Evidence of CERCLA Hazardous Substances and
Potential Exposures at CERCLA §108(b) Mining
and Mineral Processing Sites
Prepared by
United States Environmental Protection Agency
Office of Resource Conservation and Recovery (ORCR)
And
Office of Superfund Remediation and Technology Innovation (OSRTI)
September 23, 2016
-------
9/23/2016
Disclaimer
This document was prepared by staff from the Office of Resource Conservation and
Recovery (ORCR), and the Office of Superfund Remediation and Technology Innovation
(OSRTI), U.S. Environmental Protection Agency (EPA). Any opinions, findings, conclusions, or
recommendations do not change or substitute for any statutory or regulatory provisions. This
document does not impose legally binding requirements, nor does it confer legal rights, impose
legal obligations, or implement any statutory or regulatory provisions. Mention of trade names or
commercial products is not intended to constitute endorsement or recommendation for use. This
document is being made available to the public. Any questions or comments concerning this
document should be addressed to Timothy Taylor, U.S. Environmental Protection Agency,
Office of Resource Conservation and Recovery, 1200 Pennsylvania Ave. N.W., Washington, DC
20460 (email:Taylor.Timothy@epa.gov).
-------
9/23/2016
Table of Contents
Table of Contents i
List of Tables iii
List of Figures iii
List of Abbreviations iv
Executive Summary 1
Findings for 108(b) Historical CERCLA Sites 1
Findings for 2009 Current Sites 3
Using Case Study Historical Sites to Predict Potential Human and Ecological Exposure
to CERCLA Hazardous Substances from 2009 Current Sites 5
1.0 Introduction and Problem Formulation 1
1.1 Background and Purpose 1
1.2 Scope 2
1.3 Methodology and Data Sources 3
1.3.1 Defining the Universes of Sites Evaluated in this Study 3
1.3.2 Mining and Mineral Processing Practices Responsible for CERCLA Hazardous
Substance Releases 4
1.3.3 Hazardous Substance Release Mechanisms 5
1.3.4 Hazardous Substances of Concern 5
1.3.5 Exposures to Hazardous Sub stances: Receptors 6
1.3.6 Exposure Pathways/Routes 7
1.3.7 Discussion of Findings, and Public Health Assessments 8
2.0 Hazard Identification 9
2.1 Universes of Sites Reviewed in this Study 9
2.1.1 Historical Sites 9
2.1.2 2009 Current Sites 10
2.2 Mining and Mineral Processing Practices 11
2.2.1 Historical Sites 12
2.2.2 2009 Current Sites 13
2.3 Release Mechanisms 15
2.3.1 Historical Sites 15
2.3.2 2009 Current Sites 15
2.4 CERCLA Contaminants of Concern (COCs) 16
2.4.1 Historical Sites 16
2.4.2 2009 Current Sites 17
2.5 Toxicity of Priority COCs 19
3.0 Exposure Analysis 26
l
-------
9/23/2016
3.1 Conceptual Site Models for Superfund Human Health and Ecological Risk
Assessments 27
3.2 Receptors 33
3.2.1 Case Study Historical Sites: Human Receptors 33
3.2.2 Case Study Historical Sites: Ecological Receptors 33
3.2.3 2009 Current Sites: Documented Human Receptors 33
3.2.4 2009 Current Sites: Potential Human Receptors 34
3.2.5 2009 Current Sites: Documented Ecological Receptors 35
3.2.6 2009 Current Sites: Potential Ecological Receptors 36
3.3 Exposure Pathways and Routes 36
3.3.1 Case Study Historical Sites: Human Exposure Pathways and Routes 36
3.3.2 Case Study Historical Sites: Ecological Exposure Pathways and Routes 37
3.3.3 2009 Current Sites: Documented Human Exposure Pathways and Routes 38
3.3.4 2009 Current Sites: Potential Human Exposure Pathways and Routes 38
3.3.5 2009 Current Sites: Documented Ecological Exposure Pathways and Routes 39
3.3.6 2009 Current Sites: Potential Ecological Exposure Pathways and Routes 39
4.0 Discussion of Findings 41
4.1 Overview of Superfund Risk Assessment 41
4.2 Case Study Historical Site Data Collection Results 42
4.2.1 Human Health 42
4.2.2 Ecological Impacts 43
4.3 2009 Current Site Data Collection Results 44
4.3.1 Human Health 44
4.3.2 Ecological Impacts 45
4.4 Comparisons of Data from Historical and 2009 Current Sites 46
4.4.1 Overview 46
4.4.2 Similar CERCLA Hazardous Substances are Present 46
4.4.3 Similar Exposure Pathways 47
4.5 Other Analyses 48
4.5.1 Public Health Hazards 48
4.5.2 Documented Human Health Impacts in Other Countries 49
4.5.3 Ecological Impacts of Acidic Mine Drainage 50
4.5.4 Impacts from Low-Probability, High-Consequence Events 51
4.6 Uncertainty in This Report 51
4.6.1 Time Interval Assumptions 51
4.6.2 Data Gaps for 2009 Current Sites 52
4.6.3 Mine and Processor Site Locations 52
4.6.4 Identifying COCs 52
4.6.5 Identifying Receptor Locations 52
4.6.6 Estimating Exposures 53
li
-------
9/23/2016
4.7 Summary of Findings Regarding the Potential for Human Health and Ecological
Impacts from 2009 Current Sites 54
4.8 Overall Findings 55
5.0 References 57
Appendix A Superfund Risk Assessments and Public Health Assessments of 2009
Current Sites
Appendix B Defining the Universes of 108(b) Historical CERCLA and 2009 Current
Sites
Appendix C Presence and Sources of CERCLA Hazardous Substances at 108(b)
Historical CERCLA Sites
Appendix D Identification of Contaminants of Concern and Priority Contaminants of
Concern at Case Study Historical Sites
Appendix E Geospatial Methodologies and Quality Assurance Protocol for 2009
Current Site Analyses
Appendix F Evidence of CERCLA Hazardous Substances at 2009 Current Sites
Appendix G Potential for Human Drinking Water Exposures from 2009 Current Sites
Appendix H Presence of Ecological Receptors near Case Study Historical and 2009
Current Sites
Appendix I Flooding and Runoff Potential for 108(b) Historical CERCLA and 2009
Current Sites
Appendix J Toxicity of Priority Contaminants of Concern (COCs)
Appendix K Conceptual Site Model for Mining or Mineral Processing Sites
Appendix L Potential Human Receptors for 2009 Current Sites
Appendix M ATSDR Public Health Findings for 108(b) Historical CERCLA Sites
List of Tables
Table 2-1. CERCLA Hazardous Substances Identified in Superfund Risk Assessments of Case
Study Historical Sites 16
Table 4-2. Priority COCs Identified at Case Study Historical and 2009 Current Sites 47
List of Figures
Figure 3-1. Generic mine site conceptual site model and exposure pathways for a Superfund
human health risk assessment 28
Figure 3-2. Contaminant sources, exposure pathways, exposure routes, and human receptors at
Case Study Historical sites 31
Figure 3-3. Contaminant sources, exposure pathways, exposure routes, and ecological receptors
at Case Study Historical sites 32
Figure 3-4. Number of 2009 Current sites, by estimated population within 3 miles 35
Figure 4-1. Example of a five-mile buffer zone intersected with Census block group boundaries,
illustrating how block group areas are split by the buffer zone 54
in
-------
9/23/2016
List of Abbreviations
AT SDR
Agency for Toxic Substances and Disease Registry
BRA
baseline risk assessment
CERCLA
Comprehensive Environmental Response, Compensation and Liability Act
CERCLIS
Comprehensive Environmental Response, Compensation and Liability
Information System database
CFR
Code of Federal Regulations
COC
contaminant of concern
COPC
contaminant of potential concern
CSF
cancer slope factor
CSM
conceptual site model
CWA
Clean Water Act
DMR
Discharge Monitoring Report
EPA
Environmental Protection Agency
ERA
ecological risk assessment
FEMA
Federal Emergency Management Agency
GIS
geographic information systems
HEAST
Health Effects Assessment Summary Tables
HHRA
human health risk assessments
HI
hazard index
HQ
hazard quotient
ICIS
Integrated Compliance Information System
MSHA
Mine Safety and Health Administration
NCP
National Contingency Plan
NEPA
National Environmental Policy Act
NHD+
National Hydrography Dataset Plus
NPDES
National Pollutant Discharge Elimination System
NPL
National Priorities List
PCS
Permit Compliance System
RCRA
Resource Conservation and Recovery Act
RfC
reference concentration
RfD
reference dose
RI/FS
Remedial Investigation/Feasibility Study
RME
reasonable maximum exposure
ROD
Record of Decision
TRI
Toxics Release Inventory
U.S.C.
United States Code
UR
unit risk
USGS
U.S. Geological Survey
iv
-------
9/23/2016
Executive Summary
This report documents Agency efforts from 2009 - 2012 to determine what mining and
mineral processing practices and contamination patterns have historically caused Comprehensive
Environmental Response, Compensation and Liability Act (CERCLA, also known as Superfund)
cleanups to occur. Specifically, the Agency studied the human and ecological exposures to
releases of CERCLA hazardous substances identified in Superfund risk assessments, and
described the extent to which those same practices, contamination patterns, releases, and
exposures might occur at current and future sites.
The methodology presented in this report is two pronged: first, examine Superfund risk
assessments and other CERCLA site-specific documents for risk estimates, including estimated
exposures of human and ecological receptors to CERCLA hazardous substances from mining
and mineral processing sites cleaned up under Superfund in the past (i.e., Historical sites), and
second, collect available information on potential exposures of human and ecological receptors
to CERCLA hazardous substances from mining and mineral processing sites that were
operational in 2009 (the most current available data at the time the evaluation took place). EPA
is using these 2009 Current sites as a proxy for current and future mining and mineral
processing sites that may be subject to CERCLA 108(b) regulatory requirements.
EPA compared conditions at Case Study Historical sites to those at 2009 Current sites,
in order to compare the potential for human or ecological exposures to CERCLA hazardous
substances from mines and processors to be regulated under CERCLA 108(b) to Historical sites
where Superfund cleanups had occurred. EPA used data from Historical sites for two main
reasons:
CERCLA Section 108(b)(2) requires EPA to set the level of financial responsibility based
on the experience of the Superfund (42 U.S.C. 9608(b)(2)), and
Few Superfund risk assessments have been conducted at currently operating mines and
mineral processors. In addition, insufficient information is available from other CERCLA
site documents regarding potential exposures of human and ecological receptors to
CERCLA hazardous substances from releases at currently operating mines and mineral
processors to estimate risks.
Findings for 108(b) Historical CERCLA Sites
EPA initially identified 251 sites as mining and mineral processing sites cleaned up using
Superfund authority. Referred to in the report as the 108(b) Historical CERCLA Sites universe,"
or "Historical sites," the list included 104 National Priorities List (NPL) sites, 132 Removal sites,
and 15 sites cleaned up as part of Superfund enforcement actions. Within the 108(b) Historical
CERCLA Sites universe, 82 sites had operated after 1980. The report refers to this group as the
"post-1980 sites." To better represent current mining and processing operations and practices,
EPA randomly selected a subset of 30 post-1980 sites (including 24 NPL sites and 6 removal
sites) for in-depth review. The focus on post-1980 sites was intended to strengthen the relevance
of the data to 2009 Current sites, because sites operating after 1980 would be more likely to use
mining and mineral processing techniques similar to those still in use today, compared with sites
that had closed or been abandoned before 1980. Data collection for the 30 randomly selected
sites found that insufficient Superfund risk assessment data were available for the selected
ES-1
-------
9/23/2016
Removal and other non-NPL sites. As a result, only detailed data from the 24 NPL sites were
available to use in the analysis. The report refers to these 24 NPL sites as Case Study Historical
sites.
The Case Study Historical sites mined or processed various commodities, including non-
precious metals such as aluminum, copper, lead, and zinc (16 sites); precious metals (10 sites);
radioactive elements (2 sites); phosphorus/phosphate compounds (3 sites); and unusual
commodities such as lithium (1 site). Some sites mined or processed more than one type of
commodity, so the number of sites mentioned above for each commodity sums to more than 24.
Typical mining and processing practices at the Case Study Historical sites included disposal of
waste rock near excavation areas, use of extraction solutions such as cyanide for dissolving gold
from ore, and use of high-temperature smelters and chemical processes to isolate metallic and
nonmetallic mineral values from ores and/or concentrates.
To ensure that EPA's analysis included the widest possible range of conditions at mining
and mineral processor sites, EPA conducted an exhaustive review of CERCLA data to identify
sites missed in the original 108(b) Historical CERCLA Sites universe. As of the end of 2012, the
108(b) Historical CERCLA Sites universe had expanded to 448 sites. EPA also selected
additional sites from the expanded 108(b) Historical CERCLA Sites universe for in-depth
review, to better represent the range of commodities mined and/or processed at Historical sites.
While Superfund risk assessment data were collected for the supplemental sites, and for
completeness of documentation their collection is recorded in Appendix B, the data were not
available in time to be included in the analyses. References to "Case Study Historical sites" in
this report refer only to the randomly selected 24 NPL sites, and any conclusions drawn by this
report are based solely on data from the 24 NPL sites and not on data from the supplemental
sites.
To collect information for the Case Study Historical sites, EPA reviewed documents
available in the Superfund Data Management System, including Remedial Investigation/
Feasibility Studies (RI/FS) on hazardous substances that were found to be contaminants of
concern, contaminant sources, pathways of concern, human and ecological receptors, and
quantitative risk estimates, when those estimates were available.
A CERCLA hazardous substance found at a concentration that a Superfund risk
assessment has determined poses an unacceptable risk to human health or the environment is
referred to as a Contaminant of Concern (COC). These are the substances that are addressed by
cleanup actions at the site. EPA identified 86 different COCs associated with Case Study
Historical sites. To focus the remainder of this analysis, EPA identified the subset of COCs that
occurred most frequently at the Case Study Historical sites. COCs identified at four or more of
the sites, due to either associated human health or ecological risks, were retained for further
review and called Priority COCs. Priority COCs for human health risk were, in descending order
of frequency: arsenic, manganese, cadmium, zinc, antimony, lead, beryllium, copper,
benzo[a]pyrene, chromium, mercury, selenium, thallium, benzo[b]fluoranthene, nickel, radium-
226, benz[a]anthracene, dibenz[a,h]anthracene, fluorine (as fluoride), lead-210, silver, uranium-
238, polychlorinated biphenyls, radon-222, and thorium-228. Priority COCs for ecological risk
were, in descending order of frequency: zinc, lead, arsenic, cadmium, copper, antimony,
chromium, selenium, thallium, manganese, beryllium, silver, mercury, and nickel.
ES-2
-------
9/23/2016
Environmental settings at the Case Study Historical sites ranged from lightly populated
arid areas to densely populated urban areas, with the majority of sites located in the western
United States. Exposure pathways found to occur at sites where Superfund risk assessments
estimated human health risks were at or above levels of concern included surface water, ground
water, soil, and food ingestion (i.e., one case study included resident ingestion of homegrown
vegetables, and one case study included fisher ingestion of shrimp). Exposure pathways found to
occur for ecological receptors included soil, food, and surface water exposures. Flooding, or the
presence of hazardous substances in a floodplain zone with periodic rising water levels,
contributed to hazardous substance releases at several of the Case Study Historical sites.
Quantitatively, the highest estimated human cancer or noncancer risks to a reasonable
maximum exposure (RME) individual in Superfund risk assessments were associated with
practitioners of traditional lifestyles on an Indian reservation, due to exposures from
contamination resulting from an abandoned uranium mine. Other examples of high RME
individual risks are associated with metals in drinking water from wells at off-site residences
near an abandoned gold mine, as well as with arsenic in soil ingested by current and future
residents near an abandoned gold mine and mill.
The highest Superfund risk assessment ecological risk estimates at Case Study Historical
sites, for raccoons ingesting selenium-contaminated prey at a tungsten processing site, were four
to five orders of magnitude higher than the benchmark for adverse effects. Other examples of
ecological risks include reduced fish populations downstream from an abandoned gold mine and
mill (possibly due to dam releases of contamination from the mine/mill site), and suggestive
evidence of risk to the viability and functioning of omnivorous birds (robins) due to cadmium,
lead, and zinc in in their prey, resulting from zinc smelting waste disposal.
EPA also compiled a list of 64 Natural Resource Damage Assessment (NRDA)
settlement sites where final settlements had been reached as of the end of 2012 (i.e., the period
covered by this report). Nine of the NRDA sites were also Case Study Historical sites, and data
from these sites' natural resource injury assessment documents are included in this report.
Findings for 2009 Current Sites
EPA identified 491 mining and mineral processing sites operating in 2009, using data
from the Department of Labor's Mine Safety and Health Administration (MSHA) and the
Department of Interior's U.S. Geological Survey (USGS). These "2009 Current" sites mine or
process the same commodities that were mined or processed at the Historical sites. Nine of the
2009 Current sites are also Historical sites, and six of those nine were among the Case Study
Historical sites for which EPA reviewed detailed Superfund risk assessment information.
EPA searched documents for available information on mining and mineral processing
practices at the 2009 Current sites. Mining and mineral processing practices at the 2009 Current
sites were then compared to practices at the Case Study Historical sites to assess whether similar
sources of potential hazardous substance releases could also occur at 2009 Current sites.
EPA also reviewed its databases to identify evidence of CERCLA hazardous substances
present at, or released from, 2009 Current sites. EPA found that 121 (24%) of 2009 Current sites
reported on-site releases of CERCLA hazardous substances to the Toxics Release Inventory
(TRI). These on-site 2009 releases totaled almost 300 million pounds. The most frequently
reported CERCLA hazardous substances released on site were lead compounds, followed by
ES-3
-------
9/23/2016
copper, mercury, zinc, manganese, nickel compounds, ammonia, and 58 other hazardous
substances. In terms of total quantities released, five CERCLA hazardous substances (lead, zinc,
copper, arsenic, and manganese, in that order) accounted for 85% of the total. Sixty-six percent
of the total quantity of hazardous substances reported as released on site in 2009 were from the
10 highest reporting facilities, which included four lead/zinc ore mines, two copper smelters, one
gold mine, one silver mine, one iron and steel mill, and one copper/nickel ore mine.
EPA also compiled information on the 2009 Current sites that are required by their
National Pollutant Discharge Elimination System (NPDES) permits to monitor and report
releases of hazardous substances to surface waters. This evaluation found that roughly 14% of
the sites reported discharging CERCLA hazardous substances to surface waterbodies in
quantities that exceeded their NPDES permit limits.
In addition to the data regarding the presence and release of CERCLA hazardous
substances, EPA compiled data in a geographic information system (GIS) to estimate the
proximity of human and ecological receptors to 2009 Current sites in the contiguous United
States and Alaska. Findings include:
Roughly half of the sites are located in moderately or densely populated areas, based on
the U.S. Census Bureau's 2000 population estimates.
An estimated 82% of the sites in the contiguous United States are within a 24-hour travel
distance upstream of non-tribal drinking water sources. An estimated 45% of sites in
Alaska are a similar distance upstream of non-tribal drinking water sources.
An estimated 3% of sites in the contiguous U.S. are within a 24-hour travel distance
upstream of tribal drinking water sources. (Relevant information was not available to
evaluate sites in Alaska.)
An estimated 32% of the sites (i.e., in both the contiguous United States and Alaska) are
within a 24-hour travel distance upstream of river/stream segments listed as impaired
waters under Section §3 03(d) of the Clean Water Act.
An estimated 23% of the sites have reported TRI releases of the Priority COCs or have
NPDES permits with numerical permit limits for the Priority COCs.
An estimated 57% of the sites are within Federal Emergency Management Agency
(FEMA) special flood hazard areas: in the event of a "base" flood (also known as a 100-
year flood) these sites may experience hazardous substance releases associated with
floodwaters contributing to hazardous substance movement.
Findings regarding potential ecological receptors at 2009 Current sites include:
An estimated 6% of the sites are located within 3 miles of a critical habitat designated for
federally listed threatened or endangered species.
An estimated 37% of the sites are within a 24-hour travel distance upstream of dams on
waterbodies that may provide habitat for aquatic receptors.
An estimated 34% of the sites in the contiguous U.S. are within a 24-hour travel distance
upstream from river/stream segments listed as impaired waters under Section §303(d) of
the Clean Water Act. This does not necessarily mean that the 2009 Current sites located
upstream from impaired waters are contributing to the water quality problems in those
segments; rather, it is an indication of proximity to an already impacted water resource
and ecological receptor habitat.
ES-4
-------
9/23/2016
The findings for human and ecological receptor proximity to the 2009 Current sites,
where exposures to CERCLA hazardous substance releases could be of concern, are uncertain.
One source of uncertainty is the uncertainty regarding the exact location of each 2009 Current
site. Other sources of uncertainty are information source-specific, such as uncertainty from the
use of Census Bureau data to estimate residence locations, as well as the age of the data (from
Census 2000). However, despite the uncertainties with the findings, they can be useful in
providing context regarding the potential for future CERCLA hazardous substance exposures
from mines and mineral processors.
Using Case Study Historical Sites to Predict Potential Human and
Ecological Exposure to CERCLA Hazardous Substances from 2009
Current Sites
Based on the 2009-2012 data collection and analysis, EPA has concluded the following:
Case Study Historical Sites: Human health and ecological risk estimates in Superfund
risk assessments are site-specific and highly variable. CERCLA hazardous substances
that often drive the risk estimates include several metals, radionuclides, Polychlorinated
biphenyls (PCBs), and Polynuclear Aromatic Hydrocarbons (PAHs). The human
receptors affected, or potentially affected, are frequently site workers, nearby residents
(including children), and site trespassers. Ecological receptors are typically flora and
fauna that inhabit the sites. The COCs migrate through the environment and affect human
or ecological receptors, or potentially affect future receptors, via specific exposure
pathways. Human exposure pathways include: surface water and ground water
contamination that affects drinking water sources, and soil and food plant contamination
that affects nearby residents. Ecological exposure pathways include: surface water
contamination that causes fish kills or otherwise adversely affects aquatic organisms, and
contamination of soil and prey that affects birds and mammals inhabiting the sites.
