pathway, EPA used the most appropriate approaches available to screen and
rank facilities, impoundments, and constituents for further analysis.
EPA used several different measures of chronic risk and hazard in the risk assessment.
Cancer risks were expressed as individual lifetime excess probability of cancer; a threshold of 1
in 100,000 was used as the criteria for determining whether a constituent posed a risk of concern.
The hazard associated with exposure to noncancer constituents was measured using a hazard
quotient (HQ). The HQ is the ratio of the estimated exposure concentration to an EPA reference
dose (RfD) for ingestion or reference concentration (RfC) for inhalation. RfDs and RfCs are
threshold measures of hazard that are set at a level that EPA has estimated will not result in
adverse effects in humans. The human health threats associated with surface water
contamination were evaluated using ratios of estimated surface water concentrations to ambient
water quality criteria for human health (HH-AWQC).
The final risk results for the statistically representative sample were extrapolated to
generate national estimates of the number and proportion of facilities and impoundments with
potential risks. Throughout this chapter facility proportions are expressed as a percentage of the
estimated 4,500 facilities, and surface impoundment proportions are expressed as a percentage of
the estimated 11,900 in-scope surface impoundments.
3.1.1.2 Relevant Exposure Pathways. EPA structured its risk analysis methodology to
identify potential risks posed to people by direct pathways and indirect pathways and to
ecological receptors. A pathway is the route a chemical takes from the impoundment to the
person or to ecological receptors after release of a chemical from a surface impoundment.
As suggested in Figure 3-1, chemicals may be released from an impoundment by
volatilizing from the wastewater into the air, by leaching through the bottom of the impoundment
into groundwater, or by erosion/runoff of contaminated sludge particles from an impoundment
that has closed.1 Once released into the environment, chemicals may pose direct exposures,
migrate through the groundwater to reach the surface water, or be deposited onto the soil in areas
that are close to the facility. Plants and animals that are exposed to these media may accumulate
chemicals in their tissues, and human and ecological exposures may occur through the food
chain.
People may be exposed to chemicals by many pathways. In direct pathways, the person
is exposed to the medium, such as air or groundwater, to which the chemical was released. In
1 Chemicals may also be released through direct discharge to surface water (currently regulated under the
Clean Water Act) or through overtopping events. However, these releases were not evaluated in this analysis.
O O
3-2
-------
Source
Release
Exposure Medium
Exposure
Pathway
Exposure Route
KJ
Inhalation
Ingestion
I | Shaded boxes refer to components of the preliminary screening of direct exposure pathways.
I I Unshaded boxes refer to components of the release assessment and risk modeling stages.
Dashed lines indicate other indirect exposure pathways that were not modeled quantitatively.
3 Medium concentration was com pa red directly to ecological risk screening factors.
bThis indirect pathway was modeled and the results used in the indirect pathway analysis.
Figure 3-1. Exposure pathways for active surface impoundments considered for human and ecological receptors.
n
5-
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March 26, 2001 Chapter 3
indirect pathways, the person is exposed to a different medium than the one to which the
chemical was released. For example, chemicals may be released into the groundwater aquifer
and transported to an adjacent surface waterbody by subsurface transport. If the chemical is
bioaccumulative, people who eat fish from that waterbody may be exposed to contaminants in
their diet.
This study develops quantitative risk estimates for the direct pathways of air inhalation
and groundwater ingestion and the indirect pathway of groundwater to surface water. In addition,
a screening was conducted of other indirect pathways, such as air deposition or erosion and
transport of chemicals across soil, to provide insight into the potential for food chain risks
attributable to these types of exposures. The direct discharge of chemicals to surface waters is
not considered because this pathway is already regulated by EPA. This study also includes a
screening-level assessment of potential ecological risks.
The following sections summarize the methodology and present the risk results for each
of the pathways in the human health risk analysis and for the ecological risk screening.
For each area of analysis, the screening and ranking stages were based on clear science decision
rules related to threshold concentrations of potential concern and the likelihood of exposures.
The modeling stages used peer-reviewed modeling tools available for use by the Agency.
Appendix C provides a detailed discussion of the methodologies used, including a listing of
health-based screening factors, ecological screening factors, and relevant data sources. In
addition, Appendix C presents the full analytical results of the assessment.
3.7.2 Overview of Results
Tables 3-1 and 3-2 present the overall results for each of the pathways in the human
health risk analysis and for the screening analyses of indirect pathways and potential ecological
risks. Sections 3.2 through 3.5 provide more detailed results and discussion for each analysis and
pathway. The complete results of the risk analysis are provided in Appendix C. The results for
each analytic question are given as the number or percent of facilities or impoundments having
the attribute in question. These numbers and percents are weighted national estimates derived
from the risk results for the sample population.
The results for the risk analysis are presented in two distinct sets depending on the nature
of the information provided in the surveys on chemical concentrations. Chemical concentration
data were central to EPA's risk screening and risk analysis of surface impoundments. EPA
provided considerable flexibility to survey respondents in submitting concentration data for use
in this study. This affects the certainty of the results. Some respondents provided analytical
reports; some used professional judgment to identify chemicals likely to be present; some
estimated concentrations based on averaged sampling events or other methods; some reported
chemicals to be present but did not report a concentration value; and some indicated that
concentrations were below detection limits. Survey respondents used many different reporting
conventions for detection limits. Sometimes chemicals were reported with very high detection
limits, possibly because of analytical interferences. In other cases constituents were reported
with very low detection limits. In still other cases facilities that did not expect certain chemicals
to be present would report higher detection limits, possibly not wanting to exert the additional
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March 26, 2001
Chapter 3
Table 3-1. Overview of Modeling-Level Results
Pathway
Groundwater
Air
Groundwater
to surface
water
Route
Ingestion
Inhalation
Ingestion
Facilities
That Have
Environmental
Releases3' c
RV
641
(14%)
173
(4%)
790
(18%)
S/DL
846
(19%)
165
(4%)
1,079
(24%)
Facilities
That May
Exceed Risk
Criterion" c
RV
27
(0.6%)
171
(4%)
44
(1%)
S/DL
23
(0.5%)
55
(1%)
31
(0.7%)
Numbers of Chemicals and
Impoundments That May Exceed
Risk Criterion
Chemicals
15 chemicals:
1 inorganic
2 metals
3 SVOCs
9VOCs
11 chemicals:
1 dioxin-like
5 SVOCs
5 VOCs
35 chemicals:
1 dioxin-like
3 metals
24 SVOCs
7 VOCs
Impoundments
126 impoundments:
114 dechar waste
12 never char waste
236 impoundments:
85 dechar waste
151 never char
waste
142 impoundments:
100 dechar waste
42 never char waste
RV = Reported values.
S/DL = Surrogate values/detection limits.
a An impoundment was determined to have an environmental release when there was evidence that contaminants
had the potential to migrate from the impoundment into the media of concern at concentrations above health-
based levels. The specific definitions vary by media.
b A facility was determined to exceed a risk criterion if individual constituents had concentrations in excess of
10"5 for cancer, an HQ greater than 1 for noncancer effects, or concentrations in excess of the ambient water
quality criteria in the case of surface water. EPA also summed risk across constituents where appropriate to
identify any cases where, even though a particular constituent might not exceed a risk criterion, all of the
constituents together might exceed a risk level.
0 Number of facilities (percentages are of the total number of facilities, approximately 4,500).
analytical effort that would be needed to establish a much lower detection limit. EPA observed
several cases where facilities reported a rather high limit of detection when, in fact, the chemicals
are very unlikely in a particular industrial sector and are probably not present at levels anywhere
near the detection limit. When chemicals were reported to be present but the quantity was
unknown or when chemicals were reported as being below a detection limit but the respondent
did not provide the detection limit, EPA inferred a value for use in the risk analysis as described
in Appendix B. When a value was reported to be less than a detection limit and that detection
limit was provided, EPA used the reported detection limit in the analysis.
EPA is most confident in those data where repondents reported a value above a limit of
detection and far less confident in other values, such as values less than detection limits. EPA
took great care to present the results separately based on concentrations actually reported in the
surveys because: (1) these values are based on survey respondents' knowledge or estimates of
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March 26, 2001
Chapter 3
Table 3-2. Overview of Screening-Level Results
Pathway
Indirect
Ecological
Route
Ingestion
Ingestion
Facilities
That Are
of Lower
Concern"
2,620
(59%)
2,359
(53%)
Facilities
That Are
of Potential
Concern"
285
(6%)
1,310
(29%)
Number of Chemicals and
Impoundments That Have a Potential
Concern
Chemicals
37 chemicals:
8 dioxin-like
1 mercury
2 metals
26 SVOCs
34 chemicals:
1 dioxin-like
1 mercury
14 metals
7 SVOCs
HVOCs
Impoundments
NAb
2,355 impoundments:
675 dechar waste
1,680 never char waste
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
b Not applicable; the indirect pathway analysis evaluates potential exposures for the entire facility.
chemical concentrations and (2) EPA considers these data to have a reasonable degree of
certainty. The results based on concentrations that EPA inferred or on detection limits are
presented separately, because the Agency believes that these span a greater range of potential
uncertainty. These results, nonetheless, may provide an indication of the range of possible
environmental releases or exposures for the significant number of surface impoundments for
which we lack concentration data.2 Where concentrations are reported below detection limits,
the use of detection limits for risk screening served two purposes: to screen out cases of no
concern, and to identify cases where, even at detection limits, there could be exposures of
concern depending on environmental settings and management conditions. Some survey
respondents who provided a response in the context of detection limits may have intended their
responses to represent negligible concentrations or may have intended to convey that the
chemical is not present. In these cases, the corresponding risks may be negligible and the risk
estimates based on detection limits would clearly be overestimates of potential risk. In summary,
the results based on surrogate data and detection limits span a range from negligible risk and no
environmental releases of concern to potential risk exceedances and environmental releases.
These are all accompanied by a greater level of uncertainty than results based on reported
concentrations.
EPA's field sampling provides additional insights concerning the concentration data reported in the
surveys. While generally confirming the range of reported concentration values, the field sampling identified many
cases where chemicals were not reported and other cases where chemicals were reported that EPA did not detect in
its sampling. This suggests that some facility operators do not have full knowledge of the chemicals contained in
their impoundments. The EPA field sampling results are discussed further in Chapter 2 and in Appendices C and E.
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March 26, 2001 Chapter 3
The results presented for the risk analysis are the national number and percent of all
facilities or impoundments that occur in the following categories:
• Negligible concern: These are facilities or impoundments for which no pathway
exceedances are predicted and/or environmental characteristics prevent the
completion of any exposure pathway. Based on the data made available, EPA
believes that these facilities or impoundments do not present any concern.
• Environmental releases: These are facilities or impoundments at which
environmental releases may be occurring because of the concentrations present in
the impoundments, and also because of operating conditions such as the presence
or absence of liners, the use of aeration, or other factors. However, taking into
account actual residential exposures, risks are not anticipated.
• Potential risk exceedances: These are facilities and impoundments that
potentially pose risks, taking into account actual residential exposures. These tend
to be high-end estimates because they are developed for the closest residential
exposures.
EPA identified potential environmental releases and risk exceedances, and separately
presented results based on reported concentration values, for three pathways: direct inhalation,
direct groundwater ingestion, and groundwater discharges to surface water with potential
exceedances of HH-AWQC. Tables 3-3 and 3-4 portray the overall results of the risk analysis
for these three pathways. Table 3-3 distinguishes results between never characteristic and
decharacterized wastes, and Table 3-4 distinguishes results according to the facilities' discharge
status under the Clean Water Act. These questions were examined because of the statutory
intent, expressed in the 1996 Land Disposal Program Flexibility Act, that decharacterized
wastewaters managed in surface impoundments under the scope of the Clean Water Act be
assessed in this study. Notable findings are that most facilities do not seem to pose risks or
exposures of concern. Twenty-one percent of facilities may have significant environmental
releases for at least one of the pathways examined, although not exceeding risk criteria. Five
percent of facilities (corresponding to 2 percent of impoundments) may pose potential risk
exceedances. Up to 23 percent of facilities may have releases or exposures for at least one of the
pathways examined based on surrogate data or detection limits, although the extent to which this
may actually be occurring is uncertain due to the lack of concentration data.
The results of EPA's screening level assessments for other indirect pathways and for
potential ecological concerns are described in Sections 3.4 and 3.5.
3.2 Direct Pathways (Inhalation and Groundwater Ingestion)
3.2.7 Methodology
Table 3-5 provides an overview of the tiered methodology used to assess potential risks
from direct ingestion of groundwater, and Table 3-6 provides an overview of the methodology to
assess direct inhalation risks. Appendix C provides complete details on the methodologies used.
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March 26, 2001
Chapter 3
Table 3-3. Facility-Level Overview of Human Health Results by
Decharacterization Statusa
Facility Status
Environmental
Release15
May Exceed
Risk Criteria15
Risk results based on reported waste concentrations
Never characteristic
Decharacterized
All facilities with reported values
598 (13%)
330 (7%)
928 (21%)
196 (4%)
41 (0.9%)
237 (5%)
Risk results based on surrogate/DL waste concentrations
Never characteristic
Decharacterized
All facilities with surrogate/DL values
812(18%)
169 (4%)
981 (22%)
0 (0%)
66(1%)
66 (1%)
DL = Detection limit.
a Results are for groundwater, air, and groundwater to surface water pathways.
b Number of facilities (percentages are of the total number of facilities, approximately 4,500).
Table 3-4. Facility-Level Overview of Human Health Results by Discharge Statusa
Facility Status
Environmental
Release15
May Exceed
Risk Criteria15
Risk results based on reported concentrations
Direct dischargers
Zero dischargers
All facilities with reported values0
716 (16%)
150 (3%)
865 (19%)
191 (4%)
27 (0.6%)
218(5%)
Risk results based on surrogate/DL concentrations
Direct dischargers
Zero dischargers
All facilities with surrogate/DL values0
1,111(25%)
76 (2%)
1,187(27%)
66(1%)
0 (0%)
66 (1%)
DL = Detection limit.
a Results are for groundwater, air, and groundwater to surface water pathways.
b Number of facilities (percentages are of the total number of facilities, approximately 4,500).
0 Note that the facility total for Table 3-4 does not equal the facility total for Table 3-3. This is because the patterns
of missing data are different for each of the tables, and the weight adjustments for missing data lead to slightly
different estimates.
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March 26, 2001
Chapter 3
Table 3-5. Overview of Tiered Risk Assessment Methodology for
Direct Ingestion of Groundwater
Analysis
Stage
Risk Assessment Methodology - Groundwater/Direct Ingestion Human Health
Chronic Risk Measures: (1) Lifetime excess risk of cancer greater than 105 and
(2) Exposure in excess of a reference dose
Approach
Receptor Exposure
Key Variables
Preliminary
screen
Precautionary screen
Eliminate
impoundments with no
evidence of risk from
further evaluation
Direct consumption of
impoundment water
Impoundment
chemical
concentrations
Exposure factors
Release
assessment
Evaluate facilities,
impoundments, and
constituents not
eliminated in the
preliminary screen
Use Industrial D Tier I
groundwater model
lookup tables
Impoundments not
screened out have
release potential;
evaluate for risk
modeling
Drinking water well
located at 150 m from
unit boundary
Liner type
Impoundment
chemical
concentrations
Exposure factors
Risk
modeling
Review site-specific
data for all facilities
with release potential
Select facilities with
the greatest potential
for risk
Conduct site-specific
modeling using
EPACMTP
Conduct Monte Carlo
analysis of
exposure/risk to capture
within-site variability
Nearest actual
household with a
reported domestic well
in the direction a plume
would migrate
Actual exposure to
receptor could occur in
the future depending on
transport time
Surface impoundment
dimensions
Impoundment
chemical
concentrations
Presence and distance
to receptor well
Subsurface
characteristics
Infiltration/liner type
Groundwater flow
direction
Exposure factors
EPACMTP = EPA's Composite Model for Leachate Migration with Transformation Products.
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March 26, 2001
Chapter 3
Table 3-6. Overview of Tiered Risk Assessment Methodology for the
Direct Inhalation of Air
Analysis
Risk Assessment Methodology - Air / Direct Inhalation Human Health
Chronic Risk Measures: (1) Lifetime excess risk of cancer greater than 105 and
(2) Exposure in excess of a reference concentration
stage
Preliminary
screen
Release
assessment
Risk
modeling
Approach
• Precautionary screen
• Eliminate impoundments
with no evidence of risk
from further evaluation
• Required reporting of
emissions data — few
impoundments screened
out
• Promoted impoundments
lacking sufficient data to
screen to the next tier
• Evaluate facilities,
impoundments, and
constituents not
eliminated in the
preliminary screen
• Apply Industrial D air
model with a combination
of default assumptions
and site-specific data
• Review site-specific data
for all facilities with
release potential,
including aerial
photographs to identify
nearest residence
• Apply Industrial D air
model with a combination
of default assumptions
and site-specific data
Receptor Exposure
• Direct inhalation of
impoundment
emissions with zero
dispersion
• Direct inhalation by
hypothetical receptor
exposed at a fixed
distance of 25 m
along the centerline
of the plume
• Direct inhalation by
actual closest
resident, assumed to
be along the
centerline of the
plume
Key Variables
• Impoundment
chemical
concentrations
• Exposure factors
• Impoundment
chemical
concentrations
• Meteorological
conditions
• Impoundment
characteristics such
as surface area,
aeration status
• Impoundment
chemical
concentrations
• Meteorological
conditions
• Receptor distance
• Impoundment
characteristics such
as surface area,
aeration status
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March 26, 2001
Chapter 3
In the initial screening stage, EPA
compared the reported concentration data (in
impoundment water and emissions) collected
from the facility survey with threshold
concentrations that are protective of human
health (residential exposures). EPA made full
use of all survey data available to derive
concentrations in wastewater and leachate in
surface impoundments where values were not
reported by respondents. The textbox
summarizes the surrogate data protocol used
by EPA to infer concentrations when necessary
from other reported values. See Appendix B
for more discussion on the protocol for
inferring concentrations.
EPA Surrogate Data Protocol
EPA relied on the surveys to identify the presence or
absence of particular constituents and used the
reported concentration data when available. When
chemicals were reported present, but concentrations
or emission data were not reported, EPA used a
number of approaches to derive surrogate values for
screening purposes. These included using data from
other impoundments at the same facility, using data
from other facilities in the same industrial category,
or modeling and backcalculating to infer
concentrations. In a number of cases, EPA's own
sampling identified additional constituents not
reported. These data provide an important QA step.
Impoundments with concentrations below the screening factors were below risk criteria
for that particular chemical or pathway. Those units that screen out remain an important
component of the overall risk profile for the surface impoundment universe. This screening was
precautionary because it was based on direct ingestion of the surface impoundment influent and
direct inhalation of the emissions.
To remain under consideration at this stage for additional risk screening, a facility must
either have at least one constituent in one impoundment that exceeds a risk criterion or present
cumulative risks from several constituents and/or impoundments that exceed the risk criteria.
Appendix C, Section C.I, provides additional detail on the methodology used for assessing
cumulative risks.
In the first modeling stage, EPA used screening-level fate and transport models developed
for use under the Industrial D guidance in situations where the major routes of exposure were
direct ingestion of drinking water or direct inhalation. These models used some key site-specific
data such as unit size, presence or absence of liners, and whether the unit is aerated. Because
some chemicals and units were to be screened from further analysis, EPA used precautionary
modeling approaches, such as assessing risks for close-in receptors (150 m for groundwater and
25 m for inhalation).3 Most impoundments reporting volatile constituents did not report
emissions data, so the reported wastewater concentrations were used to model emission levels for
the air pathway.
Based on the results of the screening-level modeling, EPA identified those chemicals,
impoundments, and facilities for which risks could not be ruled out and that, therefore, required
The Industrial D air model (U.S. EPA, 1998) is based on CHEMDAT8 and ISCST3 models for emissions
and dispersion factors, respectively. This model uses emissions data from the survey or, if no data are available,
estimates emissions from concentration and other site-specific data from the survey. The Industrial D groundwater
model is based on the EPACMTP. In this analysis, the Tier I approach was used (U.S. EPA, 1999a, b), using
dilution attenuation factors that correspond to a receptor well distance of 150 m.
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March 26, 2001 Chapter 3
further analysis. The second modeling stage consisted of site-based modeling of exposures and
potential risks to human receptors using more site-based data such as actual receptor locations.
With respect to inhalation, the risk analysis was repeated using the Industrial D air model
(U.S. EPA, 1998) and site-specific data were used as before; however, the receptor was placed at
the actual distance to the nearest residence for each impoundment (taken from the survey and
checked for accuracy against census data and aerial photos). This was typically more than the
default distance of 25 m used in the previous step, and, as a result, predicted air risks were almost
always lower in this stage.
With respect to groundwater ingestion, EPA reviewed the risk distribution of
groundwater ingestion risks after the first two stages of analysis within the context of the site-
specific details for those facilities at the high end of that distribution. The conclusions from that
review were that EPA could only properly characterize the risk through a more site-specific
modeling process. EPA developed numeric ranking criteria based on the potential for receptor
well chemical concentrations to exceed risk-based levels of concern. These criteria included site-
specific characteristics relevant to completing the groundwater pathway, such as the presence of
a confining clay layer in the subsurface. EPA selected 10 facilities with the greatest potential for
exposures that could lead to risk and modeled these 10 facilities using more sophisticated tools.
Monte Carlo model simulations were executed using EPA's Composite Model for
Leachate Migration with Transformation Products (EPACMTP, U.S. EPA, 1997) for the top-
ranked facilities to predict the 90th and 50th percentile risk levels.4 The simulation varied
parameters from site-specific, regional, and national data sources, as appropriate. The
groundwater concentrations predicted by EPACMTP were then used to conduct a Monte Carlo
simulation of the exposure to contaminated drinking water to generate risk distributions. This
assessment focused on chronic cancer risk and noncancer hazard resulting from tap water
ingestion. Consequently, the exposure assessment combined modeled residential well
concentrations with tap water ingestion rates and exposure durations to predict average daily
dose estimates for noncarcinogens and lifetime-averaged daily dose estimates for carcinogens.
At each stage (i.e., screening or modeling), EPA used the same risk criteria to determine
when risks to an individual are considered significant:
• For carcinogens: excess lifetime cancer risk = 10"5
• For noncarcinogens: hazard index (HI) = 1.
These criteria were applied to potential risks posed by a specific constituent, unit, and pathway,
as well as to summations of risks for a constituent, an impoundment, or a facility.
Once final risk results were generated based on the sample facilities, these were
extrapolated using the appropriate facility weights to generate a national estimate of the
proportions of facilities and surface impoundments that may pose potential risks.
4 The full risk distribution was calculated in the groundwater pathway analysis. This chapter presents
results at the 90th and 50th percentiles; the full risk results are presented in Attachment C-l 1 of Appendix C.
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Chapter 3
Appendix C provides further discussion of the methodologies and data used for risk
analysis, including a listing of the human health and ecological benchmarks used to derive
screening factors, the derivation of provisional benchmarks in some cases, the methodologies for
deriving surrogate concentration data, and the methodology for representing cumulative risks for
constituents, surface impoundments, and facilities. Appendix C also discusses uncertainties
associated with the analysis.
3.2.2 Screening Results and Proportions of Facilities that May Pose Risks
Table 3-7 shows the number of facilities and chemicals in the survey sample that were
evaluated for potential air and groundwater risks at each stage of the analysis. This table
illustrates that, with each stage of the analysis, progressively fewer facilities and constituents
continued to the next analytic stage.
3.2.3 Results for Groundwater Ingestion
Based on the precautionary screening
stages described above, EPA ranked the
facilities that showed risk criteria
exceedances in the release assessment phase
according to their potential for groundwater
concentrations to occur at levels of concern.
For each facility that passed an initial
decision criterion for potential groundwater
flow in the direction of receptor wells, EPA
conducted an additional review using data in
technical materials submitted by the survey
respondents. This review focused on criteria
relevant to the completion of the groundwater
pathway (e.g., well depth), and was used to
determine whether to conduct detailed fate
and transport modeling. A narrative was
prepared for each facility summarizing all
pertinent information according to a series of
technical and risk-based criteria. Although
the quantitative risk estimates generated in
the release assessment were above levels of
concern, the review of technical data
indicated that, for some facilities, the potential for groundwater contamination at receptor wells
was insignificant relative to levels of concern. To ensure consistency during this technical
review process, EPA quantified these criteria and adopted a numeric framework to rank the
facilities for groundwater contamination potential (see Attachment C-8 of Appendix C). Based
on this numeric ranking and the supporting narratives, EPA selected the 10 highest ranked
facilities to model for the groundwater pathway. Table 3-8 presents the maximum hazard and
risk exceedances for the seven facilities that showed potential risk exceedances; the results based
on reported concentrations are distinguished from those based on surrogate data and/or detection
Example of a Site-Specific Narrative
The site is underlain by 260 feet of lacustrine clay.
The thickness of the formation, combined with the
characteristic low conductivity of clay, suggests that
leachate emanating from a surface impoundment
would likely not impact drinking water resources.
The facility did not indicate that drinking water wells
were present within 2 km of the site. This is
supported by the fact that the clay formation is not a
producing aquifer (i.e., insufficient yield to provide
water). Furthermore, the area surrounding the facility
is structured in city blocks, suggesting that the
populace is supplied with municipal water.
The release assessment indicates that there are seven
chemicals of concern at this site. Although the
screening suggests that maximum cancer and
noncancer risks could be 1.9E-01 and 4.28,
respectively, it is highly unlikely that the surrounding
populace is at risk from ingestion of groundwater.
EPA did not model this facility any further.
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Chapter 3
Table 3-7. Summary of Screening Process and Risk Analysis Results for
Direct Pathways: Groundwater Ingestion and Air Inhalation
Category
Reported in Survey
Entered screening assessment
(Facilities that reported chemicals to be present)
Entered release assessment
(Facilities that did not screen out)
Considered for risk modeling
(Facilities that did not screen out)
Modeled
Evaluated but not modeled
Number of
Sample
Facilities"
195
133
116
75
37
38
Number of
Chemicals
215
193
147
92b
65
66
Number of
Impoundment/
Chemical
Combinations
8,117
4,097
795
359
436
Final Analytic Results0
Results based on reported concentrations
Environmental release
May exceed risk criteria
36
8
53
6
202
16
Results based on surrogate/DL concentrations
Environmental release
May exceed risk criteria
24
7
68
20
519
59
DL = Detection limit.
a The number of actual facility responses analyzed in the study that were used to perform the national
extrapolations presented throughout this report. There are no nationally extrapolated estimates in this
table.
b Some chemicals were modeled for only one of the two direct pathways; in addition, some chemicals
were modeled for several impoundments at the same facility. Therefore, the number of chemicals in
subsequent stages does not add to 92.
0 These results were subdivided according to whether the concentration data used were reported values
or were based on surrogate data and detection limits.
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Chapter 3
Table 3-8. Summary of Chemicals and their Maximum of Hazard and
Risk Exceedances for Groundwater Pathway"
Summary of HQ Exceedances
90th Percentile (50th Percentile)3
Summary of Risk Exceedances
90th Percentile (50th Percentile)3
Risk exceedances based on reported concentrations
Acetone - 13 (0.02)
Fluoride-59 (12)
Risk exceedances based on surrogate/DL chemical concentrations
Allyl alcohol - 26 (0.06)
Chloroformb - 50 (0.09)
Pyridine-1.7 (0.003)
Methanol-1.7 (0.004)
Methylene chlorideb - 8.2 (0.01)
Thallium - 4.5 (0.03)
Toluene-1.8 (0.004)
Acrylonitrile - 2.5E-5 (1E-6)
Arsenic - 1.6E-5 (8E-9)
Benzidine - 1.6E-03 (3E-4)
Chloroformb - 1.5E-4 (2E-7)
Methylene chlorideb - 1.8E-4 (3E-7)
N-Nitrosodi-n-propylamine - 4.5E-5 (1E-5)
N-Nitrosodimethylamine - 3.3E-4 (7E-5)
Vinyl chloride - 1.1E-5 (2E-6)
DL = Detection limit.
a Risk estimates and HQ values at the 90th percentile are shown first, and those at the 50th percentile are shown
in parentheses.
b Agency had both cancer and noncancer endpoints for these constituents.
limits. Several of these facilities showed potential exceedances at more than one impoundment.
The complete impoundment level results are presented in Appendix Table C-3-20.
Table 3-9 portrays the groundwater ingestion risk analysis results for decharacterized and
never characteristic wastes and further distinguishes these according to whether the results derive
from reported concentrations or from surrogate data and detection limits. For each category of
interest, Table 3-9 portrays the proportion of the surface impoundment universe that may exceed
risk criteria because of the direct ingestion of groundwater and those that may have
environmental releases to groundwater that do not exceed risk criteria.
3.2.3.1 Quantitative Risk Estimation for the Groundwater Pathway. Notable findings in
Table 3-9 are that very few facilities seem to show risks due to groundwater ingestion, less than 1
percent of reported concentrations. The majority of potential risk exceedances may be associated
with decharacterized wastes, although the total numbers are too small to generalize with
confidence. Fourteen percent of facilities (based on reported concentration data) may have
environmental releases, that is, the potential to generate groundwater plumes that extend 150
meters or more beyond the impoundment boundary. These releases are evenly split between
decharacterized and never characteristic wastes. As described in Attachment C-12 to
Appendix C, the rates of potential risk exceedances and environmental releases are higher for
decharacterized wastes than for never characteristic wastes. About 20 percent of facilities cannot
be assessed with confidence because the results are based on surrogate concentration data and
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Chapter 3
Table 3-9. Facility-Level Results for Groundwater Pathway by Decharacterization Status
Facility Status
Environmental
Release3
May Exceed Risk
Criteria3
Risk results based on reported concentrations
Never characteristic
Decharacterized
All facilities with reported values
341 (8%)
300 (7%)
641 (14%)
9 (0.2%)
18 (0.4%)
27 (0.6%)
Risk results based on surrogate/DL concentrations
Never characteristic
Decharacterized
All facilities with surrogate/DL values
714 (16%)
132 (3%)
846 (19%)
0 (0%)
23 (0.5%)
23 (0.5%)
DL = Detection limit.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
detection limits. Some of these facilities
may have negligible concentrations and
others may have environmental releases or
risk exceedances.
Not surprisingly, the highest risks for
the groundwater pathway on an
impoundment basis correlate strongly with
the absence of a liner. The liner status
reported in the survey responses provided
the necessary data to make this
determination, and, as shown in Table 3-10,
the number of risk criteria exceedances
observed in unlined impoundments is twice
the number for those that are lined.
Similarly, the number of unlined
impoundments that indicate the potential for
environmental releases is almost three times
the number for lined impoundments. These
results strongly suggest that (1) the
modeling is sensitive to the presence and
type of liner, and (2) the contaminant release
into the environment tends to be much
higher for unlined impoundments.
Two chemical constituents with reported
concentrations exceeded the risk criteria for the
groundwater ingestion pathway: acetone and fluoride.
Acetone is a non-cancer-causing chemical that has
been associated with increased liver and kidney
weights and nephrotoxicity in rats via oral
administration. The RfD of 0.1 mg/kg-d for
ingestion was identified in IRIS and used in the risk
modeling. This benchmark represents a health
benchmark suitable for evaluating chronic exposures.
Fluoride is a noncarcinogen that, at elevated doses,
may cause objectionable dental fluorosis in children.
The RfD of 0.06 mg/kg-d used in the risk modeling
was based on fluorine, as soluble fluoride, currently
found in IRIS. EPA has determined that dental
fluorosis is a cosmetic effect, not a toxic or adverse
health effect. However, it is important to note that, at
somewhat higher levels of exposure, the endpoint of
concern is crippling skeletal fluorosis. Although an
RfD for skeletal fluorosis is not available, EPA has
determined that a safe exposure level for this more
severe endpoint in adults is twice the RfD for dental
fluorosis, or 0.12 mg/kd-d.
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Chapter 3
Table 3-10. Impoundment-Level Results for Groundwater Pathway by Liner Status
Impoundment Status
Environmental
Release3
May Exceed
Risk Criteria3
Risk results based on reported concentrations
Lined
Not lined
All impoundments with reported values
449 (4%)
850 (7%)
1,299(11%)
8 (0.07%)
36 (0.3%)
44 (0.4%)
Risk results based on surrogate/DL concentrations
Lined
Not lined
All impoundments with surrogate/DL values
461 (4%)
1,939 (16%)
2,400 (20%)
32 (0.3%)
47 (0.4%)
79 (0.7%)
DL = Detection limit.
a Number of impoundments (percentages are of the total number of in scope impoundments,
approximately 11,900).
3.2.3.2 Discussion of Uncertainties Associated with Groundwater Analysis. In its
assessment of the groundwater pathway, EPA relied on modeling tools that have been peer-
reviewed and used in previous analyses, as much site-specific data as possible from the surveys,
and standard EPA sources for important data such as exposure factors and health benchmarks.
All of these factors contributed to a relatively robust analysis that met the study objectives of the
Surface Impoundment Study. This section identifies the primary sources of uncertainty and
qualitatively describes how each may influence the results of the risk assessment. Additional
details on these uncertainties are presented in Appendix C of this report.
Parameter Uncertainties. The critical parameters required for the screening of
groundwater pathway included the distribution coefficients (Kd) and model parameter inputs.
• Distribution Coefficients. Empirical data were used to characterize partitioning
of chemical contaminants between the aqueous phase and soil and aquifer
materials. The Kd values used in the SI Study are based on values found in the
literature. Uncertainty associated with these values could result in either an
underestimation or an overestimation of risk.
• Model Input Parameters. Application of the EPACMTP model requires input
values for the source-specific, chemical-specific, unsaturated zone-specific, and
saturated zone-specific model parameters. For this analysis, facility-specific
values for impoundment location and waste, soil, and aquifer characteristics were
used to the extent possible. Where facility-specific data were not available,
regional databases were used to obtain the parameter values for soil and aquifer
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March 26, 2001 Chapter 3
conditions. The use of facility-specific data reduces but does not eliminate
uncertainty. Use of regional databases may result in a greater spread of risks in
Monte Carlo analyses.
Model Uncertainties. Model uncertainty is associated with all models used in all phases
of a risk assessment because models and their mathematical expressions are simplifications of
reality that are used to approximate real-world conditions, processes, and their relationships.
These simplifications generally rely on precautionary assumptions and, as a result, the modeling
approach tends to overpredict the potential effects on water quality.
• Model Simplifications. In modeling the fate and transport of chemicals in
groundwater, complex hydrogeology such as karst or highly fractured aquifers was
not directly assessed. A small fraction of the groundwater settings in this analysis
are located in hydrogeologic environments where fracturing is likely. EPACMTP
also does not model colloidal transport nor does it model possible geochemical
interactions among different contaminants in the leachate and the subsurface
environment. In addition, some precautionary assumptions are made that allow
for the saturated zone to be modeled as having a uniform thickness. The use of
these simplifications may result in a greater spread of concentrations in the
groundwater in the Monte Carlo analysis.
• Recharge Rates. The recharge rates used in this analysis rely on regionalized
climatic data and generalized soils types. These are not site-specific data, but are
intended to represent the range of conditions expected in the area. Although the
model accounts for uncertainty using a probabilistic simulation, the recharge rates
are not site-specific and may over- or underpredict the contaminant flux to
groundwater.
• Timeframe of Exposure. There is uncertainty in predicting the movement of
contaminants over long periods of time. The risk to receptors for the groundwater
pathway was evaluated over a time period of 10,000 years. There are significant
uncertainties concerning how exposure and environmental assumptions will
change over time, and the modeling methodology does not change these
assumptions over this 10,000-year period.
Uncertainty in Results. It is important to consider several key uncertainties in
interpreting the significance of the groundwater pathway results. The greatest uncertainty relates
to assumptions made in defining the geometric configuration of the modeled system, specifically
concerning the groundwater flow direction, well construction, and aquifer mounding.
• Groundwater Flow Direction. The direction of groundwater flow was not
provided in the survey responses. Because the exact direction of the groundwater
flow was unknown, the actual receptor well locations in the general the direction
of the groundwater flow, as well as the physiography of the site were used to
define the angle "THETA." For each surface impoundment, THETA sets the
bounds for the true direction of groundwater flow and, therefore, captures the
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Chapter 3
uncertainty in centerline for groundwater flow and contaminant movement
relative to the nearest receptor well to the impoundment. The error margin for
THETA was based on professional judgement, and was set to 5 degrees for all
facilities evaluated in the risk modeling. The impact of this geometrical
inexactitude is considered to be small compared to several other uncertainties in
the groundwater pathway analysis.
• Well Construction. The aquifer from which receptor wells drew water was not
consistently reported in survey results. In the absence of technical information
from the survey respondents indicating a site-specific well depth, it was assumed
that the receptor wells considered in this analysis drew water from the uppermost
unconfined saturated zone. This is a protective assumption and would tend to
overestimate risk.
3.2.4 Results for Direct Inhalation Pathway
Table 3-11 identifies the chemicals that
showed potential risk exceedances for the
direct inhalation pathway. The more reliable
findings based on reported values are
distinguished in the table from those based on
use of surrogate values and detection limits as
modeling inputs. Eleven chemicals show a
potential risk of 1E-5 or more or an HQ of 1 or
more. Two of these chemicals show potential
risks based on reported values.
Table 3-12 provides national estimates
of the number of facilities that may have risk
exceedances by the direct inhalation pathway,
distinguishing those results in which we have
more confidence because they are based on
reported concentration data from those less
reliable results based on inferred
concentrations or detection limits. Table 3-12
further distinguishes results for
decharacterized wastewaters and for never
characteristic wastewaters.
Two chemical constituents with reported
concentrations exceeded the risk criteria for the air
inhalation pathway: alpha-hexachlorocyclohexane
and chlorodibromomethane.
alpha-Hexachlorocyclohexane is considered a
probable human carcinogen (Class B2) and has been
shown to cause hepatic nodules and hepatocellular
carcinomas in male mice when administered orally.
The cancer slope factor for inhalation of
6.3 (mg/kg-d)"1 was identified in IRIS and used in the
risk modeling. The inhalation CSF found in IRIS is
based on the oral ingestion study on male mice.
Chlorodibromomethane is considered a possible
human carcinogen (Class C); oral administration to
female mice resulted in an increased incidence of
hepatocellular adenomas and carcinomas. The CSF
for inhalation of 8.4E-02 (mg/kg-d)"1 was
extrapolated from the CSF for ingestion identified in
IRIS and used in the risk modeling. This provisional
inhalation benchmark was derived from the oral
ingestion study described in IRIS; however, this
benchmark has not undergone EPA-wide review.
Table 3-13 shows the proportion of
impoundments by aeration status. Aeration greatly facilitates emissions to air. The majority (86
percent) of impoundments are not aerated, thus most of the exceedances are for nonaerated
impoundments.
3.2.4.1 Quantitative Risk Estimation for Air Pathway. Table 3-12 shows that 4 percent
of facilities potentially exceed risk criteria (based on reported wastewater concentrations.) Most
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Chapter 3
Table 3-11. Maximum Hazard and Risk Exceedances for Air Pathway
Summary of HQ Exceedance
Summary of Risk Exceedance
Risk exceedances based on reported concentrations
Chlorodibromomethane - 1E-05
alpha-Hexachlorocyclohexane - 3E-05
Risk exceedances based on surrogate/DL chemical concentrations
Acetonitrile - 57
Acroleinb - 11
Chloroform - 2
Hexachlorocyclopentadiene - 1.5
Bis (chloromethyl) ether - 4E-01
n-Nitrosodiethylamineb- 5 E-05
n-Nitrosodi-n-butylamineb - 2 E-05
Tetrachlorodibenzofurans - 3 E-05
Toxaphene - 4E-03
Risk exceedances based on summed risks for the facility
Facility level sum - 1.5E-05
Acetaldehyde3 - 6 E-06
Tetrachlorodibenzodioxins - 9E-06
DL = Detection limit.
a Constituent risk was based on a reported value. However, the individual risk did not exceed the risk
criterion.
b Industry representatives, subsequent to completion of the survey, have indicated that this constituent
is not expected to be present at the facility. These constituents were reported to EPA in response to
the Survey of Surface Impoundments in November 1999 as less than a specified limit of detection.
When this constituent was evaluated in our risk analysis at the reported detection limit the
concentrations were high enough to predict the indicated risk/hazard of concern. EPA included the
results in this table because of the methodology used throughout the study to evaluate less than
detection limit data.
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Chapter 3
Table 3-12. Facility-Level Results for Air Pathway by Decharacterization Status
Facility Status
Environmental
Release3
May Exceed
Risk Criteria"
Risk results based on reported concentrations
Never characteristic
Decharacterized
All facilities with reported values
105 (2%)
69 (2%)
173 (4%)
158 (4%)
13 (0.3%)
171 (4%)
Risk results based on surrogate/DL concentrations
Never characteristic
Decharacterized
All facilities with surrogate/DL values
31(0.7%)
134 (3%)
165 (4%)
0 (0%)
55 (1%)
55 (1%)
DL = Detection limit.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
Facility-Level Risk Summation
The risks presented in the exceedance tables in this section reflect risks for individual chemicals in
individual impoundments. However, an aggregate facility-level risk was also calculated and was
used to determine whether a facility exceeded the risk criterion or not.
• For carcinogens, the aggregate risk for a facility was calculated by taking the maximum risk for
each chemical across all impoundments at the facility and summing these.
• For noncarcinogens, the aggregate risk for a facility was calculated by taking the maximum
hazard index for each chemical across all impoundments at the facility, summing those that act
on the same target organ, and taking the maximum of the target organ-specific sums.
In only one case did a facility have an aggregate risk that exceeded the risk criterion and no
individual impoundment-chemical results that exceeded the risk criterion. This was via the air
pathway. This aggregate, however, is a combination of reported data and less reliable surrogate or
detection limit data. That exceedance is listed in Table 3-11 with all the individual impoundment
chemical components as well as the aggregate facility-level risk.
See Attachment C-6 in Appendix C for the full impoundment-level results that were used to generate
facility-level risk summations.
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Chapter 3
Table 3-13. Impoundment-Level Results for Air Pathway by Aeration Status
Impoundment Status
Environmental
Release3
May Exceed
Risk Criteria3
Risk results based on reported concentrations
Aerated
Not aerated
All impoundments with reported values
78 (0.7%)
297 (3%)
375 (3%)
8 (0.06%)
154(1%)
161 (1%)
Risk results based on surrogate/DL concentrations
Aerated
Not aerated
All impoundments with surrogate/DL values
195 (2%)
207 (2%)
402 (3%)
60 (0.5%)
26 (0.2%)
85 (0.7%)
DL = Detection limit.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
of these manage never characteristic wastes. The trend is reversed for facilities and
impoundments that show environmental releases, with a higher rate of these releases associated
with decharacterized wastes. From an impoundment standpoint, Table 3-13 shows that a
significantly higher number of impoundments that may exceed risk criteria are not aerated.
These data are somewhat misleading because the number of non-aerated impoundments (10,193)
far exceeds the number of aerated impoundments (1,670). The relative proportion of aerated
impoundments that are classified as "may exceed risk criteria" is much higher than the relative
proportion of not aerated impoundments classified as "may exceed risk criteria." Approximately
one-third of the total risk exceedances are attributable to aerated impoundments even though less
than one-fifth of the sample population consists of aerated impoundments. (See Attachment C-7
to Appendix C for additional detail.) Chemicals of interest included primarily volatile organic
compounds (VOCs), although several semivolatile organic compounds (SVOCs) and one dioxin-
like chemical showed potential risk exceedances; both cancer risks and noncancer risks were
predicted.
Table 3-12 also shows that 4 percent of facilities may have environmental releases, i.e.,
exposures of potential concern at a distance of 25 meters from the facility boundary. An
additional 5 percent of facilities cannot be assessed with certainty because of lack of information
on concentrations. Some of these facilities may have negligible concentrations, and others may
have environmental releases or risk exceedances.
3.2.4.2 Discussion of Uncertainties for Air Analysis. In its assessment of the air
pathway, EPA relied on modeling tools that have been peer-reviewed and used in previous
analyses, as much site-specific data as possible from the surveys, and standard EPA sources for
important data such as exposure factors and health benchmarks. All of these factors contribute to
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March 26, 2001 Chapter 3
an analysis that met the study objectives of precautionary screening at earlier stages for the many
impoundments and constituents and more robust modeling at the final stages of analysis.
However, there are several key uncertainties that should be considered in interpreting the results
of the air analysis. These are grouped under parameter uncertainties, modeling uncertainties, and
results uncertainties. This section identifies these sources of uncertainty and qualitatively
describes how each may influence the results. Additional details on these uncertainties are
presented in Appendix C.
Parameter Uncertainties. The key parameters required for the air pathway modeling
included impoundment characteristics, receptor location, and exposure parameters.
• Impoundment Characteristics. Impoundment characteristics needed for the
modeling were taken from the survey responses whenever possible; however,
when this was not possible, assumptions or estimates were made that introduce
uncertainty into the results. Assumptions and estimates were generally chosen to
be somewhat conservative (i.e., to overpredict risk).
• Receptor Location. To the extent that receptor locations were based on old or
inaccurate maps, there is some uncertainty introduced in the risk estimates, which
could be either over- or underestimated. However, conclusions regarding whether
or not the risk may exceed the risk criteria are more robust, because, in cases
where this conclusion was sensitive to receptor location, the location was verified
using recent aerial photos.
• Exposure Parameters. The air model used in this analysis, is called the IWAIR,
the Industrial Waste Air Model (IWAIR) (U.S. EPA, 1998) and was developed for
EPA's draft industrial nonhazardous waste guidelines and used standard EPA
exposure factors, such as inhalation rate, body weight, and exposure duration.
Exposure factors have been chosen to be somewhat conservative; therefore, this
uncertainty will typically result in an overestimate of risk.
• Volatilization. Our evaluation of the groundwater pathway was focused only on
the ingestion of contaminated groundwater. We did not address volatlization of
chemical constituents in groundwater that may result in inhalation exposures
during showering. Because the inhalation pathway associated with shower
exposure was not modeled, the groundwater pathway risk results may
underestimate the total risk from leaching to groundwater. This contributes to the
uncertainty in the risk estimates in the direction of underprotection.
Modeling Uncertainties. The modeling for the air pathway simplifies the fate and
transport of chemicals from an impoundment through air to a receptor. Many of these
simplifications could result in either over- or underprediction of risk.
• Hydrolysis. IWAIR cannot model hydrolysis. To the extent that constituents
modeled do hydrolyze, IWAIR will overpredict risks. For constituents that
hydrolyze quickly, this could be significant. For others, it will be less significant.
3-23
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March 26, 2001 Chapter 3
• Biodegradation Losses. IWAIR models biodegradation losses using conservative
biodegradation rate constants. However, biodegradation is heavily influenced by
site-specific factors. Therefore, the emissions estimates are uncertain. This
uncertainty could result in either over- or underprediction of emissions and risks.
• Receptor Location Relative to Plume. The receptor is assumed to be located at
the centerline of the plume, where air concentrations are highest. Depending on
site-specific meteorology, particularly prevailing wind directions, the nearest
receptor may not be located in the centerline of the plume. This uncertainty tends
to overpredict air concentration at the nearest receptor, and thus the risk.
• Coverage of Meteorological Data in IWAIR. The version of IWAIR used for
this study uses dispersion factors for 41 meteorological stations. Use of these
meteorological stations introduces uncertainty to the extent that they may not fully
represent all possible impoundment locations. However, this uncertainty is
believed to be small. The direction of this uncertainty is not known.
• Interpolation of Dispersion Factors in IWAIR Based on Impoundment Area.
IWAIR uses dispersion factors generated for a fixed set of impoundment areas and
interpolates results for other areas. This will result in the underprediction of risk;
however, this underprediction is expected to be modest.
Results Uncertainties. As with any risk assessment, there is uncertainty in the risk
results associated with simplifying assumptions and data limitations. Several key uncertainties to
consider in interpreting the risk results are presented below.
• Chemical-Physical Properties. Adequate chemical-physical properties to run
IWAIR were not available for 12 constituents of interest in this study for the air
pathway. To the extent that these constituents pose risks, this results in an
underestimate of risk.
• Health Benchmarks. It was not possible to assess inhalation risks for many
constituents in the scope of this study becasue they do not have health benchmarks
for inhalation. If inhalation health benchmarks were available for all constituents
of interest, a few more might be found to pose risks; therefore, this uncertainty
tends to result in an underestimate of risk.
3.3 Indirect Pathways: Groundwater to Surface Water
Many impoundments are located near surface waterbodies and their direct discharges are
subject to regulatory standards. However, there is the potential for indirect discharge to surface
waters when chemicals are released through the bottom of the impoundment, travel through the
subsurface, and impact nearby waterbodies. The intersection of groundwater flow with surface
water is often referred to as groundwater discharge to surface water. Through this pathway,
contaminant discharge into a pond or stream has the potential to affect water quality adversely.
3-24
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March 26, 2001 Chapter 3
For chemicals that are bioaccumulative, chemical concentrations in fish may approach or exceed
levels of concern for the segment of the population that ingests fish from the nearby waterbody.
For convenience, we will refer to the release, transport, and accumulation of chemicals in fish
and other aquatic organisms as the groundwater to surface water (gw-sw) pathway.
3.3.1 Methodology for Groundwater to Surface Water Pathway
Table 3-14 provides an overview of the methodology for assessing the groundwater to
surface water pathway. The basic approach to evaluating the potential for risks by this pathway
was first to identify candidate sites through a screening process that considered groundwater
concentrations, proximity to surface waterbodies, and the magnitude of potential dilution. For
these candidate sites, screening-level modeling was conducted to generate flux rates from the
surface impoundments, estimate groundwater concentrations that might contaminate the surface
waterbody, and estimate the ensuing dilution. This analysis was conducted on all facilities that
reported the presence of in-scope constituents. The basic steps in the screening process were to
• Identify sites near (within 1 km) one or more fishable waterbodies
• Screen out some sites based on a comparison of wastewater concentrations to the
human health ambient water quality criteria for the ingestion of surface water and
aquatic organisms (HH-AWQC)
• For those that did not screen out, estimate groundwater concentrations (from
dilution attenuation factors [DAFs]) and compare these to the HH-AWQC. The
DAFs used were intended to provide conservative estimates of groundwater
concentrations
• Using site-specific data (such as surface impoundment area) and reviewing
topographical maps, identify sites with a potential to impact surface water.
Typically, this was based on a low probability of dilution by the surface
waterbody based on flow data for the closest waterbody.
After the screening process, EPA conducted screening-level modeling to generate more
refined estimates of chemical concentrations in the receiving waterbody and compared the
resulting values to the HH-AWQC.5
5 In cases in which the receiving waterbody was brackish (e.g., in an estuary), the HH-AWQC for ingestion
of contaminated aquatic biota only was used (i.e., no drinking water ingestion).
3^25
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Table 3-14. Overview of Tiered Risk Assessment Methodology for Potential for Adverse Effects on Surface Water Quality
Analysis
Stage
Risk Assessment Methodology—Groundwater to Surface Water
Human Health
Chronic Risk Measure: Surface water concentrations in excess of AWQC for protection of human health for ingestion of aquatic
organisms and surface water
Approach
Receptor Exposure
Driving Variables
Preliminary
Screen
to
Precautionary screen
Determine potential for a groundwater
to surface water pathway as a function
of distance (surface waterbody within
1km)
Eliminate impoundments with
wastewater concentrations below HH-
AWQC from further evaluation
Ingestion of aquatic organisms and surface
water (as defined by the HH-AWQC)
Wastewater leachate concentrations
Release
Assessment
Evaluate facilities, impoundments,
and constituents not eliminated in the
preliminary screen
Use Industrial D Tier I groundwater
model lookup tables to estimate
groundwater concentrations
Eliminate impoundments with
leachate concentrations below HH-
AWQC from further evaluation
Impoundments not screened out have
release potential and are evaluated for
screening risk modeling
Ingestion of aquatic organisms and surface
water (as defined by the HH-AWQC)
Impoundment wastewater
concentrations
Liner type
Distance to surface waterbody
(groundwater concentration was not
diluted if waterbody was within 150
km of impoundment)
(continued)
-------
Analysis
Stage
Risk
modeling
(screening)
to
Table 3-14. (continued)
KJ
Risk Assessment Methodology—Groundwater to Surface Water
Human Health
Chronic Risk Measures: Surface water concentrations in excess of AWQC for protection of human health for ingestion of aquatic
organisms and surface water
Approach
Evaluate characteristics of
impoundments (e.g., surface area) and
receiving waterbodies (e.g., flow rate)
that drive this pathway
Develop numeric ranking scheme to
identify impoundments with potential
to adversely affect surface water
quality
Using EPACMTP, calculate
infiltration rate and contaminant flux
from impoundment to surface water
Determine surface water
concentrations using instantaneous
dilution and full mixing assumptions
Compare surface water concentrations
with HH-AWQC for the
impoundments modeled
Receptor Exposure
Ingestion of aquatic organisms and surface
water (as defined by the HH- AWQC)
EPACMTP = EPA's Composite Model forLeachate Transformation Products.
HH-AWQC = Human health ambient water quality criteria.
Driving Variables
Impoundment leachate concentrations
Surface area of surface impoundment
Meteorological conditions that affect
infiltration (e.g., precipitation)
Type of receiving waterbody (flowing
versus quiescent)
Flow rate
Liner type
Distance to surface waterbody
n
5-
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March 26, 2001 Chapter 3
3.3.2 Results for Indirect Pathway—Surface Water
After completion of this screening-level modeling, EPA found 158 potential risk
exceedances (35 constituents) at 27 impoundments at nine facilities in the survey sample. In
summary, EPA found
• 30 exceedances of the HH-AWQC by a factor of over 100—of these 30
exceedances, 7 are based on reported values for arsenic at a single facility.
• 38 exceedances of the HH-AWQC by a factor between 10 and 100—none are
based on reported values.
• 90 exceedances of the HH-AWQC by a factor between 1 and 10—of these 90
exceedances, only thallium and arsenic are based on reported values.
Table 3-15 identifies the maximum exceedances for reported values at each of the nine facilities
with respect to the ratio of the surface water concentration to the HH-AWQC. Where a reported
value was not identified, the maximum exceedance based on a surrogate/detection limit (DL)
value, in which there is less confidence, is presented.
Tables 3-16 and 3-17 illustrate the proportion of the surface impoundment universe that
show potential exceedances of HH-AWQC and those that show potential environmental release
to surface water. Table 3-16 shows the proportion of facilities by decharacterization status;
Table 3-17 shows the proportion of impoundments by liner status.
3.3.2.1 Quantitative Risk Estimation for Surface Water Pathway. Based on screening
level modeling, Table 3-16 shows that very few facilities—about 1 percent—may exceed risk
criteria using reported concentration data. Eighteen percent of facilities may have environmental
releases into surface water that are higher than HH-AWQC at the point of discharge before
dilution occurs. An additional 25 percent of facilities cannot be assessed with certainly because
of incomplete information on concentrations; some of these facilities may have negligible
concentrations, and others may have environmental releases or risk exceedances. The number of
potential risk exceedances is roughly similar for decharacterized and never characteristic wastes;
however, the rate of potential risk exceedance is higher for decharacterized wastes. (See
Attachment C-15 of Appendix C.) Table 3-18 shows the risk results by discharge status. For
the groundwater pathway, no zero discharge facilities exceeded the risk criteria; however, for the
surface water pathway, it can be inferred that roughly 37 percent6 of all facilities that exceeded
the risk criteria were zero dischargers. The value of liners for protecting the surface water
pathway was pronounced (see Table 3-17); no impoundments with liners show potential
exceedances of the human health ambient water quality criteria, whereas unlined impoundments
do show potential risk exceedances.
There are approximately 73 total facilities with 27 zero dischargers listed as "May Exceed Risk Criteria."
The complete analytical results for this pathway are shown in Attachment C-15 in Appendix C.
3^28
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March 26, 2001
Chapter 3
Table 3-15. Maximum Exceedances for Groundwater to Surface Water Pathway
Constituent of Concern
r a
Bleach
(mg/L)
C b
^gw
(mg/L)
C
^ river
(mg/L)
HH-AWQC
(mg/L)
'river'
HH-AWQC"
Risk exceedances based on reported chemical concentrations
Thallium
Arsenic
2.40E-01
1.95E-01
3.29E-03
1.95E-01
3.29E-03
1.95E-01
1.70E-03
1.80E-05
1.93E+00
1.08E+04
Risk exceedances based on surrogate/dl chemical concentrations
Antimony
3,3 Dichlorobenzidine
4,4-DDD
4,4-DDE
4,4-DDT
Heptachlor epoxide
Hexachlorobenzene
PCBs
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Chrysene
Dibenzo(a,h)anthracene
Ideno 1,2,3-cdpyrene
1 , 1 ,2,2-Tetrachloroethane
1 , 1 -Dichloroethylene
1 ,2-Dichloroethane
1 ,2-Diphenylhydrazine
2,4-Dinitrotoluene
Acrylonitrile
Aldrin
Benzidine
Bis(2-chloroethyl) ether
Carbon tetrachloride
Chlordane
6.00E-02
2.00E-02
3.67E-04
3.67E-04
3.67E-04
2.93E-03
l.OOE-02
1.65E-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
5.00E-03
5.00E-03
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-05
l.OOE-02
l.OOE-02
5.00E-03
5.00E-05
6.00E-02
2.00E-02
3.67E-04
3.67E-04
3.67E-04
2.93E-03
l.OOE-02
1.65E-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
5.00E-03
5.00E-03
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-05
l.OOE-02
l.OOE-02
5.00E-03
5.00E-05
3.74E-04
9.02E-05
1.65E-06
1.65E-06
1.65E-06
1.32E-05
4.51E-05
7.45E-05
1.44E-04
1.44E-04
1.44E-04
1.44E-04
1.44E-04
1.44E-04
4.87E-04
4.87E-04
4.87E-04
9.73E-04
9.73E-04
9.73E-04
4.87E-06
9.73E-04
9.73E-04
4.87E-04
4.87E-06
1.40E-04
4.00E-05
8.30E-07
5.90E-07
5.90E-07
l.OOE-07
7.50E-07
1.70E-07
4.40E-06
4.40E-06
4.40E-06
4.40E-06
4.40E-06
4.40E-06
1.70E-04
5.70E-05
3.80E-04
4.00E-05
1.10E-04
5.90E-05
1.30E-07
1.20E-07
3.10E-05
2.50E-04
2.10E-06
2.67E+00
2.26E+00
1.99E+00
2.80E+00
2.80E+00
1.32E+02
6.02E+01
4.38E+02
3.28E+01
3.28E+01
3.28E+01
3.28E+01
3.28E+01
3.28E+01
2.86E+00
8.54E+00
1.28E+00
2.43E+01
8.85E+00
1.65E+01
3.74E+01
8.11E+03
3.14E+01
1.95E+00
2.32E+00
(continued)
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March 26, 2001
Chapter 3
Table 3-15. (continued)
Constituent of Concern
Chlorodibromomethane
Dieldrin
Heptachlor
Hexachlorobutadiene
N-Nitrosodimethylamine
N-Nitrosodi-n-propylamine
Pentachlorophenol
Toxaphene
r a
Bleach
(mg/L)
5.00E-03
2.00E-04
5.00E-05
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
C b
^gw
(mg/L)
5.00E-03
2.00E-04
5.00E-05
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
C
^ river
(mg/L)
4.87E-04
1.95E-05
4.87E-06
9.73E-04
9.73E-04
9.73E-04
9.73E-04
4.87E-04
HH-AWQC
(mg/L)
4.10E-04
1.40E-07
2.10E-07
4.40E-04
6.90E-07
5.00E-06
2.80E-04
7.30E-07
'river'
HH-AWQC"
1.19E+00
1.39E+02
2.32E+01
2.21E+00
1.41E+03
1.95E+02
3.48E+00
6.67E+02
HH-AWQC = Ambient Water Quality Criteria for human health.
a The estimated concentration in the leachate as it leaves the unit boundary.
b The estimated concentration in the groundwater as it enters the surface water; if this value exceeds a
HH-AWQC then the facility is considered to have the potential for an environmental release.
0 The estimated concentration in the surface water after complete mixing.
d The ratio of the surface water concentration to the HH-AWQC; if this ratio exceeds 1, then the facility
is considered to pose a potential risk to surface water quality.
Table 3-16. Facility-Level Results for Groundwater to Surface Water
Pathway by Decharacterization Status
Facility Status
Environmental
Release3
May Exceed
Risk Criteria3
Risk results based on reported concentrations
Never characteristic
Decharacterized
All facilities with reported values
479(11%)
311 (7%)
790 (18%)
29 (0.7%)
14 (0.3%)
44(1.0%)
Risk results based on surrogate/DL concentrations
Never characteristic
Decharacterized
All facilities with surrogate/DL values
918 (21%)
161 (4%)
1,079 (24%)
9 (0.2%)
22 (0.5%)
31 (0.7%)
DL = Detection limit.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
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March 26, 2001
Chapter 3
Table 3-17. Impoundment-Level Results for Groundwater to Surface Water
Pathway by Liner Status
Impoundment Status
Environmental
Release"
May Exceed
Risk Criteria3
Risk results based on reported concentrations
Lined
Not lined
All impoundments with reported values
1,123(9%)
1,028 (9%)
2,150(18%)
0 (0%)
64 (0.5%)
64 (0.5%)
Risk results based on surrogate/DL concentrations
Lined
Not lined
All impoundments with surrogate/DL values
426 (4%)
1,121 (9%)
1,547(13%)
0 (0%)
74 (0.6%)
74 (0.6%)
DL = Detection limit.
a Number of impoundments (percentages are of the total number of in scope impoundments, approximately 11,900).
Table 3-18. Facility-Level Results for Groundwater to Surface Water Pathway by
Discharge Status"
Facility Status
Environmental
Release3
May Exceed
Risk Criteria3
Risk results based on reported concentrations
Direct dischargers
Zero dischargers
All facilities with reported valuesb
622 (14%)
115(3%)
738 (17%)
14 (0.3%)
27 (0.6%)
42 (0.9%)
Risk results based on surrogate/DL concentrations
Direct dischargers
Zero dischargers
All facilities with surrogate/DL valuesb
906 (20%)
76 (2%)
982 (22%)
31 (0.7%)
0 (0%)
31 (0.7%)
DL = Detection limit.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
b Note that the facility totals for Tables 3-16 through 3-18 do not match. This is because the patterns of missing
data are different for each of the tables, and the weight adjustments for missing data lead to slightly different
estimates.
3.3.3 Discussion of Uncertainties
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March 26, 2001 Chapter 3
There are several key uncertainties that should be considered in interpreting the results of
the surface water quality screening assessment. These are grouped under parameter uncertainties,
modeling uncertainties, and results uncertainties. This section identifies these sources of
uncertainty and qualitatively describes how each may influence the results. Additional details on
these uncertainties are presented in Appendix C to this report.
3.3.3.1 Parameter Uncertainties. The critical parameters required for the screening
modeling of surface waterbodies included flow rates and dilution/attenuation factors.
• Flow Rates. Flow rates were a potentially significant source of uncertainty; the
low flow rate (7Q10) was often greater than the average flow rate, suggesting that
the data sources were highly variable. In addition, many flow rate estimates are
based on end-of-stream locations, which could be a substantial distance from the
point at which the groundwater could reasonably be expected to intersect with the
surface waterbody. Consequently, the river dilution factor calculated from the
flow rate may be highly uncertain.
• Dilution/Attenuation Factors. For surface waterbodies within 150 meters, a
default DAF of 1.0 was chosen. This value tends to overestimate the contaminant
flux in groundwater that reaches the surface waterbody. The DAFs in Industrial
Waste Evaluation Model (IWEM) were used for waterbodies beyond 150 meters
and, as with the default DAF, these were developed for a groundwater screening
tool. The resulting groundwater concentrations will generally lead to an
overprediction of the contaminant concentration in the surface waterbody.
3.3.3.2 Modeling Uncertainties. The screening modeling for the groundwater to surface
water pathway simplifies the fate and transport of chemicals from groundwater to surface water
and is based on several assumptions. These simplifications generally rely on precautionary
assumptions and, as a result, the modeling approach tends to overpredict the potential effects on
water quality.
• Groundwater Flow Direction. For the surface water screening, groundwater
flow direction was inferred from the topography and a plausible groundwater flow
direction was established perpendicular to the receiving waterbody—either a
flowing waterbody or a quiescent system such as a small pond. In addition, the
plume was assumed to completely intersect with the waterbody so that the
groundwater would exert the maximum impact on the surface waterbody. The
combination of these assumptions creates a bias toward higher surface water
concentrations.
• Designation of Fishable Waterbody. The closest fishable waterbody was
identified for each impoundment based on both survey responses and simple
decision rules. However, there may be substantial uncertainty in this selection
because, in many instances, survey responses were not useful in identifying the
closest fishable waterbody.
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March 26, 2001 Chapter 3
• Infiltration Rates. The infiltration rates used in this analysis were developed
with the EPACMTP model using generalized soils data. These are not site-
specific data but are intended to represent the conditions expected in the area.
The infiltration rates are not site-specific and may over- or underpredict the
contaminant flux to groundwater.
3.3.3.3 Results Uncertainties. It is important to consider several key uncertainties in
interpreting the significance of the surface water pathway results. The modeling approach is
based on the assumption of instantaneous and thorough dilution throughout the surface
waterbody, which would create a constant exposure profile for human usage throughout the
entire receiving waterbody. In reality, contaminant release into the surface waterbody through
this pathway would likely be associated with a concentration gradient that would vary the
exposure pattern throughout the length of the waterbody. In many instances, only a small portion
of the receiving waters may actually maintain chemical concentrations above the HH-AWQC.
For the highest area of contamination (perhaps a "favorite" fishing spot), the dilution may mask
potentially adverse impacts on surface water quality. Nevertheless, the results of this analysis
suggested that, despite the proximity of receiving waterbodies to surface impoundments, the risks
from adverse effects to surface water quality are generally low nationwide.
• Data Gaps. The screening criteria (HH-AWQC) selected for this analysis were
identified in EPA's compilation of national recommended water quality criteria
developed pursuant to section 304(a) of the Clean Water Act. An HH-AWQC
was not available for all of the constituents that failed the preliminary screen;
therefore, the results may not capture impacts from all chemicals that may be
released through this pathway.
• Additive/Synergistic Effects. The screening modeling does not address the
possibility that other contaminant sources may be releasing similar chemical
constituents into the same waterbody. For waterbodies that are already receiving
significant contaminant loads of similar chemicals (or synergistic chemicals), the
chemical release from an impoundment may be a significant contributor to water
quality degradation.
• Surface Water as a Drinking Water Source. Some facilities were located next
to freshwater systems and others were located adjacent to saline estuarine systems.
In freshwater systems EPA used HH-AWQC that assume both fish consumption
and use of the waterbody as a drinking water source without treatment. Because
few people use untreated surface water as a source of drinking water, some of the
results are overestimates of the potential groundwater to surface water risk. In
estuarine systems, EPA assumed the water would not be used as a source of
drinking water and only used the HH-AWQC that are based on fish consumption.
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March 26, 2001 Chapter 3
3.4 Other Indirect Pathways
3.4.1 Methodology
The potential for industrial sites with surface impoundments to pose a risk to surrounding
populations through indirect exposure pathways was evaluated using a screening analysis that
was implemented in two stages. Table 3-19 provides an overview of the methodology used.
In reviewing the indirect pathway methodology and results it is important to consider the
limited nature and explicit purpose of this risk screening. This analysis ranks and orders
facilities and impoundments based on whether they have the potential to generate an indirect risk.
Unlike the previous risk analysis of groundwater, air and groundwater to surface water this
analysis does not use models to predict the movement of chemicals through indirect pathways
and therefore this analysis never measures the actual degree of indirect risk, this analysis only
identifies the potential for risk. It is likely that many of the facilities in this screening analysis
that are indicated to have the potential for an indirect risk would not actually indicate a risk of
concern if modeling were conducted. This was certainly observed in the risk analysis of
groundwater, air, and groundwater to surface water. Since indirect pathways often involve even
more complex and highly site specific movement of contaminants through several different
environmental compartments (e.g., sludge to wind blown dust to crops to cattle to humans) it is
even more likely that many potential indirect exposure pathways would not be completed and as
a result the proportion of facilities with actual indirect risk are likely to be far less than those with
only the potential for risk.
In the first stage of the indirect screening, EPA reviewed the constituents reported in the
surveys to identify a short list of constituents of focused concern for indirect exposure. The
tendency to bioaccumulate is a chemical property that is considered especially relevant for
indirect pathways of exposure where accumulation occurs in food chains and humans ingest
these foods. This screening-level assessment of indirect pathways focused on those chemicals
having a significant potential to bioaccumulate. The first step was to rank order all the
constituents reported in the surveys, irrespective of their concentrations, according to their
potential to bioaccumulate considering chemical-specific data on bioaccumulation. Based on this
rank ordering, 37 constituents were included in our assessment of indirect exposure pathways.
These chemicals are shown in Table 3-20.
The second stage of the screening analysis was to identify all facilities that reported
managing these constituents and to screen these facilities according to their potential for indirect
exposures. This potential was evaluated by examining facility-specific data and environmental
settings, including probable proximity to receptors such as residents, farmers, and fishers. The
release scenarios considered were volatilization of constituents from wastewater, particulate
entrainment or erosion of constituents from exposed sludge, and leaching of constituents from
wastewater into groundwater with subsequent transport and release to surface water.
The criteria considered in the ranking process included size of the surface impoundment,
distance from the impoundment to the nearest receptor, slope of the terrain in the vicinity of the
site (which impacts the degree of erosion/runoff that may occur in some cases after closure), size
3-34
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Table 3-19. Overview of Tiered Risk Assessment Methodology for Indirect Pathway Assessment
Analysis
Stage
Risk Assessment Methodology—Indirect Pathway
Human Health
Chronic Risk Measure: Numeric ranking scheme for potential completion of indirect pathways
KJ
Approach
Receptor Exposure
Key Variables
Preliminary
screen
Precautionary screen for indirect
exposure potential conducted at the
facility-level
Focus on bioaccumulative chemical
constituents that may pose risk via
indirect exposures
Eliminate facilities from further
evaluation that do not manage
bioaccumulative chemicals
Indirect exposures (e.g., food chain) are
considered to be a function of the presence
or absence of bioaccumulative chemicals
Source concentration data indicating
that the facility manages
bioaccumulative chemicals
Release
Assessment
Take full advantage of site-specific
information on physiography,
residences, presence of farms, location
of nearest waterbody
Consider potential from exposures
associated with active impoundments
as well as for postclosure scenario
Scoring criteria include impoundment
characteristics such as surface area,
proximity to receptors, and
groundwater-surface water modeling
results
Use the numeric ranking criteria to
identify facilities with the highest
potential to complete indirect
pathways
Ingestion of fruits and vegetables grown in
local gardens or on local farms
Ingestion of animals and animal products
raised on local farms
Ingestion offish caught in fishable
waterbodies located near the facility
Receptors and farms located at actual
distances reported in the survey responses
or identified using GIS tools
Impoundment characteristics (e.g.,
size)
Distance to farms, residences
Distance to fishable waterbodies
Results from gw-sw pathway
screening modeling
Impoundment characteristics
Physiographical characteristics
indicating potential for erosion/runoff
of soil particles
GIS = Geographic information system.
n
5-
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March 26, 2001
Chapter 3
Table 3-20. Chemicals Selected for Inclusion in Indirect Exposure
Pathway Ranking Analysis
p,p'-DDT
Dibenz[a,h]anthracene
3 -Methylcholanthrene
Chlordane, alpha & gamma isomers
7,12-Trimethylbenz [a] anthracene
Lindane
Dieldrin
Endrin
Methoxychlor
p,p'-DDD
p,p'-DDE
Heptachlor
Fluorene
Hexachloro-1,3 -butadiene
1,2,4,5-Tetrachlorobenzene
2,4,5-Trichlorophenol
Endosulfan
Hexachlorobenzene
1,2,4-Trichlorobenzene
Kepone
Indeno(l,2,3-cd) pyrene
Benzo(b)fluoranthene
Aldrin
Pentachlorobenzene
Heptachlor epoxide, alpha, beta,
and gamma isomers
Polychlorinated biphenyls
2,3,7,8-TCDD
Lead
Mercury
Cadmium
Toxaphene
Pentachlorodibenzofurans
Hexachlorodibenzo-p-dioxins
Pentachlorodibenzo-p-dioxins
Tetrachlorodibenzo-p-dioxins
Hexachlorodibenzofurans
Tetrachlorodibenzofurans
of the waterbody (which can influence the degree of dilution following deposition of
bioaccumulative chemicals into waterbodies such as lakes, rivers, or creeks). These criteria were
quantified and integrated into a numerical ranking framework designed to provide a consistent
protocol to determine the potential for complete exposure pathways. The decision to list a
facility as potential concern, lower concern, or least concern is based on the outcome of the
numeric scheme.
The rankings assigned to facilities are based exclusively on an assessment of current site-
conditions, including both impoundment status and environmental setting criteria in the vicinity
of the facilities. However, a future closure scenario was also included in the analysis to address
potential risks following impoundment closure. The future closure scenario is based on the
precautionary assumption that all impoundments close without taking action to mitigate
environmental releases such as dredging of residual sludge and capping to prevent
erosion/runoff. Because of the precautionary assumptions underlying the future closure scenario,
the results of this portion of the analysis are used to qualify the overall rankings given to
individual facilities, but are not considered explicitly in assigning those rankings. Appendix C
provides additional detail on the methodology, and Attachment 17 of Appendix C presents the
full ranking results.
Once the screening had been completed to identify facilities where indirect pathways are
of potential concern, EPA generated national estimates of the proportion of facilities that could
pose concerns due to indirect pathway exposures. The measures used to portray the results in
Tables 3-1 and 3-2 (overview of results) and in the tables described below, are as follows:
• Potential Concern: This risk metric is an indicator of the potential for completion
of more than one indirect exposure pathway at the facility.
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• Lower Concern: This risk metric is an indicator of the potential for completion of
one indirect exposure pathway at the facility and, therefore, of relatively lower
concern.
• Least Concern: This risk metric is an indicator of low potential to complete even
one indirect exposure pathway at the facility.
3.4.2 Results
The screening analysis generated a number of results that provide a different perspective
on whether facilities have the potential to pose indirect exposures of concern to surrounding
populations. These include: (1) overall rankings, which summarize the overall facility-rankings
across the entire set of facilities that manage bioaccumulative chemicals, (2) results presented
according to which receptor population and exposure pathways are of concern. Appendix C
provides additional detail on these results and additional perspectives of potential interest.
3.4.2.1 Overall Results. Table 3-217 summarizes the overall results by characterization
status of the indirect pathway screening analysis, expressed as national estimates. Six percent of
facilities fall into the potential concern category for indirect exposure. Table 3-22 presents the
overall results by regulatory status, also expressed as national estimates, and indicates that all
facilities classified as of potential concern are direct dischargers.
3.4.3 Discussion of Uncertainties
The qualitative character of the indirect exposure pathway analysis leads to several major
areas of uncertainty that affect interpretation of the results. These are grouped under parameter
uncertainties, modeling uncertainties, and results uncertainties. Additional details on these
uncertainties are presented in Appendix C to this report.
Table 3-21. Facility-Level Results for Indirect Pathways by Decharacterization Status
Facility Status
Never characteristic
Decharacterized
All facilities
Lower Concerna
2,153(48%)
466 (10%)
2,620 (59%)
Potential Concerna
116(3%)
169 (4%)
285 (6%)
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
7 Because specific chemical concentrations are not used in the indirect assessment, these results are not
divided into reported vs. surrogate DL as other results are.
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Table 3-22. Facility-Level Results for Indirect Pathways by Discharge Statusa
Facility Status
Direct dischargers
Zero dischargers
All facilities'3
Lower Concerna
2,487 (56%)
181 (4%)
2,668 (60%)
Potential Concerna
272 (6%)
0 (0%)
272 (6%)
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
b The facility total for Table 3-22 does not equal the facility total for Table 3-21 because the patterns of
missing data are different for each of the tables, and the weight adjustments for missing data lead to slightly
different estimates.
3.4.3.1 Parameter Uncertainties. Key parameters required for this analysis fall into one
of two broad categories, including facility performance parameters and environmental setting
parameters. Various sources of uncertainty can impact each of these parameters. The following
parameter uncertainties are believed to have the greatest potential impact on the indirect exposure
pathway screening assessments.
• Distance to Nearest Receptor. The distance between specific impoundments and
the nearest receptor (i.e., residential areas, farms, or fishable waterbodies) was
estimated using a combination of aerial photos and topographic maps. Although
these measurements were made using the most up to-date photos and maps
available, some of the photos and maps were somewhat dated and possibly
inaccurate. This introduces uncertainty in the distance-to-nearest-receptor
measurements because land use change could result in a receptor either being
added to or removed from a given study area. This is less of an issue in
identifying fishable waterbodies.
• Assessment of Potential for Erosion/Runoff. Topographic maps used to assess
slope and the potential for sheet versus channel flow may not be current, in which
case significant changes in land use (which would not show up on older maps)
could introduce uncertainty into the characterization of this parameter.
3.4.3.2 Modeling Uncertainties. The indirect exposure pathway screening assessment is a
facility-level evaluation intended to rank facilities according to their potential for complete
indirect exposure pathways. This analysis uses a ranking algorithm together with facility-specific
and environmental setting criteria to generate overall ranking scores for individual exposure
pathways. The criteria used in this analysis were selected as surrogates for key factors related to
human health risk (e.g., impoundment surface area was used as a surrogate for level of chemical
emissions, distance to receptor was used as a surrogate for level of dispersion following source
release). The use of these surrogate parameters as criteria in the ranking algorithms for
individual exposure pathways, while appropriate given the screening nature of the analysis, does
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introduce modeling uncertainty into the analysis. In addition, there are uncertainties associated
with the ranking algorithms used in the analysis.
• Use of ranking algorithms. The ranking algorithm used in this analysis assumes
an additive relationship between the criteria that are considered. However, in
relation to actual risk, these criteria may have multiplicative or other nonlinear
relationships to each other, in which case the overall importance of individual
criteria could be misrepresented in the ranking algorithm.
• Use of surface area as a surrogate parameter. Total aggregated impoundment
surface area for a given facility was used as a surrogate for the level of constituent
emissions from that facility. However, a wide range of factors can influence the
degree of source emissions from an impoundment including chemical
composition of the wastewater/sludge and other environmental
setting/impoundment characteristics. Consequently, use of surface area as a
surrogate for emissions levels does introduce uncertainty into the analysis.
• Use of distance to receptor as a surrogate parameter. The shortest distance
from any of the impoundments at a facility to the nearest offsite receptor (i.e.,
resident, farmer, or fisher) was used as a surrogate for the degree of chemical
dispersion that would occur following release. However, a wide range of factors
in addition to distance-to-receptor can impact dispersion including meteorology,
topography, and the specific characteristics of the source release.
3.4.3.3 Results Uncertainties. The indirect exposure screening analysis is designed to
identify which facilities have the potential to pose an indirect exposure pathway risk to
surrounding populations. Given this scope, the analytical framework for the screening analysis
uses a combination of surrogate criteria and simple additive ranking algorithms in place of a
formal site-specific risk assessment framework to generate ranking results. While this semi-
quantitative approach does support ranking of facilities with regard to the potential for indirect
exposure pathway risk, care should be taken not to overextend conclusions drawn from the
analysis. A similar issue applies to results produced for the current status scenario versus future
closure scenario.
• Drawing Conclusions from the Analysis. Because the indirect exposure
screening analysis uses surrogate criteria combined with simple additive
algorithms to rank facilities, there is significant uncertainty associated with the
overall analysis that should be considered in interpreting results. While this
degree of uncertainty is considered acceptable for a first-pass assessment as to
whether individual facilities have the potential for indirect exposure pathway risk,
it precludes drawing any conclusions regarding the potential magnitude of risk
that these facilities could pose.
• Current Status Scenario Versus Future Closure Scenario Results. There is
significantly greater uncertainty associated with results generated for the future
closure scenario than for the current status scenario. This discrepancy results
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from the fact that the current status scenario is based on best available data
regarding the current status of modeled facilities, while the future closure scenario
is not intended as a "best guess" of future closure conditions at sites, but rather as
a precautionary analysis of the potential for indirect exposure pathway risk should
impoundments close without sufficient postclosure actions being taken to limit
constituent mobility. Reflecting this discrepancy in uncertainty, overall rankings
for the indirect exposure screening analysis are based only on results for current
status scenario—results from the future closure scenario are not considered in
assigning these rankings. However, the results of the future closure scenario
could be used to qualify the results of the current status scenario since they
provide perspective on how many facilities could pose an indirect exposure
pathway risk should impoundment closure occur without remediation.
3.5 Ecological Risk Screening
Industrial wastes managed in surface impoundments can potentially cause adverse effects
on flora and fauna in natural systems. Many impoundments are located near rivers and
waterbodies and are freely accessible to wildlife. Moreover, some chemicals are more toxic to
wildlife than to humans; wildlife species generally have higher metabolic rates than humans and,
therefore, eat, drink, and breathe proportionately more contaminants than humans. In addition,
nonhuman organisms live in closer association with their immediate environment and often
cannot avoid contamination or replace destroyed food sources as humans can. For this study,
EPA assessed the potential for impoundments to pose risks to populations and communities of
ecological receptors that live in and near surface impoundments.
3.5.1 Methodology
Table 3-23 provides an overview of the methodology used to assess potential ecological
risks. The ecological risk screening was similar to the first screening stage of the human health
risk analysis, but did not go beyond that stage to consider actual exposures and did not rely on
fate and transport modeling. The assessment strategy is intended to represent only the potential
for adverse ecological effects, not the actual risk posed to wildlife.
In reviewing the ecological risk screening methodology and results it is important to
consider the limited nature and explicit purpose of this evaluation. This analysis ranks and
orders facilities and impoundments based on their potential to generate an ecological threat.
Unlike the previous risk analysis of groundwater, air, and groundwater to surface water, this
analysis does not use models to predict the movement of chemicals through the environment and
actual exposure through the food chain. In this way the ecological risk screening analysis never
measures the actual degree of ecological risk; this analysis only identifies the potential for risk. It
is likely that many of the facilities in this analysis that are indicated to have the potential for an
ecological risk would not actually indicate a risk of concern if modeling were conducted. This
was certainly observed in the risk analysis of groundwater, air, and groundwater to surface water.
Because the ecological pathways often involve even more complex and highly site-specific
movement of contaminants through several different environmental compartments and food
chains (e.g., sludge to windblown dust to flora to fauna to other fauna), it is even more likely that
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Chapter 3
Table 3-23. Overview of Tiered Risk Assessment Methodology for
Screening Ecological Risk Assessment
Analysis
Stage
Risk Assessment Methodology
Ecological Receptors
Chronic Risk Measures: (1) Media concentrations in excess threshold concentration and
(2) Exposure in excess of a reference dose
Approach
Receptor Exposure
Key Variables
Preliminary
Screen
Screen using protective
ecological screening
factors for range of taxa
Use endpoints relevant to
population sustainability
and community
structure/function
Eliminate impoundments
with no evidence of risk
from further evaluation
Ascertain potential for
adverse ecological effects
across habitats
Divide facilities into two
categories based on the
number of receptor
exceedances: potential
concern or lower concern
Identify sensitive and
protected ecosystems in the
proximity of facilities with
chemicals that exceed risk
criteria
Direct consumption of
impoundment water
Direct contact with
contaminants in sludge and
impoundment water
Direct ingestion of sludge and
plant/animals in contact with
the sludge
Receptors presumed to have
complete access to
impoundment and rely on
immediate area as major food
source
Impoundment
chemical
concentrations
Ecological
benchmarks including
NOAELs
Ecological exposure
factors
NOAEL = No observed adverse effect level.
many potential ecological pathways would not be completed; as a result, the proportion of
facilities with actual ecological risk is likely to be far smaller than the proportion with only the
potential for risk.
A screening assessment was performed to estimate the potential risk for a wide variety of
plants and animals. EPA assigned receptors to each facility based on regional data sources and
land use characteristics at each facility. EPA screened for ecological risk in a manner similar to
that used in the preliminary screening stage for noncancer risks for humans. The assessment
compares chemical concentrations in surface impoundment water and sludge to concentrations
that are considered protective of animals and plants. When this ratio, or hazard quotient,
exceeds 1, there is the potential for adverse effects; if the result is less than 1, adverse effects are
not expected for a particular ecological receptor. The ecological screening assessment is
precautionary because it is based on direct ingestion or uptake of the surface impoundment
influent. Risk was assessed for birds, mammals, and amphibians as well as for organisms that
live in the soil, water, and sediment (e.g., worms, fish, and insect larvae). Plants that grow in
water and those that grow on land were also assessed. By including many different types of
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ecological receptors, EPA can infer a degree of protection to ecosystems as a whole.8 An
additional element of the ecological screening considered whether surface impoundments are
located near sensitive ecosystems such as wetlands, wildlife refuges, or national forests.
The final stage of the screening-level assessment was to compare the number of each
facility's risk exceedances9 to the median number of exceedances (38 exceedances) for all the
facilities that did not screen out. Using this standard, facilities were placed in two categories:
• Potential concern: Facilities having at least the median number of exceedances
for ecological receptors (i.e., 38 or more exceedances).
• Lower concern: Facilities having fewer than the median number of exceedances
for ecological receptors.
Note that the selection of the median number of exceedances does not guarantee that an equal
number of facilities will be assigned to the two risk categories. The risk results from the sample
population are weighted-up to produce the national risk estimates; therefore, the percentages for
each risk category reflect the weights and missing data patterns as well as the exceedance rate.
3.5.2 Results
Based on the comparison with screening factors, a total of 34 chemicals exceeded the risk
criteria for at least one receptor at one impoundment, and 54 of the more than 62 ecological
receptors considered in this assessment showed potential risk exceedances. These receptor taxa
include mammals, birds, and plants, as well as organisms living in the soil, water, and sediment.
Wildlife species for which potential risks were indicated cover a variety of taxa and feeding
strategies, from species that depend on aquatic systems for food (e.g., mink, river otter,
kingfisher, great blue heron) to those typical of terrestrial systems (e.g., terrestrial plants, coyote,
white tailed deer, cerulean warbler). These results were not based on modeling; they represent a
screening-level exposure assessment that implies direct usage of the impoundment by wildlife.
EPA recognizes that, although direct usage is possible, surface impoundments are not designed to
provide habitat and it is highly unlikely that many receptors would rely on an impoundment
exclusively to provide shelter, food sources, and other attributes of functioning habitats.
Nevertheless, these results do measure the potential ecological impacts at a national level.
Regionally unique species occurring in coastal areas of the southeastern United States (e.g., Florida
manatee) and other species listed as threatened and endangered were not evaluated in the analysis. However, the
precautionary nature of the screening factors, which are based on standards such as EPA ambient water quality
criteria and no observed effects levels, implies some degree of protection for species already considered to be under
stress.
9 Risk exceedances are defined as the ratio of the chemical concentration in the medium of interest to the
ecological screening factors for surface water, sludge, and soil, as appropriate.
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Chapter 3
Figure 3-2 presents the nationally weighted facility results correlated with potentially
sensitive ecosystems such as wetlands and managed areas (e.g., national wildlife refuges,
national forests). Approximately 25 percent of all facilities that show screening-level risk
exceedances are located within 1 km of a permanently flooded wetland or 3 km of a managed
area. Figure 3-2 illustrates the relative level of exceedances for lower concern (light shading)
and potential concern (dark shading). At facilities identified as of potential concern, 19 percent
are located within 1 km of a wetland and 7 percent are located within 3 km of a managed area.
At facilities listed as lower concern, 19 percent are located within 1 km of a wetland and 14
percent are located within 3 km of a managed area. Slightly more than 3 percent of these
facilities have both a wetland within 1 km and a managed area within 3 km.
3.5.2.1 Quantitative Risk Estimation for Ecological Risk Screening. Tables 3-24 and
3-25 summarize the ecological screening results. Because of the screening nature of the
assessment and the precautionary exposure assumptions used, these results are associated with a
high level of uncertainty. As shown in Table 3-24, 29 percent of facilities may pose potential
concern for ecological receptors. Table 3-24 distinguishes the facilities according to whether
they manage decharacterized wastes, and Table 3-25 distinguishes facilities according to their
discharge status. Most of the facilities of potential concern manage never characteristic wastes
and are direct dischargers. This is consistent with the fact that 80 percent of facilities manage
never characteristic wastes and the vast majority of facilities are direct dischargers.
V)
o>
o
re
o
]_
d>
1
3
Wetland within 1 km Managed area within 3 Wetland within 1 km
km and managed area
within 3 km
Proximity to Sensitive Ecosystem
H Lower Concern
• Potential Concern
Figure 3-2. Summary of sensitive ecosystem analysis.
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Chapter 3
Table 3-24. Facility-Level Results for Ecological Risk by Decharacterization Status
Facility Status
Never characteristic
Decharacterized
All facilities
Lower Concern"
2,007 (45%)
352 (8%)
2,359(53%)
Potential Concern"
1,037 (23%)
273 (6%)
1,310(29%)
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
Table 3-25. Facility-Level Results for Ecological Risk by Discharge Status"
Facility Status
Direct dischargers
Zero dischargers
All facilities'3
Lower Concern"
2,058 (46%)
101 (2%)
2,160(48%)
Potential Concern"
1,072 (24%)
160 (4%)
1,232 (28%)
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
b The facility total for Table 3-25 does not equal the facility total for Table 3-24 because the patterns of missing
data are different for each of the tables, and the weight adjustments for missing data lead to slightly different
estimates.
3.5.3 Discussion of Uncertainties Associated with Screening Ecological Risk Analysis
The screening nature of the analysis leads to several major areas of uncertainty that affect
interpretation of the results. These are grouped under parameter uncertainties, modeling
uncertainties, and results uncertainties. Additional details on these uncertainties are presented in
Appendix C to this report.
3.5.3.1 Parameter Uncertainties. The key parameters required for the ecological risk
screening include the list of ecological receptors assigned to each facility, dietary assumptions,
and ecological screening factors. As appropriate for screening-level analyses, the selection of
parameter values tends to support a precautionary assessment.
• Ecological Receptor Assignments. Ecological receptors were assigned at each
facility as a function of the land use patterns and presence of wetlands and/or
fishable waterbodies. This adds to the protective nature of the screening
assessment because not all facilities are located in areas of sufficient ecological
quality to sustain those receptors.
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• Assumptions on Dietary Exposure. Screening-level assessments typically
assume exclusive intake of contaminated prey in the diets of primary and
secondary consumers (i.e., 100 percent of the diet originates from the
contaminated area), providing a very conservative estimate of potential risks.
• Conservatism of Screening Factors. Because the screening factors were
generally based on benchmarks for very low levels of effect for sensitive
endpoints, these factors tend to be precautionary of wildlife species and natural
communities.
3.5.3.2 Modeling Uncertainties. The screening ecological risk assessment did not
involve fate and transport modeling of chemical movement and uptake into plants and prey
items. Consequently, this direct exposure approach is precautionary in the sense that it implies
actual usage of the impoundment as habitat.
• Spatial Scale of Exposure. The screening level of resolution does not provide
insight into the scope/size of ecological impacts. The size of the contaminated
area is a critical determinant of the risk results because larger areas dilute
chemical concentrations. Restricting the area to the impoundment tends to bias
the results toward an overestimate of risk.
• Temporal Scale of Exposure. The timing is assumed to include the entire life
stage of the wildlife species evaluated or, in the case of community-type receptors
(e.g., soil biota), a period that is relevant to the structure and function of the
community. The chronic, low-level exposure that this implies may be
underprotective of some species during sensitive lifestages or of short-lived
species.
• Constant Chemical Concentration. The chemical concentration was assumed to
be constant for the screening analysis when, in reality, the chemical concentrations
in plants, prey, and media will vary over time and space. A constant chemical
concentration will tend to overpredict the potential risks to wildlife.
• Chemical Behavior. For screening purposes, all forms of a constituent are
assumed to be equally bioavailable and toxic. This assumption may either
overestimate or underestimate the actual exposures, depending on the
environmental characteristics. For example, the form of arsenic (i.e., elemental,
ionic, and methylated) has been shown to influence toxicity profoundly.
• Single Chemical Exposures. The risk of each constituent is considered
separately in this analysis, and this may overlook possible synergistic effects.
This is one example of a potential underestimation of adverse effects.
3.5.3.3 Results Uncertainties. As with any screening ecological risk assessment, there is
considerable uncertainty in the risk results associated with simplifying assumptions and data
limitations such as ecological benchmarks. Moreover, the screening analysis does not address
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the potential significance of predicted ecological impacts. Although the ecological risk results
indicate that the potential for adverse ecological effects exists at these facilities, it is not possible
to quantify that potential within the broader context of ecological health and sustainability. Key
uncertainties to consider in interpreting the risk results are as follows:
• Concentration Data Source. A portion of the risk findings are based on
surrogate data and detection limits, rather than on reported concentrations, which
contributes to the overall uncertainty in the results.
• Data Gaps. Protective ecological screening factors were developed for
constituents when sufficient data were available, which, for this analysis, included
41 chemicals. The absence of benchmarks may lead to the underestimation of
risks associated with stressors for those chemicals that could not be evaluated.
• No Additional Stressors. The only stressor assumed in the screening analysis is
the introduction of chemicals into the environment. In the field, wildlife may be
exposed to a variety of stressors (e.g., habitat alteration) and, therefore, the risk
results may underestimate the potential for adverse effects.
• Threatened/Endangered Species. Only common species were evaluated in this
analysis. The sensitivity of endangered species that are already under substantial
stress is not accounted for explicitly. Although the selection of screening
approach and parameters is inherently precautionary, it is possible that the results
do not capture the risks to sensitive species and habitats.
3.6 Summary and Conclusions
This section summarizes several key findings of the risk assessment and highlights
findings that address the statutory requirements for the scope of the study.
The assessment of potential risks posed by surface impoundments was based on a tiered
approach designed to address comments from EPA's Science Advisory Board and external peer
review comments on the technical plan. The first stage of this tiered approach was an initial
screening based on precautionary exposure assumptions. Subsequent stages increased the level
of realism through the use of increasing levels of facility-specific data, screening-level models,
and site-based models. At each stage in the analysis, EPA was able to identify chemicals at
particular surface impoundments and facilities that did not require further analysis. Given the
design of the overall approach, which proceeds from precautionary exposure scenarios to realistic
exposure scenarios, and based on the data available to EPA, the Agency has concluded that those
constituents and impoundments do not pose significant risks to human health or the environment.
The risk estimates developed in this study for human health and the screening conducted
for indirect exposures and ecological risks are based on an extensive analysis of the survey data
reported for a wide array of chemicals and impoundments of potential concern. EPA
acknowledges the uncertainties in the predicted risks and considers the following findings to be
representative of the population of industrial surface impoundments managing wastewaters.
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3.6.1 Summary of Major Risk Analysis Findings
• Most facilities and impoundments nationally do not appear to pose risks to human
health through environmental releases. Two percent of impoundments and 5
percent of facilities show potential risk exceedances for at least one pathway,
based on reported concentration data.
• Twenty-four percent of impoundments (21 percent of facilities) have the potential
for environmental releases to occur from impoundments by at least one pathway,
considering the chemical concentrations present in the impoundments and site-
specific attributes such as the presence or absence of liners and proximity to
surface water. These releases do not appear to pose risks to human health;
however, some degradation of the environment is possible.
• For 23 percent of facilities and impoundments overall, EPA was not able to
estimate potential risks with any confidence due to lack of chemical concentration
data. This study portrays a range of possible findings, limited to the extent they
are based on inferred data and detection limits, that may provide insights into
potential risks or environmental releases for some portion of these facilities.
3.6.2 Findings by Pathway Based on Risk Analysis
• Direct inhalation risks can occur if a toxic chemical volatilizes from the
impoundment's water surface, is carried by air dispersion to nearby residences,
and then is inhaled by residents. EPA developed risk estimates for the closest
residences, based on locations reported in the surveys or identified through census
information, and generated national estimates of the proportion and number of
facilities and impoundments exceeding levels of concern. Most facilities (87
percent) and impoundments (92 percent) appear to pose no concern. Four percent
of facilities and three percent of impoundments do not pose risks, but do show
releases that exceed levels of concern within 25 meters from impoundments. Four
percent of facilities and one percent of impoundments are estimated to have a
potential for risk exceedances to occur. Five percent of facilities and 4 percent of
impoundments cannot be assessed with confidence due to incomplete reporting of
concentration data. For those chemicals with reported concentration values, only
chlorodibromomethane and alpha-hexachlorocyclohexane exceeded risk criteria
and only acetaldehyde contributed to a calculated facility risk of potential concern.
• Groundwater ingestion risks can occur if impoundments release toxic chemicals
through the bottom or sides of the impoundment and these chemicals enter
groundwater and move through the subsurface to a drinking water well. EPA
developed risk estimates that could occur at the closest drinking water wells
reported in the surveys. If survey data were not available, EPA used census
information and assigned the receptor well to the nearest residence identified with
a census block that reports drinking water well usage. The majority of facilities
and impoundments appear to pose no concerns. A very small percentage of
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facilities and impoundments have the potential for risk exceedances to occur at
the time the impacted groundwater reaches the closest well. Fourteen percent of
facilities and eleven percent of impoundments do not appear to pose risks but are
predicted to generate groundwater releases that will exceed levels of concern at or
beyond 150 meters of the unit boundary. About 19 percent of facilities and 22
percent of impoundments cannot be assessed with confidence due to the lack of
concentration data.
• Groundwater to surface water risks can occur if impoundments release toxic
chemicals through the bottom or sides of the impoundment and these chemicals
migrate through groundwater, discharge into nearby surface water, and
contaminate fish and drinking water supplies. EPA identified exceedances of
human health ambient water quality that could occur to surface waterbodies that
were reported in the surveys and generated national estimates. Fifty-six percent of
facilities do not appear to pose concerns by this pathway. About 18 percent of
facilities may produce contaminated groundwater concentrations that exceed the
FtH-AWQC at the point of entry into the surface waterbody. One percent of
facilities may contribute to exceedances of EPA's HH-AWQC by this pathway.
About 25 percent of facilities could not be assessed with confidence because of
the lack of concentration data.
3.6.3 Findings Based on Risk Screening
EPA also screened for potential risks to human health through other indirect pathways
and screened for potential risks to ecological receptors.
• Indirect pathway risks can occur when humans ingest food sources that have
been contaminated indirectly by surface impoundment releases. For example,
toxic chemicals can evaporate, move by dispersion through air, and then deposit
on nearby crops and contaminate food sources. Another example may occur when
impoundments close with sludge left in place; chemicals present in those sludges
can move with stormwater, or by erosion, onto nearby soil and crops or can be
dispersed as dust. Based on a screening analysis and precautionary assumptions,
an estimated 6 percent of facilities nationally may pose the greatest potential
concern through indirect pathways.
• Ecological risks are possible for flora and fauna in natural systems located near
impoundments. Many impoundments are located near rivers and waterbodies and
are freely accessible to wildlife. The objective of the ecological screening was to
characterize the national potential for adverse ecological effects associated with
the management of chemicals in impoundments considered within the scope of
this study. Although the screening methods imply that the impoundment is used
directly as habitat, the intent of the screen is to characterize the potential for
adverse ecological effects at the site, not simply from direct use of the
impoundment. The measure of this potential was based on ecotoxicological
endpoints relevant to the sustainability of wildlife populations (e.g., reproductive
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effects) and the structure and function of communities (e.g., growth and survival
of key species). Based only on this initial screening level analysis and using
precautionary assumptions, no more than 29 percent of facilities nationally may
pose potential concerns to ecological receptors that live near, or make direct use
of, surface impoundments.
3.6.4 Additional Findings of Interest
EPA examined potential risks for decharacterized wastes separately from never
characteristic wastes and also examined potential risks depending on discharge status. This was
to address the statutory intent in the 1996 Land Disposal Program Flexibility Act that the study
assess decharacterized wastewaters managed in surface impoundments subject to the Clean
Water Act.
• The results suggest that impoundments managing decharacterized waste may be
associated with higher risks than those managing never characteristic waste for
two pathways of concern. For one pathway, direct inhalation, the trend is
reversed, with never characteristic waste representing two-thirds of the overall
risk. This is largely because most impoundments (about 80 percent) manage
never characteristic wastes. However, for all pathways, including direct
inhalation, the rates of risk exceedances for decharacterized wastes were higher
than for never characterized wastes.
• The bulk of facilities are direct dischargers; consequently, most of the potential
risk exceedances and environmental releases are associated with direct
dischargers. For the groundwater to surface water pathway, the rates of potential
HH-AWQC exceedances are much higher for zero dischargers even though the
national numbers in that group are relatively small.
Reference
U.S. EPA (Environmental Protection Agency). 1997. EPA 's Composite Model for Leachate
Migration with Transformation Products, EPACMTP. User's Guide. Office of Solid
Waste, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1998. Industrial Waste Air Model Technical
Background Document. EPA-530-R-99-004. Washington, DC: U.S. Government
Printing Office.
U.S. EPA (Environmental Protection Agency). 1999a. Technical Background Document:
Industrial Waste Management to Support the Guide for Industrial Waste Management.
EPA530-R-99-002. Washington, DC: U.S. Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1999b. User's Guide for the Industrial Waste
Management Evaluation Model (IWEM): Tier 1 Look-up Tables and Tier 2 Neural
Networks. EPA530-R-99-003. Washington, DC: U.S. Government Printing Office.
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Chapter 4
Regulatory/Program Coverage and Gaps Analysis
4.0 Introduction and Background
This chapter presents EPA's regulatory/program coverage and gaps analysis in support of
the Surface Impoundment Study. The regulatory/program coverage and gaps analysis was
conducted to satisfy provisions of (1) the Land Disposal Program Flexibility Act of 1996 and
(2) a consent decree in the matter ofEDF v. Whitman. The methodology and regulatory coverage
findings are summarized under the following sections:
4.1 Regul atory/Program Analysi s Methodol ogy
4.2 Coverage and Potential Gaps in Existing Programs and Regulations Addressing
Air Risks
4.3 Coverage and Potential Gaps in Existing Programs and Regulations Addressing
Nonair Risks
4.4 The Role of EPA's Multimedia Strategy for PBT Pollutants in Reducing Risks
from Surface Impoundments.
4.1 Regulatory/Program Analysis Methodology
The general approach for conducting the regulatory coverage and gaps analysis for this
study required a detailed review of provisions in applicable federal and state programs that
address surface impoundments, an evaluation of the extent to which the constituents of concern
are specifically addressed by such programs, and the extent to which the industry categories
covered by this study are addressed by the programs. The regulatory coverage and gaps were
identified and evaluated based on potential risks found by the human health and ecological risk
screening analyses, as described in Chapter 3. The regulatory gaps analysis addresses coverage
for each of the two human direct exposure pathways of concern (i.e., air and groundwater),
indirect pathways including groundwater releases to surface water, and other indirect pathways.
The information reflects risk results with varying levels of certainty. The level of certainty
depends, in part, on the extent to which the results were based on (1) reported concentration
values, and (2) surrogate data (including detection limit values). Regulatory gaps identified
based on this information thus carry the same level of varying certainty.
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4.1.1 Approach for Conducting Regulatory/Program Coverage and Gaps Analysis for Air
Risks
To evaluate regulatory coverage and potential gaps in regulations addressing air releases
from surface impoundments, EPA identified existing federal and state programs that potentially
address such releases. Federal programs evaluated included RCRA hazardous and nonhazardous
waste programs and the Clean Air Act. The specific activities and related analyses are
summarized below. The detailed analysis is presented in Section 4.2.
Existing RCRA Regulations/Programs That Can Address Air Risks from Non-
Hazardous Surface Impoundments. EPA evaluated existing RCRA regulations and programs
that address air emissions from nonhazardous waste surface impoundments. RCRA programs
(both federal and state) are included in this part of the analysis primarily to address the
requirement of the LDPFA to evaluate the extent to which existing federal and state programs
address risks posed by decharacterized wastes in surface impoundments. The coverage analysis
also applies to never characteristic wastes managed in surface impoundments, thereby providing
additional information to support EPA's obligations under the EDF consent decree. Programs
evaluated were:
• RCRA Subtitle C corrective action program (and the authority under RCRA
section 3005) to address air risks from nonhazardous surface impoundments
located at RCRA interim status and permitted facilities,
• RCRA Subtitle D (nonhazardous) waste regulations and state programs that
address air emissions from nonhazardous waste surface impoundments,
• EPA's draft Guide for Industrial Waste Management (U. S. EPA, 1999a),
• Toxicity characteristic (TC) (to assess whether the management of impoundment
wastewaters not classified as hazardous by the TC could still result in
environmental air releases), and
• Other nonregulatory programs including the use of Supplemental Environmental
Projects (SEPs) and EPA's Multimedia Strategy for Persistent, Bioaccumulative,
and Toxic Pollutants.
Existing RCRA Subtitle C Hazardous Waste Regulations and Programs That
Address Air Emissions from Hazardous Waste Surface Impoundments. Even though the
focus of the surface impoundment study is on nonhazardous wastes, hazardous waste
requirements were included in this part of the analysis to address the extent to which regulations
can address air risks from wastes in impoundments if these wastes were newly characterized or
listed as hazardous wastes. If a waste were classified as hazardous, then it would be subject to
current Subtitle C requirements.
The following provisions within the Subtitle C program were evaluated to determine the
extent to which these programs can address potential air risks: requirements for hazardous waste
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management units (e.g., Subpart K, Surface Impoundments), RCRA air emission control
standards (e.g., Subpart CC—Air Emission Standards for Tanks, Surface Impoundments, and
Containers), land disposal restrictions, the omnibus permitting authority under RCRA section
3005(c)(3), and the RCRA corrective action program.
This discussion assumes these wastes will continue to be managed in surface
impoundments even if they became subject to the Subtitle C requirements. It is perhaps more
realistic to assume that these wastes would be managed in tanks if they became subject to the
Subtitle C requirements (such that the LDR requirements would not apply). The tank
management scenario was evaluated as part of EPA's Air Characteristics Study (U.S. EPA, 1998,
1999b).
Existing Clean Air Act Programs. The primary focus of the air pathway analysis was
the CAA requirements. Identifying potential gaps in current CAA regulations was required to
fulfill one of the obligations in the EDF consent decree. The analysis also provided information
needed to satisfy the requirements of the LDPFA. The analysis involved three interrelated
elements: (1) a waste management unit analysis to identify provisions within the CAA that can
address surface impoundments, (2) a constituent coverage analysis that focused on the
constituents of concern from the risk assessment, and (3) an industry coverage analysis that
focused on the industry categories within the scope of this study.
The outputs of the waste management unit, constituent, and industry analyses were
integrated with the findings of the risk assessment to identify those constituents and industry
categories for which regulations or programs may not adequately address potential risks.
4.1.2 Approach for Conducting Regulatory Program Coverage and Gaps Analysis for Nonair
Risks Found from Managing Nonhazardous Waste in Surface Impoundments
In addition to examining potential air risks, EPA investigated risks to other media as well.
In this portion of the analysis, EPA assessed program coverage of (1) risks resulting from
consumption of groundwater containing constituents released from surface impoundments,
(2) risks resulting from the contamination of surface water (from the groundwater pathway),
(3) risks posed via other indirect pathways (e.g., erosion runoff and deposition), and (4)
ecological risks, collectively identified as "nonair risks." EPA evaluated the extent to which
these predicted risks are adequately addressed under existing federal and state programs.
4.1.2.1 Approach for Conducting Regulatory/Program Coverage and Gaps Analysis for
Groundwater and Surface Water Risks Found from Managing Nonhazardous Waste in Surface
Impoundments. Leachate from a nonhazardous waste surface impoundment can potentially
migrate through the subsurface and affect groundwater and surface water quality. Therefore, it
was necessary to identify existing regulations and programs that address the release of
constituents from nonhazardous waste surface impoundments to groundwater and surface water.
The general approach for identifying regulatory coverage by federal and state programs
comprises four general steps:
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1. Use the risk analysis results to identify constituents posing potential risks to
groundwater.
2. Identify federal regulations and programs that address releases to groundwater
from nonhazardous waste surface impoundments.
3. Identify state regulations and programs that address releases to groundwater from
nonhazardous waste surface impoundments.
4. Determine if gap exists.
4.1.2.2 Approach for Conducting Regulatory Program Coverage and Gaps Analysis for
Risks Associated with Other Indirect Pathways. As discussed in Chapter 3, EPA evaluated
potential risk scenarios from indirect pathways, including air deposition to surrounding crops and
exposures resulting from runoff and erosion of contaminated sludge particles onto local farms
and gardens. Runoff and erosion of contaminated sludge was assumed to occur after closure;
therefore, EPA evaluated regulations and programs addressing industrial runoff, corrective
action, and postclosure care. EPA did not evaluate regulatory coverage of indirect risk posed by
air deposition separately; it is included in the air pathway coverage analysis.
4.1.2.3 Approach for Conducting Regulatory Program Coverage and Gaps Analysis for
Ecological Risks. The approach for evaluating regulatory coverage and gaps for any ecological
risks focused on reviewing regulations, programs, and guidance on location standards for new
units and other provisions in federal and state programs designed to protect endangered and
threatened species and habitats.
4.2 Coverage and Potential Gaps in Existing Programs and Regulations Addressing Air
Risks
One of the primary objectives of the Thg intent rf ^ chapter ig to identify existing
surface impoundment study was to investigate
gaps in the current hazardous waste
characteristics and CAA programs for air
risks associated with managing never
programs/regulations that are used to address risks
from surface impoundments and to identify possible
gaps in them based on the results of the risk
assessment. If EPA determines these gaps must be
propose changes to existing regulations or propose
new regulations to address the gaps, such as new
LDR requirements, a new hazardous waste
characteristic, a new hazardous waste listing, or
perhaps investigate the protectiveness of some of the
hazardous waste exclusions/exemptions.
, . . .. . . r- addressed, then the Agency may either: (1) use
characteristic wastes in surface existing programs as fool/to J^ the gapg or (2)
impoundments. A related objective was to
address the requirements of
section 3004(g)(10) of RCRA, as amended by
the LDPFA, which required EPA to evaluate
the extent to which risks posed from
decharacterized wastes in surface
impoundments are adequately addressed
under existing state and federal programs.
This part of the study, which in part fulfills EPA's obligation under both the EDF consent decree
and the LDPFA, describes the Agency's analysis of coverage by regulations that address air risks
posed by wastes managed in surface impoundments.
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The regulatory coverage and gaps analysis for the air pathway addresses relevant RCRA,
CAA, and state regulations and programs; however, emphasis is placed on those constituents that
did not screen out of the study upon completion of the risk assessment for the air pathway. The
direct inhalation risk assessment determined that air emissions from surface impoundments can,
in some cases, potentially exceed the specified risk threshold. Specifically, the risk assessment
identified the possibility of risks associated with 13 chemicals. Refer to Chapter 3 for more
detailed information on the risk assessment findings.
4.2.1 Existing RCRA Rules and Programs That Address Air Risks
Existing RCRA Subtitle C and Subtitle D programs include various provisions that, when
implemented, can limit air emissions from nonhazardous waste surface impoundments. This
section includes the following:
• An analysis of the ability of the RCRA Subtitle C corrective action program (and
the authority under RCRA section 3005) to address air risks from nonhazardous
surface impoundments located at RCRA interim status and permitted facilities
(Section 4.2.1.1).
• An analysis of Subtitle D (nonhazardous) RCRA waste regulations and state
programs that address air emissions from nonhazardous waste surface
impoundments (Section 4.2.1.2).
• An analysis of coverage by EPA's draft Guide for Industrial Waste Management
(Section 4.2.1.3).
• An analysis of the TC regulatory levels to determine if the management of
impoundment wastewaters not classified as hazardous by the TC (e.g.,
decharacterized wastewaters or wastewaters that have never been hazardous
waste) could still result in environmental air releases (Section 4.2.1.4).
• A description of EPA's enforcement program for SEPs and how it may be used to
address risks posed by nonhazardous waste surface impoundments. Note that the
use of SEPs is discretionary, and their potential application for addressing risks
posed by surface impoundments would be determined on a case-specific basis
(Section 4.2.1.5).
Finally, EPA's Multimedia Strategy for Persistent, Bioaccumulative, and Toxic (PBT)
Pollutants (PBT Strategy) has the goal of reducing risks to human health and the environment
from current and future exposure to priority PBT pollutants. See Section 4.4 for an evaluation of
how the PBT initiative may affect constituents that may be found in surface impoundments.
4.2.1.1 RCRA Corrective Action Program. Permitting Authority under RCRA 3005. and
RCRA 7003. Facilities that treat, store, or dispose of hazardous waste (TSDFs) must apply for a
RCRA Subtitle C permit. Under RCRA 3004(u), RCRA permits must require corrective action
for releases of hazardous waste or constituents from any solid waste management units
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(SWMUs) as necessary to protect human health and the environment. TSDFs that have not yet
received permits and have been authorized to operate under interim status may be compelled to
conduct corrective action under section 3008(h). Under the RCRA corrective action program, a
surface impoundment containing nonhazardous waste located at a TSDF is considered an
SWMU. Therefore, releases from these impoundments, including air emissions, are subject to
corrective action requirements on a site-specific basis.1 EPA can incorporate specific corrective
action requirements into the permit during the permitting process or when a permit is already in
place. Corrective action requirements could include interim measures (e.g., use of a temporary
cover), institutional controls (such as deed restrictions or access controls), and application of
remediation technologies designed to contain, remove, and/or destroy contamination.
The survey indicates that about 33 percent of the surface impoundments nationwide that
fall within the scope of this study have been designated as SWMUs pursuant to the RCRA
corrective action RCRA Facility Assessment (RFA) process (see also Chapter 2, Section 2.5, for
additional information on the permit and corrective action status of impoundments within the
scope of this study). This indicates that a significant number of nonhazardous surface
impoundments are located at RCRA TSD facilities; these impoundments are being addressed by
EPA and the states on a priority basis, and thus no regulatory gaps should exist for these
impoundments.
RCRA contains various additional permitting requirements for facilities. The omnibus
permitting authority at RCRA section 3005(c)(3) requires EPA to include in permits any
requirements necessary to protect human health and the environment. For impoundments
containing nonhazardous waste, permit writers may use their omnibus permitting authority under
RCRA 3005(c)(3) to impose additional standards to achieve the health-based requirements of
RCRA 3004(n).
RCRA section 3005(h) mandates, as a permit condition, that TSDFs that are also
generators must have a program in place to reduce the volume and toxicity of the waste they
generate. These waste minimization requirements, to the extent they are used to minimize
concentrations of constituents of concern that might be released to the air pathway, provide some
potential for control of air emissions.
Note that the imminent and substantial endangerment provision of RCRA section 7003
allows EPA, upon evidence of past or present handling of solid or hazardous waste, to require
any action necessary if a situation presents an imminent and substantial endangerment to health
or the environment. This authority applies to all facilities that manage solid waste, whether or
not they have a RCRA permit, and could be used at any impoundment that is within the scope of
this study if the situation meets the statutory threshold.
4.2.1.2 Coverage by State Waste Programs. Historically, regulation of nonhazardous
waste has been provided by the states; however, state nonhazardous waste regulations typically
1 See also EPA's policy on integrating RCRA corrective action with requirements imposed in permits
issued pursuant to other environmental laws at 55 FR 30798, 30808 (July 27, 1990), and 61 FR 19423, 19442
(May 1, 1996).
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March 26, 2001 Chapter 4
do not include provisions that address inhalation risks from nonhazardous waste surface
impoundments. Previous studies summarizing state nonhazardous waste regulations, including
ASTSWMO (1996), ICF (1993), and U.S. EPA (1995a, 1995b), provide limited information on
programs for controlling air emissions from industrial nonhazardous waste surface
impoundments.
EPA's own analysis for this study indicates that, of the 50 states, only six have waste
regulations or other waste programs in place that address, to some degree, air emissions from
industrial nonhazardous waste surface impoundments. These states are California, Colorado,
Delaware, Louisiana, Maryland, and Pennsylvania (see also Appendix D, Section D-l, Summary
of State Regulations and Programs Covering Nonhazardous Industrial Waste Surface
Impoundments). The type of regulatory coverage varies considerably among these states. For
example, some states require monitoring and reporting of emissions and some require permits.
Another state regulates both fugitive dust and gas emissions. Note that this program coverage
discussion applies to waste programs (i.e., RCRA) and not air programs. State air regulations
should provide more extensive coverage for air releases from surface impoundments.
Note that EPA's analysis of state waste regulations and programs in Appendix D is based
on publicly available information rather than a survey of state regulators. EPA did not review
state air programs. Therefore, the analysis may not have identified all state regulations and
programs that address nonhazardous waste industrial surface impoundments. Furthermore, the
state regulatory coverage may change in the future.
Federal regulations for solid waste disposal facilities (including nonhazardous waste
surface impoundments) are given in 40 CFR Part 257, Criteria for Classification of Solid Waste
Disposal Facilities and Practices. Regulations that specifically address potential impacts to air
are identified in 40 CFR 257'.3-1'. However, the Part 257 applicability to air emissions from
surface impoundments of this study is limited to restrictions on open burning and referencing
applicable State Implementation Plan (SIP) requirements (see Part 257.3-7(a) and (b)). The
regulatory coverage of the Part 257 requirements does not provide additional restrictions beyond
those provided by the SIPs. Due to the complexity and potential for change, as noted above, SIPs
were not evaluated as part of this study.
4.2.1.3 Coverage by EPA 's Draft Guide for Industrial Waste Management. In 1999,
EPA's Office of Solid Waste, in collaboration with states, industry, and environmental groups,
published the draft Guide for Industrial Waste Management (U.S. EPA, 1999a). The document,
which is voluntary and commonly referred to as the "Industrial D Guidance," evaluates all
aspects of the design and operation of industrial waste management facilities to enable these
facilities to protect human health and the environment. It is designed primarily for new units and
can be used by state regulatory programs to evaluate their existing programs. The approach taken
in the guide is site-specific to help communities and facility managers identify a protective
facility site, design, and operation that fits their needs.
The draft guide recommends a three-part strategy for addressing potential air risks from
waste management units (including surface impoundments). First, the guide helps the user
determine whether the waste management unit(s) is already subject to requirements under the
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Clean Air Act. Second, the guide provides a tool (the IWAIR model software) to assess risks
associated with toxic air emissions. Third, the guide suggests the user implement pollution
prevention, treatment, or controls to reduce risks, if appropriate. For the protection of air, 95
constituents are addressed in the draft guide.
The extent to which risk assessment constituents of concern are addressed by this guide is
discussed in Section 4.2.3.2.
4.2.1.4 Toxicity Characteristic Regulatory Levels. Under RCRA regulations, a solid
waste is defined as a hazardous waste if it either is listed as a hazardous waste or exhibits one of
the four characteristics of a hazardous waste (i.e., toxicity, ignitability, corrosivity, or reactivity).
Wastes are listed as hazardous based on the criteria set forth in 40 CFR 261.11. Once listed, the
waste is presumed hazardous regardless of the concentration of hazardous constituents present
(unless the generator has successfully petitioned EPA to delist the waste) and must be managed
in accordance with Subtitle C standards. In contrast to hazardous waste listings, the toxicity
characteristic provides concentration-based regulatory thresholds used to identify wastes that
present significant hazard and therefore should be managed under Subtitle C. The regulations
defining the other three characteristics (ignitability, corrosivity, and reactivity) do not generally
address specific constituents and are not addressed in this analysis.
The TC was designed to protect against human health risks from exposure to hazardous
waste constituents released to groundwater. EPA's current definition of toxicity was promulgated
in 1990, replacing the Extraction Procedure (EP) leach test with the Toxicity Characteristic
Leaching Procedure (TCLP). The final TC rule added 25 organic chemicals to the eight metals
and six pesticides on the existing list and established regulatory levels for these constituents. All
39 TC constituents (40 including total cresols) are also on the list of 256 constituents of interest
for this study.
Wastewaters with TC constituent concentrations meeting or exceeding the TC regulatory
levels would be hazardous, subject to the protective measures required under RCRA Subtitle C
regulations (unless exempted or excluded from regulation), and thus are not within the scope of
this study. To determine if wastewater concentrations at or below TC levels could still result in
environmental releases to the air pathway, a direct comparison was made between the
milligram/liter TC levels in the regulations (40 CFR 261.24) and waste concentrations in surface
impoundments predicted to cause environmental air releases. For purposes of this analysis,
environmental air releases are defined as air releases from surface impoundments that result in
predicted risks as indicated by the screening-level Industrial D risk model for receptors at a
default distance of 25 meters rather than site-specific distances to receptors. This comparison is
presented in Appendix D, Section D-2.
The wastewater concentrations (presented as ranges in Appendix D) are divided into three
categories: concentrations with predicted inhalation risks less than the risk criteria,
concentrations with predicted risks in the range of 10E-5 to 10E-4 or HI of 1 to 10, and
concentrations with predicted risks greater than 10E-4 or HI greater than 10. It is appropriate to
report a range of concentration values because risk results for a given constituent varied
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significantly due to factors such as the concentration of the constituent in the wastewater, the size
of the impoundment, where it is located, and whether it is aerated.
The comparison indicates that concentrations of 10 TC constituents in surface
impoundment wastewater may result in environmental air releases at concentrations less than
their respective TC regulatory levels. As mentioned above, this conclusion is based on the use of
a screening-level risk model employing conservative assumptions (i.e., chronic exposure at 25
meters). The 10 constituents include nine volatile organics plus mercury. For the remaining nine
volatiles on the TC list, there were no concentration data that yielded predicted environmental
releases. This does not mean, however, that the TC regulatory levels for these constituents
prevent environmental air releases (we did not evaluate whether environmental air releases
would occur if concentrations of these constituents increased). The remaining 21 non-volatiles
on the TC list are constituents that would not likely cause environmental air releases, and risk
estimates were not conducted for these constituents.
The TC constituents that show the potential for environmental air releases in
Appendix D-2 reflect risk results with varying levels of certainty. The level of certainty depends,
in part, on the extent to which the results were based on (1) reported concentration values and
(2) surrogate data (including detection limit values). For this analysis, we did not determine the
extent to which predicted environmental air releases were based on reported or surrogate data.
4.2.1.5 Use of Supplemental Environmental Projects to Address Risk from Surface
Impoundments. If EPA or a state believes that an individual or company has failed to comply
with federal environmental laws, it may initiate an enforcement action. Enforcement actions are
taken to require an individual or company to return to compliance and deter others from violating
these laws. Enforcement settlements may also include Supplemental Environmental Projects
(U.S. EPA, 2001). EPA's SEP Policy encourages the use of environmentally beneficial projects
as part of the settlement of an enforcement action. Through SEPs, the settlement of an
enforcement action can result in environmental and public health protections beyond that
specifically required by law. There must be some connection between the SEP and the kinds of
concerns addressed by the statute or statutes that were violated (EPA SEP Policy, May 1, 1998).
The SEP Policy provides criteria to guide when and how SEPs may be included as part of a
settlement. SEPs may not be appropriate in the settlement of all cases, but they are an important
part of EPA's enforcement program.
SEPs are actions taken by an individual or company that are in addition to what is
required to return to compliance with environmental laws. A SEP is an environmentally
beneficial project that a violator voluntarily agrees to perform. When volunteering to perform a
SEP, a company must show that it can and will complete the project and must provide all funds
used to finance the project. EPA provides oversight to ensure that the company does what it
promises to do. EPA, however, does not manage or control the funds.
EPA has seven specific categories of projects that can be acceptable SEPs. These include
Pollution Prevention, Pollution Reduction, Public Health, Environmental Restoration and
Protection, Assessments and Audits, Environmental Compliance Promotion, and Emergency
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Planning and Preparedness. Other acceptable SEPs would be those that have environmental
merit but do not fit within the categories above (U.S. EPA, 2000b).
In the context of a nonhazardous waste surface impoundment, a violation of existing
regulations affecting a facility could result in an enforcement action and then, as a condition of
the settlement, EPA and the defendant could agree upon a SEP that is related to reducing the
risks posed by a surface impoundment at the facility. A SEP related to a surface impoundment
could include closure, installation of a liner, or implementation of some other measure that
would eliminate or reduce risk to the environment and/or public health.
4.2.2 Extent to Which Current RCRA Subtitle C Regulations Address Risks from Wastes Newly
Classified as Hazardous
Subtitle C of RCRA established management practices to safely control hazardous wastes
from the point of generation to final disposal. If a waste stream that is within the scope of this
study was newly classified as hazardous based on a new characteristic or listing, then it would be
subject to current Subtitle C requirements for hazardous waste surface impoundments (assuming
the waste stream continued to be managed in a surface impoundment). Therefore, the RCRA
hazardous waste regulations relevant to the regulatory analysis include those that limit air
emissions from surface impoundments. Several RCRA Subtitle C regulations and RCRA
statutory provisions have this effect, including
• Requirements for hazardous waste management units (e.g., Subpart K—Surface
Impoundments)
• RCRA air emission control standards (e.g., Subpart CC—Air Emission Standards
for Tanks, Surface Impoundments, and Containers)
• Land disposal restrictions
• Omnibus permitting authority under RCRA section 3005(c)(3)
• RCRA corrective action program.
These regulations and provisions are discussed in Sections 4.2.2.1 through 4.2.2.5.
4.2.2.1 Subpart K—Surface Impoundments. RCRA standards for hazardous waste
TSDFs include specific requirements for surface impoundments. Because a new characteristic or
listing could subject additional wastes to RCRA Subtitle C standards, it would also subject
surface impoundments managing the waste to Subtitle C standards and permitting as well, if such
units do not currently manage hazardous wastes (and the wastes are continued to be managed in
the impoundments). Thus, affected surface impoundments would be subject to the requirements
at 40 CFR Parts 264 and 265, Subpart K. These requirements include the use of double liners,
leachate collection, leak detection, inspection, waste analysis, financial responsibility, closure,
and postclosure. In addition, there are special requirements restricting the placement of ignitable
and reactive wastes in surface impoundments. To control air emissions, Subpart K requires the
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owner or operator to manage all hazardous waste placed in a surface impoundment in accordance
with the requirements of Subparts CC—Air Emission Standards for Tanks, Surface
Impoundments, and Containers.
4.2.2.2 Subpart CC—Air Emission Standards for Tanks. Surface Impoundments, and
Containers. Section 3004(n) of RCRA authorizes EPA to regulate air emissions from hazardous
waste TSDFs. Under this authority, EPA issued air emission standards under 40 CFR Part 264
and 265, Subpart CC—Air Emission Standards for Tanks, Surface Impoundments, and
Containers. Subpart CC applies to tanks, surface impoundments, containers, and certain
miscellaneous units that
• Are not expressly exempted from the rule.
• Are subject to permit standards (40 CFR 264) or interim status standards
(40 CFR 265)
• Manage hazardous wastes that have an average volatile organic concentration at
the point of waste origination equal to or greater than 500 parts per million by
weight (ppmw).
These requirements do not apply to surface impoundments in which all the hazardous
waste entering the surface impoundment meets one of the following (40 CFR 264.1082(c) and
265.1083(c)):
• The average volatile organic concentration of the hazardous waste at the point of
waste origination is less than 500 ppmw (as noted above)
• The organic content of the hazardous waste has been reduced by an organic
destruction or removal process. For example, organic destruction can be
achieved by waste incineration or biodegradation. Organic removal must achieve
the treatment level specified for the process.
• The waste meets the treatment standards for hazardous waste as specified in
40 CFR 268.40 or has been treated by the treatment technology established by
EPA for the waste in 268.42(a) or by an equivalent method.
To control air emissions from a surface impoundment managing a hazardous waste with a
volatile organic concentration greater than 500 ppmw, an owner or operator must install and
operate either a floating membrane cover or a cover that is vented through a closed-vent system
to a control device. The floating membrane cover must meet certain design and inspection
requirements including use of materials that meet standards for organic permeability and
compatibility with the waste, weather conditions, and operating conditions. The facility must
also perform periodic (once per year) inspections for membrane defects.
The technical requirements for the RCRA air rules in Subpart CC as amended are
essentially the same as those adopted by EPA under the MACT program (e.g., requirements in
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March 26, 2001 Chapter 4
Subparts OO, PP, and QQ of Part 63). A unit controlled under one or the other set of
requirements would achieve the same emission reduction and performance level; the various
requirements thus provide the same level of protection (61 FR 59939, November 25, 1996).
Due to the exclusion for wastes below the 500-ppmw threshold for volatile organic
content, any wastes subject to the Subpart CC requirements that potentially pose air risks at
concentrations less than 500 ppmw might not be controlled by the Subpart CC air emission
standards for surface impoundments.
4.2.2.3 Land Disposal Restrictions Treatment Requirements. RCRA LDRs limit the
placement of untreated hazardous waste in all land-based waste management units, including
landfills, wastepiles, land application units, and surface impoundments. Under 40 CFR 268.1,
characteristic wastes may not be land disposed unless (1) the wastes are treated in a Clean Water
Act or equivalent treatment system, and (2) the wastes no longer exhibit the characteristic at the
point of land disposal. Listed waste must meet treatment standards defined in 40 CFR Part 268,
Subpart D, prior to land disposal.
Note that RCRA section 3005(j)(l 1) and 40 CFR Part 268.4 (which implements that
provision) provide an exclusion allowing treatment of otherwise prohibited wastes (i.e., listed or
characteristic hazardous wastes that do not meet the otherwise applicable treatment standard) in
surface impoundments provided that treatment occurs in the impoundment, the treated residues
are removed at least annually, sampling and testing and recordkeeping requirements are met, and
evaporation of hazardous constituents is not used as a means of treatment. Because the LDR
treatment requirements would not apply to these wastes, the LDR treatment requirements would
not mitigate risks to the air pathway. Nonetheless, such surface impoundments must meet the
Subpart K and Subpart CC design and operating requirements for hazardous waste surface
impoundments.
The LDR treatment standards—when they apply—are based on the performance of best
demonstrated available technology (BOAT) and are deemed sufficient to minimize threats to
human health and the environment posed by land disposal of the waste. In fact, the standards for
most organics reflect the performance of combustion technology, which destroys organics to
nondetectable levels, so that the treatment standard is actually the analytical detection limit for
the organic chemical times a factor that reflects technological variability. Consequently, EPA
has found that units receiving wastes that satisfy these standards for organics need not be
controlled further, since the organics in the wastes are already reduced to levels at which threats
posed by release of the organics have been minimized (see 61 FR 59941, November 25, 1996).
4.2.2.4 EPA 's Permitting Authority under RCRA 3005. If a waste i s newly subj ect to
Subtitle C, then EPA's permitting authority under RCRA 3005 is another statutory control that
could be used to address air risks posed by surface impoundments. See Section 4.2.1.1 for a
detailed explanation of EPA's omnibus permitting authority at RCRA section 3005(c)(3).
4.2.2.5 RCRA Corrective Action Program. If a waste is newly subject to Subtitle C, then
EPA's corrective action authority is another control that could be used to address air risks posed
by surface impoundments. See Section 4.2.1.1 for a detailed explanation of EPA's corrective
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March 26, 2001 Chapter 4
action authority under RCRA section 3004(u) for permitted facilities and under section 3008(h)
for interim status facilities.
4.2.3 Analysis of Coverage and Potential Gaps in CAA Requirements
This section focuses on relevant federal programs under the Clean Air Act to determine
the extent of coverage of air emissions from surface impoundments. This analysis was
conducted in four steps. First, a general analysis of relevant CAA programs was conducted
(Section 4.2.3.1). Second, an evaluation of the risk assessment constituents of concern was
conducted to determine the extent to which they are covered by existing programs
(Section 4.2.3.2). The third part of the analysis focused on the CAA NESHAP program since it
was identified as the primary program to address air releases from industrial surface
impoundments (Section 4.2.3.3). This section provides a list of NESHAP requirements that may
apply to surface impoundments and industry sectors that are within the scope of this study. The
fourth part of the analysis focuses on the Criteria Air Pollutant Program, which may, to a lesser
extent, also address air releases from surface impoundments (Section 4.2.3.4).
4.2.3.1 Overview of Relevant Clean Air Act Programs. The 1990 Amendments to the
CAA substantially enhanced existing air quality programs. These enhancements include new
attainment provisions for National Ambient Air Quality Standards (NAAQS) and substantial
changes to the NESHAP program including control of HAPs using MACT standards. These
programs can, to varying degrees, address air emissions from industrial surface impoundments.
Most of the CAA programs regulate significant sources of air pollution; these sources are
defined as major sources of air pollution. A major source generally includes all of the individual
emission points within a plant complex or facility; emissions from the source would be the sum
of emissions from all the individual emission points. Typical sources include petroleum
refineries, power plants, and manufacturing facilities. Whether a source meets the definition of
major depends on the type and amount of air pollutants it emits.2
The following subsections summarize the relevant CAA programs that address air
emissions from industrial surface impoundments.
Regulation of Hazardous Air Pollutants
Air Toxics Program. Prior to the 1990 CAA amendments, a few HAPs were regulated
using risk-based standards under the NESHAP program. These NESHAPs appear at 40 CFR
Part 61. Section 112 of the 1990 amendments to the CAA authorized EPA to set technology-
based standards to reduce HAP emissions. While both the risk-based standards (i.e., those
enacted prior to 1990) and the technology-based standards (i.e., those enacted after 1990) are all
considered NESHAPs, the risk-based standards are generally referred to as original NESHAPs
and the technology-based standards are referred to as MACT standards.
2 As discussed later, the definition of major source differs for the NESHAP and Criteria Air Pollutant
Program.
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March 26, 2001 Chapter 4
The following is a brief overview of the pertinent subsections of section 112 applicable to
this study:
List of Hazardous Air Pollutants
MACT Emissions Standards
Residual Risk Program
Area Source Standards
Urban Air Toxics Program.
List of Hazardous Air Pollutants. Section 112(b)(l) established the list of HAPs to which
the air toxics program applies. Currently EPA is required to regulate 188 HAPs.3 While broad in
nature, the statutory list may be modified by adding or deleting pollutants. The CAA also allows
outside parties to request an addition or deletion to the list of HAPs. EPA may, after notice and
comment, add or delete a pollutant. Section 112(b)(3)(B) lists the following criteria for adding a
pollutant to the list:
...determination that the substance is an air pollutant and that
emissions, ambient concentrations, bioaccumulation or deposition
of the substance are known to cause or may reasonably be
anticipated to cause adverse effects to human health or adverse
environmental effects.
MACT Standards. The technology-based MACT program and the related residual risk
program are key elements of the CAA air toxics provisions. Under section 112, EPA is required
to list all categories of major sources emitting HAPs and such area sources warranting regulation
and to promulgate MACT standards to control, reduce, or otherwise limit the emissions of HAPs
from these categories. To the extent possible, this list of source categories is consistent with the
list of source categories listed pursuant to New Source Performance Standard (NSPS)
requirements. EPA has identified 83 source categories requiring MACT standards and has
promulgated 47 MACT standards to date. The remaining standards are in various stages from
proposal to under development. As discussed in Section 4.2.3.3, many industry categories that
are within the scope of this surface impoundment study are, or will be, covered by a MACT rule.
A major source is defined as a facility with the potential to emit 10 tons per year or more
of any one HAP or 25 tons per year or more of a combination of HAPs. Under section 112(a)(l),
EPA is authorized to reduce the 10-ton/yr threshold upon a demonstration that a lesser quantity
cutoff is warranted.
MACT standards must require the maximum degree of emission reduction that EPA
determines to be achievable by each particular source category. Different criteria for MACT
standards apply for new and existing sources. In setting MACT standards, EPA does not
generally prescribe a specific control technology. Instead, whenever feasible, EPA sets a
performance level based on the performance of technology or other practices already used by the
3 The original list contained 189 chemicals; however, EPA removed caprolactam from the list in 1996 after
a review of the most current scientific information.
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March 26, 2001 Chapter 4
industry. Facilities are free to achieve these performance levels in whatever way is most
cost-effective for them. Eight years after each MACT standard is issued, EPA must assess the
remaining health risks from source categories through the residual risk program.
Residual Risk Program. To ensure that MACT regulations protect public health and the
environment, Congress included section 112(f) in the 1990 CAA Amendments, which requires a
human health risk-based and adverse environmental effects-based "needs test" in the second
regulatory phase of the air toxics program. In this phase, referred to as residual risk standard
setting, EPA is required to promulgate additional standards for those source categories that, after
imposition of MACT standards, are emitting HAPs at levels that present a potential unacceptable
risk to the public or the environment. Congress directed that such residual risk standards should
"provide an ample margin of safety to protect public health."
Section 112(f) specifically gives EPA the mandate to consider environmental health
assessment. Although not very explicit as to how this should be done, Congress does say that
EPA shall promulgate standards to provide an ample margin of safety to protect public health
unless the Administrator determines that a more stringent standard is necessary to prevent "an
adverse environmental effect." The statute directs that consideration of adverse environmental
effects must take into account "costs, energy, safety, and other relevant factors" in deciding what
level is protective. Adverse environmental effect is defined in section 112(a)(7) as "any
significant and widespread adverse effect, which may reasonably be anticipated to wildlife,
aquatic life, or other natural resources, including adverse impacts on populations of endangered
or threatened species or significant degradation of environmental quality over broad areas."
EPA has developed the residual risk strategy to implement the requirements of CAA
sections 112(f)(2) through (6). Goals of the residual risk strategy include (1) assessing any risks
remaining after MACT standard compliance, (2) determining if additional emission reductions
are necessary and, if so, for which source categories, (3) setting a standard that protects the public
with an "ample margin of safety," and (4) setting a more stringent standard, if necessary, to
protect the environment. (See U.S. EPA, 1999c, Residual Risk, Report to Congress., EPA-453/R-
99-001, for a more detailed description of the residual risk program.)
Area Source Standards. Area sources are smaller sources, such as dry cleaners and gas
stations, that release smaller amounts of toxic pollutants into the air than major sources. Area
sources are defined as sources that emit less than 10 tons per year of a single air toxic and less
than 25 tons per year of a mixture of air toxics. Though emissions from individual area sources
are often relatively small, collectively their emissions can be of concern. The CAA provides
EPA with broad authority to control HAP emissions from area sources. EPA is authorized to
develop technology-based standards for area sources when such sources present a threat of
adverse effects to health or the environment (this is often referred to as a "positive area source
finding" that is issued pursuant to CAA 112(c)(3)). These technology-based standards are to be
based either on MACT or generally achievable control technology (GACT). For example,
hazardous waste incinerators, cement kilns, and lightweight aggregate kilns are required to
comply with MACT standards, regardless of whether they are major or area sources.
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March 26, 2001 Chapter 4
Urban Air Toxics Program. The National Urban Air Toxics Strategy aims to reduce the
health risks associated with air toxics exposures affecting populations in urban areas
(metropolitan areas with population greater than 250,000) by developing a number of national
standards for stationary and mobile sources to reduce HAP risks. The strategy includes a
description of risk reduction goals; a list of 33 HAPs judged to pose the greatest potential threat
to public health in the largest number of urban areas, including 30 HAPs specifically identified as
being emitted from area sources; and a list of area source categories that emit a substantial
portion of these HAPs and that are being considered for regulation under section 112(d). The
goal of the strategy is to attain a 75 percent reduction in incidence of cancer attributable to
exposure to HAPs emitted by stationary sources. This is relevant to all HAPs from both major
and area stationary sources in all urban areas nationwide.
The list of area source categories includes 29 categories: 13 new categories being listed
for regulation and 16 categories already subject to standards or for which standards are under
development. The area source categories include industrial organic and industrial inorganic
chemical manufacturing.
Section 112(k)(3)(b) of the CAA requires that the Urban Air Toxics program ensure that
area sources that account for 90 percent of the aggregate emissions for each of the 30 area source
HAPs are subject to standards. The program has developed MACT standards for these 30 area
source HAPs for those area sources whose emissions pose the greatest threat to urban areas under
section 112(k). Section 112(k) requires that area source categories be subject to standards under
section 112(d). Section 112(d) standards are national standards that generally apply everywhere
in the country. Consistent with this approach, EPA expects to apply section 112(k) standards
nationally. This approach may also result in reductions of emissions from facilities with surface
impoundments not located in urban areas.
Additionally, if further analyses reveal that an area source category that is currently
unregulated or unlisted poses a public health risk, the Urban Air Toxics program will list that
source category under authority of section 112(c) and develop the necessary regulation under
112(d), or they may address it through other activities like pollution prevention or voluntary
programs. Similarly, if a specific source is contributing to a local risk problem, then it may be
more appropriate for the state, local, or tribal program to address it.
Regulation of Volatile Organic Compounds
Criteria Air Pollutant Program. The CAA authorizes EPA to protect human health and
the environment from criteria air pollutants, including ozone, lead, sulfur dioxide (SO2), nitrogen
oxides (NOX), particulate matter, and carbon monoxide (CO). Few sources emit ozone directly;
rather ozone is formed in the atmosphere through the reaction of VOCs and NOX. To attain the
ozone standard, EPA typically requires VOC and NOX emission reductions. The definition of
VOCs according to the CAA regulations (40 CFR Part 51.100), while complex, is basically any
compound of carbon (excluding CO, carbon dioxide, carbonic acid, metallic carbides or
carbonates, and ammonium) that participates in atmospheric photochemical reactions.
Essentially all organic compounds are considered VOCs except those with negligible
photochemical reactivity. The definition specifically excludes methane, ethane, methyl chloride,
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March 26, 2001 Chapter 4
methyl chloroform, and many chlorofluorocarbons (CFCs), and hydrochlorofluorocarbons
(HCFCs). Most of these are halogenated compounds (i.e., refrigerants) and do not take part in
the photochemical reactions that cause ozone formation. CAA provisions that reduce VOCs to
address ozone formation thus have the potential to limit VOC emissions from surface
impoundments.
As required by the CAA, EPA established NAAQS for the criteria air pollutants.
NAAQS are ambient concentrations above which the air is deemed unhealthy. Geographic areas
(e.g., counties and urban areas) in which ambient concentrations exceed the NAAQS are referred
to as nonattainment areas, and areas in which ambient concentrations are below the NAAQS are
called attainment areas.
Under the Criteria Air Pollutant Program, major sources are stationary facilities that emit
100 tons or more per year of a criteria air pollutant. For purposes of this study, this would mean
any source that emits greater than 100 ton/yr VOCs. Two of the major components of criteria air
pollutant control programs are New Source Review (NSR) and control programs under State
Implementation Plans that require reasonably available control technology (RACT) on existing
sources. In attainment areas, new and modified major sources must install best available control
technology (BACT) under the Prevention of Significant Deterioration (PSD) permit program,
which is an NSR program. Within nonattainment areas, states must require emissions reductions
beyond those called for in attainment areas to bring the area back into attainment. New and
modified major sources in nonattainment areas must be equipped with technology representing
lowest achievable emissions rate (LAER) as part of NSR permitting.
As previously discussed, existing sources in nonattainment areas must be equipped with
technology representing RACT. Although EPA publishes guidance for RACT, SIPs are designed
to meet local and regional problems and vary substantially between states. Smaller sources are
considered major in areas that are not meeting the NAAQS for a particular pollutant. For
example, VOC sources emitting 50 ton/yr are considered major for SIP and NSR programs in
areas in serious ozone nonattainment areas. The amount goes down to 25 ton/yr in severe
nonattainment areas and to 10 ton/yr in extreme nonattainment areas.
A federal program requiring emission reductions in both attainment and nonattainment
areas is the NSPS program. This program, as authorized by section 111 of the Clean Air Act,
requires EPA to identify source categories emitting criteria pollutants or their precursors and to
establish emissions limits for new, modified, and reconstructed sources of emissions. Emissions
limits must be based on the best demonstrated technology. To date, EPA has promulgated 77
NSPSs. As discussed in Section 4.2.3.4, several industry categories that fall within the scope of
this study have applicable VOC NSPS requirements; sources in these industry sectors would thus
be subject to the requirements if they met the definition of new, modified, or reconstructed
source.
4.2.3.2 Constituent Coverage Analysis. Under the CAA, constituents could be regulated
under the Air Toxics Program as HAPs or under the Criteria Air Pollutant Program pursuant to
NAAQS. For the purposes of evaluating emissions from surface impoundments, the relevant
criteria pollutants are VOCs. Note that some coverage may be provided by the draft Guide for
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March 26, 2001 Chapter 4
Industrial Waste Management (U.S. EPA, 1999a) as discussed in Section 4.2.1.3. This section
thus evaluates whether the risk assessment constituents of concern in this study are HAPs or
VOCs or are covered by the draft Guide for Industrial Waste Management.
The risk assessment identified 13 constituents of concern for the air pathway based on
reported data as well as surrogate data. Table 4-1 lists the 13 constituents and indicates if they are
CAA HAPs or VOCs.4 Table 4-1 also indicates whether the constituent is addressed in EPA's
draft Guide for Industrial Waste Management and the companion Industrial Waste Air Model.
As explained earlier, the constituents of concern listed in Table 4-1 reflect risk results
with varying levels of certainty. The level of certainty depends, in part, on the extent to which
the results were based on (1) reported concentration values and (2) surrogate data (including DL
values). Constituents of possible concern that were reported at specific concentration values
(above the detection limit) are identified in the table. Of the 13 constituents, only 3 represent
reported values. The 10 surrogate values were not detected, and, if present in the samples, were
at levels less than the detection limits. For these 10 constituents, modeling risk at the detection
limit provided a conservative and protective basis for analysis of regulatory gaps.
HAP Constituents. Of the 13 constituents of concern that show potentially elevated risk,
four are not HAPs. These four constituents cannot be directly controlled by MACT standards
unless they are added to the list of HAPs pursuant to section 112 (b)(3)(B). These constituents
may, however, be indirectly co-controlled by MACT standards if control of other, perhaps
similar, regulated constituents also results in control of the non-HAP (see discussion below on
draft Guide for Industrial Waste Management constituents for additional details on co-control).
Instances where non-HAPs pose risk can thus be considered a limitation of current CAA
requirements.
Nine of the 13 risk assessment constituents are CAA HAPs. These nine HAPs thus fall
within the jurisdiction of the MACT program. A HAP-emitting facility, however, must first be
subject to a specific MACT standard in order to be regulated under section 112 under the CAA.
Section 4.2.3.3 discusses the extent to which surface impoundments and industry sectors that are
within the scope of this study are, or will be, covered by MACT rules.
VOC Constituents. Table 4-1 identifies all 13 constituents of concern as VOCs under the
CAA. VOC regulations may fill regulatory gaps for those constituents not regulated as HAPs.
For example, NSPS Subpart QQQ regulates wastewater for petroleum refineries. Constituents
that are not HAPs but are VOCs could be controlled by oil/water separators or other NSPS
requirements under this subpart. One disadvantage of NSPS requirements is that they apply to
new and modified sources. This leaves a potential gap because the control requirements are not
applied to "grandfathered" sources. The same issue occurs with NSR program requirements.
Although BACT is applied to major modifications and new sources, grandfathered sources may
remain uncontrolled.
4 This risk assessment differentiated between volatile and semivolatile organic compounds as a result of
different analytical methods. 40 CFR Part 51.100 defines VOCs differently for the Criteria Air Pollutant Program.
Table 4-1 reflects the Part 51.100 definition.
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March 26, 2001
Chapter 4
Table 4-1. Extent That Constituents Exceeding Risk Criteria for Air Pathway Are HAPs,
VOCs, or Covered by Draft Guide for Industrial Waste Management
Chemical Name
alpha-Hexachlorocyclohexane [alpha-BHC] b
Acetaldehydeb'c
Chlorodibromomethane [dibromochloromethane]b
Acetonitrile [methyl cyanide] a
Acrolein [2-propenal] a
Bis(chloromethyl) ether [sym-dichloromethyl ether] a
Chloroform [trichloromethane] a
Hexachlorocyclopentadiene a
N-Nitrosodi-n-butylamine a
N-Nitrosodiethylamine a
Tetrachlorodibenzodioxins [TCDDs] a> °
Tetrachlorodibenzofurans [TCDFs] a
Toxaphene [chlorinated camphene] a
Totals
CAA HAP
•
•
•
•
•
•
•
•
•
9
Criteria
Pollutant
(VOC)
•
•
•
•
•
•
•
•
•
•
•
•
•
13
Addressed
by Guide for
Industrial Waste
Management
•
•
•
•
•
•
•
•
•
•
10
CAA = Clean Air Act.
HAP = Hazardous air pollutant.
VOC = Volatile organic compound as defined by criteria air pollutant program.
a Indicates risk estimate was based on surrogate or detection limit value.
b Indicates risk estimate was based on reported concentrations.
0 Indicates no individual chemical combination exceeds the risk criteria, but the aggregate facility-level risk does.
It is not clear to what extent SIP regulations will provide coverage. Although state
regulations may reduce emissions from surface impoundments, the regulations are likely to apply
only to major sources located in urban areas with photochemical smog problems. Because of
this, SIP programs were not included as a potential mechanism for gap filling even though they
may regulate surface impoundment emissions in some areas.
Draft Guide for Industrial Waste Management Constituents. The draft Guide for
Industrial Waste Management identifies 95 constituents for the protection of air (see Section
4.2.1.3). Ten of the 13 compounds that showed the potential for risk are addressed by the guide.
These 10 constituents included three of the four non-HAPs (chlorodibromethane, N-nitrosodi-n-
butylamine, and N-nitrosodiethylamine).
The three non-HAP, draft Guide for Industrial Waste Management constituents are also
considered VOCs, and any source emitting them would be subject to applicable VOC
regulations. If a source emits one of these three compounds along with any HAP, there could be
a co-control benefit. Co-control occurs when measures taken to reduce HAP emissions under the
MACT standards also reduce emissions of non-HAPs. Co-control is likely to occur at facilities
that are major HAP sources and that also emit non-HAP chemicals. Most of the technology-
based controls prescribed for HAPs will reduce emissions of all organic chemicals, including
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March 26, 2001 Chapter 4
non-HAPs. Similarly, most MACT requirements to reduce emissions of specific HAPs, or to
reduce total HAP emissions by specific amounts, imply or identify control technologies that are
also effective for non-HAP pollutants. Thus, co-emitted HAPs and non-HAPs could receive
roughly equivalent levels of control. For example, if a source generates wastewater containing
both chlorodibromomethane and a regulated HAP and is required to meet wastewater
concentration limitations pursuant to MACT, then the source's efforts to reduce the wastewater
HAP concentration could also reduce chlorodibromomethane concentrations. Lower
chlorodibromomethane wastewater levels would subsequently reduce chlorodibromomethane
emissions from any impoundment that receives that wastewater.
4.2.3.3 NESHAP Program Coverage. The primary regulatory program that addresses air
releases from industrial surface impoundments is the CAA NESHAP program. Under this third
step of this analysis, specific NESHAP regulations were examined to determine the extent to
which these requirements address air releases from surface impoundments.
Waste Management Unit Coverage. NESHAP rules that directly regulate surface
impoundments were examined. CAA regulations are not typically adopted for waste
management units such as surface impoundments—instead the emission limits are targeted at
specific source categories that may include surface impoundments as a regulated emission unit.
Generally speaking, most NESHAP standards tend to focus on HAP levels in wastewater
generated in the production process, which eventually could be treated/stored in the surface
impoundment unit (e.g., MACT standards may control HAP levels in wastewater as opposed to
requiring emission controls, such as a cover, on surface impoundments). However, there are
some NESHAP regulations that specifically address surface impoundments. Table 4-2 lists these
regulations.
Although there is a MACT standard for surface impoundments (40 CFR 63, Subpart QQ),
it is only applicable to facilities subject to other MACT or NESHAP requirements that also
reference subpart QQ. This subpart is listed only as an administrative convenience. The
requirements include standards for floating membrane covers and closed-vent systems venting to
a control device. The subpart also includes requirements for test methods, inspection procedures,
monitoring, recordkeeping, and reporting.
Industry Coverage. As previously discussed, MACT standards are typically issued for
specific industries. Table 4-3 lists the in-scope industry categories (by four-digit SIC code) and
the extent to which they are, or will be, covered by MACT standards (e.g., proposed, completed,
and upcoming). The table also notes if there is no existing, proposed, or scheduled MACT
standard for the industry sector. The four-digit SICs are ranked by estimated wastewater volume
managed in descending order. For example, Table 4-3 indicates that pulp mills (1) manage the
highest estimated volume of wastewater and (2) have an applicable MACT standard.
Table 4-3 shows that MACT requirements exist, or will exist, for the majority of the SIC
codes that manage the largest wastewater volume in surface impoundments. For example, the
paper and allied products industry, which EPA estimates manages roughly 67 percent of the
wastewater capacity, is subject to the Pulp and Paper Cluster rule (see Chapter 2, Table 2-2).
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March 26, 2001
Chapter 4
Table 4-2. Potential MACT and NESHAP Requirements
Applicable to Surface Impoundments
MACT/NESHAP
National Emission Standard for Benzene
Waste Operations
National Emission Standard for Organic
Hazardous Air Pollutants from the Synthetic
Organic Chemical Manufacturing Industry
for Process Vents, Storage Vessels,
Transfer Operations, and Wastewater
Operations
National Emission Standard for Hazardous
Air Pollutants from Off-Site Waste and
Recovery Operations
National Emission Standards for
Pharmaceuticals Production
National Emission Standards for Pesticide
Active Ingredient Production
National Emission Standards for Polyether
Polyols Production
Regulatory
Citation
40CFRPart61
Subpart FF
40 CFR Part 63
Subpart G
40 CFR 63
Subpart DD,
including 10 CFR
63 Subpart QQ
40 CFR Part 63
Subpart GGG
40 CFR Part 63
Subpart MMM
40 CFR Part 63
Subpart PPP
Waste Streams
Covered
Benzene-containing waste from chemical
manufacturing plants, coke byproduct
recovery plants, and petroleum refineries,
individual drain systems, wastewater
treatment system
Wastewater streams
Waste and recoverable
materials from offsite for treatment, storage,
disposal, recovery, or recycling
Wastewater
Wastewater
Wastewater
Table 4-3. List of In-Scope 4-Digit SICs and Extent to Which They are Covered by MACT
SIC (Ranked
by Estimated
Wastewater
Volume
Managed)
2611
2631
2621
2911
5171
SIC Title
Pulp mills
Paperboard mills
Paper mills
Petroleum refining
Petroleum bulk
stations and
terminals
Potentially Applicable MACT
Standard
Pulp and Paper Cluster Rule
Petroleum Refineries
Petroleum Refineries- Catalytic
Cracking, Catalytic Reforming
& Sulfur Plant Unit
Gasoline Distribution
Regulatory
Citation
40 CFR Part 63
Subparts S and MM
40 CFR 63 Subpart CC
40 CFR Part 63
Subpart UUU
40 CFR Part 63
Subpart R
Completed/
Proposed/
Upcoming
Completed
Completed
Proposed
Completed
(continued)
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Chapter 4
Table 4-3. (continued)
SIC (Ranked
by Estimated
Wastewater
Volume
Managed)
3313
3312
2821
SIC Title
Electrometallurgical
products
Blast furnaces and
steel mills
Plastics materials
and resins
Potentially Applicable MACT
Standard
Wool Fiberglass Manufacturing
Ferroalloys Production
Metal Coil (Surface Coating)
Integrated Iron & Steel
Steel Pickling-HCl Process
Metal Coil (Surface Coating)
Coke Oven Batteries
Coke Oven Batteries: Pushing,
Quenching and Battery Stacks
Polymers and Resins I
Polymers and Resins II
Polymers and Resins III
Polymers and Resins IV
Generic MACT
Amino/Phenolic Resins
Production
Miscellaneous Organic
Chemical Production and
Processes (MON)
Polyvinyl Chloride and
Copolymers Production
Cellulose Product Manufacture
Regulatory
Citation
40 CFR Part 63
Subpart NNN
40 CFR Part 63
Subpart XXX
40 CFR Part 63
Subpart SSSS
40 CFR Part 63
Subpart FFFFF
40 CFR Part 63
Subpart CCC
40 CFR Part 63
Subpart SSSS
40 CFR Part 63
Subpart L
40 CFR Part 63
Subpart CCCCC
40 CFR Part 63
Subpart U
40 CFR Part 63
Subpart W
40 CFR Part 63
Subpart OOO
40 CFR Part 63
Subpart JJJ
40 CFR Part 63
Subpart YY
40 CFR Part 63
Subpart OOO
40 CFR Part 63
Subpart FFFF
40 CFR Part 63
Subpart J
40 CFR Part 63
Subpart UUUU
Completed/
Proposed/
Upcoming
Completed
Completed
Proposed
Upcoming
Completed
Proposed
Completed
Upcoming
Completed
Completed
Completed
Completed
Proposed
Completed
Upcoming
Proposed
Proposed
(continued)
4-22
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March 26, 2001
Chapter 4
Table 4-3. (continued)
SIC (Ranked
by Estimated
Wastewater
Volume
Managed)
2819
2092
2874
2436
2063
3273
2022
2873
2035
4953
2869
SIC Title
Industrial inorganic
chemicals, not
elsewhere classified
Food and kindred
products (fish)
Phosphatic
fertilizers
Softwood veneer &
plywood
Food and kindred
products (beet
sugar)
Ready-mixed
concrete
Food and kindred
products (cheese)
Nitrogenous
fertilizers
Food and kindred
products (pickles,
sauces, salad
dressing)
Refuse systems
Industrial organic
chemicals, not
elsewhere classified
Potentially Applicable MACT
Standard
Hydrochloric Acid Production
Industry
Generic MACT
Cellulose Product Manufacture
Uranium Hexafluoride
Production
Regulatory
Citation
Rules not yet proposed
or promulgated
40CFRPart63
Subpart YY
40 CFR Part 63
Subpart UUUU
Rules not yet proposed
or promulgated
Completed/
Proposed/
Upcoming
Upcoming
Proposed
Proposed
Upcoming
No existing, proposed, or scheduled MACT standard
Phosphoric Acid Manufacturing
Plants/
Phosphate Fertilizer Plants
Plywood & Composite
Wood Products
Wood Building Products
40 CFR Part 63
Subpart AA and BB
40 CFR Part 63
Subpart ZZZ
40 CFR Part 63
Subpart QQQQ
Completed
Upcoming
Upcoming
No existing, proposed, or scheduled MACT standard
No existing, proposed, or scheduled MACT standard
No existing, proposed, or scheduled MACT standard
No existing, proposed, or scheduled MACT standard
No existing, proposed, or scheduled MACT standard
MSW Landfills
Synthetic Organic Chemical
Manufacturing Industry
(SOCMI) Manufacture
SOCMI for Process Vents,
Storage Vessels, Transfer
Operations, and Wastewater
40 CFR Part 63
Subpart AAAA
40 CFR Part 63
Subpart F
40 CFR Part 63
Subpart G
Proposed
Completed
Completed
(continued)
4-23
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March 26, 2001
Chapter 4
Table 4-3. (continued)
SIC (Ranked
by Estimated
Wastewater
Volume
Managed)
2869 (cont.)
3353
2653
3339
3351
3334
2824
2899
2833
3229
SIC Title
Aluminum sheet,
plate, and foil
Corrugated and
solid fiber boxes
Primary nonferrous
metals, not
elsewhere classified
Copper rolling and
drawing
Primary aluminum
Organic fibers,
noncellulosic
Chemical
preparations, not
elsewhere classified
Medicinals and
botanicals
Pressed and blown
glass, not elsewhere
classified
Potentially Applicable MACT
Standard
SOCMI for Equipment Leaks
SOCMI for Negotiated
Regulation for Equipment Leaks
Generic MACT
Polyether Polyols Production
Cellulose Product Manufacture
Metal Coil (Surface Coating)
Regulatory
Citation
40 CFR Part 63
Subpart H
40 CFR Part 63
Subpart I
40 CFR Part 63
Subpart YY
40 CFR Part 63
Subpart PPP
40 CFR Part 63
Subpart UUUU
40 CFR Part 63
Subpart SSSS
Completed/
Proposed/
Upcoming
Completed
Completed
Proposed
Completed
Proposed
Proposed
No existing, proposed, or scheduled MACT standard
Wool Fiberglass Manufacturing
Primary Magnesium Refining
40 CFR Part 63
Subpart NNN
Rules not yet proposed
or promulgated
Completed
Upcoming
No existing, proposed, or scheduled MACT standard
Primary Aluminum Production
Metal Coil (Surface Coating)
Generic MACT
Miscellaneous Organic
Chemical Production and
Processes (MON)
Misc. Organic Chemical
Production & Processes (MON)
40 CFR Part 63
Subpart LL
40 CFR Part 63
Subpart SSSS
40 CFR Part 63
Subpart YY
40 CFR Part 63
Subpart FFFF
40 CFR Part 63
Subpart FFFF
Completed
Proposed
Proposed
Upcoming
Upcoming
No existing, proposed, or scheduled MACT standard
Wet Formed Fiberglass Mat
Production
40 CFR Part 63
Subpart HHHH
Proposed
(continued)
4-24
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March 26, 2001
Chapter 4
Table 4-3. (continued)
SIC (Ranked
by Estimated
Wastewater
Volume
Managed)
3624
2435
2843
4952
2251
2834
3011
3341
3761
2865
3399
9711
2211
3321
SIC Title
Carbon and graphite
products
Hardwood veneer &
plywood
Surface active
agents
Sewerage systems
Women's hosiery,
except socks
Pharmaceutical
preparations
Tires and inner
tubes
Secondary
nonferrous metals
Guided missiles and
space vehicles
Cyclic crudes and
intermediates, and
organic dyes and
pigments
Primary metal
products, not
elsewhere classified
National security
Broadwoven fabric
mills, cotton
Gray and ductile
iron foundries
Potentially Applicable MACT
Standard
Regulatory
Citation
Completed/
Proposed/
Upcoming
No existing, proposed, or scheduled MACT standard
Plywood & Composite
Wood Products
Wood Building Products
Polyether Polyols Production
Publicly Owned Treatment
Works (POTW)
Sewage Sludge Incinerators
Fabric, Printing, Coating and
Dyeing
Pharmaceuticals Production
Tire Manufacturing
Secondary Lead
Secondary Brass and Bronze
Aerospace Industry
Rocket Engine Test
Miscellaneous Organic
Chemical Production and
Processes (MON)
Fabric, Printing, Coating and
Dyeing
Taconite Iron Ore Processing
40CFRPart63
Subpart ZZZ
40 CFR Part 63
Subpart QQQQ
40 CFR Part 63
Subpart PPP
40 CFR Part 63
Subpart VW
Rules pending
40 CFR Part 63
Subpart OOOO
40 CFR Part 63
Subpart GGG
40 CFR Part 63
Subpart XXXX
40 CFR Part 63
Subpart RRR
40 CFR Part 63
Subpart SSSS
40 CFR Part 63 Part
GG
Rules not yet proposed
or promulgated
40 CFR Part 63
Subpart FFFF
40 CFR Part 63
Subpart OOOO
Rules not yet proposed
or promulgated
Upcoming
Upcoming
Completed
Completed
Upcoming
Upcoming
Completed
Proposed
Completed
Proposed
Completed
Upcoming
Upcoming
Upcoming
Upcoming
No existing, proposed, or scheduled MACT standard
No existing, proposed, or scheduled MACT standard
Iron & Steel Foundries
40 CFR Part 63
Subpart EEEEE
Upcoming
(continued)
4-25
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March 26, 2001
Chapter 4
Table 4-3. (continued)
SIC (Ranked
by Estimated
Wastewater
Volume
Managed)
3087
3674
3462
3317
2011
3324
2679
3316
3499
3069
3089
3731
SIC Title
Custom compound
purchased resins
Semiconductors and
related devices
Iron and steel
forgings
Steel pipe and tubes
Food and kindred
products (meat
packing)
Steel investment
foundries
Converted paper
products, not
elsewhere classified
Cold finishing of
steel shapes
Fabricating metal
products, not
elsewhere classified
Fabricated rubber
products, not
elsewhere classified
Plastics products,
not elsewhere
classified
Shipbuilding and
repairing
Potentially Applicable MACT
Standard
Regulatory
Citation
Completed/
Proposed/
Upcoming
No existing, proposed, or scheduled MACT standard
Semiconductor Production
40CFRPart63
Subpart BBBB
Upcoming
No existing, proposed, or scheduled MACT standard
Metal Coil (Surface Coating)
Steel Pickling-HCl Process
40CFRPart63
Subpart SSSS
40 CFR Part 63
Subpart CCC
Proposed
Completed
No existing, proposed, or scheduled MACT standard
Iron & Steel Foundries
40 CFR Part 63
Subpart EEEEE
Upcoming
No existing, proposed, or scheduled MACT standard
Metal Coil (Surface Coating)
Metal Coil (Surface Coating)
Metal Furniture (Surface
Coating)
Misc. Metal Parts & Products
(surface coating)
40 CFR Part 63
Subpart SSSS
40 CFR Part 63
Subpart SSSS
40 CFR Part 63
Subpart RRRR
40 CFR Part 63
Subpart MMMM
Proposed
Proposed
Upcoming
Upcoming
No existing, proposed, or scheduled MACT standard
Plastic Parts
(surface coating)
Reinforced Plastics Components
Production
Shipbuilding & Ship repair
Boat Manufacturing
40 CFR Part 63
Subpart PPPP
40 CFR Part 63
Subpart WWWW
40CFR Part 63
Subpart II
40 CFR Part 63
Subpart WW
Upcoming
Upcoming
Completed
Proposed
(continued)
4-26
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March 26, 2001
Chapter 4
Table 4-3. (continued)
SIC (Ranked
by Estimated
Wastewater
Volume
Managed)
3357
3398
2952a
3052a
308P
SIC Title
Nonferrous
wiredrawing &
insulating
Metal heat treating
Asphalt felts and
coatings
Rubber & plastics
hose and belting
Unsupported
plastics film & sheet
Potentially Applicable MACT
Standard
Regulatory
Citation
Completed/
Proposed/
Upcoming
No existing, proposed, or scheduled MACT standard
No existing, proposed, or scheduled MACT standard
Asphalt Roofing and Processing
Plastic Parts
(surface coating)
Metal Coil (Surface Coating)
Plastic Parts
(surface coating)
40 CFR Part 63
Subpart LLLLL
40 CFR Part 63
Subpart PPPP
40 CFR Part 63
Subpart SSSS
40 CFR Part 63
Subpart PPPP
Upcoming
Upcoming
Proposed
Upcoming
1 Survey data not available to adequately quantify wastewater volumes for ranking purposes.
This set of rules is an innovative regulatory effort to address both air and water releases from
pulp and paper mills. The air rule covers MACT I emissions (noncombustion sources from
pulping and bleaching operations at chemical and semichemical wood pulping mills); MACT II
emissions (chemical recovery combustion areas of mills); and MACT HI emissions
(noncombustion sources from mills that mechanically pulp wood, pulp secondary fibers, or pulp
nonwood materials and those that use paper machine additives and solvents). The final water
rule applies to mills in Subpart B (Bleached Papergrade Kraft and Soda) and Subpart E
(Papergrade Sulfite) Subcategories and includes best available technology (BAT) limitations and
Best Management Practice (BMP) requirements. The implementation of the cluster rule will
eliminate the use of chlorine or hypochlorite in the pulp bleaching process or require the facility
to meet the revised effluent limitation guidelines and standards. This rulemaking will also
achieve 99 percent reduction in chloroform in the wastewater discharged.
It is important to note that this industry coverage analysis did not focus on the industry
types that showed potential risks. There were not enough risk exceedances in any one industry
sector that warranted a more detailed industry-specific regulatory analysis. A review of those
industry sectors that did show the potential for risk, however, indicated that the majority of those
industry sectors are, or will be, covered by MACT regulations.
A HAP-emitting facility must first be part of a source category that is subject to a specific
MACT standard in order to be regulated under section 112 of the CAA. If a surface
impoundment emits a HAP but is not part of a listed source category for which there is an
applicable MACT standard, then it is not an affected source subject to MACT requirements.
Situations where nonaffected HAP-emitting sources pose unacceptable risk could thus also be
4-27
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March 26, 2001 Chapter 4
considered a limitation in current MACT requirements, since these types of sources should be
regulated pursuant to section 112. This could potentially occur in two different scenarios.
First, MACT standards may not exist for a source category that emits HAPs (and are not
on the list of upcoming MACT rules). As noted previously, a review of industry sectors that
showed the potential for risk indicated that the majority (but not all) of those industry sectors are,
or will be, covered by MACT regulations. Second, a source category that is covered by an
existing MACT rule may not be considered an affected source if it does not meet the definition of
a major source. A facility emitting HAPs is considered a major source if it emits or has the
potential to emit 10 tons per year or more of any listed HAP or a combination of listed HAPs of
25 tons or more. This study did not investigate what fraction of the facilities that were within the
scope of this study would meet the definition of a major source.
In addition, MACT regulations for each source category do not always address all the
HAPs listed in section 112 of the CAA. For example, the Petroleum Refinery MACT (40 CFR
63 Subpart CC) is limited to organic HAPs as defined by the regulation. The regulation includes
only 28 of the 188 HAPs. In some cases, this occurs because the source category emits only a
subset of CAA HAPs. In other cases, this may have occurred because the best performing
sources were uncontrolled and EPA therefore concluded that the MACT standard for that
pollutant was no control. A recent court decision (National Lime Association v. EPA, 99-1325
(DC Cir)) clarifies that, even if no controls are found to be in use, other means of reduction must
also be evaluated and that MACT represents the performance level of lowest emitting facilities
and a MACT standard must address all HAPs emitted by the industrial category. For the
instances where an unacceptable risk is identified as a result of a constituent of concern in this
study being a HAP but not addressed in an existing MACT regulation, it is assumed that this will
be addressed by the residual risk program. Therefore, for those constituents that are HAPs, there
is not a regulatory gap because the Air Toxics Program should, in time, address HAPs that pose
unacceptable threats to human health.
Other air toxics regulations may achieve some emissions reductions for HAPs.
Section 112(j) contains the MACT "hammer" requirement. This requires facilities and states to
establish MACT equivalent standards should EPA fail to meet congressionally mandated MACT
schedule deadlines. Prior to the 1990 CAA and MACT programs, individual states had a variety
of air toxics programs. Although these programs may control emissions from industrial surface
impoundments, they have not been included in this regulatory/program analyses because these
provisions vary significantly from state to state.
4.2.3.4 Other CAA Coverage—Criteria Air Pollutant Program. We also evaluated
applicability of VOC regulations. All of the 13 constituents of potential concern in this study are
VOCs. As VOCs, the constituents of concern may be regulated indirectly as part of a national
program to reduce ozone. Although VOC regulations have resulted in substantial reductions in
emissions of air toxics, it is important to note that NSPS requirements apply only to new and
newly modified sources. This means that older "grandfathered" sources may not be required to
comply with the standards.
4-28
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March 26, 2001 Chapter 4
NSPS Waste Management Unit and Industry Coverage. There are no NSPS requirements
that directly regulate surface impoundments. However, NSPS regulations that control, for
example, VOCs generated in the manufacturing process and ultimately in the wastewater
generated can serve to limit VOC emissions from surface impoundments that manage such
wastewaters. For example, NSPS Subpart QQQ regulates VOC emissions from petroleum
refinery wastewater systems. Appendix D, Section D-3, lists the in-scope industry sectors and
potentially applicable NSPS VOC standards. The appendix lists several NSPS regulations that
can potentially limit VOC emissions from surface impoundments within the scope of this study
(provided the source has been modified as defined by the NSPS requirements).
Many ozone problems are regional in nature; thus additional VOC requirements may be
in place pursuant to SIPs at the state and local level. There are SIP programs that specifically
regulate surface impoundments; however, control of criteria pollutants under the CAA is based
on local, state, and regional air quality programs and regulations. A detailed analysis of SIPs was
not conducted for this study. EPA may issue guidance, such as control technology guidelines
(CTGs) and alternative control technique guidance (ACTs) for VOC sources, to assist states in
designing control programs to meet local air quality needs. The Office of Air Quality Planning
and Standards developed a CTG in 1993 and released an ACT guidance in 1994 for VOCs in
industrial wastewater.
4.2.3.5 Summary of Potential Regulatory Program Coverage and Gaps in CAA
Regulations. The analysis of potential regulatory gaps under the Clean Air Act examined
constituents of concern and the regulatory applicability under Air Toxics and Criteria Pollutant
Control programs. The analysis looked at regulations that directly control constituents of
concern (e.g., MACT regulations) as well as regulations that indirectly control constituents of
concern (e.g., VOC regulations). This subsection outlines the nature and extent of potential
regulatory/program gaps.
The analysis showed that MACT requirements exist, or will exist, for the majority of the
SIC codes that manage the largest wastewater volume in surface impoundments. The analysis
also indicates that the majority of industry categories that showed the potential for risk were
covered by MACT standards. However, potential exists for a particular source category not to be
covered by a MACT rule. Under the CAA, MACT categories are supposed to include all source
categories that emit HAPs and pose risks to human health. Thus, source categories that emit
HAPs at levels of concern but are not currently regulated, regardless whether they are major or
area sources, are supposed to be regulated when MACT is fully implemented. Section 112(c) of
the CAA gives EPA the authority to list additional source categories that emit HAPs but are not
currently subject to existing or proposed MACT standards.
Another type of gap under this analysis may occur when a MACT standard exists for an
industrial category that exceeds the risk threshold, but does not specifically address surface
impoundments or the constituents of concern that are HAPs. A review of the industry sectors that
showed the potential for risk found two instances in which an industry category was covered by
MACT standards, but the MACT standard did not directly address the HAP constituent of
concern. It must be noted, however, that both of these risk estimates were based on DL values as
opposed to reported concentration values, and both of these constituents would have benefitted
4-29
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March 26, 2001 Chapter 4
from co-control of similar HAPs that are covered by the MACT standard. Thus, it is not clear
that the risks are real, and, if they are, they may well be addressed by the MACT standard.
Regardless, gaps associated with unaddressed HAPs at sources that are covered by MACT
standards should be addressed by the Residual Risk Program.
It must be noted, however, that MACT typically applies only to major sources. Although
major sources account for most of the pollution (e.g., traditionally less than 20 percent of the
sources are considered to emit over 80 percent of the pollution), there is still the potential for
elevated exposure from small sources. The area source program for HAPs is designed to address
this issue. EPA is authorized to develop technology-based standards for area sources when such
sources present a threat of adverse health effects. One important qualification for coverage under
the area source program is that the residual risk program cannot address area sources unless they
have been listed in accordance with section 112(c)(3) and have been included in regulations
under section 112(d).5 This study did not investigate what fraction of the facilities that were
within the scope of this study would meet the definition of a major source.
These limitations are supposed to be addressed when MACT is fully implemented. For
those constituents of concern that are non-HAPs, there are still potential regulatory gaps.
Table 4-1 lists the four constituents of concern that are not regulated as HAPs and show the
potential for elevated risks. They are
• Alpha-hexachlorocyclohexane
• N-Nitrosodi-n-butylamine
• N-Nitrosodiethylamine
• Chlorodibromomethane.
Non-HAP constituents were evaluated to determine if they are regulated as VOCs.
Alpha-hexachlorocyclohexane, Chlorodibromomethane, N-nitrosodi-n-butylamine, and N-
nitrosodiethylamine are VOCs and would potentially be subject to VOC requirements for
wastewater treatment for some NSPS industrial categories. NSPS standards for VOCs only
address new or newly modified sources in certain industrial categories and would not apply to
"grandfathered" sources that had not made modifications that triggered NSPS requirements.
Because the NSPS requirements do not address "grandfathered" sources, there is no certainty that
a regulatory gap would be closed. However, as previously discussed, additional VOC
requirements may be in place pursuant to SIPs at the state and local level.
The likelihood of these four constituents presenting a problem should also be considered.
Risk results for both N-nitrosodi-n-butylamine and N-nitrosodiethylamine were not based on
reported values. This means that concentration values used in the risk assessment were a
function of the detection levels. Both Chlorodibromomethane and alpha-hexachlorocyclohexane
were only detected at one facility each. The limited verification of the hazard posed by these
constituents suggests that any gap is likely to be small.
5 The Residual Risk Program is not required to cover area sources that are subject to GACT rather than
MACT.
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March 26, 2001 Chapter 4
4.3 Coverage and Potential Gaps in Existing Programs and Regulations Addressing
Nonair Risks
Although the EDF consent decree was limited to examining the air risks from never
characteristic wastes in surface impoundments, EPA investigated risks associated with other
media as well in response to the requirements of the LDPFA. In this portion of the analysis, EPA
assessed program and regulatory coverage for
• Risks resulting from consumption of groundwater containing constituents released
from surface impoundments (Section 4.3.1)
• Indirect risks resulting from contaminated groundwater leaching into surface
waterbodies (Section 4.3.2)
• Risks posed via other indirect pathways (Section 4.3.3)
• Ecological risks (Section 4.3.4).
EPA evaluated the extent to which these predicted risks are adequately addressed under
existing federal and state programs.
4.3.1 Groundwater Risks Found from Managing Nonhazardous Waste in Surface
Impoundments
Leachate from a nonhazardous waste surface impoundment can potentially migrate
through the subsurface and affect groundwater quality. Therefore, EPA identified existing
federal and state regulations and programs that address the release of constituents from
nonhazardous waste surface impoundments to groundwater.
In this part of the analysis, EPA used the results of the groundwater risk assessment to
illustrate regulatory coverage and potential gaps. The risk assessment evaluated risks from
specific facilities, constituents, and impoundments resulting from ingestion of groundwater that
had been contaminated with impoundment leachate. The results of the risk assessment indicate
that groundwater contamination from surface impoundments may potentially pose a risk (see also
Section 3.2 for a discussion of groundwater risks). Specifically, the risk assessment identified 15
constituents that potentially exceed the specified risk threshold of this study for the groundwater
pathway.
4.3.1.1 Existing Federal RCRA Regulations and Programs that Control Releases to
Groundwater from Nonhazardous Industrial Waste Surface Impoundments. This section
describes the federal solid waste regulations and programs that may address potential risks to
groundwater posed by the management of nonhazardous wastes in surface impoundments. State
programs are described in Section 4.3.1.2. Federal regulations and programs that address
groundwater risks at nonhazardous waste impoundments include the following:
• RCRA Subtitle C—Corrective Action Program
4-31
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March 26, 2001 Chapter 4
• Omnibus permitting authority under RCRA section 3005(c)(3)
• SEPs conducted in connection with an enforcement action
• RCRA Subtitle D Regulations
• EPA's draft Guide for Industrial Waste Management.
In addition, EPA's multimedia strategy for persistent, bioaccumulative, and toxic (PBT)
pollutants could potentially reduce risks to groundwater from surface impoundments in the
future. EPA's PBT strategy is described in detail in Section 4.4.
Potential regulatory coverage and gaps in these programs, as they pertain to protection of
groundwater at nonhazardous waste surface impoundments, are discussed below.
Potential Coverage by RCRA 7003 and Subtitle C Corrective Action Program. As
described in Section 4.2.1.1, releases from SWMUs can be addressed under the RCRA corrective
action program if a facility has a RCRA permit or is an interim status facility. For facilities with
RCRA permits, the RCRA corrective action program provides extensive regulatory and program
coverage to address any releases to groundwater from nonhazardous waste surface
impoundments that pose unacceptable risks.
Also, as previously discussed, the imminent and substantial endangerment provision of
RCRA section 7003 allows EPA, upon evidence of past or present handling of solid or hazardous
waste, to require any action necessary when a situation may present an imminent and substantial
endangerment to health or the environment.
The survey indicates that about 33 percent of the surface impoundments nationwide that
fall within the scope of this study have been designated as solid waste management units
pursuant to the RCRA corrective action RFA process (see also Chapter 2, Section 2.5 for
additional information on the permit and corrective action status of impoundments within the
scope of this study). This indicates that a significant number of nonhazardous surface
impoundments are located at RCRA TSD facilities; these impoundments are being addressed by
EPA and the states on a priority basis, and thus no regulatory gaps should exist for these
impoundments.
EPA's Permitting Authority under RCRA 3005. EPA's permitting authority under
RCRA 3005 is another statutory control that could be used to address groundwater risks posed by
surface impoundments if they are located at a RCRA TSD facility. See Section 4.3.1.1 for a
detailed explanation of EPA's omnibus permitting authority at RCRA section 3005(c)(3).
Use of SEPs to Address Surface Impoundments at Facilities Subject to Enforcement
Actions. As discussed in Section 4.2.1.5, a SEP is one program that could be used to address
contamination problems found at a nonhazardous waste surface impoundment if the facility is
subject to a related enforcement action. As a condition of the settlement, EPA and the defendant
could agree upon a SEP that is related to reducing groundwater risks posed by a surface
impoundment at the facility. A SEP related to a surface impoundment could include closure,
installation of a liner, or implementation of some other measure that would eliminate or reduce
risk to the environment and/or public health.
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March 26, 2001 Chapter 4
Coverage by RCRA Subtitle D Regulations. RCRA sections 1008(a)(3) and 4004(a)
required EPA to develop criteria for states to use in determining which facilities would be
classified as open dumps and thus be required to be closed or upgraded. EPA promulgated 40
CFR Parts 256 and 257 to partially fulfill the Agency's obligations under the Act. Part 256
establishes guidelines for the states to use in the development and implementation of their solid
waste management plans and includes provisions related to the scope of the plan, the
identification of the responsibilities for state and substate agencies, the requirements for state
legal and regulatory authorities, and planning and implementation. The federal regulations at
Part 257 were EPA's primary mechanism for controlling open dumps prior to promulgation of
municipal solid waste landfill regulations at Part 258. The Part 257 standards provide siting
restrictions, limited performance standards, and references to other applicable federal programs
(e.g., CWA). Table 4-4 is provided in this report for completeness; the regulations have limited
ability to address potential risks, as identified in our study, posed by surface impoundments.
Although the Part 257 regulations typically are administered and enforced by the states, and state
regulations generally are more stringent than the Part 257 regulations, the federal Part 257
regulations may still apply to surface impoundments that are in the scope of this study.
Table 4-4 describes the Part 257 criteria that potentially apply to industrial surface
impoundments.
The regulations that specifically address potential impacts to groundwater are identified
in 40 CFR 257.3-4. This regulation identifies a list of contaminants (appearing at 40 CFR 257
Appendix I) and maximum concentration limits (MCLs) that cannot be exceeded in groundwater.
Table 4-5 compares the risk assessment constituents of concern for the groundwater pathway to
the Part 257 constituent list. Note that the information in the table reflects risk results with
varying levels of certainty. The level of certainty depends, in part, on the extent to which the
results were based on (1) reported concentration values and (2) surrogate data (including DL
values). (See discussion in Chapter 3.) Constituents of possible concern that were reported at
specific concentration values (above the detection limit) are identified in the table. Regulatory
gaps identified based on this information thus carry the same level of varying certainty.
Table 4-5 indicates that only 3 of the 15 constituents potentially exceeding the risk
criteria (flouride, arsenic, and vinyl chloride) are covered under 40 CFR Part 257.3-4. Thus,
coverage of the constituents of potential concern for groundwater risks must be provided by other
programs such as state programs (see Section 4.3.1.2) or EPA's voluntary draft Guide for
Industrial Waste Management. Two of the potential constituents of concern (allyl alcohol and
flouride) are not covered by the draft guidance. Allyl alcohol is not covered by either 40 CFR
Part 257.3-4 or the draft guidance. The groundwater tool in the draft guidance allows the user to
enter additional constituents that are not specifically listed in the guidance. Because the guidance
is in draft form, the constituent list may change in the future.
Description of EPA's Draft Guide for Industrial Waste Management as It Relates to
Coverage of the Groundwater Pathway. EPA's draft Guide for Industrial Waste Management
(U.S. EPA, 1999a) includes three categories of groundwater protection guidelines: risk
assessment, liner design and installation, and long-term operations. See Section 4.2.1.3 for a
more generalized description of the draft guide.
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Chapter 4
Table 4-4. Summary of 40 CFR Part 257 Criteria That Potentially Apply to Surface
Impoundments
Regulatory Citation
§257.3-1 Floodplains
§257.3-2 Endangered
or Threatened Species
§257.3-3
Surface Water
§257.3-4 Groundwater
Protection
§257.3-7
Air
§257.3-8
Safety
Summary of Requirement
Facilities located in the 100-year floodplain must not restrict the flow of the
flood, reduce water storage of the floodplain, or result in a washout of solid
waste.
Facilities must not cause or contribute to the taking of endangered or
threatened species nor destroy or adversely modify their critical habitat.
Facilities must not cause a discharge of pollutants or dredged or fill material
in violation of the requirements of the Clean Water Act or cause nonpoint
source pollution that violates an area or statewide water quality
management plan under the Clean Water Act.
Facilities must not contaminate underground drinking water sources beyond
the solid waste boundary unless it can be shown that an alternative
boundary would not result in the contamination of water that may be needed
for human consumption.
Facilities must not engage in the open burning of waste unless it is the
infrequent burning of agricultural wastes in the field, silvicultural wastes for
forest management purposes, land-clearing debris, diseased trees, debris
from emergency cleanup operations, and ordinance and must not violate
requirements developed under a State Implementation Plan under the Clean
Air Act.
Facilities must not generate high concentrations of explosive gases, pose a
fire hazard, be located within 10,000 feet of a jet aircraft runway or 5,000
feet of a piston-type aircraft runway, or allow uncontrolled public access.
Assessing Risk. Chapter 7a of the draft guide provides a tool for assessing risks
associated with waste management practices and for tailoring management
controls accordingly. The guidance employs a three-tiered evaluation approach to
determine recommended liner systems and whether land application is
appropriate. The chapter is intended for use at new units.
Designing and Installing Liners. Chapter 7b of the draft guide discusses
different types of liner systems that can be used to protect groundwater from
contamination. Liner recommendations may include clay liners, synthetic liners,
composite liners, leachate collection systems, and leak detection systems as
appropriate. The chapter is intended for use at new units.
Long-Term Operation. Chapter 9 of the draft guide includes recommendations
for groundwater monitoring, Chapter 10 includes guidance on taking corrective
action, and Chapter 11 provides guidance on closure/postclosure care. While the
draft guide focuses primarily on new units, information in these chapters can be
applied to existing industrial waste units.
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Chapter 4
Table 4-5. Federal Regulatory or Program Coverage of Constituents with Predicted Risks
Exceeding Risk Criteria for Groundwater Pathway
CAS Number
107-13-1
107-18-6
110-86-1
16984-48-8
621-64-7
62-75-9
67-56-1
67-64-1
67-66-3
7440-28-0
7440-38-2
75-09-2
75-01-4
8001-35-2
92-87-5
Constituent
Acrylonitrile a
Allyl alcohol a
Pyridine a
Fluoride a'b
N-Nitrosodi-n-propylamine [di-n-
propylnitrosamine] a
N-Nitrosodimethylamine a
Methanol a
Acetone [2-propanone] a>b
Chloroform [trichloromethane] a
Thallium a
Arsenic a
Methylene chloride [dichloromethane] a
Vinyl chloride a
Toluene a
Benzidine a
40 CFR Part 257
Constituent
•
•
•
Guide for Industrial
Waste Management
Constituent
•
•
•
•
•
•
•
•
•
•
•
•
•
a Risk estimate was based on surrogate or detection limit value.
b Risk estimate was based on a reported waste concentration.
Note: Bold indicates the constituent is not specifically addressed by either program.
Corrective action can include use of interim measures, institutional controls (such as deed
restrictions or access controls), and application of remedial technologies designed to contain,
remove, and/or destroy contamination.
4.3.1.2 Existing State Regulations and Programs that Control Releases to Groundwater
at Nonhazardous Waste Surface Impoundments. States typically regulate nonhazardous waste
surface impoundments under their more general solid and industrial waste management
regulations for nonhazardous waste or pursuant to their water programs. This section provides an
overview of state regulations that are applicable to nonhazardous waste management in general
or nonhazardous waste surface impoundments in particular. The following types of state
programs and regulations may address potential groundwater risks from in-scope surface
impoundments:
• States may have regulations or programs addressing the groundwater pathway,
such as monitoring or unit design requirements.
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March 26, 2001 Chapter 4
• A facility may have a permit for the surface impoundment issued by the state that
addresses potential groundwater risks.
• States may make specific exclusions to their requirements for certain facilities.
Such facilities, therefore, would not be subject to otherwise stricter state
requirements.
Key Components of State Regulations and Programs that Address Releases to
Groundwater at Nonhazardous Waste Surface Impoundments. Based on available
information, most states have a program that includes provisions for controlling or addressing
releases to groundwater from industrial nonhazardous waste surface impoundments (see
Appendix D, Section D-l). The level of controls, however, varies across states. Many
provisions are not formally adopted regulations; rather, they are imposed through permits, on a
case-by-case basis at the discretion of the regulators, or via nonmandatory guidance. Note that
EPA's analysis of state waste regulations and programs in Appendix D is based on publicly
available information rather than on a survey of state regulators. Therefore, the analysis may not
have identified all state waste regulations and programs that address nonhazardous waste
industrial surface impoundments.
State programs may include some or all of the following key components, many of which
are for the protection of groundwater:
• Location standards. Location standards generally address both potential effects a
waste management unit may have on the surrounding environments and the effect
that natural and man-made conditions may have on the performance of the unit.
Location standards may include provisions such as airport safety; restrictions on
placement of a unit in flood plains and wetlands; and design, construction, or
siting requirements for placement in a fault area, seismic impact zone, or unstable
areas. Note that the federal Part 257 location restrictions apply in all states and
territories, even if such restrictions are not covered by state regulations.
• Design criteria. Design criteria typically include design standards for liners and
leachate collection or performance standards for maintaining contaminant
concentrations in groundwater at protective levels at a point of compliance.
• Operating criteria. State programs for nonhazardous waste surface
impoundments may include criteria pertaining to routine operation, management,
and environmental monitoring. Operating criteria may include provisions for
preventing disposal of hazardous or special waste, access and security, stormwater
runon/runoff controls, freeboard requirements, nuisance controls, inspection, and
reporting and recordkeeping.
• Monitoring. Monitoring programs may be required to evaluate whether a unit
meets performance objectives and whether there are releases of constituents to and
impacts on the surrounding environment that need to be corrected. Monitoring
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Chapter 4
requirements typically emphasize groundwater monitoring; however, states may
require monitoring of air, surface water, and sludge or soil.
• Corrective action. If monitoring indicates that performance objectives are not
being met, then a state program may require corrective measures. Under a
remedial program, a facility may be required to assess the nature and extent of the
releases of waste or constituents; to evaluate unit characteristics; and to identify,
evaluate, and implement an appropriate corrective measure or measures to protect
human health.
• Closure andpostclosure care. A state may have requirements for unit closure to
minimize or eliminate potential threats and the need for future corrective action at
a site. Closure measures may include removal of wastewater, treatment of wastes,
and/or containment. For postclosure care, the overall goal is to minimize the
infiltration of water into a unit after closure by providing maintenance of the final
cover until such time as it is determined that care is no longer necessary.
Figure 4-1 summarizes the number of states that have various programs in place for the
protection of groundwater at nonhazardous industrial waste surface impoundments. A
comprehensive summary of state waste regulations applicable to nonhazardous waste surface
impoundments is included in Appendix D, Section D-l.
Location Standards
Design Criteria
Operating Criteria
Monitoring
Reporting and Recordkeeping
Inspection and Enforcement
Performance Standards/Corrective
Action
Closure/Post-Closure Care
24
24
18-
24
22
25;
12
13
29
45'
0 5
!27
19
24
24
Number of States
H State Program or Regulation
El Addressed on a Case-By-Case or Discretionary Basis
DNo Requirement/Program, or Undetermined
Figure 4-1. State programs or regulations for the protection of groundwater at
nonhazardous waste surface impoundments.
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March 26, 2001 Chapter 4
In conclusion, many, but not all, states have regulatory or other programs in place
designed to address groundwater risks posed by nonhazardous waste surface impoundments.
While these programs provide an important level of protection, they do not, at least by regulation,
address all potential releases of concern.
4.3.1.3 Existing Programs Under the Safe Drinking Water Act that Address Releases to
Groundwater from Surface Impoundments. Programs under the SDWA Amendments of 1996
also provide coverage at the national level and state level.
To determine the susceptibility of all public water supplies in the nation through source
water assessments, EPA published guidance for state source water assessment and protection
programs in 1997, under section 1453 of the SDWA. Each state, using the national guidance and
funding under the Drinking Water State Revolving Fund (SRF) (section 1452 of the SDWA),
developed and has started to implement a Source Water Assessment Program (SWAP) approved
by EPA. Each SWAP includes delineation or mapping of the areas around drinking water
sources, an inventory of potential contamination sources (such as Class 5 wells, landfills, surface
impoundments), assessment of risks or likelihood of contamination, and reports to the public.
While SWAPs do not control releases to groundwater or provide for remediation of any releases,
they are part of EPA's overall strategy, Source Water Contamination Prevention.
Nationally, by the end of 2003, all 170,000 public water systems should have a completed
assessment showing their relative susceptibility to potential sources of contamination, including
surface impoundments. To the extent a surface impoundment is in a delineated source water
protection area geospatially mapped by a state, it will be part of an assessment. Whether or not
an impoundment is mapped and determined to be a significant potential source of contamination
for a water supply depends on the factual situation for any such water supply and the approved
state methodology for determining a public water system's susceptibility.
In addition, 49 states are implementing EPA-approved Wellhead Protection Programs
(WHP) under section 1428 of the Safe Drinking Water Act to protect public water wells from
identified potential sources of contamination. While many states do not require local
governments and public water systems to develop and implement these programs, about
6,000 public water systems as of September 30, 1999, are in communities where some
management measures have been implemented to protect the systems (measures could be
nonregulatory or regulatory).
Also, the Groundwater Report to Congress in October 1999 (U.S. EPA, 1999e), required
by section 1429 of the SDWA, reported that every state is "undertaking some component of a
comprehensive groundwater protection program, including enacting protection legislation and
regulations, coordinating activities of various agencies responsible for groundwater management,
performing groundwater mapping and classification, monitoring ambient quality, developing data
management systems, and implementing remediation and prevention programs." Although the
report pointed out that there are many sources threatening groundwater contamination, there were
no national data ranking sources from more to less threatening.
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March 26, 2001 Chapter 4
In the 1998 National Water Quality Inventory, Report to Congress (U.S. EPA, 2000c)
requested by Clean Water Act section 305(b), states report the major sources of groundwater
contamination in their states. Nineteen states reported that surface impoundments ranked only
ninth as a contamination source of groundwater. Potential sources of contamination that were
reported to be more prevalent than surface impoundments were underground storage tanks, septic
systems, landfills, large industrial facilities, fertilizer applications, spills, pesticide applications,
and hazardous waste sites.
4.3.2 Risks to Surface Water from Releases of Contaminated Groundwater to Surface Water
EPA evaluated the potential for risks and performed an indirect exposure pathway
screening analysis and quantitative modeling to estimate risks from surface water contaminated
by releases from groundwater to surface water (see also Section 3.3).
By design, surface impoundments are often located near receiving waterbodies.
Impoundments designed for final treatment are intended to produce effluent that meets regulatory
standards (e.g., NPDES) and, therefore, discharges directly into the waterbody. Many
impoundments, however, are designed as part of a treatment train and are not intended to produce
effluent of sufficient quality to meet regulatory standards. Although these impoundments do not
discharge directly to surface water, chemicals may be released through the bottom or sides of the
impoundment, travel through the subsurface, and adversely impact the quality of nearby
waterbodies.
The risk analysis identified 35 constituents of concern for the groundwater to surface
water pathway. Of the 35 constituents estimated to pose potential risks to surface water from
groundwater releases, five are regulated under 40 CFR Part 257 as constituents whose
concentrations must not exceed MCLs in groundwater. Thirty-one of the constituents are
addressed in EPA's draft Guide for Industrial Waste Management. Only two constituents of
concern are not addressed by either program. These constituents are dibenz[a,h]anthracene and
1,2-diphenylhydrazine. The 35 constituents and their program coverage by 40 CFR Part 257
regulations and EPA draft Guide for Industrial Waste Management are presented in Table 4-6.
Note that the information in the table reflects risk results with varying levels of certainty.
The level of certainty depends, in part, on the extent to which the results were based on
(1) reported concentration values and (2) surrogate data (including DL values). (See discussion
in Chapter 3.) Constituents of possible concern that were reported at specific concentration
values (above the detection limit) are identified in the table. Regulatory gaps identified based on
this information thus carry the same level of varying certainty.
Regulations and programs designed to control releases to groundwater or to address
groundwater contamination at or near a unit's boundary (as discussed previously in Section
4.3.1) should, in turn, control any potential releases from groundwater to downgradient surface
water. Based on research of federal and state regulations, there do not appear to be any
programs or requirements specifically intended to control releases from groundwater to surface
water. EPA's longstanding interpretation of the Clean Water Act, however, is that the discharge
of a pollutant from a point source to a navigable water via groundwater that has a direct
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Chapter 4
Table 4-6. Federal Regulatory or Program Coverage of Constituents with Predicted Risks
Exceeding the Risk Criteria for Groundwater to Surface Water Releases
Constituent
Arsenic a>b
Thallium a'b
Acrylonitrile a
Aldrin a
Antimony a
Benzidine a
Benzo(a)anthracene [benz[a]anthracene] a
Benzo(a)pyrene a
Benzo(b)fluoranthene a
Bis(2-chlororethyl)ether a
Carbon tetrachloride a
Chlordane a
Chlorodibromomethane a
Chrysene a
4,4-DDD a
4,4-DDE a
4,4-DDT a
Dibenz[a,h] anthracene a
3,3-Dichlorobenzidine a
1,2-Dichloroethane a
1 , 1 -Dichloroethylene a
Dieldrin a
2,4-Dinitrotoluene a
1,2-Diphenylhydrazine a
Heptachlor a
Heptachlor epoxide a
Hexachlorobenzene a
Hexachlorobutadiene [hexachloro-l,3-butadiene] a
Ideno (1,2,3-cd) pyrene a
Pentachlorophenol a
PCBsa
1 , 1 ,2,2-Tetrachloroethane a
Toxaphene a
N-Nitrosodimethylamine a
N-Nitrosodi-n-propylamine a
40 CFR Part 257
Constituent
•
•
•
•
•
Guide for Industrial
Waste Management
Constituent
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
a Risk estimate was based on surrogate or detection limit value.
b Risk estimate was based on a reported waste concentration.
Note: Bold indicates the constituent is not specifically addressed by either program.
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March 26, 2001 Chapter 4
hydrologic connection to that water is subject to regulation under the NPDES. EPA and states
with authorized NPDES programs have issued permits addressing the discharge or potential
discharge of pollutants to surface water via hydrologically connected groundwater to a number of
facilities including those involved in
Concentrated animal feeding operations (CAFOs)
Waste disposal
Site remediation
Mining
Petroleum refining
Aircraft production.
In those cases where these facilities may impact a waterbody not meeting state water quality
standards, their impacts could be addressed through the Total Maximum Daily Load (TMDL)
program.
Also, EPA has recently proposed that CAFOs that discharge or have the potential to
discharge wastes to navigable waters via groundwater with a direct hydrologic connection must
apply for an NPDES permit. See, generally, 66 FR 2960, 3015-3020, 3138, and 3144
(January 12, 2001).
4.3.3 Risks Associated with Other Indirect Pathways
The risk assessment evaluated indirect pathways other than the groundwater to surface
water pathway. This involved numerically ranking facilities that manage bioaccumulative
chemicals based on criteria relevant to release, transport, and exposure to farmers, home
gardeners, and fishers (see also Section 3.4 in Chapter 3). The release scenarios considered
included volatilization of constituents from wastewater and particulate entrainment or erosion of
constituents from exposed sludge. In addition, the possibility that postclosure exposures could
occur through any of these release scenarios was also considered.
To address postclosure exposure to sludge, the regulatory/program coverage and gaps
analysis focused on federal and state programs and regulations that address closure and post-
closure care requirements for nonhazardous waste surface impoundments (see Section 4.3.3.1).
The analysis also evaluated CWA programs that can address erosion and runoff (see Section
4.3.3.2). Program coverage for air deposition indirect pathway risks is identical to programs
discussed in Section 4.2.
4.3.3.1 Programs That Address Closure and Postclosure Care of Nonhazardous Waste
Surface Impoundments. The RCRA corrective action program and EPA's draft Guide for
Industrial Waste Management (U.S. EPA, 1999a) are two federal programs that may be used to
address closure and postclosure care of nonhazardous waste surface impoundments. Note that
the Subtitle D regulations at 40 CFR Part 257 (Subpart A) addressing solid waste disposal units
do not address closure and postclosure care. In addition, closure of nonhazardous waste
impoundments also could be addressed under various state programs, as voluntary actions, or
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March 26, 2001 Chapter 4
under the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA), commonly known as Superfund.
RCRA Corrective Action. As discussed previously, the RCRA corrective action
program provides authorized states or the EPA Regions with the authority to address potential
risks from nonhazardous waste surface impoundments located at TSDFs. This provides a
regulatory mechanism to address any risks that may be posed by sludge left in place after closure.
Draft Guide for Industrial Waste Management. As discussed previously, EPA has
developed the draft Guide for Industrial Waste Management (U.S. EPA, 1999a) to address
multiple aspects of industrial waste management in land-based units. The guide, as currently
drafted, includes detailed information on closure and postclosure care of nonhazardous waste
surface impoundments. The document currently includes guidance on
Developing a closure plan
Selecting a closure method
Closure by use of a final cover system
Closure by waste removal
Postclosure care monitoring and financial assurance.
Implementation of the practices recommended in the guidance, when finalized, would
provide substantial reduction in potential risks associated with sludges left in place after closure
of a nonhazardous waste surface impoundment.
State Programs. State regulations and programs relevant to closure and postclosure care
typically address potential risks posed by exposure to sludge after closure of an impoundment.
Based on available information, approximately 26 states have regulations that address closure
and postclosure care of nonhazardous waste surface impoundments.
4.3.3.2 CWA Coverage of Erosion/Runoff of Sludges. Once a surface impoundment is
closed, the sludge left in the impoundment may contain significant concentrations of chemical
contaminants. In some cases, impoundments may be completely filled (or nearly so) with sludge
upon closure. If the impoundment sludge is not capped following closure (perhaps pursuant to
the previously discussed programs), the potential for runoff and erosion of contaminated sludge
particles exists.
EPA's NPDES Program for Storm Water Discharges Associated with Industrial Activity
may provide a regulatory mechanism by which erosion/runoff of contaminated sludge particles
can be controlled. Under 40 CFR Part 122.26, EPA or authorized states regulate storm water
discharges associated with a variety of industrial activities, including discharges associated with
those activities from the portions of such "sites used for residual treatment, storage, or disposal"
including surface impoundments.
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March 26, 2001 Chapter 4
4.3.4 Ecological Risks
Federal regulations applicable to nonhazardous waste surface impoundments that may
reduce risks posed to ecological receptors include the provisions at 40 CFR Part 257.3-2 for the
protection of endangered or threatened species and critical habitats at nonhazardous waste
disposal facilities. For facilities that have or are seeking RCRA permits, clearly identified
ecological risks may be addressed under the RCRA corrective action program. In addition, the
imminent and substantial endangerment provision of RCRA section 7003, allows EPA, upon
evidence of past or present handling of solid or hazardous waste, to require any action necessary
when a situation may present an imminent and substantial endangerment to health or the
environment. This authority applies to all facilities, whether or not they have a RCRA permit, in
those specific situations where the statutory threshold is met.
Approximately 26 of 50 states have siting requirements to prevent adverse effects on
endangered or threatened species from surface impoundments.
In addition, EPA's draft Guide for Industrial Waste Management suggests buffer zones to
help prevent the destruction or adverse modification of a critical habitat and minimize harm to
endangered or threatened species. The guidance also indicates the need to check with state and
local officials in the area to determine if buffer zones are required for industrial waste
management units.
4.4 Role of EPA's Multimedia Strategy for PBT Pollutants in Reducing Risks from
Surface Impoundments
EPA has a multimedia strategy in place to address the challenges associated with priority
persistent, bioaccumulative, and toxic pollutants in the environment. The purpose is to create a
mechanism that will enable EPA to better address the cross-media issues associated with
reducing priority PBT pollutants in the environment. PBT chemicals pose risks because they are
toxic, persist in ecosystems, and accumulate in fish and other organisms.
A set of 12 chemicals is the initial focus of EPA's PBT Strategy. These pollutants are the
Level 1 chemicals identified in the United States - Canada Binational Toxicity Strategy (BNS).
It is these chemicals, listed in Table 4-7, that are the subject of national action plans, currently in
various stages of development. When priority PBTs are selected for the development of national
action plans, a comprehensive analysis is conducted to identify, among other things, chemical
characteristics, release patterns, uses, sources, multimedia fate and transport, geographic hot
spots, sensitive populations, and impacts to human health and the environment. A pesticide
action plan will cover aldrin/dieldrin, chlordane, DDT (DDE, DDD), mirex, and toxaphene.
Table 4-7 indicates that, out of the 12 priority PBT chemicals, eight showed the potential
for risk for one or more pathways. No groundwater risks were predicted for any of the PBT
chemicals listed in the table. Note that all predicted risks for these listed chemicals were based
on detection limit/surrogate data, not reported concentrations.
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Chapter 4
Table 4-7. List of Priority PBT Chemicals and Extent to Which They Showed
Potential for Risk
Level 1 PBT Chemicals
CAS Number
309-00-2/60-57-1
50-32-8
57-74-9
50-29-3 (72-54-8 & 72-55-9)
110-00-9
118-74-1
7439.97.6
2385-85-5
29082-74-4
1336-36-3
8001-35-2
Chemical Name
Aldrin/dieldrin b
Alkyl-lead
Benzo(a)pyrene
Chlordane
DDT (ODD & DDE)b
Dioxins and furans
Hexachl orob enzene
Mercury and its
compounds
Mirex
Octochlorostyrene
PCBs
Toxaphene
Potential Risk Predicted for
One or More Pathways?
Yes (gw-sw)a
Not evaluated
Yes (gw-sw)
Yes (gw-sw)
Yes (gw-sw)
Yes (gw-sw, air)a
Yes (gw-sw)
No
Not evaluated
Not evaluated
Yes (gw-sw)
Yes (gw-sw, air)
a "Air" and "gw-sw" (groundwater to surface water) indicate the pathways for which risks were predicted for the
identified PBT chemical.
b PBT chemicals listed together, such as aldrin/dieldrin and DDT (DDD&DDE), are listed separately on the Surface
Impoundment Study list of constituents.
The Surface Impoundment Study seeks to evaluate the risks posed by managing
wastewaters in surface impoundments and to determine whether existing state or federal
programs adequately address those risks. If, through the action plan development process, EPA
decides to address PBT risks through any of the various regulatory and nonregulatory
mechanisms that are appropriate, any subsequent reductions to the generation of PBT pollutants
can, in turn, reduce the quantity of PBT chemicals sent to surface impoundment units, thereby
indirectly reducing risk from this source.
References
ASTSWMO (Association of State and Territorial Solid Waste Management Officials). 1996.
Non-Municipal, Subtitle D Waste Survey. Washington, DC.
Environmental Information, Ltd. 1996. Nonhazardous Industrial Surface Impoundments, State
Regulations and the Environmental Marketplace. Minneapolis, MN.
Environmental Law Institute. 1998. An Analysis of State Superfund Programs: 50 State Study,
1998 Update. EPA 540-R-98-046, OSWER 9375.6-08E. Washington, DC.
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ICF, Inc. 1993. Study of State Industrial Non-Hazardous Waste Regulatory Programs - 25 State
Profiles. Submitted to the Chemical Manufacturers Association.
U.S. District Court for the District of Columbia. Environmental Defense Fund, Inc. v. Whitman,
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U.S. EPA (Environmental Protection Agency). 1995a. State Requirements for Industrial Non-
Hazardous Waste Management Facilities. Fourth draft. Office of Solid Waste,
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U.S. EPA (Environmental Protection Agency). 1998. Air Characteristics Study, Volume I,
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U.S. EPA (Environmental Protection Agency). 1999a. A Guide for Industrial Waste
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Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1999c. Residual Risk, Report to Congress.
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Enforcement and Compliance Assurance.
U.S. EPA (Environmental Protection Agency). 1999e. Safe Drinking Water Act, Section 1429,
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Government Printing Office.
U.S. EPA (Environmental Protection Agency). 2000a. Surface Impoundment Study Technical
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Park, NC.
U.S. EPA (Environmental Protection Agency). 2000b. Supplemental Environmental Projects.
EPA-300-B-00-007. Washington, DC: U.S. Government Printing Office.
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U.S. EPA (Environmental Protection Agency). 2000c. National Water Quality Inventory: 1998
Report to Congress. EPA 841-R-00-001. Washington, DC: U.S. Government Printing
Office.
U.S. EPA (Environmental Protection Agency). 2001. Beyond Compliance: Supplemental
Environmental Projects. EPA 325-R-01-001. Washington, DC: U.S. Government
Printing Office.
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Chapter 5
Summary and Conclusions
5.1 Scope of Surface Impoundment Study
This study is of industrial surface impoundments located in the United States that
operated during the 1990s and managed nonhazardous wastes. This study does not address
management of hazardous wastes in surface impoundments. For this study, the term "industrial"
refers to manufacturing, chemical and petroleum storage, waste management, transportation, and
national security activities. The term "surface impoundment" means a natural topographic
depression, artificial excavation, or diked arrangement for storing, treating, or disposing of
wastewater. It may be constructed above ground, below ground, or partly above and partly below
ground.
5.2 SIS Requirements
EPA undertook this study to satisfy two separate requirements: (1) a consent decree
between EPA and the Environmental Defense Fund (EDF) resulting from EDF vs. Whitman,
D.C. Circuit, 89-0598; and (2) the March 26, 1996, amendment to the Solid Waste Disposal Act
(see section 3004(g)(10)), also known as the Land Disposal Program Flexibility Act of 1996
(LDPFA). These requirements are described in detail in Chapter 1.
5.3 Survey and Risk Assessment Findings
5.3.1 Survey of Industrial Impoundments
Chapter 2 of this report discusses the findings of the survey of industrial impoundments.
EPA's best estimate is that no more than two-thirds of the 18,000 industrial impoundments in the
United States contain one or more of the chemical constituents that were of interest for this study
or contain either high (11-12.5) or low (2-3) pH wastewater. More than half of the impound-
ments with chemical constituents or pH of interest are in the chemical, concrete, paper, and
petroleum industries.
Industrial impoundments vary greatly in size, from less than a quarter hectare to several
hundred hectares. The larger impoundments form the bulk of the total national industrial
impoundment capacity. On a volume basis, the paper and allied products sector manages roughly
two-thirds of the total quantity of wastewater—this represents more wastewater than all
categories combined.
Industrial impoundments frequently use management techniques that increase the
potential for chemical releases and frequently are found in environmental settings that increase
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the potential for impacts to humans or ecosystems in the event of a chemical release. For
example, in this study, EPA found that most industrial impoundments are located only a few
meters above groundwater and that, in most cases, shallow groundwater discharges to a nearby
surface waterbody. More than half of the impoundments do not have liner systems to prevent
releases of wastes to soil or groundwater.
There is also significant potential for people to be exposed to chemical constituents
released from industrial impoundments. EPA estimates that 20 million people live within 2
kilometers (about 1.2 miles) of an industrial impoundment that was in operation during the
1990s. Additionally, about 10 percent of impoundments have a drinking water well located
within 150 meters of the impoundment's edge.
5.3.2 Risk Assessment
This section summarizes key findings of the risk assessment, which included a risk
analysis quantifying risks associated with exposure to contaminated groundwater, air, and surface
water and a risk screening ranking the risks associated with indirect pathways and ecological
threats. This discussion also highlights findings that address the statutory requirements for the
scope of the study. A detailed discussion of the risk screening and risk analysis is included in
Chapter 3 of this report.
The analysis to characterize potential risks posed by surface impoundments was based on
a tiered approach designed to screen the large number of constituents and impoundments in order
to focus subsequent analysis. The first stage of this tiered approach was an initial screening
based on very protective exposure assumptions; subsequent stages increased the level of realism
through the use of increasing levels of facility-specific data, screening-level models, and site-
based models. At each stage in the analysis, EPA was able to identify combinations of facility,
impoundment, and chemical that did not require further analysis. Given the design of the overall
approach-proceeding from a very protective exposure scenario to a realistic exposure
scenario-EPA is confident that combinations that were omitted from further consideration, or
screened out, do not pose significant risks to human health or the environment.
The risk estimates developed in this study for human health and the screening conducted
for ecological risks are based on an extensive analysis of the survey data reported for a wide array
of chemicals and impoundments of potential concern. While there are elements of uncertainty in
this analysis, EPA has increased confidence in the results by emphasizing those risk findings that
are based on concentration data reported in the survey as being above a limit of detection.
Our major risk analysis findings, as they apply to the 11,900 surface impoundments
containing constituents or exhibiting a pH within the scope of this study, can be summarized as
follows:
• Most facilities and impoundments nationally do not appear to pose risks to human
health or environmental releases of concern.
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• Twenty-one percent of facilities nationally—corresponding to 24 percent of
impoundments—have the potential for environmental releases above health-based
levels to occur from impoundments. While these releases do not appear to pose
risk to human health (because of limited exposure), the results do indicate that, at
these facilities, selected contaminants have the potential to move beyond the
surface impoundment confines and through the environment in excess of health-
based levels.
• Five percent of facilities nationally, corresponding to 2 percent of impoundments,
may pose potential risks by at least one pathway.
• For 23 percent of impoundments and facilities, EPA was not able to estimate
potential risks with confidence because the chemical concentration data were
based on inferred or detection-limit data.
Our major risk screening findings for the in-scope surface impoundments can be
summarized as follows:
• Based on a screening analysis and protective assumptions, 6 percent of facilities
nationally may pose potential concerns through indirect pathways such as
contamination of croplands.
• Based on a screening analysis and protective assumptions, 29 percent of facilities
nationally may pose potential localized ecological impacts to receptors that
inhabit the impoundment area or the nearby areas affected by undiluted
impoundment runoff.
EPA also examined potential risks according to whether wastewaters are decharacterized
or never characterized and according to their discharge status. This examination was to address
the requirement of the 1996 LDPFA that EPA assess decharacterized wastewaters that are
managed in surface impoundments under the scope of the Clean Water Act. The findings may be
summarized as follows:
• Only about 20 percent of impoundments manage decharacterized wastewaters.
Because of this, a relatively small number of the total potential risk exceedances
or environmental releases are attributable to decharacterized wastes. However,
the rates of risk exceedances and releases generally are higher for decharacterized
than for never characterized wastes.
• There are relatively few zero dischargers compared to direct dischargers. For
certain pathways, notably the groundwater to surface water pathway, the zero
dischargers have a higher rate of potential risk exceedances and environmental
releases.
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5.4 Regulatory Analysis Findings
As is discussed in detail in Chapter 4, EPA performed a regulatory and program analysis
specific to each risk pathway. For the air pathway, EPA conducted a generic program analysis
and then a more detailed analysis based on the constituents that showed the potential for risk.
Programs that were analyzed include: Clean Air Act (e.g., MACT, residual risk, NSPS), RCRA
(e.g., corrective action, permitting, solid waste program), and state regulations and programs.
Similarly, for the groundwater and surface water pathways, EPA conducted a RCRA coverage
analysis, a review of state programs, and a review of the Clean Water Act and Safe Drinking
Water Act.
5.4.1 Air Pathway Regulatory Analysis
5.4.1.1 Summary of Clean Air Act Coverage. As discussed in previous chapters, the risk
analysis showed with that, with relatively few exceptions, the impoundments in the scope of the
study do not pose risks from air emissions.
The primary regulatory program that addresses potential air risks from industrial surface
impoundments is the CAA NESHAP program. Our regulatory analysis found that MACT
requirements exist, or will exist, for the majority of industries managing the largest estimated
wastewater volume in surface impoundments. Also, a review of the industry sectors that showed
the potential for risk did show that the majority, but not all, of the industry sectors are covered by
MACT regulations or will be covered by upcoming MACT standards. Further, most of the
pollutants that may cause concern are hazardous air pollutants. EPA recognizes that some of
these NESHAP rules have not yet reached their compliance dates, so some releases identified in
these findings reflect the preregulatory status. Also, the NESHAPs issued after 1990 CAA
(commonly referred to as MACT standards) are technology based and, therefore, may not
completely restrict releases to levels below the EPA identified risk level. However, under the
Clean Air Act, sources subject to MACT standards must be evaluated to determine if "residual
risk" remains; if so, additional controls may be imposed.
The study also found that most industry-level NESHAPs do not directly address surface
impoundments. A few industry NESHAPs require covers on surface impoundments only if
wastewater exceeds a certain threshold concentration value for particular constituents (e.g.,
benzene loading, total organic concentration). Generally, however, most NESHAP standards
tend to focus on HAP levels in the wastewater generated in the production process, which
eventually could be treated/stored in the surface impoundment unit (e.g., MACT standards may
control wastewater concentration HAP levels as opposed to requiring emission controls, such as
a cover, on surface impoundments). However, when a technology standard addresses and reduces
or removes pollutants upstream of the surface impoundment, this reduces the load entering the
impoundment and, ultimately, emitted to the environment.
5.4.1.2 Possible Limitations in Air Regulatory Coverage. Even though coverage of the
air pathway is fairly complete, coverage may not address all surface impoundments in all
situations (i.e., in different industries or with different pollutants of concern). Current limitations
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March 26, 2001 Chapter 5
in regulatory coverage may include situations in which a source category is not covered and,
therefore, is not subject to a NESHAP. If an industry is not listed as a source category under
section 112 of the CAA, the source would not be subject to a NESHAP or, therefore, a residual
risk analysis. As explained previously, this situation is the exception based on the results of this
survey and risk analysis.
Another potential gap in coverage is the limited situation in which pollutants of concern
are not HAPs. As discussed in Chapter 3, this study suggested only four non-HAP constituents
that potentially exceed risk thresholds. It should be noted that there are uncertainties with the
identification of a regulatory gap for these four constituents. Risk results for two of the four
constituents were not based on reported values; that is, the concentration values used in the risk
assessment were a function of the detection levels. Clearly, the other two constituents were
detected at only one facility each. The limited verification of the hazard posed by these
constituents suggests that any gap is likely to be small. Furthermore, non-HAPs that cannot be
addressed directly with NESHAPs and subsequent residual risk determinations still may be
indirectly "co-controlled" through use of pollution abatement technologies for other, similar
HAPs.
Another type of existing CAA limitation may occur when a MACT rule exists for an
industrial category that exceeds the risk threshold, but the MACT rule does not directly address
surface impoundment emissions or the risky constituents of concern that are HAPs. As discussed
previously, MACT rules typically address the emissions of HAPs generated facility-wide;
therefore, few MACT rules require air emission controls specifically for the surface
impoundment. Also, based on a review of the industry sectors that showed the potential for risk,
EPA found two instances suggestive of industry categories covered by MACT standards, but
where the MACT standard did not directly address the HAP constituent of potential concern.
Because both of these risk estimates were based on detection limit values as opposed to reported
concentration values, and both of these constituents would benefit from co-control of similar
HAPs that are covered by the MACT standard, it is not clear that a regulatory gap, in fact, exists.
It should be noted that the NESHAP program only automatically applies to facilities that
are considered "major sources," as determined by quantitative measure of the facilities' HAP
emissions. Facilities that release less than 10 tons per year of a single HAP or less than 25 tons
of more than one HAP are not major sources, and are defined as "area sources." Area sources
have special designation under the NESHAP program and their emissions may not be controlled
to the same degree as major sources or they may not be controlled at all. To issue equivalent
controls for area sources, EPA must either: (1) find that the source presents a threat to human
health or the environment warranting regulation, which may or may not be as stringent as major
source regulations;1 or (2) determine that MACT standards are necessary to fulfill the
requirements of the Urban Air Toxics Program pursuant to CAA 112(c)(3) and 112(k). One
important aspect of the area source program is that the residual risk program cannot address area
sources unless they have been listed in accordance with section 112(c)(3) and have been included
1 "Positive area source determinations" are rarely made and, if not made, area sources are not subject to the
MACT controls that apply to major sources for the same source category.
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March 26, 2001 Chapter 5
in regulations under section 112(d). EPA did not evaluate the extent to which surface
impoundments are located at facilities that meet the definition of a NESHAP major source.
5.4.1.3 Whether Unaddressed Risks Could Be Better Addressed under Existing
Programs. Overall, the study shows that coverage of potential air risks is fairly complete, and
any gaps in coverage appear, at most, to be limited to specific industry sectors, individual
facilities that meet certain exemptions in the NESHAP program, or specific HAPs. This
regulatory analysis has determined that, for the air risks that may be present from impoundments,
EPA and states have the following tools that could be used more expansively to better address
the few risks identified. Most of these tools are currently available, without any regulatory or
statutory changes. Voluntary and site-specific tools are included on this list because the potential
risks are not widespread.
• Clean Air Act NESHAPs: The CAA requires air emission standards for certain
source categories under section 112, i.e., Hazardous Air Pollutants. Additionally,
the CAA has residual risk evaluations associated with the 112 MACT standard.
• Clean Air Act Criteria Air Pollutant Program: New or modified sources may be
subject to NSPS requirements that could limit VOC emissions from surface
impoundments.
• RCRA: For those facilities that are subject to permitting under Section 3005, EPA
has the authority to address releases from nonhazardous waste impoundments
under the corrective action provisions of section 3008(h) and 3004(u). The
"omnibus" permit provision of section 3005 also requires that any RCRA permit
issued be protective of human health and the environment and, therefore, can be
used to address any identified risks. Further, EPA retains authority to address any
solid waste unit, including nonhazardous waste impoundments, under RCRA
section 7003 to the extent that "an imminent and substantial endangerment" to
human health and the environment may exist.
• State regulation programs: This study determined that a few state solid waste
programs address, to varying degrees, air releases from surface impoundments.
States also may have additional authorities they can bring to bear at the site-
specific level (e.g., through the state's Air Toxics Program or State
Implementation Plan). Such programs may be able to target facilities that have
the potential to exceed risk thresholds for the air pathway. EPA also has issued
draft guidance for state Industrial D programs that identify ways air risks can be
evaluated and addressed.
• Voluntary Waste Minimization Programs: Federal and state agencies have a
number of waste minimization programs that may address the pollutants of
concern. Process changes made upstream of impoundments may reduce or
eliminate the pollutants of concern to prevent them from even reaching the
impoundments. These programs generally rely on voluntary actions by private
parties.
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• Supplemental Environmental Programs: When enforcement actions are taken
under RCRA or other authorities at facilities with impoundments, EPA or the
states may negotiate supplemental agreements or compliance orders to address
releases from impoundments.
• New controls: Under RCRA, EPA has considerable authority to develop new
regulations that would address possible gaps. These regulations might identify
additional wastes as hazardous under 40 CFR Part 261, either through additional
waste listings or characteristics. Wastes identified as hazardous would then be
subjected to all Subtitle C requirements, which include controls on air emissions.
Also, for the decharacterized waste, EPA can issue additional rules under the
Land Disposal Restrictions (see 40 CFR Part 268). These controls may require
treatment of the pollutants of concern prior to placement in the impoundment so
that the pollutants would either be eliminated or reduced to levels that minimize
threats to human health and the environment.
• New controls: The CAA provides the ability to add industrial source categories
and HAPs to the section 112 and 129 evaluations. (See sections 112 (c)(5) and
(b)(3)(B), respectively.)
In summary, a number of tools exist to better address any risks that may be present from
impoundment air emissions. Some of the tools are already being used as a matter of course to
address impoundments and pollutants of concern.
5.4.2 Groundwater and Surface Water Pathway Analysis
5.4.2.1 Summary of State and Federal Coverage. For the groundwater pathway, several
metal and organic constituents were identified as potentially posing risks above the EPA
threshold at IE-OS cancer risk or 1 HQ noncancer risk. As discussed above, in general, releases
to groundwater from nonhazardous surface impoundments are controlled under state programs.
This study found that regulatory and nonregulatory coverage of potential groundwater risks is
fairly complete, but may still have some limited gaps. Based on available information, most
states have a program(s) that includes provisions for controlling or addressing groundwater
releases from industrial nonhazardous waste surface impoundments. The level of regulatory
control or ability to address these releases, however, varies from state to state. These state
regulations may be implemented under either general solid and industrial waste management
authority or under water program authority. Note that EPA's analysis of state regulations and
programs is based on publicly available information rather than on a survey of state regulators.
Therefore, the analysis may not have identified all state regulations and programs that address
nonhazardous waste industrial surface impoundments.
Additionally, there are RCRA, CWA, and SWDA programs that also, to varying degrees,
address groundwater releases or assess the susceptibility of drinking water sources to
contamination. These programs, for example, include the SDWA Source Water Assessment
Program (SWAP), SDWA Wellhead Protection Programs, RCRA corrective action, reliance on
the voluntary Guide for Industrial Waste Management as it is being developed, NPDES program
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(including the Program for Storm Water Discharges Associated with Industrial Activity), and
federal or state waste minimization programs. Where these facilities may impact a waterbody
not meeting state water quality standards, their impacts could be addressed through the total
maximum daily load program.
5.4.2.2 Limitations in State and Federal Coverage. As noted in Chapter 4, coverage
under the various state programs varies, and some impoundments posing potential risks may not
currently be addressed. Further, as discussed elsewhere in this report, should land use patterns
change and populations increase around impoundments, additional impoundments could pose
risks in the future that are not currently addressed by state programs.
5.4.2.3 Whether Unaddressed Risks Could Be Better Addressed under Existing
Programs. Many of the same RCRA and state tools described for the air pathway are also
applicable to the groundwater and surface water pathways:
• RCRA: The same RCRA tools that exist for the air pathway also exist for the
groundwater and surface water pathway.
• State non-RCRA regulations: State NPDES programs and solid waste programs
may be able to target facilities that have the potential to exceed risk thresholds for
the groundwater and surface water pathway. EPA also has issued draft guidance
for State Industrial D programs that identify ways groundwater and surface water
risks can be evaluated and addressed.
• Voluntary Waste Minimization Programs: Same as discussed for the air pathway.
• Supplemental Environmental Programs: Same as discussed for the air pathway.
• New RCRA Controls: Same as discussed for the air pathway.
In summary, a number of tools exist to better address any risks that may be present from
impoundment groundwater releases. Some of the tools are already being used as a matter of
course to address impoundments and pollutants of concern.
5.5 Surface Impoundment Study Conclusions
5.5.1 Our General Findings
This study satisfies both the requirements of the consent decree and the LDPFA with
regard to evaluating the risks and regulatory programs for surface impoundments receiving
"decharacterized" wastewaters and never characteristic wastewaters. In both cases, EPA has
conducted an extensive analysis of the in-scope surface impoundment universe to better
understand the risks that may be posed, and the extent that risks are addressed by current and
emerging federal and state programs.
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5.5.2 Specific Findings to Satisfy Consent Decree Resulting from EDF v. Whitman
In conducting the study pursuant to the EDF consent decree, EPA has obtained the
information necessary to determine whether a rulemaking to promulgate a hazardous waste
characteristic should be initiated. Specifically, EPA examined the universe of impoundments
that manage nonhazardous wastewaters; characterized the pollutants of concern, likely releases,
and pathways from these impoundments; and assessed potential risks to human health and the
environment. Little risk was found and, such as it is, any risk is not widespread. However, risks
may, at most, exist in certain industrial sectors or at a facility-specific level, which needs to be
verified more specifically. Further, EPA examined the regulations that may apply to
impoundments under the variety of federal and state authorities and found that coverage is
extensive, but may not be complete in all cases. EPA also identified a number of tools that may
be used more expansively to better address risks.
5.5.3 Specific Findings to Satisfy LDPFA—RCRA Section 3004 (e)(10)
In conducting the study pursuant to the LDPFA, EPA has completed a study of
"decharacterized" wastewaters that characterizes the risks to human health or the environment
associated with such management. The findings of the risk assessment, and its limitations, are
discussed at length in Chapter 3 of this study. Further, EPA examined existing federal and state
programs to evaluate the extent that risks are adequately addressed under those programs. EPA
also looked at whether the risks could be better addressed under such laws or programs. These
analyses, including a "gap analysis," are discussed in detail in Chapter 4 of this study. EPA
concluded that there are some limited gaps in regulatory coverage, but did not find any serious
risks that are not addressed by existing programs.
5.5.4 Study Conclusion
The completed surface impoundment study will undergo a formal peer review process
similar to the one EPA conducted after completion of the first phase of the consent decree study.
Consequently, any technical data in the report should be used with appropriate caveats and
cautions. The Agency has not yet determined whether any specific regulatory actions are
appropriate to mitigate the potential risks identified in the study.
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Appendix A
Study Design and
Survey Data Collection and Processing
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March 26, 2001 Appendix A
Table of Contents
A.I Statistical Study Design and Survey Implementation A-l
A. 1.1 Sampling Frame and Stratification A-2
A. 1.2 Screener Survey Implementation A-4
A. 1.3 Long Survey (Second-Phase Sample) A-6
A.2 Long Survey Data Entry A-l 1
A.2.1 Data Entry Objectives A-l 1
A.2.2 Data Entry Database A-l 1
A.2.3 Data Entry Protocols A-13
A.2.4 Digitizing Map Data A-13
A.2.5 Diagram Data, Elevation Data A-l8
A.2.6 Quality Assurance/Quality Control A-21
A.3 Collection of Supplementary Data A-21
A.3.1 Development of Supplementary Spatial Data A-22
A.3.2 Surface Water Distances and Flow Data A-30
A.4 Data Processing A-32
A.4.1 Consolidated Database A-33
A.4.2 Risk Assessment Input Data A-34
A.4.3 Derived Variables for Exploration and Analysis A-42
A.5 Data Analysis Methods A-42
A.5.1 Statistical Analysis Weights A-42
A.5.2 Estimation Procedures A-54
A.6 References A-59
Attachment Al. Survey Forms A-l-1
Attachment A2. Data Entry Database Design A-2-1
Attachment A3. Data Entry Protocols A-3-1
Attachment A4. GIS Protocols A-4-1
Attachment A5. Diagram Data A-5-1
Attachment A6. Data Processing Algorithms: Consolidated Database A-6-1
Attachment A7. Consolidated Database Design A-7-1
Attachment A8. Risk Assessment Input Database Design A-8-1
Attachment A9. Chemical-Specific Variables Used for Risk Input Data A-9-1
Attachment A10. Derived Variable Specifications A-10-1
in
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March 26, 2001 Appendix A
Appendix A
Study Design and Survey Data Collection and Processing
This appendix describes the overall study design, implementation of the survey data
collection, and the preparation of these data for the analyses described in Chapters 2 and 3 of this
document. Section A. 1 explains the statistical study design and the development of the original
sampling frame, or list of facilities from which EPA selected facilities for the study. It also
provides details on the design and implementation of the screener and long surveys developed to
collect study data.
The remainder of this appendix provides details on the creation of electronic long survey
databases and their use in providing data for data exploration (Chapter 2) and the risk assessment
(Chapter 3). This includes how the long survey data were entered and archived in electronic
formats (A.2); how facility-specific data supplemental to the survey were collected (A.3); how
the data were processed for consistency and to provide inputs for modeling and data analysis
(A.4); and a description of the statistical methodology used to weight up survey data and risk
assessment results to estimates applicable to the entire population of surface impoundments with
constituents or pH of concern (A.5).
A.I Statistical Study Design and Survey Implementation
As described in Chapter 1, the Surface Impoundment Study is directed towards
identifying and characterizing certain nonhazardous surface impoundments. An eligible
impoundment is one that meets the criteria in the legislation or consent decree, regarding the
wastes managed, and meets additional scope criteria described in Chapter 1, notably extreme pH
conditions (i.e., less than 3 or greater than 11) or that one or more of 256 chemicals are present.
In order to identify a representative sample of facilities with impoundments meeting the study
criteria, EPA developed a two-phase or double-sampling design. In the two-phase design EPA
collected some information on a relatively large sample of facilities through a screener survey
and then used this information to select a second-phase subsample of facilities for which detailed
facility and impoundment data were collected using a longer survey questionnaire.
EPA decided to collect data in the long survey for all eligible impoundments at the
facilities in the sample. This decision meant that EPA would obtain an approximately equal
probability sample of impoundments within primary sampling strata because facilities were
selected with approximately equal probabilities within primary sampling strata (direct discharge
facilities with high priority SICs, direct discharge facilities with low priority SICs, and zero
discharge facilities). In addition, by collecting data for all eligible impoundments at sample
facilities, EPA could overlay risk estimates for the separate impoundments to produce an
integrated assessment of risk at the facility level. Facility-level risk estimates are important if a
facility's nearby residents can be exposed to emissions from multiple sources (impoundments).
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March 26, 2001 Appendix A
A. 1.1 Sampling Frame and Stratification
The sampling frame for nonhazardous industrial surface impoundments was based on
available data identifying and listing facilities with surface impoundments that might meet the
study criteria. Three primary sampling strata were defined for selection of facilities for the
screener survey based on the facility's regulatory status under the Clean Water Act:
• Direct discharge (Section 402) impoundments treat waste in systems that
ultimately discharge directly into surface waters. This subpopulation is regulated
under CWA Section 402, which requires National Pollution Discharge
Elimination System (NPDES) permits for all facilities that discharge to "waters of
the United States."
• "Zero discharge" impoundments are not designed to discharge waste into the
environment except through infiltration into soil or evaporation. Facilities that
use infiltration or evaporation ponds for waste treatment or disposal may be
regulated under a variety of state laws addressing both waste handling and
groundwater protection. Specific regulations regarding these impoundments vary
by State.
• Indirect discharge (Section 307) impoundments treat or hold waste prior to
discharging to a publicly owned treatment works (POTW). Facilities that
discharge significant waste flows to POTWs must comply with federal and local
standards for pretreatment of waste in order to prevent adverse impacts on the
public treatment plants. Local POTWs are the principal permitting authorities for
CWA Section 307 facilities.
There are major differences in the sources and availability of data for defining the
sampling frame for each of these subpopulations, and this affected the sampling frame and
stratification for each. For the direct and zero discharger subpopulations, sampling frame data
were adequate to use a stratified simple random sampling design, in which facilities were
randomly selected from strata without replacement, and data were collected for all eligible
impoundments at the facilities in the sample. For the indirect discharger subpopulation, limited
sampling frame data led to a purposive (non-random) sample of facilities identified using
anecdotal information. The chosen designs mean that the direct discharger and zero discharger
samples are representative (although the sample is less representative for zero dischargers
because their sampling frame was incomplete for some states). However, the non-random
indirect discharger sample may not be representative.
A. 1.1.1 Direct Discharge Facilities and Impoundments. The Permit Compliance System
database (PCS) contains all facilities releasing waste to surface water, including those operating
surface impoundments. EPA used this database as the sampling frame for the direct discharger
subpopulation. EPA took the records in this database, as of late 1997, for facilities having SIC
codes that were defined as the study's scope.
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Each PCS record related to a given discharge point, so a facility with multiple discharge
points had multiple records. In addition, facilities with multiple permits were listed more than
once. EPA combined multiple records for a given facility into one record only when it was quite
clear that the records were for the same facility. EPA merged up to three different permits into a
single facility-level record. The final count of records for facilities with SIC codes in the study's
scope was 43,050.
EPA partitioned the sampling frame into three primary sampling strata, defined as:
1. Facilities in high-priority SICs (26, 2819, 2824, 2834, 2869, 2897, 2911, 30, 33,
or 36)
2. All other facilities with in-scope SICs
3. Six pilot study facilities
Stratum 1, the high-priority SICs, were expected to contain a higher proportion of
facilities that use surface impoundments to manage decharacterized wastewaters. Hence, this
stratum was sampled at a much higher rate than Stratum 2, the remainder of the in-scope SICs, to
ensure that the screener survey would include an adequate number of facilities using surface
impoundments to manage decharacterized wastewaters. Each of these strata was then partitioned
into substrata based on SIC codes, and the substrata were all sampled at the same rate within
each primary sampling stratum. Hence, a stratified simple random sample of 2,000 facilities was
selected from 15 sampling strata plus all six pilot study facilities.
A. 1.1.2 Zero Discharge Impoundments. In this study, EPA defined zero discharge
impoundments as those that are neither permitted under Section 402 of the Clean Water Act to
release to surface water, nor permitted under Section 307 to pretreat waste before releasing it to
a publicly owned treatment works (POTW). Because states are the primary regulators of zero
discharge impoundments, state databases were the principal source of information on these
impoundments. In addition, EPA identified some zero discharge impoundments in the Toxics
Release Inventory (TRI) and the Aerometric Informational Retrieval System (AIRS) Facility
Subsystem (AFS) databases. By assembling information from TRI, AFS, and available state
data, EPA developed a list of 5,807 zero discharger facilities. EPA stratified the sampling frame
according to general categories of completeness for the different state and federal data sources,
and according to high and low priority SIC codes. A stratified random sample of 250 facilities
was selected in the first stage using the same sampling rate for all strata except for the Oklahoma
database of private sewage treatment facilities. EPA expected this group of facilities to be
mostly out-of-scope, and if in-scope, to be relatively homogeneous. Hence, EPA sampled them
at one-half the rate used for the other strata.
A.I.1.3 Indirect Discharge Impoundments. Section 307 of the Clean Water Act regulates
indirect discharger facilities, which "pretreat" or hold waste prior to discharging it to a POTW.
The total population of facilities required to pretreat their waste prior to discharge to a POTW is
over 30,000; they are regulated and tracked by the approximately 2,000 POTWs that receive this
pretreated waste. However, the POTWs do not routinely collect data on surface impoundment
use by their pretreating customers, so there is no consistent data source from which to identify
indirect dischargers that use surface impoundments. In addition to the 30,000 pretreaters, there
A-3
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March 26, 2001 Appendix A
are an unknown number of other indirect dischargers who are not required to pretreat their waste
(and who discharge to POTWs outside the national pretreatment programs). Theoretically, any of
these indirect dischargers could potentially use surface impoundments to store wastewater before
discharging it. Based on information from EPA Regional pretreatment coordinators, it appears
that only a very small proportion of these indirect discharger facilities are likely to use surface
impoundments. From this information, EPA assembled a group of 35 facilities likely to operate
indirect discharge impoundments and used this as a purposive sample to characterize the indirect
discharger subpopulation.
A.I.2 Screener Survey Implementation
The sampling frame and stratification scheme led to a total of 2,285 facilities being
selected for the screener survey, a short questionnaire designed to identify facilities and
impoundments that meet the study criteria and thereby provide the sampling frame data for the
long survey (see Attachment Al). These facilities included 2000 direct dischargers, 250 zero
dischargers, and 35 indirect dischargers. Implementing the screener survey involved identifying
and removing ineligible facilities from this sample, identifying and locating survey respondents
to obtain the highest possible response rate, adjusting facility weights to account for survey
nonresponse, and data entry, quality control, and processing.
A. 1.2.1 Removal of Ineligible Facilities from Sample. The facilities chosen for the direct
and zero discharger samples included a number of facilities that were outside the scope of the
study. In many cases, the facilities selected in the sample were private residences or retail
businesses that did not have activities in the SIC code range defined for the study, even though
they were listed on the sample frame as having eligible SIC codes. EPA confirmed these sample
members' status as "ineligible" using other data sources, and removed them from the sample. For
the direct discharger sample, EPA determined that 138 facilities among the 2,000 direct
dischargers were ineligible, and 74 facilities among the 250 zero dischargers were ineligible,
resulting in 2,038 direct and zero discharger facilities in the sample.
A.1.2.2 Identifying Screener Survey Respondents. Once eligible facilities were
identified, EPA needed to identify and locate the survey respondents. EPA found that the PCS
data and the zero discharger frame data were frequently missing mailing address, location, and
contact information. Of the 2,038 direct and zero discharger facilities, EPA found mailing
addresses for 1,982. EPA found mailing addresses for all 35 indirect dischargers. Thus, the
screener survey was mailed to 2,017 facilities.
The screener survey was mailed in February 1999. A large proportion of the surveys
went to the appropriate individuals and were returned within the requested 45-day time frame
with adequate information. EPA found that a significant proportion of the sample facilities had
either changed ownership or names, or had ceased to exist during the period between 1990 and
1999, and required further tracing to locate individuals who were knowledgeable about those
facilities' impoundments. Thus the screener survey data collection extended over a six-month
period.
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March 26, 2001 Appendix A
EPA also needed to address the sampling frame multiplicity problem described in Section
A. 1.1.1. Any facilities with multiple permits that did not get merged into a single facility-level
record on the sampling frame had multiple chances to be selected into the sample. Because being
listed on the sampling frame more than once increases a facility's probability of selection, EPA
needed to correct for this multiplicity, or being present on the sample frame more than once.
EPA listed on the screener survey all wastewater permits that had been used to define the facility
on the sampling frame, and asked each facility (on the screener survey) to list any additional
permits that had been active for the facility at any time since June 1, 1990. In addition, EPA set
up a computer-assisted telephone interviewing (CATI) application to call the screener survey
respondents and probe for any additional permits that had not been listed on their screener survey
responses. EPA then used both the responses to the original screener survey question and the
responses to the supplemental CATI interviews to make weight adjustments for frame
multiplicity (described in Section A. 5).
EPA also used a CATI version of the mail survey to increase the response rate for
approximately 100 of the mail screening survey recipients who did not provide their responses in
a timely manner.
A. 1.2.3 Screener Survey Weight Adjustments. For each of the 1,982 direct and zero
discharge facilities mailed a screener, an initial sampling weight was computed by dividing the
total number of facilities in the stratum (frame count) by the number of facilities selected into the
sample from the stratum. Frame counts, sample sizes, and initial sampling weights for each
stratum are provided in Section A.5, along with the detailed statistical methodologies. Sampling
weights were not computed for the sample of 35 indirect discharger facilities because the sample
was purposively selected and the survey results cannot be statistically extrapolated to any larger
population.
Next, EPA needed to adjust these initial sampling weights for the sampling frame
multiplicity described in Section A. 1.1.1. After considerable data cleaning, multiplicity (number
of linkages to the sampling frame) was determined for each facility that responded to the
screening questionnaire. Because frame multiplicity must be known for every sample facility,
not just the responding facilities, EPA computed, for each direct discharger sampling stratum,
the average multiplicity among the respondents and used this value to impute multiplicity for
each nonresponding facility. These multiplicity estimates were then used to adjust weights as
described in Section A. 5.
Weight adjustments to minimize bias due to survey nonresponse are based on models for
the probability of not responding, using data that are available for both the respondents and the
nonrespondents. For nonresponding facilities, EPA knew only the sampling stratum, and thus,
EPA used sample-based ratio adjustments based on the sampling strata (Kalton and Maligalig,
1991). The nonresponse adjustments were defined only for the direct and zero discharge
facilities because the indirect discharger sample was not a probability-based sample. Statistical
details on facility weights and weight adjustments, including item-specific adjustments made
during data analysis, can be found in Section A.5.
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March 26, 2001 Appendix A
A.1.2.4 Screener Survey Data Processing. In the screener survey (U.S. EPA, 1999b),
EPA collected data on the facility's use of surface impoundments, and on the activities that were
the source of the waste in the impoundment(s). For those facilities that reported using
impoundments that met the criteria for being in the study, EPA also collected data on the
facility's status as a hazardous waste generator, whether any impoundments contained
decharacterized waste, whether the impoundments were used to treat waste biologically, and
whether the impoundments had permanently stopped receiving waste.
When the screener surveys were returned, a coding clerk assigned codes for the
closed-ended questions, according to a predetermined code list for the various response options.
The surveys were then grouped into batches for tracking the hard copy survey forms and to
subdivide the overall data entry task into more manageable segments. Double-extraction/double-
entry was used to minimize data entry errors. Each coded response was entered into the data file
twice, by different data entry staff, the files were electronically compared, and any differences
were resolved by referring to the hard-copy forms.
EPA also performed a check on the responses indicating that there was no impoundment
at the facility that met the study criteria. To perform the check, EPA drew a systematic random
sample of every tenth response that indicated an absence of impoundments meeting the study
criteria. For these responses, EPA obtained independent data (generally, state environmental
agency files such as inspection reports) to verify these respondents' answers that no
impoundments meeting the study criteria existed at these facilities. This check did not turn up
any false negative responses.
Some facilities claimed their screening survey responses as Confidential Business
Information (CBI), and EPA handled those facilities' screening survey responses data separately,
in accordance with RCRA CBI procedures, but challenged all CBI claims. One screener survey
response remains CBI.
EPA conducted a final edit of the screening survey data for all 1,787 completed screening
surveys. This edit cleaned the data and ensured consistent formatting of responses and coded
standardized responses for subsequent analyses. The cleaned data includes all screening survey
data items, plus additional data needed for statistical analyses, and are available in electronic
format (U.S. EPA, 1999b).
A. 1.3 Long Survey (Second-Phase Sample)
For all facilities in the second phase sample, EPA prepared a long survey questionnaire
requesting detailed information on the impoundments' design, operation, and closure practices as
well as data on the wastewater and sludge composition and quantity. This three-part survey (U.S.
EPA, 1999d) was developed by EPA to characterize the sample facilities with in-scope
nonhazardous industrial surface impoundments and is the primary source of data for the Surface
Impoundment Study (SIS), including the risk assessment, regulatory coverage, and other analyses
presented in this report. EPA developed the sampling frame for this long survey from the
screener survey data, as described in the following section.
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March 26, 2001 Appendix A
A. 1.3.1 Long Survey Sampling Frame Development. While screener survey data
collection was continuing through the summer of 1999, EPA needed to proceed with developing
the sampling frame for the second phase sample of facilities that were to receive the long survey.
The study's schedule required the long surveys to be mailed in the fall of 1999 so that the long
survey data could be processed and analyzed for both the risk assessment and the regulatory
coverage analysis. EPA chose to draw the second phase sample in two parts: a June 1999
sample, using the screener survey responses that had been received and processed by June 14,
1999, and a September 1999 supplementary sample to complete the sample with the facilities
whose screener survey responses were processed after June 14, 1999, along with those that had
claimed CBI status for all or part of their screener survey responses. The reason for this timing
was so that EPA could collect publicly available data for most of the second phase sample
facilities from state environmental agencies, along with the publicly available data being used to
perform the false negative quality assurance check on the systematic random sample of screener
survey responses.
After developing the complete set of non-CBI screeners, and reducing them to one record
per facility, EPA determined which facilities were eligible for the second phase sample (long
survey). The June sampling frame was developed from 1,597 completed screeners. Some
facilities had more than one record in the combined hard-copy and CATI, non-CBI database. If
there were screener surveys from both former and current owners, for the same facility, EPA kept
the record for the current owner and deleted the record for the former owner. The resulting file
contained 1,684 unique facilities with completed screeners.
The next step was to identify the facilities that were eligible for the second phase sample,
according to their screener survey responses for the questions about the existence of an
impoundment at the facility, meeting the criteria necessary for being in the study. Not all
facilities answered the question about their facility's SIC code. In these cases, EPA obtained SIC
codes from EPA databases or from descriptions of the facility's products or processes.
The file of facilities with a completed screener survey that were determined to be eligible
for the second phase was the sampling frame for the second phase sample. The June 1999
sampling frame for the second phase sample consisted of 380 facilities; the non-CBI September
1999 sampling frame consisted of 43 facilities, and the CBI September 1999 sampling frame
consisted of 9 facilities. EPA's objective was to obtain an overall sample of approximately 200
facilities, with approximately half of the facilities having at least one impoundment with
decharacterized waste (to satisfy the requirements in the LDPFA), and approximately half of the
facilities having never characteristic waste (to satisfy the requirements of the consent decree). In
addition, EPA needed to balance the study resources so that direct and zero dischargers, and a
few indirect dischargers, were included in the sample. With these general criteria, EPA selected
sampling rates from the various strata that achieved the overall objectives, and resulted in the
sample drawn as shown in Table A-l.
The final result was a sample of 216 facilities, plus the six pilot study facilities.
However, one of the 222 facilities was included in both the June and September sample frames.
Thus, the second phase sample consisted of 221 facilities, six of which were pilot study facilities.
A-7
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March 26, 2001 Appendix A
A. 1.3.2 Weight Adjustments for Ineligible Facilities andNonresponses. Theoretically, all
facilities selected into the sample to receive the long survey should have been eligible for this
phase of the study. That is, they should all have had at least one surface impoundment that
satisfied the eligibility conditions in the screener survey. However, after they received the long
survey, 21 facilities reported no eligible impoundments. By using extensive followup contacts,
EPA determined the eligibility status of all facilities selected into the sample for the long survey.
Hence, nonresponse adjustments were confined to adjustment for nonresponse among the sample
facilities that were determined to be eligible for the survey.
For the full sample, there were only four eligible facilities that did not respond to the
long survey, and one of those was an indirect discharge facility. Hence, for the weight
adjustments for direct and zero discharge facilities, there were only three nonresponding
facilities. Moreover, all three were direct discharge facilities whose screener data indicated that
they did not handle any formerly characteristic waste.
The statistical analysis weights for the remaining 195 long survey respondents then were
computed by adjusting the calibrated sampling weights for nonresponse among the eligible
sample facilities. The weight adjustment process and results is described in detail in Section A.5.
Because data were collected for all eligible impoundments at each responding facility (i.e., there
was no subsampling of impoundments), these facility-level analysis weights also are appropriate
for analysis of the impoundment-level data collected for the responding facilities.
A. 1.3.3 Long Survey Implementation. The long survey questionnaire (U.S. EPA, 1999d)
is a three-part form designed to collect the detailed information necessary for the risk assessment
and regulatory gaps analysis as well as general characteristics of the study population. This
information includes each facility's environmental setting (including receptor locations) and
details on the design, operation, and history of each eligible surface impoundment, including the
chemical composition of wastewater and sludge managed within these impoundments. The
three parts include: Part A, basic facility identification information; Part B, an overview of the
wastewater treatment system and environmental setting at the facility; and Part C, details about
the design and operation of each in-scope impoundment. Part C also requested, for a list of 256
chemicals, chemical concentration data for wastewater, sludge, air, and leachate. Attachment A.I
includes electronic copies of the Part A, Part B, and Part C long survey forms.
The detailed information in the long survey required considerable effort to enter into an
electronic format, standardize to consistent units and format, clean to correct skip pattern errors
and other inconsistent responses, and process for data exploration and risk analyses. This was
accomplished by creating and populating a series of relational databases, described in the
subsequent sections, that hold the raw and processed survey data. Statistical methods were then
applied (as described in Section A.5) to weight and analyze variables derived from the screener
and long surveys (including risk assessment results) to characterize the population of
nonhazardous industrial surface impoundments that meet the study criteria.
A-8
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March 26, 2001
Appendix A
Table
Stage 2
Stratum
Type
A-l. Second Phase (Long Survey) Strata and Sample Sizes
of Facility
Decharacterized
Waste
SIC Priority
Frame
Count
Sample
Size
Non-CBI Stage 2 Strata and June Sample Sizes
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Total
Direct Dischargers
(DISCHARGE)
Zero Dischargers
(DISCHARG=2)
Preselected Indirect
Dischargers
(DISCHARG=3 and
PREINDIR=1)
Other Indirect
Dischargers
(DISCHARG=3 and
PREINDIR=2)
Yes
(Q16=l)
Other
(Q 1 6=2 or missing)
Yes
(Q16=l)
Other
(Q 1 6=2 or missing)
Yes
(Q16=l)
Other
(Q16=2 or missing)
Yes
(Q16=l)
Other
(Q16=2 or missing)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
69
7
183
72
2
4
13
20
2
0
4
4
0
0
0
0
380
69
4
61
12
2
4
13
20
2
0
4
4
0
0
0
0
195
(continues
A-9
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March 26, 2001
Appendix A
Table A-l. (continued)
Stage 2
Stratum
Type of Facility
Decharacterized
Waste
SIC Priority
Frame
Count
Sample
Size
Non-CBI Stage 2 Strata and September Sample Sizes
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Total
Direct Dischargers
(DISCHARGE)
Zero Dischargers
(DISCHARG=2)
Preselected Indirect
Dischargers
(DISCHARG=3 and
PREINDIR=1)
Other Indirect
Dischargers
(DISCHARG=3 and
PREINDIR=2)
Yes
(Q16=l)
Other
(Q 1 6=2 or missing)
Yes
(Q16=l)
Other
(Q 1 6=2 or missing)
Yes
(Q16=l)
Other
(Q16=2 or missing)
Yes
(Q16=l)
Other
(Q16=2 or missing)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
4
0
17
4
0
0
1
0
0
0
2
1
2
1
3
8
43
4
0
6
1
0
0
1
0
0
0
2
1
0
0
1
0
16
(continues
A-10
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March 26, 2001
Appendix A
Table A-l. (continued)
Stage 2
Stratum
Type of Facility
Decharacterized
Waste
SIC Priority
Frame
Count
Sample
Size
CBI Stage 2 Strata and Sample Sizes
1
2
3
4
Total
Direct Dischargers
(DISCHARGE)
Yes
(Q16=l)
Other
(Q 1 6=2 or missing)
High
(SIC STR=1)
Low
(SIC_STR=2)
High
(SIC STR=1)
Low
(SIC_STR=2)
3
0
4
2
9
3
0
1
1
5
A.2 Long Survey Data Entry
The goals of the data entry effort for the long survey were 1) to archive as complete a
dataset as possible, in order to increase statistical confidence and 2) to maintain the integrity of
the dataset through entry, processing, and analysis. This required rigorous quality
assurance/quality control (QA/QC) procedures at every step of the process. The general QA/QC
plan was to check all manually entered data 100 percent and to manually confirm that each data
processing or analysis program was functioning correctly. Details on the data entry methodology
and associated QC measures follow. This required entry of almost 200 Part A and Part B forms
and, because many facilities had multiple eligible impoundments, over 500 Part C forms.
A.2.1 Data Entry Objectives
The overall objective of long survey data entry was to record and preserve, in an
electronic format, exactly what the survey respondents reported on their returned forms.
Although obvious typographical errors were corrected, entry staff were instructed not to judge
how reasonable or consistent responses were, but to record them exactly as written. Database
fields for margin notes from the long survey were included in for practically every question; this
also enabled for typographic or other corrections to be recorded in the data entry database.
A.2.2 Data Entry Database
The data entry database for the long survey mirrors the design of the survey forms shown
in Attachment Al. Data tables were indexed at the facility level (questions in Parts A and B),
facility and impoundment level (Part C), and at a third level, by chemical for chemical data and
by layer for liner and subsurface layer data. To help ensure consistent entry, coding tables were
used for units and other repeated data elements. Duplicate tables were included in the entry
database to allow for double extraction and double entry. Once double extraction/double entry
A-ll
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March 26, 2001 Appendix A
comparisons were complete, these tables were removed from the database, resulting in the design
described in this section. Although created and maintained in Microsoft Access, data design
conventions include compatibility with *.dbf format, and programs are available to automatically
export the database tables as .dbf or ASCII text files.
Data entry forms were developed that replicate the survey's appearance as closely as
possible. This provided almost immediate familiarity with the entry screen for the data entry
staff. Buttons were used to open text fields to record margin notes and comments. Drop-down
boxes included standardized selections for units and other repeated data responses. EPA designed
the survey to allow respondents to choose units for numeric values, resulting in a number of units
being used for each numeric variable. As new units were encountered during data entry, the
standard list of units was expanded to help ensure consistent and correct entry of each response.
Attachment A2 includes data entry database design documentation which describes the
data table structure, linkages, codes, and the content of the various data fields. The database
design is fully documented three parts, described briefly below.
A.2.2.1 Entity Relationship Diagram. Attachment A2-1 contains entity relationship
diagrams that picture how the various tables that make up the data entry database are linked
together using key fields. Links in this diagram are shown as one-to-many (where a table is
related to several tables of the same structure) or one-to-one (where a table is linked to a single
table). Tables are linked using one, two, or three key fields, depending on the number of tables
linked and the position of the tables in the database. For example, because there can be multiple
surface impoundments at a facility, there can be many surface impoundment data tables for each
facility, with these multiple tables linked to the Surfjmps table by the key fields FAC_ID and
IMP ID.
The first figure in Attachment A2-1 shows the overall database structure along with table
structures for Part A and Part B of the long survey questionnaire. The remaining figures show the
table structures and relationships for the Form C tables connected to the SURF_IMPS table.
Survey questions corresponding to the data tables are listed at the top of each diagram.
A2.2.2 Data Dictionary. Attachment A2-2 contains the data dictionary for the database
tables shown in the entity relationship diagram (Attachment A2-1). This dictionary provides data
type, size, and description (including long survey question number) for each field (column) in
each database table, which are listed in the order of the survey questions and as they appear in the
entity relationship diagrams. Data dictionaries for the coding tables are provided in alphabetical
order at the end of this attachment.
A.2.2.3 Coding Tables. Attachment A2-3 contains the coding tables from the data entry
database. In the SI survey database, coding tables serve the same function as a data entry code
book: to ensure consistent responses for questions with answers that can be standardized, such as
units or chemical names, or for questions with multiple choice responses (e.g., yes, no, don't
know, or other). These tables were adapted from coding tables developed during survey design.
Standardization (i.e., use of a table for multiple questions) was used wherever practical to
minimize the number of tables and increase consistency within the database. During data entry,
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March 26, 2001 Appendix A
codes and their definitions are presented as drop-down boxes in the data entry forms to ensure
correct and consistent data entry. The coding tables appearing in this document supercede those
in the previous version in that they include additional rows for new values encountered during
data entry. For example, the codes for concentration units expanded from 20 to over 40 possible
entries during the course of data entry.
A.2.3 Data Entry Protocols
Data entry protocols were developed for and followed by data entry staff, and serve as a
record of how data were entered. As new situations were encountered during data entry, the
protocols were modified. The final protocol is included in Attachment A3.
Data entry protocols were developed to ensure consistent treatment of potentially
inconsistent or incomplete data, and thereby minimize the double-entry comparison task and
ensure a higher quality dataset. Perhaps the most important protocol was to record exactly,
word-for-word, what was recorded in the survey, including the margin notes entered by the
survey respondents. Another was to record a comment for every change made to correct obvious
errors, resulting in a note wherever the database differs from the original survey.
Chemical data conventions were needed to ensure consistent treatment of nonstandard
responses. Examples include: enter "cyanide" and "reactive cyanide" as total cyanide and
"amenable" cyanide as free cyanide; sum individual alachlor values and enter total under "PCBs,"
including individual values in margin note; enter "chromium" values as total chromium. In each
of these cases, notes were included in the database describing what was done. These and other
data entry conventions are detailed in the data entry protocol in Attachment A3.
A. 2.4 Digitizing Map Data
A geographic information system (GIS) was used to digitize residence and well locations
from the marked topographic maps returned as question B3 of the Part B of the survey. Question
B3 asked the survey respondents to mark wells, residences, and schools within a 2-kilometer
radius of their surface impoundments on a U.S. Geological Survey (USGS) topographic map that
was included with the survey form (see Attachment Al).
Survey response data for question B3 maps were used to develop a series of GIS map
layers. The goals of these procedures were (1) to develop a series of GIS map and data layers that
could be used to analyze spatial relationships among surface impoundment ponds, receptors,
schools, and wells; and (2) to process and extract data to serve as inputs to risk assessment
models. The coordinate locations of impoundment boundaries, individual residences, residential
areas, schools and wells were entered into a GIS through "heads-up digitizing," a process
whereby a GIS technician uses a mouse to enter the locations of features by pointing to them on a
digitized image displayed on screen. A series of programs were written in Arc Macro Language
(AML) to automate the data preparation and digitizing processes.
A.2.4.1 Map Preparation and Registration. Map preparation and registration consisted
of three main steps:
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March 26, 2001 Appendix A
1. Obtain the necessary documents, including the map, image files of the map, and
any additional annotation.
2. Assess the overall quality of the scanned image.
3. Create a registered image from the scanned image.
Obtain documents and images. Spatial data were acquired by physically searching the
file of documents returned by each survey respondent in response to question B3. For most sites,
these documents consisted of one or more hardcopy maps, which were usually annotated by the
survey respondent to show the features to be digitized. In some most cases, these maps were the
USGS topographic maps originally supplied to the respondent. In many cases, however, the
respondent provided an alternate map or maps. These included other USGS topographic maps,
photocopies of USGS maps, and a variety of non-USGS maps including site plan drawings and
as-built diagrams.
Question 3B maps were labeled with preprinted labels containing a text ID and barcode.
These maps were then scanned and converted to TIFF multiband ("composite") images.
Assess image quality. GIS technicians assessed the usability of each scanned image by
displaying the map on the screen and viewing it to confirm that:
all features shown on the map could be seen clearly on the image;
registration marks and site ID label were clearly visible;
there was no apparent distortion of the image;
the image covered all of the area within 2km of the impoundments; and
features and annotation added by the respondent were clearly visible.
The AML program epa_scanmap.aml prompted the user with a checklist and ensured
consistency during this procedure. If the map was not usable and/or areas within the 2km buffer
were missing, USGS Digital Raster Graphic (DRG) images of 1:24,000 Quads were downloaded
via the internet and stored in the respective site directory as TIFF files.
Register image. The original maps provided to survey respondents were standard USGS
7.5-foot topographic quadrangles (1:24,000 scale). These maps contain registration marks for
NAD 83 geographic coordinates near the four corners of the map area. Some of the maps
returned by survey respondents were not standard USGS 7.5-foot topographic quadrangles.
Although some of these maps contained registration marks labeled with geographic coordinates,
others contained grid lines or registration marks based on arbitrary or unidentified coordinate
systems. In some cases, no coordinate system or grid was shown on the map.
Prior to digitizing, each image was registered to a real world coordinate system so that
subsequent measurements of distance and area could be expresses in real world units (as opposed
to scanner inches). In most cases, the appropriate State Plane coordinate system was used. In this
case, "appropriate" means the State Plane coordinate system zone specified on the map. Although
the standard units of the State Plane coordinate system are generally feet, meters were used
throughout this project.
A-14
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March 26, 2001 Appendix A
For maps with registration marks for NAD 83 geographic coordinates (primarily standard
USGS topographic quadrangles), the program epa_box.aml was used to create a file containing
the geographic coordinates of the four registration marks. The program then used this file to
generate a map layer whose corners were coincident with the tic marks at the corners of the 7.5-
foot topographic quadrangle and project this to the user-specified State Plane coordinate system
zone.
A series of other programs, links.ami, register_image.aml, register_grayscale.aml and
register_pseudocolor.aml, utilized Arc/Info's GRIDWARP command to identify registration
marks and transform images to the appropriate State Plane coordinate system.
A.2.4.2 Digitizing Procedures. Features from all maps were digitized using the
menu-driven digitize.ami program. Scanned images were displayed in the background and
features were captured from these images using the cursor as the input device. Each feature type
was stored as a separate map layer, or coverage, and a set of digitizing guidelines was developed
(see Attachment A4-1). The coverage names, their contents and associated map symbols are
shown in Table A-2.
All coverages contained fields for feature-specific margin notes, i.e. information that was
noted on the map by the respondent, and digitizer's comments. Feature-specific margin notes and
comments were added to individual features as they were digitized. Attachment A4-2 contains a
list of standard digitizer's comments. Margin notes and comments that were not specific to one
or more features were inserted into a text file specific to that site and image, i.e., 1234a.txt.
Because all coverages and all of their contained data items were created with the
digitize.ami program, all coverages containing the same feature types have identically defined
attribute tables. This ensures that coverages can be appended at some point in the future after
they are projected to a common coordinate system.
A.2.4.3 QA/OC of Digitized Coverages. QA procedures were incorporated into the
digitizing process and QC checks were carried out throughout the data development process
through the use of computer programs that ensured standardization of data development.
The digitize.aml program was initiated at the command line and required a single
parameter, the image ID of the image to be used for the current digitizing session. The menu
interface to this program, displayed in Figure A-l, contained a large number of buttons which
allowed the user to select the coverage to be edited (the "edit coverage"), add or delete features,
assign impoundment ids, margin notes, or digitizer comments to feature databases ("feature
attribute tables"), and perform all of the other normally-required processes. Also included was a
button to allow the user to temporarily suspend menu input so that commands could be entered
directly on the ArcEdit command line.
Most attributes were assigned to the feature attribute tables automatically, including the
facility ID and map letter, type of source map, feature "origin" (preprinted or handdrawn), and
attributes that controlled the symbolization of features in the graphic display.
A-l 5
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March 26, 2001
Appendix A
Table A-2. GIS Coverage Name, Type, and Content
Coverage
BOX_siteid
BUFF 2KM
PONDS PNT
PONDS POLY
PROPERTY
RECP PNT
RECP POLY
RESP_2KM
SCHL PNT
WELLS
Type
Line
Line
Point
Polygon
Line
Point
Polygon
Line
Point
Point
Contents
Topographic map limits
A system-generated 2-km buffer around
impoundments
Impoundments represented by points
Impoundment boundaries of ponds with areas
Site property boundary
Receptor locations - Individual buildings
known or believed to be residences
Receptor locations - Urban or residential areas
The 2-km radius as drawn by the survey
respondent
Schools represented by point symbols and
individual school buildings
Wells (generally groundwater supply wells)
Map Symbol
Thick red line
Blue dot
Blue line
Dashed red line
Green dot
Green line
Thick red line
Red dot
Hollow blue triangle
with cross
too* toil
,-.« l,,j |M«. Ik,
Bs
1 II
. •
i -
•t "i.V
-i
Figure A-l. Digitizing menu used in digitize.aml program.
A-16
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March 26, 2001 Appendix A
This interface was flexible enough to be used by both experienced GIS personnel and
others without significant prior GIS experience. The program behind the interface was also
designed to prevent or at least limit the inadvertent assignment of incorrect attributes. In other
words, QA was integrated into the program wherever practical.
When all features had been digitized using the digitize.ami program, a program,
qc_site.aml, was run to perform a series of automated QC checks on all coverages created for that
site. These checks ensured that
All the required coverages had been created
All items in each feature attribute tables were present and correctly defined
All standardized items (e.g. site, map, symbol, etc.) had correct values
All lines in coverages containing polygon features formed closed polygons
Lines did not intersect except at nodes (a requirement of lines that would be used
to build polygon features).
The results of the program were written to a text file containing two types of messages. A
warning message was issued if a coverage lacked features (e.g., the coverage containing
residences lacked any points). Error messages were issued if any of the situations described in the
above list dictated (e.g., the program found an incorrectly-defined item or an unclosed polygon).
Corrections were made to the respective coverages, when necessary.
A second QC process involved the generation of large (24" x 36") checkplots of each
image for examination by a quality control reviewer. The reviewer was a GIS analyst who had
not been involved in that site's digitizing process. The checkplot displayed the map image and
each of the digitized features drawn with its corresponding symbol (see Table A-2). The review
process consisted of comparing the original map with both the checkplot and the digital
coverages and carrying out the following steps:
• Determine whether all features had been digitized
• Determine whether all margin notes had been entered with feature data
• Determine whether appropriate digitizer's comments had been entered
• Determine whether non-feature-specific margin notes had been inserted into a text
file.
The reviewer also examined receptor features to determine whether questionable
residences should remain in the coverage. Ancillary data, such as Digital Ortho Quarter Quads,
viewable via a web browser, were used in this determination. In the event that additional
digitizing or revisions were needed, the map original was returned to the digitizer. Corrections
were made and the review process was repeated.
A.2.4.4 Additional Data Modifications. Prior to final analyses of in-scope surface
impoundments (described below), modifications were made to some features to improve the
accuracy of analyses. Three types of modifications were made:
A-17
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March 26, 2001 Appendix A
• Many wells of WELLTYPE 7 or 14 (unknown or unspecified) were reclassified,
based on ancillary data, such as documentation included with the survey.
• An examination of aerial photographs for specific ponds during the analysis of
sites showing air risks revealed residences that had not been digitized. These
were located in subdivisions that were developed after the USGS topographic
quad was produced. In these cases, the additional residences were digitized.
• The assumption was made that all private drinking water wells should have
residences associated with them. Residences were added to many sites to
correspond with these wells.
A.2.5 Diagram Data. Elevation Data
Survey respondents were asked to supply diagrams containing information for three sets
of questions in the survey. These diagrams contained information on facility wastewater
treatment information (survey question Bl), plan and elevation diagrams (question CIO), and
liner diagrams (question Cl 1). Respondents often combined some or all of this information into a
single diagram and or sent diagrams that combined different impoundments on a single diagram.
To avoid making multiple scanned image files of these large format diagrams for each question,
it was decided that each diagram should be scanned only once and then linked to the appropriate
questions.
A.2.5.1 Database for Diagram Tracking and Linkages. A database system was
developed to link each diagram to one or more facilities, impoundments, and uses. Tables A-3
and A-4 provide dictionaries for the two data tables in this database. Adhesive stickers were
printed that contained a unique number printed in both Code 39 barcode and text. One sticker
was placed on each diagram and its number was used as a "diagram number" to track and link the
diagrams. The diagram number contained a checkdigit, which was used to detect and prevent
data entry errors. Database tables were created in an Microsoft Access database to store linkage
information. Simple data entry forms were created to permit linking the diagrams to their use(s)
with simultaneous entry of plan and elevation data extracted from the diagrams.
Diagrams could be linked either to a facility (survey question Bl, wastewater treatment
diagrams) or to an impoundment (survey question CIO, plan and elevation diagrams; survey
question Cl 1, liner diagrams). Wastewater treatment diagrams were linked to a facility by
entering a record containing the diagram number and the facility ID in the table DIAG_WWT.
Other diagrams were linked to an impoundment by entering a record containing the diagram
number, the facility ID, and the impoundment ID in the table DIAG_IMP. In this way, a single
diagram could be linked to a facility and one or more impoundments.
After linkage, the diagrams were scanned into TIFF format, which was converted to the
more highly compressed (i.e., smaller files) GIF format for archiving. The resulting diagram files
were titled with their diagram number (and .gif) as their file name. A simple report program was
written in Microsoft Access that produced listings of documents by facility, impoundment, and
use. This report was printed to an Adobe Acrobat (pdf) file for reference and use in retrieving the
A-18
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March 26, 2001
Appendix A
Table A-3. Structure of DIAG WWT Database Table for Wastewater
Treatment Diagrams (Question Bl)
Field Name
FAC ID
DIAG ID
Type
Text
Text
Size
5
15
Description
Facility ID - Linked to Table FACJNFO
Unique ID for diagram (from diagram sticker)
Table A-4. Structure of DIAG_IMP Database Table for Impoundment Diagrams
(Question CIO, plan and elevation views; Question Cll, liner cross sections)
Field Name
FAC ID
IMP ID
DIAG ID
C10_PLN
C10_XST
C11_LNR
Type
Text
Text
Text
Boolean
Boolean
Boolean
Size
5
50
15
1
1
1
Description
Facility ID - Linked with IMPJD to table SURFJMP
Impoundment ID - unique ID for impoundment at Facility
Diagram ID - unique ID for diagram
True if diagram is a plan view of impoundment
True if diagram is a elevation (cross section) view
True if diagram is a liner cross section
desired files for review. A copy of this report is included in Attachment A-5. The GIF format
survey diagrams are archived and available on CD-ROM.
A. 2.5.2 Processing of Elevation Data from Diagrams. In survey question C-10,
Respondents were asked to supply plan and elevation diagrams for each surface impoundment.
These diagrams were used to obtain the following elevation data:
• Ground elevation,
• Water table elevation,
• Base (bottom surface of the impoundment) elevation,
• Elevation of liquid level in the impoundment.
Maximum, minimum, and typical values (if supplied) were recorded for all elevation data, except
for ground elevation, where an average value was recorded (if supplied). From this data, the
following information was calculated:
• Distance of base from the water table,
• Distance of liquid level from the water table, and
• Height of liquid in the impoundment (i.e., distance of liquid level from base).
A-19
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March 26, 2001
Appendix A
Table A-5. Structure of IMP_ELEV Database Table for Impoundment Elevation Data
(Question C-10)
Field Name
FAC ID
IMP ID
GR EL
GRELUTS
WT MIN
WT MAX
WT TYP
WT_UTS
B MIN
B MAX
B TYP
B_UTS
LH MIN
LH MAX
LH TYP
LHJJTS
Comment
Type
Text
Text
Double
Long Integer
Double
Double
Double
Long Integer
Double
Double
Double
Long Integer
Double
Double
Double
Long Integer
Text
Size
5
50
8
4
8
8
8
4
8
8
8
4
8
8
8
4
250
Description
Unique ID for each facility
Unique ID for impoundment at that facility
Ground (reference) elevation - 0 when referenced to ground
Units code for ground elevation
Minimum water table distance from ground
Maximum water table distance from ground
Typical water table distance from ground
Units code for water table distances
Minimum distance from ground to base of impoundment
Maximum distance from ground to base of impoundment
Typical distance from ground to base of impoundment
Units code for base distances
Minimum distance from ground to top of liquid surface
Maximum distance from ground to top of liquid surface
Typical distance from ground to top of liquid surface
Units code for liquid distances
Comment
A database table (IMP_ELEV) was created to store impoundment plan and elevation data
extracted from diagrams. The structure of the database table (EVIP_ELEV) is shown in
Table A-5. The data entry form for the plan and elevation data was combined with the
impoundment linkage form (mentioned above).
Because of the wide variety of diagrams supplied by participants, extraction of elevation
data required some interpretation. In some instances, the needed elevation data was clearly noted
on the diagram. In other cases, the needed data could be measured from scale drawings. For
quality control, a second person compared all diagrams to their extracted values (i.e., 100 percent
of all data was checked).
Upon completion of data entry and comparison, a senior review was conducted that
focused on extreme data points including:
A-20
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March 26, 2001 Appendix A
Facilities with the greatest differences between high and low water table values
Impoundments with the greatest depth to the water table
Impoundments with the water table at or above the base of the impoundment
Impoundments with water table aboveground elevation
Impoundments with base aboveground elevation
Impoundments with the water table above the impoundment liquid level
Facilities with the greatest distance between impoundment liquid level and water
table
• Inconsistencies between elevation data and depth to saturated zone in survey
questionB-10.
This review considered approximately 15 percent of the facilities. The facility diagrams,
surveys, and published data, such as USGS maps, were used in the review. Changes were made
for 10 facilities based on review of elevation data. Corrections were made for three additional
facilities based on the comparison of elevation data with question B-10. Additional corrections
were made for three impoundments with unusually large distances between the water table and
their impoundment liquid levels.
A.2.6 Quality Assurance/Quality Control
Extensive and rigorous QA/QC procedures were developed and followed throughout the
data entry process. QA/QC procedures for map and diagram data have been described in the
sections above. To achieve a 100-percent check for data entry, all survey data that were manually
entered into the survey entry database from the hard-copy surveys were double-extracted and
entered independently by two different staff members. To accommodate double-extraction/
double-entry, the data entry database contained duplicate tables for every data element as well as
duplicate entry forms. Once both entries were complete, the two files were electronically
compared, and, using the hard copy survey, a third staff member reconciled any differences.
Other manually entered data were checked 100 percent.
For automated data processing, the data extraction/processing system was thoroughly
validated before use. This involved manually checking enough of the data (usually 5 percent to
10 percent) to ensure that the system functioned properly. When conducting such checks, the QC
procedures required that each unique calculation or data combination be checked at least once. In
addition, a version control system was employed to ensure data integrity and that each analysis
conducted with the most recent dataset. Detailed records were kept of every QC check, and these
were reviewed during a final QA audit of the data entry process.
A.3 Collection of Supplementary Data
Secondary data sources included U.S. Census GIS data (used to supplement survey
information on the number and location of people living around the site), GIS coverages of soils
and aquifer data, USGS topographic maps, and river flow data from EPA's Basins database.
These data were collected and used to provide more consistency and completeness for key data
elements, or to provide data not directly available from the survey (e.g., population data).
A-21
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March 26, 2001 Appendix A
A.3.1 Development of Supplementary Spatial Data
A geographic information system was used to digitize residence and well locations from
the marked topographic maps requested in question B3 of the Part B of the long survey. Question
B3 asked the survey respondents to mark wells, residences, and schools within a 2-kilometer
radius of their surface impoundments on a USGS topographic map that was included with the
survey form (see Attachment Bl). Because these maps were returned unmarked (or not returned)
by a significant number of respondents and because the survey did not ask for population data,
the GIS was used to supplement these data with U.S. Census data. In addition, the GIS was used
to collect spatial data on the presence of waterbodies, wetlands, and managed areas with 2 km for
the ecological risk assessment.
A. 3.1.2 Data Processing and Spatial Analysis. Out of the total 157 facility sites with
impoundments in-scope for the long survey (i.e., those with chemicals or pH of concern), a total
of 153 returned maps with the survey, including 150 sites in the continental U.S., 2 sites in
Alaska, and 1 site in Puerto Rico (four sites were determined to have missing geographic data).
The geographic analysis was carried out for these sites to develop the sample data necessary to
develop the following statistics about the distribution of wells, residences, population, and
schools for impoundments with chemicals or pH of concern:
• Estimated number of groundwater supply wells, broken out by distance (0-150,
151-500, 501-1000, and 1001-2000 meters) from the impoundments, and cross
tabbed by use (public, private drinking water, irrigation, livestock watering, don't
know, other).
• Estimated number of residences, broken out by distance (0-150, 151-500,
501-1000, and 1001-2000 meters) from the impoundments.
• Estimated number of schools, broken out by distance (0-150, 151-500, 501-1000,
and 1001-2000 meters) from the impoundments.
• Estimated number of people, broken out by distance (0-150, 151-500, 501-1000,
and 1001-2000 meters) from the impoundments.
A simple Arc/Info distance function was used to process the school data, but the remaining
questions required pre-processing of the digitized survey data and the 1990 U.S. Census data.
Overlay Processing of In-Scope Impoundments. To develop the best estimate of wells,
residences (households), and population surrounding the impoundments with constituents used
census coverages and data were used to: (1) provide an indicator of average household size;
(2) estimate the number of private drinking water wells, and (3) provide population data for
population estimates. Census coverages and corresponding data were obtained via ftp download
from the EPA server in Research Triangle Park. Additional processing was carried out to link
block and block group variables with block coverages. Census data were not available for Puerto
Rico, so the wells and residence analyses utilized only feature data on the map supplied by the
survey respondent and no population data could be estimated.
A-22
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March 26, 2001 Appendix A
The most critical data processing steps for census/feature data analyses for each of the
in-scope surface impoundment (excluding Puerto Rico) were as follows:
• Step 1. Create a set of buffers at distances of 150, 500, 1000 and 2000 meters,
respectively, from the impoundment boundary.
• Step 2. Overlay buffers on census block group coverages to create new coverage
of census blocks split by distance buffers, retaining the value of the original area
of the census block for later analysis. Steps 1 and 2 were carried out using
procbloc.aml. The resulting coverages were named BLR, e.g. BLR12341.
• Step 3. Overlay BLR coverage with RECP_PTS coverage and summarize number
of receptor points per polygon, using rcp_over.aml.
• Step 4. Overlay BLR coverage with WELLS coverage and summarize number of
wells per polygon, by welltype, using well_over.aml.
• Step 5. Populate new overlay coverages with census, receptor and well data, using
linkwells.aml andblrprep.aml.
Figure A-2 shows an example of a BLR coverage, with surface impoundments, receptors and
wells.
A.3.1.2 Dasymetric Mapping and Analysis Procedures for Human Receptor Data. As
previously noted, the computation of distances for schools was straightforward because no
census data were required. A GIS distance function (Arc/Info's NEAR command) was utilized to
compute the distance of each school from each surface impoundment at the respective site.
Distance were then categorized as belonging to Ring 1 (0 - 150m), Ring 2 (150.1 - 500m), Ring
3 (500.1 - 1000m) or Ring 4 (1000.1 - 2000m). Data were compiled in a file with the data
structure shown in Table A-6.
A similar procedure was used to compute distances to marked wells, except that wells
were broken out by well type. An additional analysis of wells was conducted, utilizing census
data to provide supplemental data on the number of drinking water wells in the vicinity of a
surface impoundment. The initial well distance file that was generated contained information
about the distance of each marked well to each surface impoundment. The structure of this file is
shown in Table A-7.
A-23
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March 26, 2001
Appendix A
•v BLR, Receptor and Well Coverages
R eceptors
Surface Impoundment
CH
V Wells
BLR20682
Figure A-2. Overlay of census blocks and distance rings
with wells and receptors.
Table A-6. Table Structure for School Data
Variable Name
FACJD
IMPJD
RINGJD
RINGDIST
AREAUNIT
NMSCHOOL
Description
Unique facility ID
Unique impoundment ID
Ring 1,2, 3 or 4
Ring distance of 150, 500, 1000 or 2000
Meters
Number of schools within specified ring
Data Type
Text
Integer
Integer
Integer
Text
Integer
A-24
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March 26, 2001
Appendix A
Table A-7. Table Structure for Well Distance Data
Variable Name
FACJD
IMPJD
WELLJD
DIST
XCOORD
YCOORD
WELLTYPE
Description
Unique facility ID
Unique impoundment ID
Unique well ID: FAC_ID plus coverage ID
Distance from surface impoundment boundary
X-coordinate in j State Plane meters
Y-coordinate in State Plane meters
Type of well
Data Type
Text
Integer
Integer
Float
Float
Float
Integer
Census data were used to develop estimates of population and number of residences for
each geographic unit that fell within the 2-km range of each eligible surface impoundment. The
geographic unit of analysis was the result of a geographic overlay of census blocks and distance
rings (at distances of 150 m, 500 m, 1,000 m, and 2,000 m from the surface impoundment,
respectively). In some cases, the unit of analysis was an entire census block; in other cases,
where a distance ring bisected it, the unit of analysis was a partial census block.
Dasymetric Mapping. Dasymetric mapping techniques were used to obtain a more
accurate estimate of population and residence numbers than are possible by more traditional
methods. Although the census block is the smallest geographic unit used by the U.S. Census, it
is sufficiently large enough that variations in the numbers of people and residences within the
block are obscured. This does not pose a problem when the entire block is the unit of analysis.