2009 Current Sites: Many mines and mineral processors operating in 2009 release
CERCLA hazardous substances that were identified as Contaminants of Concern at the
Case Study Historical Sites, and are located near both human and ecological receptors
that may be affected by those releases. Examples of CERCLA hazardous substances
frequently reported as released are lead and manganese. Examples of nearby receptors are
humans who drink water from surface water bodies downstream from the mine or
mineral processor site, and endangered species with habitat near the mine or mineral
processing site.
Considering 2009 Current Site Data in Light of the Case Study Historical Site Data:
Taken together, the data on mining and mineral processing practices, CERCLA
hazardous substances, receptors, environmental settings, and exposure pathways suggest
the following potential for exposure of human and ecological receptors to CERCLA
hazardous substance releases from the 2009 Current sites:
- Some of the 2009 Current sites are also in the universe of 108(b) Historical CERCLA
sites.
ES-5
-------
9/23/2016
- Mining and mineral processing practices at the Case Study Historical sites continue to
be used at the 2009 Current sites, especially when comparing sites that mine or
process the same range of commodities.
- There are similarities between the Priority COCs reported at the Case Study
Historical sites and the CERCLA hazardous substances reported in TRI and NPDES
permit reporting from 2009 Current sites;
- Human and ecological receptors at Case Study Historical sites have parallel potential
receptors at 2009 Current sites.
- Environmental settings and exposure pathways at Case Study Historical sites have
corresponding environmental settings and potential exposure pathways at 2009
Current sites.
The compiled information demonstrates that the 2009 Current sites share characteristics
with the Case Study Historical sites, and illustrates the applicability of EPA's CERCLA
experience to evaluating currently operating mines and processors.
ES-6
-------
9/23/2016
1.0 Introduction and Problem Formulation
The purpose of this report is to document the efforts that EPA undertook, from 2009 to
2012, to 1) determine what mining and mineral processing practices and contamination patterns
have historically caused Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA, also known as Superfund) cleanups to occur, 2) identify the corresponding
Superfund human health and environmental risk estimates, with an emphasis on the relevant
CERCLA hazardous substances and human and ecological receptor exposures, and 3) describe
the extent to which those same practices, contamination patterns, CERCLA hazardous
substances and receptor exposures may occur at current and future mining and mineral
processing sites.
1.1 Background and Purpose
The CERCLA, Section 108(b) directs the President to promulgate requirements that
...classes offacilities establish and maintain evidence offinancial
responsibility consistent with the degree and duration of risk associated
with the production, transportation, treatment, storage, or disposal of
hazardous substances.
As authorized by the President, the EPA Administrator determined that mines and
processors of metal and non-fuel, non-metallic mineral resources were those for which financial
responsibility regulations would first be developed. EPA published a Federal Register notice in
July 2009 (74 FR 37213-37219) stating that
...the Agency has identified classes offacilities within the hard rock
mining industry as its priority for the development offinancial
responsibility requirements under CERCLA Section 108(b). For purposes
of this notice only, hardrock mining is defined as the extraction,
beneficiation or processing of metals (e.g., copper, gold, iron, lead,
magnesium, molybdenum, silver, uranium, and zinc) and non-metallic,
non-fuel minerals (e.g., asbestos, gypsum, phosphate rock, and sulfur).
Note that the July 2009 Federal Register notice defined the phrase hard rock mining as
encompassing several minerals that professional geologists and miners generally would not
consider to be hard rock minerals. Therefore, to avoid confusion, EPA is using phrases such as
minins and mineral processing or mines and mineral processors throughout this document to
indicate the economic sector that is the subject of this analysis.
To further focus the list of potentially regulated mines and mineral processors to those
most likely to cause risk, EPA published a memorandum to the record ("Mining Classes Not
Included in Identified Hardrock Mining Classes of Facilities," June 29, 2009, document number
EPA-HQ-SFUND-2009-0265-0003, U.S. EPA (2009a)) which lists 59 MSHA commodities to be
excluded from 108(b) regulation.
Current and future sites are represented in this analysis by sites operational in 2009.
Considerable information is available on current mining and mineral processing practices, the
types of associated contamination, and the cost of consequent cleanup activities. However,
relatively few Superfund risk assessments have been conducted at currently operating sites. For
1
-------
9/23/2016
the majority of sites operational in 2009, EPA could not locate Superfund risk assessments or
public health assessment. The sites operational in 2009 for which EPA located Superfund risk
assessments or public health assessments are listed in Appendix A.
Stated specifically, the purpose of this report is to summarize data on
the presence of CERCLA hazardous substances at Superfund cleanup sites where mining
and mineral processing occurred and for which Superfund risk assessments have found
human health or ecological risks at or above levels of concern;
the presence of those same CERCLA hazardous substances at mining and mineral
processing sites operating in 2009;
the known current, or potential future, human and ecological exposures at Superfund
cleanup sites where mining or mineral processing occurred; and
evidence of potential for similar human and ecological exposures to CERCLA hazardous
substances from current mining and mineral processing sites.
Taken together, this set of information comprises evidence for estimating potential human and
ecological exposures to CERCLA hazardous substances released from mining and mineral
processing sites for which no Superfund risk assessments have yet been conducted.
1.2 Scope
The scope of this document is limited to human health and ecological risks resulting from
exposure, or potential exposure, to CERCLA hazardous substances, as defined in CERCLA
Section 101 (42 U.S.C. 9601(14)). In all, EPA has designated more than 800 substances as
CERCLA hazardous, along with approximately 760 individually listed radionuclides, according
to the statutory definition.1 Physical safety hazards such as electrocution, ground subsidence, or
trips/falls/entrapment hazards are not within the scope of this analysis because the scope of the
National Contingency Plan (NCP) does not include physical safety hazards.2 The NCP is the
federal government's organizational structure and procedures for preparing for and responding
to, among other things, hazardous substance releases.
In this document, EPA has collected Superfund risk estimates, as well as data regarding
human and ecological exposure to CERCLA hazardous substances, for two groups of mining and
mineral processing sites:
108(b) Historical CERCLA sites: Sites where CERCLA authority has been used for
hazardous substance remediation. This includes NPL sites, Removal sites, and sites cleaned
up as part of a CERCLA enforcement action. This report refers to the universe of these sites
as the 108(b) Historical CERCLA Sites universe, to individual members as Historical sites,
and to the subset of this universe selected for in-depth data collection and analysis as Case
Study Historical sites; and
2009 Current sites: Sites that mined or processed commodities of interest and were
operational, to varying extents, during calendar year 2009. For the purposes of this analysis,
1 The full list of CERCLA hazardous substances, as well as their reportable quantities, is in Title 40 of the Code of
Federal Regulations in Section 302.4 (40 CFR 302.4).
2 See 40 CFR 300.3 for the scope statement of the NCP.
2
-------
9/23/2016
these sites represent the current (and future) sites to be regulated under the CERCLA section
108(b) proposal. This report refers to these sites as 2009 Current sites.
The two groups (i.e., Historical sites and 2009 Current sites) overlap to a limited extent.
As described in detail in Appendix B, roughly 5 percent of the 2009 Current sites have been
previously addressed under Superfund.
1.3 Methodology and Data Sources
The following provides an overview of the methodology employed to identify known
risks at Historical sites and the potential for similar human and ecological exposures to CERCLA
hazardous substances at the 2009 Current sites. Appendix B presents an in-depth description of
the methodology and data sources used.
1.3.1 Defining the Universes of Sites Evaluated in this Study
Historical Sites
EPA began with the EPA National Mining Team's list of abandoned mine lands: those
lands, waters and surrounding watersheds where extraction, beneficiation or processing of ores
and minerals has occurred. This list was filtered to include only mines and mineral processors of
the metal and non-fuel, non-metallic mineral resources identified in the July 2009 FR notice (74
FR 37213-37219), and to exclude mines and mineral processors of commodities listed in EPA
(2009a). The following criteria were used to select relevant CERCLA sites:
Mining or mineral processing occurred at the site (either alone, together, or in
combination with other activities).
For mineral processing, CERCLA site documents describing site activities mention
processing of primary (i.e., earthen) mineral resources rather than only secondary mineral
resources (i.e., already circulating within the economy and returned for recovery).
The site is or had been addressed by EPA under CERCLA as an NPL site, a removal site,
a site cleaned up as part of a CERCLA enforcement action, or some combination of
these.
Site contamination resulted at least in part from mining or mineral processing activities
that occurred at the site, rather than solely from mining or mineral processing wastes
transported to the site from a different location or from other non-mining, non-mineral
processing activities.
The commodity or commodities mined or processed at the site were metal and non-fuel,
non-metallic, mineral resources identified in the July 2009 FR notice, and
The commodity or commodities mined or processed at the site excluded from the rule per
EPA (2009a).
Operations at some of the qualifying Historical sites ceased many years ago, however,
and might not represent practices at current or future sites. Therefore, EPA identified the portion
of Historical sites where mining or mineral processing activities had occurred during or after
1980 and where risk assessments were available. This "post-1980" subset would represent sites
where practices resulting in contamination are confirmed, are expected to be similar to current-
day practices, and where risks have been characterized. From those sites, EPA randomly selected
3
-------
9/23/2016
sites for detailed evaluation. The sites chosen for detailed evaluation are called "Case Study
Historical sites" throughout this document and are listed in Appendix B, Table B-2.
2009 Current Sites
EPA initially identified relevant mining and/or processing sites in operation during the
2007-2009 calendar years based on two data sources:
The U.S. Department of Labor's Mine Safety and Health Administration (MSHA)
Mine Data Retrieval System: The Mine Data Retrieval System provides mine-by-mine
data for metal/non-metal mines and their contractors in the United States, Puerto Rico,
and the Virgin Islands. It contains data related to accidents, injuries, inspections,
violations, assessments, and field samples, as well as employment and production reports.
U.S. Geological Survey (USGS) Minerals Yearbooks: The Minerals Yearbooks are
published annually and provide reviews of the mineral and material industries of the
United States and foreign countries, including statistical data on materials and minerals,
as well as information on economic and technical trends and development.
There is a significant amount of overlap between the MSHA commodities and the USGS
commodities, and in many instances the commodity names are identical. After merging the two
commodity lists, EPA filtered for metal and non-metallic, non-fuel minerals identified in the July
2009 FR notice, and excluded those identified in EPA (2009a).
The degree to which a site was in active operation during the 2009 time frame could vary
substantially from site to site. For the purpose of this analysis, sites were considered operational
as long as they had the potential to resume active operations during the 2007-2009 calendar
years.3
The methodology for identifying the universe of 2009 Current sites, the resulting list, and
overlap of the 2009 Current sites and Historical sites, are discussed in detail in Appendix B,
Section B.3.
1.3.2 Mining and Mineral Processing Practices Responsible or Potentially
Responsible for CERCLA Hazardous Substance Releases
Historical Sites
For the Case Study Historical sites, EPA reviewed Records of Decision (RODs),
Superfund risk assessments, and other CERCLA site documents to identify the site histories.
These data include dates of active operation, mining and mineral processing practices, and waste
disposal practices that were identified as contributing to or resulting in the hazardous substance
releases found to present risks at or above levels of concern. Section 2 describes the summary-
level findings at the Case Study Historical sites.
3 At the time the lists were constructed, the USGS Minerals Yearbooks were available only for 2007 and 2008, and
the processors listed might or might not have still been operating in 2009. This does raise some uncertainty about
2009 operating status; however, these sites are referred to throughout this report as "2009 Current sites" for
simplicity.
4
-------
9/23/2016
2009 Current Sites
EPA reviewed information in Identification and Description of Mineral Processing
Sectors and Waste Streams (U.S. EPA, 1995a) to determine whether mining, mineral processing,
and waste disposal practices at 2009 Current sites were similar to the practices at the Case Study
Historical sites. Section 2 describes the summary-level findings. Appendix C presents more
detailed data on specific site practices.
1.3.3 Hazardous Substance Release Mechanisms
Historical Sites
At Case Study Historical sites, a wide range of mining, mineral processing, and waste
management practices were used. The probability of a CERCLA hazardous substance release
occurring is also influenced by site characteristics, as well as by physical phenomena such as the
rate of the release and its magnitude. Site characteristics such as climate, soil types, geological
settings, topography, and hydrology can play a major role in influencing CERCLA hazardous
substance releases. Section 2 presents additional information for the site characteristics that
affected CERCLA hazardous substance releases at the Case Study Historical sites.
2009 Current Sites
The scope of this analysis included some analysis of topography and hydrology,
including whether the 2009 Current sites were located within a 24-hour time of travel
downstream to a 100-year floodplain area designated by the Federal Emergency Management
Agency (FEMA) as a special flood hazard area. The scope of this analysis did not include site-
specific determinations of site characteristics such as climate, soil types, or geological settings
that can affect rates or magnitudes of hazardous substance releases. Section 2 presents summary-
level information on the proximity of the 2009 Current sites to special flood hazard areas.
1.3.4 Hazardous Substances of Concern
Historical Sites
To identify the CERCLA hazardous substances found to pose human health or ecological
risks above levels of concern, EPA reviewed detailed site data from Superfund risk assessments
and Records of Decision (RODs) for the Case Study Historical sites. For each site, EPA
identified the contaminants of concern (COCs) found to cause reasonable maximum exposure
(RME) risks at or above levels of concern. From these identified COCs, EPA selected a subset of
the COCs most frequently found to be risk drivers at the Case Study Historical sites. The COCs
identified as risk drivers at four or more sites were retained in the study for further evaluation.
These frequent COCs are referred to throughout the rest of this report as Priority COCs. Section
2 identifies the COCs found at the Case Study Historical sites, as well as the subset of Priority
COCs. See Appendix D for more details about the identification of COCs and selection of
Priority COCs at Case Study Historical sites.
2009 Current Sites
EPA reviewed existing data sources containing records of the release and onsite presence
or management of CERCLA hazardous substances at 2009 Current sites. Appendix F describes
the data and data sources reviewed, including those sources found to contain insufficient data to
5
-------
9/23/2016
develop evidence for this analysis. Two EPA databases were found to contain the most useful
information for the purposes of this analysis:
The Toxic Release Inventory (TRI): A database of reported releases of certain toxic
chemicals. Contains data on various types of releases, including but not limited to, release
to onsite facilities for treatment, disposal (e.g., in a landfill or injection well), or
recycling, as well as uncontrolled or other emissions (e.g., fugitive emissions to air). Data
also cover transfers offsite for treatment, disposal or recycling. Data are collected for
over 600 toxic chemicals from thousands of U.S. facilities.
Discharge Monitoring Reports (DMRs) from the National Pollutant Discharge
Elimination System (NPDES): Publicly available periodic reports on point source
discharges to surface water bodies. Both the Integrated Compliance Information System
(ICIS) and Permit Compliance System (PCS) databases were used to identify relevant
DMR data.
Because most 2009 Current sites are not Superfund sites, data on the presence of
CERCLA hazardous substances at 2009 Current sites were collected from other programs. This
report used data obtained from the TRI and NPDES EPA databases to characterize primarily the
types and secondarily, when available, estimate amounts of CERCLA hazardous substances
present at the 2009 Current sites. Section 2 presents the summary-level information from both of
these data sources, while Appendix F presents complete tables of CERCLA hazardous substance
release data for the 2009 Current sites.
1.3.5 Exposures to Hazardous Substances: Receptors
Historical Sites
The Superfund risk assessment conducted for each Historical site generally identifies
current and future potential land uses to define likely human and ecological receptors at or near
the site. Each Superfund risk assessment identifies the receptor types for which risks are
assessed. Examples of common receptor types assessed include current or future nearby
residents, current or future trespassers onto the site, and flora/fauna inhabiting the site itself
either currently or in the future. Distances to receptors are not usually directly measured as part
of the Superfund risk assessment; instead, at most sites field samples of soil, surface water,
sediment, or well-water samples, and sometimes plant or animal tissues, are taken in order to
determine exposure point concentrations that are used in the site-specific risk calculations.
Section 3 presents summary-level information of receptor types assessed at the Case Study
Historical sites.
2009 Current Sites
For the 2009 Current sites, EPA attempted to identify the specific locations (latitude and
longitude) for each site, using publicly available data. EPA assigned a three-tiered code to reflect
confidence in the quality of the site location assumption. Appendix E provides a detailed
discussion of the development of the geographic data and confidence codes and a description of
the entire geographic information system (GIS) analysis used to support this document.
In this report, EPA assumed that all residents near the sites are receptors of potential
concern. EPA compiled U.S. Census Bureau data on distances from the identified site
6
-------
9/23/2016
latitudes/longitudes to nearby residences within various buffer zones extending up to 20 miles
from the identified site locations. In addition, EPA analyzed information on the proximity of
drinking water source protection areas to the 2009 Current sites, in order to develop general
knowledge of potential impacts of mining or mineral processing sites on drinking water supplies.
Section 3 presents the summary-level information developed for nearby human receptors of
potential concern and proximity to drinking water supply locations, while Appendix G presents
the more detailed data tables for selected buffer distances to nearby residences.
EPA considered all federally designated threatened or endangered species with critical
habitat designated within 20 miles of the identified site latitude/longitude as ecological receptors
of potential concern. To do so, EPA used the "Final Critical Habitat" dataset produced by the
U.S. Fish and Wildlife Service. These data identify the areas where final critical habitat exist for
species listed as endangered or threatened. The Final Critical Habitat data were downloaded from
the U.S. Fish and Wildlife Service in May 2010. For the 2009 Current sites, EPA did not attempt
to define any species besides federally designated threatened or endangered species as being
receptors of potential concern, because data at the level of resolution needed was not available.
However, EPA recognizes that substantial impacts on non-federally listed species could occur,
especially in situations where acidic mine drainage could adversely affect populations of aquatic
organisms in surface water bodies down-gradient from mining or mineral processing operations.
Section 3 presents the summary-level information developed for nearby federally designated
critical habitat, for federally listed threatened or endangered species, while Appendix H presents
more detailed data tables related to ecological receptors.
1.3.6 Exposure Pathways/Routes
Historical Sites
Superfund risk assessments identify complete exposure pathways, meaning a sequence of
environmental media through which CERCLA hazardous substances move when migrating from
the site to a receptor. These risk assessments also identify potential exposure pathways when
future receptors are assessed or when inadequate information exists to definitively confirm a
complete exposure pathway. Exposure routes are the avenues by which the CERCLA hazardous
substance comes into contact with an organism, such as ingestion by humans or animals,
inhalation by humans or animals, or dermal contact by humans or animals, including aquatic
organisms living in surface water bodies affected by CERCLA hazardous substance releases.
Section 3 presents summary-level information on the exposure pathways and exposure routes
found at the Case Study Historical sites.
2009 Current Sites
Because relatively few Superfund risk assessments have been conducted for the 2009
Current sites, EPA currently lacks data on specific complete exposure pathways at most of these
sites. Section 3 presents the data that are available from Superfund risk assessments of the 2009
Current sites, presents the data from the GIS analysis that suggests potential exposure pathways,
and compares them with exposure pathways evaluated in Superfund risk assessments of the Case
Study Historical sites.
7
-------
9/23/2016
1.3.7 Discussion of Findings, and Public Health Assessments
EPA utilized multiple information sources to determine the potential for human and/or
ecological exposure to CERCLA hazardous substances from mining and mineral processing sites
operating in 2009. Section 4 reviews the summary-level information that EPA has compiled for
similarities between the Case Study Historical sites and 2009 Current sites; comparing mining,
mineral processing, and waste management practices, CERCLA hazardous substance releases,
release mechanisms, receptor types, and exposure pathways and routes. Section 4 also reviews
the major sources of uncertainty in this report.
Public Health Assessments (PHAs) and Health Consultations (HCs) conducted by the
federal Agency for Toxic Substances and Disease Registry (ATSDR) address public health
impacts of mining and mineral processing sites; Section 4 describes those findings, where
available, for the Case Study Historical sites, the broader universe of 108(b) Historical CERCLA
Sites and, in a few instances, 2009 Current sites that have not been addressed by CERCLA
cleanup authority. Finally, EPA briefly reviews some of the data from other countries that
documented human health and ecological impacts from mining and mineral processing activities.
8
-------
9/23/2016
2.0 Hazard Identification
To identify potential hazards warranting regulation under CERCLA Section 108(b), this
section first describes the universes of 108(b) Historical CERCLA sites and 2009 Current sites
(Section 2.1). Sections then describe the mining and mineral processing practices responsible for
CERCLA hazardous substance releases (Section 2.2), the release mechanisms (Section 2.3), and
the CERCLA Contaminants of Concern (COCs, Section 2.4) associated with each Historical or
2009 Current site.
2.1 Universes of Sites Reviewed in this Study
Using the methodology described in Section 1.3.1, EPA identified a universe of 108(b)
Historical CERCLA Sites to represent Superfund estimated risks associated with mining and
mineral processing activities cleaned up using CERCLA authority, and a universe of sites
operating in 2009 (i.e., 2009 Current sites) to represent current and future mining and mineral
processing sites. How these two universes were identified is described below.
2.1.1 Historical Sites
This report reviewed CERCLA experience related to human health and ecological risks
associated with past mining and mineral processing activities. To obtain Superfund risk estimates
and information on human and ecological exposures to CERCLA hazardous substances, EPA
used the methodology summarized in Section 1.3 (above), and described in detail in Appendix
B, to identify the universe of mining and mineral processing sites (i.e., sites relevant to the
108(b) hard-rock mining rule) that have been subject to cleanup actions under CERCLA
authority. This effort identified a universe of 251 sites, referred to in this report as the 108(b)
Historical CERCLA Sites universe. See Appendix B, Attachment Bl, for a complete listing of
the 108(b) Historical CERCLA Sites universe.