With partial blocks, however, population and residence numbers for the entire census block must
be reassigned to the partial block, keeping the block totals constant. Normally, this is done by
prorating the block variables (such as population) by the area of the new, or partial block unit,
that is, if the partial block was 75 percent of the size of the original, then 75 percent of the
population would be assigned to that unit. The problem with this method is that, especially in
rural areas, residences may be widely scattered and there may be large areas that are assigned a
population when, in fact, they have none. The reverse is also possible, population undercounts in
densely populated areas.
Dasymetric mapping uses supporting information about the distribution of a phenomenon
to provide a more accurate representation of a (map) surface than that provided by standard data
collection units, such as census blocks or block groups. In this case, the supporting information
comes from the residences that were digitized from maps returned by the survey respondents.
This information can be used to provide a better characterization of high and low density areas
within the census block and to develop more accurate counts for enumeration units split by the
150, 500, 1,000 and 2,000 m rings. In other words, the presence of digitized points, and
decisions made about their accuracy and currency, were used to weight the population and
residence number estimations.
A-25
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March 26, 2001 Appendix A
Assumptions. Three different methods of geoprocessing and computation were
developed, using assumptions based on the date of the map and the accuracy of the maps
provided by the survey respondents. Assumptions:
• If map predates 1990 and no residences were marked on the map by respondent,
then the 1990 census is the most accurate source of population and residence data.
• If the map predates 1990 and residences were marked on the map by respondent,
the digitized map data represents the most accurate source of population and
residence data in non-urban areas.
• If the map date is later than 1990, the digitized map data represents the most
accurate source of population and residence data in non-urban areas, whether or
not residences were marked on the map by respondent.
• Since individual receptor points are not present in urban areas, 1990 census data
provide the most accurate source of population and residence data in those areas.
Decision Rules. Using the assumptions stated above, a decision tree, based on
(1) presence of urban areas on map, (2) date of source map, and (3) whether respondent had
marked residences on the map was used to determine which one of three processing and analysis
routines would be used to most accurately estimate the population and number of residences
within the 2-km surface impoundment buffer area. This decision tree is reflected in the
Figure A-3.
Before implementing the decision tree, the map for each surface impoundment (n=517),
was checked for: (1) presence of urban polygons, (2) map date, and (3) marked residences on
map. Based on this check, one of the following three routines was implemented.
Routine A
This routine was used when no urban areas were contained in the geographic data and the
map data were assumed to be more accurate than the census data. It is the simplest of the three
routines. The number of receptor points in each geographic unit were counted. This provided
the value for estimated number of residences. This value was then multiplied by the average
number of people per housing unit, at the block group level (hereafter referred to as the block
group housing unit size), to obtain the estimated number of persons.
Routine B
This routine was used when the map from which receptor points were digitized predated
the 1990 census and there were no residences marked on the map by the respondent. Census data
were assumed to be the most accurate source of information and census population totals for each
block were held constant. However, the distribution of digitized points was used to weight
population and residence numbers for partial blocks.
For census blocks that were not split by a distance ring (hereafter referred to as whole
blocks), the estimated number of persons was simply the census population value for that block.
A-26
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March 26, 2001
Appendix A
Does the site 2km buffer contain any urban areas?
Map Date?
NO
Residences
marked
on map?
NO
YES
Routine
A
Routine
B
Routine
C
Figure A-3. Dasymetric procedure for integrating survey and U.S. Census data.
The estimated number of residences was computed by dividing the estimated number of persons
by the block group housing unit size.
For census blocks that were split by a distance ring (hereafter referred to as partial
blocks), the number of digitized receptor points was counted. If the partial block contained no
receptor points, the block population was multiplied by the area proportion, and a percentage
value was obtained by dividing the area of the partial census block by the area of the whole
census block. The resulting value was the estimated number of persons for that partial block.
The estimated number of residences was computed by dividing the estimated number of persons
by the block group housing unit size.
For partial blocks that contained digitized receptor points, a revised block population
value was obtained by multiplying the block population by the area proportion. Then, the total
number of receptor points in the whole block was multiplied by the block group housing unit
size. If that value exceeded the revised block population, the revised block population was
divided by the number of receptor points in the block to come up with an estimated block
housing unit size. This value was then multiplied by the number of receptor points in the partial
A-27
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March 26, 2001 Appendix A
block to determine the estimated number of persons. The estimated number of residences was
equal to the number of digitized receptor points.
If the product of the number of receptor points in the whole block and block group
housing unit size was less than the revised block population, the ratio of partial block receptor
points to whole block receptor points was multiplied by block population to get the estimated
number of persons. This value was divided by block group housing unit size to obtain the
estimated number of residences.
Routine C
Routine C was used when the geographic data contained urban areas (with the exception
of pre-1990 map dates with no residences marked on the map). The digitized receptor data were
assumed to be accurate. However, census data were used in polygons with no digitized receptor
points because areas delineated urban on topographic maps do not show individual residences.
For partial and whole blocks with digitized points, the number of receptor points were
counted to estimate the number of residences. This value was then multiplied by the block group
housing unit size to estimate population.
For whole blocks with no digitized receptor points, the estimated number of persons was
the census population value for that block. The estimated number of residences was computed
by dividing the estimated number of persons by the block group housing unit size. For partial
blocks, the population value was the product of the area proportion and census block population.
This value was divided by the census block group housing unit size to obtain estimated number
of residences.
Routines A, B and C were incorporated into the program dasyprog.aml. After this
program was run, the estimated number of residences was used to obtain an estimate of the
number of drinking water wells, based on census data (census wells). Where the ratio of
drinking water wells to housing units at the census block-group level was greater than 0.5, this
ratio was multiplied by the estimated number of residences to obtain this value. Because those
data were more complete (many respondents did not mark drinking water wells), the census wells
were used in subsequent analyses in all cases except where marked private wells drinking-water
wells were greater than the census well count.
The data obtained from the overlay analysis and dasymetric mapping procedures was
compiled in a table with the structure shown in Table A-8.
A. 3.1.3 Screening for Ecological Risk Modeling. GIS screening of sites with in-scope
surface impoundments was conducted to determine the level and type of ecological risk
assessment modeling. A series of GIS overlay procedures was developed and employed to
examine spatial relationships between each surface impoundment site and (1) managed areas
(such as parks and wildlife preserves), (2) land use categories, (3) permanently flooded
woodlands, (4) Bailey's ecoregions, (5) fishable water bodies, (6) soils, and (7) groundwater
geology. Attachment B4-3 contains a more detailed description of ecological screening overlay
procedures.
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March 26, 2001
Appendix A
Table A-8. Table Structure for Population, Residence, and Well Data
Variable Name
FACJD
IMPJD
PUBW_1
PUBW_2
PUBW_3
PUBW_4
PRIDW_1
PRIDW_2
PRIDW_3
PRIDW_4
IRRW_1
IRRW_2
IRRW_3
IRRW_4
COWW_1
COWW_2
COWW_3
COWW_4
DKW_1
KW_2
DKW_3
DKW_4
OTHERW_1
OTHERW_2
OTHERW_3
OTHERW_4
CENPRW_1
CENPRW_2
CENPRW_3
CENPRW_4
RES_1
RES_2
RES_3
RES_4
POP_1
POP_2
POP_3
POP_4
Description
Unique facility ID
Unique impoundment ID
No. public GW wells 0 - 150m
No. public GW wells 151 - 500m
No. public GW wells 501 - 1000m
No. public GW wells 1001 - 2000m
No. private DW GW wells 0 - 150m
No. private DW GW wells 151 - 500m
No. private DW GW wells 501 - 1000m
No. private DW GW wells 1001 - 2000m
NO. irrigation GW wells 0 - 150m
No. irrigation GW wells 151 - 500m
No. irrigation GW wells 501 - 1000m
No. irrigation GW wells 1001 - 2000m
No. livestock GW wells 0 - 150m
No. livestock GW wells 151 - 500m
No. livestock GW wells 501 - 1000m
No. livestock GW wells 1001 - 2000m
No. DKGW wells 0- 150m
No. DK GW wells 151 - 500m
No. DK GW wells 501 - 1000m
No. DK GW wells 1001 - 2000m
No. other GW wells 0 - 150m
No. other GW wells 151 - 500m
No. other GW wells 501 - 1000m
No. other GW wells 1001 - 2000m
No. 1990 census private GW wells 0 - 150m
No. 1990 census private GW wells 151-500m
No. 1990 census private GW wells 501 - 1000m
No. 1990 census private GW wells 1001 - 2000m
Estimated residences 0 - 150m
Estimated residences 151 - 500m
Estimated residences 501 - 1000m
Estimated residences 1001 - 2000m
Estimated population 0 - 150 m
Estimated population 151 - 500m
Estimated population 501 - 1000m
Estimated population 1001 - 2000m
Data Type
Text
Integer
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
A-29
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March 26, 2001 Appendix A
A.3.2 Surface Water Distances and Flow Data
Because the distance to surface water responses (survey question B12) were incomplete
and did not include surface water flow data needed for the risk assessment, it was necessary to
supplement these data with data collected from other sources. This data collection effort included
largely a manual review of topographic maps and gathering of flow data from EPA's BASINS
database.
A.3.2.1 Distance to Nearest/Nearest Waterbody and Ground Water Flow. The nearest
fishable waterbody (FWB) in any direction and the nearest, downslope FWB (stream, lake, or
pond) were identified using survey responses, site maps, atlases, topographical maps, and aerial
photographs. FWBs were selected based on the following criteria:
• Lakes beyond the facility boundary but within 2 kilometers of the SI
• Streams that extended beyond the property boundary
• Streams that were order 3 or larger (The order of the stream was determined by
tracing the convergence of tributaries with order 1 assigned to the furthest
upstream segment indicated on the 1:24,000 topographic map (both ephemeral
and perennial steams were assigned order 1). The streams were traced also using
state atlases, hydrologic unit maps, and basin maps on the EPA "Know Your
Watershed" web pages
• Waterbodies that did not meet the above criteria, but were closer to the SI than
other waterbodies and were specifically mentioned by the respondent in Part B of
the survey.
To determine the potential for a groundwater migration pathway from the SI to the FWB
the following criteria were used:
• Respondent's geology summary from the B-form of the survey
• Regional geology information
• Topography as indicated on 1:24,000 or other available topographic maps.
In most cases the topography and stream flow were used as an indication of shallow
groundwater flow to evaluate the potential contamination pathway to the FWB. In areas where
there was the potential for fracture flow in shallow, hard-rock aquifers or in karst formations, it
was automatically assumed that transport to the FWB was possible. Regional geology also was
considered. Additional information was obtained from the following sources if supplemental
information was required:
• DRASTIC: A Standard System for Evaluating Ground Water Pollution Potential
UsingHydrogeologic Settings, Kerr ERL, Table 8, p.9 (Aller et al. 1987).
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March 26, 2001 Appendix A
• Hunt, 1974, Natural Regions of the United States and Canada, map of surface
deposits, p. 122.
• USGS, 1984. Geologic Map of the United States
• USD A, state soil surveys as available
• Professional judgment.
Distances from the SI to the FWBs were typically measured using USGS 1:24,000
topographic maps. A 1:24,000 scaled rule was used for measurements, eliminating the need for
conversions. Some facility packages did not include USGS maps, and a calculated scale was
used.
Later analysis using generally newer aerial photography data (1977, 1997, 1998) than the
USGS topographical maps indicated that some streams and lakes had been missed or were no
longer present. The table was corrected based on this information. Independent, duplicate
analysis was performed using the original assessment results for each facility as a 100 percent
quality control check.
A. 3.2.2 Collection of Surface Water Flow Data. Flow data were collected for all
identified non-quiescent water-bodies (i.e., streams and rivers). Surface area was obtained for
quiescent water-bodies (i.e., ponds and lakes). Stream attribute data included mean flow, 7Q10
flow, and stream width. The 7Q10 flow is representative of drought/low-flow conditions. No
data were obtained for bay or ocean areas.
Three data sources were used to obtain stream data:
• EPA Office of Water. May 1996a. Database for Better Assessment Science
Integrating Point andNonpoint Sources (BASINS). EPA-823-R-96-001.
• Web pages: USGS, January 26 through 28, 2001. United States NWIS-W Water
Data Retrieval Internet Site: http://waterdata.usgs.gov/nwis-w/us/
• van der Leeden et al., 1990. The Water Encyclopedia - Second Edition: Table 3-6
Flowing Water Resources of the United States, Data Source: Keup, L.E., 1985.
Lewis Publishers, Inc., pp. 176.
EPA's BASINS model was the primary data source for 7Q10 and mean stream flow data for
approximately 219 streams. The streams were found by searching the data tables and using GIS
techniques to compare the site's latitude and longitude with the gaging station's coordinates. This
search yielded all gages within 10 miles of the facility and a manual search was performed to
narrow the list to modeled streams. The distance between the gage and the facility was calculated
from the coordinate data using a spreadsheet. This calculation was validated for two facilities (in
the Northwest and Southeast) using hand calculations and map comparisons.
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March 26, 2001 Appendix A
The USGS's NWIS-W water data and associated state geological survey web pages were
used to obtain flow data for 56 streams that did not have appropriate data in the BASINS
database. Typically, annual mean flow data were available from this source; however, only daily
mean values were available for several streams. A relative annual mean was calculated from the
daily mean values based on the data collected over the last 5 years or the available period of
record. Generally, there was not enough data to obtain a 7Q10 value, and most of the data were
not available in a format that could be downloaded into a digital file. As a result, a
representative annual 7Q10 flow for streams was not calculated using the USGS gage data.
The distance along lines of latitude and longitude from the facility to gage stations was
also provided in the tabulated results. Flow data webpages for the streams were printed and used
to check the inputs of the original data table. A quality control check was performed on
approximately six of the mean flows calculated from daily averages.
Table 3-6 Flowing Water Resources of the United States by Keup (van der Leeden et al.,
1990) was used to estimate flow data for approximately 115 streams that were not listed in
BASINS or on the USGS websites. The table correlates the stream's measured width and its
estimated mean flow. Estimates based on the Keup's data are from end-of-stream locations. If
actual data existed even many miles away (usually for large rivers) from the facility, the mean for
the gage data was also presented along with the estimated Keup flow. Interpolations from the
Keup data were independently verified.
The width of every stream was measured. At the end of the data collection activities, all
data were queried to compare measured stream widths and flows to the estimated flows from the
Keup's table. The query results showed that interpolations from the Keup data for mean annual
flow compared well with actual gage information obtained from BASINS and the USGS sources.
The estimates of the mean flow data appeared congruous for the set of streams to be modeled.
The surface areas for most of the lakes, ponds, and river inlets were measured on USGS
1:24,000 topographic maps using a planimeter. Some maps were of a different scale, and the
planimeter was calibrated accordingly. Some waterbodies had areas below the limit of the
planimeter. The areas of these waterbodies were estimated by multiplying the measuring length
and width to find the square area. Some inlet areas were considered lake-like and areas were also
determined for these waterbodies. The areas of approximately six, randomly selected
waterbodies were independently checked for accuracy.
A.4 Data Processing
Data processing includes the calculations, conversions, and transformations necessary to
prepare the basic survey data in the data entry database (described in Section A.2), for additional
exploration and analysis. Data processing activities produced three primary products:
• Consolidated database, which is similar in basic structure and content as the data
entry database except that units have been standardized and initial data cleaning
(e.g., correction of skip pattern errors) has been conducted.
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March 26, 2001 Appendix A
• Risk assessment input database, which contains the chemical concentrations and
associated surface impoundment characteristics necessary for modeling risks from
surface impoundments.
• Derived variables, which were developed from survey data, risk assessment
results, or combinations of these for estimating population characteristics using
the statistical methodologies described in Section A.5.
Each of these processing activities is described in greater detail below.
The automated programs developed to create each of these data products were subjected
to rigorous and complete QA/QC protocols. For all automated data processing, the data
extraction/processing system was thoroughly validated before use. This involved manually
checking enough of the data (usually 5 percent to 10 percent) to ensure that the system
functioned properly. When conducting such checks, the QC protocol required that each unique
calculation or data combination be checked at least once. In addition, a version control system
was employed to ensure data integrity and that each analysis conducted with the most recent
dataset.
A.4.1 Consolidated Database
The consolidated database is intended to serve as the final archive of survey data and
contains the data in a form that makes it makes it useable for future analyses. To achieve these
objectives, the consolidated database was designed to be consistent with the following criteria.
• Accurate reflection of survey responses, including margin notes as possible.
• Cleaning of conflicting responses and correction of skip pattern errors by
respondents completing the survey.
• Conversion of quantitative data to standard units to enable meaningful analyses to
be conducted.
• Collapse of chemical data from 8 tables in the data entry database into a single
table in the consolidated database to allow easy comparison between the different
sampling points (influent, effluent, and within the impoundment) and media
(wastewater, sludge, leachate, air) requested by the survey.
Processing of the survey data in accordance with the last two criteria presented the
biggest challenge, both from a programming and QA perspective. The chemical data from survey
questions C23 and C24, required the most complex processing to convert units, calculate
concentrations and mass per unit time values when possible, average different sampling periods,
and, for wastewater influent only, combine data across multiple influent points. Over 40 different
units used by survey respondents had to be converted to standard units for wastewater, leachate,
sludge, and air. To document this process, Attachment A6 provides the data processing
algorithms and unit conversions used for processing the chemical data. Each of these algorithms
A-33
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March 26, 2001 Appendix A
was checked manually during QC for correct program functioning. Records of these checks are
available and archived and were subjected to a final GA audit.
To find conflicting data and skip pattern errors, SQL queries were performed based on the
structure of the original survey form. For example survey question C2a asks if the impoundment
has ceased receiving wastes since June 1, 1990, based on the response to this question the
respondent should have or should not have responded to questions C2b, C2c, and C27a. By
searching for instances that the response to question C2a was "no" or "don't know", but any one
of C2b, C2c, or C27a is answered, or conversely if the response to question C2a was "yes", but
there were no responses for C2b, C2c and C27a, problems were identified and rectified by
looking at the responses to the questions as well as any margin notes made by the respondent. If
the respondent clearly indicated that the impoundment was closed, but failed to answer the
follow up questions, then non response codes could be entered as appropriate. In a couple of
cases, the response to C2a was "yes", but the margin note for C27a clearly indicated that the
impoundment was not closed. In this case the C2a response was rectified with the C27a margin
note, and the change was noted in the C2a margin note. There also were instances when
respondents answered all questions in some manner even if a response was not required. These
spurious responses remain in the original data entry database, but were not transferred to the
consolidated database.
Values for any survey response that could result in values reported with varying units
were converted to a standard set of units. The only exception to this is the liner thickness
response to question C12. Because liner thicknesses can vary greatly in magnitude by liner type,
the values were transferred as provided with the actual survey units listed in the field provided.
Similarly the chemical concentration data required conversion to a standard set of units as well as
calculating concentrations and mass per unit time values, and combining data across multiple
influent points for survey question C24a. Processing of the chemical data would also vary based
on the type of data provided. Processing for concentration values, mass per unit time values,
chemicals present with quantity unknown, non-detects, etc all required slightly different
processing. A6-1 is an algorithm for the processing of each type of chemical data by survey
question. This algorithm was used to document the processing as well as being used for quality
control. The conversion functions written to convert survey data to a standard set of units are
provided in A6-2.
Attachment A7 provides the basic design documents for the consolidated database. As
described in section A.2 for the data entry database, these include entity relationship diagrams, a
data dictionary, and copies of each coding table.
A. 4.2 Risk Assessment Input Data
The risk assessment input database includes all of the chemical concentration data needed
to run the risk assessment models. Design documents for this database, including a data
dictionary and coding tables, are provided in Attachment A8. The risk assessment input database
was populated in accordance with the risk assessment Technical Plan (see Appendix C), and
included the following conventions developed to help reduce missing data and to ensure that the
screening analysis was adequately protective.
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March 26, 2001 Appendix A
• Values below detection limits were entered at the detection limit given in the
survey. Where the detection limit was not specified, a lookup table of default
detection limits was used to fill a detection limit value in the risk assessment
database.
• A nearest neighbor imputation methodology was applied to develop surrogate
concentration data were chemicals are expected to be present, but quantities are
unknown.
• Where sludge data were not available, partition coefficients were used to estimate
sludge concentrations from wastewater concentrations
Each of these procedures is discussed in more detail in the following sections.
A. 4.2.1 Detection Limits. Where the survey respondent entered a concentration value as
less than a detection limit, for example "< 0.05 mg/L", a value at the detection limit (i.e., 0.05
mg/L) was placed in the risk assessment input database. This protective convention was adopted
for the screening risk assessment to ensure broad coverage in cases where a chemical could be
just below the detection limit. To ensure that this assumption is not overly conservative, chemical
concentrations still exceeding risk criteria after the final phase of the risk analysis were examined
as to their source (i.e., detection limit, surrogate) (see Section 3 and Appendix C).
For cases where the survey did not provide a detection limit (e.g., specified "not detected"
or "ND"), a lookup table of default detection limits was developed considering analytical
methods likely to be used for wastewater samples. The primary sources are summarizes as
follows.
• Wastewater. EPA method 1624 and 1625 were selected because the methods are
designed to meet the requirements of NPDES under 40 CFR parts 136.1 and
136.5. For inorganics (metals) standard methods for inductively coupled plasma
(TCP) and cold-vapor atomic adsorption (CVAA) analyses were used. When
detection limits for organic constituents were not available from these methods,
the EPA 600 series for municipal and industrial wastewater was used. For any
remaining constituents without detection limits, SW-846 EPA 8000 series was
used. Finally, if no method was available, then a detection limit was pulled from
the available detection limits in the survey database.
• Sludge. For the organics SW-846 EPA 8000 series was used. For method 8021,
the method provided an estimated quantitation limit (EQL) of 0.1 mg/kg, and this
value was used for applicable constituents. For 8081, a factor for sludge was
calculated into the detection limit as noted in the spreadsheet. Finally, if no
method is referenced, then the detection limit was pulled from the available
detection limits in the survey database.
• Air. Detection limits in air were taken from the EPA report Ambient
Measurement Methods and Properties of the 189 Clean Air Act Hazardous Air
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March 26, 2001 Appendix A
Pollutants. When a method is not referenced, then the detection limit was based
on best professional judgment.
All detection limits were multiplied by a factor often to account for interferences. The final Ix
and lOx values for wastewater, sludge, and air are provided in Attachment A-9 (Tables A-9-1,
A-9-2, and A-9-3).
A.4.2.2 Surrogate Values. The Surface Impoundment Study Technical Plan for Human
Health and Ecological Risk Assessment (Attachment C) specifies that in cases where the
presence of a chemical in an impoundment can be inferred, but it is not possible to quantify a
value, a value from a similar impoundment will be used to represent a likely concentration. These
surrogate values were developed using a nearest neighbor imputation method which made it
possible to maximize the use of presence information in the survey. Presence was inferred, and
surrogate concentrations were sought, in three cases: (1) where the respondent had checked the
"present but quantity unknown" (PQU) flag, (2) where the respondent had entered a chemical but
provided no value (and did not check PQU), and (3) where chemicals were reported in
wastewater effluent (to infer presence within the impoundment).
The imputation methodology is picture in Figure A-4 and described in the following text.
Note that because detection limits were decided to be valid representations of concentrations in
the impoundments for this risk analysis, the detection limit values described in Section A.4.2.1
were available and used for surrogates. All surrogate data processing was done on the constituent
level and the maximum of the surrogate data gets filled into the CHEM_CONC Table in the risk
assessment database with "Surrogate" marked as true.
The imputation methodology employed a decision framework that was programmed into
a data processing system to implement the methodology. The theme throughout the process is to
find the most similar impoundment possible within the survey database that had data for the
chemicals without values. Steps in the process include answering the following questions:
1. Are there any other impoundments at the same facility with data for the constituent?
Yes
la. Are there any impoundments with the exact same treatment processes?
Yes - fill surrogate data - finished
Ib. If the impoundment requiring surrogate data is aerated, are there any other
impoundments which are aerated?
Yes - fill surrogate data - finished
Ic. Are there any impoundments which perform the same function (treatment or
non-treatment only)?
Yes - fill surrogate data - finished
2. Are there any other impoundments with the same 6 digit SIC code with data for the
constituent?
Yes
2a. Are there any impoundments with the exact same treatment processes?
Yes - fill surrogate data - finished
A-36
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Surrogate Processing Flowchart
Similar SI characteristics
Processing
Are there any
impoundments with \ Yes
data at the same
facility?
characteristics
similar?
impoundments with
data with the same 6
requiring surrogate
Fill surrogate data
Are SI
characteristics
similar?
using maximum of
impoundments with
data with the same 4
Are SI
characteristics
similar?
Are there any
impoundments with
data with the same 2
igit SIC group?
Add constituent to
Chem NoData Table
oes the SI have
identical treatment
processes?
oes SI have the
same function?
(treatment/non-
treatment only)
* Note all processing is done at the constiuent level
Figure A-4. Decision tree for identifying surrogate data for risk assessment
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March 26, 2001 Appendix A
2b. If the impoundment requiring surrogate data is aerated, are there any other
impoundments which are aerated?
Yes - fill surrogate data - finished
2c. Are there any impoundments which perform the same function (treatment or
non-treatment only)?
Yes - fill surrogate data - finished
3. Are there any other impoundments with the same 4 digit SIC code with data for the
constituent?
Yes
3 a. Are there any impoundments with the exact same treatment processes?
Yes - fill surrogate data - finished
3b. If the impoundment requiring surrogate data is aerated, are there any other
impoundments which are aerated?
Yes - fill surrogate data - finished
3c. Are there any impoundments which perform the same function (treatment or
non-treatment only)?
Yes - fill surrogate data - finished
4. Are there any other impoundments with the same 2 digit industry group with data for the
constituent?
Yes
4a. Are there any impoundments with the exact same treatment processes?
Yes - fill surrogate data - finished
4b. If the impoundment requiring surrogate data is aerated, are there any other
impoundments which are aerated?
Yes - fill surrogate data - finished
4c. Are there any impoundments which perform the same function (treatment or
non-treatment only)?
Yes - fill surrogate data - finished
5. If there are still constituents requiring surrogates which can not be matched in steps 1 to
4, then add the constituents to the Chem_NoData table.
A.4.2.3 Estimating Sludge Concentrations from Wastewater Concentrations. When there
is not a sludge concentration provided in the survey, but there is sludge within the impoundment,
a sludge concentration was estimated from using waste-water partition coefficients (Kdw) for
metals and a soil organic carbon-water partition coefficient (Koc) for organic constituents, along
with total suspended solids (TSS) data pulled from the study survey. This approach accounts for
contaminants sorbed to TSS, which is necessary when using total wastewater concentrations
(versus dissolved).
The equations to be used are.
Kd (metals):
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March 26, 2001 Appendix A
Sludge_Conc = WW_Conc*([Kdw_L/kg]/(l+([Kd_L/kg]*([TSS_WW]/1000000))))
where:
WW_Conc is the wastewater concentration within the SI in mg/L
Kdw_L/kg is the 50th percentile waste-water Kdw value in L/kg
TSS_WW is the TSS value in mg/L.
Koc (organics):
Sludge_Conc = WW_Conc*(([Koc]*foc)/(l+(([Koc]*foc)*([TSS_WW]/1000000))))
where:
WW_Conc = wastewater concentration within the SI in mg/L
Koc = soil organic carbon / water partition coefficient in L/kg
foe = fraction organic carbon (waste solids)
TSS_WW = TSS value for wastewater in mg/L.
These two equations were derived from the following equation:
C_sol (mg/kg) = C_ww (mg/L) * { Kdw/ (1+Kdw [TSS])}
where:
C_sol = solids concentration (sorbed, mg/kg)
C_ww = measured wastewater sample contaminant concentration (total, mg/L)
Kdw = waste-water partitioning coefficient = Koc*foc for organics (L/kg)
TSS = total suspended solids concentration (kg/L = g/cm3).
Total Suspended Solids (TSS). TSS values were obtained from the SI survey database
(question CIS) using the following hierarchy:
1. Use wastewater within the impoundment TSS value (WW_TSSV)
2. Use wastewater within the impoundment Total Solids value (WW_TSOLV)
3. Use wastewater within the impoundment MLSS value (WW_MLSSV)
4. Use wastewater within the impoundment MLVSS value (WW_MLVSS)
5. Use wastewater within the impoundment Biomass Concentration value
(WW_BIOV)
6. Use wastewater influent TSS value (INF_TSSV)
7. Use wastewater influent Total Solids value (INF_TSOLV)
8. Use wastewater influent MLSS value (INF_MLSSV)
9. If still no data, use IWAIR default of 0.2 g/L (200 mg/L)
Fraction Organic Carbon (foe). With respect to foe, some correlations developed for
biomass sludge in activated sludge systems suggest that an foe around 0.7 would be reasonable.
Given that MLVSS is a measure of solids that volatilize at about 550 degrees centigrade, it is
also reasonable to estimate fraction organic carbon (foe) in wastewater solids using the following
equation:
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March 26, 2001 Appendix A
foe = MLVSS / (TSS or MLSS)
SI Survey data (MLVSS/TSS) that can be used to estimate foe for wastewater solids are
limited to 99 pairs of MLVSS/TSS or MLVSS/MLSS data for influent, effluent, and wastewater
in the impoundment (Table A-9). Review of these data shows little difference between the
different sampling points and limited variability (overall coefficient of variation = 0.3). Based on
these data the median fraction organic carbon (foe) value of 0.7 (70 percent organic carbon) was
used as a typical value.
Table A-9. Summary Statistics: MLVSS/TSS
Medium
wastewater
influent
effluent
all
n
37
30
32
99
mean
0.68
0.61
0.71
0.67
StdDev
0.16
0.28
0.15
0.20
cv
0.24
0.46
0.20
0.31
min
0.20
0.03
0.32
0.03
10th
%ile
0.46
0.12
0.51
0.32
median
0.71
0.71
0.70
0.70
90th
%ile
0.82
0.89
0.88
0.86
max
0.88
0.93
1.00
1.00
StdDev = Standard deviation.
CV = Coefficient of variation (StdDev/mean).
Partition Coefficients for Organics (Koc). Soil organic carbon-water partition
coefficients (Koc values) were extracted from the following readily available sources (listed in
order or preference):
• IWEM model datafiles (178 values). This will ensure consistent Koc values with
the groundwater modeling results described in Appendix C. IWEM Koc values
are reported to be collected from Kollig et al. (1993).
• Kollig et al. (1993; 2 values), the EPA ORD reference containing peer-reviewed
Koc values used in EPACMTP and IWEM.
• Superfund Chemical Data Matrix (SCDM; 29 values). Well-referenced EPA
Superfund values used in Hazard Ranking System (HRS) (U.S. EPA, 1996b).
Available online.
Values were found from these sources for most of the study organic chemicals. Koc
values for nine study constituents were developed as follows:
• Extract log octanol / water partition coefficient (log Kow) from Hansch et al.
(1995).
• Use following equation to calculate log Koc values from log Kow :
log Koc = log Kow+ 0.32.
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March 26, 2001 Appendix A
This equation was used in HWIR and in Kollig et al. (1993) to calculate Koc values.
The final Koc values used for sludge estimatation methodology as well as for the
groundwater pathway exposure modeling are provided in Attachment A9. As shown above, Koc
x foe was used to estimate waste-water partition coefficients (Kdw values) for organic
constituents in the sludge estimation methodology. The two most significant uncertainties in this
assumption are:
• the accuracy of applying soil Koc values to wastes
• limited data on waste organic carbon content.
Depending on waste streams, organic carbon content could contribute up to about a two-order of
magnitude uncertainty factor to the Kdw value. The magnitude and impact of uncertainty
introduced by the the applicability question is unknown.
Wastewater Partition Coefficients for Metals (Kdw). Waste solids / water Kdw values
for metals were obtained from the HWIR modeling effort (U.S. EPA, 1999c). HWIR developed
distributions from collected literature values for soil, sediment, suspended matter, and wastes.
For wastes managed in surface impoundments, HWIR uses metal partition coefficients (Kd
values) collected for suspended matter in surface water bodies. The distributions were based on
collected data or, for metals where data were inadequate, using a regression equation relating soil
and suspended matter log Kd values collected for other metals. These data show that suspended
matter tends to have 2 to 3 times the affinity for metals than soil. This has been attributed to the
higher surface area and organic carbon content of suspended particulate matter, which are also
characteristics of solids in many industrial surface impoundments. The distributions for metals
are provided in Attachment A9.
Significant uncertainties associated with the wastewater partition coefficients for metals
include:
• Literature values are not a random, nonbiased sample and thus may not
adequately represent the true distribution of partition coefficients.
• The accuracy of applying soil data to suspended solids; r2 for the HWIR soil /
supended matter regression equation is 0.37. However, the calculated values
appear to be roughly in line with the measurements collected from published
literature for other metals.
• The accuracy of applying surface water suspended solids data to waste solids.
The magnitude and impact of these uncertainties are uncertain in themselves, but, given the
variability in partition coefficients, could be several orders of magnitude for a particular metal in
a particular impoundment.
A-41
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March 26, 2001 Appendix A
A.4.3 Derived Variables for Exploration and Analysis
Both the survey findings presented in Chapter 2 and section A.5.2 of this attachment, and
the risk results provided in Chapter 3 required weighting up to the entire population of facilities
represented by the survey so that national level observations and conclusions could be made
about nonhazardous industrial surface impoundments. This required development of derived
variables and populating them from the surface impoundment database and the risk results. As
with the other database discussed above, this was accomplished using automated data processing
programs that were subjected to rigorous, complete QA/QC protocols to ensure that the programs
are functioning as designed (i.e., all algorithms and calculations were hand-checked for each
unique data situation).
Attachment A10 includes detailed specifications, by report question and variable, used to
develop and check these derived variables. In each case, the source and destination of each
variable is included in these tables, which are organized by section Chapter 2, Appendix B, and
Appendix C) and variable level (facility or impoundment).
A.5 Data Analysis Methods
This section describes the statistical methodology underlying the population estimates
computed using screener and long survey data. It is divided into two sections. The first section
discusses how the statistical analysis weights were computed to account for the sampling design
and to reduce the bias due to nonresponse. The second section discusses how these weights and
features of the sampling design were used to compute robust, design-consistent estimates of
sampling variances, standard errors, and confidence interval estimates of population parameters.
A. 5.1 Statistical Analysis Weights
The statistical analysis weights for the observational units in any probability-based
sample survey are the initial sampling weights adjusted to reduce the potential for bias due to
survey nonresponse. The initial sampling weight for each unit is the reciprocal of the probability
that the unit was selected into the sample. If each unit could have more than one linkage to the
sampling frame (or list) from which the sample was selected, the initial sampling weights must
be adjusted to compensate for this multiplicity. Finally, a model-based estimate of the
probability of responding is usually used to reduce the bias due to nonresponse. The following
sections discuss each of these steps for computing the statistical analysis weights for the Surface
Impoundment Study.
A.5.1.1 Initial Sampling Weights. As described in Section A. 1.1, major differences in the
sources and availability of sampling frame data led to the definition of three primary sampling
strata based on the facility's regulatory status under the Clean Water Act:
For direct discharge facilities, EPA constructed an essentially complete sampling frame of
43,050 facilities from the NPDES permits in the EPA's Permit Compliance System (PCS)
database. EPA partitioned the sampling frame into three primary sampling strata, defined as
follows:
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March 26, 2001 _ Appendix A
1. Facilities in high-priority SICs (26, 2819, 2824, 2834, 2869, 2897, 2911, 30, 33,
or 36)
2. All other facilities with in-scope SICs
3. The six pilot study facilities.
Substrata were defined based on SIC codes resulting in a total of 15 sampling strata. A stratified
simple random sample of 2,000 facilities was selected from the 15 sampling strata, and the six
pilot study facilities were retained with certainty.
For zero discharge facilities, a sampling frame of 5,807 facilities was constructed from
available state data and two federal databases: EPA's Toxics Release Inventory (TRI) and the
Aerometric Information Retrieval System, Facility Subsystem (AFS). The sampling frame was
stratified into 15 sampling strata based on general categories of completeness for the different
state and federal data sources, and according to high and low priority SIC codes. A stratified
random sample of 250 facilities was selected using the same sampling rate for all but one
stratum.
Because local POTWs are the principal permitting authorities for indirect discharge
facilities, anecdotal information collected from EPA, state and local personnel, and database
information from EPA Region 7 was used to construct a sampling frame from which 35 facilities
were purposively selected.
Subsequent to selection of this sample for the screener survey, EPA determined that some
of the sample facilities were ineligible for Phase 2 of the study, and those facilities were removed
from the sample before mailing the screener surveys. For each of the 1,984 direct and zero
discharge facilities mailed a screener survey, the initial sampling weight was computed for the
j-th facility in stratum r as follows:
where
Nl(r) = Total number of facilities in stratum r, and
nl(r) = Number of facilities selected into the sample from stratum r.
The frame count, Nl(r), sample size, nl(r), and initial sampling weight, wl(j), are shown for
each stratum in Table A- 10. Sampling weights were not computed for the sample of 35 indirect
discharger facilities because the sample was purposively selected and the survey results cannot be
statistically extrapolated to any larger population.
A. 5. 1.2 Multiplicity Adjustments. The PCS data used to construct the sampling frame for
the direct discharger sample were outfall- or pipe-level records. The first step was to collapsed
the pipe-level records to the permit level by permit ID (NPID). Permits were then combined to
the facility level. Because there was no unique facility ID to guide this process, permits were
A-43
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March 26, 2001
Appendix A
Table A-10. Initial Sampling Weights for the Screener Survey
Sampling Stratum
Frame Count
Sample Size
Initial Weight
Direct Discharge Facilities
High-priority SICs:
• SIC 26
• SIC 28
• SIC 29
• SIC 30
• SIC 33
• SIC 36
Low-priority SICs:
• SIC 20-23
• SIC 24-27
• SIC 28-31
• SIC 32
• SIC 34
• SIC 35-39
• SIC 42-45a
• SIC 49b
• SIC 50-76C
Pilot study facilities (certainty
selections)
Direct discharger subtotal
927
1019
440
1478
1752
919
5169
3442
3000
3212
2680
3642
2688
9276
3400
6
43,050
142
156
67
226
268
141
141
95
82
88
73
100
74
254
93
6
2,006
6.528
6.532
6.567
6.540
6.537
6.518
36.660
36.232
36.585
36.500
36.712
36.420
36.324
36.520
36.559
1.000
NA
Zero Discharge Facilities
States with complete databases:
• In TRI or AFS
• High-priority SICsd
• Low-priority SICsd
• Unknown SICd
228
61
301
1155
13
5
13
55
17.539
12.200
23.154
21.000
(continues
A-44
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March 26, 2001
Appendix A
Table A-10. (continued)
Sampling Stratum
• SIC 4952d
States with general databases:
• In TRI or AFS
• High-priority SICs
• Low-priority SICs
• Unknown SIC
• SIC 4952
States with partial databases:
• In TRI or AFS
• With target SICs
• Unknown SICs
• SIC 4952
States with no relevant databases
• In TRI or AFS
Zero discharger subtotal
Frame Count
891
128
127
543
1592
95
116
121
117
138
194
5,807
Sample Size
22
6
6
25
74
3
4
6
4
8
6
250
Initial Weight
40.500
21.333
21.167
21.720
21.514
31.667
29.000
20.167
29.250
17.250
32.333
NA
TRI = EPA's Toxic Release Inventory.
AFS = EPA's Aerometric Information Retrieval System, Facility Subsystem.
aSICs 4212, 4213, 4231, and 4581
bSICs 4952 (excluding Publicly Owned Treatment Works), 4953, and 4959
cSICs 5085, 5093, 5169, 5171, and 7699 (transportation equipment cleaners only)
dNotinTRIorAFS.
merged to the facility level only when it was quite clear that there were multiple permits for the
same facility. Up to 3 different permits were merged into a single facility-level record. Any
facilities that had multiple permits that did not get merged into a single facility-level record on
the sampling frame had multiple chances of being selected into the sample.
The screener survey listed all permits that had been used to define the facility on the
sampling frame, and asked each facility to list any additional permits that had been active for the
facility at any time since June 1, 1990. After considerable data cleaning, the multiplicity
(number of linkages to the sampling frame) was determined for each facility that responded to
the screener survey.
However, the frame multiplicity must be known for every sample facility, not just the
responding facilities. Therefore, for each direct discharger sampling stratum, the average
A-45
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March 26, 2001 Appendix A
multiplicity was computed among the respondents and the multiplicity was imputed for each
nonresponding facility within each sampling stratum to be the average multiplicity for that
stratum. After having computed or imputed the multiplicity, m(j), for each direct discharge
sample facility, the multiplicity-adjustment to the sampling weight was computed for the j-th
facility as follows:
w2 (j) = 1 /m(j) for direct discharge facilities
w2 (j) = 1 for zero discharge facilities.
Lessler and Kalsbeek (1992, Section 5.2.2) show how this using this multiplicity adjustment
produces survey estimates that are design-unbiased.
A.5.1.3 Adjustment for Nonrespome to the Screener Survery. Weight adjustments to
reduce the bias due to survey nonresponse are based on models for the probability of responding,
using data that are available for both respondents and nonrespondents. Since the sampling
stratum was the only thing we knew about the nonresponding facilities, we used sample-based
ratio adjustments based on the sampling strata (see Brick and Kalton, 1996). The nonresponse
adjustments were defined only for the direct and zero discharge facilities because the indirect
discharger sample was not a probability-based sample.
The weight adjustment for nonresponse is simply the reciprocal of the weighted response
rate in each weighting class. Therefore, strata for which the number of respondents was small
(e.g., less than 20) were collapsed with similar strata to form weighting classes. However,
assigning strata with dissimilar response rates to different weighting classes is necessary to
reduce nonresponse bias.
Hence, after reviewing the pattern of study eligibility and survey response by sampling
strata, it was decided that each of the 15 sampling strata for the direct discharger sample
contained sufficient numbers of respondents to be a separate weighting class, and they are the
first 15 weighting classes. However, because of the smaller sample size for the zero discharger
sample, strata were combined to form weighting classes as follows:
• Weighting class 16 consists of zero discharger strata 1 through 4: the facilities
from the TRI or AFS portion of the sampling frame;
• Weighting class 17 consists of zero discharger strata 5, 6, and 9: the facilities with
high-priority SICs; and
• Weighting class 18 consists of the remainder of the zero discharger facilities.
Having defined the weighting classes for nonresponse adjustment, the weight adjustments
were implemented for nonresponse in two stages. First, an adjustment was made for inability to
determine whether or not a facility was eligible for the screener survey (i.e., was in operation at
any time since June 1, 1990). The second stage of nonresponse adjustment was an adjustment
for nonresponse among the facilities known to be eligible for the screener survey.
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March 26, 2001 Appendix A
The weight adjustment factor for inability to determine eligibility for the screener survey
was computed for the c-th weighting class follows:
E wi CO "
jec
where Ik (j) is an indicator that the eligibility status or they'-th facility is known, i.e.,
4 (j) = 1 if the eligibility status of they'-th facility is known
Ir(j) = 0 otherwise.
This adjustment is equivalent to assuming that the proportion of sample facilities that are eligible
for the screener survey (i.e., in operation at any time since June 1, 1990) is the same for facilities
both with known and unknown eligibility status.
Similarly, the weight adjustment factor for survey nonresponse was defined for the c-th
weighting class as follows:
E WiWjWjr
jec
where/,, and/e are indicators of response and eligibility status, respectively, i.e.,
Ir (J) = 1 if they'-th facility was a screener respondent
Ir (j) = 0 otherwise, and
Ie (j) = 1 if they'-th facility was eligible for Phase 1
Ie (j) = 0 otherwise.
These nonresponse adjustments are shown for each of the 18 weighting classes in Table A-l 1.
The final statistical analysis weight for the screener survey was defined for they'-th facility
in the c-th weighting class as the product of the various weight components, as follows:
W5 (j) = Wl (j) W2 (j) W3(C) W4(C) IrQ) •
A.5.1.4 Adjustment for Subsampling for the Long Survey. Respondents to the screener
survey were eligible for selection into the subsample to receive the long survey if their screener
survey data indicated that they satisfied the following conditions:
• Had an in-scope SIC1
1 Major groups 20-39 and 97 plus codes 4212, 4213, 4231, 4581, 4952 (except Publicly Owned Treatment
Works), 4953, 4959, 5085, 5093, 5169, 5171, and 7699 (transportation equipment cleaners only).
A-47
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March 26, 2001 Appendix A
• Were in operation at any time since June 1, 1990, and the time of the survey in the
summer of 1999
• Used at least one direct- or zero-discharge surface impoundment to manage only
nonhazardous waste.
A stratified random sample of 201 of the screener respondents, plus the six pilot study facilities,
were selected to receive the long survey. The weight component for selection of this subsample
was the reciprocal of the probability of selection. It was computed for they'-th facility in stratum
s as
v>6(j) =N2(s)/n2(s),
where
N2 (s) = Total number of facilities in stratum s eligible to be selected for the long
survey sample, and
n2 (s) = Number of facilities selected from stratum s to receive the long survey.
The frame count, N2 (s), sample count, n2 (s), and weight component, w6(j) are shown in
Table A-12 for each sampling stratum.
A.5.1.5 Calibration to Screener Survey Weight Totals. The estimated number of
facilities in the survey population using the long survey weights is not identical to the estimate
based on the screener analysis weights (7,459 facilities) because the screener weights were not all
the same within each stratum from which facilities were selected for the long survey. The
screener sample weights provide a more reliable estimate of the size of the population because of
the larger number of screener respondents, relative to the long survey subsample. Therefore, the
long survey weights were calibrated to sum to the screener totals within each stratum used to
select facilities for the long survey. In particular, the calibration weight factor was computed for
they'-th facility in stratum s as follows:
Aid)
E ws(0
where Is is a (0,1) indicator of inclusion in the long survey sample. These calibration adjustment
factors also are shown in Table A-12.
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March 26, 2001
Appendix A
Table A-ll. Weighting Class Adjustments for Screener Survey Nonresponse
Weighting Class
Adjustment for Inability to
Determine Eligibility
Adjustment for
Nonresponse Among
Eligible Facilities
Direct Discharge Facilities
High-priority SICs:
• SIC 26
• SIC 28
• SIC 29
• SIC 30
• SIC 33
• SIC 36
Low-priority SICs:
• SIC 20-23
• SIC 24-27
• SIC 28-31
• SIC 32
• SIC 34
• SIC 35-39
• SIC 42-45a
• SIC 49b
• SIC 50-76C
Pilot study facilities (certainty
selections)
1.035
1.096
1.159
1.071
1.058
1.109
1.126
1.044
1.052
1.098
1.105
1.074
1.119
1.315
1.105
1.000
1.000
1.000
1.000
1.010
1.008
1.016
1.008
1.023
1.000
1.000
1.000
1.033
1.000
1.038
1.012
1.000
Zero Discharge Facilities
In TRI or AFS
High-priority SICsd
All other facilities'1
1.105
1.290
1.154
1.000
1.000
1.012
TRI = EPA's Toxic Release Inventory.
AFS = EPA's Aerometric Information Retrieval System, Facility Subsystem.
aSICs 4212, 4213, 4231, and 4581
bSICs 4952 (excluding Publicly Owned Treatment Works), 4953, and 4959
cSICs 5085, 5093, 5169, 5171, and 7699 (transportation equipment cleaners only)
dNotinTRIorAFS.
A-49
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March 26, 2001
Appendix A
Table A-12. Subsampling and Calibration Weights for the Long Survey
Sampling Stratum3
Frame Count
Sample
Size
Subsampling
Weight
Calibration
Weight
Direct Discharge Facilities
Handles formerly characteristic waste and
high-priority SIC
Handles formerly characteristic waste and
low-priority SIC
Does not handle formerly characteristic
waste and high-priority SIC
Does not handle formerly characteristic
waste and low-priority SIC
Pilot study facilities (certainty selections)
Direct discharger subtotal
75
7
204
78
6
370
75
4
68
14
6
167
1.000
1.750
3.000
5.571
1.000
NA
1.000
0.894
1.003
0.938
1.000
NA
Zero Discharge Facilities
Handles formerly characteristic waste and
high-priority SIC
Handles formerly characteristic waste and
low-priority SIC
Does not handle formerly characteristic
waste and high-priority SIC
Does not handle formerly characteristic
waste and low-priority SIC
Zero discharger subtotal
2
4
14
20
40
2
4
14
20
40
1.000
1.000
1.000
1.000
NA
1.000
1.000
1.000
1.000
NA
aBased on the screener survey data.
A.5.1.6 Adjustment for Nonresponse to the Long Survey. Theoretically, all facilities
selected into the sample to receive the long survey should have been eligible for this phase of the
study. That is, they should all have had at least one surface impoundment that satisfied the
eligibility conditions in the screener survey. However, several facilities reported that they had no
eligible impoundments and had completed the screener survey incorrectly. Using extensive
follow-up contacts, the eligibility status was determined for all facilities selected into the sample
for the long survey. Hence, nonresponse adjustments were confined to adjustment for
nonresponse among the sample facilities that were determined to be eligible for the survey.
For the full sample, there were only four eligible facilities that did not respond to the
long survey, and one of those was an indirect discharge facility. Hence, for the weight
adjustments for direct and zero discharge facilities, there were only three nonresponding
facilities. Moreover, all three were direct discharge facilities whose screening data indicated that
they did not handle any formerly characteristic waste. Therefore, the weighting classes for
nonresponse to the long survey will be defined as shown in Table A-13.
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March 26, 2001
Appendix A
Table A-13. Weighting Class Adjustments for Long Survey Nonresponse
Weighting Class3
Eligible
Facilities
Responding
Facilities
Nonresponse
Adjustment
Direct Discharge Facilities
Facility does not handle formerly characteristic waste
Facility and its impoundment(s) handle formerly
characteristic waste
Facility handles formerly characteristic waste, but not its
impoundment(s)
Direct discharger subtotal
33
75
38
146
30
75
38
143
1.084
1.000
1.000
NA
Zero Discharge Facilities
All
35
35
1.000
aBased on the screener survey data.
The statistical analysis weights for the long survey respondents then were computed by
adjusting the calibrated sampling weights, w5 *w6 * w7, for nonresponse among the eligible
sample facilities. Hence, the weight adjustment factor for nonresponse to the long survey was
defined for the A>th weighting class as follows:
(*) =
iek
£
iek
where/,, and/e are indicators of long survey response and eligibility status, respectively, i.e.,
I/i) = 1 if the /'-th facility was a long survey respondent
Ir(i) = 0 otherwise, and
Ie(i) = 1 if the /-th facility was eligible to receive the long survey
Ie(i) = 0 otherwise.
The final statistical analysis weight for the long survey then was defined for the /'-th
facility in the c-th weighting class as the product of the various weight components, as follows:
w9 ft) = ws ft) w6 ft) w7 ft) w8 (k) I/i) .
Because data were collected for all eligible impoundments at each responding facility (i.e., there
was no subsampling of impoundments), these facility-level analysis weights also are appropriate
for analysis of the impoundment-level data collected for the responding facilities.
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March 26, 2001 Appendix A
A.5.1.7 Adjustment for Item Nonresponse. Using the final statistical analysis weights, w5
and w9, for the 1,774 screener survey and 195 long survey respondents, respectively, reduces the
potential for bias due to nonresponse of eligible facilities selected for these surveys. However,
some survey items have additional missing data among these survey respondents. Failure to
adjust for nonresponse to individual data items again leads to nonresponse bias. In particular, all
population totals will be underestimated if item nonresponse is ignored. Statistical imputation
procedures are often used to replace missing data items because they result in simpler, more
consistent, analyses. However, they also have the potential to distort relationships between
variables (see Brick and Kalton, 1996).
Because of concern regarding the potential distortions that can result from using imputed
data, weight adjustments were used to reduce the potential for bias due to item nonresponse,
exactly as they were used to compensate for total survey nonresponse. In particular, if an
analysis was based on m variables that were constructed from long survey data, the data used in
the analysis were those belonging to the facilities (or impoundments) that had complete data for
all m variables. The weight adjustment for item nonresponse was developed as a SAS macro so
that it could easily be implemented for each individual data analysis for which complete data
were not available for all long survey respondents. The adjustment was a standard weighting
class adjustment. Because some analyses had high levels of missing data, the weighting classes
used to adjust for long survey nonresponse were collapsed to the following three weighting
clases:
• Direct discharge facilities that do not manage decharacterized waste (based on the
screener survey data).
• Direct discharge facilities that do manage decharacterized waste (based on the
screener survey data).
• Zero discharge facilities.
Hence, the weight adjustment factor for item nonresponse to the long survey was defined
for the /-th weighting class as follows:
,(0 =
iel
where Ir is an indicator of respondents with data for all m items used in a particular analysis and
Ie is an indicator of the full set of long survey respondents, i.e.,
Ir(i) = 1 if the /-th facility or impoundment has data for all m variables used in the
particular analysis
Ir(i) = 0 otherwise, and
Ie(i) = 1 if the /-th facility or impoundment was a long survey respondent
///') = 0 otherwise.
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March 26, 2001 _ Appendix A
The final statistical analysis weight, adjusted for item nonresponse, then was defined for
the /'-th facility in the 7-th weighting class as follows:
i) = w9(i) w
,0
Hence, each analysis was based on complete data cases with a statistical adjustment for
nonresponse to the set of data items used in each particular analysis. This ensures that the
estimated numbers of facilities and impoundments in the survey population are consistent across
all analyses.
Nevertheless, estimates of population totals for other population characteristics (e.g., the
total number of impoundments with liners) may be somewhat inconsistent from one analysis to
the next because of different missing data patterns. However, when the extent of missing data is
low (e.g., 10 percent or less), the inconsistencies will be small.
A.5.1.8 Analysis Domains. Statistical analyses were performed primarily for two
populations of facilities and the surface impoundments used to manage non-hazardous wastes at
those facilities. This section describes and briefly characterizes each of these populations.
The first population of particular interest consists of those facilities in the screener survey
population that had at least one eligible impoundment, as defined for that survey. The specific
characteristics of that population of facilities are as follows: facilities with in-scope SICs2 in the
United States that were in operation at any time between June 1, 1990, and the summer of 1999
that used at least one direct- or zero-discharge surface impoundment to manage only
nonhazardous wastes resulting from any one of the following processes:
• A manufacturing process other than heat transfer
• A direct-contact heat transfer process
• Equipment washing, product washing, or washing surfaces (e.g., buildings or
floors)
• Spill cleanup
• Air pollution control
• Materials handling (e.g., valve/pump drips collected in a sump and mixed with
rainwater)
• Boiler blowdown
• Laundering
• Leachate (liquid percolated through or drained from a waste management unit).
Because of many false positive responses to the screener survey, the best estimate of the
size of this population is based on the long survey responses. The estimated number of such
facilities is 7,459, based on 184 such facilities that responded to the long survey. The estimated
number of surface impoundments at these facilities that meet these same eligibility conditions is
16,782, based on 562 such impoundments reported in the long survey.
2 Major groups 20-39 and 97 plus codes 4212, 4213, 4231, 4581, 4952 (except Publicly Owned Treatment
Works), 4953, 4959, 5085, 5093, 5169, 5171, and 7699 (transportation equipment cleaners only).
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March 26, 2001 _ Appendix A
The second population of particular interest consists of those facilities in the first
population that used at least one eligible surface impoundment to manage at least one of the
target chemicals identified in the long survey or had an extreme pH in an eligible impoundment .
The specific characteristics of this population of facilities are as follows: facilities in the first
population whose direct- and zero-discharge impoundments were used only to manage non-
hazardous waste for which any of the following were true:
• 30-day average pH was less than 3
• 30-day average pH was greater than 1 1
• at least one target chemical was managed in the surface impoundment.
The estimated number of such facilities is 4,457, based on 157 such facilities that responded to
the long survey. The estimated number of surface impoundments at these facilities that meet
these same eligibility conditions is 1 1,863, based on 53 1 such impoundments reported in the long
survey.
A. 5. 2 Estimation Procedures
This section discusses the statistical analysis procedures used to compute point estimates
of population totals, means, and proportions for the populations of facilities and impoundments
discussed above. In addition, it describes how standard errors were computed for these
population estimates, how estimates with poor precision were identified, and how confidence
interval estimates can be generated. All the standard errors were produced using RTFs
SUDAAN software for analysis of data from complex sample surveys (Shah et al, 1997).
A.5.2.1 Point Estimates. If Yt denotes a measured quantity for the /'-th facility or
impoundment (e.g., number of eligible impoundments or presence of a liner), then the population
total for characteristic Y was estimated as
where wt denotes the statistical analysis weight and S denotes summation over either all facilities
in the sample or over all impoundments at these facilities (depending on whether the outcome, Yt,
is a facility-level or impoundment-level outcome). In the same manner, the population mean for
characteristic Yt was a ratio estimate computed as follows:
Likewise, population proportions were ratio estimates, computed as follows:
P = *
x
where Xt =1 for those facilities or impoundments with the characteristic of interest (e.g., ever
managed RCRA characteristic hazardous waste) and Xt = 0 otherwise.
A-54
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March 26, 2001 Appendix A
In addition, estimates of population totals, means, and proportions were generated for
various subpopulations, or analysis domains (e.g., states or SIC codes). In these cases, the
estimators of the population totals, means, and proportions were generated by substituting the
product djwt for wt in the above formulas, where dt = 1 if the facility or impoundment is a
member of the analysis domain and di = 0 otherwise.
A. 5.2.2 Standard Errors. The standard error of an estimate is a common statistical
measure of its precision. It is the standard deviation of the sampling distribution of the estimate
or, alternatively, is the square root of the variance of the estimate. That is, if one were to
replicate the sample selection and data collection procedures many times in exactly the same way
and with exactly the same population, the standard error of the estimate is the standard deviation
of the values of that estimate that would be generated by those samples.
Estimates of variances and standard errors of survey statistics were computed using RTFs
SUDAAN software. For nonlinear survey statistics, such as estimated means and proportions,
SUDAAN uses the classical first-order Taylor Series linearization method (Wolter, 1985).
Because the number of facilities and impoundments in the target population is much
greater than the number included in the sample, calculation of standard errors was simplified by
treating the initial sample of facilities selected for the screener survey as having been selected
with replacement. Hence, computation of standard errors only required identifying the analysis
strata and primary sampling units (PSUs) used at the first stage of sample selection. Because
facilities were selected directly in the initial sample for the screener survey, they are the PSUs.
Because each analysis stratum must contain at least two responding facilities in order to calculate
standard errors, some of the sampling strata shown in Table A-10 were collapsed to form analysis
strata as shown in Table A-14. In addition, when the number of facilities with complete data for
the set of items entering a particular analysis was low, adjacent analysis strata were sometimes
collapsed, but strata representing direct discharge facilities were never collapsed with strata
representing zero discharge facilities.
The procedures used by SUDAAN to estimate variances and standard errors can best be
explained by introducing some mathematical notation to represent the statistical analysis strata,
facilities, impoundments, and observations. Hence, let
h = 1, 2, ..., 15 denote the 15 statistical analysis strata shown in Table A-14
/ = 1,2, ...,nh denote the sample facilities in stratum h and
j= 1,2, ...,mhi denote the impoundments at the i-th facility in stratum h.
If 7 represents an impoundment-level characteristic (e.g., concentration of a target analyte), then
let
Yhij = the value of the outcome, 7, for they-th impoundment at the i-th facility in stratum h
and
mu
YM = £ YMJ •
-------
March 26, 2001 Appendix A
However, if 7 represents a facility-level characteristic (e.g., number of years of operation), then let
Yhi = the value of the outcome, 7, for the /'-th facility in stratum h.
Using this notation, whether 7 represents an impoundment-level characteristic or a facility-level
characteristic, Yhi is a facility-level outcome, and it is helpful to further let
ZM = ™MYM •
Then, the estimated population total for characteristic 7 can be represented as
15 «/,
Y = E E ZM •
h= 1 z= 1
Sampling variances for estimated totals were then estimated as
h=\
where
T n.
and
~ 1
E
In order to illustrate how SUDAAN computed sampling variances for estimates means
and totals, it is helpful to represent these ratio estimates as
15 »*
E E ™h?hi
R= *lllli - .
15 »*
E E ™M
h=\i=\
The estimated variance of the ratio was then based on the following "linearized value:"
E E
h=\i=\
The variance of the estimated mean or proportion was then computed as the estimated variance
for the population total of the linearized values, Z^* , i.e,
where the latter variance is computed using the formula presented above for estimating the
variance of a population total.
A-56
-------
March 26, 2001 Appendix A
The standard errors computed in this manner account only for the uncertainty resulting
from random errors, primarily those due to making inferences from a sample, rather than from a
census of all facilities in the population. They do not account for potential sources of systematic
error (or bias), such as the incomplete nature of the sampling frame for zero dischargers (see
Table A-10), response errors, data entry errors, etc.
When a cell sample size (i.e., the number of observations upon which a total, mean, or the
denominator of a proportion is based) is small (e.g., less than 30), the standard error calculated by
SUDAAN often is underestimated. In that case, the survey design effect, which typically exceeds
one (1), may be estimated to be less than one, suggesting that the survey achieved greater
precision than a simple random sample. Hence, if 6represents an estimated total, mean, or
proportion and SE(&) represents its standard error calculated by SUDAAN, the standard error
used for that estimate was calculated as
se = Max [SE, __] when w< 30
when n > 30,
where DEFF is the Type 1 survey design effect calculated by SUDAAN and n is the cell sample
size. Hence, the standard error calculated by SUDAAN was inflated to compensate for
underestimation when the cell sample size was small (<30) and the survey design effect was less
than one (1).
Estimates with Poor Reliability
When cell sample sizes are small, weighted population estimates may not be reliable, and
their standard errors may not be accurately estimated. Therefore, estimated totals and means are
flagged in the report as being unreliable when the relative standard error (RSE) of the estimate is
50 percent or more. That is, if ^represents an estimated total or mean, then that estimate is
flagged as unreliable if
> 0.50 .
RSEs do not work as well as measures of precision for estimated proportions because an
estimate, P, and its complement, (1 - P), have the same variance but quite different RSEs.
Therefore, the statistic used to flag estimates of proportions as unreliable is the RSE of the
natural logarithm of P. In particular, the estimate, P, of a population proportion is flagged as
unreliable if
L / U ^
> 0.275 when P < 0.50
or
> 0.275 when P * 0.50
-ln(l - P)
A-57
-------
March 26, 2001
Appendix A
The upper bound, 0.275, is an ad hoc bound that has been found to produce reasonable results.
Table A-14. Analysis Strata Used for Variance Estimation
Analysis Stratum
Number of Long Survey Respondents
Direct Discharge Facilities
• SIC 26
• SIC 28
• SIC 29
• SIC 30
• SIC 33
• SIC 34-39
• SIC 20-23
• SIC 24-27
• SIC 28-31
• SIC 32
• SIC 49-76a
Pilot study facilities (certainty selections)
Direct discharger subtotal
27
29
21
6
20
6
6
6
9
6
7
6
149
Zero Discharge Facilities
InTRIorAFS
High priority SICsb
All other facilities'5
Zero discharger subtotal
5
6
24
35
TRI = EPA's Toxic Release Inventory.
AFS = EPA's Aerometric Information Retrieval System, Facility Subsystem.
aSICs 4952 (excluding Publicly Owned Treatment Works), 4953, and 4959, 5085, 5093, 5169, 5171, and 7699
(transportation equipment cleaners only)
bNotinTRIorAFS.
A.5.2.3 Confidence Intervals. The reported standard errors also can be used to compute
confidence interval estimates of population totals, means, and proportions. If 8 represents an
estimated total, mean, or proportion, an approximate 100(1-a) percent confidence interval
estimate of that parameter can be calculated as
»±r
df,,l-
A-58
-------
March 26, 2001 _ Appendix A
where t is the 100(l-a/2) percentile of the Student's t distribution with 4f degrees of freedom and
SE(&) is the standard error of the estimate. The appropriate degrees of freedom is
df = £ (rh ~ 1) ,
h=\
where h represents the analysis strata (see Table A-14) and rh is the number of responding
facilities in analysis stratum h.
These confidence intervals are valid so long as the number of facilities contributing to the
estimated total, mean, or proportion is large enough that the sampling distribution of the sample
total, mean, or proportion is approximately a Student's t distribution.
Because of the relatively large number of facilities in the sample for the surface
impoundment study, the resulting degrees of freedom usually are greater than 30, and the
appropriate value to use from the Student's t distribution is actually the 100(1 -a/2) percentile of
the standard normal distribution. In that case, the approximate 95 percent confidence interval
estimate of a population parameter (total, mean, or proportion) becomes
Confidence interval estimates are reported only when the cell sample size is sufficiently
large to support a reasonably precise estimate. Therefore, confidence interval estimates are not
reported for those estimates that are flagged as unreliable based on the criteria discussed above.
A.6 References
Aller, L., T. Bennett, J.H. Lehr, RJ. Petty, and G. Hackett. 1987. DRASTIC: A Standard System
for Evaluating Ground Water Pollution Potential Using Hydrogeologic Settings.
EPA-600/2-87-035. Robert S. Kerr Environmental Research Laboratory, Ada, OK.
Brick, J.M., and G. Kalton. 1996. Handling missing data in survey research. Statistical Methods
in Medical Research 5:215-238.
Hansch, C., A. Leo, and D. Hoekman. 1995. Exploring QSAR: Hydrophobic. Electronic, and
Steric Constants. American Chemical Society, Washington, DC.
Hunt, C. B., 1974. Natural Regions of the United States and Canada. W. H. Freeman and
Company, San Francisco, California.
Kalton, G. and D.S. Maligalig. 1991. "A Comparison of Methods of Weighting Adjustment for
Nonresponse." Bureau of the Census 1991 Annual Research Conference Proceedings,
pp. 105-110.
Kollig, H.P., J.J. Ellington, S.W. Karickhoff, B.E. Kitchens, J.M. Long, E.J. Weber, andN.L.
Wolf. 1993. Environmental Fate Constants for Organic Chemicals Under Consideration
A-59
-------
March 26, 2001 Appendix A
for EPA 's Hazardous Waste Identification Projects. U.S. Environmental Protection
Agency. Office of Research and Development. Athens, GA.
Lessler, J.T. and W.D. Kalsbeek (1992). Nonsampling Error in Surveys. New York, NY:
Wiley.
Shah, B.V., Barnwell, E.G., Bieler, GS. (1997) SUPAAN User's Manual. Research Triangle
Institute, RTF, NC.
U. S. EPA (Environmental Protection Agency). 1999b. Screening Survey for Land
DisposalRestrictions Surface Impoundment Study. Washington, DC. February.
U.S. EPA (Environmental Protection Agency). 1999d. Survey of Surface Impoundments.
Washington, DC. November.
U.S. EPA (Environmental Protection Agency). 1999a. Chemical Data Base for HWIR99. Office
of Research and Deveopment. Athens, GA.
U.S. EPA (Environmental Protection Agency). 1999c. Surface Water, Soil, and Waste Partition
Coefficients for Metals. National Exposure Research Laboratory. Athens, GA. June 22.
U.S. Geological Survey (USGS), 1984. Geologic Map of the United States. USGS Branch of
Distribution at Federal Center, Denver, CO.
U.S. EPA (Environmental Protection Agency). 1996b. SuperfundChemical Data Matrix.
Office of Emergency and Remedial Response, Washington, DC.
http://www.epa.gov/oerrpage/superfnd/web/resources/scdm/index.htm
U.S. EPA (Environmental Protection Agency). 1996a. Better Assessment Science Integrating
Point and Nonpoint Sources (BASINS), Version 1. EPA-823-R-96-001. Office of Water,
Washington, DC.
USGS (United States Geological Survey). Updated daily. United States National Water
Information System (NWIS) water data retrieval internet site accessed on January 31,
2001. http://waterdata.usgs.gov/nwis-w/us/.
van der Leeden, F., Troise, F. L., Todd, D. K., 1990. The Water Encyclopedia - Second Edition.
Chelsea, Michigan; Lewis Publishers, Inc.
Wolter, K.M. (1985). Introduction to Variance Estimation. New York: Springer-Verlag.
A-60
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Appendix B
Database Tables
-------
-------
March 26, 2001 _ Appendix B
Appendix B: Database Tables
This Appendix supplements Chapter 2 with additional estimates of the characteristics of
the surface impoundment sampling frame. The first section of the appendix presents tables of
various data elements from the survey database, with standard errors where appropriate. All of
the data presented are extrapolated estimates; no sample-level data are shown. The tables in this
first section are Table B-2 through Table B-18. The second section of the appendix focuses on
the chemical data, and presents comparisons of the chemical data in the survey (consolidated)
database to the chemical data in the risk input database, as well as other chemical data
comparisons relevant to the Study. This section includes Table B-19 through Table B-30, and
Figures B-l through B-33.
Table B-l lists all of the tables and figures in this appendix, and provides for each the
survey question or other data source used, along with references to relevant sections of this report
that describe data processing methods, protocols, and specifications used to create the data
displayed in the tables. The primary section referenced is Appendix A and its attachments, which
provide background on the sampling methodology, survey, and database development, including
the consolidated survey and risk input databases. For example, Attachment Al is the actual three-
part survey forms, which have the questions (number and text) referred to in Table B-l. The
information in Appendix A and its attachments provides the context for understanding the data
provided in the tables in this appendix.
How to read and interpret the tables and the standard errors. Most of the tables in this
appendix include the standard errors for each population estimate, usually in parentheses but
sometimes as separate tables (e.g., Tables B-19b and B-20b). Estimates that may be unreliable
because of a high relative standard error are indicated with an asterisk. The standard error is a
common statistical measure of the precision of an estimate. It is the standard deviation of the
sampling distribution of the estimate. That is, if one were to replicate the sample selection and
data collection procedures many times in exactly the same way and with exactly the same
population, the standard error of the estimate is the standard deviation of the values of that
estimate generated by the samples. Section A.5.2 (Appendix A) explains how standard errors
were calculated for the surface impoundment study.
Two common applications of standard errors are for computing relative standard errors,
which are unit-free measures of precision, and for computing confidence interval estimates of
population parameters. Both these uses of standard errors are summarized briefly below.
If se(&) represents the standard error of the estimate, 0, then the relative standard error is
the ratio of the standard error divided by the estimate itself, i.e.,
Estimates in Tables B-l through B-30 that have relative standard errors exceeding 50 percent
have been flagged (with an asterisk) as possibly being unreliable.
Because the estimates in Tables B-l through B-30 are all based on a large sample of
facilities, a 95 percent confidence interval estimate of the population total, mean, or proportion is
the point estimate, 0, plus or minus two standard errors, i.e.,
0 ± 2^(0) .
Additional details on the calculation of standard errors and confidence intervals may be found in
section A.5.2 of Appendix A.
B-3
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March 26, 2001
Appendix B
Table B-l. Description of Tables and Figures
Table Number
Description: Survey Question, Data Sources
Table B-l. List of Tables and Figures
(This table) Summarizes content and data sources for
Appendix B tables and figures, including long survey
question number and relevant Appendix A sections.
Table B-2. Characteristics of Industrial
Impoundments
Number of all impoundments, number of impoundments
with chemicals and pH of concern: B2; impoundment
level characteristics: C6 to C9a; wastewater quantities:
C16 or from impoundment areas and depths: from
diagrams/maps provided in response to B3 and CIO (see
section A.2.5)
Table B-3. Estimated Number of
Facilities with Chemicals/pH of Concern
by EPA Region
Facility location (address, city, state): A2
Table B-4. Estimated Number of
Impoundments with Chemicals/pH of
Concern by EPA Region
Table B-5. Estimated Number of
Facilities with Chemicals/pH of Concern
by 2-Digit Standard Industrial
Classification (SIC) Code
SIC code: screener data or, if missing, obtained from
other sources (see section A. 1.2)
Table B-6. Estimated Number of
Impoundments with Chemicals/pH of
Concern by 2-Digit Standard Industrial
Classification (SIC) Code
Table B-7. Estimated Quantity of
Wastewater (metric tons) Managed in
Impoundments with Chemicals/pH of
Concern, by 2-Digit Standard Industrial
Classification (SIC) Code
Wastewater quantities: C16 or from impoundment areas
and depths: from diagrams/maps provided in response to
B3 and CIO (see section A.2.5)
Table B-8. Distribution of Ages of
Impoundments with Chemicals/pH of
Concern in Operation in Year 2000
Ages of impoundments: Cl (midpoint of year range), C2a
(operating status in 2000)
Table B-9. Distribution of Lifetimes of
Impoundments with Chemicals/pH of
Concern that have Permanently Ceased
Receiving Wastes
Impoundment lifetimes: Cl (midpoint of year range), C2a
(closure status); Year impoundment ceased receiving
wastes: C2b
Table B-10. Estimated Number of
Facilities with Chemicals/pH of Concern
by Treatment Type
Treatment types: CIS (treatment, storage, disposal
status); C20:types of treatment being performed.
Table B-l 1. Estimated Number of Lined
Impoundments with Chemicals/pH of
Concern by 2-Digit Standard Industrial
Classification (SIC) Code
Liner status: standardized data based on C12 (see liner
tables in consolidated database, section A.4.1 and
Attachment A7).
(continued)
B-4
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March 26, 2001
Appendix B
Table B-l. (continued)
Table Number
Description: Survey Question, Data Sources
Table B-12. Frequency of Liner Usage
for Impoundments by Age of
Impoundment
Time when impoundments began receiving wastes: Cl,
C2; liner status: standardized data based on C12 (see liner
tables in consolidated database, section A.4.1 and
Attachment A7); liner failure determination: C14a (oldest
failure event)
Table B-13. Estimated Number of
Overtopping Events at Impoundments
with Chemicals/pH of Concern by
Duration
Number and duration of overtopping events : C25
Table B-14. Estimated Number of
People, Residences, Drinking Water
Wells, and Schools within Distance
Ranges of the Population of
Impoundments with Chemicals/pH of
Concern
Estimates for the number of residences, drinking water
wells, and schools: B3 maps, U.S. Census data, GIS
analysis (see section A.3.1)
Table B-15. Estimated Number of
Impoundments with Chemicals/pH of
Concern that had a State or Local Permit
for Wastewater, Sludge Management,
Groundwater Protection, or Air
Emissions by 2-Digit SIC Code
Determination of whether impoundment is under a state
or local permit: C8a
Table B-16. Estimated Number of
Impoundments with Chemicals/pH of
Concern which are Solid Waste
Management Units at RCRA Treatment,
Storage, and Disposal Facilities (TSDs)
Evaluated During a RCRA Facility
Assessment, or Similar Action by 2-Digit
SIC Code
Determination of whether impoundment was evaluated
during a RCRA Facility Assessment: C9a
Table B-17. Estimated Number of
Impoundments with Chemicals/pH of
Concern which Received Any Waste
Exempt or Excluded from Regulation by
2-Digit SIC Code
Determination of whether impoundment received
exempt/excluded waste and exemption/exclusion type:
C7a (see Attachment A2.3, coding table EX_LIST for a
listing of exemptions/exclusions by regulatory code).
Table B-18. Estimated Quantity (metric
tons) of Wastewater Managed in
Impoundments with Chemicals/pH of
Concern that is Exempt or Excluded from
Regulation
Determination of whether impoundment received
exempt/excluded waste and exemption/exclusion type:
C7a; estimated quantity: C7b (midpoint of the percentage
range), C16 (typical wastewater quantity) (see
Attachment A2.3, coding table EX_LIST for a listing of
exemptions/exclusions by regulatory code)
Table B-19a. Chemicals: Presence and
Volume in Wastewater (for
Impoundments with Chemicals/pH of
Concern)
Table B-l9b. Standard Errors for
Chemicals: Presence and Volume in
Wastewater (for Impoundments with
Chemicals/pH of Concern)
Chemical presence in wastewater: C23a, C24a, or C24c
(mark as present but quantity unknown or reported
concentration or flux detection ); wastewater quantities:
C23a, C24a, and C24c (concentration or mass per unit
time), (consolidated database - see section A.4.1 and
Attachments A6, A7); C16 (wastewater quantity)
(continued)
B-5
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March 26, 2001
Appendix B
Table B-l. (continued)
Table Number
Description: Survey Question, Data Sources
Table B-20a. Chemicals: Presence and
Volume in Sludge (for Impoundments
With Chemicals/pH of Concern)
Table B-20b Standard Errors for
Chemicals: Presence and Volume in
Sludge (for Impoundments With
Chemicals/pH of Concern)
Chemical presence in sludge: C23b, C24b, or C24d (mark
as present but quantity unknown or reported
concentration or flux detection ); sludge chemical
quantities: C23b, C24b, and C24d (concentration or mass
per unit time), (consolidated database - see section A.4.1
and Attachments A6, A7); C16 (sludge quantity)
Table B-21. Comparison of Survey Data
and Risk Input Data: Chemical
Categories for Wastewater and Sludge at
Influent, In Impoundment, and Effluent
Sampling Points
Chemical presence in wastewater, sludge: C23, C24
(consolidated database - see section A.4.1 and
Attachments A6, A7; risk input database - see section
A.4.2 and Attachment A8); C16 (wastewater and sludge
quantity)
Table B-22. Chemical Presence in
Wastewater Influent by SIC Code
(Survey Database)
Chemicals presence in influent: C24a (mark as present
but quantity unknown or reported concentration or flux
detection ) (consolidated database - see section A.4.1 and
Attachments A6, A7)
Table B-23. Chemical Presence in
Wastewater In Impoundment by SIC
Code (Survey Database)
Chemical presence in wastewater in impoundment: C23a
(mark as present but quantity unknown or reported
concentration or flux detection ) (consolidated database -
see section A.4.1 and Attachments A6, A7)
Table B-24. Chemical Presence in
Wastewater Effluent by SIC Code
(Survey Database)
Chemical presence in effluent: C24c (mark as present but
quantity unknown or reported concentration or flux
detection) (consolidated database - see section A.4.1 and
Attachments A6, A7)
Table B-25. Chemical Presence in
Sludge by SIC Code (Survey Database)
Chemical presence in sludge: C23b, C24b, or C24d (mark
as present but quantity unknown or reported
concentration or flux detection) (consolidated database -
see section A.4.1 and Attachments A6, A7)
Table B-26. Chemical Presence in
Wastewater Influent by SIC Code (Risk
Input Database)
Chemical presence in influent: all chemicals listed in the
risk input data for wastewater influent (risk input
database - see section A.4.2 and Attachment A8)
Table B-27. Chemical Presence in
Wastewater In Impoundment by SIC
Code (Risk Input Database)
Chemical presence in wastewater in impoundment: all
chemicals listed in the input risk data set for wastewater
in impoundment (risk input database - see section A.4.2
and Attachment A8)
Table B-28. Chemical Presence in
Sludge by SIC Code (Risk Input
Database)
Chemical presence in sludge: all chemicals listed in the
risk input data for sludge (risk input database - see section
A.4.2 and Attachment A8)
Table B-29. Chemicals Cooccurring in
Wastewater by Human Health Effect,
Number of Cooccurring Chemicals, and
Facility at which they Cooccur
If the number of chemicals in wastewater (C23a, C24a, or
C24c) across all impoundments at a facility for a
particular target human health effect was greater than 2,
then the number and list Cooccurring chemicals were
reported by target health effect, number of cooccurrences,
and facility (consolidated database - see section A.4.1 and
Attachments A6, A7)
(continued)
B-6
-------
March 26, 2001
Appendix B
Table B-l. (continued)
Table Number
Description: Survey Question, Data Sources
Table B-30. Facility-Level Cooccurrence
of Chemicals in Wastewater by Human
Health Effect (Survey Database)
Query based on chemical presence in wastewater: C23a,
C24a, C24c (consolidated database: PQU or reported
detection - see section A.4.1 and Attachments A6, A7)
Table B-31. Facility-Level Cooccurrence
of Chemicals in Sludge by Human Health
Effect (Survey Database)
Query based on chemical presence in sludge: C23b,
C24b, C24d (consolidated database: PQU or reported
detection - see section A.4.1 and Attachments A6, A7)
Table B-32. Impoundment-Level
Cooccurrence of Chemicals in
Wastewater by Human Health Effect
(Survey Database)
Query based on chemical presence in wastewater: C23a,
C24a, C24c (consolidated database: PQU or reported
detection - see section A.4.1 and Attachments A6, A7)
Table B-33. Impoundment-Level
Cooccurrence of Chemicals in Sludge by
Human Health Effect (Survey Database)
Query based on chemical presence in sludge: C23b,
C24b, C24d (consolidated database: PQU or reported
detection - see section A.4.1 and Attachments A6, A7)
Table B-34. Facility-Level Cooccurrence
of Chemicals in Wastewater by Human
Health Effect (Risk Input Database)
Query based on chemical presence in wastewater: C23a,
C24a, C24c (risk database: PQU, reported detection, or
reported below detection - see section A.4.2 and
Attachment A8)
Table B-35. Facility-Level Cooccurrence
of Chemicals in Sludge by Human Health
Effect (Risk Input Database)
Query based on chemical presence in sludge: C23b,
C24b, C24d (risk database: PQU, reported detection, or
reported below detection - see section A.4.2 and
Attachment A8)
Table B-36. Impoundment-Level
Cooccurrence of Chemicals in
Wastewater by Human Health Effect
(Risk Input Database)
Query based on chemical presence in wastewater: C23a,
C24a, C24c (risk database: PQU, reported detection, or
reported below detection - see section A.4.2 and
Attachment A8)
Table B-37. Impoundment-Level
Cooccurrence of Chemicals in Sludge by
Human Health Effect (Risk Input
Database)
Query based on chemical presence in sludge: C23b,
C24b, C24d (risk database: PQU, reported detection, or
reported below detection - see section A.4.2 and
Attachment A8)
Table B-38. 50th and 90th Percentile
Wastewater Concentrations in
Impoundment for Selected Chemicals
For selected Toxicity Characteristic (TC) chemicals:
concentration percentiles from C23a (consolidated
database - see section A.4.1 and Attachments A6, A7)
Figure B-l. Arsenic influent and effluent
wastewater concentrations.
For arsenic: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4.1 and Attachments A6, A7)
Figure B-2. Arsenic influent wastewater
concentrations by decharacterization
status.
For arsenic: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A.4.1 and
Attachments A6, A7); decharacterization status: C6
Figure B-3. Arsenic wastewater
concentrations in impoundment (survey
data versus risk input data).
For arsenic: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4.1 and Attachments A6, A7);
concentrations (risk input database - see section A.4.2 and
Attachment A8)
(continued)
B-7
-------
March 26, 2001
Appendix B
Table B-l. (continued)
Table Number
Figure B-4. Barium influent and effluent
wastewater concentrations.
Figure B-5. Barium influent wastewater
concentrations by decharacterization
status.
Figure B-6. Barium wastewater
concentrations in impoundment (survey
data versus risk input data).
Figure B-7. Benzene influent and
effluent wastewater concentrations.
Figure B-8. Benzene influent wastewater
concentrations by decharacterization
status.
Figure B-9. Benzene wastewater
concentrations in impoundment (survey
data versus risk input data).
Figure B-l 0. Cadmium influent and
effluent wastewater concentrations.
Figure B-l 1 . Cadmium influent
wastewater concentrations by
decharacterization status.
Figure B-12. Cadmium wastewater
concentrations in impoundment (survey
data versus risk input data).
Figure B-13. Chloroform influent and
effluent wastewater concentrations.
Figure B-14. Chloroform influent
wastewater concentrations by
decharacterization status.
Figure B-15. Chloroform wastewater
concentrations in impoundment (survey
data versus risk input data).
Description: Survey Question, Data Sources
For barium: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For barium: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A. 4.1 and
Attachments A6, A7); decharacterization status: C6
For barium: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
For benzene: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For benzene: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A. 4.1 and
Attachments A6, A7); decharacterization status: C6
For benzene: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
For cadmium: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For cadmium: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A. 4.1 and
Attachments A6, A7); decharacterization status: C6
For cadmium: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
For chloroform: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For chloroform: influent (C24a) concentrations, PQU
flags, BDLs (consolidated database - see section A.4.1
and Attachments A6, A7); decharacterization status: C6
For chloroform: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
(continued)
B-8
-------
March 26, 2001
Appendix B
Table B-l. (continued)
Table Number
Figure B-l 6. Chromium influent and
effluent wastewater concentrations.
Figure B-l 7. Chromium influent
wastewater concentrations by
decharacterization status.
Figure B - 1 8 . Chromium wastewater
concentrations in impoundment (survey
data versus risk input data).
Figure B-l 9. Cresol influent and effluent
wastewater concentrations.
Figure B-20. Cresol influent wastewater
concentrations by decharacterization
status.
Figure B-21. Cresol wastewater
concentrations in impoundment (survey
data versus risk input data).
Figure B-22. Lead influent and effluent
wastewater concentrations.
Figure B-23. Lead influent wastewater
concentrations by decharacterization
status.
Figure B-24. Lead wastewater
concentrations in impoundment (survey
data versus risk input data).
Figure B-25 . Mercury influent and
effluent wastewater concentrations.
Figure B-26. Mercury influent
wastewater concentrations by
decharacterization status.
Figure B-27. Mercury wastewater
concentrations in impoundment (survey
data versus risk input data).
Description: Survey Question, Data Sources
For chromium: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For chromium: influent (C24a) concentrations, PQU
flags, BDLs (consolidated database - see section A.4.1
and Attachments A6, A7); decharacterization status: C6
For chromium: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
For cresols: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For cresols: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A.4.1 and
Attachments A6, A7); decharacterization status: C6
For cresols: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
For lead: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For lead: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A.4.1 and
Attachments A6, A7); decharacterization status: C6
For lead: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
For mercury: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For mercury: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A.4.1 and
Attachments A6, A7); decharacterization status: C6
For mercury: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
(continued)
B-9
-------
March 26, 2001
Appendix B
Table B-l. (continued)
Table Number
Figure B-28. Methyl ethyl ketone (MEK)
influent and effluent wastewater
concentrations.
Figure B-29. Methyl ethyl ketone (MEK)
influent wastewater concentrations by
decharacterization status.
Figure B-30. Methyl ethyl ketone (MEK)
wastewater concentrations in
impoundment (survey data versus risk
input data).
Figure B-3 1 . Selenium influent and
effluent wastewater concentrations.
Figure B-32. Selenium influent
wastewater concentrations by
decharacterization status.
Figure B-33. Selenium wastewater
concentrations in impoundment (survey
data versus risk input data).
Description: Survey Question, Data Sources
For MEK: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For MEK: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A. 4.1 and
Attachments A6, A7); decharacterization status: C6
For MEK: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
For selenium: influent (C24a) and effluent (C24c)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7)
For selenium: influent (C24a) concentrations, PQU flags,
BDLs (consolidated database - see section A. 4.1 and
Attachments A6, A7); decharacterization status: C6
For selenium: wastewater in impoundment (C23a)
concentrations, PQU flags, BDLs (consolidated database
- see section A.4. 1 and Attachments A6, A7);
concentrations (risk input database - see section A. 4. 2 and
Attachment A8)
B-10
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March 26, 2001
Appendix B
Table B-2. Characteristics of Industrial Impoundments
Characteristic
Direct
Dischargers
Zero
Dischargers
Total
Estimates for All Nonhazardous Industrial Impoundments
Number of facilities
Number of impoundments (based on screener survey)
Number of impoundments (based on long survey)
6,575 (384)
15,992 (2,038)
16,701 (1,756)
884 (178)
1,705 (240)
1,717(421)
7,459 (385)
17,697 (2,048)
18,417 (1,764)
Estimates for Impoundments with Constituents/pH of Concern
Number of facilities
Number of impoundments
Total volume of wastewater managed (metric tons)
Number of facilities that manage decharacterized
wastes
Number of facilities that manage never characteristic
wastes
Number of impoundments that manage decharacterized
wastes
Number of impoundments that manage never
characteristic wastes
Quantity (metric tons) of wastewater managed in
impoundments that manage decharacterized wastes
Quantity (metric tons) of wastewater managed in
impoundments that manage never characteristic wastes
Number of facilities with pH of concern pH<3
pH>ll
Number of impoundments with pH of concern pH<3
pH>ll
Number of facilities that manage any waste exempt or
excluded from RCRA regulations
Number of impoundments that manage any waste
exempt or excluded from RCRA regulations
Number of impoundments with state/local permits
Number of impoundments that have RFAs conducted
3,944(518)
10,987 (1,896)
627,218,336*
(334,849,400)
605 (128)
3,339 (440)
2,167(454)
8,821 (1,715)
481,135,509
(202,260,427)
156,398,430
(43,847,438)
302* (206)
565 (271)
295* (196)
758 (352)
541 (171)
1,587 (537)
9,538 (1,777)
3,761 (1,320)
512(139)
876 (165)
27,250,309*
(14,903,337)
62* (45)
450(112)
140* (115)
736 (137)
532,435*
(463,972)
27,084,601
(12,580,135)
28* (31)
144 (68)
54* (54)
164 (67)
83* (52)
183* (122)
682 (136)
185* (113)
4,457 (522)
11,863 (1,903)
654,468,645*
(334,824,107)
667(133)
3,789 (441)
2,306 (468)
9,557 (1,720)
481,667,944
(202,257,984)
183,483,030
(45,616,418)
330* (208)
709 (276)
349* (204)
921 (358)
625 (178)
1,770(551)
10,220 (1,783)
3,946 (1,325)
B-ll
-------
March 26, 2001
Appendix B
Table B-3. Estimated Number of Facilities with Chemicals/pH of Concern by EPA Region
EPA Region
All Facilities
1
2
3
4
5
6
7
8
9
10
Direct Dischargers
3,944 (348)
87* (50)
100* (66)
585 (210)
1,705 (390)
391 (130)
434* (233)
165* (132)
219* (165)
114* (58)
145* (117)
Zero Dischargers
512(116)
0(0)
83* (49)
75* (47)
103* (55)
28* (29)
89* (51)
28* (29)
0(0)
46* (37)
59* (42)
Total
4,457 (348)
87* (50)
183 (76)
661 (213)
1,808 (393)
419(133)
524 (237)
193* (135)
219* (165)
159 (68)
205* (125)
B-12
-------
March 26, 2001
Appendix B
Table B-4. Estimated Number of Impoundments with Chemicals/pH of
Concern by EPA Region
EPA Region
All impoundments
1
2
3
4
5
6
7
8
9
10
Direct Dischargers
10,987(1,704)
437* (351)
229* (138)
1,895* (1,168)
3,975 (991)
1,064 (329)
1,900* (1,161)
368* (278)
395* (207)
418* (228)
307* (238)
Zero Dischargers
876(137)
0(0)
83* (44)
100* (56)
128 (63)
56* (56)
168* (91)
28* (28)
0(0)
184* (140)
128* (105)
Total
11,863(1,706)
437* (351)
312(143)
1,995* (1,169)
4,103 (993)
1,121 (333)
2,068* (1,165)
396* (279)
395* (207)
601 (268)
434* (260)
B-13
-------
March 26, 2001
Appendix B
Table B-5. Estimated Number of Facilities with Chemicals/pH of Concern by 2-Digit
Standard Industrial Classification (SIC) Code
2-Digit SIC Code
All Facilities
20
22
24
26
28
29
30
32
33
34
36
37
49
51
97
Direct Dischargers
3,944 (348)
236* (236)
157* (127)
243* (122)
244 (83)
819(141)
263 (86)
96* (53)
517(165)
401 (127)
7* (14)
15* (21)
0(0)
333* (199)
491 (243)
122* (122)
Zero Dischargers
512(116)
101* (54)
0(0)
0(0)
25* (27)
28* (29)
62* (44)
19* (23)
149 (66)
27* (28)
24* (26)
0(0)
50* (39)
0(0)
28* (29)
0(0)
Total
4,457 (348)
336* (241)
157* (127)
243* (122)
270 (87)
847 (143)
325 (95)
114* (58)
666 (172)
429 (130)
31* (30)
15* (21)
50* (39)
333* (199)
519(244)
122* (122)
B-14
-------
March 26, 2001
Appendix B
Table B-6. Estimated Number of Impoundments with Chemicals/pH of
Concern by 2-Digit Standard Industrial Classification (SIC) Code
2-Digit SIC Code
All Impoundments
20
22
24
26
28
29
30
32
33
34
36
37
49
51
97
Direct Dischargers
10,987(1,704)
708* (708)
157* (127)
486* (243)
1,340 (400)
2,734 (1,022)
1,230 (252)
119(52)
1,426* (1,001)
884 (229)
7* (13)
37* (29)
0(0)
419* (220)
1,197* (636)
244* (244)
Zero Dischargers
876(137)
267* (153)
0(0)
0(0)
25* (25)
28* (28)
130* (106)
74* (74)
174 (63)
27* (27)
47* (47)
0(0)
75* (54)
0(0)
28* (28)
0(0)
Total
11,863(1,706)
974* (724)
157* (127)
486* (243)
1,365 (400)
2,762 (1,022)
1,361 (273)
193 (80)
1,600* (1,003)
912 (230)
54* (48)
37* (29)
75* (54)
419* (220)
1,225* (637)
244* (244)
B-15
-------
March 26, 2001
Appendix B
Table B-7. Estimated Quantity of Wastewater (metric tons) Managed in Impoundments
with Chemicals/pH of Concern, by 2-Digit Standard Industrial Classification (SIC) Code
2-Digit SIC Code
All Impoundments
20
22
24
26
28
29
30
32
33
34
36
37
49
51
97
Direct Dischargers
626,495,468
(200,068,968)
13,296,807*
(13,296,807)
388,459* (293,594)
10,042,479*
(9,372,635)
426,454,295
(195,842,259)
60,443,443
(24,132,932)
36,028,791*
(21,167,383)
67,914* (61,270)
619,108* (609,131)
46,970,517*
(30,868,752)
7,038* (12,912)
502,008* (661,349)
0(0)
4,259,858* (3,85 1,949)
27,345,022*
(26,311,362)
69,729* (69,729)
Zero Dischargers
26,818,959
(11,992,958)
18,714,576*
(11,627,671)
0(0)
0(0)
1,774,657* (1,774,657)
139,799* (139,799)
443,535* (443,535)
337,517* (337,517)
5,118,566* (4,941,102)
86,284* (86,284)
48,265* (48,265)
0(0)
144,692* (143,530)
0(0)
11,067* (11,067)
0(0)
Total
653,314,426
(200,145,906)
32,011,382*
(17,663,742)
388,459* (293,594)
10,042,479*
(9,372,635)
428,228,953
(195,841,439)
60,583,241
(24,132,547)
36,472,326*
(21,166,930)
405,432* (342,900)
5,737,674* (4,940,840)
47,056,801*
(30,868,586)
55,303* (48,775)
502,008* (661,349)
144,692* (143,530)
4,259,858* (3,85 1,949)
27,356,090*
(26,311,364)
69,729* (69,729)
B-16
-------
March 26, 2001
Appendix B
Table B-8. Distribution of Ages of Impoundments with Chemicals/pH of
Concern in Operation in Year 2000
Age of Impoundment
All Impoundments In Operation in 2000
5 years
15 years
25 years
35 years
45 years
55 years
65 years
101 years
Direct
Dischargers
9,083(1,751)
1,970 (905)
1,371 (414)
3,325 (1,095)
1,144(359)
1,122(389)
110* (60)
34* (28)
7* (13)
Zero
Dischargers
849 (137)
205 (78)
100(49)
331(94)
188* (142)
25* (25)
0(0)
0(0)
0(0)
Total
9,932 (1,753)
2,175(908)
1,471 (416)
3,656 (1,099)
1,332(386)
1,147(389)
110* (60)
34* (28)
7* (13)
B-17
-------
March 26, 2001
Appendix B
Table B-9. Distribution of Lifetimes of Impoundments with Chemicals/pH of
Concern that have Permanently Ceased Receiving Wastes
Age Range
All Closed Impoundments
0-5 years
6-10 years
11-15 years
16-20 years
21-25 years
26-30 years
31-35 years
36-40 years
4 1-45 years
46-50 years
51-55 years
56-60 years
Direct Dischargers
1,630(533)
93* (52)
29* (26)
798* (453)
143* (76)
116(55)
37* (29)
31* (27)
22* (22)
28* (26)
262* (241)
47* (47)
24* (24)
Zero Dischargers
25* (25)
0(0)
0(0)
25* (25)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
Total
1,655 (534)
93* (52)
29* (26)
823* (454)
143* (76)
116(55)
37* (29)
31* (27)
22* (22)
28* (26)
262* (241)
47* (47)
24* (24)
B-18
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March 26, 2001
Appendix B
Table B-10. Estimated Number of Facilities with Chemicals/pH of
Concern by Treatment Type
Treatment Type
Aeration
Flocculation
Sedimentation
Filtration
Coagulation
Disinfection
Precipitation
Ion exchange
Adsorption
Chemical oxidation
Nitrification
Denitrification
Carbonaceous
biochemical oxygen
demand (CBOD) removal
Anaerobic biological
treatment process
Aerobic biological
treatment process
Facultative treatment
process
pH adjustment
Temperature adjustment
Other
No treatment
Direct Dischargers
920 (221)
239* (232)
1,780 (278)
38* (34)
156* (130)
7* (15)
200* (133)
0(0)
7* (15)
76* (49)
97* (55)
63* (44)
122* (61)
399* (266)
612(268)
150(68)
795 (307)
449 (182)
498(181)
2,091 (273)
Zero Dischargers
160 (69)
0(0)
217(80)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
36* (36)
29* (30)
29* (30)
65* (46)
0(0)
36* (36)
29* (30)
0(0)
0(0)
26* (29)
232 (83)
Total
1,081 (226)
239* (232)
1,997 (285)
38* (34)
156* (130)
7* (15)
200* (133)
0(0)
7* (15)
112* (60)
127 (62)
92* (53)
187 (75)
399* (266)
647 (271)
180 (74)
795 (307)
449(182)
525 (183)
2,323 (280)
B-19
-------
March 26, 2001
Appendix B
Table B-ll. Estimated Number of Lined Impoundments with Chemicals/pH of
Concern by 2-Digit Standard Industrial Classification (SIC) Code
2-Digit SIC Code
All Impoundments
20
22
24
26
28
29
30
32
33
34
36
37
49
51
97
Direct Dischargers
4,444(1,148)
708* (708)
21* (22)
233* (233)
544 (229)
1,466* (790)
290 (88)
44* (32)
0(0)
460(166)
7* (13)
37* (29)
0(0)
177* (163)
214* (214)
244* (244)
Zero Dischargers
403 (126)
110* (78)
0(0)
0(0)
0(0)
28* (28)
102* (102)
37* (37)
25* (25)
0(0)
47* (47)
0(0)
25* (25)
0(0)
28* (28)
0(0)
Total
4,847(1,155)
818* (712)
21* (22)
233* (233)
544 (229)
1,494* (791)
392(135)
81* (46)
25* (25)
460 (166)
54* (48)
37* (29)
25* (25)
177* (163)
242* (216)
244* (244)
B-20
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March 26, 2001
Appendix B
Table B-12. Frequency of Liner Usage for Impoundments by Age of Impoundment
Year Impoundment
Began Receiving Waste
Number of Impoundments
% of Total Impoundments
Before
1900
0
0
1900-
1939
114
1
1940-
1949
409
3
1950-
1959
1,213
10
1960-
1969
1,446
12
1970-
1979
4,226
36
1980-
1989
2,073
17
1990-
2000
2,382
20
Total
11,863
100
Impoundments with Liners
Number of Lined
Impoundments
% of Lined Impoundments
for Given Year Range
% of Total Lined
Impoundments
% of Lined Impoundments
with No Liner Failure
% of Lined Impoundments
with Liner Failure
0
0
0
0
0
79
68
2
2
0
267
65
6
6
0
95
8
2
2
1
356
25
7
8
4
1,887
45
40
35
73
631
30
13
13
17
1,440
60
30
34
4
4,755
40
100
100
100
Impoundments without Liners
Number of Unlined
Impoundments
% of Unlined
Impoundments for Given
Year Range
% of Total Unlined
Impoundments
0
0
0
35
31
0.5
142
35
2
1,118
92
16
1,090
75
15
2,339
55
33
1,442
70
20
942
40
13
7,108
60
100
B-21
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March 26, 2001
Appendix B
Table B-13. Estimated Number of Overtopping Events at Impoundments with
Chemicals/pH of Concern by Duration
Duration
All Overtopping Events
1 Day
2 Days
4 Days
1 Month
2 Months
5 Months
Cannot Be Determined
Direct Dischargers
2,040(761)
932 (428)
96* (79)
116* (116)
4* (9)
3* (9)
7* (13)
882* (538)
Zero Dischargers
61* (44)
61* (44)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
Total
2,101 (763)
992 (430)
96* (79)
116* (116)
4* (9)
3* (9)
7* (13)
882* (538)
B-22
-------
March 26, 2001
Appendix B
Table B-14. Estimated Number of People, Residences, Drinking Water Wells,
and Schools within Distance Ranges
Distance from Impoundment
Number
of people within
0-150m
151-500m
501-lOOOm
1001 -2000m
Number
of residences within
0-150m
151-500m
501-lOOOm
1001 -2000m
Number of drinking water
wells within
0-150m
151-500m
501-lOOOm
1001 -2000m
Number
of schools within
0-150m
151-500m
501-lOOOm
1001 -2000m
Direct Dischargers
47,979 (14,524)
580,127(162,685)
2,938,328(964,251)
12,434,974
(2,899,926)
19,687 (5,836)
249,429 (72,408)
1,202,653 (379,787)
5,072,366
(1,135,606)
567* (3 17)
12,064* (6,342)
53,528 (22,575)
195,041 (55,029)
0(N/A)
541* (321)
2,146 (1,032)
8,116(2,069)
Zero Dischargers
3,600(1,079)
83,253 (36,390)
346,050* (184,390)
1,979,202(946,061)
1,540 (453)
35,983 (15,495)
139,182* (69,912)
826,444 (390,984)
321* (200)
1,663* (1,317)
2,618* (1,557)
9,944* (5,097)
0 (N/A)
0(N/A)
243* (163)
874 (387)
Total
51,579(14,564)
663,380 (166,705)
3,284,378(981,722)
14,414,175
(3,050,344)
21,227(5,854)
285,411(74,047)
1,341,834(386,168)
5,898,810
(1,201,029)
888 (379)
13,728 (6,476)
56,146 (22,622)
204,984(55,165)
0(N/A)
541* (321)
2,390 (1,044)
8,990(2,104)
B-23
-------
March 26, 2001
Appendix B
Table B-15. Estimated Number of Surface Impoundments with Chemicals/pH of Concern
That Had a State or Local Permit for Wastewater, Sludge Management, Groundwater
Protection, or Air Emissions by 2-Digit Standard Industrial Classification (SIC) Code
2-Digit SIC
All Industries
20 (Food and Kindred Products)
22 (Textile Mill Products)
24 (Lumber and Wood Products)
26 (Paper and Allied Products)
28 (Chemicals and Allied Products)
29 (Petroleum and Coal Products)
30 (Rubber and Miscellaneous Plastic
Products)
32 (Stone, Clay, and Glass Products)
33 (Primary Metal Industries)
34 (Fabricated Metal Products)
36 (Electronic and Other Electrical
Equipment)
37 (Transportation Equipment)
49 (Electric, Gas, and Sanitary Services)
5 1 (Wholesale Trade, Nondurable Goods)
97 (National Security and International
Affairs)
Direct
Dischargers
9,159
708
21
233
1,222
2,515
965
98
1,199
488
7
7
0
256
1,197
244
Zero
Dischargers
643
267
0
0
25
28
28
37
103
27
24
0
75
0
28
0
All
Impoundments
9,802
974
21
233
1,247
2,543
993
135
1,302
516
31
7
75
256
1,225
244
B-24
-------
March 26, 2001
Appendix B
Table B-16. Estimated Number of Impoundments in Population B Which Were
Solid Waste Management Units at RCRA Treatment, Storage, and Disposal Facilities
(TSDs)Evaluated During a RCRA Facility Assessment or Similar Action, by 2-Digit
Standard Industrial Classification (SIC) Code
2-Digit SIC
All Industries
26 (Paper and Allied Products)
28 (Chemicals and Allied Products)
29 (Petroleum and Coal Products)
33 (Primary Metal Industries)
37 (Transportation Equipment)
49 (Electric, Gas, and Sanitary Services)
Direct
Dischargers
3,288
20
2,171
778
240
0
79
Zero
Dischargers
146
0
0
68
27
50
0
All
Impoundments
3,433
20
2,171
846
267
50
79
B-25
-------
March 26, 2001
Appendix B
Table B-17. Estimated Number of Impoundments with Chemicals/pH of Concern that
Received Any Waste Exempt or Excluded from RCRA Regulations, by 2-Digit Standard
Industrial Classification (SIC) Code
2-Digit SIC (Industry)
All Industries
22 (Textile Mill Products)
26 (Paper and Allied Products)
28 (Chemicals and Allied Products)
29 (Petroleum and Coal Products)
32 (Stone, Clay, and Glass Products)
33 (Primary Metal Industries)
34 (Fabricated Metal Products)
36 (Electronic and Other Electrical
Equipment)
37 (Transportation Equipment)
49 (Electric, Gas, and Sanitary
Services)
Direct
Dischargers
1,534
21
641
588
206
0
28
7
22
0
22
Zero
Dischargers
173
0
0
0
102
20
0
0
0
50
0
All
Impoundments
1,706
21
641
588
308
20
28
7
22
50
22
B-26
-------
March 26, 2001
Appendix B
Table B-18. Estimated Quantity (Metric Tons) of Wastewater Managed in Impoundments
with Chemicals/pH of Concern That is Exempt or Excluded from Regulation
Regulation
All Regulations
§260.22 and §3001(f)
§261.3(a)(2)(i)
§261.3(a)(2)(iii)
§261.3(a)(2)(iv)
§261.3(a)(2)(iv)(A)
§261.3(a)(2)(iv)(B)
§261.3(a)(2)(iv)(C)
§261.3(a)(2)(iv)(D)
§261.3(a)(2)(iv)(E)
§261.3(a)(2)(iv)(F)
§261.3(a)(2)(iv)(G)
§261.3(c)(2)(ii)
§261.3(c)(2)(ii)(A)
§261.3(c)(2)(ii)(B)
§261.3(c)(2)(ii)(C)
§261.3(c)(2)(ii)(D)
§261.4(a)
§261.4(a)(l)
§261.4(a)(2)
§261.4(a)(3)
§261.4(a)(4)
§261.4(a)(5)
§261.4(a)(6)
§261.4(a)(7)
§261.4(a)(9)
§261.4(b)
§261.4(b)(l)
§261.4(b)(2)
§261.4(b)(3)
§261.4(b)(4) and §3001(b)(3)(A)(i)
§261.4(b)(5) and §3001(b)(12)(A)
§261.4(b)(6)
§261.4(b)(7) and §3001(b)(3)(A)(ii)
§261.4(b)(8) and §3001(b)(3)(A)(iii)
§261.4(b)(10)
§268.4 and §3005(j)(ll)
§268.5 and §3004(h)
§268.6 and §3004(d)
§3004(h)
Other
Direct
Dischargers
94,472,856
0
0
16,731,865
86,328
8,221
0
95,669
1,168,963
1,845,175
0
0
0
0
0
0
0
1,000,407
1,606,185
13,366,523
0
0
0
2,016,833
0
0
0
0
0
0
7,836,906
0
0
8,265,414
0
0
0
0
0
0
40,444,366
Zero Dischargers
4,295,692
0
0
0
0
0
0
10,098
6,859
6,859
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4,271,877
0
0
0
0
0
0
0
Total
98,768,548
0
0
16,731,865
86,328
8,221
0
105,767
1,175,821
1,852,033
0
0
0
0
0
0
0
1,000,407
1,606,185
13,366,523
0
0
0
2,016,833
0
0
0
0
0
0
7,836,906
0
0
12,537,291
0
0
0
0
0
0
40,444,366
B-27
-------
March 26, 2001
Appendix B
Table B-19a. Chemicals: Presence and Volume in Wastewater
(for Impoundments with Chemicals/pH of Concern)
Chemical
Barium
Zinc
Copper
Nickel
Lead
Chromium
Manganese
Arsenic
Selenium
Mercury
Toluene
Fluoride
Xylenes, mixed isomers [Xyenes]
Chloroform [Trichloromethane]
Phenol
Cadmium
Ethyl benzene
Benzene
Vanadium
Molybdenum
Acetone [2-Propanone]
Carbon disulfide
Sulfide
Antimony
Methyl ethyl ketone
[2-Butanone][MEK]
Naphthalene
Number of
Impoundments
with Chemical
Present in
Wastewater *
5,609
5,537
4,435
4,332
4,187
3,840
2,672
2,163
2,101
1,943
1,933
1,640
1,591
1,570
1,434
1,325
1,176*
1,108*
1,086
1,062
1,047*
1,023*
915
907
903
884*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
86,867*
42,413
6,690*
743,304*
1,288*
2,340*
273,073*
1,993*
1,395*
138*
190*
881,320*
35*
3,000*
2,505*
125*
11*
51*
5,519*
471*
385,119*
130*
62,403*
47*
25,812*
267*
Influent
(kg/yr)
4,045,548*
44,137,843*
232,239
232,559*
81,436*
72,702*
17,537,976*
39,721
30,767*
10,977*
6,450*
655,872,641*
4,672*
149,528*
449,842*
5,756*
4,965*
4,164*
32,666*
19,499*
48,558,027*
14,416*
7,273,444*
2,530*
1,554,826*
7,890*
Effluent
(kg/yr)
334,235,652*
26,175,024*
1,197,404*
709,369*
325,629*
921,257*
697,272,315*
335,748*
1,039,495*
15,523*
6,348*
709,804,880*
3,294*
80,860*
2,539,884*
10,984*
3,207*
2,262*
25,233*
35,317*
24,103,457*
939,914*
5,472,858*
2,450*
11,445,363*
1,594,276*
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-28
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
Methanol [methyl alcohol]
Silver
Chromium VI [Hexavalent Chromium]
Beryllium
Ethylene glycol
Cyanide
Formaldehyde
Acetaldehyde [Ethanal]
Cresols
2,4,5-Trichlorophenol
Methylene chloride [Dichloromethane]
Cobalt
Bis(2-ethylhexyl) phthalate [Dioctyl
phthalate]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Bromodichloromethane
[Dichlorobromomethane]
Chloromethane [Methyl chloride]
Formic Acid
Bromoform [Tribromomethane]
Thallium
Chlorodibromomethane
[Dibromochloromethane]
n-Dioctyl phthalate
Chloroethane [Ethyl chloride]
o-Xylene
Bromomethane [Methyl bromide]
Carbon tetrachloride
Number of
Impoundments
with Chemical
Present in
Wastewater *
807
748
745
722
710*
653
626*
621*
535*
484*
481*
470
451*
392*
379*
373*
360*
336*
309*
291*
280*
253*
252*
232*
232*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
6,147,194*
72*
40*
101*
23,303*
377*
479*
14,858*
437*
16*
254*
18*
16*
0
1,823*
209*
0
29,772*
5*
9,464*
7*
29*
5*
664*
13*
Influent
(kg/yr)
636,494,373
2,749*
5,559*
618*
9,488,441*
173,996*
3,739,508*
5,854,234*
65,631*
0
6,348*
868*
9*
0
169*
17,009*
8,804,297*
301*
1,931*
54*
0
0
427*
0
0
Effluent
(kg/yr)
3,994,144,150*
2,658*
9,790*
1,158*
17,246*
91,663*
1,604,584*
237,461*
2,908,262*
0
9,658*
945*
6,193*
0
28,669*
4,459*
1,580*
468,223*
1,693*
148,767*
302*
456*
427*
10,430*
203*
1. Chemical presence in influent, effluent, or within impoundment, as indicated by
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
reported value or check for
B-29
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
Heptachlor epoxide, alpha, beta, and
gamma isomers
p-Cresol [4-Methyl phenol]
Benzyl alcohol
Pyrene
Aniline
2,4,6-Trichlorophenol
Methyl tert-butyl ether [MTBE]
o-Cresol [2 -Methyl phenol]
Tetrachlorodibenzofurans [TCDFs]
m-Cresol [3 -Methyl phenol]
Methoxychlor
Tetrachloroethylene
[Perchloroethylene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
Cyanide, amenable
2,4-D [2,4-Dichlorophenoxyacetic
acid]
2,4-Dinitrotoluene
Chlordane, alpha & gamma isomers
Endrin
Heptachlor
Lindane
[gamma-Hexachlorocyclohexane]
[gamma-BHC]
Silvex
[2,4,5-Trichlorophenoxypropionic
acid]
Toxaphene [Chlorinated camphene]
Chrysene
Number of
Impoundments
with Chemical
Present in
Wastewater *
230*
229*
207*
194
190*
188*
187*
184*
182*
159*
156*
152*
143*
142*
136*
136*
136*
136*
136*
136*
136*
136*
136
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0*
16*
473*
8*
699*
16*
412*
16*
0*
16*
5*
2*
16*
14*
2*
16*
1*
0*
0*
0*
0*
8*
10*
Influent
(kg/yr)
49*
150*
87,068*
1,259*
75,635*
0
0
86*
1*
0
222*
53*
0
8,514*
0
0
0
0
0
0
0
0
197*
Effluent
(kg/yr)
31*
276*
41,424*
2*
64,560*
0
0*
0
4*
0
0
53*
0
1,776*
0
0
0
0
0
0
0
0
12*
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-30
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
Styrene
2,3,7,8-TCDD
[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
alpha-Hexachlorocyclohexane
[alpha-BHC]
Di-n-butyl phthalate
Acenaphthene
Benzo(a)pyrene
Fluoranthene
Tetrachlorodibenzo-p-dioxins
[TCDDs]
Benzo[a]anthracene
Anthracene
Fluorene
1 , 1 -Dichloroethylene [ Vinylidene
chloride]
Polychlorinated biphenyls [Aroclors]
N,N-Dimethyl formamide [DMF]
2,4-Dichlorophenol
2-Chlorophenol [o-Chlorophenol]
Hexachlorodibenzofurans [HxCDFs]
1,2-Dichloropropane [Propylene
dichloride]
1,2-Dichloroethane [Ethylene
dichloride]
Ethylene thiourea
Thiram [Thiuram]
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
Cumene [Isopropyl benzene]
Number of
Impoundments
with Chemical
Present in
Wastewater *
129*
121*
115*
114*
106*
103*
100*
91*
85*
85*
66*
57*
55*
52*
52*
52*
51*
50*
49*
46*
46*
46*
44*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
52*
0
1*
0
0
0*
0*
0
0*
0
0
0*
1*
0
0
0
0*
18*
0*
0
0
0
0
Influent
(kg/yr)
69,572*
0*
106*
0*
109*
102*
178*
0
23*
28*
41*
79*
2,907*
0
0
0
0*
20,848*
332*
0
0
0
0
Effluent
(kg/yr)
28,460*
0*
49*
0
0
1*
9*
0
2*
0
5*
79*
6,061*
0
0
0
0*
10,039*
21*
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-31
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
n-Hexane
Acrylonitrile
1,1,1-Trichloroethane [Methyl
chloroform]
Epichlorohydrin
[ 1 -Chloro-2,3 -epoxypropane]
2,4-Dimethylphenol
Hexachlorodibenzo-p-dioxins
[HxCDDs]
Pentachlorodibenzofurans [PeCDFs]
1,4-Dioxane [1,4-Diethyleneoxide]
Benzo(b)fluoranthene
Bis(2-chloroisopropyl) ether [2,2
-Dichloroisopropyl ether]
Cyclohexanone
Pentachlorophenol [PCP]
Indeno(l,2,3-cd) pyrene
Acrolein [2-propenal]
Allyl alcohol
Dibenz[a,h]anthracene
Ethylidene dichloride
[ 1 , 1 -Dichloroethane]
Pyridine
Chlorobenzene
Diethyl phthalate [DEP]
Vinyl acetate
Chloroprene [2-Chloro-l,3-butadiene]
1 ,2,4-Trichlorobenzene
m-Xylene
p-Xylene
Number of
Impoundments
with Chemical
Present in
Wastewater *
44*
43*
43*
42*
42*
41*
41*
40*
40*
36*
35*
35*
33*
32*
31*
29*
29*
24*
22*
22*
22*
22*
21*
21*
21*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0
3*
3*
0
14*
0
0
107*
0*
53*
88*
0
0
18*
5,128*
0
1*
0
0
0
0
0
0
0*
0*
Influent
(kg/yr)
0
1,360*
0*
0
3,487*
0
0
32,468*
34*
46,503*
20,485*
0
25*
0
1,636,554*
10*
0
191*
0*
3*
0
0
1*
123*
123*
Effluent
(kg/yr)
0
1,380*
0
0
379*
0*
0*
4,811*
1*
29,530*
5,051*
9*
2*
0
471,788*
1*
0
0
0
0
0
0
0
123*
123*
1. Chemical presence in influent, effluent, or within impoundment, as indicated by
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
reported value or check for
B-32
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
Ethyl acetate
Ethyl ether [Diethyl ether]
Methyl methacrylate
Ethylene dibromide
[ 1 ,2-Dibromoethane]
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
Trichloroethylene [TCE]
1 , 1 ,2-Trichloroethane [Vinyl
trichloride]
2,6-Dinitrotoluene
Allyl chloride
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Triethylamine
Vinyl chloride [chloroethylene]
2,3,4,6-Tetrachlorophenol
n-Butyl alcohol [n-Butanol]
Hexachlorobenzene
2,4-Dinitrophenol
Dimethyl phthalate [DMP]
Acrylic acid [propenoic acid]
Acetonitrile [Methyl cyanide]
beta-Hexachlorocyclohexane
[beta-BHC]
Ethylene oxide
Furfural
Propylene oxide [1,2-Epoxypropane]
Cyclohexanol
Isobutyl alcohol [Isobutanol]
Number of
Impoundments
with Chemical
Present in
Wastewater *
16*
16*
15*
15*
15*
15*
14*
14*
14*
14*
14*
14*
14*
11*
11*
8*
8*
8*
7*
7*
6*
5*
4*
1*
1*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
242*
0
0
2*
0
0
100*
0
0
0
0
0
0
0
0
3*
0
3*
76*
0
30*
0
0
Influent
(kg/yr)
187,466*
898*
124,055*
0
0
0
0*
0
46,234*
0
0
0*
0
388,258*
0
0
0
769,840*
0
168*
42,880*
7,266*
11,052*
0
0
Effluent
(kg/yr)
0
0
17,782*
0
0
0
0
1,034*
9,484*
54*
0
0
0
247*
0
0
0
2,307*
0
168*
58*
0
0
0
0
1. Chemical presence in influent, effluent, or within impoundment, as indicated by
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
reported value or check for
B-33
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
1,1, 1 ,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
1 , 1 ,2-Trichloro-l ,2,2-trifluoroethane
[FreonllS]
1 ,2,3 -Trichloropropane
1,2,4,5-Tetrachlorobenzene
l,2-Dibromo-3-chloropropane
1 ,2-Diphenylhydrazine
1,2-Epoxybutane [1,2-Butylene oxide]
1 , 3 ,5 -Trinitrobenzene
[sym-Trinitrobenzene]
1,3 -Butadiene
1,3-Dinitrobenzene [m-Dinitrobenzene]
1 , 3 -Phenylenediamine
[m-Phenylenediamine]
2,4,5-Trichlorophenoxyacetic acid
[2,4,5,-T]
2,4-Toluenediamine
[2,4-Diaminotoluene]
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
2-Ethoxyethanol acetate [2-EEA]
2-Methoxyethanol [methyl cellosolve]
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-34
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Nitropropane
3,3 -Dichlorobenzidine
3,3 -Dimethoxybenzidine
3,3 -Dimethylbenzidine
3 ,4-Dimethylphenol
3 -Methylcholanthrene
4,4 -Methylene bis(2-chloroaniline)
4-Chloroaniline
[p-aminochlorobenzene]
7, 12-Dimethylbenz[a]anthracene
Acetophenone
Acrylamide
Aldicarb
Aldrin
Ammonium vanadate
Amonium perchlorate
Aramite
Benzidine
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-35
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
Benzyl chloride
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Butyl benzyl phthalate
Chloral [Trichloroacetaldehyde]
Chloral hydrate [Trichloroacetaldehyde
hydrate]
Chlorobenzilate
Chloromethyl Methyl Ether
cis- 1 ,2-Dichloroethylene
cis- 1 ,3 -Dichloropropylene
Cyanogen bromide [Bromine cyanide]
Cyanogen chloride [Chlorine cyanide]
Diallate
Dichlorodifluoromethane [CFC-12]
Dieldrin
Diethylstilbestrol [DBS]
Dimethoate
Dinoseb
[2-sec-Butyl-4,6-dinitrophenol]
Diphenylamine
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-36
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
Direct Black 3 8
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Ethyl methacrylate
Ethyl methanesulfonate
Furan
Glycidylaldehyde
Hexachloro- 1 ,3 -butadiene
[Hexachlorobutadiene]
Hexachlorocyclopentadiene
Hexachloroethane
Hexachlorophene
Hydrazine
Isophorone
Kepone
Maleic anhydride
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-37
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
Maleic hydrazide
Methacrylonitrile
Methomyl
Methyl parathion
Methylene bromide [Dibromomethane]
Nickel Subsulfide
Nitrobenzene
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitro so -N-methy lethy lamine
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
o-Toluidine
p,p -ODD
p,p -DDE
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-38
-------
March 26, 2001
Appendix B
Table B-19a. (continued)
Chemical
p,p -DDT
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins
[PeCDDs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Perchlorate
Phorate
Phthalic anhydride
Pronamide
p-Toluidine
Safrole
Strychnine
Styrene oxide
Tetraethyldithiopyrophosphate
[Sulfotepp]
trans-l,2-Dichloroethylene
trans- 1 , 3 -Dichloropropylene
Trichlorofluoromethane
[Trichloromonofluoromethane]
[CFC-11]
Tris(2,3-dibromopropyl) phosphate
Warfarin
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-39
-------
March 26, 2001
Appendix B
Table B-19b. Standard Errors for Chemicals: Presence and Volume in Wastewater
(For Impoundments with Chemicals/pH of Concern)
Chemical
Barium
Zinc
Copper
Nickel
Lead
Chromium
Manganese
Arsenic
Selenium
Mercury
Toluene
Fluoride
Xylenes, mixed isomers [Xyenes]
Chloroform [Trichloromethane]
Phenol
Cadmium
Ethyl benzene
Benzene
Vanadium
Molybdenum
Acetone [2-Propanone]
Carbon disulfide
Sulfide
Antimony
Methyl ethyl ketone
[2-Butanone][MEK]
Naphthalene
Number of
Impoundments
with Chemical
Present in
Wastewater *
1,616
1,319
1,029
1,360
1,218
905
736
692
989
704
869
535
776
620
330
361
665*
665*
433
373
601*
678*
381
333
398
647*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
92,570*
19,623
4,694*
735,781*
1,161*
1,468*
198,223*
1,087*
1,485*
126*
293*
932,880*
22*
2,376*
1,945*
90*
7*
71*
5,016*
306*
511,381*
140*
94,198*
31*
23,992*
448*
Influent (kg/yr)
3,359,085*
69,191,620*
98,639
137,148*
68,854*
42,265*
9,291,106*
19,008
18,329*
10,071*
8,252*
652,297,404*
6,637*
120,208*
305,642*
4,270*
4,228*
3,496*
32,051*
13,414*
64,548,719*
17,303*
7,911,353*
2,745*
1,130,593*
6,804*
Effluent
(kg/yr)
601,022,558*
41,154,732*
1,758,524*
954,657*
472,479*
1,474,002*
1,217,759,748*
458,257*
1,805,473*
14,620*
8,050*
645,992,631*
5,440*
63,104*
4,323,561*
8,405*
4,204*
2,205*
30,889*
18,996*
40,066,547*
2,306,653*
5,481,577*
2,405*
18,400,064*
2,893,890*
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-40
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
Methanol [methyl alcohol]
Silver
Chromium VI [Hexavalent
Chromium]
Beryllium
Ethylene glycol
Cyanide
Formaldehyde
Acetaldehyde [Ethanal]
Cresols
2,4,5-Trichlorophenol
Methylene chloride
[Dichloromethane]
Cobalt
Bis(2-ethylhexyl) phthalate [Dioctyl
phthalate]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Bromodichloromethane
[Dichlorobromomethane]
Chloromethane [Methyl chloride]
Formic Acid
Bromoform [Tribromomethane]
Thallium
Chlorodibromomethane
[Dibromochloromethane]
n-Dioctyl phthalate
Chloroethane [Ethyl chloride]
o-Xylene
Bromomethane [Methyl bromide]
Number of
Impoundments
with Chemical
Present in
Wastewater *
362
289
317
291
373*
239
359*
357*
356*
374*
244*
233
260*
350*
234*
234*
275*
242*
203*
234*
236*
233*
232*
232*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
5,208,393*
50*
22*
84*
22,348*
473*
584*
14,707*
404*
16*
184*
16*
12*
N/A
1,822*
180*
N/A
29,770*
5*
9,464*
9*
29*
4*
664*
Influent (kg/yr)
289,572,696
2,408*
3,947*
585*
27,583,115*
191,511*
8,209,467*
5,117,810*
58,808*
N/A
7,566*
1,407*
8*
N/A
206*
28,116*
10,828,275*
284*
3,488*
40*
N/A
N/A
715*
N/A
Effluent
(kg/yr)
6,024,051,004*
2,392*
9,878*
779*
23,388*
108,534*
1,451,442*
210,533*
4,970,921*
N/A
9,224*
1,415*
9,681*
N/A
28,633*
3,056*
4,442*
467,897*
3,020*
148,750*
796*
450*
715*
10,430*
1. Chemical presence in influent, effluent, or within impoundment, as indicated by
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
reported value or check for
B-41
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
Carbon tetrachloride
Heptachlor epoxide, alpha, beta, and
gamma isomers
p-Cresol [4-Methyl phenol]
Benzyl alcohol
Pyrene
Aniline
2,4,6-Trichlorophenol
Methyl tert-butyl ether [MTBE]
o-Cresol [2 -Methyl phenol]
Tetrachlorodibenzofurans [TCDFs]
m-Cresol [3 -Methyl phenol]
Methoxychlor
Tetrachloroethylene
[Perchloroethylene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
Cyanide, amenable
2,4-D [2,4-Dichlorophenoxyacetic
acid]
2,4-Dinitrotoluene
Chlordane, alpha & gamma isomers
Endrin
Heptachlor
Lindane
[gamma-Hexachlorocyclohexane]
[gamma-BHC]
Silvex
[2,4,5-Trichlorophenoxypropionic
acid]
Toxaphene [Chlorinated camphene]
Number of
Impoundments
with Chemical
Present in
Wastewater *
232*
166*
145*
154*
72
136*
142*
106*
139*
95*
137*
137*
137*
136*
106*
136*
136*
136*
136*
136*
136*
136*
136*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
13*
0.08*
16*
468*
7*
699*
16*
412*
16*
0.000*
16*
5*
2*
16*
57*
2*
16*
0.8*
0.2*
0.08*
0.08*
0.2*
8*
Influent (kg/yr)
N/A
56*
508*
84,668*
1,677*
75,635*
N/A
N/A
290*
1*
N/A
326*
53*
N/A
36,182*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
203*
52*
277*
49,993*
3*
64,560*
N/A
0.4*
N/A
6*
N/A
N/A
53*
N/A
3,700*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-42
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
Chrysene
Styrene
2,3,7,8-TCDD
[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
alpha-Hexachlorocyclohexane
[alpha-BHC]
Di-n-butyl phthalate
Acenaphthene
Benzo(a)pyrene
Fluoranthene
Tetrachlorodibenzo-p-dioxins
[TCDDs]
Benzo[a]anthracene
Anthracene
Fluorene
1 , 1 -Dichloroethylene [ Vinylidene
chloride]
Polychlorinated biphenyls [Aroclors]
N,N-Dimethyl formamide [DMF]
2,4-Dichlorophenol
2-Chlorophenol [o-Chlorophenol]
Hexachlorodibenzofurans [HxCDFs]
1,2-Dichloropropane [Propylene
dichloride]
1,2-Dichloroethane [Ethylene
dichloride]
Ethylene thiourea
Thiram [Thiuram]
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
Number of
Impoundments
with Chemical
Present in
Wastewater *
67
66*
82*
115*
67*
54*
55*
53*
55*
51*
50*
39*
57*
39*
41*
41*
41*
42*
38*
34*
46*
46*
46*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
10*
74*
N/A
0.8*
N/A
N/A
0.02*
0.09*
N/A
0.08*
N/A
N/A
0.3*
1*
N/A
N/A
N/A
0.000*
24*
0.1*
N/A
N/A
N/A
Influent (kg/yr)
148*
80,509*
0.002*
106*
0.04*
516*
83*
352*
N/A
37*
55*
42*
79*
3,767*
N/A
N/A
N/A
0.02*
23,714*
1,082*
N/A
N/A
N/A
Effluent
(kg/yr)
14*
50,226*
0.002*
81*
N/A
N/A
2*
14*
N/A
2*
N/A
10*
79*
6,545*
N/A
N/A
N/A
0.002*
16,607*
54*
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-43
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
Cumene [Isopropyl benzene]
n-Hexane
Acrylonitrile
1,1,1-Trichloroethane [Methyl
chloroform]
Epichlorohydrin
[ 1 -Chloro-2,3 -epoxypropane]
2,4-Dimethylphenol
Hexachlorodibenzo-p-dioxins
[HxCDDs]
Pentachlorodibenzofurans [PeCDFs]
1,4-Dioxane [1,4-Diethyleneoxide]
Benzo(b)fluoranthene
Bis(2-chloroisopropyl) ether [2,2
-Dichloroisopropyl ether]
Cyclohexanone
Pentachlorophenol [PCP]
Indeno(l,2,3-cd) pyrene
Acrolein [2-propenal]
Allyl alcohol
Dibenz[a,h]anthracene
Ethylidene dichloride
[1,1 -Dichloroethane]
Pyridine
Chlorobenzene
Diethyl phthalate [DEP]
Vinyl acetate
Chloroprene [2-Chloro-l,3-butadiene]
1 ,2,4-Trichlorobenzene
m-Xylene
Number of
Impoundments
with Chemical
Present in
Wastewater *
33*
33*
36*
31*
31*
31*
41*
41*
38*
30*
36*
34*
28*
27*
27*
27*
26*
26*
24*
22*
22*
22*
22*
22*
22*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
4*
3*
N/A
24*
N/A
N/A
362*
0.008*
76*
128*
N/A
N/A
32*
9,203*
N/A
0.9*
N/A
N/A
N/A
N/A
N/A
N/A
0.4*
Influent (kg/yr)
N/A
N/A
1,758*
0.3*
N/A
8,145*
N/A
N/A
109,950*
57*
48,605*
73,865*
N/A
39*
N/A
2,041,911*
19*
N/A
646*
0.02*
4*
N/A
N/A
2*
206*
Effluent
(kg/yr)
N/A
N/A
2,439*
N/A
N/A
659*
0.001*
0.000*
16,292*
2*
51,713*
6,622*
9*
3*
N/A
843,892*
2*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
206*
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-44
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
p-Xylene
Ethyl acetate
Ethyl ether [Diethyl ether]
Methyl methacrylate
Ethylene dibromide
[ 1 ,2-Dibromoethane]
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
Trichloroethylene [TCE]
1 , 1 ,2-Trichloroethane [Vinyl
trichloride]
2,6-Dinitrotoluene
Allyl chloride
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Triethylamine
Vinyl chloride [chloroethylene]
2,3,4,6-Tetrachlorophenol
n-Butyl alcohol [n-Butanol]
Hexachlorobenzene
2,4-Dinitrophenol
Dimethyl phthalate [DMP]
Acrylic acid [propenoic acid]
Acetonitrile [Methyl cyanide]
beta-Hexachlorocyclohexane
[beta-BHC]
Ethylene oxide
Furfural
Propylene oxide [1,2-Epoxypropane]
Cyclohexanol
Number of
Impoundments
with Chemical
Present in
Wastewater *
22*
19*
19*
19*
19*
18*
18*
18*
18*
18*
18*
18*
18*
18*
16*
16*
13*
13*
13*
13*
12*
11*
11*
9*
5*
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
0.4*
N/A
N/A
314*
N/A
N/A
4*
N/A
N/A
180*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
8*
N/A
6*
192*
N/A
77*
N/A
Influent (kg/yr)
206*
635,951*
3,045*
282,462*
N/A
N/A
N/A
0.05*
N/A
68,044*
N/A
N/A
0.2*
N/A
1,195,884*
N/A
N/A
N/A
2,612,547*
N/A
310*
87,103*
25,588*
28,031*
N/A
Effluent
(kg/yr)
206*
N/A
N/A
31,885*
N/A
N/A
N/A
N/A
1,336*
17,005*
70*
N/A
N/A
N/A
839*
N/A
N/A
N/A
7,832*
N/A
310*
197*
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-45
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
Isobutyl alcohol [Isobutanol]
1,1, 1 ,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
1 , 1 ,2-Trichloro-l ,2,2-trifluoroethane
[FreonllS]
1 ,2,3 -Trichloropropane
1,2,4,5-Tetrachlorobenzene
1 ,2-Dibromo-3 -chloropropane
1 ,2-Diphenylhydrazine
1,2-Epoxybutane [1,2-Butylene oxide]
1 , 3 ,5 -Trinitrobenzene
[sym-Trinitrobenzene]
1,3 -Butadiene
1 , 3 -Dinitrobenzene
[m-Dinitrobenzene]
1 , 3 -Phenylenediamine
[m-Phenylenediamine]
2,4,5-Trichlorophenoxyacetic acid
[2,4,5,-T]
2,4-Toluenediamine
[2,4-Diaminotoluene]
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
2-Ethoxyethanol acetate [2-EEA]
Number of
Impoundments
with Chemical
Present in
Wastewater *
5*
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent (kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-46
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
2-Methoxyethanol [methyl cellosolve]
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Nitropropane
3,3 -Dichlorobenzidine
3,3 -Dimethoxybenzidine
3,3 -Dimethylbenzidine
3 ,4-Dimethylphenol
3 -Methylcholanthrene
4,4 -Methylene bis(2-chloroaniline)
4-Chloroaniline
[p-aminochlorobenzene]
7, 12-Dimethylbenz[a]anthracene
Acetophenone
Acrylamide
Aldicarb
Aldrin
Ammonium vanadate
Amonium perchlorate
Aramite
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent (kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-47
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
Benzidine
Benzyl chloride
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Butyl benzyl phthalate
Chloral [Trichloroacetaldehyde]
Chloral hydrate
[Trichloroacetaldehyde hydrate]
Chlorobenzilate
Chloromethyl Methyl Ether
cis- 1 ,2-Dichloroethylene
cis- 1 ,3 -Dichloropropylene
Cyanogen bromide [Bromine cyanide]
Cyanogen chloride [Chlorine cyanide]
Diallate
Dichlorodifluoromethane [CFC-12]
Dieldrin
Diethylstilbestrol [DBS]
Dimethoate
Dinoseb
[2-sec-Butyl-4,6-dinitrophenol]
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent (kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-48
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
Diphenylamine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Ethyl methacrylate
Ethyl methanesulfonate
Furan
Glycidylaldehyde
Hexachloro- 1 ,3 -butadiene
[Hexachlorobutadiene]
Hexachlorocyclopentadiene
Hexachloroethane
Hexachlorophene
Hydrazine
Isophorone
Kepone
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent (kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-49
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
Maleic anhydride
Maleic hydrazide
Methacrylonitrile
Methomyl
Methyl parathion
Methylene bromide
[Dibromomethane]
Nickel Subsulfide
Nitrobenzene
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitro so -N-methy lethy lamine
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
o-Toluidine
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent (kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-50
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
p,p -ODD
p,p -DDE
p,p -DDT
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins
[PeCDDs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Perchlorate
Phorate
Phthalic anhydride
Pronamide
p-Toluidine
Safrole
Strychnine
Styrene oxide
Tetraethyldithiopyrophosphate
[Sulfotepp]
trans-l,2-Dichloroethylene
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent (kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-51
-------
March 26, 2001
Appendix B
Table B-19b. (continued)
Chemical
trans- 1 , 3 -Dichloropropylene
Trichlorofluoromethane
[Trichloromonofluoromethane]
[CFC-11]
Tris(2,3-dibromopropyl) phosphate
Warfarin
Number of
Impoundments
with Chemical
Present in
Wastewater *
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Wastewater
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
Influent (kg/yr)
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-52
-------
March 26, 2001
Appendix B
Table B-20a. Chemicals: Presence and Volume in Sludge
(for Impoundments with Chemicals/pH of Concern)
Chemical
Barium
Lead
Zinc
Chromium
Nickel
Selenium
Copper
Arsenic
Manganese
Cadmium
Mercury
Vanadium
Toluene
Cobalt
Acetone [2-Propanone]
Molybdenum
Xylenes, mixed isomers [Xyenes]
Carbon disulfide
Silver
Antimony
Beryllium
Chloroform [Trichloromethane]
Ethyl benzene
Phenol
Benzene
Number of
Impoundments
with Chemical
Present in
Sludge *
4,269
3,499
3,282
3,108
2,773
2,647
2,399
2,184
1,937
1,921
1,538
1,316
1,287
999
878*
848
809
787*
709
670
660
632*
617
592
581
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
15,229,003*
6,292,236*
64,793,166*
3,343,304*
2,443,425*
15,851*
21,112,774*
1,014,712*
88,742,093*
187,321*
10,394*
9,169*
2*
4,124*
7*
651*
5,686*
1*
13,527*
0
3,246,766*
2*
1,004*
160*
0
Influent
(kg/yr)
201,078*
10,960*
1,746,200*
51,779*
53,698*
0
35,953*
5,546*
542,791*
77*
2*
0
0
0
0
0
0
0
0
0
0
0
0
273*
0
Effluent
(kg/yr)
156,990*
13,106*
374,157*
21,342*
38,907*
0
31,103*
10,926*
346,030*
1,265*
25*
468*
0
0
0
0
51*
0
0
0
0
1*
9*
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-53
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
Polychlorinated biphenyls [Aroclors]
Methyl ethyl ketone
[2-Butanone][MEK]
Sulfide
Fluoride
Bis(2-ethylhexyl) phthalate [Dioctyl
phthalate]
p-Cresol [4-Methyl phenol]
Fluorene
Pyrene
Naphthalene
Trichloroethylene [TCE]
Chrysene
Cyanide
n-Dioctyl phthalate
1,2-Dichloroethane [Ethylene
dichloride]
2,4-Dimethylphenol
Fluoranthene
Benzo(a)pyrene
o-Xylene
Benzo[a]anthracene
Chromium VI [Hexavalent
Chromium]
Thallium
Di-n-butyl phthalate
n-Butyl alcohol [n-Butanol]
Aldrin
beta-Hexachlorocyclohexane
[beta-BHC]
Number of
Impoundments
with Chemical
Present in
Sludge l
533*
518
505
433
427*
377*
367*
349
303
292*
284
278
278*
273*
270*
259
257
253*
248
240*
238*
238*
234*
232*
232*
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
86,997*
0
2,423,021*
54,793,440*
0
0
0
3,029*
2,903*
0
1,788*
30,127*
0
0
0
1,768*
83*
0
98*
0
942*
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2*
0
0
4*
0
0
Effluent
(kg/yr)
5,354*
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-54
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
Butyl benzyl phthalate
Chlordane, alpha & gamma isomers
Dieldrin
Endrin
Heptachlor
Heptachlor epoxide, alpha, beta, and
gamma isomers
Lindane
[gamma-Hexachlorocyclohexane]
[gamma-BHC]
Methoxychlor
p,p -ODD
p,p -DDE
p,p -DDT
Anthracene
Tetrachlorodibenzofurans [TCDFs]
Methylene chloride
[Dichloromethane]
Acenaphthene
Dibenz[a,h]anthracene
Benzo(b)fluoranthene
2,3,7,8-TCDD
[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Cyanide, amenable
Indeno(l,2,3-cd) pyrene
Formaldehyde
Tetrachlorodibenzo-p-dioxins
[TCDDs]
Methanol [methyl alcohol]
o-Cresol [2 -Methyl phenol]
Number of
Impoundments
with Chemical
Present in
Sludge l
232*
232*
232*
232*
232*
232*
232*
232*
232*
232*
232*
223
182*
173
165
139
133
128
126*
119*
111
108*
104
99*
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0*
0*
0
0
155*
0
0
0
881*
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0*
0
0
0
0
0
0
0
5,234*
0
1*
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0*
0*
0
0
0
0
0
0
2,640*
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-55
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
Tetrachloroethylene
[Perchloroethylene]
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
Ethylene glycol
m-Cresol [3 -Methyl phenol]
Acetaldehyde [Ethanal]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
Chloromethane [Methyl chloride]
Styrene
Chlorobenzene
Ethylene thiourea
Thiram [Thiuram]
2,4,6-Trichlorophenol
2,4-Dichlorophenol
2-Chlorophenol [o-Chlorophenol]
Bromomethane [Methyl bromide]
Cresols
1 ,4-Dioxane [ 1 ,4-Diethyleneoxide]
Isophorone
1,1,1-Trichloroethane [Methyl
chloroform]
2,4-Dinitrophenol
Diethyl phthalate [DEP]
Dimethyl phthalate [DMP]
Ethylene dibromide
[ 1 ,2-Dibromoethane]
Ethylidene dichloride
[1,1 -Dichloroethane]
Number of
Impoundments
with Chemical
Present in
Sludge l
99*
98*
81*
80*
80*
77*
62*
60*
52*
46*
46*
45*
45*
45*
42*
41*
40*
38*
38*
38*
38*
38*
38*
38*
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
487*
0
0*
0
0
0
0
0
0
0
0
0
0
0
100*
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0*
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-56
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
Methyl tert-butyl ether [MTBE]
N,N-Dimethyl formamide [DMF]
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
Pyridine
Hexachlorodibenzofurans [HxCDFs]
1,2-Dichloropropane [Propylene
dichloride]
Bromoform [Tribromomethane]
1 , 1 -Dichloroethylene [ Vinylidene
chloride]
Hexachlorodibenzo-p-dioxins
[HxCDDs]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins
[PeCDDs]
Vinyl chloride [chloroethylene]
Bis(2-chloroisopropyl) ether [2,2
-Dichloroisopropyl ether]
Cumene [Isopropyl benzene]
n-Hexane
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Acrolein [2-propenal]
Hexachlorobenzene
1,2,4-Trichlorobenzene
2,3,4,6-Tetrachlorophenol
Pentachlorophenol [PCP]
Number of
Impoundments
with Chemical
Present in
Sludge l
38*
38*
38*
38*
38*
36*
36*
29*
27*
27*
27*
27*
22*
21*
20*
20*
14*
11*
11*
7*
7*
7*
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0*
0
1*
0*
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0*
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-57
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
Acrylonitrile
Acrylic acid [propenoic acid]
Allyl alcohol
Ethylene oxide
Formic Acid
1,1, 1 ,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
1 , 1 ,2-Trichloro-l ,2,2-trifluoroethane
[FreonllS]
1 , 1 ,2-Trichloroethane [Vinyl
trichloride]
1 ,2,3 -Trichloropropane
1,2,4,5-Tetrachlorobenzene
1 ,2-Dibromo-3 -chloropropane
1 ,2-Diphenylhydrazine
1,2-Epoxybutane [1,2-Butylene oxide]
1 , 3 ,5 -Trinitrobenzene
[sym-Trinitrobenzene]
1,3 -Butadiene
1 , 3 -Dinitrobenzene
[m-Dinitrobenzene]
1 , 3 -Phenylenediamine
[m-Phenylenediamine]
2,4,5-Trichlorophenol
Number of
Impoundments
with Chemical
Present in
Sludge l
4*
2*
2*
2*
2*
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
17*
8*
0*
8*
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-58
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
2,4,5-Trichlorophenoxyacetic acid
[2,4,5,-T]
2,4-D [2,4-Dichlorophenoxyacetic
acid]
2,4-Dinitrotoluene
2,4-Toluenediamine
[2,4-Diaminotoruene]
2,6-Dinitrotoluene
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
2-Ethoxyethanol acetate [2-EEA]
2-Methoxyethanol [methyl cellosolve]
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Nitropropane
3,3 -Dichlorobenzidine
3,3 -Dimethoxybenzidine
3,3 -Dimethylbenzidine
3 ,4-Dimethylphenol
3 -Methylcholanthrene
4,4 -Methylene bis(2-chloroaniline)
Number of
Impoundments
with Chemical
Present in
Sludge l
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-59
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
4-Chloroaniline
[p-aminochlorobenzene]
7, 12-Dimethylbenz[a]anthracene
Acetonitrile [Methyl cyanide]
Acetophenone
Acrylamide
Aldicarb
Allyl chloride
alpha-Hexachlorocyclohexane
[alpha-BHC]
Ammonium vanadate
Amonium perchlorate
Aniline
Aramite
Benzidine
Benzyl alcohol
Benzyl chloride
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Bromodichloromethane
[Dichlorobromomethane]
Number of
Impoundments
with Chemical
Present in
Sludge l
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-60
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
Chloral hydrate
[Trichloroacetaldehyde hydrate]
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloromethyl Methyl Ether
Chloroprene [2-Chloro-l,3-butadiene]
cis- 1 ,2-Dichloroethylene
cis- 1 ,3 -Dichloropropylene
Cyanogen bromide [Bromine cyanide]
Cyanogen chloride [Chlorine cyanide]
Cyclohexanol
Cyclohexanone
Diallate
Dichlorodifluoromethane [CFC-12]
Diethylstilbestrol [DBS]
Number of
Impoundments
with Chemical
Present in
Sludge l
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-61
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
Dimethoate
Dinoseb
[2-sec-Butyl-4,6-dinitrophenol]
Diphenylamine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Epichlorohydrin
[ 1 -Chloro-2,3 -epoxypropane]
Ethyl acetate
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Furan
Furfural
Glycidylaldehyde
Number of
Impoundments
with Chemical
Present in
Sludge l
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-62
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
Hexachloro- 1 ,3 -butadiene
[Hexachlorobutadiene]
Hexachlorocyclopentadiene
Hexachloroethane
Hexachlorophene
Hydrazine
Isobutyl alcohol [Isobutanol]
Kepone
Maleic anhydride
Maleic hydrazide
Methacrylonitrile
Methomyl
Methyl methacrylate
Methyl parathion
Methylene bromide
[Dibromomethane]
m-Xylene
Nickel Subsulfide
Nitrobenzene
Number of
Impoundments
with Chemical
Present in
Sludge l
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-63
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitro so -N-methy lethy lamine
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
o-Toluidine
Parathion
Pentachlorobenzene
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Perchlorate
Phorate
Phthalic anhydride
Pronamide
Propylene oxide [1,2-Epoxypropane]
Number of
Impoundments
with Chemical
Present in
Sludge l
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-64
-------
March 26, 2001
Appendix B
Table 20a. (continued)
Chemical
p-Toluidine
p-Xylene
Safrole
Silvex
[2,4,5-Trichlorophenoxypropionic
acid]
Strychnine
Styrene oxide
Tetraethyldithiopyrophosphate
[Sulfotepp]
Toxaphene [Chlorinated camphene]
trans-l,2-Dichloroethylene
trans- 1 , 3 -Dichloropropylene
Trichlorofluoromethane
[Trichloromonofluoromethane]
[CFC-11]
Triethylamine
Tris(2,3-dibromopropyl) phosphate
Vinyl acetate
Warfarin
Number of
Impoundments
with Chemical
Present in
Sludge l
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Not Present or
Not Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Influent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Effluent
(kg/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-65
-------
March 26, 2001
Appendix B
Table B-20b. Standard Errors for Chemicals: Presence and Volume in Sludge
(for Impoundments with Chemicals/pH of Concern)
Chemical
Barium
Lead
Zinc
Chromium
Nickel
Selenium
Copper
Arsenic
Manganese
Cadmium
Mercury
Vanadium
Toluene
Cobalt
Acetone [2-Propanone]
Molybdenum
Xylenes, mixed isomers [Xyenes]
Carbon disulfide
Silver
Antimony
Beryllium
Chloroform [Trichloromethane]
Ethyl benzene
Phenol
Benzene
Number of
Impoundments
with Chemical
Present in Sludge 1
1,203
1,035
644
801
634
1,036
521
494
467
473
438
425
480
373
486*
330
305
485*
234
267
282
468*
248
164
267
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
11,198,278*
7,557,758*
69,522,056*
3,930,014*
1,622,692*
19,857*
17,034,712*
943,882*
78,768,980*
186,252*
7,078*
7,611*
2*
4,124*
7*
616*
9,885*
0.5*
13,993*
N/A
3,258,540*
2*
1,742*
165*
N/A
Influent
(kg/yr)
204,414*
10,402*
1,563,828*
46,243*
52,842*
N/A
27,576*
5,612*
550,742*
77*
2*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
475*
N/A
Effluent
(kg/yr)
168,935*
9,563*
245,664*
23,369*
31,510*
N/A
20,442*
8,898*
408,023*
1,265*
25*
840*
N/A
N/A
N/A
N/A
89*
N/A
N/A
N/A
N/A
1*
16*
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-66
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Polychlorinated biphenyls
[Aroclors]
Methyl ethyl ketone
[2-Butanone][MEK]
Sulfide
Fluoride
Bis(2-ethylhexyl) phthalate
[Dioctyl phthalate]
p-Cresol [4-Methyl phenol]
Fluorene
Pyrene
Naphthalene
Trichloroethylene [TCE]
Chrysene
Cyanide
n-Dioctyl phthalate
1,2-Dichloroethane [Ethylene
dichloride]
2,4-Dimethylphenol
Fluoranthene
Benzo(a)pyrene
o-Xylene
Benzo [a] anthracene
Chromium VI [Hexavalent
Chromium]
Thallium
Di-n-butyl phthalate
n-Butyl alcohol [n-Butanol]
Aldrin
Number of
Impoundments
with Chemical
Present in Sludge 1
338*
255
213
131
242*
236*
234*
118
92
236*
88
121
236*
235*
235*
87
114
233*
86
121*
129*
135*
232*
232*
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
158,541*
N/A
2,704,783*
55,465,247*
N/A
N/A
N/A
3,099*
5,020*
N/A
1,788*
36,371*
N/A
N/A
N/A
3,181*
151*
N/A
178*
N/A
950*
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
4*
N/A
N/A
14*
N/A
Effluent
(kg/yr)
9,899*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-67
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
beta-Hexachlorocyclohexane
[beta-BHC]
Butyl benzyl phthalate
Chlordane, alpha & gamma
isomers
Dieldrin
Endrin
Heptachlor
Heptachlor epoxide, alpha, beta,
and gamma isomers
Lindane
[gamma-Hexachlorocyclohexane]
[gamma-BHC]
Methoxychlor
p,p -ODD
p,p -DDE
p,p -DDT
Anthracene
Tetrachlorodibenzofurans
[TCDFs]
Methylene chloride
[Dichloromethane]
Acenaphthene
Dibenz[a,h]anthracene
Benzo(b)fluoranthene
2,3,7,8-TCDD
[2,3,7,8-Tetrachlorodibenzo-p-di
oxin]
Cyanide, amenable
Indeno(l,2,3-cd) pyrene
Formaldehyde
Number of
Impoundments
with Chemical
Present in Sludge 1
232*
232*
232*
232*
232*
232*
232*
232*
232*
232*
232*
232*
79
93*
72
68
67
65
54
106*
63*
50
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.1*
0.08*
N/A
N/A
282*
N/A
N/A
N/A
1,560*
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.04*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
5,819*
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.05*
0.005*
N/A
N/A
N/A
N/A
N/A
N/A
3,849*
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-68
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Tetrachlorodibenzo-p-dioxins
[TCDDs]
Methanol [methyl alcohol]
o-Cresol [2 -Methyl phenol]
Tetrachloroethylene
[Perchloroethylene]
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
Ethylene glycol
m-Cresol [3 -Methyl phenol]
Acetaldehyde [Ethanal]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
Chloromethane [Methyl chloride]
Styrene
Chlorobenzene
Ethylene thiourea
Thiram [Thiuram]
2,4,6-Trichlorophenol
2,4-Dichlorophenol
2-Chlorophenol [o-Chlorophenol]
Bromomethane [Methyl bromide]
Cresols
1,4-Dioxane
[ 1 ,4-Diethyleneoxide]
Isophorone
1,1,1-Trichloroethane [Methyl
chloroform]
2,4-Dinitrophenol
Diethyl phthalate [DEP]
Number of
Impoundments
with Chemical
Present in Sludge 1
57*
49
58*
59*
56*
45*
54*
43*
54*
45*
44*
41*
46*
46*
39*
39*
39*
42*
31*
38*
38*
38*
38*
38*
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
2*
N/A
N/A
N/A
1,651*
N/A
0.8*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
340*
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.04*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-69
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Dimethyl phthalate [DMP]
Ethylene dibromide
[ 1 ,2-Dibromoethane]
Ethylidene dichloride
[1,1 -Dichloroethane]
Methyl tert-butyl ether [MTBE]
N,N-Dimethyl formamide [DMF]
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
Pyridine
Hexachlorodibenzofurans
[HxCDFs]
1,2-Dichloropropane [Propylene
dichloride]
Bromoform [Tribromomethane]
1 , 1 -Dichloroethylene [ Vinylidene
chloride]
Hexachlorodibenzo-p-dioxins
[HxCDDs]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Pentachlorodibenzofurans
[PeCDFs]
Pentachlorodibenzo-p-dioxins
[PeCDDs]
Vinyl chloride [chloroethylene]
Bis(2-chloroisopropyl) ether [2,2
-Dichloroisopropyl ether]
Cumene [Isopropyl benzene]
n-Hexane
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Acrolein [2-propenal]
Number of
Impoundments
with Chemical
Present in Sludge 1
38*
38*
38*
38*
38*
38*
38*
29*
36*
36*
29*
25*
25*
25*
25*
22*
22*
22*
22*
18*
16*
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.007*
N/A
1*
0.08*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.02*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment, as indicated by
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
reported value or check for
B-70
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Ethylene thiourea
Thiram [Thiuram]
2,4,6-Trichlorophenol
2,4-Dichlorophenol
2-Chlorophenol [o-Chlorophenol]
Bromomethane [Methyl bromide]
Cresols
1,4-Dioxane
[ 1 ,4-Diethyleneoxide]
Isophorone
1,1,1-Trichloroethane [Methyl
chloroform]
2,4-Dinitrophenol
Diethyl phthalate [DEP]
Hexachlorobenzene
1 ,2,4-Trichlorobenzene
2,3,4,6-Tetrachlorophenol
Pentachlorophenol [PCP]
Acrylonitrile
Acrylic acid [propenoic acid]
Allyl alcohol
Ethylene oxide
Formic Acid
1,1, 1 ,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
1 , 1 ,2-Trichloro-l ,2,2-trifluoroeth
ane [Freon 113]
Number of
Impoundments
with Chemical
Present in Sludge 1
46*
46*
39*
39*
39*
42*
31*
38*
38*
38*
38*
38*
16*
12*
12*
12*
9*
7*
7*
7*
7*
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
340*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
58*
26*
0.2*
28*
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-71
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
1 , 1 ,2-Trichloroethane [Vinyl
trichloride]
1 ,2,3 -Trichloropropane
1,2,4,5-Tetrachlorobenzene
1 ,2-Dibromo-3 -chloropropane
1 ,2-Diphenylhydrazine
1,2-Epoxybutane [1,2-Butylene
oxide]
1 , 3 ,5 -Trinitrobenzene
[sym-Trinitrobenzene]
1,3 -Butadiene
1 , 3 -Dinitrobenzene
[m-Dinitrobenzene]
1 , 3 -Phenylenediamine
[m-Phenylenediamine]
2,4,5-Trichlorophenol
2,4,5-Trichlorophenoxyacetic
acid [2,4,5,-T]
2,4-D
[2,4-Dichlorophenoxyacetic acid]
2,4-Dinitrotoluene
2,4-Toluenediamine
[2,4-Diaminotoluene]
2,6-Dinitrotoluene
2-Chloronaphthalene
[beta-Chloronaphthalene]
Number of
Impoundments
with Chemical
Present in Sludge 1
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-72
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
2-Ethoxyethanol acetate [2-EEA]
2-Methoxyethanol [methyl
cellosolve]
2-Methoxyethanol acetate
[2-MEA] [methyl cellosolve
acetate]
2-Nitropropane
3,3 -Dichlorobenzidine
3,3 -Dimethoxybenzidine
3,3 -Dimethylbenzidine
3 ,4-Dimethylphenol
3 -Methylcholanthrene
4,4 -Methylene
bis(2-chloroaniline)
4-Chloroaniline
[p-aminochlorobenzene]
7, 12-Dimethylbenz[a]anthracene
Acetonitrile [Methyl cyanide]
Acetophenone
Acrylamide
Aldicarb
Number of
Impoundments
with Chemical
Present in Sludge 1
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-73
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Allyl chloride
alpha-Hexachlorocyclohexane
[alpha-BHC]
Ammonium vanadate
Amonium perchlorate
Aniline
Aramite
Benzidine
Benzyl alcohol
Benzyl chloride
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Bromodichloromethane
[Dichlorobromomethane]
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
Chloral hydrate
[Trichloroacetaldehyde hydrate]
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloromethyl Methyl Ether
Number of
Impoundments
with Chemical
Present in Sludge 1
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-74
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Chloroprene
[2-Chloro-l,3-butadiene]
cis- 1 ,2-Dichloroethylene
cis- 1 ,3 -Dichloropropylene
Cyanogen bromide [Bromine
cyanide]
Cyanogen chloride [Chlorine
cyanide]
Cyclohexanol
Cyclohexanone
Diallate
Dichlorodifluoromethane
[CFC-12]
Diethylstilbestrol [DBS]
Dimethoate
Dinoseb
[2-sec-Butyl-4,6-dinitrophenol]
Diphenylamine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Number of
Impoundments
with Chemical
Present in Sludge 1
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-75
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Endosulfan
Endothall
Epichlorohydrin
[ 1 -Chloro-2,3 -epoxypropane]
Ethyl acetate
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Furan
Furfural
Glycidylaldehyde
Hexachloro- 1 ,3 -butadiene
[Hexachlorobutadiene]
Hexachlorocyclopentadiene
Hexachloroethane
Hexachlorophene
Hydrazine
Isobutyl alcohol [Isobutanol]
Kepone
Maleic anhydride
Number of
Impoundments
with Chemical
Present in Sludge 1
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-76
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Maleic hydrazide
Methacrylonitrile
Methomyl
Methyl methacrylate
Methyl parathion
Methylene bromide
[Dibromomethane]
m-Xylene
Nickel Subsulfide
Nitrobenzene
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitro so -N-methy lethy lamine
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
o-Toluidine
Number of
Impoundments
with Chemical
Present in Sludge 1
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment.
"present but quantity unknown."
2. Calculated from reported concentration or flux.
(continued)
as indicated by reported value or check for
B-77
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
Parathion
Pentachlorobenzene
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Perchlorate
Phorate
Phthalic anhydride
Pronamide
Propylene oxide
[ 1 ,2-Epoxypropane]
p-Toluidine
p-Xylene
Safrole
Silvex
[2,4,5-Trichlorophenoxypropioni
c acid]
Strychnine
Styrene oxide
Tetraethyldithiopyrophosphate
[Sulfotepp]
Toxaphene [Chlorinated
camphene]
trans-l,2-Dichloroethylene
Number of
Impoundments
with Chemical
Present in Sludge 1
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(continued)
I. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-78
-------
March 26, 2001
Appendix B
Table B-20b. (continued)
Chemical
trans- 1 , 3 -Dichloropropylene
Trichlorofluoromethane
[Trichloromonofluoromethane]
[CFC-11]
Triethylamine
Tris(2,3 -dibromopropyl)
phosphate
Vinyl acetate
Warfarin
Number of
Impoundments
with Chemical
Present in Sludge 1
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Not Present or Not
Reported
Reported Quantity of Chemical in Sludge
(All Impoundments) 2
Within
Impoundment
(kg)
N/A
N/A
N/A
N/A
N/A
N/A
Influent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
Effluent
(kg/yr)
N/A
N/A
N/A
N/A
N/A
N/A
1. Chemical presence in influent, effluent, or within impoundment, as indicated by reported value or check for
"present but quantity unknown."
2. Calculated from reported concentration or flux.
B-79
-------
March 26, 2001
Appendix B
Table B-21. Comparison of Survey Data and Risk Input Data: Chemical Categories for
Wastewater and Sludge at Influent, In Impoundment, and Effluent Sampling Points
Survey Database Chemical Data
Chemical
Categories
VOCs
SVOCs
Metals
Dioxin-like
compounds
Mercury
PBTs
Any chemicals
Percent missing
overall
Number
nonmissing zero
dischargers*
Wastewater (< 5 weight percent solids)
Influent
#
5,866
3,824
9,966
291
2,483
6,870
10,745
16
30
%
76
75
84
24
27
71
96
42
10
In
Impoundment
#
5,412
3,786
9,982
218
2,479
7,216
10,766
24
28
%
76
75
83
21
30
72
97
24
26
Effluent
#
4,815
3,508
7,762
346
2,235
4,989
8,187
16
30
%
72
69
85
22
31
67
92
34
17
Sludge (> 5 weight percent solids)
Influent
#
1,690
863
3,925
247
1,061
2,556
4,101
30
22
%
4
7
42
10
0.9
13
45
63
12
In
Impoundment
#
2,006
1,261
5,551
861
1,745
4,539
5,759
21
23
%
21
24
98
35
66
91
100
47
16
Effluent
#
1,311
605
3,078
412
826
2,269
3,230
19
30
%
14
3
88
41
6
72
89
36
23
Risk Input Database Chemical Data
Chemical
Categories
VOCs
SVOCs
Metals
Dioxin-like
compounds
Mercury
PBTs
Any chemicals
Percent missing
overall
Number
nonmissing zero
dischargers*
Wastewater (< 5 weight percent solids)
Influent
#
5,791
4,819
10,476
811
2,934
8,648
1 1 ,345
16
30
%
85
83
89
41
45
80
100
42
10
In
Impoundment
#
5,835
4,819
10,493
811
2,934
8,676
1 1 ,345
24
28
%
77
81
85
33
36
83
99
24
26
Effluent
#
NA
NA
NA
NA
NA
NA
NA
NA
NA
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
Sludge (> 5 weight percent solids)
Influent
#
NA
NA
NA
NA
NA
NA
NA
NA
NA
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
In
Impoundment
#
3,417
2,914
6,293
1,343
2,228
5,302
6,559
21
23
%
79
78
100
64
70
97
100
47
16
Effluent
#
NA
NA
NA
NA
NA
NA
NA
NA
NA
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
% = percent of total volume
NA = not applicable
*Total number of Zero Dischargers = 36
B-80
-------
March 26, 2001
Appendix B
Table B-22. Chemical Presence in Wastewater Influent by SIC Code (Survey Database)
Industry
Group
Chemical
Acenaphthene
Acetaldehyde [Ethanal]
Acetone [2-Propanone]
Acetonitrile [Methyl cyanide]
Acetophenone
Acrolein [2-propenal]
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldicarb
Aldrin
Allyl alcohol
Allyl chloride
Ammonium vanadate
Ammonium perchlorate
Aniline
Anthracene
Antimony
Aramite
Arsenic
Barium
Benzene
Benzidine
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo[a]anthracene
Benzyl alcohol
Benzyl chloride
Beryllium
beta-Hexachlorocyclohexane [beta-BHC]
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Bis(2-chloroisopropyl) ether
[2,2'-Dichloroisopropyl ether]
Bis(2-ethylhexyl) phthalate
[Dioctyl phthalate]
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Bromodichloromethane
[Dichlorobromomethane]
Bromoform [Tribromomethane]
Bromomethane [Methyl bromide]
1 ,3-Butadiene
n-Butyl alcohol [n-Butanol]
Butyl benzyl phthalate
Cadmium
Carbon disulfide
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
"8
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1*:
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•
•
•
Lumber and wood
products
•
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
•
•
•
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•
•
•
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Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-81
-------
March 26, 2001
Appendix B
Table B-22. (continued)
Industry
Group
Chemical
Chloral hydrate [Trichloroacetaldehyde
hydrate]
Chlordane, alpha & gamma isomers
4-Chloroaniline [p-aminochlorobenzene]
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Chloromethyl methyl ether
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Chlorophenol [o-Chlorophenol]
Chloroprene [2-Chloro-1 ,3-butadiene]
Chromium
Chromium VI [Hexavalent Chromium]
Chrysene
Cobalt
Copper
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols
Cumene [Isopropyl benzene]
Cyanide
Cyanide, amenable
Cyanogen bromide [Bromine cyanide]
Cyanogen chloride [Chlorine cyanide]
Cyclohexanol
Cyclohexanone
2,4-D [2,4-Dichlorophenoxyacetic acid]
p,p'-DDD
p,p'-DDE
p,p'-DDT
Di-n-butyl phthalate
Diallate
Dibenz[a,h]anthracene
1 ,2-Dibromo-3-chloropropane
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
3,3'-Dichlorobenzidine
Dichlorodifluoromethane [CFC-12]
1 ,2-Dichloroethane [Ethylene dichloride]
1 1-Dichloroethylene [Vinylidene
chloride]
"8
?
1*:
^B
ro o
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LL Q.
Textile mill products
•
•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
•
•
CO
in
(0
D)
T3
c
ro
>^
ro
3
CT3
00
W Q.
•
Primary metal industries
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
•
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-82
-------
March 26, 2001
Appendix B
Table B-22. (continued)
Industry
Group
Chemical
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
2,4-Dichlorophenol
1 ,2-Dichloropropane [Propylene
dichloride]
cis-1 ,3-Dichloropropylene
trans-1 ,3-Dichloropropylene
Dieldrin
Diethyl phthalate [DEP]
Diethylstilbestrol [DES]
Dimethoate
3,3'-Dimethoxybenzidine
N,N-Dimethyl formamide [DMF]
Dimethyl phthalate [DMP]
7,12-Dimethylbenz[a]anthracene
3,3'-Dimethylbenzidine
2,4-Dimethylphenol
3,4-Dimethylphenol
1 ,3-Dinitrobenzene [m-Dinitrobenzene]
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Dinoseb [2-sec-Butyl-4,6-dinitrophenol]
n-Dioctyl phthalate
1 ,4-Dioxane [1 ,4-Diethyleneoxide]
Diphenylamine
1 ,2-Diphenylhydrazine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Endrin
Epichlorohydrin
[1-Chloro-2,3-epoxypropane]
1 ,2-Epoxybutane [1 ,2-Butylene oxide]
2-Ethoxyethanol acetate [2-EEA]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
Ethyl acetate
Ethyl benzene
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Ethylene dibromide [1,2-Dibromoethane]
Ethylene glycol
Ethylene oxide
"8
?
1*:
^B
ro o
J!
LL Q.
Textile mill products
•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
ro
3
CT3
00
W Q.
Primary metal industries
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-83
-------
March 26, 2001
Appendix B
Table B-22. (continued)
Industry
Group
Chemical
Ethylene thiourea
Ethylidene dichloride
[1,1 -Dichloroethane]
Fluoranthene
Fluorene
Fluoride
Formaldehyde
Formic Acid
Furan
Furfural
Glycidylaldehyde
Heptachlor
Heptachlor epoxide, alpha, beta, and
gamma isomers
Hexachloro-1 ,3-butadiene
[Hexachlorobutadiene]
Hexachlorobenzene
alpha-Hexachlorocyclohexane
[alpha-BHC]
Hexachlorocyclopentadiene
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachlorodibenzofurans [HxCDFs]
Hexachloroethane
Hexachlorophene
n-Hexane
Hydrazine
lndeno(1,2,3-cd) pyrene
Isobutyl alcohol [Isobutanol]
Isophorone
Kepone
Lead
Lindane [gamma-
Hexachlorocyclohexane] [gamma-BHC]
Maleic anhydride
Maleic hydrazide
Manganese
Mercury
Met hacrylonit rile
Methanol [methyl alcohol]
Methomyl
Methoxychlor
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Methoxyethanol [methyl cellosolve]
Methyl ethyl ketone [2-Butanone][MEK]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Methyl methacrylate
Methyl parathion
"8
?
1*:
^B
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LL Q.
•
Textile mill products
•
•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
ro
>^
ro
3
CT3
00
W Q.
•
Primary metal industries
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-84
-------
March 26, 2001
Appendix B
Table B-22. (continued)
Industry
Group
Chemical
Methyl tert-butyl ether [MTBE]
3-Methylcholanthrene
4,4'-Methylene bis(2-chloroaniline)
Methylene bromide [Dibromomethane]
Methylene chloride [Dichloromethane]
Molybdenum
Naphthalene
Nickel
Nickel Subsulfide
Nitrobenzene
2-Nitropropane
N-Nitroso-N-methylethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachlorodibenzofurans [PeCDFs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Pentachlorophenol [PCP]
Perchlorate
Phenol
1 ,3-Phenylenediamine
[m-Phenylenediamine]
Phorate
Phthalic anhydride
Polychlorinated biphenyls [Aroclors]
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Silvex[2,4,5-Trichlorophenoxypropionic
acid]
Strychnine
Styrene
Styrene oxide
Sulfide
"8
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•
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•
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Lumber and wood
products
•
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•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
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miscellaneous plastic
products
•
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in
(0
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•
•
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Primary metal industries
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-85
-------
March 26, 2001
Appendix B
Table B-22. (continued)
Industry
Group
Chemical
2,3,7,8-TCDD [2,3,7,8-
Tetrachlorodibenzo-p-dioxin]
1 ,2,4,5-Tetrachlorobenzene
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlorodibenzofurans [TCDFs]
1,1,1 ,2-Tetrachloroethane
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene [Perchloroethylene]
2,3,4,6-Tetrachlorophenol
Tetraethyldithiopyrophosphate
[Sulfotepp]
Thallium
Thiram [Thiuram]
Toluene
2-4-Toluenediamine
[2,4-Diaminotoluene]
o-Toluidine
p-Toluidine
Toxaphene [Chlorinated camphene]
1,1 ,2-Trichloro-1 ,2,2-trifluoroethane
[Freon 113]
1 ,2,4-Trichlorobenzene
1 1,1-Trichloroethane [Methyl
chloroform]
1 ,1 ,2-Trichloroethane [Vinyl trichloride]
Trichloroethylene [TCE]
Trichlorofluoromethane
[Trichloromonofluoromethane] [CFC-1 1 ]
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
2.4,5-Trichlorophenoxyacetic acid
[2,4,5,-T]
1 ,2,3-Trichloropropane
Triethylamine
1 ,3,5-Trinitrobenzene
[sym-Trinitrobenzene]
Tris(2,3-dibromopropyl) phosphate
Vanadium
Vinyl acetate
Vinyl chloride [chloroethylene]
Warfarin
m-Xylene
o-Xylene
p-Xylene
Xylenes, mixed isomers [Xylenes]
Zinc
"8
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•
•
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products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
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miscellaneous plastic
products
•
•
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in
(0
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>^
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3
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•
•
•
Primary metal industries
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
•
National security and
international affairs
B-86
-------
March 26, 2001
Appendix B
Table B-23. Chemical Presence in Wastewater in Impoundment by SIC Code
(Survey Database)
Industry
Group
Chemical
Acenaphthene
Acetaldehyde [Ethanal]
Acetone [2-Propanone]
Acetonitrile [Methyl cyanide]
Acetophenone
Acrolein [2-propenal]
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldicarb
Aldrin
Allyl alcohol
Allyl chloride
Ammonium vanadate
Ammonium perchlorate
Aniline
Anthracene
Antimony
Aramite
Arsenic
Barium
Benzene
Benzidine
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo[a]anthracene
Benzyl alcohol
Benzyl chloride
Beryllium
beta-Hexachlorocyclohexane [beta-
BHC]
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Bis(2-chloroisopropyl) ether
[2,2'-Dichloroisopropyl ether]
Bis(2-ethylhexyl) phthalate [Dioctyl
phthalate]
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Bromodichloromethane
[Dichlorobromomethane]
Bromoform [Tribromomethane]
Bromomethane [Methyl bromide]
1 ,3-Butadiene
n-Butyl alcohol [n-Butanol]
Butyl benzyl phthalate
Cadmium
Carbon disulfide
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products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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products
•
•
•
•
•
•
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•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment |
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-87
-------
March 26, 2001
Appendix B
Table B-23. (continued)
Industry
Group
Chemical
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
Chloral hydrate [Trichloroacetaldehyde
hydrate]
Chlordane, alpha & gamma isomers
4-Chloroaniline [p-aminochlorobenzene]
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Chloromethyl methyl ether
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Chlorophenol [o-Chlorophenol]
Chloroprene [2-Chloro-1 ,3-butadiene]
Chromium
Chromium VI [Hexavalent Chromium]
Chrysene
Cobalt
Copper
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols
Cumene [Isopropyl benzene]
Cyanide
Cyanide, amenable
Cyanogen bromide [Bromine cyanide]
Cyanogen chloride [Chlorine cyanide]
Cyclohexanol
Cyclohexanone
2,4-D [2,4-Dichlorophenoxyacetic acid]
p,p'-DDD
p,p'-DDE
p,p'-DDT
Di-n-butyl phthalate
Diallate
Dibenz[a,h]anthracene
1 ,2-Dibromo-3-chloropropane
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
3,3'-Dichlorobenzidine
Dichlorodifluoromethane [CFC-12]
1 ,2-Dichloroethane [Ethylene dichloride]
"8
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•
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products
Paper and allied products
•
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•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
•
•
CO
in
(0
D)
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c
ro
>^
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3
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W Q.
•
Primary metal industries
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
Transportation equipment |
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-88
-------
March 26, 2001
Appendix B
Table B-23. (continued)
Industry
Group
Chemical
1 1-Dichloroethylene [Vinylidene
chloride]
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
2,4-Dichlorophenol
1 ,2-Dichloropropane [Propylene
dichloride]
cis-1 ,3-Dichloropropylene
trans-1 ,3-Dichloropropylene
Dieldrin
Diethyl phthalate [DEP]
Diethylstilbestrol [DES]
Dimethoate
3,3'-Dimethoxybenzidine
N,N-Dimethyl formamide [DMF]
Dimethyl phthalate [DMP]
7,12-Dimethylbenz[a]anthracene
3,3'-Dimethylbenzidine
2,4-Dimethylphenol
3,4-Dimethylphenol
1 ,3-Dinitrobenzene [m-Dinitrobenzene]
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Dinoseb [2-sec-Butyl-4,6-dinitrophenol]
n-Dioctyl phthalate
1 ,4-Dioxane [1 ,4-Diethyleneoxide]
Diphenylamine
1 ,2-Diphenylhydrazine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Endrin
Epichlorohydrin
[1-Chloro-2,3-epoxypropane]
1 ,2-Epoxybutane [1 ,2-Butylene oxide]
2-Ethoxyethanol acetate [2-EEA]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
Ethyl acetate
Ethyl benzene
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Ethylene dibromide [1,2-
Dibromoethane]
"8
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1*:
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•
•
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products
Paper and allied products
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
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3
CT3
00
W Q.
Primary metal industries
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment
Transportation equipment |
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-89
-------
March 26, 2001
Appendix B
Table B-23. (continued)
Industry
Group
Chemical
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Ethylidene dichloride
[1,1-Dichloroethane]
Fluoranthene
Fluorene
Fluoride
Formaldehyde
Formic Acid
Furan
Furfural
Glycidylaldehyde
Heptachlor
Heptachlor epoxide, alpha, beta, and
gamma isomers
Hexachloro-1 ,3-butadiene
[Hexachlorobutadiene]
Hexachlorobenzene
alpha-Hexachlorocyclohexane
[alpha-BHC]
Hexachlorocyclopentadiene
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachlorodibenzofurans [HxCDFs]
Hexachloroethane
Hexachlorophene
n-Hexane
Hydrazine
lndeno(1,2,3-cd) pyrene
Isobutyl alcohol [Isobutanol]
Isophorone
Kepone
Lead
Lindane [gamma-
Hexachlorocyclohexane] [gamma-BHC]
Maleic anhydride
Maleic hydrazide
Manganese
Mercury
Met hacrylonit rile
Methanol [methyl alcohol]
Methomyl
Methoxychlor
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Methoxyethanol [methyl cellosolve]
Methyl ethyl ketone [2-Butanone][MEK]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
"8
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•
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•
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products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
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in
(0
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c
ro
>^
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3
CT3
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W Q.
•
•
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•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment |
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-90
-------
March 26, 2001
Appendix B
Table B-23. (continued)
Industry
Group
Chemical
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
3-Methylcholanthrene
4,4'-Methylene bis(2-chloroaniline)
Methylene bromide [Dibromomethane]
Methylene chloride [Dichloromethane]
Molybdenum
Naphthalene
Nickel
Nickel Subsulfide
Nitrobenzene
2-Nitropropane
N-Nitroso-N-methylethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins
[PeCDDs]
Pentachlorodibenzofurans [PeCDFs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Pentachlorophenol [PCP]
Perchlorate
Phenol
1 ,3-Phenylenediamine
[m-Phenylenediamine]
Phorate
Phthalic anhydride
Polychlorinated biphenyls [Aroclors]
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Silvex [2,4,5-Trichlorophenoxypropionic
acid]
"8
•g
1*:
^B
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J!
LL Q.
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•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
ro
>^
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3
CT3
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W Q.
•
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment |
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-91
-------
March 26, 2001
Appendix B
Table B-23. (continued)
Industry
Group
Chemical
Strychnine
Styrene
Styrene oxide
Sulfide
2378-TCDD
[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
1 ,2,4,5-Tetrachlorobenzene
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlorodibenzofurans [TCDFs]
1,1,1 ,2-Tetrachloroethane
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene [Perchloroethylene]
2,3,4,6-Tetrachlorophenol
Tetraethyldithiopyrophosphate
[Sulfotepp]
Thallium
Thiram [Thiuram]
Toluene
2-4-Toluenediamine
[2,4-Diaminotoluene]
o-Toluidine
p-Toluidine
Toxaphene [Chlorinated camphene]
1,1 ,2-Trichloro-1 ,2,2-trifluoroethane
[Freon 113]
1 ,2,4-Trichlorobenzene
1 1,1-Trichloroethane [Methyl
chloroform]
1 ,1 ,2-Trichloroethane [Vinyl trichloride]
Trichloroethylene [TCE]
Trichlorofluoromethane
[Trichloromonofluoromethane] [CFC-1 1 ]
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
2.4,5-Trichlorophenoxyacetic acid
[2,4,5,-T]
1 ,2,3-Trichloropropane
Triethylamine
1 ,3,5-Trinitrobenzene
[sym-Trinitrobenzene]
Tris(2,3-dibromopropyl) phosphate
Vanadium
Vinyl acetate
Vinyl chloride [chloroethylene]
Warfarin
m-Xylene
o-Xylene
p-Xylene
Xylenes, mixed isomers [Xylenes]
Zinc
"8
•g
1*:
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•
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•
•
•
•
•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
ro
>^
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3
CT3
00
W Q.
•
Primary metal industries
•
•
•
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment |
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
•
National security and
international affairs
B-92
-------
March 26, 2001
Appendix B
Table B-24. Chemical Presence in Wastewater Effluent by SIC Code (Survey Database)
Industry
Group
Chemical
Acenaphthene
Acetaldehyde [Ethanal]
Acetone [2-Propanone]
Acetonitrile [Methyl cyanide]
Acetophenone
Acrolein [2-propenal]
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldicarb
Aldrin
Allyl alcohol
Allyl chloride
Ammonium vanadate
Ammonium perchlorate
Aniline
Anthracene
Antimony
Aramite
Arsenic
Barium
Benzene
Benzidine
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo[a]anthracene
Benzyl alcohol
Benzyl chloride
Beryllium
beta-Hexachlorocyclohexane [beta-BHC]
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Bis(2-chloroisopropyl) ether
[2,2'-Dichloroisopropyl ether]
Bis(2-ethylhexyl) phthalate [Dioctyl
phthalate]
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Bromodichloromethane
[Dichlorobromomethane]
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T3
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•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-93
-------
March 26, 2001
Appendix B
Table B-24. (continued)
Industry
Group
Chemical
Bromoform [Tribromomethane]
Bromomethane [Methyl bromide]
1 ,3-Butadiene
n-Butyl alcohol [n-Butanol]
Butyl benzyl phthalate
Cadmium
Carbon disulfide
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
Chloral hydrate [Trichloroacetaldehyde
hydrate]
Chlordane, alpha & gamma isomers
4-Chloroaniline [p-aminochlorobenzene]
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Chloromethyl methyl ether
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Chlorophenol [o-Chlorophenol]
Chloroprene [2-Chloro-1 ,3-butadiene]
Chromium
Chromium VI [Hexavalent Chromium]
Chrysene
Cobalt
Copper
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols
Cumene [Isopropyl benzene]
Cyanide
Cyanide, amenable
Cyanogen bromide [Bromine cyanide]
Cyanogen chloride [Chlorine cyanide]
"8
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products
Paper and allied products
•
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•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
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•
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•
•
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Rubber and
miscellaneous plastic
products
•
•
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•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-94
-------
March 26, 2001
Appendix B
Table B-24. (continued)
Industry
Group
Chemical
Cyclohexanol
Cyclohexanone
2,4-D [2,4-Dichlorophenoxyacetic acid]
p,p'-DDD
p,p'-DDE
p,p'-DDT
Di-n-butyl phthalate
Diallate
Dibenz[a,h]anthracene
1 ,2-Dibromo-3-chloropropane
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
3,3'-Dichlorobenzidine
Dichlorodifluoromethane [CFC-12]
1 ,2-Dichloroethane [Ethylene dichloride]
1 1-Dichloroethylene [Vinylidene
chloride]
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
2,4-Dichlorophenol
1 ,2-Dichloropropane [Propylene
dichloride]
cis-1 ,3-Dichloropropylene
trans-1 ,3-Dichloropropylene
Dieldrin
Diethyl phthalate [DEP]
Diethylstilbestrol [DES]
Dimethoate
3,3'-Dimethoxybenzidine
N,N-Dimethyl formamide [DMF]
Dimethyl phthalate [DMP]
7,12-Dimethylbenz[a]anthracene
3,3'-Dimethylbenzidine
2,4-Dimethylphenol
3,4-Dimethylphenol
1 ,3-Dinitrobenzene [m-Dinitrobenzene]
2,4-Dinitrophenol
"8
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products
•
•
•
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miscellaneous plastic
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•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
National security and
international affairs
(continued)
B-95
-------
March 26, 2001
Appendix B
Table B-24. (continued)
Industry
Group
Chemical
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Dinoseb [2-sec-Butyl-4,6-dinitrophenol]
n-Dioctyl phthalate
1 ,4-Dioxane [1 ,4-Diethyleneoxide]
Diphenylamine
1 ,2-Diphenylhydrazine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Endrin
Epichlorohydrin
[1-Chloro-2,3-epoxypropane]
1 ,2-Epoxybutane [1 ,2-Butylene oxide]
2-Ethoxyethanol acetate [2-EEA]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
Ethyl acetate
Ethyl benzene
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Ethylene dibromide [1,2-Dibromoethane]
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Ethylidene dichloride
[1,1-Dichloroethane]
Fluoranthene
Fluorene
Fluoride
Formaldehyde
Formic Acid
Furan
Furfural
Glycidylaldehyde
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•
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•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
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miscellaneous plastic
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(0
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•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-96
-------
March 26, 2001
Appendix B
Table B-24. (continued)
Industry
Group
Chemical
Heptachlor
Heptachlor epoxide, alpha, beta, and
gamma isomers
Hexachloro-1 ,3-butadiene
[Hexachlorobutadiene]
Hexachlorobenzene
alpha-Hexachlorocyclohexane
[alpha-BHC]
Hexachlorocyclopentadiene
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachlorodibenzofurans [HxCDFs]
Hexachloroethane
Hexachlorophene
n-Hexane
Hydrazine
lndeno(1,2,3-cd) pyrene
Isobutyl alcohol [Isobutanol]
Isophorone
Kepone
Lead
Lindane [gamma-
Hexachlorocyclohexane] [gamma-BHC]
Maleic anhydride
Maleic hydrazide
Manganese
Mercury
Met hacrylonit rile
Methanol [methyl alcohol]
Methomyl
Methoxychlor
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Methoxyethanol [methyl cellosolve]
Methyl ethyl ketone [2-Butanone][MEK]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
3-Methylcholanthrene
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•
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•
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•
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•
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Chemicals and allied
products
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
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SS.
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Primary metal industries
•
•
•
•
Fabricated metal products
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-97
-------
March 26, 2001
Appendix B
Table B-24. (continued)
Industry
Group
Chemical
4,4'-Methylene bis(2-chloroaniline)
Methylene bromide [Dibromomethane]
Methylene chloride [Dichloromethane]
Molybdenum
Naphthalene
Nickel
Nickel Subsulfide
Nitrobenzene
2-Nitropropane
N-Nitroso-N-methylethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachlorodibenzofurans [PeCDFs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Pentachlorophenol [PCP]
Perchlorate
Phenol
1 ,3-Phenylenediamine
[m-Phenylenediamine]
Phorate
Phthalic anhydride
Polychlorinated biphenyls [Aroclors]
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
"8
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•
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•
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•
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products
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
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CT3
SS.
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•
Primary metal industries
•
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-98
-------
March 26, 2001
Appendix B
Table B-24. (continued)
Industry
Group
Chemical
Selenium
Silver
Silvex[2,4,5-Trichlorophenoxypropionic
acid]
Strychnine
Styrene
Styrene oxide
Sulfide
2,3,7,8-TCDD
[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
1 ,2,4,5-Tetrachlorobenzene
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlorodibenzofurans [TCDFs]
1,1,1 ,2-Tetrachloroethane
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene [Perchloroethylene]
2,3,4,6-Tetrachlorophenol
Tetraethyldithiopyrophosphate
[Sulfotepp]
Thallium
Thiram [Thiuram]
Toluene
2-4-Toluenediamine
[2,4-Diaminotoluene]
o-Toluidine
p-Toluidine
Toxaphene [Chlorinated camphene]
1,1 ,2-Trichloro-1 ,2,2-trifluoroethane
[Freon113]
1 ,2,4-Trichlorobenzene
1 1,1-Trichloroethane [Methyl
chloroform]
1 ,1 ,2-Trichloroethane [Vinyl trichloride]
Trichloroethylene [TCE]
Trichlorofluoromethane
[Trichloromonofluoromethane] [CFC-1 1 ]
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
2,4. 5-Trichlorophenoxyacetic acid
[2,4,5,-T]
1 ,2,3-Trichloropropane
"8
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•
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products
•
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•
•
Petroleum and coal
products
•
•
•
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•
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•
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miscellaneous plastic
products
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CT3
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•
•
Primary metal industries
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-99
-------
March 26, 2001
Appendix B
Table B-24. (continued)
Industry
Group
Chemical
Triethylamine
1 ,3,5-Trinitrobenzene
[sym-Trinitrobenzene]
Tris(2,3-dibromopropyl) phosphate
Vanadium
Vinyl acetate
Vinyl chloride [chloroethylene]
Warfarin
m-Xylene
o-Xylene
p-Xylene
Xylenes, mixed isomers [Xylenes]
Zinc
"8
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•
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products
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•
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Chemicals and allied
products
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
Rubber and
miscellaneous plastic
products
•
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in
(0
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CT3
SS.
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•
•
Primary metal industries
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
•
National security and
international affairs
B-100
-------
March 26, 2001
Appendix B
Table B-25. Chemical Presence in Sludge by SIC Code (Survey Database)
Industry
Group
Chemical
Acenaphthene
Acetaldehyde [Ethanal]
Acetone [2-Propanone]
Acetonitrile [Methyl cyanide]
Acetophenone
Acrolein [2-propenal]
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldicarb
Aldrin
Allyl alcohol
Allyl chloride
Ammonium vanadate
Ammonium perchlorate
Aniline
Anthracene
Antimony
Aramite
Arsenic
Barium
Benzene
Benzidine
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo[a]anthracene
Benzyl alcohol
Benzyl chloride
Beryllium
beta-Hexachlorocyclohexane [beta-BHC]
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Bis(2-chloroisopropyl) ether
[2,2'-Dichloroisopropyl ether]
Bis(2-ethylhexyl) phthalate [Dioctyl
phthalate]
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Bromodichloromethane
[Dichlorobromomethane]
"8
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•
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
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miscellaneous plastic
products
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in
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.22
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•
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
•
•
Wholesale trade
nondurable goods
National security and
international affairs
•
•
(continued)
B-101
-------
March 26, 2001
Appendix B
Table B-25. (continued)
Industry
Group
Chemical
Bromoform [Tribromomethane]
Bromomethane [Methyl bromide]
1 ,3-Butadiene
n-Butyl alcohol [n-Butanol]
Butyl benzyl phthalate
Cadmium
Carbon disulfide
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
Chloral hydrate [Trichloroacetaldehyde
hydrate]
Chlordane, alpha & gamma isomers
4-Chloroaniline [p-aminochlorobenzene]
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Chloromethyl methyl ether
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Chlorophenol [o-Chlorophenol]
Chloroprene [2-Chloro-1 ,3-butadiene]
Chromium
Chromium VI [Hexavalent Chromium]
Chrysene
Cobalt
Copper
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols
Cumene [Isopropyl benzene]
Cyanide
Cyanide, amenable
Cyanogen bromide [Bromine cyanide]
"8
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•
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•
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•
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•
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•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
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>^
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»3
CT3
-2S
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
•
•
•
•
(continued)
B-102
-------
March 26, 2001
Appendix B
Table B-25. (continued)
Industry
Group
Chemical
Cyanogen chloride [Chlorine cyanide]
Cyclohexanol
Cyclohexanone
2,4-D [2,4-Dichlorophenoxyacetic acid]
p,p'-DDD
p,p'-DDE
p,p'-DDT
Di-n-butyl phthalate
Diallate
Dibenz[a,h]anthracene
1 ,2-Dibromo-3-chloropropane
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
3,3'-Dichlorobenzidine
Dichlorodifluoromethane [CFC-12]
1 ,2-Dichloroethane [Ethylene dichloride]
1 1-Dichloroethylene [Vinylidene
chloride]
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
2,4-Dichlorophenol
1 ,2-Dichloropropane [Propylene
dichloride]
cis-1 ,3-Dichloropropylene
trans-1 ,3-Dichloropropylene
Dieldrin
Diethyl phthalate [DEP]
Diethylstilbestrol [DES]
Dimethoate
3,3'-Dimethoxybenzidine
N,N-Dimethyl formamide [DMF]
Dimethyl phthalate [DMP]
7,12-Dimethylbenz[a]anthracene
3,3'-Dimethylbenzidine
2,4-Dimethylphenol
3,4-Dimethylphenol
1 ,3-Dinitrobenzene [m-Dinitrobenzene]
"8
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Paper and allied products
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Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
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CT3
.22
W Q.
Primary metal industries
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
National security and
international affairs
(continued)
B-103
-------
March 26, 2001
Appendix B
Table B-25. (continued)
Industry
Group
Chemical
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Dinoseb [2-sec-Butyl-4,6-dinitrophenol]
n-Dioctyl phthalate
1 ,4-Dioxane [1 ,4-Diethyleneoxide]
Diphenylamine
1 ,2-Diphenylhydrazine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Endrin
Epichlorohydrin
[1-Chloro-2,3-epoxypropane]
1 ,2-Epoxybutane [1 ,2-Butylene oxide]
2-Ethoxyethanol acetate [2-EEA]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
Ethyl acetate
Ethyl benzene
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Ethylene dibromide [1,2-Dibromoethane]
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Ethylidene dichloride
[1,1 -Dichloroethane]
Fluoranthene
Fluorene
Fluoride
Formaldehyde
Formic Acid
Furan
"8
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Paper and allied products
•
•
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Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
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CT3
.22
W Q.
Primary metal industries
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
Wholesale trade
nondurable goods
National security and
international affairs
(continued)
B-104
-------
March 26, 2001
Appendix B
Table B-25. (continued)
Industry
Group
Chemical
Furfural
Glycidylaldehyde
Heptachlor
Heptachlor epoxide, alpha, beta, and
gamma isomers
Hexachloro-1 ,3-butadiene
[Hexachlorobutadiene]
Hexachlorobenzene
alpha-Hexachlorocyclohexane
[alpha-BHC]
Hexachlorocyclopentadiene
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachlorodibenzofurans [HxCDFs]
Hexachloroethane
Hexachlorophene
n-Hexane
Hydrazine
lndeno(1,2,3-cd) pyrene
Isobutyl alcohol [Isobutanol]
Isophorone
Kepone
Lead
Lindane [gamma-
Hexachlorocyclohexane] [gamma-BHC]
Maleic anhydride
Maleic hydrazide
Manganese
Mercury
Met hacrylonit rile
Methanol [methyl alcohol]
Methomyl
Methoxychlor
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Methoxyethanol [methyl cellosolve]
Methyl ethyl ketone [2-Butanone][MEK]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Methyl methacrylate
Methyl parathion
"8
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Paper and allied products
•
•
•
•
•
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•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
•
Primary metal industries
•
•
•
•
•
Fabricated metal products
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
National security and
international affairs
•
(continued)
B-105
-------
March 26, 2001
Appendix B
Table B-25. (continued)
Industry
Group
Chemical
Methyl tert-butyl ether [MTBE]
3-Methylcholanthrene
4,4'-Methylene bis(2-chloroaniline)
Methylene bromide [Dibromomethane]
Methylene chloride [Dichloromethane]
Molybdenum
Naphthalene
Nickel
Nickel Subsulfide
Nitrobenzene
2-Nitropropane
N-Nitroso-N-methylethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachlorodibenzofurans [PeCDFs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Pentachlorophenol [PCP]
Perchlorate
Phenol
1 ,3-Phenylenediamine
[m-Phenylenediamine]
Phorate
Phthalic anhydride
Polychlorinated biphenyls [Aroclors]
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
"8
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•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
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ro
>^
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»3
CT3
SS.
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•
Primary metal industries
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
National security and
international affairs
•
•
•
(continued)
B-106
-------
March 26, 2001
Appendix B
Table B-25. (continued)
Industry
Group
Chemical
Pyridine
Safrole
Selenium
Silver
Silvex [2,4,5-Trichlorophenoxypropionic
acid]
Strychnine
Styrene
Styrene oxide
Sulfide
2378-TCDD
[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
1 ,2,4,5-Tetrachlorobenzene
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlorodibenzofurans [TCDFs]
1,1,1 ,2-Tetrachloroethane
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene [Perchloroethylene]
2,3,4,6-Tetrachlorophenol
Tetraethyldithiopyrophosphate
[Sulfotepp]
Thallium
Thiram [Thiuram]
Toluene
2-4-Toluenediamine
[2,4-Diaminotoluene]
o-Toluidine
p-Toluidine
Toxaphene [Chlorinated camphene]
1,1 ,2-Trichloro-1 ,2,2-trifluoroethane
[Freon 113]
1 ,2,4-Trichlorobenzene
1 1,1-Trichloroethane [Methyl
chloroform]
1 ,1 ,2-Trichloroethane [Vinyl trichloride]
Trichloroethylene [TCE]
Trichlorofluoromethane
[Trichloromonofluoromethane] [CFC-1 1 ]
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
"8
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•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
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>^
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CT3
SS.
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•
•
•
Primary metal industries
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
National security and
international affairs
•
(continued)
B-107
-------
March 26, 2001
Appendix B
Table B-25. (continued)
Industry
Group
Chemical
2.4,5-Trichlorophenoxyacetic acid
[2,4,5,-T]
1 ,2,3-Trichloropropane
Triethylamine
1 ,3,5-Trinitrobenzene
[sym-Trinitrobenzene]
Tris(2,3-dibromopropyl) phosphate
Vanadium
Vinyl acetate
Vinyl chloride [chloroethylene]
Warfarin
m-Xylene
o-Xylene
p-Xylene
Xylenes, mixed isomers [Xylenes]
Zinc
"8
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Textile mill products
•
Lumber and wood
products
Paper and allied products
•
•
Chemicals and allied
products
•
•
•
•
•
Petroleum and coal
products
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
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oj2
»3
CT3
52
W Q.
•
•
Primary metal industries
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment |
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
National security and
international affairs
•
•
B-108
-------
March 26, 2001
Appendix B
Table B-26.Chemical Presence in Wastewater Influent by SIC Code (Risk Input Database)
Industry
Group
Chemical
Acenaphthene
Acetaldehyde [Ethanal]
Acetone [2-Propanone]
Acetonitrile [Methyl cyanide]
Acetophenone
Acrolein [2-propenal]
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldicarb
Aldrin
Allyl alcohol
Allyl chloride
Ammonium vanadate
Ammonium perchlorate
Aniline
Anthracene
Antimony
Aramite
Arsenic
Barium
Benzene
Benzidine
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo[a]anthracene
Benzyl alcohol
Benzyl chloride
Beryllium
beta-Hexachlorocyclohexane [beta-BHC]
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Bis(2-chloroisopropyl) ether
[2,2'-Dichloroisopropyl ether]
Bis(2-ethylhexyl) phthalate
[Dioctyl phthalate]
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
Bromodichloromethane
[Dichlorobromomethane]
"8
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•
•
•
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products
•
•
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
•
•
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
•
•
•
Transportation equipment
•
•
Electric, gas, and sanitary
services
•
•
•
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-109
-------
March 26, 2001
Appendix B
Table B-26. (continued)
Industry
Group
Chemical
Bromoform [Tribromomethane]
Bromomethane [Methyl bromide]
1 ,3-Butadiene
n-Butyl alcohol [n-Butanol]
Butyl benzyl phthalate
Cadmium
Carbon disulfide
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
Chloral hydrate [Trichloroacetaldehyde
hydrate]
Chlordane, alpha & gamma isomers
4-Chloroaniline [p-aminochlorobenzene]
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Chloromethyl methyl ether
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Chlorophenol [o-Chlorophenol]
Chloroprene [2-Chloro-1 ,3-butadiene]
Chromium
Chromium VI [Hexavalent Chromium]
Chrysene
Cobalt
Copper
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols
Cumene [Isopropyl benzene]
Cyanide
Cyanide, amenable
Cyanogen bromide [Bromine cyanide]
"8
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•
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•
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products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
•
•
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
•
Transportation equipment
•
•
•
Electric, gas, and sanitary
services
•
•
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-110
-------
March 26, 2001
Appendix B
Table B-26. (continued)
Industry
Group
Chemical
Cyanogen chloride [Chlorine cyanide]
Cyclohexanol
Cyclohexanone
2,4-D [2,4-Dichlorophenoxyacetic acid]
p,p'-DDD
p,p'-DDE
p,p'-DDT
Di-n-butyl phthalate
Diallate
Dibenz[a,h]anthracene
1 ,2-Dibromo-3-chloropropane
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
3,3'-Dichlorobenzidine
Dichlorodifluoromethane [CFC-12]
1 ,2-Dichloroethane [Ethylene dichloride]
1 1-Dichloroethylene [Vinylidene
chloride]
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
2,4-Dichlorophenol
1 ,2-Dichloropropane [Propylene
dichloride]
cis-1 ,3-Dichloropropylene
trans-1 ,3-Dichloropropylene
Dieldrin
Diethyl phthalate [DEP]
Diethylstilbestrol [DES]
Dimethoate
3,3'-Dimethoxybenzidine
N,N-Dimethyl formamide [DMF]
Dimethyl phthalate [DMP]
7,12-Dimethylbenz[a]anthracene
3,3'-Dimethylbenzidine
2,4-Dimethylphenol
3,4-Dimethylphenol
1 ,3-Dinitrobenzene [m-Dinitrobenzene]
"8
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Paper and allied products
•
•
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•
•
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
National security and
international affairs
(continued)
B-lll
-------
March 26, 2001
Appendix B
Table B-26. (continued)
Industry
Group
Chemical
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Dinoseb [2-sec-Butyl-4,6-dinitrophenol]
n-Dioctyl phthalate
1 ,4-Dioxane [1 ,4-Diethyleneoxide]
Diphenylamine
1 ,2-Diphenylhydrazine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Endrin
Epichlorohydrin
[1-Chloro-2,3-epoxypropane]
1 ,2-Epoxybutane [1 ,2-Butylene oxide]
2-Ethoxyethanol acetate [2-EEA]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
Ethyl acetate
Ethyl benzene
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Ethylene dibromide [1,2-Dibromoethane]
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Ethylidene dichloride
[1,1 -Dichloroethane]
Fluoranthene
Fluorene
Fluoride
Formaldehyde
Formic Acid
Furan
"8
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Lumber and wood
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Paper and allied products
•
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•
•
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•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-112
-------
March 26, 2001
Appendix B
Table B-26. (continued)
Industry
Group
Chemical
Furfural
Glycidylaldehyde
Heptachlor
Heptachlor epoxide, alpha, beta, and
gamma isomers
Hexachloro-1 ,3-butadiene
[Hexachlorobutadiene]
Hexachlorobenzene
alpha-Hexachlorocyclohexane
[alpha-BHC]
Hexachlorocyclopentadiene
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachlorodibenzofurans [HxCDFs]
Hexachloroethane
Hexachlorophene
n-Hexane
Hydrazine
lndeno(1,2,3-cd) pyrene
Isobutyl alcohol [Isobutanol]
Isophorone
Kepone
Lead
Lindane [gamma-
Hexachlorocyclohexane] [gamma-BHC]
Maleic anhydride
Maleic hydrazide
Manganese
Mercury
Met hacrylonit rile
Methanol [methyl alcohol]
Methomyl
Methoxychlor
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Methoxyethanol [methyl cellosolve]
Methyl ethyl ketone [2-Butanone][MEK]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Methyl methacrylate
Methyl parathion
"8
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•
•
•
•
•
•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
Transportation equipment
•
•
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-113
-------
March 26, 2001
Appendix B
Table B-26. (continued)
Industry
Group
Chemical
Methyl tert-butyl ether [MTBE]
3-Methylcholanthrene
4,4'-Methylene bis(2-chloroaniline)
Methylene bromide [Dibromomethane]
Methylene chloride [Dichloromethane]
Molybdenum
Naphthalene
Nickel
Nickel Subsulfide
Nitrobenzene
2-Nitropropane
N-Nitroso-N-methylethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachlorodibenzofurans [PeCDFs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Pentachlorophenol [PCP]
Perchlorate
Phenol
1 ,3-Phenylenediamine
[m-Phenylenediamine]
Phorate
Phthalic anhydride
Polychlorinated biphenyls [Aroclors]
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
"8
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•
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Lumber and wood
products
•
Paper and allied products
•
•
•
•
•
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•
•
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•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
•
•
National security and
international affairs
(continued)
B-114
-------
March 26, 2001
Appendix B
Table B-26. (continued)
Industry
Group
Chemical
Pyridine
Safrole
Selenium
Silver
Silvex [2,4,5-Trichlorophenoxypropionic
acid]
Strychnine
Styrene
Styrene oxide
Sulfide
2,3,7,8-TCDD [2,3,7,8-
Tetrachlorodibenzo-p-dioxin]
1 ,2,4,5-Tetrachlorobenzene
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlorodibenzofurans [TCDFs]
1,1,1 ,2-Tetrachloroethane
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene [Perchloroethylene]
2,3,4,6-Tetrachlorophenol
Tetraethyldithiopyrophosphate
[Sulfotepp]
Thallium
Thiram [Thiuram]
Toluene
2-4-Toluenediamine
[2,4-Diaminotoluene]
o-Toluidine
p-Toluidine
Toxaphene [Chlorinated camphene]
1,1 ,2-Trichloro-1 ,2,2-trifluoroethane
[Freon 113]
1 ,2,4-Trichlorobenzene
1 1,1-Trichloroethane [Methyl
chloroform]
1 ,1 ,2-Trichloroethane [Vinyl trichloride]
Trichloroethylene [TCE]
Trichlorofluoromethane
[Trichloromonofluoromethane] [CFC-1 1 ]
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
"8
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Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
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>^
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»3
CT3
-2S
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•
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-115
-------
March 26, 2001
Appendix B
Table B-26. (continued)
Industry
Group
Chemical
2.4,5-Trichlorophenoxyacetic acid
[2,4,5,-T]
1 ,2,3-Trichloropropane
Triethylamine
1 ,3,5-Trinitrobenzene
[sym-Trinitrobenzene]
Tris(2,3-dibromopropyl) phosphate
Vanadium
Vinyl acetate
Vinyl chloride [chloroethylene]
Warfarin
m-Xylene
o-Xylene
p-Xylene
Xylenes, mixed isomers [Xylenes]
Zinc
"8
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•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
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>^
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»3
CT3
SS.
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•
•
Primary metal industries
•
•
•
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
B-116
-------
March 26, 2001
Appendix B
Table B-27. Chemical Presence in Wastewater in Impoundment by SIC Code
(Risk Input Database)
Industry
Group
Chemical
Acenaphthene
Acetaldehyde [Ethanal]
Acetone [2-Propanone]
Acetonitrile [Methyl cyanide]
Acetophenone
Acrolein [2-propenal]
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldicarb
Aldrin
Allyl alcohol
Allyl chloride
Ammonium vanadate
Ammonium perchlorate
Aniline
Anthracene
Antimony
Aramite
Arsenic
Barium
Benzene
Benzidine
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo[a]anthracene
Benzyl alcohol
Benzyl chloride
Beryllium
beta-Hexachlorocyclohexane [beta-
BHC]
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Bis(2-chloroisopropyl) ether
[2,2'-Dichloroisopropyl ether]
Bis(2-ethylhexyl) phthalate
[Dioctyl phthalate]
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
T3
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°°
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•
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Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
•
•
•
Transportation equipment
•
•
Electric, gas, and sanitary
services
•
•
•
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-117
-------
March 26, 2001
Appendix B
Table B-27. (continued)
Industry
Group
Chemical
Bromodichloromethane
[Dichlorobromomethane]
Bromoform [Tribromomethane]
Bromomethane [Methyl bromide]
1 ,3-Butadiene
n-Butyl alcohol [n-Butanol]
Butyl benzyl phthalate
Cadmium
Carbon disulfide
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
Chloral hydrate [Trichloroacetaldehyde
hydrate]
Chlordane, alpha & gamma isomers
4-Chloroaniline [p-aminochlorobenzene]
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Chloromethyl methyl ether
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Chlorophenol [o-Chlorophenol]
Chloroprene [2-Chloro-1 ,3-butadiene]
Chromium
Chromium VI [Hexavalent Chromium]
Chrysene
Cobalt
Copper
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols
Cumene [Isopropyl benzene]
Cyanide
Cyanide, amenable
"8
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•
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•
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•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
•
•
•
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
•
Transportation equipment
•
•
•
Electric, gas, and sanitary
services
•
•
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-118
-------
March 26, 2001
Appendix B
Table B-27. (continued)
Industry
Group
Chemical
Cyanogen bromide [Bromine cyanide]
Cyanogen chloride [Chlorine cyanide]
Cyclohexanol
Cyclohexanone
2,4-D [2,4-Dichlorophenoxyacetic acid]
p,p'-DDD
p,p'-DDE
p,p'-DDT
Di-n-butyl phthalate
Diallate
Dibenz[a,h]anthracene
1 ,2-Dibromo-3-chloropropane
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
3,3'-Dichlorobenzidine
Dichlorodifluoromethane [CFC-12]
1 ,2-Dichloroethane [Ethylene dichloride]
1 1-Dichloroethylene [Vinylidene
chloride]
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
2,4-Dichlorophenol
1 ,2-Dichloropropane [Propylene
dichloride]
cis-1 ,3-Dichloropropylene
trans-1 ,3-Dichloropropylene
Dieldrin
Diethyl phthalate [DEP]
Diethylstilbestrol [DES]
Dimethoate
3,3'-Dimethoxybenzidine
N,N-Dimethyl formamide [DMF]
Dimethyl phthalate [DMP]
7,12-Dimethylbenz[a]anthracene
3,3'-Dimethylbenzidine
2,4-Dimethylphenol
3,4-Dimethylphenol
"8
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products
Paper and allied products
•
•
•
•
•
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
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oj2
»3
CT3
-2S
V) Q.
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
National security and
international affairs
(continued)
B-119
-------
March 26, 2001
Appendix B
Table B-27. (continued)
Industry
Group
Chemical
1 ,3-Dinitrobenzene [m-Dinitrobenzene]
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Dinoseb [2-sec-Butyl-4,6-dinitrophenol]
n-Dioctyl phthalate
1 ,4-Dioxane [1 ,4-Diethyleneoxide]
Diphenylamine
1 ,2-Diphenylhydrazine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Endrin
Epichlorohydrin
[1-Chloro-2,3-epoxypropane]
1 ,2-Epoxybutane [1 ,2-Butylene oxide]
2-Ethoxyethanol acetate [2-EEA]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
Ethyl acetate
Ethyl benzene
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Ethylene dibromide [1,2-
Dibromoethane]
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Ethylidene dichloride
[1,1 -Dichloroethane]
Fluoranthene
Fluorene
Fluoride
Formaldehyde
Formic Acid
"8
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Chemicals and allied
products
•
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•
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•
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
ro
>^
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»3
CT3
SS.
V) Q.
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
(continued)
B-120
-------
March 26, 2001
Appendix B
Table B-27. (continued)
Industry
Group
Chemical
Furan
Furfural
Glycidylaldehyde
Heptachlor
Heptachlor epoxide, alpha, beta, and
gamma isomers
Hexachloro-1 ,3-butadiene
[Hexachlorobutadiene]
Hexachlorobenzene
alpha-Hexachlorocyclohexane
[alpha-BHC]
Hexachlorocyclopentadiene
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachlorodibenzofurans [HxCDFs]
Hexachloroethane
Hexachlorophene
n-Hexane
Hydrazine
lndeno(1,2,3-cd) pyrene
Isobutyl alcohol [Isobutanol]
Isophorone
Kepone
Lead
Lindane [gamma-
Hexachlorocyclohexane] [gamma-BHC]
Maleic anhydride
Maleic hydrazide
Manganese
Mercury
Met hacrylonit rile
Methanol [methyl alcohol]
Methomyl
Methoxychlor
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Methoxyethanol [methyl cellosolve]
Methyl ethyl ketone [2-Butanone][MEK]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Methyl methacrylate
"8
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•
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•
•
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products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
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»3
CT3
-2S
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
Transportation equipment
•
•
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-121
-------
March 26, 2001
Appendix B
Table B-27. (continued)
Industry
Group
Chemical
Methyl parathion
Methyl tert-butyl ether [MTBE]
3-Methylcholanthrene
4,4'-Methylene bis(2-chloroaniline)
Methylene bromide [Dibromomethane]
Methylene chloride [Dichloromethane]
Molybdenum
Naphthalene
Nickel
Nickel Subsulfide
Nitrobenzene
2-Nitropropane
N-Nitroso-N-methylethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins
[PeCDDs]
Pentachlorodibenzofurans [PeCDFs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Pentachlorophenol [PCP]
Perchlorate
Phenol
1 ,3-Phenylenediamine
[m-Phenylenediamine]
Phorate
Phthalic anhydride
Polychlorinated biphenyls [Aroclors]
Pronamide
"8
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products
•
Paper and allied products
•
•
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•
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•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
ro
>^
ro
oj2
»3
CT3
-2S
V) Q.
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
•
•
National security and
international affairs
(continued)
B-122
-------
March 26, 2001
Appendix B
Table B-27. (continued)
Industry
Group
Chemical
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Silvex[2,4,5-Trichlorophenoxypropionic
acid]
Strychnine
Styrene
Styrene oxide
Sulfide
2,3,7,8-TCDD [2,3,7,8-
Tetrachlorodibenzo-p-dioxin]
1 ,2,4,5-Tetrachlorobenzene
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlorodibenzofurans [TCDFs]
1,1,1 ,2-Tetrachloroethane
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene [Perchloroethylene]
2,3,4,6-Tetrachlorophenol
Tetraethyldithiopyrophosphate
[Sulfotepp]
Thallium
Thiram [Thiuram]
Toluene
2-4-Toluenediamine
[2,4-Diaminotoluene]
o-Toluidine
p-Toluidine
Toxaphene [Chlorinated camphene]
1,1 ,2-Trichloro-1 ,2,2-trifluoroethane
[Freon113]
1 ,2,4-Trichlorobenzene
1 1,1-Trichloroethane [Methyl
chloroform]
1 ,1 ,2-Trichloroethane [Vinyl trichloride]
Trichloroethylene [TCE]
Trichlorofluoromethane
[Trichloromonofluoromethane] [CFC-1 1 ]
"8
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Lumber and wood
products
Paper and allied products
•
•
•
•
•
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
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»3
CT3
-2S
V) Q.
•
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
(continued)
B-123
-------
March 26, 2001
Appendix B
Table B-27. (continued)
Industry
Group
Chemical
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
2,4. 5-Trichlorophenoxyacetic acid
[2,4,5,-T]
1 ,2,3-Trichloropropane
Triethylamine
1 ,3,5-Trinitrobenzene
[sym-Trinitrobenzene]
Tris(2,3-dibromopropyl) phosphate
Vanadium
Vinyl acetate
Vinyl chloride [chloroethylene]
Warfarin
m-Xylene
o-Xylene
p-Xylene
Xylenes, mixed isomers [Xylenes]
Zinc
"8
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Textile mill products
•
•
•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
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c
ro
>^
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»3
CT3
-2S
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
•
•
National security and
international affairs
B-124
-------
March 26, 2001
Appendix B
Table B-28. Chemical Presence in Sludge by SIC Code (Risk Input Database)
Industry
Group
Chemical
Acenaphthene
Acetaldehyde [Ethanal]
Acetone [2-Propanone]
Acetonitrile [Methyl cyanide]
Acetophenone
Acrolein [2-propenal]
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldicarb
Aldrin
Allyl alcohol
Allyl chloride
Ammonium vanadate
Ammonium perchlorate
Aniline
Anthracene
Antimony
Aramite
Arsenic
Barium
Benzene
Benzidine
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo[a]anthracene
Benzyl alcohol
Benzyl chloride
Beryllium
beta-Hexachlorocyclohexane [beta-BHC]
Bis(2-chloroethyl) ether
[sym-Dichloroethyl ether]
Bis(2-chloroisopropyl) ether
[2,2'-Dichloroisopropyl ether]
Bis(2-ethylhexyl) phthalate
[Dioctyl phthalate]
Bis(chloromethyl) ether
[sym-Dichloromethyl ether]
"8
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Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
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>^
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»3
CT3
-2S
V) Q.
•
•
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
•
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
•
•
•
Wholesale trade
nondurable goods
National security and
international affairs
•
•
(continued)
B-125
-------
March 26, 2001
Appendix B
Table B-28. (continued)
Industry
Group
Chemical
Bromodichloromethane
[Dichlorobromomethane]
Bromoform [Tribromomethane]
Bromomethane [Methyl bromide]
1 ,3-Butadiene
n-Butyl alcohol [n-Butanol]
Butyl benzyl phthalate
Cadmium
Carbon disulfide
Carbon tetrachloride
Chloral [Trichloroacetaldehyde]
Chloral hydrate [Trichloroacetaldehyde
hydrate]
Chlordane, alpha & gamma isomers
4-Chloroaniline [p-aminochlorobenzene]
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
[Dibromochloromethane]
Chloroethane [Ethyl chloride]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Chloromethyl methyl ether
2-Chloronaphthalene
[beta-Chloronaphthalene]
2-Chlorophenol [o-Chlorophenol]
Chloroprene [2-Chloro-1 ,3-butadiene]
Chromium
Chromium VI [Hexavalent Chromium]
Chrysene
Cobalt
Copper
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols
Cumene [Isopropyl benzene]
Cyanide
Cyanide, amenable
"8
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•
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Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
•
•
•
•
CO
in
(0
D)
T3
c
ro
>^
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»3
CT3
-2S
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
•
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
•
•
•
•
(continued)
B-126
-------
March 26, 2001
Appendix B
Table B-28. (continued)
Industry
Group
Chemical
Cyanogen bromide [Bromine cyanide]
Cyanogen chloride [Chlorine cyanide]
Cyclohexanol
Cyclohexanone
2,4-D [2,4-Dichlorophenoxyacetic acid]
p,p'-DDD
p,p'-DDE
p,p'-DDT
Di-n-butyl phthalate
Diallate
Dibenz[a,h]anthracene
1 ,2-Dibromo-3-chloropropane
1 ,2-Dichlorobenzene
[o-Dichlorobenzene]
1 ,4-Dichlorobenzene
[p-Dichlorobenzene]
3,3'-Dichlorobenzidine
Dichlorodifluoromethane [CFC-12]
1 ,2-Dichloroethane [Ethylene dichloride]
1 1-Dichloroethylene [Vinylidene
chloride]
cis-1 ,2-Dichloroethylene
trans-1 ,2-Dichloroethylene
2,4-Dichlorophenol
1 ,2-Dichloropropane [Propylene
dichloride]
cis-1 ,3-Dichloropropylene
trans-1 ,3-Dichloropropylene
Dieldrin
Diethyl phthalate [DEP]
Diethylstilbestrol [DES]
Dimethoate
3,3'-Dimethoxybenzidine
N,N-Dimethyl formamide [DMF]
Dimethyl phthalate [DMP]
7,12-Dimethylbenz[a]anthracene
3,3'-Dimethylbenzidine
2,4-Dimethylphenol
3,4-Dimethylphenol
"8
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Lumber and wood
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
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c
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>^
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»3
CT3
.22
W Q.
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment
Electric, gas, and sanitary
services
Wholesale trade
nondurable goods
National security and
international affairs
(continued)
B-127
-------
March 26, 2001
Appendix B
Table B-28. (continued)
Industry
Group
Chemical
1 ,3-Dinitrobenzene [m-Dinitrobenzene]
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Dinoseb [2-sec-Butyl-4,6-dinitrophenol]
n-Dioctyl phthalate
1 ,4-Dioxane [1 ,4-Diethyleneoxide]
Diphenylamine
1 ,2-Diphenylhydrazine
Direct Black 38
Direct Blue 6
Direct Brown 95
Disulfoton
Endosulfan
Endothall
Endrin
Epichlorohydrin
[1-Chloro-2,3-epoxypropane]
1 ,2-Epoxybutane [1 ,2-Butylene oxide]
2-Ethoxyethanol acetate [2-EEA]
2-Ethoxyethanol [Ethylene glycol
monoethyl ether]
Ethyl acetate
Ethyl benzene
Ethyl ether [Diethyl ether]
Ethyl methacrylate
Ethyl methanesulfonate
Ethylene dibromide [1,2-Dibromoethane]
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Ethylidene dichloride
[1,1 -Dichloroethane]
Fluoranthene
Fluorene
Fluoride
Formaldehyde
Formic Acid
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•
•
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•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
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c
ro
>^
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»3
CT3
SS.
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Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
Wholesale trade
nondurable goods
National security and
international affairs
(continued)
B-128
-------
March 26, 2001
Appendix B
Table B-28. (continued)
Industry
Group
Chemical
Furan
Furfural
Glycidylaldehyde
Heptachlor
Heptachlor epoxide, alpha, beta, and
gamma isomers
Hexachloro-1 ,3-butadiene
[Hexachlorobutadiene]
Hexachlorobenzene
alpha-Hexachlorocyclohexane
[alpha-BHC]
Hexachlorocyclopentadiene
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachlorodibenzofurans [HxCDFs]
Hexachloroethane
Hexachlorophene
n-Hexane
Hydrazine
lndeno(1,2,3-cd) pyrene
Isobutyl alcohol [Isobutanol]
Isophorone
Kepone
Lead
Lindane [gamma-
Hexachlorocyclohexane] [gamma-BHC]
Maleic anhydride
Maleic hydrazide
Manganese
Mercury
Met hacrylonit rile
Methanol [methyl alcohol]
Methomyl
Methoxychlor
2-Methoxyethanol acetate [2-MEA]
[methyl cellosolve acetate]
2-Methoxyethanol [methyl cellosolve]
Methyl ethyl ketone [2-Butanone][MEK]
Methyl isobutyl ketone [Hexone]
[4-Methyl-2-pentanone] [MIBK]
Methyl methacrylate
"8
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•
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
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»3
CT3
-2S
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
•
(continued)
B-129
-------
March 26, 2001
Appendix B
Table B-28. (continued)
Industry
Group
Chemical
Methyl parathion
Methyl tert-butyl ether [MTBE]
3-Methylcholanthrene
4,4'-Methylene bis(2-chloroaniline)
Methylene bromide [Dibromomethane]
Methylene chloride [Dichloromethane]
Molybdenum
Naphthalene
Nickel
Nickel Subsulfide
Nitrobenzene
2-Nitropropane
N-Nitroso-N-methylethylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine
[Di-n-propylnitrosamine]
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodiphenylamine
[Diphenylnitrosamine]
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethylpyrophosphoramide
Parathion
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachlorodibenzofurans [PeCDFs]
Pentachloronitrobenzene [PCNB]
[Quintobenzene] [Quintozene]
Pentachlorophenol [PCP]
Perchlorate
Phenol
1 ,3-Phenylenediamine
[m-Phenylenediamine]
Phorate
Phthalic anhydride
Polychlorinated biphenyls [Aroclors]
Pronamide
Propylene oxide [1,2-Epoxypropane]
"8
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products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
•
CO
in
(0
D)
T3
c
ro
>^
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»3
CT3
-2S
V) Q.
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
•
•
•
(continued)
B-130
-------
March 26, 2001
Appendix B
Table B-28. (continued)
Industry
Group
Chemical
Pyrene
Pyridine
Safrole
Selenium
Silver
Silvex [2,4,5-Trichlorophenoxypropionic
acid]
Strychnine
Styrene
Styrene oxide
Sulfide
2,3,7,8-TCDD [2,3,7,8-
Tetrachlorodibenzo-p-dioxin]
1 ,2,4,5-Tetrachlorobenzene
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlorodibenzofurans [TCDFs]
1,1,1 ,2-Tetrachloroethane
1 ,1 ,2,2-Tetrachloroethane
Tetrachloroethylene [Perchloroethylene]
2,3,4,6-Tetrachlorophenol
Tetraethyldithiopyrophosphate
[Sulfotepp]
Thallium
Thiram [Thiuram]
Toluene
2-4-Toluenediamine
[2,4-Diaminotoluene]
o-Toluidine
p-Toluidine
Toxaphene [Chlorinated camphene]
1,1 ,2-Trichloro-1 ,2,2-trifluoroethane
[Freon113]
1 ,2,4-Trichlorobenzene
1 1,1-Trichloroethane [Methyl
chloroform]
1 ,1 ,2-Trichloroethane [Vinyl trichloride]
Trichloroethylene [TCE]
Trichlorofluoromethane
[Trichloromonofluoromethane] [CFC-1 1 ]
2,4,5-Trichlorophenol
"8
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•
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
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oj2
»3
CT3
-2S
V) Q.
•
•
•
Primary metal industries
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Fabricated metal products
•
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
•
•
Transportation equipment
Electric, gas, and sanitary
services
•
•
•
•
•
•
Wholesale trade
nondurable goods
•
National security and
international affairs
•
(continued)
B-131
-------
March 26, 2001
Appendix B
Table B-28. (continued)
Industry
Group
Chemical
2,4,6-Trichlorophenol
2.4,5-Trichlorophenoxyacetic acid
[2,4,5,-T]
1 ,2,3-Trichloropropane
Triethylamine
1 ,3,5-Trinitrobenzene
[sym-Trinitrobenzene]
Tris(2,3-dibromopropyl) phosphate
Vanadium
Vinyl acetate
Vinyl chloride [chloroethylene]
Warfarin
m-Xylene
o-Xylene
p-Xylene
Xylenes, mixed isomers [Xylenes]
Zinc
"8
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•
•
•
Textile mill products
•
Lumber and wood
products
Paper and allied products
•
•
•
•
•
•
•
•
•
Chemicals and allied
products
•
•
•
•
•
•
•
•
•
•
•
•
Petroleum and coal
products
•
•
•
•
•
•
Rubber and
miscellaneous plastic
products
•
CO
in
(0
D)
T3
c
ro
>^
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oj2
»3
CT3
SS.
V) Q.
•
•
Primary metal industries
•
•
•
•
•
•
•
•
Fabricated metal products
•
Industrial machinery and
equipment
Electronic and other
electric equipment
•
Transportation equipment
•
Electric, gas, and sanitary
services
•
•
Wholesale trade
nondurable goods
National security and
international affairs
•
•
B-132
-------
March 26, 2001 Appendix B
Table B-29. Chemicals Co-occurring in Wastewater by Human Health Effect, Number of
Co-occurring Chemicals, and Facility at which they Co-occur.
Cancer
Facilities having 16 chemicals with cancer effects
Facility 068
Arsenic
Benzene
Benzo(a)pyrene
Benzo (b)ffuoranthene
Benzo [a] anthracene
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Chloroform [Trichloromethane]
Chrysene
Dibenz [a,h] anthracene
1,4-Dichlorobenzene [p-Dichlorobenzene]
1,2-Dichloroethane [Ethylene dichloride]
1,4-Dioxane [1,4-Diethyleneoxide]
Ethylene dibromide [1,2-Dibromoethane]
Indeno(l,2,3-cd) pyrene
Tetrachloroethylene [Perchloroethylene]
Trichloroethylene [TCE]
Facilities having 12 chemicals with cancer effects
Facility 103
Acetaldehyde [Ethanal]
Arsenic
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Formaldehyde
Methylene chloride [Dichloromethane]
Pentachlorophenol [PCP]
Polychlorinated biphenyls [Aroclors]
2,3,7,8-TCDD [2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlprodibenzorurans [TCDFs]
2,4,6-Trichlorophenol
Facility 126
Arsenic
Benzo(a)pyrene
Benzo (b)fmoranthene
Benzo [a] anthracene
Bromodichloromethane [Dichlorobromomethane]
Chloroform [Trichloromethane]
Chrysene
Dibenz [a,h] anthracene
Indeno(l,2,3-cd) pyrene
Methylene chloride [Dichloromethane]
Polychlorinated biphenyls [Aroclors]
Trichloroethylene [TCE]
Facilities having 9 chemicals with cancer effects
Facility 085
Arsenic
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Bromodichloromethane [Dichlorobromomethane]
(continued)
ETT33
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Bromoform [Tribromomethane]
Carbon tetrachloride
Chlorodibromomethane [Dibromochloromethane]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Methylene chloride [Dichloromethane]
Facilities having 8 chemicals with cancer effects
Facility 148
Chlordane, alpha & gamma isomers
1,4-Dichlorobenzene [p-Dichlorobenzene]
2,4-Dinitrotoluene
Heptachlor
Heptachlor epoxide, alpha, beta, and gamma isomers
Lindane [gamma-Hexachlorocyclohexane] [gamma-BHC]
Toxaphene [Chlorinated camphene]
2,4,6-Trichlorophenol
Facilities having 7 chemicals with cancer effects
Facility 104
Benzene
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Chloroform [Trichloromethane]
1,2-Dichloroethane [Ethylene dichloride]
1,2-Dichloropropane [Prqpylene dichloride]
1,1,2-Trichloroethane [Vinyl trichloride]
Vinyl chloride [chloroethylene]
Facility 174
Arsenic
Benzene
Benzo [a] anthracene
Chrysene
Dibenz [a,h] anthracene
Indeno(l,2,3-cd) pyrene
Methylene chloride [Dichloromethane]
Facilities having 6 chemicals with cancer effects
Facility 021
Acetaldehyde [Ethanal]
Benzene
1,2-Dichloroethane [Ethylene dichloride]
1,4-Dioxane [1,4-Diethyleneoxide]
Ethylene oxide
Formaldehyde
Facility 046
Acrylonitrile
Benzene
2-chloroethyl) ether [sym-Dichloroethyl ether]
2-chloroisopropyl) ether [2,2-Dichloroisopropyl ether]
2-ethylhexyl) phthalate [Dioctyl phthalate]
~ " iichlo ' " '
Bis
Bis
Bis
1,2-Dichlbroprbpahe [Propylene dichloride]
Facility 084
Benzo(a)pyrene
Benzo (b)ffuoranthene
(continued)
B-134
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Benzo [a] anthracene
Chrysene
Formaldehyde
Indeno(l,2,3-cd) pyrene
Facility 118
Acetaldehyde [Ethanal]
Arsenic
Chloroform [Trichloromethane]
Formaldehyde
2,3,7,8-TCDD[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Tetrachlorodibenzofurans [TCDFs]
Facility 134
Chloroform [Trichloromethane]
1,2-Dichloroethane [Ethylene dichloride]
Ethylene oxide
Hexachlorobenzene
Hexachlorodibenzofurans [HxCDFs]
Propylene oxide [1,2-Epoxypropane]
Facility 157
Arsenic
Bromodichloromethane [Dichlorobromomethane]
Chlorodibromomethane [Dibromochloromethane]
Chloroform [Trichloromethane]
Formaldehyde
Methylene chloride [Dichloromethane]
Facilities having 5 chemicals with cancer effects
Facility 002
Benzo(a)pyrene
Bromodichloromethane [Dichlorobromomethane]
Chlorodibromomethane [Dibromochloromethane]
Chloroform [Trichloromethane]
Chrysene
Facility 012
Acrylonitrile
Arsenic
Bromodichloromethane [Dichlorobromomethane]
Bromoform [Tribromomethane]
Chloroform [Trichloromethane]
Facility 038
Acetaldehyde [Ethanal]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Formaldehyde
2,3,7,8-TCDD[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Facility 041
Acetaldehyde [Ethanal]
Formaldehyde
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachlorodibenzofurans [HxCDFs]
Pentachlorodibenzofurans [PeCDFs]
(continued)
B-135
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 151
Aniline
beta-Hexachlorocyclohexane [beta-BHC]
Chloroform [Tricnloromethane]
Heptachlor epoxide, alpha, beta, and gamma isomers
alpha-Hexachlorocyclohexane [alpha-BHC]
Facility 156
Acetaldehyde [Ethanal]
Formaldehyde
2,3,7,8-TCDD[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Tetrachlorodibenzo-p-dioxins [TCDDs]
Tetrachlorodibenzofurans [TCDFs]
Facility 160
Arsenic
Bromodichloromethane [Dichlorobromomethane]
Chloroform [Trichloromethane]
Methylene chloride [Dichloromethane]
2,4,6-Trichlorophenol
Facilities having 4 chemicals with cancer effects
Facility 035
Benzene
Benzo(a)pyrene
Benzo [a] anthracene
Chrysene
Facility 048
Bromodichloromethane [Dichlorobromomethane]
Bromoform [Tribromomethane]
Chlorodibromomethane [Dibromochloromethane]
Chloroform [Trichloromethane]
Facility 081
Bromoform [Tribromomethane]
Chloroform [Trichloromethane]
1,1-Dichloroethylene [Vinylidene chloride]
Methylene chloride [Dichloromethane]
Facility 115
Benzene
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Methylene chloride [Dichloromethane]
Facility 185
Chloroform [Trichloromethane]
1,2-Dichloroethane [Ethylene dichloride]
Formaldehyde
Methylene chloride [Dichloromethane]
Facilities having 3 chemicals with cancer effects
Facility 022
Acetaldehyde [Ethanal]
Chloroform [Trichloromethane]
Formaldehyde
(continued)
B-136
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 023
Acetaldehyde [Ethanal]
Arsenic
Chloroform [Trichloromethane]
Facility 037
Arsenic
Benzene
Chrysene
Facility 071
Acetaldehyde [Ethanal]
Chloromethane [Methyl chloride]
Tetrachlorodibenzofurans [TCDFs]
Facility 128
Arsenic
Benzene
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Facility 159
Arsenic
Benzene
N-Nitrosodiphenylamine [Diphenylnitrosamine]
Facility 173
Acetaldehyde [Ethanal]
Arsenic
Chloroform [Trichloromethane]
Facilities having 2 chemicals with cancer effects
Facility 006
Chloroform [Trichloromethane]
Tetrachlorodibenzo-p-dioxins [TCDDs]
Facility 007
Arsenic
Benzene
Facility 053
Acetaldehyde [Ethanal]
Formaldehyde
Facility 088
Acetaldehyde [Ethanal]
Chloroform [Trichloromethane]
Facility 091
Aniline
Benzene
Facility 098
Acetaldehyde [Ethanal]
Chloroform [Trichloromethane]
Facility 107
Chloroform [Trichloromethane]
Methylene chloride [Dichloromethane]
(continued)
ETT37
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 127
Arsenic
Formaldehyde
Facility 180
Arsenic
Chloroform [Trichloromethane]
Facility 183
Aniline
Chloromethane [Methyl chloride]
Facility 187
Arsenic
Bromoform [Tribromomethane]
Facility 191
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Formaldehyde
Body weight
Facilities having 8 chemicals with body weight effects
Facility 068
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
Cyanide
1,2-Dichlorobenzene [o-Dichlorobenzene]
Diethyl phthalate [DEP]
Naphthalene
Nickel
Xylenes, mixed isomers [Xylenes]
Facilities having 7 chemicals with body weight effects
Facility 021
o-Cresol [2-Methyl phenol]
Ethyl acetate
Ethyl ether [Diethyl ether]
Formaldehyde
Formic Acid
Naphthalene
Xylenes, mixed isomers [Xylenes]
Facilities having 6 chemicals with body weight effects
Facility 118
Cresols
Cyanide
Formaldehyde
Formic Acid
Nickel
Xylenes, mixed isomers [Xylenes]
Facility 157
Cyanide
(continued)
B-138
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Formaldehyde
Nickel
m-Xylene
o-Xylene
p-Xylene
Facilities having 4 chemicals with body weight effects
Facility 023
Cyanide
Ethyl acetate
Ethyl ether [Diethyl ether]
Formic Acid
Facility 041
Cresols
Formaldehyde
Nickel
Xylenes, mixed isomers [Xylenes]
Facility 091
o-Cresol [2-Methyl phenol]
Naphthalene
Nickel
Xylenes, mixed isomers [Xylenes]
Facility 103
Cresols
Formaldehyde
Naphthalene
Nickel
Facility 105
Cyclohexanone
Naphthalene
Nickel
Vinyl acetate
Facility 137
Cyanide
Formaldehyde
Formic Acid
Nickel
Facility 158
Diethyl phthalate [DEP]
Ethyl acetate
Ethyl ether [Diethyl ether]
Nickel
Facility 179
Cyanide
m-Xylene
o-Xylene
p-Xylene
Facility 185
Cyanide
Formaldehyde
Formic Acid
(continued)
ETT39
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Nickel
Facility 191
Cyanide
Formaldehyde
Nickel
Vinyl acetate
Facilities having 3 chemicals with body weight effects
Facility 018
Nickel
o-Xylene
Xylenes, mixed isomers [Xylenes]
Facility 032
Cyanide
Naphthalene
Nickel
Facility 037
Naphthalene
Nickel
Xylenes, mixed isomers [Xylenes]
Facility 104
Cyanide
Diethyl phthalate [DEP]
Naphthalene
Facility 127
Cresols
Formaldehyde
Nickel
Facility 130
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
Cresols
Facility 159
Cyanide
Nickel
Xylenes, mixed isomers [Xylenes]
Facility 193
Naphthalene
Nickel
Xylenes, mixed isomers [Xylenes]
Facilities having 2 chemicals with body weight effects
Facility 013
Chloroprene [2-Chloro-1,3-butadiene]
Xylenes, mixed isomers [Xylenes]
Facility 022
Formaldehyde
Nickel
(continued)
B-140
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 029
Cyanide
Nickel
Facility 035
Naphthalene
Xylenes, mixed isomers [Xylenes]
Facility 036
Cyanide
Nickel
Facility 045
Cyclohexanone
Nickel
Facility 046
Naphthalene
Nickel
Facility 053
Formaldehyde
Nickel
Facility 058
Formaldehyde
Nickel
Facility 084
Formaldehyde
Nickel
Facility 088
Formic Acid
Nickel
Facility 114
Cyanide
Nickel
Facility 126
Cyanide
Naphthalene
Facility 135
Cyanide
Nickel
Facility 140
Formaldehyde
Nickel
Facility 148
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
Facility 156
Cresols
Formaldehyde
(continued)
B-141
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 173
Cresols
Naphthalene
Developmental
Facilities having 4 chemicals with developmental effects
Facility 068
Carbon disulfide
Ethyl benzene
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facilities having 3 chemicals with developmental effects
Facility 041
Carbon disulfide
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 103
Carbon disulfide
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 105
Ethyl benzene
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 151
Carbon disulfide
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 156
Carbon disulfide
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 160
Ethyl benzene
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facilities having 2 chemicals with developmental effects
Facility 018
Ethyl benzene
Phenol
Facility 021
Ethyl benzene
Phenol
(continued)
B-142
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 046
Ethyl benzene
Methyl ethyl ketone [2-Butanone] [MEK]
Facility 054
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 071
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 085
Chloroethane [Ethyl chloride]
Phenol
Facility 086
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 091
Ethyl benzene
Phenol
Facility 118
Carbon disulfide
Methyl ethyl ketone [2-Butanone] [MEK]
Facility 127
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 159
Ethyl benzene
Phenol
Facility 173
Methyl ethyl ketone [2-Butanone] [MEK]
Phenol
Facility 174
Ethyl benzene
Phenol
(continued)
B-143
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Hematological
Facilities having 7 chemicals with hematological effects
Facility 068
Antimony
2,4-Dimethylphenol
Fluoranthene
Fluorene
Mercury
Styrene
Zinc
Facilities having 5 chemicals with hematological effects
Facility 046
Bis(2-chloroisopropyl) ether [2,2 -Dichloroisopropyl ether]
2,6-Dinitrotoluene
Mercury
Styrene
Zinc
Facility 091
Antimony
2,4-Dimethylphenol
Fluorene
Mercury
Zinc
Facilities having 4 chemicals with hematological effects
Facility 104
Fluoranthene
Fluorene
1,1,2-Trichloroethane [Vinyl trichloride]
Zinc
Facility 126
Fluoranthene
Fluorene
Mercury
Zinc
Facility 159
Antimony
Fluoranthene
Mercury
Zinc
Facilities having 3 chemicals with hematological effects
Facility 037
Antimony
Mercury
Zinc
(continued)
B-144
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 118
Antimony
Mercury
Zinc
Facility 160
Antimony
Mercury
Zinc
Facility 174
Fluoranthene
Mercury
Zinc
Facility 180
Antimony
Mercury
Zinc
Facility 187
Antimony
Mercury
Zinc
Facilities having 2 chemicals with hematological effects
Facility 005
Mercury
Zinc
Facility 006
Mercury
Zinc
Facility 012
Mercury
Zinc
Facility 014
Mercury
Zinc
Facility 019
Antimony
Zinc
Facility 021
Etnylene oxide
Styrene
Facility 022
2,4-Dimethylphenol
Zinc
Facility 028
Mercury
Zinc
(continued)
B-145
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 036
Mercury
Zinc
Facility 041
Styrene
Zinc
Facility 044
Mercury
Zinc
Facility 045
Mercury
Zinc
Facility 050
Antimony
Zinc
Facility 080
Mercury
Zinc
Facility 084
Fluoranthene
Zinc
Facility 085
Mercury
Zinc
Facility 088
Mercury
Zinc
Facility 103
Antimony
Zinc
Facility 105
Styrene
Zinc
Facility 114
Fluorene
Zinc
Facility 123
Mercury
Zinc
Facility 128
Mercury
Zinc
Facility 135
Antimony
Zinc
(continued)
B-146
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 148
2,4-D [2,4-Dichlorophenoxyacetic acid]
2,4-Dinitrotoluene
Facility 157
Mercury
Zinc
Facility 164
Mercury
Zinc
Facility 170
Antimony
Zinc
Facility 179
Mercury
Zinc
Facility 183
Styrene
Zinc
Kidney
Facilities having 11 chemicals with kidney effects
Facility 068
Barium
Cadmium
Chlorobenzene
Chloroform [Trichloromethane]
Ethyl benzene
Ethylene glycol
Ethylidene dichloride [1,1-Dichloroethane]
Fluoranthene
Methyl tert-butyl ether [MTBE]
Pyrene
Toluene
Facilities having 8 chemicals with kidney effects
Facility 103
Acetone [2-Propanone]
Barium
Cadmium
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Ethylene glycol
Methyl isoburyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
Pentachlorophenol [PCP]
Facilities having 7 chemicals with kidney effects
Facility 002
Acetone [2-Propanone]
(continued)
B-147
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Barium
Bromodichloromethane [Dichlorobromomethane]
Cadmium
Chloroform [Trichloromethane]
Methyl tert-butyl ether [MTBE]
Pyrene
Facility 021
Acetone [2-Propanone]
Allyl alcohol
Barium
n-Dioctyl phthalate
Ethyl benzene
Ethylene glycol
Toluene
Facility 126
Acetone [2-Propanone]
Barium
Bromodichloromethane [Dichlorobromomethane]
Cadmium
Chloroform [Trichloromethane]
Fluoranthene
Pyrene
Facility 160
Acetone [2-Propanone]
Barium
Bromodichloromethane [Dichlorobromomethane]
Cadmium
Chloroform [Trichloromethane]
Ethyl benzene
Toluene
Facilities having 6 chemicals with kidney effects
Facility 104
Chlorobenzene
Chloroform [Trichloromethane]
Ethyl benzene
Fluoranthene
Pyrene
Toluene
Facility 118
Barium
Cadmium
Chloroform [Trichloromethane]
Ethylene glycol
Methyl isobutyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
2,4,5-Trichlorophenol
Facility 157
Barium
Bromodichloromethane [Dichlorobromomethane]
Cadmium
Chloroform [Trichloromethane]
Ethyl benzene
Toluene
(continued)
B-148
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 159
Barium
Cadmium
Ethyl benzene
Fluoranthene
Pyrene
Toluene
Facilities having 5 chemicals with kidney effects
Facility 012
Acetone [2-Propanone]
Barium
Bromodichloromethane [Dichlorobromomethane]
Cadmium
Chloroform [Trichloromethane]
Facility 023
Acetone [2-Propanone]
Allyl alcohol
Chloroform [Trichloromethane]
Ethylene glycol
Methyl tert-butyl ether [MTBE]
Facility 038
Acetone [2-Propanone]
Barium
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Ethylene glycol
Facility 046
Acetone [2-Propanone]
Barium
2,6-Dinitrotoluene
Ethyl benzene
Toluene
Facility 156
Acetone [2-Propanone]
Barium
Cumene [Isopropyl benzene]
Ethylene glycol
Methyl isobutyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
Facility 174
Barium
Ethyl benzene
Fluoranthene
Pyrene
Toluene
Facility 191
Barium
Cadmium
Epichlorohydrin [l-Chloro-2,3-epoxypropane]
Ethylene glycol
Vinyl acetate
(continued)
B-149
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facilities having 4 chemicals with kidney effects
Facility 018
Barium
Ethyl benzene
Ethylene glycol
Toluene
Facility 022
Barium
Cadmium
Chloroform [Trichloromethane]
Ethylene glycol
Facility 084
Acetone [2-Propanone]
Barium
Fluoranthene
Pyrene
Facility 085
Bromodichloromethane [Dichlorobromomethane]
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
n-Dioctyl phthalate
Facility 091
Barium
Ethyl benzene
Methyl tert-butyl ether [MTBE]
Toluene
Facility 105
Acetone [2-Propanone]
Ethyl benzene
Toluene
Vinyl acetate
Facility 115
Barium
Chloroform [Trichloromethane]
Chloromethane [Methyl chloride]
Ethylidene dichloride |l,l-Dichloroethane]
Facility 173
Barium
Chloroform [Trichloromethane]
Ethylene glycol
Toluene
Facility 180
Acetone [2-Propanone]
Barium
Chloroform [Trichloromethane]
Toluene
Facility 183
Chloromethane [Methyl chloride]
Ethyl benzene
Ethylene glycol
(continued)
ETT50
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Toluene
Facilities having 3 chemicals with kidney effects
Facility 006
Barium
Chloroform [Trichloromethane]
Ethylene glycol
Facility 032
Barium
Cadmium
Pyrene
Facility 035
Ethyl benzene
Pyrene
Toluene
Facility 037
Cadmium
Pyrene
Toluene
Facility 041
Barium
Cumene [Isopropyl benzene]
Ethylene glycol
Facility 077
Acetone [2-Propanone]
Cadmium
Toluene
Facility 081
Barium
Chloroform [Trichloromethane]
1,1-Dichloroethylene [Vinylidene chloride]
Facility 148
2,4-D [2,4-Dichlorophenoxyacetic acid]
Lindane [gamma-Hexachlorocyclohexane] [gamma-BHC]
2,4,5-Trichlorophenol
Facility 151
Acetone [2-Propanone]
Barium
Chloroform [Trichloromethane]
Facility 172
Barium
Cadmium
n-Diocryl phthalate
Facility 193
Barium
Ethyl benzene
Toluene
(continued)
B-151
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facilities having 2 chemicals with kidney effects
Facility 004
Barium
Cadmium
Facility 005
Barium
Cadmium
Facility 013
Ethyl benzene
Toluene
Facility 014
Barium
Cadmium
Facility 036
Barium
Cadmium
Facility 039
Alfyl alcohol
Chloromethane [Methyl chloride]
Facility 040
Barium
Cadmium
Facility 043
Barium
Toluene
Facility 048
Bromodichloromethane [Dichlorobromomethane]
Chloroform [Trichloromethane]
Facility 050
Barium
Cadmium
Facility 053
Acetone [2-Propanone]
Cadmium
Facility 080
Barium
Cadmium
Facility 086
Barium
Cadmium
Facility 088
Barium
Chloroform [Trichloromethane]
Facility 090
Barium
(continued)
ETT52
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Cadmium
Facility 116
Barium
Pentachlorophenol [PCP]
Facility 123
Barium
Cadmium
Facility 128
Ethyl benzene
Toluene
Facility 134
Chloroform [Trichloromethane]
Ethylene glycol
Facility 135
Barium
Cadmium
Facility 164
Barium
Cadmium
Facility 167
Acetone [2-Propanone]
Toluene
Facility 176
Barium
Cadmium
Facility 185
Chloroform [Trichloromethane]
Epichlorohydrin [l-Chloro-2,3-epoxypropane]
Liver
Facilities having 14 chemicals with liver effects
Facility 068
Acenaphthene
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Chlorobenzene
Chloroform [Trichloromethane]
1,4-Dichlorobenzene [p-Dichlorobenzene]
N,N-Dimethyl formamide [DMF]
Ethyl benzene
Fluoranthene
Methanol [methyl alcohol]
Methyl tert-butyl ether [MTBE]
Pyridine
Styrene
Tetrachloroethylene [Perchloroethylene]
Toluene
(continued)
ETT53
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facilities having 11 chemicals with liver effects
Facility 104
Acenaphthene
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Chlorobenzene
Chloroform [Trichloromethane]
1,2-Dichloropropane [Propylene dichloride]
Ethyl benzene
Fluoranthene
Toluene
1,2,4-Trichlorobenzene
1,1,2-Trichloroethane [Vinyl trichloride]
Vinyl chloride [chloroethylene]
Facility 148
Chlordane, alpha & gamma isomers
2,4-D [2,4-Dichlorophenoxyacetic acid]
1,4-Dichlorobenzene [p-Dichlorobenzene]
2,4-Dinitrotoluene
Endrin
Heptachlor
Heptachlor epoxide, alpha, beta, and gamma isomers
Lindane [gamma-Hexachlorocyclohexane] [gamma-BHC]
Silvex [2,4,5-Trichlorophenoxypropionic acid]
Toxaphene [Chlorinated camphene]
2,4,5-Trichlorophenol
Facilities having 10 chemicals with liver effects
Facility 046
Acetone [2-Propanone]
2-chloroethyl) ether [sym-Dichloroethyl ether]
2-chloroisopropyl) ether [2,2-Dichloroisopropyl ether]
2-ethylhexyl) phthalate [Dioctyl phthalate]
Bis
Bis
1,2-Dichloropropane [Propylene dichloride]
2,6-Dinitrotoluene
Ethyl benzene
Methanol [methyl alcohol]
Styrene
Toluene
Facility 103
Acetone [2-Propanone]
Chloroform [Trichloromethane]
Methanol [methyl alcohol]
Methyl isoburyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
Methylene chloride [Dichloromethane]
Pentachlorophenol [PCP]
Polychlorinated biphenyls [Aroclors]
2,3,7,8-TCDD[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
2,3,4,6-Tetrachlorophenol
Thallium
Facilities having 8 chemicals with liver effects
Facility 021
Acetone [2-Propanone]
Allyl alcohol
n-Dioctyl phthalate
(continued)
B-154
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Ethyl benzene
Methanol [methyl alcohol]
Pyridine
Styrene
Toluene
Facility 085
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Bromodichloromethane [Dichlorobromomethane]
Bromoform [Tribromomethane]
Carbon tetrachloride
Chlorodibromomethane [Dibromochloromethane]
Chloroform [Trichloromethane]
n-Dioctyl phthalate
Methylene chloride [Dichloromethane]
Facilities having 7 chemicals with liver effects
Facility 023
Acetone [2-Propanone]
Allyl alcohol
Chloroform [Trichloromethane]
N,N-Dimethyl formamide [DMF]
Methanol [methyl alcohol]
Methyl tert-butyl ether [MTBE]
Pyridine
Facility 126
Acenaphthene
Acetone [2-Propanone]
Bromodichloromethane [Dichlorobromomethane]
Chloroform [Trichloromethane]
Fluoranthene
Methylene chloride [Dichloromethane]
Polychlorinated biphenyls [Aroclors]
Facilities having 6 chemicals with liver effects
Facility 105
Acenaphthene
Acetone [2-Propanone]
Ethyl benzene
Methanol [methyl alcohol]
Styrene
Toluene
Facility 118
Chloroform [Trichloromethane]
Methanol [methyl alcohol]
Methyl isobutyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
2,3,7,8-TCDD[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Thallium
2,4,5-Trichlorophenol
(continued)
B-155
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 157
Bromodichloromethane [Dichlorobromomethane]
Chlorodibromomethane [Dibromochloromethane]
Chloroform [Trichloromethane]
Ethyl benzene
Methylene chloride [Dichloromethane]
Toluene
Facility 160
Acetone [2-Propanone]
Bromodichloromethane [Dichlorobromomethane]
Chloroform [Trichloromethane]
Ethyl benzene
Methylene chloride [Dichloromethane]
Toluene
Facilities having 5 chemicals with liver effects
Facility 002
Acetone [2-Propanone]
Bromodichloromethane [Dichlorobromomethane]
Chlorodibromomethane [Dibromochloromethane]
Chloroform [Trichloromethane]
Methyl tert-butyl ether [MTBE]
Facility 151
Acetone [2-Propanone]
beta-Hexachlorocyclohexane [beta-BHC]
Chloroform [Trichloromethane]
Heptachlor epoxide, alpha, beta, and gamma isomers
alpha-Hexachlorocyclohexane [alpha-BHC]
Facilities having 4 chemicals with liver effects
Facility 012
Acetone [2-Propanone]
Bromodichloromethane [Dichlorobromomethane]
Bromoform [Tribromomethane]
Chloroform [Trichloromethane]
Facility 038
Acetone [2-Propanone]
Chloroform [Trichloromethane]
Methanol [methyl alcohol]
2,3,7,8-TCDD [2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Facility 048
Bromodichloromethane [Dichlorobromomethane]
Bromoform [Tribromomethane]
Chlorodibromomethane [Dibromochloromethane]
Chloroform [Trichloromethane]
Facility 081
Bromoform [Tribromomethane]
Chloroform [Trichloromethane]
1,1-Dichloroethylene [Vinylidene chloride]
Methylene chloride [Dichloromethane]
Facility 091
Acenaphthene
(continued)
B-156
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Ethyl benzene
Methyl tert-butyl ether [MTBE]
Toluene
Facility 156
Acetone [2-Propanone]
Methane! [methyl alcohol]
Methyl isobutyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
2,3,7,8-TCDD[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Facility 159
Ethyl benzene
Fluoranthene
Thallium
Toluene
Facility 174
Ethyl benzene
Fluoranthene
Methylene chloride [Dichloromethane]
Toluene
Facility 183
Ethyl benzene
Methanol [methyl alcohol]
Styrene
Toluene
Facilities having 3 chemicals with liver effects
Facility 022
Chloroform [Trichloromethane]
Furfural
Methanol [methyl alcohol]
Facility 035
Acenaphthene
Ethyl benzene
Toluene
Facility 077
Acetone [2-Propanone]
Methanol [methyl alcohol]
Toluene
Facility 084
Acetone [2-Propanone]
Fluoranthene
Methanol [methyl alcohol]
Facility 128
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Ethyl benzene
Toluene
Facility 167
Acetone [2-Propanone]
Toluene
1,2,4-Trichlorobenzene
(continued)
B-157
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 172
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
n-Dioctyl phthalate
Ethylene thiourea
Facility 173
Chloroform [Trichloromethane]
Methanol [methyl alcohol]
Toluene
Facility 180
Acetone [2-Propanone]
Chloroform [Trichloromethane]
Toluene
Facility 185
Chloroform [Trichloromethane]
Methanol [methyl alcohol]
Methylene chloride [Dichloromethane]
Facilities having 2 chemicals with liver effects
Facility 006
Chloroform [Trichloromethane]
Methanol [methyl alcohol]
Facility 013
Ethyl benzene
Toluene
Facility 018
Ethyl benzene
Toluene
Facility 039
Allyl alcohol
Methanol [methyl alcohol]
Facility 041
Methanol [methyl alcohol]
Styrene
Facility 053
Acetone [2-Propanone]
Methanol [methyl alcohol]
Facility 088
Chloroform [Trichloromethane]
Methanol [methyl alcohol]
Facility 098
Chloroform [Trichloromethane]
Methanol [methyl alcohol]
Facility 107
Chloroform [Trichloromethane]
Methylene chloride [Dichloromethane]
Facility 115
Chloroform [Trichloromethane]
(continued)
ETT58
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Methylene chloride [Dichloromethane]
ility
Chlo
Facility 134
loroform [Trichloromethane]
Hexachlorobenzene
Facility 137
Acetone [2-Propanone]
Methane! [methyl alcohol]
Facility 158
Methanol [methyl alcohol]
Toluene
Facility 191
Bis(2-ethylhexyl) phthalate [Dioctyl phthalate]
Methanol [methyl alcohol]
Facility 193
Ethyl benzene
Toluene
Lung
Facilities having 4 chemicals with lung effects
Facility 080
Arsenic
Beryllium
Cadmium
Chromium VI [Hexavalent Chromium]
Facility 135
Arsenic
Beryllium
Cadmium
Chromium VI [Hexavalent Chromium]
Facilities having 3 chemicals with lung effects
Facility 012
Arsenic
Beryllium
Cadmium
Facility 014
Arsenic
Cadmium
Chromium VI [Hexavalent Chromium]
Facility 029
Beryllium
Cadmium
Chromium VI [Hexavalent Chromium]
Facility 036
Arsenic
(continued)
B-159
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Beryllium
Cadmium
Facility 068
Arsenic
Beryllium
Cadmium
Facility 103
Arsenic
Beryllium
Cadmium
Facility 118
Arsenic
Beryllium
Cadmium
Facility 160
Arsenic
Beryllium
Cadmium
Facilities having 2 chemicals with lung effects
Facility 004
Arsenic
Cadmium
Facility 007
Arsenic
Cadmium
Facility 037
Arsenic
Cadmium
Facility 040
Arsenic
Cadmium
Facility 044
Arsenic
Cadmium
Facility 046
Bis(2-chloroisopropyl) ether [2,2 -Dichloroisopropyl ether]
Chromium VI [Hexavalent Chromium]
Facility 050
Beryllium
Cadmium
Facility 067
Arsenic
Cadmium
Facility 085
Arsenic
Chromium VI [Hexavalent Chromium]
(continued)
ETT60
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 086
Cadmium
Chromium VI [Hexavalent Chromium]
Facility 126
Arsenic
Cadmium
Facility 157
Arsenic
Cadmium
Facility 159
Arsenic
Cadmium
Facility 174
Arsenic
Beryllium
Facility 176
Arsenic
Cadmium
Facility 182
Arsenic
Cadmium
Neurological
Facilities having 11 chemicals with neurological effects
Facility 068
Carbon disulfide
m-Cresol [3-Methyl phenol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Cyanide
2,4-Dimethylphenol
Mercury
Methanol [methyl alcohol]
Styrene
Toluene
Xylenes, mixed isomers [Xylenes]
Facilities having 8 chemicals with neurological effects
Facility 118
Carbon disulfide
Cresols
Cyanide
Manganese
Mercury
Methanol [methyl alcohol]
Methyl isoburyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
Xylenes, mixed isomers [Xylenes]
(continued)
B-161
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facilities having 7 chemicals with neurological effects
Facility 021
n-Butyl alcohol Jn-Butanol]
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
Methanol [methyl alcohol]
Styrene
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 041
Carbon disulfide
Cresols
n-Hexane
Manganese
Methanol [methyl alcohol]
Styrene
Xylenes, mixed isomers [Xylenes]
Facility 157
Cyanide
Manganese
Mercury
Toluene
m-Xylene
o-Xylene
p-Xylene
Facilities having 6 chemicals with neurological effects
Facility 046
2,6-Dinitrotoluene
Manganese
Mercury
Methanol [methyl alcohol]
Styrene
Toluene
Facility 091
o-Cresol [2-Methyl phenol]
p-Cresol [4-Methyl phenol]
2,4-Dimethylphenol
Mercury
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 156
Carbon disulfide
Cresols
n-Hexane
Manganese
Methanol [methyl alcohol]
Methyl isoburyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
Facility 179
n-Butyl alcohol [n-Butanol]
Cyanide
Mercury
m-Xylene
(continued)
ETT62
-------
March 26, 2001 Appendix B
Table B-29. (continued)
o-Xylene
p-Xylene
Facilities having 5 chemicals with neurological effects
Facility 103
Carbon disulfide
Cresols
Manganese
Methanol [methyl alcohol]
Methyl isobutyl ketone [Hexone] [4-Methyl-2-pentanone] [MIBK]
Facility 130
m-Cresol [3 -Methyl phenol]
o-Cresol [2 -Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols
Mercury
Facility 148
m-Cresol [3 -Methyl phenol]
o-Cresol [2 -Methyl phenol]
p-Cresol [4-Methyl phenol]
2,4-Dinitrotoluene
Endrin
Facilities having 4 chemicals with neurological effects
Facility 018
Manganese
Toluene
o-Xylene
Xylenes, mixed isomers [Xylenes]
Facility 105
n-Butyl alcohol [n-Butanol]
Methanol [methyl alcohol]
Styrene
Toluene
Facility 137
n-Butyl alcohol [n-Butanol]
Cyanide
Isobutyl alcohol [Isobutanol]
Methanol [methyl alcohol]
Facility 159
Cyanide
Mercury
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 173
Cresols
Manganese
Methanol [methyl alcohol]
Toluene
Facility 174
Manganese
(continued)
ETT63
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Mercury
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 180
Carbon disulfide
Manganese
Mercury
Toluene
Facility 183
Methanol [methyl alcohol]
Styrene
Toluene
Xylenes, mixed isomers [Xylenes]
Facilities having 3 chemicals with neurological effects
Facility 022
2,4-Dimethylphenol
Manganese
Methanol [methyl alcohol]
Facility 036
Cyanide
Manganese
Mercury
Facility 037
Mercury
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 043
p-Cresol [4-Methyl phenol]
Manganese
Toluene
Facility 077
Manganese
Methanol [methyl alcohol]
Toluene
Facility 088
Manganese
Mercury
Methanol [methyl alcohol]
Facility 126
Cyanide
Manganese
Mercury
Facility 127
Cresols
Manganese
Methanol [methyl alcohol]
Facility 128
Mercury
(continued)
ETT64
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 158
n-Butyl alcohol [n-Butanol]
Methanol [methyl alcohol]
Toluene
Facilities having 2 chemicals with neurological effects
Facility 005
Manganese
Mercury
Facility 006
Mercury
Methanol [methyl alcohol]
Facility 013
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 023
Cyanide
Methanol [methyl alcohol]
Facility 032
Cyanide
Manganese
Facility 035
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 038
Manganese
Methanol [methyl alcohol]
Facility 039
Allyl chloride
Methanol [methyl alcohol]
Facility 053
Manganese
Methanol [methyl alcohol]
Facility 080
Manganese
Mercury
Facility 084
Manganese
Methanol [methyl alcohol]
Facility 089
Cyanide
Manganese
(continued)
B-165
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 090
Cyanide
Manganese
Facility 104
Cyanide
Toluene
Facility 119
Cyanide
Manganese
Facility 123
Manganese
Mercury
Facility 135
Cyanide
Manganese
Facility 151
Carbon disulfide
Cresols
Facility 160
Mercury
Toluene
Facility 164
Manganese
Mercury
Facility 185
Cyanide
Methanol [methyl alcohol]
Facility 187
Manganese
Mercury
Facility 189
Toluene
Xylenes, mixed isomers [Xylenes]
Facility 191
Cyanide
Methanol [methyl alcohol]
Facility 193
Toluene
Xylenes, mixed isomers [Xylenes]
(continued)
B-166
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Organ weight
Facilities having 2 chemicals with organ weight effects
Facility 068
Diethyl phthalate [DEP]
Nickel
Facility 158
Diethyl phthalate [DEP]
Nickel
Reproductive
Facilities having 2 chemicals with reproductive effects
Facility 012
Acrylonitrile
Barium
Facility 021
Acrylic acid [propenoic acid]
Barium
Facility 041
Barium
n-Hexane
Facility 046
Acrylonitrile
Barium
Facility 068
Barium
Ethylene dibromide [1,2-Dibromoethane]
Facility 103
Barium
2-Chlorophenol [o-Chlorophenol]
Facility 151
Barium
Methoxychlor
Facility 156
Barium
n-Hexane
Facility 160
Barium
2-Chlorophenol [o-Chlorophenol]
(continued)
B-167
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Respiratory
Facilities having 5 chemicals with respiratory effects
Facility 021
Acetaldehyde [Ethanal]
Acrylic acid [propenoic acid]
p-Cresol [4-Methyl phenol]
Naphthalene
Toluene
Facility 068
Beryllium
p-Cresol [4-Methyl phenol]
Naphthalene
Selenium
Toluene
Facility 091
Beryllium
p-Cresol [4-Methyl phenol]
Naphthalene
Selenium
Toluene
Facility 103
Acetaldehyde [Ethanal]
Beryllium
Naphthalene
Selenium
2,3,7,8-TCDD[2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Facilities having 4 chemicals with respiratory effects
Facility 012
Acrolein [2-propenal]
Acrylonitrile
Beryllium
Selenium
Facility 046
Acrylonitrile
1,2-Dichloropropane [Propylene dichloride]
Naphthalene
Toluene
Facility 105
Acrylic acid [propenoic acid]
Naphthalene
Toluene
Vinyl acetate
Facility 118
Acetaldehyde [Ethanal]
Beryllium
Selenium
2,3,7,8-TCDD [2,3,7,8-Tetrachlorodibenzo-p-dioxin]
(continued)
B-168
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facilities having 3 chemicals with respiratory effects
Facility 023
Acetaldehyde [Ethanal]
Selenium
Triethylamine
Facility 037
Naphthalene
Selenium
Toluene
Facility 104
1,2-Dichloropropane [Propylene dichloride]
Naphthalene
Toluene
Facility 156
Acetaldehyde [Ethanal]
n-Hexane
2,3,7,8-TCDD [2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Facility 173
Acetaldehyde [Ethanal]
Naphthalene
Toluene
Facility 174
Beryllium
Selenium
Toluene
Facilities having 2 chemicals with respiratory effects
ility
Chlo
Facility 013
loroprene [2-Chloro-1,3-butadiene]
Toluene
Facility 022
Acetaldehyde [Ethanal]
Furfural
Facility 035
Naphthalene
Toluene
Facility 038
Acetaldehyde [Ethanal]
2,3,7,8-TCDD [2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Facility 041
Acetaldehyde [Ethanal]
n-Hexane
Facility 043
p-Cresol [4-Methyl phenol]
Toluene
Facility 085
Bromomethane [Methyl bromide]
(continued)
B-169
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Selenium
Facility 088
Acetaldehyde [Ethanal]
Selenium
Facility 130
p-Cresol [4-Methyl phenol]
Selenium
Facility 134
Acrylic acid [propenoic acid]
Propylene oxide [1,2-Epoxypropane]
Facility 135
Beryllium
Selenium
Facility 137
Acrylic acid [propenoic acid]
Methyl methacrylate
Facility 159
Selenium
Toluene
Facility 160
Beryllium
Toluene
Facility 185
Acrolein [2-propenarj
Epichlorohydrin [l-Chloro-2,3-epoxypropane]
Facility 191
^pichloi
' myl acetate
Epichlorohydrin [l-Chloro-2,3-epoxypropane]
Vin
Facility 193
Naphthalene
Toluene
Skin
Facilities having 2 chemicals with skin effects
Facility 004
Arsenic
Silver
Facility 012
Arsenic
Silver
Facility 014
Arsenic
Silver
(continued)
B-170
-------
March 26, 2001 Appendix B
Table B-29. (continued)
Facility 037
Arsenic
Silver
Facility 068
Arsenic
Silver
Facility 103
Arsenic
Silver
Facility 118
Arsenic
Silver
Facility 157
Arsenic
Silver
Facility 159
Arsenic
Silver
Facility 160
Arsenic
Silver
Vascular
Facilities having 2 chemicals with vascular effects
Facility 134
1,2-Dichloroethane [Ethylene dichloride]
Propylene oxide [1,2-Epoxypropane]
B-171
-------
March 26, 2001
Appendix B
Table B-30. Facility-Level Co-occurance of Chemicals in Wastewater by
Human Health Effect (Survey Database)
Estimated Number of Facilities with Co-occurrencesb in Wastewater'
Target Health
Effect a
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/Across Impoundments d
2-3
621 (254)
0(0)
0(0)
984 (414)
0(0)
0(0)
0(0)
635 (220)
13* (22)
0(0)
0(0)
0(0)
1,246 (289)
1,099 (379)
0(0)
972 (390)
766 (260)
0(0)
0(0)
873 (329)
13* (22)
123* (68)
832 (364)
0(0)
238 (96)
0(0)
0(0)
0(0)
6* (15)
4-6
328 (105)
0(0)
0(0)
193 (83)
0(0)
0(0)
0(0)
11* (21)
0(0)
0(0)
0(0)
0(0)
76* (53)
799 (220)
0(0)
339(107)
64* (49)
0(0)
0(0)
696 (285)
0(0)
0(0)
131* (69)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
7-10
390* (263)
0(0)
0(0)
13* (22)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11* (20)
111* (67)
0(0)
212* (171)
0(0)
0(0)
0(0)
73* (55)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11-20
30* (33)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11* (20)
0(0)
221* (200)
0(0)
0(0)
0(0)
10* (19)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
All Facilities
with 2 or More
Co-occurrences
1,369 (328)
0(0)
0(0)
1,191 (405)
0(0)
0(0)
0(0)
646 (220)
13* (22)
0(0)
0(0)
0(0)
1,334(291)
2,020 (412)
0(0)
1,743 (417)
830 (263)
0(0)
0(0)
1,653 (414)
13* (22)
123* (68)
962 (369)
0(0)
238 (96)
0(0)
0(0)
0(0)
6* (15)
For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based. Cancer or leukemia
for carcinogenic chemicals. See Appendix C for discussion of health benchmarks.
A facility-level co-occurrence is defined as when two or more chemicals with a common target health effect occur
within or across impoundments at a single facility.
Estimate for population of facilities with surface impoundments having constituents or pH of concern. Value in
parentheses is standard error. Asterisk (*) indicates estimates that may not be reliable because of a large relative
standard error (see Appendix A.5 for a discussion of standard error estimates).
Lists of the co-occurring chemicals at each facility in the sample are provided in Appendix B.
B-172
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March 26, 2001
Appendix B
Table B-31. Facility-Level Co-occurance of Chemicals in Sludge by
Human Health Effect (Survey Database)
Estimated Number of Facilities with Co-occurrencesb in Sludgec
Target Health
Effect a
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Cancer
Adrenal
Bladder
Number of Chemicals Co-occurring Within/Across Impoundments d
2-3
595 (220)
0(0)
0(0)
539(186)
0(0)
0(0)
0(0)
314(145)
11* (21)
0(0)
0(0)
0(0)
553 (170)
737 (217)
54* (54)
475 (187)
1,064 (246)
0(0)
0(0)
530 (163)
11* (21)
221* (140)
444 (150)
0(0)
324 (109)
0(0)
0(0)
0(0)
0(0)
595 (220)
0(0)
0(0)
4-6
107* (64)
0(0)
0(0)
93* (60)
0(0)
0(0)
0(0)
10* (20)
0(0)
0(0)
0(0)
0(0)
230* (140)
424 (181)
0(0)
72* (53)
51* (44)
0(0)
0(0)
210* (138)
0(0)
0(0)
234* (139)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
107* (64)
0(0)
0(0)
7-10
126* (69)
0(0)
0(0)
11* (20)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
20* (28)
71* (53)
0(0)
82* (56)
0(0)
0(0)
0(0)
189* (138)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
126* (69)
0(0)
0(0)
11-20
155* (136)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
10* (20)
0(0)
147* (137)
0(0)
0(0)
0(0)
10* (20)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
155* (136)
0(0)
0(0)
All Facilities
with 2 or More
Co-occurrences
983 (245)
0(0)
0(0)
642 (180)
0(0)
0(0)
0(0)
324 (145)
11* (21)
0(0)
0(0)
0(0)
803 (198)
1,242 (248)
54* (54)
776 (193)
1,116(248)
0(0)
0(0)
939 (200)
11* (21)
221* (140)
678(181)
0(0)
324 (109)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
(continued)
B-173
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March 26, 2001
Appendix B
Table B-31. (continued)
Estimated Number of Facilities with Co-occurrencesb in Sludge'
Target Health
Effect a
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/Across Impoundments d
2-3
539(186)
0(0)
0(0)
0(0)
314(145)
11* (21)
0(0)
0(0)
0(0)
553 (170)
737 (217)
54* (54)
475 (187)
1,064 (246)
0(0)
0(0)
530 (163)
11* (21)
221* (140)
444 (150)
0(0)
324 (109)
0(0)
0(0)
0(0)
0(0)
4-6
93* (60)
0(0)
0(0)
0(0)
10* (20)
0(0)
0(0)
0(0)
0(0)
230* (140)
424(181)
0(0)
72* (53)
51* (44)
0(0)
0(0)
210* (138)
0(0)
0(0)
234* (139)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
7-10
11* (20)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
20* (28)
71* (53)
0(0)
82* (56)
0(0)
0(0)
0(0)
189* (138)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11-20
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
10* (20)
0(0)
147* (137)
0(0)
0(0)
0(0)
10* (20)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
All Facilities
with 2 or More
Co-occurrences
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based. Cancer or leukemia
for carcinogenic chemicals. See Appendix C for discussion of health benchmarks.
A facility-level co-occurrence is defined as when two or more chemicals with a common target health effect occur
within or across impoundments at a single facility.
Estimate for population of facilities with surface impoundments having constituents or pH of concern. Value in
parentheses is standard error. Asterisk (*) indicates estimates that may not be reliable because of a large relative
standard error (see Appendix A.5 for a discussion of standard error estimates).
Lists of the co-occurring chemicals at each facility in the sample are provided in Appendix B.
B-174
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March 26, 2001
Appendix B
Table B-32. Impoundment-Level Co-occurance of Chemicals in Wastewater by Human
Health Effect (Survey Database)
Estimated Number of Impoundments with Co-occurrencesb in Wastewater'
Target Health
Effect a
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Cancer
Adrenal
Bladder
Number of Chemicals Co-occurring Within/Across Impoundments
2-3
1,230 (237)
0(0)
0(0)
2,061 (302)
0(0)
0(0)
0(0)
1,577 (363)
9* (15)
0(0)
0(0)
0(0)
3,326 (658)
2,749 (333)
0(0)
2,942 (282)
1,636 (325)
0(0)
0(0)
3,616 (258)
9* (15)
183 (69)
2,003 (272)
0(0)
485(111)
0(0)
0(0)
0(0)
0(0)
1,230 (237)
0(0)
0(0)
4-6
670 (129)
0(0)
0(0)
573 (120)
0(0)
0(0)
0(0)
9* (15)
0(0)
0(0)
0(0)
0(0)
121 (56)
2,043 (348)
0(0)
574 (120)
169 (67)
0(0)
0(0)
737 (302)
0(0)
0(0)
231(78)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
670 (129)
0(0)
0(0)
7-10
536* (273)
0(0)
0(0)
11* (17)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
9* (15)
72* (47)
0(0)
384* (206)
0(0)
0(0)
0(0)
452 (107)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
536* (273)
0(0)
0(0)
11-20
25* (26)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
9* (15)
0(0)
205* (180)
0(0)
0(0)
0(0)
9* (15)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
25* (26)
0(0)
0(0)
All
Impoundments
with 2 or More
Co-occurrences
2,461 (478)
0(0)
0(0)
2,646 (324)
0(0)
0(0)
0(0)
1,586 (363)
9* (15)
0(0)
0(0)
0(0)
3,456 (662)
4,873 (531)
0(0)
4,105(427)
1,805 (329)
0(0)
0(0)
4,814(411)
9* (15)
183 (69)
2,235 (285)
0(0)
485(111)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
(continued)
B-175
-------
March 26, 2001
Appendix B
Table B-32. (continued)
Estimated Number of Facilities with Co-occurrencesb in Sludge'
Target Health
Effect a
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/Across Impoundments d
2-3
2,061 (302)
0(0)
0(0)
0(0)
1,577 (363)
9* (15)
0(0)
0(0)
0(0)
3,326 (658)
2,749 (333)
0(0)
2,942 (282)
1,636 (325)
0(0)
0(0)
3,616 (258)
9* (15)
183 (69)
2,003 (272)
0(0)
485(111)
0(0)
0(0)
0(0)
0(0)
4-6
573 (120)
0(0)
0(0)
0(0)
9* (15)
0(0)
0(0)
0(0)
0(0)
121 (56)
2,043 (348)
0(0)
574 (120)
169 (67)
0(0)
0(0)
737 (302)
0(0)
0(0)
231 (78)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
7-10
11* (17)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
9* (15)
72* (47)
0(0)
384* (206)
0(0)
0(0)
0(0)
452 (107)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11-20
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
9* (15)
0(0)
205* (180)
0(0)
0(0)
0(0)
9* (15)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
All Facilities
with 2 or More
Co-occurrences
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
a For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based. Cancer or leukemia
for carcinogenic chemicals. See Appendix C for discussion of health benchmarks.
b An impoundment-level co-occurrence is defined as when two or more chemicals with a common target health
effect occur within or across a single impoundment.
0 Estimate for population of imppundments having constituents or pH of concern. Value in parentheses is standard
error. Asterisk (*) indicates estimates that may not be reliable because of a large relative standard error (see
Appendix A.5 for a discussion of standard error estimates).
B-176
-------
March 26, 2001
Appendix B
Table B-33. Impoundment-Level Co-occurance of Chemicals in Sludge by
Human Health Effect (Survey Data)
Estimated Number of Impoundments with Co-occurrencesb in Sludgec
Target Health
Effect a
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/Across Impoundments
2-3
843 (250)
0(0)
0(0)
978 (356)
0(0)
0(0)
0(0)
571 (213)
45* (36)
0(0)
0(0)
0(0)
1,254 (178)
1,966 (397)
46* (46)
1,054 (226)
1,969 (450)
0(0)
0(0)
1,546 (258)
45* (36)
378* (202)
666 (155)
0(0)
678 (134)
0(0)
0(0)
0(0)
0(0)
4-6
247 (83)
0(0)
0(0)
123 (59)
0(0)
0(0)
0(0)
45* (36)
0(0)
0(0)
0(0)
0(0)
420 (204)
1,033 (215)
0(0)
124 (59)
139 (62)
0(0)
0(0)
380 (172)
0(0)
0(0)
381* (202)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
7-10
130 (60)
0(0)
0(0)
45* (36)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
45* (36)
81* (48)
0(0)
106* (54)
0(0)
0(0)
0(0)
297* (201)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11-20
304* (168)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
45* (36)
0(0)
296* (168)
0(0)
0(0)
0(0)
45* (36)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
All
Impoundments
with 2 or More
Co-occurrences
1,526 (348)
0(0)
0(0)
1,146 (390)
0(0)
0(0)
0(0)
616(213)
45* (36)
0(0)
0(0)
0(0)
1,718 (273)
3,125 (550)
46* (46)
1,580 (324)
2,108(451)
0(0)
0(0)
2,268 (388)
45* (36)
378* (202)
1,047 (261)
0(0)
678 (134)
0(0)
0(0)
0(0)
0(0)
a For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based. Cancer or leukemia
for carcinogenic chemicals. See Appendix C for discussion of health benchmarks.
b An impoundment-level co-occurrence is defined as when two or more chemicals with a common target health
effect occur within or across a single impoundment.
0 Estimate for population of imppundments having constituents or pH of concern. Value in parentheses is standard
error. Asterisk (*) indicates estimates that may not be reliable because of a large relative standard error (see
Appendix A.5 for a discussion of standard error estimates).
B-177
-------
March 26, 2001
Appendix B
Table B-34. Facility-Level Co-occurance of Chemicals in Wastewater by
Human Health Effect (Risk Input Database)
Estimated Number of Facilities with Co-occurrencesb in Wastewater'
Target Health
Effect a
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/Across Impoundments d
2-3
631(253)
230* (174)
34* (36)
836 (376)
0(0)
0(0)
6* (15)
718 (223)
18* (27)
63* (49)
28* (33)
12* (21)
1,278 (291)
1,557 (480)
114* (65)
916 (367)
1,270 (369)
0(0)
12* (21)
842 (330)
274* (177)
185 (82)
1,009 (377)
0(0)
680 (261)
30* (34)
23* (30)
0(0)
85* (57)
4-6
326 (103)
56* (46)
46* (42)
397 (187)
0(0)
0(0)
0(0)
109* (63)
0(0)
12* (21)
30* (34)
0(0)
268* (176)
556 (202)
0(0)
379(111)
101* (60)
0(0)
0(0)
569 (262)
0(0)
37* (37)
200 (83)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
7-10
432* (261)
0(0)
0(0)
93* (58)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
65* (49)
331(160)
0(0)
348* (213)
45* (41)
0(0)
0(0)
264* (177)
0(0)
0(0)
10* (19)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11-20
241* (172)
0(0)
0(0)
16* (24)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
60* (47)
38* (36)
0(0)
282* (201)
0(0)
0(0)
0(0)
94* (57)
0(0)
0(0)
61* (47)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
>20
77* (51)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
46* (40)
0(0)
68* (49)
0(0)
0(0)
0(0)
5* (13)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
All Facilities
with 2 or More
Co-occurrences
1,706 (322)
286* (175)
80* (55)
1,342 (403)
0(0)
0(0)
6* (15)
827 (223)
18* (27)
74* (53)
57* (47)
12* (21)
1,671 (270)
2,528 (470)
114* (65)
1,993 (415)
1,416 (370)
0(0)
12* (21)
1,774 (414)
274* (177)
222 (90)
1,280 (383)
0(0)
680 (261)
30* (34)
23* (30)
0(0)
85* (57)
a For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based. Cancer or leukemia
for carcinogenic chemicals. See Appendix C for discussion of health benchmarks.
b A facility-level co-occurrence is defined as when two or more chemicals with a common target health effect occur
within or across impoundments at a single facility.
0 Estimate for population of facilities with surface impoundments having constituents or pH of concern. Value in
parentheses is standard error. Asterisk (*) indicates estimates that may not be reliable because of a large relative
standard error (see Appendix A.5 for a discussion of standard error estimates).
Lists of the co-occurring chemicals at each facility in the sample are provided in Appendix B.
B-178
-------
March 26, 2001
Appendix B
Table B-35. Facility-Level Co-occurance of Chemicals in Sludge by
Human Health Effect (Risk Input Database)
Estimated Number of Facilities with Co-occurrencesb in Sludgec
Target Health
Effect a
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/Across Impoundments d
2-3
552 (203)
41* (37)
12* (20)
371(138)
0(0)
0(0)
129* (125)
416(141)
13* (20)
161* (126)
144* (125)
8* (16)
560 (156)
894 (290)
259 (129)
403 (144)
1,049 (223)
0(0)
8* (16)
326 (98)
207* (128)
386 (159)
431 (140)
0(0)
558 (126)
21* (26)
8* (16)
0(0)
190* (126)
4-6
237 (85)
165* (126)
161* (126)
154 (69)
0(0)
0(0)
0(0)
205* (128)
0(0)
8* (16)
21* (26)
0(0)
250* (130)
329 (140)
0(0)
256 (88)
253* (133)
0(0)
0(0)
266 (130)
0(0)
30* (31)
341 (138)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
7-10
92* (54)
0(0)
0(0)
112* (59)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
49* (40)
274 (130)
0(0)
44* (38)
36* (34)
0(0)
0(0)
245* (132)
0(0)
0(0)
8* (16)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11-20
246* (129)
0(0)
0(0)
136* (124)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
173* (126)
40* (36)
0(0)
239* (128)
0(0)
0(0)
0(0)
198* (127)
0(0)
0(0)
164* (125)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
>20
191* (125)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
162* (124)
0(0)
176* (125)
0(0)
0(0)
0(0)
4* (11)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
All Facilities
with 2 or More
Co-occurrences
1,318(238)
207* (127)
173* (126)
773 (172)
0(0)
0(0)
129* (125)
621 (169)
13* (20)
169* (126)
165* (126)
8* (16)
1,033 (191)
1,700 (328)
259 (129)
1,118(192)
1,338 (228)
0(0)
8* (16)
1,039 (187)
207* (128)
416(159)
944 (183)
0(0)
558 (126)
21* (26)
8* (16)
0(0)
190* (126)
a For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based. Cancer or leukemia
for carcinogenic chemicals. See Appendix C for discussion of health benchmarks.
b A facility-level co-occurrence is defined as when two or more chemicals with a common target health effect occur
within or across impoundments at a single facility.