A detailed review of Superfund risk assessments and other CERCLA site documents for
all sites in the 108(b) Historical CERCLA Sites universe was not possible within time and
funding constraints. Therefore, EPA selected a subset of these sites for more in-depth review. To
better represent current mining and processing operations and practices, EPA randomly selected
30 sites (including 24 NPL sites and 6 removal sites) that had operated after 1980. CERCLA site
documents were reviewed to identify numerical risk estimates, as well as contextual information
for those estimates, such as specific hazardous substances; the contaminated media; exposure
pathways and routes; and, for ecological receptors, the species, if available. While collecting data
for the randomly selected sites, EPA found that insufficient data were available for the sample of
Removal and other non-NPL sites. As a result, only detailed data from the 24 NPL sites were
available to use in the report. The report refers to these 24 NPL sites as Case Study Historical
sites.
Based on ongoing QA/QC of the 108(b) Historical CERCLA Sites list, EPA decided to
continue developing the 108(b) Historical CERCLA Sites universe. As described in detail in
Appendix B Section B.2 ("Expanded List of Historical Sites and Supplemental Sampling"), the
continued development culminated in a universe of 448 sites.
EPA also found that the range of commodities mined or processed at Case Study
Historical sites was limited when compared to the entire 108(b) Historical CERCLA Sites
9
-------
9/23/2016
universe. EPA therefore conducted a supplemental selection and data collection for additional
historical sites. However, while this report describes the selection and data collection for these
supplemental sites in order to completely document EPA's 2009 - 2012 research efforts, the data
were not available in time to be included in the comparisons to 2009 Current site data.
References to "Case Study Historical sites" in the remainder of this report refer only to the
original, randomly selected 24 NPL sites, and any conclusions drawn by this evaluation are
based solely on data from the 24 NPL sites and not on data from the supplemental sites.
Appendix B describes in detail the original development and subsequent expansion of the
108(b) Historical CERCLA Sites universe. Appendix B also describes the process used to
randomly select and collect data for the initial Case Study Historical sites, as well as the process
used to select and collect data for the supplemental sites.
2.1.2 2009 Current Sites
A set of sites representative of current and future mining and mineral processing sites
potentially subject to CERCLA 108(b) requirements was also needed. Two federal agencies
monitor the existence and activities of U.S. mines and mineral processors: the Department of
Interior's U.S. Geological Survey (USGS), which conducts annual surveys to determine
production rates and commodity prices, and the Department of Labor's Mine Safety and Health
Administration (MSHA), which collects mine safety compliance and employment information.
EPA used data from both agencies to construct a list of mining or mineral processing sites in
operation during calendar year 2009.
Each agency uses different nomenclature to identify specific mineral commodities, so
EPA combined mineral commodities that were named similarly by both USGS and MSHA. EPA
then compiled mining and mineral processing site information for the subset of commodities that
were not excluded from consideration in the CERCLA 108(b) rule, per U.S. EPA (2009a).
Appendix B also contains the list of commodities that EPA used to compile mining and mineral
processing sites.
Defining whether a mining or mineral processing site is "in operation" is complicated
somewhat by the tendency of mines and mineral processors to limit or shut down their operations
because of external pressures such as commodity price fluctuations. Such shutdowns affect the
probability of hazardous substance releases occurring. Because the proposed rule aims to
internalize costs associated with cleanups of CERCLA hazardous substance releases, EPA
needed to identify sites with an operating status similar to those that would be subject to the
proposed rule. Therefore, EPA chose to develop a list of mines and mineral processors that were
operatinginterpreted broadly as not abandonedat some point during calendar year 2009. For
example, the MSHA database contains five mine status codes: active, intermittent, non-
producing, new, and abandoned. EPA included sites with any of these codes except abandoned.
From the USGS data, EPA included any additional mines and mineral processors that were not
identified in the MSHA database but were mentioned in a published USGS Minerals Yearbook
for 2009. Thus, the degree to which a site was in active operation during 2009 may vary
substantially from site to site, from mines or mineral processors that actively produced
commodities throughout the entire year, to mines or mineral processors that were essentially
inactive for much or all of the year but that had not notified MSHA to change their mine status to
"abandoned."
10
-------
9/23/2016
Using the methodology described above resulted in a universe of 491 sites in the
contiguous United States and Alaska, referred to in the remainder of this report as the 2009
Current Sites universe, and individual members as 2009 Current sites. Appendix B Attachment
B5 lists the 2009 Current Sites universe. The locations for 74 of the 2009 Current sites could not
be identified with confidence (e.g., location-related information, such as address, were for a
corporate office and not the location of the facility itself). The locations of the remaining 417
sites, including 22 sites in Alaska, could be verified and were presumed to be accurate.
Therefore, analyses that were based on spatial relations (for example, populations within a
certain distance of a site) were only performed on the 417 sites with verifiable locations.
In addition, some analyses could not be run for sites in Alaska because of lack of data. In
such cases, the total number of valid sites is 395. Where the number 417 is used in the text, it is
referring to all sites with verifiable locations; where the number 395 is used, it is referring to
those sites with verifiable locations in the contiguous United States.
2.2 Mining and Mineral Processing Practices
Five general methods are used to extract metal and nonmetallic resources in the United
States; the method used depends on characteristics of the ore body or brine/water resource, its
position within the earth, and economic considerations:
Brine/surface water/ground water extraction removes compounds such as boron,
bromine, iodine, lithium, and magnesium compounds from the brine or water supply.
Solution mining extracts metals in ores by injecting and circulating chemical solutions
through ore and recovering those solutions for processing.
Surface mining removes ores at the surface by removing overburden.
Underground mining remove ores underground, where miners access ore bodies via
adits, mine shafts, and tunnels.
Placer mining removes target metals from placer deposits located in sand, gravel, or
rock, typically deposited by flowing water (and thus usually located in or adjacent to
surface water bodies).4
For the purposes of this report EPA considers all of these types of mining except surface water
extraction as potentially subject to the 108(b) requirements.
Processing non-fuel minerals includes a range of activities that depend on ore or
brine/water characteristics and typically occur in a stepwise manner to increase the concentration
of the target material within the medium being processed. The entire range of processing
activities spans a continuum between the initial manipulation of the ore or brine/water upon
removal from the earth and highly specialized steps that produce the final target material to a
customer's exact specifications. Some mineral processing is categorized as chemical
manufacturing and, thus, would be outside the scope of the proposed 108(b) regulations for
mining and mineral processing.
MSHA defines a coal or other mine as
4 Currently, most of the placer mining sites (except those using CERCLA hazardous substances) are not included in
the 2016 proposed CERCLA 108(b) rule.
11
-------
9/23/2016
(a) an area of land from which minerals are extracted in nonliquid form
or, if in liquidform, are extracted with workers underground, (b) private
ways and roads appurtenant to such area, and (c) lands, excavations,
underground passageways, shafts, slopes, tunnels and workings,
structures, facilities, equipment, machines, tools, or other property
including impoundments, retention dams, and tailings ponds, on the
surface or underground, used in, or to be used in, or resulting from, the
work of extracting such minerals from their natural deposits in nonliquid
form, or if in liquidform, with workers underground, or used in, or to be
used in, the milling of such minerals, or the work ofpreparing coal or
other minerals, and includes custom coal preparation facilities. In making
a determination of what constitutes mineral milling for purposes of this
act, the Secretary shall give due consideration to the convenience of
administration resulting from the delegation to one Assistant Secretary of
all authority with respect to the health and safety of miners employed at
one physical establishment. (30 CFR 41.1(c))
The MSHA regulations apply to facilities that mine and mill minerals, but as the final
sentence in this definition indicates, the worker safety requirements at mineral processing sites
are sometimes handled by a different agency within the Department of Labor. Thus, MSHA
records include all mines known to MSHA to extract minerals from the earth, according to the
definition of mine in 30 CFR 41.1(c), including those that also process minerals at or near the
mine site and some, but not all, mineral processing sites.
In contrast to this definition, USGS uses slightly different criteria for identifying mines
and mineral processors for which it publishes statistics for mineral production:
Although crude mineral production may be measured at any of several
stages of extraction and processing, the stage of measurement used in this
annual report is what is termed "mine output. " This term refers to
minerals or ores in the form in which they are first extracted from the
ground, but customarily may include the output from auxiliary processing
at or near the mines. (USGS, 2011)
In practice, there are differences between whether a given facility would be considered a
"mine" under the MSHA regulations and whether USGS would report its production in its
Minerals Yearbooks. For example, MSHA's limitation for liquid extraction operations where
workers are underground means that MSHA might not consider sites extracting minerals from
surface waters, ground water, or in-situ solution mining to be mines, while USGS does consider
them to be mines because they are producing minerals.
2.2.1 Historical Sites
EPA grouped the Case Study Historical sites into 6 categories, based on the type of
commodity mined or processed at each site, and then assessed the specific mining and mineral
processing practices used at each site:
Aluminum: Three of the Case Study Historical sites were aluminum smelters, and all
used the Hall-Heroult production process. CERCLA site documents for all three of these
sites list a common waste management practice on-site disposal of a waste referred to
12
-------
9/23/2016
as "potliners," which is generated from the Hall-Heroult process as the source of site-
related contamination.
Iron and steel: One of the Case Study Historical sites was a ferrochromium alloy
manufacturer that smelted chromium ore in an electric arc furnace. CERCLA site
documents indicate that calculated risks are related to on-site disposal of waste generated
at the site.
Phosphates: Three of the Case Study Historical sites processed phosphate. CERCLA site
documents for all three sites indicate that on-site waste disposal was the source of site
contamination. One waste stream identified in common among the three sites was slag
from processing of phosphate ore.
Primary metals: Twelve of the Case Study Historical sites mined or processed primary
metals. CERCLA site documents indicate three general types of mining or processing
practices that resulted in hazardous substance contamination requiring cleanup at these
sites: high-temperature smelting (5 sites), cyanide leaching and/or mercury amalgamation
of precious metals ore (4 sites), and exposure of sulfide-bearing rock resulting in acidic
mine drainage or tailings/waste rock drainage (7 sites). Some sites reported more than
one of these practices; hence, the number of sites sums to more than 12. On-site waste
disposal was reported for 11 of the 12 sites.
Radioactive metals: Two of the Case Study Historical sites mined radioactive metals.
CERCLA site documents indicated acidic mine drainage from onsite disposal as a
condition common to both sites that resulted in hazardous substance releases.
Other metals: Three of the Case Study Historical sites processed other metals. CERCLA
site documents indicated on-site disposal of mineral processing waste as the practice in
common at all three that resulted in hazardous substance releases.
Appendix C presents more detailed information on the mining and mineral processing
wastes documented for the Case Study Historical sites.
2.2.2 2009 Current Sites
Using the same categories described above for the Case Study Historical sites, EPA
reviewed the mining and mineral processing and waste management techniques used at the 2009
Current sites.
Aluminum: Two of the three aluminum smelters in the set of Case Study Historical sites
were still operating in 2009. It appears that all aluminum smelters operating in 2009 use
the same Hall-Heroult process that was used at the three Historical sites. However, an
important difference between the three Historical sites and the aluminum smelters
operational in 2009 is that the hazardous waste regulations under the Resource
Conservation and Recovery Act (RCRA) have now been in effect for a number of years;
those regulations modify the waste management practices substantially compared with
the practices that resulted in contamination at the three Historical sites.
Iron and steel: The single Case Study Historical site was a chromite ore processor that
produced ferrochromium alloys using electric arc furnaces. The single ferrochromium
alloy producer operational in 2009 produced ferrochromium via an electrolytic process.
Phosphates: Two of the three phosphate-related Case Study Historical sites were still
operating in 2009, and an additional 26 sites mined or processed phosphates in 2009.
13
-------
9/23/2016
Similar processes were used at the two Case Study Historical sites. The general processes
used at these sites are similar to those used today; however, the specific methodologies
used may differ among sites and over time.
Primary metals: Three of the 12 primary metal-related Case Study Historical sites were
still operating in 2009, and an additional 207 sites mined or processed primary metals in
2009. However, mining and processing practices have changed somewhat from those
used at the Case Study Historical sites. Specifically:
- High-temperature smelting practices have changed substantially, both in terms of
reductions in the absolute number of high-temperature smelters operating in the
United States and in terms of additional air emissions controls (and ensuing
contaminant release reductions) instituted in response to regulations (primarily Clean
Air Act regulations).
- While cyanide leaching of precious and certain base metals still occurs, voluntary and
state-mandated changes in practices, such as impermeable liners installed underneath
leaching areas to collect more of the leaching solution, have changed the potential for
releases of hazardous substances at certain sites. At other sites that either have not
voluntarily changed practices or are not mandated to change by state requirements,
there may be relatively few changes compared with the practices that occurred at the
Historical sites. At many, if not most, sites, changes may have occurred for the actual
leaching areas, while waste disposal area practices may have changed very little.
- EPA is not aware of mercury amalgamation occurring in the United States in 2009,
and EPA issued final regulations controlling mercury emissions from gold ore
processing operations in December 2010.
- Exposure of sulfide-bearing rock resulting in acidic mine drainage or tailings/waste
rock drainage can still occur at certain sites.
Radioactive metals: Neither of the two radioactive metals-related Case Study Historical
sites were still operating in 2009. However, eight of the 2009 Current sites mined or
processed uranium or thorium. At these sites, exposure of sulfide-bearing rock resulting
in acidic mine drainage or tailings/waste rock drainage remains a potential cause of
CERCLA hazardous substance releases, unless state requirements or voluntary practices
mitigate the conditions that lead to releases. However, because the development of acidic
mine drainage is a very long-term threat, even state-required or voluntary practices in
effect in the early 21st century may not mitigate conditions over the centuries during
which the threat may persist.
Other metals: One of the three Case Study Historical sites associated with other metals
was still operating in 2009, and an additional 49 sites mined or processed other metals or
non-metallic, non-fuel minerals in 2009. These sites include a wide range of practices due
to the widely varying nature of the ores and earthen materials being processed into a wide
range of products.
Appendix C describes in more detail the information that EPA found for mining and
mineral processing wastes documented for the 2009 Current sites.
14
-------
9/23/2016
2.3 Release Mechanisms
Environmental characteristics such as meteorological conditions (e.g., precipitation,
temperature, wind direction and speed), topography, and other site-specific factors play roles in
the potential for, and rate of, the movement of hazardous substances through the environment.
For example:
Higher temperatures can increase the rate at which mercury or other volatile compounds
move from rock, soil or water into the air.
Dusty conditions are more prevalent in dry climates than in wet climates, potentially
causing air to be a more important movement conduit than water.
Steep slopes increase precipitation runoff rates and resulting erosion into surface water
bodies.
Sites located in floodplains have an increased probability of hazardous substance
dispersion via flooding relative to sites not located in floodplains.
Clay soils often adsorb metal contaminants to a much greater degree than silty or sandy
soils, thus slowing the environmental transport relative to silty/sandy soils.
Superfund risk assessments often refer to these mechanisms as environmental fate and
transport processes. Fate and transport processes influence the types of environmental media (air,
soil, ground water, or surface water) that serve either as reservoirs of, or directional movement
conduits for, CERCLA hazardous substances.
2.3.1 Historical Sites
This analysis did not consider weather conditions, soil types, or geological settings at the
Case Study Historical sites. However, topography was considered to the extent that many of the
CERCLA site documents mentioned flooding as playing a role in dispersing CERCLA hazardous
substances from mining and mineral processing sites. In particular:
Past flood events or erosion due to water played a role in contamination.
At least part of the site was located within a 100-year floodplain at 10 sites (42%).
Flooding was a potential contaminant dispersion mechanism at 13 sites (54%).
Appendix I presents the flood scenarios found at the Case Study Historical sites.
2.3.2 2009 Current Sites
Site-specific analyses required verifiable locations for each 2009 Current site. As
introduced in Section 1.3 and described in detail in Appendix E, EPA attempted to identify the
specific location of each site and assign a three-tiered code to reflect confidence in the quality of
the site location information. EPA was able to map 417 of the 491 sites in the 2009 Current Sites
universe.
A GIS analysis determined which surface waterbodies receive runoff from 2009 Current
sites, and estimated if flooding of those waterbodies could affect the 2009 Current sites. FEMA
flood maps were overlain with the National Hydrography Dataset Plus (NHDplus) data layer to
perform this analysis. The analysis estimated that 236 out of 417 (57%) of the mining/mineral
processing sites in the continental U.S. and Alaska are within the 100-year floodplain of a river
or stream catchment. These sites have approximately a 1% annual chance of being inundated
15
-------
9/23/2016
during a flood event. If floodplain waters rise sufficiently, CERCLA hazardous substances
present at the sites may be released to surrounding media similar to scenarios that occurred at the
Case Study Historical sites.
Appendix I presents a list of the 2009 Current Sites located within 100-year flood zones.
2.4 CERCLA Contaminants of Concern (COCs)
2.4.1 Historical Sites
As specified in the NCP, 40 CFR 300.430(e)(2)(i), and introduced in Section 1.3.4, a
CERCLA hazardous substance estimated to cause risks at or above levels of concern is referred
to as a COC. Based on a review of Superfund risk assessments of the Case Study Historical
sites, EPA identified 86 unique COCs associated with those sites. Table 2-1 presents the list of
the 86 COCs associated with the Case Study Historical sites. Superfund risk assessments of some
sites identified only general categories of hazardous substances (e.g., "radionuclides").
To focus the remainder of this analysis, EPA identified the subset of COCs that occurred
most frequently at the Case Study Historical sites. COCs identified at four or more of the Case
Study Historical sites, due to either human health or ecological risks, were retained for further
evaluation and called Priority COCs.5 This selection was modeled after the ATSDR Priority List
(found at http://www.atsdr.cdc.gov/spl/). Table 2-1 also identifies the 27 Priority COCs and their
frequency at the Case Study Historical sites.
The toxicity of the Priority COCs is described in Section 2.5. Appendix D provides more
detail on the selection of the COCs and Priority COCs.
Table 2-1. CERCLA Hazardous Substances Identified in Superfund Risk Assessments
of Case Study Historical Sites
CAS
COC
No. of Sites
with Risks of
Concern
CAS
COC
No. of Sites
with Risks of
Concern
Human
Eco
Human
Eco
Priority Contaminants of Concern
Other Contaminants of Concern (continued)
7440-38-2
Arsenic & compounds
22
8
NA
Polynuclear aromatic
hydrocarbons
1
2
7439-96-5
Manganese & compounds
14
5
7440-66-6
Zinc & compounds
13
9
12674-11-2
Arodor 1016
1
1
7440-43-9
Cadmium & compounds
13
8
11104-28-2
Arodor 1221
1
1
7440-36-0
Antimony & compounds
11
6
11141-16-5
Arodor 1232
1
1
7440-41-7
Beryllium & compounds
9
4
207-08-9
Benzo[k]fluoranthene
1
1
7440-50-8
Copper & compounds
7
8
67-66-3
Chloroform
1
1
7439-97-6
Mercury & compounds
7
3
014952-40-0
Actinium-227
1
0
7439-92-1
Lead & compounds
6
10
111-44-4
Bis(2-chloroethyl)ether
1
0
7440-28-0
Thallium & compounds
6
7
75-25-2
Bromoform
1
0
7440-02-0
Nickel & compounds
6
3
56-23-5
Carbon tetrachloride
1
0
50-32-8
Benzo[a]pyrene
6
2
108-90-7
Chlorobenzene
1
0
205-99-2
Benzo[b]fluoranthene
6
2
106-46-7
Dichlorobenzene, 1,4-
1
0
5 Chemicals qualify as COC's (and therefore possibly as Priority COCs) because they have a toxicity value and can
therefore be quantitatively evaluated. Section 4.6 (Uncertainty) discusses chemicals that are not quantitatively
evaluated.
16
-------
9/23/2016
No. of Sites
No. of Sites
with Risks of
with Risks of
Concern
Concern
CAS
coc
Human
Eco
CAS
COC
Human
Eco
NA
Radionuclides
6
0
75-35-4
Dichloroethylene, 1,1-
1
0
13982-63-3
Radium-226
6
0
156-60-5
Dichloroethylene, 1,2-
1
0
7440-47-3
Chromium & compounds
5
6
75-09-2
Methylene chloride
1
0
7782-41-4
Fluorine (as fluoride)
5
3
13981-52-7
Polonium-210
1
0
56-55-3
Benz[a]anthracene
5
2
13966-00-2
Potassium-40
1
0
53-70-3
Dibenz[a,h]anthracene
5
1
7440-14-4
Radium
1
0
7440-61-1
Uranium-238
5
1
7440-29-1
Thorium-232
1
0
14255-04-0
Lead-210
5
0
71-55-6
Trichloroethane, 1,1,1-
1
0
1336-36-3
Polychlorinated biphenyls
4
2
7440-61-1
Uranium
1
0
14859-67-7
Radon-222
4
0
7440-61-1
Uranium-230
1
0
14274-82-9
Thorium-228
4
0
15117-96-1
Uranium-235
1
0
7440-22-4
Silver & compounds
3
4
75-01-4
Vinyl Chloride
1
0
7440-48-4
Cobalt compounds
3
3
129-00-0
Pyrene
0
3
7782-49-2
Selenium & compounds
2
6
83-32-9
Acenaphthene
0
2
Other Contaminants of Concern
208-96-8
Acenaphthylene
0
2
193-39-5
lndeno[1,2 3-cd]pyrene
3
1
191-24-2
Benzo(g,h,i)perylene
0
2
79-01-6
Trichloroethylene
3
1
117-81-7
Bis(2-ethylhexyl) phthalate
0
2
18540-29-9
Chromium (VI)
3
0
218-01-9
Chrysene
0
2
15262-20-1
Radium-228
3
0
85-01-8
Phenanthrene
0
2
127-18-4
Tetrachloroethylene
3
0
67-64-1
Acetone
0
1
14269-63-7
Thorium-230
3
0
120-12-7
Anthracene
0
1
13966-29-5
Uranium-234
3
0
85-68-7
Butyl benzyl phthlate
0
1
53469-21-9
Aroclor 1242
2
2
57-74-9
Chlordane, alpha isomer
0
1
12672-29-6
Aroclor 1248
2
2
106-44-5
Cresol, p-
0
1
57-12-5
Cyanides
2
2
72-54-8
DDD
0
1
11096-82-5
Aroclor 1260
2
1
72-55-9
DDE, 4,4'-
0
1
71-43-2
Benzene
2
0
50-29-3
DDT
0
1
107-06-2
Dichloroethane, 1,2-
2
0
72-20-8
Endrin
0
1
10043-92-2
Radon
2
0
206-44-0
Fluoranthene
0
1
79-34-5
Tetrachloroethane,1,1,2,2-
2
0
72-43-5
Methoxychlor
0
1
11097-69-1
Aroclor1254
1
2
7440-23-5
Sodium
0
1
2.4.2 2009 Current Sites
To evaluate the potential for release of the Priority COCs from the 2009 Current sites,
EPA used two data sources: The Toxics Release Inventory (TRI, available at
http://www2.epa.gov/toxics-release-inventory-tri-program) and Discharge Monitoring Reports
(DMRs, available at http://cfpub.epa.gov/dmr/) required under the National Pollutant Discharge
Elimination System (NPDES).
EPA reviewed TRI on-site release data for the reporting year 2009 for the 2009 Current
sites. These data indicate that 103 (21%) of the sites reported on-site releases of the Priority
COCs. In terms of quantity released, the top five Priority COCs released were, in order, lead,
zinc, copper, arsenic, and manganese. Together, these five substances accounted for 85% of the
total quantity of all the Priority COCs reported as released in TRI. Mercury accounted for less
than 1% of the total releases. The 10 facilities reporting the highest quantities released (four
17
-------
9/23/2016
lead/zinc mines, two copper smelters, one gold mine, one silver mine, one iron and steel mill,
and one copper/nickel mine) accounted for 66% of the total quantity of Priority COCs reported
in TRI as released on site in 2009. The Priority COCs most frequently reported as released on site
were lead compounds, followed by copper, mercury, zinc, manganese, nickel compounds,
ammonia, and 58 other hazardous substances.
Not all of the 27 Priority COCs listed in Table 2-1 were represented among the reported
TRI chemicals. EPA grouped the Priority COCs into four broad categories:
Non-radioactive metals: arsenic, manganese, cadmium, zinc, antimony, lead, beryllium,
copper, chromium, mercury, selenium, thallium, nickel, and silver, together with their
compounds
Radionuclides: the general category "radionuclides" and the specific radionuclides
radium-226, lead-210, uranium-238, radon-222, and thorium-228
Organics: benzo[a]pyrene, benzo[b]fluoranthene, benz[a]anthracene,
dibenz[a,h]anthracene, and polychlorinated biphenyls
Other: fluorine (as flouride).
Of these categories, only the members of the non-radioactive metals category and
fluorine were required to be reported in TRI reporting year 2009. None of the radionuclides were
required to be reported in 2009, and only one of the five organic compounds (polychlorinated
biphenyls) was required to be reported in 2009. Thus, the TRI release data are best used as an
information source on quantities of non-radionuclide metals and fluorine released on site at
mines and mineral processors.
It is important to note that the TRI may also under-report Priority COC releases. Because
of a court order stating that naturally occurring ores in situ have not been manufactured within
the meaning of the legislation authorizing TRI reporting, and some mining companies may
interpret the TRI reporting requirements as not applying to movement of rock materials and their
naturally occurring hazardous substance content as a result of mining practices. This may explain
why fewer than half of the 2009 Current mines appear to have reported to the 2009 TRI.
Submitted by NPDES permit holders, DMRs are another source of data regarding Priority
COC releases from 2009 Current sites. NPDES permits are required for direct discharges of
pollutants (as that term is defined in the Clean Water Act [CWA]) to the waters of the United
States. By definition in the CERCLA statute, all CWA pollutants are considered CERCLA
hazardous substances. Under the national NPDES program, permits for industrial facilities are
only issued for point sources of process wastewater, non-process wastewater, or site storm water
runoff that discharges directly into regulated surface waters, while industrial discharges from on-
site treatment facilities that are indirect discharges (i.e., flows conveyed through treatment
facilities prior to discharge) are regulated by the National Pretreatment Program and do not
require an NPDES permit. Discharges to groundwater are also typically not regulated under the
NPDES program unless hydrogeologic conditions allow an interaction with surface waters. Data
regarding monitored releases of hazardous substances from mining and mineral processing sites
into surface water bodies are documented in DMRs submitted to EPA by some, but not all,
NPDES permit holders.
Some, but not all NPDES direct point source discharge permits stipulate that the permit
holder monitor certain CWA pollutants and report the levels found to their state environmental
18
-------
9/23/2016
agency. The data are entered into one of two EPA databases: the Permit Compliance System
(PCS) or the Integrated Compliance Information System (ICIS).
For this evaluation EPA used data from both of these databases to define CERCLA
releases of Priority COCs. In CERCLA, hazardous substance "releases" do not include federally
permitted releases such as those allowed by an NPDES permit. Rather, CERCLA releases
include only releases that exceed the permit limit, and are therefore a subset of all CERCLA
hazardous substance discharges recorded in the PCS and ICIS databases.
Of the 2009 Current sites with verifiable locations (i.e., 417 sites), an estimated 57 (14%)
reported Priority COC releases to surface water bodies through permitted NPDES discharges that
exceeded the permitted discharge limit.
See Appendix F for more information on how the TRI and DMR data were extracted and
compiled, and tables showing the CERCLA hazardous substance and Priority COC releases to
surface water data for the 2009 Current sites.
The EPA's Effluent Guidelines program has conducted a detailed review of TRI data
from 2007 and DMR data for mines and mineral processors, among other industries (U.S. EPA,
2009b). Although these data do not match the 2009 time frame examined in this report, they do
provide similar findings regarding the number of sites and the quantities of toxic chemicals
released that corroborate the findings reported here.
Under Section 303(d) of the Clean Water Act, states, territories, and authorized tribes are
required to develop lists of impaired waters. These are waters that are too polluted or otherwise
degraded to meet the water quality standards set by states, territories, or authorized tribes. The
law requires that these jurisdictions establish priority rankings for waters on the lists and develop
Total Maximum Daily Loads (TMDLs) for these waters. A TMDL is a calculation of the
maximum amount of a pollutant that a waterbody can receive and still safely meet water quality
standards. A TMDL has been established along many of the streams that were evaluated using a
constructed Aquatic Area of Review (AqAoR - see Appendix H for a detailed discussion of how
AqAoRs were constructed and used). The streams identified in Appendix F by mine or
processor site represent only the principal waterbody of the aquatic area of review. Tributaries of
the principal stream may also have their own established TMDLs, and would be part of the
aquatic area of review, but are not identified; these streams may also be the source of the TMDL
at some distance downstream of the mine or processor site. Limitations of the original data
sources only allow inclusion of streams within the conterminous United States. A total of 134
streams are listed in Appendix F; however, the cause of the impairment has not been determined
for each stream. It should be noted that the identified mine or processor may not be the cause of
the impairment, but a release from the identified mine or processor could further deteriorate an
already stressed aquatic ecosystem or degrade stream quality to affect associated uses of the
stream (e.g., drinking water source or recreation). Appendix F also includes maps showing the
distribution of mines and facilities located along streams with established TMDLs.
2.5 Toxicity of Priority COCs
This section describes the toxicity of each Priority COC. The toxicity of a Priority COC
varies depending on the receptor and the route of exposure (i.e., inhalation, ingestion, or dermal),
as well as information from toxicity and/or epidemiology studies. The descriptions below,
19
-------
9/23/2016
therefore, present the toxicity information for likely receptors and exposure pathways and
exposure routes.
The human health toxicity descriptions below are from ATSDR's ToxFAQs (ATSDR,
2011) and the EPA's Integrated Risk Information System (IRIS) database (U.S. EPA, 201 lb)
during the period of this analysis (i.e., 2009 - 2012). The ecological toxicity descriptions are
from the EPA's ECOTOX database (U.S. EPA, 201 lc) and National Oceanic and Atmospheric
Administration's (NOAA) Screening Quick Reference Tables (NOAA, 2008). EPA identified
general classes of sensitive receptors from a literature search of EPA's ECOTOX database.
Because ecological toxicity studies have been conducted only on a limited number of species, in
general, EPA presents the toxicity for aquatic organisms (sediment and surface water biota).
Antimony
Antimony is a silvery white metal found in small quantities in the earth's crust. Antimony
ores are mined and then either processed into antimony metal or combined with oxygen to form
antimony oxide. Antimony enters the environment during the mining and processing of its ores
and in the production of antimony metal, alloys, antimony oxide, and the combination of
antimony with other substances.
Human Health Toxicity: The primary exposure route of concern for antimony is
ingestion of contaminated media. The non-cancer endpoint for ingestion of antimony is
hematological effects. Available studies indicate chronic ingestion of antimony may result in
altered blood glucose and cholesterol levels. EPA has not classified the carcinogenicity of
antimony. (U.S. EPA, 2011b; ATSDR, 2011)
Ecological Toxicity: Based on available toxicological data, screening benchmarks have
been developed for terrestrial, aquatic, and sediment receptors. Mammals are the most sensitive
terrestrial receptors to antimony exposure. Sediment and surface water biota are sensitive aquatic
receptors to antimony exposure. Antimony is not known to bioaccumulate in animals. (U.S. EPA
2011c; NOAA, 2008)
Arsenic
The main use of metallic arsenic is for strengthening alloys of copper and lead.
Human Health Toxicity: The main exposure routes of concern for arsenic are ingestion
and inhalation of contaminated media. The main non-cancer endpoints for ingestion of arsenic
are cardiovascular and dermal effects. Exposure to lower levels can cause nausea and vomiting,
decreased production of red and white blood cells, abnormal heart rhythm, damage to blood
vessels, and a sensation of "pins and needles" in hands and feet. Ingesting or breathing low levels
of inorganic arsenic for a long time can cause a darkening of the skin and the appearance of
small "corns" or "warts" on the palms, soles, and torso. Skin contact with inorganic arsenic may
cause redness and swelling. (U.S. EPA, 2011b; ATSDR, 2011)
EPA classifies arsenic as a known human carcinogen through ingestion and inhalation.
Ingestion of inorganic arsenic can increase the risk of skin cancer and cancer in the liver,
bladder, and lungs. Inhalation of inorganic arsenic can cause increased risk of lung cancer. (U.S.
EPA, 2011c)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to arsenic exposure in soil. Invertebrates are the most sensitive aquatic
20
-------
9/23/2016
receptors to arsenic exposure. Arsenic is known to bioaccumulate in animals. (U.S. EPA 201 lc;
NO A A, 2008)
Beryllium
Human Health Toxicity: The primary exposure routes identified for beryllium are
ingestion or inhalation of contaminated media. The associated non-cancer endpoints are
gastrointestinal and pulmonary effects, respectively. Ingestion of beryllium may result in ulcers.
Inhalation of high concentrations of beryllium may result in acute beryllium disease, resembling
pneumonia. Exposure at lower concentrations may result in heightened sensitivity to beryllium
and inflammation of the respiratory tract, weakness, and difficulty breathing. (U.S. EPA, 201 lb;
AT SDR, 2011)
Beryllium is classified as a probable human carcinogen. The primary cancer exposure
route identified for beryllium is inhalation of contaminated media, causing lung cancer. (U.S.
EPA, 2011b)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to beryllium exposure in soil. Invertebrates are the most sensitive aquatic
receptors to beryllium exposure. Beryllium is not known to bioaccumulate in animals. (U.S. EPA
2011c; NO A A, 2008)
Cadmium
Human Health Toxicity: Cadmium's primary exposure route is ingestion of
contaminated media, leading to renal effects. Available studies indicate chronic ingestion of
cadmium may result in proteinuria, the excretion of essential proteins in urine that would
otherwise be retained by the body, and kidney disease. (U.S. EPA, 201 lb; ATSDR, 2011)
Cadmium is classified as a probable human carcinogen. The primary exposure route of
concern for cadmium is inhalation of contaminated media, leading to lung cancer. (U.S. EPA,
2011b)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to cadmium exposure in soil. Invertebrates and fish are the most sensitive
aquatic receptors to cadmium exposure. Cadmium is known to bioaccumulate in animals. (U.S.
EPA 201 lc; NO A A, 2008)
Chromium
Human Health Toxicity: The primary exposure routes for chromium are ingestion and
inhalation of contaminated media. The associated non-cancer endpoints are gastrointestinal and
pulmonary effects, respectively. Available studies indicate chronic ingestion of chromium may
result in irritation and ulcers in the stomach and small intestine, while inhalation may result in
irritation to the lining of the nose, nose ulcers, and breathing problems such as asthma. (U.S.
EPA, 201 lb; ATSDR, 2011)
When chromium is in the hexavalent oxidation state, EPA classifies it as a known human
carcinogen. The primary exposure routes of concern for hexavalent chromium are ingestion and
inhalation of contaminated media, leading to gastrointestinal and pulmonary cancers,
respectively. (U.S. EPA, 2011b)
21
-------
9/23/2016
Ecological Toxicity: Based on available data, invertebrates are the most sensitive
terrestrial ecological receptors to chromium exposure in soil. Invertebrates are also the most
sensitive aquatic receptors to chromium exposure. Chromium is known to bioaccumulate in
animals. (U.S. EPA 201 lc; NO A A, 2008)
Copper
Human Health Toxicity . The primary exposure route for copper is ingestion of
contaminated media. The associated non-cancer endpoint is gastrointestinal effects. Available
studies indicate chronic ingestion of copper may result in gastrointestinal disturbances, such as
nausea and diarrhea. (U.S. EPA, 201 lb; ATSDR, 2011)
EPA has not classified the carcinogenicity of copper. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to copper exposure. Invertebrates are the most sensitive aquatic receptors to
copper exposure. Copper is known to bioaccumulate in animals. (U.S. EPA 201 lc; NOAA,
2008)
Fluorine
Human Health Toxicity: The primary exposure route for fluorine is ingestion of
contaminated media. The associated non-cancer endpoint is hematological effects. Available
studies indicate chronic ingestion of fluorine may result in decreased count for red blood cells,
packed cell volume, and hemoglobin. (U.S. EPA, 2011b; ATSDR, 2011)
EPA has not classified the carcinogenicity of fluorine. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, microbes are the most sensitive terrestrial
ecological receptors to fluorine exposure. Invertebrates are the most sensitive aquatic receptors
to fluorine exposure. Fluorine is not known to bioaccumulate in animals. (U.S. EPA 201 lc;
NOAA, 2008)
Lead
Human Health Toxicity . The primary exposure routes for lead are ingestion of and
inhalation of contaminated media. The associated non-cancer endpoint for both exposure
pathways is neurological effects. Available studies indicate chronic exposure to lead may result
in changes to neurobehavioral development in children or brain damage. (U.S. EPA, 201 lb;
ATSDR, 2011)
EPA classifies lead as a potential human carcinogen. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to lead exposure. Amphibians are the most sensitive aquatic receptors to
lead exposure. Lead is known to bioaccumulate in animals. (U.S. EPA 201 lc; NOAA, 2008)
Manganese
Human Health Toxicity: The primary exposure routes for manganese are ingestion of
and inhalation of contaminated media. The associated non-cancer endpoint for both exposure
pathways is neurological. Available studies indicate chronic exposure to manganese may result
in weakness and fatigue, gait disturbances, tremors, dystonia, or impairment of neurobehavioral
function. (U.S. EPA, 2011b; ATSDR, 2011)
22
-------
9/23/2016
EPA has not classified the carcinogenicity of manganese. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, invertebrates are the most sensitive
terrestrial ecological receptors to manganese exposure. Fish are the most sensitive aquatic
receptors to manganese exposure. Manganese is not known to bioaccumulate in animals. (U.S.
EPA 201 lc; NO A A, 2008)
Mercury
Human Health Toxicity: The primary exposure route for mercury is ingestion of
contaminated media. The associated non-cancer endpoint is neurological effects. Available
studies indicate chronic exposure to mercury may result in hand tremor, increases in memory
disturbances, autonomic dysfunction, and developmental neurotoxicity. (U.S. EPA, 2011b;
ATSDR, 2011)
EPA has not classified the carcinogenicity of mercury. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to mercury exposure. Invertebrates and fish are the most sensitive aquatic
receptors to mercury exposure. Mercury is known to bioaccumulate in animals. (U.S. EPA
2011c; NO A A, 2008)
Nickel
Human Health Toxicity . The primary exposure routes for nickel are ingestion and
inhalation of contaminated media. The associated non-cancer endpoints are body weight and
pulmonary effects, respectively. Available studies indicate chronic ingestion of nickel may result
in decreased weight of the body and select organs, while chronic inhalation may result in
bronchitis and reduced lung function. (U.S. EPA, 201 lb; ATSDR, 2011)
EPA has not classified the carcinogenicity of nickel. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to nickel exposure. Fish are the most sensitive aquatic receptors to nickel
exposure (Nanda et al., 2000). Nickel is known to bioaccumulate in animals. (U.S. EPA 201 lc;
NO A A, 2008)
Polvcvclic Aromatic Hydrocarbons (PAHs)
PAHs are a class of structurally similar chemical compounds characterized by the
presence of fused aromatic rings. PAHs are typically formed during the incomplete burning of
organic material including coal, oil, gasoline, and garbage. Benzo[a]pyrene,
benzo[b]fluoranthene, benz[a]anthracene, and dibenz[a,h]anthracene were the individual PAHs
identified as Priority COCs. (U.S. EPA, 201 lb; ATSDR, 2011)
Human Health Toxicity. EPA classifies some individual PAHs as probable human
carcinogens. All PAHs identified as Priority COCs are classified as probable carcinogens. The
primary exposure routes for PAHs are ingestion and inhalation of contaminated media, with
associated endpoints of gastrointestinal and pulmonary cancers, respectively. (U.S. EPA, 2011b)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to PAH exposure. Invertebrates are the most sensitive aquatic receptors to
PAH exposure. PAHs are known to bioaccumulate in animals. (U.S. EPA 201 lc; NOAA, 2008)
23
-------
9/23/2016
Polvchlorinated Biphenyls (PCBs)
PCBs are a class of organic compounds with 2 to 10 chlorine atoms attached to a
biphenyl molecule composed of two benzene rings. Each type of PCB with a given number of
chlorine atoms and a given structure is known as a congener, and each congener is usually
identified with the word "Aroclor" and a number. PCB production was banned by the U.S.
Congress in 1979.
Human Health Toxicity . Non-cancer health data are available for select PCB congeners.
The primary exposure route for Aroclor-1016 is ingestion of contaminated media, resulting in
reproductive effects. Available studies indicate chronic ingestion of Aroclor-1016 may result in
reduced birth weight and neurological impairment of infants. The primary exposure pathway for
Aroclor-1254 is ingestion of contaminated media, which is associated with ocular, hair, and
immunological effects. Available studies indicate chronic ingestion of Aroclor-1254 may result
in inflammation of the eyes, distorted nails, and reduced antibody function. (U.S. EPA, 201 lb;
AT SDR, 2011)
EPA classifies all PCBs as probable human carcinogens. The primary exposure pathways
of concern for PCBs are ingestion and inhalation of contaminated media, which are associated
with liver cancer. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to PCB exposure. Fish are the most sensitive aquatic receptors to PCB
exposure. PCBs are known to bioaccumulate in animals. (U.S. EPA 201 lc; NOAA, 2008)
Radionuclides
Radionuclides are any atoms with unstable nuclei that will eventually decay toward a
more stable configuration by releasing excess energy to the surrounding environment in the form
of radiation. Naturally occurring radionuclides are ubiquitous in nature but can be concentrated
during mining and processing activities. The individual radionuclides identified as Priority COCs
at Case Study Historical sites were radium-226, radon-222, lead-210, uranium-238, and thorium-
228.
Human Health Toxicity . Radionuclides are chemically identical to their stable
counterparts. Therefore, they share the same toxicological endpoints and health effects.
EPA classifies all radionuclides as known human carcinogens. The primary exposure
routes of concern for radionuclides are ingestion and inhalation of contaminated media, as well
as external exposure to radiation. The associated cancer endpoints vary by radionuclide and
exposure route; however, exposure of any organ system to elevated levels of radiation increases
the likelihood of cancer. (U.S. EPA, 201 lb)
Ecological Toxicity: Little information is available to establish a dose-response
relationship between ecological receptors and radionuclide exposure. (U.S. EPA 2011c)
Selenium
Human Health Toxicity . The primary exposure routes for selenium are ingestion and
inhalation of contaminated media, which are associated with dermal, neurological, hepatic and
pulmonary effects, respectively. Available studies indicate chronic ingestion of selenium may
result in clinical selenosis, resulting in hair loss, sloughing of nails, fatigue, irritability, and
neurological damage. Extreme cases of selenosis can result in cirrhosis of the liver, pulmonary
24
-------
9/23/2016
edema, and death. Chronic inhalation of selenium may result in respiratory irritation, bronchial
spasms, and coughing. (U.S. EPA, 2011b; ATSDR, 2011)
EPA has not classified the carcinogenicity of selenium. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, plants and birds are the most sensitive
terrestrial ecological receptors to selenium exposure. Egg laying vertebrates (i.e., fish) are the
most sensitive aquatic receptors to selenium exposure. Selenium is known to bioaccumulate in
animals. (U.S. EPA 201 lc; NO A A, 2008)
Silver
Human Health Toxicity . The primary exposure route for silver is ingestion of
contaminated media, which is associated with dermal effects. Available studies indicate chronic
ingestion of silver may result in argyra, a permanent blue-gray discoloration of the skin and other
body tissues. (U.S. EPA, 2011b; ATSDR, 2011)
EPA has not classified the carcinogenicity of silver. (U.S. EPA, 201 lc)
Ecological Toxicity: Based on available data, plants are the most sensitive terrestrial
ecological receptors to silver exposure. Invertebrates are the most sensitive aquatic receptors to
silver exposure. Silver is known to bioaccumulate in animals. (U.S. EPA 201 lc; NOAA, 2008)
Thallium
Human Health Toxicity . The primary exposure route for thallium is ingestion of
contaminated media. The associated non-cancer endpoints are dermal, neurological, and
reproductive effects. Available studies indicate chronic ingestion of thallium may result in hair
loss, as well as damage to the nervous and reproductive systems. (U.S. EPA, 201 lb; ATSDR,
2011)
EPA has not classified the carcinogenicity of thallium. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available data, mammals are the most sensitive terrestrial
ecological receptors to thallium exposure. Invertebrates are the most sensitive aquatic receptors
to thallium exposure. Thallium is not known to bioaccumulate in animals. (U.S. EPA 201 lc;
NOAA, 2008)
Zinc
Human Health Toxicity . The primary exposure route for zinc is ingestion of
contaminated media. The associated non-cancer endpoints are dermal, neurological, and
reproductive effects. Available studies indicate chronic ingestion of zinc may result in hair loss,
damage to the nervous and reproductive systems, and decreases in erythrocyte Cu, Zn-
superoxide dismutase (ESOD) activity in healthy adults. (U.S. EPA, 201 lb; ATSDR, 2011)
EPA has not classified the carcinogenicity of zinc. (U.S. EPA, 201 lb)
Ecological Toxicity: Based on available literature, invertebrates are the most sensitive
terrestrial ecological receptors to zinc exposure. Invertebrates and fish are the most sensitive
aquatic receptors to zinc exposure. Zinc is known to bioaccumulate in animals. (U.S. EPA
2011c; NOAA, 2008)
In summary, each of the Priority COCs has certain toxic effects on either humans,
ecological receptors, or both.