0 Estimate for population of facilities with surface impoundments having constituents or pH of concern. Value in
parentheses is standard error. Asterisk (*) indicates estimates that may not be reliable because of a large relative
standard error (see Appendix A.5 for a discussion of standard error estimates).
Lists of the co-occurring chemicals at each facility in the sample are provided in Appendix B.
B-179
-------
March 26, 2001
Appendix B
Table B-36. Impoundment-Level Co-occurance of Chemicals in Wastewater by
Human Health Effect (Risk Input Database)
Estimated Number of Impoundments with Co-occurrencesb in Wastewater'
Target Health
Effect a
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/Across Impoundments
2-3
1,004 (223)
243* (155)
72* (44)
2,144(280)
0(0)
0(0)
4* (11)
1,763 (375)
52* (37)
116(55)
86* (47)
42* (33)
3,293 (656)
3,418 (568)
189 (70)
2,798 (307)
2,403 (537)
0(0)
42* (33)
3,578 (257)
359 (160)
257 (82)
2,116(367)
0(0)
1,415 (258)
55* (38)
50* (36)
0(0)
149 (62)
4-6
959(153)
114(55)
102* (52)
811(168)
0(0)
0(0)
0(0)
181 (69)
0(0)
42* (33)
46* (35)
0(0)
429 (172)
1,887 (264)
0(0)
924 (150)
359 (96)
0(0)
0(0)
747 (257)
0(0)
102* (52)
793 (140)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
7-10
709 (278)
0(0)
0(0)
157 (64)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
101* (52)
496 (173)
0(0)
486* (327)
105 (53)
0(0)
0(0)
665 (156)
0(0)
0(0)
17* (21)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11-20
326 (160)
0(0)
0(0)
50* (36)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
131(59)
122 (57)
0(0)
389(188)
0(0)
0(0)
0(0)
191(71)
0(0)
0(0)
131 (59)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
>20
175 (67)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
114(55)
0(0)
148 (62)
0(0)
0(0)
0(0)
4* (11)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
All
Impoundments
with 2 or More
Co-occurrences
3,172 (577)
358(158)
175 (67)
3,161 (361)
0(0)
0(0)
4* (11)
1,944 (391)
52* (37)
158 (64)
132 (59)
42* (33)
3,954 (771)
6,038 (824)
189 (70)
4,744 (492)
2,868 (555)
0(0)
42* (33)
5,186 (444)
359 (160)
360 (96)
3,057 (408)
0(0)
1,415 (258)
55* (38)
50* (36)
0(0)
149 (62)
a For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based. Cancer or leukemia
for carcinogenic chemicals. See Appendix C for discussion of health benchmarks.
b An impoundment-level co-occurrence is defined as when two or more chemicals with a common target health
effect occur within or across a single impoundment.
0 Estimate for population of imppundments having constituents or pH of concern. Value in parentheses is standard
error. Asterisk (*) indicates estimates that may not be reliable because of a large relative standard error (see
Appendix A.5 for a discussion of standard error estimates).
B-180
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March 26, 2001
Appendix B
Table B-37. Impoundment-Level Co-occurance of Chemicals in Sludge by
Human Health Effect (Risk Input Database)
Estimated Number of Impoundments with Co-occurrencesb in Sludgec
Target Health
Effect a
Cancer
Adrenal
Bladder
Body weight
Brain
Cardiovascular
Death
Developmental
Eyes
Forestomach
Gastrointestinal
General
Hematological
Kidney
Leukemia
Liver
Lung
Mammary
Nasal cavity
Neurological
Organ weight
Reproductive
Respiratory
Respiratory tract
Skin
Spleen
Stomach
Thyroid
Vascular
Number of Chemicals Co-occurring Within/Across Impoundments
2-3
930 (247)
229* (124)
53* (36)
885(211)
0(0)
0(0)
124* (121)
1,372 (302)
47* (33)
208* (123)
189* (122)
37* (30)
1,664 (229)
2,134(358)
349 (166)
1,421 (252)
2,087 (448)
0(0)
37* (30)
1,630 (243)
429 (165)
575* (296)
888 (185)
0(0)
1,265 (185)
49* (34)
37* (30)
0(0)
277 (124)
4-6
816(135)
214* (122)
207* (122)
605 (144)
0(0)
0(0)
0(0)
306 (127)
0(0)
37* (30)
41* (31)
0(0)
667 (284)
1,103 (224)
0(0)
661 (123)
453 (138)
0(0)
0(0)
389 (104)
0(0)
92* (47)
900 (221)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
7-10
267 (79)
0(0)
0(0)
184 (66)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
94* (47)
702 (289)
0(0)
168* (122)
87* (46)
0(0)
0(0)
771 (280)
0(0)
0(0)
15* (19)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
11-20
568 (278)
0(0)
0(0)
165* (121)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
230* (123)
125 (55)
0(0)
487 (197)
0(0)
0(0)
0(0)
287 (127)
0(0)
0(0)
222* (123)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
>20
280 (126)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
214* (122)
0(0)
241* (123)
0(0)
0(0)
0(0)
4* (9)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
0(0)
All
Impoundments
with 2 or More
Co-occurrences
2,861 (493)
443 (166)
260 (124)
1,838 (413)
0(0)
0(0)
124* (121)
1,677 (382)
47* (33)
246* (124)
230* (123)
37* (30)
2,654 (565)
4,278 (620)
349 (166)
2,978 (425)
2,627 (541)
0(0)
37* (30)
3,081 (536)
429 (165)
667 (298)
2,024 (421)
0(0)
1,265 (185)
49* (34)
37* (30)
0(0)
277 (124)
a For noncarcinogenic chemicals, target organ on which health benchmark (e.g., RfD) is based. Cancer or leukemia
for carcinogenic chemicals. See Appendix C for discussion of health benchmarks.
b An impoundment-level co-occurrence is defined as when two or more chemicals with a common target health
effect occur within or across a single impoundment.
0 Estimate for population of imppundments having constituents or pH of concern. Value in parentheses is standard
error. Asterisk (*) indicates estimates that may not be reliable because of a large relative standard error (see
Appendix A.5 for a discussion of standard error estimates).
B-181
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March 26, 2001
Appendix B
Table B-38. 50th and 90th Percentile Wastewater Concentrations in
Impoundment for Selected Chemicals
Chemical
Arsenic
(7440-38-2)
Barium
(7440-39-3)
Benzene
(71-43-2)
Cadmium
(7440-43-9)
Chloroform
(67-66-3)
Chromium
(7440-47-3)
Cresol
(1319-77-3)
Lead
(7439-92-1)
Mercury
(7439-97-6)
Methyl Ethyl
Ketone
(78-93-3)
Selenium
(7782-49-2)
Screening Factor a
Carcinogen
(mg/L)
6.6E-04
NA
1.8E-02
NA
1.6E-01
NA
NA
NA
NA
NA
NA
Noncarcinogen
(mg/L)
6.9E-03
1.6E+00
NA
1.2E-02
2.3E-01
6.9E-02
1.2E+00
NA
6.9E-03
1.4E+01
1.2E-01
TC
Limit "
(mg/L)
5.0
100.0
0.5
1.0
6.0
5.0
200.0
5.0
0.2
200.0
1.0
Wastewater Concentrations in Impoundment (mg/L)
Survey Data
50th
Percentile
9.0E-03
1.3E-01
1.1E-02
3.0E-03
4.0E-03
8.0E-03
1.2E-02
9.0E-03
6.0E-05
3.2E-01
5.5E-03
90th
Percentile
2.1E-02
8.8E-01
1.6E-02
8.4E-03
2.8E+00
4.8E-02
3.1E-02
4.0E-02
3.8E-03
1.4E+00
6.0E-02
Risk Input Data
50th
Percentile
9.0E-03
3.0E-01
5.3E-03
3.1E-03
5.0E-03
1.6E-02
l.OE-02
2.0E-02
2.0E-04
1.4E+00
l.OE-02
90th
Percentile
l.OE+00
8.4E+00
l.OE-01
1.5E-01
2.8E+00
4.6E-01
1.1E-01
4.0E-01
6.0E-03
2.1E+00
7.5E-01
a Human health based screening level (HBL) for drinking water (see Appendix C, Attachment 3).
b Source: RCRA §261.24, Table 1 - Maximum Concentration of Contaminants for the Toxicity Characteristic.
B-182
-------
March 26, 2001
Appendix B
c
0>
.2
E
600
500
400
300
200
100
0
Arsenic - Influent (All Impoundments)
HBL - carcinogen
(0.000657 mg/L)
1 !•!•!• I
HBL - noncarcinogen
(0.00693 mg/L)
,11
!• !• I !•!•!• I I-™H h
TC Limit
(5 mg/L)
f™H !• !•!•!• I h™4-
-J Z3
Lnt-CNico-^-mcDr— oocDT-tNcO'srun
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O
LnLnooo
Wastewater Concentration (mg/L)
Arsenic - Effluent (All Impoundments)
c
0)
|
13
O
E"
l
E
600
500
400
300
200
100
0
HBL - carcinogen
0.000657 mg/L)
HBL - noncarcinogen
(0.00693 mg/L)
.1. .•.!.•
TC Limit
(5 mg/L)
9 O
ooooooooo
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-l. Arsenic influent and effluent wastewater concentrations.
B-183
-------
March 26, 2001
Appendix B
Arsenic - Influent (Never Characteristic)
0
"
400
350
300
250
200
HBL - carcinogen
. (0.000657 mg/L)
0
JD
1
100
50
0
4-™H 1 h
+™H 1 h
H h
HBL - noncarcinogen
(0.00693 mg/L)
H h™H h
TC Limit
(5 mg/L)
H 1 I-™H !• !• I H
— ) O LO
CM CO
OOOOOOOOOOOOOOO
O O O O O O
000000000
0-0-0-0-0-
>-'>-'
Wastewater Concentration (mg/L)
Arsenic - Influent (Decharacterized)
400
350
mpoundment
IV) IV) W
o en o
o o o
£1
1 100
50
HBL - carcinogen
(0.000657 mg/L)
i ^^ i ^^ i ^^ i
1 !•!•!• I
HBL - noncarcinogen
(0.00693 mg/L)
• ill
f™H 1 !•!•!• I h
-+-
—i —join-*— c\ico^u">(Di--oocr>T—
Q ;=/ ooooooooooooooo
rQ ^"^ O C5 CD G5 CD C5 C5 CD CD CD —j
°- qddcicicicicicici
o
TC Limit
(5 mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-2. Arsenic influent wastewater concentrations by decharacterization status
B-184
-------
March 26, 2001
Appendix B
Arsenic - In Impoundment (Survey Data)
c
Q)
E
T3
O
Q.
E
800
700
600
500
400
HBL - carcinogen
- (0.000657 mg/L)
55 30°
n
I 200
z
100
HBL - noncarcinogen
(0.00693 mg/L)
i.l.l. I
1
TC Limit
(5 mg/L)
1 • I • I • I
I • I
M H
=3
a
Q.
ooooooooooppppp
LT> O O O
oppppppppp
ddddddddd
CD CD CD CD CD
O O
Wastewater Concentration (mg/L)
Arsenic - In Impoundment (Risk Input Data)
800
700
§ 600
E
§ 500
o
E" 400
fe 30°
&
I 200
100
HBL - carcinogen
- (0.000657 mg/L)
HBL - noncarcinogen
(0.00693 mg/L)
TC Limit
(5 mg/L)
I
I MM
Q g
m cC
ooooooooooppppp
d d d d d
oppppppppp
o'do'ciddcidd
o o o
1- OJ ^
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-3. Arsenic wastewater concentrations in impoundment
(survey data vs. risk input data).
B-185
-------
March 26, 2001
Appendix B
2500
^ 2000
CD
E
T3
§ 1500
CL
E
CD
_Q
E
I!
1000
500
2500
2000
CD
2 1500
1000
CD
500
Barium - Influent (All Impoundments)
HBL - noncarcinogen
(1.62 mg/L)
TC Limit
(100 mg/L)
c\l CO
O O O O
t- CM CD O
CM
Wastewater Concentration (mg/L)
Barium - Effluent (All Impoundments)
HBL - noncarcinogen
(1.62 mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-4. Barium influent and effluent wastewater concentrations
B-186
-------
March 26, 2001
Appendix B
1600
1400
en
1 1200
E
§ 1000
o
E 800
Barium - Influent (Never Characteristic)
_Q
§
600
400
200
0
HBL - noncarcinogen
(1.62 mg/L)
CM CO
Wastewater Concentration (mg/L)
Barium - Influent (Decharacterized)
E
§
o
E
CD
_Q
E
D
1600
1400
1200
1000
800
600
400
200
HBL - noncarcinogen
(1.62 mg/L)
CM CO
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
TC Limit
(100 mg/L)
0000
t- CM CD O
CM
TC Limit
(100 mg/L)
o o o o
t- CM CD O
CM
Figure B-5. Barium influent wastewater concentrations by decharacterization status.
B-187
-------
March 26, 2001
Appendix B
2500
2000
CD
5 1500
1000
CD
500
2500
^ 2000
CD
E
T3
§ 1500
CL
E
1000
o>
_Q
E
•
500
Barium - In Impoundment (Survey Data)
HBL - noncarcinogen
(1.62 mg/L)
TC Limit
(100 mg/L)
Wastewater Concentration (mg/L)
Barium - In Impoundment (Risk Input Data)
HBL - noncarcinogen
(1.62 mg/L)
TC Limit
(100 mg/L)
O O O O
t- CM CD O
CM
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-6. Barium wastewater concentrations in impoundment
(survey data vs. risk input data)
B-188
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March 26, 2001
Appendix B
Benzene - Influent (All Impoundments)
900
HBL - noncarcinogen
(0.0179 mg/L)
900
800
w
c 700
CD
600
_ 500
E
•t 400
300
200
100
0
TC Limit
(0.5 mg/L)
Wastewater Concentration (mg/L)
Benzene - Effluent (All Impoundments)
HBL - noncarcinogen
(0.0179 mg/L)
TC Limit
(0.5 mg/L)
CM
CD
ro
CD
in
CD
CM
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-7. Benzene influent and effluent wastewater concentrations.
B-189
-------
March 26, 2001
Appendix B
900
800
w
c 700
o>
| 600
g.500
E
•5 400
Jl 300
E
^ 200
100
0
900
800
I 700
0)
| 600
8. 500
| 400
Jl 300
Benzene - Influent (Never Characteristic)
HBL - noncarcinogen
(0.0179 mg/L)
TC Limit
(0.5 mg/L)
if) T-
0 o
O
C\l
O
CO
o
Wastewater Concentration (mg/L)
Benzene - Influent (Decharacterized)
HBL - noncarcinogen
(0.0179 mg/L)
TC Limit
(0.5 mg/L)
CO
O
in
o
T- (M
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-8. Benzene influent wastewater concentrations by decharacterization status.
B-190
-------
March 26, 2001
Appendix B
o>
900
800
700
600
. 500
E
H- 400
300
200
100
0
900
800
V)
c 700
0)
600
. 500
E
>*- 400
300
200
100
0
Benzene - In Impoundment (Survey Data)
HBL - noncarcinogen
(0.0179 mg/L)
TC Limit
(0.5 mg/L)
If) T-
0 O
o
CM
O
CO
o
in
o
Wastewater Concentration (mg/L)
Benzene - In Impoundment (Risk Input Data)
HBL - noncarcinogen
(0.0179 mg/L)
TC Limit
(0.5 mg/L)
CM
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-9. Benzene wastewater concentrations in impoundment
(survey data vs. risk input data).
B-191
-------
March 26, 2001
Appendix B
Cadmium - Influent (All Impoundments)
1200
1000
"c
CD
CD
800
E 600
400
200
HBL - noncarcinogen
(0.0115 mg/L)
TC Limit
(1 mg/L)
Wastewater Concentration (mg/L)
Cadmium - Effluent (All Impoundments)
1200
1000
c
CD
E
T3
I!
o
CL
E
CD
_Q
E
•
800
600
400
200
HBL - noncarcinogen
(0.0115 mg/L)
TC Limit
(1 mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-10. Cadmium influent and effluent wastewater concentrations
B-192
-------
March 26, 2001
Appendix B
Cadmium - Influent (Never Characteristic)
500
450
| 400
Q)
E 350
§ 30°
Q.
E
_ 250
° 200
o
f 150
i 100
50
0
HBL - noncarcinogen
(0.0115 mg/L)
TC Limit
(1 mg/L)
LT>
O
O
O
O
O
O
O
O
O
O
Wastewater Concentration (mg/L)
Cadmium - Influent (Decharacterized)
500
450
| 400
0)
E 350
§ 300
Q.
E 250
CD
E
n
200
150
100
50
HBL - noncarcinogen
(0.0115 mg/L)
TC Limit
(1 mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-ll. Cadmium influent wastewater concentrations by decharacterization status.
B-193
-------
March 26, 2001
Appendix B
CD
CD
CD
_Q
E
Cadmium - In Impoundment (Survey Data)
1200
w 1000
800
E 600
400
200
HBL - noncarcinogen
(0.0115 mg/L)
o
o
o
p
o
o
o
p
o
TC Limit
(1 mg/L)
Wastewater Concentration (mg/L)
Cadmium - In Impoundment (Risk Input Data)
1200
„ 1000
CD
| 800
o
E" 600
400
200
HBL - noncarcinogen
(0.0115 mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-12.Cadium wastewater concentrations in impoundment
(survey data vs. risk input data).
B-194
-------
March 26, 2001
Appendix B
700
600
c
E 500
c
o_ 400
E"
-5 300
o
E 200
100
0
Chloroform -
-
- _
II
1
1
Q F< OOOOOO
03 jr* OOOOOO
°. d d d d d
o
Influent (All Impoundments)
HBL - carcinogen
(0.162 mg/L)
• 1*M^
o o o o o 5 d
00000
TC Limit
(6 mg/L)
HBL-
noncarcinogen
(0.231 mg/L)
odd g
Wastewater Concentration (mg/L)
700
Impoundments
•P>. en cn
o o o
o o o
•5 300
CD
E 200
z
100
0
Chloroform -
II
• 1
Q^ OOOOOO
S iT5 OOOOOO
P d d d d d
o
Effluent (All Impoundments)
HBL - carcinogen
(0.162 mg/L)
O O O O O o' o'
d d d d d
TC Limit
(6 mg/L)
HBL-
noncarcinogen
(0.231 mg/L)
CO ^~ U") ^ — CO CD C5
odd g
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-13. Chloroform influent and effluent wastewater concentrations.
B-195
-------
March 26, 2001
Appendix B
700
600
Impoundments
•P>. en
o o
o o
"5 300
CD
E 200
100
0
Chloroform
-
-
-
I I ^^ I I ^^ I I
Q 2 00000
Q3 fr O O O O O
P d d d d
0
- Influent (Never
Characteristic)
HBL - carcinogen TC Limit
(0.162
i ^^ i ^^ i ^^ i ^^ i ^™ i
O O O O O O
P d d d d d
0
Wastewater Concentration
700
600
-J2
| 500
T3
C
o 400
E
•5 300
CD
E 200
100
0
Chloroform
-
1
1 •) f~l ]_{") -^ — £NJ £V} ^-
Q Q O O O O O
°- P d d d d
o
mg/L) (6 mg/L)
HBL-
noncarcinogen
(0.231 mg/L)
I I ^^ I I I I I I
O O O O O g
(mg/L)
- Influent (Decharacterized)
HBL - carcinogen TC Limit
(0.162
LO T — CNl CO "^1" W~)
o o o o o o
d
Wastewater Concentration
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
mg/L) (6 mg/L)
HBL-
noncarcinogen
(0.231 mg/L)
^~ CNl CO ^" l^) ^~ CO CO f — i
(mg/L)
Figure B-14. Chloroform influent wastewater concentrations by decharacterization status
B-196
-------
March 26, 2001
Appendix B
Chloroform - In Impoundment (Survey Data)
700
600
| 500
T3
o 400
E
-5 300
!_
0
E 200
100
HBL - carcinogen
(0.162 mg/L)
I !• I"
H H
H [•[•[•[•M
4-1
TC Limit
(6 mg/L)
HBL-
noncarcinogen
(0.231 mg/L)
-+-
Q
DO
Q ooooooqqqqq^dddd
°~ P d d d d d
o
co CD o
o
Wastewater Concentration (mg/L)
Chloroform - In Impoundment (Risk Input Data)
HBL - carcinogen
(0.162 mg/L)
HBL-
noncarcinogen
(0.231 mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-15. Chloroform wastewater concentrations in impoundment
(survey data vs. risk input data).
B-197
-------
March 26, 2001
Appendix B
•\cr\r\ .
Number of Impoundments
ro.p>.CBoooro-P>.c
oooooooc
3OOOOOOOC
U
•\Kr\r\
IOUU
1400
1 1200
E
§ 1000
o
I" 800
"5
55 600
JD
1 400
200
Chromium - Influent (All Impoundments)
HBL - noncarcinogen TC Limit
(0.0693 mg/L) (5 mg/L)
I ~) O T — T — CM CO ^" LO CD I" — OO O} ^ — CM CO ^" LO ^ — U") LO O O
Q ;=* OOOOOOOOOOOOOOOQQ i-o
CQ fr OOOOOOOOOOQQQQQ^^ CM
Pddddddddd
o
Wastewater Concentration (mg/L)
Chromium - Effluent (All Impoundments)
HBL - noncarcinogen TC Limit
(0.0693 mg/L) (5 mg/L)
Q 2 OOOOOOOOOOOOOOOQQ T-O
mjr OOOOOOOOOOQQQQQ^^ CM
"- Pddddddddd
0
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-16. Chromium influent and effluent wastewater concentrations.
B-198
-------
March 26, 2001
Appendix B
co
c
CD
E
T3
C
3
0
CL
E
"5
CD
E
1200
1000
800
600
400
200
0
~
_
-
-
1, > <
_l -) 0
Q p?
m Q"
^^
Chromium -
i i i i i
T- T- CM CO ^T
O O O O O
o o o o o
P d d d d
o
Influent (Never Characteristic)
HBL - noncarcinogen TC Limit
(0.0693 mg/L) (5 mg/L)
i — i i ^^ i i ^^ i ^^ i ^™ i i ^^ i ^™ i ^™ i i ^*
iocoi-~-ooa>t-CNcO"3-LO-!-Loiooo
OOOOOOOOOOoo T- O
00000,-Joooo1-''-' CM
o o o o o
Wastewater Concentration (mg/L)
co
c
CD
E
T3
C
3
O
CL
E
M—
Number o
1000
800
600
400
200
~
_
-
ll
_i -> o
Q p?
CO rT
^^
Chromium
T- T- CM CO TT
O O O O O
00000
P d d d d
o
- Influent (Decharacterized)
HBL - noncarcinogen TC Limit
(0.0693 mg/L) (5 mg/L)
lOC0h-OOCDi-CMrO^J-lO-<-LOLOOO
OOOOOOOOOOoo T- o
oooooodddd ^
d d d d d
Wastewater Concentration (mg/L)
BDL = Below
detection limit
PQU = Present quantity unknown
HBL = Health
TC = Toxicity
based limit
characteristic
Figure B-17. Chromium influent wastewater concentrations by decharacterization status
B-199
-------
March 26, 2001
Appendix B
1400
co
1 1200
E
§ 1000
o
Q.
E 800
^ 600
.Q
1 400
200
•\Kr\r\
IDUU
1400
1 1200
£
T3
§ 1000
o
Q.
E 800
"o
55 600
JD
1 400
200
-
1
i
Q
—
_
-
-
-
-
Q
BDL
PQU
HBL
TC =
Chromium - In Impoundment (Survey Data)
HBL - noncarcinogen TC Limit
(0.0693 mg/L) (5 mg/L)
— lO-s— T— CNCO'^J'LOCDI^-OOOt— CNICO'^]'tO^~U^ir)OO
;=* ooooooooooooooo,-;,-; t- o
0 OOOOOOOOOOooooo00 CM
Pddddddddd
0
Wastewater Concentration (mg/L)
Chromium - In Impoundment (Risk Input Data)
HBL - noncarcinogen TC Limit
(0.0693 mg/L) (5 mg/L)
_
_•_ ill. l.lll.l.ll _
<-< OOOOOOOOOOOOOOOocJ T- o
v ooooooooooo'dddd ^
Pooooooooo
0
Wastewater Concentration (mg/L)
= Below detection limit
= Present quantity unknown
= Health based limit
Toxicity characteristic
Figure B-18. Chromium wastewater concentrations in impoundment
(survey data vs. risk input data)
B-200
-------
March 26, 2001
Appendix B
Cresol - Influent (All Impoundments)
450
400
I 350
Q)
| 300
8.250
E
"5 20°
% 150
E
^ 100
50
0
HBL - noncarcinogen
(1.15 mg/L)
TC Limit
(200 mg/L)
in
O
p
O
CD
O
O
O
O
O
O
Wastewater Concentration (mg/L)
Cresol - Effluent (All Impoundments)
HBL - noncarcinogen
(1.15 mg/L)
TC Limit
(200 mg/L)
in
O
O
O
O
o
O
co
O
O
o>
O
O
p
O
in
p
O
in
d
CM
O
O
CM
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-19. Cresol influent and effluent wastewater concentrations.
B-201
-------
March 26, 2001
Appendix B
A £n
4OU
400
1 350
0>
| 300
8.250
E
•5 20°
Jl 150
E
^ 100
50
400
1 350
o>
| 300
8.250
£
•s 20°
| 150
E
i 100
50
Cresol - Influent (Never Characteristic)
HBL - noncarcinogen
(1.15 mg/L)
TC Limit
(200 mg/L)
-
-
-
-
Q Qoooooooooqq^d °
CLddddddddd
Wastewater Concentration (mg/L)
Cresol - Influent (Decharacterized)
^H HBL - noncarcinogen
• (1.15 mg/L)
H TC Limit
• (200 mg/L)
1
- I
1
- I
||
^^H i ^^H i i i ^^^i i i i i i i i i BB i ^^H i ^^^ i i
1 — ) ^ — CN1 CO ^3" LO CD r~~- CO O^ "^ — LO ^ — LO CM G3
Q QOOOOOOOOOOOQQ O
^ddddddddd
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-20. Cresol influent wastewater concentrations by decharacterization status.
B-202
-------
March 26, 2001
Appendix B
Cresol - In Impoundment (Survey Data)
450
400
c 350
0>
300
.
200
150
100
50
0
HBL - noncarcinogen
(1.15 mg/L)
TC Limit
(200 mg/L)
^m •
o
p
0
CM
O
O
0
CO
O
o
o
p
d
o
p
d
CD
o
p
o'
r--
o
o
CO
o
p
d
o
p
o
p
o'
p
o'
in
d
o
o
CM
Wastewater Concentration (mg/L)
Cresol - In Impoundment (Risk Input Data)
450
400
w
c 350
o
300
8.250
Z 200
150
100
50
HBL - noncarcinogen
(1.15 mg/L)
TC Limit
(200 mg/L)
Q
00
O
Q_
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-21. Cresol wastewater concentrations in impoundment
(survey data vs. risk input data).
B-203
-------
March 26, 2001
Appendix B
onnn .
zuuu
1800
£ 1600
CD
E 1400
T3
§ 1200
E" 1000
° 800
CD
H 600
z 400
200
onnn
zuuu
1800
| 1600
CD
E 1400
T3
§ 1200
1" 1000
° 800
CD
-| 600
z 400
200
Lead - Influent (All Impoundments)
TC
Limit
(5 mg/L)
_i ^oin-<-r\icy}^iooh-rocn-!-r\ico^fu~>T-uoi-r>oo
Q rx OOOOOOOOOOOOOOOoo t- CM
m 0 oooooooooocjcjcjcjcju(-'
Hod d d d d d d d
o
Wastewater Concentration (mg/L)
Lead - Effluent (All Impoundments)
TC
Limit
(5 mg/L)
_i ^OLnt-
-------
March 26, 2001
Appendix B
Lead - Influent (Never Characteristic)
1800
1600
in
c 1400
CD
-o 1200
c
D
8. 1000
E
M- 800
o
jjj 600
E
^ 400
200
-
-
_
-
-
-
d Q ooooooooooqqq
°~ Pddddddddd
o
Wastewater Concentration (mg/L)
TC
Limit
(5 mg/L)
i i i i i ^^ i i
° ° o o ^ CNJ
d d
Lead - Influent (Decharacterized)
1800
1600
•E 1400
0)
•o 1200
c
D
8. 1000
E
^ 800
E 600
E
^_ 400
200
-
_
_
-
-
-
Q Q ooooooooooppp
°- Pddddddddc)
0
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
TC = Toxicity characteristic
TC
Limit
(5 mg/L)
^~ uo ^ — '-O LO c? n?
° ° d d -^ CM
d d
Figure B-23. Lead influent wastewater concentrations by decharacterization status.
B-205
-------
March 26, 2001
Appendix B
ocnn
Number of Impoundments
_>._>. ro iv
en o en o e
o o o o c
D O O O O C
VJ
ocnn
Number of Impoundments
_>._>. ro iv
en o en o e
o o o o c
D O O O O C
Lead - In Impoundment (Survey Data)
TC
Limit
(5 mg/L)
Q Q OOOOOOOOOOOOOOO^O •'-CM
°~ Pooooooooo
o
Wastewater Concentration (mg/L)
Lead - In Impoundment (Risk Input Data)
TC
Limit
(5 mg/L)
t ^^ f~^ LO ^ — CM co ^f LO co r^*- co o^ ^ — CM co ^~ LO ^^ LO LO G} c^
Q Q OOOOOOOOOOOOOOOQQ t- CM
°~ °. ooooooooo
0
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
TC = Toxicity characteristic
Figure B-24. Lead wastewater concentrations in impoundment
(survey data vs. risk input data).
B-206
-------
March 26, 2001
Appendix B
Mercury - Influent (All Impoundments)
600
500
400
o
E 300
200
100
0
HBL - noncarcinogen
(0.00693 mg/L)
TC Limit
(0.2 mg/L)
Wastewater Concentration (mg/L)
Mercury- Effluent (All Impoundments)
600
w 500
"c
0)
| 400
13
O
E 300
200
100
HBL - noncarcinogen
(0.00693 mg/L)
TC Limit
(0.2 mg/L)
CNI
O
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-25. Mercury influent and effluent wastewater concentrations
B-207
-------
March 26, 2001
Appendix B
Mercury - Influent (Never Characteristic)
400
350
300
E
T3
§ 250
o
" 200
5
JD
I
100
50
HBL - noncarcinogen
(0.00693 mg/L)
TC Limit
(0.2 mg/L)
Wastewater Concentration (mg/L)
Mercury - Influent (Decharacterized)
400
350 -
HBL - noncarcinogen
(0.00693 mg/L)
TC Limit
(0.2 mg/L)
CNI
O
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-26. Mercury influent wastewater concentrations by decharacterization status
B-208
-------
March 26, 2001
Appendix B
Mercury - In Impoundment (Survey Data)
600
500
400
o
E 300
200
100
HBL - noncarcinogen
(0.00693 mg/L)
TC Limit
(0.2 mg/L)
Wastewater Concentration (mg/L)
Mercury - In Impoundment (Risk Input Data)
600
500
0)
E
T3
13
O
E
400
300
200
100
HBL - noncarcinogen
(0.00693 mg/L)
TC Limit
(0.2 mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-27. Mercury wastewater concentrations in impoundment
(survey data vs. risk input data).
B-209
-------
March 26, 2001
Appendix B
450
400
c 350
0)
300
200
150
100
50
0
450
400
I 350
CD
| 300
I 250
I 200
1 150
E
^ 100
50
0
Methyl Ethyl Ketone - Influent (All Impoundments)
HBL - noncarcinogen
(13.9 mg/L)
TC
(200 I
Limit
mg/L)
Wastewater Concentration (mg/L)
Methyl Ethyl Ketone - Effluent (All Impoundments)
HBL - noncarcinogen
(13.9 mg/L)
TC
(200 I
Limit
mg/L)
LO
O
CM
O
O
CM
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-28. Methyl ethyl ketone (MEK) influent and effluent wastewater concentrations.
B-210
-------
March 26, 2001
Appendix B
CD
450
400
350
300
8. 250
E
"5 20°
! 150
E
^ 100
50
0
450
400
c 350
CD
| 300
I 250
I 200
1 150
E
^ 100
50
0
Methyl Ethyl Ketone - Influent (Never Characteristic)
HBL - noncarcinogen
(13.9mg/L)
TC
(200
Limit
mg/L)
in
o
o
CM
o
o
CM
Wastewater Concentration (mg/L)
Methyl Ethyl Ketone - Influent (Decharacterized)
HBL - noncarcinogen
(13.9 mg/L)
TC
(200
Limit
mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-29. Methyl ethyl ketone (MEK) influent wastewater
concentrations by decharacterization status.
B-211
-------
March 26, 2001
Appendix B
Methyl Ethyl Ketone - In Impoundment (Survey Data)
600
w 500
CD
| 400
o
E 300
200
E
13
100
HBL - noncarcinogen
(13.9 mg/L)
TC
(200
Limit
mg/L)
O
CM
O
O
CM
Wastewater Concentration (mg/L)
Methyl Ethyl Ketone - In Impoundment (Risk Input Data)
600
HBL-
noncarcinogen
(13.9 mg/L)
TC
(200
Limit
mg/L)
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-30. Methyl ethyl ketone (MEK) wastewater concentrations in
impoundment (survey data vs. risk input data).
B-212
-------
March 26, 2001
Appendix B
Selenium - Influent (All Impoundments)
900
HBL - noncarcmogen
(0.0115 mg/L)
900
800
V)
c 700
0)
600
. 500
E
>*- 400
300
200
100
O O O
Wastewater Concentration (mg/L)
Selenium - Effluent (All Impoundments)
HBL - noncarcinogen
(0.0115 mg/L)
CM
000
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-31. Selenium influent and effluent wastewater concentrations.
B-213
-------
March 26, 2001
Appendix B
600
500
-o 400
13
O
E" 300
"5
Jl 200
E
Z!
^ 100
600
500
400
13
O
E 300
200
.
E
Z!
100
Selenium - Influent (Never Characteristic)
Wastewater Concentration (mg/L)
Selenium - Influent (Decharacterized)
HBL - noncarcinogen
(0.0115 mg/L)
TC Limit (1mg/L)
CM
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-32. Selenium influent wastewater concentrations by decharacterization status.
B-214
-------
March 26, 2001
Appendix B
Selenium - In Impoundment (Survey Data)
1200
1000
CD
E
T3
D
o
CL
E
CD
_Q
E
I!
800
600
400
200
HBL - noncarcinogen
(0.0115 mg/L)
TC Limit (1mg/L)
c\l
000
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Selenium - In Impoundment (Risk Input Data)
1200
1000
o>
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800
600
400
200
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(0.0115 mg/L)
000
Wastewater Concentration (mg/L)
BDL = Below detection limit
PQU = Present quantity unknown
HBL = Health based limit
TC = Toxicity characteristic
Figure B-33. Selenium wastewater concentrations in impoundment
(survey data versus risk input data).
B-215
-------
Appendix C
Risk Assessment Methodology and Results
-------
-------
March 26, 2001 Table of Contents for Appendix C
Contents
Appendix Page
C. Risk Assessment Methodology and Results C-1
C.I Appendix Overview and Discussion of Results C-l
C.I.I Overview C-2
C.I.2 Phase IA: Preliminary Screen - Human Health C-19
C.I.3 Phase IB: Release Assessment - Human Health C-22
C.I.4 Results of Phase IA and IB - Human Health C-27
C.I.5 Phase IC/H: Risk Modeling - Air Pathway C-27
C.I.6 Phase IC/H: Risk Modeling - Groundwater Pathway C-33
C. 1.7 Phase IC/EL Risk Modeling - Groundwater to Surface
Water Pathway C-38
C. 1.8 Phase IC/EL Indirect Exposure Pathway Assessment - Human
Health C-42
C.I.9 Phase IA: Preliminary Screen - Ecological Risk C-46
C.2 Air Pathway C-51
C.2.1 Methods C-51
C.2.2 Results from Air pathway Analysis C-63
C.3 Direct Exposure Pathway—Groundwater C-65
C.3.1 Numeric Ranking System for Facilities, Impoundments, and
Constituents C-66
C.3.2 Modeling Groundwater Exposure Concentrations C-86
C.3.3 Methods - Exposure/Risk Calculations C-104
C.3.4 Results from Groundwater Pathway Analysis C-109
C.4 Indirect Exposure Pathway Analysis—Groundwater to Surface Water C-l 13
C.4.1 Numeric Ranking of Facilities. C-l 13
C.4.2 Surface Water Screening Modeling C-121
C.5 Indirect Exposure Pathway Analysis: Methodology and Results C-l35
C.5.1 Overview C-135
C.5.2 Technical Approach C-138
C.6 Ecological Screening Assessment C-l59
C.6.1 Overview C-159
C.6.2 Management Goals and Assessment Endpoints C-160
C.6.3 Summary of Approach C-160
C.6.4 Development of Ecological Screening Factors C-163
C.6.5 Screening Procedures C-176
C.6.6 Screening Results C-179
C.7 References C-192
C-iii
-------
March 26, 2001 Table of Contents for Appendix C
Contents (continued)
Attachments
C-l Toxicological Profiles for Selected Chemicals
C-2 Human Health Benchmarks - Data Sources and Assumptions
C-3 Human Health Screening Factors for Preliminary Screening
C-4 Analytical Risk Results Across Pathways - National Estimates
C-5 Procedures for Obtaining Data for IWAIR Emissions Modeling for Surface
Impoundments
C-6 Risk Modeling Results for Air Pathway - Sample Population
C-7 Analytical Results for Air Pathway - National Estimates
C-8 Numeric Ranking of Facilities for Risk Modeling - Groundwater Pathway
C-9 Narrative Summaries of Facility Characteristics Relevant to Groundwater Pathway Risks
C-10 Facility-specific Site Characterization and Data Selection for Risk Modeling
C-l 1 Risk Modeling Results for Groundwater Pathway - Sample Population
C-l2 Analytical Risk Results for Groundwater Pathway - National Estimates
C-l3 Numeric Ranking of Facilities for Risk Modeling - Groundwater to Surface Water
Pathway
C-l4 Screening Modeling Results for Groundwater to Surface Water Pathway - Sample
Population
C-15 Analytical Screening Results of Groundwater-Surf ace Water Pathway - National
Estimates
C-16 Identification of Bioaccumulative Chemicals for Indirect Exposure Pathway Assessment
C-l 7 Ranking of Facilities for Indirect Exposure Pathway Assessment
C-19 Wildlife Species Evaluated in the Screening Ecological Risk Assessment
C-20 Ecological Benchmarks for Wildlife Species
C-21 Ecological Exposure Factors
C-22 Bioaccumulation Factors Used to Calculate Ecological Screening Factors
C-23 Ecological Risk Screening Factors
C-24 Screening Ecological Risk Results - Sample Population
C-25 Analytical Results for Ecological Risk Screening - National Estimates
Due to the volume and format of the information in the attachments, they are reproduced in electronic
form and are available from EPA's RCRA Information Center.
C-iv
-------
March 26, 2001 Appendix C
Appendix C
Risk Assessment Methodology and Results
C.I Appendix Overview and Discussion of Results
The purpose of this appendix is to present the tiered risk assessment methodology
developed by EPA to characterize the risks associated with chemical constituents managed in
surface impoundments considered in this study. This appendix builds on Chapter 3 of the study
report, and provides an in-depth description of the methodology, assumptions, models, data
sources, results, and uncertainties involved in this assessment. As appropriate, this appendix
includes elements of the approach and terminology proposed in the Surface Impoundment Study
Technical Plan for the Human Health and Ecological Risk Assessment (U.S. EPA, 2000c),
referred to hereafter as the Technical Plan.
Appendix C is organized in six major sections. Section C.I provides an overview of the
methodology and a crosswalk between the tiered risk assessment conducted for the Surface
Impoundment Study (SIS) and the two-phased risk assessment approach described in the
Technical Plan. This section begins by summarizing the key results from this analysis and
presents a discussion of key uncertainties that are relevant to any of the pathways for which
quantitative risk results were predicted. In addition to an overall presentation of methods and
results, Appendix C.I presents a methods summary, key results, and a discussion of uncertainty
for each of the three stages of this assessment: preliminary screen, release assessment, and risk
modeling. This first section is organized as follows:
C.I.I Overview
C.I.2 Phase I A: Preliminary Screen - Human Health
C. 1.3 Phase IB: Release Assessment - Human Health
C. 1.4 Results of Phase I A and IB - Human Health
C. 1.5 Phase IC/II: Risk Modeling - Air Pathway
C. 1.6 Phase IC/II: Risk Modeling - Groundwater Pathway
C.I.I Phase IC/II: Risk Modeling - Groundwater to Surface Water Pathway
C. 1.8 Phase IC/II: Indirect Exposure Pathway Assessment - Human Health
C.I.9 Phase IA: Preliminary Screen - Ecological Risk
C. 1.10 Results of Special Interest
The other major sections of Appendix C include
C.2 Air Pathway
C. 3 Groundwater Pathway
C.4 Groundwater to Surface Water Pathway
C. 5 Indirect Exposure Pathway
C. 6 Ecological Risk Screening
C-l
-------
March 26, 2001 Appendix C
The major sections provide a detailed description of the methodology, including assumptions,
input parameters, and data sources, for each pathway. The discussion of key results and
uncertainties for each of these pathways is discussed in Section C.I.I.
C. 1.1 Overview
EPA proposed the Technical Plan for this assessment in February 2000. That Technical
Plan was peer-reviewed and largely implemented in the SIS. However, based on an evaluation
of the peer review comments, and in consideration of the initial sets of risk results from the
screening stages of the analysis, EPA modified the methodology presented in the Technical Plan.
As the assessment strategy evolved, EPA introduced these modifications to address the peer
review comments and to reflect an increasing understanding of the technical risk assessment
issues. This section provides a crosswalk with the technical plan that will allow the reader to
identify features that were implemented largely as presented in the Technical Plan and provides a
full description of the methods not covered by the technical plan but added to the assessment to
better accomplish the goal of characterizing impoundment risks at a national level.
There are two principal differences between the Technical Plan and the tiered risk
assessment methodology used to produce the national risk estimates presented in Chapter 3.
First, EPA determined that the level of resolution offered by the release assessment (referred to
as Phase IB in the Technical Plan) was insufficient to winnow down the number of facilities,
impoundments, and constituents to be evaluated using a multimedia risk model to a reasonable
number (referred to as Phase II in the Technical Plan). EPA decided that uncertainty in the
results from the release assessment could be greatly reduced by conducting additional modeling
using currently available peer-reviewed modeling tools, such as EPA's Composite Model for
Leachate Migration with Transformation Products (EPACMTP). Site-specific data on receptor
locations, surface water flow, and other site characteristics were used as input to the risk models
to predict pathway-specific risks. Second, EPA determined that the 3MRA model (multimedia,
multipathway, multireceptor risk assessment model) selected for Phase n was not sufficiently
developed to provide reliable risk estimates within the timeframe for this study. The 3MRA
model represents the state-of-the-science in multimedia modeling at EPA; however, EPA is
currently evaluating peer review comments on the beta version of that model, and the subsequent
version that addresses those comments would be a much more appropriate tool for this national
assessment. The Phase n multimedia modeling plan was integrated with the prioritization
scheme to identify facilities indirect pathway modeling as described in the Technical Plan
(referred to as Phase 1C). This integration produced a risk modeling approach that made full use
of available site data to rank facilities for additional modeling and used peer-reviewed models to
evaluate facilities that exceeded risk criteria during the release assessment for direct exposure to
groundwater and air and indirect exposure through the groundwater to surface water pathway.
For the assessment of other indirect exposure pathways, EPA developed a series of criteria based
on a variety of data sources (including the survey responses) and created a numeric ranking of
facilities according to their potential for completion of indirect exposure pathways such as the
farm food chain. This integrated approach, referred to in this section as the Phase IC/n approach
for a convenient reference to the Technical Plan, is described in substantial detail in Sections C.2
through C.5 of this appendix. Table C.l-1 provides a crosswalk between
C-2
-------
March 26, 2001
Appendix C
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-------
March 26, 2001 Appendix C
the Technical Plan proposed by EPA and the tiered risk assessment approach described in
Chapter 3.
C. 1.1.1 Methods Summary. As shown in Table C. 1.1, EPA designed an analytical
framework that progressed from precautionary screening stages to more realistic, site-based
modeling using peer-reviewed simulation models. EPA used several different measures of
chronic risk and hazard in the risk assessment. Cancer risks were expressed as individual
lifetime excess probability of cancer; a threshold of 1 in 100,000 was used as the criteria for
determining whether a constituent posed a risk of concern. The hazard associated with exposure
to noncancer constituents was measured using a hazard quotient (HQ). The HQ is the ratio of the
estimated exposure concentration to an EPA reference dose (RfD) for ingestion or reference
concentration (RfC) for inhalation. RfDs and RfCs are threshold measures of hazard that are set
at a level that EPA has estimated will not result in adverse effects in humans. The human health
threats associated with surface water contamination were evaluated using ratios of estimated
surface water concentrations to ambient water quality criteria for human health (HH-AWQC).
The screening stages referred to in the technical plan as Phase IA and Phase IB, were based on
clear science decision rules related to threshold concentrations of potential concern and low
likelihood of exposures. These decision rules allowed EPA to screen out those constituents,
impoundments, and facilities presenting negligible potential risks and to focus the risk modeling
efforts on those facilities that may present higher potential risks. EPA used risk criteria of 10"5
for carcinogenic risk and HI = 1 for noncarcinogenic risk throughout the analysis. In this report,
these stages are referred to as "preliminary screening" and "release assessment," respectively, to
provide the reader with more descriptive terms for the risk assessment steps.
The human health risk screening of direct pathways consisted of a staged analysis
described as a preliminary screen and release assessment. These stages can be summarized as
follows:
• The preliminary screen (Phase IA) compared reported constituent concentrations
in surface impoundments to concentrations protective of human health (called
human health screening factors) for the air pathway and the groundwater pathway.
This stage is described in detail in Section C.I.2 of this appendix.
• The release assessment (Phase IB) estimated human health risk levels based on
exposure concentrations predicted using screening-level models for the air
pathway, the groundwater pathway, and the groundwater to surface water
pathway. The Phase IB risk screening was only performed for constituents not
eliminated from further evaluation based on Phase IA. This stage is described in
detail in Section C.I.3 of this appendix.
The human health risk screening of the groundwater to surface water pathway also
consisted of a staged analysis described as a preliminary screen and release assessment. Because
this pathway analysis was not discussed in the Technical Plan, it is described in Section C.4 of
this appendix.
C-5
-------
March 26, 2001 Appendix C
• The preliminary screen (Phase IA) compared reported constituent concentrations
in surface impoundments to ambient water quality criteria developed for the
protection of human health from ingestion of contaminated aquatic organisms and
drinking water.
• The release assessment (Phase IB) estimated human health risk levels based on
exposure concentrations predicted using screening-level models for the air
pathway, the groundwater pathway, and the groundwater to surface water
pathway. The Phase IB risk screening was only performed for constituents not
eliminated from further evaluation based on Phase IA.
In addition to screening direct exposure pathways and the groundwater to surface water
pathway, the human health risk screening also involved an assessment of the potential for other
indirect exposure pathways to be completed at facilities that manage bioaccumulative chemical
constituents. This screening assessment was qualitative and integrated information on site
physiography, potential receptors, and impoundment characteristics into a numeric framework to
rank facilities according to their potential for concern for indirect exposure. This methodology is
based on Phase 1C in the Technical Plan. It includes chemical-specific evaluations for
bioaccumulative potential and a ranking scheme that takes full advantage of several data sources,
including the survey responses, geographic information system (GIS) tools, and results from the
Phase IB screening analysis. This methodology also borrows from Phase n of the Technical Plan
in that it seeks to quantify the potential for indirect exposures at the facility level using an array
of explicit criteria. Section C.5 of this appendix provides a complete discussion of the methods
developed for this study to evaluate indirect pathways.
The ecological risk screening consisted of a single stage that parallels the human health
Phase IA screening of direct pathways for noncancer chemicals:
• The preliminary screen (Phase I) compared reported constituent concentrations to
concentrations protective of ecological receptors in freshwater aquatic, wetland,
and terrestrial habitats, (called ecological screening factors). Exposure pathways
included direct ingestion of contaminated plants, prey, and media, as well as direct
contact with a contaminated medium for certain types of receptors such as soil
biota. This assessment is presented in detail in Section C.6 of this appendix.
Based on the results of the release assessment, the human health risk modeling of direct
pathways and surface water was conducted using peer-reviewed models, such as EPACMTP to
develop site-based risk estimates for the air, groundwater, and groundwater to surface water
pathways.1 For the groundwater and groundwater to surface water pathways, EPA determined
that the screening risk results were not sufficient justification to perform risk modeling. In many
instances, the site characteristics did not support the completion of the exposure pathway. To
identify those sites appropriate for risk modeling, EPA developed a series of criteria to rank
1 The surface water modeling is considered a screening-level model and, although the methodology has
been peer-reviewed, the approach does not involve modeling tools developed to the same level of sophistication as
those used for the air and groundwater pathways.
-------
March 26, 2001 Appendix C
facilities based on site attributes relevant to completion of a given pathway. For example, EPA
reviewed technical reports on groundwater hydrology submitted by the survey respondents as
input to a numeric ranking scheme. For each site, the available information on the stratigraphy
(the composition of subsurface layers) and the location of receptor wells was assigned a numeric
score for ranking purposes. Once this ranking was completed, EPA evaluated the potential for
adverse impacts on water quality from the groundwater to surface water pathway for all of the
highest ranked facilities.
• For the air pathway, EPA used Industrial Waste Air Model (IWAIR) to model risk
at the actual location of the nearest receptor, identified using topographic maps
and aerial photos. This methodology is described in detail in Section C.2 of this
appendix.
• For the groundwater pathway, EPA conducted a Monte Carlo simulation of the
fate and transport and exposure to predict the distribution of cancer risks and
noncancer hazard, as appropriate, for chemicals of potential concern managed at
each facility. This methodology is described in detail in Section C.3 of this
appendix.
• For the groundwater to surface water pathway, EPA performed screening risk
modeling using a simplified fate and transport construct to predict the surface
water concentrations and compared those levels with the ambient water quality
criteria. This methodology is described in detail in Section C.4 of this appendix.
C.I.1.2 Key Results of the Analysis. Table C.I-2 illustrates the progression of facilities
in the sample population from the risk screening stages through the risk modeling stage.2 Note
that the results in this table are not weighted and that we do not distinguish between
concentrations based on reported values and those based on surrogate protocols or detection
limits (DLs). This table is intended to show that the analytical framework designed by EPA
provided an effective tool for reducing the number of facilities/impoundments/constituent
combinations requiring risk modeling. Notice that, at each stage, fewer facilities and
impoundments enter the subsequent stage. For example, of the 71 facilities that exceed the risk
criteria, only 10 facilities entered into the risk modeling stage; of these 10 facilities, only 7
facilities show risk exceedances, indicating that the conceptual approach of eliminating facilities
from consideration because of very low potential risks is sound. Indeed, the peer review
comments on the technical plan were, without exception, supportive of this framework. The
results generated at each stage were updated so that the risk modeling results could be integrated
with the screening results and ultimately weighted up to present a national risk characterization.
The overall results for the analysis are presented in Tables C. 1-3 through C. 1-6. Tables
C.l-3 and C.l-4 present results at the facility level, and Tables C.l-5 and C.l-6 present results at
the impoundment level. This set of tables presents the national risk characterization produced by
weighting up the sample population results presented in Table C.l-2. The weighting
methodology is described in detail in Appendix A. The tables contain information on the number
This table presents results only for the direct pathways, air, and groundwarter.
CX7
-------
March 26, 2001
Appendix C
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March 26, 2001
Appendix C
Table C.l-3. Facility-Level Overview of Human Health Results by Decharacterization
Status
Facility Status
Never Characteristic b
Decharacterized °
All facilities
Below
Crit
2,031
56%
212
26%
2,244
50%
Risk
eria
(46%)
91%
(5%)
9%
(50%)
100%
Environmental Release
All Values
1,410
39%
(32%)
74%
499 (11%)
61%
1,909
43%
26%
(43%)
100%
Exceeds Risk Criteria a
All
Values
196* (4%)
5%*
65%*
107* (2%)
13%
35%*
304* (7%)
7%
100%
Total
3,638
100%
818
100%
4,457
100%
(82%)
82%
(18%)
18%
(100%)
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
a Results are for groundwater, air, and groundwater to surface water pathways.
b Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
Table C.l-4. Facility-Level Overview of Human Health Results by Decharacterization
Status—Reported Values and Surrogate/DL Valuesa
Facility Status
Never Characteristic
Decharacterized
All facilities
Below Risk
Criteria
2,031
56%
212
26%
2,244
50%
(46%)
91%
(5%)
9%
(50%)
100%
Environmental Release1"
Reported
Values
598 (13%)
16%
330
40%*
64%*
(7%)
36%*
928 (21%)
21%
100%
Surrogate/
DL Values
812 (18%)
22%
83%
169 (4%)
21%
17%
981 (22%)
22%
100%
Exceeds Risk Criteria1"
Reported
Values
196*
5%*
(4%)
83%*
41* (0.9%)
5%*
237*
5%
17%*
(5%)
100%
Surrogate/
DL Values
0 (0%)
0%
66*
8%*
66*
1%
0%
(1%)
100%
(1%)
100%
Total
3,638
100%
(82%)
82%
818 (18%)
100%
18%
4,457 (100%)
100%
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
DL = Detection limit.
a Results are for groundwater, air, and groundwater to surface water pathways.
b Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
C-9
-------
March 26, 2001
Appendix C
Table C.l-5. Impoundment-Level Overview of Human Health Results by
Decharacterization Statusa
Impoundment
Status
Never Characteristic
Decharacterized
All Impoundments
Below Risk
Criteria
5,329
57%
697
28%
6,025
51%
(45%)
88%
(6%)
12%
(51%)
100%
Environmental Releaseb
All Values
3,813
41%
1,630
65%
5,442
46%
(32%)
70%
(14%)
30%
(46%)
100%
Exceeds Risk Criteriab
All Values
202*
2%
193
8%
396
3%
(2%)
51%*
(2%)
49%*
(3%)
100%
Total
9,344
100%
2,520
100%
11,863
100%
(79%)
79%
(21%)
21%
(100%)
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
a Results are for groundwater, air, and groundwater to surface water pathways.
b Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
Table C.l-6. Impoundment-Level Overview of Human Health Results by
Decharacterization Status—Findings Shown for Reported Values and
Surrogate/DL Values3
Impoundment
Status
Never Characteristic
Decharacterized
All Impoundments
Below Risk
Criteria
5,329
57%
697
28%
6,025
51%
(45%)
88%
(6%)
12%
(51%)
100%
Environmental Release1"
Reported
Values
1,703
18%
1,117
44%
2,820
24%
(14%)
60%*
(9%)
40%*
(24%)
100%
Surrogate/
DL Values
2,110
23%
513
20%
2,623
22%
(18%)
80%
(4%)
20%
(22%)
100%
Exceeds Risk Criteria1"
Reported
Values
187*
2%
(2%)
78%*
54* (0.5%)
2%
240*
2%
22%*
(2%)
100%
Surrogate/
DL Values
16* (0.1%)
0.2%
10%*
140 (1%)
6%
90%*
155 (1%)
1%
100%
Total
9,344
100%
2,520
100%
11,863
100%
(79%)
79%
(21%)
21%
(100%)
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
DL = Detection limit.
a Results are for groundwater, air, and groundwater to surface water pathways.
b Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
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March 26, 2001 Appendix C
of facilities in each category (shown as numerical values), the percent of the total weighted
population (shown in parentheses), and the percent within each category for both rows and
columns. Consequently, the tables may be used to provide insight on total numbers of facilities
and impoundments, percentages of the national picture, and percentages within categories of
interest such as characterization status.3 Attachment C-4 to Appendix C presents the complete
array of tables, along with standard errors, for characterization status and regulatory classification
(direct versus zero dischargers) developed for this analysis.
Table C.l-3 presents the overall results across the three pathways for which risks were
quantified—air, groundwater, and groundwater to surface water— with facilities classified
according to waste characterization categories. Table C. 1-4 presents this same information
according to whether the source concentration data were based on reported values or
surrogate/DL values. Facilities with even one impoundment that manages formerly characteristic
waste were classified under the "decharacterized" category; a facility was grouped under "never
characteristic" only if none of the impoundments receive formerly characteristic waste. Notice
that the results that are reported as "below risk criteria" are identical between Tables C.l-3 and
C.l-4. This is because the "below risk" category was effectively removed from consideration, or
screened out, in the analysis, and the focus was on characterizing those results indicating risk
criteria exceedances or environmental releases. This same information is presented at the
impoundment level in Tables C. 1-5 and C. 1-6. For the entire series of tables, it is important to
realize that the categories of "reported values" and "surrogate/DLs" are mutually exclusive. That
is, an impoundment or facility with one or more reported values that falls into the "exceeds risk
criteria" or "environmental release" categories contributes only to the results under the reported
values column. Also, an impoundment or facility that "exceeds risk criteria" if even one
constituent and impoundment is reported only in that category. As discussed throughout this
report, EPA regards the reported values as of sufficient quality to support risk findings.
The key findings from this series of tables can be summarized as follows:
• EPA estimates that 7 percent of all facilities may exceed risk criteria for one or more
direct pathways and/or the groundwater to surface water pathway. The majority of
results for those facilities are based on reported values; therefore, the risk exceedance
estimates are largely based on reported data, not surrogate protocols or detection
limits.
• Less than half the facilities (43 percent) were classified in the environmental release
category. This percentage is based on the facilities that exceeded criteria after the
screening-level modeling and did not show exceedances in the risk modeling stage
either because (1) the facility was determined to be a low priority for risk modeling or
(2) the results from the risk modeling were below levels of concern.
3 The total percentages shown in the first table of each set will sometimes be slightly higher than the
percentages shown in the detailed table with both reported and surrogate/DL concentrations. This is due to the
convention adopted for these tables to limit entries to two significant figures. Hence, 19 percent may be shown in
the table as 20% and, therefore, the totals do not appear to match exactly.
CM1
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March 26, 2001 Appendix C
• The percentage of facilities that may exceed risk criteria is higher than the percentage
of impoundments that may exceed risk criteria. Many facilities have multiple
impoundments, and this finding suggests that, where risk exceedances occur, they
generally include only a subset of the impoundments at the facility. Thus, facilities
predicted to exceed risk criteria have proportionally fewer impoundments that exceed
risk criteria than the entire group of facilities evaluated in this study. That is, the risk
estimates at the impoundment level are below the risk estimates at the facility level.
C. 1.1.3 Discussion of Key Uncertainties. This section describes the key uncertainties that
EPA identified in the risk characterization of surface impoundments that are relevant to the entire
study, regardless of the exposure pathway considered. The discussion is presented in order of
importance, beginning with the uncertainties associated with a tiered risk assessment approach,
and ending with the background concentrations. Additional pathway-specific discussions of
uncertainty are included in Sections C.I.5 through C.I.9.
Uncertainties Associated with the Approach. A tiered risk assessment offers some
distinct advantages with respect to the resources required to develop risk estimates across a large
population of facilities, impoundments, and chemical constituents. In addition, the a tiered
approach allows for the use of all information, both quantitative and qualitative, in characterizing
risks. That is, the tiered framework is not constrained by an inflexible list of data requirements.
For instance, only 15 of the 69 facilities that were classified under "environmental releases" in
the release assessment stage of the analysis progressed to screening risk modeling. Because
many of those facilities and impoundments did not exceed the risk criteria (i.e., ambient water
quality criteria), EPA concluded that the ranking scheme developed to identify high-priority
facilities was successful. Similarly, EPA conducted risk modeling for only 10 of the 71 facilities
that exceeded the risk criteria during the screening-level modeling using Industrial Waste
Evaluation Model (IWEM). If all 10 facilities that were evaluated during the risk modeling had
shown risk exceedances, then EPA might have concluded that the numeric ranking criteria were
not protective enough and that additional facilities needed to be modeled. If none of the facilities
had shown risk exceedances, then EPA might have concluded that the early screening stages
were excessively protective and that the final modeling was, in some cases, unnecessary.
However, the final modeling showed that some facilities pose potential risks while others do not,
and EPA concludes from this that the first two stages of analysis performed well in that they did
not introduce a systematic bias to the risk estimates. EPA also concludes that the third stage
served as a useful discriminator of facilities that should be considered to have risks of potential
concern.
This logic notwithstanding, there are inherent uncertainties in a tiered approach that
introduce uncertainty into the risk estimates. Specifically, it is not possible to determine with
absolute certainty that the predicted risks for facilities that were not assessed in the risk modeling
would not exceed risk criteria if they were modeled. Consequently, there is uncertainty with
respect to our ability to identify all potential risk exceedances. However, given the relatively low
level of risk exceedances for reported values (approximately 5 percent), and the apparent
effectiveness of the ranking schemes developed for the groundwater and groundwater to surface
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March 26, 2001
Appendix C
water pathways, respectively, it appears that the uncertainty in missing false positives (i.e.,
facilities that may exceed risk criteria but were not modeled) is low.4
Source Concentration Data. One of the most sensitive parameters in risk modeling is
the source concentration term. Frequently, this term is associated with a high level of uncertainty
because (1) the data on concentration may not be sufficient to characterize the variability due to
changing waste streams, impoundment conditions, and other characteristics; and (2) the
analytical methods may be insufficient to quantify the concentration term, so there is a lack of
knowledge as to what the actual concentration might be or which chemicals are actually managed
in given impoundment. The former has serious cost implications for industry because the
reporting requirements to capture the entire picture of concentration variability would be
prohibitive. The latter also has cost implications in that analytical packages with lower detection
limits tend to be more costly. However, this may be a serious source of uncertainty because it is
not known whether a chemical
concentration reported as "below the
detection limit" is slightly below the
limit, 3 orders of magnitude below the
limit, or simply an artifact of the
sampling/analysis package chosen by a
particular facility. To investigate the
uncertainty in the source concentration
data extracted from the survey responses,
EPA conducted field sampling and
analysis of a subset of facilities that
received the survey. EPA evaluated the
potential risks for direct exposure
pathways using the sampling data, and
compared those results to the results
based on survey responses; these
responses included reported detection
limits or default detection limits if none
were reported. Appendix E describes the
field sampling and analysis program,
including the methodology for sampling
and a comparison of results to the survey
data. The following discussion summarizes that approach and discusses the implications of the
findings.
Risk Screening Approach. Risk modeling for the direct pathways (air and groundwater)
was conducted on the sampling data, using the same methodology described in Section C.I. 1.1.
An Example of Sampling Data Indicating the
Presence of Chemical Constituents
A facility reported no in-scope chemicals in their
survey response, so were classified as not having an
in-scope impoundment. No risk modeling was
performed on this facility based on survey data.
The sampling program detected concentrations of 10
chemicals at this facility: 9 metals and 1 inorganic.
None of these constituents are volatile, so air
modeling was not conducted. However, groundwater
modeling was conducted using sampling data. All
but one metal (arsenic) screened out in the direct
exposure pathway screening, and arsenic screened
out at the screening-level modeling (assuming no
liner, since actual liner data were not provided in the
survey response).
Therefore, based on the sampling data, this facility
would be classified as below risk criteria.
4 It was not necessary to develop a ranking scheme to identify facilities for risk modeling of the air
pathway. Because of the limited number of facilities that exceeded risk criteria in the air release assessment, and
because of the computational speed of IWAIR, EPA decided to model all facilities indicating the potential for
environmental releases.
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March 26, 2001
Appendix C
At each stage, some impoundment-chemical combinations dropped out, and the remainder
progressed to the next stage. For groundwater, EPA conducted a preliminary screen (Phase IA)
and release assessment (Phase IB) and compared the results for each facility to those obtained
with the survey data at the conclusion of screening-level modeling. Site-based risk modeling was
not conducted for groundwater for the sampling data. For air, the sampling data did not include
the appropriate data for conducting a preliminary screen (this step requires air emissions or air
concentration data, which were not obtained in the sampling program). Therefore, we conducted
screening-level modeling and site-based risk modeling (as needed) for air. Because the sampling
data represent a small subset of the facilities surveyed (12 of 195), national weights were not
applied to these results.
Risk Re suits Using Sampling Data. None of the sampling data risk results exceeded the
risk criteria; most of the risk results fell below the risk criteria, although a few qualify under the
environmental release category. Table C. 1-7 shows the impoundments with environmental
releases for either air or groundwater based on the sampling data in contrast to the survey-based
results for these impoundments. In all cases, the sampling-based risk result is the same or below
the survey-based result.
Table C.l-7. Impoundment-level Results Comparison for Environmental
Releases Based on Sampling Data
Facility
6
68
135
173
Impoundment
2
2
1
4
Groundwater
Survey-based
Result for
Impoundment
Environmental
release
Environmental
release
Environmental
release
Environmental
release
Sample-based
Result for
Impoundment
Environmental
release
Environmental
release
Environmental
release
Below risk criteria
Air
Survey-based
Result for
Impoundment
Environmental
release
Below risk criteria
Below risk criteria
Environmental
release
Sample-based
Result for
Impoundment
Environmental
release
Below risk criteria
Below risk criteria
Environmental
release
Additional chemical-specific details for the groundwater pathway results that indicated
potential environmental releases for the sampling data are presented in Table C. 1-8. This table
compares the risk results and underlying concentrations based on the survey data with the
corresponding results and data from the sampling data. Of these seven impoundment-chemical
combinations, five had been modeled based on survey data (although four of those five were
modeled based on surrogate data rather than reported data). The sampling concentrations are
generally higher than the survey concentrations. Three of the five impoundment-chemical
combinations resulted in environmental release using the survey data; two resulted in risks below
the risk criterion using survey data. Although all three of the facilities showing environmental
C-14
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March 26, 2001
Appendix C
releases using sampling data also had environmental releases using survey data, none of the three
was chosen for further evaluation because these facilities were ranked relatively low in the
numeric ranking for groundwater risk modeling (see Attachment C-8 for ranking results). As
discussed in Section C.3, these factors include environmental setting, hydrogeologic conditions,
and direction and distance to receptor wells. In this example, the sampling data results support
our results using survey data. As a result, we are confident that the sampling results are not of
sufficient concern to merit additional groundwater modeling.
Table C.l-8. Environmental Releases for Groundwater Based on Sampling Data
Facility
6
6
68
135
135
135
135
Impoundment
2
2
2
1
1
1
1
Chemical
Fluondeb
Chloroformb
Arsenic
Fluorideb
Benzo(a)pyrene
Benz(a,h)anthracene
Arsenicb
Survey-based
Result
Below risk
criteria
Below risk
criteria
Environmental
release
Environmental
release
Not modeled
Not modeled
Environmental
release
Survey
Medium3
Leachate
Leachate
Leachate
Leachate
NA
NA
Leachate
Survey
Concentration
(mg/L)
0.26
0.053
0.17
3.75
NA
NA
0.0014
Sampling
Medium
WWm
impoundment
WWm
impoundment
WWm
impoundment
WWm
impoundment
WW influent
WW influent
WWm
impoundment
Sample
Concentration
(mg/L)
3.5
0.71
0.023
11.6
0.046
0.09
0.052
NA = Not available.
WW = Wastewater.
a All impoundment-chemical concentrations also had wastewater within the impoundment concentrations, which were equal to
the leachate concentrations.
b Survey result based on surrogate concentration data.
Additional, chemical-specific details for the air pathway results that indicated potential
environmental releases for the sampling data are presented in Table C. 1-9. This table compares
the risk results and underlying concentrations based on the survey data with the corresponding
results and data from the sampling data. Risk modeling was not performed for either of these
impoundment-chemical combinations for the air pathway using survey data. Nevertheless, EPA
conducted site-based modeling on both these impoundment-chemical combinations using actual
receptor distances (roughly 1,000 meters in both cases) and obtained risks below the risk
criterion, leaving them in the environmental release category.
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Appendix C
Table C-l-9. Environmental Releases for Air Based on Sampling Data
Facility
6
173
Impoundment
2
4
Chemical
Chloroform
Chloroform
Survey-based
Result
Not modeled
Not modeled
Survey
Medium
NA
NA
Survey
Concentration
(mg/L)
NA
NA
Sampling
Medium
WW influent
WW influent
Sample
Concentration
(mg/L)
0.81
0.071
The risk results comparison between the survey and sampling data suggest that the
concentration data reported in the surveys may not constitute a serious source of uncertainty in
this assessment. Although there are some differences in the concentrations reported in the
sampling program, and some chemicals detected in the sampling program were not reported in
the survey,5 the sampling data do not change the impoundment-level results for any
impoundment. Interestingly, the majority of survey-based results for impoundment-chemical
combinations showing environmental releases were based on surrogate/DL protocols used to
infer chemical concentrations (see Appendix A for a complete discussion of these protocols).
Although EPA considers risk results based on surrogate/DL concentration values to be more
uncertain, this comparative exercise with the sampling-based risk modeling suggests that the
decisions regarding the use of surrogate data worked as intended.
Data Limitations. Virtually every input parameter required for risk modeling is
associated with some data limitations and uncertainty. Health and ecological benchmarks,
human health and ecological exposure factors and behavior patterns, and environmental
characteristics of each site rely on data sources of differing quality and are incomplete to some
degree. For example, human health benchmarks for inhalation were not available for all
constituents evaluated in this study. The absence of air risk results for these constituents does
not imply that there are no significant inhalation risks associated with those constituents or the
facilities and impoundments in which they are managed. The absence of air risks for chemicals
lacking inhalation benchmarks is a source of uncertainty that cannot be quantified given the
current state-of-the science and available data. The implications of missing benchmarks along
with other sources of uncertainty are discussed below.
Human Health and Ecological Benchmarks. Sources of uncertainty in toxicological
benchmarks include one or more of the following: extrapolation from laboratory animal data to
humans or ecological receptors, variability of response within the population of interest,
extrapolation of responses at high experimental doses under controlled conditions to low doses
under highly variable environmental conditions, and adequacy of the database (number of studies
available, toxic endpoints evaluated, exposure routes evaluated, sample sizes, length of study,
etc.). Toxicological benchmarks are designed to be protective (i.e., to potentially overestimate
As reported in Appendix A, EPA expected to find chemical constituents not reported in the survey
responses in some impoundments because the analytical methods used by EPA included lower detection limits for
some chemicals.
C-16
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March 26, 2001 Appendix C
risk) because of the uncertainties and challenges associated with condensing toxicity data into a
single quantitative expression.
Cancer Slope Factors. Cancer slope factors (CSFs) were derived as the 95 percent upper
confidence limit of the slope of the dose-response curve using a linear, no-threshold
dose-response model. The cancer slope factor is, therefore, an upper-bound estimate of the
cancer risk per unit dose and, for this reason, may overstate the magnitude of the risk. In
addition, the use of CSFs in projecting excess individual cancer risk introduces uncertainty
stemming from a number of factors, including
• Limited understanding of cancer biology
• Variability in the response of animal models
• Differential response in animal models versus humans
• Difference between animal dosing protocols and human exposure patterns.
A key step in CSF development is high- to low-dose extrapolation. Depending on the
model used to fit the data, extrapolations to the low dose range can vary by several orders of
magnitude, reflecting the potential uncertainty associated with the cancer slope factor.
Reference Doses and Reference Concentrations. Uncertainty in the toxicological and
epidemiological data from which reference doses and reference concentrations are derived is
accounted for by applying uncertainty factors. An RfD (or RfC) is "an estimate (with uncertainty
spanning perhaps an order of magnitude) of a daily exposure to the human population (including
sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a
lifetime" (U.S. EPA, 2000b). RfDs and RfCs are based on the no observed adverse effect level
(NOAEL) or lowest observed adverse effects level (LOAEL) for the most sensitive effect in the
most sensitive or most relevant species. A series of standard uncertainty factors are applied to
the NOAEL or LOAEL to derive the RfD or RfC. The following uncertainty factors account for
areas of scientific uncertainty:
• Intraspecies variation: accounts for variation in sensitivity among humans (including
sensitive individuals such as children, the elderly, or asthmatics)
• Interspecies variation: accounts for extrapolating from animals to humans
• LOAEL to NOAEL extrapolation
• Subchronic to chronic: accounts for extrapolating from a subchronic NOAEL or
LOAEL to a chronic NOAEL or LOAEL
• Incomplete database; accounts for the lack of data for critical endpoints (e.g.,
reproductive and developmental).
Uncertainty factors of 1, 3, or 10 are used. The default value is 10; however, an
uncertainty factor of 3 may be used, for example, if appropriate pharmacokinetic data (or models)
are available. In addition, a modifying factor may be applied to account for additional
C-17
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March 26, 2001
Appendix C
uncertainties in accordance with professional judgment. The default value for the modifying
factor is 1. All uncertainty factors (UFs) and the modifying factor (MF) are multiplied together
to derive the total uncertainty factor (e.g., U.S. EPA, 1994e). Therefore, the RfD (or RfC) is
derived using the following formula:
RfD = NOAEL/(UF x MF).
The effect of applying uncertainty and modifying factors is to lower the estimate of the
reference dose and increase the hazard quotient for a given exposure.
Exposure Factors. The uncertainty in selection of health and ecological exposure factors
changes depending on which stage of the risk analysis is considered. For the preliminary screen
(Phase IA) and release assessment (Phase IB), screening factors6 were derived using protective,
default values for exposure as discussed in the Technical Plan. The default exposure factors for
human health are presented in Table C.l-10; because of the number of ecological receptors, the
ecological exposure factors are presented in Attachment C-21. For the risk modeling of the air
pathway, the default exposure factors for IWAIR are virtually identical to those shown in Table
C.l-10 and, as a result, the choice of exposure factors for the inhalation pathway will also tend to
overpredict risk. As described in the Technical Plan., the IWAIR model is not currently set up to
run Monte Carlo simulations, and these protective exposure factors were used. These exposure
factors are, by design, protective of human health and wildlife and, therefore, tend to overpredict
risk.
Table C.l-10. Exposure Parameter Values Used to Calculate
Human Health Risk Screening Factors
Receptor
Child < 1
Child 1-5
Child 6- 11
Child 12-18
Adult Resident
Inhalation
Rate
(m3/d)
4.5
7.55
11.75
14
13.3
Ingestion
Rate of
Water
(L/d)
0.3
0.7
0.79
0.96
1.38
Ingestion
Rate of
Soil
(mg/d)
ID
200
50
50
50
Exposure
Frequency
(d/yr)
350
350
350
350
350
Exposure
Duration
(yr)
1
5
6
7
11
Body
Weight
(kg)
9.1
15.5
30.8
58.4
71.4
ID = Insufficient data.
In contrast, the risk modeling of the groundwater pathway involved the use of
distributions generated by fitting the data summaries in the Exposure Factors Handbook (EFH)
(U.S. EPA, 1997c, 1997d, 1997e), in most cases by fitting distributions to selected percentiles. It
is assumed that little information is lost by fitting to percentiles versus fitting to raw data. Three
See Attachment C-3 for a complete list of human health screening factors, and Attachment C-23 for a
complete list of ecological risk screening factors.
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March 26, 2001 Appendix C
standard two-parameter probability statistical distributions (gamma, lognormal, and Weibull)
were used in the groundwater pathway simulation. Other statistical distributions are possible
(e.g., U.S. EPA, 2000d), but the technique used in this analysis offered considerable
improvement over using a lognormal model in all cases.
Although they offer significant improvement in objectivity over visual estimation,
goodness-of-fit tests used to determine which statistical distribution to use for a particular
parameter are themselves subject to some uncertainty. One area of concern is uncertainty about
how the survey statistics in the EFH (U.S. EPA, 1997c, 1997d, 1997e) were calculated. All of
the statistics that have been used to assess goodness-of-fit assume a random sample, which may
or may not be a valid assumption for EFH data. Specifically, many of the EFH data sources are
surveys that, in many cases, do not involve purely random samples. Rather, they use clustering
and stratification, primarily for economic reasons. The effect of this uncertainty on the risk
modeling results is unknown.
Natural Background Exposures. In certain cases, EPA performs a risk assessment on
wastes that contain contaminants that also are present in the environment as a result of both
natural processes and anthropogenic activities. Under these circumstances, receptors potentially
receive a "background" exposure that may be greater than the exposure resulting from release of
contaminants from the waste. For national analyses like this assessment, the inclusion of
background concentrations as part of the analysis is not feasible due to the variability of
background concentrations nationwide and the lack of data on national background
concentrations for each constituent. Although the margin of exposure and risk predicted during
the tiered risk assessment may be used to represent the risk attributable to chemicals managed in
surface impoundments, the methodology does not allow us to calculate risks or hazards that
reflect both impoundment releases and other environmental sources. For instance, the margin of
exposure attributable to a particular facility may be below levels of concern; however, in addition
to other background exposures, the total risk to residents attributed to the facility and other
sources of chemical exposure may be above levels of concern. The variability in background
exposures is not reflected in this analysis and is considered a source of uncertainty that is not
quantifiable in this analytical framework.
C.I.2 Phase I A: Preliminary Screen - Human Health
As described in the Technical Plan, the human health risk screening calculation was
performed for each constituent in each surface impoundment for each of the in-scope sample
facilities. For this phase, the screening risk estimates were constituent-specific cancer risks or
hazard indices (His) summed across exposure pathways. Cumulative risks were then calculated
for each impoundment and each facility and for each constituent (summed over all
impoundments at the facility). The cumulative risk estimates were used to build initial risk
distributions for the surface impoundments within the scope of the study. Risk distributions were
generated by characterization status and regulatory status and divided into cancer risks and
noncancer hazard. These risk estimates were used to exclude constituents, impoundments, and
facilities from further analysis.
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March 26, 2001 Appendix C
C.I.2.1 Methods Summary. The groundwater ingestion pathway was evaluated whenever
wastewater concentrations or leachate concentrations were available. The air inhalation pathway
was evaluated if the constituent was a volatile organic chemical (VOC) or a semivolatile organic
chemical (SVOC), and airborne chemical concentration or emissions data were provided in the
survey. The soil ingestion pathway was considered; however, EPA believed that uncertainties in
characterizing the exposure scenario for postclosure were sufficiently high to render the
screening risk results of little value. Environmental releases of sludge particles could occur
through erosion/runoff or windblown emissions only assuming that: (1) the impoundment was
not capped at closure, (2) the impoundment was completely filled with sludge to grade; and (3)
no vegetation was allowed to grow on the sludge. This pathway was evaluated, instead, under
the indirect exposure pathway assessment described in Section C.5. Once the air and water
concentrations were determined from the survey results, the risks were calculated by dividing the
concentration by the appropriate health screening factor, and then multiplying by the appropriate
risk criterion. If the screening factor was based on a regulatory standard such as a maximum
contaminant level (MCL), then the ratio of concentration to the screening factor was calculated.
Finally, the constituent risk and HI were calculated by summing the risks and hazard quotients
for all pathways for that particular constituent. If the screening for the constituent has used a
regulatory standard, then the maximum ratio of all pathways for that constituent was selected.
Concentration data from the facility survey questionnaire provided the direct exposure
concentrations for the Phase IA risk estimates. A special condition existed for calculating air
inhalation risks from survey data: if the survey questionnaire did not provide an air concentration
or emission rate for a VOC or SVOC constituent, the constituent automatically progressed to
Phase IB.
Cumulative Risk Calculation. The calculated screening risks for each constituent for a
specific impoundment and facility were combined to generate three cumulative risk estimates:
impoundment risk, constituent risk, and facility risk. The cumulative risks were used in the risk
screening and risk distributions, as described below.
The impoundment risk (i.e., risk for a particular impoundment for a particular facility)
was determined as follows:
• For carcinogenic risks, sum risks from all carcinogenic constituents.
• For noncarcinogenic risks, sum the His for all constituents potentially affecting
the same target organ, then select the maximum HI from the target organ His.
The constituent risk (i.e., risk for a particular constituent for a particular facility) was
determined as follows:
• For carcinogenic risks, select the maximum risk for the constituent across all
impoundments for the particular facility.
• For noncarcinogenic risks, select the maximum HI for the constituent across all
impoundments for the particular facility.
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March 26, 2001 Appendix C
Facility risks were calculated as follows:
• For carcinogenic risks, sum the constituent risks.
• For noncarcinogenic risks, sum the His from all constituents potentially affecting
the same target organ, then select the maximum HI from the target organ His.
Note that this approach takes into account that an individual receptor's exposure factors will only
be counted once for the entire facility (e.g., 1.4 L ingested per day or 13 m3 inhaled per day).
Risk Distribution Development. Cumulative frequency histograms of the risks/His
were developed from the impoundment, constituent, and facility cumulative risks. A risk
cumulative histogram was defined by a set of six class intervals or "bins." The carcinogenic risk
ranges defining those bins are: Oto 10'8, 10'8to 10'7, 10'7to 10'6, 10'6to 10'5, 10'5to 10'4, and 10'4.
An HI cumulative histogram was defined by six bins: 0 to 0.01, 0.01 to 0.1, 0.1 to 1.0, 1.0 to 10,
10 to 100, and greater than 100. For the nationally weighted risk results, all of the risk results
below the risk criteria were aggregated into a single bin; however, the risk data were not
aggregated in this manner prior to the application of national weights.
Risk Screening. The Phase IA risk screening used the three cumulative risk distributions
to identify
• Constituents, impoundments, and facilities that have risks below a decision
criterion and, therefore, are considered to have negligible risks and are not
assessed further.
• Constituents, impoundments, and facilities that have risks above a decision
criterion and that will be assessed in Phase IB.
The screening procedure first screened facilities by comparing the facility cumulative risk
to the risk decision criteria. If the facility had a risk above the screening criteria, then the
impoundment cumulative risk for each impoundment for that facility was compared to the
screening criteria. If the impoundment had a risk above the screening criteria, then the
constituent cumulative risk for that facility was compared to the screening criteria. If the
constituent had a risk above the screening criteria, then the constituent passed to Phase IB for
further screening. The constituent was further evaluated only for those impoundments at the
facility that had risks above the screening criteria. The risk screening was performed for both
cancer and noncancer risks.
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March 26, 2001 Appendix C
EXAMPLE. Calculating the cumulative risks and risk screening for a facility.
The example facility has the risk estimates shown in Table C. 1-11. The first table
presents the risk estimates for each chemical in each of the four impoundments.
The second part of the table shows the cumulative facility, impoundment, and
constituent risks. The impoundment risk is the sum of the chemical risks for the
impoundment; the impoundment HI is the maximum HI of the two target organ
His. For instance, for Impoundment A, the carcinogenic risk of 3.7 x 10"4 is the
sum of Chemicals 1 and 4. The HI of 0.5 is the HI for Target Organ B.
The constituent risks and His are the maximum of risks and HI for all four
impoundments. For instance, Chemical 1 is detected in Impoundments A, B, and
D. Impoundment A has the maximum risk of 3.7 x 10"4 (from Impoundment A).
The facility risk of 3.7 x 10"4 is the summation of all carcinogenic constituent risks
(Chemicals 1, 4, and 6). The facility HI of 11.05 is the summation of constituent
His for target organ A. Specifically, this is Chemical 2 from Impoundment A and
Chemical 5 from Impoundment B.
The third part of the table shows the risk screening results for the facility. One
impoundment and three chemicals are screened from further assessment at this
facility. Three chemicals at three impoundments move on for further assessment
in Phase IB.
C.I.3 Phase IB: Release Assessment - Human Health
As described in the Technical Plan, the human health risk screening was performed for
each constituent in each surface impoundment for each of the in-scope sample facilities that
exceeded the risk criteria in Phase IA. As with Phase IA, the screening risk estimates were
constituent-specific cancer risks or His summed across exposure pathways. Cumulative risks
were then calculated for each impoundment and each facility and for each constituent and used to
update the Phase IA risk results. Risk distributions were generated by characterization status and
regulatory status and divided into cancer risks and noncancer hazard. These risk estimates were
used to exclude constituents, impoundments, and facilities from further analysis.
C. 1.3.1 Methods Summary. EPA used screening models to supplement the initial
screening performed under Phase IA. Use of screening models provided additional
characterization of exposure by evaluating the fate and transport of constituents from their
release from the surface impoundment through the environmental media to the point of exposure.
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March 26, 2001
Appendix C
Table C.l-11. Example Screening Risks for a Facility
Impoundment
Impoundment A
Impoundment B
Impoundment C
Impoundment D
Cumulative risk
Impoundment risk
Constituent risk
Facility risk
Chemical
Chemical 1
Chemical 2
Chemical 3
Chemical 4
Chemical 1
Chemical 3
Chemical 4
Chemical 5
Chemical 2
Chemical 3
Chemical 5
Chemical 1
Chemical 6
Impoundment A
Impoundment B
Impoundment C
Impoundment D
Chemical 1
Chemical 2
Chemical 3
Chemical 4
Chemical 5
Chemical 6
HI
Risk Target Organ A Target Organ B
3.7E-04
le-08
2.0E-05
8.0E-08
5.0E-12
3e-08
Risk
3.7E-04
2.0E-05
-
3.0E-08
0
8e-08
3e-08
0
0.05
0.3
0.007
11.00
0.0004
0.8
0.003
HI
0.3
11.00
0.8
-
0.05
0.8
11
11.05
Risk Screening Results:
Tierl
Tier 2
Tier3
Conclusion
Facility
Impoundment A
Impoundment B
Impoundment C
Impoundment D
Chemical 1
Chemical 2
Chemical 3
Chemical 4
Chemical 5
Chemical 6
Risk and HI > decision criteria3
Risk and HI > decision criteria3
Risk and HI > decision criteria3
HI > decision criteria3
Risk < decision criteria3
Risk > decision criteria3
HI < decision criteria3
HI > decision criteria3
Risk < decision criteria3
HI > decision criteria3
Risk < decision criteria3
Impoundment A: Chemicals 1 and 3 to be assessed in next phase
Impoundment B: Chemicals 1 and 5 to be assessed in next phase
Impoundment C: Chemical 3 to be assessed in next phase
Impoundment D: No further assessment of chemicals 1 and 6; no further
assessment at this facility
Decision criteria: 10"5 for cancer risk; 0.1 for noncancer risk.
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March 26, 2001 Appendix C
The Phase IB screening addressed only the major routes of exposure that were expected
to contribute significantly to potential risks (i.e., ingestion of drinking water and inhalation of
air). However, because constituents from specific units may be screened from further analysis,
the Phase IB modeling approach used several precautionary assumptions, such as assessing risks
for close-in receptors.
The EPA screening models IWAIR and IWEM, developed for use under the Industrial D
guidance, were used to calculate screening risk estimates. These risk estimates replaced the
corresponding Phase IA screening risk estimates and, therefore, decreased the uncertainty of the
overall screening risk distributions developed in Phase I.
Phase IB Human Health Screening Models. IWAIR and IWEM assess the risks from
potential exposure of air and groundwater, respectively, from constituents released from surface
impoundments. The screening models, as described below, use different approaches. However,
both models provided screening analyses that are useful in characterizing exposure, and both
models incorporated additional site-specific data. Despite the difference in modeling approaches,
the results from each of the Phase IB models constitute a defensible basis to provide screening-
level estimates of risk.
IWAIR. The IWAIR model (U.S. EPA, 1998b) was used to calculate risks due to
inhalation of airborne volatile and semivolatile constituents released from surface
impoundments. IWAIR incorporates the CHEMDAT8 volatile emission model to
calculate the constituent release (i.e., emission rate) from an impoundment, uses
dispersion factors developed from Industrial Source Complex Short Term (ISCST3)
modeling simulations to calculate an air concentration, uses exposure and risk
calculations following EPA guidance (Risk Assessment Guidance for Superfund, U.S.
EPA, 1989b), and uses a chemical and toxicological database to calculate carcinogenic
and noncarcinogenic chronic inhalation risks. CHEMDAT8 has undergone extensive
review by both EPA and industry representatives and is publicly available. ISCST3 is
another regulatory standard model that has undergone substantial review and use by
industry. Dispersion factors for multiple source area sizes, receptor distances, and
meteorological conditions are provided.
IWAIR uses the same exposure factors as Phase IA from the Exposure Factors Handbook
(U.S. EPA, 1997d). An age-weighted resident was considered for carcinogenic
chemicals. An adult resident was considered for noncarcinogenic chemicals. Phase IA
toxicological benchmarks were used (in place of IWAIR toxicological benchmarks) to
calculate screening risks with IWAIR. For SIS constituents that were not included in the
IWAIR chemical database, the physicochemical properties from CHEMDAT8 and Phase
IA toxicity benchmarks were added to IWAIR to calculate the constituent risks and His.
The IWAIR model is computationally fast and easy to use and requires input data on
impoundment characteristics and meteorological conditions. The data required were
obtained from the survey to the extent possible; these data include constituent waste
concentration, impoundment depth, area, annual wastewater flow rate, and whether or not
aeration occurs. Default or additional site-specific data were used for aeration
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March 26, 2001 Appendix C
parameters and wastewater parameters important for biodegradation. The data protocols
established to populate the data files for IWAIR are described in detail in Attachment C-5
of this appendix.
IWEM. The IWEM Tier 1 (U.S. EPA, 1999c) model was used to calculate the risks due
to exposure to groundwater containing constituents released from surface impoundments.
IWEM Tier 1 is based on a health-protective Monte Carlo probabilistic analysis that
accounts for the nationwide variability of groundwater modeling parameters. The Monte
Carlo approach used in EPACMTP and IWEM has been applied in various EPA
regulatory efforts, including the proposed 1995 Hazardous Waste Identification Rule
(HWIR) and hazardous waste listing evaluations. As such, the Monte Carlo procedure
and its applicability to national analyses has been reviewed extensively within EPA and
by the Science Advisory Board and has been subject to public review and comment (U.S.
EPA, 1999a). The Monte Carlo procedure randomly drew input parameter values from
representative statistical distributions for each parameter. A set of input parameter values
was developed and the model was run to compute the groundwater monitoring well
concentration and the dilution attenuation factor (DAF) at 150 m from the source along
the centerline of the plume. This process was repeated thousands of times until a
distribution of thousands of output values (DAFs) was produced. The DAF values were
ranked from high to low, and the 90th percentile DAF was determined. The 90th percentile
DAF represents the amount of dilution and attenuation that would occur in at least 90
percent of the cases modeled. In other words, the DAF is protective in at least 90 percent
of the modeled cases. The selection of 90th percentile DAF is based on
• The need to choose a level of protection that is protective and consistent with
other EPA analyses, including the proposed HWIR of 1995 (U.S. EPA, 1995b)
and hazardous waste listing evaluations (e.g., the Petroleum Refinery Waste
Listing Determination, U.S. EPA, 1997g)
• The desire to have a large degree of confidence that the results are adequately
protective of human health and the environment given the degree of uncertainty
inherent in the data and the analyses.
Leachate concentration threshold values and DAFs are included for three impoundment
liner scenarios in IWEM: no liner, single liner, and a composite liner. The no liner
scenario represents an impoundment that is relying upon location-specific conditions such
as low-permeability native soils beneath the unit or low annual precipitation rates to
mitigate the release of contaminants to the groundwater. The single liner scenario
represents a 3-foot-thick clay liner with a low hydraulic conductivity (10"7 cm/s) beneath
the impoundment. The composite liner scenario consists of a 3-foot-thick clay liner
beneath a well-installed and operated 40-mil-thick high-density polyethylene (HOPE)
flexible membrane liner.
For each chemical, the DAF from the appropriate liner scenario was multiplied by the
carcinogenic or noncarcinogenic risk screening factor from Phase IA to adjust the
leachate concentration values in the IWEM Tier I table to reflect the same exposure
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March 26, 2001 Appendix C
factors that were used in the Phase IA analysis. For example, the age-adjusted ingestion
rates used in the Phase IA drinking water screening are different from the standard
ingestion rate used to construct the IWEM Tier I table (i.e., adult-only rates). In effect,
the Tier I table was normalized to the same exposure factors used throughout the Phase
IA preliminary risk screening.
A number of SIS constituents are not included in the IWEM Tier 1 table. For these
constituents, a leachate concentration threshold value using a DAF from a surrogate
chemical was calculated (see Section C.3 for DAFs). The leachate concentration
threshold value was calculated by using the IWEM procedure for estimating DAFs of
chemicals for which EPACMTP was not simulated, as follows: the DAF was determined
by interpolating between the DAFs of chemicals whose hydrolysis rate and retardation
factor are in the same range as the hydrolysis rate and retardation factor of the new
chemical.
Human Health Risk Calculation. Because IWAIR must represent wind conditions
across the continental United States, IWAIR contains wind dispersion data based on 29
meteorological stations.7 Because the wind pattern may not be representative of the actual site
conditions, a close-in receptor at 25 m was assumed for the Phase IB screen. If a constituent was
not currently in IWAIR, its physicochemical and toxicological data were added to the IWAIR
chemical database.
The Phase IB groundwater risk calculation considered the type of lining at each
impoundment in determining the appropriate groundwater screening factor, called the leachate
concentration threshold value (LCTV) in IWEM. The risk calculation mirrors the Phase IA
calculation: calculate the ratio of the leachate concentration to the LCTV and multiply by the risk
criteria.
Cumulative Risk Calculation. The calculated screening risks for each constituent for a
specific impoundment and facility were combined to generate three cumulative risk estimates:
impoundment risk, constituent risk, and facility risk , as described in Section C.I.2.1. It is
important to note that the cumulative risks are a combination of the Phase IA and Phase IB
calculated risks for each constituent, because the Phase IB risk estimate is considered a
refinement of the initial Phase IA risk estimate.
Risk Distribution Development. The risk distribution approach was identical to that
defined in Phase IA. Because the Phase IB cumulative risks are a combination of the results
from Phase IA and IB, the risk distributions also represent the combined analysis of Phase IA
and IB. That is, overall results were updated using the Phase IB results.
Risk Screening. The risk screening approach is also identical to that defined in
Phase IA.
7 Dispersion data for 12 additional meteorological stations were added to IWAIR for this study.
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March 26, 2001 Appendix C
C.I.4 Results of Screening Assessment—Phase IA and IB
The combined Phase IA and IB screening risks for each constituent, impoundment, and
facility provided the initial screening-level risk distribution profiles for the sample population.
The refinement of the screening-level risk distribution from Phase IA to Phase IB is shown in
Figures C. 1-1 and C. 1-2 for cancer risks associated with the groundwater pathway, for
decharacterized and never characteristic impoundments, respectively. These figures present the
actual risk results derived for the Phase 1A and IB analyses of the groundwater pathway on the
sample population. Notice that these results are not aggregated according to the three bins
described in Chapter 3—below risk criteria, environmental release, and potential concern—
because these results are unweighted. The figures illustrate the progression of impoundment-
chemical combinations through the screening process. Risk results calculated in Phase IA are
shown as lightly shaded in the figures and are always below the risk criterion because any
combinations that were above the risk criteria in Phase IA progressed to the Phase IB release
assessment. The results of Phase IB darkly shaded in the figures indicate that, while a number of
impoundments fell below the risk criteria, a significant number would be considered for risk
modeling of the groundwater pathway and, ultimately, would either be shown as "environmental
release" or "may exceed risk criteria." The impoundments that are shown to be above the risk
criteria in these histograms became the subset that was considered for the groundwater pathway
risk modeling described in detail in Section C.3. However, only those impoundments (and
facilities) that were at the top of the numeric ranking scheme progressed to the risk modeling
stage of the analysis.
C.I.5 PhaseIC/II: Risk Modeling— Air Pathway
C.I.5.1 Methods Summary and Key Results. In the risk modeling of the air pathway, EPA
evaluated the risk to a person inhaling air contaminated with the chemicals released from surface
impoundments. These chemicals reach the air by volatilizing from the surface impoundment.
They may then be transported some distance from the impoundment before a person inhales
them. The farther the person is from the impoundment, the lower the concentration of the
chemical in the air and the lower the risk. Each of the screening steps described above is similar
in that the risk criteria were established at 1E-5 for risk or 1 for hazard, and the release
assessment and risk modeling used IWAIR. This model uses emissions data from the survey or,
if no data are available, estimates emissions from concentration and other site-specific data from
the SIS survey. IWAIR then estimates the concentration in air at some distance from the
impoundment. The farther from the impoundment, the lower the air concentration. In the risk
modeling stage, the default receptor distance of 25 meters was replaced with a site-specific
distance identified in the survey responses or gleaned from GIS sources and a review of aerial
photographs. Because the actual distance to the nearest receptor was typically higher than the
default IWAIR distance of 25 meters, the risk estimates in this stage generally were lower than
those predicted in the release assessment. Table C. 1-12 presents the results for the air pathway
with facilities classified according to waste characterization categories. Table C.l-13 presents
this same information according to whether the source concentration data were based on reported
values or surrogate/DL values. The complete risk results, standard errors, and additional
descriptors on regulatory status (direct vs. zero dischargers) and impoundment type (e.g., aerated
vs. nonaerated) are presented in Attachment C-7 to this appendix.
C-27
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March 26, 2001
Appendix C
Phase! A Results
• Phase 1A + 1B Results
10O
80-
20-
-Risk Criterion
E-4
Human Cancer Risks
(Leachate beneath impoundment)
Figure C.l-1. Unweighted cancer risk results for sample population of
impoundments for the groundwater pathway—decharacterized.
Phase!A Results
• Phase 1A + 1B Results
E-4
Human Cancer Risks
(Leachate beneath impoundment)
Figure C.l-2. Unweighted cancer risk results for sample population of
impoundments for the groundwater pathway—never characteristic.
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March 26, 2001
Appendix C
The results of the air pathway analysis indicate that, for facilities that may exceed the risk
criteria, the weighted risk estimates may be associated with a significant standard error. Indeed,
Table C.l-13 indicates that the national risk estimates may not be reliable for the facilities that
may exceed the risk criteria based on reported concentration data. Although the standard errors
associated with these results are large, the data suggest a trend that facilities that manage never
characteristic wastes are associated with potentially higher risk levels than facilities that manage
decharacterized waste.
Table C.l-12. Facility-Level Overview of Human Health Risk Results for
Air Pathway by Decharacterization Status
Facility Status
Never Characteristic
Decharacterized
All Facilities
Below Risk
Criteria
3,344
92%
(75%)
86%
547 (12%)
67%
3,892
87%
14%
(87%)
100%
Environmental Release3
All Values
136
4%
198
24%
334
8%
(3%)
41%*
(4%)
59%*
(8%)
100%
Exceeds Risk
Criteria3
All Values
158* (4%*)
4%*
68%*
73* (2%)
9%
32%*
231* (5%)
5%
100%
Total
3,638 (82%)
100%
818
100%
4,457
100%
82%
(18%)
18%
(100%)
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
Table C.l-13. Facility-Level Overview of Human Health Risk Results for the Air Pathway
by Decharacterization Status - Reported Values and Surrogate/DL Values
Facility Status
Never Characteristic1"
Decharacterized0
All Facilities
Below Risk
Criteria
3,344
92%
(75%)
86%
547 (12%)
67%
3,892
87%
14%
(87%)
100%
Environmental Release
Reported
Values
105*
3%
64*
8%*
169
4%
(2%)
62%*
(1%)
38%*
(4%)
100%
Surrogate/
DL Values
31* (0.7%)
0.9%
19%*
134 (3%)
16%
81%*
165 (4%)
4%
100%
Exceeds Risk Criteria3
Reported
Values
158*
4%*
(4%*)
92%*
13* (0.3%*)
2%*
171*
4%*
8%*
(4%*)
100%*
Surrogate/
DL Values
0 (0%)
0%
60*
7%*
60*
1%
0%
(1%)
100%
(1%)
100%
Total
3,638
100%
(82%)
82%
818 (18%)
100%
18%
4,457 (100%)
100%
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
DL = Detection limit.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
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March 26, 2001 Appendix C
C.I. 5.2 Discussion of Uncertainty. In its assessment of the air pathway, EPA relied on
modeling tools that have been peer-reviewed and used in previous analyses, as much site-specific
data as possible from the surveys, and standard EPA sources for important data such as exposure
factors and health benchmarks. All of these factors contribute to a relatively robust analysis that
met the study objectives of protective screening at earlier stages of the many impoundments and
constituents and more robust modeling at the final stages of analysis. However, there are several
key uncertainties that should be considered in interpreting the results of the air analysis. These
are grouped under parameter uncertainties, modeling uncertainties, and results uncertainties.
This section identifies these sources of uncertainty and qualitatively describes how each may
influence the results.
Parameter Uncertainties. The key parameters required for the air pathway modeling
included impoundment characteristics, receptor location, and exposure parameters.
• Impoundment Characteristics. To the extent possible, impoundment characteristics
needed for the modeling were taken from the survey responses. However, some
parameter values such as oxygen transfer rate, were not available from the survey
responses for some or all impoundments. In these cases, assumptions or estimates
were made, and these introduce uncertainty into the results. These assumptions and
defaults could result in either under- or overprediction of risk, depending on the actual
impoundment characteristics; however, they were generally chosen to be somewhat
conservative (i.e., to overpredict risk), in keeping with the screening nature of this
assessment.
• Receptor Location. The predicted risks were derived using actual receptor locations at
each site. To the extent that some of these locations were based on old maps, there is
some uncertainty introduced in the risk estimates, which could be either over- or
underestimated, depending on whether the actual nearest receptor is nearer or farther
from the site than the receptor location used. However, the conclusions regarding
whether or not the risk may exceed the risk criteria are more robust, because in cases
where this conclusion was sensitive to receptor location, the location was verified
using recent aerial photos. Therefore, the uncertainties in the final results based on
receptor location are small. It is important to note, however, that the air risks
represent the nearest receptor to a given impoundment and do not necessarily reflect
the "typical" risks to other receptors living within a 2-km radius of the facility; those
"typical" risks are likely to be lower than the predicted risks for the closest receptor.
• Exposure Parameters. IWAIR uses standard EPA exposure factors, such as inhalation
rate, body weight, and exposure duration. These parameters are based on the
assumption of a receptor who ages from childhood to adulthood during the course of
exposure. There is uncertainty in the risk results to the extent that actual receptors do
not match these "typical" factors or this age profile. Exposure factors have been
chosen to be somewhat conservative; therefore, this uncertainty will typically result in
an overestimate of risk.
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March 26, 2001 Appendix C
Modeling Uncertainties. The modeling for the air pathway simplifies the fate and
transport of chemicals from an impoundment through air to a receptor. Many of these
simplifications could result in either over- or underprediction of risk.
• Volatile Emissions. Emissions were modeled using CHEMDAT8. The level of peer
review to which this model has been subjected supports confidence in the modeling
construct to provide a solid basis for predicting inhalation risks. To the extent that
this model is uncertain, it is unknown whether it would over- or underpredict
emissions.
• Hydrolysis. The version of CHEMDAT8 incorporated in IWAIR cannot model
hydrolysis. Hydrolysis rates are also not readily available for many chemicals. To the
extent that constituents modeled with IWAIR do hydrolyze, IWAIR will overpredict
emissions and therefore risks. For some constituents that hydrolyze quickly, this
could be significant. For others, it will be less significant or insignificant, depending
on the rate at which the constituent actually hydrolyzes in a particular impoundment.
• Biodegradation Losses. IWAIR does model biodegradation losses in the
impoundment, using conservative (i.e., lowest available) biodegradation rate
constants. The lower the level of biodegradation, the more constituent is available to
volatilize, and the greater the emissions and risks. However, biodegradation is heavily
influenced by such site-specific factors as temperature, pH, and other constituents
present. Therefore, the emissions estimates are uncertain to the extent that actual
biodegradation at a particular impoundment differs from the rate assumed. This
uncertainty could result in either over- or underprediction of emissions and risks.
• Dispersion Factors. Dispersion factors were generated using the Industrial Source
Complex model (ISC). ISC has been thoroughly peer-reviewed, which provides
confidence in the modeling construct to provide a solid basis for predicting inhalation
risks. To the extent that this model is uncertain, it is unknown whether it would over-
or underpredict emissions.
• Receptor Location Relative to Plume. The receptor is assumed to be located at the
centerline of the plume of constituent as it disperses around the site. Air
concentrations are highest at the centerline of the plume, and decrease with distance
from the centerline. Depending on the site-specific meteorology, particularly
prevailing wind directions, the nearest receptor may not be located in the centerline of
the plume. This uncertainty tends to overpredict air concentration at the nearest
receptor, and thus risk.
• Coverage of Meteorological Data in IWAIR. IWAIR uses dispersion factors for a pre-
determined set of 29 meteorological stations. Peer review of IWAIR suggested that
additional meteorological stations would reduce uncertainty in the air concentration
estimates; therefore, dispersion factors for 12 additional meteorological stations were
generated and added to IWAIR for this study. There remains some uncertainty in the
risk estimates to the extent that the 41 available meteorological stations do not fully
C-31
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March 26, 2001 Appendix C
represent all possible locations where there are impoundments. However, this
uncertainty, with the addition of new meteorological stations for IWAIR, is believed
to be small. The direction of this uncertainty is not known—depending on the
impoundment location, the air concentration (and thus risk) could be over- or
underpredicted.
• Interpolation of Dispersion Factors in IWAIR Based on Impoundment Area. IWAIR
uses dispersion factors generated for a fixed set of 14 impoundment areas. For
impoundment areas that fall between the impoundment areas in IWAIR, there is some
uncertainty based on this interpolation. The interpolation will result in the
underprediction of air concentration, and therefore risk. This underprediction is
expected to be modest; it will be greatest for small areas that fall close to halfway
between 2 of the 14 modeled areas. It will be less for areas that fall near 1 of the 14
modeled areas, and less for large areas regardless of closeness to one of the modeled
areas (because the dispersion factor curve flattens out at large areas and is less
sensitive to area).
• Interpolation of Risk by Distance. The IWAIR model can only be run at 7 preset
distances. Therefore, risk results were interpolated to the actual distance of the
nearest receptor. This interpolation is likely to slightly overpredict risk.
Results Uncertainties. As with any risk assessment, there is uncertainty in the risk
results associated with simplifying assumptions and data limitations such as chemical-physical
properties and health benchmarks. Several key uncertainties to consider in interpreting the risk
results are presented below.
• Standard Error. The large standard error for the national estimate of potential risk
exceedances for facilities with reported chemical concentrations indicates that there is
considerable uncertainty in this estimate. Given the available data, it is not possible
to quantify the magnitude or direction of this uncertainty with respect to
protectiveness. Indeed, only two facilities in the sample population had potential
exceedances for reported concentrations. The impact of our assumption that the
receptor is located along the centerline of the air plume suggests that the risk
estimates may be overprotective.
• Multiple Constituent Exposures. The risk of each constituent is considered separately
in this analysis, and this may overlook additive or possible synergistic effects. This is
a potential underestimation of adverse effects.
• Chemical-Physical Properties. IWAIR did not include all of the constituents of
interest in this study that had inhalation benchmarks. Therefore, 25 additional
constituents were added to IWAIR. However, adequate chemical-physical properties
to run IWAIR were not available for 12 of these constituents. To the extent that these
constituents may pose risks, this results in an underestimate of risk.
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March 26, 2001 Appendix C
• Health Benchmarks. Many constituents in the scope of this study do not have health
benchmarks for inhalation. This limited the number of constituents and facilities for
which it was possible to assess inhalation risks. The absence of an inhalation health
benchmark is generally taken as an indication that the constituent is not of great
concern by the inhalation pathway; however, there is some uncertainty in this
assumption. If health benchmarks were available for inhalation, a few more
constituents might be found to pose risks; therefore, this uncertainty tends to result in
an underestimate of risk.
C. 1.6 Phase IC/II: Risk Modeling— Groundwater Pathway
C. 1.6.1 Methods Summary and Key Results. In the risk modeling of the groundwater
pathway, EPA evaluated the risk to a person drinking contaminated groundwater from the well
located nearest to an impoundment that exceeded the risk criteria during the release assessment.
Chemicals may reach a receptor well by leaching through the bottom of the impoundment into
groundwater and migrating downgradient to residences that rely on drinking water wells. The
potential for direct exposure to constituents via the groundwater pathway was assessed in three
phases, each designed to be more protective than the previous phase. The first phase, direct
exposure pathway screening, compared estimated leachate concentrations to screening factors for
drinking water ingestion. The second phase, screening-level modeling, calculated risks and
hazard quotients using EPA's IWEM. The third phase, site-based risk modeling, identified
facility and impoundment combinations that have the greatest potential to impact receptor wells,
and performed a Monte Carlo simulation to derive a site-specific distribution of risk for the
nearest receptor well at each facility that was determined to be high priority for modeling.
The facilities were chosen for risk modeling using three basic decision rules:
• EPA evaluated the 71 facilities that exceeded risk criteria based on the IWEM Tier 1
screening analysis to determine if the potential exists for direct exposure to
contamination via the groundwater pathway.
• EPA assumed the potential for exposure by determining if drinking water wells were
present in the downgradient direction of groundwater flow.
• If receptor wells were not present, or if the receptor wells were determined not to be
downgradient of the surface impoundment, EPA presumed the pathway to be
incomplete and excluded the site from further evaluation.
For those facilities that were not excluded, two sets of criteria were developed and used to
identify which facilities required site-based modeling. The first set of criteria focused on
environmental setting characteristics (e.g., distance to receptor well), and the second set of
criteria relied on professional judgment (e.g., conductivity of aquifer material). Each set of
criteria and the method in which they were applied are described in Attachment C-8. Application
of the two sets of ranking criteria resulted in the selection of 10 facilities that were considered the
highest priority for site-based groundwater modeling. Site-based modeling involved assessing
the fate and transport of chemical constituents present in surface impoundments by performing a
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Appendix C
Monte Carlo simulation using EPACMTP and feeding the groundwater concentrations into a
Monte Carlo exposure/risk simulation that varied human health exposure factors.
Table C.I-14 presents the results for the groundwater pathway with facilities classified
according to waste characterization categories. Table C. 1-15 presents this same information
according to whether the source concentration data were based on reported values or
surrogate/DL values. The complete risk results, standard errors, and additional descriptors on
regulatory status (direct vs. zero dischargers) and impoundment characteristics (e.g., liner vs. no
liner) are presented in Attachment C-12.
Table C.l-14. Facility-Level Overview of Human Health Risk Results for
Groundwater Pathway by Decharacterization Status
Facility Status
Never Characteristic
Decharacterized
All Facilities
Below Risk
Criteria
2,574
71%
345
42%*
2,919
65%
(58%)
88%
(8%)
12%
(65%)
100%
Environmental Release3
All Values
1,055
29%
(24%)
71%
432 (10%)
53%
1,488
33%
29%
(33%)
100%
Exceeds Risk Criteria3
All Values
9* (0
0.3%*
2%*)
18%*
41* (0.9%)
5%*
50*
1%
82%*
(1%)
100%
Total
3,638
100%
(82%)
82%
818 (18%)
100%
18%
4,457 (100%)
100%
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
The results of the groundwater pathway analysis indicate that less than one percent of the
facilities nationally that manage chemical constituents with reported values may exceed risk
criteria for groundwater ingestion. Both tables suggest that facilities that manage decharacterized
waste may potentially pose two to five times the risk of facilities that manage only waste that has
never been characteristic.
C.I. 6.2 Discussion of Uncertainty. In its assessment of the groundwater pathway, EPA
relied on modeling tools that have been peer-reviewed and used in previous analyses, as much
site-specific data as possible from the surveys, and standard EPA sources for important data such
as exposure factors and health benchmarks. All of these factors contributed to a relatively robust
analysis that met the study objectives of the Surface Impoundment Study. This section identifies
the primary sources of uncertainty and qualitatively describes how each may influence the results
of the risk assessment.
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Appendix C
Table C.l-15. Facility-Level Overview of Human Health Risk Results for Groundwater
Pathway by Decharacterization Status—Reported Values and Surrogate/DL Values
Facility Status
Never Characteristic
Decharacterized
All Facilities
Below Risk
Criteria
2,574 (58%)
71%
345 (
42%*
88%
8%)
12%
2,919 (65%)
65%
100%
Environmental Release a
Reported
Values
341* (8%)
9%
53%*
300 (7%)
37%
47%*
641 (14%)
14%
100%
Surrogate/
DL Values
714 (16%)
20%
84%*
132* (3%)
16%
16%*
846 (19%)
19%
100%
Exceeds Risk Criteria3
Reported
Values
9* (0
0.3%*
2%*)
33%*
18* (0.4%)
2%*
67%*
27* (0.6%)
0.6%
100%
Surrogate/
DL Values
0 (0%)
0%
0%
23* (0.5%)
3%*
100%
23* (0.5%)
0.5%
100%
Total
3,638
100%
(82%)
82%
818 (18%)
100%
18%
4,457 (100%)
100%
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
DL = Detection limit.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A.5 for details.
Parameter Uncertainties. The sources of parameter uncertainty include measurement
errors, sampling errors, variability, and use of generic or surrogate data. Parameter uncertainty
was incorporated in the Surface Impoundment Study by (1) executing a Monte Carlo analysis to
capture the natural variability present in nature, and (2) using a regional site-based modeling
approach that relied on data compiled at actual waste sites around the country. The critical
parameters required for the screening of groundwater pathway included the distribution
coefficients (Kd) and model parameter inputs.
• Distribution Coefficients. Empirical data were used to characterize partitioning of
chemical contaminants between the aqueous phase and soil and aquifer materials.
The Kd values used in the Surface Impoundment Study are based on values
compiled from the literature. The values for all constituents are assumed to range
over at least 3 orders of magnitude. For values with five or fewer literature values
available for establishing a distribution of Kd values, a lognormal distribution was
assumed centered on the mean value of the available log Kds and extending for 1.5
log units on each side of the log mean. This uncertainty could result in either an
underestimation or an overestimation of risk.
• Model Input Parameters. Application of the EPACMTP model requires input
values for the source-specific, chemical-specific, unsaturated zone-specific, and
saturated zone-specific model parameters. For this analysis, facility-specific
values for impoundment location and waste, soil, and aquifer characteristics were
used to the extent possible. Where facility-specific data were not available,
regional databases were used to obtain the parameter values for soil and aquifer
conditions. The use of facility-specific data reduces, but does not eliminate,
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uncertainty. Use of regional databases may result in a greater spread of risks in
Monte Carlo analyses.
• ToxicologicalEndpoint for Fluoride. The chemical that exceeds the risk criterion
most often in the groundwater pathway assessment is fluoride. This is one of the
two chemicals for which risk modeling indicates exceedances that are based on
reported chemical concentrations. However, the endpoint of interest is currently
dental fluorosis, an endpoint that is not considered to be an adverse effect by EPA.
Although safe levels for fluoride of skeletal fluorosis are within a factor of 2 of
the RfD for fluoride, there is considerable uncertainty in this value because there
has been no formal workgroup process to derive a health benchmark.
Model Uncertainties. Model uncertainty is associated with all models used in all phases
of a risk assessment because models and their mathematical expressions are simplifications of
reality that are used to approximate real-world conditions, processes, and their relationships.
Models used in the Surface Impoundment Study were selected based on science, policy, and
professional judgment. These models were selected because they provide the information needed
for this analysis and because they are generally considered to be state-of-the-science. Even
though the models used in the risk analyses are used widely and have been accepted for
numerous applications, they each retain significant sources of uncertainty. Evaluated as a whole,
the sources of model uncertainty in this analysis could result in either an overestimation or
underestimation of risk. Specific areas of modeling uncertainty in this analysis are as follows:
• Channel Flow. In modeling the fate and transport of chemicals in groundwater,
complex hydrogeology such as karst or highly fractured aquifers was not assessed.
Some fraction of the groundwater settings in this analysis are located in
hydrogeologic environments where fracturing is likely. In general, fractured flow
in groundwater can channel the contaminant plume, thus allowing it to move
faster and in a more concentrated state than in a nonfractured flow environment.
As a result, the modeling may under- or overestimate the concentrations in the
groundwater.
• Model Simplifications. EPACMTP does not model colloidal transport nor does it
model possible geochemical interactions among different contaminants in the
leachate and the subsurface environment. The EPACMTP modeling incorporates
the following assumptions: (1) transverse dispersion is negligible in the
unsaturated zone, potentially resulting in an overestimation of risks; (2) receptors
use the uppermost aquifer rather than a deeper aquifer as a domestic source of
drinking water, which overestimates risks where the uppermost aquifer is not
used;8 and (3) hydrogeologic conditions that influence contaminant fate and
Note that, for some facilities, EPA used technical materials supplied by the survey respondents to confirm
that the uppermost aquifer was not used as a drinking water source. This information was entered in the numeric
ranking scheme and used to identify facilities that were not considered to be a high priority with respect to potential
groundwater risks.
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transport are uniform spatially (i.e., no heterogeneity or fractured flow) as well as
uniform temporally (i.e., over the 10,000-year time frame modeled). The use of
these simplifications may result in a greater estimated spread of concentrations in
the groundwater.
• Groundwater Mounding. Groundwater flow in the saturated zone is based on the
assumption that the contribution of recharge from the unsaturated zone is small
relative to the regional flow in the aquifer and the saturated aquifer thickness is
large relative the rise due to infiltration. This assumption allows for the saturated
zone to be modeled as having a uniform thickness (i.e., in the absence of
mounding). The use of this simplification may result in a greater estimates spread
of concentrations in the groundwater.
• Recharge Rate. The recharge rates used in this analysis were developed based on
analyses that rely on regionalized climatic data and generalized soils types. These
are not site-specific data but are intended to represent the range of conditions
expected in the area. Although the model accounts for uncertainty using a
probabilistic simulation, the recharge rates are not site-specific and may over- or
underpredict the contaminant flux to groundwater.
• Time frame of Exposure. There is uncertainty in predicting the movement of
contaminants over long periods of time. The risk to receptors for the groundwater
pathway was evaluated over a time period of 10,000 years. Depending on the
constituent properties and rate as which it moves in groundwater, the time to peak
concentration may be relatively long, on the order of hundreds or thousands of
years. There are significant uncertainties concerning how exposure and
environmental assumptions will change over time, and the modeling methodology
does not change these assumptions over this 10,000-year period. As a result,
groundwater concentrations may be under- or overestimated.
Results Uncertainties. It is important to consider several key uncertainties in
interpreting the significance of the groundwater pathway results. The greatest uncertainty is
focused around assumptions made in defining the geometric configuration of the modeled
system, specifically, with regard to the groundwater flow direction and well construction. In
addition, the risk results for reported values are based entirely on two chemical constituents:
fluoride and acetone. As discussed above, the fluoride hazard is based on an effect that is not
considered adverse by EPA, and the recommended safe value by EPA is approximately two times
the health benchmark. Given the fact that fluoride is the risk driver for the entire groundwater
pathway assessment and that the 90th percentile hazard quotient for acetone is 13 (50th percentile
hazard quotient is 0.02), the groundwater hazard estimates may tend to be overprotective of
actual adverse effects. Other uncertainties are discussed below.
• Groundwater Flow Direction. The direction of groundwater flow was not
provided in the survey responses. Because the exact direction of the groundwater
flow was unknown, the actual receptor well locations in the general the direction
of the groundwater flow, as well as the physiography of the site were used to
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define the angle "THETA." For each surface impoundment, THETA sets the
bounds for the true direction of groundwater flow and, therefore, captures the
uncertainty in centerline for groundwater flow and contaminant movement
relative to the nearest receptor well to the impoundment. The error margin for
THETA was based on professional judgment and was set to 5 degrees for all
facilities evaluated in the risk modeling. The impact of this geometrical
inexactitude is considered to be much smaller than the impact of several other
uncertainties in the groundwater pathway analysis.
• Well Construction. The aquifer from which receptor wells drew water was not
consistently reported in survey results. In the absence of technical information
from the survey respondents indicating a site-specific well depth, it was assumed
that the receptor wells considered in this analysis drew water from the uppermost
unconfmed saturated zone. This is a protective assumption and would tend to
overestimate risk.
• Volatilization. The evaluation of the groundwater pathway was focused only on
the ingestion of contaminated groundwater. EPA did not address volatilization of
chemical constituents in groundwater that may result in inhalation exposures
during showering. Because the inhalation pathway associated with shower
exposure was not modeled, the groundwater pathway risk results may
underestimate the total risk from leaching to groundwater. This contributes to the
uncertainty in the risk estimates in the direction of underprotectiveness.
C. 1.7 Phase IC/II: Risk Modeling—Groundwater to Surface Water Pathway Screening
C. 1.7.1 Methods Summary and Key Results. In the risk modeling of the groundwater to
surface water pathway, EPA evaluated the potential for degradation of surface water quality with
respect to human usage. The basic approach to evaluating the potential for risks by this pathway
was first to identify high-priority sites through a screening process (that considered groundwater
concentrations, proximity to surface waterbodies, and the magnitude of potential dilution). For
high-priority sites, modeling was conducted to generate flux rates from the surface
impoundments, estimate groundwater concentrations that might contaminate the surface
waterbody, and model the ensuing dilution. This analysis was conducted on all facilities that
reported the presence of in-scope constituents. The basic steps in the assessment of this pathway
were to
• Identify sites near (within 1 km) one or more fishable waterbodies
• Eliminate facilities from consideration based on a comparison of leachate
concentrations to the ambient water quality criteria for the ingestion of surface
water and aquatic organisms (HH-AWQC)
• For those that were not eliminated, estimate groundwater concentrations (from
DAFs) and compare these to the HH-AWQC. The DAFs used were intended to
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Appendix C
provide estimates of groundwater concentrations toward the high end of the
possible distribution
• Using site-specific data (such as surface impoundment area) and reviewing
topographical maps, identify sites with a high potential to impact surface water.
Typically, this was based on a low probability of dilution by the surface
waterbody based on flow data for the closest waterbody
• Conduct screening-level risk modeling using site-generated infiltration rates and
flow rates for receiving waterbodies to estimate of chemical concentrations in
surface water, and compare the resulting values to the HH-AWQC.
Table C.l-16 presents the results for the groundwater pathway with facilities classified
according to waste characterization categories. Table C. 1-17 presents this same information
according to whether the source concentration data were based on reported values or
surrogate/DL values. The complete risk results, standard errors, and additional descriptors on
regulatory status (direct vs. zero dischargers) and impoundment characteristics (e.g., liner vs. no
liner) are presented in Attachment C-15.
Table C.l-16. Facility-Level Overview of Human Health Risk Results for
Groundwater to Surface Water Pathway by Decharacterization Status
Facility Status
Never Characteristic
Decharacterized
All Facilities
Below Risk
Criteria
2,203 (49%)
61%
88%
310 (7%)
38%
12%
2,513 (56%)
56%
100%
Environmental Release3
All Values
1,397 (31%)
38%
75%
472 (11%)
58%
25%
1,869 (42%)
42%
100%
Exceed Risk Criteria3
All Values
38* (0.9%)
1%
52%*
36* (0.8%)
4%*
48%*
75* (2%)
2%
100%
Total
3,638 (82%)
100%
82%
818 (18%)
100%
18%
4,457 (100%)
100%
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
a Number of facilities (percentages are of the total number of facilities,
* This estimate may not be reliable because of a large relative standard
* This estimate may not be reliable because of a large relative standard
approximately 4,500).
error. See Appendix A.5 for details.
error. See Appendix A.5 for details.
The results of the groundwater to surface water pathway analysis indicate that
approximately 1 percent of the facilities nationally that manage chemical constituents with
reported values may exceed risk criteria for adverse surface water impacts. The results are
similar for risk exceedances predicted using surrogate/DL-based chemical concentrations. The
overall trend using both types of concentration data does not indicate that decharacterized
facilities are associated with higher potential risks than facilities that manage only never
characteristic waste.
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Appendix C
Table C.l-17. Facility-Level Overview of Human Health Risk Results for the Surface
Water Pathway by Decharacterization Status - Reported Values and Surrogate/DL Values
Facility Status
Never Characteristic
Decharacterized
All Facilities
Below Risk
Criteria
2,203
61%
310
38%
2,513
56%
(49%)
88%
(7%)
12%
(56%)
100%
Environmental Release3
Reported
Values
479 (11%)
13%
311
38%
61%*
(7%)
39%*
790 (18%)
18%
100%
Surrogate/
DL Values
918 (21%)
25%
85%
161 (4%)
20%
15%
1,079 (24%)
24%
100%
Exceed Risk Criteria3
Reported
Values
29* (0.7%)
0.8%
67%*
14* (0.3%)
2%*
33%*
44* (1.0%)
1.0%
100%
Surrogate/
DL Values
9* (0
0.3%*
2%*)
30%*
22* (0.5%)
3%*
70%*
31* (0.7%)
0.7%
100%
Total
3,638
100%
(82%)
82%
818 (18%)
100%
18%
4,457 (100%)
100%
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
DL = Detection limit.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
C.I. 7.2 Discussion of Uncertainty. There are several key uncertainties that should be
considered in interpreting the results of the surface water quality screening assessment. These
are grouped under parameter uncertainties, modeling uncertainties, and results uncertainties.
This section identifies these sources of uncertainty and qualitatively describes how each may
influence the results.
Parameter Uncertainties. The critical parameters required for the screening modeling
of surface waterbodies included flow rates and DAFs.
• Flow Rates. Flow rates were a potentially significant source of uncertainty; the
low flow rate (7Q10) was often greater than the average flow rate, suggesting that
the data sources were highly variable. In addition, many flow rate estimates are
based on end-of-stream locations, which could be a substantial distance from the
point at which the groundwater could reasonably be expected to intersect with the
surface waterbody. Consequently, the river dilution factor calculated from the
flow rate may be highly uncertain.
• Dilution Attenuation Factors. For surface waterbodies within 150 meters, a
default DAF of 1.0 was chosen. This value tends to overestimate the contaminant
flux in groundwater that reaches the surface waterbody. The DAFs in IWEM
were used for waterbodies beyond 150 meters and, as with the default DAF, these
were developed for a protective groundwater screening tool. The resulting
groundwater concentrations will generally lead to an overprediction of the
contaminant concentration in the surface waterbody.
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Modeling Uncertainties. The screening modeling for the groundwater to surface water
pathway simplifies the fate and transport of chemicals from groundwater to surface water and is
based on several protective assumptions. These simplifications generally rely on protective
assumptions and, as a result, the modeling approach tends to overpredict the potential effects on
water quality.
• Groundwater Flow Direction. For the surface water screening, groundwater flow
direction was inferred from the topography, and a plausible groundwater flow
direction was established perpendicular to the receiving waterbody—either a
flowing waterbody or a quiescent system such as a small pond. In addition, the
plume was assumed to completely intersect with the waterbody so that the
groundwater would exert the maximum impact on the surface waterbody. The
combination of these assumptions creates a bias toward higher surface water
concentrations.
• Designation of Fishable Waterbody. The closest fishable waterbody was
identified for each impoundment based on both survey responses and simple
decision rules (e.g., a reach order of 3 or above is presumed to be fishable).
However, there may be substantial uncertainty in this selection because, in many
instances, survey responses were not useful in identifying the closest fishable
waterbody.
• Infiltration Rates. The infiltration rates used in this analysis were developed
using the HELP model using regionalized climatic data and generalized soils data.
These are not site-specific data but are intended to represent the range of
conditions expected in the area. Although the model accounts for uncertainty
using a probabilistic simulation, the infiltration rates are not site-specific and may
over- or underpredict the contaminant flux to groundwater.
Results Uncertainties. It is important to consider several key uncertainties in interpreting
the significance of the surface water pathway results. The modeling approach is based on the
assumption of instantaneous and thorough dilution throughout the surface waterbody, which
would create a constant exposure profile for human usage throughout the entire receiving
waterbody. In reality, contaminant release into the surface waterbody through this pathway
would likely be associated with a concentration gradient that would vary the exposure pattern
throughout the length of the waterbody. In many instances, only a small portion of the receiving
waters may actually maintain chemical concentrations above the HH-AWQC. For the highest
area of contamination (perhaps a "favorite" fishing spot), the dilution may mask a potentially
adverse impact on surface water quality. It should be noted that the HH-AWQC used in this
analysis are based on the consumption of aquatic organisms and surface water. In reality, the
percentage of the population that consumes untreated surface water on a regular basis is very
small. Therefore, the selection of the HH-AWQC for the ingestion of both aquatic organisms
and surface will tend to produce an overestimate of the potential risks to surface water quality
(relative to the actual usage of receiving waterbodies). The results of this analysis suggest that,
despite the proximity of receiving waterbodies to surface impoundments, the risks from adverse
effects to surface water quality are generally low nationwide.
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A second potentially important source of uncertainty in the national risk estimates is
based on the fact that HH-AWQC exceedances greater than a factor of 10 were observed for only
one facility, and the only constituent with reported concentrations was arsenic. This finding in
no way mitigates that risk potential at that particular facility. However, given the generally
protective design of the screening risk modeling for this pathway, it is conceivable that this is the
only facility (182) for which surface water impacts are of potential significance. Two other key
uncertainties are worth considering when interpreting these results:
• Data Gaps. The screening criteria (HH-AWQC) selected for this analysis were
identified in EPA's compilation of national recommended water quality criteria
developed pursuant to section 304(a) of the Clean Water Act. An HH-AWQC
was not available for all of the constituents that failed the preliminary screen and,
therefore, the results may not capture impacts from all chemicals that may be
released through this pathway.
• Additive/Synergistic Effects. The screening modeling does not address the
possibility that other contaminant sources may be releasing the similar chemical
constituents into the same waterbody. For waterbodies that are already receiving
significant contaminant loads of the similar chemicals (or synergistic chemicals),
the chemical release from an impoundment may be a significant contributor to
water quality degradation.
C.I.8 Phase IC/II: Indirect Exposure Pathway Assessment
C.I.8.1 Methods Summary and Key Results. To characterize the potential for indirect
exposures at facilities that manage bioaccumulative chemicals at in-scope surface
impoundments, EPA conducted an indirect exposure pathway (IEP) screening analysis that used
a combination of facility-specific and environmental setting criteria to assign each facility to one
of three categories regarding the potential for indirect exposure pathway risk:
• Potential concern - The potential exists for indirect exposure pathway risk.
• Lower concern - There is a lower potential for indirect exposure pathway risk.
• Least concern - The analysis suggests that these facilities have the least potential
for indirect exposure pathway risk.
In order for a facility to be placed in the category with the highest level of concern (i.e.,
the potential concern category), the IEP screening analysis had to suggest that the potential exists
for indirect exposure pathway risk under current site conditions. Consequently, overall rankings
for the facilities were assigned based on a current status scenario, which was designed to
represent current conditions at the facilities. A future closure scenario was also included in the
analysis to provide perspective on the number of facilities that had the potential to pose risk
through an indirect exposure pathway after impoundment closure. This future closure scenario
analysis was based on precautionary assumptions concerning postclosure actions and,
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Appendix C
consequently, the results of the analysis were used only to qualify the results of the current status
scenario (i.e., future closure results were not used in assigning overall rankings to the facilities).
The IEP analysis considered a set of exposure pathways, each linked to a specific release
scenario and receptor population. For example, the analysis considered volatilization of
chemicals from impoundments with subsequent transport to offsite residential home gardens (this
represented a specific exposure pathway that was evaluated for the resident receptor population).
Each of these exposure pathways was evaluated using a specific set of facility-specific and
environmental setting criteria, which in turn, were used in a ranking algorithm to generate the
overall ranking for that exposure pathway regarding the potential for indirect exposure pathway
risk. Once all exposure pathways were evaluated for a given facility, those rankings were
reviewed and an overall ranking was given to that facility for the IEP screening analysis. As
noted above, these overall rankings were based only on the current status scenario.
Table C.l-18 presents the results for the indirect exposure pathway assessment with
facilities classified according to waste characterization categories. Because the results of this
assessment do not include quantified risk estimates that are chemical- and impoundment-specific,
these results are not presented according to facilities with reported values or surrogate/DL values.
The complete risk results, standard errors, and additional descriptors such as regulatory status are
presented in Attachment C-18.
Table C.l-18. Facility-Level Overview of Human Health Risk Results for
Indirect Exposure Pathway Assessment by Decharacterization Status
Facility Status
Never characteristic
Decharacterized
All facilities
Least
Concern3
1,369 (31%)
38%*
88%
183 (4%)
22%
12%
1,552 (35%)
35%
100%
Lower
Concern3
2,153 (48%)
59%*
82%
466 (10%)
57%
18%
2,620 (59%)
59%
100%
Potential
Concern3
116* (3%)
3%
41%*
169 (4%)
21%
59%*
285 (6%)
6%
100%
Total
3,638 (82%)
100%
82%
818 (18%)
100%
18%
4,457 (100%)
100%
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
The results of the IEP screening analysis indicate that approximately 6 percent of the
facilities nationally that manage bioaccumulative chemical constituents may present potential
concern via indirect exposures. The overall results do not indicate that decharacterized facilities
are associated with higher potential risks than facilities that manage only never characteristic
waste.
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C.I.8.2 Discussion of Uncertainty. The qualitative character of the indirect exposure
pathway analysis leads to several major areas of uncertainty that affect interpretation of the
results. These are grouped under parameter uncertainties, modeling uncertainties, and results
uncertainties.
Parameter Uncertainties. Key parameters required for this analysis fall into one of two
broad categories: facility performance parameters and environmental setting parameters. Various
sources of uncertainty can impact each of these parameters. Those parameter uncertainties that
are believed to have the greatest potential impact on the indirect exposure pathway screening
assessment are discussed below.
• Distance to nearest receptor: The distance between specific impoundments and
the nearest receptor (i.e., residential areas, farms, or fishable waterbodies) was
estimated using a combination of aerial photos and topographic maps. Although
these measurements were made using the most up to-date photos and maps
available, some of the photos and maps were somewhat dated. This introduces
uncertainty in the distance to nearest receptor measurements since land use change
could result in a receptor either being added to or removed from a given study
area (note, this is less of an issue in identifying fishable waterbodies).
• Assessment of potential for erosion/runoff. Topographic maps used to assess slope
and the potential for sheet versus channel flow may not be current, in which case
significant changes in land use (which would not show up on older maps) could
introduce error into the characterization of this parameter.
Modeling Uncertainties. The indirect exposure pathway screening assessment is a
facility-level evaluation intended to rank facilities according to their potential for complete
indirect exposure pathways. This analysis uses a ranking algorithm together with facility-specific
and environmental setting criteria to generate overall ranking scores for individual exposure
pathways. The criteria used in this analysis were selected as surrogates for key factors related to
human health risk (e.g., impoundment surface area was used as a surrogate for level of chemical
emissions, distance to receptor was used as a surrogate for level of dispersion following source
release). The use of these surrogate parameters as criteria in the ranking algorithms for
individual exposure pathways, while appropriate given the screening-nature of the analysis, does
introduce modeling uncertainty into the analysis. In addition, there are uncertainties associated
with the ranking algorithms used in the anlaysis.
• Use of ranking algorithms: The ranking algorithm used in this analysis assumes
an additive relationship between the criteria that are considered. However, in
relation to actual risk, these criteria may have multiplicative or even nonlinear
relationships to each other, in which case the overall importance of individual
criteria could be misrepresented in the ranking algorithm.
• Use of surface area as a surrogate parameter. Total aggregated impoundment
surface area for a given facility was used as a surrogate for the level of constituent
emissions from that facility. However, a wide range of factors can influence the
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degree of source emissions from an impoundment including chemical
composition of the wastewater/sludge and other environmental
setting/impoundment characteristics. Consequently, use of surface area as a
surrogate for emissions levels does introduce uncertainty into the analysis.
• Use of distance to receptor as a surrogate parameter: The shortest distance from
any of the impoundments at a facility to the nearest offsite receptor (i.e., resident,
farmer, or fisher) was used as a surrogate for the degree of chemical dispersion
that would occur following release. However, a wide range of factors in addition
to distance to receptor can impact dispersion including meteorology, topography,
and the specific characteristics of the source release.
Results Uncertainties. The indirect exposure pathway screening analysis is designed to
identify which facilities have the potential to pose an indirect exposure pathway risk to
surrounding populations. Given this scope, the analytical framework for the indirect exposure
pathway screening analysis uses a combination of surrogate criteria and simple additive ranking
algorithms in place of a formal site-specific risk assessment framework to generate ranking
results. While this semiquantitative approach does support ranking of facilities with regard to the
potential for indirect exposure pathway risk, care should be taken not to overextend conclusions
drawn from the analysis. A similar issue applies to results produced for the current status
scenario versus future closure scenario.
• Drawing conclusions from the analysis: Because the IEP screening analysis uses
surrogate criteria combined with simple additive algorithms to rank facilities,
there is significant uncertainty associated with the overall analysis that should be
considered in interpreting results. While, this degree of uncertainty is considered
acceptable for a first-pass assessment as to whether individual facilities have the
potential for indirect exposure pathway risk, it precludes drawing any conclusions
regarding the potential level of risk that these facilities could pose.
• Current status scenario vs. future closure scenario results: There is significantly
greater uncertainty associated with results generated for the future closure
scenario than for the current status scenario. This discrepancy results from the
fact that the current status scenario is based on best available data regarding the
current status of modeled facilities, while the future closure scenario is not
intended as a "best guess" of future closure conditions at sites, but rather as a
protective analysis of the potential for indirect exposure pathway risk should
impoundments close without sufficient postclosure actions being taken to limit
constituent mobility. Reflecting this discrepancy in uncertainty, overall rankings
for the indirect exposure pathway screening analysis are based only on results for
current status scenario—results from the future closure scenario are not
considered in assigning these rankings. However, the results of the future closure
scenario could be used to qualify the results of the current status scenario since
they provide perspective on how many facilities could pose an indirect exposure
pathway risk should impoundment closure occur without remediation.
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C.I.9 Phase I: Preliminary Screen—Ecological Risk
C.I.9.1 Methods Summary and Key Results. The ecological risk screening is somewhat
different from the human health screening in that a single comparison of screening factors and
constituent concentrations was conducted. The screening ecological risk assessment focused on
a subset of 43 constituents for which toxicological and exposure factor data were readily
available. The habitats and receptors considered in this study are consistent with the national
assessment strategy developed to support HWIR, proposed in November 1999. Because the
HWIR risk assessment framework was intended to support national studies of waste management
practices, the SIS has adopted this framework as the basis for selecting receptors and habitats.
Depending on the ecological receptor of concern, the analysis estimated risks from either the
ingestion of contaminated plants, prey, and media or from direct contact with a contaminated
medium such as sediment or soil. The ecological risk estimates were compared to risk criteria to
characterize the potential for adverse ecological effects at facilities of interest.
As with the preliminary screening of noncancer hazard for human health, the ecological
screening analysis calculates risks to individual ecological receptors (e.g., red fox, aquatic biota)
based on the ratio between risk screening factors and the concentrations of constituents in surface
impoundments reported in the survey questionnaire. Consequently, ecological risk screening
factors are given in units of concentration (e.g., mg/kg or mg/L). The use of screening factors is
considered to be precautionary because the factors are
• Derived using established EPA protocols for use in evaluating ecological risk
(e.g., sediment quality criteria)
• Based on highly protective assumptions regarding the toxicological potency of a
constituent (e.g., no adverse effects levels and low adverse effects levels)
• Calculated assuming that all media and food items originate from a contaminated
source.
In addition, the application of the screening factors assumes that ecological receptors are exposed
directly to chemical concentrations in the sludge and wastewater found in the surface
impoundment. For mammals, birds, and selected herpetofauna, these screening factors reflect
ingestion of contaminated media, plants, and prey. For other receptor groups, such as soil fauna,
these screening factors reflect both the direct contact and ingestion routes of exposure.
Table C.l-19 presents the results for the indirect exposure pathway assessment with
facilities classified according to waste characterization categories. The categories for risk,
although similar to those used in the IEP screening analysis, have a specific meaning in the
context of the ecological risk assessment. The metric chosen to distinguish potential concern
from lower concern was the number of receptors for which chemical concentrations exceeded
ecological screening factors. The precautionary nature of the screening assessment resulted in a
high percentage of "failures," that is, facilities and impoundments for which the predicted hazard
quotient was greater than 1. Therefore, EPA used the median number of receptor of exceedances
(38) across all facilities evaluated to discriminate between potential concern and lower concern.
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Appendix C
Consequently, the national percentages shown in Table C. 1-19 for potential concern reflect the
potential for screening ecological risks to exceed the target criterion of 1 for more than 38
ecological receptors across various taxa. However, because the results of this assessment are
considered screening-level, they are not presented according to facilities with reported values or
surrogate/DL values. Table C.l-19 suggests that the majority of facilities have some potential for
adverse ecological effects, and somewhat less than one third of the facilities have a relatively
high level of potential concern based on the number of receptors for which risk exceedances were
predicted. There is an apparent trend with regard to decharacterization status in that almost four
times the number of facilities listed as of potential concern manage never characteristic waste.
Table C.l-20 provides insight into the ecological risks at facilities located near sensitive
habitats such as wetlands and/or managed areas (e.g., national wildlife refuges). This table
indicates that less than 10 percent of the facilities classified of potential concern are located
within 1 km of a wetland or 3 km of a managed area. This figure trebles (roughly 30 percent) if
the facilities classified as of lower concern are considered. Naturally, the "least concern"
category refers to facilities for which ecological risks were not predicted at levels of potential
concern. The complete risk results, standard errors, and additional descriptors such as regulatory
status are presented in Attachment C-23.
Table C.l-19. Facility-Level Overview of Human Health Risk Results for
Indirect Exposure Pathway Assessment by Decharacterization Status
Facility Status
Never Characteristic
Decharacterized
All Facilities
Least Concern3
594* (13%)
16%*
75%*
194 (4%)
24%
25%*
788 (18%)
18%
100%
Lower Concern3
2,007 (45%)
55%*
85%
352 (8%)
43%*
15%
2,359 (53%)
53%
100%
Potential Concern3
1,037 (23%)
28%
79%
273 (6%)
33%
21%
1,310 (29%)
29%
100%
Total
3,638 (82%)
100%
82%
818 (18%)
100%
18%
4,457 (100%)
100%
100%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
C.I.9.2 Discussion of Uncertainty. The screening nature of the analysis leads to several
major areas of uncertainty that affect interpretation of the results. These are grouped under
parameter uncertainties, modeling uncertainties, and results uncertainties.
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Appendix C
Table C.l-20. Facility-Level Results for Ecological Risk by Proximity
to Wetlands and Managed Areas
Facility Status
Wetland Within 1 km
Managed Area Within 3 km
Wetland Within 1 km
and
Managed Area Within 3 km
Least Concern3
105* (2%)
13%*
17%*
58* (1%)
12%*
8%*
9* (0.2%*)
17%*
1%*
Lower Concern3
460* (10%*)
56%*
19%*
326* (7%)
69%*
14%
5* (0.1%*)
9%*
0.2%*
Potential Concern3
263 (6%)
32%*
19%
92 (2%)
19%*
7%
40* (0.9%)
75%*
3%
Total
828 (19%)
100%
19%
476 (11%)
100%
11%
54* (1%)
100%
1%
Table key: Number of facilities (% of all facilities).
Row %, Column %.
a Number of facilities (percentages are of the total number of facilities, approximately 4,500).
* This estimate may not be reliable because of a large relative standard error. See Appendix A. 5 for details.
Parameter Uncertainties. The key parameters required for the ecological risk screening
include the list of ecological receptors assigned to each facility, dietary assumptions, and
ecological screening factors. As appropriate for screening-level analyses, the selection of
parameter values tends to support a protective assessment.
• Ecological Receptor Assignments. Ecological receptors were assigned at each
facility as a function of the land use patterns and presence of wetlands and/or
fishable waterbodies. This adds to the protective nature of the screening
assessment because not all facilities are located in areas of sufficient ecological
quality to sustain those receptors.
• Assumptions on Dietary Exposure. Screening-level assessments typically assume
exclusive intake of contaminated prey in the diets of primary and secondary
consumers (i.e., 100 percent of the diet originates from the contaminated area),
providing a very conservative estimate of potential risks.
• Conservatism of Screening Factors. Because the screening factors were generally
based on benchmarks for very low levels of effect for sensitive endpoints, these
factors tend to be very protective of wildlife species and natural communties.
Modeling Uncertainties. The screening ecological risk assessment did not involve fate
and transport modeling of chemical movement and uptake into plants and prey items.
Consequently, this direct exposure approach is protective in the sense that it implies actual usage
of the impoundment as habitat.
• Spatial Scale of Exposure. The screening level of resolution does not provide
insight into the scope/size of ecological impacts. The size of the contaminated
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area is a critical determinant of the risk results because larger areas dilute
chemical concentrations. Restricting the area to the impoundment tends to bias
the results toward an overestimate of risk.
• Temporal Scale of Exposure. The timing is assumed to include the entire life
stage of the wildlife species evaluated or, in the case of community-type receptors
(e.g., soil biota), a period that is relevant to the structure and function of the
community. The chronic, low-level exposure that this implies may be
underprotective of some species during sensitive lifestages or of short-lived
species.
• Constant Chemical Concentration. The chemical concentration was assumed to
be constant for the screening analysis when, in reality, the chemical concentrations
in plants, prey, and media will vary over time and space. A constant chemical
concentration will tend to overpredict the potential risks to wildlife.
• Chemical Behavior. For screening purposes, all forms of a constituent are
assumed to be equally bioavailable and toxic. This assumption may either
overestimate or underestimate the actual exposures, depending on the
environmental characteristics. For example, the form of arsenic (i.e., elemental,
ionic, and methylated) has been shown to influence toxicity profoundly.
• Single Chemical Exposures. The risk of each constituent is considered separately
in this analysis, and this may overlook possible synergistic effects. This is one
example of a potential underestimation of adverse effects.
Results Uncertainties. As with any screening ecological risk assessment, there is
considerable uncertainty in the risk results associated with simplifying assumptions and data
limitations such as ecological benchmarks. Moreover, the screening analysis does not address
the potential significance of predicted ecological impacts. Although the ecological risk results
indicate that the potential for adverse ecological effects exists at these facilities, it is not possible
to quantify that potential within the broader context of ecological health and sustainability.
Several key uncertainties to consider in interpreting the risk results are presented below.
• Concentration Data Source. A portion of the risk findings are based on surrogate
data and detection limits, rather than on reported concentrations, and this
contributes to the overall uncertainty in the results.
• Data Gaps. Protective ecological screening factors were developed for
constituents when sufficient data were available which, for this analysis, included
41 chemicals. The absence of benchmarks may lead to the underestimation of
risks associated with stressors for those chemicals that could not be evaluated.
• No Additional Stressors. The only stressor assumed in the screening analysis is
the introduction of chemicals into the environment. In the field, wildlife may be
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exposed to a variety of stressors (e.g., habitat alteration); therefore, the risk results
may underestimate the potential for adverse effects.
• Threatened/Endangered Species. Only common species were evaluated in this
analysis. The sensitivity of endangered species that are already under substantial
stress is not accounted for explicitly. Although the selection of screening
approach and parameters is inherently protective, it is possible that the results do
not capture the risks to sensitive species and habitats.
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C.2 Direct Exposure Pathway-Air
The air pathway considers the risk to a person (or receptor) inhaling air contaminated
with the chemicals present in surface impoundments. These chemicals reach the air by
volatilizing from the surface impoundment. They may then be transported some distance from
the impoundment before a person inhales them. The farther the person is from the impoundment,
the lower the concentration of the chemical in the air and the lower the risk.
C.2.7 Methods
C.2.1.1 Overview. The air pathway was assessed using several screening steps, each less
conservative than the previous. The first two steps, direct exposure pathway screening and
screening level modeling, are summarized in Section C.I.I; additional details are provided in the
Technical Plan (where they are referred to as Phase IA and IB, respectively). The third step,
Site-based Modeling, was not covered by the Technical Plan but is discussed here.
Although each of the screening steps is similar, for each successive step, the person
inhaling the air was placed farther from the impoundment and more site-specific data from the
SIS survey were used.
In the direct exposure pathway screening, data from the SIS survey on air concentration
of chemicals of concern in the air over the impoundment were used. A receptor was assumed to
inhale that concentration from childhood through adulthood. The air concentration data needed
for this step were not available from the survey for many impoundments and chemicals. If data
were not available or the risk calculated by this step for an impoundment and chemical exceeded
the risk criteria, which were 1E-5 for risk or 1 for HQ, they passed on to the next step.
In the screening level modeling, an air risk model called IWAIR (Industrial Waste Air
Model) was used. This model uses emissions data from the survey or, if no data are available,
estimates emissions from concentration and other site-specific data from the SIS survey. IWAIR
then estimates the concentration in air at some distance from the impoundment. The farther from
the impoundment, the lower the air concentration. In this step, a distance of 25 m was used. The
person inhaling the chemicals was assumed to do so for 30 years, starting in childhood. Site-
specific data from the survey were used for the model inputs that most affect the results,
including the size of the impoundment, where it is located, and whether it is aerated.
In the site-based modeling, IWAIR was used again, with the same site-specific data as
before, but with the receptor placed at the actual distance to the nearest residence for each
impoundment (taken from the survey). This was typically more than the 25 m used in the
previous step, so the risk was typically lower than in the screening level modeling step.
Because the data on distance to nearest residence were sometimes incomplete or based on
old maps, census data and aerial photos that were acquired from the United States Geological
Survey (USGS) were used as a check on the distance to the nearest residence. The distance to
the nearest populated census block was used to identify sites that might change from being below
risk criteria to exceeding risk criteria if there were residences nearer than the survey data
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suggested. For those sites, aerial photos were examined. In most cases, the aerial photos
confirmed the nearest residence location reported in the survey. When they did not, the receptor
distance was updated based on the aerial photo, and the risk was recalculated.
C.2.1.2 IWAIR. IWAIR is an interactive computer program with three main components:
an emissions model, a dispersion model to estimate fate and transport of constituents through the
atmosphere and determine ambient air concentrations at specified receptor locations, and a risk
model to calculate the risk to exposed individuals. IWAIR can model four types of waste
management unit, but only the surface impoundment component was used for this study. IWAIR
requires only a limited amount of site-specific information, including facility location,
impoundment characteristics, waste characteristics, and receptor information. IWAIR was
modified for this study to bypass the interactive user interface and read data compiled from the
surface impoundment survey directly from a database.
A brief description of each component and other modifications made to IWAIR for this
study follows. The IWAIR Technical Background Document (U.S. EPA, 1998b) contains a more
detailed explanation of the IWAIR model.
Emissions Model. The emission model uses waste characterization, impoundment, and
facility information to estimate emissions for 95 constituents identified in Table C.2-1. The
emission model incorporated into IWAIR is EPA's CHEMDAT8 model. This model has
undergone extensive review by both EPA and industry representatives and is publicly available
from EPA's web page. For this study, data on 13 additional chemicals, identified in Table C.2-2,
were added to IWAIR. These chemicals represent the chemicals reported in the survey that were
not already in IWAIR and that have inhalation health benchmarks and sufficient chemical-
physical properties data to be modeled using IWAIR.
Table C.2-1. Constituents Included in IWAIR
CAS No. Chemical Name
75070 Acetaldehyde
67641 Acetone
75058 Acetonitrile
107028 Acrolein
79061 Acrylamide
79107 Acrylic acid
107131 Acrylonitrile
107051 Allyl chloride
62533 Aniline
71432 Benzene
92875 Benzidine
50328 Benzo(a)pyrene
75274 Bromodichloromethane
106990 Butadiene, 1,3-
75150 Carbon disulfide
(continued)
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Table C.2-1. (continued)
CAS No. Chemical Name
56235 Carbon tetrachloride
108907 Chlorobenzene
124481 Chlorodibromomethane
67663 Chloroform
95578 Chlorophenol, 2-
126998 Chloroprene
10061015 cis-l,3-Dichloropropylene
1319773 Cresols (total)
98828 Cumene
108930 Cyclohexanol
96128 Dibromo-3-chloropropane, 1,2-
75718 Dichlorodifluoromethane
107062 Dichloroethane, 1,2-
75354 Dichloroethylene, 1,1-
78875 Dichloropropane, 1,2 -
57976 Dimethylbenz[a,h]anthracene, 7, 12-
95658 Dimethylphenol, 3,4-
121142 Dinitrotoluene, 2,4-
123911 Dioxane, 1,4-
122667 Diphenylhydrazine, 1,2-
106898 Epichlorohydrin
106887 Epoxybutane, 1,2-
111159 Ethoxyethanol acetate, 2-
110805 Ethoxyethanol, 2-
100414 Ethylbenzene
106934 Ethylene dibromide
107211 Ethylene glycol
75218 Ethylene oxide
50000 Formaldehyde
98011 Furfural
87683 Hexachloro-1,3-butadiene
118741 Hexachlorobenzene
77474 Hexachlorocyclopentadiene
67721 Hexachloroethane
78591 Isophorone
7439976 Mercury
67561 Methanol
110496 Methoxyethanol acetate, 2-
109864 Methoxyethanol, 2-
74839 Methyl bromide
74873 Methyl chloride
78933 Methyl ethyl ketone
108101 Methyl isobutyl ketone
80626 Methyl methacrylate
1634044 Methyl tert-butyl ether
56495 Methylcholanthrene, 3-
(continued)
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March 26, 2001 Appendix C
Table C.2-1. (continued)
CAS No. Chemical Name
75092 Methylene chloride
68122 N,N-Dimethyl formamide
91203 Naphthalene
110543 n-Hexane
98953 Nitrobenzene
79469 Nitropropane, 2-
55185 N-Nitrosodiethylamine
924163 N-Nitrosodi-n-butylamine
930552 N-Nitrosopyrrolidine
95501 o-Dichlorobenzene
95534 o-Toluidine
106467 p-Dichlorobenzene
108952 Phenol
85449 Phthalic anhydride
75569 Propylene oxide
110861 Pyridine
100425 Styrene
1746016 TCDD, 2,3,7,8 -
630206 Tetrachloroethane, 1,1,1,2-
79345 Tetrachloroethane, 1,1,2,2-
127184 Tetrachloroethylene
108883 Toluene
10061026 trans-l,3-Dichloropropylene
75252 Tribromomethane
76131 Trichloro-l,2,2-trifluoroethane, 1,1,2-
120821 Trichlorobenzene, 1,2,4-
71556 Trichloroethane, 1,1,1-
79005 Trichloroethane, 1,1,2-
79016 Trichloroethylene
75694 Trichlorofluoromethane
121448 Triethylamine
108054 Vinyl acetate
75014 Vinyl chloride
1330207 Xvlenes
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Table C.2-2. Constituents Added to IWAIR for Surface Impoundment Study
CAS No.
Chemical Name
542881 Bis(chloromethyl)ether
75343 Dichloroethane, 1,1-
76448 Heptachlor
319846 Hexachlorocyclohexane, alpha-
319857 Hexachlorocyclohexane, beta-
55684941 Hexachlorodibenzofurans [HxCDFs]
34465468 Hexachlorodibenzo-p-dioxins [HxCDDs]
30402154 Pentachlorodibenzofurans [PeCDFs]
1336363 Polychlorinated biphenyls
55722275 Tetrachlorodibenzofurans [TCDFs]
41903575 Tetrachlorodibenzo-p-dioxins [TCDDs]
8001352 Toxaphene
88062 Trichlorophenol. 2.4.6-
Dispersion Model. IWAIR's second modeling component estimates dispersion of
volatilized contaminants and determines air concentrations at specified receptor locations, using
default dispersion factors developed with EPA's Industrial Source Complex, Short-Term Model,
version 3. ISCST3 was run to calculate dispersion for a standardized unit emission rate
(1 |ig/m2-s) to obtain a unitized air concentration (UAC), also called a dispersion factor, which is
measured in jo/m3 per |ig/m2-s. The total air concentration estimates are then developed by
multiplying the constituent-specific emission rates derived from CHEMDAT8 with a site-
specific dispersion factor. Running ISCST3 to develop a new dispersion factor for each location
and impoundment is very time consuming and requires extensive meteorological data and
technical expertise. Therefore, IWAIR incorporates default dispersion factors developed by
ISCST3 for many separate scenarios designed to cover a broad range of unit characteristics,
including
• 29 meteorological stations, chosen to represent the nine general climate regions of
the continental United States
• 14 surface area sizes for surface impoundments
• 7 receptor distances from the unit (0, 25, 50, 75, 150, 500, 1000 meters)
• 16 directions in relation to the edge of the unit.
The default dispersion factors were derived by modeling each of these scenarios, then
choosing as the default the maximum dispersion factor for each impoundment/surface
area/meteorological station/receptor distance combination.
Peer review comments on IWAIR received before this study was completed suggested
that the 29 meteorological stations were not sufficient to be fully representative of the United
States. Therefore, 12 additional meteorological stations were selected to be added to IWAIR for
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March 26, 2001
Appendix C
this study. These additional meteorological stations were selected to better represent the
locations of surface impoundments, based on data from the surface impoundment survey. The
appropriate dispersion factors for these new meteorological stations were developed and added to
the IWAIR dispersion factor database. Table C.2-3 lists the original 29 meteorological stations
included in IWAIR and the 12 new stations added to IWAIR for this study.
Table C.2-3. Meteorological Stations Included in and Added to IWAIR
for Surface Impoundment Study
Original Met Stations
Added for SIS
Met Station ID
23050
13874
24011
24131
24089
13880
94846
14820
23062
93193
14751
14740
12960
3860
23169
14939
13963
23174
12839
14922
13739
23183
14764
13722
24232
City
Albuquerque, NM
Atlanta, GA
Bismarck, ND
Boise, ID
Casper, WY
Charleston, SC
Chicago, IL
Cleveland, OH
Denver, CO
Fresno, CA
Harrisburg, PA
Hartford, CT
Houston, TX
Huntington, WV
Las Vegas, NV
Lincoln, NE
Little Rock, AR
Los Angeles, CA
Miami, FL
Minneapolis, MN
Philadelphia, PA
Phoenix, AZ
Portland, ME
Raleigh-Durham, NC
Salem, OR
Met Station ID
3812
12842
12916
13737
13865
13957
14742
14840
24033
13897
13968
14778
City
Asheville, NC
Tampa, FL
New Orleans, LA
Norfolk, VA
Meridian, MS
Shreveport, LA
Burlington, VT
Muskegon, MI
Billings, MT
Nashville, TN
Tulsa, OK
Williamsport, PA
(continued)
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Appendix C
Table C.2-3. (continued)
Original Met Stations
Added for SIS
Met Station ID
24127
23234
24233
24128
City
Salt Lake City, UT
San Francisco, CA
Seattle, WA
Winnemucca, NV
Met Station ID
City
Based on the size and location of a unit, IWAIR selects an appropriate dispersion factor
from the default dispersion factors in the model. If the impoundment surface area that falls
between two of the sizes that have already been modeled, a linear interpolation method then
estimates dispersion in relation to the two closest unit sizes.
Risk Model. The third component of IWAIR combines the constituent's air
concentration with receptor exposure factors and toxicity benchmarks to calculate the risk from
concentrations managed in the impoundment. The model applies default values for exposure
factors, including inhalation rate, body weight, exposure duration, and exposure frequency.
These default values are based on data presented in EPA's Exposure Factors Handbook
(U.S. EPA, 1997c, d, e) and represent average exposure conditions. IWAIR maintains standard
health benchmarks (cancer slope factors for carcinogens and reference concentrations for
noncarcinogens) for 95 constituents. These health benchmarks are from the Integrated Risk
Information System (IRIS) (U.S. EPA, 2000f) and the Health Effects Assessment Summary
Tables (HEAST) (U.S. EPA, 1997h). As noted earlier, data on 13 additional chemicals reported
in the surface impoundment survey were added to IWAIR.
C.2.1.3 Additional Methodology Details for Site-Based Modeling. The basic approach
used for the site-based modeling step was to identify the location of the nearest receptor,
interpolate the risk or HQ at that receptor, and evaluate that risk or HQ with respect to the risk
criteria, which were 1E-5 for risk or 1 for HQ.
Calculating Risk at Nearest Receptor. IWAIR can only be run at seven preset distances:
0, 25, 50, 75, 150, 500, and 1,000 m. IWAIR had already been run at 25 m for the screening-
level modeling. To conduct the site-based modeling, an interpolation approach was taken:
IWAIR was run at all six remaining distances for the impoundment/chemical combinations that
had risks in the screening level modeling that exceeded the risk criteria. EPA then interpolated
the risk at the nearest receptor using standard interpolation techniques. Due to the overall shape
of the risk-distance curve, which is not strictly linear but approaches zero risk asymptotically as
distance increases, EPA did a log-log interpolation, as shown in Equation C-l.
-logfll)
(log D2 - log Z)l)
x (logZ) -logDl)
(C-l)
C-57
-------
March 26, 2001 Appendix C
where
R2 = upper-bound risk or HQ modeled by IWAIR
R! = lower-bound risk or HQ modeled by IWAIR
D2 = upper-bound distance modeled by IWAIR (m)
Dj = lower-bound distance modeled by IWAIR (m)
D = nearest receptor distance (m)
R = interpolated risk or HQ at nearest receptor distance.
The lower and upper bound distances are the distances at which IWAIR can be run that
bracket the actual distance to the nearest receptor. For example, if the nearest receptor were at
100 m, the lower bound distance would be 75 m and the upper bound distance would be 150 m.
The lower and upper bound risk or HQ is the modeled risk or HQ at the lower or upper bound
distance. When the actual receptor distance is beyond the data modeled, the last two points
modeled can be used to extrapolate using this same equation; for example, for a receptor distance
of 1,200 m, the data for 500 m and 1,000 m can be used to extrapolate.
The interpolated risks were then compared to the risk or HQ criterion. If the risk
exceeded the risk or HQ criterion (1E-5 for risk or 1 for HQ), the combination was retained for
further analysis. If the risk or HQ was below the criterion, the combination was dropped from
further analysis.
Identifying the Nearest Receptor. Based on the survey data, we identified the nearest
residence for the impoundments for which the risk calculated in the screening-level modeling
exceeded the risk criteria. The survey respondents were sent topographic maps of the area
surrounding their facility. These maps show residences present at the time the map was last
updated. Some maps had been updated recently and others had not been updated for many years.
Survey respondents were asked to mark any additional residences on the map, verify the map as
provided, or provide their own map with residences shown. Some respondents did not annotate
the provided map or verify the map as provided. These maps were considered unverified. The
returned maps were digitized, and a computer program was used to calculate the distance to the
nearest marked residence.
Because some of the returned maps were old and unverified, EPA also considered two
alternative methods of locating residences as checks.
One alternative method of locating residences is to assume that the nearest edge of the
nearest populated census block edge is a reasonable minimum distance to the nearest residence.
However, there may not be residences in that part of the census block, so this approach
introduces a high degree of uncertainty. This distance can be determined by computer based on
publicly available census data.
A more accurate method of locating the nearest residence is by examination of aerial
photos of the area surrounding each facility. EPA acquired aerial photos from USGS for most
sites in the survey at the time the survey was conducted. However, examination of aerial photos
is very time consuming, so it could not realistically be done for all sites.
C-58
-------
March 26, 2001 Appendix C
To make the most efficient use of resources, EPA used map date, verification status, and
census block distance to identify facilities with the most uncertainty in residence location and
most likely to change from having a risk below the risk criterion to having a risk that exceeds the
risk criterion if there were residences closer than indicated by the survey. EPA examined aerial
photos only for those facilities. Specifically, EPA performed the following steps:
• EPA calculated risk based on digitized (survey) residence location. If this risk
exceeded the criterion, then that result was taken as final. Because the risk
already exceeds the risk criterion, there is little to be gained by locating the nearest
residence more precisely even if there is a closer residence.
• If the risk at the nearest digitized receptor was below the risk criterion, EPA
considered whether the map was verified and the map date. If the map was
verified, or if the map date was more recent than the most recent census data
(1990), EPA considered the nearest digitized residence to be reliable, and the
result stood.
• If the map was unverified and older than 1990, EPA calculated the risk based on
the nearest edge of the nearest populated census block. This is a realistic worst
case for residence distance; therefore, if the risk was below the risk criterion even
at this distance, then the result based on the digitized receptor stood.
• If the risk at the census block edge exceeded the risk criterion, EPA examined the
aerial photo to identify the actual nearest residence. If this was different than the
digitized residence location, EPA updated that location and recalculated the risk at
the new location. The risk at the updated location was then the final result,
whether it exceeded or fell below the risk criterion.
Figure C.2-1 shows this same logic in a flow diagram.
In all cases, the final risk was that calculated at the digitized residence location or the
location determined by examination of the aerial photo, if that was different. In most cases, the
aerial photos confirmed the digitized residence location. In the few cases that they did not, the
nearest residence was still considerably farther away than the nearest edge of the nearest
populated census block. Therefore, risk at the edge of the census block was never used as the
final risk.
Figures C.2-2 and C.2-3 show the digitized maps and aerial photos of two of the sites
examined. The aerial photo of the site in Figure C.2-3 clearly shows residences closer to some of
the impoundments than those shown on the digitized map from the survey.
C-59
-------
March 26, 2001
Appendix C
Exceeds
risk criteria at
digitized
receptor?
Map verified
or as recent as
1990?
Below risk
criteria at census
block edge?
Aerial photo
confirm digitized
receptor?
Exceeds risk criteria
Below risk criteria
Below risk criteria
Below risk criteria
Calculate new risk
based on aerial
photo distance
Below risk
criteria at new
distance?
Below risk criteria
Exceeds risk criteria
Figure C.2-1. Decision tree for performing air risk screening.
C-60
-------
March 26, 2001
Appendix C
Figure C.2-2. Examples of nearest receptor: Example 1.
C-61
-------
March 26, 2001
Appendix C
Figure C.2.3. Examples of nearest receptor: Example 2.
C-62
-------
March 26, 2001 Appendix C
C.2.2 Results from Air Pathway Analysis
C.2.2.1 Direct Exposure Pathway Screening Results. A total of 39 constituents present
in 84 surface impoundments at 19 facilities were considered in the initial screening step. When
constituent air concentrations reported in the surface impoundments (or estimated from reported
emissions rates) were compared to human health screening factors based on toxicity benchmarks
for inhalation, 17 constituents in 28 surface impoundments at 11 facilities exceeded the risk
criteria for the direct exposure pathway screening. The constituent counts reflect only those
chemicals for which at least one human health benchmark was available. Many of the facilities
and impoundments did not have the emissions or air concentration data needed for the direct
exposure pathway screening for air; those impoundments were passed on for consideration in the
screening-level modeling step.
C.2.2.2 Screening-Level Modeling Results. For those constituents, impoundments, and
facilities that exceeded the risk criteria for the direct exposure pathway screening, plus those for
which the direct exposure pathway screening could not be performed due to lack of data, a more
realistic assessment of air risk was calculated using IWAIR. In this case, 90 constituents in 290
surface impoundments at 85 facilities were modeled. Forty-two constituents in 75
impoundments at 33 facilities exceeded the risk criteria at this step and were retained for site-
based modeling.
C.2.2.3 Site-Based Modeling. Site-based modeling was conducted for the constituents,
impoundments, and facilities that exceeded the risk criteria for screening-level modeling. After
the site-based modeling, 12 constituents in 17 impoundments at 12 facilities exceeded the risk
criteria. A summary of exceedances is presented in Table C.2-4. Attachment C-6 presents the
full set of site-based air modeling results for the sample population. Attachment C-7 presents the
national estimates for the air pathway results.
Table C.2-4. Summary of Hazard and Risk Exceedances for the Air Pathway
Facility
SI
Summary of HQ Exceedance
Summary of Risk Exceedance
Risk Exceedances Based on Reported Concentrations
85 1 Chlorodibromomethane - le-05
151 1 alpha-Hexachlorocyclohexane -2.62e-05
Risk Exceedances Based on Surogate/DL Chemical Concentrations
23 1 Chloroform - 2.2
23 1 Acetonitrile -57.2
23 4 Chloroform-1.82
23 4 Acetonitrile - 47.7
45 2 Acrolein-7.96
(continued)
-------
March 26, 2001
Appendix C
Table C.2-4. (continued)
Facility SI Summary
of Risk Exceedance
45 4 Acrolein - 4.52
45 5 Acrolein -
3.63
46 3 Acroleinb -2.64
46 3
46 3
46 3
46 4
46 5
77 1
84 4
84 5 Acrolein -
84 5
Bis(chloromethyl) ether b -
N-Nitrosodiethylamine b -
N-Nitrosodi-n-butylamine
Bis(chloromethyl) ether b-
Bis(chloromethyl) ether b-
Bis(chloromethyl) ether -
Bis(chloromethyl) ether -
8.73
Bis(chloromethyl) ether -
4.84e-04
4.64e-05
b- 1.55e-05
1.05e-04
2.44e-04
3.61e-01
1.62e-04
8.73e-03
84 5 Hexachlorocyclopentadiene - 1.5
103 3
175 3 Acroleinb-
184 2
Tetrachlorodibenzofurans
11.5
Toxaphene - 4.00e-03
- 3.22e-05
Risk Exceedances Based on Summed Risks for the Facility
156 Facility level sum - 1.5e-05
156 5 Acetaldehyde a - 6. OOe-06
156 7 Tetrachlorodibenzodioxins - 9.OOe-06
a This constituent and the other bolded ones are based on reported values.
b Industry representatives, subsequent to completion of the survey, have indicated that this constituent is not
expected to be present at the facility. These constituents were reported to EPA in response to the Survey of Surface
Impoundments in November 1999 as less than a specified limit of detection. When this constituent was evaluated in
the risk analysis at the reported detection limit, the concentrations were high enough to predict the indicated
risk/hazard of concern. EPA included the results in this table because of the methodology used throughout the study
to evaluate less than detection limit data.
C-64
-------
March 26, 2001 Appendix C
C.3 Direct Exposure Pathway—Groundwater
People may be exposed to constituents originating in surface impoundments if the
constituents leach through the bottom of the impoundment into groundwater and migrate to
downgradient receptor wells. The potential for direct exposure to constituents via the
groundwater pathway was assessed in three phases, each less conservative than the previous
phase. The first phase, direct exposure pathway screening, compared estimated leachate
concentrations to screening factors for drinking water ingestion. The second phase,
screening-level modeling, calculated risks and hazard quotients using EPA's Industrial Waste
Evaluation Model. The third phase, site-based modeling, identified facility and impoundment
combinations that have the greatest potential to impact receptor wells and provided quantitative
risk estimates for the nearest receptor well at each site of interest.
Site-based modeling was accomplished in three basic steps:
• EPA evaluated the 71 facilities that exceeded risk criteria based on the IWEM
Tier 1 screening analysis to determine if the potential exists for direct exposure to
contamination via the groundwater pathway.
• EPA assumed the potential for exposure by determining if drinking water wells
were present in the downgradient direction of groundwater flow.
• If receptor wells were not present, or if the receptor wells were determined not to
be downgradient of the surface impoundment, EPA presumed the pathway to be
incomplete and excluded the site from further evaluation.
For those facilities that were not excluded, two sets of criteria were developed and used to
prioritize which facilities required site-based modeling. The first set of criteria focused on
environmental setting characteristics (e.g., distance to receptor well) and the second set of criteria
relied on professional judgment (e.g., conductivity of aquifer material). Each set of criteria and
the method in which they were applied are detailed in Attachment C-8. Application of the two
sets of screening criteria produced 10 facilities that were considered the highest priority for
site-based groundwater modeling. The 10 facilities are identified in Attachment C-8 and
summaries of pertinent site and risk characteristics are presented in Attachment C-9.
Characterization and data selection for the 10 modeled facilities are presented in
Attachment C-10. Risk results and modeling for the groundwater pathway are presented in
Attachments C-ll and C-12, respectively.
Site-based modeling was conducted following identification of the highest priority
facilities. Modeling involved assessing the fate and transport of chemical constituents present in
surface impoundments using Monte Carlo simulations executed using EPACMTP. Site-specific,
regional, and national data, as appropriate, were used in model simulations.
C-65
-------
March 26, 2001 Appendix C
These groundwater concentrations were then coupled with Monte Carlo-generated
exposure parameters to generate individual cancer risk and noncancer hazard quotients for the 10
highest priority facilities. The results of this analysis are presented in Attachment C-12.
C.3.1 Numeric Ranking System for Facilities. Impoundments, and Constituents
The direct exposure pathway screening analysis compared constituent concentrations
reported in surface impoundments to human health screening factors protective of residential
exposure. Specifically, the risks posed to an individual receptor based on concentrations of
constituents in surface impoundments were compared to human health risk screening factors
based on toxicity benchmarks for direct ingestion of drinking water. These screening risks are
highly protective of human health because the underlying assumption is that the resident drinks
impoundment water. Those constituents, impoundments, and facilities that posed negligible risk
(i.e., cancer risk less than 1E-5 or HQ less than 1.0) were below risk criteria for the analysis.
This human health risk screening calculation was performed for each constituent in each surface
impoundment for each of the 133 facilities. Of the 133 facilities, 106 facilities exceeded risk
criteria.
For those constituents, impoundments, and facilities that exceeded risk criteria, a more
refined assessment of groundwater risk was performed by evaluating fate and transport processes
in the environment using EPA's IWEM Tier 1 screening model (U.S. EPA, 1999b, c). This
phase of the screening process also used protective assumptions, such as assessing risks for
receptor wells located 150 meters from the surface impoundment.
The IWEM Tier 1 screening model consists of tabulated leachate concentration threshold
values for specific chemicals based on a dilution attenuation factor and the toxicity reference
levels for 191 constituents. The toxicity reference level is based on toxicological benchmarks or
the maximum contaminant level. The DAFs were generated by modeling the migration of waste
constituents from an impoundment through the underlying soil to a monitoring point in the
aquifer using EPACMTP in a national Monte Carlo probabilistic analysis. The DAFs are
multiplied by the toxicity benchmark to provide the leachate concentration threshold value for
each constituent.
To maintain consistency with the initial phase of risk screening, only the DAFs from
IWEM were used. DAFs and leachate concentration threshold values were evaluated for three
impoundment liner scenarios: no liner, single liner, and a composite liner. The no liner scenario
represented an impoundment relying on location-specific conditions such as low-permeability
native soils beneath the unit or low annual precipitation rates to mitigate the release of
contaminants to the groundwater. The single liner scenario represented a 3-foot-thick clay liner
with low hydraulic conductivity (10"7 cm/s) beneath the impoundment, and the composite liner
scenario consisted of a 3-foot-thick clay liner beneath a 40-mil-thick high-density polyethylene
(HOPE) flexible membrane liner. The DAFs for each constituent for each of the three liner
scenarios are presented in Table C.3-1.
C-66
-------
March 26, 2001
Appendix C
Table C.3-1. Constituent Dilution Attenuation Factors for Liner Scenarios
Constituent
1 , 1 ,2,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
1,1-Dichloroethylene [Vinylidene chloride]
1,1-Dichloroethylene [Vinylidene chloride]
1,1-Dichloroethylene [Vinylidene chloride]
1,2,3-Trichloropropane
1,2,3-Trichloropropane
1,2,3-Trichloropropane
1,2,4,5-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
l,2-Dibromo-3-chloropropane
l,2-Dibromo-3-chloropropane
l,2-Dibromo-3-chloropropane
1,2-Dichloroethane [Ethylene dichloride]
1,2-Dichloroethane [Ethylene dichloride]
1,2-Dichloroethane [Ethylene dichloride]
1,2-Dichloropropane [Propylene dichloride]
1,2-Dichloropropane [Propylene dichloride]
1,2-Dichloropropane [Propylene dichloride]
1 ,2-Diphenylhydrazine
1 ,2-Diphenylhydrazine
1 ,2-Diphenylhydrazine
1,3-Dinitrobenzene [m-Dinitrobenzene]
CAS_NO
79345
79345
79345
75354
75354
75354
96184
96184
96184
95943
95943
95943
96128
96128
96128
107062
107062
107062
78875
78875
78875
122667
122667
122667
99650
Scenario"
1
2
3
1
2
3
3
1
2
2
3
1
1
3
2
3
1
2
1
2
3
1
3
2
1
DAF
3.9
34000
34000
1.8
7
730000
l.OOE+06
1.2
10
170
170
5.2
1.8
110000000
13
l.OOE+06
1.8
8.4
1.9
19
19
1.8
130000
6.6
1.1
(continues
C-67
-------
March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
1,3-Dinitrobenzene [m-Dinitrobenzene]
1,3-Dinitrobenzene [m-dinitrobenzene]
1,4-Dichlorobenzene [p-dichlorobenzene]
1 ,4-Dichlorobenzene [p-dichlorobenzene]
1 ,4-Dichlorobenzene [p-dichlorobenzene]
1 ,4-Dioxane [ 1 ,4-diethyleneoxide]
1,4-Dioxane [1,4-diethyleneoxide]
1 ,4-Dioxane [ 1 ,4-diethyleneoxide]
2,3,7,8-TCDD[2,3,7,8-tetrachlorodibenzo-p-dioxin]
2,3,7,8-TCDD[2,3,7,8-tetrachlorodibenzo-p-dioxin]
2,3,7,8-TCDD[2,3,7,8-tetrachlorodibenzo-p-dioxin]
2,4,6-Trichlorophenol
2,4,6-Trichlorophenol
2,4,6-Trichlorophenol
2,4-Dichlorophenol
2,4-Dichlorophenol
2,4-Dichlorophenol
2,4-Dinitrophenol
2,4-Dinitrophenol
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,4-Dinitrotoluene
2,4-Dinitrotoluene
2,6-Dinitrotoluene
2,6-Dinitrotoluene
CAS_NO
99650
99650
106467
106467
106467
123911
123911
123911
1746016
1746016
1746016
88062
88062
88062
120832
120832
120832
51285
51285
51285
121142
121142
121142
606202
606202
Scenario"
3
2
3
2
1
1
3
2
1
2
3
1
3
2
1
3
2
1
3
2
1
2
3
1
3
DAF
310000
5
11000000
15
2
1.8
130000
6.6
300
7900000000
7900000000
1.8
1900000
7.9
1.2
3100000
7.2
1.1
130000
4.8
1.1
5.2
600000
1.1
380000
(continues
C-68
-------
March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
2,6-Dinitrotoluene
2-Chlorophenol [o-chlorophenol]
2-Chlorophenol [o-chlorophenol]
2-Chlorophenol [o-chlorophenol]
3,3 -Dichlorobenzidine
3,3 -Dichlorobenzidine
3,3 -Dichlorobenzidine
4,4-Methylene bis(2-chloroaniline)
4,4-Methylene bis(2-chloroaniline)
4,4-Methylene bis(2-chloroaniline)
Acetone [2-Propanone]
Acetone [2-Propanone]
Acetone [2-Propanone]
Acrylic acid [propenoic acid]
Acrylic acid [propenoic acid]
Acrylic acid [propenoic acid]
Acrylonitrile
Acrylonitrile
Acrylonitrile
Aldrin
Aldrin
Aldrin
Allyl alcohol
Allyl alcohol
Allyl alcohol
CAS_NO
606202
95578
95578
95578
91941
91941
91941
101144
101144
101144
67641
67641
67641
79107
79107
79107
107131
107131
107131
309002
309002
309002
107186
107186
107186
Scenario"
2
1
2
3
1
3
2
3
1
2
1
3
2
1
3
2
1
3
2
1
2
3
1
3
2
DAF
5
1.1
5.4
790000
2.1
21000000
22
l.OOE+06
1.8
8
1.1
130000
4.8
1.1
130000
4.8
1.8
190000
6.6
360
9800000000
9800000000
1.1
130000
4.8
(continues
C-69
-------
March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
alpha-Hexachlorocyclohexane [a-BHC]
alpha-Hexachlorocyclohexane [a-BHC]
alpha-Hexachlorocyclohexane [a-BHC]
Aniline
Antimony
Antimony
Antimony
Arsenic
Arsenic
Arsenic
Barium
Barium
Barium
Benzene
Benzene
Benzene
Benzidine
Benzidine
Benzidine
Benzo(a)pyrene
Benzo(a)pyrene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(b)fluoranthene
Benzo(b)fluoranthene
CAS_NO
319846
319846
319846
62533
7440360
7440360
7440360
7440382
7440382
7440382
7440393
7440393
7440393
71432
71432
71432
92875
92875
92875
50328
50328
50328
205992
205992
205992
Scenario"
2
3
1
2
2
3
1
1
2
3
1
3
2
1
2
3
1
3
2
1
2
3
1
2
3
DAF
230000000
230000000
59
6.6
1360
1360
45
33
969
969
2.6585
232269.81
47.4
1.8
7.1
770000
1.8
320000
6.7
150
3300000000
3300000000
150
2100000000
2100000000
(continues
C-70
-------
March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
Benzo [a] anthracene
Benzo [a] anthracene
Benzo [a] anthracene
Benzyl chloride
Benzyl chloride
Benzyl chloride
Beryllium
Beryllium
Beryllium
beta-Hexachlorocyclohexane [ p-BHC]
beta-Hexachlorocyclohexane [ p-BHC]
beta-Hexachlorocyclohexane [ p-BHC]
Bis(2-chloroethyl) ether [sym-dichloroethyl ether]
Bis(2-chloroethyl) ether [sym-dichloroethyl ether]
Bis(2-chloroethyl) ether [sym-dichloroethyl ether]
Bis(2-chloroisopropyl) ether [2,2 -dichloroisopropyl ether]
Bis(2-chloroisopropyl) ether [2,2 -dichloroisopropyl ether]
Bis(2-chloroisopropyl) ether [2,2 -dichloroisopropyl ether]
Bis(chloromethyl) ether [sym-dichloromethyl ether]
Bis(chloromethyl) ether [sym-dichloromethyl ether]
Bis(chloromethyl) ether [sym-dichloromethyl ether]
Bromodichloromethane [dichlorobromomethane]
Bromodichloromethane [dichlorobromomethane]
Bromodichloromethane [dichlorobromomethane]
Cadmium
CAS_NO
56553
56553
56553
100447
100447
100447
7440417
7440417
7440417
319857
319857
319857
111444
111444
111444
39638329
39638329
39638329
542881
542881
542881
75274
75274
75274
7440439
Scenario"
2
3
1
2
1
3
3
1
2
1
2
3
1
2
3
1
3
2
2
1
3
1
3
2
3
DAF
230000000
230000000
50
l.OOE+06
l.OOE+06
l.OOE+06
l.OOE+06
4.6
70
2.2
26
27000000
2.3
40
40
1.8
2600000
8.4
l.OOE+06
l.OOE+06
l.OOE+06
1.8
1400000
8.1
l.OOE+06
(continues
C-71
-------
March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
Cadmium
Cadmium
Carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride
Chlordane, a & y isomers
Chlordane, a & y isomers
Chlordane, a & y isomers
Chlorobenzilate
Chlorobenzilate
Chlorobenzilate
Chloroform [trichloromethane]
Chloroform [trichloromethane]
Chloroform [trichloromethane]
Chloromethane [methyl chloride]
Chloromethane [methyl chloride]
Chloromethane [methyl chloride]
Chromium
Chromium
Chromium
Chromium VI [hexavalent chromium]
Chromium VI [hexavalent chromium]
Chromium VI [hexavalent chromium]
cis- 1 ,3 -Dichloropropylene
cis- 1 ,3 -Dichloropropylene
CAS_NO
7440439
7440439
56235
56235
56235
57749
57749
57749
510156
510156
510156
67663
67663
67663
74873
74873
74873
7440473
7440473
7440473
18540299
18540299
18540299
10061015
10061015
Scenario"
1
2
1
2
3
2
3
1
2
3
1
1
2
3
1
3
2
1
2
3
3
1
2
2
1
DAF
15.4
325.6
1.9
36
36
130000
130000
176
16000
16000
4.1
1.8
6.9
930000
1.8
200000
6.6
23
645
645
l.OOE+06
23
645
21000
21000
(continues
C-72
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March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
cis- 1 ,3 -Dichloropropylene
Copper
Copper
Copper
Cyanide
Cyanide
Cyanide
Diallate
Diallate
Diallate
Dibenz [a,h] anthracene
Dibenz [a,h] anthracene
Dibenz [a,h] anthracene
Dieldrin
Dieldrin
Dieldrin
Ethyl acetate
Ethyl acetate
Ethyl acetate
Ethylene dibromide [1,2-dibromoethane]
Ethylene dibromide [1,2-dibromoethane]
Ethylene dibromide [1,2-dibromoethane]
Ethylene glycol
Ethylene glycol
Ethylene glycol
CAS_NO
10061015
7440508
7440508
7440508
57125
57125
57125
2303164
2303164
2303164
53703
53703
53703
60571
60571
60571
141786
141786
141786
106934
106934
106934
107211
107211
107211
Scenario"
3
2
3
1
2
3
1
1
2
3
1
2
3
2
1
3
1
2
3
2
3
1
1
3
2
DAF
21000
164
313372.81
7.139
l.OOE+06
l.OOE+06
28
13
830000
830000
1059
2.9e+015
2.9e+015
2992
2992
2992
1.4
21
21
1200
1200
3.1
1.1
130000
4.8
(continues
C-73
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March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
Ethylene oxide
Ethylene oxide
Ethylene oxide
Fluoride
Fluoride
Fluoride
Formaldehyde
Formaldehyde
Formaldehyde
Furfural
Furfural
Furfural
Heptachlor
Heptachlor
Heptachlor
Heptachlor epoxide, a, p, and y isomers
Heptachlor epoxide, a, p, and y isomers
Heptachlor epoxide, a, p, and y isomers
Hexachloro- 1 ,3 -butadiene [hexachlorobutadiene]
Hexachloro- 1 ,3 -butadiene [hexachlorobutadiene]
Hexachloro- 1 ,3 -butadiene [hexachlorobutadiene]
Hexachlorobenzene
Hexachlorobenzene
Hexachlorobenzene
Hexachloroethane
CAS_NO
75218
75218
75218
16984488
16984488
16984488
50000
50000
50000
98011
98011
98011
76448
76448
76448
1024573
1024573
1024573
87683
87683
87683
118741
118741
118741
67721
Scenario"
2
3
1
1
3
2
1
3
2
1
3
2
2
1
3
2
1
3
2
3
1
2
3
1
1
DAF
l.OOE+06
l.OOE+06
28
1.1
130000
4.8
1.1
130000
4.8
1.1
130000
4.8
l.OOE+06
l.OOE+06
l.OOE+06
557
557
557
250
250
7.9
520000000
520000000
59
2.5
(continues
C-74
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March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
Hexachloroethane
Hexachloroethane
Hexachlorophene
Hexachlorophene
Hexachlorophene
Indeno(l,2,3-cd) pyrene
Indeno(l,2,3-cd) pyrene
Indeno(l,2,3-cd) pyrene
Kepone
Kepone
Kepone
Lead
Lead
Lead
Manganese
Manganese
Manganese
Mercury
Mercury
Mercury
Methanol [methyl alcohol]
Methanol [methyl alcohol]
Methanol [methyl alcohol]
Methyl ethyl ketone [2-butanone] [MEK]
Methyl ethyl ketone [2-butanone] [MEK]
CAS_NO
67721
67721
70304
70304
70304
193395
193395
193395
143500
143500
143500
7439921
7439921
7439921
7439965
7439965
7439965
7439976
7439976
7439976
67561
67561
67561
78933
78933
Scenario"
2
3
1
2
3
2
3
1
2
3
1
3
2
1
3
1
2
1
2
3
1
3
2
1
3
DAF
37
41000000
23
860
860
12000000000
12000000000
440
120
le+030
4.7
l.OOE+06
46290.666667
490.66666667
l.OOE+06
11
283.9
15
545
545
1.1
130000
4.8
1.1
130000
(continues
C-75
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March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
Methyl ethyl ketone [2-butanone] [MEK]
Methylene chloride [dichloromethane]
Methylene chloride [dichloromethane]
Methylene chloride [dichloromethane]
Molybdenum
Molybdenum
Molybdenum
Naphthalene
Naphthalene
Naphthalene
n-Butyl alcohol [n-butanol]
n-Butyl alcohol [n-butanol]
n-Butyl alcohol [n-butanol]
Nickel
Nickel
Nickel
Nitrobenzene
Nitrobenzene
Nitrobenzene
N-Nitrosodiethylamine
N-Nitrosodiethylamine
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodimethylamine
N-Nitrosodimethylamine
CAS_NO
78933
75092
75092
75092
7439987
7439987
7439987
91203
91203
91203
71363
71363
71363
7440020
7440020
7440020
98953
98953
98953
55185
55185
55185
62759
62759
62759
Scenario"
2
1
3
2
3
1
2
1
3
2
1
3
2
3
1
2
1
3
2
1
3
2
1
3
2
DAF
4.8
1.8
350000
6.8
l.OOE+06
23
645
1.4
13000000
15
1.1
170000
4.9
l.OOE+06
11
283.9
1.1
460000
5.1
1.8
130000
6.6
1.8
170000
6.6
(continues
C-76
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March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-butylamine
N-Nitrosodi-n-propylamine [di-n-propylnitrosamine]
N-Nitrosodi-n-propylamine [di-n-propylnitrosamine]
N-Nitrosodi-n-propylamine [di-n-propylnitrosamine]
N-Nitroso-N-methylethylamine
N-Nitroso-N-methylethylamine
N-Nitroso-N-methylethylamine
N-Nitrosopyrrolidine
N-Nitrosopyrrolidine
N-Nitrosopyrrolidine
o-Cresol [2 -methyl phenol]
o-Cresol [2 -methyl phenol]
o-Cresol [2 -methyl phenol]
p-Cresol [4-methyl phenol]
p-Cresol [4-methyl phenol]
p-Cresol [4-methyl phenol]
Pentachlorobenzene
Pentachlorobenzene
Pentachlorobenzene
Pentachlorophenol [PCP]
Pentachlorophenol [PCP]
Pentachlorophenol [PCP]
Polychlorinated biphenyls [aroclors]
CAS_NO
924163
924163
924163
621647
621647
621647
10595956
10595956
10595956
930552
930552
930552
95487
95487
95487
106445
106445
106445
608935
608935
608935
87865
87865
87865
1336363
Scenario"
1
3
2
1
3
2
1
3
2
1
3
2
1
2
3
1
2
3
2
3
1
3
2
1
2
DAF
1.8
1400000
7.5
1.8
240000
6.7
1.8
240000
6.7
1.8
130000
6.6
1.1
5.3
680000
1.1
5.3
680000
280000000
280000000
56
12000000
15
2
10000000000
(continues
C-77
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March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
Polychlorinated biphenyls [aroclors]
Polychlorinated biphenyls [aroclors]
Pyridine
Pyridine
Pyridine
Selenium
Selenium
Selenium
Silver
Silver
Silver
Tetrachlorodibenzofurans [TCDFs]
Tetrachlorodibenzofurans [TCDFs]
Tetrachlorodibenzofurans [TCDFs]
Tetrachloroethylene [perchloroethylene]
Tetrachloroethylene [perchloroethylene]
Tetrachloroethylene [perchloroethylene]
Thallium
Thallium
Thallium
Toluene
Toluene
Toluene
Toxaphene [chlorinated camphene]
Toxaphene [chlorinated camphene]
CAS_NO
1336363
1336363
110861
110861
110861
7782492
7782492
7782492
7440224
7440224
7440224
55722275
55722275
55722275
127184
127184
127184
7440280
7440280
7440280
108883
108883
108883
8001352
8001352
Scenario"
3
1
1
3
2
2
3
1
3
1
2
2
3
1
1
3
2
2
3
1
1
3
2
1
2
DAF
10000000000
370
1.1
170000
4.9
166
166
6.7
388554.45
4.05
52.9
l.OOE+06
l.OOE+06
1059
1.2
1700000
6.1
2380
2380
73
1.2
2800000
6.9
12
640000
(continues
C-78
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March 26, 2001
Appendix C
Table C.3-1. (continued)
Constituent
Toxaphene [chlorinated camphene]
trans- 1 ,3 -Dichloropropylene
trans- 1 ,3 -Dichloropropylene
trans- 1 ,3 -Dichloropropylene
Trichloroethylene [TCE]
Trichloroethylene [TCE]
Trichloroethylene [TCE]
Vanadium
Vanadium
Vanadium
Vinyl chloride [chloroethylene]
Vinyl chloride [chloroethylene]
Vinyl chloride [chloroethylene]
Zinc
Zinc
Zinc
CAS_NO
8001352
10061026
10061026
10061026
79016
79016
79016
7440622
7440622
7440622
75014
75014
75014
7440666
7440666
7440666
Scenario"
3
2
1
3
1
3
2
3
1
2
1
3
2
3
2
1
DAF
640000
21000
21000
21000
1.8
1400000
7.5
1000022.3
11.933333333
397.56666667
1.1
240000
4.9
100000
118.971
6.328
' Liner scenario key:
1 = No liner.
2 = Single liner.
3= Composite liner.
For each constituent, the DAF from each liner scenario was multiplied by the
carcinogenic or noncarcinogenic risk screening factor from the initial phase of risk screening to
develop a new Si-modified IWEM Tier 1 table containing the leachate concentration threshold
values. This approach ensured that receptors were evaluated with the same exposure factors
(e.g., groundwater ingestion rate) used in the initial phase of risk screening.
There were a number of SIS constituents that were not included in the IWEM Tier 1
table. For those constituents, a leachate concentration threshold value was calculated using a
DAF from a surrogate chemical. The leachate concentration threshold value was calculated by
C-79
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March 26, 2001 Appendix C
using the IWEM procedure for estimating DAFs of chemicals for which EPACMTP was not
simulated, as follows: the DAF was determined by interpolating between the DAFs of chemicals
whose hydrolysis rate and retardation factor are in the same range as the hydrolysis rate and
retardation factor of the new chemical.
Leachate concentration threshold values were exceeded for chemicals at 71 facilities in
the IWEM Tier 1 screening model. Each of the 71 facilities was then evaluated to determine if
the potential exists for direct exposure to contamination via the groundwater pathway.
Specifically, the topographic maps supplied by the facilities as part of their survey
responses were evaluated to determine (1) whether drinking water wells were located within 2
km of any impoundment, (2) if the groundwater flow direction could be determined based on
review of the topographic maps, and, if so, (3) if receptor wells were present in the downgradient
direction.
The map review considered the location of the surface impoundments relative to surface
waterbodies in the area. Surface waterbodies included bays, estuaries, rivers, lakes, streams,
creeks, canals, harbors, and wetlands. The purpose of evaluating the relative location of
impoundments to surface waterbodies was to determine the likely direction of groundwater flow.
If the surface impoundment was situated proximate to the surface waterbody, it was assumed that
leachate originating from the surface impoundment discharged in the direction of the nearby
surface waterbody.
Survey respondents were also asked to identify the type and location of wells within a
2-km radius of the facility. Each of the topographic maps was reviewed to determine the location
of receptor wells relative to the groundwater flow direction. To ensure that the assessment was
conservative, all wells that might potentially be used for drinking water purposes, as identified by
the facilities in their survey responses, were included in the assessment. The wells selected for
consideration included the following categories:
• Private drinking water wells (residential)
• Public drinking water wells
• Industrial drinking water wells
• Business/commercial wells
• Church wells
• Drinking water services
• Wells designated as "don't know"
• Wells designated as "other"
• Wells for which no designation was provided.
If no drinking water wells were present, or the groundwater flow was determined not to
be in the downgradient direction of any receptor well, the potential for exposure via the
groundwater pathway was presumed to be nonexistent and the site was excluded from further
assessment. The facilities that were excluded from further assessment are presented in
Attachment C-8. A numeric ranking of either 1 or 2 was assigned to the facilities for which
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March 26, 2001 Appendix C
groundwater exposures could not definitively be ruled out. Table C.3-2 presents the ranking
system used.
Table C.3-2. Ranking System for Groundwater Receptors
Score
2
1
Exclude
Criteria
Groundwater direction can be determined and there
downgradient of the failed surface impoundments
are receptor wells located
Groundwater direction cannot be determined with certainty but the presence of potential
receptor wells cannot be definitively ruled out
Groundwater direction can be determined and there
downgradient of the failed surface impoundments
are no potential receptor wells located
Thirty-three of the 71 facilities were excluded from further assessment based on evidence
that the groundwater pathway would not result in exposure. The remaining 38 facilities were
evaluated using two sets of criteria developed to assign a numeric score that could be used to
rank the facilities at greatest risk for groundwater exposures.
Two sets of criteria were developed for the groundwater analysis. The first set of criteria
focused on easily quantifiable environmental setting characteristics such as distance to the
nearest receptor well. The second set was based on professional judgment and involved detailed
review of survey data and, in many cases, geotechnical reports submitted by the respondents.
Each of the criteria was assigned a numeric score to rank facilities for additional site-based fate
and transport modeling. The criteria and scoring methodology are discussed below.
C.3.1.1 Criteria Based on Environmental Setting Characteristics. Four criteria were
selected to prioritize facilities and impoundments having potential for direct exposure to
contaminants via the groundwater pathway. Each of the four criteria was selected to permit
quantification of parameters that support the probability that the groundwater pathway may result
in exposure. Hence, the criteria focus on the source of potential groundwater contamination (i.e.,
the chemicals present in the surface impoundment and their risk factors) and the point of
exposure (i.e., the presence of wells used for drinking water consumption). Criteria were
assigned a numeric score ranging from 1 to 3, with 3 having the highest potential for exposure.
The four criteria were applied to the 38 facilities that exceeded the IWEM Tier 1 screening
criteria. The four environmental setting criteria are
• Distance to the nearest receptor well
• Maximum cancer risk or HQ as determined using IWEM Tier 1
• Numb er of chemi cal s
• Surface area.
C-81
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March 26, 2001
Appendix C
Distance to Nearest Receptor Well. The distance to the nearest receptor is an important
indicator of the likelihood that exposure will occur as a result of consumption of contaminated
drinking water. Receptor wells that are close to sources of contamination have a greater potential
of being impacted than those located at great distances from the source of contamination. Hence,
facilities that were characterized by receptor wells located at distances of less than 500 meters
were given a higher ranking for modeling than facilities with receptor wells located at distances
greater than 1,000 meters.
As noted above, survey respondents were asked to identify the type and location of wells
within a 2-km radius of the facility. Distances from the surface impoundments to each of the
wells identified as having the potential to be used for drinking water purposes were measured
using the topographic maps. The minimum distance measured from the surface impoundment to
a drinking water well was recorded and assigned a numeric scoring in accordance with
Table C.3-3.
Although each of the facilities was asked to provide well information, not all respondents
were able to supply this information. In the absence of survey data, the distance to the nearest
populated census block within a census block group with residential wells was calculated. The
minimum distance to the nearest populated census block was used in assessing well distances for
facilities that did not supply well data. Table C.3-4 presents the distance value that was assigned
and the associated scores.
Table C.3-3. Distance to Nearest Drinking Water Well
(As Marked on Topographic Map)
Score
Criteria
3
2
1
0< Distance < 150m
1 50 < Distance < 500m
500 < Distance < 2,000m
Table C.3-4. Distance to Populated Census Block
Score
O
2
1
Criteria
0 m < Residential well < 150 m
150 m < Residential well < 500 m
500 m < Residential well < 2000 m
Assigned distance (m)
75
150
500
Each facility received a single score based on well distance. Data supplied by the facility
was the preferred source of data. Census data were only used as a default in the absence of
facility-supplied well data. Scoring is presented in Attachment C-8.
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March 26, 2001
Appendix C
Maximum Cancer Risk or HO. Cancer risks and HQs were estimated during the IWEM
screening analysis. The maximum cancer risk and the maximum HQ for each surface
impoundment were compared and the risk or HQ that resulted in the highest overall score in
accordance with Table C.3-5 was used in prioritization.
Table C.3-5. Maximum Cancer Risk or HQ
Score
3
2
1
Cancer Risk
Cancer risk >10E-4
10E-6 < Cancer risk < 10E-4
Cancer risk < 10E-6
Hazard Quotient
HQ>100
10HQ< 10
Number of Chemicals. The total number of chemicals present at a facility was also
scored. The larger the number of chemicals, the higher the score. Table C.3-6 presents the
scores.
Table C.3-6. Total Number of Chemicals
Score
O
2
1
Criteria
Chemicals > 15
5 < Chemicals < 15
Chemicals < 5
Surface Area. The last criterion used was the surface area of the largest surface
impoundment containing chemicals that exceeded the IWEM screening criteria. The scores were
applied as presented in Table C.3-7.
Table C.3-7. Surface Area of Largest Surface Impoundment that
Exceeded Risk Criteria
Score
O
2
1
Criteria (m2)
Area > 75,000
1 0,000 < area < 75,000
Area< 10,000
C-83
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March 26, 2001 Appendix C
Overall scores for the environmental setting criteria were calculated by summing each of
the individual scores. A maximum of 14 points was possible.
C.3.1.2 Criteria Based on Professional Judgment. A second set of criteria were applied
to refine the evaluation further. The second set of criteria were based on professional judgment
and depended on detailed review of the survey responses and any supplemental geotechnical
reports submitted with the surveys. These criteria were important because they added yet another
dimension to assessing whether groundwater exposures were viable. These criteria depended on
geometric considerations such as whether receptor wells are drawing water from a contaminated
aquifer as opposed to drawing water from an aquifer situated hundreds of feet below the
contaminated zone. The presence of low-conductivity layers that impede the downward
migration of contaminants was also considered. These criteria were scored similarly to the
environmental setting criteria in that scores ranged from 1 to 3, with 3 having the greatest
potential for viable groundwater exposures.
Presence of Aquifers That Support Drinking Water Use. An aquifer is best defined as a
saturated permeable layer that yields significant or economic quantities of groundwater.
Ninety-six percent of the world's available fresh water reserve is groundwater and the U.S.
Geologic Survey reports that groundwater supplies 51 percent of our nation's population with
drinking water (U.S. EPA, 1998c). This water reaches the population through private water
wells or through municipal systems that use groundwater as a source. The focus of this
assessment is on private wells that supply drinking water.
Survey respondents were asked to provide information on whether the aquifers beneath
the facility were suitable for drinking water purposes. If the aquifers were not suitable for use as
a source of drinking water, the potential for exposure via the groundwater pathway was limited.
A score of 1 to 3 was awarded to each facility based on the survey results (Table C.3-8).
Table C.3-8. Aquifers Support Domestic Supply
Score
3
2
1
Criteria
Facility indicates that aquifers are used for domestic supply
Facility does not know if aquifers are used for domestic supply
Facility indicates that aquifers are not used for domestic supply
Twelve facilities indicated that the aquifers beneath the site were used to supply drinking
water (Attachment C-8). Two facilities indicated that the groundwater beneath their sites was not
suitable for drinking water; however, a score of "3" was assigned to both of these sites. One of
the facilities received a score of "3" because the existence of groundwater contamination
confirmed the possibility of exposure via the groundwater pathway. The presence of an onsite
potable well at the second facility showed that the groundwater was used for drinking water
C-84
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March 26, 2001 Appendix C
purposes and, hence, could support drinking water purposes. Therefore, 14 facilities or 38
percent of the facilities were characterized by aquifers that support drinking water use.
Presence of Wells Screened in Aquifer. If the aquifer beneath the site was suitable to
supply drinking water, the next step was to assess whether wells were drawing water from the
aquifer for human consumption. Table C.3-9 illustrates the scoring system used.
Table C.3-9. Domestic Wells Screened in Aquifer
Score
3
2
1
Criteria
Facility indicates that wells draw water from an at-risk drinking water aquifer
Facility does not know if there are wells screened in the drinking water aquifer
Facility indicates that there are no wells screened in the drinking water aquifer at risk
Survey respondents were asked to indicate which subsurface saturated zone (or aquifer)
supplied water to wells shown on the topographic map. This information was cross-referenced
against aquifer information supplied in the survey and a judgment was made as to whether
receptor wells draw drinking water from the aquifers of interest. Eleven facilities (or 38 percent)
indicated that wells were screened in the drinking water aquifers (Attachment C-8).
Presence of a Continuous Confining Layer. Aquifers are defined as layers that yield
significant quantities of water. Layers that do not produce or yield significant quantities of water
are defined as aquitards. The most common aquitards are clays, chalk, shales, and dense
crystalline rock. Definitions of aquifers and aquitards are imprecise because the terms are
relative. For example, in an interlayered sand-silt sequence, the silts may be considered
aquitards, whereas in a silt-clay system, the same silts may be described as aquifers. For
purposes of this assessment, thick continuous layers (in excess of 20 feet) of clay or chalk were
defined as aquitards.
Aquitards are characterized by low conductivity (10"4 m/d to 10"7 m/d). The low
conductivity retards the downward migration of contamination. If an aquitard is present,
contamination is unlikely to reach the underlying aquifer, and the groundwater pathway is
considered incomplete. A score of either 1 or 2 was assigned (Table C.3-10).
Table C.3-10. Presence of a Low Conductivity Confining Layer
Score
2
1
Criteria
Thin, discontinuous, or absent
Well-defined confining layer
confining layer
> 20 feet thick
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March 26, 2001 Appendix C
A score of 1 indicates that the potential for vertical migration of contaminants is
negligible and the facility is excluded from further scoring. Eight facilities (22 percent) were
characterized by the presence of a thick, continuous confining layer that made the groundwater
pathway not viable (Attachment C-8).
Aquifer Conductivity. Aquifers are commonly characterized by hydraulic conductivities
that range from 106 m/d to 10 m/d. The higher hydraulic conductivities are associated with well-
sorted sands and gravels. If an aquifer is characterized by higher hydraulic conductivity,
contaminants have the potential to migrate at a faster rate and impact receptor wells. Scoring
was based on survey responses (Table C.3-11).
Eleven facilities were characterized by aquifer stratigraphy that was conducive to rapid
migration of contaminants (Attachment C-8).
Table C.3-11. Aquifer Conductivity
Score
3
2
1
Criteria
Highly conductive stratigraphy (sand, sand and gravel)
Variable conductivity (silty sands)
Low conductive stratigraphy (clay, chalk)
Having scored each of the professional judgment criteria, both the environmental setting
scores and the professional judgment scores were summed into a total score. The facilities that
received the highest scores were prioritized for additional characterization using groundwater
modeling. The methods and results for groundwater modeling are presented in Attachments
C-ll andC-12.
C.3.2 Modeling Groundwater Exposure Concentrations
Groundwater fate and transport modeling was conducted for constituents that did not pass
the screening analyses described in Section C.3.1. The modeling was conducted for wastewaters
managed in onsite surface impoundments and was directed toward estimating groundwater
concentrations in residential drinking water wells downgradient from the surface impoundment.
Surface impoundment characteristics and constituent concentrations were obtained from data
provided by operators in the Survey of Surface Impoundments.
The analysis used EPACMTP, a state-of-the-science vadose zone and groundwater fate
and transport model designed specifically for regulatory applications. The model can be applied
in either a probabilistic (Monte Carlo) or a deterministic mode. The version of EPACMTP used
resulted from modifications made specifically for the Inorganics Listing Determination (U.S.
EPA, 2000b) with two additional modifications. These modifications removed constraints on the
depth of the receptor well location and the angle of the receptor well off plume centerline that
were implemented specifically for the Inorganics Listing Determination. Additional details are
C-86
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March 26, 2001 Appendix C
provided in Section C.3.2.2. Monte Carlo model runs were conducted in this analysis. Site-
specific modeling data were used when available and supplemented by regional and national data
sources. Distributions were used to characterize potential site variability and uncertainty in
model input parameters.
Section C.3.2.1 presents a brief technical summary of the simulation model chosen for
this analysis, the EPACMTP. The general modeling methodology and assumptions for this
analysis are described in Section C.3.2.2, in addition to code modifications made specifically for
this analysis. Data sources and assumptions for the modeling of conservative and non-
conservative organic constituents are described in Section C.3.2.3. Data sources for site-specific
characteristics and subsurface modeling parameters are described in Section C.3.2.4. Section
C.3.2.5 presents the facility-specific modeling approach adopted for this analysis. The results of
the Monte Carlo simulations are presented in Attachment C-l 1 of this Appendix.
C.3.2.1 EPACMTP Background. Only releases to groundwater were considered in this
portion of the risk assessment. The EPACMTP groundwater model was used to estimate the fate
and transport of constituents through the subsurface environment, as described here.
Description of EPACMTP. The groundwater pathway modeling conducted for this
Monte Carlo analysis was performed to determine the residential groundwater well exposure
concentrations resulting from the release of waste constituents from surface impoundments.
Liquid that percolates through the surface impoundment generates leachate, which can infiltrate
from the bottom of the impoundment into the subsurface. For surface impoundments, the liquid
is the wastewater managed in the impoundments. The waste constituents dissolved in the
leachate are then transported via aqueous phase migration through the vadose zone (unsaturated
zone that lies below the bottom of the surface impoundment and above the water table) to the
underlying aquifer (or saturated zone) and then downgradient to a groundwater receptor well.
The exposure concentration is evaluated at the intake point of a hypothetical groundwater
drinking water well located at a specified distance from the downgradient edge of the surface
impoundment. This well is referred to hereafter as the "receptor well." This conceptual model
of the groundwater fate and transport of contaminant releases from the surface impoundment is
illustrated in Figure C.3-1.
The conceptual procedure described here is quantitatively evaluated with a groundwater
model developed by EPA, EPACMTP (U.S. EPA, 1996d,e, 1997b). EPACMTP is a tool that has
been widely peer reviewed and is used by EPA to assess wastes managed in land disposal units
(landfills, surface impoundments, wastepiles, or land application units). EPACMTP simulates
flow and transport of contaminants in the unsaturated zone and aquifer beneath a waste disposal
unit to predict the maximum concentration arriving at a specified receptor well location. For use
in risk assessments, the receptor well concentration can be reported as the peak concentration or
as the highest average concentration over an appropriate exposure time interval.
Fate and transport processes accounted for in the model are advection, hydrodynamic
dispersion, linear and nonlinear sorption at equilibrium, and chemical hydrolysis. The composite
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Appendix C
.WASTE MANAGEMENT UNIT
RESIDENTIAL (RECEPTOR)
WELL
SATURATED
ZONE LEACHATE PLUM
Figure C.3-1. Schematic diagram of groundwater modeling
scenario.
model consists of two coupled modules: a one-dimensional (1-D) module that simulates
infiltration and dissolved contaminant transport through the unsaturated zone and a saturated
zone flow and transport module that can be run in either a fully 3-D or quasi-3-D mode. Quasi-
3-D mode simplifies the fully 3-D flow and transport solutions to one of two 2-D conditions. For
conditions where the saturated zone is thin and the contaminant mass flux into the saturated zone
is large, fully mixed conditions are assumed and an areal (x-y) planar approximation is
implemented. For conditions in which flow in the horizontal transverse (y) direction is of minor
significance, such as when infiltration through the surface impoundment area is relatively low
compared to the groundwater flow rate, a vertical 2-D cross-sectional solution is employed where
a numerical solution is achieved in the x-z plane and an analytical solution is used to expand this
in the transverse (y) direction. EPACMTP uses an automatic criterion for determining which of
these quasi-3-D scenarios to apply based on the combination of aquifer parameters. The
principal benefit of this quasi-3-D approach is that it provides substantial savings in
computational effort, making large-scale Monte Carlo simulations feasible. It is for this reason
that the quasi-3-D approach was used for all of the Monte Carlo runs in this analysis.
It is assumed that the soil and aquifer are uniform porous media and that flow and
transport are described by the flow equation and the advection-dispersion equation, respectively.
The flow equation is based on Darcy's law, which states that the flow per unit area of
groundwater through porous media is the product of hydraulic conductivity and hydraulic
gradient. The advection-dispersion equation describes solute transport by flowing groundwater
(advection) and hydrodynamic dispersion resulting from mechanical mixing and molecular
diffusion.
Flow and Transport Equations Used in EPACMTP. The groundwater flow simulation is
based on the following simplifying assumptions:
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March 26, 2001 Appendix C
• The aquifer is homogeneous.
• Groundwater flow is steady-state.
• Flow is isothermal and governed by Darcy's law.
• The fluid is slightly compressible and homogeneous.
• The principal directions of the hydraulic conductivity tensor are aligned with the
Cartesian coordinate system.
According to Freeze and Cherry (1979), the governing equation for steady-state flow in
three dimensions may be written:
92H 32H 32H .
rXryrZ .
dx2 dy2 dz2
where
H = hydraulic head (m)
kr = relative permeability (dimensionless)
KX, Ky, and Kz = hydraulic conductivities (m/yr) in the longitudinal (x), horizontal
transverse (y), and vertical (z) directions, respectively.
Further details about these parameters may be found in Freeze and Cherry (1979).
Equation (C.3-1) is solved subject to the boundary conditions given in U.S. EPA (1996e).
Flow in the vadose zone is modeled as steady-state, one-dimensional, and vertically
downward from underneath the source surface impoundment toward the water table. The lower
boundary of the vadose zone is the water table. The flow in the vadose zone is predominantly
gravity-driven; therefore, the vertical flow component accounts for most of the fluid flux between
the source and the water table. The flow rate is determined by the long-term average infiltration
rate through the surface impoundment.
For the saturated zone, relative permeability kr is equal to unity. Flow in the saturated
zone is based on the assumption that the contribution of recharge from the unsaturated zone is
small relative to the regional flow in the aquifer and the saturated aquifer thickness is large
relative to the rise due to infiltration from the surface impoundment and recharge outside the
surface impoundment so that the saturated zone can be modeled as having a uniform thickness.
The governing equation for transport in three dimensions is given by (Bear, 1979):
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March 26, 2001 Appendix C
d dc] dc,
D V
dx. 1J dx. \ ' dx.
where
dc, M
-ft/? + ft rn r + >^ n i c
^m (C-3-2)
xh x2, and x3 = x, y, and z Cartesian coordinates, respectively
t = time
Q = concentration of the /-th component species in the nc member decay
chain, ^
Rj = first-order decay coefficient and retardation coefficient, both for
species/
Q, and Qm = correction factors to account for sorbed phase decay of species / and
parent m, respectively
0 = water content
and Einstein summation conventions are used to simplify the notation. For computation of the
longitudinal, horizontal transverse, and vertical dispersion coefficients (Dxx, Dw and Z)zz), the
conventional dispersion tensor for isotropic porous media is modified to allow the use of
different horizontal transverse and vertical dispersivities (U.S. EPA 1996e). The dispersion
coefficients are given by:
999
yl yl yl
D = ar— + ou—- + aT/— + QD *
LIV} TIV} vlv}
V2 vl vz
D - v.T—^- + aT—^- + 0.1,—— + QD*
L\v\ T\v\ v\v\
999
yl yl yl
D = a,^- + a,.—^- + aT/—^- + QD *
L\v\ v\v\ v\v\ (C3.3)
vxv,
Dyz ~ Dzy - (aL - av)^
\v\
z
\v\
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March 26, 2001
Appendix C
where aL, ar, and aFare the longitudinal, horizontal transverse, and vertical dispersivity (m),
respectively, and/)* is the effective molecular diffusion coefficient (m2/yr).
The water content, 0, and Darcy velocity V;, are defined as follows:
(C.3-4)
v
V =
(C.3-5)
where
(p = effective porosity
Sw = degree of water saturation.
In the saturated zone, Sw = 1. Equation (C.3-2) is solved separately for the vadose and saturated
zones. Details of boundary conditions and solution methods are given in U.S. EPA (1996e).
The retardation factor for each of the member species is given by
p,ds
R = 1
e dc
(C.3-6)
where
pb = bulk density (g/m3)
s = adsorbed concentration (g/g)
and
where
S -
(C.3-7)
k, = Freundlich coefficient
r| = Freundlich exponent.
The subscript / has been dropped for convenience. Assuming the adsorption isotherm follows
the equilibrium Freundlich equation, the retardation coefficient can be written as
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March 26, 2001 Appendix C
R - 1 + TiC"1'1 . (C.3-8)
0
The coefficient Q is given by
0 = 1 + TiC"1'. (C.3-9)
0
Note that, in general, the retardation factor is a nonlinear function of concentration. The
Freundlich isotherm becomes linear when the exponent T| = 1 . The Freundlich coefficient, k, in
this case, is the same as the familiar solid-liquid phase partition coefficient, Kd. When sorption is
linear, the coefficients R and Q also become identical. For all the inorganic chemicals reported
herein, r| = 1,^ = 0, and nc=\.
EPACMTP does not account for heterogeneity, preferential pathways such as fractures
and macropores, or colloidal transport, which may affect migration of strongly sorbing
constituents such as metals. However, sites located in karstic terrain may be accommodated by
using the associated solution limestone hydrogeologic environment provided in the
HydroGeologic DataBase (Newell et al., 1990, U.S. EPA, 1997b) used by EPACMTP. The
database is described in more detail in Section C.3.2.2.
EPACMTP simulates steady-state flow in both the unsaturated zone and the saturated
zone; contaminant transport can be either steady-state or transient. The steady-state modeling
option is used for continuous source modeling scenarios; the transient modeling option is used
for finite source modeling scenarios. The output from EPACMTP is a prediction of the
contaminant concentration arriving at a downgradient groundwater receptor well. This can be
either a steady-state concentration value, corresponding to a continuous source scenario, or a
time-dependent concentration, corresponding to a finite source scenario. In the latter case, the
model can calculate the peak concentration arriving at the well or a time-averaged concentration
corresponding to a specified exposure duration (e.g., a 9-year average residence time). For this
analysis, either the peak or the average concentrations were calculated to determine the risks
associated with noncarcinogenic or carcinogenic constituents, respectively. For all modeled
constituents, the groundwater averaging time and exposure duration are assumed to follow a
prespecified probability distribution instead of being input as constant values. For each given
realization, however, the groundwater averaging time and exposure duration are identical.
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For the probabilistic analysis, 10,000 realizations1 were conducted for each modeling
scenario, with the inputs specified as constant values, derived values, or statistical or empirical
distribution of values. Each realization comprises a complete and distinct set of model input
parameters and the flow and transport solution derived from those inputs. The input parameters
for each realization are chosen by EPACMTP from the user-specified values or distributions
based on a sequence of randomly generated numbers.
Source Terms and Release Mechanisms. The release of contaminants into the subsurface
constitutes the source term for the groundwater fate and transport model. Because the modeled
subsurface fate and transport processes are the same for each waste management scenario, the
conceptual differences between different waste management scenarios are reflected solely in how
the model source term is characterized. The contaminant source term for the EPACMTP fate and
transport model is defined in terms of four primary parameters: (1) area of the waste unit, (2)
leachate flux rate emanating from the waste unit (infiltration rate), (3) constituent-specific
leachate concentration, and (4) duration of the constituent leaching. Leachate flux rate and
leaching duration are determined as a function of both the design and operational characteristics
of the waste management unit and the waste stream characteristics (waste quantities and waste
constituent concentrations).
C.3.2.2 Modeling Methodology. The general modeling methodology and assumption for
this analysis are described in this section, in addition to code modifications made specifically for
this analysis, the Monte Carlo modeling approach, and a summary of modeling data sources.
Modeling Infiltration and Recharge Rates. EPACMTP requires inputs for both
infiltration and recharge rates. Infiltration is defined as water percolating through the surface
impoundment to the underlying soil, while recharge is water percolating through the soil to the
aquifer outside of the surface impoundment. For recharge, EPACMTP uses estimates from the
1 The Monte-Carlo groundwater pathway analysis was performed with 10,000 realizations based on the
results of a previous bootstrap analysis to maintain consistency with previous analyses, such as the Petroleum
Refining and Lead Based Paint Analyses. Bootstrap analysis is a technique of replicated resampling (usually by a
computer) of an original data set for estimating standard errors, biases, confidence intervals, or other measures of
statistical accuracy. It can automatically produce accuracy estimates in almost any situation without requiring
subjective statistical assumptions about the original distribution.
In this case, the bootstrap analysis upon which this decision was based was documented in EPACMTP
Sensitivity Analyses (U.S. EPA, 1996d). This report presents a bootstrap analysis conducted in response to public
comments regarding the number of realizations used for the 1995 proposed Hazardous Waste Identification Rule.
In using a Monte Carlo modeling approach, a higher number of realizations usually leads to a more convergent and
more accurate result. However, it is not generally possible to determine beforehand how many realizations are
needed to achieve a specified degree of convergence since the value can be highly dependent on parameter
distributions. Therefore, EPA conducted a bootstrap analysis for the EPACMTP model to evaluate how
convergence improves with increasing numbers of realizations. The analysis was based on a continuous source,
landfill disposal scenario in which the 90th percentile DAF was 10. The bootstrap analysis results suggested that,
with 10,000 realizations, the expected value of the 90th percentile DAF was 10 with a 95 percent confidence interval
of 10±0.7. The 95 percent confidence interval was near asymptotic. Because the parameter distributions used in
the analyses for HWIR and this analysis are similar, the HWIR-related bootstrap analysis results were considered
applicable.
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March 26, 2001 Appendix C
HELP model, a hydrologic model for conducting water balance analysis of landfills, cover
systems, and soil systems (U.S. EPA, 1994a, b). In the context of EPACMTP, HELP has been
run for three soil textures (sandy loam, silt loam, silty clay loam) and 97 climatic centers across
the country to represent nationwide variability in soil properties, cover characteristics, and
climatic data (e.g., precipitation and evapotranspiration) that affect recharge and infiltration rates.
For this risk assessment, recharge rates were selected from this set of data to represent site
conditions of each facility.
Infiltration rates for this analysis were calculated using the semi-analytical solution
defined below. Impoundment-specific data were used where available. In cases where the base
of the impoundment is at or below the water table, the leachate flux to the aquifer was calculated
outside of EPACMTP (using the method described in Bear, 1979), and this flux was directly
applied to the saturated zone; that is, the vadose zone was not modeled.
A semi-analytical solution technique used in EPACMTP allows a very efficient and
accurate solution of the vertical steady-state flow resulting from a surface impoundment unit.
The surface impoundment scenario consists of a surface impoundment unit overlying a liner
overlying the soil in the vadose zone. Ideally, an accurate method of determining the infiltration
rate through the liner is to solve the variably saturated flow equation in a composite domain
consisting of the liner and the vadose zone. However, this method requires a fine discretization to
describe a relatively sharp pressure profile above the interface between the liner and the
underlying soil. A simpler but conservative approach was, therefore, adopted by EPA.
Infiltration rate through the liner is obtained by solving the non-linear variably saturated flow
equation for the one-dimensional vertical flow domain encompassing the liner and the vadose
zone soil (U.S. EPA, 1996e). For computational efficiency, the liner is assumed to be saturated
at all times, and the gradient across the liner is uniform and may be approximated using the
ponding depth (i.e., the height of wastwaters above the liner) and the thickness of the liner. The
method tends to overestimate infiltration rate when the ponding depth is relatively small. When
the ponding depth is relatively large, the infiltration rates estimated using the current method in
EPACMTP approach the respective rates determined by the variably saturated flow equation.
An independent computational model has recently been developed to assist in estimating
infiltration from surface impoundment units by solving the variably saturated flow equation in
the whole flow domain (U.S. EPA, 1999e). This module allows the sediments at the bottom of
the unit to settle and be consolidated by the overlying hydrostatic and loose sediment loads. In
this case, the hydraulic function of the consolidated sediment layer is equivalent to that of a liner.
In the module, the flow domain encompasses the compacted sediment and the native material in
the vadose zone.
In the simulations described here, the EPACMTP effective liner layer consists of two
components: a layer of in-unit compacted sediment derived from sludge solids in the waste
water, underlain by a liner reported by the owner of the surface impoundment unit. The effective
hydraulic conductivity of the effective liner layer is determined using the harmonic mean of the
hydraulic conductivity of the liner (reported by the owner/ operator) and the consolidated
sediment hydraulic conductivity using the constitutive relationship between the hydrostatic loads
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March 26, 2001 Appendix C
above the consolidated sediment and hydraulic conductivity of the consolidated sediment (U.S.
EPA, 1999e). When no liner information is reported, only the in-unit sediments contribute to the
determination of the liner conductivity. The thickness of the compacted sediment is assumed to
be one-half the total thickness of the sediment. If the total thickness of the sediment is not
reported, a default value of 15 cm is used for the compacted sediment thickness. If the liner
conductivity is not available, a value of l.OxlO"7 cm/s is assumed. The compacted sediment
conductivity is given by the constitutive relationship between hydraulic conductivity and
water-and-loose-sediment load as given in the HWIR99 background document for the surface
impoundment source module (U.S. EPA, 1999e).
Infiltration rates for the composite-liner scenario, consisting of a clay liner with a flexible
membrane liner (FML) on top of the clay layer, were computed using a liner leakage equation
developed by Bonaparte et al. (1989) to estimate leakage through pinholes in a geomembrane for
good contact conditions:
/~\ rv r\i 0 1 7 0.9 7 0.74 ,„ „ , _>.
QL=Q2\-av>A-hw -ks (C.3-10)
where
QL = rate of leakage through a circular hole in the geomembrane component of the
composite liner (m3/s)
a = geomembrane hole area (m2)
hw = head of liquid on top of the geomembrane (m)
ks = hydraulic conductivity of the low-permeability soil component of the
composite liner (m/s).
A geomembrane hole was assumed to have an area of 3xlO"6 m2 and a hole density of 1 hole per
acre of membrane. These assumptions are consistent with those in IWEM (U.S. EPA 1999b, c).
Location and Time of Exposure. The selected receptors for the groundwater pathway
were hypothetical adult and child residents who obtained drinking water from a groundwater
well. The exposure point was determined as the nearest drinking water well likely to be exposed
to constituent releases migrating through the groundwater from a surface impoundment at a
facility. The nearest drinking water well was identified by an examination of each facility's
topographic map and selecting wells in the probable direction of groundwater flow. Based on
survey responses, these are well locations in potential use by residents.
The location of the receptor well is confined for each surface impoundment to a circular
arc defined by an angle "THETA." The angle THETA is defined as the angle of the well off the
plume centerline (based on the best estimate of the local groundwater flow direction) plus a small
C-95
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March 26, 2001 Appendix C
amount as an additional margin of safety. For a fixed groundwater flow direction, THETA may
be viewed as uncertainty associated with the well location. Conversely, for a fixed receptor well
location, THETA implies uncertainty with respect to the groundwater flow direction. Since site
maps were furnished with defined well locations, THETA is considered to be a measure of the
uncertainty in the groundwater flow direction.
A potential problem arises in the event that multiple surface impoundments are present at
a given facility. For consistency in calculating risks, it is imperative that all impoundments at a
given facility have the same degree of uncertainty associated with the inferred average
groundwater flow direction. This can be done by using a common angle THETA for all units at a
given facility. Thus, THETA, the average uncertainty with respect to the groundwater flow
direction at a given site, is defined as the sum of two angles:
• The average of the impoundment-specific values for THETA at that facility
• A small angle to account for an error margin.
The error margin is subjective and has been set to 5 degrees for all facilities for this analysis
based on professional judgment. In the Monte Carlo EPACMTP modeling conducted for this
project, THETA is enforced by assigning a minimum and a maximum value whose difference is
THETA. Geometrically, the corresponding well locations for respective surface impoundments
are located near one another; however, these locations are not quite identical. Effects due to this
geometrical inexactitude are considered insignificant when compared with those due to other
uncertainties in the modeling scenario.
A distribution of 10,000 exposure durations was selected from a Weibull distribution
corresponding to all nonfarming residents and applied to all Monte Carlo simulations. The
selection of the shape and scaling parameter for the Weibull distribution are described in Table
C.3-15.
Description of Required Code Modifications. For the Surface Impoundment Study, only
two modifications were made to EPACMTP to facilitate the groundwater analysis. EPACMTP
Version 1.2.2 was created specifically for the Inorganics Listing Determination (U.S. EPA,
2000b) and subsequently tested (U.S. EPA, 2000e). In addition to the main input data file, an
extra input file may be specified in EPACMTP version 1.2.2, also referred to as the source data
file. The source data file contains values of parameters whose distribution types are set to "88" in
the main input data file. The source data file permits output from source models or previous
simulations of EPACMTP to be used as input to EPACMTP and provides the means to correlate
parameters, such as leachate concentration, infiltration rate, and soil and aquifer type, to facility
location. Version 1.2.2 limited the depth of the receptor location to vary uniformly throughout
the aquifer thickness or throughout the upper 10 m of the aquifer thickness, whichever is less.
That is, the well depth is never allowed to exceed 10m below the water table. For this study, the
10-m depth restriction was removed.
In addition, logic was added to version 1.2.2 to override the existing receptor well
location algorithm to permit the user to specify a constant value for the angle between the well
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March 26, 2001 Appendix C
location and the plume centerline. This constraint was relaxed to allow the user to specify a
range for the angle. The resulting EPACMTP version is version 1.2.3.
Monte Carlo Analysis. Application of the EPACMTP model requires input values for the
source-specific, chemical-specific, unsaturated zone-specific, and saturated zone-specific model
parameters. Each of these input parameters can be represented by a probability distribution
reflecting the range of variation that may be encountered at the modeled waste site(s). The fate
and transport simulation modules in EPACMTP are linked to a Monte Carlo module to allow
quantitative estimation of the uncertainty in the downgradient receptor well concentration due to
uncertainty and variability in the model input parameters.
Following is a brief description of the general Monte Carlo methodology used in
EPACMTP. Additional information about Monte Carlo modeling using EPACMTP can be
found in EPACMTP documents (U.S. EPA, 1996c, 1996e, 1997b).
The Monte Carlo option in EPACMTP is based on the module incorporated in EPA's
Composite Model for Landfills (EPACML) (U.S. EPA, 1990). This module has been enhanced
in three ways: (1) to account more directly for dependencies between various model parameters
by using data from actual waste sites across the United States (2) to include a site-based
methodology to directly associate the appropriate regional climatic and hydrogeologic conditions
to the location of a waste site, and (3) to account for statistical correlations between two or more
model parameters (e.g., hydraulic conductivity and gradient) when missing parameter values are
generated.
The EPACMTP input parameters considered in the groundwater Monte Carlo modeling
are presented in Table C.3-12. For modeling the surface impoundment, the depth of the sludge
layer and the ponding depth were set to a constant value based on facility information; the
hydraulic conductivity of the sediment layer at the base of impoundment and the underlying
unsaturated zone were derived as described in the surface impoundment module documentation
(U.S. EPA, 1999a).
Modified Regional Site-Based Methodology. The regional site-based approach offers
several advantages over a strictly nationwide methodology. This methodology relies on data
compiled at actual waste sites around the country, which can be linked to databases of climatic
and hydrogeologic parameters through the use of climate and hydrogeologic indices. Thus, the
regional site-based approach attempts to approximate the ideal situation where a complete set of
the required site-specific values is available for each Monte Carlo realization without requiring
the extensive sampling that would be required to actually gather these data.
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Appendix C
Table C.3-12. EPACMTP Input Parameters for Monte Carlo Modeling
Impoundment Scenario/Parameter
Surface impoundment scenario
WMU area (m2)
Leachate concentration
Regional recharge rate (m/yr)
Infiltration rate (m/yr)
Pulse duration (yr)
Depth of wastewater (m)
Liner thickness (m)
Liner conductivity (m/yr)
Chemical-specific parameters
Organics
Hydrolysis rate (yr"1)
Koc (L/kg)
Inorganics
^(L/kg)
Both organics and inorganics
Exposure duration (yr)
Unsaturated zone parameters
Sat. hydraulic cond (cm/h)
Hydraulic parameter, a (cm"1)
Hydraulic parameter, p
Residual water content
Saturated water content
Depth to groundwater (m)
Organic matter content (%)
Bulk density (g/cm3)
Input Data Source
Site-specific data from SI Survey
Site-specific data from SI Survey
Location-specific from national distribution based on proximity of
facility to climate station (U.S. EPA, 1997b)
Derived using EPACMTP model or Darcy's law if liner is below water
table
Site-specific data from SI Survey or 50 years if impoundment is still
operational and has operational life less than 50 years
Site-specific data from SI Survey or schematic drawings, if available
Site-specific data from SI Survey or schematic drawings, if available
Site-specific data from SI Survey or schematic drawings, if available,
else assumed to be l.Oe-7 cm/s [3.15e-02 m/yr]
Constituent-specific (Kollig et al., 1993)
Constituent-specific (Kollig et al., 1993)
Empirical or statistical distribution of values from the scientific literature
(U.S. EPA, 2000b)
Weibull-based distribution; same for all Monte Carlo simulations
Distribution based on soil type (Carsel and Parrish, 1988)
Distribution based on soil type (Carsel and Parrish, 1988)
Distribution based on soil type (Carsel and Parrish, 1988)
Distribution based on soil type (Carsel and Parrish, 1988)
Distribution based on soil type (Carsel and Parrish, 1988)
Site-specific data from SI Survey or schematic drawings, if available,
else distribution on HG region8 (Newell et al., 1990)
Distribution based on soil type (Carsel et al., 1988)
Distribution based on soil type (Carsel et al., 1988)
(continued)
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Appendix C
Table C.3-12 (continued)
Impoundment Scenario/Parameter
Saturated zone parameters
Particle diameter (cm)
Saturated thickness (m)
Hydraulic conductivity (m/yr)
Hydraulic gradient (m/m)
Longitudinal dispersivity (aL)
Transverse dispersivity (OT)
Vertical dispersivity (ocv)
Groundwater temperature (°C)
Groundwater pH
Fraction organic carbon
Receptor well location
Radial well distance (m)
Angle off plume centerline (°)
X-well distance (m)
Y-well location (m)
Z-well depth (m)
Input Data Source
National distribution (U.S. EPA, 1997b)
Site-specific data from SI Survey or schematic drawings, if available,
else distribution based on HG region a (Newell et al., 1989)
Site-specific data from SI survey if available, else distribution based on
HG region3 (Newell et al., 1989)
Site-specific data from SI survey if available, else distribution based on
HG region a (Newell et al., 1989)
Derived from distance to well (Gelhar et al., 1992; U.S.EPA, 1997b)
Derived from distance to well (Gelhar et al., 1992; U.S.EPA, 1997b)
Derived from distance to well (Gelhar et al., 1992; U.S.EPA, 1997b)
Location-specific
Value based on soil type
National distribution (U.S. EPA, 1997a)
Site-specific data from topographic maps
Site-specific data from topographic maps
Derived from radial distance to well and angle off the plume centerline
Derived from radial distance to well and angle off the plume centerline
Uniformly distributed throughout saturated thickness
1 HG is the HydroGeologic database for modeling (Newell et al., 1990; U.S. EPA, 1997b).
The specific methodology for data gathering employed for this risk assessment can be
summarized as follows:
• For sites where adequate site-specific data on soil and aquifer parameters were not
available: (1) the site's geographic location was correlated with available GIS
data and aquifer maps to classify the underlying aquifer as 1 of 13 types and to
classify the soil as 1 of 3 types; (2) the site's geographic location was used to
place the site within 1 of 97 climatic regions in the continental United States; and
(3) the hydrogeologic and climatic indices were then used to define the site-
specific distributions of hydrogeologic and climatic parameter values,
respectively.
• For sites where adequate site-specific data on soil and aquifer parameters were
available: (1) site-specific data were used to define the percentage of the three
soil types present at the site and their associated pH, and values (or distribution of
values) for aquifer parameters; and (2) the site's geographic location was used to
place the site within 1 of 97 climatic regions in the continental United States, and
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March 26, 2001 Appendix C
this climatic index and the soil type(s) present at the site were then used to define
the site-specific recharge rate.
Once the percentages of soil types were defined for a facility, an ensemble of 10,000 soil
type identifiers (1, 2, or 3) was randomly generated respecting the distribution of soil type
percentages. These identifiers were used in the Monte Carlo simulation for all impoundments at
a facility to choose from the appropriate distribution of values appropriate for that soil type
(Carsel et al., 1988). These distributions are specified within the EPACMTP code, as described
in U.S. EPA(1997b).
Data sources for the modified regional site-based methodology that were used to conduct
this analysis include: (1) the infiltration and recharge analysis performed for 97 U.S. climatic
centers using the HELP model (U.S. EPA, 1997b); (2) the USGS inventory of the groundwater
resources of each state (USGS, 1985); and (3) the HydroGeologic DataBase for Modeling
(HGDB) (Newell et al., 1990; U.S. EPA, 1997b), developed from a survey of hydrogeologic
parameters for actual hazardous waste sites in the United States.
For this analysis, facility-specific values for impoundment location and waste, soil, and
aquifer characteristics were used to the extent possible. Where site-specific data were not
available, the following parameters were available from the HGDB database (Newell et al., 1990;
U.S. EPA, 1997b):
• Depth to groundwater (m)
• Aquifer thickness (m)
• Hydraulic conductivity (m/yr)
• Hydraulic gradient (m/m).
Given a hydrogeologic environment, 10,000 values for the above four parameters were
selected as correlated parameters according to the methodology described in U.S. EPA (1997b).
If reliable site-specific values for any of the four were available, that value was used instead of
the generated values. In most cases, sufficient information existed to establish values for the
depth to groundwater and the thickness of the saturated region. Information about the remaining
hydrogeologic parameters, hydraulic gradient and hydraulic conductivity of the aquifer, were
generally not available, therefore, these parameters were generated using the hydrogeologic
environment classification. It was assumed that the loss in correlation by supplanting correlated
parameters with site-specific parameters was more than equaled by the uncertainty in other
parameters (i.e., groundwater flow direction).
For surface impoundments, the infiltration rate was calculated using EPACMTP; the
ambient recharge rate was set equal to the HELP model recharge rate for the nearest climate
center.
For facilities without adequate site-specific data, the USGS inventory of state
groundwater resource maps (USGS, 1985) and available GIS data were used to identify the
predominant hydrogeologic environment (or aquifer type) underlying each impoundment to be
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March 26, 2001 Appendix C
modeled. Once the aquifer type was determined, the HGDB was then used to specify the
probability distribution for each of the groundwater parameters. The HGDB provides data on
depth to groundwater, aquifer thickness, hydraulic gradient, hydraulic conductivity, and
hydrogeologic classification for approximately 400 hazardous waste sites nationwide. These
site-specific data were then regrouped according to hydrogeologic classification, and 13 aquifer
types were classified (12 specific environments and one category called "other"). Each aquifer
type consists of a distribution of values for each of the four aquifer parameters.
For this analysis, each site to be modeled was located on the appropriate state
groundwater map from USGS (1985), and available GIS data were compiled and evaluated.
Then the primary aquifer type for that location was classified according to the 13 aquifer types.
The aquifer types and the parameter values for each are provided in the EPACMTP User's Guide
(U.S. EPA, 1997b).
C.3.2.3 Chemical Data. Chemical properties used in the analysis include hydrolysis rate
constants and the organic carbon partition coefficient Koc for the organic constituents and soil-
water partition coefficients for metals. These were collected from measured literature values as
available and are described in U.S. EPA (2000b, c).
Many of the chemical constituents present at facilities included in this phase of the
analysis can be characterized as conservative in that they do not sorb (Koc=0) nor hydrolyze
(lambda = 0) in partially or fully saturated environments. Conservative chemicals behave
linearly with respect to advective and dispersive contaminant transport: an increase or decrease
in the source concentration results in a proportional increase or decrease in observed
concentrations in the groundwater. This behavior permits the use of a single surrogate chemical
to represent all conservative chemicals.
All conservative chemical constituent modeling at a unique facility/impoundment
combination was represented by a surrogate constituent in a single Monte Carlo simulation. The
resulting normalized peak and average concentrations for the surrogate were then scaled by the
leachate concentration of the constituents escaping the impoundment to produce
constituent-specific results. For organics, a conservative constituent is defined as one with Koc
value equal to or less than that of benzene (Koc = 63.1 L/kg; since the values in the nationwide
distribution of fraction organic carbon are generally small, the resulting average unsaturated zone
retardation coefficient for benzene is 1.17) and with an average hydrolysis rate in the unsaturated
zone equal to or less than l.OE-4 1/yr (this criterion was used to define nondegraders in modeling
conducted for the 1995 HWIR proposed rule). Fluoride was also considered to behave as a
conservative constituent since it is an anion in solution under environmental conditions.
To test the above assumptions, a chemical-specific modeling run was conducted for each
of two of the organic constituents assumed to be conservative to verify our assumption that they
behave conservatively during subsurface transport: benzene (in the impoundment at Facility
174) and chloroform (in impoundment 1 at Facility 23). Benzene was chosen because it has the
highest Koc of the organic constituents assumed to be conservative. Chloroform was chosen
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March 26, 2001
Appendix C
because it has the highest hydrolysis rate of the organic constituents assumed to be conservative.
No toxic daughter products were simulated in this analysis.
Test results are presented in Table C.3-13 as percent differences for select percentiles of
the dilution-attenuation factor between simulations using constituent-specific constants (Koc and
hydrolysis rates) and conservative surrogate assumptions (Note: the 10th percentile DAF
Table C.3-13. Percent Difference for Selected Percentile DAFs for
Benzene and Chloroform
Select Percentiles
for DAF
50
25
20
15
10
5
2.5
1
Benzene
% Difference for
Average DAFa
5.4%
7.4%
6.9%
7.8%
8.6%
5.9%
7.2%
4.9%
Chloroform
% Difference for
Average DAFa
1.6%
2.4%
5.8%
5.2%
6.1%
5.8%
7.5%
1.9%
1 Percent difference is calculated as (Conservative Constituent
Average DAF - Surrogate Average DAF)/Conservative
Constituent Average DAF.
corresponds to the 90th percentile concentrations, peak and average). The maximum difference in
the lower half of the distribution is 8.6 percent and represents the worst case scenario under this
assumption.
The metals-modeling methodology in EPACMTP incorporates two options to specify the
Kd for a given metal: distributions of values or sorption isotherms. For this analysis, the Kd for
metals was defined based on a comprehensive review of literature Kd values performed for the
Inorganics Listing Determination (U.S. EPA, 2000b). Based on this review, Kd was defined as an
empirical distribution when sufficient data are available or a log uniform distribution of values
when fewer data are available from the scientific literature. The second option is the automated
use of adsorption isotherms, which are expressions of the equilibrium relationship between the
aqueous concentration and the sorbed concentration of a metal (or other constituent) at constant
temperature. This second option was not used for this analysis because of current modeling
limitations for generating metal sorption isotherms.
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C.3.2.4 Sources for Site andHydrogeologic Parameter Values. Data collected from the
surveys and any supporting information, such as reports and diagrams, were examined to extract
the maximum amount of reliable site-specific data for use in this analysis. The data included
information on impoundment areas, volumetric flows of wastewater and sludge into
impoundments, liner information, constituents present in wastewaters and their concentration,
operation life, and maps that identify real and potential receptor wells and surface waterbodies.
Survey data were also cross-referenced with other data sources to supplement the data collection
effort. These sources include STATSGO (U.S. EPA, 1998d), HGDB (Newell et al., 1990), and
meteorological databases.
C.3.2.5 Facility-Specific Modeling Approach. The groundwater modeling approach
adopted for this analysis attempted to incorporate the maximum amount of facility-specific data
available from the following primary sources: survey responses, topographic maps, and
schematic drawings. Technical reports, when provided by respondents, were also used in
extracting parameter values. Table C.3-12 identifies the sources for specific input modeling
parameters.
The following general procedure was applied to all facilities modeled in this analysis:
• Groundwater Flow Direction - Assess topological details on provided maps to
determine the most probable flow direction; decision may be supplemented by
technical reports, when available.
• Receptor Location Selection - Using topological maps and the assumed flow
direction, identify the downgradient receptor well screened in the surficial aquifer
nearest to the impoundment most likely to be impacted by a migrating
contaminant plume. If multiple impoundments are present at the facility, select
the receptor location that is most likely to be impacted by the most
impoundments; if no receptor wells are identified, use identified residences.
• Radial Receptor Well Distance and Angle Off Plume Centerline- Determine the
radial distance as shortest distance from each impoundment to the selected
receptor location. Measure the angle defined by the radius and the groundwater
flow direction; these angles will be used to calculate the angle range used in the
simulation to account for uncertainty in flow direction. The method for angle
range calculation is
Determine average angle, THETA and for each impoundment at the
facility
Min Angle = maximum ( 0°, THETA - Angle)
Max Angle = maximum (THETA, Angle) + 5°
• Extract Impoundment-Specific Data - Collect the following parameters from the
survey: impoundment area, operational life, liner thickness and conductivity,
depth of wastewater and sludge in the impoundments, depth to groundwater,
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March 26, 2001 Appendix C
saturated thickness, aquifer hydraulic conductivity, and regional groundwater
gradient, if available. If multiple sources exist for parameter values, the most
conservative value is used (e.g., survey indicates wastewater depth is 1m and
schematic prescribes a 2-m depth, the value from the schematic is used).
• Calculate Effective Liner Parameters - Combine sludge and liner information to
determine the effective liner conductivity and thickness. If bottom of
impoundment is below the water table, calculate an infiltration rate using the
gradient across the liner and compacted sludge (Darcy's law [Bear, 1979]).
• Chemical Parameters - Group constituents present in wastewater into conservative
and nonconservative populations using the guidelines described in Section
C.3.2.2. Select chemical constituent parameters/distributions needed for
simulating sorption and decay processes. Extract the leachate concentration of
each constituent from survey data.
• Compilation of Data - Combine and supplement the above parameters with
region-based and location-based parameters/parameter distributions as described
in Section C.3.2.2 with exposure duration distribution to create input files and
source data files.
The results of the data extraction process are presented in Attachment C-10 of this
Appendix.
C.3.3 Methods - Exposure/Risk Calculations
The purpose of exposure and risk assessment is to estimate a contaminant dose to each
receptor by combining modeled groundwater concentrations with relevant intake rates for the
individuals being modeled. The dose, coupled with the relevant human health benchmarks,
allows an estimation of human health risk and/or hazard. This assessment focused on chronic
cancer risk and noncancer hazard resulting from tap water ingestion. Consequently, for this
analysis, exposure assessment involved combining modeled residential well concentrations with
adult and child tap water ingestion rates and exposure durations to generate both average daily
dose estimates for noncarcinogens and lifetime averaged daily dose estimates for carcinogens.
For all impoundments evaluated in this analysis, groundwater was assumed to be
contaminated from contaminants leaching from the impoundment, through the vadose zone, into
the underlying aquifer, and migrating to the offsite residential well location. It was further
assumed that the groundwater well was used as the sole source of tap water for the adults and
children living in that residence.
Both child and adult residents were modeled in this analysis. For noncancer risk, a child
in the 1- to 6-year-old age range was modeled. Note: The use of the 1- to 6-year-old child cohort
in this analysis excluded exposures in the first year of life. For carcinogenic risk, an adult
resident between the ages of 20 and 64 was modeled.
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March 26, 2001 Appendix C
C.3.3.1 Exposure Parameter Variability Distributions Used in Probabilistic Analysis.
The probabilistic analysis requires exposure parameter variability distributions for exposure
duration and tap water ingestion rates. Although water ingestion rates were required for both the
adult and child, exposure duration is required only in cancer risk calculations; therefore, exposure
duration variability data were needed only for the adult. See Section C.3.2 for a discussion of
exposure duration.
Tap Water Intake Rates. Tap water ingestion rate data standardized for body weight (i.e.,
with units of mL/kg-d) were used in this analysis. Because intake data that were standardized for
body weight were used, body weight was not a variable in the analysis.
The statistical parameters used to derive the distributions for tap water ingestion rates are
presented in Table C.3-15. A critical issue in using continuous variability distributions in
probabilistic risk analysis is the truncation of these distributions to avoid inclusion of exposure
parameter estimates that are unreasonable (truncation is typically not an issue with discrete
distributions since the upper-bound values in these distributions are generally defined as the
highest percentile value for which data are available from the underlying study). In selecting the
truncation strategy to develop continuous distributions, care must be taken to avoid the inclusion
of unrealistic values, while still allowing for consideration of individuals who could experience
intake rates beyond the 99th percentile (i.e., high-end exposure). A number of different strategies
have been used in previous analyses to truncate exposure parameter variability distributions,
including (1) setting the upper bound between 2 and 3 standard deviations, and (2) setting the
upper bound at twice the 99th percentile. For this analysis, exposure parameter variability
distributions for tap water ingestion rates were truncated at 3 standard deviations. This approach
produced upper-bound tap water ingestion rates that fell between the 99th percentile and twice the
99th percentile, which represents a reasonable approximation of high-end behavior without
including unreasonably high intake rates, yet allows the possibility of exposures above the 99th
percentile. The truncation values for each of the tap water ingestion rate variability distributions
are also included in Table C.3-15. Tables C.3-16 and C.3-17 present the intake rate data from
the lognormal distributions developed for this risk assessment and compare them with the
empirical data presented in Tables 3-7 and 3-30 in the EFH.
Average Daily Dose for Children (Noncancer Endpoints). The average daily dose (ADD)
estimates for the child resident receptor were generated by combining a daily intake rate that
reflected variability in tap water ingestion rates with a residential well concentration. This
produced a distribution of 10,000 ADD estimates. The ADD distribution was used, in turn, to
generate a distribution of 10,000 noncancer HQs for each surface impoundment constituent
combination for the child resident receptor.
The daily intake rate for the child resident was generated using a two-step procedure for
determining tap water ingestion rate variability for the 1- to 6-yr-old cohort. The procedure
involved: (1) random selection of either the 1- to 3- or 4- to 6-yr-old cohort for the child being
modeled and (2) random sampling of a tap water ingestion rate from the tap water ingestion rate
distribution for that age. This approach generated a daily intake rate for the child resident that
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March 26, 2001
Appendix C
Table C.3-15. Variability Distributions for Exposure Parameters Used in
Probabilistic Risk Analysis
Receptor Population/
Cohort Age Group
Percentile Values and Statistical
Parameters Used to Define Discrete and
Continuous Variability Distributions
References/Comments
Tap water ingestion rates (mL/kg-d)
1-to 3-yr-old cohort
lognormal distribution:
mean: 46.8
STD:28.1
truncation value (3 standard deviations):
211.35
1997EFHTable3-7
1997EFHTable3-7
derived
4- to 6-vr-old cohort
lognormal distribution:
mean: 37.9
STD:21.8
truncation value (3 standard deviations):
164.26
1997EFHTable3-7
1997EFHTable3-7
derived
Table C.3-16. Comparison of Lognormal Distribution with
Empirical Data for Percentiles of Tap Water Intake Rates for Adults
Percentile
1%
5%
10%
25%
50%
75%
90%
95%
99%
Lognormal
Distribution
(based on Table 3-7)
mL/kg-d
5.40
7.50
9.10
12.50
17.50
24.50
33.60
40.40
57.50
Empirical Data
Total Tap Water Intake
(Table 3-7)
mL/kg-d
2.2
5.9
8
12.4
18.2
25.3
33.7
40.0
54.8
Recommended Drinking
Water Intake Rates
(Table 3-30)
mL/kg-d
19
34
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March 26, 2001
Appendix C
Table C.3-17. Comparison of Percentiles of Tap Water Intake Rates Between Lognormal
Distribution and Empirical Data for Empirical Data for Child Age Groups (mL/kg-d)
Percentiles
1%
5%
10%
25%
50%
75%
90%
95%
99%
Lognormal
Distribution"
Empirical Data
for Total Tap
Water Intake3
1-to 3-yr-old
11.1
15.8
19.6
27.4
39.6
75.7
81.1
99.4
144.1
2.7
11.8
17.8
27.2
41.4
60.4
82.1
101.6
140.6
Lognormal
Distribution"
Lognormal
Distribution"
4-to 6-yr-old
9.6
13.7
16.5
22.9
32.7
47.1
65.6
78.6
112.7
3.4
10.3
14.9
21.9
33.3
48.7
69.3
81.1
103.4
aBased on Table 3-7 of Exposure Factors Handbook (U.S.EPA, 1997c).
reflected the age-specific differences in tap water ingestion rates that occurs within the 1-to 6-yr-
old cohort.
Cohort aging was not considered in characterizing noncancer risk for the child resident
because emphasis was placed on capturing the highest chronic exposure level within this age
group, which was expected to occur in children in the youngest cohort due to their higher intake
rate to body weight ratio. The exposure parameter variability distributions for tap water
ingestion for both the 1- to 3- and 4- to 6-year-old cohorts were normalized for body weight
(intakes are expressed as L/kg-d), which eliminated the need to account for the correlation
between body weight and tap water ingestion rate.
Once the daily intake rate data set was generated, it was combined with the residential
well concentration data set to generate a discrete distribution of ADD estimates. The following
equation was used to generate each ADD estimate for the child resident receptor:
rn x f~*
drinking water
1 L
1000 mL
(C.3-11)
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March 26, 2001
Appendix C
Parameter
ADDchlld
IR
r
v^ drinking water
Definition (units)
Modeled average daily dose for the child resident receptor (mg/kg-d)
Tap water ingestion rate sampled from the 1 - to 6-yr-old cohort variability
for tap water ingestion normalized for body weight (mL/kg-d)
distribution
Peak modeled annual drinking water well constituent concentration (mg/L)
The generalized distribution of the child ADD without the residential well concentration
component is the same as the child intake distribution converted to liters per kilogram per day.
The ADD distribution percentiles are presented in Table C.3-18. The ADD is then divided by
the non-cancer RfD to develop the hazard quotient (HQ).
Table C.3-18. Percentiles for Child ADD (L/kg-d)
Percentiles
1%
5%
10%
25%
50%
75%
90%
95%
99%
Lognormal
Distribution3
1- to 6-yr-old
0.0101
0.0144
0.0178
0.0249
0.0359
0.0525
0.0731
0.0893
0.1296
Total Tap Water Intake"
1- to 3-yr-old
0.0027
0.0118
0.0178
0.0272
0.0414
0.0604
0.0821
0.1016
0.1406
4- to 6-yr-old
0.0034
0.0103
0.0149
0.0219
0.0333
0.0487
0.0693
0.0811
0.1034
1- to 6-yr-old
(average of 1- to 3-yr-
old and 4- to 6-yr-old)
0.0031
0.0111
0.0164
0.0246
0.0374
0.0546
0.0757
0.0914
0.122
Recommended
Drinking Water
Intake Rates0
1- to 10-yr-old
0.031
0.064
0.0794
a Based on Table 3-11 of Exposure Factors Handbook (U.S. EPA, 1997c)
b Based on Table 3-7 of Exposure Factors Handbook (U.S. EPA, 1997c)
c Based on Table 3-30 of Exposure Factors Handbook (U.S. EPA, 1997c)
Lifetime Average Daily Dose (LAPP) for Adult (Cancer Endpoints). The LADD for the
adult resident were estimated by combining 10,000 Monte Carlo-generated lifetime averaged
daily intake rates for the adult resident with 10,000 Monte Carlo-generated drinking water well
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March 26, 2001
Appendix C
concentrations for a given surface impoundment/constituent. The groundwater averaging time
used to estimate the residential well concentration was matched with the exposure duration for
each iteration of the risk estimate. For the adult resident, an exposure duration and a single tap
water ingestion rate were sampled. An averaging time of 70 years was also used in this
calculation. The equation used to generate each LADD estimate for the adult resident is
^ x 77? x
drinking water adult cohort
adult cohort
1 L
LADD, „
adult
1,000 mL
(C.3-12)
AT x 365
Parameter
LADD adult
r
^ drinking water
IR adult
-ED adult
EF
AT
Definition (units)
Modeled lifetime average daily dose for the adult resident receptor (mg/kg-d)
Modeled drinking water well constituent concentration derived using an averaging time
that corresponds to the exposure duration sampled for this LADD estimate (mg/L)
Tap water ingestion rate sampled from the adult variability distribution for tap water
ingestion normalized for body weight (mL/kg-d)
Exposure duration value sampled for this modeled adult resident (yr)
Exposure frequency (d/yr)
Average lifetime used to generate a lifetime average intake rate (d).
Note: LADD estimates are generated using an exposure frequency of 350 d/yr and an average lifetime of
25,500 days (i.e., 365 d x 70 yr).
The generalized distribution of the adult LADD without the residential well concentration
component is presented in Table C.3-19. The LADD is multiplied by the oral CSF to calculate
the cancer risk.
C.3.4 Results from Groundwater Pathway Analysis
C.3.4.1 Direct Exposure Pathway Screening Results. A total of 186 constituents present
in 435 surface impoundments at 127 facilities were considered in the preliminary screen. When
constituent concentrations reported in the surface impoundments were compared to human health
screening factors based on toxicity benchmarks for direct ingestion of drinking water, 109
constituents in 320 surface impoundments at 101 facilities exceeded the human health
benchmark. The constituent counts reflect only those chemicals for which at least one human
health benchmark was available. Complete results from the direct exposure pathway screening
analysis are presented in this appendix.
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Appendix C
C.3.4.2 Screening-Level Modeling Results. For those constituents, impoundments, and
facilities that did not screen out in the preliminary screen, a more realistic assessment of
groundwater risk was calculated using IWEM; in this case, 76 constituents in 214 surface
impoundments at 71 facilities exceeded the criteria.
Table C.3-19. Percentiles of Generalized Adult LADD
Percentile
1%
5%
10%
25%
50%
75%
90%
95%
99%
Adult LADD (L/kg-d)
0.000573
0.00089
0.00116
0.00187
0.00335
0.00587
0.00953
0.0125
0.0201
C.3.4.3 Site-Based Modeling. Site-based modeling was conducted for 10 facilities and a
total of 39 surface impoundments. There were a total of 30 HQ exceedances and 48 risk
exceedances for all facilities, impoundments, and constituents for all risk/hazard estimation (i.e.,
for all central tendancy and high-end estimations. There were six 50th percentile HQ exceedances
and fifteen 50th percentile risk exceedances. Also, there were four incidences where a chemical
had an exceedance for both HQ and risk. Therefore, there were a total of 53 different
facility/impoundment/chemical combinations that showed an exceedance of either HQ or risk out
of a possible 202 facility/impoundment/chemical combinations.
Seven of the 10 facilities had at least one exceedance and 24 of the 39 impoundments had
at least one exceedance. A summary of exceedances is presented in Table C.3-20. Each
modeled facility/impoundment combination is presented in Table C.3-20. If an exceedance was
observed, the chemical that exceeded the threshold is noted, followed by the HQ or cancer risk
that was observed for that chemical. The central tendency value for that particular exceedance is
then noted in parentheses. Attachment C-l 1, Tables C-l 1 through C-125, presents the full set of
site-based modeling results.
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March 26, 2001
Appendix C
Table C.3-20. Summary of Hazard and Risk Exceedances for the Groundwater Pathway
Facility
SI
Summary of HQ Exceedance
Summary of Risk Exceedance
Risk exceedances based on reported concentrations
23
78
182
182
182
182
182
182
1
2
1
2
3
4
6
8
Acetone - 13 (0.02)
Fluoride- 1.2(0.01)
Fluoride -27 (1.5)
Fluoride -59 (12)
Fluoride -6.1 (0.4)
Fluoride -38 (8.1)
Fluoride- 10(3.1)
Fluoride -3.1 (0.3)
None
None
None
None
None
None
None
None
Risk exceedances based on surrogate/DL concentrations
23
23
23
23
175
12
173
45
1
2
3
4
3
2
1
2
Chloroform - 50 (0.09)
Methylene chloride - 8.2 (0.01)
Pyridine- 1.7 (0.003)
Toluene -1.8 (0.004)
Methanol- 1.7 (0.004)
Allyl alcohol - 26 (0.06)
Methanol -1.3 (0.002)
Allyl alcohol - 20 (0.03)
Chloroform - 23 (0.004)
Methylene chloride - 4 (0.0006)
Acetone - 6 (0.0009)
Thallium - 4.5 (0.03)
Fluoride -1.3 (0.1)
Methanol -1.7 (0.03)
None
Chloroform - 1.5E-4 (2.1E-7)
Methylene chloride - 1.8E-4 (2.6E-7))
None
None
Chloroform - 7.0E-5 (9.3E-9)
Methylene chloride - 8.3E-5 (1.1E-8)
N-Nitrosodimethylamine - 2.6E-4 (1.3E-5)
Benzidine a - 1.2E-2 (5.7E-4)
N-Nitrosodi-n-propylamine a - 3.5E-5 (1.7E-6)
Acrylonitrile - 2.5E-5 (1.3E-6)
None
None
Acrylonitrile - 1.4E-5 (3.1E-6)
N-Nitrosodi-n-propylamine - 4.4E-5 (9.6E-6)
N-Nitrosodimethylamine - 3.2E-4 (7.0E-5)
Vinyl Chloride - 1.1E-5 (2.3E-6)
Benzidine- 7. 3E-3 (1.6E-3)
C-lll
(continued)
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March 26, 2001
Appendix C
Table C.3-20. (continued)
Facility
45
45
45
45
45
45
45
78
182
182
SI
4
6
7
8
9
10
11
2
7
9
Summary of HQ Exceedance
None
None
None
None
None
None
None
Fluoride -37 (1.2)
Fluoride -35 (3.7)
Summary of Risk Exceedance
Acrylonitrile - 1.5E-5 (3.2E-6)
N-Nitrosodi-n-propylamine -4.5E-5 (l.OE-5)
N-Nitrosodimethylamine - 3.3E-4 (7.3E-5)
Vinyl Chloride - 1.1E-5 (2.4E-6)
Benzidine- 7.5-3 (1.6E-3)
N-Nitrosodi-n-propylamine - 7.1E-5 (1.2E-5)
Benzidine - 1.6E-3 (2.8E-4)
N-Nitrosodi-n-propylamine - 1.4E-5 (2.3E-6)
N-Nitrosodimethylamine - l.OE-4 (1.7E-5)
Benzidine- 2. 3E-3 (3. 7E-4)
N-Nitrosodi-n-propylamine - 1.5E-5 (2.3E-6)
N-Nitrosodimethylamine - 1.1E-4 (1.7E-5)
Benzidine- 2. 4E-3 (3. 9E-4)
N-Nitrosodimethylamine - 2.7E-5 (3.1E-6)
Benzidine - 6.2E-4 (6.8E-5)
N-Nitrosodimethylamine - 1.9E-5 (1.7E-6)
Benzidine - 4.2E-4 (3.8E-5)
N-Nitrosodimethylamine - 1.6E-5 (1.4E-6)
Benzidine- 3. 7E-4 (3 .2E-5)
Arsenic- 1.6E-5 (8.1E-9)
None
None
3 Industry representatives, subsequent to completion of the survey, have indicated that this constituent is not
expected to be present at the facility. These constituents were reported to EPA in response to the Survey of Surface
Impoundments in November 1999 as less than a specified limit of detection. When this constituent was evaluated in
the risk analysis at the reported detection limit, the concentrations were high enough to predict the indicated
risk/hazard of concern. EPA included the results in this table because of the methodology used throughout the study
to evaluate less than detection limit data.
C-112
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March 26, 2001 Appendix C
C.4 Indirect Exposure Pathway Analysis—Groundwater to Surface Water
By design, surface impoundments are often located near receiving waterbodies. As
described in Section 2.0, impoundments designed for final treatment are intended to produce
effluent that meets regulatory standards (e.g., the National Pollutant Discharge Elimination
System, or NPDES and, therefore, the effluent can discharge directly into the waterbody.
However, many impoundments are designed as part of a treatment train and are not intended to
produce effluent of sufficient quality to meet regulatory standards. Although these
impoundments do not discharge directly to surface water, chemicals may be released through the
bottom of the impoundment, travel through the subsurface, and impact nearby waterbodies. The
intersection of groundwater flow with surface water is often referred to as groundwater discharge
to surface water. This is potentially a significant exposure pathway because 75 percent of RCRA
and Superfund sites are located within a half mile of a surface waterbody, and almost half of all
Superfund sites have impacted surface water (U.S. EPA, 2000a, Proceedings of the Ground-
Water/Surface-Water Interactions Workshop). Of the 133 facilities considered in the Surface
Impoundment Study, approximately 84 percent (112) have one or more fishable waterbodies
located within 1 km of an impoundment.
For chemicals that are moderately mobile, contaminant fate and transport in the
subsurface may result in a contaminant flux to the surface waterbody as the groundwater
discharges into a pond or stream. Depending on the resulting surface water concentrations, the
water quality may be adversely affected. For chemicals that are also bioaccumulative, chemical
concentrations in fish may approach or exceed levels of concern for the segment of the
population that fishes. For convenience, we refer to the release, transport, and accumulation of
chemicals in fish and other aquatic organisms as the groundwater to surface water pathway, or
gw-sw pathway.
C.4.1 Numeric Ranking of Facilities
EPA did a numeric ranking of facilities according to their potential to discharge to surface
waterbodies at significant levels. This ranking was the basis for selecting facilities to model.
The ranking was accomplished as follows.
The area surrounding each of the facilities was evaluated to determine if fishable
waterbodies were present within a 1-km radius of the impoundments. Fishable waterbodies were
defined as streams of reach order 3 and above, as well as bays, estuaries, lakes, canals, harbors,
and wetlands. The name of the closest fishable waterbody was recorded and the distance from it
to the impoundment was measured on the topographic map. Fishable waterbodies within a 1-km
radius were identified for 112 facilities and 353 surface impoundments.
Wastewater (or leachate, when available) concentrations of the constituents present in the
353 surface impoundments were then compared to water quality benchmarks. The benchmark
for this screen was the human health (HH) level associated with the ambient water quality
criteria, or HH-AWQC. Table C.4-1 lists the HH-AWQC levels for the constituents of concern.
C-113
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March 26, 2001 Appendix C
Most are based on aquatic organism and surface water ingestion. For facilities near estuarine or
other unpotable surface waterbodies, the HH-AWQC was based on aquatic organism ingestion
only.
The leachate concentration of at least one constituent exceeded the HH-AWQC in 240
surface impoundments across 79 facilities. The magnitude of the exceedances ranged from
approximately 1 to 1,538,000. Exceedances were documented for 66 chemicals.
Having compared wastewater concentrations to the HH-AWQC, the next step of the
surface water analysis was to compare constituent concentrations estimated to be in groundwater
to the HH-AWQC. The constituent concentration in groundwater was calculated by dividing the
constituent concentration in wastewater by the dilution attenuation factors generated as part of
the groundwater screening analysis. If the surface waterbody was located within 150 meters of
the surface impoundment, the DAF was set equal to 1 for consistency with the IWEM screening
analysis. Hence, for impoundments located within 150 meters of a surface waterbody, the
calculated groundwater concentration equaled the wastewater concentration. For 204 surface
impoundments distributed among 70 facilities, calculated groundwater concentrations exceeded
the AWQC-HH. Sixty-three constituents exceeded the benchmark.
A set of criteria was developed for use in prioritizing the 70 facilities having the greatest
potential to impact surface water quality adversely. The criteria consisted of five easily
quantifiable factors:
• Area of the surface impoundment
• Dilution factor
• Number of constituents that exceeded the water quality criteria
• Magnitude of the exceedance
• Distance to the nearest fishable waterbody.
Each of the criteria was assigned a numeric score, and these were used to rank facilities
for site-based fate and transport modeling. Distance from surface impoundment to the nearest
fishable waterbody, the area of the surface impoundment, and dilution factor are important
determinants in assessing potential impacts to surface water quality and, as a consequence, these
three criteria were each weighted by a factor of 2. The criteria and scoring methodology are
detailed below. The resulting scores are presented in Attachment C-13.
C.4.1.1 Area of Surface Impoundment. The area of the largest surface impoundment
that contained chemicals exceeding the HH-AWQC was determined and ranked in accordance
with Table C.4-2.
C-114
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March 26, 2001
Appendix C
Table C.4-1. Ambient Water Quality Criteria for Human Health (HH-AWQC)
Constituent
Antimony
Arsenic
Copper
Mercury
Nickel
Selenium
Thallium
Zinc
Cyanide
2,3,7,8-TCDD
Acrolein
Acrylonitrile
Benzene
Bromoform
Carbon tetrachloride
Chlorobenzene
Chlorodibromomethane
Chloroform
Dichlorobromomethane
1 ,2-Dichloroethane
1 , 1 -Dichloroethylene
1 ,2-Dichloropropane
1 , 3 -Di chl oropropene
Ethylbenzene
Methyl bromide
CAS No.
7440360
7440382
7440508
7439976
7440020
7782492
7440280
7440666
57125
1746016
107028
107131
71432
75252
56235
108907
124481
67663
75274
107062
75354
78875
542756
100414
74839
HH-AWQC
(ug/L)
1.40E+01
1.80E-023
1.30E+03
5.00E-02
6.10E+02
1.70E+02
1.70E+OOb
9.10E+03
7.00E+02
1.30E-08
3.20E+02
5.90E-02
1.20E+00
4.30E+00
2.50E-01
6.80E+02
4.10E-01
5.70E+00
5.60E-01
3.80E-01
5.70E-02
5.20E-01
l.OOE+01
3.10E+03
4.80E+01
(continued)
C-115
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March 26, 2001
Appendix C
Table C.4-1. (continued)
Constituent
Methyl ene chloride
1 , 1 ,2,2-Tetrachloroethane
Tetrachloroethylene
Toluene
1 ,2-trans-Dichloroethylene
1 , 1 ,2-Trichloroethane
Trichloroethylene
Vinyl chloride
2-Chlorophenol
2,4-Dichlorophenol
2,4-Dimethylphenol
2-Methyl-4,6-dinitrophenol
2,4-Dinitrophenol
Pentachlorophenol
Phenol
2,4,6-Trichlorophenol
Acenaphthene
Anthracene
Benzidine
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Bis2-chloroethyl ether
Bis2-Chloroisopropyl ether
Bis2-ethylhexyl phthalate
CAS No.
75092
79345
127184
108883
156605
79005
79016
75014
95578
120832
105679
534521
51285
87865
108952
88062
83329
120127
92875
56553
50328
205992
207089
111444
39638329
117817
HH-AWQC
(ug/L)
4.70E+00
1.70E-01
8.00E-01
6.80E+03
7.00E+02
6.00E-01
2.70E+00
2.00E+00
1.20E+02
9.30E+01
5.40E+02
1.34E+01
7.00E+01
2.80E-01
2.10E+04
2.10E+00
1.20E+03
9.60E+03
1.20E-04
4.40E-03
4.40E-03
4.40E-03
4.40E-03
3.10E-02
1.40E+03
1.80E+00
(continued)
C-116
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March 26, 2001
Appendix C
Table C.4-1. (continued)
Constituent
Butylbenzl phthalate
2-Chloronaphthalene
Chrysene
Dibenzo(a, h)anthracene
1 ,2-Dichlorobenzene
1,3-Dichlorobenzene
1 ,4-Dichlorobenzene
3,3-Dichlorobenzidine
Diethyl pthalate
Dimethyl phthalate
Di-n-butyl phthalate
2,4-Dinitrotoluene
1 ,2-Diphenylhydrazine
Fluoranthene
Fluorene
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclopentadiene
Hexachloroethane
Ideno 1,2,3-cdpyrene
Isophorone
Nitrobenzene
n-Nitrosodimethylamine
n-Nitrosodi-n-propylamine
n-Nitrosodiphenylamine
Pyrene
CAS No.
85687
91587
218019
53703
95501
541731
106467
91941
84662
131113
84742
121142
122667
206440
86737
118741
87683
77474
67721
193395
78591
98953
62759
621647
86306
129000
HH-AWQC
(ug/L)
3.00E+03
1.70E+03
4.40E-03
4.40E-03
2.70E+03
4.00E+02
4.00E+02
4.00E-02
2.30E+04
3.13E+05
2.70E+03
1.10E-01
4.00E-02
3.00E+02
1.30E+03
7.50E-04
4.40E-01
2.40E+02
1.90E+00
4.40E-03
3.60E+01
1.70E+01
6.90E-04
5.00E-03
5.00E+00
9.60E+02
(continued)
C-117
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March 26, 2001
Appendix C
Table C.4-1. (continued)
Constituent
1 ,2,4-Trichlorobenzene
Aldrin
a-BHC
p-BHC
5-BHC
Chlordane
4,4-DDT
4,4-DDE
4,4-DDD
Dieldrin
a-Endosulfan
p-Endosulfan
Endosulfan sulfate
Endrin
Endrin aldehyde
Heptachlor
Heptachlor epoxide
Toxaphene
PCBs
CAS No.
120821
309002
319846
319857
58899
57749
50293
72559
72548
60571
959988
33213659
1031078
72208
7421934
76448
1024573
8001352
1336363
HH-AWQC
(ug/L)
2.60E+02
1.30E-04
3.90E-03
1.40E-02
1.90E-02
2.10E-03
5.90E-04
5.90E-04
8.30E-04
1.40E-04
1.10E+02
1.10E+02
1.10E+02
7.60E-01
7.60E-01
2.10E-04
l.OOE-04
7.30E-04
1.70E-04
a For one facility near unpotable water, a value
which reflects only aquatic organism ingestion.
b For one facility near unpotable water, a value
which reflects only aquatic organism ingestion.
of 1.4E-7 was used,
of 6.3E-6 was used,
C-118
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March 26, 2001 Appendix C
Table C.4-2. Scoring Criteria for Surface Area
Score
O
2
1
Criteria
Area> 100,000m2
1 0,000 < Area < 100,000m2
0
-------
March 26, 2001
Appendix C
Table C.4-3. Median Annual Flow Rate (mfr) of Flowing Waterbody
(e.g., River, Creek)
Score
3
2
1
Criteria
mfr 5,000 ft3/s
Table C.4-4. Surface Area of Quiescent Waterbody
(e.g., Lake, Pond)
Score
3
2
1
Criteria
Area< 10,000m2
1 0,000 < Area < 150
Area> 150,000
,000 m2
m2
Table C-4-5. Number of Chemical Constituents Potentially Exceeding a
Groundwater / HH-AWQC Ratio of 1
Score
3
2
1
Criteria
Chemicals > 21
2 < Chemicals < 21
Chemicals < 1
C.4.1.4 Magnitude of Exceedance. The magnitude of the exceedance was defined as the
maximum ratio of the calculated groundwater concentration to the HH-AWQC at each
impoundment. If the ratio exceeded 1, it was scored in accordance with Table C.4-6.
C.4.1.5 Distance to Nearest Fishable Waterbody. The distance to the nearest fishable
waterbody was also scored. The method of scoring is reflected in Table C.4-7.
As noted above, the distance from surface impoundment to the nearest fishable
waterbody, the area of the surface impoundment, and the dilution factor were each weighted by a
factor of 2 and the five individual scores were summed. The final scores were ranked in
descending order and every surface impoundment that was characterized by a total score equal to
C-120
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March 26, 2001 Appendix C
Table C.4-6. Maximum Groundwater Concentration / HH-AWQC Ratio
Score
3
2
1
Criteria
Ratio > 100
10 < Ratio < 100
1 < Ratio < 10
Table C.4-7. Distance to Nearest Surface Waterbody
(as Marked on Topographic Map)
Score
3
2
1
Criteria
0< Distance^ 333 m
333 < Distance < 667 m
Distance > 667 m
or exceeding 20 was identified for site-based modeling. If a facility had multiple surface
impoundments and only one surface impoundment was characterized by a score equal to or
exceeding 20, all surface impoundments at the facility were modeled, regardless of their
individual scores. In summary, 15 facilities and 69 surface impoundments were modeled.
C.4.2 Surface Water Screening Modeling
The surface water screening analysis was conducted to quantify the potential for
degradation of surface water quality with respect to human usage. The pathway begins with
infiltration of the constituent into soils beneath the surface impoundment and is completed with
the subsequent transport in aquifers and discharge into the surface waterbodies.
Section C.4.2.1 describes the simplifying assumptions made to perform this analysis;
Section C.4.2.2 states the basis for screening results; and Section C.4.2 presents the screening
procedure, required input parameters, and their values. The results of the groundwater to surface
water pathway screening are presented in Attachment C-14 of this Appendix.
C.4.2.1 Assumptions. To simplify the surface water screening methodology and to
ensure conservative results, it was assumed that:
• The liquid in the surface impoundment leaks through the base of the unit and the
underlying vadose zone to the aquifer
C-121
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March 26, 2001 Appendix C
• Constituent concentrations are assumed to be decreased during subsurface
transport by a factor equal to the groundwater DAF defined in the IWEM Tier 1
tables (see Table C.3-1) corresponding to the constituent and liner scenario.1
• All of the seepage from the aquifer discharges into the river immediately and is
fully and instantaneously mixed with the river water
• The river is initially uncontaminated. The result of this screening calculation is an
estimate of the final concentration of the constituent of concern in the river after
the leachate from the surface impoundment has mixed with the water in the river.
C.4.2.2 Water Quality Screen. The surface water screening methodology compared
constituent concentrations to the ambient water quality criteria for the ingestion of surface water
and aquatic organisms (HH-AWQC). Attachment C-14 tabulates the results of the comparision.
Specifically, constituent concentrations in wastewater, groundwater, and river water were
compared to the HH-AWQC in the preliminary screening, the release assessment, and the risk
modeling, respectively. If the constituent concentration exceeded the HH-AWQC, the
constituent was said to have failed the screen. If the constituent concentration did not exceed the
HH-AWQC, the constituent was said to have passed the screen. A pass/fail result is provided in
Attachment C-14 for each facility-impoundment-constituent combination.
C.4.2.3 Screening Procedure. The first step of the analysis was to determine the
infiltration rate from the surface impoundment. For surface impoundments, infiltration rates
were calculated using EPACMTP. For impoundments where the water table was at or above the
bottom of the impoundment, the infiltration rate was calculated according to the methodology
presented in Bear (1979). Soil parameter values, liner characteristics, and liquid depth of the
impoundment were chosen in a manner consistent with the methodology used for the
groundwater modeling, as described in Section C.3.2.4 (see Table C.4-8).
After the appropriate infiltration rate /was obtained, an areal leakage rate Qt from
beneath the waste management unit was calculated as follows:
QrA I
where
A = area of the waste management unit (m2)
/ = infiltration rate (m/yr).
1 A DAF of 1.0 was assigned if the waterbody was closer to the impoundent than the IWEM default
distance of 150 meters.
C-122
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March 26, 2001
Appendix C
Table C.4-8. Parameters for Infiltration Rate Calculation Used in Screening
Facility
22
38
45
50
61
78
84
Impoundment
ID
1
3
1
2
1
2
3
4
5
6
7
8
9
10
11
1
3
4
5
6
7
1
2
3
4
5
Predominant
Soil Type
Silty clay loam
Silty clay loam0
Silty clay loam
Silty clay loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Silty loam
Silty loam
Unsaturated
Zone
Thickness"
(m)
14.17
14.17C
0.00
4.27
0.00
0.00
0.00
0.00
0.00
1.33
1.34
0.00
0.00
0.00
0.00
63.25
0.61
1.22
0.76
0.00
0.61
0.91
1.37
1.52
0.00
0.00
Water
Table
Elevation11
(m)
-
-
0.00
-
0.61
2.18
5.22
1.26
4.46
-
-
0.25
1.25
2.47
2.77
-
-
-
-
0.61
-
4.57
3.048
-
1.83
Ponding Depth
of Surface
Impoundment
(m)
4.09
4.42
3.64
1.28
2.25
4.42
5.57
2.21
5.03
6.07
4.77
2.60
4.53
4.53
4.53
1.52
1.91
2.22
1.30
2.03
1.07
3.0
3.2
4.9
0.30
2.90
Effective
Thickness
of
Liner
(m)
0.15
0.15
0.92
0.99
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.08
0.08
0.08
0.68
2.28
2.1
2.6
3.1
0.15
0.15
Effective
Hydraulic
Conductivity
of Liner
(m/yr)
4.02E-02
4.01E-02
4.41E-02
5.34E-02
4.07E-02
4.01E-02
4.00E-02
4.07E-02
4.00E-02
3.99E-02
4.01E-02
4.05E-02
4.01E-02
4.01E-02
4.01E-02
4.13E-02
4.03E-02
4.01E-02
4.05E-02
4.56E-02
2.89E-03
5.21E-02
5.41E-02
5.08E-02
4.21E-02
4.17E-02
(continued)
C-123
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March 26, 2001
Appendix C
Table C-4-8. (continued)
Facility
103
105
127
151
156
159
Impoundment
ID
1
2
3
4
5
6
1
1
2
5
1
2
3
4
6
8
18
6
7
8
9
1
2
3
4
5
Predominant
Soil Type
Silty loam
Silty loam
Sandy clay loam
Silty loam
Silty loam
Silty loam
Silty clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam8
Unsaturated
Zone
Thickness"
(m)
2.00d
1.22
2.74
2.00d
2.00d
NAe
1.52
0.00
0.00
0.00
0.00
0.00
0.00
1.52
2.44
2.90
2.90
0.00
0.00
0.00
0.00
0.30
0.00
0.00
2.65
0.31
Water
Table Elevation1"
(m)
-
-
-
-
-
-
-
0.00
0.00
0.00
0.19
NAf
NAf
-
-
-
-
1.49
1.37
1.68
1.66
-
0.914
0.914
-
-
Ponding Depth
of Surface
Impoundment
(m)
5.49
2.90
1.21
2.90
2.90
NAe
1.96
0.28
2.78
2.58
4.41
2.15
2.64
2.59
2.59
9.55
9.55
2.29
1.84
2.29
4.88
0.76
0.51
6.33
0.74
0.16
Effective
Thickness
of
Liner
(m)
0.15
0.15
0.15
0.15
0.15
NAe
0.15
0.15
0.66
0.15
0.15
1.53
0.15
0.15
0.15
1.91
1.91
0.15
0.15
0.15
1.22
0.46
0.26
0.40
0.09
0.15
Effective
Hydraulic
Conductivity
of Liner
(m/yr)
4.00E-02
4.04E-02
4.18E-02
4.04E-02
4.04E-02
NAe
4.09E-02
4.92E-02
4.38E-02
4.06E-02
4.01E-02
5.23E-02
4.05E-02
4.05E-02
4.05E-02
4.31E-02
4.31E-02
4.07E-02
4.10E-02
4.07E-02
4.41E-02
5.04E-02
4.88E-02
4.06E-02
4.17E-02
5.63E-02
(continued)
C-124
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March 26, 2001
Appendix C
Table C-4-8. (continued)
Facility
173
182
184
Impoundment
ID
4
5
6
7
8
1
2
3
4
5
6
7
8
9
10
2
Predominant
Soil Type
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Silty clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Sandy clay loam
Unsatu rated
Zone
Thickness3
(m)
3.66
3.66
3.66
7.65
5.97
6.10
6.10
6.10
6.10
6.10
6.10
6.10
6.10
6.10
6.10
0.00
Water
Table Elevationb
(m)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.00
Ponding Depth
of Surface
Impoundment
(m)
4.53
3.41
2.14
0.60
0.93
1.14
0.76
0.76
0.76
0.76
0.76
0.76
0.76
0.76
0.76
4.57
Effective
Thickness
of
Liner
(m)
0.45
0.45
0.45
0.45
0.76
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
4.57
Effective
Hydraulic
Conductivity
of Liner
(m/yr)
3.39E-02
3.40E-02
3.41E-02
3.48E-02
3.32E-02
4.19E-02
4.31E-02
4.31E-02
4.31E-02
4.31E-02
4.31E-02
4.31E-02
4.31E-02
4.31E-02
4.31E-02
5.74E-02
a Value used in EPACMTP to calculate infiltration rate when bottom of impoundment is above the water table.
b Used to calculate the infiltration rate when the bottom of impoundment is at or below the water table; measured from bottom
of impoundment.
c Data not available, used data from impoundment 1.
d Data not available, used the average of impoundments 2 and 3.
e Subsurface data not available; rate assumed to be average the rate of impoundments 1-5.
f Elevation of wastewater in the surface impoundment is below the water table.
g Data not available, assumed same soil type as impoundments 1-4.