25
-------
9/23/2016
3.0 Exposure Analysis
Superfund exposure assessments estimate the magnitude of current and possible future
human and ecological exposures, the frequency and duration of these exposures, and the
pathways by which receptors are potentially exposed. Reasonable maximum exposures are
developed for past, present, and possible future exposures to CERCLA hazardous substances.
The Superfund exposure assessment process includes the following tasks:
Characterizing exposure setting, including the receptors that may be impacted by the
CERCLA hazardous substances being evaluated;
Identifying exposure pathways and the specific routes by which the receptors may come
into contact with the CERCLA hazardous substances; and
Quantifying exposure.
When evaluating potential human health risk, The EPA's Risk Assessment Guidance for
Superfund, or RAGS, Part A, directs that the exposure assessment consider both current and
future land uses and corresponding exposures (U.S. EPA, 1989a, page 6-4). Guidance for
evaluating ecological risks at Superfund sites suggests that a qualitative and, if data allow,
quantitative appraisal of the actual or potential impacts of contaminants from a hazardous waste
site on plants and animals be performed (U.S. EPA, 1997). Additionally, ecological assessments
should consider exposure to especially sensitive habitats and critical habitats of federally
classified threatened or endangered species.
Some concepts related to exposure assessments are described here. Please refer to EPA's
RAGS, Part A (U.S. EPA, 1989a) for further explanation of exposure analysis in the Superfund
program.
A stressor is "any physical, chemical, or biological entity that can induce an adverse
response. Stressors may adversely affect specific natural resources or entire ecosystems,
including plants and animals, as well as the environment with which they interact" (U.S.
EPA, 201 la). In the context of the Superfund clean ups described in this report, stressors
are limited to CERCLA hazardous substances.
A receptor is an organism exposed to the stressor. Examples of human receptors are
occupational workers, current and future residential adults and children, and trespassers.
Examples of ecological receptors include birds, mammals, fish, benthic invertebrates, and
plants.
Environmental fate and transport evaluates how contaminants might move through or
be transformed physically, chemically, and biologically in the environment; how
contaminants are taken up by plants and animals; and how they are transferred among
plants and animals (i.e., through animals eating plants or other animals) (U.S. EPA,
1997).
EPA has defined an exposure pathway as "[t]he course a chemical or physical agent
takes from a [contamination] source to an exposed organism. An exposure pathway
describes a unique mechanism by which an individual or population is exposed to
chemicals or physical agents at or originating from a site. Each exposure pathway
includes a source or release from a source, an exposure point, and an exposure route. If
the exposure point differs from the source, a transport/exposure medium (e.g., air) or
media (in cases of intermedia transfer) also is included" (U.S. EPA, 1989a, p. 6-2).
26
-------
9/23/2016
EPA has defined exposure route as "[t]he way a chemical or physical agent comes in
contact with an organism (e.g., by ingestion, inhalation, dermal contact)" (U.S. EPA,
1989a, p. 6-2). Exposure occurs when there are complete pathways between a chemical
or physical agent and receptors.
3.1 Conceptual Site Models for Superfund Human Health and
Ecological Risk Assessments
The purpose of a conceptual site model (CSM) is to identify potential receptors, exposure
pathways, and exposure routes based on the potential release, transport, and fate of CERCLA
hazardous substances (contaminants of potential concern) at a mine or processor site. The CSM
describes specific contaminant sources, contaminant release mechanisms, pathways for
contaminant transport, and the resulting potential for human and ecological exposure.
The example CSM provided in Figure 3-1, adapted from a CSM prepared for a mining
NPL site in Nevada, shows a mining and ore processing site of nonspecific location, climate, and
physical setting. Although this model may not capture every possible combination of receptor
and pathway that could occur at a site (e.g., recreational users of surface waters are excluded), it
is generally consistent with what was seen at the Case Study Historical sites. Thus, it is likely to
be generally consistent with the exposure pathways that can be expected at the 2009 Current sites
that are the surrogate for the current and future population of sites. The current and future
receptors and their corresponding exposure pathways depicted in Figure 3-1 are summarized
below. More detailed information about the CSM can be found in Appendix K.
Future Construction Worker: This represents an adult who would likely be exposed to
on-site contamination at a point in the future when the land is being redeveloped. The
future construction worker could potentially be exposed to contamination through the
following pathways:
- Surface water, via ingestion or direct contact
- Sediment, via ingestion or direct contact
- Particulates and vapors in the air, via inhalation
- Soil, via ingestion or direct contact
- External radiation.
Current and Future Outdoor Worker: This represents an adult who is either currently
working on site and in direct contact with environmental media (e.g., a guard or a
remediation worker) or a future adult working on site and in direct contact with
environmental media (e.g., landscaper, gardener, guard). This person could potentially be
exposed to contamination through the following pathways:
- Tailings, via ingestion or direct contact
- Surface water, via ingestion or direct contact
- Sediment, via ingestion or direct contact
- Particulates and vapors in the air, via inhalation
- Ground water, via ingestion or direct contact
- Soil, via ingestion or direct contact
- External radiation.
27
-------
9/23/2016
CURRENT AND FUTURE OUTDOOR
WORKER
FUTURE CONSTRUCTION WORKER
ON-SITE RESIDENT'
OFF-SITE RESIDENT
TRADITIONAL TRIBAL LIFEWAYS
INGESTION OF,
CONTACT
WITH TAILINGS
COWTACT WITH
GROUNDWATER.
SURFACE WATER
INHALATION Of
PARTICULATES AND
VAPORS
INGESTION
OF. CONTACT
WITH SEDIMENT
INGESTION
OF. CONTACT
WITH SEDIMENT
PUMPBACK WELLS
(GROUNDWATER
EXTRACTION)
NEARBY
RESIDENCES
FUTURE INDOOR WORKER
GROUNDWATER
DISCHARGE
SEWAGE -
TREATMENT
PONDS
EVAPORATION y -fl
PONDS i
W PUMPBACK
AND PON06 '
DEPOSITION EVAPORATION POND WIND EROSION
" AND ,
DEPOSITION/
EVAPORATION
PONDS
v. HEAPLEACH
"Al LINGS
WIND EROSION
AND
DEPOSITION
WASTE ROCK AREAS
MGESTON OF WILD GAME
PI T LAKE WATERFOWL AND FISH
J |C EXTERNAL . / 1
- - .aT 4 W
WT PERCOLATION * INHALATION OF
-------
9/23/2016
Traditional Tribal Lifeways: This represents a person who is partially or fully living a
traditional tribal lifestyle that involves hunting wild game and/or collecting wild
plants/berries for sustenance. This person would likely be spending time outdoors and
could potentially be exposed to contamination through the following pathways:
- Particulates in the air, via inhalation
- Wild game and waterfowl, via ingestion
- Fish, or shellfish , via ingestion
- Contact with native plants, via ingestion, cultural uses, and/or inhalation of smoke.
On-Site Resident: This represents current and future adults and children who live on
site. Except for temporary on-site living facilities for workers at more remote mines, the
probability of residents living on site is low; however, if this does occur, the potential
exposures are high. These residents could potentially be exposed to contamination
through the following pathways:
- Ground water, via ingestion or direct contact
- Surface water, via ingestion or direct contact
- Livestock and wild game, via ingestion
- Produce, via ingestion
- Particulates and vapors in the air, via inhalation
- Soil, via ingestion or direct contact
- Tailings, via ingestion or direct contact
- Sediment, via ingestion or direct contact
- Indoor dust, via ingestion or direct contact
- External radiation.
Off-Site Resident: This represents current and future adults and children who live off
site but within the buffer zone of potential exposures (i.e., 3 miles). Exposures will vary
depending on several factors (e.g., whether the residential area is down-gradient or up-
gradient from the site). These residents could potentially be exposed to contamination
through the following pathways:
- Indoor dust, via ingestion or direct contact
- Ground water, via ingestion or direct contact
- Livestock and wild game, via ingestion
- Product, via ingestion
- Particulates, via inhalation
- Soil, via ingestion or direct contact.
Future Indoor Worker: This represents a person who would be working indoors, on
site, at a point in the future after the land has been redeveloped (e.g., a librarian). It is
unlikely that this person would come into direct contact with the land because the
assumption is that the ground where they walk is paved (i.e., parking lot, sidewalks).
However, this person could potentially be exposed to contamination through the
following pathways:
- Particulates and vapors in the air, via inhalation
- Ground water, via ingestion or direct contact
- Soil and dust, via ingestion or direct contact
29
-------
9/23/2016
- External radiation.
Trespasser/Hunter: This represents a current or future adult or adolescent who is
exposed to environmental media on site, even though the site may be fenced, guarded, or
otherwise prohibited from public access. This person could potentially be exposed to
contamination through the following pathways:
- Tailings, via ingestion or direct contact
- Soil, via ingestion or direct contact
- Native plants, via ingestion
- Sediment, via ingestion or direct contact
- Surface water, via ingestion or direct contact
- Wild game, waterfowl, and fish, via ingestion
- Particulates and vapors, via inhalation
- External radiation.
The collected data indicate that mineral processing operations that do not occur at or near
mining sites frequently take place in a more urban or densely populated setting. A CSM for a
mineral processing operation in an urban setting would show site features, sources for hazardous
substance releases, receptors, and likely transport pathways from source to receptor. Mineral
processing that takes place within enclosed buildings may present a different (lower) potential
for hazardous substance transport than mining operations taking place outdoors. Outdoor waste
management practices could occur at both mine and processor sites.
Based on a review of Superfund risk assessments and other CERCLA site documents,
EPA compiled a list of contaminant sources, affected environmental media, human exposure
routes, and human and ecological receptors at Case Study Historical sites. Figure 3-2 is a
detailed chart displaying the contaminant sources, affected environmental media, human
exposure routes, and human receptors for the Case Study Historical sites. Figure 3-3 shows the
same information for ecological receptors.
30
-------
9/23/2016
CONTAMINANT RELEASE
NPL Sites
CONTAMINANT TRANSPORT
CONTAMINANT FATE
SOURCES
Acid Mine/Rock
Potliners
Drainage
Pressing Ponds
Asbestos Fibers
Process Fluids
Cryolite Disposal
Process Stacks Emissions
Demolition Dumps
Quartzite Dust Slurry
Deposition
Radioactive Waste Piles
Dredged Sediments
Run-off
Flue Dust
Sewage Sludge
Fugitive Dust
Slag Piles
Housekeeping Debris
Smelter Emissions
Incinerator Ash
Storage Tanks
Iron-rich Liquid Acid
Sulfate Residuals
Non-Contact Cooling
Waste Tailings
Water Effluent
Transformers
Ore Slimes
Treater Dust Stock Piles
Ore/Nodule Stockpiles
Underflow Solids Piles
Ore Waste
Unlined Pits
Overburden
Waste Drums
Waste Piles
Waste Rock
MEDIA
Air
Groundwater
Sediment
Soil
Surface Water
Vadose Zone
ROUTE
Dermal Contact
External Radiation
Ingestion of
Food-Plants
Food-Birds
Food-Mammals
Food-Terrestrial
Food-Benthic
Food-Fish
Food-Aquatic Plants
Food-Aquatic
Inhalation
Combined Routes
RECEPTORS
Occupational (Agricultural)
Occupational (Construction)-Current
Occupational (Construction)-Future
Occupational (Dredging)-Future
Occupational (Industrial)-Current
Occupational (Industrial)-Future
Occupational(Not Specified)-Current
Occupational(Not Specified)-Future
Recreational-Current
Recreational-Hiker
Residential-Current
Residential-Future
Site Visitor
Trespasser-Current
Trespasser-Future
Figure 3-2. Contaminant sources, exposure pathways, exposure routes, and human receptors at Case Study Historical sites.
31
-------
9/23/2016
CONTAMINANT RELEASE
EXPOSURE PATHWAYS
WILDLIFE SPECIES
SOURCES
Airborne Emissions
Potliners
ARD
Process Residues
Calcium Silicate
Process Stacks
Slag Piles
Air Emissions
Coke Dust Slurry
Quartzite Dust
Coke Stockpiles
Slurry
Cryolite Disposal
Run-off
Debris
Slag
Exposed Mineralized
Slag Piles
Bedrock
Sludge
Fuel/Oil
Spent Mineral
Fugitive Dust
Waste
Leachate
Spent Ore
Manual/Aerial
Tailings
Deposition
Treater Dust
Municipal Waste
Stock Piles
Nodule Stockpiles
Underflow Solids
Non-Contact Cooling
Piles
Water Effluent
Waste Drums
Ore Stockpiles
Waste Piles
Overburden
Waste Rock
Phossy Water
Wastewater
EXPOSURE PATHWAYS
Groundwater
Sediment
Soil
Subsurface Soil
Surface Soil
Surface water
Water
COMPARTMENTS
Aquatic Invertebrates
Aquatic Plants
Benthic Invertebrates
Birds
Fish
Mammals
Plants
Terrestrial Invertebrates
Terrestrial Plants
Plants
Soil Invertebrates
ROUTES
Dermal Contact
Ingestion
Inhalation
Combined Routes
" Receptors are considered current unless otherwise stated.
Birds
American Dipper
Mallard
American Kestrel
Mountain Chickadee
American Robbin
Northern Harrier
Bam Owl
Omnivorous Birds
Belted Kingfisher
Pine Grosbeak
Bobwhite Quail
Red-tailed Hawk
Carnivorous Birds
Sage Grouse
Cliff Swallow
song sparrow
Great blue heron
spotted sandpiper
Horned Lark
Waterfowl
King Fisher
Woodcock
Mammals
Carnivorous Mammals
Mink
Coyote
Montane Vole
Deer
Omnivorous Mammals
Deer Mouse
Piscivorous Mammals
Field Mice
Rabbits
Herbivorous Mammals
Raccoon
Long-tailed Weasel
Red Fox
Masked Shrew
Small mammals
Meadow Vole
Soil Invertebrate-
feeding Mammals
White-tailed Deer
Other-Terrestrial
Other-Aquatic
Benthic Invertebrates
Sagebrush
Benthic macroinvertebrates
Soil invertebrates
Benthic Organisms
Terrestrial Invertebrates
Deepwater Habitats
Terrestrial Organisms
Fish
Terrestrial Plant
Future-Aquatic Organisms
Community
Future-Wetland Invertebrates
Terrestrial Soil
Periphyton Community
Community
Predatory Fish
Thickspike Wheatgrass
Rainbow Trout
Other-Generic
Amphibians
Future-Wildlife
Plants
Herbivores
Vegetation
Figure 3-3. Contaminant sources, exposure pathways, exposure routes, and ecological receptors at Case Study Historical sites.
32
-------
9/23/2016
3.2 Receptors
3.2.1 Case Study Historical Sites: Human Receptors
Superfund risk assessments of Case Study Historical sites included a wide range of
human habitation settings, from very sparsely populated sites to densely populated urban metal
smelting sites, and also included one Indian reservation. The most common human receptor to be
exposed to CERCLA hazardous substances at levels of concern (i.e., >lE-06 cancer risk or >1.0
hazard quotient/hazard index, discussed further in Section 4.0) at the Case Study Historical sites
is the residential receptor (22 sites), followed by occupational receptors (18 sites). Of the highest
hazard quotients (i.e., HQs > 100) for human receptors, 9 of 11 (or 82%) are attributed to
residential receptors; of the highest cancer risk values (i.e., >lE-02) for human receptors, 18 of
25 (72%) are attributed to residential receptors.
3.2.2 Case Study Historical Sites: Ecological Receptors
Superfund risk assessments of the Case Study Historical sites also evaluated a range of
ecological receptor habitat settings, including aquatic habitats, especially streams near mines, as
well as habitat for terrestrial and avian receptors, including some federally designated threatened
and endangered species. Ecological receptors at the Case Study Historical sites included species
identified as federally designated threatened or endangered species at the time the site was
investigated, as well as state-designated threatened or endangered and federal or state-designated
species of concern. The federally designated threatened/endangered species identified at the Case
Study Historical sites included mammals, birds, aquatic organisms, plants, invertebrates, fish,
amphibians, and one reptile species, in descending order of frequency. Appendix H,
Attachment HI shows the federally listed threatened/endangered species mentioned in the
CERCLA site documents for the Case Study Historical sites, and the species' status listed in the
table reflects what their status was at the time the CERCLA site documents were prepared. The
Superfund ecological risk assessments of the Case Study Historical sites also evaluated species
that are not specifically identified as federally designated threatened or endangered species. In
several cases the ecological risk assessments identified major groupings of ecological receptors,
for example, benthic invertebrates (e.g., crayfish or mussels) or omnivorous birds, rather than
individual species.
3.2.3 2009 Current Sites: Documented Human Receptors
Human and ecological exposure analyses have been conducted at a very limited number
of the 2009 Current sites. For example, a lead smelter in Herculaneum, Missouri, has undergone
a public health exposure investigation by ATSDR and the state of Missouri (ATSDR, 2005); a
copper smelter in Arizona has undergone a public health assessment that included an exposure
evaluation (ATSDR, 2002); a phosphate mining area has undergone a risk assessment that
included an exposure analysis (NewFields, 2005); a licensed uranium processing site has
undergone a Superfund risk assessment (U.S. EPA, 2002); and a currently operating manganese
processing site has undergone an exposure assessment (ATSDR, 2009). At these sites, known
human receptors have been identified. For example, the lead smelter's and copper smelter's
receptors of concern are residents living in the vicinity of those two smelters, including pregnant
women and children, while the phosphate mining area's receptors are Native American children
33
-------
9/23/2016
and children living a subsistence lifestyle. Appendix A provides more details on the exposure
analyses that EPA located for the 2009 Current sites.
Residents within the 3-mile buffer zone of a site or other, varying buffer distances
depending on the hazardous substances being evaluated, could be exposed to contamination via
several pathways. These pathways include ingestion of ground water, surface water, soil,
sediment, and dust; dermal contact with ground water, surface water, soil, sediment, and dust;
inhalation of particulates; and ingestion of animals and produce. Pregnant women and children
may be more vulnerable to the harmful effects that can occur as a result of exposure to
contaminated media, and are therefore given special consideration when determining their
exposure potential.
3.2.4 2009 Current Sites: Potential Human Receptors
Information on the presence of human receptors was gathered for most of the 2009
Current sites, from a spatial dataset that EPA developed as part of this analysis. See Appendix E
for the GIS methodology and documentation and Appendix L for detailed GIS data.
For potential human receptors, EPA developed an area-apportionment method to analyze
the 2009 Current sites using 2000 Census population data to estimate the human residential
populations within several specified distances from each site. EPA created buffer zones of
selected distances around each site and then overlaid each buffer zone with census block group
boundaries to estimate total population. The numbers of sites with different populations of
potential human receptors living within 3 miles of each site are shown in Figure 3-4. EPA chose
the 3-mile distance for this analysis because a few mines are as large as 1 to 2 miles or more
across (e.g., a molybdenum mine in New Mexico; an iron ore mine and processor in Minnesota),
and humans typically would not be living inside or next to a mine pit or directly on top of
disturbed land while the mine is active. As shown in Figure 3-4, of the 2009 Current sites with
verifiable locations (i.e., 417 sites), 227 sites (i.e., 54%) have fewer than 1,000 people living
within 3 miles.
Examples of sites with estimated populations within 3 miles are presented below. These
are intended to show the range of population densities that occur within a 3-mile radius of
currently active mines or processors in the United States. In general, the denser the population
surrounding a site, the higher the potential for human exposure to and subsequent health impacts
from contamination from that site. However, each site will have a site-specific potential to
expose the surrounding population, depending on various factors such as site activities (release
rates, types of CERCLA hazardous substances present), the number of people living down-
gradient vs. up-gradient from the site, and the lifestyle of those exposed (e.g., subsistence
farming vs. urban setting).
34
-------
9/23/2016
250
200
V)
50,000*
Number of Individuals
* Maximum number reported is 214,215
Figure 3-4. Number of 2009 Current sites, by estimated population within 3 miles.
In sparsely populated areas (fewer than 1,000 people within 3 miles):
- an active gold mine in Humboldt County, Nevada, 6 people
- an intermittently active wollastonite mine in Essex County, New York, 395 people
- an intermittently active rare earth ore mine and processor in San Bernardino County,
California, 7 people
In moderately populated areas (1,000 - 50,000 people within 3 miles):
- an iron and steel slag processor in Butler County, Ohio, 31,923 people
- a silicomanganese producer in Mason County, West Virginia, 26,548 people
- a tungsten processor in Madison County, Alabama, 18,548 people
In densely populated areas (more than 50,000 people within 3 miles):
- a vermiculite processor in Maricopa County, Arizona, 210,332 people
- an iron and steel slag processor in Cuyahoga County, Ohio, 140,164 people
- a vermiculite processor in Middlesex County, New Jersey, 95,550 people
3.2.5 2009 Current Sites: Documented Ecological Receptors
Information on known ecological receptors was available for only a limited number of
the 2009 Current sites. For example, studies are performed as part of the National Environmental
Policy Act (NEPA) process at mines or mineral processors located on federal lands, and these
studies sometimes identify the presence of threatened or endangered species or other ecological
receptors (e.g., Kanouse, 2011). At sites regulated under Resource Conservation and Recovery
Act (RCRA) hazardous waste regulations, or the state's equivalent requirements, site owners or
operators are sometimes required to perform ecological risk assessments as part of their permit
requirements (e.g., Oklahoma DEQ, 2008). The risk assessment of one phosphate mine evaluated
35
-------
9/23/2016
livestock, wildlife, fish, and aquatic invertebrates (NewFields, 2005). At a copper mine,
ecological receptors included specific birds, mammals, and reptiles (Golder and Associates Inc.,
2005).
3.2.6 2009 Current Sites: Potential Ecological Receptors
EPA searched multiple data sources to identify the existence of critical habitat for
federally designated threatened and endangered species and the presence and proximity of
aquatic habitat inhabited by aquatic species. For federally designated threatened and endangered
species, 24 (i.e., 6%) of the estimated 417 sites with verifiable locations are located within 3
miles of federally designated "critical habitat" according to data that were current as of the
download date of May 5, 2010. At a distance of 3 miles, the federally designated threatened and
endangered species included certain birds, mammals, fish, reptiles, and amphibians. As the
distance from the sites increases, the number of sites near critical habitat increases; an estimated
22% (92 of 417 sites) of the 2009 Current sites are within 20 miles of critical habitat. Depending
on the species and the extent of the range that it uses for habitat and acquiring food, either a 3-
mile or a 20-mile distance (or more) may be relevant. Appendix H shows the species identified
in this analysis.
Perennial streams were detected within a 24-hour downstream travel distance from 371
(i.e., 94%) of the 395 sites in the contiguous United States with verifiable locations.6 These
streams would therefore receive precipitation runoff from these sites, unless an engineered
diversion has been constructed. Aquatic receptors could be expected to be present in many
surface water bodies with perennial flow. Even some streams with only intermittent flow support
aquatic life when flow is present. Eight percent of the 395 sites are located in such arid climates
that there is no perennial stream nearby.
An estimated 151 (i.e., 38%) of the 395 sites are estimated to be within a 24-hour
downstream travel distance of a dam that provides a beneficial use for fish and wildlife.
3.3 Exposure Pathways and Routes
Exposure pathways include the sequence of environmental media, such as air, water, soil,
or sediments, through which CERCLA hazardous substances move from the source to the
receptor. Exposure routes are the points of contact into the receptor organism (inhalation;
ingestion; direct contact with plant tissue, skin or exterior membranes). Figure 3-2 identifies
environmental media, exposure pathways, and exposure routes found in the Superfund human
health and ecological risk assessments performed at the Case Study Historical sites.
3.3.1 Case Study Historical Sites: Human Exposure Pathways and Routes
As noted above, the most common human receptors for the Case Study Historical sites
were residential and occupational. For both residential and occupational receptors at Case Study
Historical sites, the most common exposure medium was ground water (at 18 of 22 sites with
residential receptors and 8 of 14 sites with occupational receptors), followed by soil (at 9 of 22
sites with residential receptors and 5 of 14 sites with occupational receptors). The most common
6 As discussed in Section 2.1.3, the 2009 Current Sites universe includes 417 sites with verifiable locations. Some
analyses could not be run for sites in Alaska because of lack of data. The remaining 395 sites with verifiable
locations are all in the contiguous United States.
36
-------
9/23/2016
exposure route was ingestion (at 21 of 22 sites with residential receptors and all 14 sites with
occupational receptors), followed by inhalation (at 14 of 22 sites with residential receptors and 8
of 14 sites with occupational receptors). Note that all values are for CERCLA hazardous
substances found to be above a level of concern. Also, a single site could report more than one
medium or route; thus, the numbers sum to more than the total number of sites.
Examples of human exposure pathways and exposure routes evaluated for specific
CERCLA hazardous substances found to be of concern at the Case Study Historical sites include
the following:
Antimony in surface soil ingested by current and future residents (Colorado DPHE, 2008,
Table 8-54)
Uranium found in food plants ingested by people (U.S. EPA, 2005a, p. 97)
Thorium in creek sediment contacted by adolescent recreational users of the creek (U.S.
EPA, 2005b, Table 11).
The Superfund risk assessments of other Case Study Historical sites include similar
examples of human exposure pathways and exposure routes shown in Figure 3-2.
3.3.2 Case Study Historical Sites: Ecological Exposure Pathways and Routes
The most common exposure media for ecological receptors at Case Study Historical sites
were sediment and surface water (at 13 and 11 sites, respectively). The most common ecological
exposure routes were ingestion and dermal contact (at 9 and 8 sites, respectively). Again, all
counts are for CERCLA hazardous substances present above a level of concern.
Examples of ecological exposure pathways and exposure routes evaluated at the Case
Study Historical sites include the following:
Lead and zinc in food items ingested by terrestrial invertebrates and subsequently eaten
by birds (Colorado DPHE, 2008, p. 9-111);
Lead in soil, surface water, and food items ingested by robins (U.S. EPA, 2001, Table
65);
Selenium, aluminum, antimony, and arsenic in food items ingested by red fox (U.S. EPA,
1998, Appendix 7B-3).
The Superfund risk assessments of other Case Study Historical sites include similar
examples of exposure pathways and exposure routes for ecological receptors.
The species near the Case Study Historical sites that were classified as federally
endangered or threatened at the time of the source document include the following:
Endangered:
- Birds: Bald eagle, peregrine falcon, whooping crane
- Mammals: Gray wolf
- Reptiles: Bog turtle
Threatened:
- Birds: Bald eagle
- Fish: Bull trout
37
-------
9/23/2016
- Mammals: [Canada] lynx, grizzly bear
- Plants: Ute ladies'-tresses.
A table showing the full list of both federal- and state-designated threatened and
endangered species, by site, can be found in Appendix H, Attachment HI.
At the dozen Case Study Historical sites that also had final NRD settlements, most
involved natural resource injuries caused by contamination of surface water bodies. Migratory
birds, anadromous fish species and threatened/endangered species were affected.
3.3.3 2009 Current Sites: Documented Human Exposure Pathways and Routes
Examples of exposure pathways and exposure routes for specific CERCLA hazardous
substances found to be of concern in human health risk assessments of 2009 Current sites include
the following:
Selenium from a phosphate mining area, both soil ingestion and fish consumption, by
people following subsistence lifestyles (NewFields, 2005, page 10-1)
Radionuclides from a uranium processor, external radiation exposure to nearby residents
(U.S. EPA, 2002, page 7-4)
Arsenic, copper, and lead from a copper smelter, direct soil contact and air inhalation
exposures to residential soil and ambient air by residents (U.S. EPA, 2008).
These examples of exposure pathways and exposure routes are consistent with exposure
pathways and exposure routes shown in Figure 3-2 that were found at the Case Study Historical
sites.
3.3.4 2009 Current Sites: Potential Human Exposure Pathways and Routes
On-site workers can be exposed through incidental ingestion of contaminated soil, air
inhalation, drinking water ingestion, or external radiation exposure. Nearby residents may come
into contact with soil contaminated by mining or mineral processing activities; the probability
may increase in more densely populated areas relative to sparsely populated areas. Trespassers
and recreational users of less densely populated sites can have exposures such as incidental
ingestion of contaminated soils, surface water, or sediment or external radiation exposure from
their presence near radiation sources such as tailings disposal areas, where tailings have elevated
levels of radionuclides relative to the background soil and rock.
The GIS analysis (see Appendix E) illustrates the population densities near 2009 Current
sites and describes the potential for drinking water supplies to be affected by CERCLA
hazardous substance releases from 2009 Current sites. Drinking water source protection areas for
both surface and ground water supplies are located within a 24-hour downstream travel distance
of 324 (i.e., 82%) of the 395 sites within the contiguous United States with verifiable locations.
38
-------
9/23/2016
3.3.5 2009 Current Sites: Documented Ecological Exposure Pathways and
Routes
Examples of known ecological exposure pathways and exposure routes either evaluated
or disclosed at the 2009 Current sites include the following:
Direct contact of aquatic organisms to contaminated water from an Alaskan lead, silver,
and zinc mine on Forest Service land (habitat degradation monitoring described in
Kanouse, 2011)
Direct contact of aquatic organisms to selenium in surface water bodies down-gradient
from a phosphate mining area (NewFields, 2005)
Direct contact of birds with mineral processing wastes in inactive tailings impoundments
(Phelps Dodge, 2005).
3.3.6 2009 Current Sites: Potential Ecological Exposure Pathways and Routes
Aquatic organisms inhabiting surface waterbodies down-stream from a 2009 Current site
could be exposed to CERCLA hazardous substances through direct contact with contaminated
surface water or sediment. Birds and terrestrial mammals with habitats that include a 2009
Current site may be exposed through ingestion of contaminated soil or prey, or from direct
contact with mining or mineral processing wastes (such as birds attracted to cyanide-containing
surface impoundments). Plants in the vicinity of a 2009 Current site could also be adversely
affected by CERCLA hazardous substance releases from the site.
The GIS analysis evaluated the potential for federally listed threatened and endangered
species to be exposed to CERCLA hazardous substances from 2009 Current sites with verifiable
locations, when critical habitats for those species are located near the sites.
The GIS analysis illustrates the potential for surface water organisms to be adversely
affected by hazardous substance releases from mining and mineral processing sites, where those
releases impact surface water bodies. For example:
Spatial analysis identified dams within a 24-hour downstream travel distance of 153
(approximately 37%) of the 417 sites with verifiable locations. These dams suggest that
aquatic habitat is present within the stream, and could have beneficial uses for fish and
wildlife.
Approximately 5% of the sites (19 of 417 sites) are adjacent to or upstream of National
Wild and Scenic Rivers that are generally considered outstanding resource waters and
typically provide ecological services.
Terrestrial receptors (e.g., mammals, birds) can be adversely affected by CERCLA
hazardous substance releases from 2009 Current sites, where those releases impact lands that
provide habitat. For example:
Approximately 8% of the sites (32 of 417 sites) are within 3-miles of lands managed by
the U.S. Fish and Wildlife Service (U.S. FWS) and characterized by FWS as Approved;
also, 3% of the sites (13 of 417 sites) are located within 3 miles of U.S. FWS Interest
Areas that are also managed by the FWS. Some of these U.S. FWS lands may be
maintained or managed as habitat.
39
-------
9/23/2016
Over half of the sites (230 of 417 sites) are located on, adjacent to, or within a 24-hour
travel distance upstream from Federal Lands. Federally owned and managed public lands
include National Parks, National Forests, and National Wildlife Refuges.
Approximately 70% of the sites (294 of 417 sites) are within, adjacent to, or within a 24-
hour travel distance upstream of lands designated as protected areas. These "protected
areas" are lands dedicated to the preservation of biological diversity and to other natural,
recreation, and cultural uses and managed for these purposes through legal or other
effective means.
Approximately 6% of the sites (24 of 417 sites) are within 3 miles of areas that are
designated as critical habitat.
40
-------
9/23/2016
4.0 Discussion of Findings
The objective of this section is to integrate the information on known and potential
exposures discussed in the exposure analysis (Section 3.0), with known toxicity information for
the COCs and risks from Superfund risk assessments, into an evaluation of the current and
possible future human health and ecological impacts associated with CERCLA hazardous
substance releases at 2009 Current sites.
The paucity of available Superfund risk assessments of the 2009 Current sites led EPA to
compare CERCLA hazardous substance release, human and ecological receptor, and exposure
information from 2009 Current sites to similar information collected during assessments of Case
Study Historical sites. This report therefore presents information for both Case Study Historical
and 2009 Current sites.
Section 4.1 presents an overview of Superfund risk assessment methodology. Section 4.2
summarizes the results of data collection from CERCLA site documents for the Case Study
Historical sites, and Section 4.3 summarizes the data collection results for the 2009 Current sites.
Section 4.4 compares the information about the CERCLA hazardous substances and exposure
potential associated with Case Study Historical and 2009 Current sites. Section 4.5 discusses
information from other data sources (e.g., ATSDR Public Health Assessments) regarding Case
study Historical sites and 2009 Current sites. Section 4.6 discusses the uncertainties inherent in
this report. Section 4.7 summarizes the results. Lastly, Section 4.8 presents the findings of this
report, taking into account both the comparison results and the uncertainties.
4.1 Overview of Superfund Risk Assessment
Superfund risk assessments are site-specific and therefore may vary in both detail and the
extent to which qualitative and quantitative analyses are used. As EPA (1989a) describes in
detail, there are four steps in the Superfund baseline risk assessment process: data collection and
analysis; exposure assessment; toxicity assessment; and risk characterization.
Data collection and evaluation (also known as hazard identification) involves gathering
and analyzing the site data relevant to the human health or ecological evaluation and identifying
the CERCLA hazardous substances present at the site that are the focus of the risk assessment
process.
The exposure assessment estimates the magnitude of current and possible future human
or ecological exposures, the frequency and duration of those exposures, and the pathways by
which human or ecological receptors are exposed. The exposure assessment estimates reasonable
maximum exposures for both current and possible future land-uses. Estimates of current
exposures are used to determine whether a threat exists based on existing site conditions.
Estimates of future exposures provide decision-makers with an understanding of potential future
exposures and threats and include a qualitative estimate of the likelihood of such exposures
occurring.
The toxicity assessment considers: (1) the types of adverse health effects associated with
exposure to the CERCLA hazardous substances identified during hazard identification; (2) the
relationship between magnitude of exposure and adverse effects; and (3) related uncertainties
such as the weight of evidence of a particular CERCLA hazardous substance's carcinogenicity in
humans.
41
-------
9/23/2016
In risk characterization, the information from hazard identification, exposure assessment,
and toxicity assessment are summarized and integrated into quantitative and qualitative
expressions of risk. To estimate potential noncarcinogenic effects, intakes of CERCLA
hazardous substances are compared to toxicity values; to estimate potential carcinogenic effects,
probabilities that an individual will develop cancer over a lifetime of exposure are determined
from intakes and chemical-specific dose-response information. Major assumptions, scientific
judgments, and to the extent possible, estimates of the uncertainties embodied in the assessment
are also presented.
Superfund ecological risk assessments use various parameters (e.g., area use, food
ingestion rates, bioaccumulation rates, bioavailability, life-stage, body weight, and dietary
composition) to estimate the exposure of plant or animal receptors to a CERCLA hazardous
substance. Estimation of risk involves the calculation of hazard quotients (the ratio of chemical
contaminant concentration to a selected screening benchmark).7
4.2 Case Study Historical Site Data Collection Results
EPA compiled data for the Case Study Historical sites from Superfund risk assessments
and other CERCLA site documents (e.g., remedial investigations (RIs) and feasibility studies
(FSs), and records of decision (RODs)). The information was used to characterize exposures of
human and ecological receptors to CERCLA hazardous substance releases from Case Study
Historical mining and mineral processing operations. EPA identified CERCLA hazardous
substances, contaminated media, and exposure pathways that contributed to the human health
and ecological risks associated with these activities in the Superfund risk assessments and other
CERCLA site documents.
EPA compiled human cancer and noncancer risks and ecological hazards from Superfund
risk assessments of Case Study Historical sites (see Section 2, Table 2-1). Further review of the
risk estimates was conducted for those CERCLA hazardous substances most frequently
identified as contaminants of concern (COCs) at Case Study Historical sites.
4.2.1 Human Health
EPA's experience with cleaning up the Case Study Historical sites reveals certain
consistencies in CERCLA hazardous substance releases, complete exposure pathways and
receptor types, and estimated risks that are at or above levels of concern in Superfund risk
assessments.
In-depth review of the Case Study Historical sites identified a consistent pattern in the
COCs found to pose human health risks of concern (i.e., >lE-06 cancer risk or >1 HQ) in
Superfund risk assessments. In descending order of frequency, these Priority COCs for human
health risks of concern include arsenic, manganese, cadmium, zinc, and antimony. The releases
generally occur in a pattern of three broad categories: either as air emissions from smelters or
other processing activities, as contamination of surface waters from acidic mine drainage, or as
contamination from on-site waste disposal practices.
7 See EPA (1997): "Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting
Ecological Risk Assessments," available at http://semspub.epa.gov/work/ll/157941.pdf
42
-------
9/23/2016
Complete site-specific exposure pathways in Superfund risk assessments are more
variable across sites, possibly reflecting the range of different mining and mineral processing
techniques used at the Case Study Historical sites. The exposure scenarios that present the
greatest number of exposure routes are the on-site resident (evaluated at 22 sites), the current and
future outdoor worker (occupational worker - evaluated at 14 sites), and the trespasser. For the
on-site resident, the exposure routes that most often lead to risks exceeding benchmarks in
Superfund risk assessments include ingestion (which exceeded at 21 of the 22 sites that evaluated
residential exposures) and inhalation (which exceeded at 14 of the 22 sites). The media through
which residential exposures most often exceeded benchmarks are groundwater (exceeded at 18
out of 22 sites) and soil (exceeded at 9 out of 22 sites). Similarly, the occupational worker is
most commonly exposed to contamination via the ingestion route (14 out of 14 sites) and
through groundwater (8 out of 14 sites). The on-site resident is of particular concern because of
the potential presence of children and elderly, who may be more susceptible to the effects of
hazardous substances.
Reported major sources of uncertainty in Superfund risk assessments of Case Study
Historical sites include future land use patterns, uncertainties about the toxicity assessments of
COCs, limited data on contamination levels at some sites, and lack of overall knowledge of
specific human behaviors that affect the magnitude of exposures and resulting risks.
Uncertainties are discussed further in Section 4.7.
4.2.2 Ecological Impacts
EPA identifies any federally listed threatened or endangered species with critical habitat
in the vicinity of Superfund sites (in order to ensure that the selection of a cleanup strategy does
not adversely affect federally protected species) (U.S. EPA, 1989b). EPA conducts these
threatened/endangered species identifications at all CERCLA cleanup sites. EPA found that there
were federally designated threatened or endangered species at most of the Case Study Historical
sites. The federally designated threatened and endangered species found most often were
mammals and birds.
Screening level, or in some cases in-depth, ecological risk assessments have also been
conducted at many sites. The COCs found most frequently to cause ecological risks of concern in
Superfund risk assessments of the Case Study Historical sites follow a pattern that is similar to
those that cause human health risks of concern. This overlapping but slightly different set of
metals reflects differences in toxicity between humans and other organisms. These Priority
COCs for ecological risks of concern include lead, zinc, arsenic, cadmium, and copper. Of these,
lead, arsenic, and cadmium (in descending order of frequency) are also Priority COCs for human
health risks.
The sources of Priority COCs for ecological exposures are frequently acidic mine
drainage and on-site waste disposal practices. Complete exposure pathways for ecological
receptors generally do not include the ground water pathway (except in cases where groundwater
intersects with surface waters), but include direct contact with contaminated surface waters,
sediments, soils, and food (prey) items.
The Superfund ecological risk assessments found high exposures of birds and raccoons -
orders of magnitude higher than benchmarks - to arsenic, lead, and zinc. For aquatic ecological
43
-------
9/23/2016
receptors, there is no consistent CERCLA hazardous substance responsible for risk estimates
above levels of concern.
Sources of uncertainty in Superfund ecological risk assessments of Case Study Historical
sites include uncertainties regarding the toxicity of substances to species inhabiting the site
(often, data are only available for similar surrogate species, rather than data for the specific
species at the site); uncertainties due to limited data regarding environmental media
concentrations to which ecological receptors might be exposed; and uncertainties due to lack of
knowledge about specific receptor behaviors that could affect exposures and resulting risks.
Overall uncertainties found in Superfund ecological risk assessments of Case Study Historical
sites are discussed further in Section 4.7.
4.3 2009 Current Site Data Collection Results
4.3.1 Human Health
Only a small number of exposure assessments have been performed at 2009 Current sites,
either for nearby residents, workers, or others potentially affected by CERCLA hazardous
substance releases. Exposure assessments performed as part of Superfund risk assessments of
two sites, found complete exposure pathways and corresponding estimated human health risks
that exceeded benchmarks (U.S. EPA 2008), or situations in which "sole use of a site-specific
location over extended periods of time could result in elevated risks" (NewFields, 2005).
The potential for human exposure to CERCLA hazardous substance releases at the 2009
Current sites is associated with a combination of factors. These factors include 1) the quantity of
CERCLA hazardous substances released; 2) the toxicity of the CERCLA hazardous substances;
3) the proximity of people; and 4) the site's environmental conditions or settings. Typically,
these factors must be present to create a situation in which humans might be exposed to one or
more CERCLA hazardous substances at or above a level of concern. Children living on-site
(which has been documented for at least one 2009 Current site) could be exposed at especially
high levels because of behaviors such as playing outside close to the ground, where they would
be likely to ingest soil from their hands, or playing in nearby streams where they may be
potentially exposed to contaminated surface waters through ingestion and dermal contact.
Given the mechanisms of CERCLA hazardous substance releases at 2009 Current sites, it
is possible to identify trends regarding current conditions and the potential for human exposures
of concern:
Sites that are located in areas with a higher population density, that are located in
floodplains, and that release (or could release) highly toxic CERCLA hazardous
substances due either to on-site waste disposal practices or flooding, would have an
increased potential to adversely affect human health.
Sites that are located in areas with a higher population density and that release air
emissions from smelting or other processing activities would have an increased potential
to adversely affect human health.
Sites that are located in areas with a lower population density, that are not located in
floodplains, and that release less toxic CERCLA hazardous substances (or lower
quantities of CERCLA hazardous substances) than other sites, or have other site or
environmental conditions that would tend to mitigate or reduce the possibility of
44
-------
9/23/2016
CERCLA hazardous substance releases, would have a lower potential to adversely affect
human health.
It is also possible to identify trends regarding future conditions and the potential for
future human exposures of concern, although projections regarding future conditions are
inherently more uncertain than known current conditions:
Sites that are located where future residents are likely to settle, that release (or could
release) highly toxic CERCLA hazardous substances due either to on-site waste disposal
practices or flooding, have higher potential to adversely affect human health.