The next step was to calculate a river dilution factor (RD) to account for the mixing of the
seepage volume with the river water. RD is defined as
RD=-
O
River
(C.4-2)
where
Qriver = river flow rate (m3/yr).
C-125
-------
March 26, 2001 Appendix C
The river flow rate, Qriven was represented by the lowest 7-day average flow in a 10-year
period (7Q10) when available. If the 7Q10 was not available, the mean flow rate was used.
The leachate migrating through the subsurface was assumed to be diluted by a factor
equal to the groundwater DAF defined in the IWEM Tier 1 Tables (see Table C.3-1)
corresponding to the constituent and liner scenario. Therefore, the concentration in the
groundwater is given as:
C
r = leachate (C 4 3^
*" DAF ( }
where
C^ = concentration in groundwater (mg/L),
C'leachate = leachate concentration (mg/L), and
DAF = dilution attenuation factor.
The chemical concentration in groundwater reaches the river and is assumed to be
instantaneously and fully mixed with clean river water. The resulting final river concentration is
related to the appropriate analytical concentration in the leachate through the following equation:
C
C = —^ (C4-4)
nver RD ( '
where
Criver = final river concentration (mg/L).
The final river concentration was then compared with the HH-AWQC concentration for
the human usage. Specifically, if Criver was less than the appropriate HH-AWQC for a given
constituent, then that constituent passed the surface water screening; however, if Criver equaled or
exceeded the benchmark, then that constituent failed the screening. The modeling inputs for the
surface water screening analysis are presented in Table C.4-9. Table C.4-10 identifies the
exceedances at each of the nine facilities.
C-126
-------
March 26, 2001
Appendix C
Table C.4-9 Input Parameters for Screening Calculations by Facility and Impoundment
Facility
ID
22
38
45
50
68
78
84
103
105
127
151
Impound-
ment ID
1
3
1
2
1
2
3
4
5
6
7
8
9
10
11
1
3
4
5
6
7
1
2
3
4
5
1
2
3
4
5
6
1
1
2
5
1
2
3
4
Surface
Impoundment
Area
K)
7689
148924
174015
129500
1012
169968
6475
202343
202343
24281
23067
48562
8094
8094
8094
129904
708201
283280
424920
36422
26305
26709
30351
62726
2023
469436
6611
79318
481576
19223
19223
180490
109265
279233
12141
4856232
7469
20234
214484
348030
Liner
Scenario
NAa
NAa
No liner
NAa
No liner
No liner
No liner
NAa
NAa
No liner
No liner
No liner
No liner
No liner
No liner
No liner
NAa
NAa
NAa
NAa
Single liner
No liner
No liner
NAa
NAa
NAa
No liner
No liner
No liner
NAa
NAa
NAa
No liner
No liner
No liner
NAa
No liner
No liner
NAa
NAa
Distance to
Surface
Water Body
(m)
65
65
200
50
270
500
360
140
25
820
845
910
895
975
950
280
35
35
35
20
215
315
330
150
65
115
720
565
670
40
40
95
710
905
950
125
395
255
40
115
Infiltration
Ratec
(m/yr)
1.140
1.220
0.219d
0.137
0.486d
0.639d
0.133d
0.299d
0.1 92d
1.740
1.410
0.676d
0.917d
0.591d
0.511d
0.632
1.000
1.220
0.744
0.141d
0.005
0.015d
0.057d
0.004f
0.327d
0.339d
1.590
0.948
0.488
0.956
0.956
0.988s
0.580
0.141d
0.229d
0.738d
1.169d
NAe
NAe
0.827
Leachate Flux
from Surface
Impoundment
(m3/s)
2.780E-04
5.761E-03
9.667E-04
5.626E-04
1.428E-05
3.228E-03
1.916E-05
1.655E-03
9.759E-04
1.340E-03
1.031E-03
9.781E-04
2.250E-04
1.413E-04
1.207E-04
2.603E-03
2.246E-02
1.096E-02
1.002E-02
1.104E-04
4.146E-06
2.685E-05
1.424E-04
7.340E-06
5.518E-06
5.051E-03
3.333E-04
2.384E-03
7.452E-03
5.827E-04
5.827E-04
5.652E-03
2.010E-03
8.136E-04
7.109E-05
1.074E-01
2.673E-04
NAe
NAe
9.127E-03
River Flow
Rate
(nWs)
2.251e-01
2.266E-01
2.286E+02
2.286E+02
3.115E-01
4.248E-01
3.115E-01
4.248E-01
3.115E-01
4.248E-01
4.248E-01
4.248E-01
4.248E-01
4.248E-01
4.248E-01
NAB
1.558E+00
1.558E+00
1.558E+00
1.558E+00
1.558E+00
4.248e-01
4.248E-01
4.248E-01
5.914E+00
5.183E-02
4.248E-01
7.607E+00
7.607E+00
4.248E-01
4.248E-01
1.487E+02
9.884E+00
6.587E+01
2.719E+00
6.587E+01
6.522E+01
6.522E+01
6.522E+01
6.522E+01
River
Flow
Rate
Type
7Q10
7Q10
7Q10
7Q10
7Q10
Mean
7Q10
Mean
7Q10
Mean
Mean
Mean
Mean
Mean
Mean
NAb
Mean
7Q10
7Q10
7Q10
7Q10
Mean
Mean
Mean
7Q10
7Q10
Mean
7Q10
7Q10
Mean
Mean
Mean
7Q10
Mean
Mean
Mean
7Q10
7Q10
7Q10
7Q10
River
Dilution
Factor
8.099e+02
3.933E+01
1.892E+05
4.063E+05
1.997E+04
1.233E+02
1.141E+04
2.214E+02
2.529E+02
3.171E+02
4.119E+02
4.081E+02
1.805E+03
2.801E+03
3.239E+03
l.OOOE+00
6.938E+01
1.422E+02
1.554E+02
9.567E+03
3.736E+05
3.344e+04
7.744E+03
5.339E+04
2.819E+05
1.027E+01
1.274E+03
3.190E+03
1.021E+03
7.290E+02
7.290E+02
2.630E+04
4.918E+03
5.276E+04
3.084E+04
5.796E+02
2.356E+05
NAE
NAE
7.146E+03
(continued)
C-127
-------
March 26, 2001
Appendix C
Table C.4-9 (Continued)
Facility
ID
151
(cont.)
156
159
173
182
184
Impound-
ment ID
6
8
18
6
7
8
9
1
2
3
4
5
4
5
6
7
8
1
2
3
4
5
6
7
8
9
10
2
Surface
Impoundment
Area
(m2)
24281
48562
48562
76890
157828
971
267093
7525
52583
18395
436923
295421
101172
230671
465389
669
3855
101172
215698
61917
531757
57061
135165
236337
28779
81034
7701
230671
Liner
Scenario
No liner
No liner
No liner
NAa
No liner
NAa
No liner
No liner
No liner
No liner
NAa
NAa
No liner
No liner
NAa
No liner
No liner
No liner
No liner
NAa
NAa
NAa
NAa
No liner
NAa
NAa
No liner
NAa
Distance to
Surface
Water Body
(m)
495
985
970
20
215
120
245
460
460
370
60
30
795
270
105
810
575
700
200
20
20
40
0
300
0
0
700
65
Infiltration
Ratec
(m/yr)
0.829
0.269
0.269
0.257d
0.169d
0.207d
0.160d
0.150
0.012d
0.006d
0.407
0.167
0.376
0.295
0.206
0.107
0.092
0.469
0.380
0.380
0.380
0.380
0.380
0.380
0.380
0.380
0.380
0.115d
Leachate Flux
from Surface
Impoundment
(m3/s)
6.383E-04
4.142E-04
4.142E-04
5.265E-04
6.399E-04
5.122E-06
9.850E-04
3.579E-05
3.652E-05
3.476E-06
5.639E-03
1.564E-03
1.206E-03
2.158E-03
3.040E-03
2.270E-06
1.119E-05
1.505E-03
2.599E-03
7.461E-04
6.408E-03
6.876E-04
1.629E-03
2.848E-03
3.468E-04
9.764E-04
9.279E-05
1.612E-03
River Flow
Rate
(nrYs)
6.522e+01
6.522E+01
6.522E+01
2.832E+01
2.832E+01
2.832E+01
2.832E+01
9.048E-01
9.048E-01
9.048E-01
9.048E-01
9.629E+00
2.048E+02
2.048E+02
2.048E+02
2.048E+02
2.048E+02
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
River
Flow
Rate
Type
7Q10
7Q10
7Q10
Mean
Mean
Mean
Mean
Mean
Mean
Mean
Mean
Mean
7Q10
7Q10
7Q10
7Q10
7Q10
NAb
NAb
NAb
NAb
NAb
NAb
NAb
NAb
NAb
NAb
7Q10
River
Dilution
Factor
1.022e+05
1.574E+05
1.574E+05
4.520E+04
3.348E+04
4.443E+06
2.090E+04
2.528E+04
4.522E+04
2.585E+05
1.605E+02
6.155E+03
1.698E+05
9.491E+04
6.737E+04
9.023E+07
1.821E+07
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
O.OOOE+00
Liner scenario is not required since the impoundment is less than or equal to 150 meters; DAF assumed to be 1.0.
The waterbody is a pond, therefore the River Flow Rate is essentially zero and the River Dilution Factor is assumed to be 1.
Infiltration rates for this analysis were calculated using the semi-analytical solution in EPACMTP and impoundment-specific data
unless otherwise noted.
The base of the impoundment is at or below the water table, so the infiltration rate was calculated using the method described in
Bear (1979).
Infiltration rate, Leachate flux, and River Dilution Factor are not applicable because the elevation of the wastewater in the surface
impoundment is at or below the water table.
The infiltration rate was generated using the formula for composite liner leakage rate of Bonaparte et al. (1989).
The infiltration rate was generated by averaging the infiltration from impoundments 1,2,3,4 and 5 because of the lack of
subsurface data.
C-128
-------
March 26, 2001
Appendix C
Table C.4-10. Summary of Water Quality Exceedances for Groundwater
to Surface Water Pathway
Facility
SI
Constituent of Concern
C a
^ leach
(mg/L)
C b
^ GW
(mg/L)
C c
^ river
(mg/L)
HH-AWQC "
(mg/L)
Criver/HH-
AWQCe
Risk Exceedances Based on Reported Chemical Concentrations
50
68
182
182
182
182
182
182
182
1
o
J
1
2
3
4
5
8
6
Thallium
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
2.40e+00
1.20E-02
2.67E-01
2.53E-01
4.94E-02
1.55E-01
1.95E-01
3.70E-03
1.72E-02
3.29E-03
1.20E-02
8.09E-03
7.68E-03
4.94E-02
1.55E-01
1.95E-01
3.70E-03
1.72E-02
3.29E-03
1.73E-04
8.09E-03
7.68E-03
4.94E-02
1.55E-01
1.95E-01
3.70E-03
1.72E-02
1.70E-03
1.80E-05
1.80E-05
1.80E-05
1.80E-05
1.80E-05
1.80E-05
1.80E-05
1.80E-05
1.93E+00
9.61E+00
4.49E+02
4.26E+02
2.74E+03
8.63E+03
1.08E+04
2.06E+02
9.56E+02
Risk Exceedances Based on Surrogate/DL Chemical Concentrations
22
22
22
22
22
22
22
22
22
22
22
22
45
45
45
45
45
45
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
Benzidine
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)iluoranthene
Chrysene
Dibenzo(a,h)anthracene
Hexachlorobenzene
Ideno 1,2,3-cdPyrene
N-Nitrosodimethylamine
N-Nitrosodi-n-propylamine
PCBs
Toxaphene
1 ,2-Diphenylhydrazine
3,3 Dichlorobenzidine
Acrylonitrile
Benzidine
Bis2-chloroethyl ether
Hexachlorobenzene
3.50e+00
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
l.OOE-02
1.75E-03
l.OOE-03
l.OOE-02
2.00E-02
4.33E-02
5.00E-02
l.OOE-02
l.OOe+00
3.50E-02
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
l.OOE-02
1.75E-03
l.OOE-03
5.56E-03
9.52E-03
2.41E-02
2.78E-02
4.35E-03
1.69E-04
4.32E-05
1.23E-05
1.23E-05
1.23E-05
6.17E-06
1.23E-05
1.23E-05
1.23E-05
6.17E-06
1.23E-05
2.16E-06
1.23E-06
4.50E-05
7.72E-05
1.95E-04
2.25E-04
3.53E-05
1.37E-06
1.20E-07
4.40E-06
4.40E-06
4.40E-06
4.40E-06
4.40E-06
7.50E-07
4.40E-06
6.90E-07
5.00E-06
1.70E-07
7.30E-07
4.00E-05
4.00E-05
5.90E-05
1.20E-07
3.10E-05
7.50E-07
3.60E+02
2.81E+00
2.81E+00
2.81E+00
1.40E+00
2.81E+00
1.65E+01
2.81E+00
8.95E+00
2.47E+00
1.27E+01
1.69E+00
1.13E+00
1.93E+00
3.31E+00
1.88E+03
1.14E+00
1.83E+00
(continued)
C-129
-------
March 26, 2001
Appendix C
Table C.4-10. (continued)
Facility
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
SI
2
2
2
2
o
J
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Constituent of Concern
n-Nitrosodimethylamine
n-Nitrosodi-n-propylamine
PCBs
Toxaphene
Benzidine
1 ,2-Diphenylhydrazine
3,3 Dichlorobenzidine
4,4-DDD
4,4-DDE
4,4-DDT
Acrylonitrile
Aldrin
Arsenic
Benzidine
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Bis2-chloroethyl ether
Chlordane
Chrysene
Dibenzo(a,h)anthracene
Dieldrin
Heptachlor
Heptachlor Epoxide
Hexachlorobenzene
Ideno 1,2,3-cdPyrene
n-Nitrosodimethylamine
n-Nitrosodi-n-propylamine
PCBs
Toxaphene
C a
*^ leach
(mg/L)
l.OOE-02
l.OOE-02
1.65E-02
8.80E-03
5.00E-02
l.OOE-02
2.00E-02
3.67E-04
3.67E-04
3.67E-04
4.33E-02
1.83E-04
l.OOE-02
5.00E-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
7.33E-04
l.OOE-02
l.OOE-02
7.33E-05
1.83E-04
2.93E-03
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
1.65E-02
8.80E-03
C b
*^ GW
(mg/L)
5.56E-03
5.56E-03
4.46E-05
7.33E-04
2.78E-02
l.OOE-02
2.00E-02
3.67E-04
3.67E-04
3.67E-04
4.33E-02
1.83E-04
l.OOE-02
5.00E-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
7.33E-04
l.OOE-02
l.OOE-02
7.33E-05
1.83E-04
2.93E-03
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
1.65E-02
8.80E-03
C c
^ river
(mg/L)
4.50E-05
4.50E-05
3.62E-07
5.95E-06
2.44E-06
4.51E-05
9.02E-05
1.65E-06
1.65E-06
1.65E-06
1.96E-04
8.27E-07
4.51E-05
2.26E-04
4.51E-05
4.51E-05
4.51E-05
4.51E-05
3.31E-06
4.51E-05
4.51E-05
3.31E-07
8.27E-07
1.32E-05
4.51E-05
4.51E-05
4.51E-05
4.51E-05
7.45E-05
3.97E-05
HH-AWQC "
(mg/L)
6.90E-07
5.00E-06
1.70E-07
7.30E-07
1.20E-07
4.00E-05
4.00E-05
8.30E-07
5.90E-07
5.90E-07
5.90E-05
1.30E-07
1.80E-05
1.20E-07
4.40E-06
4.40E-06
4.40E-06
3.10E-05
2.10E-06
4.40E-06
4.40E-06
1.40E-07
2.10E-07
l.OOE-07
7.50E-07
4.40E-06
6.90E-07
5.00E-06
1.70E-07
7.30E-07
Crive/HH-
AWQCe
6.53E+01
9.01E+00
2.13E+00
8.15E+00
2.03E+01
1.13E+00
2.26E+00
1.99E+00
2.80E+00
2.80E+00
3.31E+00
6.36E+00
2.51E+00
1.88E+03
1.03E+01
1.03E+01
1.03E+01
1.46E+00
1.58E+00
1.03E+01
1.03E+01
2.36E+00
3.94E+00
1.32E+02
6.02E+01
1.03E+01
6.54E+01
9.02E+00
4.38E+02
5.44E+01
(continued)
C-130
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March 26, 2001
Appendix C
Table C.4-10. (continued)
Facility
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
SI
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
6
6
6
6
6
7
Constituent of Concern
3,3 Dichlorobenzidine
4,4-DDD
4,4-DDE
4,4-DDT
Acrylonitrile
Aldrin
Arsenic
Benzidine
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Bis2-chloroethyl ether
Chlordane
Chrysene
Dibenzo(a,h)anthracene
Dieldrin
Heptachlor
Heptachlor Epoxide
Hexachlorobenzene
Ideno 1,2,3-cdPyrene
n-Nitrosodimethylamine
n-Nitrosodi-n-propylamine
PCBs
Toxaphene
Acrylonitrile
Benzidine
n-Nitrosodimethylamine
n-Nitrosodi-n-propylamine
Toxaphene
Benzidine
C a
*^ leach
(mg/L)
2.00e+00
3.67E-04
3.67E-04
3.67E-04
4.33E-02
1.83E-04
l.OOE-02
5.00E-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
7.33E-04
l.OOE-02
l.OOE-02
7.33E-05
1.83E-04
2.93E-03
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
1.65E-02
8.80E-03
4.33E-02
5.00E-02
l.OOE-02
l.OOE-02
8.80E-03
5.00E-02
C b
*^ GW
(mg/L)
2.00E-02
3.67E-04
3.67E-04
3.67E-04
4.33E-02
1.83E-04
l.OOE-02
5.00E-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
7.33E-04
l.OOE-02
l.OOE-02
7.33E-05
1.83E-04
2.93E-03
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
1.65E-02
8.80E-03
2.41E-02
2.78E-02
5.56E-03
5.56E-03
7.33E-04
2.78E-02
C c
^ river
(mg/L)
7.92E-05
1.45E-06
1.45E-06
1.45E-06
1.72E-04
7.26E-07
3.96E-05
1.98E-04
3.96E-05
3.96E-05
3.96E-05
3.96E-05
2.90E-06
3.96E-05
3.96E-05
2.90E-07
7.26E-07
1.16E-05
3.96E-05
3.96E-05
3.96E-05
3.96E-05
6.53E-05
3.48E-05
7.59E-05
8.76E-05
1.75E-05
1.75E-05
2.31E-06
6.74E-05
HH-AWQC "
(mg/L)
4.00E-05
8.30E-07
5.90E-07
5.90E-07
5.90E-05
1.30E-07
1.80E-05
1.20E-07
4.40E-06
4.40E-06
4.40E-06
3.10E-05
2.10E-06
4.40E-06
4.40E-06
1.40E-07
2.10E-07
l.OOE-07
7.50E-07
4.40E-06
6.90E-07
5.00E-06
1.70E-07
7.30E-07
5.90E-05
1.20E-07
6.90E-07
5.00E-06
7.30E-07
1.20E-07
Crive/HH-
AWQCe
1.98E+00
1.75E+00
2.46E+00
2.46E+00
2.91E+00
5.58E+00
2.20E+00
1.65E+03
9.00E+00
9.00E+00
9.00E+00
1.28E+00
1.38E+00
9.00E+00
9.00E+00
2.07E+00
3.46E+00
1.16E+02
5.28E+01
9.00E+00
5.74E+01
7.92E+00
3.84E+02
4.77E+01
1.29E+00
7.30E+02
2.54E+01
3.50E+00
3.17E+00
5.62E+02
(continued)
C-131
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March 26, 2001
Appendix C
Table C.4-10. (continued)
Facility
45
45
45
45
45
45
45
45
45
45
45
45
45
50
68
68
68
68
68
68
78
84
84
84
84
84
84
84
84
84
SI
7
7
7
8
8
8
8
9
9
10
10
11
11
1
o
J
3
3
3
3
o
J
2
5
5
5
5
5
5
5
5
5
Constituent of Concern
n-Nitrosodimethylamine
n-Nitrosodi-n-propylamine
Toxaphene
Benzidine
n-Nitrosodimethylamine
n-Nitrosodi-n-propylamine
Toxaphene
Benzidine
n-Nitrosodimethylamine
Benzidine
n-Nitrosodimethylamine
Benzidine
n-Nitrosodimethylamine
Arsenic
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)iluoranthene
Chrysene
Dibenzo(a,h)anthracene
Ideno 1,2,3-cdPyrene
Arsenic
1 , 1 ,2,2-Tetrachloroethane
1 , 1 -Dichloroethylene
1 ,2-Dichloroethane
1 ,2-Diphenylhydrazine
2,4-Dinitrotoluene
3,3 -Dichlorobenzidine
4,4-DDD
4,4-DDE
4,4-DDT
C a
*^ leach
(mg/L)
l.OOE-02
l.OOe+00
8.80E-03
5.00E-02
l.OOE-02
l.OOE-02
8.80E-03
5.00E-02
l.OOE-02
5.00E-02
l.OOE-02
5.00E-02
l.OOE-02
5.00E-01
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE+01
5.00E-03
5.00E-03
5.00E-03
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-05
l.OOE-05
l.OOE-05
C b
*^ GW
(mg/L)
5.56E-03
5.56E-03
7.33E-04
2.78E-02
5.56E-03
5.56E-03
7.33E-04
2.78E-02
5.56E-03
2.78E-02
5.56E-03
2.78E-02
5.56E-03
1.52E-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
3.03E-01
5.00E-03
5.00E-03
5.00E-03
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-05
l.OOE-05
l.OOE-05
C c
^ river
(mg/L)
1.35E-05
1.35E-05
1.78E-06
6.81E-05
1.36E-05
1.36E-05
1.80E-06
1.54E-05
3.08E-06
9.91E-06
1.98E-06
8.57E-06
1.71E-06
1.52E-02
1.44E-04
1.44E-04
1.44E-04
1.44E-04
1.44E-04
1.44E-04
3.93E-05
4.87E-04
4.87E-04
4.87E-04
9.73E-04
9.73E-04
9.73E-04
9.73E-07
9.73E-07
9.73E-07
HH-AWQC "
(mg/L)
6.90E-07
5.00E-06
7.30E-07
1.20E-07
6.90E-07
5.00E-06
7.30E-07
1.20E-07
6.90E-07
1.20E-07
6.90E-07
1.20E-07
6.90E-07
1.80E-05
4.40E-06
4.40E-06
4.40E-06
4.40E-06
4.40E-06
4.40E-06
1.80E-05
1.70E-04
5.70E-05
3.80E-04
4.00E-05
1.10E-04
4.00E-05
8.30E-07
5.90E-07
5.90E-07
Crive/HH-
AWQCe
1.96E+01
2.70E+00
2.44E+00
5.67E+02
1.97E+01
2.72E+00
2.46E+00
1.28E+02
4.46E+00
8.26E+01
2.87E+00
7.14E+01
2.48E+00
8.42E+02
3.28E+01
3.28E+01
3.28E+01
3.28E+01
3.28E+01
3.28E+01
2.18E+00
2.86E+00
8.54E+00
1.28E+00
2.43E+01
8.85E+00
2.43E+01
1.17E+00
1.65E+00
1.65E+00
(continued)
C-132
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March 26, 2001
Appendix C
Table C.4-10. (continued)
Facility
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
84
159
159
159
182
182
182
184
SI
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
4
4
4
7
9
10
2
Constituent of Concern
Acrylonitrile
Aldrin
Arsenic
Benzidine
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Bis(2-chloroethyl) ether
Carbon Tetrachloride
Chlordane
Chlorodibromomethane
Chrysene
Dibenzo(a,h)anthracene
Dieldrin
Heptachlor
Heptachlor Epoxide
Hexachlorobenzene
Hexachlorobutadiene
Ideno 1,2,3-cdPyrene
N-Nitrosodimethylamine
N-Nitrosodi-n-propylamine
Pentachlorophenol
Toxaphene
Antimony
Arsenic
Thallium
Arsenic
Arsenic
Arsenic
Benzidine
C a
*^ leach
(mg/L)
l.OOE-02
5.00E-05
3.00e+00
l.OOE-02
5.00E-05
5.00E-05
5.00E-05
l.OOE-02
5.00E-03
5.00E-05
5.00E-03
5.00E-05
5.00E-05
2.00E-04
5.00E-05
5.00E-05
5.00E-05
l.OOE-02
5.00E-05
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
6.00E-02
3.00E-01
2.00E+00
2.67E-01
2.53E-01
2.67E-01
5.00E-02
C b
*^ GW
(mg/L)
l.OOE-02
5.00E-05
3.00E-03
l.OOE-02
5.00E-05
5.00E-05
5.00E-05
l.OOE-02
5.00E-03
5.00E-05
5.00E-03
5.00E-05
5.00E-05
2.00E-04
5.00E-05
5.00E-05
5.00E-05
l.OOE-02
5.00E-05
l.OOE-02
l.OOE-02
l.OOE-02
5.00E-03
6.00E-02
3.00E-01
2.00E+00
8.09E-03
2.53E-01
8.09E-03
5.00E-02
C c
^ river
(mg/L)
9.73E-04
4.87E-06
2.92E-04
9.73E-04
4.87E-06
4.87E-06
4.87E-06
9.73E-04
4.87E-04
4.87E-06
4.87E-04
4.87E-06
4.87E-06
1.95E-05
4.87E-06
4.87E-06
4.87E-06
9.73E-04
4.87E-06
9.73E-04
9.73E-04
9.73E-04
4.87E-04
3.74E-04
1.87E-03
1.25E-02
8.09E-03
2.53E-01
8.09E-03
3.82E-05
HH-AWQC "
(mg/L)
5.90E-05
1.30E-07
1.80E-05
1.20E-07
4.40E-06
4.40E-06
4.40E-06
3.10E-05
2.50E-04
2.10E-06
4.10E-04
4.40E-06
4.40E-06
1.40E-07
2.10E-07
l.OOE-07
7.50E-07
4.40E-04
4.40E-06
6.90E-07
5.00E-06
2.80E-04
7.30E-07
1.40E-04
1.40E-04F
6.30E-03 F
1.80E-05
1.80E-05
1.80E-05
1.20E-07
Crive/HH-
AWQCe
1.65E+01
3.74E+01
1.62E+01
8.11E+03
1.11E+00
1.11E+00
1.11E+00
3.14E+01
1.95E+00
2.32E+00
1.19E+00
1.11E+00
1.11E+00
1.39E+02
2.32E+01
4.87E+01
6.49E+00
2.21E+00
1.11E+00
1.41E+03
1.95E+02
3.48E+00
6.67E+02
2.67E+00
1.34E+01
1.98E+00
4.49E+02
1.41E+04
4.49E+02
3.19E+02
(continued)
C-133
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March 26, 2001
Appendix C
Table C.4-10. (continued)
Facility
184
184
184
184
184
184
184
184
184
184
184
SI
2
2
2
2
2
2
2
2
2
2
2
Constituent of Concern
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Chrysene
Dibenzo(a,h)anthracene
Hexachlorobenzene
Ideno 1,2,3-cdPyrene
n-Nitrosodimethylamine
n-Nitrosodi-n-propylamine
PCBs
Toxaphene
C a
*^ leach
(mg/L)
l.OOE-02
l.OOE-02
l.OOe+00
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
3.50E-02
2.00E-03
C b
*^ GW
(mg/L)
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
l.OOE-02
3.50E-02
2.00E-03
C c
^ river
(mg/L)
7.65E-06
7.65E-06
7.65E-06
7.65E-06
7.65E-06
7.65E-06
7.65E-06
7.65E-06
7.65E-06
2.68E-05
1.53E-06
HH-AWQC "
(mg/L)
4.40E-06
4.40E-06
4.40E-06
4.40E-06
4.40E-06
7.50E-07
4.40E-06
6.90E-07
5.00E-06
1.70E-07
7.30E-07
Crive/HH-
AWQCe
1.74E+00
1.74E+00
1.74E+00
1.74E+00
1.74E+00
1.02E+01
1.74E+00
1.11E+01
1.53E+00
1.57E+02
2.10E+00
a C leach The estimated concentration in the leachate as it leaves the unit boundary.
b C GW The estimated concentration in the groundwater as it enters the surface water; if this value exceeds a HH-
AWQC then the facility is considered to have the potential for an environmental release.
0 C nver The estimated concentration in the surface water after complete mixing.
d HH-AWQC Ambient Water Quality Criteria for human health.
e Cnvei/HH-AWQC The ratio of the surface water concentration to the ambient water quality criteria for human health;
if this ratio exceeds one then the facility is considered to have a potential risk exceedance.
f The HH-AWQC selected is based on aquatic organism ingestion only because the impoundment is located next to
an estuarine waterbody.
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Appendix C
C.5 Indirect Exposure Pathway Analysis: Methodology and Results
C.5.1 Overview
The indirect exposure pathway (IEP) screening analysis was designed to evaluate the
potential for indirect exposure pathway risk as a result of potential chemical release from surface
impoundments. Only those facilities with impoundments that currently handle bioaccumulative
constituents (i.e., SVOCs, dioxin-like compounds, mercury, and several additional metals), were
included in this analysis.
Key Attributes of Indirect Exposure Pathway
Screening Analysis
• Evaluated potential for indirect exposure
pathway risk to offsite populations
including residents, farmers, and fishers.
• Assigned facilities to one of three
categories regarding potential for indirect
exposure pathway risk: potential concern,
lower concern, or least concern.
• Used numerical ranking algorithms
combined with facility-specific and
environmental setting criteria to assign
rankings.
• Considered both current status and future
closure scenarios. Future status scenario
results were used only to qualify overall
rankings, which were based on current
status scenario results.
The IEP screening analysis used a
combination of facility-specific and
environmental setting criteria to assign each
facility to one of three categories regarding the
potential for indirect exposure pathway risk:
• Potential concern: The potential exists
for indirect exposure pathway risk.
• Lower concern: There is a lower
potential for indirect exposure pathway
risk.
• Least concern: The analysis suggests that
these facilities have the least potential
for indirect exposure pathway risk.
In order for a facility to be placed in the
category with the highest level of concern (i.e.,
the potential concern category), the IEP
screening analysis had to suggest that the potential exists for indirect exposure pathway risk
under current site conditions. Consequently, overall rankings for the facilities were assigned
based on a current status scenario, which was designed to represent current conditions at the
facilities. A future closure scenario was also included in the analysis to provide perspective on
the number of facilities that could pose an indirect exposure pathway risk after impoundment
closure. This future closure scenario analysis was based on precautionary assumptions regarding
postclosure actions; consequently, the results of the analysis were used only to qualify the results
of the current status scenario (i.e., future closure results were not used in assigning overall
rankings to the facilities).
Although a number of the facility-specific and environmental setting criteria used in the
numerical ranking of facilities were assessed at the impoundment level, the IEP screening
analysis was implemented primarily at the facility level with overall rankings regarding indirect
exposure pathway risk being assigned to facilities and not impoundments. In addition, although
the types of chemical classes handled at facilities were considered part of the analysis (e.g., in
determining which release scenarios were applicable), the analysis was not conducted at the level
of individual chemicals and did not use chemical-specific concentration data. This level of
analytical resolution was considered appropriate for the IEP screening analysis, which was
C-135
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March 26, 2001 Appendix C
intended as a first-pass assessment of the potential for indirect exposure pathway risk at these
facilities and not as a site-specific quantitative assessment of risk.
The IEP analysis considered a set of exposure pathways, each linked to a specific release
scenario and receptor population. For example, the analysis considered volatilization of
chemicals from impoundments with subsequent transport to offsite residential home gardens (this
represented a specific exposure pathway that was evaluated for the resident receptor population).
Each of these exposure pathways was evaluated using a specific set of facility-specific and
environmental setting criteria, which in turn were used in a ranking algorithm to generate the
overall ranking for that exposure pathway regarding the potential for indirect exposure pathway
risk. Once all exposure pathways were evaluated for a given facility, those rankings were
reviewed and an overall ranking was given to that facility for the IEP screening analysis. As
noted above, these overall rankings were based only on the current status scenario.
The procedure used to complete the IEP screening analysis is presented below and
illustrated in Figure C.5-1 (more detailed discussion of individual elements of the analytical
framework is presented in the next section):
• Step 1: Obtained facility-specific and environmental setting information used to establish
criteria for the IEP screening analysis. Reviewed SI survey data to obtain key facility-
specific performance information (e.g., current impoundment status, postclosure actions
taken for closed impoundments, impoundment size). Used U.S. Census data, aerial
photos, topographic maps and other resources to characterize key environmental setting
attributes (e.g., distance to receptor, potential for erosion/runoff, potential level of
dilution for downgradient waterbodies)
• Step 2: Converted information obtained in Step 1 into individual criteria scores used in
the ranking algorithms for different exposure pathways: Converted facility-specific and
environmental setting information into specific criteria scores ranging from 1 to 3 (with
1 having a lower impact on potential exposure and risk, 2 having a moderate impact, and
3 having a higher impact). The parameter ranges that were used in defining the three
categories for each criterion reflected the underlying characteristics of that parameter.
• Step 3: Used exposure-pathway-specific ranking algorithms together with criteria from
Step 2 to generate numerical rankings for each exposure pathway: Separate ranking
algorithms were developed for each exposure pathway reflecting the specific mix of
criteria that should be considered in evaluating the potential for indirect exposure
pathway risk for that pathway. These ranking algorithms were combined with applicable
criteria to generate numerical rankings for each exposure pathway. Note that the
numerical rankings were generated for both the current status scenario exposure pathways
and the future closure scenario exposure pathways. This produced two sets of overall
pathway-specific rankings for a given facility-one set for the current status scenario and
C-136
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March 26, 2001
Appendix C
Stepl: Obtain facility -
specific and environmental
setting information used to
establish criteria for the IEP
screening analysis.
Step 2: Convert information
obtained in Step 1 into actual
criteria scores used in the
ranking algorithms for
different exposure pathways.
Step 3: Use exposure pathway-
specific ranking algorithms
together with criteria from Step
2 to generate numerical
rankings for each exposure
pathway. Convert these
numerical rankings into
qualitative rankings of high,
medium, or low.
Step 4: Review qualitative
rankings for current status
exposure pathways and assign
an OVERALL ranking to each
facility (i.e., potential
concern, lower concern, least
concern).
Step 5: Review qualitative
rankings for future closure
exposure pathways in order to
identify high ranking exposure
pathways that can be used in
qualifying the OVERALL
ranking results of the analysis
developed in Step 4.
Figure C.5-1. Procedure used to assign overall rankings to facilities in indirect
exposure pathway screening analysis.
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March 26, 2001 Appendix C
one set for the future closure scenario. Ultimately, these exposure pathway-specific
numerical rankings were converted into qualitative rankings of high, medium, or low for
each exposure pathway, which were then used in assigning overall rankings to facilities.
• Step 4: Reviewed qualitative rankings for current status exposure pathways and assigned
an overall ranking to each facility: Overall rankings for this analysis were assigned based
on a review of the individual rankings assigned to each current status scenario exposure
pathway. Specifically, to add confidence to conclusions that a facility has the potential
for indirect exposure pathway risk (i.e., that that facility should be assigned a potential
concern ranking), it was decided that a facility had to meet one of two criteria: (1) have at
least two current scenario exposure pathways with a "high" ranking, or (2) have one
current scenario pathway with a "high" rank and failure of the direct exposure pathway
screen for air for at least one bioaccumulative constituent.
• Step 5: Reviewed qualitative rankings for future closure exposure pathways in order to
identify high-ranking exposure pathways that could be used in qualifying the overall
ranking results of the analysis: The results of pathway-specific rankings for the future
closure scenario were reviewed for each facility to determine if any pathways have high
rankings. This information was then used to qualify or augment overall rankings for
those sites.
C.5.2 Technical Approach
This section provides an expanded discussion of the technical approach used in the IEP
screening analysis, including a detailed explanation of how the semi quantitative ranking
procedure was applied to each of the exposure pathways that were considered in the analysis.
C.5.2.7. Release Scenarios. To evaluate both the current status scenario and the future
closure scenario, several different release scenarios were considered, including volatilization,
particulate entrainment, erosion/runoff, and leaching to groundwater (with subsequent transport
and release to surface water). Each of the release scenarios is associated with a specific set of
indirect exposure pathways that can result when constituents are transported from the
impoundments to different offsite receptor locations (i.e., residential areas with home gardens,
farming areas with crop or grazing fields, or fishable waterbodies). Each of the release scenarios
considered in the screening analysis is summarized below.
• Volatilization: Addressed release of volatile or semivolatile constituents from
surface impoundments and subsequent transport to offsite receptors. This release
scenario was considered only for constituents that have the potential to volatilize
(i.e., SVOCs, dioxin-like compounds, and mercury-bioaccumulative metals other
than mercury are not considered). Because the future closure scenario assumed
that there was no residual wastewater in the impoundments after closure,
volatilization was evaluated only for the current status scenario and was not
considered for the future closure scenario.
C-138
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March 26, 2001 Appendix C
• Particulate entrainment. Addressed the wind erosion and entrainment of
particulates with subsequent dispersion and transport to offsite receptors. This
release scenario was considered for all classes of constituents considered in the
IEP screening analysis, since all have the potential to either exist in paniculate
form or be adsorbed to sludge particles. Particulate entrainment was considered
only for those impoundments that are closed with the potential for exposed sludge
which includes (1) facilities with currently closed impoundments that have been
drained without being dredged or capped (this is a relatively small number) and
(2) all facilities under the future closure scenario that assumed impoundments
close without action being taken to reduce constituent mobility.
• Erosion/runoff: Addressed the potential for rainfall to create erosion and/or
runoff from impoundments that impacts downgradient receptors including
residential areas, farms, and waterbodies. This release scenario was considered
for all classes of constituents, since it includes constituents that are either
dissolved in rainwater (and carried offsite as runoff) or adsorbed to sludge
particulates (and carried offsite as eroded material). The erosion/runoff release
scenario was restricted to those facilities with impoundments that have closed
without dredging or capping. These conditions would have to exist if rainfall in
the vicinity of an impoundment results in either channel flow or sheet flow across
the impoundment with subsequent runoff/erosion of sludge-bound constituents.
Consequently, erosion/runoff was considered only for the current status scenario
for those facilities with closed impoundments that have not been dredged or
capped. The erosion/runoff scenario was considered for all facilities under the
future closure scenario, since that scenario assumed that all impoundments close
at grade without dredging or capping.
• Groundwater to surface water recharge (gw-sw): Addressed the potential for
constituents in impoundments to leach into groundwater, move (with groundwater
flow) offsite, and impact surfacewater through recharge. Once constituents have
entered a surface waterbody through recharge, they then have the potential to
bioaccumulate in fish, thereby presenting an indirect exposure pathway risk
through fish ingestion. The gw-sw release scenario was evaluated for all
bioaccumulative constituent groups. Because the future closure scenario assumes
that all impoundments close without residual wastewater (i.e., only exposed
sludge remains), this release scenario was considered only for the current status
scenario.
Each of these four release scenarios was associated with specific indirect exposure pathways
(e.g., volatilization of constituents can result in dispersion and transport of those constituents to
adjacent farm fields where they can bioconcentrate in crops that are subsequently consumed by
the farmer or the public). Table C.5-1 presents a matrix that shows which exposure pathways are
associated with each release scenario and identifies whether each release scenario was considered
for the current status scenario, the future closure scenario, or both.
C-139
-------
March 26, 2001
Appendix C
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March 26, 2001
Appendix C
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-------
March 26, 2001 Appendix C
C. 5.2.2 Criteria and Ranking Algorithms Used in Generating Rankings for Individual
Exposure Pathways. Each exposure pathway was ranked for indirect exposure pathway risk
using a specific mix of criteria and an additive unweighted ranking algorithm that allowed those
criteria to be combined to generate an overall score for indirect exposure pathway risk. This
score was then converted into a qualitative rank of high, medium, or low for each exposure
pathway. The criteria were used as surrogates for key elements in the risk equation in order to
support ranking of the facilities for indirect exposure pathway risk. For example, the following
criteria were considered in evaluating the potential for indirect exposure pathway risk for the
volatilization/home garden crop consumption exposure pathway: (1) aggregated surface area for
all currently operating impoundments at the site under evaluation (represents a surrogate for
source emissions strength for constituents from that site), and (2) distance between the facility
and the nearest residential location (represents a surrogate for fate/transport and the resulting
level of exposure for the receptor).
The criteria for a given exposure pathway were selected based on two factors: (1) what
elements in the risk equation were most critical for assessing relative significance for a given
exposure pathway, and (2) which elements could be characterized quantitatively or
semiquantitatively given the combination of facility-specific and environmental setting data
available for this screening analysis.
All of the criteria have assigned integer values ranging from 1 to 3, with 1 representing
lower-risk facility-specific or environmental setting conditions, 2 representing intermediate
conditions, and 3 representing higher risk conditions. One of two approaches was used in
establishing the cutoff points for the criteria considered in the screening analyses:
• Simple ranking of facility-specific and environmental values and separation
into three equal-sized bins: For those criteria where it was not possible to define
the scores based on performance data (see next bullet), the raw criteria values
across all facilities were simply ordered from lowest to highest and the 33rd
percentile and 66th percentile values were identified as the cutoff points defining
the boundary between the first, second, and third bins, respectively. This approach
produced three equal-sized bins of values.
• Performance-based cutoff points: For several of the criteria, it was possible to
use the results from previous regional- or national-scale risk assessments as a
guide for defining cutoff points between the three scores (i.e., to support a
performance-based approach). Specifically, for distance-to-receptor following
volatilization and particulate entrainment, it was possible to review past modeling
results for volatile air concentrations and dry deposition, respectively, to establish
reasonable cutoff points for the distance to receptor criterion. In both cases,
graphs of modeling results were reviewed to identify distances at which
significant changes in vapor air concentration or particulate deposition occurred.
These distance values were then used to establish the distance measures at which
a receptor received a 1, 2, or 3. Ideally, the performance-based approach would
have been used for more of the criteria; however, the complexity of the other
C-142
-------
March 26, 2001 Appendix C
factors prohibits them from being evaluated using this approach without
conducting sophisticated sensitivity analyses.
After the criteria for a specific exposure pathway were scored for a given facility (i.e.,
given values of 1 to 3 for each criterion), they were summed, without weighting, to generate an
overall numerical score for that specific exposure pathway-the higher the aggregate score, the
greater the level of concern for indirect exposure pathway impacts. The option of using weights
to adjust the criteria to reflect differing degrees of significance in predicting indirect exposure
pathway risk was considered as was the use of a different algorithm with a multiplicative or non-
linear structure. However, for the IEP pathway screening analysis, it was decided that an
unweighted summation approach would be used to derive the aggregated scores, since it would
be difficult to develop defensible weights for individual criteria without further quantitative
analysis or to develop a more complex algorithm.1
Table C.5-2 presents the specific criteria and the additive unweighted ranking algorithm
used to generate numerical rankings for each exposure pathway. Table C.5-2 also presents the
ranges for the numerical rankings that can be generated for each combination, as well as the
ranges used in determining whether a given exposure pathway receives a high, medium, or low
ranking for the potential for indirect exposure pathway risk. The specific approach and rationale
used to establish cutoff points for assigning numerical scores of 1 to 3 for each of the criteria is
presented in Table C.5-3. Figure C.5-2 presents a case study example for one of the facilities
considered in the analysis that details the procedure followed in conducting the IEP screening
analysis for a representative facility.
C.5.2.3 Use of Demographic Data to Augment Rankings. To provide additional
information for assessing the potential for facilities to impact public health, the number of
residents and farmers located within 1 km of the facility boundaries was estimated using 1990
U.S. Census block group-level data. Specifically, area-weighted apportionment was used to
estimate the number of farmers and residents within the fraction of each block group that
intersected the 1-km ring extending out from the facility boundaries. These demographic data
were not included as a criterion in the ranking of individual facilities. Instead, they were used to
augment the overall rankings assigned to each facility by flagging those facilities falling in each
ranking category that also had a high ranking for either farmer or residential population totals.
Cutoff points for a high ranking for both the residents and farmers were established by (1)
ranking all of the facility population totals from lowest to highest, (2) identifying the 66th
percentile facility within that ranking, and (3) using the population total for that facility as the
cutoff point for a high ranking for population density (this analysis was completed separately for
the residents and farmers, thereby generating two distinct cutoff points for population density).
1 Because it can be argued that the criterion "distance to receptor" has greater predictive power in assessing
indirect exposure pathway risk, the final aggregated rankings for the 107 facilities handling bioaccumulative
constituents includes a category of results that flags those facilities with a high ranking for the potential for indirect
exposure pathway risk and a 3 for "distance to receptor" for at least one exposure pathway (see Attachment C-17,
Table C-17-2).
C-143
-------
March 26, 2001
Appendix C
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C-144
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Marc/7 26, 2007
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C-146
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March 26, 2001
Appendix C
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C-147
-------
March 26, 2001
Appendix C
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-------
March 26, 2001
Appendix C
USGS topographic map
showing site boundary,
impoundments and 2km site
radius (red border).
• Used to assess runoff/erosion
potential (e.g., slope of areas
downgradient from
impoundment, potential for
sheet versus channel flow).
• Used along with aerial
photograph to support
identification of nearest fishable
waterbody and downgradient
waterbody.
Aerial photographs.
• Used to identify nearest
receptors (farmers and
residents) for volatilization
and particulate entrainment
and nearest downgradient
receptors (farmers and
residents) for
erosion/runoff
(alternate id #180) j
Figure C.5-2.Case study example of the IEP screening analysis procedure.
C-149
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March 26, 2001
Appendix C
STEP 1 - Characterize Site: Review USGS topographic maps, aerial photos, and site-specific information reported in the SI Survey to
characterize key facility-specific and environmental setting factors. This resulted in the following attributes being identified for Site #180:
• Site #180 handles bioaccumulative metals including mercury.
• Impoundments that manage bioaccumulative chemicals at the facility are all currently active and have an aggregate surface area of 40,745 m2.
• The nearest residential area is approximately 475m from the closest impoundment, while the nearest farming area is 1100m. The nearest
fishable waterbody is Nanticoke River which is approximately 30m away from the closet impoundment. This river has a flowrate of 92.26
ft3/sec.
• The nearest downgradient fishable waterbody is the Nanticoke river as described above - there are no downgradient farms or residential areas
identified.
• The potential for erosion/runoff is assessed as HIGH (the terrain is fairly flat, but the impoundment is moderately sized and the down-gradient
waterbody is very close). The erosion/runoff predictive factor score of HIGH for Site #180 translates into a 3 for purposes of generating
numerical rankings (see below).
• 293 residents and 1-2 farmers are estimated to reside within a 1km radius of the site (this translates into a medium residential population
density and a high farmer population density for this site).
• Site #180 had no failure of the direct exposure pathway screen for air for any bioaccumulative constituents.
STEP 2 - Develop criteria scores based on facility and environmental setting characterization: The above characteristics translate into the
following criteria scores (Note, values for all criteria range from 1 to 3 with a criteria score of 1 tending to decrease the overall potential for risk,
while a 3 increases it):
The identified impoundment surface area is of average size for the sample of 107 facilities handling bioaccumulative chemicals (2). The nearest
residential areas are located an average distance for volatilization (2) but fairly far away for particulate entrainment (1). The nearest farming areas
are located relatively far for both volatilization and particulate entrainment (1 each). As mentioned in Step 1 above, this site has a HIGH potential
for erosion/runoff which translates into a 3.
STEP 3: Assess current status exposure pathways (this scenario
is evaluated based on current site conditions as reported in the SI
survey)
• volatilization/homegarden crop consumption', intermediate sized
aggregated impoundment (2) with intermediate distance
residential area (2) produces a score of 4, which is ranked
MEDIUM.
• volatilization/farm commodity consumption', intermediate sized
aggregated impoundment (2) with a fairly distant farming area (1)
produces a score of 3, which is ranked LOW.
• volatilization/fish ingestion: intermediate sized aggregated
impoundment (2), with a close fishable waterbody (3) that has low
dilution (3) produces a score of 8, which is ranked HIGH.
• particulate entrainment (all pathways): no currently closed
impoundments with exposed sludge - no significant particulate
entrainment for the current status scenario.
• runoff/erosion (all pathways): no currently closed
impoundments with exposed sludge - no significant
erosion/runoff for the current status scenario.
STEP 4: Assess future closure exposure pathways (assumption
with this scenario is that all impoundments close at grade without
measures to reduce chemical mobility)
• particulate entrainment/homegarden crop consumption.
intermediate sized aggregated impoundment (2) with intermediate
distance residential area (2) produces a score of 4, which is ranked
MEDIUM.
• particulate entrainment/farm consumption: intermediate sized
aggregated impoundment (2) with a fairly distant farming area (1)
produces a score of 3, which is ranked LOW.
• particulate entrainment/fish consumption: intermediate sized
aggregated impoundment (2), with a close fishable waterbody (3) that
has low dilution (3) produces a score of 8, which is ranked HIGH.
• runoff/erosion/homegarden crop consumption and farm commodity
consumption: No downgradient residential area or farm identified.
• runoff/erosion/fish consumption: intermediate sized aggregated
impoundment (2), with a close fishable waterbody (3) that has low
dilution (3) and a HIGH potential for erosion/runoff (3) produces a
score of 11, which is ranked HIGH.
STEP 5: Assign overall rankings - review results from the current status scenario assessment and assign an overall ranking to the site (i.e.,
potential concern, lower concern, least concern). Then, review the future closure scenario and augment overall ranking as appropriate:
• Overall Ranking: Site #180 has one current scenario exposure pathway with a HIGH ranking and no bioaccumulative chemicals that failed the
direct pathway screen for air. Therefore, it is assigned an overall ranking of lower concern for the potential to pose an indirect exposure
pathway risk.
• Augmenting the overall ranking: (a) Facility #180 had two future closure exposure pathways with a HIGH rankings and consequently, the
facility would be designated as " Lower concern + high future closure risk potential", and (b ) the site has a high farm population density relative
to other facilities that handle bioaccumulative chemicals and consequently would be designated as "Lower concern - with high farmer pop", in
terms of population density-augmented results.
Figure C.5-2. (continued)
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March 26, 2001 Appendix C
C.5.2.4 Results. This section presents the results of the indirect exposure pathway
screening analysis completed for the SI study. Of the SI facility sample, 107 facilities reported
managing bioaccumulative chemicals; consequently, the IEP screening analysis generated
numerical rankings for this subset of facilities (all other facilities in the SI sample were assigned
a default overall ranking of lowest criteria). The results presented in this section have not been
weighted to reflect the entire SI universe (see Section 3.4 for presentation of weighted results).
This section includes a variety of different results categories designed to present different
perspectives of the IEP screening analysis including (all of the results presented in this section
are aggregated across the 107 bioaccumulative constituent handling facilities):
• Overall results, which summarize the overall facility rankings across the set of
107 facilities that handle bioaccumulative chemicals.
• Receptor population/exposure pathway perspective, which presents aggregated
results according to receptor population/exposure pathway
• Release scenario perspective, which presents aggregated results according to
release scenario
• Bioaccumulative chemical category perspective, which presents aggregated
results according to the bioaccumulative chemical category groups (i.e., SVOCs,
mercury, dioxin-like compounds, metals).
The intent in providing these different categories of aggregated results is to allow
consideration of a range of risk management questions in reviewing the results of the IEP
screening analysis (e.g., "which receptor population appears to contribute the largest number of
high ranked exposure pathway results in the analysis," or "how many facilities with at least one
high ranking for the resident receptor also have a high residential population density within 1 km
of the facility boundary?").
The remainder of this section is organized according to the four groupings of aggregated
results listed above. In presenting these results, the significance of the different ranking
categories is discussed as well as the sources of uncertainty that can impact each category.
C.5.2.5 Overall Results. This section presents the overall results for the 107 facilities
that report managing bioaccumulative chemicals and, as such, represent the primary findings of
the analysis. The overall rankings presented in this section are based on the current status
scenario. The future status results were not considered in assigning overall rankings, but were
used to augment the results as explained below. The overall rankings for the facilities were
based on a review of the current status results for individual exposure pathways and the results of
the screening-level modeling for air for the bioaccumulative chemicals at a given facility.
A facility could receive an overall ranking of potential concern if one of two criteria were
met: (1) the facility had two or more current status exposure pathways with a high rank, or (2) the
facility had one exposure pathway with a high rank and at least one bioaccumulative chemical
that exceeded the direct exposure pathway screening analysis for air. This two-criteria approach
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March 26, 2001
Appendix C
for identifying potential concern-ranked facilities, reflects the goal of having the IEP analysis
identify the subset of facilities that have a strong probability of posing an indirect exposure
pathway risk to nearby populations. Both of these criteria increase the potential that a facility
will have completed indirect exposure pathways. With this approach, a facility with a single
high-ranked exposure pathway (that does not exceed risk criteria for screening-level modeling for
air) was assigned an overall rank of lower concern regarding the potential for indirect exposure
pathway risk. Table C.5-4 presents the overall ranking results for the IEP screening analysis,
which include the following categories (note, several categories of augmented results are
included here):
• Potential concern: Identifies facilities that have either (1) two high-ranking
current scenario exposure pathways, or (2) one high-ranking exposure pathway
and at least one exceedance of the direct exposure pathway screen for air for a
bioaccumulative chemical.
Table C.5-4. Overall Results for Indirect Exposure Pathway Screening Analysis
(107 Unweighted BC Sites)
Category
Number of Sites
Overall Rankings
Potential concern
29
Potential concern (high 2X)
Potential concern (one exceedance in air screening
modeling)
Potential concern with nearby receptor
Potential concern + high future
Lower concern
Lower concern + high future
Least concern
Least concern + low future
27
12
29
7
63
23
15
3
Population density-augmented results
Potential concern + high resident pop
Potential concern + high farmer pop
Lower concern + high resident pop
Lower concern + high farmer pop
9
7
11
4
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March 26, 2001 Appendix C
• Potential concern (high 2X): Identifies the number of facilities that received a
potential concern overall ranking because of having two or more current scenario
exposure pathways with a high ranking.
• Potential (one exceedance in air screen modeling): Identifies the number of
facilities that received a potential concern overall ranking because of having one
current scenario exposure pathway with a high ranking and at least one
bioaccumulative chemical that exceeded risk criteria for the screening level
modeling for air.
• Potential concern (with nearby receptor): Identifies those sites that have a
potential concern overall ranking that also have a "distance to receptor" criterion
score of "3" for one of its high-ranking exposure pathways. A "3" distance to
receptor criterion score designates that facility as having receptors very
close/adjacent to impoundments. For example, a facility would fall into this
category if it had a potential concern overall ranking and a high ranking for a
volatilization/home garden exposure pathway where the resident location was less
than 250 m from the facility and therefore received a score of "3" for distance to
receptor. Inclusion of this category of results reflects the possibility that, all other
things being equal, distance to receptor could have somewhat greater predictive
power than the other criteria in characterizing the potential for indirect exposure
pathway risk.
• Potential concern + high future: Identifies facilities assigned an overall ranking
of potential concern (based on the current status scenario as described above) that
also have at least one future closure scenario with a high rank.
• Lower concern: Identifies facilities that have either a single high-ranking current
scenario exposure pathway, or at least one medium ranking current scenario
exposure pathway and no high-ranking exposure pathway.
• Lower concern + high future: Identifies facilities assigned an overall ranking of
lower concern that also have at least one future closure scenario exposure pathway
with a high rank.
• Least concern: Identifies sites that have all current scenario exposure pathways
assigned a low ranking.
• Least concern + high future: Identifies sites assigned an overall ranking of least
concern that also have at least one future closure scenario exposure pathway with
a high rank.
• Potential concern + high resident pop: Identifies those facilities that have a high
ranking for resident-related exposure pathways and that also have a high
residential population density (for the 1-km ring surrounding the facility
boundary). For example, a facility that has a high ranking for volatilization of
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March 26, 2001 Appendix C
constituents and transport to an adjacent residential area that also has a high
ranking for residential population within the 1-km ring would have membership in
this group. This category is included to allow more focused consideration of
potential population-level impacts.
• Potential concern + high farmer pop: Parallels the "potential concern + high
resident pop," except this category focuses on the farmer (i.e., farmer-related
exposure pathways and farmer population density).
• Lower concern + high resident pop; Lower concern + high farmer pop:
Mirror the last two categories described, except that these categories identify those
facilities with medium-ranked exposure pathways that also have high rankings for
the matching receptor population.
A number of conclusions can be drawn from the results presented in Table C.5-4,
including (1) slightly less than one-third of the modeled facilities have a potential concern overall
ranking for indirect exposure pathway risk, (2) nearly all of the sites with an overall ranking of
potential concern (which is based on current status scenario results) also have at least one future
closure pathway ranked as high, (3) all of the potential concern sites have receptor populations
located very close to the facilities, and (4) roughly one-third of the potential concern facilities
also have high population densities for residents and farmers. This subset of facilities could be
given greater weight when considering the potential for population risk.
Sources of Uncertainty. A number of sources of uncertainty impact the overall ranking
results presented in this section. Each of these sources of uncertainty is related to the broader
issue of using criteria as surrogates for key elements in the risk equation. While the overall
rankings given to the 107 bioaccumulative constituent handling facilities are considered to have
sufficient confidence to support ranking of these facilities, there is the possibility that, when a
potential concern facility is subjected to site-specific risk assessment, the risk estimates resulting
from that assessment could show the facility to have insignificant risk. However, the goal of the
IEP screening analysis is not to estimate potential risk levels for individual sites, but rather to
identify the subset of facilities that would most likely have significant indirect exposures.
Specific sources of uncertainty that impact the overall ranking results include the following:
• Assessment of potential for erosion/runoff: Topographic maps used to assess
slope and the potential for sheet versus channel flow may not be current, in which
case significant changes in land use (which would not show up on older maps)
could introduce error into the characterization of this criterion.
• Distance to nearest receptor: The distance between specific impoundments and
the nearest receptor (i.e., residential areas, farms, or fishable waterbodies) was
estimated using a combination of aerial photos and topographic maps. Although
these measurements were made using the most up-to-date photos and maps
available, some of the photos and maps were somewhat dated. This introduces
uncertainty in the distance to nearest receptor measurements because land use
change could result in a receptor either being added to or removed from a given
C-154
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March 26, 2001
Appendix C
study area (note, this is less of an issue in identifying fishable waterbodies). In
addition, the possibility of having agricultural activity within facility boundaries
was not considered, even though the aerial photos did show evidence of such
activity. This activity could have been associated with bioremediation or some
other non-agricultural commodity-related activity. If there is agricultural activity
within facility boundaries, then some of the distance to nearest receptor
measurements could be misrepresented.
• Residential exposure scenarios and home gardening: A critical assumption in
assessing exposure pathways for the resident was that home gardening occurs
within the residential areas located closest to the facility. To the extent that home
gardening does not occur in these areas, then the exposure pathway would not be
complete and any rankings for this receptor would be incorrect.
Receptor Population (Exposure Pathway) Perspective. This section presents aggregated
results of the IEP screening analysis differentiated by receptor population (and, by implication,
indirect exposure pathway).2 The intent in presenting these results is to allow the reader to
determine which receptor populations drive the overall rankings for the current status scenario
for the 107 facilities that report handling bioaccumulative chemicals. As discussed below, each
of the receptor populations has a different level of uncertainty associated with its inclusion in this
screening analysis, which could impact the way rankings are interpreted.
Table C.5-5 shows the number of facilities that had achieved a given ranking for each of
the three receptor populations (e.g., the number of facilities that had a high ranking for one of the
exposure pathways that involved the resident).
Results presented in Table C.5-5 suggest that the resident and fisher receptor populations
contribute the largest number of high-ranking exposure pathways in the screening analysis,
although the farmer receptor population also makes a significant contribution. The fisher
receptor population contributes the majority of the medium-ranking exposure pathways.
Table C.5-5. Receptor Population Perspective: Number of Facilities with
Specific Ranking Level for Exposure Pathways Associated with Each Receptor Population
Receptor
Population
Resident
Farmer
Fisher
High
23
14
28
Medium
34
25
61
Low
27
20
18
Each of the receptor populations considered in this analysis is associated with a single, or distinct, set of
indirect exposure pathways. These include fisher (self-caught fish consumption), resident (consumption of home
garden-produced crops), and farmer (consumption of home-produced agriculture commodities such as crops,
livestock, and dairy).
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Appendix C
Sources of Uncertainty. Sources of uncertainty associated with this category of results
include many of the same sources described in the last section for the overall ranking results. For
example, the residential ranking results are impacted by (1) uncertainty associated with
identifying the nearest residential areas using aerial photos that may be dated in some cases (i.e.,
land use change could have involved changes in the location of houses), and (2) uncertainty
associated with the presence of home gardens in specific residential areas. Farmer rankings are
impacted by the exclusion of areas within facility boundaries that could potentially be
agricultural land use. Fisher rankings are impacted by uncertainty associated with assessing the
potential for erosion/runoff and, consequently, assessing the magnitude of chemical loading to
either nearest or downgradient fishable waterbodies.
Release Scenario Perspective. This section presents aggregated results of the IEP
screening analysis differentiated by release scenario (i.e., volatilization, particulate entrainment,
erosion/runoff, leaching to groundwater with subsequent transport, and surface water impact).
This set of aggregated results is intended to provide perspective on how the rankings of exposure
pathways relate to the different release scenarios considered in the analysis and, as such, can be
used to answer a range of questions related to release scenarios and exposure pathway rankings
(e.g., which release scenario dominates high exposure pathway rankings under the current status
scenario).
Table C.5-6 presents the aggregated results differentiated by release scenario. Note that
Table C.5-6 includes only particulate entrainment and erosion/runoff release scenarios for the
future closure scenario since it is assumed for the future closure scenario that volatilization and
groundwater impacts are minimal given the absence of wastewater recharge to the impoundment
following closure.
Table C.5-6. Release Scenario Perspective: Number of Facilities with
Specific Exposure Pathway Rankings for Each Release Scenario
Exposure Pathway
Rankings
Release scenario
High
Med
Low
Current status
Volatilization
Particulate entrainment (current)
Erosion/runoff (current)
Groundwater to surface water
40
5
5
15
31
20
13
49
1
2
3
43
Future closure
Particulate entrainment (future)
Erosion/runoff (future)
42
39
43
56
10
12
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Appendix C
Results presented in Table C.5-6 suggest that, for the current status scenario,
volatilization is the dominant release scenario producing high rankings for indirect exposure
pathways. However, high rankings under the future closure scenario are nearly evenly distributed
between the two release scenarios considered for the future closure scenario (i.e., erosion/runoff
and paniculate entrainment).
Sources of Uncertainty. There is considerable uncertainty associated with using a
screening approach based on predictive (surrogate) factors to represent complex fate/transport
processes such as volatilization, dispersion, and runoff/erosion. However, the overall level of
confidence associated with the approach used to represent these fate/transport processes in
screening the facilities for indirect exposure pathway risk is considered sufficient to support the
ranking and descriptive goal of the IEP screening analysis.
Bioaccumulative Chemical Group Perspective. This section presents overall rankings for
the 107 bioaccumulative constituent handling facilities differentiated by constituent class (i.e.,
metals (excluding Hg), Hg, SVOCs, and dioxin-like compounds). This set of aggregated results
is intended to provide perspective on how the rankings of facilities relate to the different
bioaccumulative chemical classes considered in the analysis. Consequently, these results can be
used to answer a range of questions related to bioaccumulative chemical classes and ranking
scores (e.g., which chemical class is associated with potential concern-ranked sites).
Table C.5-7 presents the number of facilities with a specific overall rank that are reported
to handle a particular bioaccumulative chemical class. In interpreting these results, it is
important to note that the different chemical classes are not necessarily mutually exclusive (i.e.,
the set of eight facilities identified as having a "potential" overall ranking under the metals
category for the current status scenario do not necessarily handle bioaccumulative metals
exclusively; facilities in that category could also handle other constituents). However, the table
does allow the reader to assess which chemical classes are consistently associated with potential
concern, lower concern, or least concern ranks across all 107 facilities.
Table C.5-7. Bioaccumulative Chemical Group Perspective: Number of
Facilities with Specific Overall Ranking for Each Chemical Class
Overall IEP Screening Analysis
Ranking
Chemical Class
Metals (excluding Hg)
Mercury
SVOCs
Dioxin-like compounds
Potential
concern
25
22
12
17
Lower
concern
56
42
22
10
Least
concern
15
0
0
0
SVOCs = Semivolatile organic compounds.
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March 26, 2001 Appendix C
Results presented in Table C.5-7 suggest that the potential concern category is dominated
by facilities that handle metals including mercury, although a significant number of potential
concern facilities also handle SVOCs and dioxin-like compounds.
The different chemical classes cannot be differentiated in any meaningful way with regard
to uncertainty in the screening analysis; consequently, the issue of uncertainty is not addressed
specifically from the chemical class perspective.
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March 26, 2001 Appendix C
C.6 Ecological Screening Assessment
Industrial wastes managed in surface impoundments not only can impact the health of
people living near them, they can also have adverse effects on nonhuman organisms and natural
systems. For example, wildlife can come into contact with contaminants by swimming or living
in contaminated waters or by drinking or catching prey, such as fish, from contaminated waters.
Plants that grow in soils containing constituents of concern (CoCs) can take them into their
leaves and stems through root uptake, which can have detrimental effects on the plants as well as
on the animals that eat them. Microorganisms and small invertebrates that live in close contact
with the soil (e.g., worms) can accumulate CoCs through contact with contaminated soil.
Therefore, it is important to evaluate risks posed to ecological receptors as well as those posed to
humans. Protection of human health does not necessarily protect ecological receptors. Some
chemicals are more toxic to nonhumans; wildlife species generally have higher metabolic rates
than humans and, therefore, eat, drink, and breathe proportionately more contaminants than
humans; and nonhuman organisms live in closer association with their immediate environment
and often cannot avoid contamination or replace destroyed food sources as humans can (Suter,
1993).
The ecological risk screening is somewhat different from the human health screening in
that a single comparison of screening factors and constituent concentrations was conducted. The
scope of this phase of the assessment includes a subset of 43 constituents for which toxicological
and exposure factor data were readily available. The assessment addresses 57 vertebrate species
as well as 5 community-level receptors. Depending on the ecological receptor of concern, the
analysis estimates risks from either the ingestion of contaminated plants, prey, and media or from
direct contact with a contaminated medium such as sediment or soil. The ecological risk
estimates were compared to risk criteria to prioritize the list of constituents, impoundments, and
facilities that warrant further evaluation of the likelihood of adverse ecological effects.
C. 6.1 Overview and Goals
The primary goal of the ecological screening assessment was to establish a priority list of
constituents, impoundments, and facilities based on the potential for adverse ecological effects.
The screening approach considers the potential for adverse effects to a suite of ecological
receptors, including mammals and birds and aquatic, benthic, and soil fauna that are found in
terrestrial, freshwater, and wetland habitats. Facilities with impoundments that exceed the
ecological risk criterion for one or more chemicals are carried forward for further analysis. The
habitats and receptors considered in this study are consistent with the national assessment
strategy developed to support the Hazardous Waste Identification Rule proposed in November
1999. Because the HWIR risk assessment framework was intended to support national studies of
waste management practices, the SI Study has adopted this framework as the basis for selecting
receptors and habitats.
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March 26, 2001 Appendix C
C.6.2 Management Goals and Assessment Endpoints
Assessment endpoints, defined as "explicit expressions of the actual environmental value
that is to be protected" (U.S. EPA, 1998a), serve as a critical link between the ecological risk
assessment and the management goals. For the SI Study, the management goals may be
summarized as follows: "prioritize impoundments and facilities based on the potential for
adverse ecological effects and describe the national distribution of ecological risks associated
with the management of wastes in surface impoundments." Two key elements are required to
define an assessment endpoint: (1) a valued ecological entity (e.g., a species, a community) and
(2) an attribute of that entity that is important to protect (e.g., reproductive fitness).
For the SI Study, ecological exposures are assumed to occur at facilities that may be
located anywhere within the contiguous United States. Consequently, a suite of assessment
endpoints was chosen based on
• Significance for ecosystem functions
• Ability to represent a variety of habitat types
• Position along a continuum of trophic levels
• Susceptibility to chemical stressors managed in surface impoundments.
In Table C.6-1, the assessment endpoints (i.e., values to be protected) selected for the SI
Study analysis are defined in terms of (1) the significance of an ecological entity, (2) the
ecological receptor representing that entity, (3) the characteristic about the entity that is important
to protect, and (4) the measures of effect used to predict risk. The intent of including multiple
receptors is that, by protecting producers (i.e., plants) and consumers (i.e., predators) at different
trophic levels, as well as certain structural components (e.g., benthic community), a degree of
protection from chemical stressors may be inferred to the ecosystem as a whole. Consequently,
the selection of the assessment endpoints for each receptor taxon is critical to the development of
ecological screening factors.
Risk for sensitive receptors such as threatened and endangered species or managed lands
(e.g., national wildlife refuges, state and national parks, and national forests) were not estimated
for a screening level assessment. However, the SI Study included a qualitative assessment of the
presence of sensitive ecosystems in proximity to SI facilities. Facilities with managed lands
within 3 kilometers or with wetlands within 1 kilometer were identified, and this information was
used in identifying facilities of potential concern.
C.6.3 Summary of Approach
As with the screening approach for human health, the ecological screening analysis
calculates risks to individual ecological receptors (e.g., red fox, aquatic biota) based on the ratio
between ecological risk screening factors and the concentrations of constituents in surface
C-160
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March 26, 2001
Appendix C
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C-161
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March 26, 2001 Appendix C
impoundments reported in the survey questionnaire. Consequently, ecological risk screening
factors are given in units of concentration (e.g., mg/kg or mg/L). The use of screening factors is
considered to be protective because the factors are
• Derived using established EPA protocols for use in evaluating ecological risk
(e.g., sediment quality criteria)
• Based on highly protective assumptions regarding the toxicological potency of a
constituent (e.g., no adverse effects levels and low adverse effects levels)
• Calculated assuming that all media and food items originate from a contaminated
source.
In addition, the application of the screening factors assumes that ecological receptors are exposed
directly to chemical concentrations in the sludge and wastewater found in the surface
impoundment. For mammals, birds, and selected herpetofauna, these screening factors reflect
ingestion of contaminated media, plants, and prey. For other receptor groups, such as soil fauna,
these screening factors reflect both the direct contact and ingestion routes of exposure.
C.6.3.1 Selection of Representative Species/Receptor Groups. The 62 ecological
receptors used for the HWIR assessment were selected for use in the screening analysis. The
HWIR receptors were developed to support the assessment of ecological risks in 14 different
terrestrial, waterbody margin, and wetland habitats. They are representative of the entire
continental United States, and they reflect potential exposure for a variety of trophic levels,
feeding strategies, and taxa (see Attachment C-19 to this appendix). Furthermore, the HWIR
databases for these receptors contain complete exposure factor data as well as a compilation of
selected ecotoxicological data that are relevant to the surface impoundment study endpoints.
Thus, this group of receptors constitutes a readily available data set that is appropriate for use in
the assessment.
In the screening analysis for the SI Study, it was assumed that each facility site supports
terrestrial receptors. Receptors found in waterbody margin habitats (i.e., stream corridor and lake
or pond margin) were assumed to occur at sites where there are fishable waterbodies. Fishable
waterbodies were defined as lakes and ponds designated in Reach File Version 3.0 Alpha Release
(RF3-Alpha) (U.S. EPA, 1994c) and streams of order 3 or higher. Receptors found in wetlands
were assumed to occur at sites where wetlands are designated by the National Wetland Inventory
(NWI) data (U.S. FWS, 1998), where available, or by EPA's Geographic Information Retrieval
and Analysis System (GIRAS) (U.S. EPA, 1994d) where NWI coverage was not available. The
HWIR ecological receptor databases include information on the geographic distribution of each
receptor species. These data were used to match species distribution with facility location so that
risk for each receptor species was estimated only at those facilities located within its geographic
range.
C.6.3.2 Identification of Relevant Exposure Pathways. Ecological exposure pathways
for the screening analysis were identified based on (1) both active and postclosure scenarios for
surface impoundments, and (2) likely routes of exposure for receptors assigned to simple food
C-162
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March 26, 2001 Appendix C
webs. Chemical constituents may volatilize from active surface impoundments and deposit onto
adjacent soils, plants, or surface waters. In addition, constituents may leach into groundwater
and contaminate nearby surface waters and sediments. Following closure, a surface
impoundment may be integrated with local habitats (assuming the contaminant concentration
does not prevent vegetative growth) and serve as a long-term source of exposure to certain types
of constituents (e.g., metals). As shown in Figures C.6-1 and C.6-2, receptors may be exposed to
contaminated media and/or prey and plants in both terrestrial and aquatic systems. Consequently,
the exposure pathways that were assessed are
• Direct contact with contaminated sludge/soil (e.g., plants, soil fauna)
• Ingestion of contaminated sludge/soil (e.g., mammals, birds)
• Ingestion of plants/prey from contaminated sludge/soil (e.g., mammals, birds)
• Direct contact with contaminated surface water (e.g., fish, amphibians)
• Direct contact with contaminated sludge (e.g., benthos)
• Ingestion of aquatic plants/prey from contaminated surface water (e.g., birds)
• Ingestion of contaminated surface water (e.g., mammals).
Exposure routes that were not addressed in the ecological screening assessment include
• Dermal absorption from contaminated surface water or sludge (e.g., mammals)
• Inhalation of volatile constituents in air.
Dermal absorption of constituents is considered to be an insignificant exposure pathway
for potentially exposed wildlife receptors and was not assessed for two reasons:
• Dense undercoat or down effectively prevents chemicals from reaching the skin of
wildlife species and significantly reduces the total surface area of exposed skin
(Peterle, 1991; U.S. ACE, 1996).
• Results of exposure studies indicate that exposures due to dermal absorption are
insignificant compared to ingestion for terrestrial receptors (Peterle, 1991).
Inhalation of volatile compounds was not assessed for wildlife receptors for two reasons:
• Concentrations of volatile chemicals released from soil to aboveground air are
drastically reduced, even near the soil surface (U.S. ACE, 1996).
• Significant concentrations of VOCs would be required to induce noncarcinogenic
effects in wildlife based on inhalation toxicity data for laboratory rats and mice
(U.S. ACE, 1996).
C.6.4 Development of Ecological Screening Factors
The screening analysis addresses constituents that were identified as occurring in
surveyed surface impoundments and that were included in the HWIR analysis. Constituents
included in the HWIR analysis are supported by available ecotoxicological data and by exposure
C-163
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March 26, 2001
Appendix C
Apex Species
can
any
potentially prey on
T1 or T2 species
Omnivorous Mammals
T3 • Black bear
• Red fox
• Coyote
Omnivorous Birds
• Burrowing owl
Carnivorous Birds
• Hawks
• American kestrel
• Loggerhead shrike
Carnivorous Mammals
• Weasels
• Kit fox
Medium Omnivores
• Racoon
Carnivorous
Reptiles
• Snakes
Omnivorous
Small Mammals
• Shrews
• Least weasel
• Mice
Carnivorous
Amphibians
• Newts
• Salamanders
• Frogs
Omnivorous
Reptiles
Eastern box turtle
Omnivorous Birds
• Passerines
• Ground birds
Insectivores
•Bats
• Birds
Small Herbivorous
Mammals
• Rabbits • Mice
• Voles • Shrews
Large Herbivores
• Mule deer
• White-tailed deer
Soil Community
Other
invertebrates
Flying
invertebrates
Vascular Plants - Primary Producers
Movement through the food web
of primary producer biomass
Movement through the food web
of soil community biomass
Movement through the food web
ofT1 biomass
Movement through the food web
of T2 biomass
Figure C.6-1. Terrestrial web, including example receptors.
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March 26, 2001
Appendix C
Terrestrial Receptors
Dependent on Aquatic Habitats
Terrestrial Piscivores
(T2 and T3)
• Bald eagle
• Osprey
• Green heron
• Kingfisher
• Otter
• Mink
Terrestrial Omnivores
(T2 and T3)
• Bear
• Raccoon
• Coyote
• Amphibians
• Turtles
• Wading birds
Terrestrial Herbivores
(T1)
• Beaver
• Muskrat
• Deer
• Ducks
Simplified Aquatic Food Web
Sediment Community
Aquatic Invertebrates
Herbivorous Fish
Primary Producers - Aquatic Plants
Algae
Figure C.6-2 Interface between terrestrial and aquatic food webs, including example receptors.
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March 26, 2001 Appendix C
factor data for the relevant receptors and, therefore, could be assessed without further literature
review or extensive data collection and processing. The screening factors for these constituents
were taken directly from the HWIR analysis, where appropriate, and calculated using the HWIR
ecological databases in other cases. The following discussion describes the methods and data
sources used in the development of screening factors, which are presented in Attachment C-23 to
this appendix.
C.6.4.1 Selection of Appropriate Ecotoxicological Studies—Population Inference. As
suggested in Table C.6-1, risks to three groups of receptors (mammals, birds, and amphibians)
were estimated based on endpoints relevant to population sustainability. It is important to note
that screening factors were not developed based on population-level studies. Rather,
ecotoxicological data on selected physiological endpoints (e.g., developmental effects) were used
to infer risks to wildlife populations.
Table C.6-2 presents some examples of key data sources used analysis to identify suitable
ecotoxicological studies.
Table C.6-2. Selected Sources of Toxicity Data
Databases
• Hazardous Substances Data Bank (HSDB). National Library of Medicine, National Toxicology
Information Program. Bethesda, MD.
• PHYTOTOX. Chemical Information System (CIS) Database.
• Registry of Toxic Effects of Chemical Substances (RTECS). National Institute for Occupational
Safety and Health (NIOSH), Washington, DC.
Compilations
• Agency for Toxic Substances and Disease Registry (ATSDR). 1997. Toxicological Profiles. On
CD-ROM. CRC press. U.S. Public Health Service. Atlanta, GA.
• Devillers, I. and I.M. Exbrayat. 1992. Ecotoxicity of Chemicals to Amphibians. Grodon and
Breach Science Publishers. Philadelphia, PA.
• Eisler, R. 1985-1993. Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review. U.S. Fish
and Wildlife Service Biological Reports.
• Hudson, R.H., R.K. Tucker, and MA. Haegele. 1984. Handbook of Toxicity of Pesticides to
Wildlife. U.S. Fish and Wildlife Service. Resour. Publ. 153. 90 pp.
• Sample, B.E., D.M. Opresko, and G.W. Suter II. 1996. Toxicological Benchmarks for Wildlife:
1996 Revision. Prepared for the U.S. Department of Energy.
For amphibians, the development of screening factors is severely limited by data
availability. Several compendia presenting amphibian ecotoxicity data (e.g., U.S. EPA, 1996a;
Power et al., 1989) as well as primary literature sources were reviewed, and it was determined
that there was a general lack of chronic or subchronic ecotoxicological studies. Consequently,
studies on acute exposures during sensitive amphibian life stages were selected for developing
C-166
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March 26, 2001 Appendix C
screening factors. The potential sensitivity of this receptor group warrants their inclusion even
though chronic study data are not yet available. All studies used to develop amphibian screening
factors included the following information:
• Test organism
• Toxicological endpoint
• Exposure duration
• Life stage at which exposure occurred (e.g., embryo, tadpole).
Appropriate toxicity data for amphibians included reproductive effects, developmental effects, or
lethality from studies conducted for an exposure duration of less than 8 days. Limiting the study
duration to short exposures allowed use of a larger data set in deriving the screening factors.
For mammals and birds, only toxicity studies relevant to ingestion were reviewed (e.g.,
gavage); studies where the chemical was administered via injection or implantation were not
reviewed. At a minimum, studies reported the following data elements to be considered for use
in developing the ecological screening factors:
Test organism
Toxicological endpoint
Dose-response information
Exposure duration
Exposure route
Sample size.
Preferred Studies—Toxicity studies that reported reproductive impairment,
developmental abnormalities, and mortality were preferred to studies on other physiological
endpoints because these endpoints are highly relevant to the assessment endpoints selected for
the SI Study (e.g., population sustainability). In addition, the use of reproductive and
developmental toxicity data has been recommended in guidance across several federal agencies
(U.S. EPA, 1998b; Department of the Air Force, 1997; U.S. ACE, 1996). Studies that report
NOAELs as well as LOAELs were preferred. Several other important aspects of study selection
are summarized below.
Duration of Exposure. Duration is critical in assessing the potential for adverse effects
to wildlife. However, since definitive guidance is not available on subchronic versus chronic
exposures, chronic exposures are defined as greater than 50 percent of the life span of
mammalian wildlife representative species. Little information exists concerning the life span of
birds used in toxicity studies, and a standard study duration has not been established for avian
toxicity tests. Therefore, exposures greater than 10 weeks were considered chronic for birds;
exposures less than 10 weeks were considered subchronic (Sample et al., 1996).
Timing of Exposure. The timing of exposure is critical in assessing the potential for
adverse effects to wildlife. For example, early development is a particularly sensitive life stage
due to the rapid growth and differentiation occurring within the embryo and juvenile. For many
species, exposures of a few hours to a few days during gestation and early fetal development may
C-167
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March 26, 2001 Appendix C
produce severe adverse effects (Sample et al., 1996). Therefore, in the absence of chronic studies
on developmental or reproductive effects (e.g., multigenerational studies), studies that report
exposures during reproductive and/or developmental stages were in some cases selected for use
in developing ecological screening factors.
Endpoint of Interest. A review of toxicity data indicated that reproductive or
developmental effects were frequently observed at lower doses than those causing mortality .
Therefore, chronic mortality studies were used only when reproductive or developmental data
were not available. Physiological (e.g., enzyme activity), systemic, and behavioral responses
were less preferred because it is often difficult to relate these responses to quantifiable decreases
in reproductive fitness or the persistence of wildlife populations. Tumorigenic and carcinogenic
toxicity studies are not considered ecologically relevant and were not used to develop toxicity
benchmarks because debilitating cancers in wildlife are exceedingly rare under field conditions.
C.6.4.2 Selection of Appropriate Ecotoxicological Studies—Community Inference. The
community-based screening factors generally reflect direct exposures to a contaminated medium,
which, in the screening analysis, is represented by actual impoundment concentrations in water
and sludge. Risks were estimated for five community-level receptors: soil fauna, terrestrial
plants, aquatic biota, algae and aquatic plants, and benthos. Risk was estimated based on
endpoints relevant to sustainability of community structure and function. The screening factors
for communities generally are not based on community-level studies in the sense that they do not
reflect endpoints relevant to community dynamics (e.g., predator-prey interactions). Rather, they
are based on the theory that protection of 95 percent of the species in the community will provide
a sufficient level of protection for the community (see, for example, Stephan et al., 1985, for
additional detail). As with the wildlife populations, ecotoxicological data on individual species
were used to infer risks to the community.
Appropriate ecotoxicological studies to derive screening factors for these receptor groups
were identified in a number of compendia; as a result, it was not necessary to conduct primary
literature reviews to identify suitable studies. These compendia generally present threshold
concentrations that may be used directly as screening factors with little or no modification.
Table C.6-3 presents the primary data sources used to support the derivation of screening factors
for the community receptors. The selection process for screening factors and the screening factor
calculations are discussed in the following section.
C.6.4.3 Calculation of Ecological Screening Factors—Receptor Populations. Screening
factors for receptor populations consist of media concentrations that are assumed to be
protective. Each screening factor is species- and medium-specific. Calculation of the screening
factors was based on the ecotoxicological data identified as described above in Section C.6.4 and
on species-specific exposure factors from the HWIR analysis. These exposure factors include
body weight, ingeston rates, and dietary composition; Attachment 21 presents the exposure factor
values used in the assessment.
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March 26, 2001
Appendix C
Table C.6-3. Examples of Primary Data Sources for Derivation of Screening Factors
for Community Receptors
Source
Contents
Plant Community
Efroymson, R.A., M.E. Will, G.W. Suter II, and A.C.
Wooten. 1997a. Toxicological Benchmarks for
Screening Contaminants of Potential Concern for
Effects on Terrestrial Plants: 1997Revision.
This document provides effects data for terrestrial
plants exposed in soil and solution mediums.
Approximately 45 constituents have proposed soil
criteria.
PHYTOTOX Database. Office of Research and
Development, U.S. Environmental Protection Agency.
This database contains over 49,000 toxicity tests on
terrestrial plants for more the 1,600 organic and
inorganic chemicals and 900 species.
Freshwater Community / Algae and Aquatic Plants
AQUIRE (AQUatic toxicity Information REtrieval)
Database. 1997. Environmental Research Laboratory,
Office of Research and Development, U.S. EPA,
Duluth, MN
This database contains over 145,000 toxicity tests for
more than 5,900 organic and inorganic chemicals and
2,900 aquatic species.
U.S. EPA. 1989a. Ambient Water Quality Criteria.
Washington, DC.
These chemical-specific documents provide the
ecotoxicity data and derivation methodologies used to
develop the National Ambient Water Quality Criteria
(NAWQC).
U.S. EPA. 1995. Great Lakes Water Quality Initiative
Criteria Documents for the Protection of Aquatic Life
in Ambient Water. Office of Water. (U.S. EPA,
1996a Update)
For a limited number of constituents, the GLWQI has
proposed surface water criteria for aquatic biota using
analogous methods as implemented in the derivation of
the NAWQC.
Suter II, G.W., and C. Tsao. 1996. Toxicological
Benchmarks for Screening Contaminants of Potential
Concern for Effects on Aquatic Biota: 1996 Revision.
This compendia reference provides acute and chronic
water quality criteria for freshwater species including
algae.
Soil Community
Efroymson, R.A., M.E. Will, and G.W. Suter II.
1997b. Toxicological Benchmarks for Contaminants
of Potential Concern for Effects on Soil and Litter
Invertebrates andHeterotrophic Process: 1997
Revision. Oak Ridge National Laboratory.
This document provides effects data for soil biota
(i.e., microbial processes and earthworms).
Approximately 35 constituents have proposed soil
criteria, and some field studies are included.
CCME (Canadian Council of Ministers of the
Environment), 1997. Recommended Canadian Soil
Quality Guidelines.
The criteria developed by the CCME are
concentrations above which effects are likely to be
observed.
Sediment Community
U.S. EPA. 1993a. Technical Basis for Deriving
Sediment Quality Criteria for Nonionic Organic
Contaminants for the Protection ofBenthic Organisms
by Using Equilibrium Partitioning.
This document supplies lexicological criteria for
nonionic hydrophobic organic chemicals using FCVs
(final chronic values) and SCVs (secondary chronic
values) developed for surface water (Sediment Quality
Criteria, SQC).
(continued)
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March 26, 2001
Appendix C
Table C.6-3. (continued)
Source
Contents
Plant Community (continued)
Long and Morgan. 1991. The Potential for Biological
Effects of Sediment-Sorb ed Contaminants Tested in the
National Status and Trends Program. National
Oceanic and Atmospheric Administration (NOAA)
Technical Memorandum. Update: (Longetal., 1995)
Jones, D.S., G.W. Sutler III, andR.N. Hall. 1997.
Toxicological Benchmarks for Screening
Contaminants of Potential Concern for Effects on
Sediment-Associated Biota: 1997 Revision. Oak Ridge
National Laboratory.
MacDonald, D.D. 1994. Approach to the Assessment
of Sediment Quality in Florida Coastal Waters.
Florida Department of Environmental Protection
(FDEP), Tallahassee.
Field-measured sediment concentrations are correlated
with impacts to sediment biota in estuarine
environments. Measures of abundance, mortality, and
species composition are the primary toxicity endpoints.
This document proposes sediment criteria for both
organic and inorganic constituents using both field and
estimation methodologies.
This approach applies statistical derivation methods to
determine sediment criteria using NOAA data. The
resulting criteria are more conservative than NOAA
values.
The calculation of ecological screening factors for receptor populations is based on the
implicit assumption that each receptor species forages only within the contaminated area,
regardless of the size of its home range. For smaller animals, this assumption has little impact on
the estimates of exposure. However, for larger animals with more extensive foraging areas, this
assumption may overestimate exposure if the animal's foraging patterns tend to be evenly spread
over the home range. Thus, it is important to recognize both the explicit and implicit sources of
protection in this methodology.
For amphibian populations, a screening factor for water (SFwater)was derived as the
geometric mean of acute studies meeting the data requirements discussed above (i.e., relevant
endpoint, acute exposure, high effect level). However, it is important to point out that this
screening factor should be construed as only "protective" of gross effects to amphibian
populations (e.g., lethality to 50 percent of the population), and careful consideration should be
given in interpreting the screening results for amphibians. The remainder of this section outlines
the basic technical approach used to convert avian or mammalian benchmarks (in daily doses) to
soil and water screening factors (in units of concentration).
Once the appropriate ecotoxicological study was identified for mammals and/or birds,1
the screening factors were calculated for each medium of interest using a three-step process:
1. Scale benchmark from test species to receptor species.
2. Identify uptake/accumulation factors.
3. Calculate protective concentration (i.e., screening factor).
1 Reptiles are not discussed in this section because of the data deficiencies for this receptor group.
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March 26, 2001 Appendix C
Step 1. Scale Benchmark from Study Species to Receptor Species
The benchmarks for the mammalian and avian receptors were extrapolated from the study
species to the receptor species within the same taxa using a cross-species scaling equation
(Sample et al., 1996). Benchmarks were based on the geometric mean of NOAEL and LOAEL
values. For population-inference benchmarks for mammals, the extrapolation is performed using
Equation C.6-1.
/ 6wV\i/4
GEOMN^ = GEOMNSS • —- (C.6-1)
V bw^J
where
GEOMNSS = GEOMN for the study species
bwRS = body weight of the receptor species
bwss = body weight of the study species.
This is the default methodology EPA proposed for carcinogenicity assessments and reportable
quantity documents for adjusting animal data to an equivalent human dose.
For avian species, research suggests that the cross-species scaling equation used for
mammals is not appropriate (Mineau et al., 1996). Mineau et al. (1996) used a database that
characterized acute toxicity of pesticides to avian receptors of various body weights. The results
of the regression analysis revealed that applying mammalian scaling equations may not predict
sufficiently protective doses for avian species. Mineau et al. (1996) suggested that a scaling
factor of 1 provides a better dose estimate for birds, as shown in Equation C.6-2. This
recommendation was adopted for developing screening factors for avian receptors.
/ bw^y
GEOMN^ - GEOMNSS • —^ (C.6-2)
V bWpg)
Attachment 20 to this appendix presents the scaled benchmarks for mammals and birds.
Step 2. Identify Uptake/Accumulation Factors
Movement of contaminants through the food web is an important exposure vector for
mammals and birds. Consequently, estimates of chemical accumulation in the tissues of plants
and prey items are required. For receptors likely to rely on aquatic systems for food (e.g.,
kingfisher), bioaccumulation factors and/or bioconcentration factors are required for aquatic
biota such as fish, benthos, and aquatic plants. These data were identified in the open literature
or estimated for organic constituents using regression equations such as that shown in
Equation C.6-3 (Lyman et al., 1990):
log BCF - 0.76 [log (KJ\ - 0.23 (C.6-3)
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March 26, 2001 Appendix C
where
BCF = estimated bioconcentration factor for fish
Kow = constituent-specific octanol-water partition coefficient.
For receptors found primarily in terrestrial systems, bioconcentration factors (BCFs) were
required for terrestrial plants, soil invertebrates (e.g., earthworms), and vertebrates. These BCFs
report the relationship between tissue concentrations and soil concentrations. As with aquatic
accumulation factors, these values were identified in the open literature and EPA references or
calculated based on the relationship between log Kow and accumulation in lipid tissue (Sample et
al., 1998a, 1998b). To ensure that the ecological screening assessment is protective, a default
value of 1 was assigned to each uptake/accumulation factor that could not be derived through
estimation methods or identified in the literature. Attachment 22 presents the biouptake factors
used in the screening factor calculations.
Step 3. Calculate Protective Concentration for Receptor
Based on the GEOMNRS, the screening factor for a receptor that relies on aquatic biota as
the primary food source was calculated as a function of the receptor's body weight, the receptor's
ingestion rate for food and water, and the bioaccumulation potential of the constituent, as shown
in Equation C.6-4:
GEOMN^ x bw
SF , = ^ (C.6-4)
(If ^BAF. x F x AB) + (I , )
v jood'—' J J J water-7
where
bw = body weight (kg)
Ifood = total daily intake of aquatic biota (kg WW/d)
BAFj = bioaccumulation factor for food item j (L/kg WW))
Fj = fraction of diet consisting of food item j (unitless)
ABj = absorption of chemical in the gut from food item j (assumed =1)
Iwater = total daily soil intake (kg/d).
Equation C.6-4 can also be used to derive an "impoundment use only" screening factor for sites
that do not have any fishable waterbodies identified in the survey data. For these cases, only Iwater
would be included in the denominator to reflect use of the impoundment as a drinking water
source.
For terrestrial systems, Equation C.6-5 is simply modified to account for soil or sludge
intake:
GEOMN^ x bw
soil/sludge ~ ~7~j V BCF r F r AR} + (J i (C.6-5)
\lfood L D(-^j X fj X ADj) + Vsoil/sludge)
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March 26, 2001 Appendix C
where
bw = body weight (kg)
Ifood = total daily food intake of terrestrial biota (kg/d)
= bioconcentration factor for food item j (assumed unitless)
= fraction of diet consisting of food item j (unitless)
= absorption of chemical in the gut from food item j (assumed =1)
ISoii/siudge = total daily soil intake (kg/d).
Information sources to develop the input values for body weight (bw), ingestion rates (Ixx), and
dietary fractions (Fj) were taken from the extensive HWIR databases. The HWIR databases were
developed using EPA's Wildlife Exposure Factors Handbook (U.S. EPA, 1993b) and augmented
by substantial literature review and synthesis of a variety of information sources.
The dietary fractions (Fj) were derived from the HWIR dietary preference database and
reflect the variability in receptor species' dietary composition. The dietary preference database
consists of the minimum and maximum proportion of a species'diet that different diet items can
constitute. Diet items are categorized as one of 17 types, including different types of vegetation
(e.g., fruits, forage, grain, roots) and several categories of prey (e.g., small birds, small mammals,
invertebrates, fish). For example, the Eastern box turtle's dietary proportion ranges are:
Diet Item Dietary Proportion Range
Soil invertebrates 8 to 93
Fruits 7 to 92
Worms 15 to 27
Forage 0 to 24
The development of the dietary preference database is fully described in the HWIR
documentation (U.S. EPA 1999d). Each receptor's diet was constructed using the midpoint of
dietary proportions for each diet item, beginning with the item with highest midpoint value and
proceeding through the diet items until a full diet (100 percent) was accumulated. Thus, the
turtle's diet would consist of 50.5 percent soil invertebrates and 49.5 percent fruits based on the
following dietary proportion midpoints:
Diet Item Dietary Proportion Midpoint
Soil invertebrates 50.5
Fruits 49.5
Worms 21
Forage 12
The dietary composition used for each receptor species is presented in Attachment 21.
C.6.4.4 Calculation of Ecological Screening Factors—Receptor Communities. The
calculation of ecological screening factors for receptor communities relied heavily on existing
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March 26, 2001 Appendix C
data sources, many of which have produced peer-reviewed concentrations for soils and surface
water presumed to be protective of ecological receptors. Examples include:
• Aquatic Biota: U.S. EPA's National Ambient Water Quality Criteria
• Sediment-Associated Biota: National Oceanic and Atmospheric
Administration's (NOAA) Effects Range-Low (ER-Ls)
• Soil Invertebrates: Dutch National Institute of Public Health and Environmental
Protection's (RIVM) Ecotoxicological Intervention Values (EIVs).
The methods used to develop each of the receptor community screening factors are briefly
described here.
Aquatic Community. For aquatic biota in freshwater systems, the final chronic value
(FCV) developed for the National Ambient Water Quality Criteria were chosen as the screening
factor. If an AWQC was not available, the continuous chronic criterion (CCC) developed for the
Great Lakes Water Quality Initiative (GLWQI) was used (U.S. EPA, 1995a, 1996f). If neither of
these criteria were available, a secondary chronic value (SCV) was calculated using the Tier II
methods developed through the Great Lakes Initiative (Stephan et al., 1985; Suter and Tsao,
1996).
The SCV is calculated using methods analogous to those applied in calculating the FCV.
However, the Tier II methods (1) require chronic data on only one of the eight family
requirements, (2) use a secondary acute value (SAV) in place of the FAV, and (3) are derived
based on a statistical analysis of AWQC data conducted by Host et al. Host et al. (1991)
developed adjustment factors (AFs) depending on the number of taxonomic families that are
represented in the database. The Tier II methodology was designed to generate SCVs that are
below FCVs (for a complete data set) with a 95 percent confidence limit.
Algae and Aquatic Plants. For algae and aquatic plants, toxicological data were
available in the open literature and in data compilations such as the Toxicological Benchmarks
for Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision
(Suter and Tsao, 1996). Studies on freshwater vascular plants are seldom available; however,
toxicity data are available from standard algal tests. In order of preference, the screening factors
for algae and aquatic plants were based on either (1) a lowest observed effects concentration
(LOEC) for vascular aquatic plants or (2) an effective concentration (EC^) for a species of
freshwater algae, generally a species of green algae.
Benthic Community. Two methods were applied to develop screening factors for the
sediment community. The first and preferred method uses measured sediment concentrations
that resulted in de minimis effects to the composition and abundance of the sediment community.
The second derivation method uses the equilibrium partitioning relationship between sediments
and surface waters to predict a protective concentration for the benthic community using the
chronic FCV. A brief discussion of each method is provided below.
C-174
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March 26, 2001 Appendix C
• Screening Factors from Measured Data: The premier sources of measured
sediment toxicity data are NOAA and the Florida Department of Environmental
Protection (FDEP). These data are used by NOAA to estimate the 10th percentile
effects concentration effects range-low (ER-L) and a median effects concentration
effects range-median (ER-M) for adverse effects in the sediment community. The
FDEP sediment criteria are developed from the ER-L and ER-M values to
approximate a threshold effects level (TEL) (estimated from ER-L data). The
TELs are preferable to the ER-L primarily because they have been shown to be
analogous to TELs observed in freshwater organisms (Smith et al., 1996).
• Predicted Sediment CSCLs. If neither a TEL nor an ER-L is available for
nonionic, organic constituents, the screening factor will be calculated using the
sediment quality criteria (SQC) method (U.S. EPA, 1993b). This method assumes
that equilibrium-partitioning between the sediment and water column is a function
of the organic carbon fraction (foc) in sediment and the organic carbon partition
coefficient of the constituent. The screening factor is calculated as shown in
Equation C.6-6, assuming that the foc is equivalent to 1 percent total organic
carbon (Jones et al., 1997).
= foc X Koc X FCV (C.6-6)
Terrestrial Plant Community. For the terrestrial plant community, screening factors for
soil were derived according to the methodology presented in the Toxicological Benchmarks for
Screening Contaminants of Potential Concern for Effects on Terrestrial Plants: 1997 Revision
(Efroymson et al., 1997a). The authors derive ecologically relevant benchmarks by rank-ordering
the phytotoxicity data according to the LOECs. This analysis adopted the same approach and
selected screening factors for constituents with 10 or fewer values at the lowest LOEC. For
constituents with more than 10 LOEC values, the 10th percentile LOEC was selected. Because
the toxicity endpoints reflect endpoints such as plant growth and yield reduction, the screening
factors are presumed to be relevant to sustaining "healthy" plant communities.
Soil Community. The screening factors for soil fauna were estimated to protect species
found in a typical soil community, including earthworms, insects, and other soil fauna. Eight taxa
of soil fauna are represented to reflect the key structural (e.g., trophic elements) and functional
(e.g., decomposers) components of the soil community. The methodology presumes that
protecting 95 percent of the soil species will ensure long-term sustainability of a functioning soil
community. The toxicity data on soil fauna were gleaned from several major compendia and
supplemented with additional studies identified in the open literature. The mathematical
construct shown in Equation C.6-7 was developed by Dutch scientists (i.e., the RTVTVI
methodology) and was used to calculate screening factors at a 50th percentile level of confidence
(Sloof, 1992). For the screening factors for soil biota (SFsoil50/0), the 50th percentile level of
confidence was selected because the 95th percentile has been shown to be overly conservative
(e.g., well below background levels).
C-175
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March 26, 2001 Appendix C
SFso,i5% = \-xm ~ ki 5J (C.6-7)
where
xm = sample mean of log LOEC data
k[ = extrapolation constant for calculating one-sided leftmost confidence limit
sm = sample standard deviation of log LOEC data.
When data were insufficient to calculate screening factors using this methodology, two other
sources of screening factors were used. First, the ecotoxicological data presented on indicator
species such as earthworms were used to select a protective soil concentration (Efroymson et al.,
1997b). Second, the criteria developed by the Canadian Council of Ministers of the Environment
(CCME, 1997) for the protection of soil organisms were adopted as screening factors.
C.6.5 Screening Procedures
In most respects, the ecological risk screening procedure mirrors the methods for the risks
from noncancer constituents to human health. The salient features of the ecological risk
screening are summarized below.
C. 6.5.1 Risk Calculation. Ecological risks were estimated by selecting appropriate
screening factors and constituent concentrations for each facility and impoundment and
calculating HQs. The screening factors for the assessment were developed from the HWIR
ecological databases, as described in the previous sections. It was assumed that all sites
supported terrestrial receptors (e.g., terrestrial plants, birds, and mammals). However, surface
impoundments are not intended to support aquatic plants, aquatic invertebrates, fish, or sediment-
associated receptors; therefore, aquatic and sediment-associated biota were assessed only if a
potentially affected waterbody was identified within 2 kilometers of the surface impoundment.
Although not intended to support amphibians, birds, and mammals, surface impoundments are
likely to be attractive to these receptors (especially if impoundments support vegetation);
therefore, amphibians, birds, and mammals were assessed for all surface impoundments.
Risk was defined as the ratio between the impoundment concentration and the screening
factor, or hazard quotient. To evaluate the receptor risks from exposure to a chemical constituent
at a particular surface impoundment, Equation C.6-8 was used:
C C C
- lmp-""er nr lmPsludge nr lmP^slud^ (r , Rx
constituent ~ T - OT T - OT - - (C.6-8)
sludge soil
C-176
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March 26, 2001 Appendix C
where
Cimp water = impoundment water concentration
Cimp siudge and Cimp soil(sludge) = impoundment sludge concentration
SFwater, SFsludge, and SFsoil = corresponding ecological screening factors for each
medium.
HQ'constituent = risk to receptor i associated with that impoundment
and facility.
The HQ values for each receptor i may be summed across the entire facility in generating facility
risks because (1) the screening factors for each receptor are based on the same study data (and
endpoints) and (2) receptors may be exposed through both terrestrial and aquatic systems.
Attachment C-23 shows the results of the ecological screening assessment.
C.6.5.2 Risk Screening Methods. Risk estimates generated by the ecological screening
assessment were reported for receptors, constituents, surface impoundments, and facilities by the
following categories of interest.
Facility
• Regulatory status
Surface Impoundment
• Waste type
• Treatment type
Constituent
• Constituent type
Ecological Attributes
• Receptor group
• Habitat type.
The facility risk is defined as the maximum surface impoundment risk to receptor i for a
particular facility. Facility risk estimates are used to develop regulatory-type risk distributions.
The surface impoundment risk is defined as the cumulative risk to receptor i from exposure to all
constituents at a particular surface impoundment.
For the ecological screening assessment, the constituent risk is defined as risk to the most
sensitive receptor across all impoundments at a facility. Constituent risk estimates are used to
develop constituent-specific risk distributions.
C-177
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March 26, 2001 Appendix C
Construct Risk Distributions. Separate risk distributions were constructed from risk
estimates to evaluate categories of interest. Risk distributions consist of the following five risk
intervals (risk bin):
• >0.1andland<10
• >10and<100
• >100.
A unitary value (1), representing the constituent, surface impoundment, or facility, was
added to the appropriate risk bin. Since sample facilities represent a number of facilities
nationwide, unitary values were weighted by the facility sample weight before being added to the
bin.
The facility- and surface impoundment-related risk distributions were constructed from
risk estimates for all receptors considered at a particular surface impoundment or facility. These
risk distributions are used to screen facilities, surface impoundments, and constituents. Risk
distributions constructed from maximum risk estimates (i.e., risk estimate for the most sensitive
receptor) were compared to risk distributions for all receptors to determine if the number of
receptors affects the facility- and impoundment-level risk distributions. In addition, risk
distributions for each trophic level were developed to evaluate potential impacts on food webs.
These risk distributions for receptor groups and trophic levels provide useful metrics for the risk
characterization.
Establish Risk Criterion. A risk criterion of 1 was used to screen ecological risk
estimates. Risk estimates less than 1 (e.g., HQ1 < 1) indicate a negligible potential for adverse
ecological impacts. Alternatively, risk estimates of 1 or greater indicate a potential for adverse
ecological effects. Surface impoundments and facilities with risk estimates of 1 or greater may
be assigned for further evaluation, depending on the results of the human health screening.
Conduct Risk Screening. The ecological risk screening process is very similar to the
health risk decision process. However, there are distinct differences in the ecological risk
screening procedure. Whereas the human health risk screening is intended to protect
individuals, the ecological risk screening is intended to protect species populations and
communities from adverse effects. In addition, the ecological risk screening does not include
cancer effects; only the endpoints described under Section C.6.1 were considered.
Based on the results of the surface impoundment pilot study, it was anticipated that, for
each facility, at least one constituent would exceed the ecological risk criterion for the terrestrial
plant receptor group. Because impoundment sludge/soils are not intended to support terrestrial
habitats and because the screening factors for terrestrial plants are based on a data set that does
not reflect adaptation by plant communities, EPA determined that a simple exceedance of the
plant screening factor does not provide an adequate basis to determine the potential for adverse
ecological effects. Thus, if plants are the only receptors with an HQ of 1 or higher, the
C-178
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March 26, 2001 Appendix C
constituent, impoundment, or facility proceeds to further analysis only if the HQ for plants
exceeds 10 (indicating a greater potential for adverse effects than a simple exceedance).
C. 6.6 Screening Results
Ecological risk was calculated in a manner similar to that used to estimate noncancer
risks for humans. Chemical concentrations that are assumed to be protective of wildlife and
plants were established based on toxicological data. These protective concentrations are referred
to as screening factors. Individual screening factors were developed for each of 62 receptors for
35 chemicals. The screening factors and the reported chemical concentrations in surface
impoundments were used to calculate hazard quotients for each chemical and each receptor at
each impoundment at each facility. HQs were calculated by dividing the chemical concentration
in the impoundment by the receptor's screening factor.
Results by Facility. A total of 108 facilities out of 133 exceeded the ecological risk
criterion for at least one receptor. Table C.6-4 shows a summary of the screening results by
facility. Forty-six facilities had exceedances at three or more impoundments, 24 facilities had
exceedances at two impoundments, and 38 facilities had exceedances at only one impoundment.
Results by Chemical. A total of 34 chemicals exceeded the risk criterion for at least one
receptor at one impoundment. Table C.6-5 shows how frequently each chemical had the highest
HQ for a particular impoundment. These chemicals are referred to as the "risk drivers" for that
impoundment.
Results by Receptor. The screening ecological assessment addressed 62 receptors,
including several species of mammals, birds, and amphibians as well as several ecological
communities (e.g., the soil community and the sediment community). (See Attachment C-19 for
a list of receptor species.) Based on the screening results, 54 receptors exceeded the risk criterion
at at least 1 impoundment. One receptor, the Great Basin pocket mouse inhabits a relatively
limited geographic area in the northwestern United States; no SI facilities fell within its
geographic range, and, therefore, no exceedances occurred for this receptor. Table C.6-6 shows
the receptors that exceeded the risk criterion.
The receptors that exceeded the risk criterion include all of the community receptors
assessed as well as representative mammals and birds at all level of the food chain. Furthermore,
receptors that depend on aquatic systems for food (e.g., mink, river otter, kingfisher, great blue
heron) as well as those that depend on terrestrial systems (e.g., terrestrial plants, coyote, white
tailed deer, and cerulean warbler) exceeded the risk criterion. HQs greater than 1 also occurred
for receptors in all three habitat types—terrestrial, wetland, and aquatic, indicating that potential
ecological risks are not restricted to any single type of habitat.
Sensitive Ecosystems. The presence of managed areas was assessed for 133 sites; 21
sites had managed areas within 3 km. Considering only the 108 sites that exceeded the risk
criterion (i.e., had at least one HQ greater than 1), 18 facilities are within 3 km of a managed
area. Twenty seven of the 108 facilities are within 1 km of wetlands. Three facilities are both
C-179
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March 26, 2001 Appendix C
within 3 km of a managed area and within 1 km of a wetland. Table C.6-7 summarizes the
proximity to sensitive habitats for facilities with exceedances.
C-180
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March 26, 2001
Appendix C
Table C.6-4. Summary of Risk Criterion Exceedances by Facility
Facility
1
4
5
7
11
12
14
18
19
22
28
29
32
33
35
36
38
41
44
45
46
50
57
64
68
71
78
80
82
Number of Impoundments
Lower
Concern
1
1
2
1
6
1
4
1
4
2
6
1
1
Potential
Concern
1
1
1
1
1
3
1
2
3
2
1
1
4
1
2
9
1
10
1
11
3
1
2
1
7
1
2
5
1
Number of Constituents
Lower
Concern
5
6
8
6
1
19
10
10
20
3
11
14
4
5
6
4
7
6
11
19
13
1
1
13
3
2
7
3
Potential
Concern
2
2
1
2
2
6
1
1
3
4
3
1
3
1
8
1
5
1
14
8
1
1
11
2
1
11
1
(continued)
C-181
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March 26, 2001
Appendix C
Table C.6-4 (Continued)
Facility
84
86
96
98
103
104
115
116
120
126
127
133
135
140
144
156
157
160
164
172
173
176
180
182
2
6
8
13
21
Number of Impoundments
Lower
Concern
1
1
1
4
3
1
1
1
5
1
8
7
4
7
2
2
2
Potential
Concern
5
3
1
2
6
2
2
1
1
2
6
1
5
1
1
8
2
1
3
2
3
1
2
3
Number of Constituents
Lower
Concern
15
7
1
14
8
15
14
2
2
12
4
3
8
2
2
8
16
10
1
5
5
6
1
6
3
2
2
6
Potential
Concern
11
5
2
3
8
2
3
1
1
4
6
2
9
1
3
1
1
9
2
2
1
6
2
2
5
(continued)
C-182
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March 26, 2001
Appendix C
Table C.6-4 (Continued)
Facility
23
31
40
43
47
48
49
51
52
54
55
58
63
65
67
70
74
81
85
89
90
91
97
105
107
111
112
118
122
Number of Impoundments
Lower
Concern
4
2
1
1
6
1
1
5
1
4
1
3
1
2
2
2
1
10
2
5
1
9
1
2
1
2
1
9
1
Potential
Concern
Number of Constituents
Lower
Concern
7
17
9
21
12
4
3
1
7
1
3
10
1
4
6
4
1
4
8
3
5
11
7
5
4
1
2
6
2
Potential
Concern
6
4
1
1
2
1
6
11
(continued)
C-183
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March 26, 2001
Appendix C
Table C.6-4 (Continued)
Facility
132
134
137
141
145
148
149
151
153
155
159
167
170
175
177
181
183
185
186
187
193
Number of Impoundments
Lower
Concern
1
1
1
1
1
1
1
23
1
3
6
1
2
3
2
2
1
9
1
15
3
Potential
Concern
Number of Constituents
Lower
Concern
2
1
4
2
3
1
4
7
1
11
11
1
6
17
1
5
2
2
5
5
1
Potential
Concern
2
5
1
4
2
5
C-184
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March 26, 2001
Appendix C
Table C.6-5. Frequency That Constituent Has the Maximum HQ Value Exceeding
a Risk Criterion at an Impoundment
Constituent of Concern
Toluene
Phenol
Bis(2-ethylhexyl) phthalate [dioctyl phthalate]
2,3,7,8-TCDD [2,3,7,8-Tetrachlorodibenzo-p-dioxin]
Chromium VI [hexavalent chromium]
Benzo(a)pyrene
Dibenz [a,h] anthracene
Chloroform [trichloromethane]
Benzene
Methoxychlor
Lead
Mercury
Nickel
Silver
Thallium
Arsenic
Barium
Beryllium
Cadmium
Vanadium
Zinc
Carbon disulfide
Selenium
Pentachlorophenol [PCP1
Number of Impoundments
where Constituent Is Max HQ
8
20
6
18
1
9
27
6
3
1
107
10
18
3
3
49
37
6
2
4
35
8
5
1
C-185
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March 26, 2001
Appendix C
Table C.6-6. Receptors with HQ >1
Trophic Level
Communities
Communities
Communities
Producers
Producers
Tl
Tl
Tl
Tl
Tl
Tl
Tl
Tl
Tl
Tl
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
Species Common Name
Aquatic Community
Sediment Community
Soil Community
Aquatic Plants
Terrestrial Plants
Beaver
Black-Tailed Jackrabbit
Canada Goose
Eastern Cottontail
Meadow Vole
Mule Deer
Muskrat
Pine Vole
Prairie Vole
White-tailed Deer
American Kestrel
American Robin
American Woodcock
Belted Kingfisher
Bullfrog
Burrowing Owl
Cerulean Warbler
Deer Mouse
Eastern Newt
Flatwoods Salamander
Gopher Frog
Great Blue Heron
Green Frog
Green Heron
Herring Gull
Least Weasel
Lesser Scaup
Little Brown Bat
Loggerhead Shrike
Long-Tailed Weasel
Number of Exceedances
1306
1481
732
565
299
799
97
614
489
280
49
694
340
142
605
779
797
788
869
366
229
354
280
519
197
192
791
445
872
934
71
742
554
721
554
(continued)
C-186
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March 26, 2001
Appendix C
Table C.6-1. (Continued)
Trophic Level
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T2
T3
T3
T3
T3
T3
T3
T3
T3
Species Common Name
Mallard Duck
Marsh Wren
Mink
Northern Bob white
Raccoon
River Otter
Short-Tailed Shrew
Short-Tailed Weasel
Spotted Sandpiper
Tree Swallow
Western Meadowlark
Bald Eagle
Black Bear
Cooper's Hawk
Coyote
Kit Fox
Osprey
Red Fox
Red-Tailed Hawk
Number of Exceedances
975
602
992
616
1057
847
399
69
1104
944
245
896
616
578
717
51
536
635
614
C-187
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March 26, 2001
Appendix C
Table C.6-7. Facilities That Have Exceedances and Are Near Sensitive Habitats
Facility
1
2
4
5
6
7
8
11
12
13
14
18
19
21
22
23
28
29
31
32
33
35
36
38
40
41
43
44
45
46
Wetlands Within
1km
No
No
Yes
No
No
No
Yes
No
No
No
No
No
No
Yes
No
No
No
No
Yes
No
No
No
No
Yes
No
No
No
Yes
Yes
Yes
Managed Area Within
3 km
No
No
No
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
Yes
No
No
No
No
No
Wetland Within 1 km and
Managed Area Within 3 km
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
(continued)
C-188
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March 26, 2001
Appendix C
Table C.6-7. (Continued)
Facility
47
48
49
50
51
52
54
55
57
58
63
64
65
67
68
70
71
74
78
80
81
82
84
85
86
89
90
91
96
Wetlands Within
1km
No
No
Yes
No
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
Yes
No
No
No
No
No
No
Managed Area Within
3 km
Yes
Yes
No
No
Yes
No
No
No
No
No
No
No
Yes
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
Wetland Within 1 km and
Managed Area Within 3 km
No
No
No
No
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
(continued)
C-189
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March 26, 2001
Appendix C
Table C.6-7. (Continued)
Facility
97
98
103
104
105
107
111
112
115
116
118
120
122
126
127
132
133
134
135
137
140
141
144
145
148
149
151
153
155
Wetlands Within
1km
No
No
Yes
Yes
Yes
Yes
No
No
No
No
Yes
No
No
Yes
No
No
No
Yes
No
No
No
No
No
No
No
Yes
Yes
No
Yes
Managed Area Within
3 km
Yes
Yes
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
Yes
Yes
No
Yes
No
No
No
No
No
No
No
Wetland Within 1 km and
Managed Area Within 3 km
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
(continued)
C-190
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March 26, 2001
Appendix C
Table C.6-7. (Continued)
Facility
156
157
159
160
164
167
170
172
173
175
176
177
180
181
182
183
185
186
187
193
Wetlands Within
1km
Yes
No
No
Yes
No
No
No
No
No
No
Yes
No
No
No
Yes
No
No
No
No
Yes
Managed Area Within
3 km
No
No
Yes
No
No
No
No
No
No
No
Yes
No
No
No
No
Yes
No
No
No
No
Wetland Within 1 km and
Managed Area Within 3 km
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
No
No
no
C-191
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March 26, 2001 Appendix C
C.I References
Agency for Toxic Substances and Disease Registry (ATSDR). 1997. Toxicological Profiles. On
CD-ROM. CRC press. U.S. Public Health Service. Atlanta, GA.
Bear, J., 1979. Hydraulics of Groundwater. New York: McGrawHill.
Bonaparte, R., J.P. Giroud, B.A. Gross. 1989. Rates of Leakage Through Landfill Liners,
Conference Proceedings, Volume I. Geosynthetics'89 Conference, San Diego,
California, February 23, 1989.
Carsel, R.F., and R.S. Parrish. 1988. Developing joint probability distributions of soil water
retention characteristics. Water Resour. Res. 29:755-770.
Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. Characterizing the
uncertainty of pesticide leaching in agricultural soils. Journal of Contaminant Hydrology,
2:111-124.
CCME (Canadian Council of Ministers of the Environment). 1997. Recommended Canadian
Soil Quality Guidelines. Science Policy and Environmental Quality Branch, Ecosystem
Science Directorate, Environment Canada, Ottawa, Ontario. (ISBN 1-895-925-92-4).
Devillers, J. and J.M. Exbrayat. 1992. Ecotoxicity of Chemicals to Amphibians. Grodon and
Breach Science Publishers. Philadelphia, PA.
Efroymson, R.A., M.E. Will, G.W. Suter, and A.C. Wooten. 1997a. Toxicological Benchmarks
for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants: 1997
Revision. ES/ER/TM-85/R3. Oak Ridge National Laboratory, Oak Ridge, TN.
Efroymson, R.A., M.E. Will, and G.W. Suter. 1997b. Toxicological Benchmarks for
Contaminants of Potential Concern for Effects on Soil and Litter Invertebrates and
Heterotrophic Process: 1997Revision. ES/ER/TM-126/R2. Oak Ridge National
Laboratory, Oak Ridge, TN.
Eisler, R. 1985-1993. Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review. U.S.
Fish and Wildlife Service Biological Reports.
Freeze, R.A., and J. Cherry, 1979. Groundwater. Englewood Cliffs, NJ: Prentice-Hall.
Gelhar, L.W., C. Welty, K.R. Rehfeldt, 1992. A critical review of data on field-scale dispersion
in aquifers. Water Resour. Res., 28(7), 1955-1974.
Host, G. E., R. R. Regal, and C. E. Stephan. 1991. Analyses of Acute and Chronic Data for
Aquatic Life. Draft. U.S. Environmental Protection Agency, Office of Research and
Development, Office of Environmental Processes and Effects Research, Washington, DC.
January 4.
C-192
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Hudson, R.H., R.K. Tucker, and M.A. Haegele. 1984. Handbook ofToxicity of Pesticides to
Wildlife. U.S. Fish and Wildlife Service. Resour. Publ. 153. 90 pp.
Kollig, H.P., J.J. Ellington, E.J. Weber, and N.L. Wolfe. 1993. Pathway Analysis of Chemical
Hydrolysis for 14 RCRA Chemicals. U.S. EPA Environmental Research Brief.
EPA/600/M-89/009. Washington, DC: U.S. Government Printing Office.
Long, E.R., and L. G. Morgan. 1991. The Potential for Biological Effects of Sediment-Sorbed
Contaminants Tested in the National Status and Trends Program. NOAA Technical
Memorandum. National Oceanic and Atmospheric Administration (NOAA).
Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt. 1990. Handbook of Chemical Property
Estimation Methods: Environmental Behavior of Organic Compounds. American
Chemical Society, Washington, DC.
Jones, D.S., G.W. Suter, II, and R.N. Hull. 1997. Toxicological Benchmarks for Screening
Contaminants of Potential Concern for Effects on Sediment-Associated Biota: 1997
Revision. ES/ER/TM-95/R4. Oak Ridge National Laboratory, Oak Ridge, TN.
MacDonald, D.D. 1994. Approach to the Assessment of Sediment Quality in Florida Coastal
Waters. Volume 1: Development and Evaluation of Sediment Quality Assessment
Guidelines. Report prepared for Florida Department of Environmental Protection,
Tallahassee, FL.
Mineau, P., B.T. Collins, and A. Baril. 1996. On the use of scaling factors to improve
interspecies extrapolation of acute toxicity in birds. Regul. Toxicol. andPharmacol.
24:24-29.
Newell, C.J., L.P. Hopkins, and P.B. Bedient. 1989. Hydrogeologic Database for Ground
Water Modeling. API Publication No. 4476. Prepared for American Petroleum Institute.
Prepared by Rice University, Department of Environmental Science and Engineering,
Washington, DC. February.
Newell, C. J., L. P. Hopkins, and P. B. Bedient. 1990. A hydrogeologic data base for
groundwater modeling. Ground Water 28(5):703-714.
Peterle, TJ. 1991. Wildlife Toxicology. New York: Van Nostrand Reinhold.
Power, T., K.L. Clark, A. Harfenist, and D.B. Peakall. 1989. A Review and Evaluation of the
Amphibian Toxicological Literature. Technical Report Series No. 61. Canadian Wildlife
Service, Environment Canada, Hull, Quebec.
Sample, B.E., D.M. Opresko, and G.W. Suter, U. 1996. Toxicological Benchmarks for Wildlife:
1996 Revision. ES/ER/TM-86/R3. Oak Ridge National Laboratory, Oak Ridge, TN.
C-193
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Sample, B.E., JJ.Beauchamp, R.A.Efroymson, G.W.Suter, n, and T.L.Ashwood. 1998a.
Development and Validation of Bioaccumulation Models for Earthworms. ES/ER/TM-
220. Prepared for Office of Environmental Management, U.S. Department of Energy.
Prepared by Oak Ridge National Laboratory, Oak Ridge, TN. February.
Sample, B.E., JJ.Beauchamp, R.A.Efroymson, and G.W.Suter, II. 1998b. Development and
Validation of Bioaccumulation Models for Small Mammals. ES/ER/TM-219. Prepared for
Office of Environmental Management, U.S. Department of Energy. Prepared by Oak
Ridge National Laboratory, Oak Ridge, TN. February.
Sloof, W. 1992. Ecotoxicological Effect Assessment: Deriving Maximum Tolerable
Concentrations (MTC)from Single Species Toxicity Data. Guidance Document. Report
No. 719102.018. National Institute of Public Health and Environmental Protection
(RIVM), Hilversum, the Netherlands.
Smith, S.L., D.D. MacDonald, K.A. Keenleyside, C.G. Ingersoll, and L.J. Field. 1996. A
preliminary evaluation of sediment quality assessment values for freshwater ecosystems.
J. Great Lakes Res. 22(3):624-638.
Stephan, C.E., D.I. Mount, DJ. Hansen, J.H. Gentile, G.A. Chapman, and W.A. Brungs. 1985.
Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of
Aquatic Organisms and Their Uses. PB85-227049. National Technical Information
Service, Springfield, VA.
Suter, G.W., II. 1993. Ecological Risk Assessment. Chelsea, MI: Lewis Publishers.
Suter, G.W. U, and C.L. Tsao. 1996. Toxicological Benchmarks for Screening Potential
Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision. ES/ER/TM-
96/R2. Prepared for the U.S. Department of Energy, Washington, DC.
U.S. ACE (Army Corps of Engineers). 1996. Risk Assessment Handbook. Volume II.
Environmental Evaluation. Engineering and Design. Washington, DC.
U.S. Department of the Air Force. 1997. Guidance for Contract Deliverables. Appendix D:
Risk Assessment Methods. Air Force Center for Environmental excellence, Technical
Services Quality Assurance Program, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1989a. Ambient Water Quality Criteria
Document: Addendum for Antimony (Draft Report [Final]). Cincinnati, OH.
U.S. EPA (Environmental Protection Agency). 1989b. Risk Assessment Guidance for
Superfund. Human Health Evaluation Manual Part A. EPA/540-1-89/002. Washington,
DC: U.S. Government Printing Office.
C-194
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March 26, 2001 Appendix C
U.S. EPA (Environmental Protection Agency). 1990. Background Document for EPA 's
Composite Model for Landfills (EPACML). Office of Solid Waste, Washington, DC.
February.
U.S. EPA (Environmental Protection Agency). 1993a. Technical Basis for Deriving Sediment
Quality Criteria for Nonionic Organic Contaminants for the Protection ofBenthic
Organisms by Using Equilibrium Partitioning. EPA-822-R-93-011. Office of Water,
Washington, DC.
U. S. EPA (Environmental Protection Agency). 1993b. Wildlife Exposure Factors Handbook:
Volumes I andII. EPA/600/R-93/187a,b. Office of Research and Development.
Washington, DC: U.S. Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1994a. The Hydrologic Evaluation of Landfill
Performance (HELP) Model. User's Guide for Version 3. Office of Research and
Development, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1994b. The Hydrologic Evaluation of Landfill
Performance (HELP) Model. Engineering Documentation for Version 3. Office of
Research and Development, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1994c. The U.S. EPA Reach File Version 3.0
Alpha Release (RF3-Alpha) Technical Reference. 1st edition. Office of Wetlands,
Oceans, and Watersheds, Office of Water, Washington, DC. Available online at
http: //www. epa. gov/owowwtr 1 /NP S/rf/techref. html
U.S. EPA (Environmental Protection Agency). 1994d. 1:250,000 Scale Quadrangles of
Landuse/Landcover GIRAS Spatial Data in the United States. Office of Information
Resources Management, Washington, DC. Available online at
http://www.epa.gov/ngispgm3/nsdi/projects/giras.htm.
U.S. EPA (Environmental Protection Agency). 1995a. Great Lakes Water Quality Initiative
Criteria Documents for the Protection of Aquatic Life in Ambient Water. EPA-820-B-95-
004. Office of Water, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1995b. Hazardous waste management system:
identification and listing of hazardous waste-Hazardous Waste Identification Rule
(HWIR). 60 Federal Register 66344.
U.S. EPA (Environmental Protection Agency). 1996a. Database for "Better Assessment Science
Integrating Point and Nonpoint Sources. "EPA-823-R-96-001. Washington, DC: U.S.
Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1996b. Amphibian Toxicity Data for Water
Quality Criteria Chemicals. EPA/600/R-96/124. Washington, DC: U.S. Government
Printing Office.
C-195
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March 26, 2001 Appendix C
U.S. EPA (Environmental Protection Agency). 1996c. EPA 's Composite Model for Leachate
Migration with Transformation Products, EPACMTP. Background Document for the
Finite Source Methodology. Office of Solid Waste, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1996d. EPACMTP Sensitivity Analysis. Office
of Solid Waste, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1996e. EPA 's Composite Model for Leachate
Migration with Transformation Products, EPACMTP. Background Document. Office of
Solid Waste, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1996f 7995 Updates: Water Quality Criteria
Documents for the Protection of Aquatic Life in Ambient Water. EPA-820-B-96-001.
Washington, DC: U.S. Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1997a. AQUIRE Database. Environmental
Research Laboratory, Office of Research and Development, Duluth, MN.
U.S. EPA (Environmental Protection Agency). 1997b. EPA 's Composite Model for Leachate
Migration with Transformation Products, EPACMTP. User's Guide. Office of Solid
Waste, Washington, DC.
U. S. EPA (Environmental Protection Agency). 1997c. Exposure Factors Handbook. Volume I -
General Factors. EPA/600/P-95/002Fa. Washington, DC: U.S. Government Printing
Office.
U. S. EPA (Environmental Protection Agency). 1997d. Exposure Factors Handbook. Volume II -
FoodIngestion Factors. EPA/600/P-95/002Fa. Washington, DC: U.S. Government
Printing Office.
U. S. EPA (Environmental Protection Agency). 1997e. Exposure Factors Handbook. Volume III -
Activity Factors. EPA/600/P-95/002Fa. Washington, DC: U.S. Government Printing
Office.
U.S. EPA (Environmental Protection Agency). 1997f. PHYTOTOX Database. Office of
Research and Development, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1997'g. Supplemental Background Document;
Nongroundwater Pathway Risk Assessment; Petroleum Process Waste Listing
Determination. 68-W6-0053. Office of Solid Waste, Washington, DC. March 20.
U.S. EPA (Environmental Protection Agency). 1997h. Health Effects Assessment Summary
Tables (HEAST), FY 1997 Update. EPA-540-R-97-036. Washington, DC:
U.S. Government Printing Office.
C-196
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March 26, 2001 Appendix C
U.S. EPA (Environmental Protection Agency). 1998a. Guidelines for Ecological Risk
Assessment. EPA/630/R-95/002F. Washington, DC: U.S. Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1998b. Industrial Waste Air Model Technical
Background Document. EPA 530-R-99-004. Washington, DC: U.S. Government
Printing Office.
U.S. EPA (Environmental Protection Agency). 1998c. National Water Quality Inventory: 1996
Report to Congress. EPA841-R-97-008. Washington, DC: U.S. Government Printing
Office.
U.S. EPA (Environmental Protection Agency). 1998d. State Soil Geographic (STATSGO)
Database for CONUS, Alaska, and Hawaii in BASINS. U.S. Environmental Protection
Agency, Washington, DC.
U.S. EPA (Environmental Protection Agency). 1999a. Source Module for Tanks and Surface
Impoundments. Background and Implementation for the Multimedia, Mulitpathway, and
Mulitreceptor Risk Assessment (3MRA)for HWIR99. Office of Solid Waste, Washington,
DC.
U.S. EPA (Environmental Protection Agency). 1999b. Technical Background Document:
Industrial Waste Management to Support the Guide for Industrial Waste Management.
EPA530-R-99-002. Washington, DC: U.S. Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1999c. User's Guide for the Industrial Waste
Management Evaluation Model (IWEM): Tier 1 Look-up Tables and Tier 2 Neural
Networks. EPA530-R-99-003. Washington, DC: U.S. Government Printing Office.
U.S. EPA (Environmental Protection Agency). 1999d. Data Collection for the Hazardous Waste
Identification Rules: Section 12.0 Ecological Exposure Factors. Office of Solid Waste,
Washington, DC.
U.S. EPA (Environmental Protection Agency). 2000a. Proceedings of the Ground-
Water/Surface-Water Interactions Workshop. EPA/542/R-00/007. Washington, DC: U.S.
Government Printing Office.
U.S. EPA (Environmental Protection Agency). 2000b. Risk Assessment for the Listing
Determinations for Inorganic Chemical Manufacturing Wastes: Background Document.
Office of Solid Waste, Washington, DC.
U.S. EPA (Environmental Protection Agency). 2000c. Surface Impoundment Study Technical
Plan for the Human Health and Ecological Risk Assessment. Office of Solid Waste,
Washington, DC.
C-197
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March 26, 2001 Appendix C
U.S. EPA (Environmental Protection Agency). 2000d. Options for Development of Parametric
Probability Distributions for Exposure Factors. EPA/600/R-00/058. National Center for
Environmental Assessment, Office of Research and Development, Washington, DC.
July.
U.S. EPA (Environmental Protection Agency). 2000e. Testing Document for EPACMTP Code
Modifications Implemented for the Inorganics and Paints Listing Determinations. Office
of Solid Waste, Washington, DC.
U.S. EPA (Environmental Protection Agency). 2000f Integrated Risk Information System
(IRIS)—online. Duluth, MN. Available at http://www.epa.gov/iris/
U.S. FWS (Fish and Wildlife Service). 1998. National Wetlands Inventory (NWI) Metadata.
St. Petersburg, FL. Available online at ftp://www.nwi.fws.gov/metadata/nwi_meta.txt.
USGS (U.S. Geological Survey). 1985. National water summary 1984. Hydrologic events,
selected water-quality trends, and ground-water resources. In: U.S. Geologic Survey
Water-Supply Paper 2275. pp. 229-235, 297-402. United States Geological Survey,
Washington, DC.
Van derLeeden, F., F.L. Troise, andD.K. Todd. 1990. The Water Encyclopedia. 2nd Edition.
Chelsea, Michigan: Lewis Publishers.
C-198
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Appendix D
Regulatory/Program Coverage and
Gaps Analysis
-------
-------
Appendix D Program Coverage
Section D-l
Summary of State Regulations and Programs Covering
Nonhazardous Industrial Waste Surface Impoundments1
1 The EPA's analysis of state waste regulations and programs in this appendix is based on publicly
available information rather than a survey of state regulators. Therefore, the analysis may not have identified all
state waste regulations and programs that address nonhazardous waste industrial surface impoundments. Readers
should consult state regulatory agencies for more detailed and up-to-date information.
-------
Appendix D Program Coverage
Contents
State Page
Alabama D-7
Alaska D-9
Arkansas D-10
Arizona D-12
California D-14
Colorado D-19
Connecticut D-21
Delaware D-23
Florida D-25
Georgia D-27
Hawaii D-29
Idaho D-31
Illinois D-32
Indiana D-34
Iowa D-36
Kansas D-38
Kentucky D-40
Louisiana D-42
Maine D-45
Maryland D-47
Massachusetts D-49
Michigan D-50
EM
-------
Appendix D Program Coverage
Contents (continued)
State Page
Minnesota D-52
Mississippi D-54
Missouri D-56
Montana D-58
Nebraska D-60
Nevada D-62
New Hampshire D-64
New Jersey D-66
New Mexico D-68
New York D-70
North Carolina D-73
North Dakota D-75
Ohio D-77
Oklahoma D-79
Oregon D-81
Pennsylvania D-84
Rhode Island D-86
South Carolina D-87
South Dakota D-88
Tennessee D-90
Texas D-92
Utah D-94
-------
Appendix D Program Coverage
Contents (continued)
State Page
Vermont D-96
Virginia D-98
Washington D-99
West Virginia D-104
Wisconsin D-106
Wyoming D-108
D-6
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Appendix D
Program Coverage
Alabama
In Alabama, responsibility for regulating and permitting surface impoundments is
consolidated in the state's water program under the Alabama Department of Environmental
Management (ADEM). Surface impoundments for the management of nonhazardous waste are
required to obtain a state NPDES permit and are subject to non-regulatory state guidelines as
indicated in the chart below.
ADEM guidelines call for the permit applicant to submit a description of the proposed
impoundment, signed by a Registered Engineer, that includes the following information:
Proposed use of the impoundment, including a description of the liquids to be
introduced into the impoundment
• Impoundment configuration and orientation
• Plot and plan drawings of the impoundment
• Proposed liner material and thickness
• Soil boring logs for the impoundment site or other information concerning the site
geology.
Alabama Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting Standards
Design Criteria (liner, leachate collection)
Operating Criteria
Monitoring
Reporting and Recordkeeping
Inspection and Enforcement
Performance Standards and Corrective
Action
Closure/Postclosure Care
Financial Assurance
Program or Regulation
Addresses Criteria?
Yes (guidance only)
Yes (guidance only)
Yes (guidance only)
Yes (guidance only)
No
No
Yes (guidance only)
Yes (guidance only)
No
Description of Regulation or
Program
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-7
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Appendix D
Program Coverage
Alabama Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission Controls, Operating
Requirements, and Recordkeeping
Requirements
Program or Regulation
Addresses Criteria?
No
Description of Regulation or
Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Sources:
Alabama Administrative Code (AAC).
Alabama Department of Environmental Management (ADEM) web page (http://www.adem.state.al.US).
ADEM. 2000. Closure Guidelines For Industrial Wastewater Impoundments. Water Division - Industrial Section.
Revised 03/00.
ADEM. 2000. Construction Guidelines for Industrial Surface Impoundments, Water Division - Industrial Section.
Revised 03/00.
D-8
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Appendix D
Program Coverage
Alaska
Alaska does not have any regulations or programs applicable to nonhazardous waste
surface impoundments - there are not even state NPDES regulations that apply since Alaska is
not an NPDES-authorized state.
Alaska Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
No
No
No
No
No
No
No
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Alaska Statutes and Alaska Administrative Code.
D-9
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Appendix D
Program Coverage
Arkansas
Arkansas requires a state NPDES permit for discharges to surface water, but does not
further regulate surface impoundments, except for a few design and operating requirements for
surface impoundments for confined animal feeding operations (CAFOs) and oil drilling
activities. The requirements for the latter are included in the table below.
Arkansas Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
No
Yes
Yes
No
No
Yes
No
No
No
Description of Regulation or Program
Not specified in state regulations.
Regarding oil drilling activities, surface disposal of salt water and
other liquid waste sin earthen pits must be underlaid by tight soil such
as heavy clay or hardpan, or lined with asphalt or other water-tight
material and of sufficient size to assure adequate disposal of the
volume of waste to be impoundment therein. Where the soil under an
underground pit is porous and closely underlaid by gravel or sand
stratum, impounding of salt water or other liquid wastes therein will
not be allowed.
Regarding oil drilling activities, surface impoundments must have
minimum freeboard of at least 12 inches.
Not specified in state regulations.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-10
-------
Appendix D
Program Coverage
Arkansas Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Source:
Arkansas Water Division Regulations No. 1, No. 5, and No. 6.
D-ll
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Appendix D
Program Coverage
Arizona
In Arizona, responsibility for regulating and permitting surface impoundments is
consolidated in the state's water pollution control division of the Arizona Department of
Environmental Quality (ADEQ). Surface impoundments discharging to waters of the United
States must obtain an NPDES permit from USEPA.
ADEQ requires an aquifer protection permit for the construction of a surface
impoundment. The maximum duration of the permit extends through the end of the postclosure
period. All permit applications must contain two copies of a location map; two copies of a site
plan; two copies of facility design drawings; a characterization of discharge; a demonstration of
Best Available Demonstrated Control Technologies (BDACT); demonstration of compliance
with standards; demonstration of technical capability; demonstration of financial capability; past
environmental performance; and evidence that the facility complies with applicable municipal or
county zoning ordinance and regulations.
Arizona Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Program or
Regulation
Addresses
Criteria?
No
No
No
Case-by-case
Yes
Yes
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Groundwater: The state agency may require a hydrologic study on a
case-by-case basis. Monitoring requirements are determined on a
permit-specific basis.
State regulations require a facility to maintain records for monitoring
(10 years) and notification of any violations of permit conditions.
Other reporting and recordkeeping requirements are determined on a
permit-specific basis.
State regulations give the authority to inspect, but do not specify the
frequency.
(continued)
D-12
-------
Appendix D
Program Coverage
Arizona Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
No
Description of Regulation or Program
The Aquifer Protection permit establishes the point of compliance on a
site-specific basis, not farther than the property line or 750 feet from
the waste boundary. The Permit also establishes alert levels for
appropriate constituents. A notification is required if alert levels are
exceeded or if there is a reasonable expectation that state groundwater
standards may be exceeded. A contingency plan is required detailing
site-specific conditions for response actions. This may include
verification sampling, additional monitoring, assessment of impacts,
and/or corrective action.
Closure and postclosure plans are required by the state regulations.
The specific requirements, including postclosure duration, are
determined on a permit-specific basis.
For closure and postclosure, a bond, insurance, or trust fund is
required.
Not specified in state regulations
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Arizona Administrative Code (ACC) Title 18-9-1.
Arizona Department of Environmental Quality(ADEQ) web page (http://www.adeq.state.az.us/).
D-13
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Appendix D
Program Coverage
California
California has consolidated all of its environmental agencies under the California EPA
(Cal EPA); however, each board remains autonomous under the Cal EPA as do the Regional
Boards. The California Integrated Waste Management Board (CIWMB) is responsible for
regulating solid waste and solid waste management facilities, except surface impoundments. The
State Water Resources Control Board (SWRCB) regulates and governs the design, operation, and
maintenance of surface impoundments in the California Water Regulations. Regional Water
Quality Control Boards implement the NPDES and state waste management programs.