Sites that are located where future residents are likely to settle, and that release air
emissions from smelting or other processing activities, have higher potential to adversely
affect human health.
Sites that are located where future residents are less likely to settle, are not in floodplains,
and would release less toxic CERCLA hazardous substances (or lower quantities of
CERCLA hazardous substances) than other sites, or have other site or environmental
conditions that would tend to minimize or reduce the possibility of CERCLA hazardous
substance releases, would have lower potential to adversely affect human health.
4.3.2 Ecological Impacts
EPA assessed the potential for 2009 Current sites to adversely impact endangered species
by identifying the proximity of each 2009 Current site to designated critical habitat for federally
listed threatened/endangered species. Based on the assumption that site-specific activities could
affect critical habitat located up to 20 miles from the site, 22% of the 2009 Current sites could
adversely impact the habitat of endangered species. Reducing the assumed impact distance to
three miles, 6% of the sites could adversely impact the habitat of endangered species.
The biological surveys or ecological studies of several 2009 Current sites studied
ecosystem health both prior to, and during active mining or mineral processing operations (e.g.,
Kanouse, 2010; Ott and Morris, 2010, NewFields, 2005). Unfortunately, there was insufficient
information available to make general statements regarding potential exposures of ecological
receptors at 2009 Current sites based solely on information from 2009 Current sites. Using
information from the Case Study Historical sites, it is reasonable to expect that acidic mine
drainage problems might pose morbidity and mortality threats to aquatic organisms in surface
water bodies downgradient from 2009 Current sites with sulfide-bearing host rock or
overburden, and at which CERCLA hazardous substances are released. It is also reasonable to
expect that 2009 Current sites with soil, sediment, and surface water contamination patterns that
are similar to those observed at Case Study Historical sites could present similar exposures to
ecological receptors. At some of the 2009 Current sites, investigators have found CERCLA
hazardous substance releases that have, or likely have, adversely impacted ecological receptors
(e.g., NewFields, 2005; U.S. FWS, 2003). This suggests that some of the CERCLA hazardous
substance releases and resulting environmental contaminations at 2009 Current sites are the same
as those found at the Case Study Historical sites.
In addition to the evidence from the Case Study Historical sites, several studies published
in the English-language peer-reviewed scientific literature provide evidence of ecological effects
from CERCLA hazardous substance releases from mining and mineral processing activities (e.g.,
Park et al., 2011; Peplow and Edmonds, 2005).
45
-------
9/23/2016
4.4 Comparisons of Data from Historical and 2009 Current Sites
4.4.1 Overview
Quantitative human health and ecological risk estimates from Superfund risk assessments
of the Case Study Historical sites are highly variable and site-specific. Certain COCs released at
the Case Study Historical sites drive the risk estimates; primarily several common metals,
radionuclides, and two categories of organic compounds. Human receptors are typically site
workers, nearby residents, and site trespassers. Ecological receptors are typically flora and fauna
that inhabit the sites. The COCs migrate through the environment in specific ways and come into
contact with, or potentially come into contact with, receptors via specific exposure pathways:
soil and food plant contamination that affects nearby residents, ground water contamination that
affects water supply wells, surface water contamination that causes fish kills or otherwise
adversely affects aquatic organisms, and contamination of soil and prey that affects birds and
mammals inhabiting the sites.
Evidence collected from analysis of EPA databases show many 2009 Current sites release
CERCLA hazardous substances to the air and to surface waterbodies, and are located near both
human and ecological receptors that could be affected by those releases. Examples of CERCLA
hazardous substances frequently reported as released are lead and manganese; examples of
nearby receptors are humans who drink water obtained from surface water bodies downstream
from the 2009 Current site, or an endangered species with critical habitat near the 2009 Current
site.
Taken together, the data on CERCLA hazardous substances, environmental settings,
potential receptors and exposure pathways suggest the following potential exposures of human
and ecological receptors at 2009 Current sites, which represent the mining and mineral
processing sites that could be regulated under CERCLA 108(b):
The Priority COCs, and their sources, found at Case Study Historical sites are also
present at the 2009 Current sites; therefore, the Priority COCs identified at Case
Study Historical sites can be considered at least contaminants of potential concern
(COPCs) at 2009 Current sites (and by extension, at future sites).
Human and ecological receptors at Case Study Historical sites have parallel potential
receptors at 2009 Current sites.
Environmental settings and exposure pathways at Case Study Historical sites
correspond to environmental settings and potential exposure pathways at some 2009
Current sites.
These correlations suggest that the exposures at Case Study Historical sites are similar to
the potential exposures at 2009 Current sites (and thus, current and future sites). Therefore, risks
estimated in Superfund risk assessments of Case Study Historical sites may be relevant for
current or future releases of CERCLA hazardous substances at the 2009 Current sites that have
similar environmental settings, COCs, receptors and exposure pathways.
4.4.2 Similar CERCLA Hazardous Substances are Present
Table 4-2 illustrates the identification of Priority COCs at the Case Study Historical sites
that are also released at 2009 Current sites (from TRI, DMR, and NEI data sets; see Appendix F
46
-------
9/23/2016
for further discussion of the NEI data extraction and analysis, which was not described earlier in
this report due to the limited information obtained from NEI. Please note that the NEI data set
was limited to sites reporting Priority COC releases exceeding 10 tons annually.)
Table 4-2. Priority COCs Identified at Case Study Historical and 2009 Current Sites
CASRN
Priority COCs Identified at Case Study
Historical Sites
2009 Current Site Data
TRI
DMR
NEI
7440-36-0
Antimony and compounds
7440-38-2
Arsenic and compounds
56-55-3
Benz[a]anthracene
50-32-8
Benzo[a]pyrene
205-99-2
Benzo[b]fluoranthene
7440-41-7
Beryllium and compounds
7440-43-9
Cadmium and compounds
7440-47-3
Chromium and compounds
7440-48-4
Cobalt compounds
7440-50-8
Copper and compounds
53-70-3
Dibenz[a,h]anthracene
7782-41-4
Fluorine (as fluoride)
7439-92-1
Lead and compounds
14255-04-0
Lead-210
7439-96-5
Manganese and compounds
7439-97-6
Mercury and compounds
7440-02-0
Nickel and compounds
1336-36-3
Polychlorinated biphenyls
NA
Radionuclides
13982-63-3
Radium-226
14859-67-7
Radon-222
7782-49-2
Selenium and compounds
7440-22-4
Silver and compounds
7440-28-0
Thallium and compounds
14274-82-9
Thorium-228
7440-61-1
Uranium-238
7440-66-6
Zinc and compounds
4.4.3 Similar Exposure Pathways
Based on the information presented in Section 3.0 ("Exposure Analysis"), for 2009
Current sites that have undergone an exposure assessment, many of the human and ecological
exposures taking place at 2009 Current sites are similar to those that have been documented at
Case Study Historical sites. For example, the contamination of nearby residential areas from
high-temperature smelting operations at the East Helena and Omaha Lead Case Study Historical
47
-------
9/23/2016
sites are mirrored in contamination of nearby residential areas documented at the Herculaneum
lead smelter 2009 Current site, and the Hayden, Arizona copper smelter 2009 Current site.
The current operating practices at 2009 Current sites may be similar or identical to those
that took place under previous owners or operators. Certain waste management practices may be
technically difficult to change, such as the placement of a series of gravity-flow wastewater
treatment ponds relative to nearby surface water. To the extent that these practices are similar to
Case Study Historical sites' practices, and other variables are also similar (e.g., proximity of
receptors, CERCLA hazardous substances released), human or ecological exposures could be
expected to occur at 2009 Current sites that are similar to those that have occurred at Case Study
Historical sites.
Therefore, some 2009 Current sites may cause similar exposures to similar receptors, as
Case Study Historical sites. Unless specific site variables that affect CERCLA hazardous
substance release, movement, and transport toward receptors are fundamentally different, or
there are changes in the way that receptors behave, exposures will continue to be similar to those
found at Case Study Historical sites. Potentially contaminated media will continue to include air,
surface water, groundwater, sediment, and soil; potential routes of exposure will continue to
include dermal, inhalation, and ingestion. However, as mining and mineral processing
technologies change, and regulations cause practices to change, those changes may also affect
exposure potential at 2009 Current sites.
4.5 Other Analyses
4.5.1 Public Health Hazards
The federal Agency for Toxic Substances and Disease Registry (ATSDR) is tasked with
evaluating each NPL site for public health hazards, in a public health assessment (PHA) process
that is mandated by CERCLA Section 104(i)(6)(A). In addition, CERCLA Section 104(i)(4)
authorizes ATSDR to perform Health Consultations (HCs) to provide advice on public health
issues related to actual or potential human exposure to a toxic material, regardless of site status
(i.e., from sites that might not be proposed for the NPL). Thus, ATSDR may investigate
CERCLA removal sites, enforcement cleanup sites, or sites that are not CERCLA cleanup sites
but simply are of concern to a community.
Within the overall PHA and HC process, ATSDR has established five distinct descriptive
conclusion categories to help ensure a consistent approach in drawing conclusions across sites.8
These five categories are:
1) Urgent Public Health Hazard: The site has certain physical hazards or evidence of
short-term (less than 1 year), site-related exposure to hazardous substances that could
result in adverse health effects and require quick intervention to stop people from
being exposed.
2) Public Health Hazard: The site has certain physical hazards or evidence of chronic
(more than 1 year), site-related exposure to hazardous substances that could result in
adverse health effects.
8 SOURCE: ATSDR Public Health Assessment Guidance Manual, Table 9-1 ("Summary of Conclusion
Categories"), available at http://www.atsdr.cdc.gov/HAC/PHAManual/ch9.html.
48
-------
9/23/2016
3) Indeterminate Public Health Hazard: critical information is lacking (missing or has
not yet been gathered) to support a judgment regarding the level of public health
hazard.
4) No Apparent Public Health Hazard: Exposure to site-related chemicals might have
occurred in the past or is still occurring, but the exposures are not at levels likely to
cause adverse health effects.
5) No Public Health Hazard: No exposure to site-related hazardous substances exists.
Known Public Health Hazards from Historical Sites
EPA queried ATSDR databases for information on any sites in the 108(b) Historical
CERCLA Sites universe, and then reviewed the PHAs and HCs conducted at the Case Study
Historical sites. ATSDR categorized 16 of the sites (i.e., 67%) as Public Health Hazards. There
was insufficient information to draw conclusions for six sites (i.e., 25%), which ATSDR
therefore categorized as Indeterminate Public Health Hazards. One site was categorized as No
Apparent Public Health Hazard; and a PHA was performed at one site, but as of this report EPA
and ATSDR have not yet released the information. Appendix M contains more detailed
information on the PHAs and HCs conducted at sites in the 108(b) Historical CERCLA Sites
universe.
Known and Potential Public Health Hazards from 2009 Current Sites
Some of the 2009 Current sites are also NPL sites for which ATSDR performed a PHA.
At these sites, ATSDR found at least one at which human exposures to hazardous substances are
occurring (i.e., the Herculaneum Lead Smelter site (ATSDR, 2005)), and at least three at which
ATSDR has determined that a public health hazard exists, or may exist (i.e., Smokey Canyon
Mine (ATSDR, 2003); the Southeast Idaho Phosphate Mining Resource Area (ATSDR, 2006);
and the Elkem Eramet mine site (ATSDR, 2009)). Appendix A contains more information on
the PHAs and HCs conducted at 2009 Current sites.
4.5.2 Documented Human Health Impacts in Other Countries
In an attempt to look more broadly for relevant data, EPA searched the English language
peer-reviewed literature for studies of human health and ecological adverse effects from mining
and mineral processing sites in other countries. We identified studies of sites in China, Korea,
Norway, Mexico and Slovakia, as well as examples of low-probability, high-consequence
releases of CERCLA hazardous substances from mining and mineral processing sites in Hungary
and China.
Rapant et al. (2009) conducted a human biomonitoring study of residents in a heavily
contaminated mining area in Slovakia, in which they compared selected residents' hair, nail,
blood and urinary levels of arsenic and antimony (both identified as 108(b) Priority COCs).
Epidemiological data, though not age-adjusted, indicated a substantially elevated crude death
rate, cardiovascular disease mortality, and neoplasm mortality for members of both genders
living in the mining area, compared to Slovakian residents overall. In Mexico, Moreno, et al.
(2010) documented elevated blood and urinary levels of several metals identified as 108(b)
Priority COCs in children living near a mining area, including some exposures above reference
levels. In Korea and China, researchers investigating contamination of food crops have
49
-------
9/23/2016
documented elevated levels of some metals that are 108(b) Priority COCs in rice, and estimated
health effects for those food consumers (Jung and Thornton, 1997, and Park et al., 2011). In
Norway, researchers have documented adverse health effects in a population of birds living near
a mining and mineral processing site (Berglund et al., 2010). Unfortunately, these international
studies include insufficient information to fully compare the mining and mineral processing
practices in these countries, to the practices in the United States. It is also unclear to what extent
behavioral differences between U.S., Korean, Chinese, Mexican, and Slovakian populations
could affect the relevance of these studies' results to the United States.
Human health effects of low-probability, high-consequence releases of CERCLA
hazardous substances from mining and mineral processing sites have been documented. The
2010 bauxite processing "red mud" tailings impoundment failure in Kolontar, Hungary, resulted
in initial fatalities due to the flood, but also may have caused exposures to 108(b) Priority COCs.
Researchers who studied a 1985 Chinese lead-zinc tailings impoundment failure concluded that
metals levels in food crops contaminated due to the spill exceeded allowable concentrations for
arsenic and cadmium (both considered 108(b) Priority COCs) by factors of 24 and 13,
respectively (Liu et al., 2005). However, although generally identifying additional potential
catastrophic events with CERCLA hazardous substances, not enough data are available to
translate to current U.S. mining or mineral processing sites.
4.5.3 Ecological Impacts of Acidic Mine Drainage
The potential impacts of acidic mine drainage on aquatic organisms deserves special
consideration, since this form of environmental contamination is prevalent at a number of mining
and mineral processing sites. Acidic mine drainage9 poses two types of potential threats to
aquatic organisms.
First, the pH, or hydrogen ion potential, of the drainage water can be low enough that
contact with the water can cause direct damage to aquatic organisms' tissues, resulting either in
morbidity or mortality. Drainage that remains acidic for a long enough period can kill entire
populations of aquatic organisms, causing a collapse of the aquatic ecosystem and also adversely
affecting the surrounding terrestrial ecosystem.
The second type of potential threat may occur when the pH levels are not low enough to
cause aquatic organism morbidity or mortality directly, but can cause higher concentrations of
dissolved metals in the water than would occur at a more neutral pH range. These higher
concentrations of dissolved metals are toxic to the aquatic organisms, causing morbidity or
mortality. However, because of the way hazardous substances are defined in CERCLA, and the
intersection of that definition with RCRA hazardous waste regulations for mining and mineral
processing sites,10 only the second of the two types of potential threat to aquatic organism is
9 Conversely, alkaline mine drainage can occur, with high pH drainage water. Both types of effects described in the
text for acidic mine drainage could occur due to alkaline mine drainage as well.
10 CERCLA defines hazardous substances at 40 CFR 302.8. If acidic mine drainage were classified as a corrosive
hazardous waste under the RCRA regulations, then the pH of the drainage water could be investigated separately
as a causative agent in aquatic organism morbidity/mortality. Due to a regulatory exemption in the RCRA
hazardous waste regulations (at 40 CFR 261.4(b)(7)), the acidic drainage water is not classified as a RCRA
hazardous waste. Thus, Superfund risk assessments are constrained to consider only those hazardous substances,
pollutants, or contaminants that are present within the acidic mine drainage and surface water bodies at levels
higher than would be expected were the drainage to be a more neutral pH.
50
-------
9/23/2016
typically evaluated in Superfund ecological risk assessments - the potential threat from elevated
levels of metals in the surface water or sediment, due to the lowered pH of the water.
Acidic mine drainage was identified as causing, or contributing to, CERCLA hazardous
substance releases at six of the Case Study Historical sites. At these six sites, only one had
quantified impacts on aquatic organisms that were above the level of concern. At the remaining
five sites, impacts on aquatic organisms either were not quantified, or were not definitively
attributable to the acidic mine drainage.
4.5.4 Impacts from Low-Probability, High-Consequence Events
Although beyond the scope of the exposures and receptors considered in this report, the
potential for CERCLA hazardous substance releases due to low-probability, high-consequence
events exists at sites with engineered structures designed to hold accumulations of liquid wastes
(i.e., impoundments, also sometimes called ponds, pits or lagoons) or accumulations of solid
mining or mineral processing materials. Examples of low-probability, high-consequence events
include extreme flooding situations, seismic events of sufficient magnitude to cause CERCLA
hazardous substance releases from engineered structures, fires and explosions, or a wide variety
of unanticipated human-caused events that increase in probability as human activities encroach
onto nearby land. Some sites in the 108(b) Historical CERCLA Sites universe have become
cleanup sites in the aftermath of such low-probability, high-consequence events; for example,
Flat Creek/Iron Mountain Mine in Montana (USEPA, 201 Id), or the Unimin Mine Fire site in
North Carolina (USEPA, 2008).
4.6 Uncertainty in This Report
This report presents a general discussion of the potential for human and ecological
exposures to CERCLA hazardous substance releases from 2009 Current sites, representing
mining and mineral processing activities occurring in the United States. The report uses data
from Superfund risk assessments (and other CERCLA site documents) of U.S. mining and
mineral processing sites, as well as data from two federal agencies that monitor the activities at
2009 Current sites, EPA data regarding CERCLA hazardous substances present at 2009 Current
sites, and data from several other publicly available sources. At a limited number of 2009
Current sites, environmental samples and surveys and health studies have been performed that
provide direct evidence of the presence and release of CERCLA hazardous substances to
environmental media, concentrations of those CERCLA hazardous substances in environmental
biota and, sometimes, in humans, that can be attributed to exposures from the mining and
mineral processing activities. This report also uses information from studies published in the
scientific literature that were performed at mining and mineral processing sites outside of the
U.S.
4.6.1 Time Interval Assumptions
One source of uncertainty in this report results from using data for calendar year 2009 to
represent mining and mineral processing sites that were active in years both prior and subsequent
to 2009. As economic conditions and legislative policies change, and as technological
improvements occur within the industry, changes in mining and mineral processing practices can
be expected to occur. Thus, the data presented in this report should be considered the best public
data available at the time the analysis took place, to reflect potential human and ecological
51
-------
9/23/2016
exposures to CERCLA hazardous substance releases from the mines and mineral processors that
may be required to comply with the CERCLA 108(b) financial assurance requirements.
4.6.2 Data Gaps for 2009 Current Sites
Although substantial amounts of data are available on many of the factors influencing
human and ecological exposures, direct evidence of exposures of either human or ecological
receptors to CERCLA hazardous substances, with corresponding evidence of adverse effects, is
available for only a few 2009 Current sites. This data gap constitutes the largest source of
uncertainty in the overall comparison to the Case Study Historical sites. EPA has attempted to
bridge this data gap by compiling information on potential receptor proximities, and thus,
potential exposures.
4.6.3 Mine and Processor Site Locations
A source of uncertainty in the newly compiled information on potential receptor
proximities is the uncertainty regarding the accuracy of the 2009 Current site locations. The
MSHA database did not include latitude/longitude coordinates for the actual mining or mineral
processing sites; therefore, sites from that database could not be geographically mapped using
data from MSHA. EPA used several approaches to identify the location of each mine and
mineral processor, including geocoding of the location based on address, followed by detailed,
manual investigation of each address using high-quality aerial imagery. In general, the mine site
locations are likely to be less certain than the mineral processor locations. Inaccuracies in the site
locations could have a significant impact on various geospatial analyses performed using the
locations. Inaccuracies in these locations would have a direct bearing on the accuracy of any
conclusions that EPA might draw regarding proximity, and resulting exposure, of human and
ecological receptors. Appendix E contains a detailed accounting of the uncertainties involved
when using the results from the GIS analysis. It also explains uncertainties associated with using
the data on 100-year flood areas, critical habitat of federally listed threatened/endangered
species, stretches of surface water bodies that are classified as impaired waters, and drinking
water supply areas.
4.6.4 Identifying COCs
The detailed review of available documentation for the Case Study Historical sites
attempted to identify all CERCLA hazardous substances that were designated as COCs in
Superfund risk assessments. However, the search sometimes did not locate documentation for all
the operable units at a site. It is therefore possible, though not highly likely, that some CERCLA
hazardous substances designated as COCs were not identified for this report. Furthermore, the
use of a subset of sites to represent the entire population of sites creates the uncertainty that some
factors, including identifying individual COCs, may be missing from the sample population.
However, because similar COCs were identified across the Case Study Historical sites, the
exclusion of a COC from this analysis is not highly likely.
4.6.5 Identifying Receptor Locations
The locations and number of potential human receptors near 2009 Current sites were
estimated using 2000 Census data (including census geographic boundaries). Also, source water
52
-------
9/23/2016
protection areas (SPAs) were used to estimate presence of drinking water intakes downstream of
2009 Current sites.
Uncertainty about the accuracy of the Census data stems from the age of these data
sources and because Census findings are largely based on sampled data (specifically, the Census
long form data, which is a sample of 1 in 6 households). Sample surveys have uncertainty
associated with the size of the sample and some built-in inaccuracies that are created to decrease
the chance of identifying individuals from Census data.
SPAs are polygons that were created as approximate areas of drinking water sources. For
security reasons, actual drinking water source locations are not available, and SPAs were
developed as proxies for actual locations. Using SPAs to estimate the presence or absence of
drinking water intakes has considerable uncertainty because an SPA polygon may intersect with
a 2009 Current site downstream area, but the actual drinking water intake location (within the
SPA) may fall outside of the 2009 Current site downstream area.
Sources of ecological receptor locations have considerable uncertainty because few
ecological area boundaries have been accurately mapped. Sources such as boundaries of national
parks or boundaries of land that the U.S. Fish and Wildlife Service owns, manages, or may
acquire are probably more accurate than some boundaries that represent critical habitats for
threatened and endangered species. Uncertainty in the quality and accuracy of the boundaries of
the national sources used to represent ecological receptor locations will affect the accuracy of the
results of any spatial analysis.
4.6.6 Estimating Exposures
Some uncertainties are inherent in the spatial methods used to estimate exposure of
human and ecological receptors.
To estimate human populations within given distances of 2009 Current sites, an area
apportionment method was used to estimate the number of persons in Census polygons that fall
within a "buffer" polygon (a polygon drawn around the point of interest) based on the proportion
of the Census polygon that fits inside vs. outside the buffer polygon (see Figure 4-1). This
method implicitly assumes that population is evenly distributed within each Census polygon.
This (necessary) assumption leads to some uncertainty in the estimates of population and
population characteristics. In addition, because the 2009 Current sites are represented as points in
the GIS, a buffer zone created around the point is likely not to properly estimate the true area
within a particular distance of the edge of the mine or processor.
53
-------
9/23/2016
Figure 4-1. Example of a five-mile buffer zone intersected with Census block group boundaries,
illustrating how block group areas are split by the buffer zone.
The process for estimating aquatic ecological receptors used National Hydrography
Dataset polygon "catchments" to estimate downstream travel from each 2009 Current site.
Catchment polygons represent the very small river basins surrounding each river reach.
However, these catchments are approximations of actual basins, and therefore, the area
encompassed by the downstream travel could over- or underestimate the true area that "catches"
the surface runoff from the land surface. When ecologi cally sensitive boundaries (such as critical
habitats) are overlaid on the downstream catchment areas, some intersections may exist in the
computerized simulation that do not exist in reality, thus leading to over- or underestimation of
the presence of ecological receptors within the catchment areas.
4.7 Summary of Findings Regarding the Potential for Human Health
and Ecological Impacts from 2009 Current Sites
The following summarizes the findings from the analyses described above to support the
potential for risks resulting from human and ecological receptor exposure to CERCLA hazardous
substance releases from 2009 Current sites, and by extension, all current and future sites.
Human Health
Superfund risk assessments of the Case Study Historical sites demonstrate consistencies
in CERCLA hazardous substance releases, complete exposure pathways and receptor
types, and risk estimates that exceed levels of concern. As discussed in Section 4.4.3,
2009 Current sites demonstrate the potential for similar complete exposure pathways to
the same receptor types.
Superfund risk assessments of the Case Study Historical sites reveal a consistent pattern
in the COCs most often found to pose risks of concern (i.e., antimony, arsenic, cadmium,
54
-------
9/23/2016
manganese, and zinc). Many of these Priority COCs are also released from 2009 Current
sites.
Ecological Impacts
Superfund risk assessments of the Case Study Historical sites report a pattern of risks to
federally designated threatened or endangered species.
In Superfund risk assessments of Case Study Historical sites, the Priority COCs for
ecological risks include arsenic, cadmium, copper, lead, zinc, and others. This list is
similar to, but not identical to, the Priority COCs for human health risks, reflecting
differences in toxicity and exposures between humans and other organisms.
Based on the experiences with the Case Study Historical sites, it is reasonable to expect
that acidic mine drainage problems may pose morbidity and mortality threats to aquatic
organisms in surface water bodies downgradient from 2009 Current sites with sulfide-
bearing host rock or overburden, and at which CERCLA hazardous substances are
released.
Based on the experiences with Case Study Historical sites, it is also reasonable to expect
that 2009 Current sites with soil, sediment, and surface water contamination patterns that
are similar to those observed at Case Study Historical sites may present similar potential
risks to ecological receptors at those sites.
4.8 Overall Findings
EPA's findings on known and potential human health and ecological impacts from U.S.
mining and mineral processing sites include:
1. Based on similarities in CERCLA hazardous substances and exposure potential
between Case Study Historical sites and 2009 Current sites, CERCLA hazardous
substance releases from mining and mineral processing sites subject to 108(b)
regulation could potentially lead to human health and ecological risks above levels
of concern. Due to site-specific conditions and considerations at each of the Case Study
Historical sites, Superfund risk assessments quantified human health and ecological risk
estimates exceeding levels of concern varied by five orders of magnitude. The ecological
risk estimates in Superfund risk assessments are more influenced by site-specific
conditions, and are therefore more variable than the human health risk estimates.
Superfund human health and ecological risk estimates are highly site-specific, involving
site-specific conditions and uncertainties: quantifiable exposure and risk estimates from
one site are not designed to be directly applicable to another site. Nevertheless, the
similarities in CERCLA hazardous substances, receptors and potential exposure pathways
suggests that risks exceeding levels of concern from exposure to CERCLA hazardous
substance releases from sites subject to 108(b) regulation would be possible.
2. Based on the experience of the fund, Superfund could continue to be called upon to
address contamination from mining and mineral processing practices not currently
employed by the mines and mineral processors subject to 108(b) regulation.
Superfund is responsible for addressing site contamination regardless of the industrial
practices currently in use at a site. Based on the results of this report, example past
practices include the following:
55
-------
9/23/2016
Some copper high-temperature smelting processors have, in the past, caused
considerable air and soil contamination in surrounding communities or caused
ecological harm (U.S. FWS, 2008; U.S. EPA, 2002a; Phelps Dodge, 2005). An
investigation by the state of New Mexico (New Mexico, 2009), found that similar
contamination is occurring at a high-temperature smelter still operating in the United
States. Recent federal requirements (Clean Air Act Maximum Available Control
Technology regulations) for copper smelting facilities may address ongoing
contamination of this type.
Some copper processing sites using processes other than high-temperature smelting
have, in the past, caused environmental contamination from their waste disposal
practices (e.g., Kennecott South Zone; Cyprus Tohono; Tyrone Mine).
Some lead smelters have, in the past, caused considerable air and soil contamination
in surrounding communities.
Some aluminum smelters have, in the past, caused groundwater contamination from
on-site waste disposal. However, RCRA regulations now control these disposal
practices.
56
-------
9/23/2016
5.0 References
ATSDR (Agency for Toxic Substances and Disease Registry). 2002. Public Health Assessment:
Asarco Hayden Smelter Site (AJKJA Asarco IncorporatedHayden Plant). Agency for Toxic
Substances and Disease Registry, Atlanta, GA, September 30. Retrieved from
http://www.atsdr.cdc. gov/HAC/pha/PHA.asp?docid=905&pg=0
ATSDR (Agency for Toxic Substances and Disease Registry). 2003. Health Consultation:
Selenium in Fish Streams of the Upper Blackfoot River Watershed. Southeast Idaho Selenium
Project: Soda Springs, Caribou County, Idaho. Agency for Toxic Substances and Disease
Registry, Atlanta, GA. Retrieved from
http://www.atsdr.cdc. gov/hac/pha/pha.asp?docid=1052&pg=0
ATSDR (Agency for Toxic Substances and Disease Registry). 2005. Exposure Investigation:
Herculaneum Lead Smelter Site (A/K/A Doe Run Lead Smelter). Agency for Toxic
Substances and Disease Registry, Atlanta, GA. June. Retrieved from
http://www.atsdr.cdc.gov/HAC/pha/HerculaneumLeadSmelterSiteEI08/HerculaneumLeadS
melter-Final060905.pdf
ATSDR (Agency for Toxic Substances and Disease Registry). 2006. Public Health Assessment
for Southeast Idaho Phosphate Mining Resource Area Bannock, Bear Lake, Bingham, and
Caribou Counties, Idaho. Agency for Toxic Substances and Disease Registry, Atlanta, GA.
February. Retrieved from
http://www.atsdr.cdc.gov/HAC/pha/SoutheastIdahoPhosphateMining/SoutheastIdahoPhosph
ateMiningpHA022406.pdf
ATSDR (Agency for Toxic Substances and Disease Registry). 2009. Health Consultation:
Marietta Area Air Investigation, Marietta, Ohio. Agency for Toxic Substances and Disease
Registry, Atlanta, GA. July. Retrieved from
http://www.atsdr.cdc.gOv/HAC/pha/marietta3/ATSDRMariettaHealthConsultationIII2009Fin
al.pdf
ATSDR (Agency for Toxic Substances and Disease Registry). 2011. ToxFAQs: Information
About Contaminants Found at Hazardous Waste Sites. Agency for Toxic Substances and
Disease Registry, Atlanta, GA. March 3. Retrieved from
http://www.atsdr.cdc.gOv/toxfaqs/index.asp#A
Berglund, A.M.M., Ingvarsson, P.K., Danielsson, H., & Nyholm, N.E.I. 2010. Lead exposure
and biological effects in pied flycatchers (Ficedula hypoleuca) before and after the closure of
a lead mine in northern Sweden. Environmental Pollution 158:1368-1375. Retrieved from
http ://www. sciencedirect.com/science/article/pii/S0269749110000217
BLM, USD A, and ID DEQ. 2007. Final Environmental Impact Statement Smoky Canyon Mine,
Panels F & G: Appendix 2A, Smoky Canyon Mine CERCLA Investigations and Response:
Smoky Canyon Mine, Idaho. Department of the Interior, Bureau of Land Management; U.S.
Department of Agriculture, Forest Service; and Idaho Department of Environmental Quality.
November. Retrieved from https://eplanning.blm.gov/epl-front-
office/proiects/nepa/36682/56077/60768/SCM F&G Mod FEIS.pdf.
57
-------
9/23/2016
Colorado DPHE (Department of Public Health and Environment). 2008. Final Captain Jack
Superfund Site Remedial Investigation and Risk Assessment Report, Vol. 1. Prepared by
Walsh Environmental Scientists and Engineers, Boulder, CO, for Colorado Department of
Public Health and Environment, Denver, CO. May 22. Available at
https://semspub.epa.gov/work/Q8/1071946.pdf
Gil, F., Capitan-Vallvey, L., De Santiago, E., Ballesta, J., Pla, A., Hernandez, A., Gutierrez-
Bedmar, M., Fernandez-Crehuet, J., Gomez, J., Lopez-Guarnido, O., Rodrigo, L., Villanueva,
E. 2006. Heavy metal concentrations in the general population of Andalusia, South of Spain
A comparison with the population within the area of influence of Aznalcollar mine spill (SW
Spain). Science of the Total Environment 372 A9-51. Retrieved from
http://www.sciencedirect.com/science/article/pii/S00489697060Q622X
Golder and Associates. 2005. Wildlife Monitoring Plan for Post Closure - Tyrone Mine. Golder
and Associates, Inc., Albuquerque, NM. December 28. Retrieved from
http://www.emnrd.state.nm.us/MMD/MARP/permits/documents/GR010RE 20071011 Clos
eout Plan Update AppendixE Section9.N.3 Wildlife Monitoring Plan.pdf
Jung, M.C., & Thornton, I. 1997. Environmental contamination and seasonal variation of metals
in soils, plants and waters in the paddy fields around a Pb-Zn mine in Korea. The Science of
the Total Environment 795:105-121. Retrieved from
http://www.sciencedirect.com/science/article/pii/S0048969797Q5434X
Kanouse, K. M. 2011. Aquatic Biomonitoring at Greens Creek Mine, 2010. Technical Report No.
11-02. Alaska Department of Fish and Game, Department of Habitat, Juneau, AK. May.
Retrieved from http://dnr.alaska.gov/mlw/mining/largemine/greenscreek/pdf/gc2010bio.pdf
Liu, H., Probst, A., & Liao, B. 2005. Metal contamination of soils and crops affected by the
Chenzhou lead/zinc mine spill (Hunan, China). The Science of the Total Environment
339:153-166. Retrieved from
http://www.sciencedirect.com/science/article/pii/S00489697040Q5789
Moreno, M.E., Acosta-Saavedra, L.C., Meza-Figueroa, D., Vera, E., Cebrian, M.E., Ostrosky-
Wegman, P., & Calderon-Aranda, E.S. 2010. Biomonitoring of metal in children living in a
mine tailings zone in Southern Mexico: A pilot study. International Journal of Hygiene and
Public Health 273:252-258. Retrieved from
http://www.sciencedirect.com/science/article/pii/S143846391000Q398
Nanda, P., B.N. Panda, and M.K. Behera 2000. Nickel Induced Alterations in Protein Level of
Some Tissues of Heteropneustes fossilis. Journal of Environmental Biology 21(2)\ 117-119.
NewFields, 2005. NewFields. Final Site Investigation Report Smoky Canyon Mine, Caribou
County, Idaho. NewFields, Boulder, CO. July. Retrieved from
http ://www. smokycanyonmine. com/scm/dei s .html
NOAA (National Oceanic and Atmospheric Administration). 2008. Screening Quick Reference
Tables. National Oceanic and Atmospheric Administration, Office of Response and
Restoration, Silver Spring, MD. November 13. Retrieved from
http://response.restoration.noaa.gov/sites/default/files/SQuiRTs.pdf
Oklahoma DEQ (Department of Environmental Quality). 2008. Eagle Richer Technologies LLC
Quapaw Oklahoma Post-Closure Permit for the Maintenance of a Closed Hazardous Waste
58
-------
9/23/2016
Management Unit. Oklahoma Department of Environmental Quality, Oklahoma City, OK.
May. Retrieved from
http://www.deq.state.ok.us/apps/nondiv/permitspublic/storedpermits/1212.pdf
Ott, A., and Morris, W. 2010. Aquatic Biomonitoring at Red Dog Mine, 2010. Technical Report
11-01. Alaska Department of Fish and Game, Division of Habitat, Juneau, AK. March.
Retrieved from
http://www.adfg.alaska.gov/static/lands/habitatresearch/pdfs/reddog 11 Ol.pdf
Park, B.-Y., Lee, J.-K., Ro, H.-M., & Kim, Y.H. 2011. Effects of heavy metal contamination
from an abandoned mine on nematode community structure as an indicator of soil ecosystem
health. Applied Soil Ecology 57:17-24. Retrieved from
http ://www. sciencedirect.com/science/article/pii/S0929139311001880
Peplow, D., and R. Edmonds. 2005. The effects of mine waste contamination at multiple levels
of biological organization. Ecological Engineering 24: 101-119. Retrieved from
http://www.sciencedirect.com/science/article/pii/S09258574040Q1685
Phelps Dodge, 2005. Form 10K filing with U.S. Securities and Exchange Commission. March 7.
Rapant, S., Cveckova, V., Dietzova, Z., Khun, M., Letkovicova, M. 2009. Medical geochemistry
research in Spissko-Gemerske rudohorie Mts., Slovakia. Environmental Geochemistry and
Health 31:11-25. Retrieved from http://link.springer.eom/article/10.1007/sl0653-008-9152-2
U.S. EPA (Environmental Protection Agency). 1989a. Risk Assessment Guidance for Superfund,
Part A. EPA 540/1-89/002. U.S. Environmental Protection Agency, Office of Emergency and
Remedial Response, Washington, DC. December. Available at http://www.epa.gov/risk/risk-
assessment-guidance-superfund-rags-part.
U.S. EPA (Environmental Protection Agency). 1989b. CERCLA Compliance with Other Laws
Manual. Vol. II. EPA/540/G-89/009. U.S. Environmental Protection Agency, Office of Solid
Waste and Emergency Response, Washington, DC. August. Retrieved from
http://www.epa.gov/superfund/applicable-or-relevant-and-appropriate-requirements-arars.
U.S. EPA (Environmental Protection Agency). 1995a. Identification and Description of Mineral
Processing Sectors and Waste Streams. U.S. Environmental Protection Agency, Office of
Solid Waste, Washington, DC. December. Retrieved from
http://www.epa.gov/oecaerth/assistance/sectors/minerals/processing/technicaldoc.html
U.S. EPA (Environmental Protection Agency). 1997. Ecological Risk Assessment Guidance for
Superfund: Process for Designing and Conducting Ecological Risk Assessments. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response,
Washington, DC. Available at http://semspub.epa.gov/work/ll/157941.pdf.
U.S. EPA (Environmental Protection Agency). 2001. Final Draft Palmer ton Zinc Site Ecological
Risk Assessment. Volume 3: Terrestrial Community Endpoints. U.S. Environmental
Protection Agency, Philadelphia, PA. February.
U.S. EPA (Environmental Protection Agency). 2002. EPA Superfund Record of Decision:
Lincoln Park EPA ID: COD042167858 OU 02 CANON CITY, CO 01/03/2002.
EPA/ROD/R08-02/108. U.S. Environmental Protection Agency, Denver, CO. January.
Retrieved from
59
-------
9/23/2016
http://webappl.dlib.indiana.edu/virtual disk library/index.cgi/2766887/FID764/rods/Region
08/R0800115.pdf
U.S. EPA (Environmental Protection Agency). 2002a. EPA Superfund Record of Decision:
Kennecott (North Zone) EPA ID: UTD070926811 OU 08 MAGNA, UT 09/26/2002.
EPA/ROD/R08-02/6102002. U.S. Environmental Protection Agency, Denver, CO.
September. Retrieved from https://www.regulations.gov/document?D=EPA-HQ-SFUND-
2009-0265-0027
U.S. EPA (Environmental Protection Agency). 2003. Human Health Toxicity Values in
Superfund Risk Assessments. OSWER Directive 9285.7-53. Washington, DC. December.
Retrieved from https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockev=91015CKS.TXT
U.S. EPA (Environmental Protection Agency). 2004. U.S. Environmental Protection Agency
Abandoned Mine Lands Team Reference Notebook. U.S. Environmental Protection Agency,
Washington, DC. September. Retrieved from http://www.epa.gov/aml/tech/amlref.pdf
U.S. EPA (Environmental Protection Agency). 2005a. Midnite Mine Human Health Risk
Assessment Report. U.S. Environmental Protection Agency, Region 10, Seattle, WA.
September. Retrieved at
https://www3.epa.gov/regionl0/pdf/sites/midnite mine/human health risk assessment sept
2005.pdf
U.S. EPA (Environmental Protection Agency). 2005b. Record of Decision: Li Tungsten
Corporation Superfund Site, Operable Unit Four - Glen Cove Creek, City of Glen Cove,
Nassau County, New York. EPA/ROD/R02-05/017. U.S. Environmental Protection Agency,
Region 2, New York, NY. March 30. Retrieved from
https://quicksilver.epa.gov/work/HQ/186239.pdf
U.S. EPA (Environmental Protection Agency). 2005c. Final Report, Midnite Mine Site,
Ecological Risk Assessment, Wellpinit, Washington. Prepared by Lockheed Martin, Edison,
NJ, for U.S. Environmental Protection Agency, Region 10, Seattle, WA. September.
Retrieved from https://semspub.epa.gov/work/10/500010001.pdf
U.S. EPA (Environmental Protection Agency). 2008. Baseline Human Health Risk Assessment
for the ASARCO LLC Hayden Plant Site Hayden, Gila County, Arizona. U.S. Environmental
Protection Agency, Region 9, San Francisco, CA. August. Retrieved from
https://vosemite.epa.gov/r9/sfund/r9sfdocw.nsf/688299b284bl6e92882574260073faef/d7fa3
ef61b27772c882574b8006fl477/$FILE/HHRA%20Rpt-Full%20Text.pdf
U.S. EPA (Environmental Protection Agency). 2009a. Memorandum to: The Record. Mining
Classes Not Included in Identified Hardrock Mining Classes of Facilities. EPA-HQ-SFUND-
2009-0265-0033. U.S. Environmental Protection Agency, Washington, DC. June. Retrieved
from http://www.regulations.gov
U.S. EPA (Environmental Protection Agency). 2009b. Technical Support Document for the
Preliminary 2010 Effluent Guidelines Program Plan. EPA 821-R-09-006. U.S.
Environmental Protection Agency, Office of Water, Washington, DC. October. Retrieved
from
http://water.epa.gov/lawsregs/guidance/cwa/304m/archive/upload/2009 11 17 guide 304m
2010 tsdplan.pdf
60
-------
9/23/2016
U.S. EPA (Environmental Protection Agency). 2011a. Risk Assessment Glossary. U.S.
Environmental Protection Agency, Washington, DC. May 10. Retrieved from
http://www.epa.gov/risk assessment/
U.S. EPA (Environmental Protection Agency). 2011b. Integrated Risk Information System. U.S.
Environmental Protection Agency, Office of Research and Development, Washington, DC.
July 26. Retrieved from http://www.epa.gov/ncea/iris/search kevword.htm
U.S. EPA (Environmental Protection Agency). 201 lc. ECOTOXicology database, Release 4.0.
U.S. Environmental Protection Agency, Office of Research and Development, Washington,
DC. September 30. Retrieved from http://cfpub.epa.gov/ecotox/
U.S. EPA (Environmental Protection Agency). 201 Id. Final Remedial Investigation Report: Flat
Creek/IMMSuperfundSite. U.S. Environmental Protection Agency, Region 8 Superfund,
Helena, Montana. September. Retrieved from
https://www.epa.gov/sites/production/files/documents/FlatCreek RI091511-Text.pdf
U.S. FWS (Fish and Wildlife Service). 2003. Preassessment Screen for the Chino, Tyrone, and
Morenci Mine Sites, Grant County New Mexico andMorenci Arizona. Prepared by Stratus
Consulting, Boulder, CO, for U.S. Fish and Wildlife Service, Albuquerque, NM. June.
Retrieved from http://www.fws.gov/southwest/es/Documents/R2ES/Phelps Dodge Mines-
FINAL PAS.pdf
U. S. FW S (Fish and Wildlife Service). 2008. Final Restoration Plan and Environmental Action
Statement (Rp lias) for the Preservation, Restoration and Management of the Lakepoint
Wetlands Site: Tooele County, Utah. U.S. Fish and Wildlife Services, Salt Lake City, UT.
March. Retrieved from
http://www.fws.gov/utahfieldoffice/Documents/Contaminants/KUCC NR.DA Restoration P
lan FINAL.pdf
USGS (U.S. Geological Survey). 2011. 2009Minerals Yearbook: Statistical Summary [Advance
Release]. U.S. Geological Survey, Reston, VA. August. Retrieved from
http://minerals.usgs.gov/minerals/pubs/commoditv/statistical summary/mvbl-2009-stati.pdf
61
------- |