California is authorized to implement the federal Clean Water Act (CWA) NPDES
program. Any owner/operator of a surface impoundment subject to NPDES requirements must
submit a federal NPDES permit application, which is channeled to the Regional board and
receives approval from the SWRCB and USEPA Region. California has also developed a
general NPDES permit. California has waste discharge requirements (WDRs) that regulates
discharges of waste to land.
California Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Program or
Regulation
Addresses
Criteria?
Yes
Description of Regulation or Program
New and existing surface impoundments must be a minimum distance
of 5 feet above the highest anticipated elevation of underlying
groundwater. All engineered structures constituting any portion of a
surface impoundment must be capable of providing support and
capable of withstanding hydraulic pressure gradients to prevent failure
due to settlement, compression, or uplift and all effects of ground
motion resulting from the maximum probable earthquake and provide
adequate foundations or support for the waste management unit.
New and existing Class II surface impoundments must comply with
flooding, tidal wave, seismic design, and rapid geologic change (e.g.,
earthquake) requirements. New Class II units and expansions of
existing Class II units must not be located within 200 feet of a
Holocene fault.
Materials used in containment structures must comply with specific
permeability requirements.
(continued)
D-14
-------
Appendix D
Program Coverage
California Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Design Criteria (liner,
leachate collection)
Operating Criteria
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Description of Regulation or Program
New surface impoundments must comply with stringent liner
requirements. Existing surface impoundments must be lined and fitted
with subsurface barriers as needed and feasible. Synthetic liners are
not required for surface impoundments, but if used must be inspected
weekly. New surface impoundments must comply with stringent
leachate collection and removal system requirements. Existing surface
impoundments must be fitted with leachate collection and removal
systems as feasible.
Specific mandatory precipitation and drainage control requirements
exist for surface impoundments. Surface impoundments must have
sufficient freeboard to accommodate seasonal precipitation, but in no
case less than two feet and designed and constructed to prevent
overtopping as a result of wind conditions likely to accompany such
precipitation, except where potential overflows would be to exterior
surface impoundments. In addition, no discharges from surface
impoundments are allowed except as authorized by waste discharge
requirements.
Slope requirements, especially in drier areas of the state, are
incorporated on a site-specific basis through WDRs.
The General Storm Water Permit Application requires development
and implementation of Storm Water Pollution Prevention Plans.
These plans must contain over ten specific elements, such as practices
to reduce pollutants, elimination of non-storm water discharges, and
spill prevention and response procedures.
(continued)
D-15
-------
Appendix D
Program Coverage
California Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Description of Regulation or Program
Groundwater: At a minimum, monitoring must occur quarterly.
Regional boards must also establish a water quality protection
standard containing a list of constituents of concern, concentration
limits, and points of compliance. Monitoring must consist of a
sufficient number of wells, installed at appropriate locations and
depths to yield groundwater samples that indicate leakage from a
waste management unit; represent the backgroundwater quality; and
represent the quality of groundwater passing the points of compliance.
Detailed, statistical procedures are provided to determine whether to
initiate corrective action. Owners/operators of new units must collect
monitoring data before wastes are managed and must collect
background soil-pore liquid data from beneath the unit before
construction occurs. The General Industrial Storm Water Permit also
contains a four-tier, highly detailed monitoring strategy.
Surface Water: Extensive surface water monitoring requirements
exist that contain essentially the same components as the groundwater
monitoring program.
Waste Analysis Requirements: Owners/operators must report the
types, quantities, and concentrations of wastes proposed to be
managed at each waste unit. They must also provide an analysis of
projected waste decomposition processes for each unit. The following
Information also is required on: (1) the physical characteristics of the
waste management unit; (2) how the unit will affect surrounding
ground and surface water; and (3) how these waters may affect the
unit. Additional reporting requirements exist.
State regulations specify requirements for reporting and
recordkeeping.
State regulations give the authority to inspect, but do not specify the
frequency.
(continued)
D-16
-------
Appendix D
Program Coverage
California Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Description of Regulation or Program
Contingency Plan: Dischargers must submit operation plans
describing the waste management unit operation which shall include
contingency plans for the failure or breakdown of waste handling
facilities or containment systems, including notice of any such failure,
or any detection of waste or leachate in monitoring facilities to the
regional board, local governments, and water users downgradient of
the surface impoundment (23 CCR Article 9 2596).
Emergency Planning: Owners/operators must implement detection
monitoring and evaluation monitoring programs and corrective action
measures, as necessary, to comply with water quality protection
standards and reporting requirements.
Corrective Action: Regional boards will establish the water quality
protection standards for corrective action. In conjunction with
corrective action measures, owners/operators must establish and
implement a water quality monitoring program to demonstrate the
effectiveness of the corrective action program and must submit reports
at least semiannually on the effectiveness of the program. If an
owner/operator is involved in corrective action at the end of a waste
management unit's compliance period, the compliance period must be
extended so that the unit is in continuous compliance with its water
quality protection standard for at least 3 consecutive years.
Mandatory Clean-Closure Attempt: Unless the discharger
demonstrates, and the RWQCB finds, that it is infeasible to attempt
clean-closure of the impoundment, then all residual wastes, including
sludges, precipitates, settled solids, and liner materials contaminated
by wastes, shall be completely removed from the impoundment and
discharged to an approved Unit. Remaining containment features shall
be inspected for contamination and, if not contaminated, can be
dismantled. Any natural geologic materials beneath or adjacent to the
closed impoundment that have been contaminated shall be removed
for disposal at an appropriate Unit. For surface impoundments that
are successfully clean-closed, as herein described, the RWQCB shall
declare the Unit no longer subject to the SWRCB -promulgated
requirements of this title. If, after reasonable attempts to remove such
contaminated materials, the discharger demonstrates that removal of
all remaining contamination is infeasible, the surface impoundment
shall be closed as a landfill or land treatment unit.
State regulations specify requirements for financial assurance.
(continued)
D-17
-------
Appendix D
Program Coverage
California Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Description of Regulation or Program
State regulations specify requirements for air emissions from surface
impoundments.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Source:
California Code of Regulations (CCR).
D-18
-------
Appendix D
Program Coverage
Colorado
In Colorado, responsibility for regulating and permitting surface impoundments is
consolidated in the Hazardous Materials and Waste Management Division of the Colorado
Department of Public Health and the Environment (CDPHE).
Colorado's industrial waste regulations specify a set of standards and criteria for waste
impoundments as indicated in the table below. Industrial wastes disposed of on the property of
the generator are not required to obtain a permit (known as the "Certification of Designation")
but must still abide by the regulations. In addition, impoundments that discharge to surface water
or groundwater must obtain a State NPDES discharge permit.
Colorado Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Program or
Regulation
Addresses
Criteria?
No
Yes
Yes
Yes
Yes
Yes
Description of Regulation or Program
Not specified in state regulations.
State solid waste regulations require that impoundments constructed
after October 9, 1993 must have an engineering design report and, for
certain groundwater classes, a liner and leachate collection system is
required. Groundwater monitoring, however, may be required for
impoundments permitted prior to this date if seepage and impairment
of groundwater is probable. State regulations also specify that
impoundments meet embankment design requirements. (Volume 6
CCR 1007-2 Part 1B-9)
State solid waste regulations specify that impoundments must meet
standards for measurement of depth and have operational inspections.
For impoundments constructed after October 9, 1993, an operations
report and a minimum of 2 feet of freeboard is required. (Volume 6
CCR 1007-2 Part 1B-9)
The state NPDES regulations require groundwater monitoring. The
solid waste regulations further specify that groundwater monitoring is
required of indicator parameters of upgradient and downgradient wells
on an annual or quarterly basis (depending on groundwater
classification) for impoundments constructed after October 9, 1993.
(Volume 6 CCR 1007-2 Part 1B-9)
For impoundments constructed after October 9, 1993, the state
NPDES regulations require monthly summary records be maintained
until closure.
State regulations give the authority to inspect, but do not specify the
frequency.
(continued)
D-19
-------
Appendix D
Program Coverage
Colorado Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
Description of Regulation or Program
State NPDES regulations require a contingency plan for
impoundments constructed after October 9, 1993 in certain
groundwater classes dictating conditions for corrective action
State solid waste regulations require closure and postclosure plans.
The Plans include a final cover sufficient to ensure compliance with
state groundwater standards. Regulations specify that the postclosure
period be a minimum of 30 years (duration subject to modification a
case-by-case basis), and include maintenance and monitoring. An
additional requirement for surface impoundments includes
characterization of residual sediments for hazardous characteristics for
impoundments constructed after October 9, 1993.
For closure, postclosure, and corrective action, state solid waste
regulations require a trust fund, letter of credit, surety bond, insurance,
financial test, corporate guarantee certificate of deposit, or
combination. The financial assurance requirements are applicable to
those impoundments operating after October 9, 1997 (if they dispose
less than 20 tons per day) or April 9, 1997 (if they dispose greater than
20 tons per day).
State regulations require the operator of a facility employing
evaporative treatment to calculate and record on a quarterly basis: the
total volume of wastes and precipitation added to each impoundment;
the total PAN evaporation during the quarter at the Weather Service or
other station specified, multiplied by the appropriate "Lake
Evaporation Coefficient," then multiplied by the average surface area
of each impoundment during the quarter, to give the maximum
possible volume of evaporate loss; and the total change in volume of
wastes stored in each impoundment by two methods: (1) volume on
first day of quarter subtracted from the volume on the last day of the
quarter (from depth readings); and (2) maximum evaporative loss
subtracted from the total added. Seepage shall be neglected in this
calculation.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Colorado Code of Regulations (CCR) - 6 CCR 1007-2 Part 1; 5 CCR 1002-61.
Colorado Department of Public Health and the Environment (CDPHE) web page (http://www.cdphe.state.co.us).
D-20
-------
Appendix D
Program Coverage
Connecticut
Connecticut's Waste Engineering and Enforcement Division indicates that nonhazardous
surface impoundments may be regulated under the State Remediation Standards, depending on
the amount and type of constituents in the ground near the surface impoundments. In addition,
surface impoundments may be regulated under the state's NPDES program if they discharge to
surface waters. Connecticut is authorized to administer the federal NPDES program under its
Surface Water Discharge Permit Program. Connecticut also has a Groundwater Discharge
Permit Program that regulates discharges to groundwater from any source, including but not
limited to large septic systems, agricultural waste management systems, and all waste landfills.
Connecticut Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Program or
Regulation
Addresses
Criteria?
No
No
Yes
Yes
Yes
Yes
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations.
The commissioner may require any applicant or permittee for a
NPDES permit, as part of the detailed design of any treatment
facilities and/or spill prevention and control systems required, to
develop an operation and maintenance manual which shall fully
describe the operation and maintenance of the systems, including but
not limited to the following aspects:
(1) A plan for operational monitoring and inspection
(2) Instrument calibration frequency
(3) Inventory of necessary chemicals, equipment and spare parts
(4) A plan for preventive maintenance
(5) Operating instructions
(6) Housekeeping
(7) Security measures.
State regulations specify that any permittee of the NPDES permit has
requirements for monitoring of discharges.
All monitoring reports shall be submitted to the director in accordance
with the requirements and the terms and conditions of the NPDES
permit.
State regulations give the authority to inspect, but do not specify the
frequency.
Not specified in state regulations.
(continued)
D-21
-------
Appendix D
Program Coverage
Connecticut Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
No
Description of Regulation or Program
Not specified
Not specified
Not specified
in state regulations.
in state regulations.
in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Source:
Connecticut General Statutes (COS)
D-22
-------
Appendix D
Program Coverage
Delaware
The Division of Water Resources of the Delaware Department of Natural Resources and
Environmental Control has authority over surface impoundments in the state. Because Delaware
regulates surface impoundments in conjunction with other programs, it does not classify surface
impoundments or waste types; however, permits are required. Surface impoundments must be
covered by a state operating permit (required for the construction and/or operation of facilities
handling liquid waste), and a state NPDES permit for discharges into surface or groundwater.
For facilities that discharge, the NPDES permit and state operating permit are consolidated into
one permit.
Delaware Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
No
Yes
(guidance
only)
Yes
(guidance
only)
Case-by-case
No
Yes
No
No
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations, but included in the Recommended
Standards for Sewage Treatment Works (Ten States Standards).
Not specified in state regulations, but included in the Recommended
Standards for Sewage Treatment Works (Ten States Standards).
The monitoring requirements specified by the Department in the State
operating permit may include groundwater monitoring. [WPCR §
5.01(g)(8)]
Not specified in state regulations.
State regulations give the authority to inspect but do not specify
frequency.
the
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-23
-------
Appendix D
Program Coverage
Delaware Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Description of Regulation or Program
A permit is required for surface impoundments that emit more than 25
tons/year of volatile organic compounds (VOCs). Owners or
operators of a regulated source must perform testing to demonstrate
that the source is in compliance with State standards, and maintain
records of the testing for a minimum of 5 years.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Delaware Code of Regulations Governing Water Pollution (WPCR).
Air Pollution (APCR) Regulation No. 24-50.
D-24
-------
Appendix D
Program Coverage
Florida
The Florida Department of Environmental Protection requires groundwater permits and
state NPDES permits (for discharges to surface water only) for surface impoundments used to
manage nonhazardous waste. Surface impoundments that manage leachate are regulated
separately under the solid waste management facilities regulations. Otherwise, surface
impoundments are excluded from the solid waste management facilities regulations.
Florida Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
No
No
No
Yes
Yes
Yes
Yes
Yes
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
State regulations require groundwater monitoring for certain classes of
groundwater, with at least 1 upgradient, 1 intermediate, and 1
compliance well. The constituents are not specified in the regulations.
State regulations require quarterly groundwater monitoring reports be
maintained.
State regulations give the authority to inspect, but do not specify the
frequency.
State regulations require corrective action if groundwater exceeds state
standards outside ZOD and include secondary standards for certain
classes of groundwater.
Closure with waste in place is allowed by state regulations if the
impoundment is dewatered, lined, and measures (such as leachate
collection) are in place to ensure liner integrity. The regulations do
not specify any other closure/postclosure provisions.
Not specified in state regulations.
(continued)
D-25
-------
Appendix D
Program Coverage
Florida Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Florida Administrative Code (FAC) Chapters 62-520; 62-522; 62-620; 62-701.
Florida Department of Environmental Protection (FDEP) web page (http://www.dep.state.fl.us/).
D-26
-------
Appendix D
Program Coverage
Georgia
The Environmental Protection Division (EPD) of the Georgia Department of Natural
Resources has the responsibility for regulating surface impoundments in Georgia. EPD does not
require permits for non-discharging ponds, however, a few slow infiltration ponds are permitted.
Surface impoundments that discharge to groundwater must obtain a state land disposal system
permit. Impoundments that discharge to surface water must obtain a state NPDES permit.
Georgia Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
No
No
No
Case-by-case
No
Yes
Yes
No
No
Description of Regulation or Program
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Groundwater monitoring may be required under land disposal system
permit, with details determined on a site specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
State regulations give the authority to inspect, but do not specify the
frequency.
The under land disposal permit requires that groundwater must be
within state maximum contaminant levels (MCLs). Where
groundwater exceeds state MCLs, corrective measures and a
compliance schedules are determined on a site-specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
(continued)
D-27
-------
Appendix D
Program Coverage
Georgia Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Official Code of Georgia Statutes (OCGA) 12-8-20.
Georgia Regulations - Control No. 391-3-4; 391-3-6-.il.
Georgia Department of Natural Resources (GDNR) web page (http://www.dnr.state.ga.us/dnr/environ).
D-28
-------
Appendix D
Program Coverage
Hawaii
Hawaii's environmental regulations, administered by the Environmental Management
Division of the Department of Health, include few requirements applicable to nonhazardous
waste surface impoundments beyond the requirements associated with a state NPDES permit for
discharges to surface or groundwater. In addition to the NPDES regulations, there are separate
regulations and guidance governing wastewater treatment works.
Hawaii Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Yes
No
No
No
No
Yes
No
No
No
Description of Regulation or Program
For wastewater treatment works, treatment units must be located 25
feet or more from the property line and more than 10 feet away from
buildings and swimming pools. Private wastewater treatment works
must also conform to the Recommended Standards for Wastewater
Facilities (Ten State Standards).
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
State regulations give the authority to inspect
frequency.
, but do not specify the
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-29
-------
Appendix D
Program Coverage
Hawaii Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Source:
Hawaii Administrative Rules Chapter 55.
D-30
-------
Appendix D
Program Coverage
Idaho
In Idaho, the only regulations applicable to surface impoundments are design and
operating requirements for ore processing by cyanidation or mine tailing impoundments - there
are not even state NPDES regulations that apply since Idaho is not an NPDES-authorized state.
Idaho relies on Recommended Standards for Sewage Treatment Works (Ten State Standards) in
reviewing wastewater treatment plant plans.
Idaho Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
No
No
No
Yes
No
No
No
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Source:
Idaho Regulations - IDAPA Department of Environmental Quality Title 01 Chapter 02.
D-31
-------
Appendix D
Program Coverage
Illinois
Illinois requirements regarding nonhazardous surface impoundments are administered by
the Illinois Environmental Protection Agency (IEPA) by the Bureau of Water.
The Illinois Environmental Protection Act exempts on-site treatment, storage, and
disposal from permitting requirements. Owners/operators of surface impoundments, however,
that receive special waste (i.e., from off-site) not listed in an NPDES permit must obtain an
operating permit, unless the owner/operator gives notice of the operation to IEPA 30 days after
operations begin, and every three years thereafter. In the three-year notice, the owner/operator
must submit information on the types and amounts of waste stored, treated, or disposed each
year; the remaining capacity of the facility; and the remaining expected life of the facility.
A state NPDES permit is required for impoundments discharging into surface waters.
In addition, Illinois has specific design standards for new or modified livestock waste
treatment lagoons after November 12, 1998 (35 IAC 503.204). Owners/operators of these
lagoons must construct or modify the lagoon in accordance with "Design of Anaerobic Lagoons
for Animal Waste Management" which is incorporated by reference in 35 IAC 506.104. Some of
these requirements are included in the table below.
The IEPA Bureau of Air implements the requirements of the Clean Air Act, develops
state rules governing air quality standards, evaluates and issues permits for construction and
operation, and monitors Illinois' air quality.
Illinois Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Program or
Regulation
Addresses
Criteria?
No
No
Yes
Description of Regulation or Program
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Livestock waste treatment lagoons must include:
• The use of a liner at least 2 feet thick.
• Entrapment dikes and other appropriate control measures to prevent
any spillage of contaminants from causing water pollution.
• Freeboard of at least 2 feet above the fluid surface level of the
lagoon.
Extensive groundwater quality standards exist, and owners/operators
cannot cause, threaten, or allow the release of any contaminant so as to
violate a groundwater quality standard.
(continued)
D-32
-------
Appendix D
Program Coverage
Illinois Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
Yes
Yes
No
No
No
Description of Regulation or Program
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
The state regulations provide IEPA with the authority to require
periodic reports, inspect facilities, and have access to records. The
frequency of the inspections is not specified.
No person shall cause or allow the release of any contaminant to a
resource groundwater such that: treatment is necessary to continue an
existing use or to assure a potential use of such groundwater, or an
existing or potential use of such groundwater is precluded.
Not specified in state regulations.
Not specified in state regulations
Not specified in state regulations
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Illinois Regulations: Title 35 Subtitle C Parts 305, 309; Title 35 Subtitle E Part 506.
Illinois Statutes: 415 ILCS 5/2l(d).
Illinois Environmental Protection Agency (IEPA) web page (http://www.epa.state.il.us/water/index.html).
D-33
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Appendix D
Program Coverage
Indiana
In Indiana, nonhazardous waste surface impoundments are regulated through the Indiana
Department of Environmental Management (IDEM) by the Office of Land Quality (OLQ) and
the Office of Water Management (OWM). Nonhazardous waste surface impoundments are
exempt from Indiana's Solid Waste Management requirements; however, closure of an
impoundment is subject to approval by IDEM and usually occurs, at the discretion of IDEM, in
the same manner as other solid waste management facilities (e.g., final cover and groundwater
monitoring required).
The construction, installation, or modification of any facility used for wastewater
treatment requires that a construction permit be obtained from the OWM Permits Branch. These
permits are required for the construction of all water pollution treatment/control facilities
including industrial wastewater facilities. All new facilities (i.e., within the last 20 years) must
have a construction permit.
Off-site "earthen lagoons" that store industrial waste product are regulated by the Water
Pollution Control Board under 327 IAC 6.1. IDEM's OWM implements and enforces the
Federal Water Pollution Control Act (as amended), also referred to as the Clean Water Act.
IDEM's OWM Wastewater Permitting Branch has responsibility for the permit program.
Under 329 IAC 10-8.1-4, decharacterized wastes can be classified as a "special waste" if
the waste contains a toxicity characteristic contaminant listed in 40 CFR 261.24, Table 1, at a
level equal to or greater than seventy-five percent (75%) of the regulatory level for that
contaminant.
The IDEM Office of Air Management (OAM) implements the requirements of the Clean
Air Act, develops state rules governing air quality standards, evaluates and issues permits for
construction and operation, and monitors Indiana's air quality.
Indiana Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Program or
Regulation
Addresses
Criteria?
Case-by-case
Description of Regulation or Program
Design criteria and location standards are not specified in state
regulations, but may be applied through construction permits on a site-
specific basis. Location restriction are specified for earthen lagoons
under 327 IAC 6.1-8-3 ("Site restrictions for off-site storage
structures").
(continued)
D-34
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Appendix D
Program Coverage
Indiana Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Case-by-case
Yes
Case-by-case
Yes
Yes
No
Yes
No
No
Description of Regulation or Program
Not specified in state regulations. May be applied through
construction permits on a site-specific basis. Generally, IDEM and
owners/operators follow the Recommended Standards for Wastewater
Facilities and Sewage Works (Ten States Standards), 1990 edition, as
guidance. Owners/operators of wastewater treatment ponds generally
must comply with standards for liners, soil borings/freeboard limits,
etc., to protect the waters of the state.
The industrial activity permit requirements contain a waste
discharge/run-off control performance standard. Freeboard
requirements are specified in 327 I AC 6.1 for earthen lagoons. Other
operating criteria for earthen lagoon are specified at 327 IAC 6.1-8-7
("Operational requirements for off -site storage structures").
Not specified in state regulations. May be applied by the IDEM on a
site-specific basis upon closure with waste in place.
Reporting of discharge monitoring results must be maintained for 3
years.
Owners/operators conducting practices that are likely to cause
exceedances of applicable effluent limitations must notify the
commissioner. IDEM must be allowed to enter the premises of a
facility at any reasonable time to inspect, sample, or monitor. IDEM's
Office of Enforcement has authority to issue civil, administrative,
judicial, and criminal penalties.
Not specified in state regulations.
327 IAC 6.1-8-8, "Closure and abandonment of off -site storage
structures" applies.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulation or program.
Sources:
Indiana Administrative Code (IAC)
Indiana Department of Environmental Management (IDEM) web page (http://www.state.in.us/idem/index.html).
D-35
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Appendix D
Program Coverage
Iowa
In Iowa, nonhazardous waste surface impoundments are regulated through the
Environmental Protection Division (EPD) of the Iowa Department of Natural Resources (IDNR).
The Wastewater Section of the EPD issues construction, operation (discharges to groundwater),
and NPDES permits (discharges to surface water) for surface impoundments.
Iowa also has specific requirements in place for waste stabilization ponds under the state
water rules. These requirements are included below.
Iowa Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
No
Yes
Yes
Case-by-case
No
No
Description of Regulation or Program
State permit-to-construct regulations require that all surface
impoundments must be located 1000 feet from residences and
commercial buildings, 400 feet or more from wells (depending on
type) and lakes, and 25 feet from property lines.
For waste stabilization ponds only, pond length can not exceed three
times the width, capacity must be equivalent to 180 times the average
daily design flow, bottom lined with impermeable natural or man-
made material, and the depth must be uniform from 3 to 5 feet. For
other types of impoundments, not specified in regulations but may be
required as part of construction permit on a site-specific basis.
For waste stabilization ponds only, a minimum freeboard of 2 feet is
required, as well as fencing and vegetation. For other types of
impoundments, not specified in regulations but may be required as
part of NPDES or operating permit on a site-specific basis.
Not specified in regulations but groundwater monitoring may be
required on a site-specific basis.
State regulations require monthly submission of records of operation.
State regulations provide the authority to inspect, but do not specify
the frequency.
Determined on a permit-specific basis.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-36
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Appendix D
Program Coverage
Iowa Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulation or program.
Sources:
Iowa Administrative Code (IAC) Title IV, Chapters 63, 64 and 69.
Iowa Department of Natural Resources (IDNR) web page (http://www.state.ia.us/government/dnr).
D-37
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Appendix D
Program Coverage
Kansas
In Kansas, nonhazardous waste surface impoundments are regulated through the Bureau
of Waste Management, Division of Environment, Kansas Department of Health and
Environment.
Kansas requires a solid waste disposal permit if the owner/operator plans to close the
surface impoundment with waste still in place; the expiration date of this permit is determined on
a case-by-case basis. In addition, all impoundments that discharge to surface or groundwater
must obtain a state NPDES permit, which is valid for up to 5 years.
Kansas Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Program or
Regulation
Addresses
Criteria?
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Description of Regulation or Program
The solid was disposal permit regulations require that surface
impoundments be located at least one-half mile from a navigable
stream used for interstate commerce; one mile from a public surface
water supply; and 25 feet from pipelines, underground utility lines, or
an electric transmission line easement. There are also restrictions on
100-year floodplains and endangered species areas.
The solid waste disposal permit regulations specify restrictions for
limited access and requires all-weather access roads.
Not specified in state regulations.
Appropriate groundwater monitoring required, but specific details are
not listed in the regulations (determined on a permit-specific basis).
The solid waste disposal permit regulations require the facility to
retain records of volume or tonnage of waste received, land area used,
and other records as specified in the permit. A summary report of
these records must be submitted to the Department.
State regulations provide the authority to inspect, but do not specify
the frequency.
Not specified in state regulations.
The solid waste permit regulations require a closure plan, including
provisions for postclosure operation and maintenance. The plan may
also include liners and leachate collection if deemed applicable by the
state. There is a postclosure period of at least 30 years.
(continued)
D-38
-------
Appendix D
Program Coverage
Kansas Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
No
Description of Regulation or Program
The solid waste permit regulations require a trust fund, surety bond,
irrevocable letter of credit, or insurance; or pass a financial test or
obtain a financial guarantee from a related entity. The operator/owner
of the impoundment must also have liability insurance coverage.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulation or program.
Sources:
Kansas Statutes - KSA 65-33; 65-34.
Kansas Regulations - KAR 28-13; 28-16; 28-29-2 through 28-29-23.
Kansas Department of Health and Environment (KDHE) web page (http://www.kdhe.state.ks.us/waste/).
D-39
-------
Appendix D
Program Coverage
Kentucky
In Kentucky, nonhazardous waste surface impoundments with discharges to surface or
groundwater must obtain a state NPDES (KPDES) permit. The regulations are largely silent on
the requirements under these permits, leaving specific requirements to be determined by the
permit writer on a case-by-case basis. Surface impoundments that have a KPDES permit are
covered under a Permit-by-Rule for purposes of the solid waste regulations. The Permit-by-Rule
contains no specific requirements beyond those of the KPDES regulations, except that
groundwater monitoring may be required on a case-by-case basis and that the state has authority
to require corrective action.
In addition to the KPDES and solid waste permit, surface impoundments constructed
after August 24, 1994 are required to develop a Groundwater Protection Plan (GWPP). The
GWPP must consider site hydrogeology and minimize discharges to soil. The actions required to
meet the goals of the GWPP are determined by the facility operator, and minimization of
discharges to soil may be accomplished through liners, secondary containment, leak detection, or
other measures.
Kentucky Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Program or
Regulation
Addresses
Criteria?
Yes
Yes
No
Case-by-case
Yes
Yes
Description of Regulation or Program
The regulations specify restrictions for floodplains, endangered
species habitats, and wetlands.
The required GWPP must consider hydrogeology and minimize
discharges to soil. At the operator's option, this may be accomplished
through liners, secondary containment, leak detection, or other
measures. No other controls are specified by the NPDES or solid
waste regulations, but may be required in the permits on a site-specific
basis.
Not specified in state regulations.
The solid waste regulations specify that groundwater monitoring may
be required on a case-by-case basis.
A GWPP must be submitted upon request, and records of compliance
must be retained. The solid waste regulations require annual or
quarterly reports covering facility activities, as determined in the
permit.
State regulations give the authority to inspect, but do not specify the
frequency.
(continued)
D-40
-------
Appendix D
Program Coverage
Kentucky Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
No
Yes
No
Description of Regulation or Program
The solid waste regulations provide the authority to require that
appropriate corrective action to be implemented if needed. The
regulations also specify that surface impoundments may not cause
exceedances of MCLs in groundwater, adversely impact endangered
species, or violate applicable air pollution requirements.
Not specified in state regulations
The solid waste regulations state that financial assurance requirements
apply to owners/operators of any solid waste disposal site or facility.
Mechanisms can include performance bond, surety bond, letter of
credit, escrow or trust fund. Not specified in state regulations.
Not specified in state regulations
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulation or program.
Sources:
Kentucky Administrative Regulations (KAR) Title 401, Chapters 5, 47, and 48.
Kentucky Department for Environmental Protection (KDEP) web page
(http://www.nr.state.ky.us/nrepc/dep/dep2.htm/).
D-41
-------
Appendix D
Program Coverage
Louisiana
In Louisiana, nonhazardous waste surface impoundments are regulated by the Solid
Waste Division, Office of Solid and Hazardous Waste, Department of Environmental Quality
(Title 33, Part Vn, Subpart 1, Chapter 7, Subchapter B of the Louisiana Code). Section
709-Standards Governing All Solid Waste Disposal Facilities (Type I and n)-establishes the
basic management program for solid waste within the state. A Type I surface impoundment is
used for the disposal of industrial solid wastes, and a Type II surface impoundment is used for
the disposal of commercial or residential solid wastes. Discharges are subject to the Louisiana
Pollutant Discharge Elimination System (LPDES) program at Title 33, Part IX.
All surface impoundments (dischargers and nondischargers) storing nonhazardous waste
are required to obtain a state solid waste permit. In addition, all impoundments that discharge are
required to obtain a state NPDES permit.
Louisiana Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Description of Regulation or Program
Location standards are specified in Louisiana Administrative Code
(LAC) Sections 521, 709, and 713. These standards include (1)
requirements for accessing (e.g., via water or land) surface
impoundment facilities; (2) restrictions for siting such facilities near
airports, critical environmental areas (e.g., wetlands, estuaries, wildlife
hatchery areas; habitats of endangered species), faults, 100-year flood
plains, and other requirements; and (3) requirement for compliance
with local land use and zoning laws.
State regulations specify requirements for liners, leachate detection,
collection, and removal systems, run-on/run-off controls, standards for
dikes and berms, and freeboard limits.
Facilities must have a barrier around the facility that prevents
unauthorized ingress or egress, except by willful entry. During
operating hours, each facility entry point must be continuously
monitored, manned, or locked. During non-operating hours, each
facility entry point must be locked. These standards also include
requirements for buffer zones, fire protection and medical care, and
other requirements. Surface impoundments must be inspected daily
and after storms to detect evidence of deterioration of the dikes and
levees, overtopping, malfunctions, or improper operation.
(continued)
D-42
-------
Appendix D
Program Coverage
Louisiana Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
Yes
Yes
Description of Regulation or Program
Groundwater Monitoring: A groundwater monitoring system must
be installed at each facility. The system must contain a sufficient
number of wells, installed at appropriate locations and depths, to yield
groundwater samples from the uppermost aquifer. These standards
include specific requirements for groundwater sampling, location of
wells, well construction, post-construction, plugging and abandonment
of monitoring wells.
Surface Water Monitoring: Under the Louisiana Water Discharge
Permit System, effluent standards and limitations are imposed upon
discharges. The control and treatment limitations must be equivalent
to secondary treatment, best practicable control technology currently
available, best conventional technology for conventional pollutants,
and/or best available control technology economically achievable for
nonconventional or toxic pollutants. The permitting authority may,
however, prescribe more stringent or seasonal limitations.
Facilities must submit annual reports to the administrative authority
indicating quantities and types of solid waste and an estimate of the
remaining permitted capacity. Records must be maintained for the life
of the facility and at least three years after closure.
The Solid Waste Division will inspect each facility and each facility's
records periodically to determine the facility's compliance with the
terms of standard or temporary permits and these regulations.
Performance standards and corrective action requirements are
specified by the state regulations.
Standards governing facility closure are contained in LAC
33:VII.713.E (Type I and II surface impoundments). The closure plan
for all facilities must include the following: the date of final closure,
the method to be used and steps necessary for closing the facility; and
the estimated cost of closure of the facility, based on the cost of hiring
a third party to close the facility at the point in the facility's operating
life when the extent and manner of its operation would make closure
the most expensive.
The state solid waste permit requires evidence of a financial assurance
mechanism for closure and/or postclosure care and corrective action
for known releases when needed.
(continued)
D-43
-------
Appendix D
Program Coverage
Louisiana Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Description of Regulation or Program
Facilities receiving waste with a potential to produce methane gas are
subject to air monitoring requirements.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Louisiana Administrative Code (LAC).
Louisiana Department of Environmental Quality (LDEQ) web page (http://www.deq.state.la.us).
D-44
-------
Appendix D
Program Coverage
Maine
Maine does not have any regulatory standards or management guidelines specific to
surface impoundments. However, if the facility discharges, Maine's Bureau of Land & Water
Quality Control (L&W) may include, on a case-by-case basis, standards and guidelines for
surface impoundments in the state's wastewater discharge permit and site approval process.
If a surface impoundment has a point source discharge to surface waters of the United
States, the owner/operator must obtain a federal NPDES permit pursuant to Section 402 of the
Clean Water Act (CWA). Also pursuant to Section 402 of the CWA, NPDES permits are
required for storm water discharges associated with an industrial activity. (Note: Region 1 issues
NPDES permits, as Maine is not authorized.)
Licenses are required for discharges to surface waters and groundwater. Discharges to
groundwater may be direct or indirect (e.g., infiltration-percolation lagoon). Discharges are
subject to effluent limitations that require application of "best practicable treatment" (38 MRS A
Section 414-A). Permits are issued by L&W. (Note: Maine has no infiltration-percolation
lagoons holding industrial nonharardous wastewater. Some exist to hold storm water, which
require a federal NPDES Permit.)
L&W must approve all industrial developments that occupy a land or water area in excess
of 20 acres. L&W will approve the development as long as it will not adversely effect the natural
environment; cause unreasonable erosion of soil or inhibit the natural transfer of the soil; cause
unreasonable erosion of soil or inhibit the natural transfer of the soil; discharge to a significant
groundwater aquifer; cause or increase flooding, etc. State contacts report that no on-site
industrial nonharardous waste surface has land site approval. This may be because the
impoundment was constructed prior to 1970 (in which case the impoundment is
"grandfathered"), does not meet the minimum size requirement, or is not a permitting priority.
Maine Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Program or
Regulation
Addresses
Criteria?
No
Case-by-case
No
Description of Regulation or Program
Not specified in state regulations.
L&W usually includes an impervious clay liner requirement in the
wastewater discharge permit.
Not specified in state regulations.
(continued)
D-45
-------
Appendix D
Program Coverage
Maine Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Case-by-case
No
Yes
No
No
No
No
Description of Regulation or Program
Groundwater Monitoring: L&W may include groundwater
monitoring as a requirement for site approval, however, only in limited
circumstances.
Surface Water Monitoring: Surface water monitoring is required if
the facility has a federal NPDES permit.
Not specified in state regulations.
MDEP is authorized to conduct on-site inspections of wastewater
discharge licenses (38 MRSA Section 414). MDEP also has
administrative, civil, and criminal enforcement authority, including the
authority to levy penalties.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Maine Revised Statutes Annotated (MRSA).
Maine Department of Environmental Protection (MDEP) web page (http://janus.state.me.us/dep/home.htm).
D-46
-------
Appendix D
Program Coverage
Maryland
In Maryland, nonhazardous waste surface impoundments are regulated by the Water
Management Administration, Wastewater Discharge Program (WDP) of the Maryland
Department of the Environment (MDE) and the Air and Radiation Management Administration
(ARMA). The WDP has regulatory responsibility for the control of surface water discharges
from industrial impoundments, including most other requirements for surface impoundments.
ARMA is responsible for regulating air emissions from industrial surface impoundments.
Maryland currently requires surface impoundments to have a permit to construct unless they are
specifically exempt (exemptions listed in COMAR 26.11.02.10).
Maryland Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Case-by-case
Case-by-case
Yes
Case-by-case
No
Yes
No
No
No
Description of Regulation or Program
Not specified in state regulations. May be applied by the Department
on a site-specific basis.
Not specified in state regulations. May be applied by the Department
on a site-specific basis.
State regulations specify requirements for runon/runoff controls only.
Additional requirements may be applied by the Department on a site-
specific basis.
Groundwater/Leak Detection: Not specified in state regulations.
May be applied by the Department on a site-specific basis.
Surface Water Monitoring: Not specified in state regulations.
May be applied by the Department on a site-specific basis.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-47
-------
Appendix D
Program Coverage
Maryland Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Description of Regulation or Program
The Air and Regulations Management Administration regulations
requires surface impoundments to have a permit to construct.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation, program, or guidance.
Sources:
Annotated Code of Maryland.
Code of Maryland Regulations (COMAR).
Maryland Department of the Environment (MDE) web page (http://www.mde.state.md.us).
D-48
-------
Appendix D
Program Coverage
Massachusetts
The Massachusetts Department of Environmental Protection does not regulate
nonhazardous surface impoundments under solid waste regulations. Massachusetts is not
authorized to administer the federal NPDES program.
Massachusetts Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
No
No
No
No
No
No
No
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation, program, or guidance.
Sources:
Code of Massachusetts Regulations (CMR).
Massachusetts Department of Environmental Protection web page (http://www.state.ma.us/dep).
D-49
-------
Appendix D
Program Coverage
Michigan
In Michigan, responsibility for regulating and permitting surface impoundments is
consolidated in the state's water program of the Michigan Department of Environmental Quality
(MDEQ) if wastewater is discharged to surface or groundwater. If an impoundment is being
closed with waste in place, it is regulated under the Solid Waste Management Division.
An NPDES permit is required for impoundments that discharge to surface water and a
State permit is required for discharges to groundwater. Both permits are valid for no more than
five years, after which they must be renewed.
Michigan Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Description of Regulation or Program
State regulations require surface impoundments discharging to
groundwater to be located 50 or more feet (depending on well type)
from water supply wells. There must also be 4 feet of vertical
isolation between the bottom of the pit and the uppermost groundwater
level.
A surface impoundment must have a composite liner, demonstrate that
an impoundment is not leaking (at a rate likely to impact
groundwater), or conduct monitoring verifying that the impoundment
has not impacted groundwater and is not likely to do so.
Surface impoundments must meet certain operating criteria. This
includes a minimum of 2 feet of freeboard, and earthen dikes must
meet structural integrity and erosion control requirements.
Groundwater discharge permits require unlined impoundments to
monitor for parameters and frequency which are specified in the
permit on a case-by-case basis.
The owner/operator of impoundments must report monitoring results
at least annually.
State regulations give the authority to inspect, but do not specify the
frequency.
Notification is required and response action is determined by the state
agency if groundwater exceeds state standards.
(continued)
D-50
-------
Appendix D
Program Coverage
Michigan Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
No
Description of Regulation or Program
Impoundments closing with waste in place are subject to Type III
landfill closure requirements (i.e., final cover, 6 inches of topsoil,
revegetation and erosion control, 30-year postclosure period, and
biannual groundwater monitoring), and must remove all free liquids
and demonstrate that waste has sufficient bearing capacity for final
cover.
Impoundments closing with waste in place are subject to Type III
landfill financial assurance requirements that mandate a bond,
perpetual care trust, escrow account, or financial test for closure and
postclosure care.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulation or program.
Michigan Administrative Code (MAC).
Michigan Department of Environmental Quality (MDEW) web page (http://www.deq.state.mi.us/).
D-51
-------
Appendix D
Program Coverage
Minnesota
In Minnesota, nonhazardous waste surface impoundments are regulated through the
Water Quality Division of the Minnesota Pollution Control Agency (MPCA). A surface
impoundment must be covered by the state NPDES permit for discharges to surface or
groundwater.
Minnesota Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
No
No
No
No
No
Yes
Yes
No
No
Description of Regulation or Program
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Groundwater monitoring not specified in state regulations, but may be
applied on a permit-specific basis.
No specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency. Enforcement mechanisms are not specified in the
regulations.
All surface impoundments must conform to applicable effluent
limitations and water quality standards.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-52
-------
Appendix D
Program Coverage
Minnesota Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulation or program.
Sources:
Minnesota Statute - Chapter 115.
Minnesota Regulations - Chapters 7001 and 7050.
Minnesota Pollution Control Agency (MPCA) web page (http://www.state.in.us/idem/index.html).
D-53
-------
Appendix D
Program Coverage
Mississippi
In Mississippi, responsibility for regulating and permitting surface impoundments is
consolidated in the state's Office of Pollution Control's Surface Water Division of the
Mississippi Department of Environmental Quality (DEQ). Mississippi DEQ established
guidelines for permitting of surface impoundments within the state.
Any person discharging wastes into waters of Mississippi must obtain an individual
NPDES permit or be covered under a general NPDES permit. Any person operating a treatment
works from which no discharge of wastes occurs must obtain a state operating permit. Permit
writers have the flexibility to impose additional and/or more stringent conditions in the permits.
The permit writers have internal guidance that they use. NPDES permits have a fixed term not to
exceed five years. At the time of expiration, NPDES permits are reviewed. Permits are modified
only if DEQ discovers new information about a facility or upon the request of permittee. State
wastewater permits may be issued for a period up to the operating life of the facility.
Mississippi Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Program or
Regulation
Addresses
Criteria?
Yes
No
No
Yes
Yes
Description of Regulation or Program
The location of all surface impoundments within the state must be at
least 150 feet from the nearest adjoining property line except where
the adjoining property is zoned for commercial or industrial use, or
where the adjoining property, dwelling, or commercial establishment
is used for commercial or industrial use. The Permit Board will
consider requests for exception.
Not specified in state regulations.
Not specified in state regulations.
Surface Water Monitoring: Dischargers are subject to applicable
federal effluent standards and limitations if the limitations are not in
conflict with state laws. The Permit Board is authorized to specify
more stringent effluent limitations to meet applicable water quality
standards, treatment standards, or schedules of compliance established
by state laws or regulations. The Permit Board specifies average and
maximum daily quantitative limitations for the level of wastewater
constituents in the discharge in terms of weight and, if appropriate,
average or maximum concentration limits.
A permittee required to monitor discharges must maintain records and
results of the monitoring activities for a minimum of three years. The
Permit Board must request the monitoring reports at least once a year.
(continued)
D-54
-------
Appendix D
Program Coverage
Mississippi Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
No
No
No
No
Description of Regulation or Program
DEQ is authorized to conduct investigations relating to water quality
and pollution causes, prevention, control, and abatement as it deems
necessary. DEQ is also authorized to enforce the Mississippi Air and
Water Pollution Control Law and all rules and regulations and orders
promulgated thereunder.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Mississippi Statutes and Regulations.
Mississippi Department of Environmental Quality (MDEQ) web page (http://www.deq.state.ms.us).
D-55
-------
Appendix D
Program Coverage
Missouri
In Missouri, the Water Pollution Control Division of the Missouri Department of Natural
Resources has the responsibility for regulating and permitting surface impoundments. The
regulations for surface impoundments depend on whether there will be surface water or
groundwater discharges, and whether the facility plans to close with waste in place. Surface
impoundments that remove waste prior to closure are subject to the following permit programs:
• Wastewater construction permit
• State NPDES wastewater operation permit if discharging to surface water or
groundwater
• No Discharge Permit if not discharging to surface water or groundwater.
Surface impoundments closing with waste in place are subject to the following permit
programs:
• Wastewater construction permit
• State NPDES wastewater operation permit if discharging to surface water or
groundwater
• Solid Waste Disposal Area construction and operation permits, but EXEMPT
from this requirement if already covered by a state NPDES permit and comply
with the solid waste regulation regarding filing of the survey plat with the county
recorder upon closure. [10 CSR 80-2.030(2)(B)].
The multiple regulations concerning nonhazardous waste surface impoundments are
largely silent on specific requirements and details, leaving them to the discretion of the permit
writer.
Missouri Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Program or
Regulation
Addresses
Criteria?
No
No
Description of Regulation or Program
Not specified in state regulations, but may be
specific basis.
Not specified in state regulations, but may be
specific basis.
required on a permit-
required on a permit-
(continued)
D-56
-------
Appendix D
Program Coverage
Missouri Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Case-by-case
No
Yes
No
Yes
No
No
Description of Regulation or Program
Not specified in state regulations, but may be required on a permit-
specific basis.
The regulations provide for groundwater monitoring to be required in
an NPDES or No-Discharge permit on a case-by-case basis.
Not specified in state regulations, but may be required on a permit-
specific basis.
The state regulations provide the authority to inspect but do not
specify the frequency.
Not specified in state regulations, but may be required on a permit-
specific basis.
All impoundments must be closed in accordance with a closure plan,
details of plan not specified in regulations.
If waste is to be left in place and NPDES permit coverage is obtained,
solid waste regulations require the filing of the survey plat with the
county recorder upon closure.
Not specified in state regulations, but may be required on a permit-
specific basis.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Sources:
Missouri Statutes: RSMo 16-260; 40-644.
Missouri Regulations: 10 CSR 20-6; 20-8; 80-2; 80-11.
D-57
-------
Appendix D
Program Coverage
Montana
In Montana, responsibility for regulating and permitting surface impoundments is
consolidated in the state's water quality Section of the Montana Department of Environmental
Quality (DEQ). Additional state water program requirements are detailed below.
Montana regulations do not include design and operating criteria for surface
impoundments. The Montana DEQ, Water Quality Bureau (WQB) reviews the applicable
information submitted in the Montana Pollutant Discharge Elimination System (MPDES) and
Montana Groundwater Pollution Control System (MGWPCS) permit applications and includes
criteria in the conditions of the permit on a case-by-case basis.
The state has full authority to administer the federal NPDES permit program and to issue
general permits. Owners and/or operators must obtain a two part MPDES permit that establishes
effluent limitations, and monitoring and reporting requirements for discharges into surface waters
of Montana. MPDES permit application requirements parallel the federal program. WQB issues
MPDES permits.
An owner and/or operator of any source that may discharge pollutants into state
groundwaters must obtain a MGWPCS permit. All applications for a MGWPCS permit must
include general information on the site, processes, existing groundwater quality, etc. The state
may require submission of more detailed information, such as specific design criteria; description
of liner; proposed emergency procedures; and specifically for industrial waste, a description of
the waste volumes and concentrations. WQB issues MGWPCS permits. Holders of MGWPCS
permits must assure compliance with the groundwater quality standards and non-degradation
policy.
Montana Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Program or
Regulation
Addresses
Criteria?
No
Case-by-case
Case-by-case
Description of Regulation or Program
Not specified in state regulations.
WQB may include design criteria (e.g., liners) in MGWPCS on a case-
by-case basis.
WQB may include operating criteria in MGWPCS
basis.
on a case-by-case
(continued)
D-58
-------
Appendix D
Program Coverage
Montana Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
No
No
Case-by-case
No
No
No
Description of Regulation or Program
Surface Water Monitoring: MPDES regulations adopt the
monitoring and reporting requirements at 40 CFR 122.44.
Groundwater Monitoring: All MGWPCS permits must include self-
monitoring requirements for each discharge. Permits must discuss
monitoring well configuration, pollutants to be monitored, frequency
of monitoring, sampling methods, and recording and reporting
procedures.
Not specified in state regulations.
Not specified in state regulations.
WQB may include remediation requirements (e.g., emergency
procedures) in MGWPCS on a case-by-case basis.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation, program, or guidance.
Sources:
Montana Administrative Code (MAC).
Montana Department of Environmental Quality (MDEQ) web page (http://www.deq.state.mt.us).
D-59
-------
Appendix D
Program Coverage
Nebraska
In Nebraska, responsibility for regulating and permitting surface impoundments is
consolidated in the state's water quality division of the Nebraska Department of Environmental
Quality (NDEQ). NDEQ established guidelines for permitting of surface impoundments within
the state.
Nebraska is authorized to issue NPDES permits in the state. In addition, the state is also
authorized to implement and enforce the pretreatment program pursuant to 40 CFR 403.10(e).
Nebraska Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
No
Yes
Description of Regulation or Program
A lagoon shall not be installed or operated on a property less than 3
acres in size. The floor of the lagoon shall be located at least 2 feet
above the highest expected groundwater level and at least 2 feet above
fractured bedrock. The regulations specify the maximum permissible
distances to surface water, types of wells, and property lines.
The soil material of the impoundment floor shall be designed so that it
shall not seep more than l/8th inch per day. If soil borings and tests
indicate that the existing soils are not conducive to compaction, then
soda ash, bentonite, or a synthetic liner shall be used. The floor of the
impoundment shall be level with a difference of plus or minus 3
inches is permitted. The regulations specify the maximum slope
permissible.
A minimum of one foot of freeboard is required. The crest elevation
of the impoundment should be greater than the elevation of a 100-year
flood elevation. The impoundment shall be located and constructed so
it will not receive surface runoff water. The lagoon shall be fenced
with a 4-foot high woven wire, welded wire, or 7 strand barbed wire
with the first strand starting 3 inches from the ground and the
following strands spaced evenly. The fence shall be equipped with a
standard main gate that is kept locked. The fence shall be placed on
the outside edge of the top of the dike or 4 feet outside the toe of the
dike. Signs shall be located on each gate with a warning of "NO
TRESPASSING - WASTEWATER LAGOON."
Groundwater Quality: The Department may require, as a permit
condition, groundwater monitoring for any onsite wastewater
treatment system if there is a potential for groundwater pollution.
Not specified in state regulations.
NDEQ has administrative enforcement authority and the authority to
levy a penalty.
D-60
-------
Appendix D
Program Coverage
(continued)
Nebraska Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
No
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation, program, or guidance.
Source:
Nebraska Administrative Code (NAC).
Nebraska Department of Environmental Quality (NDEQ) web page (http://www.deq.state.ne.us).
D-61
-------
Appendix D
Program Coverage
Nevada
Nevada regulates surface impoundments as part of its water program. A Surface Water
Discharge Permit is required before any discharge to surface waters or to an area where surface
waters may be affected. Permits are valid for five years.
Nevada Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Program or
Regulation
Addresses
Criteria?
No
Yes
No
Yes
No
Yes
No
Description of Regulation or Program
Not specified in state regulations.
All ponds that are intended to contain process fluids must have a
primary synthetic liner and a secondary liner. Ponds that are primarily
designed to contain excess quantities of process fluids that result from
storm events for limited periods may be constructed with a single liner
if approved by the department. Ponds containing nonprocess fluids
may be required to be lined depending on their potential to degrade
waters of the state. A tailings impoundment must utilize a system of
containment equivalent to 12 inches of recompacted native, imported,
or amended soils which have an in place recompacted coefficient of
permeability of no more than 1 x 10-6 cm/sec; or competent bedrock
or other geologic formations underlying the site that has been
demonstrated to provide a degree of containment equivalent 1 x 10"6
cm/sec. No operator who conducts oil or gas development and
production may use unlined collecting pits for storage and evaporation
of brines from the oil field. Between the liners there must be a
material which has the ability to rapidly transport any fluids entering it
to a collection point which is accessible and has a system for
recovering those fluids. When the material between the liners is
unable to collect, transport and remove all liquids at a rate that will
prevent hydraulic head transference from the primary liner to the
secondary liner, the pond must be shut down.
Not specified in state regulations.
Surface water monitoring is required for surface impoundments that
are permitted under the NPDES program.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
Not specified in state regulations.
(continued)
D-62
-------
Appendix D
Program Coverage
Nevada Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
No
Description of Regulation or Program
Not specified
Not specified
Not specified
in state regulations.
in state regulations.
in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation, program, or guidance.
Sources:
Nevada Administrative Code (NAC).
Nevada Department of Environmental Protection (NDEP) web page (http://www.state.nv.us/ndep).
D-63
-------
Appendix D
Program Coverage
New Hampshire
The responsibility for regulating surface impoundments is found in New Hampshire's
Division of Water program of the New Hampshire Department of Environmental Services. New
Hampshire is not delegated NPDES authority. EPA is responsible for implementing the NPDES
permit process in accordance with Section 402 of the CWA. The state works closely with EPA
to establish appropriate discharge limits. Prior to issuance of the NPDES permit, the state must
certify that the permit meets state water quality laws and regulations. Permits are generally
issued for five years.
New Hampshire Department of Environmental Services (DES) established regulations
regarding surface impoundments within the state. Key elements of the regulations are
highlighted below.
New Hampshire Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Program or
Regulation
Addresses
Criteria?
No
Yes
Yes
No
No
Description of Regulation or Program
Not specified in state regulations.
Plastic membrane liners must be installed in all new lagoons. Lagoon
bottoms must form a stable structure impervious to seepage of lagoon
liquid. The lagoon bottom must be smooth and level at all points.
Finished elevations must vary not more than 3 inches from the average
elevation of the bottom. Lagoons must be designed such that surface
water shall not flow or drain into the lagoons. Lagoon dikes,
embankments, and bottoms shall form a stable structure impervious to
seepage of lagoon liquid. The minimum top width of a dike or
embankment must be 8 feet to permit access by maintenance vehicles.
The embankments must have inner faces not steeper than a 3 : 1
(horizontal to vertical) slope nor shallower than a 4: 1 slope, and outer
faces not steeper than a 3 : 1 slope.
Lagoon dikes must be designed to provide a minimum of three feet of
freeboard above normal lagoon water surface elevation. The
maximum and minimum normal operating depths shall be 5 feet and 3
feet, respectively. Seeding and erosion control shall have all outside
slopes seeded and inside slopes shall have rip rap of suitable size and
weight installed to at least one foot below normal lagoon level. To
prevent erosion due to discharge at the termination of distribution
piping, the piping must rest on a concrete apron 4 feet square, as a
minimum.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-64
-------
Appendix D
Program Coverage
New Hampshire Requirements for Nonhazardous Waste Surface
Impoundments (continued)
Criteria
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
No
No
No
No
Description of Regulation or Program
State regulations give the authority to inspect, but do not specify the
frequency. Formal enforcement actions may be taken. These may
include Letters of Deficiency (LOD), Administrative Orders (AO),
Administrative Fines, Consent Agreements, or Consent Decrees. In
cases where court orders such Consent Agreements or Consent
Decrees are to be issued, a referral is made to the New Hampshire
Department of Justice. Depending on the availability of resources,
and the specifics of a case, enforcement actions may be turned over to
the EPA or performed in conjunction with EPA
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation, program, or guidance.
New Hampshire Administrative Rules.
New Hampshire Department of Environmental Services (DBS) web page (http://www.des.state.nh.us).
D-65
-------
Appendix D
Program Coverage
New Jersey
In New Jersey, responsibility for regulating and permitting surface impoundments is
consolidated in the state's water quality Section of the New Jersey Department of Environmental
Protection (NJDEP). NJDEP established guidelines for permitting of surface impoundments
within the state. State Regulations require a New Jersey Pollutant Discharge Elimination
System (NJPDES) permit for any discharge of any pollutant. NJDEP has full authority to
administer the Federal NPDES permit program and to issue general permits.
New Jersey Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
Description of Regulation or Program
NJDEP requires applicants to submit scale plan; topographic,
geologic, soil, and water table maps; a plot plan showing the
impoundment area; and a soils evaluation report. NJDEP usually
requires some type of siting or location standards. In general NJDEP
will not allow applicants to site impoundments in a 100-year
floodplain, unless the applicant proves that the impoundment will not
create a danger to health or the environment.
All surface impoundments must have a liner either of natural or man-
made material. The liners must be impervious, which is defined as
having a permeability of 10-7 cm/sec. Leachate collection and
removal systems are not usually required for nonharardous waste
surface impoundments. However, if NJDEP finds the waste
constituents to be a potential danger to human health and the
environment, a leachate collection system (e.g. underdrains) may be
required.
A minimum of 2 feet of freeboard is required. NJDEP incorporates
standards into the permit on a case-by-case basis for soil erosion and
sedimentation control. At a minimum, vegetation must be placed on
earthen dikes to prevent erosion. NJDEP incorporates standards into
the permit on a case-by-case basis. At a minimum, dikes must be
maintained to prevent failure.
NPDES permittees must comply with extensive sampling, analysis,
and water monitoring requirements, and must submit monthly
monitoring reports.
Groundwater and Surface Water: Surface impoundment
applications must include designs for groundwater and surface water
monitoring, including the proposed location and sampling procedures.
Nonharardous waste facilities must conduct groundwater quality
monitoring according to the requirements for hazardous waste
facilities, including number and type of wells, sampling and analysis
procedures, sampling parameters, etc.
(continued)
D-66
-------
Appendix D
Program Coverage
New Jersey Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
No
No
Description of Regulation or Program
Applicants must submit information on waste volume, degree of
treatment, and raw and treated effluent analyses of several parameters.
NJDEP incorporates standards into the permit on a case-by-case basis.
Permits include monthly operator inspection requirements of the liner
and dikes.
If leakage occurs, the amount of corrective measures to be taken is
contingent on the potential danger of the waste to human health and
the environment. If a low-impact leak occurs, corrective measures
may include placement of wells to monitor impact on groundwater. A
high-impact leak may require removal of the wastewater from the
impoundment, removal and replacement of liner, and soil sampling.
Permits include plans for accidents and emergencies. In the event of
an accident or an emergency, the owner/operator must be able to stop
the flow of wastewater into the impoundment, empty the
impoundment, and take other measures necessary to correct the
problem. Owner/operators must notify NJDEP in the event of dike
failure, overflow, or substantial drop in level of wastewater in pond.
The state NJPDES permit specifies regulations for impoundments
which discharge to surface or groundwater.
Not specified in state regulations.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation, program, or guidance.
NJDEP Regulations.
New Jersey Department of Environmental Protection (NJDEP) web page (http://www.state.nj.us/dep/).
D-67
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Appendix D
Program Coverage
New Mexico
In New Mexico, nonhazardous waste surface impoundments are regulated through the
New Mexico Environment Department (NMED). Surface impoundments that discharge to
groundwater must have a groundwater discharge plan approved by the NMED (maximum
duration of 5 years). Additional requirements may be imposed on surface water dischargers by
the EPA region under the NPDES program.
New Mexico Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
No
Yes
No
Case-by-case
Case-by-case
Yes
Case-by-case
Case-by-case
Case-by-case
Description of Regulation or Program
Not specified in state regulations.
State regulations require that the design of a surface impoundment
must include the site and method for flow measurement and sampling.
Not specified in state regulations.
The state agency may require monitoring as part of groundwater
discharge plan on a site-specific basis.
The state agency may require submission of monitoring results,
retention of records for 5 years, and other reporting and recordkeeping
as part of groundwater discharge plan on a site-specific basis.
State regulations give the authority to inspect, but do not specify the
frequency.
The state agency may require a site-specific contingency plan as part
of a groundwater discharge plan. The facility may be required to
modify the discharge plan (or prepare an abatement plan if the
discharge plan has expired or been terminated) if groundwater exceeds
state standards at the current or foreseeable withdrawal points; or
surface water exceeds state standards.
The state agency may require a closure plan sufficient to prevent
exceedances of state standards as part of a groundwater discharge
plan. The closure plan may include provisions for postclosure
monitoring and maintenance.
The closure plan may include requirements for financial assurance.
The allowable mechanisms are not specified in the state regulations.
(continued)
D-68
-------
Appendix D
Program Coverage
New Mexico Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulation or program.
Sources:
New Mexico Administrative Code (NMAC) Chapter 6, Part 2, Subparts III & IV.
New Mexico Environment Department (NMED) web page (http://www.nmenv.state.nm.us).
D-69
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Appendix D
Program Coverage
New York
New York requirements regarding nondischarge, nonhazardous surface impoundments
are found in the state's RCRA program under the New York State Department of Environmental
Conservation (NYDEC). Surface impoundments that discharge to waters of the state are
permitted under the water program.
For other surface impoundments, New York requires permits. Under the solid waste
regulations, surface impoundments are regulated as land application units and also are subject to
requirements for liquid storage. Permits for surface impoundments must include a description of
the liquid to be stored; the estimated volume of liquid generated and a proposed recordkeeping
system to record actual quantities stored; a schedule of liquid removal; a description of the final
treatment and disposal of the liquid stored; a description of the liquid storage facility design; and
a closure plan.
RCRA permit: Solid waste permits are valid for up to 10 years, except that permits
issued pursuant to the Clean Water Act for sewage sludge must not be issued for a period
exceeding five years.
NYPDES permit: New York is authorized to implement the federal CWA NPDES
program. Any owner/operator of a surface impoundment subject to NPDES requirements (i.e.,
discharging directly to waters of the state) must submit an NPDES permit application. NYDEC
also establishes and ensures compliance with effluent limitations or other more stringent
limitations to ensure compliance with water quality standards.
The requirements below do not apply to a facility that exclusively treats wastewater that
is regulated under the Clean Water Act.
New York Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Program or
Regulation
Addresses
Criteria?
Yes
Description of Regulation or Program
Solid waste management facilities must not be constructed or operated
in a manner that causes or contributes to the taking of any endangered
or threatened species or to the destruction or adverse modification of
their critical habitat. Siting is prohibited in agricultural land,
floodplains (unless provisions have been made to prevent the
encroachment of flood waters), or within the boundary of a regulated
wetland. Any surface impoundment must be constructed a minimum
of 5 feet above the seasonally high groundwater table, and a minimum
of 5 feet of vertical separation must be maintained between the base of
the constructed liner and bedrock. Surface impoundments must be
constructed above the 100-year flood elevation.
(continued)
D-70
-------
Appendix D
Program Coverage
New York Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
No
Description of Regulation or Program
Surface impoundments must be constructed with a liner system to
minimize percolation. Surface impoundments must be constructed
with a liner system consisting of a minimum of two liners and a
leak-detection system. The top liner must be a geosynthetic liner with
a minimum thickness equal to 60 mils. Ballast material, such as
rounded gravel or sand, that will not cause damage to the geosynthetic
liner must be placed on top of the liner to preserve liner integrity. The
lower composite liner must consist of a minimum of 2 feet of
compacted soil with a maximum coefficient of permeability of 1 x 10-
7 centimeters per second overlain by a geosynthetic liner at least 60
mils thick. The bottom of the impoundment liner system must be a
minimum of 5 feet above both the seasonal high groundwater table
and top of bedrock.
All solid waste management facilities must be constructed, operated
and closed in a manner that minimizes the generation of leachate that
must be disposed of and prevent the migration of leachate into surface
and groundwaters. Leachate must not be allowed to drain or discharge
into surface water except pursuant to a State Pollutant Discharge
Elimination System permit and must not cause or contribute to
contravention of groundwater quality standards established by the
state. A leak detection and removal system must be installed between
the two synthetic liners. Surface impoundments must have a minimum
2 feet of freeboard. Proper site grading must be maintained to prevent
depressions, desiccation cracks or soil erosion and minimize ponding.
Facilities are required to have a waste control plan as part of their
permit.
Surface and groundwater quality monitoring: Solid waste must
not be deposited in, and must be prevented from, entering surface
waters or groundwaters. Groundwater monitoring is required. A
minimum of three groundwater monitoring wells, one upgradient and
two downgradient of the surface impoundment, must be installed and
sampled. Quarterly sampling of the wells at the surface impoundment
must be conducted on the following parameters: chloride, nitrate,
sulfate, specific conductivity, total hardness, alkalinity, and total
organic carbon or chemical oxygen demand.
Samples and measurements taken for the purpose of monitoring must
be representative of the monitored activity and must be conducted in a
manner approved by the department, including the use of a laboratory
and data-reporting format acceptable to the department.
Not specified in state regulations.
(continued)
D-71
-------
Appendix D
Program Coverage
New York Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
No
Description of Regulation or Program
NYDEC is authorized to implement the RCRA solid waste
requirements by the state legislature. New York has the authority to
implement the federal CWA requirements.
Every application for a permit must include a contingency plan. For
surface impoundments, the contingency plan must address the steps
that will be taken in the event of contamination detected in the
downgradient wells or leak detection system. Contingency plans
approved by the department for emergency situations must be
implemented in accordance with the terms of the plan.
Regulations specify specific requirements for non-discharging
impoundments.
Financial assurance is required for non-discharging impoundments.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
New York Codes, Rules and Regulations (NYCRR).
New York State Department of Environmental Conservation (NYS DEC) web page (http://www.dec.state.ny.us).
D-72
-------
Appendix D
Program Coverage
North Carolina
In North Carolina, responsibility for regulating and permitting nonharardous surface
impoundments is consolidated in the Water Quality Section of the North Carolina Department of
Environment and Natural Resources (DENR). An impoundment must be covered by either a
state NPDES permit if it discharges to surface water or a state permit if it does not. The
regulations outlined in the table below apply to discharging and non-discharging facilities unless
otherwise indicated.
North Carolina Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
No
Yes
Yes
No
No
Description of Regulation or Program
State regulations require that a surface impoundment must be at least 4
feet above the seasonal water table; 50 feet from property lines rivers,
and streams; and 500 feet from dwellings and wells. Restrictions also
apply for locations near 100-year floodplains, endangered species
habitats, and historical sites and parks.
State regulations require that if waste is less than 4 feet above bedrock
there must be a liner of 10"7 hydraulic conductivity or demonstration
that the design will meet groundwater standards.
State regulations identify minimum freeboard requirements.
State regulations require that nondischargers monitor groundwater
quality, but details determined on case-by-case basis.
Not specified in state regulations.
State regulations give the authority to inspect with the frequency not
specified.
Corrective action is required if groundwater exceeds state standards at
compliance boundary (250 feet from waste boundary). Assessment
and possible preventative measures are required if groundwater
exceeds state standards at review boundary (midway to compliance
boundary).
Not specified in state regulations, but may be applied on a permit-
specific basis.
The authority to require financial assurance exists, but no specific
mechanisms are identified/required in the state regulations.
(continued)
D-73
-------
Appendix D
Program Coverage
North Carolina Requirements for Nonhazardous Waste Surface
Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Sources:
North Carolina Administrative Code (NCAC) Title 15A, Chapter 2, Subchapters 2L & 2H; Title 15A Chapter 13,
Subchapter 13B.
North Carolina Department of Environment and Natural Resources (DENR) web page
(http://h2o.enr.state.nc.us/admin/rules/).
D-74
-------
Appendix D
Program Coverage
North Dakota
In North Dakota, nonhazardous waste surface impoundments are regulated through the
Department of Health's Division of Waste Management. Impoundments must be covered by a
solid waste management permit (duration not specified in the regulations), and an NPDES permit
if discharging to surface water (duration of up to 5 years). If an impoundment has both permits
because it is a surface water discharger, the design and operating criteria specified in the solid
waste management permit regulations are not applicable.
North Dakota Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
Yes
Yes
Description of Regulation or Program
State regulations require surface impoundments to be located 1,000
feet downgradient from drinking water wells, 200 feet from surface
water or wetlands, 200 feet from surface water or wetlands, and 1,000
feet from parks. The regulations specify prohibitions for disposal
within an aquifer, wellhead protection areas, 100-year flood plains,
unstable areas, critical habitats, principal glacial drift aquifers, and
pipelines and transmission lines.
Non-discharging impoundments: Impoundments that do not
discharge to surface water must have a liner that is 4 feet thick with a
permeability of less than 10"7 or equivalent (applicable to units
permitted after December 1, 1992) and meet dike construction criteria.
Surface water discharging impoundments: Not specified in state
regulations. May be required as part of permit on a site-specific basis.
Non-discharging impoundments: Impoundments that do not
discharge to surface water must have a minimum of 2 feet of
freeboard, monthly operational inspections, and a contingency plan.
Surface water discharging impoundments: Not specified in state
regulations. May be required as part of permit on a site-specific basis.
State regulations require a measurement of quantity of waste disposed
if >20 tons per day. Semiannual groundwater monitoring of at least 1
upgradient and 2 downgradient wells is required (constituents
determined on case-by-case basis). Monitoring of compliance
boundary is required within property line no more than 500 feet from
the unit.
Semiannual groundwater monitoring results; operating records; annual
audits of financial assurance mechanisms; and annual reporting of
waste quantity and noncompliances.
State regulations give the authority to inspect, but do not specify the
frequency.
(continued)
D-75
-------
Appendix D
Program Coverage
North Dakota Requirements for Nonhazardous Waste Surface
Impoundments (continued)
Criteria
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
No
Description of Regulation or Program
Remedial measures are required if groundwater exceeds state
standards or other permit limits at compliance boundary.
State regulations require a closure plan. Closure in place is allowed if
liquids are removed, impoundment is lined with low-permeability
material (applicable to units permitted after December 1, 1992), a final
cover is installed with vegetation and a permeability less than the liner,
run-on and erosion controls are installed, and postclosure monitoring
is conducted.
A reserve account, trust fund, surety bond, irrevocable letter of credit,
financial test insurance policy, or corporate guarantee is required for
closure, postclosure, and corrective action (for facilities closed after
April 9, 1994).
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or program.
North Dakota Century Code (NDCC) Chapters 23-29 & 33-20.
North Dakota Department of Health (NDHD) web page
(http://www.health.state.nd.us/ndhd/environ/wm/index.htm).
D-76
-------
Appendix D
Program Coverage
Ohio
The Permits Section in the Division of Water Pollution Control of the Ohio
Environmental Protection Agency (OEPA) oversees the regulations and permits regarding
nonharardous waste surface impoundments. The regulatory program related to surface
impoundments has two components: the permit to install (valid for life of the facility) and the
NPDES permit for discharges to surface water or groundwater (valid for up to 5 years).
Ohio Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
No
No
No
No
Yes
Yes
Yes
No
No
Description of Regulation or Program
Not specified in state regulations, but may be required as part of a
permit on a site-specific basis.
Not specified in state regulations, but may be required as part of a
permit on a site-specific basis.
Not specified in state regulations, but may be required as part of a
permit on a site-specific basis.
Not specified in state regulations, but may be required as part of a
permit on a site-specific basis.
State regulations require monthly and annual reports with information
as specified in the permit. If applicable, reports of monitoring are
required at least annually.
State regulations give the authority to inspect, but do not specify the
frequency.
State regulations require compliance with applicable effluent
limitations, water quality standards, and standards which prohibit
significant degradation of waters of the state. Specific enforcement
mechanisms, however, are not specified in the regulations.
Not specified in state regulations, but may be required as part of a
permit on a site-specific basis.
Not specified in state regulations, but may be required as part of a
permit on a site-specific basis.
(continued)
D-77
-------
Appendix D
Program Coverage
Ohio Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Sources:
Ohio Regulations: Ohio Administrative Code (OAC) 3745-31; 3745-33.
Ohio Environmental Protection Agency (OEPA) web page (http://www.epa.state.oh.us).
D-78
-------
Appendix D
Program Coverage
Oklahoma
In Oklahoma, nonhazardous waste surface impoundments are regulated through the
Oklahoma Department of Environmental Quality (ODEQ) under its water program. A State
Operation Permit is required for all impoundments (valid for up to 5 years), while a state NPDES
permit is required for discharges to surface water or groundwater (valid for up to 5 years).
The state regulations establish five classes of surface impoundments with little difference
in the regulatory requirements for each class. The determination of impoundment class is at the
discretion of the permit writer. In general, Classes I and n contain wastes with high
concentrations of harmful pollutants with (I) high or (n) low mobility in groundwater; Class in
contains wastes with other pollutants that may, if discharged, pollute the environment or waters
of the state; Class IV contains sanitary wastewater; and Class V contains industrial wastewater
not otherwise classified. The regulations outlined in the table below apply to all classes of
impoundments unless otherwise indicated.
Oklahoma Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Case-by-case
Yes
Description of Regulation or Program
The state regulations specify the following location/siting standards:
Not in floodways or floodplains
50 feet from private wells
300 feet from public water supplies
10 feet from property lines
Crest of dikes must be at least 1 foot above 100-year flood
elevation
Bottom of impoundment must be 15 feet above groundwater table
The state regulations specify the following design standards:
• Run-on/run-off controls
• Erosion controls
Dike slopes no steeper than 1:3
Liner system (native soil, compacted clay with 12 inches of soil,
flexible membrane liner with protective soil cover, or composite
liner) depending on class of impoundment
The state regulations specify a minimum of 3 feet of freeboard. In
addition, a written Maintenance and Operation Plan is required for
Classes I and II only.
Groundwater monitoring may be required when there is a potential for
groundwater contamination. If required, there must be 1 upgradient
and 2 downgradient wells, and a detailed monitoring plan must be
submitted.
The state regulations require submission of Self -Monitoring Report
forms and reports of spills or releases.
(continued)
D-79
-------
Appendix D
Program Coverage
Oklahoma Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
No
Description of Regulation or Program
State regulations give the authority to inspect, but do not specify the
frequency.
The state regulations require conformance to applicable water quality
standards.
The state regulations require the submission of a preclosure sampling
and analysis plan, and a closure plan. In addition, caps must be
installed in conformance with liner requirements. The state agency
may require submission of a postclosure maintenance plan on a case-
by-case basis. A postclosure duration is not specified in the state
regulations.
The state regulations stipulate that the owner/operator of the
impoundment must demonstrate financial capability for operation,
maintenance, replacement, and closure. The types of mechanisms and
duration are not specified in the state regulations.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Oklahoma Agency Rules (OAR) 252-605 & 252-616.
Oklahoma Department of Environmental Quality (ODEQ) web page (http://www.deq.state.ok.us).
D-80
-------
Appendix D
Program Coverage
Oregon
In Oregon, the responsibility for regulating and permitting nonharardous surface
impoundments is divided between the Water Quality Program and the Recycling and Solid Waste
Program of the Oregon Department of Environmental Quality. The RCRA program
requirements provide a general basis for surface impoundment regulations. Additional facility-
specific requirements may be added to permits.
All sources that discharge wastewater to surface waters of the state must obtain a NPDES
permit. Sources that discharge wastes into a sewerage system do not have to obtain a permit.
General requirements require effluent and discharge limitations, recordkeeping, monitoring and
reporting, and operation and maintenance responsibilities.
Along with a NPDES permit, facilities containing land irrigation systems, evaporation
lagoons, industrial seepage pits, and on-site sewage disposal systems designed for wastewater
flows greater than 2,500 gallons per day that have no direct discharge to surface waters are
required to obtain a water pollution control facility permit.
Some facilities are required to obtain a storm water permit dependent on the facility's
industrial activity.
A facility is required to obtain a solid waste permit prior to operation if it plans to store,
receive, or landfill any garbage, demolition waste, industrial waste, or sludge. Typical
requirements of these permits generally include the use of "best management practices" to
prevent contamination of the surrounding environment.
Oregon Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Program or
Regulation
Addresses
Criteria?
Yes
Description of Regulation or Program
Location of disposal sites shall be determined by giving special
consideration to the topography and geology of the surrounding area
as well as other characteristics as they may affect the protection of
ground and surface waters and air pollution. All industrial solid waste
impoundments shall be located a minimum of 100 feet horizontal
distance from the normal highwater mark of any public waters. All
sludge lagoons shall be located a minimum of 1/4 mile from the
nearest residence. Barriers shall be constructed to prevent public
access to the facility.
(continued)
D-81
-------
Appendix D
Program Coverage
Oregon Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Description of Regulation or Program
All surface impoundments must include a readily washable landfill-
type liner with a leachate removal system. The liner must demonstrate
both physical and chemical compatibility with the waste being stored.
Liners must be impervious to damage suck as cracks and leaks. A
concrete slab is not considered an acceptable liner. The impoundment
shall also have a tight lid or cover. All impoundments are required to
have a leachate removal system incorporated with a liner unless the
facility contains a vadose monitoring system. Some facilities may be
required to incorporate such physical features as dikes and berms into
the design criteria for the impoundment.
Each facility is to ensure that surface runoff and leachate seeps are
controlled as to minimize discharge of pollutants to public waters. A
minimum of 3 feet of dike freeboard shall be maintained above the
maximum water level within a sludge lagoon. It is required that all
facilities dispose of nonharardous sludge.
Groundwater: The department and/or solid waste permits may
require a groundwater monitoring system dependent on the type of
waste contained in the impoundments and the facility's cover, run-on
controls and irrigation system.
Surface Water: NPDES requirements include surface water
monitoring, analysis, and recordkeeping and reporting.
The state solid waste storage permit specifies reporting and
recordkeeping requirements.
All nonharardous waste producing facilities are required to grant
inspection authority to the appropriate implementing agency. The
terms of these inspections are permit specific for each facility. The
Environmental Quality Commission has the authority to take the
necessary appropriate actions to ensure the enforcement of its rules or
orders, as well as, levy both criminal and civil penalties against a
facility.
The state solid waste storage permit specifies that corrective action is
required if necessary.
The state solid waste storage permit specifies that closure/postclosure
care is required.
The state solid waste storage permit specifies that financial care is
required.
(continued)
D-82
-------
Appendix D
Program Coverage
Oregon Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation, program, or guidance.
Sources:
Oregon Administrative Rules (OAR).
Oregon Department of Environmental Quality web page (http://www.deq.state.or.us).
D-83
-------
Appendix D
Program Coverage
Pennsylvania
Pennsylvania Department of Environmental Resource (PADEP) regulates surface
impoundments based on their type and establishes design and operating requirements based on
the nature of the waste being managed.
In Pennsylvania, responsibility for regulating and permitting nonharardous surface
impoundments is delegated between the state's Division of Water Quality, responsible for the
NPDES program for discharging impoundments, and the Division of Municipal and Residual
Waste, responsible for managing disposal and processing impoundments under the residual waste
program.
Operators of disposal surface impoundments must obtain a Residual Waste Disposal
Permit, and a Water Quality Management Permit Part I (i.e., NPDES permit) if the impoundment
will discharge to waters of the state. A "disposal" impoundment is one that stores waste for more
than 1 year without regularly removing the waste. Disposal impoundments are classified into
two types, the only difference in requirements being the type of liner system:
Type 1: Wastes with TCLP >50 times Federal MCLs
Type 2: Wastes with TCLP <50 times Federal MCLs.
Operators of captive processing surface impoundments must abide by the residual waste
Permit-by-Rule regulations, and must obtain a Water Quality Management Permit Part I (i.e.,
NPDES permit) if the impoundment will discharge to waters of the state.
The residual waste regulations for the Permit-by-Rule and Residual Waste Disposal
Permit address all the criteria listed in the table below. The table includes the regulatory
requirements under the Residual Waste Disposal Permit-some requirements are less stringent
under the Permit-by-Rule regulations.
Pennsylvania Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Description of Regulation or Program
The residual permit regulations specify restrictions for 100-year
floodplains, wetlands, sinkhole-prone limestone and carbonate
formations, perennial streams, property lines, and nearby water
sources.
The residual permit regulations specify requirements for liners,
leachate detection and collection, structural integrity, and run-on/run-
off controls.
(continued)
D-84
-------
Appendix D
Program Coverage
Pennsylvania Requirements for Nonhazardous Waste Surface
Impoundments (continued)
Criteria
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Description of Regulation or Program
The residual permit regulations specify minimum freeboard
requirements, separation of liquids from solid waste, and solidification
of waste times.
The residual permit regulations require a monitoring plan and
upgradient and downgradient groundwater monitoring within 200 feet
of disposal area. Regulations require that indicators shall be
monitored quarterly, and metals and VOCs shall be samples annually.
The residual permit regulations require annual waste quantity and
disposition reports; quarterly groundwater results; and daily, quarterly
and annual operational reports. These records must be maintained for
the entire length of the bond held for that facility.
The residual permit regulations allow PADER to conduct up to
12 inspections per year. However, there is no established minimum
number of inspections per year for any given facility.
The residual permit regulations require abatement if: groundwater
exceeds permit-specific trigger levels, groundwater exceeds state
standards, groundwater exceeds background where background is
greater than state standards, or degradation of groundwater at property
boundaries.
The residual permit regulations require an approved closure plan that
includes plans for caps, leachate management, and revegetation.
There is no postclosure period specified by the regulations.
The residual permit regulations stipulate that a surety bond, collateral
bond, letter of credit, certificate of deposit, or combination thereof
must be maintained for a duration of 10 years after final closure along
with public liability insurance.
The state regulations require all owners/operators of surface
impoundments to implement fugitive air contaminant control
measures. If the waste managed at the facility generates gas, the
operator must monitor quarterly off-site gas migration and gas
accumulation on and off the site.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Pennsylvania Code (PAC) Chapters 92, 287, 289.
Pennsylvania Department of Environmental Protection (P ADEP) web page
(http://www.dep.state.pa. us/business_industry/default. htm).
D-85
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Appendix D
Program Coverage
Rhode Island
Rhode Island requires a state NPDES permit for discharges to surface and groundwater,
administered by the Division of Water Resources in the Department of Environmental
Management, but does not further regulate nonhazardous waste surface impoundments. If an
impoundment has a liner and doesn't not leach or overflow, an NPDES permit is not necessary,
but the liner is not required.
Rhode Island Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
No
No
No
Yes
No
No
No
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Source:
Rhode Island Administrative Rules 12-190 et seq.
D-86
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Appendix D
Program Coverage
South Carolina
The Bureau of Water Pollution Control under the South Carolina Department of
Environmental Control administers the programs concerning nonhazardous waste surface
impoundments. Surface impoundments must be covered either by a state NPDES permit (if
discharge to surface or groundwater), or a nondischarge permit. In addition, construction and
operation permits need to be obtained if an impoundment exceeds wastestream limitations.
South Carolina Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
No
No
Yes
No
No
Yes
Yes
No
No
Description of Regulation or Program
Not specified in state regulations.
Not specified in state regulations. Under non-discharge permit,
determined on a case-by-case basis.
Not specified in state regulations. Under non-discharge permit,
determined on a case-by-case basis.
Non-discharge permits require groundwater monitoring
Not specified in state regulations.
Not specified in state regulations.
Non-discharge permits require the facility's groundwater monitoring
system to meet state groundwater standards.
State regulations specify closure guidelines and require monitoring on
case-by-case basis as necessary to prevent water quality violations or
nuisance conditions.
Not specified in state regulations.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Source:
South Carolina Regulations Title 61-9 and 61-82.
D-87
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Appendix D
Program Coverage
South Dakota
South Dakota's Department of Environment and Natural Resources administers the
programs regulating nonhazardous waste surface impoundments. Such impoundments are
subject to water, solid waste, and air regulations. Required permits include a solid waste facility
permit, a state NPDES permit for discharges to surface or groundwater, and a state groundwater
discharge permit for discharges to groundwater. In addition, the Department has published
non-regulatory design criteria for wastewater stabilization and pollution control ponds, and
aerated ponds.
South Dakota Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Yes
Case-by-case
Yes
Yes
Case-by-case
Yes
Yes
Yes
Yes
Description of Regulation or Program
Solid waste permit regulations specify that impoundments can not be
located in a 100-year floodplain, wetlands, or unstable areas. They
also cannot be located within 1,000 feet of dwelling, school, hospital,
interstate, highway, or public park. If surface waters can be polluted,
not within 1,000 feet of surface waters.
Solid waste permit regulations state that a liner and leachate collection
system may be required.
Solid waste permit regulations specify operating criteria for
impoundments as appropriate.
Groundwater monitoring required under solid waste and groundwater
discharge permit regulations, and may be required by a state NPDES
permit.
Solid waste permit regulations and groundwater discharge permit
regulations state that the reporting and recordkeeping requirements are
those as specified in the permits by the permit writer.
State regulations give the authority to inspect, but do not specify the
frequency.
Solid waste permit regulations and groundwater discharge permit
regulations require meeting groundwater quality standards. The
groundwater discharge permit also requires a contingency plan for
bringing the facility into compliance with such standards.
Solid waste permit regulations require closure and postclosure plans,
and specify some criteria to be addressed in the plans.
Solid waste permit regulations require financial assurance mechanisms
for closure/postclosure care, such as trust fund, surety bond, letter of
credit, insurance, or cash.
(continued)
D-88
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Appendix D
Program Coverage
South Dakota Requirements for Nonhazardous Waste Surface
Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes:
No:
Case-by-case:
Source:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
South Dakota Regulations Title 74, Articles 74-27, 74-52, and 74-54.
D-89
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Appendix D
Program Coverage
Tennessee
The responsibility for regulating and permitting surface impoundments is held by the
Tennessee Department of Health and Environment. Under this Department, the Division of
Water Quality and the Division of Solid Waste Management enforce the regulations and oversee
closure of surface impoundments, respectively.
Three sets of regulations apply to nonhazardous waste surface impoundments.
State NPDES permit is required for dischargers to surface or groundwater (valid for up to
5 years).
• State Operation Permit is required for nondischargers (valid for up to 5 years).
• If closing with waste in place, solid waste regulations for Class VI Disposal Facilities
apply (to facilities in operation on or after March 19, 1990), but a Solid Waste Processing
and Disposal Permit is not required.
Tennessee Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Program or
Regulation
Addresses
Criteria?
No
No
No
Case-by-case
No
Yes
Yes
Description of Regulation or Program
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Monitoring requirements are determined on a case-by-case basis and
specified in applicable permits.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
The operator must comply with applicable effluent standards,
limitations, and water quality standards. Specific enforcement
mechanisms are not specified in the regulations.
(continued)
D-90
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Appendix D
Program Coverage
Tennessee Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
No
Description of Regulation or Program
If closing with waste in place, closure/postclosure plans are required,
but specific details of the plans are not specified in the state
regulations.
If closing with waste in place, state regulations require a trust fund,
surety bond, personal bond, letter of credit, insurance, financial test,
and corporate guarantee for closure and postclosure care of an
impoundment.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Sources:
Tennessee Code Annotated (TCA) 1200-1-7 & 1200-4-10.
Tennessee Department of Environment and Conservation (TDEC) web page (http://www.state.tn.us/environment).
D-91
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Appendix D
Program Coverage
Texas
The Waste Permits Division and the Water Permits & Resource Management Division,
under the Office of Permitting, Remediation & Registration of the Texas Natural Resource
Conservation Commission (TNRCC), are responsible for permitting nonharardous waste surface
impoundments.
Both solid waste and water quality regulations apply to surface impoundments. Facilities
that discharge into or adjacent to surface water or groundwater must obtain a State Water Quality
Permit. A solid waste management permit is not required, but facilities must notify the TNRCC
with information including waste composition, facility design, and geology. The specific
regulations and guidelines for surface impoundments are largely determined on a case-by-case
basis and are found in each individual facility's permit.
Texas Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Program or
Regulation
Addresses
Criteria?
No
No
No
Yes
Yes
Yes
Yes
Description of Regulation or Program
Not specified in state regulations, but may be required as part of a
Water Quality Permit on a site-specific basis.
Not specified in state regulations, but may be required as part of a
Water Quality Permit on a site-specific basis.
Not specified in state regulations, but may be required as part of a
Water Quality Permit on a site-specific basis.
Waste characterization and surface-water discharge monitoring are
required by state regulations. Groundwater monitoring may be
required as part of Water Quality Permit on a site-specific basis.
State regulations require the maintenance of records of quantity of
waste generated, disposition of waste, and waste characteristics.
State regulations authorize the state to audit records and to inspect
dischargers (frequency not specified in the regulations).
The regulations stipulate that waste disposal may not cause a nuisance
or endanger public health and welfare. They also state that
dischargers must comply with state water quality standards. In
addition, groundwater degradation is not allowed, although specific
enforcement mechanisms are not specified in regulations beyond the
authority to issue emergency orders.
(continued)
D-92
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Appendix D
Program Coverage
Texas Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
No
No
Description of Regulation or Program
The state regulations state that the decision to close a surface
impoundment is at the operator's discretion and that prior notification
of TNRCC is required.
Closure must be in a manner that is compliant with the risk-based
standards of the Texas Risk Reduction Program:
Minimize or eliminate postclosure escape of waste, contaminants,
leachate, or run-off.
Minimize or eliminate the need for further maintenance and
control
Specific closure controls and activities are not specified in
regulations
Not specified in state regulations, but may be required as part of a
Water Quality Permit on a site-specific basis.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Texas Administrative Code (TAG).
Texas Natural Resource Conservation Commission (TNRCC) web page (http://www.tnrcc.state.tx.us).
D-93
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Appendix D
Program Coverage
Utah
In Utah, the Utah Department of Environmental Quality's Division of Water Quality is
responsible for regulating and permitting nonhazardous surface impoundments. Utah regulations
require owners/operators obtain a construction permit prior to building storage or treatment
surface impoundments (valid for one year). In addition, dischargers to surface water or
groundwater must obtain a state NPDES permit (valid for up to five years), and dischargers or
potential dischargers to groundwater must also obtain a state groundwater permit (valid for up to
five years).
Utah Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
No
No
No
Yes
No
Yes
Yes
No
No
Description of Regulation or Program
Not specified in state regulations, but may be required in a permit on a
site-specific basis.
Not specified in state regulations, but may be required in a permit on a
site-specific basis.
Not specified in state regulations, but may be required in a permit on a
site-specific basis.
State regulations require groundwater monitoring; however,
monitoring details are determined on a site-specific basis and are
included in the groundwater permit.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
State regulations require a contamination investigation and corrective
action plan if monitoring indicates violation or possible violation of
water quality standards.
Not specified in state regulations, but may be required in a permit on a
site-specific basis.
Not specified in state regulations, but may be required in a permit on a
site-specific basis.
(continued)
D-94
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Appendix D
Program Coverage
Utah Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Sources:
Utah Administrative Rules (UAR) 317-1; 317-6; 317-8.
Utah Department of Environmental Quality (UDEQ) web page (http://www.deq.state.ut.usX
D-95
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Appendix D
Program Coverage
Vermont
Vermont's Department of Environmental Conservation under the Agency of Natural
Resources is responsible for overseeing the regulations regarding nonhazardous waste surface
impoundments. Vermont requires discharge (to surface water) and indirect discharge (to
groundwater) permits for all impoundments with discharges. Storage surface impoundments are
also subject to solid waste regulations. However, "wastewater treatment lagoons and digesters"
are exempt from the solid waste regulations if they are covered by a discharge and/or indirect
discharge permit. In addition, there are dam safety regulations that apply to industrial lagoons
greater than 50,000 cubic feet.
Vermont Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
No
Yes
No
Description of Regulation or Program
The state solid waste regulations specify siting requirements with
minimum isolation and separation distances from drinking water
sources and property lines.
The state solid waste regulations include design standards such as 5
months minimum storage capacity, standards for synthetic or clay
liners, and freeboard requirements
The owner and operator shall take all steps necessary to prevent and/or
control spills, nuisance dust, vectors, wind blown debris, and odors.
The owner and operator shall take all practicable steps to prevent the
inclusion of hazardous wastes, as defined and regulated by Vermont's
Hazardous Waste Management Regulations, into the waste stream
being managed by the facility.
Groundwater monitoring required by indirect discharge permit and
may be required under solid waste regulations.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
Not specified in state regulations.
(continued)
D-96
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Appendix D
Program Coverage
Vermont Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
No
No
Description of Regulation or Program
The closure plan must identify steps necessary to completely close the
facility at any point during its intended life. The closure plan must
include, at least a description of the steps necessary to close the
facility; a listing of labor, materials, and testing necessary to close the
facility; an estimate of the expected year of closure; a schedule for
final closure including, at a minimum, the total time required to close
the facility and the time required for the various steps or phases in the
closure process; a cost estimate for facility closure that satisfies the
requirements of Section 6-1004; a description of the methods for
compliance with the closure requirements; and any remedial action
necessary prior to closure, if required by the Secretary pursuant to
Section 6-3 11.
Not specified in state regulations.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Vermont Administrative Code Chapters 6 and 13.
Vermont Agency of Natural Resources web page (http://www.anr.state.vt.us/dec/dec.htm).
D-97
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Appendix D
Program Coverage
Virginia
The Water Division of the Virginia Department of Environmental Quality administers the
permit program pertaining to nonhazardous waste surface impoundments. Lagoons and surface
impoundments are regulated under state water control law and by agencies other than the
Department. Impoundments must be covered either by a state NPDES permit if it discharges
directly to surface waters, or a Virginia Pollution Abatement (VPA) permit if it does not.
Virginia Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Case-by-case
Case-by-case
Case-by-case
Yes
No
Yes
No
Yes
Yes
No
Description of Regulation or Program
Determined on a site-specific basis in VPA permit.
Determined on a site-specific basis in VPA permit.
Determined on a site-specific basis in VPA permit.
Groundwater monitoring is required under the VPA permit.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
Not specified in state regulations.
Applies only if closure with waste left in place.
Applies only if closure with waste left in place.
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Sources:
Virginia Administrative Code - Title 9 VAC 25.
Virginia Department of Environmental Quality web page (http://www.deq.state.va.us/).
D-98
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Appendix D Program Coverage
Washington
The responsibility for regulating and permitting surface impoundments in the state of
Washington is administered by the Washington Department of Ecology (DE). The department
that actually regulates surface impoundments is dependent on the type of waste handled and
whether the impoundment discharges to a water of the state. The Solid and Hazardous Waste
Program (SHWP) and Jurisdictional Health Department regulate impoundments handling
dangerous and nonharardous wastes that do not discharge to a water of the state. All
impoundments handling nonharardous waste that discharge to waters of the state are regulated by
the Water Quality Program (WQP). State RCRA requirements are located in the Water Pollution
Control Act and the Solid Waste Management Act and are described in detail below.
Impoundments managing dangerous wastes are required to have a dangerous waste
permit, which are issued by the SHWP.
Solid Waste Facility Permit: Impoundments that handle nondangerous waste, but do not
discharge into waters of the state are required to obtain a Solid Waste Facility Permit. Permits
are not required if the impoundment obtains a state waste discharge permit. Permits are issued
by the Jurisdictional health departments.
State Waste Discharge Permit: Surface impoundments that discharge to groundwater, or have the
potential to discharge to groundwater and/or impair groundwater quality, must obtain a state
waste discharge permit. Permits are issued by WQP.
State NPDES Permit: Surface impoundments that have a point source discharge to surface water
must obtain a state NPDES permit. Permits are issued by WQP.
Construction Permits: Surface impoundments handling more than 10 acre-feet of water must
obtain dam safety approval and a construction permit from WPR. Construction permits ensure
that the impoundment will remain intact throughout its life and will not threaten human health or
the environment. Criteria include requirements for dikes and berms and freeboard limits.
The states regulatory and management guidelines for surface impoundments depend on
the type of waste managed in the impoundment and whether the impoundment discharges to
waters of the state.
D-99
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Appendix D
Program Coverage
Washington Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Description of Regulation or Program
Surface Impoundments Discharging Non-Dangerous Waste to
Waters of the State: Not specified in state regulations.
Surface Impoundments Managing Dangerous and Non-
Dangerous Waste, But Not Discharging to Waters of the State:
Impoundments managing dangerous waste must not be located within
a 500-year floodplain or in areas having a mean annual precipitation
greater than 100 inches and must comply with restrictions concerning
proximity to faults, public water sources, wetlands, critical habitats,
and depth to groundwater.
Surface Impoundments Discharging Non-Dangerous Waste to
Waters of the State: Permit conditions for waste discharges may
include requirements for liners to protect the beneficial uses of
groundwater by specifying.
Surface Impoundments Managing Dangerous and Non-
Dangerous Waste, But Not Discharging to Waters of the State:
Surface impoundments must have an in place or imported soil liner of
at least 2 feet of 1 x 10 -7 cm/sec permeability or an equivalent
combination of any thickness greater than 2 feet and a greater
permeability to protect the underlying aquifers or a 30 mil reinforced
artificial liner. DE may exempt the operator from the liner
requirement if an alternate design will prevent migration of pollutants
into ground and surface waters. Surface impoundments must have
either a groundwater monitoring system that is consistent with permit
regulations, or a leachate detection, collection and treatment system,
for facilities having a capacity of more than two million gallons unless
the jurisdictional health department and the DE require either for
smaller surface impoundments. Impoundments managing dangerous
wastes must have dikes with slopes as to maintain the structural
integrity under conditions of a leaking liner and must be capable of
withstanding erosion from wave action.
(continued)
D-100
-------
Appendix D
Program Coverage
Washington Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Operating Criteria
Program or
Regulation
Addresses
Criteria?
Yes
Description of Regulation or Program
Surface Impoundments Discharging Non-Dangerous Waste to
Waters of the State: Permit conditions for waste discharge permits
and NPDES permits may require prevention and control of pollutant
discharges from plant site run-off. NPDES and state waste discharge
permits contain conditions to prevent and control pollutant discharges
from sludge disposal.
Surface Impoundments Managing Dangerous and Non-
Dangerous Waste, But Not Discharging to Waters of the State:
Impoundments managing dangerous waste must have the freeboard
equal to or greater than 18n inches to avoid overtopping from wave
action, overfilling, or precipitation. In addition, impoundments should
be designed and operated to prevent overtopping and designed so that
any flow of waste into the impoundment can be shut off should
overtopping or linear failure occur. Impoundments managing
dangerous waste must have earthen dikes with a protective cover to
minimize wind and water erosion. Dangerous wastes must not be
stored in an impoundment for more than 5 years after the waste is first
placed in the impoundment. Operators of impoundments managing
dangerous waste must perform weekly inspections. In addition,
operators must inspect the facility after each storm event to detect any
deterioration to dikes and containment devices, malfunction of
overtopping
(continued)
D-101
-------
Appendix D
Program Coverage
Washington Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Program or
Regulation
Addresses
Criteria?
Yes
No
Yes
Description of Regulation or Program
Surface Impoundments Discharging Non-Dangerous Waste to
Waters of the State:
Groundwater: Waste discharge permits must contain any monitoring
requirements specified by the DE, including any applicable
requirements under the federal CWA.
Surface Water: NPDES permits are subject to monitoring
requirements as determined by DE. The monitoring requirements
include: flow, pollutants subject to reduction or elimination under the
permit, pollutants that may have adverse impact on human health and
the environment, and pollutants specified by the DE.
Waste Analysis: DE requires NPDES permitees to monitor intake
water, influent to treatment facilities, internal waste streams, and/or
receiving waters when determined necessary.
Surface Impoundments Managing Dangerous and Non-
Dangerous Waste, But Not Discharging to Waters of the State:
Groundwater: Operators of impoundments managing dangerous
waste and having a capacity of more than two million gallons must
implement a groundwater monitoring program to detect releases to the
groundwater. The jurisdictional health departments may require a
groundwater monitoring program for facilities with less than two
million gallons capacity.
Waste Analysis Requirements: Operators of impoundments
managing dangerous wastes must perform a chemical, physical and/or
biological analysis of each dangerous waste that is stored, treated or
disposed. The analysis may consist of existing data or data obtained
via testing.
Not specified in state regulations.
Inspections: DE is authorized to inspect facilities having a state waste
discharge and NPDES permits. Jurisdiction health departments to
inspect solid waste facility permittees.
Enforcement/Penalties: DE has administrative, civil, and criminal
enforcement authority, including the authority to levy penalties.
Penalties for violations to waste discharge and NPDES permits are
$10,000 per day of violation.
(continued)
D-102
-------
Appendix D
Program Coverage
Washington Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
No
Description of Regulation or Program
Surface Impoundments Discharging Non-Dangerous Waste to
Waters of the State: Not specified in state regulations.
Surface Impoundments Managing Dangerous and Non-
Dangerous Waste, But Not Discharging to Waters of the State:
Operators of impoundments managing dangerous waste must maintain
a contingency plan at the facility in case of facility failure.
Impoundments managing dangerous waste, but not discharging to
waters of the state and impoundments Managing nondangerous waste,
but not discharging to waters of the state have specific regulations
requiring closure/postclosure care.
Impoundments managing dangerous waste, but not discharging to
waters of the state have specific requirements for financial assurance.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the states regulation or program.
Washington Administrative Code (WAC).
Washington Department of Ecology (DEC) web page (http://www.ecv.wa.govX
D-103
-------
Appendix D
Program Coverage
West Virginia
The Office of Water Resources of the West Virginia Department of Environmental
Protection is responsible for permitting and enforcement of nonhazardous waste surface
impoundments.
All nonhazardous waste surface impoundments at industrial facilities are subject to the
applicable solid waste regulations for Class F (i.e., industrial) Solid Waste Facilities and a solid
waste facility permit must be obtained. These regulations are not applicable to surface
impoundments in existence on or before May 1, 1990 which are operating under a state NPDES
permit, except that all such impoundments are required to have an adequate groundwater
monitoring system in place.
The Groundwater Protection Rule also applies and is addressed in the regulatory
provisions for the solid waste permit.
Finally, a state NPDES permit is required for discharges to surface water and
groundwater.
West Virginia Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
Yes
No
Description of Regulation or Program
State regulations specify that surface impoundments must be located at
least 5 feet above the groundwater table and must maintain a distance
of 4 feet between liner and bedrock. The facilities also must comply
with restrictions for natural wetlands and endangered species.
The state regulations require a composite liner (18-inch compacted
clay, 60 mil HDPE) and a leachate detection and collection system.
Freeboard requirements are specified in the regulations (minimum of 2
feet).
Groundwater/Leachate: Regulations specify that a minimum of three
groundwater monitoring wells are required, one up-gradient and two
down -gradient of any surface impoundment. Baseline and
background monitoring must be completed along with semiannual
monitoring for conventional parameters and metals. Daily monitoring
of flow rate and volume, and semiannual testing for conventional
parameters and metals for leachate must also be completed.
Not specified in state regulations.
(continued)
D-104
-------
Appendix D
Program Coverage
West Virginia Requirements for Nonhazardous Waste Surface
Impoundments (continued)
Criteria
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
No
No
Description of Regulation or Program
The DEP is authorized to inspect any facility, but the frequency is not
specified in the regulations.
Expansion of monitoring if statistically significant increase in one or
more groundwater parameters. Corrective action assessment required
if:
evidence of groundwater contamination
significant increase in a Phase II monitoring parameter
groundwater exceeds state standards
Closure and postclosure plans are required by the regulations. The
plans must include final cover (details not specified by the regulations)
and revegetation. Additional requirements determined on a case-by-
case basis.
The regulations do not require financial assistance for non-commercial
facilities.
Not specified in state regulations.
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
West Virginia Solid Waste Regulations (WVSWR) Titles 33-1; 47-10; 47-58.
West Virginia Department of Environmental Protection (WVDEP) web page
(http://www.dep.state.wv.us/offices.html).
D-105
-------
Appendix D
Program Coverage
Wisconsin
Responsibility for surface impoundments resides with the Wisconsin Department of
Natural Resources Division of Water if the surface impoundment discharges to waters of the
state and has a Wisconsin Pollutant Discharge Elimination System (WPDES) permit. If the
surface impoundment does not have a WPDES permit and is designed for the disposal of solid
waste, it is subject to solid waste regulations. The solid waste regulations require a permit, a
closure plan, and, on a case-by-case basis, proof of financial responsibility for closure of the
impoundment.
Wisconsin Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Program or
Regulation
Addresses
Criteria?
Yes
Yes
No
Case-by-case
No
Yes
Description of Regulation or Program
For WPDES permitted impoundments: The regulations stipulate
that the impoundment may not be located 1,000 feet from a well
serving a community public water supply system, 250 feet from other
potable water supplies, or 500 feet from an inhabited dwelling, in a
floodway, or in a wetland. In addition, a separation of 5 feet is
required between the bottom of the impoundment and either bedrock
or groundwater table, whichever is higher.
For WPDES permitted impoundments: Natural soil materials, soil-
bentonite mixtures, or synthetic liners may be used. The bottom must
be compacted to a depth of 6 inches, and an additional inorganic layer
to protect the liner may be required. The permeability of a soil or soil-
bentonite liner may not exceed 10"7. Specific requirements for oil,
soil-bentonite, and synthetic liners are provided in the regulations.
Synthetic liners must be at least 30 mils thick. Water losses from
impoundment may not exceed 500 gallons per acre per day.
Not specified in state regulations, but may be applied on a permit-
specific basis.
Groundwater monitoring may be required on a case-by-case basis
under either a WPDES or solid waste permit.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency.
(continued)
D-106
-------
Appendix D
Program Coverage
Wisconsin Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Case-by-case
No
Description of Regulation or Program
For solid waste permitted impoundments: The regulations stipulate
that facilities may not cause a detrimental effect on any surface or
groundwater or exceedances of water quality standards, significant
adverse impact on wetlands or critical habitat areas, or emissions of
any hazardous air contaminant exceeding the limitations for those
substances.
For solid waste permitted impoundments: The regulations require a
closure plan. Postclosure groundwater monitoring may be required on
a site-specific basis.
For solid waste permitted impoundments: The regulations state that
financial assurance may be required on a site-specific basis.
Not specified in state regulations
Yes:
No:
Case-by-case:
Sources:
Regulation or program addresses criteria.
There is no specific state regulation or program that addresses the criteria.
The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Wisconsin Administrative Code (WAC) Chapters 213 and 502.
Wisconsin Department of Natural Resources (WDNR) web page (http://www.dnr.state.wi.us/).
D-107
-------
Appendix D
Program Coverage
Wyoming
In Wyoming, responsibility for regulating and permitting surface impoundments is
consolidated in the Wyoming Department of Environmental Quality's Water Quality Division.
Industrial nonhazardous waste surface impoundments must be covered by a Permit to Construct,
Install, Modify or Operate, and a state NPDES discharge permit (if discharging to surface water).
The applicable regulations for the Permit to Construct are found under the nonbiological
treatment ponds section. The summary table contains these standards.
Wyoming State Requirements for Nonhazardous Waste Surface Impoundments
Criteria
Location or Siting
Standards
Design Criteria (liner,
leachate collection)
Operating Criteria
Monitoring
Reporting and
Recordkeeping
Inspection and
Enforcement
Performance
Standards and
Corrective Action
Closure/Postclosure
Care
Financial Assurance
Program or
Regulation
Addresses
Criteria?
Yes
Yes
Yes
No
No
Yes
Yes
No
No
Description of Regulation or Program
The Permit to Construct regulations state that impoundments can not
be located within high-water mark of perennial water bodies, and not
where surface water and groundwater are able to enter it.
The Permit to Construct regulations:
provide guidelines for inlet and outlet structures, and dike
protection
specify water depth on a case-by-case basis
require a permanent flow measuring device
require a composite liner if wastewater characteristics or site
conditions will not ensure the protection of the groundwater
The Permit to Construct regulations require a minimum of 3 feet of
freeboard (or 2 feet for impoundments less than 2 acres)
Groundwater monitoring not specified in state regulations.
Not specified in state regulations.
State regulations give the authority to inspect, but do not specify the
frequency. Specific enforcement mechanisms are also not specified in
the regulations.
All surface impoundments must conform to applicable ground and
surface water quality standards.
Not specified in state regulations.
Not specified in state regulations.
(continued)
D-108
-------
Appendix D
Program Coverage
Wyoming Requirements for Nonhazardous Waste Surface Impoundments (continued)
Criteria
Air Emission
Controls, Operating
Requirements, and
Recordkeeping
Requirements
Program or
Regulation
Addresses
Criteria?
No
Description of Regulation or Program
Not specified in state regulations.
Yes: Regulation or program addresses criteria.
No: There is no specific state regulation or program that addresses the criteria.
Case-by-case: The criteria can be addressed by the state via a permit condition or as allowed under the flexibility
built in to the state's regulations or programs.
Sources:
Wyoming Regulations: Department of Environmental Quality, Water Quality, Chapters 2, 3 and 11.
Wyoming Statutes: 35-11-101 et seq.
Wyoming Department of Environmental Quality (WDEQ) web page (http://deq.state.wy.us/wqd/w&ww.htm).
D-109
-------
Appendix D
Program Coverage
Section D-2
Table for Comparison of TC Levels to Wastewater Concentrations in Surface
Impoundments Predicted to Cause Environmental Releases
CAS
Number
7440-38-2
7440-39-3
71-43-2
7440-43-9
56-23-5
57-74-9
108-90-7
67-66-3
7440-47-3
95-48-7
108-39-4
106-44-5
1319-77-3
94-75-7
106-46-7
107-06-2
75-35-4
121-14-2
72-20-8
76-44-8
118-74-1
87-68-3
67-72-1
7439-92-1
Constituent
Arsenic
Barium
Benzene
Cadmium
Carbon tetrachloride
Chlordane, alpha & gamma isomers
Chlorobenzene
Chlorofornf
Chromium
o-Cresol [2 -Methyl phenol]
m-Cresol [3 -Methyl phenol]
p-Cresol [4-Methyl phenol]
Cresols (total)
2,4-D [2,4-Dichlorophenoxyacetic
acid]
1 ,4-Dichlorobenzene
1,2-Dichloroethane [ethylene
dichloride]
1 , 1 -Dichloroethylene [vinylidene
chloride]
2,4-Dinitrotoluene
Endrin
Heptachlor
Hexachlorobenzene
Hexachloro- 1 ,3 -butadiene
[hexachlorobutadiene]
Hexachloroethane
Lead
TC
Regulatory
Level
(mg/L)
5
100
0.5
1
0.5
0.03
100
6
5
200
200
200
200
10
7.5
0.5
0.7
0.13
0.02
0.008
0.13
0.5
3
5
Range of Wastewater Concentrations (mg/L) (number
of facility-unit risk estimates in the range)
No Predicted
Environmental
Releases as
Indicated by
Screening Level
Inhalation Risks
< Risk Criteria
NA
NA
0-1.1(79)
NA
0-0.125(34)
NA
0-0.125(44)
0-0.99819(96)
NA
NA
NA
NA
0.0022 -
0.03(47)
NA
0.001 -0.1(43)
0.00087 -
0.125(48)
0-0.125(39)
0-0.1(33)
NA
NA
0-0.1(21)
0.0075-0.1(26)
0-0.1(30)
NA
Predicited
Environmental
Releases as
Indicated by
Screening Level
Inhalation Risks
= 10E-5 to 10E-4
or ffl = 1 to 10
NA
NA
0.005 - 0.125
(4)
NA
0.005 -
0.01166(2)
NA
No data
0.0037 -
0.99819(15)
NA
NA
NA
NA
No data
NA
No data
0.01166(1)
0.005 - 0.125(7)
No data
NA
NA
.01 - 0.1(9)
0.01(4)
No data
NA
Predicted
Environmental
Releases as
Indicated by
Screening Level
Inhalation Risks
> 10-4 or ffl > 10
NA
NA
No data
NA
No data
NA
No data
No data
NA
NA
NA
NA
No data
NA
No data
No data
No data
No data
NA
NA
No data
No data
No data
NA
(continued)
D-110
-------
Appendix D
Program Coverage
Table (continued)
CAS
Number
58-89-9
7439.97-6
72-43-5
78-93-3
98-95-3
87-86-5
110-86-1
7782-49-2
7440-22-4
127-18-4
8001-35-2
79-01-6
95-95-4
88-06-2
93-72-1
75-01-4
Constituent
Lindane
Mercury
Methoxychlor
Methyl ethyl ketone [2-butanone]
[MEK]
Nitrobenzene
Pentachlorophenol [PCP]
Pyridine
Selenium
Silver
Tetrachloroethylene
[perchloroethylene]
Toxaphene [chlorinated camphene]a
Trichloroethylene [TCE]
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
Silvex [2,4,5-
Trichlorophenoxypropionic acid]
Vinyl chloride [chloroethylene]
TC
Regulatory
Level
(mg/L)
0.4
0.2
10
200
2
100
5
1
5
0.7
0.5
0.5
400
2
1
0.2
Range of Wastewater Concentrations (mg/L) (number
of facility-unit risk estimates in the range)
No Predicted
Environmental
Releases as
Indicated by
Screening Level
Inhalation Risks
< Risk Criteria
NA
0-0.01(106)
NA
0 - 18.28(96)
0-0.1(34)
NA
0.01 -0.1(24)
NA
NA
0-0.125(49)
NA
0.001 -
0.125(43)
NA
NA
NA
0.00053 -
0.125(36)
Predicited
Environmental
Releases as
Indicated by
Screening Level
Inhalation Risks
= 10E-5 to 10E-4
or ffl = 1 to 10
NA
No data
NA
No data
No data
NA
5(2)
NA
NA
No data
NA
No data
NA
NA
NA
0.02333(1)
Predicted
Environmental
Releases as
Indicated by
Screening Level
Inhalation Risks
> 10-4 or ffl > 10
NA
0.00055 -
0.07(2)
NA
No data
No data
NA
No data
NA
NA
No data
NA
No data
NA
NA
NA
No data
NA = Not applicable because the constituent was not evaluated for air risks.
No Data = no concentration data were reported in response to the long survey that, when modeled, indicated risks
in the specified range.
Note: Bold entries indicate concentration ranges less than TC regulatory levels and causing envionrmetal air
release. Values in () indicate the number of concentration values in the range used to estimate risk for each
facility, unit, and chemical combination.
a Indicates the constituent also exceeded the risk criteria for the air pathway in the risk assessment in which actual
(rather than default) distances to receptors were used.
D-lll
-------
Appendix D
Program Coverage
Section D-3
Table of In-Scope Industry Sectors and Potentially Applicable NSPS VOC Standards
SIC
Industry
Code
2011*,
2022*,
2035*,
2063*,
2092*
2211,
2251
2435,
2436
2611*,
2621*,
2631*,
2653*,
2679*
2819*
2821*
2824*
2833*
2834*
2843*
2865*
SIC Title
Food and Kindred Products
Te stile mill products
Hardwood, softwood veneer and
plywood
Paper and allied producrs (e.g.,
pulp and paper mills, etc.)
Industrial inorganic chemicals, not
elsewhere classified
Plastics materials and resins
Organic fibers, noncellulosic
Medicinals and botanicals
Pharmaceutical preparations
Surface active agents
Cyclic crudes and intermediates,
and organic dyes and pigments
NSPS
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
VOC Emissions from Polymer
Manufacturing Industry
Synthetic Fiber Production
Facilities
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
Regulatory
Citation
N/A
N/A
N/A
N/A
N/A
40 CFR 60
Subpart ODD
40 CFR 60
Subpart H.H.
N/A
N/A
N/A
N/A
(continued)
D-112
-------
Appendix D
Program Coverage
Table (Continued)
SIC
Industry
Code
2869*
2873*
2874*
2899*
2911*
2952*
3011
3052
3069
3081
3087
3089
3229*
3273*
3312*
3313*
SIC Title
Industrial organic chemicals, not
elsewhere classified
Nitrogenous fertilizers
Phosphatic fertilizers
Chemical preparations, not
elsewhere classified
Petroleum refining
Asphalt felts and coatings
Tires and inner tubes
Rubber & plastics hose and
belting
Fabricated rubber products, not
elsewhere classified
Unsupported plastics film & sheet
Custom compound purchased
resins
Plastics products, not elsewhere
classified
Pressed and blown glass, not
elsewhere classified
Ready-mixed concrete
Blast furnaces and steel mills
Electro metallurgical products
NSPS
Equipment Leaks of VOC
Synthetic Organic Chemical
Manufacturing Industry (SOCMI)
VOC Emissions from the SOCMI
Air Oxidation Unit Processes
VOC Emissions from the SOCMI
Air Distillation Operations
VOC Emissions from the SOCMI
Reactor Processes
(Proposed) VOC Emissions from
the SOCMI Wastewater
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
VOC Emissions from Petroleum
Refinery Wastewater Systems
No VOC NSPS standard
Rubber Tire Manufacturing
Industry
No VOC NSPS standard
Pressure Sensitive Tape and Label
Surface Coating
Polymeric Coating of Supporting
Substrates Facilities
No VOC NSPS standard
Polymeric Coating of Supporting
Substrates Facilities
No VOC NSPS standard
No VOC NSPS standard
Metal Coil Surface Coating
Metal Coil Surface Coating
Regulatory
Citation
40 CFR 60
Subpart VV
40 CFR 60
Subpart III
40 CFR 60
Subpart NNN
40 CFR 60
Subpart RRR
40 CFR 60
Subpart YYY
N/A
N/A
N/A
40 CFR 60
Subpart QQQ
N/A
40 CFR 60
Subpart BBB
N/A
40 CFR 60
Subpart RR
40 CFR 60
Subpart VVV
N/A
40 CFR 60
Subpart VVV
N/A
N/A
40 CFR 60
Subpart TT
40 CFR 60
Subpart TT
(continued)
D-113
-------
Appendix D
Program Coverage
Table (Continued)
SIC
Industry
Code
3316*
3317*
3321*
3324*
3334*
3339*
3341*
3351*
3353*
3357*
3398*
3399*
3462
3499
3624,
3674
3731,
3761
4952,
4953
5171*
9711
SIC Title
Cold finishing of steel shapes
Steel pipe and tubes
Gray and ductile iron foundries
Steel investment foundries
Primary aluminum
Primary nonferrous metals, not
elsewhere classified
Secondary nonferrous, metals
Copper rolling and drawing
Aluminum sheet, plate, and foil
Nonferrous wiredrawing &
insulating
Metal heat treating
Primary metal products, not
elsewhere classified
Iron and steel forgings
Fabricating metal products, not
elsewhere classified
Electronic and other electric
equipment
Transportation equipment
Electric, gas, and sanitary services
Petroleum bulk stations and
terminals
National security
NSPS
Metal Coil Surface Coating
Metal Coil Surface Coating
No VOC NSPS standard
No VOC NSPS standard
Metal Coil Surface Coating
No VOC NSPS standard
Metal Coil Surface Coating
No VOC NSPS standard
Metal Coil Surface Coating
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
Metal Coil Surface Coating
Surface Coating of Metal
Furniture
No VOC NSPS standard
No VOC NSPS standard
No VOC NSPS standard
Bulk Gasoline Terminal
No VOC NSPS standard
Regulatory
Citation
40 CFR 60
Subpart TT
40 CFR 60
Subpart TT
N/A
N/A
40 CFR 60
Subpart TT
N/A
40 CFR 60
Subpart TT
N/A
40 CFR 60
Subpart TT
N/A
N/A
N/A
N/A
40 CFR 60
Subpart TT
40 CFR 60
Subpart EE
N/A
N/A
N/A
40 CFR 60
Subpart XX
N/A
Denotes SIC code is associated with one of the seven two-digit SIC Code that manage 98 percent of the
wastewater capacity at impoundments within the scope of this study.
D-114
-------
Appendix E
Field Sampling and Analysis
-------
-------
March 26, 2001 Appendix E
Table of Contents
E.I Methodology E-l
E.2 Planning and Facility Selection E-l
E.2.1 Development of Data Quality Objectives E-l
E.2.2 Selection of Facilities for Field Sampling E-2
E.3 Summary of Results E-10
E.4 Conclusions E-17
in
-------
March 26, 2001 Appendix E
Appendix E
Field Sampling and Analysis Program
This appendix provides a summary of the methodology used to conduct the field
sampling and analysis and provides a summary of the sample analysis results. In its review of the
proposed study methodology, conducted in the spring of 1997, EPA's Science Advisory Board
(SAB) advised EPA to obtain monitoring data to support the study. EPA conducted field
sampling and analysis of a subset of facilities that received the survey to supplement other data
sources, provide "ground-truth," and fill gaps in data obtained via EPA's Survey of Surface
Impoundments (U.S. EPA, 1999). Section E.I describes the methodology for the field sampling
and analysis program. Section E.2 describes the data quality objectives, selection of facilities,
quality assurance project plan, and sampling and analysis plans. Section E.3 describes the results
and conclusions and includes the analytical data from the field sampling program.
E.I Methodology
EPA followed a systematic planning process to develop acceptance and performance
criteria for the collection, evaluation, and use of data obtained from the field sampling and
analysis program. Systematic planning included use of the data quality objectives (DQO)
process, optimization of the sampling program to ensure completion of the sampling program
within schedule and resource limits, and preparation of a detailed quality assurance project plan
(QAPP). The sampling and analysis program was then implemented in accordance with the
QAPP and facility-specific sampling and analysis plans (SAPs).
This section provides an overview of how EPA developed the planning documents,
selected facilities for field sampling, and conducted the sampling and analysis program.
E.2 Planning and Facility Selection
E.2.1 Development of Data Quality Objectives
EPA developed DQOs for the field sampling and analysis program. The objective of the
DQO process was to develop a sampling and analysis strategy to satisfy the data requirements of
the study. The approach for developing DQOs for the Field Sampling and Analysis Program was
based on the guidance presented in EPA's Guidance for the Data Quality Objectives Process,
EPA QA/G-4 (U.S. EPA, 2000a).
The DQO process yields qualitative and quantitative statements that
• Clarify the study objective
• Define the type, quantity, and quality of required data
E-l
-------
March 26, 2001 Appendix E
• Determine the most appropriate conditions from which to collect the samples
• Specify how the data will be used.
DQOs were used to define the quality control requirements for sampling, analysis, and
data assessment. These requirements were then incorporated into the QAPP and individual site-
specific SAPs. The outputs of this process were documented in the Draft DQOs Development
Document included as Attachment A of the QAPP.
E.2.2 Selection of Facilities for Field Sampling
As part of the planning process, EPA selected a subset of the 215 facilities for field
sampling. This section describes the rationale for selection of facilities for field sampling and
identifies those facilities at which field sampling was conducted.
E.2.2.1 Rationale. Selection of specific facilities for field sampling was based on criteria
developed by EPA's Office of Solid Waste (OSW) and included in EPA's Surface Impoundment
Study Technical Plan for Human Health and Ecological Risk Assessment (U.S. EPA, 2000c) and
the Quality Assurance Project Plan for the Surface Impoundment Study Field Sampling and
Analysis Program (U.S. EPA, 2000b). Specifically, EPA considered the following objectives in
selecting facilities as candidates for field sampling:
• Provide chemical composition data and other information for approximately 5 to
10 percent of facilities within each industry category (i.e., within each Standard
Industrial Classification (SIC) major group)
• Provide a geographically distributed set of facilities for field sampling
• "Pair" facilities geographically to optimize travel costs associated with field
sampling
• Verify facility-submitted data
• Fill data gaps (e.g., check for the presence of constituents of concern for the study1
not reported by a facility that one might reasonably expect would be present).
E.2.2.2 Facilities Selected for Sampling. Table E-l identifies each of the SIC major
industry groups, the number of facilities in the sample population distributed within each group,
the number and type of facilities selected for field sampling within each group, and the
justification or rationale for selecting each facility.
Some facilities reported more than one waste generation process, associated waste stream,
and surface impoundment in their response to the Survey of Surface Impoundments (U.S. EPA,
1999). Field sampling at several of these facilities included collection of samples from multiple
Constituents of interest for the study are listed in Appendix 2 of the Survey of Surface Impoundments
(U.S. EPA, 1999).
-------
Marc/7 2(5, 2007
Appendix E
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Marc/7 2(5, 2007
Appendix E
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March 26, 2001
Appendix E
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-------
March 26, 2001 Appendix E
waste streams and/or multiple impoundments, thereby conserving sampling resources and
providing more thorough information about an individual facility.
E.2.2.3 Preparation of the Quality Assurance Project Plan. Quality assurance is a
system of management activities that emphasizes systems and policies to aid in the collection of
data appropriate for data users and to support management decisions in a resource-efficient
manner. The outputs of the DQP process and the sampling design are combined in planning
documents, and one of the key planning documents required for implementation of a field
sampling program is a QAPP.
The QAPP serves as a "blueprint" for identifying how the quality system of the
organization performing the work is reflected in a particular project and in associated technical
goals. It is critical to any environmental data collection operation because it documents project
activities, including how QA and quality control (QC) will be implemented during the life cycle
of a project.
To support the field sampling component of the SI Study, the Agency prepared a
comprehensive QAPP in accordance with the EPA Quality Assurance Division's R-5 document
on EPA Requirements for Quality Assurance Project Plans. The QAPP, Quality Assurance
Project Plan for the Surface Impoundment Study Field Sampling and Analysis Program
(U.S. EPA, 2000b), was used as a guide for preparing sampling plans, conducting sampling,
performing all analytical work on the collected samples, and preparing all the necessary reports.
The activities addressed in the QAPP cover the entire project life cycle, integrating elements of
the planning, implementation, and assessment phases. The QAPP is composed of four sections
of project-related information describing
• Project management
• Measurement and/or data acquisition
• Assessment and oversight
• Data validation, usability, and assessment.
E.2.2.4 Development and Implementation of Facility-Specific Sampling and Analysis
Plans. EPA selected 12 facilities for field sampling. For each facility, the Agency prepared a
sampling and analysis plan in accordance with the specifications outlined in the QAPP. Each
SAP included a project description, a listing of the project organization and staff responsibilities,
quality objectives and criteria for measurement data (consistent with the Agency's performance-
based measurement system, or PBMS), field procedures to be used, procedures for sample
custody and transport, a listing of analyses required and facility-specific QA/QC procedures
(such as requirements for decontamination and use of control samples), and equipment-specific
calibration procedures and frequency. Each facility-specific SAP also included a facility-specific
health and safety plan.
Both the analytical plans and the sampling plans were organized so the requisite
information could be obtained within the given time and resource constraints. This was achieved
by narrowing down the study list of 256 constituents of concern to a list of constituents
reasonably expected to be present at each facility. This approach was consistent with the
E-7
-------
March 26, 2001 Appendix E
recommendations of EPA's SAB. We developed the list of target constituents for each facility-
specific SAP based on industry knowledge, information obtained from National Pollutant
Discharge Elimination System (NPDES) and Resource Conservation and Recovery Act (RCRA)
permits, and the survey responses.
To optimize travel resources, most of the sampling trips were arranged so that two
facilities located close to each other could be visited within a given week.
E.2.2.5 Field Sampling Activities. EPA coordinated the sampling visits in advance with
each facility representative. At each facility, prior to conducting field activities, the EPA field
team met with facility representatives to review the sampling strategy, receive a briefing on any
facility-specific health and safety requirements, and coordinate other activities such as the
collection of split samples.
At each facility, samples generally were collected at one or more surface impoundments
to represent the following locations
• Influent wastewaters
• Wastewater within the impoundment
• Effluent wastewater
• Sludges in the impoundment
• Leachate or groundwater (if present).
In addition to collecting samples for chemical analysis, the field team performed other
field data collection activities including measurements of pH, dissolved oxygen, conductivity,
temperature, and turbidity using a portable water quality tester. At influent and effluent sampling
points, the field team measured (or estimated), where possible, the flow rates.
Field sampling activities also included
• Sample labeling
• Collection and preparation of field QC samples (such as trips blanks, equipment
blanks, temperature blanks)
• Chemical and physical preservation of samples
• Decontamination of field equipment
• Implementation of sample chain-of-custody procedures and documentation
• Packaging and shipping of field samples, equipment, and supplies
• Documentation of all field activities including taking photographs of field
activities.
E-S
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March 26, 2001 Appendix E
E.2.2.6 Sample Analysis and Data Reporting. The field sampling and analysis program
employed a performance-based approach for the analysis of samples. To that end, a constituent
list was developed for each facility based on the list of constituents reported by the facility in
their survey response, knowledge of the industry sector, and whether the constituent was
reasonably expected to be present. Target quantitation limits were then set equal to or lower than
the carcinogenic-risk screening factors (CRSFs) and noncarcinogenic risk screening factors
(NCRSFs) for various matrices. EPA estimated the CRSF or NCRSF for each constituent using
equations for the development of human health screening factors as presented in Table 2-1 of the
Surface Impoundment Study Technical Plan for Human Health and Ecological Risk Assessment
(U.S. EPA, 2000c). Two exposure scenarios were used: direct ingestion of water derived from
the impoundment and direct ingestion of sediments or sludges. Finally, analytical methods were
selected based on their capability to achieve the required quantitation limits.
Laboratories analyzed the samples in accordance with the facility-specific SAPs. In some
cases, the laboratories were able to detect and report constituents of interest for the study that
were not listed in the facility-specific target analyte list. This was possible because some
analytical methods used are capable of detecting a range of constituents, many of which were not
listed as target analytes for a given facility (but nonetheless were included in the list of
256 constituents of interest for the study).
Analytical data reports and waste characterization reports were prepared as specified in
the QAPP and included the following key elements:
• Case narrative, containing a description of sample receipt, sample preparation,
analysis, QA/QC, calibration, and laboratory manager certification
• Chain-of-custody and analysis request documentation
• QA/QC and calibration data and laboratory and instrument raw data
• Executive summary tables of analytical results
• Summary of field activities and observations
• Photo log
• Data reduction and analysis of the raw data
• Information about corrective action and protocol changes made during sampling
and analysis.
Copies of the sampling plans and waste characterization reports are available from EPA.
E-9
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March 26, 2001 Appendix E
E.3 Summary of Results
This section provides a summary of the sample analysis results for the Surface
Impoundment (SI) Study field sampling program. Detailed tables of all sample analysis results
are given in the individual waste characterization reports prepared for each facility visited for
sampling.
The results are presented and discussed in terms of the original objectives.
Objective 1: Determine whether the waste characterization data provided by the
facilities in their survey responses and the corresponding sample analysis results from
EPA's sampling program are in reasonable agreement and within the range of values
expected (i.e., do the EPA data "verify" the survey data).
Objective 2: Determine whether the field sampling and analysis program confirms the
presence of constituents reported by the facilities and determine the extent to which the
field data identify gaps in the industry-supplied data.
Objective 1: Are the EPA Field Data and the Survey Data in Reasonable Agreement?
Of the 12 facilities selected for field sampling, 10 provided responses in their surveys
indicating concentration or other measurement values characterizing wastes in their in-scope
surface impoundments. EPA's field sampling program yielded 175 measurement values that can
be "paired" with a corresponding value provided in the survey responses.
Each pair was formed from a measurement value obtained from the analysis of an EPA
sample and a second value provided by the facility in their survey for the corresponding
impoundment, sample location, and matrix type (e.g., wastewater or sludge). Pairs formed from
a detected value and a "less than" value were kept in the data set; however, pairs of "less than"
values were removed from the data set. The data set was then edited as follows: If the EPA
value was less than and its quantitation limit (QL) was greater than the survey value, then the
EPA value was set equal to the survey value. If the EPA value was reported as less than QL and
the QL was less than the survey value, then the EPA value was set equal to its QL. If the survey
value was reported as "less than," then it was set equal to its reported detection or quantitation
limit.
The measurement values include 24 pairs of pH data and 151 pairs of non-pH data,
including various inorganics, volatile organics, semivolatile organics, total organic carbon
(TOC), and total suspended solids. The pairs of data represent measurements of constituent
concentrations and pH in wastewater influents, effluents, water within impoundments, sludges,
and leachate. A complete listing of the paired data is presented as Attachment E-l of this report.
If the EPA field data and the corresponding facility-provided data are in agreement, then
the paired values should, in theory, plot on an x-y scatter plot as a roughly elliptical pattern with
points falling evenly on either side of a 45 ° line. Figure E-l is a scatter plot of the 151 pairs of
E-10
-------
March 26, 2001
Appendix E
EPA Field Sample Analysis Result
Figure E-l. EPA data versus survey data (log-log plot, without pH data).
data (not including pH).2 Because the waste characterization data span several orders of
magnitude, it was necessary to create the plot using the natural log-transformed values of the data
sets to provide a more meaningful graphical display. The paired data plot is a roughly elliptical
pattern, with points falling on both sides of a 45 ° line, indicating a pattern of agreement between
EPA's field sample analysis results and the waste characterization data provided in the survey
responses. Note that more than half of the points fall above the 45 ° line, indicating that the
survey values generally are higher than the corresponding values obtained through the EPA field
sampling effort. The plot also shows substantial deviation from agreement for a number of
values. Such deviations are expected due to random variability in the waste, variability that can
be introduced in the sampling and analysis processes, the fact that the two measurements in each
pair were obtained at different times, and the fact that some values are represented by detection
limits or they are estimates made by the facility representatives.
Another method for checking the agreement between paired values is to calculate the
ratio of one value in a matched pair to the other value in the matched pair. If the ratio of the first
value to the second value is 1, then there is agreement between the paired values. If the ratio of
the first value to the second value is greater than 1, then the first value is greater than the second
value. If the ratio is between 0 and 1, then the first value is less than the second value. Using the
ratio of paired values has two advantages over the calculation of the difference between paired
values: it is dimensionless, and it provides a basis for comparing multiple locations, facilities,
pH is the negative log of the [H+] concentration and thus tends to show better agreement between paired
values than does concentration data. The pH data pairs were not included in the graphic so that any pattern of
agreement between paired concentration values would not be overstated.
-------
March 26, 2001
Appendix E
and constituents measured in different units. Furthermore, the log base 10 of the ratio provides a
simple measure of the relative relationship between paired values.
Figure E-2 is a bar chart showing the ratio of survey values to EPA sample analysis
results calculated for all of the 151 pairs of non-pH data, ranked in order from the smallest to the
largest. Positive values indicate survey values greater than the corresponding EPA sample
analysis results. Negative values indicate survey values less than their corresponding EPA
sample analysis results. The figure shows that most of the ratios are positive, indicating that the
survey values generally are greater than the corresponding values obtained through the EPA field
sampling effort. The study-wide pattern of agreement can be summarized as follows:
• Approximately 88 percent of paired values agree within 1 order of magnitude (i.e.,
one value in the pair is no more than 10 times the other value in the pair).
• Approximately 10 percent of paired values agree within 1 to 2 orders of
magnitude (i.e., one value in the pair is between 10 and 100 times the other value
in the pair).
• Less than 2 percent of the paired values differed by more than 2 orders of
magnitude (i.e., where one value in the pair was more than 100 times the other
value in the pair).
Survey values 100 times EPA sample analysis result
Survey values 10 times EPA sample analysis result
EPA sample analysis result 10 times survey value
EPA sample analysis result 100 times survey value
EPA sample analysis result 1000 times survey value
Ratios in Rank Order (all data pairs except pH)
Figure E-2. Relationship between survey values and corresponding EPA measurements.
-------
March 26, 2001
Appendix E
The ratios were then plotted on a facility-by-facility basis (Figure E-3) to evaluate any
patterns of agreement that might exist between samples collected at a given facility. The figure
shows a pattern of both negative and positive values for most facilities, similar to that which
occurs on a study-wide basis.
Finally, the ratios were plotted by constituent group (Figure E-4) to evaluate any patterns
of agreement that might exist between samples analyzed for a given constituent or parameter.
For the purpose of this analysis, constituents were grouped into inorganics, volatile organics, and
semivolatile organics, plus total organic carbon (TOC), total suspended solids (TSS), and pH.
Again, the figure shows a pattern of both negative and positive values for all constituent groups,
similar to that which occurs on a study-wide basis.
In summary, there is a pattern of agreement between the waste characterization data
provided in the surveys and EPA's sample analysis results for the corresponding impoundments,
sample locations, and parameters of interest. While there is a range of differences between
paired data, the differences are not strongly associated with a particular facility or a particular
constituent group.
Objective 2: To What Extent Do the EPA Data Confirm the Survey Data and Identify Data
Gaps?
As an indicator of the extent to which the EPA field sampling data confirm the SI Survey
responses and identify gaps in their responses, three activities were performed:
Petroleum
refinery No. 1
Industrial inorganic
chemical plant
Petroleum
refinery No. 2
! Aluminum sheet, plate,
I foil mfg. facility
Ellectrometallugical ;
products mfg. |
facility
J
Semiconductor
mfg. facility
Nylon mfc
plant
Ratios in Rank Order, By Facility (not including pH)
Figure E-3. Relationship between survey value and corresponding EPA measurement, by
facility.
E-13
-------
March 26, 2001
Appendix E
Figure 4.
Organics
iOrganics!
TOC ! TSS
PH
Ratios in Rank Order, By Constituent Group
Relationship between survey values and corresponding EPA measurements,
by constituent group.
• Determined the number of constituents reported by each facility and sample
location (i.e., influent, wastewater, effluent, or sludge) in their survey as being
present in their waste stream. A constituent was considered present in the waste
stream if it was (1) reported as a concentration value in their survey, (2) reported
as "present, but quantity unknown," or (3) reported as less than (<) a detection or
quantitation limit.
• Counted the number of those same constituents (from above) that were also
detected in samples taken by EPA.
• Counted the number of additional constituents detected in EPA samples that
were not reported by the facility in their survey response. The count of additional
constituents provided an indication of the "completeness" of the survey responses
regarding constituents present and indicated the extent to which EPA data might
fill "gaps" in data reported by the facilities.
These data are summarized on Table E-2. For most of the facilities sampled, the EPA
field sampling confirmed the presence of constituents reported by the facilities.3 The EPA field
sampling also confirmed the presence of a number of additional constituents not reported by the
facilities. Quantitation of these additional constituents serves to fill gaps in data provided by the
In Table 2, "Number of constituents" does not include parameters such as pH, TOC, TS, and TSS.
E-14
-------
March 26, 2001
Appendix E
Table E-2. Summary of Number of Constituents Reported By Facilities and
Detected in EPA Samples
Facility
Fruit processing facility
SIC Code 2037
Paper mill
SIC Code 2621
Pulp mill
SIC Code 26 11
Nylon manufacturing plant
SIC Code 2821
Industrial inorganic chemical
plant
SIC Code 28 19
Location
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
No. of
Constituents
Reported by
Facility in
Survey3
0
0
0
0
0
14
14
13
10
15
8
8
8
10
11
8
8
8
8
8
0
0
6(2)
0
6
No. of Same
Constituents
Detected by
EPA"
0
0
0
0
0
6
5
3
3
8
7
5
5
8
10
5
6
o
J
6
6
0
0
1
0
4
Additional
Constituents
Detected by
EPAC
9
10
10
11
11
9
10
6
16
18
17
13
15
27
30
11
9
8
10
18
11
9
5
15
13
(continued)
E-15
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March 26, 2001
Appendix E
Table E-2. (continued)
Facility
Petroleum refinery No. 1
SIC Code 29 11
Petroleum refinery No. 2
SIC Code 29 11
Custom rubber mixing plant
SIC Code 3087
Ready-mixed concrete plant
SIC Code 3273
Electro-metallurgical
products facility
SIC Code No. 3313
Location
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of All locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
No. of
Constituents
Reported by
Facility in
Survey3
53(4)
53(3)
54(4)
53(5)
55
10
11
11
0
11
10
10
10
10
10
0
0
0
0
0
14
17
16
14
17
No. of Same
Constituents
Detected by
EPA"
10(1)
10
11
13
17
9
10
7
0
11
4
3
2
5
5
0
0
0
0
0
12
12
11
12
15
Additional
Constituents
Detected by
EPAC
4
3
4
7
7
7
4
3
20
13
0
0
0
3
3
5
5
4
9
10
16
7
5
15
13
(continued)
E-16
-------
March 26, 2001
Appendix E
Table E-2. (continued)
Facility
Aluminum sheet, plate, and
foil manufacturing facility
SIC Code No. 3353
Semiconductors and related
devices manufacturing
facility, SIC Code No. 3674
Location
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
Influents
Wastewaters
Effluents
Sludges
Aggregate of all locations
No. of
Constituents
Reported by
Facility in
Survey3
5
5
7
5
7
0
0
4
0
4
No. of Same
Constituents
Detected by
EPA"
4
4
5
5
7
0
0
3
0
4
Additional
Constituents
Detected by
EPAC
5
3
1
11
11
8
7
3
13
9
a Value in ( ) is the number of constituents reported by the facility as a "nondetect" value or "<."
b Value in ( ) is the number of constituents reported as nondetect by the facility but detected in the
corresponding EPA sample.
0 A complete listing of all constituents detected in EPA samples and not reported in the surveys is provided in
Attachment E-2.
facilities sampled. These additional data may be used by EPA to evaluate the veracity of survey
data used to conduct the human health and ecological risk assessments.
E.4 Conclusions
The results of the field sampling indicate that there is a general pattern of agreement
between the EPA field data and the reported survey data on a sample-by-sample basis. As
expected, however, some extreme departures from agreement (i.e., differences greater than
2 orders of magnitude) are observed for a relatively small (<2 percent) percentage of the data.
This pattern of agreement also is found when the data are grouped by facility and by constituent
categories.
The Agency's field sampling program also confirmed the presence of constituents
reported by the facilities and found additional constituents not reported by the facilities. The
number of additional constituent identified at each facility provides evidence that facilities may
have incomplete knowledge of their waste composition. Quantitation of these additional
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constituents provides supplemental data for possible use in the uncertainty analysis of the SI
Study on human health and ecological risk assessment.
References
U.S. Environmental Protection Agency. 1999. Survey of Surface Impoundments.
OMB 2050-0157. Office of Solid Waste, Washington, DC.
U.S. Environmental Protection Agency. 2000a. Guidance for the Data Quality Objectives
Process, EPA QA/G-4. EPA/600/R-96/055. Office of Environmental Information,
Washington, DC.
U.S. Environmental Protection Agency. 2000b. Quality Assurance Project Plan for the Surface
Impoundment Study Field Sampling and Analysis Program. Prepared by SAIC under
Contract 68-W6-0068. March 20.
U.S. Environmental Protection Agency. 2000c. Surface Impoundment Study Technical Plan for
Human Health and Ecological Risk Assessment. Prepared by Research Triangle Institute
and Tetra Tech, Inc. under Contract No. 68-W-98-085. February 2000.
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